Generation of digital patterns for spatial light modulation

• US 6,958,841 B2
• Filed: 05/23/2002
• Issued: 10/25/2005
• Est. Priority Date: 05/23/2001
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Barlett, Terry A., Rancuret, Paul L., Koontz, Elisabeth Marley, Lee, Benjamin L.
• Primary Examiner(s): SPECTOR, DAVID N
• Application Number:
  US10/154,257
• Publication Number:
  US 20030001953A1
• Time in Patent Office: 1,251 Days
• Field of Search: 359/238, 359/290, 359/291, 359/292
• US Class Current: 359/239
• CPC Class Codes: H04N 5/7458 the modulator being an array of deformable mirrors, e.g. digital micromirror device [DMD]

Abstract

Disclosed is a method for generating patterns to be used in a spatial light modulator having a plurality of pixels. The method includes generating an optical pattern to be placed upon the pixels of the spatial light modulator, applying the optical pattern to the pixels of the spatial light modulator, measuring the optical performance of the plurality of pixels having the optical pattern applied to it, comparing the measured optical performance to a target optical performance, and adjusting the optical pattern applied to the plurality of pixels to form another optical pattern that more closely achieves the target optical performance.

Claims

1. A method for generating patterns to be used in a spatial light modulator having a plurality of pixels, the method comprising:

a) generating a pixel pattern to be placed upon the plurality of pixels of the spatial light modulator;

b) applying the pixel pattern to the pixels of the spatial light modulator;

c) measuring the optical performance of the plurality of pixels having the pixel pattern applied to it;

d) comparing the measured optical performance to a target optical performance; and

e) adjusting the pixel pattern applied to the plurality of pixels to form another optical pattern that more closely achieves the target optical performance.

2. The method of claim 1 wherein the generating of the pixel pattern further comprises:

a) generating a starting pixel pattern;

b) estimating the optical performance of the starting pixel pattern; and

c) adjusting the starting pixel pattern to approximate more closely the target optical performance.

3. The method of claim 2 wherein the estimating of the optical performance of the optical pattern comprises:

a) illuminating the plurality of pixels with an optical signal;

b) characterizing the individual optical responses of at least some of the plurality of pixels; and

c) calculating the estimated optical performance by a calculation based upon the individual optical responses of the at least some of the plurality of pixels.

4. The method of claim 2 wherein the estimating of the optical performance is accomplished by summing, for each pixel, that pixel'"'"'s off-state response and, for each “

on”

pixel, a contribution from that “

on”

pixel.

5. The method of claim 4 wherein the contribution from each “

on”

pixel is a delta phasor contribution, which is a phasor difference between each individual pixel'"'"'s on-state response and off-state response.

6. The method of claim 1 and further comprising repeating the measuring of the optical performance and the adjusting of the pixel pattern until the optical performance of the plurality of pixels is within a specified measure from the target optical performance.

7. The method of claim 6 wherein the repetitive adjustments to the pixel pattern causes the optical performance of the plurality of pixels to continually approach the target optical performance from one side of the target optical performance.

8. The method of claim 6 wherein the repetitive adjustments to the pixel pattern causes the optical performance of the plurality of pixels to continually approach the target optical performance, but from either side of the target optical performance.

9. The method of claim 1 wherein the adjusting of the pixel pattern is done according to a pixel sequence map.

10. The method of claim 9 wherein the pixel sequence map defines individual pixels to be turned on sequentially.

11. The method of claim 9 wherein the pixel sequence map defines pixels to be turned on in groups.

12. The method of claim 11 wherein the pixel sequence map contains priority pixels that are left “

on”

under normal operating conditions.

13. The method of claim 1 wherein the generated pixel pattern comprises a periodically repeating pixel pattern.

14. The method of claim 13 wherein the generated repeating pixel pattern is comprised of a tile of at least two pixels, and wherein the tile of pixels is repeated across the generated repeating pixel pattern.

15. The method of claim 14 wherein the adjusting of the generated repeating pixel pattern comprises changing the pixel pattern of the tile.

16. The method of claim 14 wherein the adjusting of the generated repeating pixel pattern comprises changing pixels within that pattern without applying that change across all tiles, whereby the resulting adjusted repeating pixel pattern is not completely periodic.

17. The method of claim 16 wherein the pixels within the generated repeating pixel pattern are adjusted according to a pixel sequence map.

18. The method of claim 16 wherein the pixel pattern of the tile is changed and wherein individual pixels of the starting periodic optical pattern are adjusted without applying the adjustment to all the tiles.

19. The method of claim 14 wherein the generating of the periodically repeating pattern further comprises:

a) generating a starting periodic pixel pattern;

b) estimating the optical performance of the starting periodic pixel pattern;

c) adjusting the starting periodic pixel pattern to approximate more closely the target optical performance.

20. The method of claim 19 wherein the starting periodic pixel pattern comprises a starting tile of at least two pixels, wherein the tile is repeated across the starting periodic pixel pattern.

21. The method of claim 20 wherein the adjusting of the starting periodic pixel pattern comprises changing the pixel pattern of the starting tile.

22. The method of claim 20 wherein the adjusting of the starting periodic pixel pattern comprises changing pixels within that pattern without repeating those changes across all tiles, whereby the resulting starting periodic optical pixel pattern is not completely periodic.

23. The method of claim 22 wherein the pixels within the starting periodic pixel pattern are adjusted according to a pixel sequence map.

24. The method of claim 23 wherein the pixel sequence map defines individual pixels to be turned on sequentially.

25. The method of claim 23 wherein the pixel sequence map defines pixels to be turned on in groups.

26. The method of claim 25 wherein the pixel sequence map contains priority pixels that are left “

on”

under normal operating conditions.

27. The method of claim 26 wherein at least some of the priority pixels are grouped in the center of the pattern of pixels, wherein the center priority pixels act as a circular aperture, and wherein the other pixels are manipulated according to the pixel sequence map to cause the plurality of pixels to act as a digital aperture.

28. The method of claim 20 wherein the pixel pattern of the starting tile is changed and wherein individual pixels of the starting periodic pixel pattern are adjusted without repeating the adjustment across all tiles.

29. The method of claim 28 wherein the pixels within the starting periodic pixel pattern are adjusted according to a pixel sequence map.

30. The method of claim 1 wherein the plurality of pixels is logically divided into at least two segments, wherein a single channel optical signal is spread across the at least two logical segments for processing.

31. The method of claim 1 wherein the plurality of pixels is logically divided into at least two segments, wherein at least three channels of an optical signal are distributed across the at least three logical segments for processing.

32. The method of claim 1 wherein the adjusting of the pixel pattern to achieve more closely the target optical performance, includes turning on or off individual pixels within the pixel pattern based on the phasor effects of those individual pixels'"'"' optical responses.

33. The method of claim 32 wherein the turning on or off of individual pixels within the pixel pattern is effective to compensate for phasor-based irregularities in an incoming optical signal.

34. The method of claim 33 wherein the phasor-based irregularity is a non-planar incoming optical signal phase front.

35. A method for generating patterns to be used in a spatial light modulator having a plurality of pixels, the method comprising:

a) generating a pixel pattern to be placed upon the plurality of pixels of the spatial light modulator, the pixel pattern comprising a periodically repeating pattern and non-periodic variations from the periodically repeating pattern;

b) applying the pixel pattern to the pixels of the spatial light modulator;

c) measuring the optical performance of the plurality of pixels having the pixel pattern applied to it;

d) comparing the measured optical performance to a target optical performance; and

e) adjusting the pixel pattern applied to the plurality of pixels to form another optical pattern that more closely achieves the target optical performance.

36. The method of claim 35 wherein the periodically repeating pattern is confined within a certain area of the pixel pattern.

37. The method of claim 35 wherein the variations from the periodically repeating pattern are interspersed within the periodically repeating pattern.

38. The method of claim 35 wherein the variations from the periodically repeating pattern are outside the periodically repeating pattern.

39. An optical signal processing system comprising:

a) a spatial light modulator operable to perform optical signal processing on an incoming light signal;

b) a look-up table operable to store a plurality of pixel patterns to be applied to the spatial light modulator to achieve certain desired optical performance characteristics by the spatial light modulator processing the incoming light signal; and

c) a processor in electrical communication with the look-up table and the spatial light modulator, the processor operable to generate and apply a pixel pattern to the spatial light modulator, to measure the optical performance of the pixel pattern, to compare the measured optical performance to a target optical performance, and to adjust the pixel pattern to more closely achieve the target optical performance.