A high precision automatic ellipsometer using grating goniometers

Abstract

The construction and performance characteristics of a high precision automatic ellipsometer are described with particular reference to a wide set of specifications. The automatic self-nulling instrument employs two-stage Faraday modulation operating at two different, high frequencies and the channel separation, response time and noise level are all optimized. A wide spectral range may be covered without instrument calibration or readjustment. The instrument also has a wide angular-setting range achieved by using, in conjunction with the Faraday modulation, a mechanical rotation system employing aerostatic journal bearings. The maximum speed using the electromechanical system is 0.09 degrees s-1 and the ultimate resolution 0.648 second of arc.