U.S. patent application number 14/993700 was filed with the patent office on 2016-05-05 for lens system and method.
The applicant listed for this patent is Manuel Aschwanden, Michael Bueeler, Chauncey Graetzel, David Niederer. Invention is credited to Manuel Aschwanden, Michael Bueeler, Chauncey Graetzel, David Niederer.
Application Number | 20160124220 14/993700 |
Document ID | / |
Family ID | 42173269 |
Filed Date | 2016-05-05 |
United States Patent
Application |
20160124220 |
Kind Code |
A1 |
Bueeler; Michael ; et
al. |
May 5, 2016 |
Lens System and Method
Abstract
An optical system includes a first deformable lens having a
membrane with a deformable portion and having a filler material.
The optical system also includes a corrective fixed lens. A sensor
is configured to receive the light focused by the first deformable
lens. An optical path extends through the first deformable lens and
to the sensor. The first deformable lens is tuned according to an
applied electrical signal in order to directly focus light
traversing the optical path onto the sensor. The corrective fixed
lens is integral with the first deformable lens and the corrective
fixed lens is in direct contact with the filler material of the
deformable lens where the light passes through, and is configured
to correct monochromatic or polychromatic aberrations.
Inventors: |
Bueeler; Michael; (VOGELSANG
AG, CH) ; Aschwanden; Manuel; (HAGENDORN, CH)
; Graetzel; Chauncey; (STALLIKON, CH) ; Niederer;
David; (KUTTIGEN, CH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Bueeler; Michael
Aschwanden; Manuel
Graetzel; Chauncey
Niederer; David |
VOGELSANG AG
HAGENDORN
STALLIKON
KUTTIGEN |
|
CH
CH
CH
CH |
|
|
Family ID: |
42173269 |
Appl. No.: |
14/993700 |
Filed: |
January 12, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14184927 |
Feb 20, 2014 |
9268110 |
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14993700 |
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12720113 |
Mar 9, 2010 |
8659835 |
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14184927 |
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61160012 |
Mar 13, 2009 |
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Current U.S.
Class: |
359/676 |
Current CPC
Class: |
G02B 3/0081 20130101;
G02B 3/14 20130101; G02B 7/04 20130101; G02B 27/0025 20130101; G02B
27/005 20130101; H04N 5/23212 20130101; H04N 5/2254 20130101 |
International
Class: |
G02B 27/00 20060101
G02B027/00; G02B 3/00 20060101 G02B003/00 |
Claims
1. An optical system comprising: a first deformable lens including
a membrane with a deformable portion and including a filler
material; a corrective fixed lens; a sensor configured to receive
the light focused by the first deformable lens; an optical path
extending through the first deformable lens and to the sensor;
wherein the first deformable lens is tuned according to an applied
electrical signal in order to directly focus light traversing the
optical path onto the sensor; wherein the corrective fixed lens is
integral with the first deformable lens and the corrective fixed
lens is in direct contact with the filler material of the
deformable lens where the light passes through, and is configured
to correct monochromatic or polychromatic aberrations.
2. The optical system of claim 1 further comprising a second
deformable lens that is disposed within the optical path, the
second deformable lens operates with the first deformable lens to
focus light traversing the optical path onto the sensor.
3. The optical system of claim 2 wherein the first deformable lens
and the second deformable lens are tuned at least in part by an
element selected from the group consisting of an electrostatic
actuator, an electromagnetic actuator, magnetostrictive actuator, a
piezo motor, a stepper motor, and an electroactive polymer
actuator.
4. The optical system of claim 1 wherein the first deformable lens
is configured to change from a concave shape to a convex shape.
5. The optical system of claim 2 wherein the second deformable lens
is configured to change from a convex shape to a concave shape.
6. The optical system of claim 1 wherein the corrective fixed lens
element is constructed from a rigid material.
7. The optical system of claim 2 wherein an aperture stop is
disposed between the two deformable lenses.
8. The optical system of claim 1 wherein an aperture stop is
disposed inside the first deformable lens
9. The optical system of claim 1 further comprising a fixed,
non-deformable lens disposed in the optical path, wherein the fixed
non-deformable lens is constructed from a rigid material, and
wherein the fixed, non-deformable lens is configured to correct for
monochromatic or spherical aberrations.
10. The optical system of claim 1 further comprising at least one
fixed, non-deformable lens disposed in the optical path, wherein
the fixed focus lens is constructed from a rigid material, and
wherein the at least one fixed, non-deformable lens is configured
to correct for polychromatic aberrations.
11. The optical system of claim 1 further comprising a second
corrective fixed lens disposed in the optical path, wherein the
second corrective fixed lens is constructed from a rigid material,
the second corrective fixed lens is disposed between a deformable
lens closest to the sensor and the sensor.
12. The optical system of claim 1 wherein an interface defined by
the corrective fixed lens and the filler material has no inflection
points in its shape where the design light rays pass through.
Description
CROSS REFERENCES TO RELATED APPLICATIONS
[0001] This application is a continuation of prior U.S. application
Ser. No. 14/184,927 entitled "Lens System and Method," filed Feb.
20, 2014, which is a continuation of prior U.S. application Ser.
No. 12/720,113 entitled "Lens System and Method," filed Mar. 9,
2010, which claims benefit under 35 U.S.C. .sctn.119 (e) to U.S.
Provisional Application No. 61/160,012 entitled "Zoom Lens System
and Method," filed Mar. 13, 2009, the contents of all of which are
incorporated herein by reference in their entirety.
TECHNICAL FIELD
[0002] This patent relates to lenses and methods of operating
lenses.
BACKGROUND OF THE INVENTION
[0003] Various types of optical systems that utilize different
operational principles exist. For instance, an afocal lens has no
focusing power and transfers parallel light rays of one beam
diameter to parallel light rays of another diameter. By adding a
single focusing lens after the afocal system, a parfocal lens is
created. In a conventional zoom lens system, only the lens elements
of the afocal portion have to be moved forth and back to obtain the
zoom effect, while the focusing lens can remain static.
Consequently, a parfocal lens stays in focus when
magnification/focal lengths are changed.
[0004] In another approach, a varifocal lens system is sometimes
used in today's optical systems. The varifocal system is not based
on the transfer of parallel light rays of one beam diameter to the
other. Rather, a first axially movable lens focuses or diverts the
light rays towards a second (or third) lens, which is a focusing
lens. In order to always obtain a sharp image in the image plane,
the focusing lens cannot be static and has to be axially movable or
be focus tunable.
[0005] Thus, a varifocal lens adjusts the position or shape of the
final focusing lens when magnification/focal length is changed.
[0006] Using either approach, conventional zoom lenses are space
consuming, expensive and prone to material wear as several optical
elements have to be axially shifted relative to the others by means
of motorized translation stages. The potential for miniaturization
of such lenses for use in cell phones, medical endoscopes, or other
devices where space is at a premium is limited due to their
functional principles and operation.
[0007] Attempts to overcome the above-mentioned deficiencies have
been made in previous systems where focus adjustable lenses were
used instead of axially shiftable fixed, non-deformable lenses. In
these previous systems, the shape of the lens was changed in order
to alter the focal length and other optical properties of the
lens.
[0008] Unfortunately, these previous approaches still suffered from
several disadvantages. More specifically, their potential to
sufficiently reduce axial length while providing a high zoom factor
and sufficient image size on the image sensor was still limited
either due to the chosen zoom principle (e.g., afocal/parfocal
systems) or due to the composition or operating principles of the
deformable lenses that did not offer sufficient tuning range (e.g.,
electrowetting lenses or liquid crystal lenses). Consequently, the
disadvantages present in these previous systems limited their
application and created user dissatisfaction with these previous
approaches.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] For a more complete understanding of the disclosure,
reference should be made to the following detailed description and
accompanying drawings wherein:
[0010] FIGS. 1A and 1B comprise a diagram of a lens system
according to principles of the present invention;
[0011] FIGS. 2A and 2B comprise block diagrams of a zoom lens
system according to principles of the present invention;
[0012] FIG. 3 comprises a diagram of a lens system according to
principles of the present invention;
[0013] FIGS. 4A,4B, 4C and 4D comprise a diagram of a lens system
according to various embodiments of the present invention;
[0014] FIGS. 5A, 5B, 5C and 5D comprise a diagram of a lens system
according to various embodiments of the present invention;
[0015] FIGS. 6A and 6B comprise a diagram of a lens system
according to various embodiments of the present invention;
[0016] FIGS. 7A, 7B, 7C, 7D, 7E, and 7F comprise a diagram of a
lens system according to various embodiments of the present
invention;
[0017] FIG. 8A and 8B comprise a lens system according to various
embodiments of the present invention;
[0018] FIG. 9 comprises a diagram of a lens system according to
various embodiments of the present invention.
[0019] In some related figures that show the same or similar
elements, for clarity some elements are not labeled. Skilled
artisans will appreciate that elements in the figures are
illustrated for simplicity and clarity. It will further be
appreciated that certain actions and/or steps may be described or
depicted in a particular order of occurrence while those skilled in
the art will understand that such specificity with respect to
sequence is not actually required. It will also be understood that
the terms and expressions used herein have the ordinary meaning as
is accorded to such terms and expressions with respect to their
corresponding respective areas of inquiry and study except where
specific meanings have otherwise been set forth herein.
DETAILED DESCRIPTION
[0020] Zoom lenses are provided with deformable lenses that
overcome the disadvantages of both conventional zoom lenses and
previous approaches that utilized deformable lenses. The deformable
lenses provided herein are, to give a few examples, tuned at least
in part by an element such as an electrostatic actuator, an
electromagnetic actuator, a piezo motor, a magnetostrictive
actuator, a stepper motor, or an electroactive polymer actuator
offering a high focus tuning range. Additionally, the zoom lenses
presented herein utilize varifocal operating principles instead of
the afocal/parfocal principles. In one example of the present
approaches, a single focus tunable lens is used as a single
autofocus element.
[0021] In many of these embodiments, a compact zoom lens includes a
first deformable lens that is constructed of a membrane with a
deformable portion and a filler material. In these approaches,
deformation is achieved at least in part by an element such as an
electrostatic actuator, an electromagnetic actuator,
magneto-strictive actuator, a piezo motor, a stepper motor, or an
electroactive polymer actuator.
[0022] The lens can also include a static diverging lens of radius
of curvature that provides sufficient magnification of the image on
the sensor. For example, the radius may be as small as
approximately 1.5 mm thereby providing a highly negative focusing
power. The lens further includes a second deformable lens
constructed of a membrane with a deformable portion and a filler
material that serves as a zoom element directing light rays from
various field angles to a desired image size on a sensor. Further,
the lens includes a sensor (e.g., a sensor chip) sensing the image
formed by the optical system. So configured, the lens exhibits the
characteristics of deformable lenses and has very high tuning
ranges. Additionally, the lens follows the varifocal principle of
optical systems instead of the afocal/parfocal principle (i.e., the
second deformable lens acts as a focus element directly focusing
the light rays onto the sensor chip).
[0023] In others of these embodiments, the zoom lens includes one
or more phase plates or corrective lens elements for the correction
of monochromatic aberrations of single lenses or of the entire
optical system. In some examples, an achromatic element is placed
in front or behind the second deformable lens serving the purpose
of correcting for chromatic aberrations. In still other examples, a
field-compensating flattener lens is placed behind the second
deformable lens serving the purpose of correcting for the
field-curvature of the optical system.
[0024] In yet others of these embodiments, an optical system
consisting of only the first deformable lens and constructed from a
membrane with a deformable portion and a filler material is
provided. Alternatively, the optical properties of the first
deformable lens may be adjusted by an element such as an
electrostatic actuator, an electromagnetic actuator,
magneto-strictive actuator, a piezo motor, a stepper motor, or an
electroactive polymer actuator to serve as an autofocus element.
Using either approach, light beam cones from various object
distances are focused sharply onto a sensor. A phase plate or
corrective lens element for the correction of monochromatic
aberrations may also be used in these approaches.
[0025] Consequently, the present approaches use two (or potentially
more) deformable lenses together with a number of fixed,
non-deformable optical elements to create a very compact varifocal
system. The adjustable lenses are constructed of a membrane with a
deformable portion and a filler material and deformation is
achieved at least in part by an element such as an electrostatic
actuator, an electromagnetic actuator, magneto-strictive actuator,
a piezo motor, a stepper motor, or an electroactive polymer
actuator. So configured, they are able to provide very high tuning
ranges superior to other lens tuning technologies such as
electrowetting or liquid crystals. Additionally, phase plates or
corrective lens elements for the correction of monochromatic
aberrations can be used in conjunction with the deformable lenses
used in the zoom lenses.
[0026] As mentioned and in contrast to previous zoom systems, the
zoom lenses described herein do not operate according to the
afocal/parfocal principle that is space consuming and requires a
large number of optical elements. Instead, the lenses and the
system where these lenses are deployed operate according to the
varifocal principle in order to drastically reduce both axial
length and the number of optical elements needed for zooming.
Generally speaking and to mention one example, a first deformable
lens together produces light ray bundles of varying angles of beam
spread while a second deformable lens acts as a focus element
directly focusing the light rays onto a sensor.
[0027] In contrast to the varifocal operating principle, an afocal
lens has no focusing power and transfers parallel light rays of one
beam diameter to parallel light rays of another diameter. By adding
a single focusing lens after the afocal system or elements, a
parfocal lens is created. In previous zoom systems, only the lens
elements of the afocal portion are moved to obtain the zoom effect,
while the focusing lens can remain at a fixed position. Put another
way and as used herein, a parfocal lens is a lens that stays in
focus when magnification/focal length is changed.
[0028] A varifocal lens system is not based on the transfer of
parallel light rays from one diameter to another. In order to
always obtain a sharp image on the sensor, the focusing lens is not
static. Put another way and as used hereon, a varifocal lens
adjusts position or shape of the final focusing lens when the
magnification/focal length is changed. In other words, a varifocal
lens is a non-fixed focal length lens where the focus changes with
focal length.
[0029] In many of these embodiments, an optical system includes a
first deformable lens, a sensor, and an optical path. The first
deformable lens includes a membrane with a deformable portion. The
sensor is configured to receive the light focused by the first
deformable lens and the optical path extends through the first
deformable lens and to the sensor. The first deformable lens is
tuned according to an applied electrical signal in order to
directly focus light traversing the optical path onto the sensor. A
first volume of a first optical media and a second volume of a
second optical media are defined at least in part by the deformable
portion of the membrane. The first volume and the second volume are
completely enclosed by the housing. The first volume and the second
volume remain substantially constant for all configurations of the
first deformable lens.
[0030] In some aspects, the first deformable lens is deformed at
least in part by an element such as an electrostatic actuator, an
electromagnetic actuator, magneto-strictive actuator, a piezo
motor, a stepper motor, or an electroactive polymer actuator. Other
examples are possible.
[0031] In other aspects, a second deformable lens is disposed
within the optical path. The second deformable lens operates with
the first deformable lens to focus light traversing the optical
path onto the sensor. In some examples, the first and second
deformable lenses are tuned according to the applied electrical
signal in order to directly focus light traversing the optical path
onto the sensor according to a varifocal operation. In another
example, the first deformable lens and the second deformable lens
are tuned at least in part by an element such as an electrostatic
actuator, an electromagnetic actuator, magnetostrictive actuator, a
piezo motor, a stepper motor, or an electroactive polymer actuator.
Other examples of actuator elements are possible.
[0032] In some of these examples, the first deformable lens is
configured to change from a concave shape to a convex shape. In
other examples, the second deformable lens is configured to change
from a convex shape to a concave shape.
[0033] A corrective fixed lens element may also be deployed and the
corrective fixed lens element is integral with the first
focus-adjustable lens and the corrective fixed lens is in contact
with the deformable material of the deformable lens and configured
to correct for monochromatic or polychromatic aberrations. In some
approaches, the corrective fixed lens element is constructed from a
rigid material (e.g., glass or polycarbonate or PMMA or
cycloolefinpolymers or copolymers). In some examples, an aperture
stop is disposed between the two deformable lenses. In other
approaches, the aperture stop is disposed inside the first
deformable lens.
[0034] In other aspects, a fixed, non-deformable lens is disposed
in the optical path. The fixed, non-deformable lens is constructed
from a rigid material, and the fixed, non-deformable lens is
configured to correct for monochromatic or spherical
aberrations.
[0035] In still other aspects, at least one fixed, non-deformable
lens is disposed in the optical path. The fixed, non-deformable
lens may be constructed from a rigid material, and the fixed,
non-deformable lens is configured to correct for polychromatic
aberrations.
[0036] In other examples, a corrective lens disposed in the optical
path. The corrective lens is constructed from a rigid material
(e.g., glass or polycarbonate or PMMA or cycloolefinpolymers or
copolymers) and the corrective lens is disposed between a
deformable lens closest to the sensor and the sensor.
[0037] In many of these approaches, the total axial length of the
optical system is reduced to a value L such that the lens is able
to produce a zoom factor k for an image sensor with a diagonal d,
having a ratio r=L/(k*d). The ratio r is less than approximately
0.7 while producing an image size to completely illuminate the
sensor in a fully zoomed state.
[0038] The actuation signals can also originate from various
sources. For example, the actuation signals may be manually
generated signals or automatically generated signals.
[0039] In others of these embodiments, a lens system includes a
first deformable lens, a corrective optical element, a sensor, and
an optical path. The first deformable lens includes a filler
material. The corrective optical element is in contact with the
filler material. The sensor is configured to receive the light
focused by the first deformable lens. The optical path extending
through the first deformable lens and the corrective element, and
to the sensor. The first deformable lens is tuned according to an
applied manual or automatic electrical signal in order to directly
focus light traversing the optical path onto the sensor and the
corrective element adjusts at least one property of the light
traversing the optical path.
[0040] The first deformable lens may be tuned at least in part by
an element such as an electrostatic actuator, an electromagnetic
actuator, a piezo motor, a magnetostrictive actuator, a stepper
motor, and an electroactive polymer actuator. Other examples of
actuator elements are possible.
[0041] In other examples, a second deformable lens is disposed
within the optical path and the second deformable lens operates
with the first adjustable lens to focus light traversing the
optical path onto the sensor. In many of these examples, the first
deformable lens and the second deformable lens are tuned at least
in part by an element such as an electrostatic actuator,
electromagnetic actuator, a piezo motor, a magnetostrictive
actuator, a stepper motor, and an electroactive polymer
actuator.
[0042] In other aspects, the interface defined by the corrective
optical element and the filler material has no inflection points in
its shape where the design light rays pass through. An inflection
point that exists in the shape in these elements is generally
undesirable as it relates to the temperature sensitivity. If the
optical surface has an inflection point, any additional surface
order beyond two (quadratic) in the interface between the filler
material and the corrective lens element leads to an increased
deterioration of the image quality when the temperature deviates
from the design temperature as a result of an increased sensitivity
to differences in the refractive indices. The elimination of any
inflection point eliminates or substantially eliminates these
problems.
[0043] The corrective lenses described herein may include a front
surface and back surface that are configured into a shape. The
shape may be a wide-variety of shapes such as spherical or
aspherical shapes or they may be described by higher-order
polynomials producing for instance an m-like shape with a
aspherical coefficients of order equal to or larger than
approximately four or a w-like shape with a aspherical coefficients
of order equal to or larger than approximately four. Other examples
of shapes are possible.
[0044] Referring now to the figures and particularly to FIG. 1A,
one example of a zoom lens in the un-zoomed wide-angle state (e.g.,
zoom factor=1) is described. A first deformable lens 101 is shown
in a state of low focusing power. A first phase plate or corrective
lens element 102 is optionally used to correct for monochromatic
aberrations of the lens such as spherical aberration or for
chromatic aberrations. A lens group 103 consists of one or more
fixed, non-deformable lenses serving the purpose of supporting the
zoom functionality of the following second deformable lens 104 and
for correcting monochromatic aberrations such as spherical
aberration or chromatic aberrations.
[0045] The second deformable lens 104 is in a state of high
focusing power focusing the light onto the image sensor 107
following the varifocal principle of operation. A second phase
plate or corrective lens element 105 is used to correct for
monochromatic or polychromatic aberrations. A field-compensating
flattener lens 106 is used serving the purpose of correcting for
the field-curvature of the optical system. The image is finally
formed on an image sensor 107. In some examples, the corrective
lenses or lens groups 103 or 106 may be omitted or further
corrective elements may be used.
[0046] The shape of the first deformable lens 101 and the second
deformable lens 104 may be changed using an element such as an
electrostatic actuator, an electromagnetic actuator, a piezo motor,
a magnetostrictive actuator, a stepper motor, and an electroactive
polymer actuator.
[0047] Deformable lens 101 is voltage or current controlled by a
first voltage or current control element 108 with the input signal
coming from an automatic or manual operation. An automatic
operation might be an autofocus algorithm. The autofocus algorithm
is any type of algorithm that provides inputs that autofocus an
image. Such autofocus algorithms are well know to those skilled in
the art and will not be described further herein. A second
deformable lens 104 is voltage or current controlled by a second
voltage or current control element 109 with the input corning from
an automatic or manual operation.
[0048] Any of the tunable or deformable lenses described herein can
be adjusted according to any approach described in the application
entitled "Lens Assembly System and Method" having attorney docket
number 97372 and filed on the same day as the present application,
the contents of which are incorporated herein in their entirety.
Other tuning approaches may also be used.
[0049] The image sensor 107 may be any type of sensing device. Any
image sensor based on CCD or CMOS technology may be used. Such
image sensors are typically used in any digital camera or cell
phone camera and they feature various pixel numbers such as 3
megapixels or 12 megapixels. One example of an image sensor is the
Omnivision Inc. OV5630 1/3.2'' 5 megapixel sensor. Other image
sensing technologies and/or sensing chips may also be employed.
[0050] Referring now to FIG. 1B, the same zoom lens of FIG. 1A now
in the fully-zoomed tele-photo state (zoom factor>approximately
2.5) is described. As shown, the first deformable lens 101 is in a
state of high focusing power while the second deformable lens 104
is in a state of low or even negative focusing power in order to
focus the light ray bundles onto the image sensor 107.
[0051] As with the example of FIG. 1A, the first deformable lens
101 and the second deformable lens 104 change shape because surface
deformation is achieved with an element such as an electrostatic
actuator, an electromagnetic actuator, a piezo motor, a
magnetostrictive actuator, a stepper motor, and an electroactive
polymer actuator. As with the example of FIG. 1A, increasing the
current or voltage increases or decreases the focusing power of the
lens. In order to activate zooming the user may press a button that
initiates the changing of the shape of the second deformable lens
(e.g., via application of a voltage or current to the lens) while
the first deformable lens is automatically adjusted by the
autofocus algorithm as described elsewhere herein.
[0052] Also as with the example of FIG. 1A, deformable lens 101 is
voltage or current controlled by the first voltage or current
control element 108 with the input signal coming from an automatic
or manual operation. The second deformable lens 104 is voltage or
current controlled by the second voltage or current control element
109 with the input coming from an automatic or manual operation.
The autofocus algorithm is any type of algorithm that determines
focus adjustments for the lens and provides inputs to the first
voltage or current control element 108 or to the second voltage or
current control element 109 indicating these adjustments. The
voltage or current control element 108 adjusts its voltage or
current thereby altering the optical characteristics of the lens
101, and consequently, autofocusing an image. The first voltage or
current control element 108 and the second voltage or current
control element 109 are any combination of analog or digital
electronic components that receive an input signal (e.g., a user
input or a signal from an autofocus algorithm) and use the signal
to directly or indirectly adjust the shape of the first deformable
lens 101 or the second deformable lens 104.
[0053] More specifically, the shape of the lens can be adjusted
according to several approaches. In addition to the approaches
described herein, other approaches are possible. In one example,
the voltage or current control elements may receive a voltage or
current and based upon the received voltage or current, directly
apply a voltage or current to the lens via an electrical lead that
directly contacts the lens.
[0054] The fixed, non-deformable lenses (i.e., all lenses having
shapes that are not deformable or focus adjustable) of the present
approaches can be formed in any number of ways. For instance, the
static lenses in FIGS. 1A and 1B such as the first phase plate or
corrective lens element 102 (e.g., a cover glass compensator), the
lens group 103 (e.g., divergent lens or meniscus lens) or the
flattener lens 106 (e.g., used for the compensation of
field-curvature) can be formed by injection molding techniques with
materials such as glass or polycarbonate or PMMA or
cycloolefinpolymers or copolymers. Other formation approaches and
materials such as glass can also be used.
[0055] Furthermore, additional deformable lenses may be used if
necessary and/or advantageous. In some approaches, two deformable
lenses achieve great efficiencies. However, more deformable lenses
could be used in other examples. For example, a third deformable
lens may be employed and is used for various purposes such as
increasing optical quality or increasing zoom range.
[0056] Referring now to FIGS. 2A and 2B, a schematic zoom lens in
the un-zoomed wide-angle state (shown in FIG. 2A) and the
fully-zoomed tele-photo state (shown in FIG. 2B) with the optical
chief ray 204 symbolizing the path of light rays in the system is
described. The zoom lens consists of a first lens group 201
consisting in part of a deformable lens and one or more corrective
lens elements and a second lens group 202 consisting in part of a
deformable lens and one or more corrective lens elements, and an
image sensor 203. The corrective elements within the various lens
groups are fixed, non-deformable lenses with specially shaped
surfaces for the compensation of various types of optical errors.
Additionally, infrared radiation (IR) filters or ultraviolet (UV)
filters can be used. The entire system of FIGS. 2A and 2B has a
total length L. As shown in FIG. 2A, light rays entering the lens
from a distant object under an angle alpha can be imaged to an
image height corresponding to half the total diagonal d (where d is
a measurement of length) of the sensor chip 203. As shown in FIG.
2B, the zoom factor is increased. More specifically, as shown in
FIG. 2B, an optical chief ray 204 entering the system under an
angle beta which is smaller than the angle alpha of FIG. 2A is
imaged to an image height corresponding to half the total diagonal
d of the sensor chip. The zoom factor k of the system is defined as
the tangent of angle alpha divided by the tangent of angle beta. In
many of the approaches presented herein, the total axial length of
the optical system is reduced to a value L such that the lens is
able to produce a zoom factor k for an image sensor with a diagonal
d, having a ratio r=L/(k*d). The ratio r is less than approximately
0.7 while producing an image size to completely illuminate the
sensor in both the un-zoomed (wide-angle) and the fully zoomed
(telephoto) state.
[0057] Referring now to FIG. 3, a single autofocus element is
described and is used independently (or with other components as
part of an optical system). For example, the first or second
deformable lens which is operated with an element such as an
electrostatic actuator, an electromagnetic actuator, a piezo motor,
a magnetostrictive actuator, a stepper motor, and an electroactive
polymer actuator (e.g., element 101 of FIGS. 1A, 1B) is used as an
autofocus element focusing light beam cones from various object
distances sharply onto a sensor (e.g., a sensor chip). A phase
plate or corrective lens element or lens stack with a range of
corrective, non-deformable lenses can be optionally used to correct
for monochromatic aberrations of the lens such as spherical
aberration or to correct for polychromatic aberrations.
[0058] A deformable lens 301 adapts to the object distance by
adjusting its refractive power. Light rays of distant objects 302
are focused sharply onto an image sensor 304 by reducing the
focusing power (solid lines), while light rays from close objects
303 are focused onto the image sensor 304 by increasing the
focusing power (dashed lines). An optional phase plate or
corrective lens element 305 can be used to compensate for
monochromatic or polychromatic aberrations of the focus tunable
lens. A voltage or current control element (not shown) is used to
control the shape of the deformable lens 301 and hence tune the
focusing power. The voltage or current applied is controlled by an
autofocus algorithm.
[0059] The various elements of FIG. 3 can be similar in
construction to similar elements of FIGS. 1A and 1B. For example,
the deformable lens 301 may be constructed of a membrane with a
deformable portion and a filler material, the deformation being
achieved at least in part by applying a voltage or current to an
element such as an electrostatic actuator, an electromagnetic
actuator, magneto-strictive actuator, a piezo motor, a stepper
motor, or an electroactive polymer actuator. For example, a voltage
or current control element may directly control the voltage or
current.
[0060] The image sensor 304 may be any type of image sensing
device. As with the other sensors described herein, any image
sensor, for example, based on CCD or CMOS technology, could be
used. Other technologies for image sensing could also be employed.
One example of an image sensor is the Omnivision Inc. OV5630
1/3.2'' 5 megapixel sensor. Other examples of sensors are
possible.
[0061] The approaches herein provide lens arrangements that are
applicable in a wide variety of applications. For example, they can
be used in cellular phones, digital cameras of any type, and
medical endoscopes to name a few examples. Other examples of
devices where these approaches may be employed are possible.
[0062] As mentioned, various materials may be used in the
construction of the lens 301. As for an electroactive polymer, any
elastomer such as the 20190 polymer available from Cargill Inc.
(with coatings that serve as electrodes) could be used. Magnetic
tuning can be achieved with any voice coil motor structure.
[0063] Referring now to FIGS. 4A and 4B another example of a lens
system that includes four lens elements is described and operates
as an autofocus system. The example of FIG. 4A depicts the state of
the system when the lens is focused on an object at infinity. An
optical path extends along (at and on either side of) an optical
axis labeled 402 and passes through the center of the elements
shown. A first lens element 411 is a deformable lens based that
operates according to an electroactive polymer technology, using
one or more magnetic tuning actuators, using one or more
piezoelectric actuators, using one or more magnetostrictive
actuators, or using one or more electrostatic actuators. A cover
410 (e.g., constructed from glass) can be deployed to protect the
deformable lens surface of the lens element 411. A corrective
element 412 is disposed so as to be in contact with the deformable
lens material (e.g., filler material within the first lens
element). In this respect, the corrective element 412 is
incorporated with the first lens element 411. The corrective
element 412 corrects monochromatic and polychromatic aberrations. A
fixed, non-deformable corrective lens 414, in one function,
corrects spherical aberration and other monochromatic aberrations
and follows the aperture stop 413 along the optical axis 402. A
fixed, non-deformable lens 415 is followed along the axis 402 by a
flattener lens 416 that, in one function, eliminates
field-curvature. The image that is transferred by the light rays
(as these rays traverse along the axis 402) is finally formed in
the image sensor plane 417. The image sensor may be any type of
sensing device. Any image sensor based on CCD or CMOS technology
may be used. Such image sensors are typically used in any digital
camera or cell phone camera and they feature various pixel numbers
such as 3 megapixels or 12 megapixels. One example of an image
sensor is the Omnivision Inc. OV5630 1/3.2'' 5 megapixel sensor.
Other image sensing technologies and/or sensing chips may also be
employed. The deformable lens 411 is current or voltage controlled
418 with the input coming from the autofocus algorithm. The dashed
lines in FIG. 4A illustrate light rays 404 originating from an
object that is relatively close to the lens (e.g. closer than
approximately 500 mm) and the additional deflection of the
deformable lens 411 necessary to focus the object onto the image
plane 417.
[0064] FIG. 4B illustrates the same system as that of FIG. 4A.
However, in this example, the state of the system has changed and
the object is closer to the system than the object whose image is
projected in FIG. 4A. The elements in FIG. 4B are the same as those
shown in FIG. 4A and their description will not be repeated here.
As shown in FIG. 4B, rays 404 (from the object) entering the lens
under a divergent angle are focused sharply onto the image plane
417 due to the change in curvature of the lens element 411.
[0065] In other examples, a zoom system can be constructed based on
the autofocus lens depicted in FIGS. 4A-B. In this case, the zooms
lens system uses two deformable lenses together with a number of
fixed, non-deformable optical elements to create a very compact
varifocal-based system. Examples of zoom systems are described in
detail elsewhere herein.
[0066] As with the lens 411 in the autofocus system, the deformable
lenses in the zoom system are constructed according to
electroactive polymer technology, are magnetically tunable, use
piezoelectric actuators, use magnetostrictive actuators, or use
electrostatic actuators. So configured, the lenses are able to
provide very high tuning ranges superior to other lens tuning
technologies such as electrowetting or liquid crystals.
Additionally, phase plates or corrective lens elements for the
correction of monochromatic aberrations can be used in conjunction
with the deformable lenses used in the zoom lens.
[0067] In the examples of FIGS. 4C and 4D, the first deformable
lens 411 includes a deformable membrane 454. An annular lens
shaping structure 460 divides the membrane 454 into a central,
optically active part 456, and a peripheral, not optically active
part 455. As mentioned, the sensor 417 is configured to receive the
light focused by the first deformable lens 411 and the optical path
449 extends through the first deformable lens 411 and to the sensor
417. The first deformable lens 411 is tuned according to the
applied electrical signal 418 via a mechanical linkage structure
461 in order to directly focus light traversing the optical path
onto the sensor 417. A first volume 450 (depicted in one style of
cross-hatching) of a first optical media (e.g., air) and a second
volume 452 (depicted in another style of cross-hatching) of a
second optical media (e.g., filler material) are defined at least
in part by the deformable membrane 454. The first volume 450 and
the second volume 452 are completely enclosed by a housing 458.
That is, these volumes do not extend outside the housing 458. The
first volume 450 and the second volume 452 remain substantially
constant for all configurations of the first deformable lens 411. A
corrective optical element 412 is incorporated with the first
deformable lens element 411 and it is in contact with the second
volume 452. Indeed, as other deformable lenses are added to the
system of FIG. 4 (to construct other types of systems), it will be
appreciated that similar new volumes may be defined by these new
elements, and that these similar new volumes will remain constant
or substantially constant with respect to the each other (as the
first and second volumes remain constant with respect to each
other).
[0068] FIG. 4D illustrates the same system as that of FIG. 4C.
However, in this example, the state of the system has changed and
the object is closer to the system than the object whose image is
projected in FIG. 4C. The curvature of the deformable lens 411 is
increased according to the applied electrical signal 418 by moving
the mechanical linkage structure 461 in the direction of the sensor
417 (direction of movement indicated by 462). In this process the
first volume 450 and the second volume 452 remain separated by the
deformable membrane 454 and they remain substantially constant.
Referring now to FIGS. 5A, 5B, 5C, and 5D depicts other examples of
autofocus lenses are described. The system includes a cover 510, a
deformable lens 520, an aperture stop 513, a fixed, non-deformable
lens 515, a flattener lens 521, a corrective lens 514, and an image
sensor plane 517. These components are similar to the corresponding
elements of FIG. 4 and will not be described again here.
[0069] In FIG. 5A, the system is shown in a state where the
deformable lens 520 is inverted and the change in lens curvature
takes place in the direction of the image sensor plane 517. FIG. 5B
shows the system with the deformable lens 520 using an m- or w-like
shaped flattener lens 521 for the correction of field-curvature and
higher order aberrations. In the example of FIG. 5C the deformable
lens 522 is positioned as the third lens element instead of the
first lens element. In the lens system depicted in FIG. 5D only
three separate lens elements are used instead of four lenses.
Various combinations of these examples are possible.
[0070] Referring now to FIGS. 6A and 6B, another example of a lens
system is described. FIG. 6A depicts one example of a zoom lens in
the un-zoomed state (i.e., wide-angle mode, zoom factor=1). A first
deformable lens 631 is in a state of low focusing power. A cover
630 (e.g., constructed from glass) may be used to protect the
deformable lens surface. A corrective element 632 is in contact
with the deformable lens material (e.g., the filler material within
the lens 631) and corrects monochromatic and polychromatic
aberrations. An aspheric corrective lens 634, in one function,
corrects spherical aberration follows the aperture stop 633. A
second deformable lens 636 with positive focal power is in contact
with an aberration correcting element 635. The second deformable
lens 636 functions to change the zoom state of the zoom lens. A
flattener lens 637 functions in one example to eliminate field
curvature is placed in front of an image sensor 638. The deformable
lenses 631 and 636 are current controlled by control inputs 639 and
640. The control input 639 of the first deformable lens 631
originates from an autofocus algorithm and the control input 640 of
the second deformable lens 636 originates from the zoom input that
is determined by the user (e.g., manual control of or adjustment by
the user).
[0071] FIG. 6B depicts the same zoom lens of FIG. 6A in the
fully-zoomed state (i.e., telephoto mode, zoom
factor>approximately 2.5). The first deformable lens 631 is in a
state of high focusing power while the second deformable lens 636
is in a state of negative focusing power in order to focus the
light ray bundles onto the sensor chip 638). By "high focusing
power" it is meant focal lengths smaller than approximately 5.0 mm
(focal powers larger than approximately 200 diopters) are used and
by "negative focusing power" it is meant that focal lengths are
between approximately -4.0 mm and 0 mm (focal powers more negative
than approximately -250 diopters) are used. The capability of one
or both of the focus-adjustable lenses provides both positive and
negative refractive power (i.e., convex and concave shapes).
[0072] Referring now to FIGS. 7A, 7B, 7C, 7D, 7E, and 7F, other
examples of a zoom lens system is described. A first deformable
lens 731 is in a state of low focusing power. By "low focusing
power" it is meant focal lengths larger than approximately 12.0 mm.
A cover 730 (e.g., constructed from glass) may be used to protect
the deformable lens surface. A corrective element 732 is in contact
with the deformable lens material (e.g., the filler material within
the lens 731) and corrects monochromatic and polychromatic
aberrations. An aspheric corrective lens 734, in one function,
corrects spherical aberration follows the aperture stop 733. As
second deformable lens 736 with positive focal power is in contact
with an aberration correcting element 735. The second deformable
lens 736 functions to change the zoom state of the zoom lens. A
flattener lens 740 functions in one example to eliminate
field-curvature is placed in front of an image sensor 738. The
deformable lenses 731 and 736 are current or voltage controlled by
control inputs 739 and 741. The control input 739 of the first
deformable lens 731 originates from an autofocus algorithm and the
control input 741 of the second deformable lens 736 originates from
the zoom input that is determined by the user (e.g., manual control
of or adjustment by the user).
[0073] FIG. 7A shows the wide-angle state of a zoom lens that
includes the flattener lens 740 with an m- or w-like shape for the
correction of field-curvature and higher order aberrations. FIG. 7B
shows the corresponding telephoto state of the lens. FIGS. 7C and
7D depict a zoom lens system with only two focus-adjustable lenses
(i.e., the lenses 731 and 736) including corrective lens elements
and a flattener lens 740. No corrective lens between the
focus-adjustable lenses is used in this configuration. FIG. 7E
illustrates an example of a zoom lens system where the first
focus-adjustable lens 742 has a negative refractive power (i.e. a
concave shape in the wide-angle zoom mode). FIG. 7F shows the
system in the corresponding telephoto state of the lens with the
first deformable lens 742 having a positive refractive power (i.e.
a convex shape). It will be appreciated that the various optical
elements can be interchanged or eliminated in other examples.
[0074] Referring to FIGS. 8A and 8B variants of a deformable lens
consisting of a corrective lens element 801 and a filler material
802 are depicted. FIG. 8A shows a preferred version where the
interface 803 defined by the corrective optical element 801 and the
filler material 802 has no inflection points in its shape at least
referring to the portion of the corrective optical element that is
optically active. An inflection point that exists in the shape in
these elements is generally undesirable as it relates to the
temperature sensitivity. If the optical surface has an inflection
point, any additional surface order beyond two (quadratic) in the
interface between the filler material and the corrective lens
element leads to an increased deterioration of the image quality
when the temperature deviates from the design temperature as a
result of an increased sensitivity to differences in the refractive
indices. The elimination of any inflection point eliminates or
substantially eliminates these problems. FIG. 8B shows an example
of an undesirable embodiment of the interface 804 between the
corrective optical element and the filler material. The interface
exhibit inflection points on the surface since it is represented by
higher order polynomials.
[0075] FIG. 9 shows an example of the optical portion of the
assembly. This example includes a top variable optical assembly 990
which contains a membrane 992, optical filler material 993,
container 991 and a corrective optical element 994 that is embedded
(or integrated) in the container 991. This assembly 990 is the
farthest optical component away from the sensor 999. This approach
provides an assembly that maximizes performance while minimizing
height from sensor 999 to cover 998 (e.g., cover glass). A further
aspect of this example is having optical elements 994 embedded into
the container 991 (e.g., such that the optical elements 994 are in
contact with filler material 993). In this example, the second lens
can be deformed from positive to negative refractive power allowing
a very compact optics design.
[0076] In the example of FIG. 9, the magnetic structures are
coupled together and also coupled through one or more optical
elements of the system (e.g., through the lens, containers, or
membranes). The system further feature very small air gaps in both
motor structures. Side return structures may be self-attaching to
the housing thereby providing easy assembly with no adhesive (e.g.,
glue) required. These approaches are also fault tolerant from an
assembly point of view since the afore mentioned air gaps will be
automatically brought in the correct centric position. The magnets
are well defined and the posts in the housing define the location
of the magnets. All of these structures are according to any
approach described in the application entitled "Lens Assembly
System and Method" having attorney docket number 97372 and filed on
the same day as the present application, the contents of which are
incorporated by reference in their entirety.
[0077] While the present disclosure is susceptible to various
modifications and alternative forms, certain embodiments are shown
by way of example in the drawings and these embodiments will be
described in detail herein. It will be understood, however, that
this disclosure is not intended to limit the invention to the
particular forms described, but to the contrary, the invention is
intended to cover all modifications, alternatives, and equivalents
falling within the spirit and scope of the invention.
[0078] Preferred embodiments of this invention are described
herein, including the best mode known to the inventors for carrying
out the invention. It should be understood that the illustrated
embodiments are exemplary only, and should not be taken as limiting
the scope of the invention.
* * * * *