Effect of absorption on visibility profiles or circularly polarized backscattered laser beam (particle size measurement)

By use of a method based on the laser Doppler anemometry technique and Mie scattering theory, the visibility for a circularly polarized backscattered laser beam is derived and computed. The effect of absorption on the visibility profiles is analyzed. This analysis is made for a fixed real part of the index of refraction of the particles (1.43) and various values of the imaginary part of the index of refraction (5.10/sup -3/, 8.10/sup -3/, 10/sup -2/, 10/sup -1/). It is shown that the technique considered is suitable for particle sizing only when the imaginary part of the index of refraction of the particles is less than or equal to 5*10/sup -3/. For values greater than 5*10/sup -3/ a nonmonotonic relationship exists between the visibility and the size parameter; therefore, the visibility technique in this case is not feasible for particle sizing.<
>