Detection of buried objects using thermal infrared imaging.

摘要

Thermal infrared images of the surface of the ground provide information about the near surface physical state of geologic materials. So, if an object is buried close to the surface of the ground, the temperature contours will show on the thermal infrared image, especially when surface temperature changes or the radiation flux on the surface changes. This is due to a buried object's different thermal properties when they transmit their thermal imprints to the immediate surface of the ground differently than the other area. The advantage of thermal infrared imaging techniques is that they yield information on the depth and topographical shape as well as the material composition of a buried object and thus have great potential for location and highly accurate identification of the object.;In this work, we seek to systematically examine, both theoretically and experimentally, all the factors that characterize the surface thermal imprints and their relationships to (i) the buried objects and their geometric and thermal characteristics, (ii) their distance from the surface and the soil medium in which they are buried, and (iii) the surrounding heating and cooling of the surface. Based on a comprehensive examination and understanding of these factors and the possibilities they present, we set up a system for close-in detection of select buried objects.;We discussed the use of the diurnal solar cycle and an artificial step function radiation heating and cooling of a sand surface to detect the presence of buried objects. The mathematical models of temperature distribution on the surface of the ground buried with a semi-infinite and finite object underneath, heated and cooled by either a diurnal solar cycle or an artificial step function radiation source were studied and developed. Numerical simulations and experimental works characterizing the surface thermal imprints of the different materials of objects with different buried depth were carried out showing the capabilities of thermal infrared imaging for detecting the buried objects. The further works of data and image processing demonstrated the capability of both further enhancement in sensitivity and increased detection speed.