A novel sensitive scheme for determining the optical parameters of thin films by p-polarized reflectance

We present a novel sensitive scheme for the measurement of optical paramete rs of thin films, based on the theory of optical admittance and data fittin g. A p-polarized laser beam falls on the glass surface at theta(i), and two beams with intensities I-a and I-b reflected from the front and the rear s urface of the glass are detected by a CCD. The characteristics of the angul ar modulation of the reflectance ratio gamma (gamma = I-a/I-b) are closely related to the optical parameters of the thin film, namely the refractive i ndex n(f), extinction coefficient k(f) and thickness d(f). By means of meas uring the angle distribution gamma (theta(i)) and fitting the results with theoretical data, the optical parameter of the films can be obtained easily . For several types of samples, such as surface layers of glass, single fil ms and multilayer films, we provide preliminary experimental results demons trating that the scheme has the advantages of simplicity and high sensitivi ty, which make it widely applicable to the fields of surface analysis, film measurement and photochemical sensors.