Patent US6756577B2 successfully refreshed from Google Patents.
US4554448A
Expired / Lapsed
US
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Optical elements
Assignee: Ferranti International PLC
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Filing: 1983-04-25
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Granted: 1985-11-19
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Expires: 2003-04-25
Abstract
Abstract An optical element for location between a source of radiation and a detector (13) includes a first optical surface (10) have a central transmissive area (11) and a surrounding area (12) reflective to radiation from direction of the detector (13). A second optical surface (15) is spaced from the first surface (10) towards the detector (13) and has a central reflective area (16) arranged to reflect radiation passing through area 11 towards the reflective area 12. A transmissive area (18) of the second surface (15) surrounds the central area (16), and is itself surrounded by a reflecting area (17) concentric with the detector (13) and forming a reflective shield for the detector.
Inventors
- 👤 Hillary G. Sillitto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 16:04
CPC Classifications
G; G02; G02B; G02B13/00; G02B13/001; G02B13/008; G01; G01J; G01J5/00; G01J5/02; G01J5/08; G01J5/0801; G01J5/0802; G01J5/0806; G01J5/0808; G01J5/0815; G02B17/00; G02B17/08; G02B17/0856; G02B17/086; G02B19/00; G02B19/0004; G02B19/0019; G02B19/0023; G02B19/0033; G02B19/0076; G02B19/009
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
157 words
An optical element for location between a source of radiation and a detector thereof and arranged to focus radiation passing through an aperture therein on to the detector and to provide a reflective shield for the detector outside said aperture, which includes a first optical surface having a central area transparent to radiation incident thereon and a surrounding area reflective to radiation incident upon it from the direction of the detector, and a second optical surface spaced from the first optical surface towards the detector and having a first central area arranged to reflect radiation passing through the central area of the first surface towards the reflective area of the first surface, a second area surrounding the first area and through which said radiation reflected from the reflective area of the first surface may pass towards the detector, and an outer area reflective towards and concentric with the detector to provide a reflective shield for the detector.
Claim 2
Dependent Claim
157 words
An optical element for location between a source of radiation and a detector thereof and arranged to focus radiation passing through an aperture therein on to the detector and to provide a reflective shield for the detector outside said aperture, which includes a first optical surface having a central area transparent to radiation incident thereon and a surrounding area reflective to radiation incident upon it from the direction of the detector, and a second optical surface spaced from the first optical surface towards the detector and having a first central area arranged to reflect radiation passing through the central area of the first surface towards the reflective area of the first surface, a second area surrounding the first area and through which said radiation reflected from the reflective area of the first surface may pass towards the detector, and an outer area reflective towards and concentric with the detector to provide a reflective shield for the detector.
Claim 3
Dependent Claim
31 words
An optical element as claimed in claim 1 in which the first reflective area of the first optical surface and the central area of the second optical surface are substantially concentric.
Claim 4
Dependent Claim
47 words
An optical element as claimed in claim 1 in which the first and second optical surfaces are the opposing surfaces of a solid body of material transparent to the radiation, the reflecting means being formed by coating the appropriate areas of the body with a radiation-reflecting coating.
Claim 5
Dependent Claim
18 words
An optical element as claimed in claim 3 in which the solid body is made of zinc selenide.
Claim 6
Dependent Claim
17 words
An optical element as claimed in claim 3 in which the solid body is made of germanium.
Claim 7
Dependent Claim
24 words
An optical element as claimed in claim 1 in which the reflecting areas of the first and second optical surfaces comprise separate reflecting surfaces.
Claim 8
Dependent Claim
21 words
An optical element as claimed in claim 6 which includes a filter arranged to pass only radiation of a required wavelength.
Claim 9
Dependent Claim
17 words
An optical element as claimed in claim 7 in which the filter is made of zinc selenide.
Claim 10
Dependent Claim
16 words
An optical element as claimed in claim 7 in which the filter is made of germanium.
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) | 1988-11-18 | 1989-05-20 | 1989-11-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-11-18 | 1993-05-20 | 1993-11-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-11-18 | 1997-05-20 | 1997-11-19 | $7700.00 | Window Closed / Lapsed |