变孔径像面散斑平均光强标定随机表面的理论与实验

THEORY AND EXPERIMENT FOR THE CHARACTERIZATION OF RANDOM SURFACES BY THE AVERAGE INTENSITY OF IMAGE SPECKLES OF VARIABLE APERTURES

采用随机表面的高斯相关模型和统计光学原理 ,推导出弱散射体在 4f系统中的像面上光强的表达式 .在此基础上提出了均方偏差粗糙度和横向相关长度的标定方法 ,该方法用理论结果对实验测量的像面散斑平均光强随滤波孔半径的关系曲线进行拟合 ,同时测量出被测样品表面的两个统计量 .实验上制作了高斯相关随机表面样品 ,对其表面参数进行了测量 ,与AFM所测结果符合得较好 ,这表明该方法具有较高的精度 .

Using the Gaussian correlation model of random surfaces, we conduct the theoretical derivation of the image-plane intensity produced by a weak scatterer in the 4f optical filtering system. Then the method is proposed for characterizing the square-root-mean deviation roughness and lateral correlation length. This method uses the derived theoretical expressions to fit the experimentally measured curve of image speckle intensity versus the radius of filtering aperture,and the two surface parameters can be extracted simultaneously. In the experiment,random surface samples are specially made and their surface parameters are measured. The results conforms with those obtained by atomic force microscopy,which shows that the method of this paper is of good accuracy.