Geometrically exact ellipsometer alignment.

A procedure is outlined in which the symmetry of the ellipsometer is used to provide the information needed for its own alignment. Alignment is based upon four null measurements taken on a transparent reflecting surface. These are related to the tilt angles of the polarizer and analyzer telescope arms, and reference angles for which the transmitted polarization vectors of the analyzer and polarizer prisms lie in the plane of incidence. The alignment is not affected by the presence of small parasitic ellipticities induced by defects in either polarizer or analyzer prisms. A step-by-step procedure for ellipsometer alignment, which requires only equipment necessary for normal operation of the instrument, is given.