Research On Multi-channel Signal Synchronization Scheme Of Dual Frequency Laser Interference Signal Phase Board

The phase shift card of dual-frequency laser interference signal has increasingly high requirements for multi-channel signal time synchronization.In order to improve the accuracy and real-time performance of displacement measurement,this paper proposes a real-time measurement algorithm based on dual-orthogonal lock-in amplifier delay phase difference.Through simulation experiments,it can measure the delay phase difference of signals within the range of 4MHz to 36 MHz in real-time,and the real-time measurement accuracy of delay phase difference can reach ±0.0004°.This paper also designs a phase modulation-demodulation delay phase difference realtime compensation algorithm.After using the dual-orthogonal lock-in amplifier delay phase difference real-time measurement algorithm to calculate the delay phase difference between dual-frequency phase shift card signal channels,this algorithm is used to compensate for the delay phase difference between signal channels in real-time.Through electrical simulation calibration experiments,it is shown that the proposed compensation algorithm can reduce the delay difference between dual-frequency phase shift card signal channels within the range of 4MHz to 36 MHz to within 7ps,which is better than the ±0.2ns index of the 4104 series Zygo board.Furthermore,this paper proposes a second compensation algorithm,namely,the phase difference-difference delay phase difference real-time compensation algorithm,which improves the accuracy and stability of the delay phase difference compensation algorithm between signal channels.First,the dual-orthogonal lock-in amplifier delay phase difference real-time measurement algorithm is used to calculate a pair of orthogonal signals containing only delay phase difference between the dual-frequency phase shift card signal channels.Then,the orthogonal signal and the measurement signal before compensation are phasedifferenced to eliminate the delay phase difference between channels.Finally,through electrical simulation calibration experiments,it is shown that using this algorithm for compensation can reduce the delay difference between dual-frequency phase shift card signal channels within the range of 4MHz to 36 MHz to within 3.5ps,which is better than the ±0.2ns index of the 4104 series Zygo board,and also optimizes the first compensation algorithm proposed in this paper.This paper is based on the dual-frequency phase shift card hardware platform,and completes the design of multi-channel signal synchronization digital circuits for dualfrequency phase shift card signals on FPGA.Through experiments,it is demonstrated that the three algorithms proposed in this paper are stable and reliable.