Cooled Dyson long-wave infrared push-broom imaging spectrometer by re-imaging

•Three-mirror off-axis aspherical optical system was selected to provide ideal image at the slit.•Re-imaging method was adopted to realize 100% cold stop efficiency in Dyson imaging spectrometer.•The corrector lens in traditional Dyson imaging spectrometer was deleted by the re-imaging lens.

A cooled long-wave infrared push-broom imaging spectrometer with an F-number of 2 was designed based on the Dyson configuration. A three-mirror off-axis aspherical optical system that provided excellent slit-shaped images was selected as the fore telescope objective. The re-imaging method was applied to obtain a cold stop efficiency of 100%, and the corrector lens in traditional Dyson imaging spectrometers was replaced with re-imaging lenses to correct spherical aberrations. The designed imaging spectrometer provided a spectral resolution of 25 nm at a range of 8–12 μm and possessed a relatively small volume.