标准硅球直径测量中的光路对准

Beam Alignment for Diameter Measurement of the Single Crystal Silicon Sphere

针对标准单晶硅球直径精密测量的需要,本文在介绍标准硅球直径测量系统原理并分析其光路特点的基础上,根据建立的数学模型,对激光束斜入射标准板时产生的椭圆干涉图像进行了分析,并对不同入射角度时干涉环中心点带来的直径测量误差进行了研究。分析结果显示,在给定的实验条件下,当入射角为10-3rad时,误差已达6.6nm。提出了一种精确调整光束垂直入射平板的方法,实验结果表明,此方法能够使光束入射角的调整优于10-5rad,满足系统测量的要求。

According to the requirement of precision diameter measurement of the single crystal silicon sphere, the principle and characteristics of the measuring system were presented, and mathematical models were established for calculating the ellipticity of concentric interference rings with different beam incident angles. Furthermore, the diameter measuring errors of the fringe center were studied in different incident angle situations. It is shown that the error can be up to 6.6 nm when the original distance between inner face of the etalon plate and the adjacent silicon sphere surface equals 13.2 mm, and the incident angle equals 10.3 rad. A novel method was proposed for accurately adjusting incident angle of laser beam relative to the plate. The experimental results show that the incident angle can be less than 10^-5 tad by applying this method.