Long-wave infrared hyperspectral imager based on a scanning Fabry–Pérot interferometer

Abstract: This work presents a hyperspectral imager sensitive to radiation in the 1250–666 cm⁻¹ wavenumber range (wavelengths between 8 and 15 μm). The system combines a low-order scanning Fabry–Pérot interferometer with a thermal camera utilizing a 1024 × 768-pixel uncooled microbolometer detector. The compact interferometer design enables a relatively small footprint, providing a spectral resolution between 26 and 39 cm⁻¹, depending on the wavenumber. Transmission measurements of various substances are shown to produce distinct interferograms, facilitating material identification. In addition, a generalized matrix method is used to estimate the relationship between physical cavity length and wavenumber of the incident light, enabling the prediction of interferogram shapes.