Take the 2-minute tour ×

I know that in free space, the width of a Gaussian beam can be written as $W=W_0\sqrt{1+(\frac{z}{z_0})^{2}}$. However, I was wondering if it was possible to express this width as a function of refractive index instead (since I don't believe a Gaussian beam originating in say, glass, will diverge in the same manner as one in air). Anyone have any ideas?

share|improve this question
add comment

1 Answer

up vote 2 down vote accepted

Yes, and the formula you already have still works. Take z to be the optical path length: refractive index n times physical distance. A Gaussian beam in glass diverges in exactly the same way as in free space, only 'squeezed' in the z direction by a factor of n.

share|improve this answer
Looks good. Could you take a look at my other question: physics.stackexchange.com/questions/38730/…, which is related to this one? –  John Roberts Oct 1 '12 at 18:38
add comment

Your Answer


