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Factors that govern the diffraction of electromagnetic waves

  1. Jan 17, 2005 #1
    What are the factors that govern the diffraction of electromagnetic waves.

    Why is it that ordinary light diffracts so much while laser is so precise. Does it have to do something with the monochromatic character of laser?
  2. jcsd
  3. Jan 17, 2005 #2


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    Perhaps you should explain to us what you undersand of defraction?
  4. Jan 17, 2005 #3
    Diffraction basically means the scattering of some wave when passing through some opening. Just look at what would happen if you would narrow down the opening of some tube in which water flows. I think you can imagine the result. It happens to all waves but indeed the scattering is not the same for all waves. The reason why a laserbeam stays together is the fact that lasers are coherent light. There are two types of coherency : spatial and time-like coherence. For example let's look at a wave that consists out of two subwaves. If you would look at some point on each subwave, you will see that the distances between those two points (one point on each subwave) does not alter when the wave propagates through space and time. One subwave does not run away from the other subwave, they stay together. This kind of wave is very ordened and no subwave will scatter off.


    check out my journal for more info on coherent light
    https://www.physicsforums.com/journal.php?s=&action=view&journalid=13790&perpage=10&page=4 [Broken]

    just look at the "for nanotechnology and micro-electronics lovers"-entry
    Last edited by a moderator: May 1, 2017
  5. Jan 17, 2005 #4
    Not sure what you have in mind when you say ordinary light diffracts more than a laser. Seems like you mix diffraction and coherence. Completely different things.

    Diffraction happens when a radiation hits matter with similar physical dimensions as its wavelength.

    Coherence is what marlon said. A more elementary way to see it is by dropping a box of ping-pong balls. If they all bounce together, they are coherent. If they're a mess, they are incoherent. If they bounce together at first, and after a while, they're a mess, there is a coherence time constant, which is the case with actual lasers.
  6. Jan 18, 2005 #5
    Thank you marlon and Gonzolo, that helped a lot. I was mixing coherence and diffraction.
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