Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Patent
1991-03-22
1993-04-13
Hannaher, Constantine
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
250205, 2503385, 250339, 250573, G01N 2159, G01J 342
Patent
active
052025705
ABSTRACT:
A gas detection device employs a tunable wavelength laser, modulated about an absorption line of a gas to be detected. By measuring the ratio of the fundamental to the second harmonic of the modulation frequency, the detection is independent of the optical path length. This permits an aimable device in which a laser beam is directed toward a remote surface, reflected thereby, and the reflected beam focused upon a detector. The presence of the gas to be detected in the space between the device and the reflective surface is thereby determined.
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Patent Abstracts of Japan, vol. 7, No. 174 (E-190), Aug. 2, 1983.
Matsuura Masayuki
Tai Hideo
Tanaka Hiroaki
Uehara Kiyoji
Glick Edward J.
Hannaher Constantine
Tokyo Gas Co. Ltd.
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