Question about optics (diffraction)

AI Thread Summary
When illuminating a hole and projecting the resulting diffraction pattern on a screen, the pattern initially decreases in size as the hole narrows, but eventually enlarges due to diffraction effects. The confusion arises from deriving the relationship between the screen pattern diameter, hole size, distance to the screen, and wavelength. The Kirchhoff integral theorem is considered for the derivation, although simpler methods may exist. The discussion reflects on the complexity of the topic, questioning whether it is still considered introductory physics. Understanding diffraction is essential for grasping these optical phenomena.
Gza
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I was working out a practice test on optics and was a little confused about how to tackle this problem:


If you illuminate a hole and project the resulting pattern on a screen- as you decrease the hole size, the screen pattern gets smaller initially and then ultimately begins to grow larger. Why is this? Derive a formula for the screen pattern diameter as a function of the hole size, distance between screen and hole and the wavelength.


I know the effect is diffraction, but deriving the mentioned relation is giving me trouble. I was thinking of using the kirchhoff integral theorem, and then perhaps carrying out an integral over a rectangular aperature; but maybe that is overkill. Is their an easier way to start thinking about this?
 
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Gza said:
If you illuminate a hole and project the resulting pattern on a screen- as you decrease the hole size, the screen pattern gets smaller initially and then ultimately begins to grow larger. Why is this? Derive a formula for the screen pattern diameter as a function of the hole size, distance between screen and hole and the wavelength.
Is this considered introductory physics nowadays? :eek: I must be getting old.

Maybe this will help a bit:
http://en.wikipedia.org/wiki/Diffraction
 
Lol, yeah this was probably a mispost; i got a chance to check the other posts in this section and realized it at that point. Thanks for the reference though galileo.
 

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