CIRCUIT DESIGN FOR AN ELECTRONIC SELF-NULLING ELLIPSOMETER

The importance of automating the ellipsometer has been recognized by researchers active in the field and considerable attention has been given to the development of a practical instrument. The present work was motivated by the belief that a more satisfactory automatic ellipsometer could be developed if the all-electronic approach suggested by Winterbottom was used. This approach has resulted in the design and construction of an instrument that is sensitive, stable, relatively inexpensive and which has a response time that is of the order of milliseconds. The electronic circuits will easily lend themselves to duplication by investigators interested in such a device and are of such a configuration that existing instruments need only minor modifications. An automatic gain stage circuit is included to maintain maximum sensitivity where spectral emission and sensitivity variations are encountered, as in continuous wavelength scanning ellipsometric measurements. © 1969.