US4953960A
Expired / Lapsed
US
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Optical reduction system
Assignee: ASML Holding NV
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Filing: 1988-07-15
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Granted: 1990-09-04
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Expires: 2008-07-15
Abstract
Abstract An unobscured catadioptric optical reduction system wherein all refractive elements are made of the same material. From its long conjugate end to its short conjugate end the system comprises a first lens group, a beamsplitter, a second lens group, a mirror and a third lens group arranged so that radiation entering the system at its long conjugate end passes through the first lens group, the beamsplitter, the second lens group, and is reflected by the mirror back through the second lens group and is reflected by the beamsplitter through the third lens group. Aberrations of the mirror are corrected by the refractive elements. Lateral color correction is obtained by balancing the power of the first lens group against the power of the third lens group.
Inventors
- 👤 David M. Williamson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 14:09
CPC Classifications
G; G02; G02B; G02B17/00; G02B17/08; G02B17/0892; G03; G03F; G03F7/00; G03F7/70; G03F7/70216; G03F7/70225
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
75 words
A catadioptric optical reduction system comprising from the long conjugate end to the short conjugate end: a first lens group; a beamsplitter; a second lens group; a reduction mirror; a third lens group; arranged such that radiation entering said system passes through said first lens group, said beamsplitter, said second lens group and is reflected by said reflector back through said second lens group and is reflected by said beamsplitter through said third lens group.
Claim 2
Dependent Claim
75 words
A catadioptric optical reduction system comprising from the long conjugate end to the short conjugate end: a first lens group; a beamsplitter; a second lens group; a reduction mirror; a third lens group; arranged such that radiation entering said system passes through said first lens group, said beamsplitter, said second lens group and is reflected by said reflector back through said second lens group and is reflected by said beamsplitter through said third lens group.
Claim 3
Dependent Claim
31 words
An optical system according to claim 1 wherein: said first lens group corrects for lateral color and distortion correction by balancing its power against the power of the third lens group.
Claim 4
Dependent Claim
26 words
An optical system according to claim 1 wherein said first, second, and third lens groups together correct for aberrations introduced into the system by the mirror.
Claim 5
Dependent Claim
26 words
An optical system according to claim 2 wherein said first, second, and third lens groups together correct for aberrations introduced into the system by the mirror.
Claim 6
Dependent Claim
19 words
An optical system according to claim 4 wherein: said second lens group corrects low order coma and spherical aberrations.
Claim 7
Dependent Claim
22 words
An optical system according to claim 5 wherein: said third lens group corrects for high order coma and higher orders of distortion.
Claim 8
Dependent Claim
16 words
An optical system according to claim 6 wherein: said third lens group predominately corrects for astigmatism.
Claim 9
Dependent Claim
24 words
An optical system according to claim 7 wherein: said first, second, and third lens groups and said beamsplitter are composed of the same material.
Claim 10
Dependent Claim
13 words
An optical system according to claim 8 wherein: said material is fused silica.
Claim 11
Dependent Claim
13 words
An optical system according to claim 9 wherein: said beamsplitter is a cube.
Claim 12
Dependent Claim
16 words
An optical system according to claim 9 wherein: said beamsplitter is a tilted thin parallel plate.
Claim 13
Dependent Claim
22 words
An optical system according to claim 11 wherein said first lens group includes means for collimating radiation before it enters said beamsplitter.
Claim 14
Dependent Claim
25 words
An optical system according to claim 10 further including a lens group disposed before said first lens group providing telecentricity at said long conjugate end.
Claim 15
Dependent Claim
19 words
An optical system according to claim 12 wherein: said third lens group provides telecentricity at said short conjugate end.
Claim 16
Dependent Claim
19 words
An optical system according to claim 13 wherein: said third lens group provides telecentricity at said short conjugate end.
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) | 1993-09-03 | 1994-03-05 | 1994-09-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-09-03 | 1998-03-05 | 1998-09-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-09-03 | 2002-03-05 | 2002-09-04 | $7700.00 | Window Closed / Lapsed |