Military targets such as aircrafts and flares do not exhibit unique infrared signatures; their emissions are dominated by
combustion products (mostly water vapor, carbon dioxide and hydrogen chloride) and hot metal greybody emissions.
An algorithm has thus been developed to categorize target signatures based on their emission source components. The
signatures are then partitioned, based on their emission components, into groups of similar emission characteristics.
Using previous trial data, seven unique flare categories were defined. A second algorithm was finally developed to
exploit this signature description and interrogate individual field measurements for target detection and categorization.
DRDC Valcartier is continuing to developed infrared spectral imagery systems for a variety of military applications.
Recently a hybrid airborne spectral imager / broadband imager system has been developed for ground target
interrogation (AIRIS). This system employs a Fourier Transform Interferometer system coupled to two 8x8 element
detector arrays to create spectral imagery in the region from 2.0 to 12 microns (830 to 5000 cm-1) at a spectral resolution
of up to 1 cm-1. In addition, coupled to this sensor are three broadband imagers operating in the visible, mid-wave and
long-wave infrared regions. AIRIS uses an on-board tracking capability to: dwell on a target, select multiple targets
sequentially, or build a mosaic description of the environment around a specified target point. Currently AIRIS is being
modified to include real-time spectral imagery calibration and application processing. In this paper the flexibility of the
AIRIS system will be described, its concept of operation discussed and examples of measurements will be shown.
In June 2005, a newly develop long wave Focal Pane Array (FPA), based on photo-voltaic technology was delivered to
the Defense Research & Development of Canada (DRDC). This development was part of technological Demonstration
program that was founded by the DRDC. This paper will describe the FPA configuration along with its performance
assessment configured in the Air PIRATE FTIR spectrometer. Air PIRATE is an airborne version of the hyper spectral
spectrometer used by the Canadian Defense for target identification, as well as chemical agent identification.
An hyperspectral imager capable of sensing from 1 to 12 micrometers with three (3) possible field-of-views (FOV) steerable within a field-of-regard eight (8) times larger than the FOV is presented. This level of flexibility imposes several constraints on the front-end optics especially when the maximum etendue of the spectrometer must be maintained for all configurations. This paper presents the design approach and trade-offs leading to a high performance optical design. Other constraints such as mass and volume are also considered. An important limiting factor is the size of the window and its minimum distance to the primary mirror of the telescope. The design has been optimized by re-imaging the aperture stop on each component that are critical in size: the interferometer corner cubes, the steering mirror and the primary mirror of the telescope. A set of two (2) telescopes and two (2) afocal relays are interchanged to produce 3 FOVs with optimized etendue and minimum size on critical components.
Design considerations and experimental measurements from an imaging Fourier transform spectrometer are presented. The system is based on the Bomem MB-series of Fourier transform interferometer and is capable of more than 8 frames/second at 4 cm(superscript -1 apodized spectral resolution. The interferometer features dual output beams, allowing for example, the coverage of two different spectral ranges using a short-wave array and a long- wave array. The present system uses a set of two 8 X 8 InSb detector arrays to cover the 2 to 5.3 micrometers spectral range on two coaligned fields of view of 4 mrad X 4 mrad and 1 mrad X 1 mrad. Predicted noise equivalent spectral radiance as well as instrument lineshape are compared to measurements on the actual system. Particular emphasis is devoted to the behavior of the instrument lineshape with respect to off-axis position in the focal plane.
The Electro-Optics division at the Defense Research Establishment Valcartier (DREV) has recently embarked on a program to develop an infrared imaging spectrometer system, a device which combines the properties of a radiometer, a thermal imager, and a spectrometer to permit the simultaneous registration of the following attributes of a distant emission source: its infrared intensity, the spatial distribution of its radiation, the spectral distribution of its energy, and its temporal behavior. The DREV instrument couples existing detector and interferometric technologies to produce a novel capability for the measurement of emissions from distant targets. This is a high-technology-based system incorporating: fast microcomputers to handle, in real-time, the vast quantities of raw data generated; specialized IR detector focal plane arrays capable of working in conjunction with spectral measurement modules; and sophisticated algorithms for processing of the spatially resolved spectral information, and for its presentation in a simple and meaningful form.
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