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

• US 6,809,873 B2
• Filed: 09/09/2002
• Issued: 10/26/2004
• Est. Priority Date: 09/09/2002
• Status: Expired due to Fees

• Current Assignee: Eastman Kodak Company
• Original Assignee: Eastman Kodak Company
• Inventors: Cobb, Joshua M.
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): Harrington, Alicia M.
• Application Number:
  US10/237,516
• Publication Number:
  US 20040047045A1
• Time in Patent Office: 778 Days
• Field of Search: 359/618, 359/623, 359/627, 359/629, 359/634, 359/636, 359/663, 353/31-33, 353/34, 353/81
• 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 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;

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

(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.

2. 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.

3. A method for projecting a multicolor image according to claim 2 wherein the step of magnifying said internal image comprises the step of directing said internal image through a telecentric base condenser lens.

4. A method for projecting a multicolor image according to claim 2 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.

5. 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.

6. 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;

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

(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.