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In order to make identifications, the analyst will need a frequency spectrum (plotting of intensity value for each frequency value). This information is not provided by the measured interferogram signal. In order to get the individual frequencies, the measured signal needs to be “decoded.“ The decoding process is where Fourier transformation is utilized. A computer performs the transformation and presents the required spectral information for analysis.
figure 3: Conversion of measured signal into frquency spectrum by application of FFT (fast Fourier transformation)
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