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|Advanced Airborne Hyperspectral Imaging System 3 (AAHIS-3)|
STI Government Systems has a general-purpose, high-resolution, passive hyperspectral sensor called AAHIS-3. The AAHIS sensor, initially developed in 1993, is currently in its third generation (AAHIS 3). Successful demonstrations took place at the Fleet Battle Exercise Hotel (FBE Hotel) in 2000 and at the Kernel Blitz in 2001 (KB01). The AAHIS sensor gathers hyperspectral data over the entire visible region and beyond into the NIR. Optimized for operation in littoral areas, the AAHIS-3 operated successfully during a number of diverse remote sensing applications including environmental monitoring, vegetation discrimination, and effluent detection. Other applications of this system have been in military target detection, classification, and identification on land and under water. The AAHIS sensor features a proprietary, state-of-the-art, three-axis navigation and stabilization system with reliable, geo-registered data, independent of aircraft movement. The system provides a fully stabilized 40° view from the aircraft, assuring a large area coverage rate. The system is compact and carried in most fixed- and rotary-wing aircraft with installed optical windows.
SenSyTech developed the Airborne Hyperspectral Scanner (AHS) based on the integration of many advanced technologies under R & D contracts over the past few years. The combination of these components is being offered for the first time, however, each of the individual items has been delivered and field-tested in operational use. The AHS incorporates advanced components to ensure high performance while maintaining the ruggedness to provide operational reliability in a survey aircraft.
The Airborne Imaging System (AIS-1, AIS-2) designed and built in the early '80s as part of a NASA Jet Propulsion Laboratory (JPL) imaging spectrometry program was a testbed for higher resolution imaging spectrometers. It yielded a number of advances in detector technology and data analysis. Rather than using a system of filters and discrete detectors, AIS-1 used a grating spectrometer to separate the signal into 128 contiguous bands in the spectral region from 1.2 to 2.4 um. The spectral resolution of AIS-1 was 9.3 nm, allowing it to clearly detect most surface material absorption features. AIS-1 used a 32x32 element mercury cadmium telluride area detector array. This design permitted a pushbroom-style scan in which the image of each cross track pixel was detected by a specific line of detectors in the area array, eliminating the need for cross track mechanical scanning. The surface pixel size, or spatial resolution, was approximately 8 m from the design altitude of 6 km. The swath size, or region-scanned perpendicular to flight path, was 365 m. AIS-1 became operational in 1984, providing information not only about the earth, but also about the technology of imaging spectrometry. No analysis of the data was performed during collection, but an on site data analysis system was developed for assessment of data quality immediately upon landing. A second generation instrument, AIS-2, imaged over the spectral region from 0.8-2.4 um, with a spectral resolution of 10.6 nm, a larger array, and a significantly higher signal-to-noise ratio.
Airborne Multi-angle Imaging SpectroRadiometer (AirMISR) - JPL
This is an airborne instrument for obtaining multi-angle imagery similar to that of the satellite-borne MISR instrument, which is designed to contribute to studies of the Earth's ecology and climate. AirMISR flies on the NASA-owned ER-2 aircraft. The Jet Propulsion Laboratory in Pasadena, California built it for NASA.
AISA is an airborne hyperspectral sensor designed to provide timely, accurate and reliable information on the Earth’s surface in commercial and scientific applications. It is a versatile tool for acquiring frequent, repetitive measurements. AISA Airborne Hyperspectral Sensor is a complete system that consists of the following basic components:
The pushbroom type AISA sensor head collects hyperspectral data by employing SPECIM’s direct sight imaging spectrograph and high performance camera. The sensor head also includes a fiber optic probe (FODIS) for real time monitoring of downwelling irradiance. The data acquisition unit employs a rugged PC with hot-swap high volume hard disk and bright flat panel display. After collecting data with the AISA system, it is post-processed by CaliGeo in a PC similar to those used for office tasks, without access to UNIX workstations. The output from CaliGeo is a calibrated, rectified and georeferenced hyperspectral image or mosaic. The final image allows discovering a variety of characteristics of the measured target in many advanced data analysis or visualization systems, such as ENVI. AISA Hyperspectral Sensor is for both research and operational use in highly dynamic conditions in the air or in the field. The AISA instrument and its supporting software are very reasonably priced and designed for fast and timely operational remote sensing activities when short turn-around time is required to keep data processing costs down and to achieve the maximum end-user satisfaction. Turn-around time is typically 24 hours from collected data to visualized information.
AIRIS is PSI's ruggedized line of low-order Fabry-Perot interferometers and is specifically designed for multispectral imaging with staring infrared focal plane arrays. The AIRIS technology allows the user to obtain direct monochromatic images at wavelengths specific to the detection task, reducing both data processing and data volume requirements for a variety of multispectral imaging problems.
AIRIS utilizes a Fabry-Perot interferometer operated with mirror spacing less than 20 µm (low order). This configuration results in an expanded free spectral range and angular acceptance while maintaining the high spectral resolution and throughput traditionally associated with the Fabry-Perot device. The free spectral range, transmission, and spectral resolution of the LWIR variant of AIRIS are shown below. Careful selection of materials, a re-entrant thermal design, and mechanically matched mirror mounts results in a system with a high degree of passive thermal and vibrational stability. We have also developed AIRIS with an integrated digital capacitance micrometry system having a 100 µs measurement time. This system, which communicates directly with a PC-ISA bus via a standard full height card, has a positional accuracy of better than 15 nm. Two types of integrated piezoelectric actuators, both under PC-ISA bus control, have been developed to provide a closed-loop positioning and alignment system with wavelength tuning times as low as 1.3 ms. PSI has developed and implemented software to operate AIRIS utilizing the Cincinnati Electronics IRC-DCB2 data collection board and the Amber Engineering 5128C/ProView FPA controller. PSI is committed to supporting the Dipix 12-bit PCI frame grabbers for Amber Radiance, Galileo, and Sentinel FPAs. Systems utilizing small format PC HgCdTe arrays with galvo-scanners have been developed for operation in the LWIR.
(AMSS) Airborne Multispectral Scanner - Geoscan Pty Ltd., Australia
The Airborne Multi-Spectral Scanner ("AMSS") is a mineral mapping system that can survey over 5,000 square kilometers of country per day, providing geologists with a low cost tool for large-scale exploration projects. The system uses 32 spectral channels in the three key spectral regions to maximize mineral differentiation. In 1985 Geoscan Pty Ltd built the 13 channel Mk I AMSS to improve the efficiency and reduce the cost of its mineral exploration activities and to gain access to joint venture projects. The system proved an early success by identifying a number of mineral deposits that convinced the company to build the 24 channel Mk II system in 1989. Geoscan was a subsidiary of the public listed resource company Carr Boyd Minerals Limited which was acquired by Ashton Mining Limited ("Ashton") in 1990. In 1995 STS acquired both the Mk I and II systems from Ashton and has extensively improved the latter, including the addition of another 8 channels to create a 32-channel instrument. The system is flown in survey aircraft at around 3,000 meters (A.G.L.) collecting images in the three spectral regions of visible/near infrared, shortwave infrared and the thermal infrared. Multiple channels are strategically set in each spectral region to provide maximum discrimination of mineral targets while the number of channels has been limited to minimize the high cost of data management and processing. The system is mounted on a state of the art stabilization platform that prevents geometric distortions caused by the aircraft's roll, pitch, yaw and drift. The data can be displayed and monitored as it is acquired which is particularly useful for short-lived events such as fires and oil spills. The acquired raw data may also be analyzed as soon as it is collected from the aircraft while optional atmospheric backscatter and geometric correction require only minimal processing. These features enable the user to ensure quality data has been secured before departing a survey area.