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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。
The use of photorefractive crystal material, can achieve broadband, small vibration measurement. The measurement system uses homodyne interference structure. BSO crystal is used to record the dynamic hologram formed by the signal light and the reference light interference and diffract in real time. The photodetector then detects the transmitted signal light and the diffraction reference signal from the BSO crystal Light interference signal formed in order to achieve the measurement of vibration. Through the study of holographic recording conditions in BSO crystal, including the relationship between the angle of two beams, the ratio of light intensity and the diffraction efficiency, the best recording conditions were determined. In the reference light path, the 1/4 wave plate is used to change the polarization state of the beam so that the interference system has higher measurement sensitivity under the condition of no external electric field in the BSO crystal. The piezoelectric ceramic driven at a certain frequency is the measured object, and the vibration frequency measured in the frequency range of 0.5 to 90 kHz is consistent with the pre-loaded frequency.