CCD图像法测量晶体光轴方向

Crystal Optic Axis Direction Measurement Based on CCD Image

提出了用CCD摄像机采集晶体锥光干涉图来快速精确测量晶体的光轴方向的方法。转动晶片使光轴的出露点形成圆形轨迹,通过最小二乘法对多个测试点拟合得到圆半径和圆心坐标。利用光轴垂直表面的晶片的锥光干涉图来确定数字图像中的距离与光线入射角的关系,使定标误差减小约一个数量级。分析了系统测量误差,提出了为保证测量精度需要采取的措施。对多片不同光轴取向的铌酸锂晶体进行了测量,误差小于0.1°。

The conoscopic interference figures of crystal are collected by CCD camara in order to measure accurately the direction of the optic axis. Turning wafers and making the melatope form the round track, plenty of measuring points are fit to gain the radius of the circle and the coordinate of the circle center by least squares method. By using the conoscopic interference pattern with optic axis vertical to the wafer surface, the relation can be conformed between the pattern distance and the incident angle. And the calibration error is reduced by about one order of magnitude. After analyzed the systematic measurement error, the measures to improve the measurement precision are proposed. The measurement error is less than 0. 1 for different optic axis direction for the niobate crystals.