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US3797942A
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Method and apparatus for analysis by light absorption spectrometry
Assignee: FCI France SA
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Filing: 1972-12-11
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Granted: 1974-03-19
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Expires: 1992-12-11
Abstract
Abstract The invention relates to the analysis of gas by light absorption, suitable for use in analysing the exhaust gasses of automobile engines. The device comprises a tank receiving the gas to be analysed and in which a source sends a beam of light. It comprises at least one interferential filter placed on the path of the beam and at an angle, not of 90* , with this latter, the said filter transmitting the larger portion of the energy of the beam to a detector in a predetermined band of wave lengths and reflecting into the tank the larger portion of the remaining energy in the form of a reflected light beam.
Inventors
- 👤 B Joly
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 12:19
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/25; G01N21/31; G01N21/314; G01J; G01J3/00; G01J3/12; G01J2003/1226; G01N21/35; G01N21/3504
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
141 words
Method of gas analysis by light absorption, wherein a beam of incident light is made to pass into a tank occupied by the gas; the fraction of the beam in a range of predetermined wave lengths is transmitted towards a detector through an interferential filter having a pass band corresponding to an absorption band of a constituent to be detected in the gas; the same filter is used for reflecting the remainder of the beam in an oblique direction with respect to the incident direction and to the interior of the tank, towards at least one other filter having a pass band different from that of the first; and there is diverted towards a detector - which can be the first, used alternately or in differential - the light reflected one or several times by one or more of the filters.
Claim 2
Dependent Claim
141 words
Method of gas analysis by light absorption, wherein a beam of incident light is made to pass into a tank occupied by the gas; the fraction of the beam in a range of predetermined wave lengths is transmitted towards a detector through an interferential filter having a pass band corresponding to an absorption band of a constituent to be detected in the gas; the same filter is used for reflecting the remainder of the beam in an oblique direction with respect to the incident direction and to the interior of the tank, towards at least one other filter having a pass band different from that of the first; and there is diverted towards a detector - which can be the first, used alternately or in differential - the light reflected one or several times by one or more of the filters.
Claim 3
Dependent Claim
88 words
Gas analyser by light absorption, comprising a tank for receiving the gas to be analysed, a source for directing a light beam into the tank, at least one interferential filter placed on the path of the beam and making an angle not of 90* with said filter, the said filter transmitting to a detector the larger portion of the energy of the beam in a predetermined wave length band and reflecting into the tank the larger portion of the energy remaining in the form of a reflected beam.
Claim 4
Dependent Claim
88 words
Gas analyser by light absorption, comprising a tank for receiving the gas to be analysed, a source for directing a light beam into the tank, at least one interferential filter placed on the path of the beam and making an angle not of 90* with said filter, the said filter transmitting to a detector the larger portion of the energy of the beam in a predetermined wave length band and reflecting into the tank the larger portion of the energy remaining in the form of a reflected beam.
Claim 5
Dependent Claim
45 words
Analyser according to claim 2, wherein several filters having different transmission bands are placed successively along the path of the beam, giving to this latter in the tank a path in broken line, in zigzag or convex polygon, in a plane or in different planes.
Claim 6
Dependent Claim
53 words
Analyser according to claim 3, wherein the filters are arranged in such an order that the light in a pass band which is less absorbed by the gas than the light in another pass band has a path within the tank larger than the path of the light in the latter pass band.
Claim 7
Dependent Claim
15 words
Analyser according to claim 2, wherein the tank comprises a nonselective wave length exit window.
Claim 8
Dependent Claim
27 words
Analyser according to claim 2, comprising a single detector and a light distributor which directs the light beams transmitted by the filters towards the detector in alternance.
Claim 9
Dependent Claim
67 words
Analyser according to claim 2, wherein the tank comprises an interferential reference filter having a pass band different from those of the other filters and not corresponding to any of the intense absorption bands of the gas, and a light modulator alternately directs the light leaving the tank through the reference filter and the light leaving the tank through one of the other filters, to the detector.
Claim 10
Dependent Claim
27 words
Analyser according to claim 7, comprising a phase-lock amplifier associated to the detector and receiving a reference signal from the modulator in order to eliminate background noise.
Claim 11
Dependent Claim
52 words
Analyser according to claim 7, including an attenuator placed on the beam transmitted through the exit window, means to adjust the attenuation of said attenuator in order to balance the beams arriving to the detector, and means to measure thE absorption of the attenuator or a parameter which is related to it.
Claim 12
Dependent Claim
23 words
Analyser according to claim 2, wherein the filter or each filter constitutes an exit window from the tank for the corresponding transmitted beam.
References Cited (Backward Citations)
US2941444A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-03-18 | 1977-09-17 | 1978-03-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-18 | 1981-09-17 | 1982-03-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-18 | 1985-09-17 | 1986-03-19 | $7700.00 | Window Closed / Lapsed |