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INTERFEROMETER
Albert Abraham Michelson
Michelson Interferometer
(1852-1931)
Experimental set up
Effective arrangement of the interferometer
Circular fringes
©SPK
Radius of nth dark ring
md
md
m
m
212
cos22
d
nDDr mn
2
222
In Michelson interferometer
Haidinger Fringe
md m cos2
•Order of the fringe
•Angular radius of the pth ring
•Formation of both real and virtual fringes
Fringe collapse/emergence
1. Measurement of wavelength of light
)(md 0 2 0 md 2
nmmdd 02
2 cosd m
2. Measurement of wavelength separation of a doublet
1112 qpd
112 12 nqnpd
1112 12 nndd
12
21
2 dd
Newton-Michelson rings
For details refer toSastry-Saraswat’s book
Michelson interferometer: R
Newton’s rings: d 0
•Measurement of the coherence length of a spectral line
•Formation of straight white light fringes
•Measurement of thickness of thin transparent flakes
•Measurement of refractive index of gases
•Standardization meter
Newton’s Ring Michelson Interferometer
Virtual fringe
Localized
Dark central ring (reflected)
Bright (transmitted)
order of the ringsincrease when one moves
away from the center
Fringes of equal thickness(Fizeau fringes)
Fringes of equal inclination(Haidinger’s fringes)
Virtual fringe*
Non-localized
Dark central ring (for
back silvered mirror)
order of the rings decrease when one movesoutwards from the center