Bag Debasish, Chakraborty Susanta, Sinha Aloka
Opt Lett. 2024 Apr 1;49(7):1705-1708. doi: 10.1364/OL.514441.
In this Letter, a phase-shifting angular shearing interferometer has been proposed for the application in optical surface metrology (SM) by using a combination of a wedge-shaped liquid crystal (LC) cell and a polarization phase shifter. The demonstration of this angular shearing interferometer for step height measurement is accomplished with the help of a phase-shifting technique. Four phase-shifted interferograms produced by a geometrical phase shifter are subjected to a simplified Wiener deconvolution method, which resembles a simple analysis technique for shearing interferograms in comparison to alternative approaches. A simulation study has been conducted to validate the proposed technique. The experimental results show an accuracy of 5.56 for determining the step height, which also agrees with the results obtained by atomic force microscopy. Owing to the tunability of birefringence, the proposed LC-based angular shearing interferometry technique will be useful to control spatial resolution in optical metrology.
在本信函中，通过结合楔形液晶（LC）盒和偏振相位调制器，提出了一种用于光学表面计量（SM）应用的相移角剪切干涉仪。借助相移技术实现了该角剪切干涉仪用于台阶高度测量的演示。由几何相位调制器产生的四幅相移干涉图采用了一种简化的维纳去卷积方法，与其他方法相比，该方法类似于一种用于剪切干涉图的简单分析技术。进行了模拟研究以验证所提出的技术。实验结果表明，确定台阶高度的精度为5.56，这也与原子力显微镜获得的结果一致。由于双折射的可调性，所提出的基于液晶的角剪切干涉测量技术将有助于控制光学计量中的空间分辨率。
