Spatial Filtering Velocity Measurement System Based On Optical Fiber Array And FPGA

High precision and real-time measurement of velocity of moving target is significant in a variety of situations.Compared with the traditional velocity measurement technology,optical velocity measurement technology has many advantages such as non-contact,strong antiinterference ability,wide measurement range and etc.Spatial Filtering Velocity measurement(SFV)technology is one kind of optical velocity measurement technologies with high precision,stable structure and easy signal-processing.This paper focuses on the study of spatial filtering velocity based on optical fiber array.Firstly several commonly-used velocity measurement technologies are introduced in this paper with some analysis and comparisons.Due to the similarity of signal processing methods,Laser Doppler Velocity measurement technology and Spatial Filtering Velocity measurement technology are highlighted introduced.This paper introduces some kinds of spatial filters.The power spectral density function of the spatial filtering output signal is analyzed.Filtering characteristics of rectangular spatial filter and circular spatial filter are studied.Then it discusses the key parameters that affect the filtering characteristics.The reason why optical fiber array is chosen for spatial filtering in this paper is given.This paper designs spatial filtering velocity measurement system based on optical fiber array.Two parts are included in this system: hardware part and software part.The hardware part is consisted of imaging lens,optical fiber array filter,photoelectric detection circuit,A/D circuit,FPGA,MCU and LCD display.The software part includes A/D control module,signal storage module,signal processing module,result calculation and display module.Finally,through experiments,this paper verifies the functions of photoelectric detection circuit,signal processing module,result calculation and display module.In this part the system is used to measure velocity of moving target.The reasons that affect the measurement accuracy are analyzed.Mainly the errors are caused by optical system,hardware circuit and signal processing algorithm.This system is small and capable of measuring velocity in real time.