Optical translation measurement

• US 6,452,683 B1
• Filed: 03/08/1999
• Issued: 09/17/2002
• Est. Priority Date: 03/09/1998
• Status: Expired due to Term

• Current Assignee: OTM Technologies Ltd.
• Original Assignee: OTM Technologies Ltd.
• Inventors: Lederer, Gilad, Kinrot, Uri, Kinrot, Opher
• Primary Examiner(s): Font, Frank G.
• Assistant Examiner(s): Lee, Andrew H.
• Application Number:
  US09/264,409
• Time in Patent Office: 1,289 Days
• Field of Search: 356/499, 356/28.5, 356/355, 356/357, 356/505, 356/521, 250/237.G
• US Class Current: 356/499
• 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 with incident illumination, having a coherence length, such that the illumination is reflected from portions of the surface, wherein at least part of at least one of the incident and reflected illumination passes through a partially transmitting object that is part of the measuring device;

detecting the illumination reflected from the surface, to generate a detected signal; and

determining the relative motion of the surface parallel to the surface, from the detected signal,

wherein the object and the surface are situated within a distance that is less than the coherence length of the detected illumination.

Claims

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

illuminating the surface with incident illumination, having a coherence length, such that the illumination is reflected from portions of the surface, wherein at least part of at least one of the incident and reflected illumination passes through a partially transmitting object that is part of the measuring device;

detecting the illumination reflected from the surface, to generate a detected signal; and

determining the relative motion of the surface parallel to the surface, from the detected signal,

wherein the object and the surface are situated within a distance that is less than the coherence length of the detected illumination.

2. A method according to claim 1 wherein the transmission of the object is spatially varying.

3. A method according to claim 1 wherein the object is partially reflecting and wherein part of the incident illumination is reflected or diffracted by the object, as a reference illumination and wherein detection of the illumination is coherent, utilizing said reference illumination.

4. A method according to claim 2 wherein the object is partially reflecting and wherein part of the incident illumination is reflected or diffracted by the object, as a reference illumination and wherein detection of the illumination is coherent, utilizing said reference illumination.

5. A method according to claim 2 wherein spatially varying comprises periodic spatially varying.

12. A method according to any of the preceding claims wherein the object is a grating.

13. A method according to claim 12 wherein the grating is placed sufficiently close to the surface such that the surface is in the near field of the grating.

14. A method according to claim 12 wherein the grating is placed sufficiently far from the surface such that the surface is outside the near field of the grating.

15. A method according to any of claims 1-11 wherein the detected illumination is at least partly coherent.

18. A method according to any of claims 1, 6 or 16 wherein determining the relative motion comprises determining variations in the amplitude of the signal with position.

19. A method according to claim 18 wherein the motion is determined from zero crossings of the detected signal.

20. A method according to any of claims 1, 6 or 16 wherein the object has a transmission characteristic that is spatially non-symmetric and including:

determining the direction of the relative motion based on the detected signal.

21. A method according to any of claims 1, 6 or 16 and including determining the magnitude and direction of the translation utilizing two detectors which produce different detected signals depending on the direction of the translation.

22. A method according to claim 21 and including determining the direction of translation from the sign of a phase difference between the different detected signals.

23. A method according any of claims 1, 6 or 16 wherein the illumination is perpendicularly incident on the surface.

24. A method according to any of claims 1, 6 or 16 wherein the surface is an optically diffusely reflecting surface.

25. A method according to claim 1 or claim 16 wherein the surface has no markings indicating position.

26. A method according to any of claims 1, 6 or 16 wherein the illumination comprises visible illumination.

27. A method according to any of claims 1, 6 or 16 wherein the illumination comprises infra-red illumination.

28. A method according to any of claims 1, 6 or 16 and including determining motion in two dimensions transverse to the surface.

29. A method according to claim 28 and including determining motion in a direction perpendicular to the surface.

30. A scanner for reading a document by movement of the scanner over the document comprising:

an optical reading head which detects patterns on the surface of the document; and

an optical detector which determines the motion of the scanner as it is translated across the surface of the document, wherein the optical detector utilizes the method of any of claims 1, 6 or 16 to determine the translation.

31. 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, 6 or 16 to determine the translation of the housing with respect to the surface.

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

placing a partially reflecting object, which is part of the measuring device, adjacent to the surface;

illuminating the object with incident illumination such that part of the incident illumination is reflected or diffracted by the object, as a reference illumination and part is reflected from the surface;

coherently detecting the illumination reflected from the surface utilizing the reference illumination, to generate a detected signal; and

determining the relative motion of the surface parallel to the surface, from the detected signal;

wherein the surface has no markings indicating position.

7. A method according to claim 6 wherein the object is a partially transmitting object and wherein at least part of at least one of the incident and reflected illumination passes through the object.

8. A method according to claim 7 wherein the reflection of the object is spatially varying.

9. A method according to claim 8 wherein spatially varying comprises periodic spatial variation.

10. A method according to claim 6 wherein the reflection of the object is spatially varying.

11. A method according to claim 10 wherein spatially varying comprises periodic spatial variation.

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

placing an object comprising a grating, which is part of the measuring device, adjacent to the surface;

illuminating the grating with incident illumination such that at least part of the illumination is incident on and reflected from the surface, wherein at least one of the incident and reflected illumination passes through the grating;

detecting the illumination reflected from the surface;

generating a signal in response to the reflected illumination; and

determining the relative motion of the surface parallel to the surface, from the detected signal,

wherein the surface is in the near field of the grating.

17. A method according to any of claims 3, 6 or 16 wherein the illumination reflected from the surface is frequency shifted from that of illumination reflected from or diffracted by the object and wherein determining the motion comprises determining the motion based on the frequency shift.