Low thermal stress birefringence imaging system
First Claim
1. An imaging system having reduced susceptibility to thermally induced stress birefringence, for projecting an image of an object plane onto a display surface, comprising:
- a relay lens, which images the object plane onto an intermediate image plane, the relay lens having a relay lens aperture stop, a first group of lens elements located between the object plane and the relay lens aperture stop, and a second group of lens elements located between the relay lens aperture stop and the intermediate image plane; and
a projection lens, which images the intermediate image plane onto the display surface, the imaging lens having a projection lens aperture stop, a third group of lens elements located between the intermediate image plane and the projection lens aperture stop, and a fourth group of lens elements located between the projection lens aperture stop and the display surface;
wherein the lens elements in the first and second groups of lens elements that are immediately adjacent to the relay lens aperture stop and the lens elements in the third and fourth groups of lens elements that are immediately adjacent to the projection lens aperture stop, are fabricated using glasses having a negligible susceptibility to thermal stress birefringence as characterized by a thermal stress birefringence metric; and
wherein the other lens elements in the first, second, third, and fourth groups of lens elements, that are not the lens elements immediately adjacent to the relay lens aperture stop and the projection lens aperture stop, are fabricated using glasses having at most a moderate susceptibility to thermal stress birefringence as characterized by the thermal stress birefringence metric.
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Accused Products
Abstract
An imaging system having reduced susceptibility to thermally induced stress birefringence, comprising; a relay lens, which images the object plane onto an intermediate image plane; a projection lens, which images the intermediate image plane onto the display surface. The lens elements that are immediately adjacent to a relay lens aperture stop and a projection lens aperture stop are fabricated using glasses having a negligible susceptibility to thermal stress birefringence, and the other lens elements are fabricated using glasses having at most a moderate susceptibility to thermal stress birefringence as characterized by the thermal stress birefringence metric.
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Citations
25 Claims
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1. An imaging system having reduced susceptibility to thermally induced stress birefringence, for projecting an image of an object plane onto a display surface, comprising:
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a relay lens, which images the object plane onto an intermediate image plane, the relay lens having a relay lens aperture stop, a first group of lens elements located between the object plane and the relay lens aperture stop, and a second group of lens elements located between the relay lens aperture stop and the intermediate image plane; and a projection lens, which images the intermediate image plane onto the display surface, the imaging lens having a projection lens aperture stop, a third group of lens elements located between the intermediate image plane and the projection lens aperture stop, and a fourth group of lens elements located between the projection lens aperture stop and the display surface; wherein the lens elements in the first and second groups of lens elements that are immediately adjacent to the relay lens aperture stop and the lens elements in the third and fourth groups of lens elements that are immediately adjacent to the projection lens aperture stop, are fabricated using glasses having a negligible susceptibility to thermal stress birefringence as characterized by a thermal stress birefringence metric; and wherein the other lens elements in the first, second, third, and fourth groups of lens elements, that are not the lens elements immediately adjacent to the relay lens aperture stop and the projection lens aperture stop, are fabricated using glasses having at most a moderate susceptibility to thermal stress birefringence as characterized by the thermal stress birefringence metric. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. An imaging system having reduced susceptibility to thermally induced stress birefringence, for projecting an image of an object plane onto a display surface, comprising;
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a relay lens, which images the object plane onto an intermediate image plane, the relay lens having a relay lens aperture stop, a first group of lens elements located between the object plane and the relay lens aperture stop, and a second group of lens elements located between the relay lens aperture stop and the intermediate image plane; and a projection lens, which images the intermediate image plane onto the display surface, the imaging lens having a projection lens aperture stop, a third group of lens elements located between the intermediate image plane and the projection lens aperture stop, and a fourth group of lens elements located between the projection lens aperture stop and the display surface; wherein the lens elements in the first and second groups of lens elements experiencing the highest optical power densities are fabricated using glasses having a negligible susceptibility to thermal stress birefringence as characterized by a thermal stress birefringence metric; and wherein all of the lens elements in the first, second, third, and fourth groups of lens elements are fabricated using glasses having at most a moderate susceptibility to thermal stress birefringence as characterized by the thermal stress birefringence metric.
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21. A laser-based projection system having reduced susceptibility to thermally induced stress birefringence which projects an image onto a display surface, comprising:
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at least one laser-based illumination system that provides polarized illumination light to at least one spatial light modulator device that modulated the polarized illumination light responsive to image data; a relay lens assembly that images light collected from at least one spatial light modulator to an intermediate image plane, the relay lens having a first group of lens elements and a second group of lens elements located to either side of a relay lens aperture stop; and a projection lens assembly that images light collected from the intermediate image plane to the display surface, the imaging lens having a third group of lens elements and a fourth group of lens elements located to either side of a projection lens aperture stop; and wherein the lens elements immediately adjacent to the relay lens aperture stop and the projection lens aperture stop, are fabricated using glasses having a negligible susceptibility to thermal stress birefringence induced by light absorbed while transiting these lens elements as characterized by a thermal stress birefringence metric; and wherein the other lens elements in the first, second, third, and fourth group of elements, that are not the lens elements immediately adjacent to the relay lens aperture stop and the projection lens aperture stop, are fabricated using glasses that have at most a moderate susceptibility to thermal stress birefringence induced by light absorbed while transiting these lens elements as characterized by a thermal stress birefringence metric. - View Dependent Claims (22, 23, 24, 25)
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Specification