Lock-In thermography was developed to complement other non-destructive techniques.

It can assist in understanding material heterogeneities or electrical failures (short circuit or leakage).

The load can be of any kind - thermal, electrical or mechanical, and of several types - continuous, pulsed or periodic (lock-in).

With static thermography, surface phenomena or thermal heterogeneities can be measured.

To detect internal inconsistencies within the sample (interface, crack, etc), a thermal flux is created, dynamic system and then its repartition at sample surface is observed.

With Dynamic « lock-in » Infrared Thermography, the mean is very sensitive and « hot spot » of some 10^-3K (or even 10^-4K) is detected.

• The sample receives a periodic load.
• A thermal wave is thus generated into the sample.
• The wave propagates in the sample, and is partially transmitted or reflected at interfaces (as for acoustic waves).
• The system acquires during several periods and compares the loading signal to the thermal signal measured at sample surface.
• As many images are acquired, the sensibility is highly increased.