Broadband protective optical window coating
First Claim
1. A protective coating having broadband transmittance for an optical substrate comprising:
- an AlP layer deposited on said substrate;
an AlGaP layer deposited on said AlP layer; and
an anti-reflection film layer deposited on said AlGaP layer.
2 Assignments
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Accused Products
Abstract
The present invention provides a broadband transmitting protective coating (10) including an AlGaP protective layer (14) deposited on an optical substrate (12) and an anti-reflection film (16) deposited on the AlGaP protective layer (14). The coating (10) is suitable for use with typical infrared and broadband optical substrate materials such as germanium or multi-spectral ZnS. In the case of a germanium substrate (12), the anti-reflection film (16), (16a) preferably consists of a single layer of hard carbon or alternating layers of hard carbon and silicon. In the case of a multi-spectral ZnS substrate (12a), the anti-reflection film (16b) preferably consists of layered Al2 O3 /TaO5 /LaF3 /MgF2. The protective coating (10) is preferably deposited on the optical substrate (12) by a metal organic chemical vapor deposition process wherein an initial layer of AlP is nucleated on the substrate (12) at a temperature of approximately 400° C. The temperature of the substrate (12) is then raised to approximately 600° C. and a layer of AlGaP (14) is grown on the substrate (12) to a preselected thickness. The AlGaP coated optical substrate (12) is then polished to a desired smoothness. The anti-reflection film (16) is then deposited on the AlGaP layer (14) using an RF chemical vapor deposition process or a thermal evaporation process.
49 Citations
18 Claims
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1. A protective coating having broadband transmittance for an optical substrate comprising:
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an AlP layer deposited on said substrate; an AlGaP layer deposited on said AlP layer; and an anti-reflection film layer deposited on said AlGaP layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An optical window for use in airborne and ground based tactical and surveillance sensors suitable for withstanding high speed rain and sand impact with improved broadband transmittance, said optical window comprising:
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a germanium substrate; an AlP nucleating layer deposited on said germanium substrate; an AlGaP protective layer deposited on said AlP nucleating layer to a preselected thickness; and an anti-reflection film deposited on said AlGaP protective layer. - View Dependent Claims (10, 11, 12, 13)
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14. An optical window for use in airborne and ground based tactical and surveillance sensors suitable for withstanding high speed rain and sand impact with improved broadband transmittance, said optical window comprising:
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a multi-spectral zinc sulfide, zinc sulfide or zinc selenoid substrate; an AlP nucleating layer deposited on said substrate; an AlGaP protective layer deposited on said AlP nucleating layer to a pre-selected thickness; and an anti-reflection film deposited on said AlGaP protective layer. - View Dependent Claims (15, 16, 17, 18)
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Specification