In this paper, we have combined a Mach-Zehnder interferometer and an optical heterodyne using an AO modulator to set up an interferometric ellipsometer for measuring the optical properties of metal surfaces. Because there is no moving mechanism, e.g., compensators and quarterwave plates, we can eliminate the errors caused by these elements. By using a phase lock-in technique and computer processing, we can measure parameters Ψ and Δ in real time and with great accuracy (where Ψ is the amplitude ratio of the P- and S-waves, and Δ is the phase difference in the P- and S-waves).
© 1990 Optical Society of America
Chin-hwa Lin, Chien Chou, and Keh-su Chang, "Real time interferometric ellipsometry with optical heterodyne and phase lock-in techniques," Appl. Opt. 29, 5159-5162 (1990)