以光折变晶体硅酸铋(BSO)为记录介质, 构建了基于反射式全息光栅零差干涉振动测量系统。系统中的参考光与被振动信号调制的信号光以反射式记录全息的方式射入BSO晶体, 在晶体内干涉形成反射式动态全息并实时衍射, 通过对信号光的透射光和参考光的衍射光所形成的干涉信号进行解调即可得到所测的振动信号。研究了两入射光束夹角、光强比、晶体晶向等测量条件对系统测量灵敏度的影响, 分析了耦合增益与测量灵敏度的关系。结果表明, 以压电陶瓷(PZT)为被测对象时,系统最高可探测到频率为360 kHz的振动信号。分析显示: 由于反射式全息降低了布拉格光栅的空间周期, 提高了入射晶体的信号光和参考光的耦合效率, 故其测量灵敏度高于透射式全息光栅振动测量系统。

A vibration measurement system based on a reflection holographic grating was built up by using the photorefractive crystal bismuth silicate (BSO) as recording media. The reference beam and the signal beam modulated by a vibration signal were injected into the crystal and to form the reflection dynamic holography, then the diffraction was happened simultaneously. The vibration signal could be obtained by demodulating the interference signal formed by the transmitted signal beam and the diffracted reference beam. The impact of the measurement conditions on the measuring sensitivity was studied which include the convergence angle between the two incident beams, light intensity ratio, and the crystal orientation. The relationship between coupling gain and measuring sensitivity was analyzed. Experimental results indicate that this system can detect the vibration signal with a frequency up to 360 kHz when the piezoelectric ceramic(PZT) is a measuring target. It demonstrates that the measuring sensitivity by the proposed system is higher than that of the vibration measurement system based on the transmission holographic grating, because the reflection holography reduces the space period of Bragg grating and improves the coupling efficiency of the reference and signal beams.