US3976875A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Photodetector filter structure
Assignee: RCA Corp
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Filing: 1975-06-24
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Granted: 1976-08-24
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Expires: 1995-06-24
Abstract
Abstract A transparent dome formed from a segment of a spherical shell of uniform thickness has an optical filter on its surface. A photodetector is positioned on the concave side of the dome so that light rays passing through the dome, normal to its surface, will fall on the center of the photodetector.
Inventors
- 👤 Ralph Warren Engstrom
- 👤 David Eugene Bowser
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 11:23
CPC Classifications
G; G01; G01J; G01J1/00; G01J1/02; G01J1/04; G01J1/0407; G01J1/0488
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
81 words
An optical filter structure for a photodetector comprising: a transparent dome in the shape of a segment of a spherical shell of uniform thickness, said dome positioned in front of the photodetector with a concave surface of the dome facing the photodetector so that light passing through the dome normal to the dome's surface will intersect at the center of the photodetector; an interference filter on the surface of the dome; and an absorption filter between the dome and the photodetector.
Claim 2
Dependent Claim
81 words
An optical filter structure for a photodetector comprising: a transparent dome in the shape of a segment of a spherical shell of uniform thickness, said dome positioned in front of the photodetector with a concave surface of the dome facing the photodetector so that light passing through the dome normal to the dome's surface will intersect at the center of the photodetector; an interference filter on the surface of the dome; and an absorption filter between the dome and the photodetector.
Claim 3
Dependent Claim
18 words
The device as in claim 1 wherein the interference filter is on the concave surface of the dome.
Claim 4
Dependent Claim
27 words
The device as in claim 1 wherein the interference filter is on the concave surface of the dome and the absorption filter is on the interference filter.
Claim 5
Dependent Claim
33 words
The device as in claim 1 including an enclosure having an aperture over which the dome is mounted so that the concave surface of the dome faces inward, the enclosure containing the photodetector.
Claim 6
Dependent Claim
15 words
The device as in claim 1 wherein the absorption filter is on the transparent dome.
Claim 7
Dependent Claim
45 words
The device as in claim 1 wherein the absorption filter comprises a flat absorption filter positioned between the concave surface of the dome and the photodetector so that all of the light passing through the dome and striking the photodetector passes through the absorption filter.
Claim 8
Dependent Claim
16 words
The device as in claim 6 wherein the flat absorption filter is attached to the photodetector.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-08-24 | 1980-02-23 | 1980-08-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-08-24 | 1984-02-23 | 1984-08-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-08-24 | 1988-02-23 | 1988-08-24 | $7700.00 | Window Closed / Lapsed |