Design of a compact wide-spectrum double-channel prism imaging spectrometer with freeform surface

A double-channel prism imaging spectrometer that includes visible-near-infrared (VNIR) and shortwave-infrared (SWIR) spectra is presented. Double slits divide a wide spectral band into two independent channels for VNIR and SWIR, guaranteeing their independent spectral resolution. A beam splitter splits the band into two, one detected by the SWIR and the other by the VNIR detector. The freeform surface, as a mirror, compensates for astigmatism across a wide spectral band. An imaging spectrometer with 30° field of view and a measured spectrum from 400 nm to 2500 nm is designed. This compact, cost-effective spectrometer with high performance and small spectral distortion has a huge potential for broadband space exploration.