Research On Optical Transceivers And Phase Demodulation Of High Speed Laser Ranging

At present,the separation data of rocket fairing mainly comes from simulation and experiment on ground,without effective measurement method in the actual environment.With the increasing demand for space exploration,in order to grasp the actual separation state of the rocket fairing,especially of the displacement during the separation of the new fairing.Phase laser ranging is one of the commonly used non-contact measurement methods;calculate the distance by the time the laser travels to and from the target.But,the existing laser range finder has a slow measuring speed and the number of measurements per second dose not exceeds five times,and it is impossible to measure the rapid change process.First,this paper has discussed the theory of phase laser ranging,and deeply studied the optical transceivers design and the phase demodulation method,which lay a theoretical foundation for the subsequent research and design.Comparing with different optical axis transceiver,the same optical axis transceiver has high return light intensity at close range without blind spot.This paper proposes a method of three way beam splitting without diaphragm simplifies the structure and enables beam splitting of the laser.The use of a dereflecting film reduces stray light and improves signal to noise ratio,thereby optimizing measurement accuracy.In order to improve the calculation accuracy of the signal phase,this paper discusses the methods of phase demodulation,and deeply studies the apFFT algorithm.The influence of the signal to noise ratio of the optical signal,the sampling signal frequency and the selection of windows function when signals frequency change on phase demodulation accuracy is analyzed.And an apFFT phase demodulation algorithm suitable for the subject was obtained.Found the relationship between the calculation accuracy and sampling rate.Finally,a Kalman filtering method is proposed to improve the calculation accuracy,and can reduce 36% of error.Through improvement of the calculation accuracy,the requirement for the amount of computation data is reduced,and the average number of iterations is reduced.So,the calculation speed is improved.At last,this paper has tested the two main aspects of the study.Experimental results show that can achieve 50 Hz ranging speed while the apFFT algorithm using 4095 points.Beside,can guarantee that the standard deviation of the distance doses not exceed 1mm with good linearity and repetition,achieving high speed and high precision distance measurement.