Evaluation of LDV performance using Mie scattering theory.

A computer code has been developed to evaluate the performance parameters of a general fringe mode LDV, including Doppler signal strength, pedestal signal strength, and signal-to-shot noise ratio, using the Mie scattering theory for spherical scattering particles. The variable parameters in the program are the particle size and refractive index, the laser wavelength, the refractive index of the fluid surrounding the particle, the geometry of the illuminating beams, the direction of observation of the scattered light and the size and shape of the light receiving aperture. Results are presented in the form of global maps of the SNR for all angles of observation, and expanded maps of the SNR as a function of position on a symmetrically located back scatter light receiving aperture. In addition, the effects of receiving aperture design have been investigated by calculating the total light flux through various shaped apertures as a function of aperture size. (A)