双频激光干涉仪相位差测量系统的设计

Design of phase-difference measuring system of dual-frequency laser interferometer

为了实现双频激光干涉仪相位差的测量,设计了一套双频激光干涉信号处理系统。整个系统包括三个部分:光电接收器、模数转换以及数据处理。光电接收器是将干涉系统的双频激光信号接收并转化成电信号,接收器的设计较好地完成了信号的转化和噪声的抑制,A/D转化电路将接收器输出的模拟信号转换成数字序列。数据处理以两重相关方法为理论基础,将测量系统的参考信号移相90°后得到另一路参考信号,再将测量信号分别与两路参考信号作相关运算,使用FPGA完成硬件实现,最后通过数据计算得出相位差信息。

In order to measure the phase-difference of dual-frequency laser interferometer, a unit of feasible measurement system for dual-frequency laser interferometer is illustrated. The whole system include three parts： photoelectric receiver, modulus conversion and data processing. The photoelectric receiver is used to receive and transform the optical signal of dual-frequency laser from interferometer system to electrical signal, the designed photoelectric receiver is good at signal transforming and noise controlling. The modulus conversion circuit transform the analog signal from photoelectric receiver to digital sequence. The data processing uses double correlation algorithm as theoretical basis, get the other reference signal from shifting the phase of the reference signal of the measuring system 90 degrees, then do correlation operation between measurement signal and the two way of reference signals respectively, using FPGA complete hardware realization. At last, it gets the phase-difference from data computation.