Solid Motion Motion Measurement Based On Laser Doppler Principle

Laser Doppler velocimetry is a principle of laser Doppler effect based on the development of the speed measurement device successfully,high measurement precision and dynamic response of the moving object surface without contact,fast and large measurement range and high analysis precision and speed measurement by bad environment restrictions,can measure the speed,can determine the speed of multidimensional the direction of all aspects of the advantages,it is widely used in scientific research and education in the field of industrial measurement field and traffic field,especially in the rolling industrial production can completely replace the traditional velocity measurement method,and improve the quality of steel rolling.This paper firstly introduces the background and significance of laser Doppler velocimetry,and then introduces the basic principle of solid state laser Doppler velocimetry,and construct a solid dual beam laser Doppler velocimeter.It includes the choice of optical path structure,the selection of optical components,the detection of signal and the design of signal processing circuit.The current commonly used method in signal processing is the fast Fourier transform(FFT),but if the FFT obtained after spectral peak estimation as the actual signal Doppler frequency value,instantaneous velocity calculated by the defects of low precision,so it is difficult to meet the demand for high precision measurement,.In this paper,a new method of high precision laser Doppler signal processing is proposed.Firstly,the wavelet transform is used to filter the original signal.After adding the nutall window function,effectively limits the spectrum leakage after fast Fourier transform,using Zoom-FFT on the peak near the band were refined using Nuttall based three spectral line interpolation of spectrum refinement corrected reduced the fence effect and spectrum interference.Using Matlab to simulate the Doppler signal,the signal is verified by the abovemethods.Through the experimental platform,access to the actual laser Doppler signal,and using the method of treatment,the result error is less than 0.2%,through the analysis and comparison of experimental data,verified the feasibility and validity of the method used by the experimental system,the velocity measurement has advantages of real time and accuracy.