Analysis and design of an ultra-wide temperature difference very long wave infrared multifunctional imaging spectrometer

Abstract

The detection of various cryogenic targets, including the polar cryosphere, high-altitude clouds, and cosmic galaxies through spectral analysis, is a highly valuable area of research. Nevertheless, creating a very long wave infrared (VLWIR) imaging spectrometer capable of detecting these targets presents a significant challenge. In this paper, we introduce a design concept for an ultra-wide temperature difference athermalization VLWIR multifunctional imaging spectrometer. Initially, we analyze the multifunctional characteristics of an imaging spectrometer that utilizes a coaxial optical layout. Subsequently, we delve into the constraints associated with smile aberration correction and coaxial optical layout of the imaging spectrometer, which utilizes a grism as the dispersion component. Finally, we construct a computational model to determine the parameters of the grism. In the study, we provide evidence that imaging spectrometers with symmetrical structural forms can effectively minimize the impact of temperature variations on the system. Building on these findings, we developed the ultra-wide temperature difference athermalization VLWIR multifunctional imaging spectrometer, which boasts a temperature variation range over 200 K. This versatile instrument features a multifunctional mode that can be easily tuned to meet a range of observation missions. The spectrometer has a spectral range of 12µm to 16µm, a field of view (FoV) of 16.8mm×6mm, a numerical aperture (NA) of 0.334, an alignment temperature of 293.15 K, and an operating temperature of 60 K. The analysis results demonstrate the many working modes and high imaging quality of the designed imaging spectrometer. This paper’s research offers a fresh approach for low-temperature VLWIR imaging spectrometer systems.