IR TIIERMAL WA VE TOMOGRAPHIC STUDIES OF STRUcruRAL COMPOSITES

Vavilov et al [1] have recently described a technique for making tomographie thermal wave images. Their method involves recording a succession of thermal wave images after a flash-heating pulse, followed by a numerical pixel-by-pixel search of the images for the time at which the reflected thermal waves from subsurface features have their peak amplitudes. Since the peak time is related to the depth of the scatterer, this information enables one to separate the image into time (or depth) slices. The result is athermal wave tomogram. Since their process involves post-processing and a search through a large number of stored images, it is memory-intensive, and is difficult to accomplish in real time. In the present paper, we report a thermal wave tomographic method which accomplishes the same result, but does so with real-time techniques which avoid the storage of a large number of images, and produces the tomogram without post-processing. DESCRWI10N OF THE TECHNIQUE The tomographic method we describe is based on wide area pulse heating (e.g. by flashlamps) of the sample's surface. Experimental curves showing the time dependence of the surface temperature of a sampie following such pulse heating are shown in Fig. 1. Thes