非单调条纹图的相位恢复新方法

在连续小波变换和展开相位拐点识别的基础上,提出一种非单调条纹图的相位恢复新方法.包裹相位通过连续小波变换的方法提取,提出小波变换尺度步长的选择准则及对粗糙尺度作迭代均值滤波的技术.基于展开相位拐点与符号歧义点的单应性,可通过检测并修正展开相化拐点的方法恢复非单调条纹图的真实相位.给出了详细的理论推导、数值模拟及实验验证过程.数值模拟包括一维及二维的含噪声信号,实验为基于显微干涉法的微桥的静动态形貌和变形测试.模拟及实验结果表明,该法只需一幅条纹图即可准确解调非单调条纹的相位,最大误差小于4%,且具有极强的抗噪能力.这为显微干涉测量提供了有效的相位恢复新手段.

A New Method for Phase Retrieval on Non-Monotonous Fringes

A novel method based on continuous wavelet transform (CWT) and guidance of inflexion points of unwrapped phase is developed to measure the phase of non-monotonous fringes. Wrapped phase values are retrieved by ridge extraction algorithms based on CWT. To increase the resolution of measurement and reduce the noise, the scale incremental step is determined by a proper criterion and the scales detected by maximum ridge algorithm are filtered iteratively before retrieval of wrapped phase. Based on the homography relationship between an inflexion point and an ambiguous point, the real phase values can be retrieved by directly identifying any inflexion point from an unwrapped phase map without the use of a carrier. The proposed method is analyzed theoretically in great details. Furthermore, the algorithm developed is validated by computer simulation, which includes one-dimensional and two-dimensional cases both with and without noise, and an experiment based on micro interferometry. Simulations and experimental results for both static and dynamic shapes and deformations of a micro structure demonstrate that the proposed method is effective for the analysis of a closed fringe pattern and subsequent deformation measurement, which has the capability of high accuracy and good noise reduction with a maximum error less than 4%.