Patent US5224200A successfully refreshed from Google Patents.
US5224200A
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Coherence delay augmented laser beam homogenizer
Assignee: United States Department of Energy
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Filing: 1991-11-27
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Granted: 1993-06-29
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Expires: 2011-11-27
Abstract
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.
Inventors
- 👤 Paul Rasmussen
- 👤 Anthony Bernhardt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 17:53
CPC Classifications
G; G02; G02B; G02B27/00; G02B27/09; G02B27/0927; G02B27/0938; G02B27/0977; G02B27/0994; G02B27/48; G02B5/00; G02B5/005; G02B6/00; G02B6/24; G02B6/26; G02B6/28; G02B6/2804; G02B6/2861; G03; G03F; G03F7/00; G03F7/70; G03F7/70058; G03F7/70483; G03F7/7055; G03F7/70583; H; H01; H01S; H01S3/00; H01S3/005
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
82 words
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.
Claim 2
Dependent Claim
82 words
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.
Claim 3
Dependent Claim
35 words
The system of claim 1 wherein said light beam has a coherence length greater than 3 millimeters, and said first and second mirrors are separated by an integral multiple of half of said coherence length.
Claim 4
Dependent Claim
56 words
The system of claim 1 wherein the portion of said light beam that is reflected into said totally reflecting mirror is reflected back into said partially reflecting mirror at a second position different from the first position, where a portion is transmitted into said homogenizer, and a portion is reflected back into said totally reflecting mirror.
Claim 5
Dependent Claim
31 words
The system of claim 3 wherein the reflection and transmission process is repeated until a portion of said light beam is reflected directly from said totally reflecting mirror into said homogenizer.
Claim 6
Dependent Claim
25 words
The system of claim 4 wherein all portions of said light beam that are transmitted through said partially reflecting mirror are substantially equal in intensity.
Claim 7
Dependent Claim
28 words
The system of claim 5 wherein the thickness of the partially reflective coating on said partially reflective mirror decreases at each successive position of incidence by said beam.
Claim 8
Dependent Claim
17 words
The system of claim 1 wherein said homogenizer comprises a light tunnel with a variable cross section.
Claim 9
Dependent Claim
51 words
The system of claim 7 wherein said light tunnel is a polygonal cavity formed by four rods with rectangular cross sections that are contiguous with, and staggered with respect to their neighbors, and said rods are coated with a reflective coating on at least the sides forming said light tunnel sidewalls.
Claim 10
Dependent Claim
31 words
The system of claim 1 wherein said light tunnel is a polygonal cavity filled with a liquid having a greater index of refraction than the material forming said light tunnel sidewalls.
Claim 11
Dependent Claim
78 words
A coherence delay line comprising a laser beam, a first partially reflective mirror, and a second totally reflective mirror, wherein: 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.
Claim 12
Dependent Claim
78 words
A coherence delay line comprising a laser beam, a first partially reflective mirror, and a second totally reflective mirror, wherein: 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.
Claim 13
Dependent Claim
45 words
The delay line of claim 10 wherein the portion reflected from said second mirror strikes said first mirror at a position different from said first position, where again a portion is transmitted, and a portion is reflected towards, and then reflected from said second mirror.
Claim 14
Dependent Claim
47 words
The delay line of claim 11 wherein the beam is successively reflected back and forth between said first and second mirrors, and each time the beam strikes said first mirror a portion is transmitted, and a portion is reflected towards, and then reflected from said second mirror.
Claim 15
Dependent Claim
15 words
The delay line of claim 12 wherein the transmitted portions all have substantially equal intensities.
Claim 16
Dependent Claim
20 words
The delay line of claim 10 wherein the reflective coatings on said mirrors are made from quarter wavelength thin films.
Claim 17
Dependent Claim
38 words
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.
Claim 18
Dependent Claim
38 words
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.
Claim 19
Dependent Claim
30 words
The homogenizer of claim 15 comprising a plurality of polygonal rods that are contiguous with, and staggered with respect to their neighbors to form a polygonal cavity with adjustable dimensions.
Claim 20
Dependent Claim
15 words
The homogenizer of claim 16 wherein the cross section of said polygonal cavity is rectangular.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-06-28 | 1996-12-28 | 1997-06-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-06-28 | 2000-12-28 | 2001-06-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-06-28 | 2004-12-28 | 2005-06-29 | $7700.00 | Window Closed / Lapsed |