Evaluation of a high accuracy reflectometer for specular materials.

A high accuracy method for measuring the spectral reflectivity of specular materials over the 0.300-15.0-microm wavelength range is described. The performance of the reflectometer has been evaluated, and results for an evaporated aluminum film are compared with those obtained by the Bennett-Koehler instrument upon which our design is based. For highly reflecting materials, like those of current interest for laser mirror coatings, it is possible to achieve accuracies, based upon evaluated systematic errors, of the order of 1 part in 10(3). Discussion of the effects of sample tilt, detector linearity optical configuration, and bandwidth on the measurements is presented.