Patent US4718765A successfully refreshed from Google Patents.
US4718765A
Expired / Lapsed
US
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Interferometric gas detector
Assignee: Elf Antar France
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Filing: 1985-06-20
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Granted: 1988-01-12
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Expires: 2005-06-20
Abstract
Abstract Selective modulation interferometric detector, intended for specifically detecting and/or identifying at least one gas in a gaseous mixture, especially with the aim of carrying out analysis and/or proportioning operations, the assembly E consists of a first strip L 1 of interferometric quality having plane and parallel faces, of thickness e and index n introducing a displacement Δ=2ne adapted to the gas to be analyzed, this strip L 1 supplying on the detector a brilliant fringe, and a second strip L 2 made of the same material as the first strip L 1 which is slightly prismatic and supplying on the detector average illumination.
Inventors
- 👤 Gerard Fortunato
- 👤 Andre Galais
- 👤 Dominique Laurent
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 18:37
CPC Classifications
G; G01; G01J; G01J3/00; G01J3/28; G01J3/45; G01J3/453
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
239 words
An interferometric gas detector intended for detecting and/or specifically identifying at least one gas in a gaseous mixture, comprising: aligned on a single axis, a light source, an interference filter for isolating a specific absorption band of the at least one gas to be identified, a gas tank, an optical focusing system, an interferometry and modulation assembly, and a detector, said optical system forming an image of said source on said detector through said filter, said tank and said interferometry and modulation assembly, wherein said interferometry and modulation assembly includes: a first plate of a material for supplying a brilliant fringe on said detector, said first plate having planar parallel faces for introducing a path difference Δ=2ne, wherein e is the thickness and n is the index of refraction of said first plate, whereby the absorption band of the at least one gas is equal to an absorption maxima of said first plate, a second plate, in the same plane as said first plate and made of the same material as said first plate, having planar faces that form a prism for supplying an average illumination on said detector, and a rotary modulation disk rotating opposite the planar faces of said first and second plates, said rotary disk having a window for permitting light from said light source to pass through the window wherein the light is alternately passed through said first and second plate as the window rotates.
Claim 2
Dependent Claim
239 words
An interferometric gas detector intended for detecting and/or specifically identifying at least one gas in a gaseous mixture, comprising: aligned on a single axis, a light source, an interference filter for isolating a specific absorption band of the at least one gas to be identified, a gas tank, an optical focusing system, an interferometry and modulation assembly, and a detector, said optical system forming an image of said source on said detector through said filter, said tank and said interferometry and modulation assembly, wherein said interferometry and modulation assembly includes: a first plate of a material for supplying a brilliant fringe on said detector, said first plate having planar parallel faces for introducing a path difference Δ=2ne, wherein e is the thickness and n is the index of refraction of said first plate, whereby the absorption band of the at least one gas is equal to an absorption maxima of said first plate, a second plate, in the same plane as said first plate and made of the same material as said first plate, having planar faces that form a prism for supplying an average illumination on said detector, and a rotary modulation disk rotating opposite the planar faces of said first and second plates, said rotary disk having a window for permitting light from said light source to pass through the window wherein the light is alternately passed through said first and second plate as the window rotates.
Claim 3
Dependent Claim
26 words
A detector according to claim 1, wherein said first and second plates are selected from the group consisting of ZnS, ZnSe, Ge or CaF 2 .
Claim 4
Dependent Claim
23 words
A detector according to claim 1, wherein a heating device is associated with said first plate in order to modify its index n.
References Cited (Backward Citations)
FR2555748A1
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-01-11 | 1991-07-13 | 1992-01-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-01-11 | 1995-07-13 | 1996-01-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-01-11 | 1999-07-13 | 2000-01-12 | $7700.00 | Window Closed / Lapsed |