The Ultra-Compact Imaging Spectrometer Moon (UCIS-Moon) instrument is a pushbroom shortwave infrared (SWIR) imaging spectrometer prototype developed at NASA’s Jet Propulsion Laboratory (JPL), California Institute of Technology under the Development and Advancement of Lunar Instrumentation (DALI) program. It is designed for integration with a lander or rover for lunar surface science missions. Operating over a 0.6 to 3.6 micron spectral range with 10 nm sampling and a 36 degree field of view, UCIS-Moon is capable of detecting spectral absorptions from common lunar materials, OH species, molecular H2O, water ice, organics, and placing mineral identifications within an established geologic context at the cm to m scale. We discuss instrument assembly, alignment, and measured laboratory optical performance, which meets or exceeds the high-uniformity and high-resolution requirements while achieving a wide spectral range, field of view, and environmental tolerance, with limited mass and power resources. As such, the UCIS-Moon imaging spectrometer is well-suited to address key science questions about lunar geology, the abundance, sources, and sinks of volatiles at the Moon, and the distribution of possible in situ resources for future human exploration.
The Visible Mid-wave Dyson Imaging Spectrometer (VMDIS) is a JPL-developed prototype instrument whose main goal is to address three key technical challenges for the next generation of imaging spectrometers for solar system exploration: (1) High signal-to-noise ratio (SNR) measurements for mapping of minerals and volatiles on solar system targets including comets, asteroids, rocky moons, icy moons, and planets especially Mars; (2) Miniaturization for low-cost mission platforms (reducing the size, mass, and power requirements compared to current options); and (3) excellent spectral cross-track and spectral-spatial uniformity required by todays advanced algorithms for rigorous quantitation with uncertainties. The core of VMDIS is the imaging spectrometer instrument: an optically fast F/1.8 Dyson imaging spectrometer covering a spectral range from 600 nm to 3600 nm, with a spectral sampling of 7 nm. Different telescopes can be used with different implementations of VMDIS to tailor the IFOV and FOV of the instrument. With its prototype telescope, the instrument enables a field of view (FOV) of 28°, with an instantaneous FOV of 0.5 milliradians subtended by each 18 μm cross-track pixel. The size of the VMDIS prototype including the telescope and heritage electronics is roughly equal to 3U (3 units – 1 unit measuring approximately 10×10×10 cm), with a mass < 8 kg and payload power < 40 W. With next generation electronics in development this mass falls below 3 kg. We present an overview of the optical, mechanical, and thermal design of VMDIS, which is required to fabricate this instrument within very demanding resource allocations. The design of the signal chain electronics is also detailed. In addition, preliminary alignment, characterization, and calibration measurements, obtained with the instrument operating in relevant space-type environment, are also discussed. While tested with an available 30-μm detector array, VMDIS is designed for a 18-μm digital readout detector array. VMDIS is intended to pave the way for future low-cost, small form factor imaging spectrometers with state-of-the-art performance in terms of combination of spectral range, high throughput, exceptional uniformity, as well as configuration flexibility for both orbital and landed mission, for the next decade and beyond.
The High-resolution Volatiles and Minerals Moon Mapper (HVM3) is a pushbroom shortwave infrared (SWIR) imaging spectrometer developed at NASA’s Jet Propulsion Laboratory (JPL), California Institute of Technology, for the Lunar Trailblazer mission. The mission, a part of NASA’s Small Innovative Missions for Planetary Exploration (SIMPLEx) program, pairs HVM3 with University of Oxford’s Lunar Thermal Mapper (LTM) to determine the form, abundance, and distribution of water on the Moon, while providing a potential reconnaissance opportunity for future landed missions. The HVM3 optical design utilizes heritage from NASA’s Moon Mineralogy Mapper (M3), and maintains a compact form while extending to longer wavelengths. Operating at F/3.4 with a spatial resolution of 70 meters per pixel and a spectral resolution of 10 nm over the 0.6 to 3.6 microns spectral range, HVM3 is optimized for the detection of volatiles to map OH, bound H2O, and water ice at the Moon, including the Moon’s permanently shadowed regions (PSRs). We discuss the optical specifications, optical design, alignment, and initial measured laboratory performance of the HVM3 instrument.
The Snow and Water Imaging Spectrometer (SWIS) is a science-grade imaging spectrometer and telescope system suitable for CubeSat applications, spanning a 350-1700 nm spectral range with 5.7 nm sampling, a 10 degree field of view and 0.3 mrad spatial resolution. The system operates at F/1.8, providing high throughput for low-reflectivity water surfaces, while avoiding saturation over bright snow or clouds. The SWIS design utilizes heritage from previously demonstrated instruments on airborne platforms, while advancing the state of the art in compact sensors of this kind in terms of size and spectral coverage. Through frequent repeat observations from space at a moderate spatial resolution, SWIS can address key science questions concerning aquatic and terrestrial ecosystem changes, cryosphere warming and melt behavior, cloud and atmospheric science, and potential impacts of climate change and human activities on the environment. We review the optical design and innovations and key technologies developed for this instrument, as well as its measured optical performance. We discuss the radiometric calibration characterization, including detector linearity, flat field correction, and SNR. Finally, we discuss stray light modeling and the development of a focused ghost removal algorithm, which is tested and supported by laboratory results.
We discuss detailed tolerancing methods developed for imaging spectrometers at NASA Jet Propulsion Laboratory, California Institute of Technology using the Earth Surface Mineral Dust Source Investigation (EMIT) imaging spectrometer as an illustrative example. We tolerance five metrics simultaneously: along-track response function, crosstrack response function, spectral response function, spectral centroid uniformity, and spatial centroid uniformity. A method to calculate tolerancing sensitivities for each metric directly, a method to statistically combine Monte Carlo files from multiple tolerancing runs, and example summary error budgets that communicate the key and driving tolerances for each metric are discussed. These methods facilitate rapid and semi-automated assessment of the predicted performance of imaging spectrometer systems from design through to assembly and launch life cycle, using metrics that are directly relevant to the extraction of accurate spectroscopic data from these instruments.
The Mapping Imaging Spectrometer for Europa (MISE) is a high-throughput pushbroom imaging spectrometer designed for NASA’s planned flyby mission to Jupiter’s moon Europa. The MISE design utilizes heritage from previously demonstrated instruments on airborne platforms, while advancing the state of the art to operate within Europa’s challenging environment. The instrument operates at F/1.4 and covers a spectral range from 0.8 to 5 microns with 10 nm spectral sampling. Through high resolution mapping, MISE is designed to identify distributions of organics, salts, acid hydrates, water ice phases, altered silicates, radiolytic compounds, and warm thermal anomalies at global, regional, and local scales. Such distribution maps will help study surface and subsurface geologic processes, and assess the habitability of Europa’s ocean. We discuss the optical specifications and baseline performance of the MISE optical design.
The Snow and Water Imaging Spectrometer (SWIS) is a science-grade imaging spectrometer designed for CubeSat integration, spanning a 350- to 1700-nm spectral range with 5.7-nm sampling, a 10-degree field-of-view, and 0.3-mrad spatial resolution. The system operates at F / 1.8, providing the high throughput for low-reflectivity (<1 % ) water surfaces, while avoiding saturation over bright snow or clouds. The SWIS design utilizes heritage from previously demonstrated instruments on airborne platforms while advancing the state of the art in compact sensors of this kind in terms of size and spectral coverage. Compared with airborne campaigns, the CubeSat platform allows for more frequent and regular sampling, while maintaining intermediate to high resolution relative to heritage global sensors. Through frequent repeat observations from space at a moderate spatial resolution, SWIS can address key science questions concerning aquatic and terrestrial ecosystem changes, cryosphere warming and melt behavior, cloud and atmospheric science, and potential impacts of climate change and human activities on the environment.
The Snow and Water Imaging Spectrometer (SWIS) is a science-grade imaging spectrometer and telescope system suitable for CubeSat applications, spanning a 350-1700 nm spectral range with 5.7 nm sampling, a 10 degree field of view and 0.3 mrad spatial resolution. The system operates at F/1.8, providing high throughput for low-reflectivity water surfaces, while avoiding saturation over bright snow or clouds. The SWIS design utilizes heritage from previously demonstrated instruments on airborne platforms, while advancing the state of the art in compact sensors of this kind in terms of size and spectral coverage. We provide an overview of the preliminary spacecraft configuration design for accommodation in a 6U CubeSat platform.
The Snow and Water Imaging Spectrometer (SWIS) is a fast, high-uniformity, low-polarization sensitivity imaging spectrometer and telescope system designed for integration on a 6U CubeSat platform. Operating in the 350-1700 nm spectral region with 5.7 nm sampling, SWIS is capable of simultaneously addressing the demanding needs of coastal ocean science and snow and ice monitoring. New key technologies that facilitate the development of this instrument include a linear variable anti-reflection (LVAR) detector coating for stray light management, and a single drive on-board calibration mechanism utilizing a transmissive diffuser for solar calibration. We provide an overview of the SWIS instrument design and potential science applications and describe the instrument assembly and alignment, supported by laboratory measurements.
The Snow and Water Imaging Spectrometer (SWIS) is a fast, high-uniformity, low-polarization sensitivity imaging spectrometer and telescope system designed for integration on a 6U CubeSat platform. Operating in the 350-1700 nm spectral region with 5.7 nm sampling, SWIS is capable of simultaneously addressing the demanding needs of coastal ocean science and snow and ice monitoring. New key technologies that facilitate the development of this instrument include a linear variable anti-reflection (LVAR) detector coating for stray light management, and a single drive on-board calibration mechanism utilizing a transmissive diffuser for solar calibration. We provide an overview of the SWIS instrument design, spacecraft configuration design, and potential science missions.
This paper describes the design of a high-throughput and high-uniformity pushbroom imaging spectrometer and telescope system that is capable of Landsat swath and resolution while providing better than 10 nm per pixel spectral resolution over the full visible to short-wave infrared band. The design is based on a 3200×480 element×18 μm pixel size focal plane array, two of which are utilized to cover the full swath. At an optical speed of F/1.8, the system is the fastest proposed to date to our knowledge. The utilization of only two Dyson-type spectrometer modules fed from the same telescope reduces system complexity while providing a solution within achievable detector technology. Two telescope designs are shown to achieve the required swath and resolution from different altitudes. Predictions of complete system response are shown. Also, it is shown that detailed ghost analysis is a requirement for this type of spectrometer and forms an essential part of a complete design.
We describe the design of a high-throughput pushbroom imaging spectrometer and telescope system that is capable of Landsat swath and resolution while providing better than 10 nm per pixel spectral resolution. The design is based on a 3200 x 480 element x 18 μm pixel size focal plane array, two of which are utilized to cover the full swath. At an optical speed of F/1.8, the system is the fastest proposed to date to our knowledge. The utilization of only two spectrometer modules fed from the same telescope reduces system complexity while providing a solution within achievable detector technology. Predictions of complete system response are shown. Also, it is shown that detailed ghost analysis is a requirement for this type of spectrometer and forms an essential part of a complete design.
The Snow and Water Imaging Spectrometer (SWIS) is a fast, high-uniformity, low-polarization sensitivity imaging spectrometer and telescope system designed for integration on a 6U CubeSat platform. Operating in the 350-1700 nm spectral region with 5.7 nm sampling, SWIS is capable of simultaneously addressing the demanding needs of coastal ocean science and snow/ice monitoring. We discuss progress in the SWIS optomechanical design, thermal analysis, and mission plan. We also describe an innovative single drive on-board calibration system capable of addressing the stringent radiometric stability and knowledge these missions require. The spectrometer features a new Teledyne CHROMA array, optimized for high temperature operation, with a linear variable anti-reflection coating to enhance quantum efficiency and minimize backscatter.
We report on the design, tolerancing, and laboratory breadboard of an imaging spectrometer for the Earth Science Decadal Survey Hyperspectral and Infrared Imager (HyspIRI) mission. The spectrometer is of the Offner type but with a much longer slit than typical designs, with 1600 resolvable spatial elements along the slit for a length of 48 mm. Two such spectrometers cover more than the required swath while maintaining high throughput and signal-to-noise thanks to the large pixel size (30 μm), relatively high speed (F/2.8) and small number of reflections. We also demonstrate a method for measuring smile using a linear array, and use the method to prove the achievement of negligible smile of less than 2% of a pixel over the entire 48 mm slit. Thus we show that this high-heritage, all-spherical mirror design can serve the requirements of the HyspIRI mission.
Imaging spectrometers require precise adjustments, in some cases at the sub-micrometer level, in order to achieve a
uniform response over both the spectral and spatial dimensions. We describe a set of measurement techniques and their
corresponding alignment adjustments to achieve the 95% or higher uniformity specifications required for Earthobserving
imaging spectrometers. The methods are illustrated with measurements from the Next Generation Imaging
Spectrometer system that has been built at the Jet Propulsion Laboratory, California Institute of Technology, under
contract with the National Aeronautics and Space Administration.
We describe the optical design and performance of the Next-Generation airborne Imaging Spectrometer (NGIS)
currently being constructed at Caltech's Jet Propulsion Laboratory. The new, high-resolution instrument incorporates a
number of design advantages including a two-mirror anastigmatic telescope for simplified alignment and high
throughput, as well as a concentric, multi-blazed grating for tailored broadband efficiency. A detailed tolerancing and
sensitivity approach reveals tight requirements that must be satisfied for spectral calibration and boresight stability. This
improved spectral and pointing stability, combined with high uniformity and high signal-to-noise ratio allows us to
generate spectrometry measurements capable of answering challenging science questions.
Three different techniques for extending the depth of field of a low-power (4x) microscope objective system are examined experimentally: wavefront coding with a cubic phase mask, amplitude modulation with a large central obscuration, and added spherical aberration. Their relative merits are discussed and demonstrated with sample images.
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