Light scattering from characterised random rough surfaces

A study of light scattering from random rough characterised rough surfaces is presented. The surfaces considered were in most cases metallic single scale surfaces having a surface height of known first order probability density function and known autocorrelation function. The first part of the thesis is concerned with the actual manufacture of these characterised rough surfaces, and the description of the equipment used to measure the scattered light from the rough surfaces i.e. the scatterometer. Then the physical optics scattering theory is developed for surfaces whose surface structure is on the order or larger than the incident wavelength by using the physical optics approximation; different probability density functions for the surface height are considered and the effect of this difference on the scattered light is studied. It is shown that the physical optics theory agrees well with the experimental data, but only when certain conditions hold, such as low mean slope and small angle of incidence. The validity of the physical optics solution is discussed. Then, scattering of light from high sloped surfaces is discussed. In measuring the scattered light from such surfaces, interesting effects are noted; the presence of a large cross polarised component, and the enhanced backscatter peak. Both of these effects can be qualitatively explained by a simple model using multiply reflecting rays. An analysis of the Stokes' parameters of the scattered light supports this simple model. The study of scattering of light from one dimensional surfaces is presented. The numerical code for the exact calculation of the scattered light from one dimensional rough surfaces (finite conductor) i.e. random gratings is developed, and the calculated values are compared with experimental data obtained using a surface that is a good approximate to a one dimensional gaussian random surface. (author)SIGLEAvailable from British Library Document Supply Centre-DSC:DX206204 / BLDSC - British Library Document Supply CentreGBUnited Kingdo