Methodology for computing Fourier-transform infrared spectroscopy interferograms

With the utilization of Fourier-transform infrared (FTIR) spectroscopy for a multitude of commercial applications, a robust methodology for designing, implementing, and servicing these systems in commercial settings is becoming increasingly paramount. Here we present a method allowing for the numerical evaluation of the interferogram signal in a FTIR spectroscopy system, in which the incident electric field can exhibit any arbitrary spectral content. The developed model assesses multiple internal reflections occurring within a beam splitter (BS) and compensating plate (CP), allows for the presence or absence of the CP, and obtains the interferogram in absolute units. The interferogram is evaluated for the representative scenarios of an incident electric field having a blackbody spectral distribution (interacting with a BS and CP composed of S i O ₂) and a randomly chosen spectral distribution (interacting with a BS composed of ZnSe and no CP).