1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Fat light

  1. Apr 21, 2005 #1


    User Avatar

    i just learned this in physics, and i dont quite understand something:

    according to Huygens, (i think) light is a ciruclar wave, and at everypoint on the wave there are wavelets. because there are so many ways for the wavelets to form, light takes every possible path from point a to point b. that parts sort of makes sense. then, all the really weird paths get cancelled, out and you are left with essentially a cone of light.

    the above (if i got it right) sort of makes sense. but what doesnt is that this is supposed to explain why when you make a pinhole thats too small you get blurryness. shouldnt you just get the image to be not as bright? i dont quite see where the blurry part comes in.
  2. jcsd
  3. Apr 21, 2005 #2
    If you have a small pinhole, you can get a diffraction from opposite edges.
    So, if you ahe a single source, you will get a bright central (main) peak and a lot of small peaks resulting from the diffraction. http://upload.wikimedia.org/wikipedia/en/e/e1/Diffraction1.png [Broken]

    The smaller the hole the stronger will be peaks. For a circular hole , I guess, you have additional rings. So your total image, produced by multiple sources will be blurred.
    Last edited by a moderator: May 2, 2017
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook