用剪切干涉仪定焦

由于剪切干涉仪结构简单、使用方便,用它来确定象的位置是很合适的。剪切干涉图中出现的条纹数或者条纹的方向与离焦之间存在着线性关系。当离焦量为零时,干涉图上或者无条纹,或者条纹有确定的方向。文中提出了计算定焦误差的方法,分析了定焦误差与双频光栅的频率差(或剪切量)及系统的F数之间的关系。给出了实验结果和应用的例子。

Determing the Position of Image by Means of Shearing Interferometer

Shearing interferometer in suitable for the determination of the position of image due to its simple structure and easy operation. There is a linear relationship between the shearing fringes appearing inside an interferogram or the direction of the fringes and defocusing. In the interferogram the fringes either do not appear or appear and have the determined direction when the defocusing is zero. The author presents a method of calculating the error of location and analyses the relationship between the error of location and the frequency difference of double-frequency grating (or the amount of shear)and F number of the system. The results of the experiment and the examples of use are also given in this paper.