Polarization interferometer applied to measure of thermal expansion

In this paper, we recall the principle of interference comparator for comparing end standards and using an additive polarization interferometer. Then, the length difference between two samples can be interpreted by the phase difference between two rectilinear vibrations which are polarized on two perpendicular directions. This phase difference is measured by the means of phase modulation. Owing to these concepts a display was imagined to assure the differential measure of thermal expansion. It is allowing to compare elongations of one sample and one standard. As the samples are magnetic materials measured under variable directions and force magnetic fields, it results a conception of interferometer taking account of sizes and characteristics of thermal expansion chamber. The assembled described display is allowing to show variations of optical phase with 10-8 relative uncertainly in terms of length differential variation.