On line minicomputer data processing of scanning laser Doppler anemometer signals

A high speed on-line minicomputer data processing system has been developed for the analysis of scanning laser Doppler anemometer signals. Both transient and steady state laminar and turbulent velocity profile measurements can be directly obtained. A compact mechanical laser Doppler anemometer scanning system has been developed which moves the scattering volume of the dual beam mode at a high speed across the test section. Both the rate of scanning and the depth of the scan are controlled by the operator. In the system presented here the maximum scan speed was 0.35 seconds per scan and the maximum depth of the scan was 3 inches. The laser Doppler photodiode signal is filtered and amplified and then processed by a Biomation 805 waveform recorder. Then it is fed directly into a Modcomp II/25 minicomputer for data processing and storage.