Morphological analysis by atomic force microscope and light scattering study for random scattering screens

The morphology of random screens with different surface roughness is studie d with atomic force microscope and it is found that their height distributi ons have very obvious fractal characteristics in short range regions. For s creens with larger and smaller roughness,the fractals exist in the forms of random height fluctuations and small grains without characteristic size re spectively. The self-affine fractal surface model is introduced to the quan titative descriptions of random screens. The light scattering measurements show that: (I)the scattered intensity in off-axis region descends in negati ve power functions,and the theoretical analysis based on self-affine fracta l model indicates that it originates from the short-range fractal of the sc reens;and (2) there is a halo ring in the scattered fields in the paraxial region. This phenomenon cannot yet be explained on the basis of the self-af fine fractal model.