US4966437A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fault-tolerant anti-reflective coatings
Assignee: Northrop Grumman Guidance and Electronics Co Inc
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Filing: 1988-04-19
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Granted: 1990-10-30
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Expires: 2008-04-19
Abstract
Abstract A method for producing a narrow band anti-reflective film on a substrate, and the film produced by that method. Uses the concept of considering a multifilm dielectric to be an equivalent two-film dielectric, then removing a predetermined thickness of the outer, lower dielectric, film to cause the complete multifilm to become anti-reflective. When limited numbers of film materials are available, uses an EIL or effective index layer concept to obtain a predetermined index of refraction which improves the tolerance of the reflection of an anti-reflective film to film thickness errors.
Inventors
- 👤 John P. Rahn
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 04:00
CPC Classifications
G; G02; G02B; G02B1/00; G02B1/10; G02B1/11; G02B1/113; G02B1/115
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
175 words
A method for making an anti-reflective dielectric multifilm, having an outer film of a first material with a known index of refraction and successive layers of second and said first materials, said second material having a known index of refraction higher than the index of refraction of said first material, on a substrate of known index of refraction comprising: determining the desired predetermined effective index of refraction for the multifilm, said effective index having an increased tolerance to its thickness errors and being correctable for those thickness errors by reducing the thickness of its outer layer and creating a dielectric multifilm of more than two films having the correct ratio of thicknesses of its sub-layers to obtain the above-mentioned effective index of refraction on an optical substrate, with the outermost film, of said first material, having a thickness greater than its required thickness; and reducing the thickness of said outermost film of said created multifilm to compensate for total thickness error of both itself and said created multifilm to reduce the reflectivity of the multifilm.
Claim 2
Independent Claim
175 words
A method for making an anti-reflective dielectric multifilm, having an outer film of a first material with a known index of refraction and successive layers of second and said first materials, said second material having a known index of refraction higher than the index of refraction of said first material, on a substrate of known index of refraction comprising: determining the desired predetermined effective index of refraction for the multifilm, said effective index having an increased tolerance to its thickness errors and being correctable for those thickness errors by reducing the thickness of its outer layer and creating a dielectric multifilm of more than two films having the correct ratio of thicknesses of its sub-layers to obtain the above-mentioned effective index of refraction on an optical substrate, with the outermost film, of said first material, having a thickness greater than its required thickness; and reducing the thickness of said outermost film of said created multifilm to compensate for total thickness error of both itself and said created multifilm to reduce the reflectivity of the multifilm.
Claim 3
Dependent Claim
37 words
An anti-reflective multifilm of alternate layers of first and second materials with said second material having a higher index of refraction that said first material, on a substrate, and made by the method recited in claim 1.
Claim 4
Dependent Claim
23 words
An anti-reflective multifilm on a substrate as recited in claim 2, wherein said first material is silica and said second material is titania.
Claim 5
Independent Claim
185 words
A method for making an anti-reflective dielectric multifilm, having an outer film of a first material with a known index of refraction and successive layers of materials other than said first material, some of said materials other than said first material with a known index of refraction higher than the index of refraction of said first material on a substrate of known index of refraction comprising: determining the predetermined effective index of refraction for the multifilm, said effective index having a reduce the sensitivity to its thickness errors and being correctable for those thickness errors by reducing the thickness of its outer layer; creating a dielectric multifilm of more than two films on an optical substrate, having the correct ratios of thicknesses of its sub-layers to obtain the above-mentioned effective index of refraction and reduced sensitivity, and the outermost film being of said first material having a thickness greater than its required thickness; and reducing the thickness of said outer film of said created multifilm to compensate for total thickness error of both itself and said created multifilm to reduce the reflectivity of the multifilm.
Claim 6
Independent Claim
185 words
A method for making an anti-reflective dielectric multifilm, having an outer film of a first material with a known index of refraction and successive layers of materials other than said first material, some of said materials other than said first material with a known index of refraction higher than the index of refraction of said first material on a substrate of known index of refraction comprising: determining the predetermined effective index of refraction for the multifilm, said effective index having a reduce the sensitivity to its thickness errors and being correctable for those thickness errors by reducing the thickness of its outer layer; creating a dielectric multifilm of more than two films on an optical substrate, having the correct ratios of thicknesses of its sub-layers to obtain the above-mentioned effective index of refraction and reduced sensitivity, and the outermost film being of said first material having a thickness greater than its required thickness; and reducing the thickness of said outer film of said created multifilm to compensate for total thickness error of both itself and said created multifilm to reduce the reflectivity of the multifilm.
Claim 7
Dependent Claim
36 words
An anti-reflective multifilm of a first material and of at least a second material having a higher index of refraction than said first material, on a substrate, and made by the method recited in claim 4.
Claim 8
Dependent Claim
23 words
An anti-reflective multifilm on a substrate, as recited in claim 5 wherein said first material is silica and said second material is titania.
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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) | 1993-10-29 | 1994-04-30 | 1994-10-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-10-29 | 1998-04-30 | 1998-10-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-10-29 | 2002-04-30 | 2002-10-30 | $7700.00 | Window Closed / Lapsed |