Research On Signal Processing Of Dual Interference FMCW Laser Range Finder System

In the field of industry,the demand for high precision large-scale measurement is growing.The traditional coordinate measurement systems cannot meet the all the requirements of industrial measurement.Commercially available large-scale coordinate measurement system,such as laser tracker,vision measurement system,indoor GPS system etc.has its own shortage.When the measurement is more convenient without the guide to cooperation.But there are still some problems.It is not fully satisfied with extra special measurement requirements.FMCW laser ranging is a type of large size absolute distance measuring technique.It has the advantages of high precision,wide range,no cooperation target and non-contact measurement.It has good application prospect in the field of high precision measurement.The research on FMCW laser ranging system and its signal online processing can make it fit the market demand better.This paper makes a comparative study of several existing methods of laser ranging.FMCW laser range finding method can be used to achieve absolute distance measurement of noncooperative targets.The accuracy of FMCW laser range measurement is higher than that of pulse method and phase method.Compared with interferometry,the advantage is that there is no need for cooperation.Then the research status of FMCW laser ranging and its signal processing algorithms in China and abroad are summarized.In the end,the factors affecting the range precision and resolution of FMCW laser ranging system are analyzed in principle,and the compensation method is put forward.Using the Mach-Zehnder interference system as an auxiliary interference system,the beat signal is employed as the sampling clock to resample the beat signal received by the measurement interference system.The frequency modulation nonlinearity of the tunable laser is eliminated.Using the method of signal splicing to break through the limit of wavelength free mode scanning range of tunable laser.The all phase FFT method and the five-point energy center method are used to improve the spectrum correction and improve the precision of the frequency measurement.Based on the above factors,a dual interferometric FMCW laser range finder system is proposed.The system of online signal processing algorithms is programmed by Lab VIEW software.The methods of signal error identification and error handling,optical frequency interval resampling,signal splicing and spectrum correction are implemented.The whole program and module program are simulated by signal generator.The simulation results show that the program can implement the corresponding functions.The comparison experiment shows that the online signal processing algorithm adopted in this paper can effectively improve the ranging accuracy and ranging resolution of the dual interference FMCW laser ranging system.The range resolution of distance measurement system can reach 60 ?m at the distance of 10 m.The laser interferometer is used for contrast measurement.The experiment shows that the precision of the system is high and the standard deviation is no more than 20 ?m.