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Spectrometer slit

  1. Jul 29, 2009 #1
    Can anyone tell me the purpose of a entrance slit in a dispersive spectrometer. What is it good for? I guess it will create a single slit diffraction pattern. Why will this make the resolution better, instead of just colliminate the beam?

    Will the slit do some kind of fourier filtering also?

  2. jcsd
  3. Jul 29, 2009 #2
    The slit should not be so small that there is notable diffraction from it. Its purpose is simply to make the spectral lines narrow. Consider that even monochromatic light entering a prism at a different spot will be projected at a different spot. So the slit keeps it to one spot.
  4. Jul 29, 2009 #3

    Andy Resnick

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    An entrance slit is not a requirement, but it's true that many spectrometer designs (Echelle, use entrance slits.

    One reason is overall transmission efficiency and aberration correction- some designs are kinda like imaging systems in that the exit slit is an image of the entrance slit.

    Another reason is so that multiple spectrometers can be daisy-chained together to provide ever-finer spectroscopic detail.

    Chapter 8 of the Richardson Grating Handbook has addtionial details:

    Last edited by a moderator: Apr 24, 2017
  5. Jul 30, 2009 #4

    Thanks, very helpful.
    Last edited by a moderator: Apr 24, 2017
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