Granted Patent B2

US 8,172,404 · App. 12/469,751 · Granted May 8, 2012

Abstract

Claims (29)

1. A coherent light projection system comprising:

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

an image forming system including one or more spatial light modulators 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 refractive speckle reduction element located at or substantially at the intermediate image plane, the refractive speckle reduction element comprising a lenslet arrangement formed on a surface of the refractive speckle reduction element, the lenslet arrangement comprising lenslets each having an aperture, wherein a size of the lenslet apertures is greater than or equal to a size of an image pixel of the intermediate image at the intermediate image plane such that refractive beam steering effects associated with the lenslet arrangement are substantially larger than any diffusion effects associated with the lenslet arrangements;

a movement generating system configured at least to move the refractive speckle reduction element and steer image light of the intermediate image as the intermediate image is transferred through the lenslet arrangement of the refractive 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 refractive 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 the size of the lenslet apertures is large enough to substantially preserve the original wavefront phase content of the light transiting through the refractive speckle reduction element.

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 separated by gaps.

6. The system of claim 5 , wherein a size of the gaps large enough to substantially preserve the original wavefront phase content of the light transiting through the refractive speckle reduction element.

7. The system of claim 5 , wherein a size of the gaps 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 refractive 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 energy inclusive of the zero diffraction order through the fourth diffraction order 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 energy inclusive of the zero diffraction order through the fourth diffraction order of the intermediate image, as transferred through the speckle reduction element, into an acceptance aperture of the projection system.

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. A method of projecting light comprising:

generating coherent light from a coherent light source system;

forming an image with an image forming system including one or more spatial light modulators 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 refractive 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 refractive speckle reduction element, the lenslet arrangement comprising lenslets each having an aperture, wherein a size of the lenslet apertures is greater than or equal to a size of an image pixel of the intermediate image at the intermediate image plane such that refractive beam steering effects associated with the lenslet arrangement are substantially larger than any diffraction effects associated with the lenslet arrangements;

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 refractive speckle reduction element with a projection subsystem.

Assignments (19)