Determination of optical constants of metals by near grazing incidence reflectivity measurements

Abstract

A critical review of the methods to measure the optical constants n and k of metal shows a severe fall in sensitivity in the infrared range. A new sensitive method which consists in obtaining ( n,k) by fitting the reflectivity R p at near grazing incidence, around the pseudo Brewster angle, is proposed. The difficulty of measuring the reflectivity near the grazing incidence is partially avoided using long samples and focusing optics. A χ 2 analysis of the sensitivity is made in order to demonstrate that the presented method is the most sensitive reflectometric one in that range. The optical constants of copper and gold at CO 2 laser wavelengths are obtained with uncertainties of about 2%.