System and method for performing optical navigation using scattered light

• US 8,138,488 B2
• Filed: 10/31/2007
• Issued: 03/20/2012
• Est. Priority Date: 10/31/2007
• Status: Active Grant

• Current Assignee: PixArt Imaging Incorporated
• Original Assignee: Avago Technologies ECBU IP Singapore Pte Limited (Broadcom, Inc.)
• Inventors: Grot, Annette C.
• Primary Examiner(s): Le, Que T
• Assistant Examiner(s): Bui Pho, Pascal M
• Application Number:
  US11/932,783
• Publication Number:
  US 20090108175A1
• Time in Patent Office: 1,602 Days
• Field of Search: 250/221, 250/208.1, 250/559.29, 250/559.32, 250/559.04, 250/559.36, 345157-167, 356/498, 356337-343, 356/612, 356/614
• US Class Current: 250/559.29
• 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

Abstract

A system and method for performing optical navigation uses scattered light to produce frames of image data to estimate displacement with respect to a target surface. The scattered light is produced from an illumination beam of light emitted along a first optical axis onto the target surface. The illumination beam of light also produces a specularly reflected beam of light along a second optical axis. The scattered light about a third optical axis, which is offset by a predefined angle with respect to the second optical axis, is received at an image sensor array to produce the frames of image.

Claims

1. A system for performing optical navigation, the system comprising;

a light source positioned to emit an illumination beam of light along a first optical axis onto a target surface at a nonzero angle of incidence with respect to the normal to the target surface to produce a specularly reflected beam of light along a second optical axis from the target surface and to produce scattered light along a third optical axis from the target surface;

an image sensor array positioned to receive the scattered light from the target surface about the third optical axis, the third optical axis being offset by a predefined angle from the second optical axis of the specularly reflected beam of light, the third optical axis being positioned at a nonzero angle with respect to the normal to the target surface, the image sensor array being further positioned such that most or all of the specularly reflected beam of light does not strike the image sensor array, the image sensor array being configured to produce frames of image data from the received scattered light, the image sensor array being positioned to receive the scattered light about the third optical axis, where the third optical axis is offset by the predefined angle of five to twenty-five degrees from the second optical axis; and

a processor operably connected to the image sensor array to receive and correlate the frames of image data to estimate displacement with respect to the target surface when the target surface is a glass-like surface with small perturbations that produces the scattered light at angles near the third optical axis.

2. The system of claim 1 wherein the light source is positioned to emit the illumination beam of light along the first optical axis onto the target surface at the nonzero angle of incidence that is greater than thirty degrees.

3. The system of claim 1 further comprising illumination optics positioned between the target surface and the light source to receive the illumination beam of light from the light source and direct the illumination beam of light onto the target surface along the first optical axis.

4. The system of claim 3 wherein the light source is an incoherent light source and the illumination optics include a diffractive optical element to provide illumination on the target surface with uniform radial angles about the third optical axis.

5. The system of claim 1 wherein the image sensor array is positioned along the third optical axis.

6. The system of claim 1 further comprising collection optics positioned along the third optical axis to direct the scattered light about the third optical axis to the image sensor array and to direct the specularly reflected beam of light away from the image sensor array.

7. The system of claim 6 wherein the collection optics includes an imaging lens configured to direct the scattered light about the third optical axis to the image sensor array.

8. The system of claim 1 further comprising at least one aperture positioned along the third optical axis between the target surface and the collection optics or between the collection optics and the image sensor array to transmit the scattered light about the third optical axis, the at least one aperture being positioned and configured to block at least some of the specularly reflected beam of light.

9. The system of claim 1 further comprising multiple light sources positioned to emit illumination beams of light along different illumination optical axes onto the target surface so that scattered light from each of the illumination beams of light about the third optical axis is received at the image sensor array.

10. The system of claim 9 wherein the multiple light sources are positioned such that the illumination beams of light strike a common region on the target surface and such that optical axes of specularly reflected beams of light due to the illumination beams of light circumscribe the third optical axis.

11. The system of claim 1 wherein the light source is positioned to emit the illumination beam of light along the first optical axis onto the target surface at the nonzero angle of incidence of approximately thirty-six degrees and wherein the third optical axis is offset by the predefined angle of approximately fourteen degrees from the second optical axis.

12. A system for performing optical navigation, the system comprising;

a light source positioned to emit an illumination beam of light along a first optical axis onto a target surface at a nonzero angle of incidence with respect to the normal to the target surface to produce a specularly reflected beam of light along a second optical axis from the target surface and to produce scattered light along a third optical axis from the target surface;

an image sensor with an array of photosensitive elements positioned to receive the scattered light from the target surface about the third optical axis at the array of photosensitive elements, the third optical axis being offset by a predefined angle from the second optical axis of the specularly reflected beam of light, the third optical axis being positioned at a nonzero angle with respect to the normal to the target surface, the image sensor being further positioned such that most or all of the specularly reflected beam of light does not strike the array of photosensitive elements, the image sensor being configured to produce frames of image data from the received scattered light;

collection optics positioned between the target surface and the image sensor to optically manipulate the scattered light about the third optical axis onto the array of photosensitive elements, the image sensor being positioned to receive the scattered light about the third optical axis from the collection optics at the array of photosensitive elements, where the third optical axis is offset by the predefined angle of five to twenty-five degrees from the second optical axis; and

a processor operably connected to the image sensor to receive and correlate the frames of image data to estimate displacement with respect to the target surface when the target surface is a glass-like surface with small perturbations that produces the scattered light at angles near the third optical axis.

13. The system of claim 12 wherein the light source is positioned to emit the illumination beam of light along the first optical axis onto the target surface at the nonzero angle of incidence that is greater than thirty degrees.

14. The system of claim 12 further comprising illumination optics positioned between the target surface and the light source to receive the illumination beam of light from the light source and direct the illumination beam of light onto the target surface along the first optical axis.

15. The system of claim 14 wherein the light source is an incoherent light source and the illumination optics include a diffractive optical element to provide uniform illumination on the target surface with uniform radial angles.

16. The system of claim 12 wherein the array of photosensitive elements of the image sensor is positioned along the third optical axis.

17. The system of claim 12 wherein the collection optics includes an imaging lens configured to direct the scattered light about the third optical axis to the image sensor array and wherein the collection optics is configured to direct the specularly reflected beam of light away from the image sensor array.

18. The system of claim 12 further comprising multiple light sources positioned to emit illumination beams of light along different illumination optical axes onto the target surface so that scattered light from each of the illumination beams of light about the third optical axis is received at the image sensor array.

19. The system of claim 18 wherein the multiple light sources are positioned such that the illumination beams of light strike a common region on the target surface and such that optical axes of specularly reflected beams of light due to the illumination beams of light circumscribe the third optical axis.

20. The system of claim 12 wherein the light source is positioned to emit the illumination beam of light along the first optical axis onto the target surface at the nonzero angle of incidence of approximately thirty-six degrees and wherein the third optical axis is offset by the predefined angle of approximately fourteen degrees from the second optical axis.

21. A method for performing optical navigation, the method comprising:

emitting an illumination beam of light along a first optical axis onto a target surface at a nonzero angle of incidence with respect to the normal to the target surface to produce a specularly reflected beam of light along a second optical axis from the target surface and to produce scattered light along a third optical axis from the target surface;

receiving the scattered light from the target surface about the third optical axis at an image sensor array that is positioned such that most or all of the specularly reflected beam of light does not strike the image sensor array, the third optical axis being offset by a predefined angle from the second optical axis of the specularly reflected beam of light, the third optical axis being positioned at a nonzero angle with respect to the normal to the target surface and wherein the predefined angle is five to twenty-five degrees; and

accumulating electrical signals at the image sensor array to produce frames of image data in response to the received scattered light to estimate displacement with respect to the target surface when the target surface is a glass-like surface with small perturbations that produces the scattered light at angles near the third optical axis.

22. The method of claim 21 wherein the nonzero angle of incidence is greater than thirty degrees.

23. The method of claim 21 further comprising optically manipulating the scattered light about the third optical axis onto the image sensor array and the specularly reflected beam of light away from the image sensor array.

24. The method of claim 21 further comprising emitting multiple illumination beams of light along different illumination optical axes onto a common region on the target surface so that scattered light from each of the illumination beams of light about the third optical axis is received at the image sensor array and so that optical axes of specularly reflected beams of light due to the illumination beams of light circumscribe the third optical axis.

25. The method of claim 21 wherein the emitting of the illumination beam of light includes emitting the illumination beam of light along the first optical axis onto the target surface at the nonzero angle of incidence of approximately thirty-six degrees with respect to the normal to the target surface and wherein the receiving of the scattered light from the target surface includes receiving the scattered light from the target surface about the third optical axis at the image sensor array, where the third optical axis is offset by the predefined angle of approximately fourteen degrees from the second optical axis.