Random photothermal thermography: Principle and examples of applications

The photothermal thermography is a procedure of non-destructive control which finds numerous applications in the field of the control and characterization of the thin materials. This technique is classically implemented under CW excitation or under flash analysis (crenel). In our laboratory, we looked, just like what we had made in punctual photothermal radiometry, to implement it under random excitation. This last technique seems to allow indeed, with regard to the previous ones, the control of more fragile materials as well as the access to extend multi frequencies analysis. Having reminded the principle of the random photothermal thermography and having presented an example of experimental device, we show that the method allows under lesser energy constraints, on one hand the detection of detachments situated in mural paintings and on the other hand, detection of a defect situated in a block of plaster while leading only a weak rise of temperature.