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Laser beam diffraction

by strikingleafs01
Tags: beam, diffraction, laser
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Dec1-07, 06:03 PM
P: 8
1. The problem statement, all variables and given/known data

A scientist needs to focus a helium-neon laser beam (lamda = 633nm) to a 10 micrometre diameter spot 8.0 cm behind the lens.

a) What focal-length should she use?
b) What minimum diameter should she use?

2. Relevant equations

w = (2.44lambda * focal length) / diameter

theta = 1.22lamda/diameter

Wmin is apprx equal to 2.5lambda....apparently, but if you have a seperate method ignore this.

3. The attempt at a solution

i attempted to calculate w through 2.5lambda, then use that to calculate the focal length. the answer i got was 0.001cm.
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Dec1-07, 08:37 PM
P: 8
I cannot seem to find any modification of this equation anywhere, but it seems that this is the only equation that is used to solve this problem
Dec1-07, 10:35 PM
P: 4
Oh! So did you get the right answer using that formula?

Dec1-07, 10:54 PM
P: 8
Laser beam diffraction

nope, still nothing, anyone know anything??

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