Chatterjee Amit, Singh Puneet, Dhanotia Jitendra, Bhatia Vimal, Prakash Shashi
Appl Opt. 2020 Apr 1;59(10):3227-3236. doi: 10.1364/AO.385797.
Phase-shifting techniques are one of the most promising strategies to extract the phase information and retrieve the parameters of interest (e.g., refractive index, beam collimation, object shape, deformations, thickness, focal length, etc.) from interferograms. However, traditional phase-shifting techniques suffer from both internal and external noise, which reduce measurement accuracy. This paper reports a comparative analysis of the three commonly used filtering techniques, namely, Fourier, windowed Fourier, and wavelet filtering for noise reduction and accurate extraction of phase information from phase-shifted interferograms. Toward this, two basic types of noise (additive and multiplicative noise) are introduced in the simulated interferograms and processed using the pre-filtering strategies. The effect of second-order harmonics in the presence of noise is also examined. In addition, experimental demonstrations of the real-life applicability of the analyses are provided using the interferograms recorded on coherent (Talbot) and incoherent (Lau) grating shearing interferometers. High accuracy in the measurement of defocusing error of the lens is obtained using the filtering strategies. Further inferences and insights are drawn in favor of the pre-filtering techniques.
相移技术是从干涉图中提取相位信息并检索感兴趣参数（例如折射率、光束准直、物体形状、变形、厚度、焦距等）最有前景的策略之一。然而，传统相移技术受到内部和外部噪声的影响，这会降低测量精度。本文报告了三种常用滤波技术（即傅里叶滤波、加窗傅里叶滤波和小波滤波）的比较分析，用于降低噪声并从相移干涉图中准确提取相位信息。为此，在模拟干涉图中引入了两种基本类型的噪声（加性噪声和乘性噪声），并使用预滤波策略进行处理。还研究了噪声存在时二次谐波的影响。此外，使用在相干（塔尔博特）和非相干（劳）光栅剪切干涉仪上记录的干涉图，对分析在实际应用中的适用性进行了实验演示。使用滤波策略在测量透镜散焦误差方面获得了高精度。进一步得出了有利于预滤波技术的推断和见解。
