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Wavelength measurement of light by Interferometer

As we know two coherent light source interference produce interference fringes which can shows various measurement factors change.

The wavelength of light depends on the change in phase of signals or number of fringes with respect to change in distance between two sources. When half of wavelength distance is change than a fringe is pass or 2π phase change occur. So during change in distance we can calculate change in phase which is used for wavelength measurement.
 
 
                  wavelength of light λ=(2Δd)/N



where Δd is change in distance and N is change in number of fringes.

Fringes detected by michleson interferometer by CCD.


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