Optical translation measurement

• US 6,330,057 B1
• Filed: 03/08/1999
• Issued: 12/11/2001
• Est. Priority Date: 03/09/1998
• Status: Expired due to Term

• Current Assignee: OTM Technologies Ltd.
• Original Assignee: OTM Technologies Ltd.
• Inventors: Kinrot, Uri, Kinrot, Opher, Lederer, Gilad
• Primary Examiner(s): Buczinski, Stephen C.
• Application Number:
  US09/264,410
• Time in Patent Office: 1,009 Days
• Field of Search: 356/28, 356/28.5, 356/373, 356/375, 356/401
• US Class Current: 356/28
• CPC Class Codes: G01B 2290/30 Grating as beam-splitter
• CPC Class Codes: G01B 9/02045 using the Doppler effect
• CPC Class Codes: G01B 9/02051 Integrated design, e.g. on-chip or monolithic
• CPC Class Codes: G01B 9/02057 by using common path configuration, i.e. reference and object path almost entirely overlapping
• CPC Class Codes: G01B 9/0207 Error reduction by correction of the measurement signal based on independently determined error sources, e.g. using a reference interferometer
• CPC Class Codes: G01D 5/26 characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
• CPC Class Codes: G01P 3/366 by using diffraction of light for measuring speed of fluids G01P5/26
• CPC Class Codes: G01P 3/806 in devices of the type to be classified in G01P3/68
• CPC Class Codes: G01S 17/50 Systems of measurement based on relative movement of target
• CPC Class Codes: G01S 7/4811 common to transmitter and receiver
• CPC Class Codes: G06F 2203/0338 Fingerprint track pad, i.e. fingerprint sensor used as pointing device tracking the fingertip image
• CPC Class Codes: G06F 3/0312 for tracking the rotation of a spherical or circular member, e.g. optical rotary encoders used in mice or trackballs using a tracking ball or in mouse scroll wheels tracking relative movement in co-operation with a regularly or irregularly patterned surface, e.g. as in optical mice G06F3/0317; constructional details of scroll or thumb-wheels G06F3/0362; optical rotary encoders G01D5/3473
• CPC Class Codes: G06F 3/0317 in co-operation with a patterned surface, e.g. absolute position or relative movement detection for an optical mouse or pen positioned with respect to a coded surface
• CPC Class Codes: G06F 3/03543 Mice or pucks G06F3/03541 takes precedence
• CPC Class Codes: G06F 3/03545 Pens or stylus
• CPC Class Codes: G06F 3/03547 Touch pads, in which fingers can move on a surface
• CPC Class Codes: G06F 3/03548 Sliders, in which the moving part moves in a plane
• CPC Class Codes: G06F 3/042 by opto-electronic means
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen

Abstract

A method for determining the relative motion of a surface with respect to a measurement device comprising:

illuminating the surface from a source with incident illumination, such that illumination is reflected from portions of the surface toward a detector;

spatially filtering the reflected illumination such that the phase of the detected optical illumination from a given scatterer on the surface is substantially constant or linearly related to the translation of the surface;

generating a signal by the detector responsive to the illumination incident on the detector; and

determining the relative motion of the surface from the signal.

Claims

1. A method for determining the relative motion of a surface with respect to a measurement device comprising:

illuminating the surface from a source with incident illumination, such that illumination is diffusely reflected from portions of the surface towards a detector;

spatially filtering the diffusely reflected illumination such that the phase of the detected optical illumination from a given scatterer on the surface is substantially constant or linearly related to the translation of the surface;

generating a signal by the detector responsive to the illumination incident on the detector; and

determining the relative motion of the surface in a direction parallel to the surface from the signal;

wherein illuminating the surface comprises illuminating the surface through a partially reflecting object placed adjacent to the surface which object reflects or diffracts illumination to the detector.

2. A method according to claim 1 wherein illuminating comprises illuminating the surface with spatially varying illumination.

3. A method according to claim 1 wherein generating a signal comprises coherent detection of the illumination reflected from the surface utilizing the illumination reflected or diffracted from the partially reflecting or diffracting object.

4. A method according to claim 1 wherein determining the relative motion comprises utilizing a Doppler shift of illumination reflected from the surface.

5. A method according to claim 1 wherein:

the illumination of the surface is substantially collimated; and

including

spatially filtering the illumination reflected from the surface such that substantially only a single spatial frequency of the reflected illumination is detected by the detector.

6. A method according to claim 1 wherein:

illumination of the surface is substantially collimated; and

including

spatially filtering the illumination reflected from the surface such that only illumination reflected from the surface substantially in a single direction is detected by the detector.

7. A method according to claim 1, wherein spatially filtering comprises:

focusing the illumination reflected from the surface with a lens having a focal point; and

placing a pinhole at the focal point of the lens.

8. A method according to claim 1, wherein spatially filtering comprises:

focusing the illumination reflected from the surface with a lens having a focal point; and

placing a single mode optical fiber at the focal point of the lens to transfer illumination to the detector.

9. A method according to claim 1, wherein spatially filtering comprises:

focusing the illumination reflected from the surface with a lens; and

placing a pinhole at an image of the source.

10. A method according to claim 1, wherein spatially filtering comprises:

focusing the illumination reflected from the surface with a lens; and

placing a single mode optical fiber at an image of the source to transfer illumination to the detector.

11. A method according to claim 1 wherein determining the relative motion comprises determining the relative motion in two directions parallel to the surface.

12. A method according to claim 1 wherein determining the relative motion comprises detecting the sense of the direction of the relative motion.

13. A method according to claim 1 wherein determining the motion comprises counting zero-crossings of the signal.

14. A method according to claim 1 wherein illuminating the surface comprises illuminating the surface through a partially diffracting object placed adjacent to the surface which diffracts illumination to the detector.

15. A method according to claim 1 wherein the object is a grating.

16. A method according to claim 14 wherein the object is a grating.

21. A method according to any of claims 1, 11 or 17 and including determining the relative motion in a direction perpendicular to the surface.

25. A method according any of claims 1, 17 or 23 wherein the illumination is perpendicularly incident on the surface.

26. A method according to any of claims 1, 17 or 23 wherein the surface is optically diffusely reflecting surface.

27. A method according to any of claims 1, 17 or 23 wherein the surface has no markings indicating position.

28. A method according to any of claims 1, 17 or 23 wherein the illumination comprises visible illumination.

29. A method according to any of claims 1, 17 or 23 wherein the illumination comprises infra-red illumination.

30. An optical mouse comprising:

a housing having an aperture facing a surface; and

an optical motion detector which views the surface through the aperture, wherein the optical motion detector utilizes the method of any of claims 1, 17 or 23 to determine the translation of the housing with respect to the surface.

17. A method for determining the relative motion of a surface with respect to a measurement device comprising:

illuminating the surface with illumination through a partially transmitting object that is not attached to the surface and is operative to cause spatial variation of the illumination on the surface, such that said illumination is reflected from the surface to illuminate a detector with diffusely reflected illumination which is not an image of a point on or a portion of the surface;

simultaneously illuminating the detector with reference illumination derived from said incident illumination;

coherently detecting the reflected illumination received by the detector utilizing said reference illumination such that the detector generates a signal;

determining the relative motion of the surface parallel to the surface, based on variations of the signal with time.

18. A method according to claim 17 wherein the incident illumination is at a given wavelength and wherein the reference illumination is at the same wavelength such that the coherent detection is homodyne detection.

19. A method according to claim 17 wherein spatially varying the illumination of the surface comprises:

illuminating the surface through a transmission grating having spatially varying periodic transmission.

20. A method according to claim 17 wherein spatially varying the illumination of the surface comprises:

illuminating the surface through a grating which specularly reflects a portion of the illumination incident upon it toward the detector to form said reference illumination.

22. A method according to claim 17 wherein the object is a partially reflecting object and wherein illumination reflected or diffracted from the object provides a local oscillator field for said coherent detection.

23. A method for determining the relative motion of a surface with respect to a measurement device comprising:

illuminating the surface with illumination having a coherence length, such that illumination is reflected from portions of the surface;

placing a grating within the coherence length from the surface;

coherently detecting diffusely reflected illumination reflected from the surface, and utilizing illumination reflected from or diffracted by the grating as a local oscillator to form a signal; and

determining the relative motion of the surface, in a direction parallel to the surface, from a characteristic of the signal.

24. A method according to claim 23 wherein the relative motion is detected utilizing a Doppler shift of the illumination reflected from the surface.

31. A method for determining the relative motion of a surface with respect to a measurement device comprising:

illuminating the surface from a source, with spatially varying incident illumination, such that a portion of the illumination is diffusely reflected from portions of the surface towards a detector;

spatially filtering the diffusely reflected illumination such that only illumination reflected from the surface substantially in a single direction is detected by the detector;

generating a signal by the detector responsive to the illumination incident on the detector; and

determining the relative motion of the surface in a direction parallel to the surface from the signal, responsive to a characteristic of the spatial variation.

32. A method according to claim 31 wherein the spatial variation is periodic spatial variation.

33. A method according to claim 32 wherein the characteristic comprises the period of the spatial variation.

34. A method according to claim 31 wherein the phase of the detected optical illumination from a given scatterer on the surface is substantially constant or linearly related to the translation of the surfaces.