Subsurface Flaw Detection In Reflective Materials By Thermal-Transfer Imaging

Abstract

A thermal-imaging apparatus is disclosed for the nondestructive detection of subsurface defects in materials which would not usually lend themselves to thermal imaging because of their low emissivity and high susceptibility to background reflection noise. This is accomplished by transferring the thermal image produced by surface temperature perturbation of ABSTRACT A thermal-imaging apparatus is disclosed for the nondestructive detection of subsurface defects in materials which would not usually lend themselves to thermal imaging because of their low eraissivity and high susceptibility to background reflection noise. This is accomplished by transferring the thermal image produced by surface temperature perturbation of the workpiece material to a high-emissivity material with which it is continuously brought in contact.The transferred thermal image may be observed by a suitable infrared device resulting in a high-radiance image with minimum reflectivity or variable emissivity noise.Numerical simulations, as well as experimental results, are presented.