Theory and experiment for the characterization of random surfaces by the average intensity of image speckles of variable apertures

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