Modular adaptive optical subsystem for integration with a fundus camera body and CCD camera unit and improved fundus camera employing same

• US 20030007124A1
• Filed: 06/05/2001
• Published: 01/09/2003
• Est. Priority Date: 06/05/2001
• Status: Active Grant

• Current Assignee: Adaptive Optics Association Incorporated
• Original Assignee: AOA Xinetics (Northrop Grumman Corporation)
• Inventors: Levine, Bruce Martin
• Granted Patent: US 6,582,079 B2
• Time in Patent Office: Days
• US Class Current: 351/206
• CPC Class Codes: A61B 3/103 for determining refraction, e.g. refractometers, skiascopes
• CPC Class Codes: A61F 2009/00846 Eyetracking
• CPC Class Codes: A61F 2009/00848 based on wavefront
• CPC Class Codes: A61F 2009/00855 Calibration of the laser system
• CPC Class Codes: A61F 2009/00863 Retina
• CPC Class Codes: A61F 2009/00872 Cornea
• CPC Class Codes: A61F 2009/00882 based on topography
• CPC Class Codes: A61F 9/008 using laser

Abstract

A modular fundus camera including an adaptive optical module that detachably interfaces to a fundus camera body and image capture subsystem. The fundus camera body directs light produced from a first light source into the human eye and that collects and collimates retinal reflections. The adaptive optical module includes a wavefront sensor, controller and phase-compensating optical element. The wavefront sensor measures phase aberrations in the retinal reflections and operates in a closed-loop fashion with the controller to control the phase-compensating optical element to compensate for such phase aberrations to produce phase-compensated retinal reflections for output to the image capture subsystem.

Claims

1. An adaptive optical module for use with a fundus camera body that directs light produced from a first light source into the human eye and that collects and collimates retinal reflections of said light in addition to an image capture subsystem, the adaptive optical module comprising:

a wavefront sensor, controller and phase-compensating optical element, wherein the wavefront sensor measures phase aberrations in said retinal reflections and operates in a closed-loop fashion with the controller to control the phase-compensating optical element to compensate for such phase aberrations to produce phase-compensated retinal reflections for output to the image capture subsystem,

wherein said wavefront sensor, phase-compensating optical element, and controller are packaged in a modular housing separate and distinct from the fundus camera body and image capture subsystem, and wherein said adaptive optical module interfaces to the fundus camera body and image capture subsystem via detachable connectors.

2. The adaptive optical module of claim 1, wherein said phase-compensating optical element comprises a deformable mirror.

3. The adaptive optical module of claim 2, wherein said deformable mirror comprises a silicon micro-machined membrane mirror including a silicon chip mounted over a printed circuit board substrate by spacers, wherein a top surface of said silicon chip comprises a membrane which is coated with a reflective layer to form a mirror surface, and wherein the printed circuit board comprises a control electrode structure that operates to deform the shape of the reflective membrane by applying bias and control voltages to the membrane and control electrodes disposed therein.

4. The adaptive optical module of claim 1, wherein said phase-compensating optical element comprises a liquid crystal device.

5. The adaptive optical module of claim 1, wherein said wavefront sensor comprises a lenslet array and an imaging device, wherein said lenslet array spatially samples said distorted wavefronts and focuses samples of the distorted wavefront to form a test spot pattern, and wherein said imaging device captures said test spot pattern, and wherein phase aberrations in said distorted wavefronts are measured by characterizing movement of spots in said test spot pattern.

6. The adaptive optical module of claim 5, wherein said imaging device comprises one of a CCD camera body, CMOS camera body and integrating CCD camera body.

7. The adaptive optical module of claim 5, wherein said wavefront sensor comprises a relay lens operably coupled between said lenslet array and said imaging device, said relay lens and imaging device mounted on a moveable stage that translates linearly along the optical axis of the relay lens and imaging device.

8. The adaptive optical module of claim 7, wherein said lenslet array comprises an array of lenslets each comprising a reference fiducial point that contributes to a reference spot pattern imaged by the relay lens onto the imaging device in a calibration mode.

9. The adaptive optical module of claim 8, wherein a reference null position for calculating movement of a spot in said test spot pattern produced from a given lenslet is derived from location of a spot in said reference spot pattern produced from the given lenslet.

10. The adaptive optical module of claim 9, wherein said calibration mode dynamically assigns non-overlapping subaperatures of the imaging device to lenslets of the lenslet array for use in tracking movement of spots of the test spot pattern.

11. The adaptive optical module of claim 9, wherein said calibration mode dynamically assigns non-overlapping subaperatures of the imaging device to particular lenslets of the lenslet array for use in tracking movement of spots of the test spot pattern, wherein each particular lenslet corresponds to a single spot in both said reference spot pattern and said test spot pattern.

12. The adaptive optical module of claim 1, wherein said image capture subsystem includes an imaging device for capturing an image of the phase-compensated retinal reflections produced by the phase-compensating optical element.

13. The adaptive optical module of claim 12, wherein said imaging device comprises one of a CCD camera body, CMOS camera body, and integrating CCD camera body.

14. The adaptive optical module of claim 1, wherein said image capture subsystem includes a photographic film unit for capturing an image of the phase-compensated retinal produced by the phase-compensating optical element.

15. The adaptive optical module of claim 1, wherein said first light source comprises a flash source.

16. The adaptive optical module of claim 15, wherein said flash source comprises one of a xenon flash lamp and krypton flash lamp.

17. The adaptive optical module of claim 1, wherein said fundus camera body further comprises a second light source, distinct from said first light source, that produces light in an observation mode, wherein said fundus camera body directs light produced from the second light source to the human eye and collects reflections of such light for observation of the human eye.

18. The adaptive optical module of claim 5, further comprising a computing apparatus, operably coupled to the imaging device of said wavefront sensor, executing a graphical user interface program for performing alignment operations of said wavefront sensor.

19. The adaptive optical system of claim 18, wherein said alignment operations comprise at least one of the following:

i) verifying that a real-time display of the image captured by said imaging device has satisfactory characteristics;

ii) adjusting the exposure time of the imaging device;

iii) verifying that an alignment beam is positioned so that it is centered on the lenslet array and imaging device;

iv) verifying that the alignment beam is focused on the lenslet array; and

v) verifying alignment of the optical axis of the wavefront sensor.

20. The adaptive optical module of claim 1, wherein both the adaptive optical module and the image capture subsystem can be selectively interfaced directly to the fundus camera body.

21. The adaptive optical module of claim 1, wherein both the adaptive optical ok module and the image capture subsystem can be selectively interfaced directly to a relay lens adapter that is detachably interfaced to the fundus camera body.

22. A fundus camera comprising:

an optical subsystem that directs light produced from a first light source into the human eye and that collects and collimates retinal reflections of said light;

an adaptive optical subsystem comprising a wavefront sensor, controller, and phase-compensating optical element, wherein the wavefront sensor measures phase aberrations in said retinal reflections and operates in a closed-loop fashion with the controller to control the phase-compensating optical element to compensate for such phase aberrations to produce phase-compensated retinal reflection that are directed to an image capture subsystem,

wherein said optical subsystem, adaptive optical subsystem and image capture subsystem are packaged in separate and distinct modular housings that interface via detachable connectors.

23. The fundus camera of claim 22, wherein said phase-compensating optical element comprises a deformable mirror.

24. The fundus camera of claim 23, wherein said deformable mirror comprises a silicon micro-machined membrane mirror including a silicon chip mounted over a printed circuit board substrate by spacers, wherein a top surface of said silicon chip comprises a membrane which is coated with a reflective layer to form a mirror surface, and wherein the printed circuit board comprises a control electrode structure that operates to deform the shape of the reflective membrane by applying bias and control voltages to the membrane and control electrodes disposed therein.

25. The fundus camera of claim 22, wherein said phase-compensating optical element comprises a liquid crystal device.

26. The fundus camera of claim 22, wherein said wavefront sensor comprises a lenslet array and an imaging device, wherein said lenslet array spatially samples said distorted wavefronts and focuses samples of the distorted wavefront to form a test spot pattern, and wherein said imaging device captures said test spot pattern, and wherein phase aberrations in said distorted wavefronts are measured by characterizing movement of spots in said test spot pattern.

27. The fundus camera of claim 26, wherein said imaging device comprises one of a CCD camera body, CMOS camera body and integrating CCD camera body.

28. The fundus camera of claim 22, wherein said wavefront sensor comprises a relay lens operably coupled between said lenslet array and said imaging device, said relay lens and imaging device mounted on a moveable stage that translates linearly along the optical axis of the relay lens and imaging device.

29. The fundus camera of claim 28, wherein said lenslet array comprises an array of lenslets each comprising a reference fiducial point that contributes to a reference spot pattern imaged by the relay lens onto the imaging device in a calibration mode.

30. The fundus camera of claim 29, wherein a reference null position for calculating movement of a spot in said test spot pattern produced from a given lenslet is derived from location of a spot in said reference spot pattern produced from the given lenslet.

31. The fundus camera of claim 29, wherein said calibration mode dynamically assigns non-overlapping subaperatures of the imaging device to lenslets of the lenslet array for use in tracking movement of spots of the test spot pattern.

32. The fundus camera of claim 29, wherein said calibration mode dynamically assigns non-overlapping subaperatures of the imaging device to particular lenslets of the lenslet array for use in tracking movement of spots of the test spot pattern, wherein each particular lenslet corresponds to a single spot in both said reference spot pattern and said test spot pattern.

33. The fundus camera of claim 22, wherein said image capture subsystem includes an imaging device for capturing an image of the phase-compensated retinal reflections produced by the phase-compensating optical element.

34. The fundus camera of claim 33, wherein said imaging device comprises one of a CCD camera body, CMOS camera body, and integrating CCD camera body.

35. The fundus camera of claim 34, wherein said imaging device is coupled to an image display apparatus via communication link.

36. The fundus camera of claim 35, wherein said communication link comprises a USB interface.

37. The fundus camera of claim 22, wherein said image capture subsystem includes a photographic film unit for capturing an image of the phase-compensated retinal reflections produced by the phase-compensating optical element.

38. The fundus camera of claim 22, wherein said first light source comprises a flash source.

39. The fundus camera of claim 38, wherein said flash source comprises one of a xenon flash lamp and krypton flash lamp.

40. The fundus camera of claim 22, wherein said optical subsystem further comprises a second light source, distinct from said first light source, that produces light in an observation mode, wherein said optical subsystem directs light produced from the second light source to the human eye and collects reflections of such light for observation of the human eye.

41. The fundus camera of claim 40, wherein said second light source comprises one of a halogen lamp and at least one infra-red light emitting diode.

42. The fundus camera of claim 40, wherein said optical subsystem directs reflections derived from the second light source to a view finder for observation of the human eye.

43. The fundus camera of claim 40, wherein said optical subsystem directs reflections derived from the second light source to an imaging device which captures an image for display on an image display for observation of the human eye.

44. The fundus camera of claim 43, wherein said imaging device comprises one of a CCD camera body and a CMOS camera body.

45. The fundus camera of claim 44, wherein said image display comprises a TFT LCD device.

46. The fundus camera of claim 26, further comprising a computing apparatus, operably coupled to the imaging device of said wavefront sensor, executing a graphical user interface program for performing alignment operations of said wavefront sensor.

47. The fundus camera of claim 46, wherein said alignment operations comprise at least one of the following:

i) verifying that a real-time display of the image captured by said imaging device has satisfactory characteristics;

ii) adjusting the exposure time of the imaging device;

iii) verifying that an alignment beam is positioned so that it is centered on the lenslet array and imaging device;

iv) verifying that the alignment beam is focused on the lenslet array; and

v) verifying alignment of the optical axis of the wavefront sensor.

48. The fundus camera of claim 22, wherein both the adaptive optical subsystem and the image capture subsystem can be selectively interfaced directly to the optical subsystem.

49. The fundus camera of claim 22, wherein both the adaptive optical subsystem and the image capture subsystem can be selectively interfaced directly to a relay lens adapter that is detachably interfaced to the optical subsystem.

50. The fundus camera of claim 22, further comprising an internal fixation target that is used to adjust accommodation of the lens of the human eye such that it is focused at (or substantially near) infinity.

51. The fundus camera of claim 22, configured as a desktop instrument.

52. The fundus camera of claim 22, configured as a hand-held instrument.

53. The fundus camera of claim 53, further comprising a strap affixed to the housing of the fundus camera that enables a user to hold the fundus camera by sliding the user'"'"'s hand under the strap.

54. The fundus camera of claim 22, configured as a hand-held binocular instrument having two channels, each having a separate optical subsystem and adaptive optical subsystem.

55. The fundus camera of claim 22, in combination with a lens fabrication system, wherein the adaptive optical subsystem provides data characterizing high order optical aberrations of the eye to the lens fabrication system.

56. The fundus camera of claim 22, in combination with a computer-assisted ophthalmic surgery system, wherein the adaptive optical subsystem provides data characterizing high order optical aberrations of the eye to the computer-assisted ophthalmic surgery system.

57. The fundus camera of claim 22, wherein the adaptive optical subsystem provides data characterizing high order optical aberrations of the eye to a practitioner for ophthalmic treatment of the eye.