Variable Angle Spectroscopic Ellipsometer is an excellent tool to measure thin film thickness and its refractive index. The instrument shines linearly polarized light on the sample surface and the ellipticity of the reflected light from the sample surface is analyzed for the s-polarized and p-polarized components of the light. Since it measures the ratio of the s and p polarized light the data is very accurate. The data is measured over the entire wavelength range and compared to a mathematically generated model to obtain film thickness and refractive index etc. This instrument can work in the visible range of the spectrum (250-850 nm) as well as in the NIR (850-2500 nm) region. Since it is spectroscopic ellipsometry multi layered films could be analyzed accurately.