US3737210A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Multilayer filter based on substitution of herpin equivalent layers in a antireflection coating formula
Assignee: Bausch and Lomb Inc
•
Filing: 1972-03-31
•
Granted: 1973-06-05
•
Expires: 1992-03-31
Abstract
Abstract A filter comprises a plurality of thin films of alternating materials arranged in a periodic pattern wherein various symmetrical periods define a stopband and have equivalent indices and thicknesses in the passbands determined by adjusting the ratio q of layer thicknesses within the period, the equivalent indices being chosen to correspond to a known antireflecting coating in the passband, while holding the sum sigma of the effective layer thicknesses constant for each period.
Inventors
- 👤 J Howe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 02:03
CPC Classifications
G; G02; G02B; G02B5/00; G02B5/20; G02B5/28; G02B5/285
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
166 words
An improved multilayer filter for a stopband and a passband comprising a stack of successive thin films on a substrate, said films consisting of one of at least first and second materials of different refractive indices; said films being arranged in periods in each of which an optical thickness phi 2 of said second material is disposed symmetrically between two equal optical thicknesses phi 1 of said first material, said optical thicknesses defining a ratio q 2 phi 1/ phi 2 and a total optical thickness sigma 2 phi , + phi 2 and each said period having an equivalent refractive index N which is a function of q for any sigma ; said periods being arranged in said stack with each period having a value of the ratio q such that its equivalent refractive index N is equal to the refractive index n of the corresponding layer of a predetermined multi-layer antireflection coating and each of said periods having the same value of sigma .
Claim 2
Dependent Claim
166 words
An improved multilayer filter for a stopband and a passband comprising a stack of successive thin films on a substrate, said films consisting of one of at least first and second materials of different refractive indices; said films being arranged in periods in each of which an optical thickness phi 2 of said second material is disposed symmetrically between two equal optical thicknesses phi 1 of said first material, said optical thicknesses defining a ratio q 2 phi 1/ phi 2 and a total optical thickness sigma 2 phi , + phi 2 and each said period having an equivalent refractive index N which is a function of q for any sigma ; said periods being arranged in said stack with each period having a value of the ratio q such that its equivalent refractive index N is equal to the refractive index n of the corresponding layer of a predetermined multi-layer antireflection coating and each of said periods having the same value of sigma .
Claim 3
Dependent Claim
49 words
The filter of claim 1 wherein said predetermined antireflection coating is of the formula n1 n4 n3 Square Root no ns wherein n is the refractive index of each layer and the layers are subnumerated in ascending order from the first massive medium o toward the massive substrate s.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-06-04 | 1976-12-04 | 1977-06-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-04 | 1980-12-04 | 1981-06-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-04 | 1984-12-04 | 1985-06-05 | $7700.00 | Window Closed / Lapsed |