基于F-P腔强度解调的微位移传感器

A Novel Fabry-Pérot Micro-displacement Sensor Based on Intensity Demodulation Method

基于一次谐波腔长锁定技术,设计了一种基于法布里-珀罗(F-P)腔干涉的强度解调型微位移传感器。系统对F-P腔的初始腔长进行动态锁定,通过将F-P腔腔长的微小变化转化为强度信号,实现直接快速地对待测目标的微位移进行测量。详细地阐述了位移传感器的理论模型及一次谐波锁定F-P腔腔长的技术方案,实验中采用商用的高精度压电陶瓷平移台(PZT)模拟了实际物体的运动状态,实验结果表明,该系统对峰峰值在λ/4(λ为光波波长)以内、频率不高于400Hz的微位移有很好的测量结果,频率误差小于0.5Hz,测量精度小于1nm。

According to the first harmonic cavity-length locking technology, a novel kind of micro-displacement sensor, which combines Fabry-Perot （F-P） interferometer and intensity demodulation method, has been developed. The initial length of the F-P cavity has been actively scanned and dynamically locked. And then the change of the F-P cavity-length induced by the motion of the target is coded on the variation of the optical output power of the cavity. As a consequence, a fast and direct micro-displacement sensing scheme through the intensity demodulation is available. The theoretical model of the displacement sensor and the technical scheme for actively locking the initial length of the F-P cavity through the first harmonic have been demonstrated in detail, respectively. Micro- displacement experiments provided by a commercial high-precision PZT with different vibrating parameters have been performed, and the experimental results agree well with the motion of the PZT within peak-to-peak amplitude ofλ/4 and frequency is no more than 400 Hz. The frequency error is less than 0.5 Hz, and the total measurement accuracy is less than 1 nm.