基于物体像的干涉条纹图像中散斑噪声的识别方法

Recognition method of speckle noise in interference fringe images based on object

散斑噪声是激光干涉时的普遍现象,其覆盖被测表面对应区域的形状信息,造成测量误差。针对斜入式激光干涉测量中散斑噪声的特点,提出一种基于物体像的散斑噪声的识别方法。该方法通过统计物体像中有效测量区域和背景区域内灰度分布的特点,自动计算出判定散斑噪声的上下阈值。基于物体像与干涉条纹图像间微米级的映射关系,得到干涉条纹图像中散斑噪声的位置。设计了相关实验,对干涉条纹图像中识别出的散斑噪声区域进行修补,消除了包裹相位图中一个条纹周期内相邻像素点间大于π的相位突变。

Speckle noise is a common phenomenon in laser interferometry, which covers shape information of corresponding area of measured surface, resulting in measurement error. Aiming at characteristics of speckle noise in oblique laser interferometry, a recognition method of speckle noise based on object image is proposed. In this method, upper and lower thresholds of speckle noise are calculated automatically by statistic characteristics of gray scale distribution in effective measurement area and background area in object image. Position of speckle noise in interference fringe image is obtained based on mapping relation between object image and interference fringe image. A correlation experiment is designed to repair speckle noise region identified in interference fringe image, and eliminate phase transition between adjacent pixel points in a fringe period of wrapped phase diagram.