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Proceedings Paper

Laser-acoustic hygrometer: procedure and results of field measurements
Author(s): Boris S. Agrovskii; Vladimir Alexeevich Myakinin; Vitaly P. Kukharets
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Paper Abstract

Trail in-the-field measurements of humidity fluctuations are taken by a laser-acoustic hygrometer which involves: a CO-laser, a CO-laser, a mechanical modulator of its radiation, a receiver, an audio-frequency amplifier, and a device for processing signals. The proposed method based on measuring the intensity of sound which is generated when pulse-modulated laser radiation is absorbed in the air. The CO-laser spectrum (5.0-5.7 mkm) is within the fundamental vapor absorption band (5.2-7 mkm). This allows a medium-powered CO-laser to be employed for measurements of humidity fluctuations. Radiation with a pulse recurrence frequency of 16 kHz, which is required for generation of sound waves, is generated by an obturator modulation of the CO-laser continuous radiation. At the point of sound measurement the laser-beam power is about 3 W. An acoustic signal carrying the information on humidity is received by a 1/2 inch microphone installed perpendicular to the beam (d equals 0.5 cm) at a distance of 3 cm from its axis. The spectra of absolute humidity fluctuations over the frequency range (2*10-3 - 10)Hz have been calculated from the obtained realizations for atmospheric conditions when relative humidity ranges between 27 and 47%. Noise characteristics of the laser-acoustic hygrometer have been studied.

Paper Details

Date Published: 20 September 1995
PDF: 4 pages
Proc. SPIE 2506, Air Pollution and Visibility Measurements, (20 September 1995); doi: 10.1117/12.221005
Show Author Affiliations
Boris S. Agrovskii, Institute of Atmospheric Physics (Russia)
Vladimir Alexeevich Myakinin, Institute of Atmospheric Physics (Russia)
Vitaly P. Kukharets, Institute of Atmospheric Physics (Russia)

Published in SPIE Proceedings Vol. 2506:
Air Pollution and Visibility Measurements
Peter Fabian; Volker Klein; Maurus Tacke; Konradin Weber; Christian Werner, Editor(s)

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