基于BSO晶体的振动测量系统

利用光折变晶体材料,可实现宽带、微小振动测量。测量系统采用零差干涉结构,使用硅酸铋(BSO)晶体记录信号光与参考光干涉所形成的动态全息,并实时衍射,再由光电探测器探测从BSO晶体出射的透射信号光与衍射参考光所形成的干涉信号,从而实现对振动的测量。通过对BSO晶体中全息记录条件,包括两光束夹角、光强比,与衍射效率关系的研究,确定了最佳记录条件。在参考光路中利用1/4波片改变光束偏振态,使干涉系统在BSO晶体不加外电场情况下,具有较高测量灵敏度。以一定频率驱动的压电陶瓷为被测物体,在0.5～90kHz的频率范围内所测量到的振动频率与预先加载的频率一致。

Vibration Measurement System Based on the Crystal BSO

A high-frequency mirco-vibration measurement system based on the photorefractive crystal is presented. The homodyne interferometer configuration is adopted and the crystal Bi12SiO20 (BSO) is used to record the dynamic holographic signal formed by the interference of the signal beam and the reference beam. Simultaneously, the diffracted reference beam is generated and interferes on the photodetector with the partial signal beam transmitted directly through the crystal. Time-based signals of photocurrent which is proportional to the vibration displacement are obtained. The factors that affect diffraction efficiency have been investigated such as intensity ratio of the reference beam and the signal beam, the angle between the above two beams. Another quarter-wave plate is used in the reference beam path to improve the measuring sensitivity without electric field on the crystal. A piezoelectric ceramic is used as the target and the detected frequency by this system exactly corresponds to the predetermined frequency from 0.5 kHz to 90 kHz.