Defeng ZHENG^1,2, Xiangzhao WANG^1,2*, and Osami SASAKI³

¹Information Optics Laboratory, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
²Graduate School of Chinese Academy of Sciences, Beijing 100039, China
³Faculty of Engineering, Niigata University, Niigata 950-2181, Japan

(Received March 22, 2007; Accepted July 17, 2007; Revised July 6, 2007)

A parallel plate interferometer with a reflecting mirror for measuring angular displacement is proposed. A deflection angle of a beam caused by an angular displacement is amplified by use of a reflecting mirror to increase the optical path difference (OPD) in the plane-parallel plate, which provides high sensitivity of the phase measurement. Detection of light transmitted through the plane-parallel plate with a position sensitive detector (PSD) enables high accurate measurement of the initial angle of incidence to the plane-parallel plate with insensitivity to stray light. The improved parallel plate interferometer achieves a measurement repeatability of 10^-8 rad.

Key words: angular displacement, interference measurement, plane-parallel plate, laser diode, phase measurement

^*E-mail address: wxz26267@mail.siom.ac.cn