Increasing the sensitivity for tilt measurement using a cyclic interferometer with multiple reflections

TLDR: In this paper, a cyclic interferometer was used to measure tilt in which the sensitivity to tilt measurement was double when compared with that of the classical Michelson interferometers.

Abstract: Measurement of tilt plays an important role in metrological applications and consequently, several methods have been proposed in the recent past. Classical interferometric methods can measure angles with high accuracy but are easily susceptible to external turbulences. We propose to use a cyclic interferometer to measure tilt in which the sensitivity to tilt measurement is double when compared with that of the classical Michelson interferometer. Since the counter propagating beams travel identical paths, the interferometer is insensitive to external vibrations and turbulence and thus can be used under harsh environmental conditions. The novelty in the technique lies in creating multiple reflections in the tilt mirror to enhance the measurement accuracy by the way of increasing the sensitivity. This paper presents the basics of the interferometer and experimental results to quantify the increase in sensitivity. By increasing the number of reflections, it is shown that sensitivity can be further improved to measure tilt angles below 5   μ rad .