Pant Kamal K, Burada Dali R, Bichra Mohamed, Singh Mahendra P, Ghosh Amitava, Khan Gufran S, Sinzinger Stefan, Shakher Chandra
Appl Opt. 2015 Dec 1;54(34):10022-8. doi: 10.1364/AO.54.010022.
A method based on subaperture stitching for measurement of a freeform wavefront is proposed and applied to wavefronts calculated from the slope data acquired using a scanning Shack Hartmann sensor (SHS). The entire wavefront is divided into a number of subapertures with overlapping zones. Each subaperture is measured using the SHS, which is scanned over the entire wavefront. The slope values and thus the phase values of separately measured subapertures cannot be connected directly due to various misalignment errors during the scanning process. The errors lying in the vertical plane, i.e., piston, tilt, and power, are minimized by fitting them in the overlapping zone. The radial and rotational misalignment errors are minimized during registration in the global frame by using active numerical alignment before the stitching process. A mathematical model for a stitching algorithm is developed. Simulation studies are presented based on the mathematical model. The proposed mathematical model is experimentally verified on freeform surfaces of a cubic phase profile.
提出了一种基于子孔径拼接的自由曲面波前测量方法，并将其应用于由扫描夏克-哈特曼传感器（SHS）采集的斜率数据计算得到的波前。整个波前被划分为多个具有重叠区域的子孔径。使用SHS对每个子孔径进行测量，SHS在整个波前上进行扫描。由于扫描过程中存在各种对准误差，单独测量的子孔径的斜率值以及相位值不能直接连接。通过在重叠区域进行拟合，将垂直平面内的误差，即活塞误差、倾斜误差和光焦度误差减至最小。在拼接过程之前，通过使用主动数值对准，在全局坐标系配准期间将径向和旋转对准误差减至最小。开发了一种拼接算法的数学模型。基于该数学模型进行了仿真研究。所提出的数学模型在立方相位轮廓的自由曲面表面上进行了实验验证。
