# Optics Question (I think about Fresnel-Kirchoff) (1 Viewer)

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#### rabbit44

1. The problem statement, all variables and given/known data
A laser produces a beam of coherent light of wavelength lambda with plane
wave-fronts travelling along z. The amplitude of light transmitted by a trans-
parency in the x; y plane is independent of y and varies with x as

A[1 + cos(2*pi*x/d)]

where A is a constant and d > lambda. Show that three beams emerge
from the transparency, and find their angles to the z-axis.

2. Relevant equations

I think:

A(B) ~ int[u(x) exp(-iBx)]

Where B=k*sin(theta), u is the amplitude distribution given and A(B) is the amplitude at some theta.

3. The attempt at a solution
So I tried using that equation, hoping that only 3 values of theta would be valid or something, but it just didn't work at all. Am I completely off?

Thanks

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