PROJECTION WITH LENSLET ARRANGEMENT ON SPECKLE REDUCTION ELEMENT

• US 20100296064A1
• Filed: 05/21/2009
• Published: 11/25/2010
• Est. Priority Date: 05/21/2009
• Status: Active Grant

• Current Assignee: IMAX Theatres International Limited (IMAX Corporation)
• Original Assignee: Eastman Kodak Company
• Inventors: Kurtz, Andrew F., Metzger, Robert, Bietry, Joseph R., Silverstein, Barry D., Nothhard, Gary E.
• Granted Patent: US 8,172,404 B2
• Time in Patent Office: Days
• US Class Current: 353/38
• CPC Class Codes: G02B 27/48 Laser speckle optics
• CPC Class Codes: G02B 3/0056 arranged along two different directions in a plane, e.g. honeycomb arrangement of lenses G02B3/0043 takes precedence; miniaturised objectives for electronic devices employing wafer level optics G02B13/0085
• CPC Class Codes: G02B 5/02 Diffusing elements; Afocal elements
• 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 9/3161 using laser light sources using laser beams scanning the display screen H04N9/3129

Abstract

In a coherent light projection system including an image forming system, a relay system, a speckle reduction element, and a projection subsystem, the relay system can have a first f-number, and the projection subsystem can have a second f-number less than the first f-number. The relay system can have a first working distance, and the projection subsystem can have a second working distance less than the first working distance. The image forming system can project an initial image having a first size, and an intermediate image can have a second size greater than or equal to the first size. The speckle reduction element can have a curved surface through which the intermediate image is transferred. The speckle reduction element can include a lenslet arrangement formed on a surface thereof. The speckle reduction element can be moved in a direction parallel to an optical axis of the speckle reduction element.

Claims

1. A coherent light projection system comprising:

a coherent light source system configured at least to emit coherent light;

an image forming system configured at least to interact with the coherent light in a manner consistent with image data;

a relay system configured at least to form an intermediate image at an intermediate image plane from coherent light output from the image forming system, the intermediate image being an aerial real image;

a speckle reduction element located at or substantially at the intermediate image plane, the speckle reduction element comprising a lenslet arrangement formed on a surface of the speckle reduction element, the lenslet arrangement comprising lenslets each having an aperture, wherein each of all or substantially all of the lenslet apertures is greater than or equal to a size of a pixel of the intermediate image at the intermediate image plane;

a movement generating system configured at least to move the speckle reduction element and steer image light of the intermediate image as the intermediate image is transferred through the lenslet arrangement of the speckle reduction element; and

a projection subsystem configured at least to project the steered image light of the intermediate image, as transferred through the moving speckle reduction element.

2. The system of claim 1, wherein the lenslet arrangement comprises a random or substantially random distribution of lenslets.

3. The system of claim 1, wherein the lenslet arrangement comprises lenslets in or substantially in a hexagonal, linear, or diagonal pattern.

4. The system of claim 1, wherein the lenslet arrangement entirely or almost entirely comprises abutting lenslets.

5. The system of claim 1, wherein the lenslet arrangement entirely or almost entirely comprises non-abutting or sparsely distributed lenslets.

6. The system of claim 5, wherein a spacing between the lenslets is or substantially is large enough to allow a diffusion from the spacing to pass into an acceptance aperture of the projection lens.

7. The system of claim 5, wherein a spacing between the lenslets is greater than or equal to a size of a pixel of the intermediate image at the intermediate image plane.

8. The system of claim 5, wherein the movement-generating system is configured at least to move the speckle reduction element in-plane a distance that is greater than or equal to a period of lenslet repetition.

9. The system of claim 1, wherein an acceptance aperture of a lens in the projection subsystem is further configured to capture diffusion caused by spacings between the lenslets or valleys between abutting lenslets.

10. The system of claim 1, wherein an acceptance aperture of a lens in the projection subsystem captures a fourth order energy or below of the intermediate image, as transferred through the speckle reduction element.

11. The system of claim 1, wherein the lenslet arrangement is configured at least to pass a fourth order energy or lower of the intermediate image, as transferred through the speckle reduction element, into an acceptance aperture of the projection subsystem.

12. The system of claim 1, wherein the image forming system comprises light modulators and a dichroic combiner that aligns a plurality of color channels from the coherent light source system onto a common axis.

13. The system of claim 1, wherein the movement-generating system is configured at least to cause motion of the speckle reduction element in a direction parallel to an optical axis of the speckle reduction element.

14. The system of claim 13, wherein the motion parallel to the optical axis is within a depth of focus of the projection subsystem.

15. The system of claim 13, wherein the motion parallel to the optical axis is within a depth of focus of the relay system.

16. The system of claim 13, wherein the movement generating system is further configured at least to cause motion of the speckle reduction element in a direction perpendicular to the optical axis of the speckle reduction element.

17. The system of claim 1, wherein the image forming system is further configured to project an initial image having a first size, and wherein the intermediate image has a second size greater than or equal to the first size.

18. The system of claim 17, wherein the second size is consistent with a 16 mm, 35 mm, or 70 mm film format.

19. The system of claim 17, wherein the projection subsystem is further configured to correct for film buckle effects.

20. The system of claim 1, wherein the projection subsystem is further configured to correct for film buckle effects, and wherein the speckle reduction element has a curved surface configured at least to compensate for the projection subsystem'"'"'s correction of film buckle effects.

21. The system of claim 20, wherein the curved surface is a surface through which the intermediate image is received.

22. The system of claim 20, wherein the curved surface is a surface through which the intermediate image exits the speckle reduction element.

23. The system of claim 1, wherein the relay system has a first f-number, and the projection subsystem has a second f-number less than the first f-number.

24. The system of claim 23, wherein the second f-number is at least half the first f-number.

25. The system of claim 1, wherein the relay system has a first working distance, and the projection subsystem has a second working distance less than the first working distance.

26. The system of claim 25, wherein the second working distance is at least half the first working distance.

27. A method of projecting light comprising:

generating coherent light from a coherent light source system;

forming an image with an image forming system at least by interacting with the coherent light in a manner consistent with image data;

forming an intermediate image at an intermediate image plane at least from coherent light output from the image forming system, the intermediate image being an aerial real image formed with a relay system;

transferring the intermediate image through a speckle reduction element located at or substantially at the intermediate image plane, the speckle reduction element comprising a lenslet arrangement formed on a surface of the speckle reduction element, the lenslet arrangement comprising lenslets each having an aperture, wherein each of all or substantially all of the lenslet apertures is greater than or equal to a size of a pixel of the intermediate image at the intermediate image plane;

moving the speckle reduction element with a movement generating system while the intermediate image is transferred through the speckle reduction element; and

projecting the intermediate image, as transferred through the speckle reduction element with a projection subsystem.