When the laser hits a solid, homogenous area, heat diffuses radially at a predictable rate. However, when the laser beam crosses an open hot crack, the thermal conductivity drops drastically. Air gaps act as insulators.
FLT is primarily a surface or near-surface technique. If the hot crack is buried under a solid layer of metal, the thermal signal is dampened. flt cracks hot
refers to the use of high-precision laser beams—either for excitation (active thermography) or scanning (laser confocal microscopy)—to inspect surfaces and sub-surfaces for defects. When we talk about "flt cracks hot," we are usually referring to two specific processes: When the laser hits a solid, homogenous area,
Software algorithms analyze the thermal decay curve. A healthy area shows a smooth exponential decay. A cracked area with the "flt cracks hot" signature shows a bifurcation or a retained thermal peak. FLT is primarily a surface or near-surface technique
No discussion of “hot cracks” is complete without warnings: