Method and devices for inspecting and calibrating of stereoscopic endoscopes

• US 6,801,325 B2
• Filed: 06/25/2002
• Issued: 10/05/2004
• Est. Priority Date: 06/25/2002
• Status: Expired due to Term

• Current Assignee: Intuitive Surgical Operations, Inc. (Intuitive Surgical Holdings, LLC)
• Original Assignee: Intuitive Surgical Incorporated (Intuitive Surgical Holdings, LLC)
• Inventors: Petersen, Alan, Farr, Mina
• Primary Examiner(s): Font, Frank G.
• Assistant Examiner(s): Lyons, Michael A.
• Application Number:
  US10/183,976
• Publication Number:
  US 20030234940A1
• Time in Patent Office: 833 Days
• Field of Search: 356/520, 348/45, 348/65, 600/111, 600/117, 600/160, 600/166
• US Class Current: 356/520
• CPC Class Codes: G01M 11/00 Testing of optical apparatus; Testing structures by optical methods not otherwise provided for

Abstract

Methods and devices for inspecting and calibrating a stereoscopic imaging device, such as a binocular endoscope. In one exemplary embodiment, the method of the present invention measures a fringe pattern from light emitted through two channels of the device. An angle of each of the fringe pattern can be measured so as to allow a diopter difference between the channels to be calculated.

Claims

1. A method of calibrating a first channel and a second channel of a stereoscopic imaging device, the method comprising:

comparing an angle of a straight line segment of a fringe pattern obtained from the first channel with an angle of a straight line segment of a fringe pattern obtained from the second channel to determine an angle difference between the first channel and second channel; and

using the angle difference to calculate a diopter difference between the first and second channel.

2. The method of claim 1 comprising:

obtaining the fringe pattern of the first channel by delivering a laser beam through the first channel and reflecting the laser beam after it exits the first channel off of a shear plate so as to create the fringe pattern;

measuring the angle of the straight line segment of the fringe pattern of the first channel;

obtaining the fringe pattern of the second channel by delivering the laser beam through the second channel and reflecting the laser beam after it exits the first channel off of the shear plate so as to create the fringe pattern on the camera; and

measuring the angle of the straight line segment of the fringe pattern of the second channel.

3. The method of claim 2 comprising moving the shear plate and the camera from a first position to a second position, wherein in;

the first position the shear plate and camera receive a laser beam light from the first channel and wherein in the second position the shear plate and camera receive the laser beam light from the second channel.

4. The method of claim 2 comprising expanding the laser beam such that the laser beam has a cross section that is large enough to simultaneously enter the first and second channel.

5. The method of claim 2 comprising moving the stereoscopic imaging device from a first position to a second position, wherein in the first position the stereoscopic imaging device is positioned so that the laser beam enters only the first channel, and wherein in the second position the imaging device is positioned such that the laser beam enters only the second channel.

6. The method of claim 2 comprising positioning a compensator lens to compensate for an optical assembly of the first channel and second channel such that a laser beam exiting the first channel and second channel is collimated.

7. The method of claim 2 wherein obtaining the fringe pattern comprises reflecting the fringe pattern from the shear plate onto an image capture device to capture at least one image of the fringe pattern, and wherein measuring comprises signal processing the image(s) of the fringe pattern.

8. The method of claim 1 wherein using the angle difference comprises applying a linear equation to the angle difference to calculate the diopter difference.

9. The method of claim 1 wherein the stereoscopic imaging device is a stereoscopic endoscope.

10. A method for calibrating a stereoscopic endoscope, the endoscope comprising a first channel and a second channel, wherein the first channel and second channel each comprise a first end and a second end, the method comprising:

delivering a laser beam into at least one of the first ends of the of the first and second channel so as to emit light through at least one of the second ends of the first channel and second channel;

reflecting the light that exits the second end of the first channel and the second channel off of a shear plate, wherein the shear plate create two beams of light that create a fringe pattern comprising straight line segments;

measuring an angle of the straight line segments for the first channel and second channel; and

comparing the measured angle of the first channel and the second channel to determine a diopter difference between the first channel and the second channel.

11. The method of claim 10 wherein measuring an angle comprises imaging the straight line segments of the first channel and second channel with a camera.

12. The method of claim 11 comprising placing a neutral density filter on the camera to reduce a brightness of the fringe pattern.

13. The method of claim 10 comprising expanding the laser beam so that the beam is large enough to simultaneously enter the first ends of both the first and second channel.

14. The method of claim 10 comprising positioning a compensator lens to collimate the light exiting the first channel and second channel.

15. The method of claim 10 comprising moving the shear plate between a first position and a second position,

wherein the shear plate in the first position reflects light exiting the second end of the first channel, and

wherein the shear plate in the second position reflects light exiting the second end of the second channel,

wherein the fringe patterns for the first channel and second channel are created separately.

16. The method of claim 10 comprising providing a microscope lens assembly in an optical path of the laser beam before the laser beam enters the first end of the first channel and second channel.

17. A method of calibrating a stereoscopic imaging device, the stereoscopic imaging device comprising a first imaging channel and a second imaging channel, the method comprising:

obtaining a fringe pattern for the first imaging channel;

calculating an angle of a straight line segment of the fringe pattern for the first imaging channel;

obtaining a fringe pattern for the second imaging channel;

calculating an angle for a straight line segment of the fringe pattern for the second imaging channel;

comparing the angles of the first imaging channel and second imaging channel; and

calculating a diopter difference between the first imaging channel and the second imaging channel from the comparison of the angles.

18. The method of claim 17 wherein obtaining a fringe pattern for the first imaging channel comprises directing a laser beam through the first imaging channel and reflecting the laser beam off of a shear plate and onto a camera, and

wherein obtaining a fringe pattern for the second imaging channel comprises directing the laser beam through the second imaging channel and reflecting the laser beam off of the shear plate and onto the camera.

19. The method of claim 18 comprising moving the shear plate and camera from a first position to a second position, in the first position the shear plate and camera intercept the laser beam from the first imaging channel, in the second position the shear plate and camera intercept the laser beam exiting the second imaging channel.

20. The method of claim 18 comprising moving the stereoscopic imaging device so that only one of the first and second imaging channels is in the path of the laser beam.

21. The method of claim 18 comprising expanding the laser beam so that the laser beam is simultaneously directed through the first imaging channel and the second imaging channel.

22. A method of focusing a stereoscopic endoscope, the method comprising:

providing a stereoscopic endoscope comprising a left channel and a right channel;

delivering a laser beam comprising a cross-section large enough to enter both the left channel and right channel, wherein an optical assembly of the first channel and second channel causes the laser beam to diverge;

compensating light that exits the left channel and right channel to collimate the light;

creating a fringe pattern for the left channel and right channel by reflecting the collimated light off of a shear plate, wherein the fringe pattern comprises straight line segments that define angles which varies with a diopter of the light; and

comparing the angles of the left channel and right channel, wherein a difference in the angles of the straight line segments of the left channel and right channel are used to calculate a diopter mismatch between the left channel and right channel.

23. The method of claim 22 wherein delivering a laser beam comprises expanding the laser beam from a first cross section to the cross section that is large enough to enter both the first and second channels.

24. The method of claim 22 wherein a diopter mismatch of ±

0.2 diopters is deemed to be matching.

25. A system for calibrating a stereoscopic imaging device, the imaging devices comprising a first channel comprising a first end, a second end, and an optical assembly between the first end and the second end, and a second channel comprising a first end, a second end, and an optical assembly between the first end and the second end, the system comprising:

a laser that generates a laser beam along an optical axis, the laser beam enters at least one of the first ends of the first channel and second channel and through the optical assemblies;

at least one compensator lens positioned adjacent the second end of the first channel and right channel, wherein the compensator lens collimates diverging light that exits the second ends;

at least one shear plate positioned to receive the collimated light after it exits the compensator lens, wherein the shear plate creates for the first channel and second channel an interference fringe pattern comprising straight line segments that define an angle that varies with a diopter of the optical assemblies of the first channel and second channel, wherein a difference in the angles of the straight line segments of the first channel and second channel is used to calculate a diopter mismatch between the first channel and second channel.

26. The system of claim 25 comprising a beam expander positioned within the optical axis of the laser beam which expands the laser beam so that the laser beam is delivered simultaneously into the first ends of the first channel and second channel.

27. The system of claim 26 comprising an objective lens positioned in the optical axis of the laser beam between the beam expander and the first end of the first channel and second channel.

28. The system of claim 25 comprising:

at least one camera that obtains an image of the fringe pattern of the first channel and second channel; and

a computer system coupled to the at least one camera that can analyze the image of the fringe pattern to calculate the angle of the fringe pattern for the first channel and second channel.

29. The system of claim 28 wherein the camera comprises a neutral density filter.

30. The system of claim 28 wherein the computer system comprises frame grabbing software to grab at least one image of the fringe patterns.

31. The system of claim 28 wherein the at least one shear plate comprises only one shear plate and the at least one camera comprises only one camera, wherein the shear plate and camera are movable to allow for independent analysis of the fringe pattern for the first channel and second channel.

32. The system of claim 31 wherein the shear plate and camera are each positioned on movable positioning devices.

33. The system of claim 25 wherein the stereoscopic imaging device is a stereoscopic endoscope.

34. The system of claim 33 wherein the stereoscopic endoscope is a Scholly endoscope.

35. A device for calibrating a stereoscopic endoscope, having a first channel and a second channel, the device comprising:

a laser source that delivers a laser beam along an optical axis and into at least one of the first channel and second channel;

a fringe pattern device that generates a fringe pattern from light that exits the first channel and second channel;

an image device that captures at least one image of the fringe patterns; and

a controller assembly that is configured to calculate an angle of the fringe pattern, determine an angle difference of the fringe patterns, and determine a diopter difference between the first channel and second channel using the angle difference.

36. The device of claim 35 comprising a collimating lens to collimate the light that exits the first and second channel.

37. The device of claim 35 comprising a beam expander that expands the laser beam so that the laser beam enters both the first channel and second channel.

38. The device of claim 35 comprising a movable support device coupled to the fringe pattern device and image device, wherein the fringe pattern device and image device are movable so as to be able to separately capture the fringe pattern from the first channel and second channel.

39. The device of claim 35 wherein the fringe pattern device is a shear plate.

40. A kit for focus matching a first channel and a second channel of a stereoscopic imaging device, the kit comprising:

a laser source that generates a laser beam;

a shear plate that reflects light exiting at least one of the first channel and second channel and creates a fringe pattern from the reflected light from the first channel and second channel;

a camera that obtains an image of the fringe patterns for the first channel and second channel; and

a computer system that compares angles of the fringe patterns of the first channel and second channel and calculates a diopter difference between the first channel and the second channel.

41. The kit of claim 40 comprising a beam expander that expands the beam so that the laser beam has a cross-sectional size that is large enough to simultaneously enter both the first channel and second channel.

42. The kit of claim 40 comprising a neutral density filter that reduces a brightness of the fringe pattern.

43. The kit of claim 40 comprising a collimating lens that collimates light that exits the first channel and second channel.

44. The kit of claim 40 comprising a movable support device for the camera and shear plate that moves the camera and shear plate from a first position to a second position, wherein the movable support device can position the shear plate and camera in the first position captures light and the fringe pattern from the first channel and the shear plate and camera in the second position captures light and the fringe pattern from the second channel.