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本文详细地讨论了外差干涉仪的两个主要问题 ,即干涉仪的横向定位问题和非线性误差分析及其误差补偿问题。首先 ,提出了一种新颖的解析方法实现干涉仪亚微米级的高精度定位。该方法首先建立了测量光束扫过台阶边缘时测量相位渐变数学模型 ,并讨论了它与激光束分布的关系。文章利用以上数学模型对测量相位数据进行了详细地分析 ,实现了在一般激光束径时 ,干涉仪的定位精度为亚微米量级。另一方面 ,文章详细地分析了共光路干涉仪三个主要误差源。分析结果表明 :由Wollaston棱镜引起的误差主要是二阶误差 ,而由激光束的椭圆偏振化引起的误差为一阶误差。同时我们发现 :金属反射镜的方位误差可以使线偏振光经反射后变为椭圆偏振光 ,该椭圆偏振光具有不正交性和不相等偏心度 ,文章首次详细地分析了这种不正交性和不相等偏心度与反射镜方位误差的关系及其由此产生的非线性误差。最后 ,文章分析了干涉仪的误差补偿措施以提高整个干涉仪的测量精度。
In this paper, two main problems of heterodyne interferometer are discussed in detail, namely, the transverse positioning and nonlinear error of the interferometer and its error compensation. First of all, a novel analytical method is proposed to achieve high-precision sub-micron interferometer positioning. In this method, a mathematical model of phase change is established when the measuring beam sweeps over the edge of the step, and its relation with the laser beam distribution is discussed. The article uses the above mathematical model to carry on the detailed analysis to the measurement phase data, realizes in the general laser beam diameter, the interferometer localization precision is on the order of submicron. On the other hand, the article analyzes the three main error sources of the common optical interferometer in detail. The analysis results show that the error caused by the Wollaston prism is mainly the second-order error, and the error caused by the elliptical polarization of the laser beam is the first-order error. At the same time, we find that the azimuth error of the metal reflector can make the linearly polarized light become elliptically polarized light after being reflected, and the elliptically polarized light has the non-orthogonality and the unequal eccentricity. The article first analyzes in detail this non-orthogonal The Relationship Between Sexual and Unequal Eccentricity and Mirror Azimuth Errors and the Nonlinear Error Caused by It. Finally, the article analyzes the error compensation of the interferometer to improve the measurement accuracy of the whole interferometer.