The Jamin interferometer is a type of interferometer, related to the Mach-Zehnder interferometer. Interferometry is the technique of using the pattern of Interference created by the superposition of two or more Waves to diagnose the properties of The Mach-Zehnder interferometer (named after physicists Ludwig Mach (son of Ernst Mach) and Ludwig Zehnder) is a device used to determine the phase shift It was developed in 1856 by the French physicist Jules Jamin. Jules Célestin Jamin ( 31 May 1818 - 12 February 1886) was a French Physicist.
The interferometer is made up of two mirrors, made of the thickest glass possible. A mirror is an object with a surface that has good Specular reflection; that is it is smooth enough to form an Image. The Fresnel reflection from the first surface of the mirror acts as a beam splitter. A beam splitter is an optical device that splits a beam of Light in two The incident light is split into two rays, parallel to each other and displaced by an amount depending on the thickness of the mirror. The rays are recombined at the second mirror, and ultimately imaged onto a screen.
If a phase-shifting element is added to one arm of the interferometer, then the displacement it causes can be determined by simply counting the interference fringes (e. The phase of an oscillation or wave is the fraction of a complete cycle corresponding to an offset in the displacement from a specified reference point at time t = 0 g. , the minima).
The Jamin interferometer allows very exact measurements of the refractive index and dispersion of gases; a transparent pressure chamber can be positioned in the instrument. The refractive index (or index of Refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves is reduced inside the medium In Optics, dispersion is the phenomenon in which the Phase velocity of a wave depends on its frequency This page is about the physical properties of gas as a state of matter The phase shift due to changes in pressure is quite easy to measure.
References
J. Jamin. Pogg. Ann. 98, S. 345 (1856)