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%$5.56{\% }$ 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.

中文翻译：

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使用基于液晶的相移角剪切干涉仪进行纳米级表面计量

在这封信中，提出了一种结合楔形液晶（LC）单元和偏振移相器的相移角剪切干涉仪，用于光学表面计量（SM）中的应用。这种用于台阶高度测量的角剪切干涉仪的演示是在相移技术的帮助下完成的。由几何移相器产生的四个相移干涉图受到简化的维纳反卷积方法的影响，与其他方法相比，该方法类似于剪切干涉图的简单分析技术。已经进行了模拟研究来验证所提出的技术。实验结果表明，确定台阶高度的准确度为5.56 %$5.56{\% }$，这也与原子力显微镜获得的结果一致。由于双折射的可调谐性，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。