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Title: Optical monitor for water vapor concentration

Abstract

A system for measuring and monitoring water vapor concentration in a sample uses as a light source an argon discharge lamp, which inherently emits light with a spectral line that is close to a water vapor absorption line. In a preferred embodiment, the argon line is split by a magnetic field parallel to the direction of light propagation from the lamp into sets of components of downshifted and upshifted frequencies of approximately 1575 Gauss. The downshifted components are centered on a water vapor absorption line and are thus readily absorbed by water vapor in the sample; the upshifted components are moved away from that absorption line and are minimally absorbed. A polarization modulator alternately selects the upshifted components or downshifted components and passes the selected components to the sample. After transmission through the sample, the transmitted intensity of a component of the argon line varies as a result of absorption by the water vapor. The system then determines the concentration of water vapor in the sample based on differences in the transmitted intensity between the two sets of components. In alternative embodiments alternate selection of sets of components is achieved by selectively reversing the polarity of the magnetic field ormore » by selectively supplying the magnetic field to the emitting plasma.« less

Inventors:
 [1]
  1. (Acton, MA)
Issue Date:
Research Org.:
Aerodyne Research, Inc. (Billerica, MA)
OSTI Identifier:
871600
Patent Number(s):
5760895
Assignee:
Aerodyne Research, Inc. (Billerica, MA) CHO
DOE Contract Number:  
FG02-95ER81915
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
optical; monitor; water; vapor; concentration; measuring; monitoring; sample; light; source; argon; discharge; lamp; inherently; emits; spectral; line; close; absorption; preferred; embodiment; split; magnetic; field; parallel; direction; propagation; sets; components; downshifted; upshifted; frequencies; approximately; 1575; gauss; centered; readily; absorbed; moved; minimally; polarization; modulator; alternately; selects; passes; selected; transmission; transmitted; intensity; component; varies; result; determines; based; differences; alternative; embodiments; alternate; selection; achieved; selectively; reversing; polarity; supplying; emitting; plasma; emits light; alternative embodiments; selectively supplying; spectral line; discharge lamp; water vapor; light source; magnetic field; preferred embodiment; alternative embodiment; transmitted intensity; absorption line; vapor concentration; optical monitor; selected components; monitoring water; light propagation; line varies; inherently emits; selected component; polarization modulator; argon discharge; /356/250/

Citation Formats

Kebabian, Paul. Optical monitor for water vapor concentration. United States: N. p., 1998. Web.
Kebabian, Paul. Optical monitor for water vapor concentration. United States.
Kebabian, Paul. Thu . "Optical monitor for water vapor concentration". United States. https://www.osti.gov/servlets/purl/871600.
@article{osti_871600,
title = {Optical monitor for water vapor concentration},
author = {Kebabian, Paul},
abstractNote = {A system for measuring and monitoring water vapor concentration in a sample uses as a light source an argon discharge lamp, which inherently emits light with a spectral line that is close to a water vapor absorption line. In a preferred embodiment, the argon line is split by a magnetic field parallel to the direction of light propagation from the lamp into sets of components of downshifted and upshifted frequencies of approximately 1575 Gauss. The downshifted components are centered on a water vapor absorption line and are thus readily absorbed by water vapor in the sample; the upshifted components are moved away from that absorption line and are minimally absorbed. A polarization modulator alternately selects the upshifted components or downshifted components and passes the selected components to the sample. After transmission through the sample, the transmitted intensity of a component of the argon line varies as a result of absorption by the water vapor. The system then determines the concentration of water vapor in the sample based on differences in the transmitted intensity between the two sets of components. In alternative embodiments alternate selection of sets of components is achieved by selectively reversing the polarity of the magnetic field or by selectively supplying the magnetic field to the emitting plasma.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1998},
month = {1}
}

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