Document Type


Publication Date



A retroreflection (return-path) spectroscopic ellipsometer without a wave plate is described that uses an IR-transparent high-refractive-index hemicylindrical semiconductor substrate to measure the optical properties of aqueous solutions from multiple principal angles and multiple principal azimuths of attenuated internal reflection (AIR) at the semiconductor–solution interface. The pseudo-Brewster angle of minimum reflectance for the p polarization is also readily measured using the same instrument. This wealth of data can also be used to characterize thin films at the solid–liquid interface. Simulated results of AIR at the Si–water interface over the 1.2–11 μm IR spectral range are presented in support of this concept. The optical properties of water and aqueous solutions are important for modeling radiative transfer in the atmosphere and oceans and for biomedical and tissue optics.


This paper was published in Applied Optics and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.

R. M. A. Azzam, "Return-path, multiple-principal-angle, internal-reflection ellipsometer for measuring IR optical properties of aqueous solutions," Appl. Opt. 49, 4710-4714 (2010)