Ellipsometer nulling: convergence and speed

Publisher Website
Google Scholar
Abstract
The process of nulling in ellipsometry is studied by a graphical presentation using the trajectories of two significant polarization states in the complex plane, χPC and χSA. These states are determined by (1) the polarizer and compensator (χPC) and (2) the specimen and the analyzer (χSA) in the polarizer–compensator–specimen–analyzer ellipsometer arrangement. As the azimuth angles of the ellipsometer elements are varied, χPC and χSA move closer to one another in a stepwise fashion until they coincide when a null is reached. Thus, at null, the polarization states are matched, and χPC = χSA. For an isotropic reflector, the trajectory of χSA is a straight line, which simplifies the development of a criterion for achieving the most rapid nulling for two nulling procedures.