Laser scanning thermal probe: A novel approach to NDE

Infrared (IR) thermography and, more recently, thermosonics have proven to be viable means of qualitative nondestructive evaluation (NDE). However, structural defects such as cracks observed through thermosonics can only be identified as "hot spots" indicating a general location of a defect without an accurate depiction of the dimensions or shape of the defect. This paper introduces a new technique dubbed Laser Scanning Thermal Probe, LSTP, which combines thermography with the use of heat application in strategic locations to observe the spatial heat flow patterns. LSTP provides the ability to record heat propagation across a defect area with temperature discontinuities forming due to differences in defect thermal diffusivity, thus providing information which can be used to characterize the defect such as crack length.