Possible Use of Two Laser Beams to Determine Particle-Size Distribution.
HARRY DIAMOND LABS ADELPHI MD
Pagination or Media Count:
A study was made to determine whether particle-size distributions for small diameter aerosols radius or 20 microns such as fog can be determined by a new technique based on resonantly distorting the liquid drops by an oscillating electric field at the drops mechanical vibrational frequencies. This field was transmitted by a linearly polarized CO2 laser of intensity 100 Wsq. cm. amplitude modulated at frequencies between 40,000 and 3,000,000 Hz, which correspond to the fundamental vibration frequencies of drops varying in radius from 21.2 to 1.19 microns. An unmodulated, 2-mW He-Ne laser was beamed along the path of the CO2 radiation, and scattering of this light was observed. The intensity of the He-Ne light scattered from the drops at the resonance frequency should be proportional to the density of the drops in the fog that oscillate at that frequency. A sensitive detection system able to measure ac signals with intensities as low as 10 to the -17th power W collected the scattered He-Ne light.
- Atmospheric Physics