I am evaluating the specifications of an FTIR instrument (Bruker Vertex) and came across the following statements/items:

Signal-to-Noise 5 sec sample, 5 sec reference: >10,000:1 (<4.34 x 10-5 AU noise) peak-to-peak @ 2,000 cm-1, 4 cm-1 spectral resolution and standard optical components

Signal-to-Noise, typical 5 sec: 16,000:1 (2.71 x 10-5 AU noise) peak-to-peak 1 min: 60,000:1 (7.2 x 10-6 AU noise) peak-to-peak Note: Achieved typical Signal-to-Noise peak-to peak values are statistical numbers which depend on the applied measurement parameters and laboratory working conditions.

I was wondering how this should be understood. I would assume, that in order to specify the SNR you have to state how much input the system gets. (Sth alike: For X mW/cm-1 coupled into the system, at frequency Y, at resolution Z the SNR is ... )

To me, here it appears as if this was an "absolute" value (apparently depending on integration time). Is 10'000:1 this the ratio between saturation signal level and noise i.e. dynamic range? (This would only be of limited use...) And what could the

5 sec reference


UPDATE: I may have been misguided by what I am trying to measure (emission of light source, without reference to the reference lamp in the system). Could it be, that 10'0000:1 refers to the signal level of the reference lamp vs. the noise level? Can anyone confirm?



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