Research On Target Vibration Drift Error Compensation Of Frequency Modulated Continuous Wave Laser Ranging

Laser ranging technology is the main method for large-scale high-precision measurement because of its high precision and high resolution.The frequency-modulated continuous wave laser ranging technology,as a kind of ranging method that can achieve non-cooperative target ranging and high measurement accuracy,has attracted more and more attention.This technique calculates the target distance by forming a stable beat frequency between the transmitted signal and the echo signal.In this dissertation,the key technologies of the FM continuous wave laser ranging system are studied.The main research contents are as follows:1.This dissertation studies the basic principles of FM continuous wave laser ranging technology,analyzes the main factors affecting the accuracy and resolution of ranging,and proposes corresponding solutions.In addition,the length of the delay fiber used in the experiment was calibrated,and the two fiber calibration methods were compared.According to the experiment,the measurement result of the fiber length calibration method based on the HCN gas absorption cell was more stable.2.This dissertation establishes the model of the influence of target vibration on FMCW laser ranging system,and proposes a compensation scheme of target vibration drift error based on triangular sweep mode.The experimental results show that the method has better compensation effect under low frequency(<6Hz)and low average velocity(<240μm/s).Compared with before vibration error compensation,the maximum standard deviation can be reduced to 1/65 of the original.In addition,the scheme can also be used to measure the speed of the target,and obtain the velocity information of the target while obtaining the distance information.In the laboratory environment,the average vibration velocity of the target is 5.09 μm/s.3.On the basis of in-depth study of the above schemes,a target vibration drift error compensation scheme based on four-wave mixing effect is proposed.The simulation results show that the standard deviation of measurement decreases from1.062 mm before vibration compensation to 29 μm after compensation,and the maximum measurement error is less than 60 μm when the measurement distance is 5m and the target vibration amplitude is 100 μm at 2 Hz frequency.The ranging accuracy is obviously improved compared with that before compensation.