Solid Motion Motion Measurement Based On Laser Doppler Principle

Laser doppler velocimeter is developed according to the doppler effect of light and becomes a speed measuring instrument,a non-contact,high accuracy of measurement,can measure small size,large measuring range,fast response speed and direction can be multidimensional measurements and discriminant rate advantages,is widely applied in the field of scientific research and education and to the field of industrial measurement.But laser doppler velocity signal with low signal to noise ratio,weak signal,signal loss and spectrum widening and belongs to the high frequency signal,so how to fast speed,high efficient and accurately extract the useful information is the core of the laser doppler velocimetry.This article first introduced the topic background and significance,the development of the laser doppler velocimetry and research status of laser doppler velocity signal processing,and then introduces the principle of laser doppler velocimetry,and on the basis of the principle,the choice of the optical heterodyne detection double beam-to receive mode after the double scattering light path as the light path layout of this system,finally,the designed system can be divided into three parts,in turn,to select and design,and successfully construct platform for laser doppler velocity in the laboratory.At present,the laser doppler velocity signal processing method mainly USES the fast Fourier transform,fast Fourier transform and FFT),but because of the fast Fourier transform in lost time information,so we can not corresponding to a certain period of time and frequency domain information or a spectrum corresponds to time information analysis;At the same time,the filtering method based on the fast Fourier transform is established,and there is a contradiction between improving the signal-to-noise ratio and improving the spatial resolution.Although low pass filtering can reduce noise by smoothing,it can also make the edge of the signal blur,which is not conducive to identification.High-pass filtering can make the edges more steep,but the noise will be enhanced.Compared with wavelet transform in time domain and frequency domain,hasthe very strong the ability of denoting local signal characteristics,and in terms of filtering,based on wavelet transform multi-resolution filtering technology has obvious advantages,can effectively remove the noise at the same time in the retention time information.Using the wavelet analysis to the simulation signal and the measured doppler radar signal processing,error can be controlled below 0.6%,through the study of the analysis and comparison of experimental data,proved this method is a rapid,accurate method of doppler radar signal processing.