Research On Frequency Conversion Fiber Interferometric Velocity Measurement Technology Based On XGM-SOA

With the rapid development of modern military and technology,more advanced speed measurement technology is urgently needed in the field of high speed and ultra-high-speed measurement.Laser interferometric high precision velocimetry technology not only has the advantages of non-contact velocimetry,but also has the characteristics of high temporal resolution and high spatial resolution.After years of development and research,it has been widely used,which is one of the major advances in measurement technology in recent years.It is of great significance for the production,development and research of high-speed moving objects to study the method suitable for measuring ultra-high-speed moving objects and to solve the problem of speed measurement and continuous tracking based on the severe environment such as large impact,high vibration and strong electromagnetic.All-fiber laser interferometry technology has been gradually mature,but in the field of highspeed measurement due to the bandwidth of photodetector,the overall speed measurement limit is still limited.Therefore,this thesis proposes a rotating frequency optical fiber interference velocimetry system based on cross gain modulation-acoustooptic modulation(XGM-SOA).In this thesis,the new system is comprehensively analyzed and discussed from the aspects of detailed optical path construction,optical path simulation,optical path device selection,speed signal analysis and so on.And through many experiments,the feasibility,stability and accuracy of the designed system are verified.This thesis focuses on the new system design,light source selection,lens design,signal processing ridge extraction and other aspects of in-depth analysis and demonstration.After many simulations and experiments,the conclusion shows that the system designed in this thesis is very suitable for the speed measurement of various fields and levels and the effect is good.The details are as follows:(1)To solve the problem that the general optical fiber interferometry technology is limited by the bandwidth of photoelectric detector and cannot increase the upper limit of measurement,an optical structure based on XGM-SOA switching frequency fiber interferometry is proposed,which integrates the traditional laser interferometry system and the reduced frequency measurement system,and the speed is combined to realize the full range measurement of low speed and high speed according to the time node.The upper limit of traditional laser interferometry is increased to 1.5 times.At the same time,the feasibility of the system is verified theoretically and practically through the simulation of the system and the measurement of the actual projectile velocity,and it is proved that it can reduce the bandwidth response of the system on the basis of measuring the full speed,which is more suitable for the acquisition of high-speed signals.(2)Due to the limitation of complex measurement environment,the system will be interfered by a lot of noise signals.In order to improve the noise suppression ability of the system,it can better complete the velocity inversion of the moving target.The structure of the optical fiber probe is optimized and improved,and the receiving form of 2*2 array is constructed.The data collected by different probes are correlated with each other,and the signal-to-noise ratio of the system is improved by differential compensation.Simulation and experiment show that this algorithm has a good effect in suppressing the noise interference in the process of photon Doppler velocity measurement.(3)In order to solve the problem of frequency mutation(frequency selection error)in the whole process of large stroke velocity measurement by using MMFE algorithm,this thesis proposed a ridge extraction correction algorithm(RECA).The problems such as frequency selection error in the continuous measurement of large stroke velocity such as the motion of gun automata or the frequency selection jump in the measurement of non-stationary signal are solved,so that the continuity of velocity is better and the accuracy of displacement and acceleration is higher.Through the improvement of the existing laser interference velocimetry technology,the speed measurement system based on XGM-SOA rotating fiber optic interferometry has a higher speed limit,better noise suppression ability and more accurate velocity curve extraction scheme,which is especially suitable for high speed,high pressure,high explosion and other complex environment velocimetry.