Optical interference reducing element for laser projection

• US 8,235,531 B2
• Filed: 06/22/2009
• Issued: 08/07/2012
• Est. Priority Date: 06/22/2009
• Status: Active Grant

• Current Assignee: IMAX Theatres International Limited (IMAX Corporation)
• Original Assignee: Eastman Kodak Company
• Inventors: Silverstein, Barry D., Nothhard, Gary E., Bietry, Joseph R., Metzger, Robert
• Primary Examiner(s): Ko, Tony
• Assistant Examiner(s): Reilly-Diakun, Jori S
• Application Number:
  US12/488,661
• Publication Number:
  US 20100321639A1
• Time in Patent Office: 1,142 Days
• Field of Search: 353/31, 353/33, 353/38, 353/94, 359/599, 359618-619, 359/707
• US Class Current: 353/33
• CPC Class Codes: G02B 27/48 Laser speckle optics
• CPC Class Codes: G03B 21/2013 Plural light sources
• CPC Class Codes: G03B 21/2033 LED or laser light sources
• CPC Class Codes: G03B 21/208 Homogenising, shaping of the illumination light
• 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 9/3161 using laser light sources using laser beams scanning the display screen H04N9/3129

Abstract

A laser projection system comprising a laser source system configured to emit coherent light, an optical integrating system configured to uniformize coherent light it receives, a randomizing optical element configured to spatially move over time in order to temporally randomize the phase, angle or spatial location of coherent light it receives, an image forming system configured to interact with laser light that has been both uniformized by the optical integrating system and randomized by the randomizing optical element, thereby forming a laser light image, and a projection system configured to project the laser light image onto a viewing screen.

Claims

1. A digital projection system comprising:

a light source system configured to emit coherent light;

an optical integrating system including an optical integrating element configured to uniformize coherent light it receives, wherein the optical integrating element (53) is an optical integrating bar or waveguide;

a randomizing optical element configured to spatially move over time in order to temporally randomize the phase, angle or spatial location of coherent light it receives, wherein the optical integrating element immediately precedes the randomizing optical element in a path of the laser light with no intervening elements;

an image forming system configured to interact with laser light that has been both uniformized by the optical integrating system and randomized by the randomizing optical element, thereby forming a laser light image; and

a projection system configured to project the laser light image onto a viewing screen.

2. The laser projection system of claim 1, wherein the randomizing optical element is a refractive optical element.

3. The laser projection system of claim 1, wherein the randomizing optical element is a diffractive optical element.

4. The laser projection system of claim 1, wherein the randomizing optical element is spatially moved by rotation.

5. The laser projection system of claim 1, wherein the randomizing optical element is spatially moved by translation.

6. The laser projection system of claim 1, wherein the optical integrating system has an associated input plane preceding the optical integrating system in the path of the emitted laser light and an associated output plane following the optical integrating system in the path of the emitted laser light.

7. The laser projection system of claim 6, wherein the randomizing optical element is located at or substantially at the output plane.

8. The laser projection system of claim 1, wherein the randomizing optical element comprises one or more anti-Newton glass surfaces.

9. The laser projection system of claim 1, wherein the randomizing optical element acts to reduce coherence artifacts in the projected laser light image.