Multi-beam laser scanning display system with speckle elimination
First Claim
Patent Images
1. A laser projection system for projecting an image with reduced speckle on a display surface, comprising:
- a light modulator for modulating laser light responsive to signals indicative of said image;
an optical system that defines an intermediate image plane for said modulated laser light, said intermediate image plane situated between said light modulator and the display surface;
a speckle eliminator situated approximately at said intermediate image plane and comprising a diffusion plate, motion-inducing elements coupled to said diffusion plate and arranged approximately orthogonally with respect to said diffusion plate and means for energizing said motion-inducing elements to provide a non-zero phase shift between the motions of said orthogonal elements, thereby avoiding periodic moments of zero velocity; and
an optical imaging system arranged to image said intermediate image plane and project diffused modulated laser light from said speckle eliminator on the display surface to display an image.
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Abstract
A display system includes blue, green, and red laser light sources and light shaping devices which receive the laser light from the laser light sources and shapes the light into a number of approximately identical beamlets. The beamlets are modulated individually and the modulated beamlets are combined. The combining results in an output of beamlets, each of which comprises three input beamlets of each of the colors red, green, and blue. The resultant beamlets can then be scanned onto a display screen.
223 Citations
26 Claims
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1. A laser projection system for projecting an image with reduced speckle on a display surface, comprising:
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a light modulator for modulating laser light responsive to signals indicative of said image; an optical system that defines an intermediate image plane for said modulated laser light, said intermediate image plane situated between said light modulator and the display surface; a speckle eliminator situated approximately at said intermediate image plane and comprising a diffusion plate, motion-inducing elements coupled to said diffusion plate and arranged approximately orthogonally with respect to said diffusion plate and means for energizing said motion-inducing elements to provide a non-zero phase shift between the motions of said orthogonal elements, thereby avoiding periodic moments of zero velocity; and an optical imaging system arranged to image said intermediate image plane and project diffused modulated laser light from said speckle eliminator on the display surface to display an image. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of eliminating speckle in an image displayed on a display surface by a laser projection system, comprising:
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modulating laser light responsive to signals indicative of the image; diffusing said modulated laser light through a diffuser situated at an intermediate image plane in the laser projection system to substantially eliminate speckle in the displayed image by nutating a diffusion plate in the modulated laser light at said intermediate image plane, said nutational motion being approximately orthogonal to the propagation direction of the modulated laser light and avoiding periodic movement of zero velocity; and imaging said intermediate image plane on the display surface, including projecting diffused modulated laser light to display an image. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A scanning projection system for projecting an image on a display surface, comprising:
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a plurality of spatial light modulators (SLMs) that modulate laser light and generate a corresponding plurality of linear arrays of modulated laser beams with an approximately uniform spacing between adjacent beams, each of said linear SLMs having a monolithic structure including a plurality of modulator elements arranged in a linear configuration with an approximately constant pitch, a scanner arranged for scanning said modulated laser light; and an optical system defining an intermediate image plane for said linear arrays of modulated light between said scanner and said display surface; a speckle eliminator situated approximately at said intermediate image plane and comprising a diffuser plate, and motion-inducing elements coupled to said diffuser plate and orthogonally arranged with respect to said diffusion plate to provide a non-zero phase shift between the motions of said orthogonal elements thereby avoiding periodic moments of zero velocity; and an optical imaging system that images said intermediate image plane and projects said scanned modulated laser light on the display surface to display a scanned image. - View Dependent Claims (25)
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26. A laser projection system for projecting an image with reduced speckle on a display surface, comprising:
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a light modulator for modulating laser light responsive to signals indicative of said image; an optical system that defines an intermediate image plane for said modulated laser light, said intermediate image plane situated between said light modulator and the display surface; a speckle eliminator including a wax diffusion plate situated approximately at said intermediate image plane; and an optical imaging system arranged to image said intermediate image plane and project diffused modulated laser light from said speckle eliminator on the display surface to display an image.
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Specification