Dhanotia Jitendra, Bhatia Vimal, Prakash Shashi
Appl Opt. 2017 Mar 10;56(8):2346-2352. doi: 10.1364/AO.56.002346.
In this paper, we demonstrate a simple automated procedure for the detection of collimation of an optical beam by incorporating the windowed Fourier fringe analysis technique into a deflectometric setup. The experimental arrangement consists of a deflectometry-based system in which light from a laser is expanded and passed through a collimating lens. The transmitted light illuminates a coarse sinusoidal grating. The grating image is directly captured through a charge-coupled device. Typical image patterns corresponding to "in-focus," "at-focus," and "out-of-focus" positions of an optical beam are recorded. Depending on the position of the collimating lens, the grating line spacing and the resulting phase of the emerging wavefront varies. Direct phase measurement using the windowed Fourier transform method has been used to obtain the slope map of the wavefront. The slope of the phase map depicts the diverging, collimated, or converging nature of the optical beam. The positioning error of light beam collimation was approximately 1 μm. The experimental arrangement is simple, low cost, and compact. The technique is fully automatic and provides high resolution, high precision, and good sensitivity.
在本文中，我们通过将加窗傅里叶条纹分析技术纳入偏折测量装置，展示了一种用于检测光束准直的简单自动化程序。实验装置由一个基于偏折测量的系统组成，其中来自激光器的光被扩束并通过一个准直透镜。透射光照射一个粗正弦光栅。光栅图像通过电荷耦合器件直接捕获。记录了对应于光束“聚焦前”、“聚焦时”和“聚焦后”位置的典型图像图案。根据准直透镜的位置，光栅线间距和出射波前的相位会发生变化。已使用加窗傅里叶变换方法进行直接相位测量以获得波前的斜率图。相位图的斜率描绘了光束的发散、准直或会聚特性。光束准直的定位误差约为1μm。该实验装置简单、成本低且结构紧凑。该技术是全自动的，具有高分辨率、高精度和良好的灵敏度。
