Setup and evaluation of a static imaging Fourier transform spectrometer for the mid-infrared spectral range

Hyperspectral imaging is an established technique for process analysis capturing a two-dimensional spatial image and the spectral information for each pixel simultaneously. When moderate spectral resolution is sufficient, static imaging Fourier transform spectrometers (sIFTS) can offer a viable alternative to their scanning counterparts in the mid-infrared spectral range. Therefore, in this paper we present a sIFTS concept based on a single-mirror interferometer which shows no internal light losses and still works with extended light sources, achieving sufficient signal-to-noise ratios. The interferometer consists of a beam splitter, a plane mirror and a lens, which makes it both inexpensive and relatively easy to adjust. For a proof of principle we present a transmission measurement setup including a light source module, imaging optics and a single-mirror interferometer. The system achieves a spectral resolution of 12 cm−1 in a spectral range from 2700 cm−1 to 800 cm−1 , respectively from 3.7 μm to 13 μm. The spatial resolution amounts to about 10.10 lp/mm, the results for a sample containing different polymers show good agreement with a laboratory FTIR spectrometer.