Patent EP0203767A2 successfully refreshed from Google Patents.
EP0203767A2
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EP
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Improved automated acousto-optic infra-red analyzer system for monotoring stack emissions
Assignee: Rosemount Inc
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Filing: 1986-05-19
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Granted: —
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Expires: 2006-05-19
Abstract
Abstract @ An automated acousto-optic analyzer system provided with an acousto-optic tunable filter coupled with a source of radiation to produce pulsed light at predetermined wavelengths. This light is transmitted through a gas stack to a distant detector. The tunable filter, radiation source on one side and a detector on the opposite side of an environment produces spatial separation of the tuned, diffracted light from the undiffracted broad spectrum of the light source at the detector. Eliminates polarizers in the system. It combines the tuning function of the AOTF with a chopping function, allowing extraneous radiation to be discriminated against.
Inventors
- 👤 Frederick Merk Ryan
- 👤 Robert Leonard Nelson
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 12:08
CPC Classifications
G; G01; G01J; G01J3/00; G01J3/12; G01J3/1256; G01J3/28; G01J3/42; G01N; G01N21/00; G01N21/17; G01N21/47; G01N21/49; G01N21/53; G01N21/534; G01N2021/536; G01N21/25; G01N21/31; G01N21/35; G01N21/3504
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
346 words
A broad-band automated acousto-optic tunable filter multi-gas infra-red analyzer system comprising means for directing infra-red radiation through an environment of interest containing species to be analyzed, an acousto-optic tunable filter with an optically aligned acousto-optic crystal through which the infra-red radiation is passed at a predetermined angle relative to the crystal optic axis, an acoustic transducer means coupled to a variable frequency RF energy source and to the acousto-optic crystal to launch acoustic waves in the crystal to interact with a selected narrow bandwidth portion of the radiation to make it distinguishable from the remaining infrared radiation, which selected narrow bandwidth portion is a function of the frequency of the RF energy and acoustic waves, said selected narrow bandwidth portion being angularly displaced with respect to the non-selected infra-red radiation passed through said acousto-optic tunable filter, means for directing the infra-red radiation upon said acousto-optic tunable filter prior to modification of the infra-red radiation by the absorption characteristics of a given species within the environment of interest characterized by infra-red radiation detection means which detects the angularly displaced, selected narrow bandwidth portion of the infra-red radiation after the angularly displaced selected narrow bandwidth portion has passed through the environment of interest, which detection means generates an output electrical signal as a function of the detected radiation, said detection means being disposed in relation to said acousto-optic tunable filter so that the angular displacement of the selected narrow bandwidth portion is adequate to separate it spatially from the broad-band non-selected radiation at said detection means, and computing means to which the detection means output electrical signal is applied for determining the species present in the sample cell, including means for the pulsed operation of the RF energy source to determine the timing and frequency of RF energy applied to the acoustic transducer mated to the acousto-optic crystal to determine the infra-red wavelength selectivity or tuning of the acousto-optic tunable filter, whereby the pulsed operation permits discrimination by said detection means between pulsed emission means of the selected narrow bandwidth portion and emissions from the environment of interest.
Claim 2
Dependent Claim
346 words
A broad-band automated acousto-optic tunable filter multi-gas infra-red analyzer system comprising means for directing infra-red radiation through an environment of interest containing species to be analyzed, an acousto-optic tunable filter with an optically aligned acousto-optic crystal through which the infra-red radiation is passed at a predetermined angle relative to the crystal optic axis, an acoustic transducer means coupled to a variable frequency RF energy source and to the acousto-optic crystal to launch acoustic waves in the crystal to interact with a selected narrow bandwidth portion of the radiation to make it distinguishable from the remaining infrared radiation, which selected narrow bandwidth portion is a function of the frequency of the RF energy and acoustic waves, said selected narrow bandwidth portion being angularly displaced with respect to the non-selected infra-red radiation passed through said acousto-optic tunable filter, means for directing the infra-red radiation upon said acousto-optic tunable filter prior to modification of the infra-red radiation by the absorption characteristics of a given species within the environment of interest characterized by infra-red radiation detection means which detects the angularly displaced, selected narrow bandwidth portion of the infra-red radiation after the angularly displaced selected narrow bandwidth portion has passed through the environment of interest, which detection means generates an output electrical signal as a function of the detected radiation, said detection means being disposed in relation to said acousto-optic tunable filter so that the angular displacement of the selected narrow bandwidth portion is adequate to separate it spatially from the broad-band non-selected radiation at said detection means, and computing means to which the detection means output electrical signal is applied for determining the species present in the sample cell, including means for the pulsed operation of the RF energy source to determine the timing and frequency of RF energy applied to the acoustic transducer mated to the acousto-optic crystal to determine the infra-red wavelength selectivity or tuning of the acousto-optic tunable filter, whereby the pulsed operation permits discrimination by said detection means between pulsed emission means of the selected narrow bandwidth portion and emissions from the environment of interest.
Claim 3
Dependent Claim
104 words
An analyzer system as claimed in claim 1 wherein the computing means includes a microprocessor and memory means for comparing the detected signal to predetermined molecular species indicative signals stored in the memory means, and in which the memory means provides a predetermined sequence of signals which are applied to the microprocessor to be applied to a frequency synthesizer to vary the frequency of the RF energy applied to the transducer means coupled to the acousto-optic crystal to vary the selection of the narrow bandwidth portion of the infra-red radiation which is analyzed, and predetermined frequencies corresponding to predetermined molecular sample species are applied.
Claim 4
Dependent Claim
93 words
An analyzer system as claimed in claim 1 or 2 wherein the RF energy source includes an RF energy frequency synthesizer coupled by electronic signal gate means amplifier which is connected to the acoustic transducer, and the computing means includes the microprocessor and memory means for applying sequential pulsed control signals to the RF frequency synthesizer to predeterminedly vary the frequency of the RF energy applied to the acousto-optic tunable filter, and control signals are applied to the electronic signal gate means to provide pulse width modulated RF energy to the RF amplifier.
Claim 5
Dependent Claim
23 words
An analyzer system as claimed in any one of claims 1 to 3 wherein the optically aligned acousto-optic crystal is a thallium-arsenic-selenide crystal.
Claim 6
Dependent Claim
76 words
An analyzer system as claimed in claim 4 characterized in that the crystal through which the infra- red radiation is passed is at a predetermined angle relative to the crystal optic axis, an acoustic transducer means coupled to a variable frequency RF energy source and to the acousto-optic crystal to launch acoustic waves in the crystal to interact with a selected narrow bandwidth portion of the radiation to make it distinguishable from the remaining infrared radiation.
References Cited (Backward Citations)
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