Time-resolved videothermography at above-frame-rate frequencies

Steven M. Shepard; David T. Sass; Thomas P. Imirowicz; A. Meng

doi:10.1117/12.46437

1 March 1991 Time-resolved videothermography at above-frame-rate frequencies

Steven M. Shepard, David T. Sass, Thomas P. Imirowicz, A. Meng

Proceedings Volume 1467, Thermosense XIII; (1991) https://doi.org/10.1117/12.46437
Event: Orlando '91, 1991, Orlando, FL, United States

Abstract

Temporal aliasing is a problem common all video imaging systems. IR video systems are particularly susceptible because of the relatively low (30 Hz) RS-170 frame rate. We have developed a system which compensates for the effects of aliasing, and allows images of repetitive thermal phenomena at frequencies up to 4 kHz to be acquired. The system utilizes an unmodified commercial imager (Inframetrics IR 600) and a microcomputer. Data is acquired selectively using a 'line-by-line' scheme which compares the motion of the camera's horizontal scanning mirror to a reference signal correlated to the event of interest. Only those horizontal lines that have a user-specified phase relationship to the reference signal are acquired. The resulting images have an effective integration time of 125 microseconds. This ability to acquire 'time-resolved' IR images allows investigation of phenomena not possible with a conventional RS-170 IR imaging system. For example, a conventional thermal image of an integrated circuit operating at several kilohertz yields no temporal information whatsoever. By comparison, we have acquired time-resolved images which show the AC heating and cooling of the circuit, so that we may identify AC hot spots. The system has also been applied to a running internal combustion engine. The imager views the piston head through an IR transparent (ZnS) window. Acquired images clearly show the motion of the flame front through the combustion chamber, and the subsequent heating and cooling of the piston head.

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Steven M. Shepard, David T. Sass, Thomas P. Imirowicz, and A. Meng "Time-resolved videothermography at above-frame-rate frequencies", Proc. SPIE 1467, Thermosense XIII, (1 March 1991); https://doi.org/10.1117/12.46437

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KEYWORDS

Imaging systems

Thermography

Infrared imaging

Head

Video

Combustion

Transistors

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