
#1
Dec107, 06:03 PM

P: 8

1. The problem statement, all variables and given/known data
A scientist needs to focus a heliumneon laser beam (lamda = 633nm) to a 10 micrometre diameter spot 8.0 cm behind the lens. a) What focallength 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. 



#2
Dec107, 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




#3
Dec107, 10:35 PM

P: 4

Oh! So did you get the right answer using that formula?




#4
Dec107, 10:54 PM

P: 8

Laser beam diffraction
nope, still nothing, anyone know anything??



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