结合非连续性测度的方向偏微分方程在电子散斑干涉中的应用

The Oriented Partial Differential Equation Based on the Discontinuities Measure for Electronic Speckle Pattern Interferometry

近年来,电子散斑干涉测量技术(ESPI)在光学粗糙表面的变形测量和无损检测方面应用广泛。应用该技术时,条纹图中大量的散斑噪声给提取条纹信息带来了极大的困难。偏微分方程图像滤波方法是一种方案灵活、处理效果良好的图像去噪方法,尤其是方向偏微分方程,因其只沿着条纹方向进行滤波,更适合电子散斑干涉条纹图。由于条纹图的疏密程度不同,因此在考虑滤波方向的同时,还应考虑不同位置像素点的滤波程度。该文在方向偏微分方程基础上引入非连续性测度,提出结合非连续性测度(DCM)的方向偏微分方程。利用该方程对模拟的条纹图以及实际获得的条纹图进行滤波,实验结果表明该文方法能够充分滤除稀疏条纹处的噪声,同时有效保持密集条纹处的重要特征。

The Electronic Speckle Pattern Interferometry （ESPI） is widely used for deformation measurement and nondestructive testing of the optical rough surface in recent years. Removal of the speckle noise is of fundamental importance for accurate extraction of the phase information. The Partial Differential Equation （PDE） filters are well-known for their good processing results, especially the oriented partial differential equation can control the direction of the filtering, which is more suitable for the ESPI image. Furthermore, the filtering degree of different pixels is considered. A new oriented PDE filter model is proposed for the ESPI fringe, in which the DisContinuities Measure （DCM） of an image is introduced to control the diffusion speed. The effectiveness of the proposed method is tested by means of the computer simulation and the experimentation on a real ESPI fringe patterns respectively. The results show that noise is effectively suppressed and the fringe edge is well preserved, even for very dense fringes.