Stereo projection apparatus using polarized solid state light sources

• US 7,871,165 B2
• Filed: 11/30/2007
• Issued: 01/18/2011
• Est. Priority Date: 11/30/2007
• Status: Expired due to Fees

• Current Assignee: IMAX Theatres International Limited (IMAX Corporation)
• Original Assignee: Eastman Kodak Company
• Inventors: Corey, Richard P., Silverstein, Barry D.
• Primary Examiner(s): Epps; Georgia Y
• Assistant Examiner(s): Reilly-Diakun; Jori S
• Application Number:
  US11/948,048
• Publication Number:
  US 20090141242A1
• Time in Patent Office: 1,145 Days
• Field of Search: 353 7- 8, 353/20, 353/31, 353/81, 353/122, 353/85, 359/458, 359/462, 359464-467, 348/42, 348/51, 348 54- 55, 348 57- 58, 348/60
• US Class Current: 353/7
• 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 system for viewing stereoscopic images, comprising:

polarized glasses worn by a viewer for viewing stereoscopic images formed on a display surface, wherein a polarized filter for a first eye transmits polarized light that is orthogonal to polarized light transmitted by a polarized filter for a second eye; and

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; and

a polarization beamsplitter disposed to direct light of both the first and second polarizations 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 single MEMS spatial light modulator for alternately modulating the light beams of the first and second polarizations on the common illumination axis; and

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

2. The stereoscopic digital image projector of claim 1 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 and produce light in a different wavelength band than the first and second polarized light sources; and

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

a second MEMS spatial light modulator for alternately modulating the light beams of the third and fourth polarizations on the second common illumination axis;

wherein the projection optics direct the light from the first and second illumination systems onto the display surface to provide a color image having at least two spectral bands.

3. The projection apparatus of claim 1 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 reflective metal structure.

4. The projection apparatus of claim 1 wherein the MEMS spatial light modulator comprises a reflective metallic structure, and where the plane polarized light vibrates in the plane of incidence of the reflective metal structure.

5. A color projection apparatus comprising:

a) 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; and

a first 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 half wave plate 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; and

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

v) a single spatial light modulator for alternately modulating the light beams of the first and second polarizations disposed to accept the illumination on the common illumination axis and to provide a modulated light output;

b) 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

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

6. The color projection apparatus of claim 5 further comprising a light guide disposed to guide light from the common illumination axis toward the spatial light modulator.

7. The color projection apparatus of claim 6 wherein the waveguide element substantially matches the proportions of the spatial light modulator.

8. The color projection apparatus of claim 6 wherein the waveguide element substantially is one half the proportions of the spatial light modulator.

9. The color projection apparatus of claim 6 wherein the waveguide element substantially maintains the polarization properties of the input illumination light.

10. The color projection apparatus of claim 5 wherein the spatial light modulator is a digital micromirror device.