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Title: Optical oxygen concentration monitor

A system for measuring and monitoring the concentration of oxygen uses as a light source an argon discharge lamp, which inherently emits light with a spectral line that is close to one of oxygen's A-band absorption lines. In a preferred embodiment, the argon line is split into sets of components of shorter and longer wavelengths by a magnetic field of approximately 2000 Gauss that is parallel to the light propagation from the lamp. The longer wavelength components are centered on an absorption line of oxygen and thus readily absorbed, and the shorter wavelength components are moved away from that line and minimally absorbed. A polarization modulator alternately selects the set of the longer wavelength, or upshifted, components or the set of the shorter wavelength, or downshifted, components and passes the selected set to an environment of interest. After transmission over a path through that environment, the transmitted optical flux of the argon line varies as a result of the differential absorption. The system then determines the concentration of oxygen in the environment based on the changes in the transmitted optical flux between the two sets of components. In alternative embodiments modulation is achieved by selectively reversing the polarity of themore » magnetic field or by selectively supplying the magnetic field to either the emitting plasma of the lamp or the environment of interest.« less
Inventors:
 [1]
  1. (Acton, MA)
Issue Date:
OSTI Identifier:
871064
Assignee:
Aerodyne Research (Billerica, MA) CHO
Patent Number(s):
US 5650845
Contract Number:
FG02-93ER81522
Research Org:
Aerodyne Research, Inc., Billerica, MA (United States)
Country of Publication:
United States
Language:
English
Subject:
optical; oxygen; concentration; monitor; measuring; monitoring; light; source; argon; discharge; lamp; inherently; emits; spectral; line; close; a-band; absorption; lines; preferred; embodiment; split; sets; components; shorter; wavelengths; magnetic; field; approximately; 2000; gauss; parallel; propagation; wavelength; centered; readily; absorbed; moved; minimally; polarization; modulator; alternately; selects; set; upshifted; downshifted; passes; selected; environment; transmission; path; transmitted; flux; varies; result; differential; determines; based; changes; alternative; embodiments; modulation; achieved; selectively; reversing; polarity; supplying; emitting; plasma; emits light; differential absorption; alternative embodiments; selectively supplying; spectral line; oxygen concentration; discharge lamp; light source; magnetic field; preferred embodiment; alternative embodiment; shorter wavelength; absorption line; transmitted optical; concentration monitor; light propagation; line varies; inherently emits; polarization modulator; argon discharge; /356/250/

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