Demonstration of tilt sensing using a homodyne quadrature interferometric translational sensor

TL;DR

This paper introduces QUIMETT, a laser interferometric sensor capable of simultaneously measuring translation and tilt with high sensitivity, suitable for space-based gravitational wave detection.

Contribution

The paper presents a novel interferometric sensor that independently measures tilt and translation simultaneously in a single package, with demonstrated high tilt sensitivity.

Findings

Tilt sensitivity of 10 nrad/Hz$^{1/2}$ at 0.1 Hz

Tilt measurement independent of interference condition

Simultaneous translation and tilt measurement in a single sensor

Abstract

Future gravitational wave observation in space will demand improvement in the sensitivity of the local sensor for the drag-free control. This paper presents the proposal, design, and demonstration of a new laser interferometric sensor named Quadrature Interferometric Metrology of Translation and Tilt (QUIMETT) for the drag-free local sensor. QUIMETT enables simultaneous measurements of both translational displacement and tilts of a reflective object with a single interferometer package. QUIMETT offers a characteristic feature where the sensitivity to tilt is independent of the interference condition while maintaining the ability to measure the translational displacement for a range greater than the laser wavelength. The tilt-sensing function has been demonstrated in a prototype experiment. The tilt sensitivity remained unchanged in different interference conditions and stayed at 10 nrad/Hz$^{1/2}$ at 0.1 Hz.