A Review of Compact Interferometers

TL;DR

This review paper discusses the principles, types, and recent improvements of compact interferometers, or phasemeters, emphasizing their high resolution and accuracy for applications like gravitational wave detection.

Contribution

It provides a comprehensive classification and comparison of homodyne and heterodyne phasemeters, highlighting recent advancements in resolution and accuracy improvements.

Findings

Resolution improvements linked to noise reduction

Accuracy enhancements through non-linearity minimization

Comparison of different phasemeter designs

Abstract

Compact interferometers, called phasemeters, make it possible to operate over a large range while ensuring a high resolution. Such performance is required for the stabilization of large instruments dedicated to experimental physics such as gravitational wave detectors. This paper aims at presenting the working principle of the different types of phasemeters developed in the literature. These devices can be classified into two categories: homodyne and heterodyne interferometers. Improvement of resolution and accuracy has been studied for both devices. Resolution is related to the noise sources that are added to the signal. Accuracy corresponds to distortion of the phase measured with respect to the real phase, called non-linearity. The solutions proposed to improve the device resolution and accuracy are discussed based on a comparison of the reached resolutions and of the residual non-linearities.