Static Fourier transform mid-infrared spectrometer with continuous background correction

In this contribution we present a broadband static Fourier transform spectrometer (bsFTS) based on a single- mirror interferometer containing only off-the-shelf optical components and an uncooled microbolometer detector array. The system uses concave mirrors instead of lenses and therefore covers a wide spectral range from 3.6 μm to 17 μm at a spectral resolution of 12 cm-1. Furthermore, dispersion effects can be minimized and the system can thus be designed with increased temperature stability. We demonstrate the optical and mechanical design of the current laboratory prototype and compare the instrument to a scanning Fourier transform infrared (FTIR) spectrometer. Additionally, we present a technique for simultaneously acquiring the sample spectrum and the background spectrum. Thereby, a variation of the background over time can be compensated continuously and hence the bsFTS presented in this contribution offers significant potential with regard to long-term stability.