Development of a wide‑band imaging FT‑IR using wavefront‑division interferometry for future planetary and space‑exploration payloads

We aim to obtain two-dimensional, spatially resolved infrared spectra for compact planetary and small-satellite missions. To meet this goal, we developed an imaging FT-IR spectrometer that uses wavefront-division Fourier interferometry and Zernike freeform mirrors. The instrument covers 4–20 µm with 3.8 cm^-1 wavenumber resolution and 34 µm spatial resolution. An uncooled mid-infrared camera records an interferogram and a spectrum at each pixel, so a full 2D spectral map is acquired in one scan. Extended sources reduce spatial coherence and wash out the fringes. We address this by placing a slit-array Wavefront Pre-Selection Mask module (WPSM) at the entrance plane. The WPSM raises the center-burst amplitude of 50 and nearly doubles the fringe contrast. A 960 cm^-1 quantum cascade laser test shows a mean wavenumber offset of 0.05 cm^-1, and polystyrene standard data agree with catalog spectra, showing that this system can provide accurate 2D infrared spectra.