Forward-scatter meter for estimating 10.6-microm aerosol extinction.
A forward-scatter meter (FSM) measures the light scattered from aerosols irradiated by a He-Ne laser beam (0.6328 microm) over a narrow angular range in the forward direction and over a path length of 0.5 m. Comparisons are made between the FSM and visible (0.55-microm) and IR (10.6-microm) transmissometers operating in hazes and fogs containing waterlike aerosol particles with widely varying size distributions. While poor correlation is found between the FSM measurements and the visible transmissometer, the FSM measurements can be scaled to the aerosol extinction coefficient at 10.6 microm with an accuracy of +/-10% at the 90% confidence level.
Gerber
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