电致伸缩系数反映了压电材料本身的固有属性, 是衡量电致伸缩特性的重要参数之一。基于逆压电效应, 准确测量微小长度变化量可实现电致伸缩系数的高精度测量。现有光学测量方法基于直接检测光强分布获取微小长度变化量, 但受光源功率稳定性和环境扰动制约, 测量精度不高。为此, 本文采用多光束激光外差技术融合多普勒振镜正弦调制技术, 加载微小长度变化量于外差信号频率中, 研究测量微小长度变化量的外差信号理论模型及外差信号频率与电致伸缩系数间数学模型, 实现外差信号频率检测取代直接强度检测, 消除光源稳定性与环境扰动影响, 并且采用频率解调可以同时获取多个微小长度变化量, 对这些微小长度变化量加权平均, 最终可以进一步提高电致伸缩系数的测量精度。以此为依据, 通过理论仿真研究待测样品的电致伸缩系数, 结果表明: 该方法的相对测量误差仅为0.28%。与现有技术相比, 测量精度提高了一个数量级。

The electrostriction coefficient can be accurately measured by using small length variation based on inverse piezoelectric effect. The conventional optical measuring method based on direct detection of light intensity distribution to obtain small length variation is restricted by light source power stability and environmental perturbation, and can not reach high measuring accuracy. This paper uses the combination of multi-beam laser heterodyne technique with sinusoidal modulation technique to load small length variation to the heterodyne signal frequency. By researching on the theoretical models of heterodyne signal for measuring small length variation, and the relationship between heterodyne signal frequency and electrostriction coefficient, the direct intensity detection can be replaced by heterodyne signal frequency detection, the effects of light source power stability and environmental perturbation can be removed. Many values of small length variation can be got by using the frequency demodulation simultaneously. Processing these values by weighted-average, can get length variation accurately, and eventually get value of electrostriction coefficient of piezoelectric material by the calculation. The measuring accuracy of electrostriction coefficient can be further improved. Based on this, the theoretical simulation research on electrostriction coefficient of testing sample can be acted, the obtained results show that the relative measurement error of this method is just 0.28%. The measuring accuracy is improved one order of magnitude compared with existing technique.