Radiant energy – Invisible radiant energy responsive electric signalling – Infrared responsive
Patent
1982-09-24
1984-12-18
Howell, Janice A.
Radiant energy
Invisible radiant energy responsive electric signalling
Infrared responsive
250343, G01J 100
Patent
active
044892390
ABSTRACT:
A portable laser system for remote detection of methane gas leaks and concentrations is disclosed. The system transmitter includes first and second lasers, tuned respectively to a wavelength coincident with a strong absorption line of methane and a reference wavelength which is weakly absorbed by methane gas. The lasers are aimed at a topographical target along a system axis and the beams successively interrupted by a chopper wheel.
The system receiver includes a spherical mirror for collecting the reflected laser radiation and focusing the collected radiation through a narrowband optical filter onto an optial detector. The filter is tuned to the wavelength of the two lasers, and rejects background noise to substantially improve the signal-to-noise ratio of the detector. The output of the optical detector is processed by a lock-in detector synchronized to the chopper, and which measures the difference between the first wavelength signal and the reference wavelength signal.
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Gerritsen, H. J., "Methane Gas Detection Using a Laser," published in SME Transactions, Dec., 1966.
Kucerovsky, Z., et al., "Characteristics of a Laser System for Atmospheric Absorption and Air Pollution Experiments," published in the Journal of Applied Meteorology, Dec., 1973, vol. 12, pp. 1387-1392.
Byer, Robert L., et al., "Pollutant Detection by Absorption Using Mie Scattering and Topographical Targest as Retro-Reflectors," published in Applied Optics, Jul., 1973, vol. 12, No. 7, pp. 1496-1505.
Henningsen, T., et al., "Remote Detection of CO by Parametric Tunable Laser," published in Applied Physics Letters, Mar. 1, 1974, vol. 24, No. 5.
Grant William B.
Hinkley, Jr. E. David
Howell Janice A.
Jones Thomas H.
Manning John R.
McCaul Paul F.
The United States of America as represented by the Administrator
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