  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.
