A new analog optical method for data evaluation in laser Doppler anemometry Available to Purchase

In Laser Doppler Anemometry the Doppler frequency of the light scattered by a particle in the flow is proportional to its velocity. In most applications the time needed for a certain number of Doppler cycles is measured by means of a counter. However, utilizing this technique the number of erroneous results will increase if the signal to noise ratio decreases. For such applications a different method may be applied. A transient recorder is used to store the time signal of the Doppler burst. The Fourier transformation of this signal is calculated by means of a digital computer in order to obtain the Doppler frequency.