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Hi In the Diffraction Handbook

  1. Dec 26, 2011 #1

    In the Diffraction Handbook http://gratings.newport.com/library/handbook/chapter6.asp#6.2.4 it says:

    A grating used in the Littrow or autocollimating configuration diffracts light of wavelength λ back along the incident light direction (Figure 6-4). In a Littrow monochromator, the spectrum is scanned by rotating the grating; this reorients the grating normal, so the angles of incidence a and diffraction b change (even though a = b for all λ).

    I don't understand what they mean by "even though a = b for all λ". Does anybody know, who wants to clarify this for me?

  2. jcsd
  3. Dec 29, 2011 #2
    Re: Monochromator

    From what I've read it looks like a=b because the incident light is reflected directly back on itself to the mirror, no matter what wavelength it is. (approximately anyways)
    I get the feeling that the angle of diffraction is the same as the angle of reflection in this case.
    hope this helps
  4. Dec 30, 2011 #3
    Re: Monochromator

    Thanks for helping.

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