17 Jun 2002
Indian researchers are developing an inexpensive, portable laser-based atmospheric sensor that could help to predict rainfall in polluted areas. This instrument detects atmospheric humidity and its variation at different oxygen levels. It has so far only been tested in a simulation chamber but the researchers hope that it will provide a mobile remote sensing device for air quality monitoring.
The team, from Tezpur University, North Guwahati College and Gauhati University, described the new humidity sensor at the Sixth International Conference on Optics Within the Life Sciences (OWLS VI), which was held last week in Sydney, Australia.
The instrument is based on a HeNe laser. Phototransistors monitor the extinction and scattering when this light is shone through the simulation chamber, or the atmosphere, at different oxygen levels and concentrations of water vapor. The device can be modified and calibrated to record the humidity in the presence of a number of gases, such as industrial effluents. At the moment the device can register a humidity change of approximately 10-6 grams per cubic centimeter.
Gazi Ameen Ahmed of Tezpur University says that the aim of the project was to produce an economical unit. The components for the team's device cost about INR 50,000 (about USD 1100). Ahmed says that more money must be invested in the instrument to increase its sensitivity, but the team hopes that this instrument will provide an attractive alternative to the more common backscattered LIDAR techniques.
SH
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