US3714430A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Photoelement intense radiation protective device
Assignee: United States Department of the Navy
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Filing: 1967-05-19
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Granted: 1973-01-30
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Expires: 1987-05-19
Abstract
Abstract An optical detector protective device for a radiation detecting system consisting of a filter of direct-band-gap emitting semiconductor material, which has an extremely steep absorption edge as compared to indirect band gap materials and a spectral filter for passing desired bandwidth. The absorption edge of the direct-band-gap filter being adjacent its emitting line and positioned such as to pass the desired emission line at ordinary temperatures and attenuate the emission line at elevated temperatures. The device prevents deterioration of the detector in the presence of high intensity light sources in cases where monochromatic or near monochromatic light is employed. The absorption coefficient of the device varies greatly with temperature and wave length.
Inventors
- 👤 R Finyold
- 👤 C Davis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 21:50
CPC Classifications
G; G02; G02B; G02B5/00; G02B5/20; G02B5/22; G02B5/23
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
258 words
In an optical and near optical radiation detecting system including a photodetecting element and optical means for focusing the field of view onto an image plane located in front of the photodetecting element, the imprOvement being a photoelement protective device comprising: a. an optical electromagnetic transmission variable density filter consisting of a thin sheet of material selected from gallium arsenide and an alloy of 50 percent gallium arsenide with 50 percent intrinsic indium arsenide whose attenuation characteristics are a function of the intensity of incident radiant optical and near optical electromagnetic energy, said variable density filter positioned in the image plane of the field of view and covers all the image plane that includes the objective field of view, said variable density filter having an electromagnetic radiation absorption coefficient that varies markedly with temperature from substantially 1 db at cold attenuation to 50 db at hot attenuation when the filter is heated by high intensity electromagnetic energy focused thereon from the field of view, b. a spectral filter of desired bandwidth positioned adjacent said variable density filter, said variable density and spectral filters protecting the photodetecting element from being damaged by high intensity electromagnetic radiation encountered in the field of view, c. said variable density filter consisting of a direct-band-gap emitting-semiconductor material having an extremely steep absorption edge which is adjacent to its emitting line and which is positioned to pass a desired emission line at ordinary temperature and attenuate the emission line at elevated temperatures, said variable density filter having fast response and high degree of attenuation.
Claim 2
Dependent Claim
258 words
In an optical and near optical radiation detecting system including a photodetecting element and optical means for focusing the field of view onto an image plane located in front of the photodetecting element, the imprOvement being a photoelement protective device comprising: a. an optical electromagnetic transmission variable density filter consisting of a thin sheet of material selected from gallium arsenide and an alloy of 50 percent gallium arsenide with 50 percent intrinsic indium arsenide whose attenuation characteristics are a function of the intensity of incident radiant optical and near optical electromagnetic energy, said variable density filter positioned in the image plane of the field of view and covers all the image plane that includes the objective field of view, said variable density filter having an electromagnetic radiation absorption coefficient that varies markedly with temperature from substantially 1 db at cold attenuation to 50 db at hot attenuation when the filter is heated by high intensity electromagnetic energy focused thereon from the field of view, b. a spectral filter of desired bandwidth positioned adjacent said variable density filter, said variable density and spectral filters protecting the photodetecting element from being damaged by high intensity electromagnetic radiation encountered in the field of view, c. said variable density filter consisting of a direct-band-gap emitting-semiconductor material having an extremely steep absorption edge which is adjacent to its emitting line and which is positioned to pass a desired emission line at ordinary temperature and attenuate the emission line at elevated temperatures, said variable density filter having fast response and high degree of attenuation.
Claim 3
Dependent Claim
258 words
In an optical and near optical radiation detecting system including a photodetecting element and optical means for focusing the field of view onto an image plane located in front of the photodetecting element, the imprOvement being a photoelement protective device comprising: a. an optical electromagnetic transmission variable density filter consisting of a thin sheet of material selected from gallium arsenide and an alloy of 50 percent gallium arsenide with 50 percent intrinsic indium arsenide whose attenuation characteristics are a function of the intensity of incident radiant optical and near optical electromagnetic energy, said variable density filter positioned in the image plane of the field of view and covers all the image plane that includes the objective field of view, said variable density filter having an electromagnetic radiation absorption coefficient that varies markedly with temperature from substantially 1 db at cold attenuation to 50 db at hot attenuation when the filter is heated by high intensity electromagnetic energy focused thereon from the field of view, b. a spectral filter of desired bandwidth positioned adjacent said variable density filter, said variable density and spectral filters protecting the photodetecting element from being damaged by high intensity electromagnetic radiation encountered in the field of view, c. said variable density filter consisting of a direct-band-gap emitting-semiconductor material having an extremely steep absorption edge which is adjacent to its emitting line and which is positioned to pass a desired emission line at ordinary temperature and attenuate the emission line at elevated temperatures, said variable density filter having fast response and high degree of attenuation.
Claim 4
Dependent Claim
258 words
In an optical and near optical radiation detecting system including a photodetecting element and optical means for focusing the field of view onto an image plane located in front of the photodetecting element, the imprOvement being a photoelement protective device comprising: a. an optical electromagnetic transmission variable density filter consisting of a thin sheet of material selected from gallium arsenide and an alloy of 50 percent gallium arsenide with 50 percent intrinsic indium arsenide whose attenuation characteristics are a function of the intensity of incident radiant optical and near optical electromagnetic energy, said variable density filter positioned in the image plane of the field of view and covers all the image plane that includes the objective field of view, said variable density filter having an electromagnetic radiation absorption coefficient that varies markedly with temperature from substantially 1 db at cold attenuation to 50 db at hot attenuation when the filter is heated by high intensity electromagnetic energy focused thereon from the field of view, b. a spectral filter of desired bandwidth positioned adjacent said variable density filter, said variable density and spectral filters protecting the photodetecting element from being damaged by high intensity electromagnetic radiation encountered in the field of view, c. said variable density filter consisting of a direct-band-gap emitting-semiconductor material having an extremely steep absorption edge which is adjacent to its emitting line and which is positioned to pass a desired emission line at ordinary temperature and attenuate the emission line at elevated temperatures, said variable density filter having fast response and high degree of attenuation.
Claim 5
Dependent Claim
21 words
A device as in claim 1 wherein said spectral filter is positioned between said variable density filter and the photodetecting element.
References Cited (Backward Citations)
US3020406A
Cited
US3317848A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-01-30 | 1976-07-31 | 1977-01-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-30 | 1980-07-31 | 1981-01-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-30 | 1984-07-31 | 1985-01-30 | $7700.00 | Window Closed / Lapsed |