Conceptual illustrations of the 1D Fourier-transform spectrometry. For a stand-alone tFTS/SHS, the period of the sinusoidal response is tuned by changing the heating power (P) or arm-length difference (Δ L SHS ). At a single wavelength (λ), the interferogram (O) is a 1D sequence sliced from a 2D transmittance matrix (A). The 1D fast Fourier transform (FFT) of the interferogram contains a peak in each quadrant.
