METHOD, APPARATUS, AND DIFFUSER FOR REDUCING LASER SPECKLE
First Claim
1. A method of reducing speckle comprising:
- a. dividing a laser illuminated area into phase cells;
b. subdividing the phase cells into a number of cell partitions; and
c. applying a temporal phase variation to the cell partitions within an integration time of an intensity detector viewing the laser illuminated area.
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Accused Products
Abstract
A method of reducing speckle includes dividing a laser illuminated area into phase cells, subdividing the phase cells into cell partitions, and applying a temporal phase variation to the cell partitions within an integration time of an intensity detector viewing the laser illuminated area. An apparatus for reducing speckle includes illumination optics, a diffuser, and projection optics. The illumination optics couple a laser illumination to the diffuser, which is located in a first image plane. The diffuser divides the laser illumination into the phase cells and subdivides the phase cells into the cell partitions. The diffuser also applies the temporal phase variation to the cell partitions. The projection optics project an image of the first image plane onto a diffuse surface. A display apparatus adds a light modulator to the apparatus for reducing speckle and places the light modulator in a third image plane located between a laser source and the diffuser. The diffuser includes first and second diffuser cells, each of which include first and second diffuser cell partitions. In use, the first diffuser cell partitions induce a first relative phase of zero while the second diffuser cell partitions induce a second relative phase of pi radians. The first and second diffuser cell partitions of the first diffuser cells are preferably arranged in a first Hadamard matrix pattern. The first and second diffuser cell partitions of the second diffuser cell are preferably arranged in a second Hadamard matrix pattern.
129 Citations
41 Claims
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1. A method of reducing speckle comprising:
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a. dividing a laser illuminated area into phase cells;
b. subdividing the phase cells into a number of cell partitions; and
c. applying a temporal phase variation to the cell partitions within an integration time of an intensity detector viewing the laser illuminated area. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. An apparatus for displaying a two dimensional image on a display screen comprising:
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a. a light modulator configured such that in operation a laser illumination illuminates the light modulator and further such that in operation the light modulator modulates the laser illumination to form an array of pixels;
b. a first optical arrangement optically coupled to the light modulator and configured such that in operation the first optical arrangement images the array of pixels in a first image plane;
c. a diffuser located at about the first image plane such that in operation the diffuser divides each pixel of the array of pixels into a number of sub-pixels and applies a temporal phase variation to the sub-pixels of each pixel; and
d. a second optical arrangement optically coupled to the diffuser, the second optical arrangement configured such that in operation the second optical arrangement projects the array of pixels onto the display screen to produce the two dimensional image. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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28. An apparatus for reducing speckle observed by an intensity detector when the intensity detector views a laser illuminated area comprising:
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a. a diffuser optically coupled to a laser illumination, the diffuser dividing resolution spots observed by the intensity detector into a number of sub-resolution spots, the number of sub-resolution spots comprising at least four of the sub-resolution spots; and
b. means for applying a temporal phase variation to the sub-resolution spots of each resolution spot. - View Dependent Claims (29, 30)
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31. An apparatus for reducing speckle observed by an intensity detector when the intensity detector views a laser illuminated area comprising:
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a. means for dividing resolution spots observed by the intensity detector into a number of sub-resolution spots, the number of sub-resolution spots comprising at least four of the sub-resolution spots; and
b. means for applying a temporal phase variation to the sub-resolution spots observed by the intensity detector. - View Dependent Claims (32, 33)
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34. A diffuser for reducing speckle produced by a laser illumination illuminating a surface where the surface is viewed by an intensity detector comprising:
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a. a first diffuser cell comprising first and second cell partitions configured to induce first and second relative phases of zero and pi radians, respectively, the first and second cell partitions arranged in a first Hadamard matrix pattern corresponding to a first Hadamard matrix having a matrix order of at least a second order; and
b. a second diffuser cell comprising the first and second cell partitions arranged in a second Hadamard matrix pattern corresponding to a second Hadamard matrix having the matrix order where the first and second Hadamard matrices satisfy a decorrelation condition. - View Dependent Claims (35, 36, 37, 38, 39)
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40. A diffuser for reducing speckle produced by a laser illumination illuminating a surface where the surface is viewed by an intensity detector comprising:
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a. a first diffuser cell comprising first through fourth cell partitions, the first, second, and third cell partitions configured to apply a first relative phase of zero to the laser illumination illuminating the surface, the fourth cell partition configured to apply a second relative phase of pi radians to the laser illumination illuminating the surface;
b. a second diffuser cell comprising the first through fourth cell partitions, the first, second, and fourth cell partitions configured to apply the first relative phase to the laser illumination illuminating the surface, the third cell partition configured to apply the second relative phase to the laser illumination illuminating the surface;
c. a third diffuser cell comprising the first through fourth cell partitions, the first, third, and fourth cell partitions configured to apply the first relative phase to the laser illumination illuminating the surface, the second cell partition configured to apply the second relative phase to the laser illumination illuminating the surface; and
d. a fourth diffuser cell comprising the first through fourth cell partitions, the second, third, and fourth cell partitions configured to apply the first relative phase to the laser illumination illuminating the surface, the first cell partition configured to apply the second relative phase to the laser illumination illuminating the surface. - View Dependent Claims (41)
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Specification