研究了一种复合光纤马赫-曾德尔外差干涉测量系统,并采用该系统对位移进行在线测量。基于光纤光栅只反射布拉格波长的特性,构建了两个独立但光程几乎重合的光纤马赫-曾德尔干涉仪。其中的一个马赫-曾德尔干涉仪用于完成测量工作,另一个马赫-曾德尔干涉仪用于监测环境干扰,补偿环境干扰对测量结果的影响,使测量系统适合用于在线测量。位于马赫-曾德尔干涉仪参考臂的声光调制器组可对参考光进行移频,当参考光与测量光会合时形成外差干涉信号,实现外差干涉测量。实验中,该系统对100 μm位移进行10次重复测量的标准差为6 nm。

A multiplexed optical fiber Mach-Zenhder heterodyne interferometric system which is suitable for on-line displacement measurement is researched. Based on the characteristic that fiber Bragg grating only reflects Bragg wavelength, two independent optical fiber Mach-Zenhder interferometers which possess almost the same optical path are established. One of the optical fiber Mach-Zenhder interferometers is used to perform the measurement task while the other one is used to monitor the environmental disturbances. The system is suitable for on-line measurement after the environmental disturbances are compensated. The acoustic optical modulators embedded in the reference arm of the interferometers shift the frequency of the reference beam, and heterodyne interferometric signals are formed when the reference beam meets the measurement beam, realizing heterodyne interferometric measurement. During the experiments, the standard deviation of 10 repeated measurements for 100 μm displacement is 6 nm.