Roll angular displacement measurement system with microradian accuracy

Abstract

A novel compact roll angular displacement measurement system is presented. It consists of a linearly orthogonally polarized, heterodyne laser source as the detection probe beam, a wave-retardation plate or a set of a half-wave plate plus a wave-retardation plate as the angle-sensing element to form an interferometric system. The roll angular displacement of a moving device can be detected by measuring the phase difference between the reference and measurement beams. The experimental results fit well with the theoretical analysis and a measurement resolution of sub-microradian over a half-degree is achieved experimentally.