# Intensity imbalance

1. Feb 1, 2007

### stunner5000pt

1. The problem statement, all variables and given/known data
An atom trapping laser beam is incident on the trapping chamber as shown in the figure. Assume the lambda/4 plates and the miror are anti reflection coated. if the windows of the trapping chamber are uncoated, what is the intensit imbalance between incident and retro reflected beams? Note taht the atom trap will hold more atoms if there is no intensity imbalance

2. Relevant equations
The fraction between reflected power for an incident wave of power Io from a medium with index of refraction n1 onto a medium of index of refraction n2 and the power of the reflected wave is

$$\frac{I_{1}}{I_{0}}= \left(\frac{1 - \frac{n_{2}}{n_{1}}}{1 + \frac{n_{2}}{n_{1}}}\right)^2$$

3. The attempt at a solution
we know the quarter wave plate rotates the beam by 45 degrees

the beam entring the atom trapping chamber from the right will be rotated 90 degrees iwth respect to the beam entering the chamber from the left. but the question says htat the mirror is anti reflection coated.. so there would be no in beam entering from the right??

what are the retro reflected beams though??

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