Experimental investigation of the angular dependence of laser light scattered in laser-Doppler anemometry

In laser-Doppler anemometry (LDA) the light scattered from small particles is generally observed either in on-axis or sligthly off-axis forward or backscattering mode. The present paper reports on experimental results achieved with a LDA-system, which clearly demonstrates the distinct superiority of the forward scattering mode over backscattering on the bases of scattering diagrams. These diagrams are compared to Mie's theory of the diffraction of electromagnetic waves on dielectric spheres. Good agreement could be found for all the observation angles which are mostly used in LDA-arrangements.