Investigation Of Improving Phase Demodulation Of Laser Interferometric Based On BSO

With the rapid development of micro-electro-mechanical technology and precision machining technology, the measurement of high-frequency mirco-vibration has become the significant research problem in engineering technology. Optical detection is a non-touch and scatheless measurement technology, it also has the advantage of simple structure, high accuracy and perfect stability, which is by widespread application. In this paper, 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 holography 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.This paper lays emphasis on the research of 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. Simultaneity, analysising other factors on the influence of the diffraction efficiency. Using the reflected light path to enhance the two wave coupling efficiency of signal light and reference one in BOS crystals, or another quarter-wave plate is used in the reference beam path to improve the measuring sensitivity in the condition of non 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 from0.5kHz to50kHz. At last, all the works above are summarized and the emphases in future investigation are also put forward.