Ellipsometry is used to determine the thickness of thin films and to find the complex index of refraction (n and k) of materials, by analyzing the polarization of light reflected at an angle from a sample surface. CMSE's ellipsometer probes the sample with a single wavelength laser, with a wavelength choice of red (633 nm), blue (488 nm) or near-IR (830 nm). The analysis area is about 1 mm x 3 mm. The minimum measurable film thickness is a few angstroms with an accuracy of + or - 3 , and the maximum measurable thickness is about 10 um.