Downward-looking infrared for vehicle-mounted mine detection

Abstract

Vehicle-mounted detection (VMMD) systems currently under development depend heavily on ground penetrating radar (GPR) for detection of buried mines. GPR is supported by electro- magnetic induction (EMI) sensors for detection of metal- cased mines, and by forward-looking infrared (FLIR) imagers for detection of surface mines. However, GPR is often subject to unacceptably high false alarm rates due to the presence of naturally occurring anomalies such as surface irregularities and spatial discontinuities below the surface (e.g., variation in soil compaction or moisture content). Thus, there is a need to rely more heavily on EMI and infrared sensors for detection of buried metal and plastic- cased mines. The conventional approach to IR detection is a roof-mounted forward-looking infrared imager (FLIR), viewing a trapezoidal region of front of the vehicle. This approach is subject to several important limitations. First, boresight tolerance, vehicle attitude variation, and terrain undulation limit registration of IR detections with those of the down-looking GPR and EMI sensors. Second, the images of the mine surface thermal effects are foreshortened by the oblique viewing angle and subject to obscuration and distortion by surface heigh variation. Third, the redundant nature of the FLIR framing process makes the data rate unnecessarily high. This paper will discuss an alternate approach, based on an array of discrete, down-looking infrared detectors that are co-located with the GPR antennas and EMI coils. The advantages of this approach, design of a breadboard sub- array, and preliminary test results will be described.