Abstract

A two-wavelength absorption/scattering technique has been developed whereby vapor concentrations inside sprays and aerosols can be probed nonintrusively. Two laser beams are overlapped and transmitted through the spray. The wavelengths of the lasers are chosen so that only one laser beam is absorbed by the vapor in question. The other laser beam interacts only with the droplets, and the scattered radiation from this beam is analyzed by a commercial drop sizing instrument which converts the scattering data into a droplet size distribution. Mie theory calculations utilizing this drop size distribution and the measured complex refractive index of the liquid at the two laser wavelengths can then predict the droplet extinction of the vapor probing laser beam. This droplet attenuation of the probe beam is factored out of the total attenuation at the probe wavelength.

© 1981 Optical Society of America