Method and apparatus for modeling an eye

Abstract

The invention may include a fixed lens (perhaps to simulate a cornea), a pair of Stokes lenses, an iris, deformable lens and an array detector. The implementation or construction of the disclosed embodiments follow and/or simulate the anatomy and geometry of an eye. Several optical and practical constraints were overcome by creating equivalent systems.

Claims

1. An optical system to simulate an eye, the system comprising: a) a fixed lens to simulate a cornea; b) a Stokes pair of lenses; c) an iris; d) a deformable lens; e) an array detector; and f) the system in electronic communication with a computer system wherein the computer system controls the system to create refraction error, the refraction error being both spherical and cylindrical.

2. The system of claim 1 wherein the fixed lens is selected from the group comprising: a plano-convex lens, a meniscus lens, a best form lens and achromatic lens.

3. The system of claim 1 wherein the Stokes pair of lenses introduce astigmatism to the optical system without affecting spherical performance.

4. The system of claim 1 wherein the Stokes pair of lenses are cylindrical lenses that may be rotated with respect to one another.

5. The system of claim 1 wherein the Stokes pair of lenses are of the same power.

6. The system of claim 1 wherein the Stokes pair of lenses are of opposite power.

7. The system of claim 1 wherein the Stokes pair of lenses are opposite in power, the total astigmatic power is between −2D and 2D depending on the angles between the two Stoke lenses to comport with the formula:
C=2D sin(α) wherein C is the cylinder power and a is the angle between the Stokes pair of lenses and wherein rotation of the Stokes pair of lenses together defines an axis of the cylinder.

8. The system of claim 1 wherein the deformable lens is a liquid lens, the liquid lens capable of being controlled by manipulating a membrane, the membrane containing fluid.

9. The system of claim 8 wherein the liquid lens is controlled by filling the membrane with fluid of a predefined amount.

10. The system of claim 8 wherein the liquid lens is controlled by electro-static deformation of a membrane of the deformable lens with the membrane containing a liquid.

11. The system of claim 1 wherein the deformable lens comprises a pair of spherical lenses having focal lengths f1 and f2, wherein the pair of spherical lenses move in relation to the other in an optical axis direction such that the distance, d, between the pair of spherical lenses changes.

12. The system of claim 11 wherein the focal length, f, of the pair of spherical lenses changes to comport with: $\frac{1}{f}=\frac{1}{f_1}+\frac{1}{f_2}-\frac{d}{f_1{f}_2}.$

13. The system of claim 1 wherein the array detector is replaced by a CCD or CMOS color camera.

14. The system of claim 1 wherein the computer system controls the system to simulate eye and vision conditions.

15. The system of claim 1 wherein the computer system controls the iris to simulate pupil response and effect on an image.

16. The system of claim 1 further comprising a second system, the second system comprising the components of the first system; the first and second systems comprising a binocular viewer, the binocular viewer providing three dimensional output and depth perception.

17. An optical system to simulate an eye, the system comprising: a) a fixed lens to simulate a cornea; b) a Stokes pair of lenses; c) an iris; d) a deformable lens; e) an array detector; f) the optical system in electronic communication with a computer system, wherein the computer system controls the system to simulate eye and vision conditions; and g) wherein the simulated eye and vision conditions comprise: cataract, macular degeneration, myopia, hyperopia and accommodation.

18. An optical system to simulate an eye, the system comprising: a) a fixed lens to simulate a cornea; b) a Stokes pair of lenses; c) an iris; d) a deformable lens; e) an array detector; f) the system mounted upon a gimbal to enable the system to move to simulate progressive lens vision; and g) wherein the shape of the deformable lens changes in reaction to movement of the system such that the deformable lens comports to close and far vision.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 depicts a construction of a disclosed embodiment

(2) FIG. 2 depicts ray tracing of a disclosed embodiment

REFERENCE NUMBERS

(3) 100 a disclosed system in general 200 fixed lens, such as a cornea 300 Stokes pair of lenses 400 Iris type of lens 500 Deformable lens 600 array detector 700 line of sight

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

(4) The following detailed description is directed to certain specific embodiments of the invention. However, the invention can be embodied in a multitude of different ways as defined and covered by the claims and their equivalents. In this description, reference is made to the drawings wherein like parts are designated with like numerals throughout.

(5) Unless otherwise noted in this specification or in the claims, all of the terms used in the specification and the claims will have the meanings normally ascribed to these terms by workers in the art.

(6) Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise,” “comprising” and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in a sense of “including, but not limited to.” Words using the singular or plural number also include the plural or singular number, respectively. Additionally, the words “herein,” “above,” “below,” and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of this application.

(7) The above detailed description of embodiments of the invention is not intended to be exhaustive or to limit the invention to the precise form disclosed above. While specific embodiments of, and examples for, the invention are described above for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize. For example, while steps are presented in a given order, alternative embodiments may perform routines having steps in a different order. The teachings of the invention provided herein can be applied to other systems, not only the systems described herein. The various embodiments described herein can be combined to provide further embodiments. These and other changes can be made to the invention in light of the detailed description.

(8) Any and all the above references and U.S. patents and applications are incorporated herein by reference. Aspects of the invention can be modified, if necessary, to employ the systems, functions and concepts of the various patents and applications described above to provide yet further embodiments of the invention.

(9) Referring to FIG. 1, a disclosed system 100 may include a fixed lens 200 (perhaps to simulate a cornea), a pair of Stokes lenses 300, an iris 400, deformable lens 500 and an array detector 600. The implementation or construction of the disclosed embodiments follow and/or simulate the anatomy and geometry of an eye. Several optical and practical constraints were overcome by creating equivalent systems as disclosed herein.

(10) Referring to FIG. 2 the optical path and optical considerations of the disclosed embodiments are depicted in the form of ray tracing lines and lens representations.

(11) Referring to FIGS. 1 and 2, a disclosed embodiment may be described wherein light, propagating from the left in figure enters the eye models through a single lens. The lens could be, without limitation a plano-convex lens, a meniscus lens, a best form lens, or achromatic lens. The lens could be made of glass or plastic, with or without coatings.

(12) The light then continues to go through a Stokes lens pair 300, two lenses numbered collectively as 300. These two lenses are cylindrical lenses that could be rotated with respect to each other. This component introduces an astigmatism term to the eye without affecting spherical performance. The two lenses could be of the same power or have different power, for example opposite power. In the case of two opposite power lenses with power ±D, the total astigmatic power from the pair is between −2D and 2D depending on the angles between the lenses according to the following formula:
C=2D sin(α)

(13) Where C is the cylinder power and a is the angle between the two lenses. Rotation of both lenses together defines the axis of the cylinder.

(14) This implementation is quite straightforward in the definition of the astigmatic power of the eye model as it is the only aspheric component in the design. In an alternative embodiment, the Stokes pair and front lens (both together mimic the cornea) could be replaced by a liquid lens that can be controlled by pulling on a membrane containing the fluid in a defined amount and direction. This implementation might closely mimic the biological eye function in terms of astigmatism. Nevertheless, it is much more complicated to fabricate.

(15) The light in FIG. 2 then moves from the Stokes pair through a changeable iris (representing the pupil) to a deformable lens. This lens could be controlled to change its focal length by changing its shape. In one embodiment, this is a liquid lens controlled electrically by changing the pressure on a reservoir of liquid, in another this liquid lens is controlled by electro-static deformation of the membrane containing the liquid. An altogether alternative embodiment includes a pair of spherical lenses of focal lengths f1 and f2, move one in relation to the other in the optical axis direction such that the distance between them, d, changes. This will cause the effective focal length f of the pair to change based on the following formula (approximately):

(16) $\frac{1}{f}=\frac{1}{f_1}+\frac{1}{f_2}-\frac{d}{f_1{f}_2}$

(17) The light from the lens will then travel to an array detector (camera). FIG. 2 presents a consideration for the determination of the size of the array. In one embodiment it could be chosen to represent the field of view (FoV) of the human macula of approximately 18°. Furthermore, the array could be chosen to detect color and provide color vision. The array's resolution could be chosen for example to be similar to that of the human macula being about 4 MP or more. The array could be a CCD or CMOS camera for example. The array could be presented as a curved array to better represent the biological eye. Furthermore, a curved array will improve the optical performance, especially with large arrays and at high FoV angles. Alternatively, the front lens (cornea lens) could be replaced with an aspheric lens to correct for the aberrations and distortion.

(18) The design of the invention could be implemented in a way that could be scaled. Scaling may be accomplished by proportionally increasing the parameters (distances, focal lengths, diameters etc.) in the design. For example, the size of the eye could be increased by a factor, maintaining the same factor for the optical system focal length, camera sensor size and element diameters will create an embodiment of the invention with similar or identical functionality, as can be measured by functional refraction ranges and FoV, as main examples of performance metrics.

(19) The following are aspects of the invention that pertain to specific embodiments and examples:

(20) The entire invention could be manual, such that changes in the performance of the eye model are done by hand. Alternatively, and preferably, the invention will utilize automatic features.

(21) The Stokes lenses could be mounted on rotation stages. These maybe based on stepper motors, servo motors, PCB motors, for example.

(22) The iris could be made of metal or plastic for example. It could be based on a leaf design or other design that controls the amount of obscuration.

(23) The camera could be further mounted on a translation (linear) stage allowing for changing the distance between the deformable lens (representing the eye lens) and the camera (representing the retina). This allows for experimental simulation of aging, myopia and hyperopia.

(24) The entirety of the components in the eye model could be connected to a processing unit, e.g. a computer. The processing unit can control the model as well as receive the images from the array detector.

(25) Various real conditions can be easily introduced in the system from a refraction standpoint, for example: myopia, hyperopia, presbyopia, accommodation.

(26) Furthermore, some eye conditions and diseases could be simulated using the processing unit, such as: cataract, AMD, color blindness.

(27) For presentation purposes the eye model could be placed in front of a visual acuity chart and a display could be connected to the processing unit to present what an eye with specific conditions would see.

(28) The eye model could be used to show the effectiveness of glasses by simulating the condition and placing eyeglasses in front of the model to show the improvement on the display.

(29) Two of the eyes could be built and placed together to allow for binocular vision and thus three-dimensional vision. That could be represented using a 3D screen/projector.

(30) Disclosed systems may be mounted upon a moveable platform and/or upon a gimbal or gimbal type device. A disclosed system upon a moveable and/or rotatable platform may allow for the simulation of progressive lens mission. The deformable lens may in linked or otherwise influenced by the system motion to account for close and/or far vision. Furthermore, such mounted system could be created in a binocular form to simulate 3D vision and include vergence and depth perception.