# Homework Help: Michelson Interferometer - Fringe Shape

1. Dec 30, 2011

### cupid.callin

Hi all

Edit: The reflecting side is the right side of left slab

Please look at the pic above ... The light from source splits at left slab and goes in 2 directions and come back to interfere.

From figure, it is obvious that path diff. in slabs for both rays is 0
and only path diff. would be because of the difference in distance of 2 mirrors from left slab, which is d

so, i found the path diff, as $\Delta = 2\mu d cos \theta \pm \frac{\lambda}{2}$

$\frac{\lambda}{2}$ as green ray is reflected by denser medium ...

But i need to know how the circular or straight fringes are formed and how it depends on alignment of M1 and M'2

EDIT: μ would be the refractive index of stuff filled in whole system ... like air for example
and θ is incidence angle angle at slabs ... :}

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Last edited: Dec 30, 2011
2. Jan 1, 2012

3. Jan 6, 2012

4. Jan 6, 2012

### JimOlsen

Perfectly parallel mirrors results in circles if the optics are clean. Else you get what appears to be straight lines but i believe they are just the edges of a circle.