Importance Of The Michelson Interferometer

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The Michelson interferometer is a device that can divide a beam of radiation into two paths and then recombine the two beams after a path difference has been introduced. A condition is thereby created under which interference between the beams can occur. The variation of intensity of the beam emerging from the interferometer is measured as a function of path difference by a detector. The Michelson interferometer consists of two mutually perpendicular plane mirrors, one of which can move along an axis that is perpendicular to its plane.

Bisecting the fixed mirror and the movable mirror is a beamsplitter, where a collimated beam of radiation which could be infrared light emitted by an external source (Globar, metal wire, Nernst bar ), can be partially reflected to the fixed mirror (at point F for the median ray) and partially transmitted to the movable mirror (at point M). When the beams return to the …show more content…

The reflected part of the beam travels to the fixed mirror M1 through a distance L, is reflected there and hits the beam splitter again after a total path length of 2 L. The same happens to the transmitted part of the beam. However, as the reflecting mirror M2 for this Interferometer arm is not fixed at the same position L but can be moved very precisely back and forth around L by a distance x, the total path length of this beam is accordingly 2 • (L + x). Thus when the two halves of the beam recombine again on the beam splitter they exhibit a path length difference or optical retardation of 2*x , the partial beams are spatially coherent and will interfere when they recombine. The beam leaving the interferometer is passed through the sample compartment and Is finally focused on the detector D. The quantity actually measured by the detector Is thus the Intensity I (x) of the combined IR beams.as a function of the moving mirror displacement x, the so-called

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