Miniature image acquistion system using a scanning resonant waveguide

• US 6,294,775 B1
• Filed: 10/22/1999
• Issued: 09/25/2001
• Est. Priority Date: 06/08/1999
• Status: Expired due to Term

• Current Assignee: Washington University In St Louis
• Original Assignee: University of Washington
• Inventors: Seibel, Eric J., Furness, Thomas A. III
• Primary Examiner(s): LE, QUE TAN
• Application Number:
  US09/425,528
• Time in Patent Office: 704 Days
• Field of Search: 250/208.1, 250/227.11, 250/227.14, 250/559.07, 250/559.4, 250/216, 356/241, 128/665, 128/673, 128/657, 128/658, 128/632-634, 359/209, 359/212, 385/12, 385/13
• US Class Current: 250/208.1
• CPC Class Codes: A61B 1/0008 characterised by distal tip features
• CPC Class Codes: A61B 1/00172 with means for scanning
• CPC Class Codes: A61B 1/00193 adapted for stereoscopic vision
• CPC Class Codes: A61B 1/05 characterised by the image sensor, e.g. camera, being in the distal end portion
• CPC Class Codes: A61B 1/07 using light-conductive means, e.g. optical fibres
• CPC Class Codes: A61B 3/12 for looking at the eye fundus, e.g. ophthalmoscopes A61B3/13 takes precedence
• CPC Class Codes: G02B 26/103 having movable or deformable optical fibres, light guides or waveguides as scanning elements light guides per se G02B6/00

Abstract

A minimally invasive, medical, image acquisition having a flexible optical fiber serving as an illuminating wave guide. In one resonance mode, the distal end of the fiber is a stationary node. The fiber includes a lens at the distal tip which collimates emitted light. A scan lens is positioned off the end of the fiber. The relative magnifications of the lenses and the relative positions determines the pixel resolution. In particular, the illumination fiber outputs a light beam or pulse which illuminates a precise spot size. A photon detector detects reflected photons from the object, including the spot. Pixel resolution is determined by the area of the illumination spot (and thus the lens configuration), rather than an area sensed by the detector.

Claims

1. A method for acquiring an image of a target surface, comprising the steps of:

outputting a beam of light from a resonant fiber waveguide, the waveguide scanning the output beam along a scan path;

focusing the beam with a scan lens onto a target surface being scanned, wherein at a given time the beam is focused to impinge on a spot of the target, the spot being an illuminated spot, the illuminated spot varying with time as the beam is scanned onto the target surface;

detecting light reflected from an area of the target surface which is greater than an area defined the illuminated spot;

correlating the given time at which the beam focuses onto the illuminated spot with the detected reflected light to acquire a pixel of the image, wherein resolution of the pixel corresponds to the area defined by the illuminated spot, wherein over time a plurality of pixels are acquired.

2. The method of claim 1, further comprising the step of collimating the light output from the resonant fiber waveguide.

3. The method of claim 1, further comprising the step of:

deflecting the waveguide in a resonant mode in which a distal tip of the waveguide is a stationary node, the distal tip changing orientation to angularly scan the output beam.

4. The method of claim 1, in which the step of detecting is performed by a photon detector which is stationary relative to a motion of the waveguide which occurs during scanning along the scan path.

5. The method of claim 1, in which the step of detecting is performed by a photon detector which does not move synchronously with the resonant waveguide.

6. The method of claim 1, in which the scan path is a raster scan path defined by a first fast scanning axis and a second scanning axis, and in which the waveguide resonates to deflect the output beam along the fast scanning axis.

7. The method of claim 6, in which the waveguide resonates to deflect the output beam simultaneously along the fast scanning axis and the second scanning axis.

8. The method of claim 1, in which the step of detecting is performed by a photon detector which is stationary relative to the fast scanning axis.

9. The method of claim 1, in which the scan path is a spiral scan path.

10. The method of claim 1, in which the scan path is a radial scan path.

11. The method of claim 1, in which the step of detecting comprises the steps of:

collecting reflected light at an optical fiber;

routing the collected light to a scanner;

scanning the collected light with the scanner onto a viewer'"'"'s eye which detects the collected light.

12. The method of claim 11, in which the step of detecting further comprises optically amplifying the collected light by adding photons having properties which are the same as photons of the collected light.

13. The method of claim 1, in which the step of detecting comprises the steps of:

collecting reflected light at an optical fiber;

routing the collected light to a scanner;

scanning the collected light with the scanner onto a display screen;

wherein the reflected light scanned onto the display screen is not stored or sampled.

14. The method of claim 13, in which a portion of the reflected light is scanned onto the display screen without being stored or sampled, while another portion of the reflected light is split off by a beam splitter and routed for storage.

15. The method of claim 1, in which the beam of light is a first beam of light, and further comprising, prior to the step of outputting the steps of:

generating a second beam of light of a first color and a third beam of light of a second color; and

combining the second beam and the third beam before entering the resonant waveguide, the combined second beam and third beam forming the first beam which is output from the resonant waveguide.

16. The method of claim 1, in which the output beam of light is a sequence of light pulses, and wherein the step of detecting is synchronized with the sequence of light pulses, the detected reflected light at said given time corresponding to a given light pulse and said acquired pixel.

17. The method of claim 1, in which the step of outputting comprises outputting a beam of ultraviolet light, and the step of detecting comprises detecting light reflected from said area.

18. The method of claim 1, in which the step of outputting comprises outputting a beam of infrared light, and the step of detecting comprises detecting infrared light reflected from said area.

19. A system for acquiring an image of a target surface, comprising:

a light source which emits light;

a flexible, optical waveguide which receives the emitted light and directs the light toward a target surface, wherein at a given time the light impinges on a spot of the target surface, the spot being an illuminated spot;

an actuator which deflects the waveguide into a resonant motion, the directed light tracing a scan path along the target surface;

a photon detector having an active viewing area of the target surface which exceeds size of the illuminated spot; and

a correlator which correlates sampling time of the photon detector with the light as the light traces a scan path, wherein pixels are acquired of an image of a portion of the target surface, wherein resolution of each one pixel of the acquired pixels corresponds to the size of the illuminated spot.

20. The system of claim 19, further comprising a display device coupled to the photon detector for displaying the image in real time as pixels are acquired.

21. The system of claim 20, in which the display device displays the image without resampling an output signal of the photon detector said output signal corresponding to a sequence of acquired pixels.

22. The system of claim 19, wherein the photon detector generates an output signal corresponding to a sequence of acquired pixels, and further comprising means, coupled to the photon detector for storing the acquired pixels.

23. The system of claim 19, further comprising a focusing lens spaced off the distal tip of the waveguide which focuses light onto the target surface as the light traces a scan path.

24. The system of claim 23, further comprising a collimating lens at a distal tip of the waveguide for collimating light directed toward the focusing lens.

25. The system of claim 19, further comprising means for driving the actuator to deflect the waveguide in a resonant mode in which a distal tip of the waveguide is a stationary node, the distal tip changing orientation to angularly scan the light.

26. The system of claim 19, in which the scan path is a spiral scan path.

27. The system of claim 19, in which the scan path is a radial scan path.

28. The system of claim 19, in which the scan path is a first scanning axis of a raster scan path having the first fast scanning axis and a second scanning axis, and in which the waveguide resonates to deflect the output beam along the first scanning axis.

29. The system of claim 28, in which the waveguide resonates to deflect the output beam simultaneously along the first scanning axis and the second scanning axis.

30. The system of claim 29, in which the actuator is a first actuator and further comprising a second actuator which causes the light to move along the second scanning axis.

31. The system of claim 29, in which the photon detector is mounted to a base which is stationary relative to the first scanning axis.

32. The system of claim 19, in which the photon detector is mounted to a base which is stationary relative to the scan path.

33. The system of claim 19, in which the light source is a first light source emitting light of a first color, the system further comprising a second light source emitting light of a second color, and a combiner which combines the light emitted from the first light source and the second light source, the combined light being received by the waveguide and being directed toward the target surface.

34. The system of claim 19, in which the photon detector comprises a plurality of photon detectors positioned and sampled for stereoscopic viewing of the target surface.

35. The system of claim 19, in which the photon detector comprises a plurality of photon detectors and light filters for detecting prescribed wavelengths and corresponding colors of light.

36. The system of claim 19, in which the photon detector comprises a plurality of photon detectors and light filters for detecting prescribed polarizations.

37. The system of claim 19, in which the photon detector comprises a plurality of photon detectors positioned and sampled to implement common mode rejection of ambient light, while detecting photons of light which are emitted by the waveguide then reflected by the target surface.

38. The system of claim 23, in which the waveguide and actuator are enclosed in a sheath which is sealed by the focusing lens.

39. An image acquisition system, comprising:

a light source which emits light;

an optical waveguide which receives the emitted light and directs the light toward a target surface, wherein at a given time the light impinges on a spot of the target surface, the spot being an illuminated spot;

an actuator for deflecting the waveguide in a resonant mode, wherein the light traces a scan path along the target surface;

a collector fiber which collects light over an area of the target surface which includes and exceeds an area of the illuminated spot;

a scanning device optically coupled to the collector fiber which scans the collected light onto a second surface;

wherein a given time at which the light impinges on the target surface is synchronized with the collection of light and scanning of collected light to acquire a portion of an image of the target surface, and wherein image resolution is determined by the area of the illuminated spot, wherein the collector fiber collects photons of light and the second surface receives collected photons of light directly, as distinguished from the second surface receiving a sampled representation of the collected light.

40. The system of claim 39, in which the scanning device is a retinal scanning device which scans the collected light onto a retina of a viewer'"'"'s eye, the retina being the second surface.

41. The system of claim 39, in which the scanning device scans the collected light onto a display screen in real time as pixels are acquired, the display screen being the second surface.

42. The system of claim 39, further comprising:

a first lens at a distal tip of the waveguide for collimating light;

a second lens spaced off the distal tip of the waveguide and away from the first lens which focuses light onto the target surface as the light traces a scan path.

43. The system of claim 39, in which the actuator is a first actuator and the scan path is a first scanning axis;

the system further comprising a second actuator for scanning light along a second scanning axis.

44. The system of claim 39, in which the actuator deflects the waveguide in a resonant mode in which a distal tip of the waveguide is a stationary node, the distal tip changing orientation to angularly scan the light along the scan path.

45. The system of claim 39, in which the collector fiber is stationary relative to a motion of the waveguide.

46. The system of claim 39, in which the light source is a first light source emitting light of a first color, the system further comprising a second light source emitting light of a second color, and a combiner which combines the light emitted from the first light source and the second light source, the combined light being received by the waveguide and being directed toward the target surface.

47. The system of claim 39, in which said light is ultraviolet light and wherein the light source emits ultraviolet light.

48. The system of claim 39, in which said light is infrared light and wherein the light source emits infrared light.

49. A medical apparatus for acquiring an image of a target surface, comprising:

a light source which emits light;

a flexible, optical waveguide which receives the emitted light and directs the light toward a target surface, wherein at a given time the light impinges on a spot of the target surface, the spot being an illuminated spot;

an actuator which deflects the waveguide into a resonant motion, the directed light tracing a scan path along the target surface;

a photon detector having an active viewing area of the target surface which exceeds size of the illuminated spot; and

a correlator which correlates sampling time of the photon detector with the light as the light traces a scan path, wherein pixels are acquired of an image of a portion of the target surface, wherein resolution of each one pixel of the acquired pixels corresponds to the size of the illuminated spot.

50. The apparatus of claim 49, further comprising a display device coupled to the photon detector for displaying the image in real time as pixels are acquired, in which the display device displays the image without resampling an output signal of the photon detector said output signal corresponding to a sequence of acquired pixels.

51. The apparatus of claim 49, further comprising a focusing lens spaced off the distal tip of the waveguide which focuses light onto the target surface as the light traces a scan path.

52. The apparatus of claim 49, further comprising means for driving the actuator to deflect the waveguide in a resonant mode in which a distal tip of the waveguide is a stationary node, the distal tip changing orientation to angularly scan the light.

53. An endoscopic device for acquiring an image of a target surface, comprising:

a light source which emits light;

a flexible, optical waveguide which receives the emitted light and directs the light toward a target surface, wherein at a given time the light impinges on a spot of the target surface, the spot being an illuminated spot;

an actuator which deflects the waveguide into a resonant motion, the directed light tracing a scan path along the target surface;

a photon detector having an active viewing area of the target surface which exceeds size of the illuminated spot; and

a correlator which correlates sampling time of the photon detector with the light as the light traces a scan path, wherein pixels are acquired of an image of a portion of the target surface, wherein resolution of each one pixel of the acquired pixels corresponds to the size of the illuminated spot.

54. The system of claim 53, further comprising a display device coupled to the photon detector for displaying the image in real time as pixels are acquired, in which the display device displays the image without resampling an output signal of the photon detector said output signal corresponding to a sequence of acquired pixels.

55. The system of claim 53, further comprising a focusing lens spaced off the distal tip of the waveguide which focuses light onto the target surface as the light traces a scan path.

56. The apparatus of claim 53, further comprising means for driving the actuator to deflect the waveguide in a resonant mode in which a distal tip of the waveguide is a stationary node, the distal tip changing orientation to angularly scan the light.

57. A medical apparatus, comprising:

a light source which emits light;

an optical waveguide which receives the emitted light and directs the light toward a target surface, wherein at a given time the light impinges on a spot of the target surface, the spot being an illuminated spot;

an actuator for deflecting the waveguide in a resonant mode, wherein the light traces a scan path along the target surface;

a collector fiber which collects light over an area of the target surface which includes and exceeds an area of the illuminated spot;

a scanning device optically coupled to the collector fiber which scans the collected light onto a second surface;

wherein a given time at which the light impinges on the target surface is synchronized with the collection of light and scanning of collected light to acquire a portion of an image of the target surface, and wherein image resolution is determined by the area of the illuminated spot, wherein the collector fiber collects photons of light and the second surface receives collected photons of light directly, as distinguished from the second surface receiving a sampled representation of the collected light.

58. An endoscopic device, comprising:

a light source which emits light;

an optical waveguide which receives the emitted light and directs the light toward a target surface, wherein at a given time the light impinges on a spot of the target surface, the spot being an illuminated spot;

an actuator for deflecting the waveguide in a resonant mode, wherein the light traces a scan path along the target surface;

a collector fiber which collects light over an area of the target surface which includes and exceeds an area of the illuminated spot;

a scanning device optically coupled to the collector fiber which scans the collected light onto a second surface;

wherein a given time at which the light impinges on the target surface is synchronized with the collection of light and scanning of collected light to acquire a portion of an image of the target surface, and wherein image resolution is determined by the area of the illuminated spot, wherein the collector fiber collects photons of light and the second surface receives collected photons of light directly, as distinguished from the second surface receiving a sampled representation of the collected light.