INTERFEROMETER. Albert Abraham Michelson Michelson Interferometer (1852-1931)

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