Radiant energy – Infrared-to-visible imaging – Including means for scanning field of view
Patent
1989-01-04
1990-08-21
Hannaher, Constantine
Radiant energy
Infrared-to-visible imaging
Including means for scanning field of view
2503381, 2503383, 250341, 324158R, G01N 2100
Patent
active
049508970
ABSTRACT:
A thermal wave three-dimensional imaging and tomography apparatus and a thermal wave detector therefor are provided. The apparatus includes a light source for generating a laser beam which is modulated and then focussed onto one side of a solid test material. A thin pyroelectric polymer electret (.beta.-PVDF) film having an electroded upper surface and an electrodeless lower surface supports the other side of the test material on its electroded surface. A single thin metal elongate pin or an array of thin metal elongate pins are disposed beneath the electrodeless lower surface. The pin or pins generate(s) signals upon detection of thermal waves passing through the solid test material resulting from the laser excitation due to the photopyroelectric (P.sup.2 E) effect. Since the pins are small, the signals generated by the pins represent local thermal wave progagation through the test material. The laser beam and the test material are moved relative to one another so that the laser beam scans substantially the entire one side of the test material. When using a single pin, the pin is moved with respect to the other side of the test material so that the pin scans the other side of the film to detect local thermal wave propagation through the test material during the entire scan of the laser beam on the test material. When using an array of pins, the array of pins remains stationary with respect to the other side of the material during the scan of the laser beam on the test material. The resulting signals generated by the pins during the laser beam scan are conveyed to a micro-computer via signal conditioning circuitry wherein a three-dimensional image of the test material subsurface structure is formed.
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Mandelis Andreas
Mieszkowski Marek
Hannaher Constantine
University of Toronto - Innovations Foundation
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