Sheng-Hui CHEN^*, Kai WU, Chien-Cheng KUO, Sheng-Ju MA, and Cheng-Chung LEE

Department of Optics and Photonics, National Central University, Chungli 320, Taiwan

(Received July 15, 2008; Revised April 12, 2009; Accepted April 13, 2009)

A new method based on the polarization interferometer structure has been applied to measure the optical admittance, the refractive index and thickness of a thin film. The structure is a vibration insensitive optical system. There is one Twyman–Green interferometer part to induce a phase difference and one Fizeau interferometer part to induce the interference in the system. The intensities coming from four different polarizers were measured at the same time to prevent mechanical vibration influence. Using the polarization interferometer, the optical admittance, the refractive index and thickness of a single layer of Ta₂O₅ thin film has been measured. The measurement results were compared with the results obtained by ellipsometer. The results meet reasonable values in both refractive index and thickness.

Key words: thin film, optical constant, optical admittance, polarization interferometer

^*E-mail address: ericchen@dop.ncu.edu.tw