THERMAL-WAVE IMAGING FOR AGING AIRCRAFT INSPECTION

A new technique of thermal wave imaging uses pulses of heat to interro gate subsurface features in solid objects. These pulses propagate into the object as thermal waves, are reflected from subsurface defects, a nd return to the surface as thermal wave ''echoes.'' These echoes can be detected by the use of infrared video cameras coupled to appropriat e electronic hardware and software. The pattern of these echoes on the surface of the object can be used to image subsurface corrosion and d isbonds in aircraft skins. In this paper, aging aircraft applications of pulse-echo thermal wave imaging are described.