[OPTICAL REVIEW Vol. 4, No. 1A (1997) 133-137]
A Compact Optical Heterodyne Interferometer by Optical Integration and Its Application
Koichiro MIYAGI, Masaya NANAMI, Isao KOBAYASHI and Akira TANIGUCHI
Research Laboratory, ANRITSU Corporation, 1800, Onna, Atsugi, Kanagawa, 243 Japan
(Received July 10, 1996; Accepted September 9, 1996)
A compact high-resolution optical heterodyne interferometer combining a two-frequency light module and a minute optical system is described. The light module, which generates two independent frequencies of light, is fabricated by proton exchange method on LiNbO3 substrate. We report an experiment evaluating measurement accuracy using a micro-displacement measurement system which incorporates this interferometer. Results of the experiment with a standard thickness sample show high thermal stability with maximum measurement error of 1.8 nm at a temperature from 19°C to 33°C. The system was used to measure the hysteresis of a piezoelectric element for displacements of several nm, thereby making it possible to analyze the system quantitatively in practice.
Key words : heterodyne interferometer, optical frequency shifter, SAW, proton exchange