Patent US4261385A successfully refreshed from Google Patents.
Patent US3861809A successfully refreshed from Google Patents.
US3861809A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Confocal cavity optical gas sensor
Assignee: Raytheon Co
•
Filing: 1973-04-06
•
Granted: 1975-01-21
•
Expires: 1993-04-06
Abstract
Abstract An optical gas sensor is described wherein a confocal cavity, which contains a gaseous mixture for detection of a particular gas, is exposed to a collimated light beam. The light beam includes wavelengths, which exhibit a particular transmission characteristic upon passage through the particular gas in the cavity. The confocal cavity provides a high multiple of reflections of the light beam to enable the detection of a gas such as carbon monoxide by monitoring the relative change in the transmission of light within the absorption band for carbon monoxide. A significant reduction in the length of the optical sensor is obtained while maintaining sensitive detection of carbon monoxide levels by comparison with the transmission of light wavelengths lying outside the absorption band and being passed through the confocal cavity.
Inventors
- 👤 Jr Joseph F Hall
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 17:57
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/01; G01N21/03; G01N21/031
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
283 words
An apparatus for detecting a particular gas in a gaseous mixture by utilizing light energy of a wavelength tending to be absorbed by the particular gas comprising: a confocal light cavity sized to contain a measurable quantity of the particular gas, said confocal cavity being formed by a pair of opposing reflectors mounted in spaced apart coaxial relation in a housing to define a gas chamber cavity therebetween, said reflectors being partially transmissive and adapted to reflect the major portions of light impinging thereon, the opposing faces of said reflectors being substantially spherical surface segments; light source means for producing a single collimated beam of light that includes light energy in an absorption band of the particular gas and reference light energy effectively outside of said absorption band; said light source means being mounted for directing said beam coaxially through one of the reflectors into said cavity, said light source means and said one reflector being dimensioned so that said beam directed into said cavity fills the major portion of the diameter of the cavity, and said opposing substantially spherical, surface segments being of equal radius of curvature spaced from each other along their common axis a distance equal to twice said radius for a maximum number of reflections of said beam within the cavity; means for introducing said gas into said cavity; means for collecting light energy transmitted out from said cavity through the other of said reflectors; means responsive to the collected light energy for producing a first signal representative of the magnitude of the collected light; and means responsive to said first signal for producing an output signal indicative of the amount of said particular gas within the confocal cavity.
Claim 2
Independent Claim
283 words
An apparatus for detecting a particular gas in a gaseous mixture by utilizing light energy of a wavelength tending to be absorbed by the particular gas comprising: a confocal light cavity sized to contain a measurable quantity of the particular gas, said confocal cavity being formed by a pair of opposing reflectors mounted in spaced apart coaxial relation in a housing to define a gas chamber cavity therebetween, said reflectors being partially transmissive and adapted to reflect the major portions of light impinging thereon, the opposing faces of said reflectors being substantially spherical surface segments; light source means for producing a single collimated beam of light that includes light energy in an absorption band of the particular gas and reference light energy effectively outside of said absorption band; said light source means being mounted for directing said beam coaxially through one of the reflectors into said cavity, said light source means and said one reflector being dimensioned so that said beam directed into said cavity fills the major portion of the diameter of the cavity, and said opposing substantially spherical, surface segments being of equal radius of curvature spaced from each other along their common axis a distance equal to twice said radius for a maximum number of reflections of said beam within the cavity; means for introducing said gas into said cavity; means for collecting light energy transmitted out from said cavity through the other of said reflectors; means responsive to the collected light energy for producing a first signal representative of the magnitude of the collected light; and means responsive to said first signal for producing an output signal indicative of the amount of said particular gas within the confocal cavity.
Claim 3
Dependent Claim
63 words
The apparatus for detecting the particular gas as claimed in claim 1 wherein the collecting means is operatively located to collect light transmitted through the other of said light reflectors; and further including means for driving a gaseous mixture (through the gas inlet port) into the gas chamber cavity to monitor the gaseous mixture for the magnitude of the particular gas mixed therein.
Claim 4
Dependent Claim
75 words
The apparatus for detecting the particular gas as claimed in claim 2 wherein said output signal producing means further includes a filter wheel mounted for rotation between the first signal producing means and the collected light energy, said filter wheel being provided with optical windows formed of material selected to chop the collected light into light within the absorption band of the particular gas and reference light of a wavelength outside of said absorption band.
Claim 5
Dependent Claim
41 words
The apparatus for detecting the particular gas as claimed in claim 3 wherein the gaseous mixture driving means includes a fan and motor driving the fan, said fan being mounted on the filter wheel for common rotational drive by the motor.
Claim 6
Dependent Claim
80 words
The improved optical gas detector as claimed in claim 1 wherein the (confocal cavity is sized to detect the particular gas of carbon monoxide,) light source means is adapted to produce a single collimated beam of light that includes light energy in an absorption band of carbon monoxide and light energy outside said absorption band, and wherein said (gas) first signal producing means includes filter means for passing light in the output beam within the absorption band of carbon monoxide.
Claim 7
Dependent Claim
41 words
The improved optical gas detector as claimed in claim 5 wherein said output signal producing means further includes filter means for passing light in the output beam in a reference band of wavelength lying outside the absorption baNd for carbon monoxide.
References Cited (Backward Citations)
US3089382A
Cited
US3250174A
Cited
US3588496A
Cited
US3704951A
Cited
US3696247A
Cited
US3728540A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-01-20 | 1978-07-22 | 1979-01-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-01-20 | 1982-07-22 | 1983-01-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-01-20 | 1986-07-22 | 1987-01-21 | $7700.00 | Window Closed / Lapsed |