Jamin-Interferometer

The Jamin interferometer is an interferometer, which was invented in 1856 by Jules Célestin Jamin. It allows a very accurate measurement of the refractive index of chemical substances, wherein the refractive index n is defined as the ratio of light velocity in a vacuum to light velocity in the medium. The interferometer consists of two mirrors with thick glass as possible. Incident light is split by the first mirror into two portions, the second mirror combines the two parts again.

Design and function

Is introduced transparent matter in an optical path of the interferometer, so there is reduced the speed of light, and the paths between the two light paths differ. To determine the dependence of the speed of light from the pressure of a gas, a transparent pressure vessel is introduced into one of the optical paths of the interferometer. With increasing pressure now occurs a well measurable phase shift.