介绍了一种结构简单紧凑、可用于高精度实时相位波前测量的红外点衍射干涉仪，采用类迈克耳孙的光学结构，并结合低通小孔滤波，同时使用窗口傅里叶变换的方法解调单幅离轴载波条纹。与传统波前测量技术相比，所提出的准共光路的光学系统结构有效地抑制了系统像差及外部环境干扰等对测量结果的影响，实现高精度和高分辨率的波前探测。实验结果表明，该方法能够实现高精度的相位测量，且其重复精度达到了纳米量级。

This paper describes the development of a novel infrared point-diffraction interferometer (IPDI), which can be readily applied to real-time quantitative phase measurement. We generate reference wave with the help of Michelson-like unit combined with a low-pass spatial filter, and extract the phase information using windowed Fourier transform algorithm from single off-axis fringes. The arrangement of the proposed setup offers a quasi-common-path geometry, which could significantly minimize the systematic errors. The proposed method of IPDI is effective and sufficient for the dynamic process measurement of small deformation with higher spatial resolution compared with the conventional off-axis scheme. The feasibility of the proposed setup is demonstrated, followed by methods of reconstruction and system calibration. The nanoscale repeatability is achieved in our experiment.