Roll angle interferometer by means of wave plates

A novel roll angle interferometer using a transverse Zeeman laser (TZL) is proposed in this paper. The orthogonally linearly-polarized light from TZL is changed to be slightly elliptically-polarized light by a quarter wave plate (QWP) when the principal axis of the QWP is at a small angle with the basis of the direction of polarization. The beam then passes through a half wave plate (HWP) that is employed as a sensor. After that it is reflected by a right angle prism (RAP) and returns to the HWP again. Owing to the reasonable transformation of coordinates by the prism, the change of direction of polarization is accumulated twice when the beam passes forward and back through the HWP. Theoretical analysis and experimental results show that the sensitivity of roll measurement can reach sub-second and be improved four times than that we had reported. This system of implementing roll measurement takes the advantage of compactness, stable performance, low cost and robust to the environment disturbance. (C) 2003 Elsevier Science B.V. All rights reserved.