STEREO PROJECTION APPARATUS USING POLARIZED SOLID STATE LIGHT SOURCES

• US 20090141242A1
• Filed: 11/30/2007
• Published: 06/04/2009
• Est. Priority Date: 11/30/2007
• Status: Active Grant

• Current Assignee: IMAX Corporation
• Original Assignee: Eastman Kodak Company
• Inventors: Corey, Richard P., Silverstein, Barry D.
• Granted Patent: US 7,871,165 B2
• Time in Patent Office: Days
• US Class Current: 353/20
• CPC Class Codes: G02B 27/0905 Dividing and/or superposing multiple light beams
• CPC Class Codes: G02B 27/14 operating by reflection only
• CPC Class Codes: G02B 30/25 using polarisation techniques
• CPC Class Codes: G03B 21/2013 Plural light sources
• CPC Class Codes: G03B 21/2073 Polarisers in the lamp house peculiar to electronic spatial light modulators H04N9/3197
• CPC Class Codes: G03B 21/208 Homogenising, shaping of the illumination light
• CPC Class Codes: G03B 35/26 using polarised or coloured light separating different viewpoint images
• CPC Class Codes: H04N 13/337 using polarisation multiplexing
• 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 13/365 using digital micromirror devices [DMD]

Abstract

A digital image projector includes a first polarized light source; a second polarized light source that is orthogonal in polarization state to the first polarized light source; a polarization beamsplitter disposed to direct light of either the first or second polarization along a common illumination axis; a MEMS spatial light modulator; and projection optics for delivering imaging light from the MEMS spatial light modulator.

Claims

1. A digital image projector comprising:

a first polarized light source;

a second polarized light source that is orthogonal in polarization state to the first polarized light source;

a polarization beamsplitter disposed to direct light of either the first or second polarization along a common illumination axis;

a MEMS spatial light modulator; and

projection optics for delivering imaging light from the MEMS spatial light modulator.

2. The digital image projector of claim 1 wherein the first or second polarized light sources are vertical-cavity devices.

3. The projection apparatus of claim 1 wherein the spatial light modulator is a digital micromirror device.

4. The projection apparatus of claim 1 wherein the projection optics deliver imaging light to provide a color image.

5. The projection apparatus of claim 1 wherein the MEMS spatial light modulator comprises an array of micromirrors, each micromirror having an axis of rotation, and wherein the polarization axis of polarized light incident on at least one of the micromirrors is substantially orthogonal to or parallel to the axis of rotation of the micromirror.

6. A stereoscopic digital image projector comprising:

an illumination system comprising;

first and second polarized light sources, wherein the first and second polarized light sources have orthogonally disposed polarization axes;

a polarization beamsplitter disposed to direct light of either the first or second polarization along a common illumination axis;

a controller system that alternately energizes the first and second polarized light sources to provide illumination of one polarization at a time;

a MEMS spatial light modulator;

projection optics in the path of modulated light from the MEMS spatial light modulator and directing the light onto a display surface; and

filter glasses for selectively viewing the stereoscopic image formed on the display surface.

7. The stereoscopic digital image projector of claim 6 wherein the illumination system is a first illumination system, wherein the polarization beamsplitter is a first polarization beamsplitter, wherein the common illumination axis is a first common illumination axis, wherein the MEMS spatial light modulator is a first MEMS spatial light modulator, and wherein the stereoscopic digital image projector further comprises:

at least a second illumination system comprising;

third and fourth polarized light sources, wherein the third and fourth polarized light sources have orthogonally disposed polarization axes;

a second polarization beamsplitter disposed to direct light of either the third or fourth polarization along a second common illumination axis; and

a second MEMS spatial light modulator; and

wherein the projection optics provide a color image.

8. The projection apparatus of claim 6 wherein the MEMS spatial light modulator comprises a reflective metallic structure, and wherein the polarization plane of the linearly polarized light incident on the metallic structure is substantially normal to the plane of the reflector.

9. The projection apparatus of claim 6 wherein the MEMS spatial light modulator comprises a reflective structure, and where the plane polarized light vibrates in the plane of incidence or perpendicular of said reflective structure.

10. An illumination apparatus for a digital image projector, the illumination apparatus comprising:

a) a first polarized light source comprising

(i) two or more solid state laser arrays providing light of a first polarization in a first emission direction,

wherein each laser comprises a plurality of lasers extended in a first length direction; and

(ii) a first light redirecting prism comprising;

a first incident surface disposed to receive light incident in said first emission direction;

a first redirection surface having a plurality of light-redirecting facets, each light redirecting facet extended in the length direction and oriented at an oblique angle relative to the first emission direction, wherein the oblique angle orientation provides a reflection surface to incident light;

an output surface for providing redirected light of the first polarization from the light-redirecting facets;

b) a second polarized light source comprising

(i) two or more solid state laser arrays disposed to provide light of the first polarization in a second emission direction,

wherein each laser array comprises a plurality of lasers extended in a second length direction;

(ii) a polarizer for conditioning the light from the second polarized light source to provide light of a second polarization that is orthogonal to the first polarization; and

(iii) a second light redirecting prism comprising;

a second incident surface disposed to receive light incident in said second emission direction;

a second redirection surface having a plurality of light-redirecting facets, each light redirecting facet extended in the second length direction and oriented at an oblique angle relative to the second emission direction, wherein the oblique angle orientation provides a reflection surface to incident light;

an output surface for providing redirected light of the second polarization from the light-redirecting facets; and

c) a polarization beamsplitter disposed to direct light of either the first or second polarization along a common illumination axis.

11. The illumination apparatus of claim 10 further comprising a light guide disposed to accept light directed along the illumination axis.

12. The illumination apparatus of claim 10 wherein the first polarized light source further comprises two or more additional solid state laser arrays extended in the first length direction and disposed to provide light of the first polarization in a third emission direction that is substantially opposed to the first emission direction, wherein the first light redirecting prism further comprises a third incident surface disposed to receive light incident in said third emission direction.

13. A color projection apparatus comprising:

two or more light modulation assemblies for a digital image projector, each light modulation assembly providing light of a predetermined wavelength band and comprising;

(i) a first polarized light source comprising two or more solid state laser arrays disposed to provide light of a first polarization in a first emission direction,

wherein each laser array comprises a plurality of lasers extended in a first length direction; and

a first light redirecting prism comprising;

a first incident surface disposed to receive light incident in said first emission direction;

a first redirection surface having a plurality of light-redirecting facets, each light redirecting facet extended in the length direction and oriented at an oblique angle relative to the first emission direction, wherein the oblique angle orientation provides a reflection surface to incident light;

an output surface for providing redirected light of the first polarization from the light-redirecting facets;

(ii) a second polarized light source comprising two or more solid state laser arrays disposed to provide light of the first polarization in a second emission direction,

wherein each laser array comprises a plurality of lasers extended in a second length direction;

a polarizer for conditioning the light from the second polarized light source to provide light of a second polarization that is orthogonal to the first polarization; and

a second light redirecting prism comprising;

a second incident surface disposed to receive light incident in said second emission direction;

a second redirection surface having a plurality of light-redirecting facets, each light redirecting facet extended in the second length direction and oriented at an oblique angle relative to the second emission direction, wherein the oblique angle orientation provides a reflection surface to incident light;

an output surface for providing redirected light of the second polarization from the light-redirecting facets;

(iii) a polarization beamsplitter disposed to direct light of either the first or second polarization as illumination along a common illumination axis;

(iv) a spatial light modulator disposed to accept the illumination and to provide a modulated light output;

a color combiner disposed to accept the modulated light output from each of the two or more light modulation assemblies and to direct the modulated light onto an output axis; and

a projection lens disposed to direct the modulated light toward a display surface.

14. The color projection apparatus of claim 13 further comprising a light guide disposed to guide light from the common illumination axis toward the spatial light modulator.

15. The color projection apparatus of claim 13 wherein the waveguide element substantially matches the proportions of the spatial light modulator.

16. The color projection apparatus of claim 13 wherein the waveguide element substantially is one half the proportions of the spatial light modulator.

17. The color projection apparatus of claim 13 wherein the waveguide element substantially maintains the polarization properties of the input illumination light.

18. The color projection apparatus of claim 13 wherein the spatial light modulator is a digital micromirror device.