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The Aerospace Corporation’s sensitive Mako thermal infrared imaging spectrometer, which operates between 7.6 and 13.2 microns at a spectral sampling of 44 nm, and flies in a DeHavilland DHC-6 Twin Otter, has undergone significant changes over the past year that have greatly increased its performance. A comprehensive overhaul of its electronics has enabled frame rates up to 3255 Hz and noise reductions bringing it close to background-limited. A replacement diffraction grating whose peak efficiency was tuned to shorter wavelength, coupled with new AR coatings on certain key optics, has improved the performance at the short wavelength end by a factor of 3, resulting in better sensitivity for methane detection, for example. The faster frame rate has expanded the variety of different scan schemes that are possible, including multi-look scans in which even sizeable target areas can be scanned multiple times during a single overpass. Off-nadir scanning to ±56.4° degrees has also been demonstrated, providing an area scan rate of 33 km2/minute for a 2-meter ground sampling distance (GSD) at nadir. The sensor achieves a Noise Equivalent Spectral Radiance (NESR) of better than 0.6 microflicks (μf, 10-6 W/sr/cm2/μm) in each of the 128 spectral channels for a typical airborne dataset in which 4 frames are co-added. An additional improvement is the integration of a new commercial 3D stabilization mount which is significantly better at compensating for aircraft motions and thereby maintains scan performance under quite turbulent flying conditions. The new sensor performance and capabilities are illustrated.

A new airborne thermal infrared imaging spectrometer, "Mako", with 128 bands in the thermal infrared covering 7.8 to 13.4 microns, has recently completed its engineering flight trials. Results from these flights, which occurred in September 2010 and included two science flights, are presented. The new sensor flies in a Twin Otter aircraft and operates in a whiskbroom mode, giving it the ability to scan to ±40° around nadir. The sensor package is supported on a commercial 3-axis-stabilized mount which greatly reduces aircraft-induced pointing jitter. The internal optics and focal plane array are operated near liquid helium temperatures, which in conjunction with a fast f/1.25 spectrometer enables low noise performance despite the sensor's small (0.55 mrad) pixel size and the high frame rate needed to cover large whisk angles. Besides the large-area-coverage scan mode (20 km2 per minute at 2-meter GSD from 12,500 ft. AGL), the sensor features a scan mirror pitch capability that enables both a high-sensitivity mode (longer integration times using frame summing, covering a smaller spatial region) and a multiple-look mode (multiple looks at a smaller region in a single aircraft overpass, for discriminating plume motion, for example).

We report progress on a high-performance, long-wavelength infrared hyperspectral imaging system for airborne research. Based on a f/1.25 Dyson spectrometer and 128x128 arsenic doped silicon blocked impurity band array, this system has significantly higher throughput than previous sensors. An agile pointing/scanning capability permits the additional signal to be allocated between increased signal-to-noise and broader area coverage, creating new opportunities to explore LWIR hyperspectral phenomenology.

The Dyson spectrometer form is capable of providing high throughput, excellent image quality, low spatial and spectral distortions, and high tolerance to fabrication and alignment errors in a compact format with modest demands for weight, volume, and cooling resources. These characteristics make it attractive for hyperspectral imaging from a space-based platform. After a brief discussion of history and basic principles, we present two examples of Dyson spectrometers being developed for airborne applications. We conclude with a concept for an earth science instrument soon to begin development under the Instrument Incubator Program of NASA's Earth Science Technology Office. Keywords: remote sensing, imaging spectroscopy, hypersp ectral imaging, infrared, concentric spectrometer 1. INTRODUCTION Concentric optical systems with 1:1 magnification, such as the Offner and Dyson forms, are known to be well suited to imaging spectrometric applications by virtue of their simplicity and low intrinsic aberrations. Both were first proposed for high numerical aperture imaging of fine spatial features for microlithography

In order to measure the effect of rocket exhaust on stratospheric ozone and aerosol profiles, it is necessary to deploy a space-based mid-UV spectrograph capable of making measurements at high spatial resolution (1 - 2 km) of the intensity and state of polarization of solar light backscattered by the atmosphere. This paper describes the design of an instrument called HIROIG (high resolution ozone imager) which is expected to be deployed in a sun synchronous orbit sometime after 1995. The instrument consists of three identical spectrographs, each one sensitive to light polarized in one direction. Each spectrograph uses a frame-transfer CCD which images the entire 270 - 370 nm spectrum at approximately equals 1 nm spectral resolution. Images re exposed, in the push broom mode, for 140 msec, providing an effective spatial resolution of better than 2 km for typical orbital velocities. The HIROIG field of view is 1000 km cross-track. A ground-based prototype consisting of a single spectrograph has been constructed and the characterization of this instrument is discussed.

The RAIDS experiment consists of eight instruments spanning the wavelength range from the extreme ultraviolet (55 nm) to the near infrared (800 nm) oriented to view the Earth's limb from the NOAA-J spacecraft to be launched into a circular orbit in 1993. Through measurements of the natural optical emissions and scattered sunlight origmating in the upper atmosphere including the mesosphere and thermosphere, state variables such as temperature, composition, density and ion concentration of this region will be inferred. This paper describes the subset of instruments fabricated or otherwise provided by the Space and Environment Technology Center (formerly Space Sciences Laboratory) at The Aerospace Corp. The companion to this paper describes the instruments from the Naval Research Laboratory. The Extreme Ultraviolet Spectrograph (EUVS), the three fixed filter photometers 0! (630), 0! (777), and Na (589), and the near infrared spectrometer (NIR) will be described. These are all mounted on a mechanical scan platform that scans the limb from approximately 75 to 750 km in the orbital plane of the satellite every 90 seconds.