【摘要】 在理论分析的基础上,对国际上目前广泛采用的干涉法测量光纤布拉格光栅(FBG)传感系统中的光波长移动所存在的相位测量原理误差进行了实验研究,提出了双相位锁相放大器加动态补偿的测量方案。结果表明,直接用锁相放大器测量布拉格波长移动所对应的相位变化时,如果布拉格波长与其相关的锯齿波光程差幅值不相等,将产生准周期性的测量原理误差。假设扫描锯齿波幅值初始偏差为20nm,那么测量原理误差将大到全量程的5%。如果使用双相位锁相放大器测量交变的被测量,误差将减小到全量程的0.4%以内。进一步而言,如果从实时测得的干涉仪输出的畸变载波信号中取出与布拉格波长相对应的周期作为数字锁相放大器的参考周期,就可以消除锯齿波幅值初始偏差的影响,从而将测量原理误差控制在一个可以接受的范围,即大约在全量程的0.1%以内。更多还原

【Abstract】 The phase measurement error in an interferometric wavelength shift measurement scheme, such as that used in in fiber Bragg grating sensors, has been investigated experimentally, with appropriate underpinning analytical theory. It has been shown that when a lock in amplifier is employed to detect the phase shift generated by the Bragg wavelength shift, a pseudo periodical measurement error can be introduced due to the difference between the amplitude of the optical path difference ramp and value of Bragg wavelength. If the initial ramp deviation equals 20 nm, the measurement error may be as large as 5% of the total measurement range. By using a double phase lock in amplifier to measure the AC strain, the measurement error can be decreased to 0.4% of the total measurement range. By using the real time measured period which corresponds to the Bragg wavelength with the distorted carrier signal of the interferometer as the reference period of a digital lock in amplifier, the effect of the initial ramp deviation can be principally avoided, and the measurement error can be kept to an acceptably low level, about 0.1% of the total measurement range.更多还原