Star shape interferometer with reduced vibration sensitivity

Abstract

An optical interferometer has a high sensitivity to displacements of the mirrors and other optical elements, something that becomes a source of fluctuations in situations where one is only interested in the phase change due to a sample inserted in one of the paths. A Sagnac interferometer minimizes this sensitivity by having the two beams follow opposite trajectories, so that a mirror displacement gives a similar phase change for both paths, but makes it impossible to insert an element that affects only one path. We present a new kind of interferometer, the Star interferometer, where the two beams still interact with all the optical elements while having different trajectories. We obtain a common phase change in both trajectories by having a different number of turns for each path. Having independent access to both trajectories makes it possible to determine the phase change due to a sample inserted in one of the paths, opening new possibilities for interferometric configurations that maintain a reduced sensitivity to displacements of the optical elements.