STEREO PROJECTION USING POLARIZED SOLID STATE LIGHT SOURCES

• US 20090213330A1
• Filed: 02/25/2008
• Published: 08/27/2009
• Est. Priority Date: 02/25/2008
• Status: Active Grant

• Current Assignee: IMAX Theatres International Limited (IMAX Corporation)
• Original Assignee: Eastman Kodak Company
• Inventors: Kircher, James R., Metzger, Robert, Bietry, Joseph R., Silverstein, Barry D.
• Granted Patent: US 7,891,816 B2
• Time in Patent Office: Days
• US Class Current: 353/8
• CPC Class Codes: H04N 13/341 using temporal multiplexing
• CPC Class Codes: H04N 13/363 using image projection screens volumetric display H04N13/388
• CPC Class Codes: H04N 13/398 Synchronisation thereof; Control thereof

Abstract

A stereoscopic digital image projector includes (a) a plurality of light modulation assemblies, each comprising: (i) at least one solid-state light source energizable to provide illumination having a first polarization axis; (ii) a polarization rotator disposed in the path of the polarized illumination from the solid-state light source(s) and actuable to controllably rotate the polarization axis from the solid-state light source(s) to a second polarized axis; (iii) a micro-electromechanical spatial light modulator in the path of the polarized illumination and energizable to modulate the polarized illumination to form a first modulated light from illumination of the first polarization state and to form a second modulated light from illumination of the second polarization state; and (b) a synchronizing means to temporally control the polarization rotation to match the appropriate image data on the spatial light modulator; and (c) projection optics for directing the first and second modulated light toward a display surface.

Claims

1. A stereoscopic digital image projector comprising:

a) a plurality of light modulation assemblies, each comprising;

at least one solid-state light source energizable to provide illumination having a first polarization axis;

a polarization rotator disposed in the path of the polarized illumination from the solid-state light source(s) and actuable to controllably rotate the polarization axis from the solid-state light source(s) to a second polarized axis; and

a micro-electromechanical spatial light modulator in the path of the polarized illumination and energizable to modulate the polarized illumination to form a first modulated light from illumination of the first polarization state and to form a second modulated light from illumination of the second polarization state;

b) a synchronizing means to temporally control the polarization rotation to match the appropriate image data on the spatial light modulator; and

c) projection optics for directing the first and second modulated light toward a display surface.

2. The projector of claim 1 wherein two adjacent spectral band solid-state light sources of orthogonal radiation are combined using a polarization beamsplitter and the polarization axis from one of the two adjacent spectral bands is subsequently rotated to match the polarization axis of the other by a color selective retardation means.

3. The projector of claim 1 wherein the spatial light modulator is a micro-mirror device.

4. The projector of claim 1 wherein the polarization rotator is a liquid crystal device.

5. The projector of claim 1 wherein the first solid-state light source comprises an array of lasers.

6. A stereoscopic digital image projector comprising:

a) a plurality of light modulation assemblies, each comprising;

a first solid-state light source energizable to provide illumination having a first polarization axis;

a second solid-state light source energizable to provide illumination having a second polarization axis orthogonal to the first polarization axis;

a rotating element disposed in the path of the polarized illumination from both first and second solid-state light sources and actuable to controllably and alternatively direct the light from the first and second solid-state light sources along an optical axis as two temporally alternating orthogonal polarized states of illumination; and

a micro-electromechanical spatial light modulator in the path of the polarized illumination and energizable to modulate the polarized illumination to form a first modulated light from illumination of the first polarization axis and to form a second modulated light from illumination of the second polarization axis;

b) a synchronizing means to temporally control the polarization rotation to match the appropriate image data on the spatial light modulator; and

c) projection optics for directing the first and second modulated light toward a display surface.

7. The projector of claim 6 wherein the first solid-state light source comprises an array of lasers.

8. The projector of claim 6 wherein the spatial light modulator is a micro-mirror device.

9. The projector of claim 6 wherein the rotating element is a segmented disk with at least one reflective and one transmissive segment.

10. The projector of claim 6 wherein the rotating element is imparted with properties that reduce laser speckle.

11. A stereoscopic digital image projector comprising:

a) a plurality of light modulation assemblies, each comprising;

a first solid-state light source energizable to provide illumination having a first polarization axis;

a second solid-state light source energizable to provide illumination having a second polarization axis orthogonal to the first polarization axis;

a rotating element disposed in the path of the polarized illumination from both first and second solid-state light sources to alternately deliver polarized light from one solid state light source to the illumination section

a retardation means to rotate the other orthogonally polarized solid-state light source such that its polarization state is matched to the polarization state delivered to the illumination section;

a redirecting means for delivering this newly matched polarized light to combine at the illumination section;

an optical integration means for mixing the light of the two solid state light sources without depolarization; and

a micro-electromechanical spatial light modulator in the path of the polarized illumination and energizable to modulate the polarized illumination to form a first modulated light from illumination of the first polarization axis and to form a second modulated light from illumination of the second polarization axis;

b) a synchronizing means to temporally control the polarization rotation to match the appropriate image data on the spatial light modulator; and

c) projection optics for directing the first and second modulated light toward a display surface.

12. The projector of claim 11 wherein the rotating element is a segmented disk with at least one reflective and one transmissive segment.

13. The projector of claim 11 wherein the optical integration means comprises of lenslet arrays.

14. The projector of claim 11 wherein the rotating element is imparted with properties that reduce laser speckle.

15. The projector of claim 11 wherein the first solid-state light source comprises an array of lasers.

16. A stereoscopic digital image projector comprising:

a) a plurality of light modulation assemblies, each comprising;

a first solid-state light source energizable to provide illumination having a first polarization axis;

a second solid-state light source energizable to provide illumination having a second polarization axis orthogonal to the first polarization axis;

an alternating polarization conversion means to alternately rotate the first or second solid-state light source to the matching polarization state of the other source;

a delivery means for delivering single polarization state light combined from both solid-state light sources as a single illumination source a preferred orientation to minimize polarization change on a spatial light modulator; and

a spatial light modulator in the path of the polarized illumination and energizable to modulate the polarized illumination to form a first modulated light from illumination of the first polarization axis and to form a second modulated light from illumination of the second polarization axis;

b) a synchronizing means to temporally control the polarization rotation to match the appropriate image data on the spatial light modulator; and

c) projection optics for directing the first and second modulated light toward a display surface.

17. The projector of claim 16 wherein the polarization conversion means is comprised of a segmented rotating disk with at least one reflective and one transmissive segment and a half wave retarder in either the reflective or transmissive paths.

18. The projector of claim 16 wherein the beam delivery path comprises at least one lenslet array.

19. The projector of claim 16 wherein the rotating element is imparted with properties that reduce laser speckle.

20. The projector of claim 16 wherein light combined in the delivery means by a choice of one of the following methods:

spatial overlap, angular overlap, or a combination of spatial and angular overlaps.

21. A stereoscopic digital image projector comprising:

a) a plurality of light modulation assemblies, each comprising;

at least one solid-state light source energizable to provide illumination having a first polarization axis;

at least one narrow band polarization rotator disposed in the path of the polarized illumination from the solid-state light source(s) and to controllably rotate the polarization axis from the solid-state light source(s) to a second polarized axis in sequence with image data provided to each modulator; and

a spatial light modulator in the path of the polarized illumination and energizable to modulate the polarized illumination to form a first modulated light from illumination of the first polarization axis and to form a second modulated light from illumination of the second polarization axis; and

b) projection optics for directing the first and second modulated light toward a display surface.

22. The projector of claim 21 wherein two adjacent spectral band solid-state light sources of orthogonal radiation are combined using a polarization beamsplitter and the polarization axis from one of the two adjacent spectral bands is subsequently rotated to match the polarization axis of the other by a color selective retardation means.

23. The projector of claim 21 wherein the spatial light modulator is a micro-mirror device.

24. The projector of claim 21 wherein the polarization rotator is a liquid crystal device.

25. The projector of claim 21 wherein the first solid-state light source comprises an array of lasers.