The Research On Key Technology Of Laser Doppler Velocimeter

Laser is a kind of clean and pollution-free environmental protection process technology in optical communication, atmospheric research, photochemical, medicine and some significant fields in the optical areas. With the continuous development of the laser,laser ranging and laser velocimeter both developed a lot. Laser and digital control systems complement each other, thus the implement of the precision measurement and non-contact measurement is becoming more easier than before.This paper first describes how a laser Doppler velocimetry be produced, and the level of current academic research achievements. It has been applied to the field of science of technology, medical treatment, and industry and so on. And then it extends from Doppler effect of sound waves to the Doppler effect of light wave, it describes three physical model of Doppler signal by graphic description, the three physical model are Coherent beam stripe model,The optical path difference model of Doppler signal,Fix wave graph model, they can analysis how to produce the Doppler signal in the field of physics.Because of the high frequency of light wave, the amplitude frequency and phase of the signal light can’t be detected by optical component,so we usually detect the Doppler frequency shift by choosing optical heterodyne detection technique. And then this paper describes what theoretical the optical heterodyne detection technique is based on. there are three heterodyne optical path model and the most suitable is chosen,that is Double—beam—Double scattering mode of backward direction。And then this paper describes the optical system and the signal processing system in the whole speed measuring system and a photoelectric conversion circuit is designed for the consideration of the photoelectric elements’ parameter and performance.The following this paper introduces the five types of Doppler signal processing methods, after the five methods are contrasted, the FFT is chosen. And we design FIR, and the signal processing hardware system, and implement DSP by using FFT. Finally we set up a experimental platform for the experiment, and used to measure the speed of roller. The experiment proves that the laser Doppler velocimetry can measure the speed of the solid and the result of this measurement is accuracy.