阶跃型三维形貌信息小波去噪方法研究

阶跃样品显微测量时，样品三维形貌本身丰富的阶跃信息极易受到噪声高频信号的干扰，如何在滤除噪声的同时保持三维形貌的阶跃特征，实现对样品表面三维形貌信息的高精度测量是一个重要研究问题。利用小波函数良好的空间域和频率域的局部化特性，针对阶跃型样品的特点选取Haar小波，并采用一种基于模平方的阈值处理方法对三维形貌信息小波去噪方法进行研究。将该方法应用在本课题组研制的激光差动共焦显微镜扫描台阶样品得到的三维高度轮廓中，去噪后测量样品高度与OLYMPUS共焦显微镜扫描结果相对比，误差为0.146 8 nm，满足三维形貌信息后续测量分析的要求，证明了算法的有效性。

Wavelet denoising method for step three dimensional shape information

When measuring step samples by using microscope, a wealth of step information of three dimensional shape itself is highly vulnerable to be interfered by high frequency noise. How to maintain the step characteristics of three dimensional shape while filtering noise and achieve high precision measurement of three dimensional shape of the sample surface information is an important research question. We did the research on wavelet denoising method based on modulus square threshold method for step three dimensional shape information by using good space domain and frequency domain localization properties of wavelet function. Haar wavelet was selected for the step characteristics of the sample. The method was applied in the three dimensional height profile which was obtained through laser differential confocal microscope developed by our research group. The height measurement result of the sample after denoising is consistent with the scanning result of OLYMPUS confocal microscope. The deviation is 0.146 8 nm. It can satisfy the requirement of the follow up measurement analysis of three dimensional shape information and prove the effectiveness of the algorithm.