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Homework Help: How does a FTIR machine operate?

  1. Jan 18, 2010 #1
    I know the basics about the interferometer and how this causes intereference patterns in a broadband spectrum to occur but I need to clarify a few things and I cant find the answer in any text book:

    1. The detector recieves information on the intensity of radiation being recieved and I have often read about the interferometer being able to simutaneousily sample the entire broadband spectrum range - I dont really understand this because when the waves interfere will there not being one resultant frequency at a particular wavelength?
    2 Is the lazer in the FTIR machine there present for calibration purposes?

    Please help if you can, I am finding it quite hard to get around some concepts
    Thanks
     
  2. jcsd
  3. Jan 18, 2010 #2

    rl.bhat

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    I dont really understand this because when the waves interfere will there not being one resultant frequency at a particular wavelength?
    Frequency is the property of the source. The interference does no affect the source.
    So there is no resultant frequency in the interference pattern.
     
  4. Jan 18, 2010 #3

    ehild

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    The FTIR spectrometer works with a Michelson interferometer. It has a moving mirror and the intensity of the radiation of a broad-band source is converted to the interferogram - resultant intensity of the interfering rays coming from two arms one with constant length, the other with a length x(t) changing in time. One frequency in the spectrum corresponds to a sine wave in x or t. The interferogram and the original spectrum are Fourier transforms of each other.

    The laser in the apparatus is for the optical alignment.

    ehild
     
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