Integrated optical units for laser anemometry

Abstract

The design of one- and two-channel optical units is described and their application to optical anemometry explained. These units permit easy operation of an optical anemometer in fringe, Doppler or reference beam modes and with either forward or backward scattering. The alignment procedures are explained and shown to require no special optical knowledge and little time. The units are robust and can be operated in nonlaboratory environments. The two-channel unit permits measurements of two mutually orthogonal instantaneous velocities and their correlation in a manner similar to that achieved with crossed hot wires. Measurements of mean velocity and one component of fluctuating velocity were obtained with each mode of operation of the single channel unit in a fully developed channel flow. The results demonstrate the ease of use of the unit and the considerable potential of the measuring technique.