Optical design of the RODES hyperspectral LWIR imager

Abstract

Demonstrator of remote sensing system based on an uncooled LWIR hyperspectral imager was designed. This paper describes design of its optical part which is a hyperspectral imager in a spectral range of 7.5-12 um with a 40°×20° field of view. The hyperspectral imaging system is push-broom type based on an imaging spectrometer with transmission grating. Emphasis during design of optical subsystem was placed on future commercial production and usability in the field, thus focused on manufacturability, robustness and reduction of complexity. The optical subsystem was reduced down to 6 aspherical elements, of which one caries the spherical diffraction grating. The use of spherical grating improved manufacturability but introduced aberrations, which were not fully compensated by limited amount of optical elements. The final optomechanical design has an envelope of a 230×80×80 mm. A length of the optical subsystem is 160 mm.