U.S. patent application number 15/880297 was filed with the patent office on 2018-06-14 for eye imaging apparatus with sequential illumination.
The applicant listed for this patent is VISUNEX MEDICAL SYSTEMS CO. LTD.. Invention is credited to Wei SU.
Application Number | 20180160903 15/880297 |
Document ID | / |
Family ID | 52132619 |
Filed Date | 2018-06-14 |
United States Patent
Application |
20180160903 |
Kind Code |
A1 |
SU; Wei |
June 14, 2018 |
EYE IMAGING APPARATUS WITH SEQUENTIAL ILLUMINATION
Abstract
An eye imaging apparatus can include a housing, an optical
imaging system in the housing, and a light source in the housing to
illuminate an eye. The optical imaging system can include an
optical window at a front end of the housing with a concave front
surface for receiving the eye as well as an imaging lens disposed
rearward the optical window. The apparatus can comprise a light
conditioning element configured to receive light from the light
source and direct said light to the eye. The apparatus can further
include an image sensor in the housing disposed to receive an image
of the eye from the optical imaging system. In various embodiments,
light conditioning element includes at least one multi-segment
surface. In some embodiments, the housing is provided with at least
one hermitic seal, for example, with the optical window. In some
embodiments, time sequential illumination is employed.
Inventors: |
SU; Wei; (Sunnyvale,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
VISUNEX MEDICAL SYSTEMS CO. LTD. |
Grand Cayman |
|
KY |
|
|
Family ID: |
52132619 |
Appl. No.: |
15/880297 |
Filed: |
January 25, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14881070 |
Oct 12, 2015 |
9907468 |
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15880297 |
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14614305 |
Feb 4, 2015 |
9155466 |
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14881070 |
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14191291 |
Feb 26, 2014 |
9351639 |
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14614305 |
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13845069 |
Mar 17, 2013 |
9179840 |
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14191291 |
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61612306 |
Mar 17, 2012 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 3/145 20130101;
A61B 3/158 20130101; A61B 3/0008 20130101; A61B 2560/0475 20130101;
A61B 3/0025 20130101; A61B 5/0013 20130101; A61B 3/14 20130101;
A61B 3/1208 20130101; A61B 3/132 20130101; A61B 3/152 20130101;
A61B 2576/02 20130101; A61B 3/125 20130101 |
International
Class: |
A61B 3/14 20060101
A61B003/14; A61B 3/00 20060101 A61B003/00; A61B 3/125 20060101
A61B003/125; A61B 3/12 20060101 A61B003/12; A61B 3/15 20060101
A61B003/15; A61B 5/00 20060101 A61B005/00; A61B 3/13 20060101
A61B003/13 |
Claims
1. A method of operation of an eye imaging apparatus, the method
comprising: emitting light through an optical window to illuminate
different portions of an eye by a plurality of light emitting
elements within the eye imaging apparatus, the optical window being
configured to be in contact with a cornea of the eye; varying an
intensity of the emitted light from each of the plurality of light
emitting elements; and receiving a plurality of images of the eye
formed by reflected light of the emitted light with a same field of
view by an image sensor within the eye imaging apparatus.
2. The method in claim 1, wherein varying an intensity of the
emitted light comprises activating each of the plurality of light
emitting elements time-sequentially.
3. The method in claim 1, further comprising directionally
controlling the emitted light by a light conditioning element
within the eye imaging apparatus, the light conditioning element
comprising at least one multi-segment surface.
4. The method in claim 3, wherein a plurality of sections of the
light conditioning element are separated by a plurality of
barriers, each of the plurality of barriers extending in a radial
direction.
5. The method in claim 3, wherein the emitted light from the
plurality of light emitting elements are transmitted directly to
the light conditioning element.
6. The method in claim 3, wherein the emitted light are transmitted
from the plurality of light emitting elements to optical fiber
bundles, and further transmitted from the optical fiber bundles to
the light conditioning element.
7. The method in claim 1, further comprising processing the
plurality of images to create a composite image of the eye.
8. The method in claim 7, wherein processing the plurality of
images comprises aligning the plurality of images.
9. The method in claim 7, wherein processing the plurality of
images comprises aligning the plurality of images based on a
reference image, wherein the reference image has a same field of
view.
10. The method in claim 7, wherein processing the plurality of
images comprises removing an unclear portion of the image and
saving a clear portion of the image for different ones of the
plurality of images.
11. The method in claim 7, wherein processing the plurality of
images comprises combining a clear portion from different ones of
the plurality of images to create a composite image of the eye.
12. The method in claim 7, wherein processing the plurality of
images comprises adjusting the image brightness to increase
uniformity in brightness in the composite image.
13. A method of operation of an eye imaging apparatus to illuminate
an eye time-sequentially, the method comprising: emitting light by
each of a plurality of light emitting elements within the eye
imaging apparatus time-sequentially; directionally controlling the
emitted light by a light conditioning element within the eye
imaging apparatus, the light conditioning element comprising at
least one multi-segment surface transmitting the emitted light
through an optical window at a front end of the eye imaging
apparatus, the optical window being configured to be in contact
with a cornea of the eye; illuminating each of a plurality of
portions of the eye by the emitted light time-sequentially; and
receiving a plurality of images of the eye formed by reflected
light of the emitted light with a same field of view by an image
sensor within the eye imaging apparatus.
14. The method in claim 13, wherein illuminating each of a
plurality of portions of the eye comprises illuminating each of a
plurality of portions of a posterior segment of the eye.
15. The method in claim 13, wherein a plurality of sections of the
light conditioning element are separated by a plurality of
barriers, each of the plurality of barriers extending in a radial
direction.
16. The method in claim 13, wherein the emitted light from the
plurality of light emitting elements are transmitted directly to
the light conditioning element.
17. The method in claim 13, wherein the emitted light are
transmitted from the plurality of light emitting elements to
optical fiber bundles, and further transmitted from the optical
fiber bundles to the light conditioning element.
18. The method in claim 13, further comprising processing the
plurality of images to create a composite image of the eye.
19. The method in claim 13, wherein processing the plurality of
images comprises aligning the plurality of images based on a
reference image, wherein the reference image has a same field of
view.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. application Ser.
No. 14/614,305 filed Feb. 4, 2015 which is a continuation of U.S.
application Ser. No. 14/191,291 filed Feb. 26, 2014 which is a
continuation-in-part of U.S. application Ser. No. 13/845,069 filed
Mar. 17, 2013 which claims the benefit of U.S. Provisional
Application No. 61/612,306 filed Mar. 17, 2012, each of which is
herein incorporated by reference in its entirety.
INCORPORATION BY REFERENCE
[0002] All publications and patent applications mentioned in this
specification are incorporated herein by reference in their
entirety to the same extent as if each individual publication or
patent application was specifically and individually indicated to
be incorporated by reference.
STATEMENT AS TO FEDERALLY SPONSORED RESEARCH
[0003] None.
BACKGROUND
[0004] Various embodiments of the invention relate generally to an
eye imaging apparatus and related methods, and for example to an
eye imaging apparatus with a wide field of view and related
methods.
[0005] Eyes are among the most valued human organs that play
indispensable roles in life. Likewise, eye diseases and vision loss
in general are serious problems. Moreover, eye diseases and vision
problems among children, especially new-born babies, can have
severe and far-reaching implications. For infants and small
children, the visual centers in the brain are not fully mature. For
the visual centers in the brain to develop properly, proper input
from both eyes is desirable. Therefore good vision can be an
important factor in the proper physical development and educational
progress.
[0006] Undetected eye problems in infants and others may result in
irreversible loss of vision. Early detection and diagnosis provide
the best opportunity for treatment and prevention of vision
loss.
[0007] In eye examinations, eye imaging apparatus has become
increasingly important. Since retinal and optic nerve problems are
among the leading causes in vision loss, eye imaging apparatus
capable of imaging a posterior segment of the eye can be
particularly useful. Moreover, an eye imaging apparatus with a wide
field of view can offer the benefit of enabling evaluation of
pathologies located on the periphery of the retina.
SUMMARY OF THE DISCLOSURE
[0008] Various embodiments disclosed herein include, although are
not limited to, an eye imaging apparatus with a wide field of view,
which may be, for example, from 60 degree to 180 degree.
[0009] Various embodiments, for example, may comprise an apparatus
comprising a housing and a light source disposed inside the housing
to illuminate an eye. The apparatus can also include an optical
imaging system. The system can include an optical window at a front
end of the housing with a concave front surface for receiving the
eye. The system can also include an imaging lens disposed rearward
the optical window and optically aligned with the optical window
along an optical imaging path. The optical imaging system can have
an optical axis. The apparatus can comprise a light conditioning
element in the housing having at least one multi-segment surface
positioned behind the peripheral portion of the optical window. The
light conditioning element can be configured to receive light from
the light source and direct said light to the eye. The apparatus
can include an image sensor in the housing disposed to receive an
image of the eye from the optical imaging system.
[0010] Various other embodiments comprise an eye imaging apparatus
including a housing and an optical window at a front end of the
housing. The apparatus can comprise a light conditioning element
having at least one multi-segment surface positioned behind the
peripheral portion of the optical window. The light conditioning
element can be configured to receive light from a light source and
direct light to an eye.
[0011] In various embodiments, a light conditioning element for an
eye imaging apparatus for illuminating an anatomical feature in a
medical examination is disclosed. The element can comprise a body
having front surface, a back surface, an inner side surface and an
outer side surface. The inner side surface and the outer side
surface can comprise at least one multi-segment surface. The light
conditioning device can be configured to receive light from a light
source and direct light to an eye.
[0012] Various embodiments disclose an eye imaging apparatus
employing sequential illumination. The apparatus can comprise a
housing and a light source disposed inside the housing and having a
plurality of light emitting elements configured to illuminate
different portions of an eye time-sequentially. The apparatus can
include an optical imaging system inside the housing. The optical
imaging system can comprise an optical window at a front end of the
housing. The system can also include an imaging lens positioned
behind the optical window and optically aligned with the optical
window. An image sensor can be configured to receive a plurality of
images of the eye with a same field of view through the optical
imaging system while each portion of the eye is illuminated
time-sequentially.
[0013] In some other embodiments, a compact eye imaging apparatus
includes a housing and a light source disposed inside the housing
to illuminate an eye. The apparatus can include an optical imaging
system. The system can include an optical window with a radius of
curvature closely matching a curvature of a cornea of the eye at a
front end of the housing. An imaging lens can be optically aligned
with the optical window. The imaging lens can be positioned behind
and separated from the optical window by a gap. The system can
include at least first and second relay lenses. At least one
miniature lens with a clear aperture size less than 5 mm can be
configured to form the image of the eye based on light received
from the at least first and second relay lenses. A miniature image
sensor with a format less than 1/1.5'' can be configured to receive
the image of the eye formed by the at least one miniature lens.
[0014] Various other embodiments comprise an eye imaging system
comprising an eye imaging apparatus comprising a housing and a
light source disposed inside the housing and having a plurality of
light emitting elements. The light emitting elements can be
configured to illuminate different portions of an eye
time-sequentially. The eye imaging system can include an optical
imaging system. The optical imaging system can include an optical
window at a front end of the housing. An imaging lens can be
positioned behind the optical window and optically aligned with the
optical window. An image sensor can be configured to receive a
plurality of images of the eye with a same field of view through
the optical imaging system while each portion of the eye is
illuminated time-sequentially. A memory can be configured to
temporarily store the plurality of images. A computing and
communication unit can be configured to receive and transmit the
plurality of images. The eye imaging system can further include an
image computing module configured to receive the plurality of
images from and exchange data with the eye imaging apparatus. The
image computing module can comprise an image processing unit
configured to generate a set of instructions to process the
plurality of images to create a composite image of the eye.
[0015] A method of imaging an eye is also disclosed. The method can
include activating a light source to illuminate an eye. An optical
window can be contacted with a cornea of the eye. The method can
further include conditioning light received from the light source
by a light conditioning element having at least one multi-segment
surface. The light conditioning device can be configured to receive
light from the light source and direct light to the eye. The method
can include imaging the eye through an optical imaging system
comprising said optical window and an imaging lens. The imaging
lens can be positioned behind the optical window and can be
optically aligned with the optical window. The method can comprise
receiving an image of the eye through the optical imaging system by
an image sensor.
[0016] A method of imaging an eye configured for sequential
illumination is also disclosed. The method can comprise varying an
intensity of a plurality of light emitting elements over time to
illuminate different portions of an eye. The method can further
include imaging the eye through an optical imaging system
comprising an optical window and an imaging lens. The optical
window can be configured to be in contact with a cornea of the eye.
The imaging lens can be positioned behind the optical window and
optically aligned with the optical window. The method can include
receiving a plurality of images of the eye with a same field of
view through the optical imaging system while each portion of the
eye is illuminated time-sequentially by an image sensor. The
plurality of images can be processed to create a composite image of
the eye from the plurality of images.
[0017] A stereo eye imaging apparatus is also disclosed. The stereo
eye imaging apparatus can include a housing and a light source
disposed inside the housing to illuminate an eye. The stereo eye
imaging apparatus can also comprise an optical imaging system. The
optical imaging system can include an optical window at a front end
of the housing with a radius of curvature closely matching a radius
of curvature of a cornea of the eye. An imaging lens can be
positioned behind the optical window and optically aligned with the
optical window. A light conditioning device can be positioned
behind the peripheral portion of the optical window that is
configured to receive light from the light source and direct light
to the eye. A first camera and a second camera can be configured to
capture a first image and a second image of the eye through the
optical imaging system. Extensions of a first optical axis of the
first stereo camera and of a second optical axis of the second
stereo camera can be converged onto the eye with a convergent
angle.
[0018] A hermetically sealed eye imaging apparatus is also
disclosed. The hermetically sealed eye imaging apparatus can
include a housing with a front end and a light source disposed
inside the housing to illuminate an eye. The hermetically sealed
eye imaging apparatus can include an optical imaging system. The
optical imaging system can include an optical window at the front
end with a concave front surface for receiving the eye. The optical
imaging system can also include an imaging lens disposed rearward
the optical window and optically aligned with the optical window
along an optical imaging path. The optical imaging system can have
an optical axis. The hermetically sealed eye imaging apparatus can
comprise a hermetical seal between the optical window and the front
end filled with a hermetically sealing material. An image sensor in
the housing can be disposed to receive an image of the eye from the
optical imaging system.
[0019] In some other embodiments, an eye imaging apparatus
comprises a housing with a front end having an inner side surface
comprising an alignment edge and a reservoir edge disposed at the
front end. The eye imaging apparatus can include a light source
disposed inside the housing to illuminate an eye. The eye imaging
apparatus can further comprise an optical imaging system. The
optical imaging system can include an optical window at the front
end with a concave front surface for receiving the eye. The optical
imaging system can also comprise an imaging lens disposed rearward
the optical window and optically aligned with the optical window
along an optical imaging path, the optical imaging system having an
optical axis. The optical window can be separated from the
alignment edge with a first gap. The optical window can be
separated from the reservoir with a second gap larger than the
first gap, configured to be a reservoir of a sealing material. An
image sensor in the housing can be disposed to receive an image of
the eye from the optical imaging system.
[0020] Other embodiments also comprise an eye imaging apparatus
comprising a housing with a front end comprising an inner side
surface comprising an alignment edge and a reservoir edge disposed
near the front end. The eye imaging apparatus can include a light
source disposed inside the housing to illuminate an eye. The eye
imaging apparatus can include an optical imaging system. The
optical imaging system can include an optical window at the front
end with a concave front surface for receiving the eye. The optical
imaging system can comprise an imaging lens disposed rearward the
optical window and optically aligned with the optical window along
an optical imaging path, said optical imaging system having an
optical axis. The optical window can be separated from the
alignment edge with a first gap. The optical window can be
separated from the reservoir with a second gap larger than the
first gap, configured to be a reservoir of a sealing material. A
plurality of balls can be disposed between the housing and the
optical windows. An image sensor in the housing can be disposed to
receive an image of the eye from the optical imaging system.
[0021] Various embodiments comprise an eye imaging apparatus
comprising a housing with a front end comprising a distal section
around an optical window comprising a first material. A proximal
section can comprise a second material. The front end can also
include a bond, wherein the distal section is connected with the
proximal section by the bond. The eye imaging apparatus can include
a light source disposed inside the housing to illuminate an eye.
The eye imaging apparatus can include an optical imaging system.
The optical imaging system can comprise the optical window at the
front end with a concave front surface for receiving the eye. The
optical imaging system can also include an imaging lens disposed
rearward the optical window and optically aligned with the optical
window along an optical imaging path, said optical imaging system
having an optical axis. An image sensor in the housing can be
disposed to receive an image of the eye from the optical imaging
system.
[0022] Some embodiments of a hermetically sealed eye imaging
apparatus with a hermetically sealed removable front imaging module
are also disclosed. The hermetically sealed eye imaging apparatus
can include a housing and a light source disposed inside the
housing to illuminate an eye. The hermetically sealed eye imaging
apparatus can include a hermetically sealed removable front imaging
module with a front end and a rear end. The hermetically sealed
removable front imaging module can include an optical imaging
system. The optical imaging system can comprise a first optical
window at the front end with a concave front surface for receiving
the eye. The optical imaging system can also include an imaging
lens disposed rearward the optical window and optically aligned
with the optical window along an optical imaging path. The
hermetically sealed eye imaging apparatus can include a first
hermetical seal between the first optical window and the front end
filled with a first hermetically sealing material. The hermetically
sealed eye imaging apparatus can include a second optical window at
the rear end. The hermetically sealed eye imaging apparatus can
include a second hermetical seal between the second optical window
and the rear end filled with a second hermetically sealing
material. A main module can comprise an image sensor in the housing
disposed to receive an image of the eye from the optical imaging
system. The hermetically sealed removable front imaging module can
be capable of being repeatedly attached to and removed from the
main module.
[0023] In some embodiments, an eye imaging apparatus comprises a
housing with a front end comprising an inner side surface
comprising an alignment edge and a reservoir edge disposed at the
front end. The eye imaging apparatus can comprise a light source
disposed inside the housing to illuminate an eye. The eye imaging
apparatus can comprise an optical imaging system. The optical
imaging system can include an optical window at the front end with
a concave front surface for receiving the eye. The optical imaging
system can also include an imaging lens disposed rearward the
optical window and optically aligned with the optical window along
an optical imaging path, said optical imaging system having an
optical axis. The alignment edge can be perpendicular to a side
surface of the optical window. The optical window can be separated
from the reservoir edge with a gap configured to be a reservoir of
a sealing material. An image sensor in the housing can be disposed
to receive an image of the eye from the optical imaging system.
[0024] In certain embodiments, the eye imaging apparatus comprises
a housing, a light source inside the housing, an optical imaging
system, a light conditioning element and an image sensor. The
optical imaging system includes an optical window configured to be
in contact with a cornea of the eye on a forward said of the
optical window and an imaging lens positioned rearward of the
optical window and optically aligned with the optical window. The
light conditioning element comprises a multi-segment surface and is
positioned behind the peripheral portion of the optical window and
configured to receive light from the light source and direct light
to the eye. The image sensor is configured to receive an image of
the eye through the optical imaging system.
[0025] Various embodiments disclosed herein include an eye imaging
apparatus with a wide field of view configured to provide
sequential illumination. The eye imaging apparatus comprises a
plurality of light emitting elements, an optical imaging system,
and an image sensor. The plurality of light emitting elements is
configured to illuminate each portion of an eye time-sequentially.
The image sensor is configured to receive a plurality of images of
the eye with a same wide field of view through the optical imaging
system while each portion of the eye is illuminated
time-sequentially. In some embodiments, the eye imaging apparatus
further comprises an image processing unit. In some embodiments,
the eye imaging apparatus may transfer the plurality of images to
other computing devices or internet based devices that include an
image processing unit. The image processing unit is configured to
generate a set of instructions to process the plurality of images
to create a single clear image of the eye.
[0026] Various embodiments disclosed herein include an eye imaging
system with a wide field of view. The eye imaging system comprises
an eye imaging apparatus and an image computing module. The eye
imaging apparatus comprising a plurality of light emitting
elements, an optical imaging system, an image sensor, a memory, and
a computing and communication unit. The memory is configured to
temporarily store the plurality of images. The computing and
communication unit is configured to receive and transmit the image.
The imaging computing module is configured to receive the plurality
of images from and exchange data with the eye imaging apparatus.
The image computing module further includes an image processing
unit configured to generate a set of instructions to process the
plurality of images to create a single clear image of the eye.
[0027] Various embodiments disclosed herein include a method of
imaging an eye with a wide field of view. The method comprises
activating a light source to illuminate an eye, conditioning the
light source using a light conditioning element with a
multi-segment surface, and receiving an image of the eye through an
optical imaging system by an image sensor. The light conditioning
element is configured to receive light from the light source and
direct light to the eye.
[0028] Various embodiments disclosed herein further include a
method of imaging an eye by sequential illumination. The method
comprises activating a plurality of light emitting elements
time-sequentially to illuminate different portions of an eye at
different times, imaging the eye through an optical imaging system,
and receiving a plurality of images of the eye with a same wide
field of view through the optical imaging system while each portion
of the eye is illuminated time-sequentially by an image sensor, and
processing the plurality of images to create a single image of the
eye.
[0029] Some embodiments disclosed herein include an eye imaging
apparatus configured to generate a three-dimensional image. The
three-dimensional eye imaging apparatus comprises a light source,
an optical imaging system, a light conditioning element, a first
image sensor and a second image sensor configured to receive a
first image and a second image of the eye. A first optical axis at
the first image sensor and a second optical axis at the second
image sensor extend to and converge onto the eye at an angle (e.g.,
convergent angle) with respect to each other.
[0030] Various embodiments disclosed herein include a compact eye
imaging apparatus with a wide field of view. The eye imaging
apparatus comprises a light source inside a housing, an optical
imaging system, and a miniature image sensor. The optical imaging
system includes an optical window, an imaging lens, two sets of
relay lenses and a set of miniature lenses. The format for the
camera comprising the miniature lens or lenses and the sensor is
less than 1/2.2inches or 1/3.2 inches in some embodiments with as
sensor size between less than 8.0.thrfore.6.0 mm or 7.0.times.5.0
mm and an camera size of less than 10 mm.times.10 mm or 9
mm.times.9 mm.
[0031] Various embodiments disclosed herein include a hermetically
sealed eye imaging apparatus. The housing of the hermetically
sealed eye imaging apparatus surrounds and fits with an edge of an
optical window. The imaging lens is positioned rearward of the
optical window and separated from the optical window by a small
gap. The optical window is separated from a first portion of the
housing by a first gap, which is configured to align the optical
window. The optical window is also separated from a second portion
of the housing by a second gap, which is configured to be a
reservoir of a hermetically sealing material. A hermetical seal is
disposed between the optical window and the housing. The hermetic
seal is airtight and watertight and can withstand remain intact
with exposure to the high temperatures of an autoclave that is used
for sterilization.
[0032] Various embodiments disclosed herein include a hermetically
sealed eye imaging apparatus with a hermetically sealed removable
front imaging module. An optical window and imaging lens are
positioned within the hermetically sealed removable front imaging
module. An image sensor is positioned within the main module. A
first hermetical seal is disposed between the optical window and a
housing for the front imaging module, and a second hermetical seal
between the housing and a second optical window, which is exposed
from a rear portion of the hermetically sealed removable front
imaging module. The hermetically sealed removable front imaging
module is capable of being removed from the main module.
[0033] Various embodiments disclosed herein include an eye imaging
apparatus with a wide field of view of 120 degrees or lager. The
eye imaging apparatus is capable of imaging the posterior segment
of the eye, and, in various embodiments, obtains high quality
images with high contrast. In various embodiments, the images of
the posterior segment of the eye acquired by the eye imaging
apparatus are essentially glare free or haze free, or have
negligible glare or haze, even for the patients with dark
pigmentation in the eyes.
[0034] Various embodiments comprise an eye imaging apparatus that
is compact and configured to be hand-held. Various embodiments are
sufficiently compact so as to be carried by in a carrying case,
e.g., a small carrying case with a handle, or in other convenient
manners due to its compactness. Various embodiments may be easily
operated by the operators with the little training. Various
embodiments meet the needs of patients who do not have convenient
access to hospitals or eye care facilities. The eye imaging
apparatus provides more opportunities for treatment and prevention
of vision loss. In particular, eye imaging apparatus described
herein potentially has far-reaching significance for the physical
development and educational progress of small children in rural
areas.
[0035] Furthermore, various embodiments of hermetically sealed eye
imaging apparatus are capable of withstanding the sterilization
procedure in an autoclave, thus reducing or eliminating the
possibility of cross-contamination among patients. Various
embodiments of the hermetically sealed eye imaging apparatus are
suitable to be used in surgical applications.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] FIG. 1(A) schematically illustrates a side view of an eye
imaging apparatus according to one embodiment of the present
invention.
[0037] FIG. 1(B) schematically illustrates the bottom view of an
eye imaging apparatus according to one embodiment of the present
invention.
[0038] FIG. 2 schematically illustrates one embodiment of the
optical design of the eye imaging apparatus showing illumination
and imaging optical systems.
[0039] FIG. 3 schematically illustrates another embodiment of the
optical design of the eye imaging apparatus showing the
illumination and imaging optical systems.
[0040] FIG. 4 schematically illustrates one embodiment of a
three-dimensional eye image apparatus.
[0041] FIG. 5(A) schematically illustrates a light conditioning
element of the eye imaging apparatus providing in some embodiments
a light channel (e.g. hollow external channel) between said light
conditioning element and sidewalls of an imaging lens.
[0042] FIG. 5(B) schematically illustrates a light intensity
profile on an optical window and the anterior surface of the
crystalline lens provided by some embodiments for illumination.
[0043] FIG. 5(C) schematically illustrates the three-dimensional
view of the light conditioning element of the eye imaging apparatus
for some embodiments.
[0044] FIG. 5(D) schematically illustrates a close-up view of
another embodiment of the light conditioning element having a
multi-segment surface and a light channel (e.g. external channel)
formed by said light conditioning element, and in particular by
said multi-segment surface, and a sidewall of an imaging lens.
[0045] FIG. 5(E) schematically illustrates the light conditioning
element comprising multiple sections in some embodiments.
[0046] FIG. 6(A) schematically illustrates the light conditioning
element including an internal light channel which can be used in
some embodiments.
[0047] FIG. 6(B) schematically illustrates a close-up view of
another embodiment of the light conditioning element comprising an
internal light channel having multi-segment surfaces on opposite
sides of the channel.
[0048] FIG. 7(A) schematically illustrates the light conditioning
element comprising an internal light channel and additionally
forming a light channel (e.g. hollow external channel) between the
light conditioning element and the side wall of an imaging lens
that can be used in various embodiments of the invention.
[0049] FIG. 7(B) schematically illustrates a close-up view of
another embodiment of the light conditioning element comprising an
internal light channel and forming an external light channel, the
light conditioning element comprising a multi-segment surface on
both the inner and outer sides.
[0050] FIG. 8 schematically illustrates one embodiment of the eye
imaging apparatus using light emitting elements such as LEDs as the
light sources.
[0051] FIG. 9 schematically illustrates the distribution of the
light emitting elements, where a total of 8 and 4 light emitting
elements are used in respective embodiments.
[0052] FIG. 10 schematically illustrates the images acquired when
the light emitting elements are activated time-sequentially and a
method used to enhance image quality according to various
embodiments of the invention.
[0053] FIG. 11 schematically illustrates another embodiment of the
eye imaging apparatus using optical fibers to guide light from the
light emitting elements to the light conditioning element.
[0054] FIG. 12 schematically illustrates embodiments of light
elements configured to couple light from the light emitting
elements to the optical fiber lighting elements.
[0055] FIG. 13 schematically illustrates another embodiment of the
eye imaging apparatus where the light emitting elements are placed
in a main module of the eye imaging apparatus. Light from the light
emitting elements is coupled to optical fiber bundles in the main
module. Optical fiber bundles in a front imaging module are aligned
and in direct contact with the optical fiber bundles in the main
module to receive light therefrom.
[0056] FIG. 14 schematically illustrates another embodiment of the
eye imaging apparatus where the light emitting elements are located
in the main module of the eye imaging apparatus, but near the
interconnection interface and couple light into optical fiber
bundles in the front imaging module.
[0057] FIG. 15 schematically illustrates the details of the optical
coupling design between the removable front imaging module and main
module of the imaging apparatus according to various embodiments of
the present invention.
[0058] FIG. 16 schematically illustrates an embodiment of a
hermetically sealed eye imaging apparatus where the optical window
may be dropped in from inside the housing during the assembly
process.
[0059] FIG. 17 schematically illustrates another embodiment of a
hermetically sealed eye imaging apparatus.
[0060] FIG. 18 schematically illustrates yet another embodiment of
a hermetically sealed eye imaging apparatus comprising a plurality
(e.g., 3 or 4) tiny balls disposed with equal spacing around the
peripheral of the optical window.
[0061] FIG. 19 demonstrates another embodiment of a hermetically
sealed eye imaging apparatus where the optical window may be
dropped in from the front side during the assembly process.
[0062] FIG. 20 schematically illustrates another embodiment of the
hermetically sealed eye imaging apparatus where an adhesive is used
to seal the optical window.
[0063] FIG. 21(A) schematically illustrates an embodiment where an
opening is made in the center of the optical window to allow a
portion of the imaging lens to be disposed in the opening.
[0064] FIG. 21(B) schematically illustrates another embodiment
where the opening in the center of the optical window has sidewalls
parallel to each other and to the optical axis of the optical
imaging system thereby potentially simplifying manufacture.
DETAILED DESCRIPTION
[0065] The present invention now will be described in detail with
reference to the accompanying figures. This invention may be
embodied in many different forms and should not be construed as
limited to the exemplary embodiments discussed herein.
[0066] Various embodiments of the present disclosure describe an
eye imaging apparatus. In some embodiments, this eye imaging
apparatus has a wide field of view. The field of view, may in
certain embodiments be at least 60 degree and up to 180 degree. In
some embodiments, the field of view is at least 120 degrees but no
more than 180 degrees. Various embodiments of the eye imaging
apparatus may, for example, comprise a housing, a light source
inside the housing to illuminate an eye, and an optical imaging
system inside the housing. The optical imaging system may include
an optical window configured to be in contact with a cornea of the
eye forward the optical window, an imaging lens positioned behind
the optical window and optically aligned with the optical window, a
light conditioning element having a multi-segment (e.g., reflective
and/or refractive) surface configured to receive light from the
light source and direct light to the eye, and an image sensor
configured to receive light from the eye through the optical
imaging system. In some embodiments, the light conditioning element
is positioned behind a peripheral portion of the optical window.
Also, in some embodiments, the imaging apparatus may further
comprises a memory configured to temporarily store images, and a
computing and communication subsystem including a touch screen
monitor configured to receive, display and transmit the image.
[0067] FIG. 1(A) and FIG. 1(B) schematically illustrate a side view
and a bottom view of an eye imaging apparatus according to various
embodiments of the present invention. The eye imaging apparatus may
be compact and in various embodiments has a size less than 250 mm
along the longest dimension thereof. For example, in some
embodiments the eye imaging apparatus may be between 250 mm and 200
mm, 150 mm, or 100 mm along the longest dimension. In some
embodiments, the eye imaging apparatus may weigh less than 1 kg.
For example, the eye imaging apparatus may weigh between 1 kg and
0.5 kg, or 0.3 kg, or 0.2 kg in some embodiments. The eye imaging
apparatus may be carried by the users in a small carrying case with
a handle, for example, that is less than 600 mm.times.400
mm.times.300 mm and weigh less than 15 kg or in another convenient
manner due to its compactness. In some embodiments, for example,
the carrying case is between (600 mm and 300 mm).times.(400 mm and
200 mm).times.(300 and 150 mm). Also, the carrying case weighs
between 15 kg and 10 kg or 5 kg, in some embodiments. Sizes outside
these ranges for the eye imaging system and the carrying case are
also possible. Various embodiments may be easily operated by the
operators with little training.
[0068] The imaging apparatus may have a portion constructed to be
in a cylindrical shape to allow easy grabbing by one hand and
usable as a handle with a display and/or user input interface such
as a touch screen monitor 102 mounted at the top of cylindrical
part 101. The users may precisely adjust the position/angle of the
apparatus with one hand freeing another hand to work on other
tasks, for example, opening the eyelids of the patient with the
fingers.
[0069] Captured images may be transferred to other computing
devices or internet based devices, like storage units, through
wired or wireless communication systems. In some embodiments, the
imaging apparatus is powered by a battery. Also in various
embodiments, live images may be displayed on the touch screen
monitor or a larger display monitor that receives data from this
imaging apparatus in real time. The eye imaging apparatus may be
used as a diseases screening or medical diagnosis device for the
ophthalmic applications. It may be used in remote rural areas where
traveling to the eye care facilities is not convenient. It may also
be used as a portable medical imaging device for other medical
needs such as ENT or dermatology. Furthermore, the imaging
apparatus may have applications in areas other than medical
applications, for example, for security screening applications
where the images from the posterior/anterior segment of the eye may
be used for the personal identification purpose.
[0070] The eye imaging apparatus may also be used to image the eyes
of animals. For example, the eye imaging apparatus may be used,
with or without modification of optics from its human use, to image
or photograph the eyes of animals such as livestock, pets, and
laboratory test animals, including horses, cats, dogs, rabbits,
rats, guinea pigs, mice, etc.
[0071] The eye imaging apparatus may comprise a front imaging
module and a main module. The eye imaging apparatus may be built as
one piece or two separate pieces, as shown as 101 and 112, in the
FIG. 1(A) and FIG. 1(B). In some embodiments, the front imaging
module 101 may be removed or replaced with other functioning
modules which may contain different optics. For example, front
imaging modules with higher magnification, front imaging modules
designed for premature babies, front imaging modules designed for
adult, front imaging modules designed for fluorescein angiography
imaging, front imaging modules for NIR imaging and front imaging
modules for anterior segment imaging can be used in different
circumstances. Accordingly, in designs where the front imaging
module is replaceable or removable, the eye imaging apparatus's
potential use or applications may be significantly expanded. An
optical window is exposed on the outside of the housing of the
imaging apparatus enabling light to enter into and exit out of the
housing. In various embodiments, the eye can be place proximal to
or up against the optical window to obtained images of the eye. The
window has central and peripheral portions 103, 104. The central
portion 103 of the window is employed as the entrance into the
housing for light reflected from the eye that is used to image the
eye. The peripheral region 104 of the window, which is disposed
about the center 103, is configured for egress of light from the
housing such as for example projecting light onto and/or into the
eye to illuminate the eye.
[0072] In some embodiments, the imaging apparatus may be used to
acquire images of the posterior segment of the eye with various
magnifications and under the illumination from broadband or narrow
spectral light sources. The spectrum of the light source may be in
the visible, IR, near IR, UV light range or combinations thereof.
To obtain a wide field of the view (FOV), the optical window may be
placed over the cornea of the eye with slight pressure.
Accordingly, the optical window may have a concave surface matching
the size of the cornea, In some embodiments, for example, the outer
surface of the optical window has a radius of curvature of between
6 mm and 15 mm. An optical transparent index matching gel with
sufficient viscosity may be placed between the cornea and the
optical window. The viscosity of the index matching gel may be at
least 100 centipoise, 200 centipoise or 300 centipoise. The iris of
the patient may or may not be dilated with special drugs. In some
embodiments, the imaging apparatus may also be used to obtain
images of the anterior segment of the eye by using a front imaging
module designed for imaging the anterior segment, using the same
illumination system.
[0073] FIG. 2 schematically illustrates one embodiment of the
optical design or optical system of the eye imaging apparatus,
where the posterior segment of the eye 201 is imaged or
photographed by the eye imaging apparatus. The optical imaging
system of the eye imaging apparatus includes an optical window 203
and an imaging lens 204. The optical window 202 is configured to be
in contact with the cornea 203 and may have a concave surface that
matched the curvature of the eye. In various embodiments, for
example, the radius curvature of the outer surface of the optical
window 202 is between about 6 mm and 15 mm. The imaging lens 204,
which may include one or multiple lens elements, is positioned
behind the optical window 202, on the opposite side of the window
as the eye, and optically aligned with the optical window 202. The
optical axis of the window and imaging lens may, for example, be
substantially aligned with the optical axis of the eye in some
cases but not all. For example, the practitioner may examine the
eye in a manner that the optical axis of the imaging system is
substantially aligned with the optical axis of the eye, however, in
some cases, the practitioner tilts the eye imaging apparatus such
that these axes are not aligned. Although the radius of the
curvature for the frontal optical surface of the optical window 202
is chosen to closely match that of the cornea, the back surface of
the optical window may be flattened out slightly depending on the
design of the optical illumination system. The optical window 202
may be made from the same or different optical materials as the
imaging lens 204. For a wide field of view optical imaging system,
the use of the optical index matching gel between the optical
window 202 and cornea 203 helps to eliminate significant amount of
optical aberrations originated from the cornea of the eye. The
curvature of the frontal surface of the imaging lens 204 may be the
same as that of the back surface of the optical window 202, or
different. The back surface of the imaging lens 204 may be either
spherical or non-spherical to obtain desired result for the images.
In some embodiments, a small gap of air or other material is placed
between the optical window 202 and the imaging lens 204, although
the two optical components may be in contact in certain areas or
even bonded or affixed together with adhesive.
[0074] In some embodiments, the optical imaging system may further
includes a first set of relay lenses 205 configured to form a
secondary image 208 of the eye near a back focal plane of the first
set of relay lenses, a second set of relay lenses 209 configured to
project the secondary image 208 to infinity with a front focal
plane positioned near the back focal plane of the first set of
relay lenses. In various embodiments, a set of miniature lenses 211
is positioned near the back focal plane of the second set of relay
lenses and configured to deliver light from the eye to the image
sensor 210. A miniature camera comprising the miniature lens or
lenses and the sensor has a format no more than 1/2.2 inches or
1/3.2 inches with a focal length of about 4 mm or less, for example
between about 4 mm and 2 mm or 4 mm and 3 mm, etc. The view angle
for the miniature lens or lenses may be 75.degree. or less with a
sensor appropriately sized based, for example, on the focal length
of the miniature lens. The camera module, which includes the sensor
chip and the miniature lens or lenses is about 8.5.times.8.5 mm, or
between 10 mm.times.10 mm and 5 mm.times.5 mm or smaller, for
example. In some embodiment, for example, the set of miniature
lenses 211 have aperture sizes between about 0.8 mm and 1.5 mm
while the first and second relay lenses 205, 209 have aperture
sizes of about 20 mm, for example between about 30 mm and 10 mm or
25 mm and 15 mm in some embodiments. The optical imaging system may
gather light reflected from the posterior segment or more
specifically the retina of the eye 206. The light passes through
the center of the iris opening and the crystalline lens of the eye
207, and forms a real image (of the posterior segment or retina) at
the secondary image plane 208. As discussed above, the imaging lens
204 may include single or multiple lenses, with spherical or
non-spherical surfaces. In some embodiments, the secondary image
plane 208 is located near the back focal plane of lens 205. In some
embodiments, a relay lens 209 may be used to project the image from
the secondary image plane 208 to infinity when the front focal
plane of the lens 209 is also placed near the secondary image plane
208. A miniature image sensor 210, either in form of CCD, CMOS or
other types, with its own miniature lenses 211, may be positioned
near the back focal plane of the lens 209 along the optical axis of
the optical imaging system. The miniature lenses 211 may include
multiple optical lenses. In some embodiments, the image sensor 210
has an active area that is about 6.2 mm.times.4.6 mm or, for
example, between about 8 mm and 4 mm.times.6 mm and 3 mm or between
about 7 mm and 5 mm.times.5 mm and 4 mm. Accordingly, in various
embodiments the active areas of the sensor 210 are about 1/4 of the
aperture size of the relay lenses 205, 208 or for example between
about 0.4 and 0.2 or 0.5 and 0.1 the size thereof. The diagonal of
the sensor 210 are also about 1.4 times of focal length of the
miniature lenses 211 or, for example, between about 1.6 and 0.8
times of the focal length.
[0075] In some embodiments, the optical imaging system has an
aperture 212 that is disposed in the set of miniature lenses 211.
FIG. 2, for example, shows the aperture 212 positioned between
lenses comprising the set of miniature lenses 211 and in front of
the miniature image sensor 210. In some embodiments, the aperture
212 of the optical imaging system is positioned in front of the set
of miniature lenses 211. In some such embodiments the aperture 212
is disposed between the miniature lenses 211 and the relay lens
209, however, possibly closer to the miniature lenses. Because the
designed object plane for the miniature lenses 211 is at infinity,
the use of such miniature lenses may bring the retinal image from
the infinity to the image sensor 210. In various embodiments, the
miniature lenses 211 are built with a circular optical aperture
(iris) 212, which may be located between miniature lenses in the
set of miniature lenses or formed by an aperture plate in front of
the miniature lenses 211. In certain embodiments such location of
the iris 212 reduces optical aberration. The miniature lenses 211
may not only relay the image of the retina 206 to the image sensor
210, but also form an entrance pupil for the optical imaging system
near the surface of crystalline lens 207 when the aperture 212
becomes the aperture of the entire optical imaging system. This
special arrangement helps to eliminate significant amount of
scattering light from the anterior chamber of the eye and the
optical elements in the optical imaging system.
[0076] In various embodiments, one or more of the miniature lenses
in the lens group 211 are configured to be moved or adjusted, for
example, longitudinally along the optical axis of the optical
imaging system with respect to one or more other of the miniature
lenses in the lens group 211, to change the effective optical focal
length of the set of miniature lenses, which changes in
magnification and results in an optical zoom for the images
acquired. Additionally, or alternatively, miniature lenses in the
lens group 211 are configured to be moved or adjusted, for example,
longitudinally along the optical axis of the optical imaging system
to adjust the position of the entire miniature lens group 211 to
change the effective focal length of the optical imaging system. In
various embodiments, therefore the effective focal length of the
whole imaging system is changed while the focal length of the
miniature lens group is unchanged thereby providing adjusting the
focus of the imaging system. Actuators such as voice coils, piezos,
stepper motors or other types of actuators or combinations thereof
may be used to longitudinally translate one or more or all of the
miniature lenses to change the effective focal length(s) and/or
provide zoom. In various embodiments, focusing adjustment of the
retinal image on the image sensor 210 may be similarly provided by
a built-in focusing mechanism that moves one or more of the
miniature lenses 211. Again, an actuator that translates one or
more of the miniature lenses in a longitudinal direction along the
optical axis may be employed. An auto-focus capability for the
imaging apparatus may be realized through the same mechanism in the
miniature lenses 211 when a closed loop control mechanism is
implemented. In various embodiments, for example, a voice coil or
other electrically controlled actuator may be employed and
controlled electronically. In various embodiments, the focusing
status of the retinal image on the image sensor 210 is determined
by comparing the sharpness of the image for multiple lens positions
in real time. The size of the retinal image may also be changed
through the optical zooming function of the miniature lenses 211
when the effective focal length of the miniature lens group is
adjustable. In various such embodiments, electronics may be used to
drive the actuator and control the focus and/or zoom. Signals from
the electronics to the actuator for varying the focus and/or zoom
may be based on input from a user and/or evaluation of the image
such as image quality. In certain embodiments, the shape or index
of refraction of the lens or lenses in the miniature lens group can
be altered in addition to or alternative to changing adjusting the
position for altering magnification, zoom, and/or focus. Control
electronics may drive such change in shape or refractive index.
[0077] In some embodiments, a second optical window 213 may be
installed when the imaging system is built into two separated
modules: the front imaging module and the main module. The optical
window 213 and the imaging lens 204 are positioned within the
removable front imaging module. The image sensor 210 is positioned
within the main module. The front imaging module is capable of
being removed from the main module. The second optical window 213
may be exposed from a rear portion of the removable front imaging
module. It may seal off the optics from the environment outside,
especially to prevent dust from depositing onto the surface of
relay lens 205 which may be visible in the images. Such a window
213 may also seal off the moisture during the sterilization
procedure if the removable front imaging module is in an autoclave.
Similarly, a third optical window 214 may also be installed on the
main module to seal off the rest of the optics from dust. The third
optical window 214 may be exposed from a front portion of the main
module. The imaging apparatus therefore may be divided into two
pieces which, in various embodiments, join at location at or
between the two optical windows 213 and 214.
[0078] FIG. 2, as do other drawings, show example optical designs.
Accordingly, the number of lens element or optical components, for
example, in each lens as well as their shapes, locations,
configurations, and arrangement may vary. For example, although the
first relay lens 205 is shown in FIG. 2 as a cemented doublet and
with one concave and one convex outer surface, this relay lens may
comprise a group of lenses including one cemented doublet and one
air spaced singlet. In various embodiments, however, one or more
optical elements are included that provide the function of a relay
lens such as the relay lens 205.
[0079] Another embodiment of the optical design is schematically
illustrated in FIG. 3. The optical imaging system in this
alternative embodiment, comprising an optical window 302, imaging
lens 304, and relay lens 305, works in similar manner as the one
shown in FIG. 2, but generates images with a smaller field of view
as shown in FIG. 3. The front part of the imaging apparatus is
different than that shown in FIG. 2, while the rest of imaging
system is the same as that shown in FIG. 2. Accordingly, the
components shown in FIG. 2 as 209, 210, 211, 212, 213 and 214 are
same as the components shown in FIG. 3 as 309, 310, 311, 312, 313,
and 314 respectively. In some other embodiments, different optical
imaging systems with special features or designs may be used that
have different performance characteristics and/or allow the imaging
apparatus to be used on different eyes or even subjects, for
example, adult eyes, horse eyes, dog or cat eyes, and rabbit eyes
etc.
[0080] FIG. 4 schematically illustrates one embodiment of a
three-dimensional eye image apparatus. The retina 406 may be imaged
or photographed when the contact optical window 402 is placed
against the cornea 403 of the eye 401. After the light from the
retina is passed through the center of the crystalline lens 407 in
the eye, a real image of the retina is formed at the secondary
image plane 408 by the imaging lens 404 and first relay lens 405.
The front focal plane of the second relay lens 409 is disposed near
the secondary image plane 408. Two imaging modules 411 and 412,
each includes miniature lenses 431 and 432 and an image sensor 441
and 442 similar to that in FIG. 2, are placed near the back focal
planes of the second relay lens 409 (one of the focal planes being
folded by a beam splitter 410). The beam splitting device 410 is
used to provide two separate optical paths for the imaging modules
411 and 412, for respective, left and right channel. In various
embodiments, the modules 411 and 412 having optical axes 413, 414
are directed toward the eye by the beamsplitter 410 such that the
optic axes are parallel but spaced apart by a fixed distance
between the second relay lens 409 and the beamsplitter 410. These
axes 413 and 414 converge on the eye, e.g., the retina and/or
posterior segment and thus are angled inward and convergent at the
optical window 402 and/or entrance pupil of the imaging system.
Individual optical apertures 451, 452 in the respective imaging
modules 411, 412 are relayed backward by the optical lenses in the
respective optical paths from the apertures to the eye and thereby
form two entrance pupils near the crystalline lens 407. The inset
in FIG. 4 shows a side view of the dual entrance pupils 415, 416
which are located near the center of the iris opening 417 of the
eye, and are the images of optical apertures 451 and 452
respectively.
[0081] In some embodiments, the extension of the optical axes of
413, 414 are not parallel but eventually converged on to the retina
406 in the eye, and result in a small convergent angle 418
therebetween on the forward side of the imaging lens 404 and
optical window 402. The amount of separation between the optical
axes 413, 414 at the imaging modules determines the convergent
angle 418. The convergent angle 418 determines the stereoscopic
effect of the 3D images recorded. In various embodiments, after the
imaging system is correctly calibrated, the focusing status of the
retinal images may be adjusted by superimposing the two images 422
and 423 that are formed on and recorded by the two image sensors
441 and 442. For example, as seen in the screen frame 421, in
various embodiments, if the features in the center of two images
422 and 423 are not fully overlapped, the images are out of focus.
Using software to detect the disparity of two images and a
close-loop control mechanism, the best focus of the retinal images
may be achieved quickly and precisely by providing that the two
images are at least substantially or in some embodiments completely
overlap to each other. As discussed above, actuators may be
employed to adjust the focus by varying the longitudinal position
of one or more lenses such as one or more miniature lens and/or of
the optical sensor in one or both of the imaging modules 411, 412.
The movement of the actuator may be driven by electronics
controlled by one or more feedback signals that assesses the image
data obtained. As discussed above, in various embodiments the
actuator may comprise a voice coil. Evaluation of the relative
positions of the same features in two images, for example, whether
the artery/vein in the left image is located at either left or
right side of same artery/vein in the right image, may be used to
determine the direction of the focus adjustment. The position of
each image sensor is pre-calibrated so that the individual image is
in focus when two images are fully overlapped. When the captured
stereoscopic images are displayed in a 3D screen, users may see the
depth of the objects in the posterior segment of the eye clearly.
Accordingly, various embodiments include a 3D display. Similar to
the embodiments discussed before, optical windows 419, 420 may be
included in the respective front imaging module and main module at
the junction therebetween to prevent dust and to build the imaging
apparatus autoclave ready.
[0082] Different approaches can be used to split the beam and thus
the beam splitting device 410 may comprise different types of
optical elements and/or arrangements. In some embodiments, the
device 410 may comprise a total reflective minor configured to be
inserted into place and removed therefrom or folded down and back
up at a rapid rate. At the position shown in FIG. 4, the light from
eye is guided to the imaging module 412. After one or more images
is taken by module 412, the device 410 may be either pulled up or
out of its previous position to allow the light from the relay lens
409 to enter the imaging module 411. As a result, two images are
recoded sequentially and at a rapid rate by two image sensors when
the various actions are synchronized. In some embodiments, the
device 410 may comprise and be split into a transparent section
410a and a reflective section 410b that are laterally disposed with
respect to each other. In various such embodiments, a dividing line
between the transparent and reflective sections 410a, 410b may be
aligned with the center of the optical axis of the imaging system.
The light from the eye, before reaching the module 411, may pass
through the transparent section 410a of device 410, while the light
to module 412 may be reflected by the reflective section 410b.
Here, the shutters (if any) of both image sensors may be
synchronized to take images simultaneously. In other embodiments,
the two imaging modules 411, 412 may be arranged to be side-by-side
and with their optical axes in parallel with an appropriate
separation of the two optical apertures to provide the stereo or 3D
effect. Although the optical axes of the imaging module 411, 412
may be arranged in parallel, a small convergent angle may be
provided at the retina. Accordingly, these optical axes may be
angled inward and convergent at the optical window 402 and/or
entrance pupil of the imaging system. The optical power of the
first relay lens 405 may contribute most of such convergence of
these optical axes at the optical window, entrance pupil, and eye
(e.g., retina). In various embodiments the convergence angle is
about 6.5.degree. or less and may for example range from 8.degree.
or 7.degree. to 3.degree., 4.degree., or 5.degree. or any
combination thereof as well as outside such ranges. In some
embodiments, a fixed but partially transmissive, partially
reflective beamsplitter 410 can be employed to split the imaging
light for directing to the respective imaging modules 411 and
412.
[0083] In some embodiments, the use of a stereoscopic imaging
arrangement may also allow implementation of more sophisticated
techniques to improve the image quality of retinal images. In
various embodiments, for example, software is used to analyze the
separation of the suspected artifacts in two stereoscopic images.
This measured separation can be compared with the separation of the
observed features on the retina. The difference in the separation
is directly related to the distance of the object in the vitreous
to the retina. If this difference in the separation is larger than
certain criteria, then the artifacts that may be removed from the
images, are present.
[0084] The separation of the features (artifacts) shown on images
from the first and second stereo cameras is related to the distance
from the object that produced such image features to the retina,
which in this case is the convergent point of the stereo cameras.
The farther away from the retina, the larger the separation (in
horizontal direction, or the along the axis separating two
cameras). In other words, if the object is located exactly at the
convergent plane, e.g., the retina, the two image features are
located at exactly same place when two images from the first and
second stereo cameras are superimposed to on each other. Using a
suitable image process technique, such as image convolution,
reference point tracking or other approaches, common features in
images captured at the same time by the first and second stereos
cameras that manifest a separation when the images are superimposed
can be identified and the separation can be measured. If the
objects are determined to be far away from the plane where the axes
of the first and second stereo cameras converge (e.g., the
convergent plane), the artifacts may be determined to be defocused
images of the object a distance away from the convergent plane
(e.g., the retina). These objects may be scattering light, for
example, from the crystalline lens, etc. Accordingly, these image
features could be removed with image processing. Information from
another camera can be used to fill in the area of the image where
the image feature was removed from one camera image. For example,
the information from the two images acquired by the two sensors
441, 442 should be sufficient. The removed portions of each of the
two images are in different locations. Therefore after removing the
artifact from one of the images, the missing part of that image
after removing the artifact could be filled with information or
portion of image from the other image. A similar approach can be
performed as well on the other image when the artifact is removed
therefrom. Such artifacts may include unwanted reflection, or haze,
from the crystalline lens. Processing electronics may be employed
to provide such an image processing capability.
[0085] FIG. 5(A) schematically illustrates a light conditioning
element employed in various embodiments of the eye imaging
apparatus. To obtain high quality images, proper illumination is
provided through the proper portion of the natural opening of the
eye while avoiding the imaging path. In particular, illumination is
provided through the peripheral regions of the eye pupil. This
approach reduces backscatter from the central portions of the
pupil, which would degrade the image of the retina obtained by
light reflected from the retina also passing through the pupil.
Since the eye is a complicated biological organ with its own
special optical systems, the scattering and reflection from the eye
in combination with its small aperture cause significant
difficulties in obtaining a high quality image. In particular, the
reflection and scattering from the eye cause glare and haze, which
obscures the images acquired by an eye imaging apparatus. Thus the
images from the posterior segment of the eye with a wide field of
view often exhibit a layer of strong haze or glare. This problem is
especially acute for the patients with dark pigmentation in the
eyes. Providing illumination through certain regions of the eye as
described herein, however, can reduce this backscatter and
reflection and the resultant haze and glare.
[0086] The light may be emitted from a light source (not shown in
FIG. 5(A)) and injected into an optical light conditioning element
506 positioned behind the peripheral portion 509 of the optical
window 501. FIG. 5(C) schematically illustrates a perspective view
of the light conditioning element. The light conditioning element
506 has a hollow ring shaped body that is configured to be disposed
about or around the imaging lens 504. In particular, the ring
shaped body has an open region in which the imaging lens 504 or a
portion thereof may be disposed. The light conditioning element is
configured to provide a channel for light to propagate around the
outside of the imaging lens 504 to the eye. The light conditioning
element has a central axis 540, a front end and a back end with
corresponding front surface 522 and back surface 503. The light
conditioning element also has inner and outer side surfaces. The
inner side surface 508 is closest to the imaging lens 504 and
defines the open inner region in which the imaging lens 504 is
disposed. In various embodiments, such as shown in FIGS. 5(A) and
5(D), the inner side surface 508 comprises a multi-segment surface.
In some embodiments, the outer side surface comprises a
multi-segment surface. Different portions or segments of the
multi-segment surface have different features such as different
shapes. In some embodiments different segments have different
curvatures and/or angles of inclination. The different segments may
also have different textures, coatings thereon, or comprise
different material. In certain, embodiments, however, the different
segments have different shapes to reflect and/or refract light
incident thereon differently, for example, into different
directions.
[0087] As illustrated in FIG. 5(C), the body of light conditioning
element may comprise a hollow truncated cone-shaped solid structure
comprising of solid optically transmissive or transparent material.
However, in certain embodiments the light conditioning element
comprises opaque material. Accordingly, the light conditioning
element may comprise glass, plastic, ceramic, metal or combinations
thereof. Other materials may also be employed. This shape may be
characterized as a hollow and ring-shaped and frusto-conical. The
front surface and the back surface as well as cross sections
orthogonal to the length are in the shape of a circular ring. The
back surface has a larger lateral extent, e.g., inner and outer
radii than the front surface. FIG. 5(D) illustrates a cross-section
view of the light condition element in some other embodiments.
Although FIG. 5(A) and FIG. 5(D) illustrate the cross-section view
of the light conditioning element in certain embodiments, the light
conditioning element can be rotationally symmetric about the
central axis 540 of the light conditioning element. In various
embodiments, each segment of the multi-segment surface is annular
and symmetric about the central axis. In various embodiments, the
light condition element comprises a hollow rotational symmetric
ring, where the inner surface of the ring comprises different
segments instead of one smooth surface.
[0088] As discussed above, at least one of the surfaces of the
light conditioning element comprises a multi-segment surface having
multiple reflective and/or refractive segments. The different
segments in the multi-segment surface may have different
orientations, different shapes, different coatings, or any other
different configurations. In some embodiments, the size of the
segments in the multi-segment surface varies between 0.05 mm or 0.1
mm to 1 mm or 2 mm along a direction of the central axis. It is
also possible for the size of the segments to be other values. In
some embodiments, the total number of segments in one light
conditioning element is greater than 2, but less than 10, or 20.
Other number of segments is also possible. In various embodiments,
the majority of the segments comprise reflective segments (e.g.,
having a reflectivity of at least 80%, 90%, 95%, 99%, or 100% and
ranged therebetween) that reflect light from the light sources to
the eye. In various embodiments, the multi-segment surface
comprises a substantially specularly reflective surface.
Accordingly, in various embodiments the multi-segment surface does
not comprise a microstructured refractive diffuser. The multiple
reflective surface segments are configured to provide precise
directional control of light, thus in various embodiments the light
conditioning element is configured to have a higher energy
efficiency than a refractive diffuser. In certain embodiments, for
example, the efficiency of the light conditioning element is 50%,
60%, 70% or higher or ranged therebetween.
[0089] The light conditioning element may distribute light received
from the light source into different portions as a result of the
different segments in the multi-segment reflective and refractive
surface. In some embodiments, light from the light source that is
reflected from the multi-segment light conditioning element is
distributed the light into different portions by total internal
reflection and possibly refraction of the multi-segment surface. In
some embodiments, the light conditioning element distributes the
light from the light source into different portions for example by
total internal reflection and refraction of the multi-segment
surface. The light conditioning element may provide a light channel
530 for propagation of light. In various embodiments such as shown
in FIGS. 5(A) and (D), the light channel 530 is formed by the an
inner surface 508 of the light conditioning element and an outer
surface or sidewall 505 of the imaging lens 504. In some
embodiments, this hollow external channel 530 is configured to
receive light from the light source and direct the light to the
eye. The light channel 530 may be considered an external light
channel because this channel is formed in an open space between the
inner surface 508 of the body of the light conditioning element and
the side surface of the imaging lens 504. In other embodiments, the
light channel may be formed between the two side surfaces of the
body of the light conditioning element and be referred to as an
internal light channel. In either case, at least one of the
surfaces forming the channel may comprise a multi-segment surface.
Such a multi-segment surface may distribute the light into the eye
in the desired manner. Various embodiments include both an external
light channel and an internal light channel.
[0090] In the embodiment shown in FIGS. 5(A) and 5(D), the light
conditioning element is configured to direct a first portion of
light from the inner edge of the light channel to a first area of a
retina of the eye including an optical axis of the optical imaging
system. In various embodiments, the first area comprises one-third
of the field of view of the optical imaging system. When the
optical axis of the optical imaging system is aligned with the
optical axis of the eye, the first area is the central area of the
retina of the eye. In various embodiments, the light conditioning
element is configured to direct more than 50%, 60%, 70% and 80% of
the light exiting from the inner edge of the light channel to the
first area of the retina. The light conditioning element is also
configured to direct a second portion of light from the outer edge
of the light channel to a second area of a retina of the eye away
from the optical axis and on an opposite side of the optical axis
from the outer edge of the light channel from which the light is
ejected. The second area is farther from the optical axis than
two-third of the field of view of the imaging system. When the
optical axis of the optical imaging system is aligned with the
optical axis of the eye, the second area is the peripheral area of
the retina. In various embodiments, the light conditioning element
is configured to direct more than 50%, 60% and 70% of 1 the light
exiting from the outer edge of the light channel to the second area
of the retina. In various embodiments, the first portion of light
forms an angle with the optical axis of the optical imaging system
from +10 degree to -30 degrees, and the second portion of light
forms an angle with the optical axis from -30 degree to -90
degrees. In this case, the plus degree corresponds to light
traveling upwardly from the optical axis shown in FIG. 5(A), and
the minus degree corresponds to light travels downwardly from the
optical axis. In various embodiments, the direction of the optical
axis of the optical window is the same as the central axis 540 of
the hollow cone-shaped solid structure and the two axes may be
aligned in certain embodiments. In various embodiments, the light
conditioning element is configured to direct more than 50%, 60%,
70% and 80% of the light exiting from the inner edge of the light
channel to propagate with a first angle between +10 degree to -30
degree with respect to an optical axis of the optical imaging
system. In various embodiments, the light conditioning element is
configured to direct more than 50%, 60%, and 70% of the light
exiting from the outer edge of the light channel with a second
angle between -30 degree to -90 degree with respect to the optical
axis.
[0091] As illustrated by FIG. 5(A), in various embodiments, the
light conditioning element is configured to direct light outside an
imaging path of the optical imaging system at the cornea and
optical window. As a result, less backscatter is generated from the
cornea and optical window that is in the imaging path. The image of
the retina relayed to the sensor therefore has reduced haze and
glare.
[0092] Also as shown in FIGS. 5(A) and 5(D), in various
embodiments, the eye imaging apparatus may include a hollow
external light channel 530 formed between the multi-segment surface
508 of the light conditioning element 506 and the side surface of
the imaging lens 504. The light conditioning element 506 may
include an optical reflective (and potentially refractive)
multi-segment surface which splits the light from the light source
into different portions, by reflection, e.g. total internal
reflection, (and potentially refraction) of its multi-segment
surface. The multi-segment surface 508 may be suspended with proper
space from the side surface of the imaging lens 504 to form an
external light channel 530. In certain embodiments the inner
surface of the light conditioning element and the outer surface of
the imaging lens are spaced apart by less than or equal to 3.0 mm,
2.5 mm, 2.0 mm, 01.5 mm, 1.0 mm or 0.5 mm and larger than zero or
ranges therebetween, such as for example, between 3.0 and 2.0 mm or
between 2.5 mm and 1.5 mm, etc. in certain embodiments of the
invention. Separations outside these ranges are also possible. In
various embodiments, the side surface of the imaging lens 504
comprises a first layer or coating of an optically absorptive
material and a second layer or coating of an optically reflective
material 505 on the top of the absorptive coating. Such multilayer
coating produces strong absorption to the stray light within the
imaging lens 504, while reflecting illumination light from another
side of the coating. However, other configurations are
possible.
[0093] Accordingly, with continued reference to FIGS. 5(A) and
5(D), in various embodiments, light is injected into the rear
portion of the light channel farther from the transparent window.
This light propagates through the light channel possibly reflecting
from the coated sidewalls of the imaging lens and the
multi-segmented inner surface of the light conditioning element.
Light in the light channel may propagate to the forward portion of
the light channel, which is closer to the transparent window and
exit the light channel.
[0094] In various embodiments, after multiple reflections (and
possibly refraction, for example, at the transmissive segment 507),
a portion of the light is propagated through the outer edge 509 of
the external light channel (see, e.g., 5(D)), the optical window
501 and the cornea 502, and onto a second area 510 of a retina of
the eye away from the optical axis and on an opposite side of the
optical axis from the outer edge of the light channel. The second
area 510 is farther from the optical axis than two-third of the
field of view of the imaging system. When the eye is aligned with
the optical axis of the optical imaging system, the second area 510
is the peripheral area of the retina. This light exits the channel
after reflecting from the inner surface of the light conditioning
element. For example, the last reflection prior to exiting the
light channel is from the inner surface of the light conditioning
element. The portion of light 509a emitted from the outer edge of
the light channel may be directed at -30 to -90 degree with respect
to the optical axis of the optical window and/or the central axis
540 of the light conditioning element. In various embodiments, most
of the light from the outer edge of the light channel, for example
50%, 60%, 70%, 80%, 90%, 95% or more of the light or ranges
therebetween, is directed into the peripheral portion, such as
between -30 to -90 degree with respect to the optical axis of the
optical window and/or the central axis 540 of the light
conditioning element.
[0095] Another portion of the light exits the light channel at its
inner edge 511 and is transmitted through the optical window 501,
the cornea 502 and is incident on the first area 512 of a retina of
the eye including an optical axis of the optical imaging system.
The first area comprises one-third of the field of view of the
optical imaging system. In some embodiments when the eye is aligned
with the optical axis of the optical imaging system, the first area
512 is the central portion of the retina. This light exits the
channel after reflecting from the outer surface of the imaging
lens. For example, the last reflection prior to exiting the light
channel is from the outer sidewall surface of the imaging lens. In
various embodiments, the portion of light emitted from the inner
ring edge of the light channel may be directed at +10 degree to -30
degree with respect to the optical axis. In various embodiments,
most of the light from the inner edge 511 of the light channel, for
example 50%, 60%, 70%, 80%, 90%, 95% or more of the light or ranges
therebetween, is directed into the central portion, such as between
+10 degree to -30 degree with respect to the optical axis.
[0096] As shown in FIG. 5(A), in various embodiments the design of
the multi-segment surface as well as the location of the inner edge
of the light channel 511 is such that the light emitted from this
area is not blocked by the edge of the iris 513 of the eye, which
may or may not be dilated during examination. Additionally, in
various embodiments, the multi-segment surface and the light
conditioning element are configured such that this light passes
through the pupil of the eye more at peripheral locations of the
pupil than at central locations of the pupil. In some embodiments,
for example, most of the light from the light conditioning element
does not pass through the eye pupil within an area corresponding to
the optical imaging path so as to reduce the likelihood of
backscatter of incident illumination into the optical imaging path.
In some embodiments this amount of light is more than 85%, 90%, or
95% or values therebetween. In many cases, the eye will be dilated
using medication during the eye examination. In such cases, the
pupil may be 6 to 8 mm for newborn babies, possibly 4 mm for
premature babies or 5 mm for children. In contrast, the entrance
pupil of the optical imaging system is about 1 to 2 mm in various
embodiments. Accordingly, in certain embodiments most of the light
from the light conditioning element propagates through the eye
pupil or past the entrance pupil of the optical imaging system a
distance of at least 2 mm or 2.5 mm to 3 mm or 3.5 mm from the
optical axis of the eye imaging system or central axis of the light
conditioning element. In some embodiments, this amount of light is
more than 80%, 90%, 95%, 97%, 99% or values therebetween.
Accordingly, this illumination light propagates into the eye at
locations well outside the entrance pupil of the imaging system
(which might be 1 to 2 mm in diameter) and only a negligible
amount, if any, passes through the entrance pupil of the optical
imaging system toward the retina. To further illustrate the
illumination arrangement, a front view of the optical window 501 is
provided as one insert in FIG. 5(A), where the light from the inner
edge of the light channel forms a light ring 511a and the light
from the outer edge forms a larger light ring 509a. The central
portion 517 of the optical window 501 is reserved as the optical
path for the light returning from the retina as the imaging light.
In order to demonstrate the lighting condition on the optical
window, the light intensity (I) profile on the optical window is
schematically shown in FIG. 5(B). As shown in FIG. 5(A) and FIG.
5(B), the illumination path and the imaging path are essentially
separated at the optical window 501.
[0097] As discussed above, in some embodiments, the optical imaging
system forms an entrance pupil near the crystalline lens of the
eye. A front view of the anterior surface of the crystalline lens
is also shown in the other insert of FIG. 5(A), where the entrance
pupil 515 is located near the center of the iris 513. The
illumination light from both the outer and inner edges of the light
channel 509, 511 falls on the area 516 which is outside of the
entrance pupil 515 of the optical imaging system, and does not fall
onto a circular area on the cornea or at the optical window (e.g.,
the front surface thereof closest to the eye) and entrance pupil
located near an optical axis of the optical window. Accordingly in
various embodiments most of the light (e.g. a value greater than
50%) from the light conditioning element does not fall within the
entrance pupil of the imaging system as this light propagates to
the retina. In some embodiments, this value is at least 70%, 80%,
85%, 90%, or values therebetween. Similarly, in various embodiments
most of the light (e.g. a value greater than 50%) from the light
conditioning element does not fall within the optical path of
imaging system at the cornea or optical window (e.g., the front
surface thereof closest to the eye) as this light propagates to the
retina. In some embodiments, this value is at least 70%, 80%, 85%,
90%, or values therebetween. In order to demonstrate the lighting
condition on the anterior surface of the crystalline lens, the
light intensity (I) profile of the illumination light is also
schematically illustrated in FIG. 5(B). Such optical arrangement
creates a separation between the illumination path and the imaging
path on the cornea, optical window (e.g., the front surface thereof
closest to the eye), and an anterior surface of the crystalline
lens and in some embodiments at the entrance pupil of the imaging
system, and reduces or prevents the reflected and scattered light
from entering the imaging path and eventually the image sensor. As
seen in FIG. 5(B), a small border area may be created between the
illumination zone 516 and entrance pupil 515, thus further reducing
the cross talk. The width of the border area is less than 0.5 mm.
As discussed above, the illumination light from the inner edge 511a
of the light channel is projected to the central portion of the
retina while the light from the outer edge 509a is projected to the
peripheral area. In various embodiments, the light from the two
light rings 509a, 511a of the optical window 501 may produce an
overlapping area for the illumination at the retina, and form a
relatively uniform illumination condition.
[0098] As illustrated, in various embodiments, the optical window
is disposed forward the imaging lens and forward the light
conditioning element. In certain embodiments, the optical window
may be dropped in from inside the housing during the assembly (for
example, from the rearward direction as opposed to from the
forward, eye side direction.). In some embodiments, the size of the
optical window is such that the peripheral portions of the optical
window extend forward and in front of the light conditioning
element. Light from the light conditioning element directed toward
the eye may be transmitted through the peripheral portions of the
optical window to the eye in various such embodiments. In certain
embodiments, the size of the optical window is smaller and light
from the light conditioning element directed toward the eye is not
transmitted through the peripheral portions of the optical window
to the eye.
[0099] FIG. 5(D) schematically illustrates a cross-sectional view
of another embodiment of the light conditioning element depicting
the external light channel formed by the inner surface of the light
conditioning element, which is shown as a multi-segment surface,
and the outer sidewall of the imaging lens. The hollow truncated
cone shaped device 506 may comprise optically transmissive or
transparent material. Some portion of its surfaces may be optically
polished. In some embodiments, the surface 507 may be left uncoated
or coated with optical transmission enhanced coating and may
potentially redirect light by refraction. The multiple segments
519, 520, 521, and 522 of the surface 508 may be coated with
optically reflective coating. The segment 521 of the surface may be
in the shape of a spherical or non-spherical curved surface as may
be the other segments in different embodiments. The light from the
light source enters the external light channel formed between the
light conditioning element 506 and reflective surface 505 of the
imaging lens 504. Some portion of the light may be blocked and
reflected by the reflective surface 519. Some portion of the light
may be reflected by the surface 505 first, then be reflected by the
surface segment 520, and then be reflected by the surface 505 the
second time, eventually being emitted from the inner edge 511 of
the light channel and projected onto the central area of the retina
near the optical axis of the eye and the imaging system. Some
portion of the light, which may be reflected by the surface 505 and
then be reflected by the surface 521, may be emitted from the outer
edge 509 of the light channel and projected onto the peripheral
area of the retina across the optical axis of the eye and the
imaging system. A portion of the light, which may be reflected by
the surface 505 only once and then exits the light channel, may
eventually be projected onto the retina between the central area
and the peripheral area in various embodiments. Ray tracing
simulations can be used to design such multi-segment surfaces.
[0100] FIG. 5(C) and FIG. 5(E) schematically illustrates a light
conditioning element comprising multiple sections or pieces spaced
apart, for example, by multiple gaps. The light conditioning
element is configured to provide enhanced illumination in a
sequential illumination method which will be discussed below. As
shown in FIG. 5(E), multiple gaps 518 or barriers are used to
separate the light conditioning element into multiple sections. The
barriers could comprise light blocking (e.g. opaque) ribs or
portions inside the light channel, or light absorbing strips or
portions in the inner surface of the light conditioning element, to
have same optical effects. For example, the light conditioning
element may include four equal sized sections. The separations
between the sections prevent the light from entering one section of
light conditioning element from another. These separations may
comprise air gaps or may be filled with material such as opaque
material or a combination thereof. In various embodiments, the
locations and numbers of the sections may correspond to the numbers
of light emitting elements used in sequential illumination method.
For example, the arrangement of the light conditioning element
shown in the FIGS. 5(C) and 5(E) is configured to work with the
illumination system with 4 light emitting elements. Although the
light conditioning element is shown to have four sections, the
light conditioning element may comprise more or less sections or
pieces. Although equal size sections are shown in FIG. 5(E), in
some embodiments, sections having unequal size may be used. Also,
although FIG. 5(E) shows four completely separate pieces, in some
embodiments elongate slits can separate the sections but the light
conditioning element may nevertheless comprise a single unitary
piece, the four sections being defined by slits that do not
completely separate the sections into separate pieces. Similarly,
various combinations may be employed. For example, the light
conditioning element may comprise two pieces, each having such a
slit thereby providing two separate sections per piece for a total
of four sections, and other configurations are also possible.
[0101] The light conditioning element may take many different
forms, yet still produce the same or similar results in various
embodiments. Some embodiments of the light conditioning element are
schematically illustrated in FIG. 6(A) and FIG. 6(B). The light
conditioning element 605 may comprise solid optically transmissive
or transparent material (which may comprise glass or plastic) with
two side surfaces, an inner surface 641 and an outer surface 642,
at least one comprising a multi-segment surface. The light
conditioning element 605 comprises a light channel 630 formed by
the two side surfaces 641, 642 of the solid optically transparent
material, where the inner surface 641 may contact the side surface
of the imaging lens. This light channel 630 within the light
conditioning element 605 may be referred to as an internal channel.
Light from the light source travels in the internal light channel
within the solid optically transparent material. The multi-segment
surfaces may include both reflective and refractive segments. In
certain embodiments, two segments 606 and 608 are coated with
optically reflective coating, while the remaining segments 607 is
polished and optically transmissive. If the index of refraction of
the solid optical transparent material is sufficiently high with
respect to the surrounding medium or media, the reflective coating
on the segments 606 or 608 may not be employed in various
embodiments as light may be reflected by total internal reflection.
Accordingly, the inner surface of the light conditioning element
and the outer surface of the imaging lens are spaced apart by an
air gap having a thickness less than or equal to 0.3 mm, 0.2 mm,
0.15 mm, 0.1 mm, or 0.05 mm and larger than zero or ranges
therebetween, such as for example, between 0.3 and 0.1 mm or
between 0.15 mm and 0.05 mm, etc. in certain embodiments of the
invention. Separations outside these ranges are also possible. The
outer side surface 604 of the imaging lens may be coated with
optically absorptive material to absorb the stray light and/or
reflective material in various embodiments. Either or both the
light channel element and imaging lens may include one or more
coatings that provide reflectivity and/or absorption.
[0102] In various embodiments, light from the light source enters
the light conditioning element 605 when the light source is
disposed against the light conditioning element 605 or light is
directed into the light condition element using a lens, optical
fiber, or other device. Some portion of the light may be blocked by
the edge 607 of the reflective segment of the surface 608. In
various embodiments, the majority of the light enters the internal
light channel 630 formed by two multi-segment surfaces 606 and 608.
For example, the surface 606 may comprise two segments 641 and 643
of the surface. In certain embodiments, a portion of the light,
which is reflected by surface 606 and then by the surface 608 and
then the surface 606 again, exits near the inner edge 611 of the
light channel and is projected onto the first area 612 of the
retina after passing through the optical window 601 and the cornea
602. A portion of the light, which is reflected by the surface 606
and then by the surface 608, exits near the outer edge 609 of the
light conditioning element 605 and is used to illuminate a second
area 610 of the retina across the optical axis 614 of the eye and
the imaging system in some embodiments. A portion of the light,
which is reflected by reflective surface 606 only once, may be
projected onto the retinal between the first area and the second
area. In various embodiments the first area of a retina of the eye
includes the optical axis of the optical imaging system. This first
area may comprise one-third of the field of view of the optical
imaging system. When the optical axis of the optical imaging system
is aligned with the optical axis of the eye, the first area is the
central area of the retina of the eye. The second area of a retina
of the eye is away from the optical axis and may be on an opposite
side of the optical axis from the outer edge of the light channel
from which the light is ejected. The second area is farther from
the optical axis than two-third of the field of view of the imaging
system. When the optical axis of the optical imaging system is
aligned with the optical axis of the eye, the second area is the
peripheral area of the retina. In certain embodiments, the optical
arrangement for the illumination and the imaging paths on the
cornea and the anterior surface of the crystalline lens of the eye
is similar as shown in FIG. 5(A) and FIG. 5(B). In some
embodiments, the light conditioning element including an internal
light channel comprises a multi-piece device that includes multiple
sections (and possibly gaps therebetween) such as illustrated in
FIG. 5(E) to provide better illumination when a sequential
illumination method is used.
[0103] FIG. 7(A) schematically illustrates some alternative
embodiments of the light conditioning element providing a hollow
external light channel and a solid internal light channel. FIG.
7(B) shows the close-up view of another embodiment of the light
conditioning element 706 with multi-segment surfaces. The hollow
external light channel 730 includes an inner reflective surface 705
formed by a side surface of the imaging lens and an outer
multi-segment surface 707, 715 and 708 on the inner surface of the
optical transparent material forming the light conditioning element
706. The light conditioning element 706 comprises a main body
comprising optical transmissive or transparent material having an
inner multi-segment surface 707, 715 and 708 and an outer
multi-segment surface that together forms the internal light
channel 731. In various embodiments, the inner multi-segment
surface comprises segments of the surface 707 and 715 that are
coated with a reflective coating such that the surfaces are
reflective from both sides. Reflective coating may be employed in
some embodiments when the index of refraction of the light
conditioning element is low such that the total internal refraction
is not sufficient. Reflective coating could also be employed when
the refractive index is high. Additionally, in some embodiments the
light conditioning element or portions thereof are coated with
absorbing material to reduce stray light. In certain embodiments,
the absorptive coating comprises epoxy with an index of refraction
similar to that of the light conditioning element and with an added
black absorptive dye. The remaining segments of the multi-segment
surfaces are polished optically clear. The side surface of the
imaging lens has a first layer of optically absorptive material 704
and a second layer of an optically reflective coating 705 thereon.
The absorptive coating 704 is used to absorb the stray light inside
the imaging lens while the reflective coating 705 is used to direct
the light propagating within the external light channel 730.
[0104] After entering the light conditioning element 706, some
portion of the light from the light source passes through the
refractive segment 708 of the light conditioning element 706 and is
reflected multiple times by two reflective surfaces 705 and 707. In
various embodiments, a portion of the light is reflected by the
coated outer sidewall surface 705 on the imaging lens first, then
reflected by the inner multi-segment surface 707 of the light
conditioning element, and then reflected by the coated outer
sidewall surface 705 of the imaging lens again, exits near the
inner edge 711 of the external light channel 730 and is eventually
projected on to the first area 712 of the retina. Another portion
of the light (not shown), which is reflected by the coated outer
sidewall surface 705 of imaging lens only once, exits the external
light channel 730 and is projected to the retina between the first
area 712 and the second area 710. As in various embodiments, a
portion of the light, which enters the internal light channel 731
of the light conditioning element 706 from the light source, is
split into two parts. As shown in FIG. 7(A), a portion of light may
be reflected by the inner surface 707 of the light conditioning
element 706 before exiting the outer edge 709, while another
portion of the light may directly exit the device 706 at the outer
edge 709 of the light conditioning element 706 without reflection
from the sidewalls thereof. Light exiting from the outer edge 709
as illustrated by rays in FIG. 7(A) may be directed toward the
second area 710 of the retina. The first area 712 of a retina of
the eye includes an optical axis of the optical imaging system. The
first area 712 comprises one-third of the field of view of the
optical imaging system. When the optical axis 714 of the optical
imaging system is aligned with the optical axis of the eye, the
first area is the central area of the retina of the eye. The second
area 710 of a retina of the eye is away from the optical axis 714
and on an opposite side of the optical axis from the outer edge of
the light channel from which the light is ejected. The second area
710 is farther from the optical axis 714 than two-third of the
field of view of the imaging system. When the optical axis 714 of
the optical imaging system is aligned with the optical axis of the
eye, the second area is the peripheral area of the retina. The
optical arrangement for the illumination and imaging paths on the
optical window 701 and crystalline lens of the eye is similar as
shown in FIG. 5(A) and FIG. 5(B). In some embodiments, the light
conditioning element may comprise be a multiple pieces device, as
shown in FIG. 5(E), comprising multiple section and multiple
separations (e.g., air or material filed gaps) therebetween to
sequentially provide different illumination patterns on the retina
when a sequential illumination method is employed.
[0105] Various embodiments discussed above disclose a method of
imaging an eye. The method comprises activating a light source to
illuminate an eye, conditioning the light from the light source by
a light conditioning element having at least one multi-segment
surface and directing the conditioned light into the eye and onto
the retina thereof, imaging the eye through an optical imaging
system using light reflected from the retina, and receiving an
image of the eye formed by the optical imaging system on an image
sensor. The light conditioning element with a multi-segment surface
is configured to receive light from the light source and direct
light to the eye in an illumination pattern that, in various
embodiments provide for illumination of peripheral sections of the
retina. In some embodiments, the light conditioning element splits
the light from the light source into different portions by
reflection (e.g. total internal reflection) from and/or refraction
caused by the multi-segment surface. The light conditioning element
may be configured to direct a first portion of light from an inner
edge of the light channel to a central area of a retina near an
optical axis of the eye imaging apparatus, and direct a second
portion of light from an outer edge of the light channel to a
peripheral area of the retina away from the optical axis. To
overcome the problems of scattering from the cornea and the
anterior surface of the crystalline lens, the light conditioning
element with a multi-segment surface may be configured to direct
the light such that the light primarily falls outside the imaging
path of the optical imaging system at the cornea and the anterior
surface of a crystalline lens of the eye.
[0106] A variety of different types of optical windows may be used.
As illustrated in FIG. 7(A), for example, the optical window has an
open central aperture through which a front end portion of the
imaging lens fits into. The optical window comprises annular or
ring-shaped transmissive or transparent body. Light rays from the
conditioning element pass through the annular body of the window.
Light returned from the retina passes through the open central
aperture into the imaging lens. The body of the optical window has
front and rear curved surfaces. The front curved surface is concave
and has a curvature to match the curvature of an eye, such as a
human eye, so as to fit on the surface of the cornea. The rear
surface, which is on the opposite side and farther from the eye,
has a convex surface, although in other embodiments other shapes
surfaces may be employed for either or both the front and rear
surface of the optical window.
[0107] Although specific designs for the frontal optical window are
shown in FIG. 5(A), FIG. 5(B), FIG. 6(A) and FIG. 7(A), the light
conditioning element and the related illumination system discussed
in each embodiment may be used in combination with other types of
frontal optical windows.
[0108] FIG. 8 schematically illustrates one embodiment of the eye
imaging apparatus using light emitting elements as the light
sources. The light source of the eye imaging apparatus may emit
light in the visible spectrum, IR spectrum, near IR spectrum and/or
UV spectrum. In some embodiments, the light source may include a
plurality of light emitting elements. The light emitting elements
may include solid state light emitters such as light emitting
diodes and/or any other elements that are capable of emitting
light. The light emitting elements may be compact, highly efficient
and driven by low voltage. The light sources 803 may be placed
directly against the light conditioning element 802. The light
sources 803 may include the light emitting elements and the heat
sink which is used to disperse the heat generated by the solid
state emitting devices. The light from the light sources is
directed into the posterior segment of the eye through the light
conditioning element 802 and optical window 801 in the manner such
as discussed above. The light sources, together with the heat
sinks, are placed outside an inner casing or shell 806 which houses
the optical imaging system including at least part of the imaging
lens 804. This casing or shell may comprise, for example, a tube or
ring. The light sources are powered electrically through the
electric wires 805 laying along the outer surface of the casing
806. When the eye imaging apparatus comprises two separate modules
such as a front imaging module 825 and a main module 828, which are
separated at interface 815, one or more electric connectors 807 may
be used to interconnect the wires 805 in or on the front module 825
and the wires 808 in or on the main module 828. In various
embodiments, more sophisticated electronic drivers for the light
sources 803 may be housed in the main module 828 in the right side
of FIG. 8. The removable front imaging module 825, which is
configured to be in contact with the cornea, may be built with
various kinds of light emitting elements for a variety of
illumination requirements and applications. For example, a first
type of front imaging module may include light emitters having a
first wavelength range and a second type of front imaging module
may include light emitters having a second wavelength range
different from the first. The first type of front imaging module
can be interchanged with the second type of front imaging module or
vise versa, for different applications, when they are connected
with the main body 828 with common electric connector 807. A user
may select which type of front imaging and conveniently remove and
switch out the front imaging module 825 to another, which is
conveniently attached onto the main module 828 by the user. In
certain embodiments, the removable front imaging modules 825 may be
driven by the same standard electronic drivers in the main module
828 through the electrical interconnector 807. To prevent dust from
entering housings for the optics, two optical windows 809 and 810
may be used. In certain embodiments comprising a single unitary
housing, however, as opposed to separate front imaging and main
modules, the electric interconnection 807 and the optical window
809, 810 may be excluded.
[0109] In various embodiments, the location of the light sources
may be distributed evenly to provide uniform illumination on the
retina. The number of the light sources may vary, depending for
example on the particular application. FIG. 9 schematically
illustrates two embodiments of the distribution of the light
emitting elements, where a total of 8 and 4 light emitting
elements, respectively, are used. In one embodiment, the light
emitting elements 902 is mounted onto a heat sink 901 that
comprises a ring to increase its mass and heat dispersion
capability. There are 8 light emitting elements 902 spaced evenly
on the heat sink. The light emitting elements may be activated
sequentially or simultaneously or be activated in any desired
order. In various embodiments, the light emitting elements are also
synchronized with the shutter of the image sensor. Drivers and/or a
controller can be employed to control the timing of and/or sequence
of illumination. Although 4 and 8 light emitters are shown in FIG.
9, more or less number of light emitting elements may be used. In
some embodiments, sufficiently large numbers of emitters are
employed such that the light sources form a "linear" line source.
Such a "linear" line source may be curved and may form a ring
centered about the optical axis of the imaging system, for example,
in some embodiment. FIG. 9 shows an embodiment with 4 light
emitting devices 904, 905, 906, 907 at 0.degree., 90.degree.,
180.degree., and 270.degree.. positioned on an annular heat sink
903.
[0110] An eye imaging apparatus with a wide field of view that
employs sequential illumination as described herein is capable of
overcoming scattering problems, and thus obtaining high quality
images that are essentially glare or haze free. In some
embodiments, the eye imaging apparatus comprises a light source
disposed inside the housing wherein the light source comprises a
plurality of light emitting elements configured to illuminate
different portions of an eye time-sequentially. The image sensor is
configured to receive a plurality of images of the eye with a same
wide field of view through the optical imaging system while each
portion of the eye is illuminated time-sequentially. In various
embodiments, the eye imaging apparatus further comprises an image
processing unit configured to generate a set of instructions to
process the plurality of images to create a single clear image of
the eye. In some embodiments, the eye imaging apparatus further
comprises a memory configured to temporarily store the plurality of
images, and a computing and communication unit configured to
receive and transmit the plurality of images. The plurality of
images may be transferred to other computing devices or internet
based devices that include the image processing unit, which is
configured to generate a set of instructions to process the
plurality of images to create a single clear image.
[0111] FIG. 10 schematically illustrates the example images
acquired when the light emitting elements are activated
time-sequentially and the method used to enhance the image quality
according to various embodiments of the invention. A useful
illumination condition is created when the light emitting elements
are activated time-sequentially. For example, in an illumination
system with 4 light emitting elements, if only one light emitting
element is activated, then a first portion of the retina or the
posterior segment of eye has increased illumination in comparison
to other portions of the retina or posterior segment of the eye. At
a later time if a second light emitting element is activated, a
second portion of the retina or the posterior segment of eye has
increased illumination in comparison to other portions of the
retina or posterior segment of the eye including the first portion
Likewise at a later time if a third light emitting element is
activated, a third portion of the retina or the posterior segment
of eye has increased illumination in comparison to other portions
of the retina or posterior segment of the eye including the first
and second portions. Again, at a later time if a fourth light
emitting element is activated, a fourth portion of the retina or
the posterior segment of eye has increased illumination in
comparison to other portions of the retina or posterior segment of
the eye including the first, second, and third portions. In this
example, where the retina is divided into four such sections, each
of the four portions may be about 25% of the retina. However, in
other embodiments the portion with increased illumination may be
less than 50%, 40% or 30% but larger than 1%, 2%, 5%, 10% or 20% of
the eye. In some embodiments, this portion is between 20-30%. Other
values outside these ranges are also possible.
[0112] In various embodiments, this portion is on average
illuminated more than other portions of the eye and has an average
intensity greater than that of remaining portion or portions of the
retina or posterior segment of the eye. Accordingly, only a portion
of the example image 1001 acquired by the eye image apparatus is
shown as having increased illumination in FIG. 10. In the example
image 1001, the shaded area which is a bit larger than one quarter
1005 of the image has increased illuminated, while on average
remaining quarters 1002, 1003 and 1004 are as well illuminated
less. However, due to the unique scattering characteristic of the
eye, the scattered light by the eye may show up mostly in the
oppositely situated quarter 1003 in the form of haze or glare,
leaving a clear portion in the primarily illuminated quarter 1005.
The clear portion is essentially glare or haze free, or only has
negligible glare or haze. Accordingly the quarter 1005, the clear
portion, has substantially less glare or haze than the other
portion. The brightness of the illuminated area often gradually
decreases toward its boundary area 1006, while the brightness of
image in the quarter 1005 is relatively uniform and with proper
light exposure for the image sensor.
[0113] Accordingly, in various embodiments, the first portion
(approximately a quarter) 1005 of the retina or posterior segment
is illuminated, for example, by providing light from one of the
light emitting elements while the other light emitters remain
unactivated. Subsequently, another one of the light emitting
elements is activated. As the next light emitting element is
activated, the illuminated area is moved to be centered on another
portion such as another quarter 1002 of the retina or posterior
segment. Another image is captured. Next a third portion, for
example, quarter, 1003 is illuminated by activating another of the
light emitting elements. Finally, a fourth portion or quarter 1004
is illuminated by activating another of the light emitters and
another image is capture. In such an example, each of the emitters
is activated while the others remains unactivated. When all of the
4 light emitting elements are activated time-sequentially, 4 images
with different quarters having increased brightness and clear
portions are acquired.
[0114] The order of sequence can vary. Additionally, although
activation of only one emitter at a time was discussed above, in
certain embodiments, two are more light emitters are activated
during the same time period. Additionally, although an image can be
captured each time a different light source is activated, more than
one image may also be recorded. Also, activating the light emitting
element may comprise switching the light emitter on as compared to
being off or otherwise increasing optical output therefrom for
example significantly. Additionally, the light from the light
emitting elements may be blocked, impeded, attenuated or redirected
or otherwise modulated. In various embodiments, however, different
portions of the retina or posterior segment are selectively
illuminated more than other portions. The portion selected for
increased illumination can be changed so as to provide increased
illumination of the different portions at different times. Such
selective illumination can be synchronized with the images captured
at those times. Accordingly, images can be obtained at these
different times and used to produce a composite image that has less
haze and glare. In some embodiments, a driver and/or controller is
used to activate the light emitters, direct light from a selected
emitter or emitters and not from the others or otherwise
selectively modulate the emitters. In some embodiments, simply more
light from the selected emitter or emitters is provided in
comparison to the other emitter. In certain embodiments shutters,
light valves, and/or spatial light modulators are employed to
control the amount of light from each of the light emitting
elements. Although one emitter at a time was describe above as
being activated, more than one light emitter can be activated at a
time. In various embodiments, more light is provided by a subset of
the total number of emitters so as to illuminate a portion of the
retina or posterior segment or illuminate that portion more than
one or more other portions. An image is recorded. Subsequently, a
different subset of the total number of emitters is selected to
illuminate another portion of the retina or posterior segment or
illuminate that portion more than others. Another image is
recorded. This process can be repeated multiple times in various
embodiments. For example, 2, 3, 4 or more subsets may be selected
at different times or for providing the primary illumination.
Images of the eye may be obtained at the different times. These
images or at least portions of these images may be employed to form
a composite image of the eye, for example, of the retina and/or
posterior segment. Accordingly, in various embodiments an imaging
processing unit may be configured to generate a set of instructions
to process the plurality of images to create a single clear image
of the eye. Because the eye or the eye imaging apparatus may be
moved slightly during the image capturing or imaging process, the
plurality of images may not overlap precisely. The imaging
processing unit may generate instructions to precisely align the
plurality of images or portions thereof by analyzing the
overlapping areas. Each of the plurality of images has a clear
portion and an unclear portion. The clear portion of the image is
essentially glare free or haze free, or has negligible glare or
haze. The clear portion has substantially less glare or haze than
the other portion, the unclear portion. The unclear portion
exhibits glare or haze, which obscures the image. The imaging
processing unit may further generate instructions to recognize the
clear portion of an image in each of the plurality of images,
remove an unclear portion and save the clear portion. The set of
instructions may further include instructions to adjust the
uniformity of the image brightness of the single clear picture near
a border area to form a uniform brightness. The imaging processing
unit is configured to combine the plurality of images to create the
single clear image.
[0115] As shown in the example image 1001 in FIG. 10, for example,
in an illumination system with 4 light emitting elements, when the
quarter 1005 is well illuminated, the unclear portion of the image
with glare is outside the boundary 1007. The unclear portion may be
recognized and removed by a set of instructions from an image
processing unit. Therefore only the clear portion of the image
within the boundary 1007 is saved. Similarly, only the clear
portion of the image within the boundary 1008 is saved when the
quarter 1002 is well illuminated. Two additional images are
acquired from the quarter 1003, 1004 and their surrounding areas
which are within the boundaries 1009 and 1010, respectively. When
all of the 4 light emitting elements are activated
time-sequentially, 4 partial images are acquired.
[0116] Because the eye or the eye imaging apparatus may be moved
slightly during the imaging process, the features from the 4
partial images may not overlap precisely. The extended area from
the border of each quarter may be used to allow the proper
adjustment and re-alignment of the images as set forth by the
instructions from the imaging processing unit. After the 4 images
are aligned precisely, the brightness of the images in the border
area can be re-adjusted to produce one single clear image with
uniform brightness.
[0117] In some embodiments, in order to align the images taken time
sequentially, one or more additional images may be captured with
all of the light emitting elements activated at the same time, in
addition to the multiple images taken time-sequentially as
described above. This image can be obtained using the same optical
imaging system having the same field of view as was used to obtain
the plurality of images obtained with time-sequential illumination.
Although such image may be hazy or with glare, it may contain the
unique graphic reference features, such as blood vessels, of the
whole imaging area or the entire field of view. Using this image as
a reference image to coordinate, each of the four partial images
described above may be aligned with the reference image. The clear
composite image could then be formed from the four images after
proper adjustment of the locations.
[0118] Although in the example embodiment described above, a single
reference image was obtained with all the light emitters activated
to assist in alignment of the other images, in other embodiments
less than all light emitters may be illuminated. For example, the
light emitters for two quarters 1002, 1003 can be activated to
align those quarters. Similarly, the light emitters for the other
quarters 1004, 1005 can be activated to align those quarters.
Additional images with less than all the light emitters can be
activated to provide further alignment. For example, four reference
images captured while illuminating different pairs of the four
quarters may be used to align each of the four quarters and create
a complete composite image.
[0119] Less reference images can also be used, for example, by
illuminating more sections when capturing the reference image. In
some embodiments, for example, a first reference image can be
captured with three of the four quarters illuminated, and a second
reference images can be captured with different three of the four
quarters illuminated. Alignment can be provided using these first
and second reference images. Other variations are possible. As
discussed above, the number of sections illuminated and number of
light emitters used to obtain the one or more reference images can
vary.
[0120] Accordingly, one or more reference image can be employed to
align images of sections obtained using time-sequential
illumination. To generate a reference image, multiple sections are
illuminated and an image is capture by the optical imaging system
and sensor. This reference image will depict the sections and their
positional relationship, and will contain reference features that
can be used to align separate images of the separate sections.
Although reference images can be obtained by illuminating all of
the sections, not all the sections need to be illuminated at the
same time to produce reference images that can assist in alignment.
These reference images can be captured using the same optical
imaging system having the same field of view as was used to obtain
the plurality of images captured during time-sequential
illumination. However, in alternative embodiments, reference images
can be captured by other optical imaging systems and sensor.
Additionally, reference images can be captured with using different
fields-of-view. Other variations are possible.
[0121] An image processing unit may be utilized to process the
images as set forth above to provide alignment. For example, the
image processing unit may identify the reference features in the
reference images to determine the positional relationship of the
sections. The image processing unit may further align sections of
images captured using time sequential illumination based on those
reference features and the determined positional relationship of
the sections.
[0122] In various embodiments, the rate of frequency of the
time-sequential capturing is determined by the image capturing
rate. In some embodiments, the imaging apparatus is configured to
capture each image between 15 ms or 30 ms to 150 ms or 200 ms.
[0123] Accordingly, a method of imaging an eye by sequential
illumination is disclosed to obtain high quality retinal images
with a wide field of view. The method comprises activating a
plurality of light emitting elements time-sequentially to
illuminate different portions of an eye, imaging the eye through an
optical imaging system and receiving a plurality of images of the
eye through the optical imaging system and sensor while different
portions of the eye are illuminated time-sequentially. The images
are captured by the image sensor and processed to create a single
clear image of the eye. The method may be used to digitally remove
the unclear sections, thus reducing or removing the haze from the
plurality of images obtained from the sequential illumination.
[0124] The sequential illumination method discussed in the previous
paragraph may be applied when different numbers of the light
emitting elements are used. The possible examples include 2
elements, 3 elements, 4 elements, 6 elements, 8 elements or even
more elements. The light emitting elements need not be individually
activated. In some embodiment, pairs may be activated at a time.
Similarly, 3, 4, or more may be activated at a time. Other
variations are possible.
[0125] Accordingly various embodiments comprise an eye imaging
system comprising an eye imaging apparatus such as for example
shown in FIG. 1(A) and FIG. 1(B), and an image computing module
that includes another computing device or internet based device.
The eye imaging apparatus may comprise a plurality of light
emitting elements, an optical imaging system, an image sensor,
memory and a computing and communication unit. In certain
embodiments, the plurality of light emitting elements is configured
to illuminate different portions of an eye time-sequentially. The
image sensor is configured to receive a plurality of images of the
eye with a same wide field of view through the optical imaging
system as the different portions of the eye are illuminated
time-sequentially. In various, although not all embodiments, the
memory is configured to at least temporarily store the plurality of
images captured by the image sensor. The computing and
communication unit may be configured to receive and transmit the
plurality of images. The eye imaging apparatus may further include
a touch screen display to display the images. The image computing
module may be configured to receive the plurality of images from
and exchange data with the eye imaging apparatus. The image
computing module may further include an image processing unit,
which is configured to generate a set of instructions to process
the plurality of images to create a single clear image of the eye.
Other embodiments are also possible.
[0126] In some embodiments of the eye imaging apparatus, as
schematically illustrated in FIG. 11, one or more optical fibers
1105 are used to guide the light from the light emitting element(s)
1107 to the light conditioning element 1102. In various
embodiments, optical fiber bundles are used. The construction for
the rest of the imaging apparatus is similar to the one shown in
FIG. 8. When the eye imaging apparatus comprises two separate
modules such as a front imaging module and a main module, which are
separated at interface 1109, one or more electric connectors 1115
may be used to interconnect the wires 1108 in or on the front
module and the wires 1110 in or on the main module. To prevent dust
from entering the housings and depositing on the optics, two
optical windows 1111 and 1112 are used to seal off the housings. If
a single piece construction is required, then the electric
interconnection 1115 and the optical windows 1111, 1112 can be
excluded.
[0127] FIG. 12 schematically illustrates two embodiments of fiber
optic couplers configured to couple light from the light emitting
elements to the optical fiber. The optical fibers may be used to
form multiple lighting elements that can be disposed against the
light conditioning element. One example is schematically
illustrated in FIG. 12, where optical fiber lighting elements 1202,
1203, 1204 and 1205 are incorporated into a lighting base 1201 and
distributed evenly thereabout. The shape and size of each optical
fiber lighting element shown in FIG. 12 is an example only and does
other design can be employed. The number of the optical fiber
lighting elements may be 4, 8 or any other number of lighting
elements. As shown, continuous light sources, such as liner light
sources, may be provided.
[0128] The lighting element such as for example lighting element
1202 shown in FIG. 12, receive light from one light emitting
element. While two examples are shown in FIG. 12, other embodiments
may be used to increase the optical coupling efficiency. In one
embodiment, an optical coupling lens 1210 is used to collect light
from the light emitting element 1208 and relay the light into the
entrance of an optical fiber bundle 1211. The individual optical
fibers in the bundle 1211 is then spread out at the another end of
the fiber to form the lighting element. The light emitting element
often comprises a protective dome 1209 and is mounted onto a
ceramic or metal base 1207. The multiple light emitting elements
may be mounted to a larger heat sink base 1116, as shown in FIG.
11, through their ceramic/metal bases, in order to increase the
heat dispersion capability. The heat sink may also be in contact
with the lens housing or casing, which is shown as 1106 in FIG. 11
of the imaging apparatus in order to disperse the heat. If the heat
sink (ring) 1116 is built next to the interconnection surface 1109
as shown in FIG. 11, a pair of matching heat conducting surfaces
comprising for example copper or other materials having good
thermal conductivity may be built along the interconnection surface
1109, and as part of extension of lens housing 1106 and lens
housing 1117 in the front and main modules of the imaging
apparatus. When the removable front imaging module is attached to
the main module of the imaging apparatus, the two heat conducting
surfaces 1106, 1117 may contact each other, thus permitting
transfer of the heat from the lighting elements to the larger mass
in the main module. Such a design may reduce the temperature of the
imaging apparatus housing, especially the housing of the removable
front imaging module, which the user may employ to holds the
imaging apparatus in various embodiments.
[0129] Also shown in FIG. 12, in some embodiments, the optical
fiber bundle 1215 is directly inserted into the dome 1214 of the
light emitting element 1213. The direct coupling may produce high
efficiency, although the seal for the dome is penetrated which may
have implications in certain situations.
[0130] In yet another embodiment shown in FIG. 13, the light
emitting element 1308 is disposed in the main module of the eye
imaging apparatus. The light is then guided to the light
conditioning element 1302 through an optical fiber bundle 1305,
which forms the new lighting element 1303. If the front imaging
module is removable, then an optical coupler 1307 may be added to
couple light from one side of interconnection 1311 to another. In
certain embodiments, for example, two fiber bundles are aligned to
each other, a first on the main module and a second on the front
modules. The fiber bundles can be disposed so as to have ends that
are in direct contact such that light can be coupled from the first
fiber bundle into the second fiber bundle. The power of the
lighting element 1303 is supplied through the electric wires 1309
by the electronic drivers.
[0131] Another coupling design is schematically illustrated in FIG.
14. A light emitting element 1407 is located in the main module of
the eye imaging apparatus, but near the interconnection interface
1411. The light is coupled into an end of an optical fiber bundle
1405, which is located in the removable front imaging module of the
imaging apparatus, with the end of the optical fiber bundle being
exposed to the outside and facing the light emitting element 1407.
The optical fibers in the bundle 1405, extend along the outside of
the lens housing or casing 1406 and are used to form the multiple
lighting elements 1403. The power of the light emitting element
1407 may be supplied through the electric wires 1408 from the
electronic drivers.
[0132] One embodiment of the optical coupling design is shown in
FIG. 15, where the dash line 1506 represents the interconnection
interface between the two modules of the imaging apparatus. In
various embodiments, the light from the light emitting element 1502
is initially collimated by a dome lens 1503. The collimated light
is coupled to the fiber optical bundle 1507 through a coupling lens
1504. The light emitting element has a base 1501 that is mounted
onto a heat sink base in the main module of the imaging apparatus.
The coupling optical lens 1504 is also mounted in the main module
and can be pre-aligned with the light emitting element 1502.
Because the optical fiber bundle 1507 is located in the removable
front imaging module of the imaging apparatus and does not come
into physical contact with optics in the main module, the light
1505 is projected into the end of the fiber bundle directly through
air or via free space. Such arrangement not only increases the
optical coupling efficiency of the light, but also reduces wear at
the end of the optical fiber bundles.
[0133] The light emitting elements in various embodiments may emit
the light with broadband spectrum or narrow band spectrum. The
light may be visible to the human eye with a single color or
broadband, for example, a white color. The light may also be
invisible to the human eye and be, for example, in the infrared,
near infrared or UV range. All of the light emitting elements used
in one unit may emit the same kind of light or different kinds of
light.
[0134] In various embodiments, the light emitting elements emit
white color light for color imaging applications. However, for
certain applications, the light emitting elements may emit light in
deep blue color, for example, when driven by the same electrical
power supply system from the main module. The blue light may excite
the fluorescin dye in the blood vessels of the eye, which in turn
may emit green light. In certain embodiments, the optical window at
the end of the removable front imaging module, such as 809 in FIG.
8, 1111 in FIG. 11, 1310 in FIG. 13 and 1409 in FIG. 14, which is
used to protect the optics from dust, comprises an optical blocking
filter. For example, a green band pass filter may be employed. In
such embodiments, the green emission light may be collected by the
optics in the main module to form an image of fluoresin angiogram.
The optical blocking filter reflects/absorbs the blue light, but
allows the green and/or other emission light to be transmitted. The
removable front imaging module with such features may be
constructed as a fluoresin angiogram unit. Similarly, another type
of angiogram imaging apparatus may be formed when the light
emitting elements emit near infrared light and the optical blocking
filter works in such spectrum too (for example, filters out near IE
light). Accordingly, a filter that blocks the light produced by the
emitters but transmits other, for example, longer, wavelengths, may
be used to transmit fluorescent or other emission to the optical
sensor.
[0135] Because the optical window in the eye imaging apparatus is
configured to be in contact with the patients, adequate sealing
around the peripheral joint between the optical window and the
housing can assist in reducing or preventing cross-contamination by
the bacteria. FIG. 16 schematically illustrates one embodiment of a
hermetically sealed eye imaging apparatus where the optical window
may be dropped in from inside the housing during the assembly
process. The optical window 1601 is in contact with the cornea 1602
of eye, but separated from the imaging lens 1603 with a small gap
1606. In various embodiments, the surfaces of the optical window
1601 and the imaging lens 1603 on both sides of the gap 1606 may
have the same or similar radius of curvature. The gap 1606 may be
filled with air or other optically transparent but mechanically
elastic materials during the subsequent assembling process. Optical
coatings may be applied to the optical surfaces on the both sides
of the gap 1606 to reduce the optical reflectivity. The gap 1606
not only allows application of more sophisticated sealing
technologies, but also adds a space for compensating for thermal
expansion. In various embodiments, the gap 1606 between the optical
window and the imaging lens adjacent thereto, for example, at the
optical axis of the imaging lens, is between about 0.5 mm and 0.001
mm, or 0.3 mm and 0.001 mm although values outside this range are
possible. The periphery of the imaging lens 1603 may be a conical
or frusto-conical shape and may be coated with optically absorptive
material 1607. The absorption spectrum of the optically absorptive
material 1607 may be in the visible spectral range of the eye
although the absorption spectrum may also extend into the invisible
spectra. The absorptive coating 1607 may not only prevent the light
from entering the imaging lens from outside, but also absorb the
stray light from the eye when this light enters the imaging lens
1603 along with the light used for forming an image. A small opaque
absorption ring 1608 may be added to the edge of the gap 1606 to
prevent the light from entering the gap from the sides. The edge of
the gap 1606 may also be simply filled with a small amount of
optically absorptive material. The optical window 1601 is aligned
with the rest of imaging optics with the help of the apparatus
housing 1640, while the proper gap 1606 is maintained as a
result.
[0136] The housing 1640 of the eye imaging apparatus comprise metal
or other materials. The housing 1640 has a front end 1630 extends
around the edge of the optical window 1601. The front end 1630 has
a smooth front edge 1609 to prevent injury to the patients during
the operation and to protect the optical window 1601 from
scratching by hard foreign objects. A small flat surface 1610, in
the form of a circular ring, may be disposed on the front
peripheral area of the optical window 1601. This small flat surface
1610 may be near and/or extend from the side of the optical window
1601 to or near to the edge of the front concave surface of the
optical window 1601. The front end 1630 of the housing 1640 is
shaped and sized to fit with the profile of the optical window 1601
at the edge of the optical window, as shown in FIG. 16, and in
various embodiments allows for various gaps between the housing
1640 and the optical window 1601. In various embodiments, an inner
side surface 1650 of the housing 1640 comprises an alignment edge
1611 and a reservoir edge 1612 at the front end 1630. The optical
window is separated from the alignment edge with a first gap which
is horizontal and parallel to the side surface of the optical
window. In various embodiments, the width of the first gap is
between 0.3 mm and 0.01 mm or 0.2 mm and 0.01 mm. The alignment
edge 1611 assists precision alignment of the optical window 1601
with the housing 1604 in directions normal to the optical axis. In
various embodiments, the housing has an opening for fitting the
optical window therein from the right hand side, as shown in FIG.
16, and for providing a gap, the first gap, between the optical
window and the housing.
[0137] In some embodiments, the housing 1640 comprises a distal
section 1604, which is a small housing, and a proximal section
1605, which is the apparatus housing. The proximal section comprise
metal or other materials. The distal section, which may be a small
housing, comprising the same or different metal material, in some
embodiments, is connected to the proximal section 1605 by a bond.
When the small housing 1604 is aligned with the apparatus housing
1605, then the optical window 1601, may, for example, be properly
aligned with the optical axis of the imaging lens and imaging
system. In various embodiments, the first gap provides for flow of
hermetical sealing material as is discussed below. The opening
bounded by the alignment edge of the housing is sufficiently large
such that after the optical window is centered and aligned, the
small first gap remains disposed between the housing and the window
to allow for hermetic sealing material. To assist in placement of
the optical window 1601 precisely along the optical axis and
maintain a proper gap 1606, a small vertical surface is made in the
frontal end 1630 of housing 1604, which creates a vertical gap 1633
between the housing and the small flat surface 1610 on the front
peripheral area of the optical window 1601. In various embodiments,
the width of the vertical gap is about between 0.3 mm and 0.01 mm
or 0.2 mm and 0.01 mm. This vertical gap 1633 may permit the flow
of hermetic material between housing and the small flat surface
1610 on the front peripheral area of the optical window 1601.
[0138] The optical window is also separated from the reservoir edge
1612 with a second gap. In various embodiments, the width of the
second gap is about between 1.0 mm and 0.3 mm or 0.5 mm and 0.3 mm.
The second gap may be larger than the first gap and configured to
be a reservoir to be filled with a hermetic sealing material 1613.
In various embodiments, when the hermetic sealing materials 1613 is
melted under high temperature, the hermetic sealing material under
the effect of gravity and surface tension force, also fills the
smaller gaps, such as the first gap as well as the vertical gap
between housing and the small flat surface 1610 on the front
peripheral area of the optical window 1601 between the optical
window 1601 and the housing 1640 to provide an air tight seal and
strong bonding. The hermetic sealing material comprise material
such as ceramic or metal that can, for example, be melted at very
high temperatures and be caused to form an airtight seal that
remains intact even when subjected to autoclave temperatures such
as for example 120.degree. C., 135.degree. C., 140.degree. C., or
temperatures therebetween or potentially higher.
[0139] As illustrated, the front end 1630 of the housing 1640 where
the optical window 1601 is disposed has vertical and horizontal
edges, that with the help of an alignment fixture during
manufacture and hermetic sealing material in the vertical and first
gap, permit horizontal and vertical alignment, positioning, and
proper orientation of the optical window in the imaging system. In
this particular case, such vertical and horizontal edges of the
housing form a corner in which the window surrounded by hermetic
sealing material fits.
[0140] To match the thermal expansion properties of optical window
material and the housing 1640, a special material may be used for
the distal section 1604 of the housing 1640. In some embodiments,
the whole housing 1640 may be made of the same material. In some
embodiments, different materials may be used to make the housing.
In various embodiments, the housing may comprise a distal section
1604, for example, a cap, and a proximal section 1605. The distal
section 1604 is connected with the proximal section 1605 by a joint
section 1613. In certain embodiments, for example, the distal
section 1604, may comprise a first material such as titanium and
the more proximal section 1605 of the housing comprises a second
material such as aluminum. In certain embodiments, a distal section
1604 of the housing may be welded, bonded or otherwise connected
together with a more proximal section of the housing 1605 at a
joint section 1613. In various embodiments, the distal section of
the housing can be bonded together with special treatment, such as
explosion welding, to a portion of the joint section 1613
comprising the same material as the proximal section of the
housing, the second material. For example, in the case where the
distal section 1604 comprises titanium (first material) and the
more proximal section comprises aluminum (second material), the
joint section 1613 may comprise the aluminum (the second material).
This aluminum (second material) in the joint section 1613 is bonded
to the titanium (first material) using, for example, explosion
bonding. The aluminum (second material) in the joint section is
then bonded to the aluminum (second material) in the more proximal
section of the housing using for example laser welding. Other
approaches to connecting the more distal and more proximal sections
of the housing may be employed. In some embodiments, for example,
the connection between the distal section 1604 of the housing and
the more proximal section 1605 of the housing is filled with a
hermetically sealing material. The material for the hermetically
sealing could be, e.g., glass, ceramic, metal or adhesives. Such a
technique may be employed, in some embodiments where the distal
section of the housing comprises a different material than the more
proximal section of the housing. In some embodiments, a special
bonding section is introduced at the joint section 1613 in the form
of a thin ring, which comprises two different materials. The front
surface of the thin ring comprises the first material that may be
welded with the distal section 1604, while rear surface of the thin
ring comprises the second material that is then welded with the
more proximal section 1605. The two materials (first material and
second material) in the thin ring are bonded together with special
bonding technique, such as explosion welding. In some embodiments,
the distal section 1604 may simply be glued to the more proximal
section 1605.
[0141] As illustrated in FIG. 16, as well as elsewhere (see, e.g.,
FIG. 1) in various embodiments, the housing is tapered and reduces
in size closer to where the optical window is disposed and where
contact with the eye/cornea is made. This tapered or sloping
profile of the housing accommodates both the larger size of the
relay lens and the smaller size of the window and imaging lens. As
discussed above, the imaging lens may be frusto-conical and
likewise be tapered as well, with the aperture size of the imaging
lens being smaller closer to the eye than farther from the eye. In
various embodiments, as shown in FIG. 16 and elsewhere, the bond,
weld, or joint discussed above may be included in the front end
where the housing is tapered.
[0142] In some embodiments a washer made of the same material as
that of housing 1605 is included in the housing between the joint
section 1613 and the proximal section 1605. The thickness of the
washer is adjustable and permits the length of the housing in the
longitudinal direction to be adjusted, which in turn controls the
gap 1606 ultimately.
[0143] FIG. 17 illustrates another embodiment of a hermetically
sealed eye imaging apparatus. In this embodiment, the shape of the
small housing, or the distal section, next to the optical window is
modified from that in the embodiment shown in FIG. 16. The gap 1721
between the alignment edge 1711 and the edge of the optical window
1701 is reduced, which can provide both more precise optical
alignment and a sufficient space to allow the free flowing of the
hermetical sealing material from the reservoir 1713 through the
narrow gap at the same time. The narrow vertical gap 1633 between
the housing and the flat surface 1610 on the front peripheral area
of the optical window 1601 shown in the FIG. 16 is removed. The
removal of this narrow vertical gap 1633 and the full filling of
the narrow gap 1721 between the alignment edge 1711 and optical
window 1701 with the hermetical sealing material reduces risk of
contamination problems. If the narrow vertical gap 1633 is not
fully filled, for example the bacteria and other contaminants may
hide inside and cause cross contamination between the patients.
[0144] As discussed above with respect to FIG. 16, in various
embodiments, the housing shown in FIG. 17 has an opening for
fitting the optical window therein and for providing a gap, the
first small gap, between the optical window and the housing. Having
such opening and a gap permits the optical window to be laterally
translated and aligned, for example, using an alignment fixture
that moves the lens laterally with respect to the housing. The
optical window, may, for example, then be properly aligned with the
optical axis of the imaging lens and imaging system when the
housing is aligned with the rest of the imaging system. The first
gap permits this lateral movement and alignment. Additionally, this
first gap provides for flow of hermetical sealing material.
Accordingly, the opening in the housing is sufficiently larger such
that after the optical window is centered and aligned, the small
first gap remains disposed between the housing and the window to
allow for filling with the hermetic sealing material.
[0145] The optical window is also separated from the reservoir edge
1712 of the housing with a second larger gap 1722. The second gap
1722 may be larger than the first gap 1721 and configured to be a
reservoir to be filled with a hermetic sealing material 1713. In
various embodiments, when the hermetic sealing materials 1713 is
melted under high temperature, the hermetic sealing material also
fills the smaller gap 1721 between housing and the optical window
1701 to provide an air tight seal and strong bond. The hermetic
sealing material 1713 may comprise material such as glass, ceramic
or metal that can, for example, be melted at very high
temperatures, for example, larger than 500.degree. C. and caused to
form an airtight seal that remains intact even when subjected to
autoclave temperatures such as for example 120.degree. C.,
135.degree. C., 140.degree. C., or temperatures therebetween or
potentially higher.
[0146] As discussed above, during the sealing operation, the
alignment fixture holds the window into the center of opening of
the housing where the window is inserted and, in certain
embodiments, preserves a uniform gap around the periphery of the
window. The alignment fixture also sets proper recess depth for the
optical window by the small flat surface 1710 in reference to the
front end 1724 of the small housing 1704, along the optical axis of
the optical window. The viscosity of the hermetic material may be
controlled so that the hermetic material wets both the window and
the housing surface next to the gap and fills the first gap 1721
from the reservoir 1722, under the gravity and surface tension
force. In various embodiments, the first gap 1721, which may be
filled with hermetical sealing material 1713, is less than 1 mm or
less than 0.2 mm although values outside this range are possible.
In some embodiments, the thickness of first gap 1721 is made larger
when approaching the space on the eye side, by the design of larger
opening for the alignment edge 1711 and/or small 45 degree chamfer
at the corner of optical window edge. As a result, when hermetic
material is flowed through the first gap 1721, from the second gap
1722, the surface tension of the hermetic material will limit or
stop the flow of the hermetic material into other surfaces on the
eye side. In certain embodiments, the sealant not only seals the
window, but also holds the window in the center of the opening of
the housing.
[0147] FIG. 18 schematically illustrates another embodiment of the
hermetically sealed eye imaging apparatus. In this embodiment, a
plurality of tiny balls 1814 are disposed with equal space around
the periphery of the optical window and inside a plurality of bores
1815. The optical window 1801 is separated from an alignment edge
1811 of the housing with a first gap 1821. The optical window is
also separated from a reservoir edge 1812 of the housing with a
second larger gap 1822. This gap 1822 is configured to be the
reservoir for the hermetically sealing material 1813. The balls
1814 are disposed in bores or boreholes 1815 drilled in the inner
surface of the front end of the housing to accommodate the balls
1814. The bores 1815 have a diameter slightly larger than the
second gap 1822 in order to enlarge the second gap 1822. Because of
the increased size of the borehole 1815, the second gap 1822 is
larger in the area surrounding the ball than in other areas where
the ball 1814 is not positioned. The bore holes 1815 are disposed
at a sufficient height such that a very narrow gap 1823 is disposed
between the ball 1814 and the optical window 1801. This gap 1823 is
beneath the ball 1814 as illustrated in the cross-sectional shown
in FIG. 18. This narrow gap 1823 beneath the ball 1814 is narrower
than the first gap 1821.
[0148] Such arrangement as describe above using balls 1814 as
spacers with a gap between the ball 1814 and the optical window
1801 facilitates precise alignment between the optical window 1801
and the housing 1804. As discussed above, the housing has an
opening for fitting the optical window therein and for providing
the first and second gaps and in particular, the small gap 1823
between the optical window 1801 and the ball 1814 when the ball
1814 is in place in a borehole 1815. Having a larger opening and a
gap permits the optical window to be laterally translated and
aligned, for example, using an alignment fixture that moves the
lens laterally with respect to the housing. The optical window 1801
may, for example, be properly aligned with the optical axis of the
imaging lens and imaging system when the housing is aligned with
the rest of imaging system. The small 1823 gap permits this lateral
movement and more precise alignment.
[0149] Additionally, this small gap 1823 provides for flow of
hermetical sealing material. Accordingly, the opening in the
housing is sufficiently larger such that after the optical window
1801 is centered and aligned, the small gap 1823 remains disposed
between the housing and the window 1801 to allow for hermetic
sealing material 1813. A slightly larger gap 1821 between the edge
of the optical window 1801 and the alignment edge 1811 of the
housing (as compared for example to the first gap 1711 shown in the
embodiment illustrated in FIG. 17) makes it easier for the
hermetically sealing material 1813 from the reservoir 1822 to fully
fill the gaps and space around the tiny balls 1814. As discussed
above, in various embodiments, when the hermetic sealing materials
1813 is melted under high temperature, the hermetic sealing
material 1813 also fills the smaller gap 1823 between balls 1814
and the optical window 1801 to provide an air tight seal and strong
bond. The melted hermetic sealing material also forms a hermetic
seal in portions of the larger gap 1822 elsewhere around the balls
1814 as well as where the balls 1814 are not disposed. The hermetic
sealing material 1813 comprise material such as glass, ceramic or
metal that can, for example, be melted at very high temperatures
and caused to form an airtight seal that remains intact even when
subjected to autoclave temperatures such as for example 120.degree.
C., 135.degree. C., 140.degree. C., or temperatures therebetween or
potentially higher.
[0150] The layout with 3 and 4 balls are demonstrated in FIG. 18.
These layouts show the arrangement of the balls, for example, as
seen from the inside of the housing. These layouts, however, are to
schematically illustrate where the balls are placed relative to
each other. The number of the balls may vary including 3, 4, and
other numbers. The spacer may be for example 0.5 mm in lateral
extent such as diameter. Larger or smaller spacers may be used. The
spacer, for example, may be as large as 1.0 mm and possibly 0.3 mm
or smaller or any size between these values. Other sizes outside
these ranges may also be possible. The spacers may comprise for
example sapphire in some embodiments although other materials may
be employed. In some embodiments, the balls may comprise the same
material as the housing 1804 and/or the optical window 1801. The
balls 1814 may also comprise materials that have a similar thermal
expansion property as the optical window 1801 and/or the housing
1804. Spacer having shapes other than spheres can be employed.
Cylindrically shaped spacers, for example, may be used.
Additionally, the spacing can be different than shown in FIG. 18
and need not be evenly spaced.
[0151] In various embodiments, the diameter of the spacer, e.g.,
the ball, is selected to be slightly larger than the second gap.
Therefore, when the bore is drilled, the outer edge of the bore
extends beyond the outer edge of the second gap. Such arrangement
prevents the balls from moving from of their location (e.g., in the
bores) during the alignment and sealing operation. When the ball
1814 is placed in the bore 1815 and the window 1801 is inserted, a
first side of the ball and the edge of the window provide the small
gap 1823 while the second opposite side of the ball contacts the
outer wall of the bore 1815. In various embodiments, the addition
of the balls effectively reduces the space between the window 1801
and the housing 1804, and allows the hermetic material 1813 to flow
easily in the large gap and the space between the balls. Also, with
the spherical shape of the ball, the width of the first gap 1823 is
widened on side facing the reservoir 1822 than the opposite side.
As the result, the material can easily wet the surface of the ball
and surround the ball within the material when the material is
still in the fluid state.
[0152] FIG. 19 demonstrates another embodiment of a hermetically
sealed eye imaging apparatus where the optical window may be
dropped in from the front side (eye side) during the assembly
process. The hermetic sealing is applied between the optical window
1901 and the housing 1904. The embodiment has similar components as
the embodiment shown in FIG. 16. For example, the imaging lens
1903, the absorptive coating 1907, the absorptive material 1908 and
the gap 1906 function similarly as the imaging lens 1603, the
absorptive coating 1607, the absorptive material 1608 and the gap
1606 respectively. Special bonding or welding process and design
can be applied to the joint section 1913 in the embodiment shown in
FIG. 19, as the joint section 1613 shown in FIG. 16. The optical
window 1901 has a small flat surface 1910 disposed about the edge
or periphery of the front concave surface of the optical window
1901. The use of the smooth corner 1909 at the front end of housing
1904 prevents potential injury to the patients during the
operation. The optical window 1901 is designed to be dropped into
the housing 1904 from the front side. A small alignment ring or
edge 1911 is built into the housing 1904. The alignment ring 1911
includes a corner in which the edge of the optical window 1901
contacts. In various embodiments, the dimensions of the alignment
ring 1911, and in particular the shape and size of the corner of
the alignment ring 1911 are sufficiently similar to that of the
edge of the optical window 1901 to provide a tight fit
therebetween. As illustrated, the alignment ring 1911 has vertical
and horizontal edges that permit horizontal and vertical alignment,
positioning, and proper orientation of the optical window in the
imaging system. In this particular case, such vertical and
horizontal edges of the housing form a corner in which the window
1901 fits. Accordingly, the small alignment ring 1911 provides more
precise alignment between the two components in comparison to an
embodiment without the alignment ring. The larger gap between the
two components is filled with the hermetically sealing material
1912 under high temperature. Such design not only provides air
tight sealing to prevent growth of the bacteria in the small gap or
cracks, but also enables strong bonding between the optical window
1901 and the housing 1904. An adhesive may also be used to seal the
optical window 1901 in this embodiment.
[0153] FIG. 20 schematically illustrates another embodiment of the
imaging apparatus where an adhesive and/or a hermetically sealing
material may be used to seal the optical window. The housing 2004
of the front module housing is constructed with one single piece
although a multi-piece front module housing may be employed as
well. The designs for the imaging lens 2003, the absorptive coating
2007, the absorptive material 2008 and the air gap 2006 are similar
as the imaging lens 1903, the absorptive coating 1907, the
absorptive material 1908 and the gap 1906 illustrated in FIG. 19. A
small flat surface 2010 is disposed about the edge or periphery of
the concave surface of the optical window 2001. An alignment edge
or ring 2011 is included in the housing 2004 to help align the
optical window 2001. Accordingly, the alignment ring 2011 has a
vertical edge that permit lateral alignment adjustment, axial
positioning, and proper orientation of the optical window in the
imaging system. However, as illustrated, the housing has an opening
for fitting the optical window 2001 therein and for providing a gap
between the housing and optical window. As discussed above, having
a larger opening and a gap 2012 permits the optical window to be
laterally translated and aligned, for example, using an alignment
fixture that moves the lens laterally with respect to the housing.
The optical window may, for example, be properly aligned with the
optical axis of the imaging lens and imaging system. The gap 2012
permits this lateral movement and alignment. Additionally, this gap
2012 provides for flow of sealing material. Accordingly, the
opening in the housing is sufficiently larger such that after the
optical window is centered and aligned, the gap 2012 remains
disposed between the housing and the window to allow for sealing
material. During manufacture, after the optical window 2001 is
dropped into the housing, an elastic sealing material 2013 is
applied to fill the gap between two components. The round corner
2009 at the end of the housing 2004 helps to build a smooth
transition from the flat surface 2010 to the housing 2004. In
various embodiments, this material comprises adhesive or epoxy,
which may be elastic. In some embodiments, the sealing material
2012 comprises UV cured acrylic adhesive. In various embodiments,
this sealing material may be elastic. In some such embodiments, the
sealing material is not heremetic sealing material. Accordingly, in
various embodiments, this seal is not a hermetic seal that can with
stand the temperature of autoclaving such as temperatures greater
than 120.degree. C., 130.degree. C., or 140.degree. C. and less
than, for example, 150.degree. C. In other embodiments, however,
the material may comprise hermetic sealing material and the seal
may be a hermetic seal. The hermetically sealing material 2013 may
comprise e.g., ceramic or metal.
[0154] As discussed above, in some embodiments, the hermetically
sealed eye imaging apparatus comprises a hermetically sealed
removable front imaging module and a main module. The hermetically
sealed removable front imaging module comprises a front end and a
rear end. The hermetically sealed removable front imaging module
includes a first optical window, a second optical window and an
imaging lens. The optical window at the front end is separated from
an alignment edge of the housing with a first smaller gap
configured to align the optical window using for example an
alignment fixture during manufacture, and separated from a
reservoir edge of the housing with a second gap larger than the
first gap, configured to be a reservoir of a hermetically sealing
material. The second gap is sometimes rearward the first gap, and
sometimes forward the first gap. There is a first hermetical seal
between this first optical window and the housing. The second
optical window is exposed from a rear end of the hermetically
sealed removable front imaging module. A second hermetical seal is
formed between the second optical window and the rear end. The
hermetically sealed removable front imaging module is capable of
being repeatedly attached to and removed from the main module that
includes the image sensor. The main module may further include a
third optical window exposed from a front portion of the main
module. In certain embodiments, the hermetically sealed eye imaging
apparatus may also include a plurality of balls disposed inside and
positioned against the reservoir edge of the housing. The
hermetically sealed removable front imaging module may further
include a first set of relay lenses configured to form a secondary
image of the eye near a back focal plane of the first set of relay
lenses. The main module may further include a second set of relay
lenses configured to project the secondary image to infinity with a
front focal plane positioned next to the back focal plane of the
first set of relay lenses. The main module may further comprise a
set of miniature lenses positioned near the back focal plane of the
second set of relay lenses and configured to deliver light from the
eye to the image sensor. The light source may be positioned within
the hermetically sealed removable front imaging module, or within
the main module. When the light source is within the main module,
the hermetically sealed removable front imaging module and/or main
module may further include a plurality of lighting coupling
elements to optically couple light from the main module to the
front imaging module.
[0155] The various embodiments as shown in FIG. 16, FIG. 17, FIG.
18, FIG. 19 and FIG. 20 can all use a special assembly process,
where the optical window is aligned, for example, with an alignment
fixture, and sealed with the housing. Other optical components
including the imaging lens and the lighting fixtures may be mounted
in a separated unit, and then aligned with the front optical
window, which has already been aligned with the housing. The
precise alignment between the optical window and the imaging lens
afterward, as well as setting of the proper gap between the optical
window and the imaging lens are steps that can affect the optical
performance of the imaging system. The proper gap is achieved in
room temperature during the assembling process with the adjustment
of the position of the lens housing, which comprises the optical
assembly, along the optical axis in reference to the housing of the
imaging apparatus. The use of the gap between the optical surfaces
of the optical window and the imaging lens helps to reduce the
thermal stress and enables the application of more sophisticated
hermetically sealing techniques.
[0156] In various embodiments such as shown in FIG. 21(A), an
opening 2103 is disposed at the center of the optical window 2101
and a portion of the imaging lens 2104 is inserted therein. The
opening may for example be drilled in the optical window 2101.
Accordingly, the shape and size of the opening 2103 may be made to
match that of imaging lens 2104, to allow a portion of the imaging
lens 2104 to be inserted in the opening. As discussed above, the
periphery of the imaging lens 2104 may be a conical shape such as a
frusto-conical shape and coated with optically absorptive material
2105 whose absorption spectrum may be in the visible range to the
eye and/or into invisible spectra, for example. The coating 2105
not only may prevent light from entering the imaging lens from
outside, but also absorb the stray light from the eye when it
enters the imaging lens 2104 along with the imaging light. The
boundary formed by the absorptive coating provides higher level of
separation between the illumination optical path and imaging
optical path in the imaging lens 2104. The concave surface of the
optical window 2101 can share the same or similar radius as the
concave surface of imaging lens 2104. Both of these concave
surfaces can have a curvature configured to receive the convex
curvature of the cornea. In various embodiments, the optical window
2101 may be cemented with the imaging lens 2104, with their concave
surface aligned for example along a common curve or reference
surface thereby forming a smooth surface against the cornea of
patient 2102. In various embodiments the concave surface of the
optical window and the imaging lens are flush against each other.
As illustrated, the imaging lens has a frusto-conical shape. The
front end is smaller than the back end and thus the sidewalls are
tapered. Additionally, the optical window has an inner sidewall or
edge that is tapered to match the taper of the sidewalls of the
imaging lens. The matching of these surface permits the imaging
lens to fit in the optical window with a junction where the optical
window contacts the imaging lens over the thickness of the optical
window. In certain embodiments, the front optical window 2101 may
comprise sapphire, optical glass or optically clear polymers.
[0157] FIG. 21(B) illustrates another embodiment with slightly
modified design. As illustrated, the optical window does not have
the tapered inner sidewall surfaces as shown in FIG. 21(A).
Instead, the optical window 2110 has inner sidewall surfaces that
are parallel to the optical axis of the imaging system and/or of
the imaging lens. Such a design may be easier for manufacturing the
optical window. In certain embodiments, however, the tip of the
imaging lens 2112 is shaped to match that of the opening 2111 of
the optical window and in particular to match the shape of the
inner sidewalls of the optical window. As shown, the imaging lens
is substantially frusto-conical in shape. However, the imaging lens
includes a neck defined by sidewall surfaces that are straight and
parallel to the central axis through the imaging lens and/or the
optical axis of the imaging lens. These sidewalls are configured to
match the shape of the inner sidewall surfaces of the optical
window. The matching of these surface permits the imaging lens to
fit in the optical window with a junction where the optical window
contacts the imaging lens over the thickness of the optical window.
An optical absorptive coating 2113 is applied to the edge of the
imaging lens 2112, before the imaging lens 2112, is cemented with
the optical window 2110. The optical window 2110 may comprise
sapphire, optical glass or optically clear polymers in certain
embodiments.
[0158] While the present invention has been disclosed in exemplary
embodiments, those of ordinary skill in the art will recognize and
appreciate that many additions, deletions and modifications to the
disclosed embodiment and its variations may be implemented without
departing from the scope of the invention.
* * * * *