Title: The Hyperspectral Thermal Emission Spectrometer (HyTES): preliminary results
Author: Simon Hook
Organization: NASA/Jet Propulsion Laboratory
Co-Authors: William R. Johnson, Bjorn T. Eng, Sarath D. Gunapala, Andrew U. Lamborn, Pantazis Z. Mouroulis, Christopher G. Paine, Alexander Soibel, Daniel W. Wilson
The Hyperspectral Thermal Emission Spectrometer (HyTES) is being developed as part of the risk reduction activities associated with the Hyperspectral Infrared Imager (HyspIRI). HyspIRI is one of the Tier 2 Decadal Survey Missions. HyTES will provide information on how to place the filters on the HyspIRI Thermal Infrared Instrument (TIR) as well as provide antecedent science data. The pushbroom design has 512 spatial pixels over a 50-degree field of view and 256 spectral channels between 7.5mm to 12mm. HyTES includes many key enabling state-of-the-art technologies including a high performance convex diffraction grating, a quantum well infrared photodetector (QWIP) focal plane array, and a compact Dyson-inspired optical design. The Dyson optical design allows for a very compact and optically fast system (F/1.6). It also minimizes cooling requirements due to the fact it has a single monolithic prism-like grating design which allows baffling for stray light suppression. The monolithic configuration eases mechanical tolerancing requirements which are a viable concern since the complete optical assembly is operated at cryogenic temperatures (~100K). The QWIP allows for optimum spatial and spectral uniformity and provides adequate responsivity or D-star to allow 200mK noise equivalent temperature difference (NEDT) operation across the LWIR passband. Assembly of the system is nearly complete. Alignment results will be presented which show low keystone and smile distortion. This is required to minimize spatial-spectral mixing between adjacent spectral channels and spatial positions. Preliminary results show the system has adequate signal to noise for laboratory calibration targets.