Optical oxygen concentration monitor

Patent · Tue Dec 31 23:00:00 EST 1996

OSTI ID:871064

Kebabian, Paul ^[1]

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1. Acton, MA

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 the magnetic field or by selectively supplying the magnetic field to either the emitting plasma of the lamp or the environment of interest.

• Research Organization: Aerodyne Research, Inc., Billerica, MA (United States)
• DOE Contract Number: FG02-93ER81522
• Assignee: Aerodyne Research (Billerica, MA)
• Patent Number(s): US 5650845
• OSTI ID: 871064
• Country of Publication: United States
• Language: English

Related Subjects

/356/250/
2000
a-band
absorbed
absorption
absorption line
achieved
alternately
alternative
alternative embodiment
alternative embodiments
approximately
argon
argon discharge
based
centered
changes
close
components
concentration
concentration monitor
determines
differential
differential absorption
discharge
discharge lamp
downshifted
embodiment
embodiments
emits
emits light
emitting
environment
field
flux
gauss
inherently
inherently emits
lamp
light
light propagation
light source
line
line varies
lines
magnetic
magnetic field
measuring
minimally
modulation
modulator
monitor
monitoring
moved
optical
oxygen
oxygen concentration
parallel
passes
path
plasma
polarity
polarization
polarization modulator
preferred
preferred embodiment
propagation
readily
result
reversing
selected
selectively
selectively supplying
selects
set
sets
shorter
shorter wavelength
source
spectral
spectral line
split
supplying
transmission
transmitted
transmitted optical
upshifted
varies
wavelength
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