一种基于平板横向剪切干涉的角位移测量方法

在一种已有的角位移干涉测量技术的基础上,提出一种改进的角位移测量方法。通过选择合适的初始入射角,使从平板前后表面反射的两光束实现剪切干涉。采用一维位置探测器测量光束经透镜会聚后在探测器光敏面上的光点偏移量。根据干涉信号的相位和光点偏移量可以计算出被测物体的角位移。在该测量方案中,引入的一平面反射镜与被测物体的反射面形成光程差放大系统,提高了角位移测量灵敏度。分析了初始入射角对剪切比的影响,并讨论了基于该方案的角位移测量精度。实验结果表明,基于该技术的角位移重复测量精度达到10-8 rad数量级。

An improved method for measuring angular displacement is proposed based on an existent measurement technique. The choice of proper initial angle of incidence makes a lateral shearing interference easy to realize between the two beams reflected from the front and back surfaces of a plane-parallel plate. One-dimensional position sensitive detector is used to measure the offset of the light spot focused upon the photo sensitive surface of the detector by a lens. According to the interference signal′s phase and light spot′s offset, the angular displacement is measured. In this optical configuration, the use of a reflecting mirror increases the optical path difference in the plane-parallel plate, which improves the sensitivity of angular displacement measurement. Finally, the influence of the initial angle of incidence on the ratio of shear is analyzed and the measurement accuracy based on this method is discussed. The experimental results show the improved parallel plate interferometer can achieve a measurement repeatability of 10-8 rad order of magnitude.