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The Wedge Imaging Spectrometer (WIS) represents a novel implementation of an imaging spectrometer sensor that is compact and rugged and, therefore, suitable for use in drug interdiction and pollution monitoring activities. With performance characteristics equal to comparable conventional imaging spectrometers, it would be capable of detecting and identifying primary and secondary indicators of drug activities and pollution events. In the design, a linear wedge filter is mated to an area array of detectors to achieve two-dimensional sampling of the combined spatial/spectral information passed by the filter. As a result, the need for complex and delicate fore optics is avoided, and the size and weight of the instrument are approximately 50% that of comparable sensors. Spectral bandwidths can be controlled to provide relatively narrow individual bandwidths over a broad spectrum, including all visible and infrared wavelengths. This sensor concept has been under development at the Hughes Aircraft Co. Santa Barbara Research Center (SBRC), and hardware exists in the form of a brassboard prototype. This prototype provides 64 spectral bands over the visible and near infrared region (0.4 to 1.0 micrometers ). Implementation issues have been examined, and plans have been formulated for packaging the sensor into a test-bed aircraft for demonstration of capabilities. Two specific areas of utility to the drug interdiction problem are isolated: (1) detection and classification of narcotic crop growth areas and (2) identification of coca processing sites, cued by the results of broad-area survey and collateral information. Vegetation stress and change-detection processing may also be useful in detecting active from dormant airfields. For pollution monitoring, a WIS sensor could provide data with fine spectral and spatial resolution over suspect areas. On-board or ground processing of the data would isolate the presence of polluting effluents, effects on vegetation caused by airborne or other pollutants, or anomalous ground conditions indicative of buried or dumped toxic materials.
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