Patent EP0349144B1 successfully refreshed from Google Patents.
EP0349144B1
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Birefringence diffraction grating type polarizer
Assignee: NEC Corp
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Filing: 1989-06-13
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Granted: 1994-09-07
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Expires: 2009-06-13
Abstract
No abstract record available.
Inventors
- 👤 Yutaka C/O Nec Corporation Urino
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 14:09
CPC Classifications
G; G02; G02B; G02B5/00; G02B5/18; G02B5/1833; G02B5/30; G02B5/3083
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
77 words
A birefringence diffraction grating type polarizer: comprising, an optically anisotropic sheet crystal substrate (1) having periodic ion-exchanged regions (2) to provide an optical diffraction grating; characterised in that; dielectric layers (3) are provided over said ion-exchanged regions, said dielectric layers (3) having a refractive index proximate or equal to that of said crystal substrate; and an anti-reflection layer (4) of a uniform thickness is provided over the whole surface of said crystal substrate and said dielectric layers.
Claim 2
Dependent Claim
43 words
A birefringence diffraction grating type polarizer as defined in claim 1, wherein said dielectric layers (3) are of a substance selected from lithium niobate, niobium pentoxide, zirconium oxide, zinc sulphide (ZnS), titanium dioxide (Ti0₂), cerium dioxide (Ce0₂), tantalum pentoxide (Ta₂0₅) and tellurium oxide.
Claim 3
Dependent Claim
41 words
A birefringence diffraction grating type polarizer as defined in claim 1 or 2, wherein said anti-reflection layer (4) is of a material of a refractive index substantially equal to the square root of the refractive index of said sheet crystal substrate.
Claim 4
Dependent Claim
46 words
A birefringence diffraction grating type polarizer as defined in claim 1, 2 or 3, wherein said anti-reflection layer (4) is of a thickness determined by a calculation in which a light wavelength is divided by a value four times the refractive index of said anti-reflection layer.
Claim 5
Dependent Claim
43 words
A birefringence diffraction grating type polarizer as defined in any of claims 1 to 4, wherein said anti-reflection layer (4) is of a material selected from silicon dioxide, calcium fluoride (CaF₂), alumium fluoride (A1F₃), lanthanum fluoride (LaF₃), strontium fluoride (SrF₂) and magnesium fluoride.
Claim 6
Dependent Claim
56 words
A birefringence diffraction grating type polarizer as defined in any preceding claim, in which the dimensions of the ion -exchanged regions and the dielectric layers are selected in view of their refractive indices so that the polarizer does not substantially diffract the ordinary ray component of light with which the polarizer is intended to be used.
References Cited (Backward Citations)
No citation records indexed.
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