Analysis of optical surfaces by means of surface plasmon spectroscopy

The sensitivity to material parameters of surface plasmon oscillations is explored in the design of a prototype simultaneous determination of thickness, complex permittivity and surface roughness of metal films. The apparatus was employed for characterization of gold and silver films with thicknesses within the 10 to 100 nm range. Thickness data measured with the prototype system were well correlated with those measured on a conventional surface profilometer. The Fourier spectrum of surface irregularities extracted from scattered light, enhanced by surface plasmon oscillations, used to determine surface roughness parameters for the distinct samples. Those parameters were shown to be representative of the typical surface structures observed with the atomic force microscope. Alternative configurations for adapting the optical system for use as a table top instrument are discussed