Investigation Of Vibration Measurement System Based On Holographic Grating Of Crystal BSO

With the rapid development of science, technology and society, the measurement of high-frequency, micro vibration is of great significance in scientific research and production. Owning to the characteristic as wave-front matching, low frequency cutoff, broad frequency band, interference vibration measuring instrument using photorefractive crystal is better suited to the measurement of high-frequency, micro vibration than traditional laser interferometer. The basic principle is that signal light beam modulated by vibration signal and reference light beam interfere in the crystal, the dynamic holography is formed, and the diffraction happens simultaneously. The vibration signal appears when demodulating the interference signal received by the detector formed by the transmitted signal beam and the diffracted reference beam.In this paper, traditional laser interferometer is contrasted to that using photorefractive crystal. Dynamic holography process in the photorefractive crystal is analyzed, and diffraction efficiency is derived. Vibration measurement system based on the reflection holographic grating of the crystal BSO is researched systematically. With the measurement principle analyzed, the optical system is built. The impact of measurement conditions, which include convergence angle between two incident beams, light intensity ratio, and crystal orientation, on measuring sensitivity was studied. The relationship between coupling gain and measuring sensitivity was analyzed. It’s indicated that this system could detect the vibration signal which frequency is up to360kHz when measuring piezoelectric ceramic driven by signal generator on the under the optimal conditions. Vibration measurement system based on the reflection holographic grating of the crystal BSO is researched deeply. The signal processing equipment is improved and small piezoelectric ceramics, piezoelectric plate, ultrasonic probe, test block driven by ultrasonic probe are measured, the upper frequency limit which can be detect is1.9MHz,3.0MHz,2.4MHz and1.8MHz.At the end of this paper, the research is summarized and the future work is presented.