Measurements of Light Scattering by Small Particles at an Angle of Zero Degrees
Final rept. 1 Jul-30 Nov 1992
TEXAS A AND M UNIV COLLEGE STATION DEPT OF PHYSICS
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We recently demonstrated an innovative new idea that permits light scattering measurements at an angle of zero degrees for the first time. The idea is based on the use of coherent beam coupling in a nonlinear, photorefractive crystal of BaTiO3 to separate the scattered light from the unscattered direct beam. The present problem is to extend these ideas to a angular distribution measurements b measurements of the phase as well as the amplitude i.e. both real and imaginary parts of the 0 deg scattering and c determination of the effects of coherent scattering at 0 deg. We have successfully measured the angular distribution of forward light scattering from quartz fibers of radii from 15 mm to 30 mm. Data have been obtained in the angular range of 0 deg to 0. 3 deg with an angular resolution of better than 0.01 deg. The results are in good agreement with theory. Finally, the existence of coherent scattering effects at zero degrees have been considered and analyzed theoretically. Experimental data have been obtained that confirm these coherent scattering affects in suspensions of polystyrene spheres.... Light scattering, Coherent scattering, Photo-refraction.