Coherence delay augmented laser beam homogenizer
First Claim
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1. An optical system comprising a light beam, a coherence delay line, and a homogenizer, wherein:
- said coherence delay line comprises a first partially reflecting mirror and a second totally reflecting mirror, and;
said homogenizer comprises a light tunnel with transparent ends and reflective sidewalls, wherein;
at least a portion of said light beam is incident upon said partially reflecting mirror at a first position where a portion is transmitted into said homogenizer, and a portion is reflected into said totally reflecting mirror.
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Abstract
The geometrical restrictions on a laser beam homogenizer are relaxed by ug a coherence delay line to separate a coherent input beam into several components each having a path length difference equal to a multiple of the coherence length with respect to the other components. The components recombine incoherently at the output of the homogenizer, and the resultant beam has a more uniform spatial intensity suitable for microlithography and laser pantogography. Also disclosed is a variable aperture homogenizer, and a liquid filled homogenizer.
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Citations
17 Claims
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1. An optical system comprising a light beam, a coherence delay line, and a homogenizer, wherein:
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said coherence delay line comprises a first partially reflecting mirror and a second totally reflecting mirror, and; said homogenizer comprises a light tunnel with transparent ends and reflective sidewalls, wherein; at least a portion of said light beam is incident upon said partially reflecting mirror at a first position where a portion is transmitted into said homogenizer, and a portion is reflected into said totally reflecting mirror. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A coherence delay line comprising a laser beam, a first partially reflective mirror, and a second totally reflective mirror, wherein:
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said first and second mirrors have planar surfaces facing each other, and; said laser beam is incident upon said first mirror at a first position where a portion is transmitted, and a portion is reflected towards, and then reflected from said second mirror, wherein; the portion reflected from said second mirror is parallel to said incident laser beam. - View Dependent Claims (11, 12, 13, 14)
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15. A homogenizer comprising a polygonal cavity either filled with a gas, and having a reflective coating on the cavity walls, or;
filled with a liquid having an index of refraction greater than the material of the cavity walls. - View Dependent Claims (16, 17)
Specification