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Proceedings Paper

Toward DMD illuminated spatial-temporal modulated thermography
Author(s): Joshua D. Pribe; Srinivas C. Thandu; Zhaozheng Yin; Edward C. Kinzel
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Paper Abstract

This paper reports on a system using a Digital Micromirror Device (DMD) to modulate a near-infrared laser source spatially and temporally. The DMD can produce an arbitrary heat source varying both spatially and temporally over the target. When the thermal response of the target surface is recorded using a thermal imager, this provides new possibilities in subsurface defect detection, partially with regard to features whose orientation does not allow them to be resolved using conventional thermographic inspection techniques. In this respect it is similar to conventional focused spot detection approaches; however, the DMD allows the signal to be frequency/phase multiplexed which provides for simultaneous interrogation over a large area. The parallel nature of the process permits a longer inspection time at each point which has signal-to-noise benefits. Preliminary experiments demonstrating the multiplexing approach are presented using a low-cost thermal imager. A NIR laser is spatially and temporary modulated to generated multiple thermal line sources on the surface of a composite circuit board. The infrared response is demodulated point-by-point at each drive frequency. This permits the thermal response from each line source to be resolved individually. Beyond damage detection the approach also has applications to system identification. Initial limitations due to the test setup are discussed along with future system improvements.

Paper Details

Date Published: 11 May 2016
PDF: 7 pages
Proc. SPIE 9861, Thermosense: Thermal Infrared Applications XXXVIII, 98610Z (11 May 2016); doi: 10.1117/12.2223859
Show Author Affiliations
Joshua D. Pribe, Missouri Univ. of Science and Technology (United States)
Srinivas C. Thandu, Missouri Univ. of Science and Technology (United States)
Zhaozheng Yin, Missouri Univ. of Science and Technology (United States)
Edward C. Kinzel, Missouri Univ. of Science and Technology (United States)

Published in SPIE Proceedings Vol. 9861:
Thermosense: Thermal Infrared Applications XXXVIII
Joseph N. Zalameda; Paolo Bison, Editor(s)

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