1976 Volume 2 Issue 4 Pages 366-372
The laser Doppler technique for measuring fluid velocity has been investigated and developed by many groups of workers. It has several advantages over the other conventional methods, such as the Pitot tube and hotwire anemometry. By this technique, measurements of instantaneous local velocity components can be performed for fluid flow speeds lying between about 10-3cm/sec and supersonic velocities, without the insertion of a disturbance-producing probe into the fluid. However, the recent commercial instruments are very expensive.
The authors constructed a simple and inexpensive instrument, which comprised He-Ne laser equipment, an optical system and a signal processing system. In this paper, details of the instrument and a few examples of measurements are described.