Abstract

A signal processing algorithm is being developed for use with a commercially available compact LDV system. Due to its size and weight, low power consumption and lack of any need for user calibration of the optics, this system is ideal for making velocity measurements in microgravity fluid and combustion processes where the nature of the experiment environments typically places severe restrictions on the above features. Maximum likelihood based techniques are being investigated in the development of an algorithm that is insensitive to variations in the number of scatterers in the measurement volume and their scattering cross-sections. A significant improvement over existing processors can be achieved by allowing past measurement information to influence the current velocity estimate. This is similar in principle to the way a PLL-based tracking processor operates. The discrete nature of the algorithm makes it applicable both to the classical photodetector signal and the photon- resolved signal arising from low scattered light levels. In addition, the algorithm will be suitable for implementation on a single-chip digital signal processor and the resulting instrument will be of minimal size and weight so as not to negate the advantages gained from using a compact LDV system.

© 1992 Optical Society of America