Image projector with flexible reflective analog modulator

• US 20060291269A1
• Filed: 05/12/2006
• Published: 12/28/2006
• Est. Priority Date: 05/13/2005
• Status: Active Grant

• Current Assignee: Her Majesty The Queen In Right of Canada As Represented By The Minister of National Defence, Institut national d'optique
• Original Assignee: Her Majesty The Queen In Right of Canada As Represented By The Minister of National Defence, Institut national d'optique
• Inventors: Doucet, Michel, Savard, Maxime, Niall, Keith, Picard, Francis
• Granted Patent: US 7,835,056 B2
• Time in Patent Office: Days
• US Class Current: 365/145
• CPC Class Codes: G03B 21/005 Projectors using an electronic spatial light modulator but not peculiar thereto
• CPC Class Codes: G03B 21/008 using micromirror devices
• CPC Class Codes: G03B 21/14 Details
• CPC Class Codes: G03B 21/208 Homogenising, shaping of the illumination light
• CPC Class Codes: H04N 9/3129 scanning a light beam on the display screen scanning a light beam on a screen in displays other than projection devices G09G3/02; scanning systems in general G02B26/10; projectors using laser light sources in general H04N9/3161

Abstract

An image projector comprises a plurality of flexible reflective analog modulators (FRAMs), an illumination optics for focusing at least one light source thereon, a conversion optics for converting the variations in divergence of the beams reflected therefrom into variations in intensity, and a scanning mechanism coupled to a projection optics for displaying an image, constructed of intensity modulated light dots or pixels, on a screen. FRAM curvatures, responsible for determining the divergence of the reflected beams, and ultimately the intensity of each pixel, are varied by an actuation voltage that can be modulated using waveforms that minimize the FRAM response times. For multicolour images, three laser light sources operating at different wavelengths are used in conjunction with three linear FRAM arrays.

Claims

1. An optical apparatus comprising at least one light source generating at least one input beam, at least one Flexible Reflective Analog Modulator (FRAM), said FRAM generally comprising a flexible reflective member attached to a substrate by at least one leg extending outwardly therefrom, an electrode on said substrate and an electrode on said flexible reflective member thus forming a set of electrodes for applying an actuation voltage thereon, the optical apparatus further comprising an illumination optics comprising at least one lens, said lens focusing said input beam to produce at least one focused beam, said focused beam comprising a beam waist, said FRAM having a FRAM position either in front of, behind or at said beam waist and a FRAM orientation such that said focused beam is divergently reflected by said flexible reflective member of said FRAM to produce at least one reflected beam therefrom.

2. The optical apparatus as claimed in claim 1, wherein said light source comprises a laser.

3. The optical apparatus as claimed in claim 1, wherein said FRAM has a FRAM position in front of said beam waist.

4. The optical apparatus as claimed in claim 1, wherein said FRAM has a FRAM position behind said beam waist.

5. The optical apparatus as claimed in claim 1, wherein said FRAM has a FRAM position at said beam waist.

6. The optical apparatus as claimed in claim 1, wherein said FRAM, having a flexible reflective member, includes a natural FRAM curvature in the absence of an applied actuation voltage defined by a natural curvature of said flexible reflective member.

7. The optical apparatus as claimed in claim 6, wherein said FRAM has a variable FRAM curvature adjusted about said natural FRAM curvature by a range of actuation voltages applied thereon.

8. The optical apparatus as claimed in claim 7, wherein said reflected beam from said FRAM has a variable reflected beam divergence which depends on said variable FRAM curvature thereof, and thus on said range of actuation voltages applied thereon.

9. The optical apparatus as claimed in claim 8, wherein said range of actuation voltages can be determined and applied to each said FRAM individually, each said FRAM thus operating independently.

10. A light intensity modulator comprising:

an optical apparatus for variably modifying a divergence of at least one reflected beam comprising at least one light source generating at least one input beam, at least one Flexible Reflective Analog Modulator (FRAM), said FRAM generally comprising a flexible reflective member attached to a substrate by at least one leg extending outwardly therefrom, an electrode on said substrate and an electrode on said flexible reflective member thus forming a set of electrodes for applying an actuation voltage thereon, said FRAM having a natural FRAM curvature in the absence of an actuation voltage applied thereon defined by a natural curvature of said flexible reflective member, and a variable FRAM curvature adjusted by a range of actuation voltages applied thereon, said optical apparatus further comprising an illumination optics comprising at least one lens, said lens focusing said input beam to produce at least one focused beam, said focused beam comprising a beam waist, said FRAM having a FRAM position either in front of, behind or at said beam waist and a FRAM orientation such that said focused beam is reflected by said flexible reflective member of said FRAM to produce at least one reflected beam therefrom, said reflected beam reflected by said FRAM having a variable reflected beam divergence dependent on the FRAM position and the variable FRAM curvature of said FRAM, and thus on the range of actuation voltages applied thereon;

a conversion optics for converting the variable reflected beam divergence of said reflected beam into a variable reflected beam intensity.

11. The light intensity modulator as claimed in claim 10, wherein said light source comprises a laser.

12. The light intensity modulator as claimed in claim 10, wherein said FRAM has a FRAM position in front of said beam waist.

13. The light intensity modulator as claimed in claim 10, wherein said FRAM has a FRAM position behind said beam waist.

14. The light intensity modulator as claimed in claim 10, wherein said FRAM has a FRAM position at said beam waist.

15. The light intensity modulator as claimed in claim 10, wherein said range of actuation voltages can be determined and applied to each said FRAM individually, each said FRAM thus being an independently operated FRAM.

16. The light intensity modulator as claimed in claim 10, wherein said conversion optics comprises either Cassegrain optics, Schlieren optics, mask arrangements combined with optics, or any combination thereof.

17. The light intensity modulator as claimed in claim 10, comprising an electronic driver performing all FRAM driving functions required for the proper operation of said FRAM.

18. The light intensity modulator as claimed in claim 17, wherein said FRAM driving functions comprise light modulation data processing.

19. The light intensity modulator as claimed in claim 17, wherein said FRAM driving functions comprise digital-to-analog data conversion.

20. The light intensity modulator as claimed in claim 17, wherein said FRAM driving functions comprise actuation voltage amplification.

21. The light intensity modulator as claimed, in claim 17, wherein said FRAM driving functions comprise coarse and fine offset generation.

22. The light intensity modulator as claimed in claim 17, wherein said range of actuation voltages are applied using at least one actuation voltage waveform constructed to minimize the response time of said FRAM.

23. The light intensity modulator as claimed in claim 22, wherein said actuation voltage waveform comprises either an exponentially varying voltage waveform, a decreasing or increasing electrostatic pressure ramp waveform, a two-step function actuation waveform, an accelerated two-step actuation waveform, a filtered step function waveform, or any combination thereof.

24. The light intensity modulator as claimed in claim 22, wherein said FRAM driving functions comprise actuation voltage waveform shaping.

25. The light intensity modulator as claimed in claim 10, comprising a plurality of FRAMs organized in at least one FRAM array, said FRAM array comprising at least two FRAMs.

26. The light intensity modulator as claimed in claim 25, wherein said FRAM array comprises at least one linear FRAM array.

27. The light intensity modulator as claimed in claim 26, wherein said illumination optics is configured to address said linear FRAM array.

28. The light intensity modulator as claimed in claim 27, wherein said illumination optics comprise either a microlens array, a diffraction grating, an optics for generating a focused beam comprising cylindrical wavefronts, or any combination thereof.

29. The light intensity modulator as claimed in claim 27, wherein said range of actuation voltages can be determined and applied to each said FRAM individually, each said FRAM thus being an independently operated FRAM.

30. The light intensity modulator as claimed in claim 29, wherein each linear FRAM array of independently operated FRAMs produces at least one line of variable intensity light dots.

31. An image projector comprising:

an optical apparatus for variably modifying the divergence of at least one reflected beam comprising at least one light source generating at least one input beam, a plurality of independently operated Flexible Reflective Analog Modulators (FRAMs) organized in at least one linear FRAM array, said linear FRAM array comprising at least one FRAM, each said FRAM generally comprising a flexible reflective member attached to a flat substrate by at least one leg extending outwardly therefrom, an electrode on said substrate and an electrode on said flexible reflective member thus forming a set of electrodes for applying an actuation voltage thereon, each said FRAM having a natural FRAM curvature in the absence of an actuation voltage applied thereon defined by a natural curvature of said respective flexible reflective member and a variable FRAM curvature adjusted by a range of actuation voltages applied thereon, said optical apparatus further comprising an illumination optics configured to address said linear FRAM array, said illumination optics focusing said input beam to produce at least one focused beam, said focused beam comprising a beam waist, said FRAM array having a FRAM array position either in front of, behind or at said beam waist and a FRAM array orientation such that said focused beam is reflected by said flexible reflective members of said FRAMs of said FRAM array to produce a plurality of reflected beams therefrom, each said reflected beam reflected by a respective FRAM of said FRAM array having a variable reflected beam divergence dependent on the respective FRAM position and the variable FRAM curvature of said respective FRAM, and thus on the range of actuation voltages applied thereon;

a conversion optics for converting the variable reflected beam divergence of each said reflected beam into a variable reflected beam intensity, said linear FRAM array of independently operated FRAMs thus producing at least one line of variable intensity light dots;

a scanning mechanism coupled to a projection optics, said scanning mechanism scanning through said at least one line of variable intensity light dots in a scanning direction perpendicular thereto, thus projecting, in conjunction with said projection optics, a bidimensional image.

32. The image projector as claimed in claim 31, wherein said light source comprises a laser.

33. The image projector as claimed in claim 31, wherein each said FRAM has a FRAM position in front of said beam waist.

34. The image projector as claimed in claim 31, wherein each said FRAM has a FRAM position behind said beam waist.

35. The image projector as claimed in claim 31, wherein each said FRAM has a FRAM position at said beam waist.

36. The image projector as claimed in claim 31, wherein said illumination optics comprises either a microlens array, a diffraction grating, an optics for generating a focused beam comprising cylindrical wavefronts, or any combination thereof.

37. The image projector as claimed in claim 31, wherein said conversion optics comprises either Cassegrain optics, Schlieren optics, mask arrangements combined with optics, or any combination thereof.

38. The image projector as claimed in claim 31, comprising an electronic driver performing all FRAM driving functions required for the proper operation of said FRAMs.

39. The image projector as claimed in claim 38, wherein said FRAM driving functions comprise light modulation data processing.

40. The image projector as claimed in claim 38, wherein said FRAM driving functions comprise digital-to-analog data conversion.

41. The image projector as claimed in claim 38, wherein said FRAM driving functions comprise actuation voltage amplification.

42. The image projector as claimed in claim 38, wherein said FRAM driving functions comprise coarse and fine offset generation.

43. The image projector as claimed in claim 38, wherein said range of voltages is applied using at least one actuation voltage waveform constructed to minimize the response time of said FRAMs.

44. The image projector as claimed in claim 43, wherein said actuation voltage waveform comprises either an exponentially varying voltage waveform, a decreasing or increasing electrostatic pressure ramp waveform, a two-step function actuation waveform, an accelerated two-step actuation waveform, a filtered step function waveform, or any combination thereof.

45. The image projector as claimed in claim 43, wherein said FRAM driving functions also comprise actuation voltage waveform shaping.

46. The image projector as claimed in claim 31, wherein said at least one light source comprises at least two laser light sources, said laser light sources operating at different wavelengths, each said laser light source illuminating a respective said linear FRAM array, each said respective linear FRAM array generating a respective line of said variable intensity light dots, said lines of variable intensity light dots being combined to form a multicoloured line of variable intensity light dots to be directed toward said scanning mechanism and said projection optics to produce a bidimensional multicolour image.

47. The image projector as claimed in claim 46, wherein said wavelengths represent additive colours.

48. The image projector as claimed in claim 47, wherein said additive colours comprise red, green and blue.