Color illumination system for spatial light modulators using multiple double telecentric relays

• US 20040047045A1
• Filed: 09/09/2002
• Published: 03/11/2004
• Est. Priority Date: 09/09/2002
• Status: Active Grant

• Current Assignee: Eastman Kodak Company
• Original Assignee: Eastman Kodak Company
• Inventors: Cobb, Joshua M.
• Granted Patent: US 6,809,873 B2
• Time in Patent Office: Days
• US Class Current: 359/634
• CPC Class Codes: G02B 27/1033 having a single light modulator for all colour channels
• CPC Class Codes: G02B 27/126 The splitting element being a prism or prismatic array, including systems based on total internal reflection
• CPC Class Codes: G02B 27/145 having sequential partially reflecting surfaces
• CPC Class Codes: G02B 27/149 using crossed beamsplitting surfaces, e.g. cross-dichroic cubes or X-cubes
• CPC Class Codes: H04N 9/3105 for displaying all colours simultaneously, e.g. by using two or more electronic spatial light modulators simultaneous projection in colour photography G03B33/10; beam splitting or combining systems per se G02B27/10
• CPC Class Codes: H04N 9/315 Modulator illumination systems general applications of lighting devices F21V; general optical systems G02B; lamp houses for projectors not peculiar to the presence of an electronic spatial light modulator G03B21/20

Abstract

A digital projection apparatus (10) for projection of a multicolor image uniformizes polychromatic light from a light source (12) and provides magnification to the uniformized illumination beam using a base condenser relay (80), providing a reduced numerical aperture for conditioning at a dichroic separator (27). For each monochromatic component color provided from the dichroic separator (27), a reducing relay (82) then demagnifies the illumination beam to provide source illumination to a spatial light modulator (30) at an increased numerical aperture. As a result, color shading across the field is minimized and brightness is optimized.

Claims

1. A projection apparatus for projecting a multicolor image onto a display surface, the apparatus comprising:

(a) a polychromatic light source;

(b) uniformizing means for homogenizing light from said polychromatic light source to provide a uniform illumination field;

(c) a base condenser relay lens for magnifying said uniform illumination field to form a magnified uniform illumination field and for directing said magnified uniform illumination field toward a dichroic separator, said dichroic separator providing colored light for a first, second, and third colored light channel;

(d) a first reducing relay lens for imaging and directing said colored light in said first colored light channel towards a first spatial light modulator for forming a first modulated light beam;

(e) a second reducing relay lens for imaging and directing said colored light in said second colored light channel towards a second spatial light modulator for forming a second modulated light beam;

(f) a third reducing relay lens for imaging and directing said colored light in said third colored light channel towards a third spatial light modulator for forming a third modulated light beam;

(g) a color combiner for combining said first, second, and third modulated light beams to form a multicolor modulated light beam; and

(h) a projection lens for projecting said multicolor modulated light beam onto the display surface.

2. A projection apparatus according to claim 1 wherein said colored light in said first colored light channel is red, said colored light in said second colored light channel is green, and said colored light in said third colored light channel is blue.

3. A projection apparatus according to claim 1 wherein said first spatial light modulator is a reflective LCD.

4. A projection apparatus according to claim 1 wherein said first spatial light modulator is a transmissive LCD.

5. A projection apparatus according to claim 1 wherein said first spatial light modulator is a digital micromirror device.

6. A projection apparatus according to claim 1 wherein said polychromatic light source comprises a lamp.

7. A projection apparatus according to claim 1 further comprising a polarizer for conditioning the light from said polychromatic light source.

8. A projection apparatus according to claim 1 further comprising a polarizer for conditioning the colored light in said first colored light channel.

9. A projection apparatus according to claim 1 wherein said base condenser relay lens is double-telecentric.

10. A projection apparatus according to claim 1 wherein said first reducing relay lens is double-telecentric.

11. A projection apparatus according to claim 1 wherein said first colored light channel further comprises a polarizing beamsplitter for directing said colored light in said first colored light channel to said first spatial light modulator.

12. A projection apparatus according to claim 11 wherein said polarizing beamsplitter is a wire-grid polarizing beamsplitter.

13. A projection apparatus according to claim 1 wherein said color combiner is an X-cube.

14. A projection apparatus according to claim 1 wherein said color combiner is a Philips prism.

15. A projection apparatus for projecting a color image onto a display surface, the apparatus comprising:

(a) a polychromatic light source;

(b) uniformizing means for homogenizing light from said polychromatic light source to provide a uniform illumination field;

(c) a base condenser relay lens for magnifying said uniform illumination field to form a magnified uniform illumination field;

(d) color splitting means for splitting said magnified uniform illumination field into a first color channel for forming a magnified first color illumination field and into at least a second single-color channel for forming a magnified second color illumination field;

(e) a first reducing relay lens for forming a reduced first color illumination field from said magnified first color illumination field and for directing said reduced first color illumination field towards a first spatial light modulator for forming a first modulated light beam; and

(f) color combining means for directing said first modulated light beam toward a projection lens for projection toward the display surface.

16. A projection apparatus for projecting a color image according to claim 15 further comprising:

(g) a second reducing relay lens for forming a reduced second color illumination field from said magnified second color illumination field and for directing said reduced second color illumination field towards a second spatial light modulator for forming a second modulated light beam, said second modulated light beam directed to said color combining means.

17. A method for projecting a multicolor image toward a display surface, the method comprising:

(a) providing a uniform illumination field of polychromatic light as an internal image;

(b) magnifying said internal image towards a dichroic color separator to obtain, as images of said internal image, a first enlarged color internal image, a second enlarged color internal image, and a third enlarged color internal image;

(c) demagnifying said first enlarged color internal image to form a first reduced color internal image for modulation at a first spatial light modulator to provide a first color modulated image;

(d) demagnifying said second enlarged color internal image to form a second reduced color internal image for modulation at a second spatial light modulator to provide a second color modulated image;

(e) demagnifying said third enlarged color internal image to form a third reduced color internal image for modulation at a third spatial light modulator to provide a third color modulated image; and

(f) combining said first, second, and third color modulated images onto a single axis to form the multicolor image and projecting the multicolor image toward the display surface.

18. A method for projecting a multicolor image according to claim 17 wherein the step of magnifying said internal image comprises the step of directing said internal image through a telecentric base condenser lens.

19. A method for projecting a multicolor image according to claim 17 wherein the step of demagnifying said first enlarged color internal image comprises the step of directing said first enlarged color internal image through a telecentric lens.

20. A method for projecting a multicolor image toward a display surface, the method comprising:

(a) magnifying a uniform illumination beam directed toward a color separator to obtain a low effective numerical aperture for said uniform illumination beam, thereby providing a first, second, and third monochromatic uniform illumination beam;

(b) demagnifying said first monochromatic uniform illumination beam directed toward a first spatial light modulator to obtain a high effective numerical aperture at said first spatial light modulator and modulating said first monochromatic uniform illumination beam to form a first color image beam;

(c) demagnifying said second monochromatic uniform illumination beam directed toward a second spatial light modulator to obtain a high effective numerical aperture at said second spatial light modulator and modulating said second monochromatic uniform illumination beam to form a second color image beam;

(d) demagnifying said third monochromatic uniform illumination beam directed toward a third spatial light modulator to obtain a high effective numerical aperture at said third spatial light modulator and modulating said third monochromatic uniform illumination beam to form a third color image beam; and

(e) combining said first, second, and third color image beams to form a multicolor image beam and projecting said multicolor image beam toward the display surface.

21. A method for projecting a multicolor image toward a display surface, the method comprising:

(a) providing a uniformized polychromatic illumination beam at a high numerical aperture;

(b) magnifying said uniformized illumination beam toward a color separator to provide a color illumination beam having low numerical aperture;

(c) demagnifying said color illumination beam toward a spatial light modulator to provide an unmodulated illumination beam having high numerical aperture; and

(d) modulating said unmodulated illumination beam having high numerical aperture to form a modulated beam, directing said modulated beam to a projection lens, and projecting said modulated beam toward the display surface.

22. A method for projecting a multicolor image according to claim 21 wherein the step of providing a uniformized polychromatic illumination beam comprises the step of energizing a lamp.

23. A method for projecting a multicolor image according to claim 21 wherein the step of demagnifying said color illumination beam toward a spatial light modulator comprises the step of directing said color illumination beam toward an LCD spatial light modulator.

24. A method for projecting a multicolor image according to claim 21 wherein the step of demagnifying said color illumination beam toward a spatial light modulator comprises the step of directing said color illumination beam toward a digital micromirror device.