MULTICHANNEL TRANSMISSION ELLIPSOMETER FOR CHARACTERIZATION OF ANISOTROPIC OPTICAL-MATERIALS

We have developed a multichannel transmission ellipsometer to characte rize the wavelength dependence of the optical characteristics of trans parent, anisotropic solids. The source side of the instrument employs a broadband lamp in conjunction with a rotating polarizer. The light t ransmitted through the sample is analyzed by a stationary polarizer, a grating spectrograph, and a 1024-pixel photodiode array. The photodio de array collects irradiance spectra at several uniformly spaced value s of the rotating polarizer angle P, and the irradiance registered at each pixel of the array is Fourier analyzed versus P. From this analys is one can characterize the change in polarization state induced by th e sample as a continuous function of wavelength from 400 to 800 nm. Th e multichannel transmission ellipsometer can be applied in studies of linear and circular birefringence in new materials as well as in asses sments of the spectroscopic performance of polarization-modifying devi ces such as retarders. However, we also emphasize the application of t he instrument as an educational tool for demonstrating polarization co ncepts in advanced undergraduate physics and optics laboratories. In t his application anisotropies in common optical materials have been cha racterized, including circular birefringence in quartz and linear bire fringence and dichroism in mica. Because high-precision data are colle cted continuously versus wavelength, the results represent a clear imp rovement over those obtained at discrete wavelengths.