U.S. patent application number 11/153203 was filed with the patent office on 2005-10-20 for video opto-diagnostic instrument with single-adjustment focus.
Invention is credited to Baldwin, Kevin C., Duncan, Donald D., Farrell, Richard A., Happel, Lorenz J. JR., McCally, Russell L..
Application Number | 20050234300 11/153203 |
Document ID | / |
Family ID | 22252445 |
Filed Date | 2005-10-20 |
United States Patent
Application |
20050234300 |
Kind Code |
A1 |
Farrell, Richard A. ; et
al. |
October 20, 2005 |
Video opto-diagnostic instrument with single-adjustment focus
Abstract
A hand-held ophthalmoscope modified by the removal or
augmentation of the focusing wheel and the addition of a manual or
automatic focusing lens system. An electronic imager (CCD array or
video camera) is placed optically conjugate to a viewing screen
such that focus operations performed by the examiner to adjust the
image seen by the examiner on the screen also focuses the image on
the electronic imager. This is accomplished by an optical system
which includes a straight path from the viewing screen to the
patient's eye with a beam splitter interposed to cause the image of
the patient's eye to be reflected onto the imager. As a result,
when the examiner uses the focusing lens system, manual or
automatic, positioned between the beam splitter and the patient's
eye, to affect the image viewed by the examiner, the focus of the
imager is simultaneously affected as well. Alternatively, the image
from the imager is sent to a liquid crystal display (LCD) in the
instrument's eye piece; when the examiner focuses the image on the
LCD, the image on the imager is focused simultaneously. Also
provided is an automatic focusing system for the imager that
operates independently of the examiner's focusing adjustments. An
automatic focusing system for the imager can also be incorporated
in the other two embodiments. The output from the electronic imager
can be in digital or analog form and can consist of a single frame
or a video stream.
Inventors: |
Farrell, Richard A.;
(Laurel, MD) ; Happel, Lorenz J. JR.; (Ellicott
City, MD) ; McCally, Russell L.; (Columbia, MD)
; Duncan, Donald D.; (Silver Spring, MD) ;
Baldwin, Kevin C.; (Baltimore, MD) |
Correspondence
Address: |
Office of Patent Counsel
The Johns Hopkins University
Applied Physics Laboratory, MS 7-156
11100 Johns Hopkins Road
Laurel
MD
20723-6099
US
|
Family ID: |
22252445 |
Appl. No.: |
11/153203 |
Filed: |
June 15, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11153203 |
Jun 15, 2005 |
|
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|
10351879 |
Jan 27, 2003 |
|
|
|
10351879 |
Jan 27, 2003 |
|
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09370646 |
Aug 6, 1999 |
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6511420 |
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60095534 |
Aug 6, 1998 |
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Current U.S.
Class: |
600/167 ;
600/109 |
Current CPC
Class: |
A61B 3/145 20130101 |
Class at
Publication: |
600/167 ;
600/109 |
International
Class: |
A61B 001/04 |
Claims
We claim:
1. Apparatus in an opto-diagnostic instrument used by a medical
examiner for simultaneously focusing first and second images of an
original image of an area of interest comprising: a mirror for
reflecting the original image; an imager for receiving the original
image and forming a first image thereon; a liquid crystal display
(LCD) for receiving the first image from the imager and forming a
second image on the LCD for direct observation by the examiner; and
a lens system located between the mirror and the area of interest
for focusing the first and second images; wherein, when the second
image on the LCD is focused using the lens system, the first image
on the imager is thereby focused simultaneously.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This is a divisional of prior filed copending application
Ser. No. 10/351,879, filed Jan. 27, 2003, now abandoned, which in
turn is a divisional of prior filed copending application Ser. No.
09/370,646, filed Aug. 6, 1999, issued as U.S. Pat. No. 6,511,420,
on Jan. 28, 2003, which claims the benefit of prior filed copending
U.S. provisional application Ser. No. 60/095,534, filed Aug. 6,
1998.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates generally to medical diagnostic
instruments and, more specifically, to a hand-held opto-diagnostic
instrument, e.g., an ophthalmoscope or an otoscope, modified so
that a video image generated by the instrument is in proper focus.
In some embodiments, fine focus adjustments performed by an
examiner (physician or physician's assistant), or automatically by
the instrument for the examiner, simultaneously focus the video
image generated by the instrument. The invention also includes
apparatus for automatically fine focusing the video image
independently of the examiner.
[0004] 2. Description of the Related Art
[0005] Various hand-held opto-diagnostic instruments for use by a
physician during office examinations of a patient have been known
in the art for examination of the eye). Physicians assistants or
nurses can readily be trained to use these instruments.
[0006] Direct ophthalmoscopes provide a source of illumination for
the retina and a small peephole for the examiner to view the fundus
of the eye. Such instruments also incorporate a focusing wheel
which has a series of positive and negative lenses (usually in one
diopter steps) which correct for the physician's and patient's eye.
Fine focus (i.e., in the .+-.1/2 diopter range between steps) is
achieved via the examiner's accommodation, i.e., by changes in the
ocular lens of the examiner's eye.
[0007] Currently available direct ophthalmoscopes modified for
video and telemedicine make use of two separate focusing
mechanisms. The first is the standard focusing wheel discussed
above. A beam splitter is placed after the focusing wheel which
directs part of the beam through the second mechanism, a continuous
focus lens, which images the patient's retina on a CCD array. This
lens is adjusted by viewing a distant object through the
ophthalmoscope and focusing the object's image on a television
viewing screen. As the examiner observes different regions of the
patient's retina, fine focus is achieved via the examiner's
accommodation exactly as in a standard direct ophthalmoscope, but
the focus of the image on the CCD is not similarly corrected unless
done manually through the continuous focus lens.
[0008] U.S. Pat. No. 5,239,984 to Cane et al discloses employing
video technology in combination with hand-held diagnostic medical
instruments through the use of an adapter which is removably
secured to the instrument. The adapter utilizes a beam splitter
which provides two optical outputs. One of the optical outputs goes
to the medical system eyepiece to enable the examiner to obtain a
direct view of the target area, such as the retina of the eye. The
second optical output goes to a video camera head, typically a
solid state imager such as a charged-coupled device (CCD). This
allows for video output of the target area for use in producing
hard copy photographs, real time video display, or
telecommunication links to remote video hook-ups.
[0009] As noted above, one difficulty experienced in the use of
such instruments is that focusing the image requires separate
adjustments for the two different images. Many devices make use of
two separate focusing mechanisms. As the examiner observes
different parts of the patient's retina, fine focus is achieved via
the examiner's accommodation exactly as in a direct ophthalmoscope,
but the focus of the image on the CCD is not similarly corrected.
Thus, the image on the CCD must be focused using a separate
focusing mechanism.
[0010] U.S. Pat. No. 5,599,276 to Hauptli et al discloses a
hand-held device with a video adapter coupled into the line of
sight between the operator and a diopter indicator window.
Hauptli's device is arranged so that the operator may view the
diopter indicator window while the video adapter is coupled into
the instrument by use of mirrored reflectors, such as a prism. The
focus adjustments are made by an adjustment means between the video
adapter and a patient's eye; however, no details are given for how
the image on the video monitor is focused. The primary purpose of
Hauptli's device is to display the diopter setting of the lens in
the focusing wheel to the physician while he is viewing through the
ophthalmoscope.
[0011] Other devices may make focus refinements solely by using the
image of the CCD. For example, U.S. Pat. No. 5,125,730 to Taylor et
al discloses a fundus imaging device (a hand-held fundus camera)
which utilizes a CCD combined with a focusing means to provide an
image of the patient's eye on a video display device.
[0012] However, none of the above devices assure that the image
viewed by the examiner is in fine focus on the CCD array or other
imaging device. Such a capability would be beneficial because it
would save the time and expense of having to deal with separate
fine focus systems for the examiner and the CCD array. Also, the
examiner would be assured that fine focus adjustments made to
affect the examiner's image also affect the fine focus of the CCD
array.
SUMMARY OF THE INVENTION
[0013] A hand-held ophthalmoscope is modified by replacing or
augmenting the focusing wheel with a manual or automatic focusing
lens system which provides coarse and fine focus. In one
embodiment, an imager, such as a CCD array or video camera, is
placed optically conjugate to a viewing screen analogous to that
used in single lens reflex (SLR) cameras such that focus operations
performed by the examiner to adjust the fine focus of the image on
the viewing screen also fine focuses the image on the CCD array or
video camera. The viewing screen can also incorporate a focusing
aid such as, but not limited to, microprisms.
[0014] In this embodiment, the invention operates by using an
optical system which includes a straight path from the patient's
eye to the viewing screen with a beam splitter interposed to cause
the image of the patient's eye to be reflected onto the CCD array
or video camera while the image is also passed through onto the
viewing screen. As a result, when the examiner uses the focusing
lens system, manual or automatic, positioned between the beam
splitter and the patient's eye, to affect the image seen on the
screen, the focus of the CCD array or video camera is
simultaneously affected as well.
[0015] In an alternate embodiment the image from the CCD array is
sent to a liquid crystal display (LCD) which is substituted for the
viewing screen. The examiner, who does not directly view the
patient's eye, focuses the image on the LCD which automatically and
simultaneously focuses the image output from the CCD array.
[0016] In still another embodiment a novel automatic focusing
system, focuses the output of the CCD array independently of the
examiner.
[0017] The image on the CCD array can be output in digital or
analog form. If a video camera is used, the image is output in
standard (analog) video format.
[0018] Several objects and advantages of the present invention
are:
[0019] (a) to eliminate the examiner's accommodation as an
adjustable optical element other than to bring the real image on
the viewing screen into sharp focus;
[0020] (b) to provide an ophthalmoscope that assures that the CCD
or video camera image is in fine focus; and
[0021] (c) to provide an ophthalmoscope that has an image capture
switch, thus allowing the examiner to save the in-focus image that
is directly viewed through the ophthalmoscope.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 is a schematic illustrating the components of the
modified ophthalmoscope of the invention.
[0023] FIG. 2 is a schematic illustrating the liquid crystal
display embodiment of the invention.
[0024] FIG. 3 is a schematic illustrating an embodiment of the
invention containing an additional optics/detection system for
automatic focusing independently of the examiner.
DETAILED DESCRIPTION OF THE INVENTION
[0025] Referring to FIG. 1, a direct ophthalmoscope 10 has been
modified by adding a continuously variable focusing lens (with
either manual or automatic focus adjustment) to provide fine focus.
This lens, together with the coarse focus provided by the focusing
wheel comprises a lens system 12 which is located between a beam
splitter 14 and the patient's eye. The lens system 12 forms a first
real image of the retina on an imager 16, e.g., a CCD array or
video camera, via the beam splitter 14. The light passing directly
through the beam splitter 14 forms a second real image on a viewing
screen 18 which is located conjugate (i.e., in the equivalent
optical position) to the imager 16. The viewing screen is analogous
to that used in SLR cameras.
[0026] The second real image is viewed by the examiner through a
magnifying eyepiece lens 20 and focused by the continuously
variable focusing or auto-focusing lens system 12. The invention
allows the incorporation of a focusing aid in the viewing screen 18
such as, but not limited to, a microprism device 19. Because the
viewing screen 18 is optically conjugate to the imager 16, the
invention ensures that the first real image on the imager 16 is
always in focus when the second or directly observed (by the
examiner) real image is in focus on the viewing screen 18.
[0027] In a second embodiment, as shown in FIG. 2, the examiner is
able to view the output of the imager 16 directly. This is
accomplished by replacing the beam-splitter assembly with a simple
folding mirror 26 and mounting a miniature liquid crystal display
(LCD) 28 and display viewing optics 30 where the physician would
ordinarily place his eye on the ophthalmoscope. The light from the
patient's eye is reflected by mirror 26 to form a first image on
imager, 16, e.g., a CCD array. The output of the imager 16 is then
sent to the LCD 28 to form a second image. Thus, the examiner by
viewing the second image will be able to see the quality of the
first image captured by the imager 16 and can compensate for poor
image quality by adjusting the focus using lens system 12. Thus,
the examiner is able to focus both first and second images
simultaneously. The fine focus of lens system 12 can be
automated.
[0028] In a third embodiment as shown in FIG. 3, an additional
optics/detection system is incorporated to effect an automatic
focusing thus relieving the physician of the focusing operation for
the imager 16. The lens system 12, minus the focusing wheel (not
shown separately) which remains in its original position, has been
moved although it could be retained in its original position as
shown in FIGS. 1 and 2. The beam splitter allows the examiner to
view the patient's eye directly while also causing light to pass
through the lens system 12 and a partial reflector 32 to form a
first image on CCD 16. The partial reflector also sends light to
mirror 34 which sends the light through lenslet array 36 to form a
second image on a linear CCD array 38. The output from the linear
CCD array is then sent through a difference amplifier 40 to form an
error signal which is sent to lens system 12 through feedback loop
42. Such a system will judge if the image is sharp (in focus) based
upon well-understood in the art image quality criterion. As noted,
an error signal, derived from the criterion, will be used to
actively focus the first image on the imager 16 by adjusting the
position of the lens system 12.
[0029] Alternatively, autofocus could be accomplished by deriving
image quality in integrated circuit 44 based on the image received
from imager 16. The integrated circuit 44 outputs a signal
indicative of the quality of the first image to difference
amplifier 40. Amplifier 40 then forms an error signal indicative of
focus error which is sent to lens system 12, through feedback loop
42 causing the lens system 12 to automatically focus the first
image. In this embodiment, partial reflector 32, mirror 34, lenslet
array 36, and linear CCD array 38 would not be required. Clearly,
automated fine focusing systems based on analyses of the CCD image
could be incorporated into embodiments 1 and 2.
[0030] Below the imager 16, in any of the embodiments, there is a
direct digital or analog output 22. The digital output used in
conjunction with a CCD would provide the highest quality. The
digital output thus lends itself to storage in a digital storage
medium, such as a computer hard drive or digital camera memory
card. An image capture switch 24 located on the handle allows the
image on the screen (digital frame) to be saved to a digital
storage medium for later use. The digital storage medium could
either be incorporated directly into the modified ophthalmoscope,
or connected externally as part of, e.g., a computer. Additionally,
the real-time analog video, such as National Television Systems
Committee (NTSC), can be generated from the digital data. This
signal could be used for the recording or transmission of the
images for instructional purposes and/or video-based examination
(i.e. telemedicine applications.)
[0031] The present invention allows focus operations to be
performed manually by the examiner using a continuously variable
focusing system, or automatically if an auto-focusing system is
used, to simultaneously focus the image on the imager 16 and the
viewing screen 18. The embodiments in FIGS. 1 and 2 also provide
the examiner with "what you see is what you get" viewing; that is,
while looking directly through the ophthalmoscope, the examiner
knows the focus details of the image that is being outputted and
captured. The image capture switch 24, coupled with the focusing
lens system 12, allows the examiner to save the exact image that is
being viewed through the ophthalmoscope. Alternatively, the imager
16 can send the image to an LCD in the instrument eye piece which
when focused by the examiner causes the image output from the
imager to be focused too. In another embodiment, automatic focusing
means operating independently of the examiner relieves the examiner
of having to worry at all about focusing the image from the imager.
Direct digital output of the image on the CCD array ensures the
image is of the highest quality possible. Analog output from the
CCD or a video camera can also be used. Similar considerations
apply to indirect ophthalmoscopes and the same principles for
eliminating examiner accommodation would apply. The invention can
be applied to other opto-diagnostic instruments, as well, for
example, an otoscope, an instrument for inspecting the ear. In the
case of the otoscope, the invention would be similar to the device
shown in FIG. 1 except that the patient's eye would be replaced
with the patient's ear and the instrument would have a cone shaped,
disposable ear speculum attached to it for insertion into the
ear.
* * * * *