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US4886341A
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Diffraction grating having a plurality of different grating constants
Assignee: Hitachi Ltd
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Filing: 1987-07-01
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Granted: 1989-12-12
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Expires: 2007-07-01
Abstract
Abstract In a diffraction grating grooves having at least two kinds of grating constants are alternately arranged so as to repetitive at a constant period.
Inventors
- 👤 Konosuki Oishi
- 👤 Kenshi Sugahara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 04:51
CPC Classifications
G; G02; G02B; G02B5/00; G02B5/18; G02B5/1861
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
92 words
A diffraction grating comprising a plurality of adjacent sets of different grating constants repetitively arranged at a constant period, each set including at least one groove, wherein when it is assumed that the different grating constants are d 1 , d 2 . . . , there is a relation of: d.sub.0 =md.sub.1 =nd.sub.2 =. . . where m and n are different natural numbers and d 0 is a constant; and wherein the constant period equals d 0 times the number of the plurality of adjacent sets of different grating constants.
Claim 2
Dependent Claim
92 words
A diffraction grating comprising a plurality of adjacent sets of different grating constants repetitively arranged at a constant period, each set including at least one groove, wherein when it is assumed that the different grating constants are d 1 , d 2 . . . , there is a relation of: d.sub.0 =md.sub.1 =nd.sub.2 =. . . where m and n are different natural numbers and d 0 is a constant; and wherein the constant period equals d 0 times the number of the plurality of adjacent sets of different grating constants.
Claim 3
Dependent Claim
45 words
A diffraction grating according to claim 1, wherein the number of the plurality of adjacent sets of different grating constants is two, the at least one set has one groove, the adjacent set has two grooves, m=1, n=2 and the constant period =2d 0 .
Claim 4
Dependent Claim
40 words
A diffraction grating according to claim 1, wherein one of said plurality of adjacent sets of different grating constants includes at least one groove and an adjacent set includes a plurality of grooves different in number than the one set.
Claim 5
Dependent Claim
45 words
A diffraction grating according to claim 3, wherein the number of the plurality of adjacent sets of different grating constants is two, the at least one set has one groove, the adjacent set has two grooves, m=1, n=2 and the constant period =2d 0 .
Claim 6
Dependent Claim
43 words
A diffraction grating according to claim 4, wherein the plurality of adjacent sets are arranged in a direction perpendicular to a longitudinal direction of the at least one groove of each set so as to provide the repetitive arrangement at the constant period.
Claim 7
Dependent Claim
43 words
A diffraction grating according to claim 1, wherein the plurality of adjacent sets are arranged in a direction perpendicular to a longitudinal direction of the at least one groove of each set so as to provide the repetitive arrangement at the constant period.
References Cited (Backward Citations)
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US3791737A
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SU934246A1
Cited
JPS58117511A
Cited
US4528448A
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-12-11 | 1993-06-12 | 1993-12-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-12-11 | 1997-06-12 | 1997-12-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-12-11 | 2001-06-12 | 2001-12-12 | $7700.00 | Window Closed / Lapsed |