Random photothermal thermography: Principle and examples of applications

Abstract

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.

Defect detection in mural painting by random infrared thermography associated with singular value decomposition and higher orders statistics

“…The period of analyze is equal to 15 s. The power of excitation is equal to 2 * 500 W. In figure 6, we present two types of photothermal results. The figure 6a corresponds to an ARMA parametric analysis [12][13]. The figure 6b corresponds to a "Kurtosis" analysis.…”

“…It has already been implemented successfully for the analysis of work art. It was then associated with correlation or parametric analysis [12][13]. In this paper, we propose to study the association of the random infrared thermography with other modes of post-treatment.…”