How does a FTIR machine operate?

[physical101]

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 can't find the answer in any textbook:

1. The detector receives information on the intensity of radiation being received and I have often read about the interferometer being able to simutaneousily sample the entire broadband spectrum range - I don't really understand this because when the waves interfere will there not being one resultant frequency at a particular wavelength?
2 Is the laser 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

 

[rl.bhat]

I don't 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.

 

[ehild]

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