US4590374A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Infra-red light absorption gas detector
Assignee: International Standard Electric Corp
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Filing: 1984-09-28
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Granted: 1986-05-20
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Expires: 2004-09-28
Abstract
Abstract A gas detector arrangement, e.g. for detecting carbon dioxide, includes an infra-red source, a photodetector and band pass filter disposed in the light path therebetween. The arrangement includes means for oscillating the pass-band of the filter across an absorption band edge of the gas to be detected. The arrangement is portable and may be installed in diving apparatus.
Inventors
- 👤 Arthur E. Brewster
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 11:23
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/25; G01N21/31; G01N21/314; G01J; G01J3/00; G01J3/28; G01J3/42; G01J3/433; G01J3/12; G01J2003/1226; G01J2003/1243; G01J2003/4332; G01N21/35; G01N21/3504
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
69 words
An arrangement for detecting and measuring the concentration of a gas having an infra-red absorption band, the arrangement including a light source and photodetector, a multilayer interference filter disposed in the light path between the source and detector and supported on a single crystal silicon substrate, and means for vibrating the filter such that its transmission peak oscillates across the absorption band edge of the gas to be detected.
Claim 2
Dependent Claim
69 words
An arrangement for detecting and measuring the concentration of a gas having an infra-red absorption band, the arrangement including a light source and photodetector, a multilayer interference filter disposed in the light path between the source and detector and supported on a single crystal silicon substrate, and means for vibrating the filter such that its transmission peak oscillates across the absorption band edge of the gas to be detected.
Claim 3
Dependent Claim
26 words
A gas detector arrangement as claimed in claim 1, wherein the substrate is suspended by a pair of integral resilient filaments in a frame support structure.
Claim 4
Dependent Claim
29 words
A gas detector arrangement as claimed in claim 1, and which includes a synchronous detector coupled via an amplifier to the photodetector and locked to the filter vibrational frequency.
Claim 5
Dependent Claim
71 words
A gas detector arrangement as claimed in claim 1, wherein said infra-red band pass interference filter includes an assembly including a laminar infra-red transparent body, a plurality of transparent dielectric layers of substantially equal thickness disposed on at least one surface of the body, and a supporting frame member within which the body is mounted via two or more resilent filaments whereby the body may be oscillated in a torsional mode.
Claim 6
Dependent Claim
27 words
A filter assembly as claimed in claim 4, wherein the body, support frame and filaments are formed by selective etching for a body of single crystal silicon.
References Cited (Backward Citations)
US2834246A
Cited
US3940623A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-05-19 | 1989-11-18 | 1990-05-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-05-19 | 1993-11-18 | 1994-05-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-05-19 | 1997-11-18 | 1998-05-20 | $7700.00 | Window Closed / Lapsed |