Patent ID: 7937240

Claim:
A method for characterizing a block of material using active pyrometry, said block of material comprising at least two superposed layers, a superficial layer of small thickness disposed on a thick substrate, said superficial layer being brought to a predetermined initial temperature, the method comprising the steps of: heating at least one predetermined area of a surface of said superficial layer of said block of material using a salvo of laser pulses and selecting said laser pulses with sufficiently high repetition frequency and sufficiently short duration so that said superficial layer of said block of material undergoes a plurality of thermal cycles consisting of a rapid temperature increase when the surface of said superficial layer is exposed to said laser pulses followed by a slow temperature decrease between two laser pulses in which the surface of said superficial layer is not allowed to return to said predetermined initial temperature, and for the surface of said superficial layer to accumulate heat from one thermal cycle to the next; collecting all or part of thermal radiation emitted by the surface of said superficial layer of said block of material; measuring at least part of said thermal radiation collected using a sensor; determining temperature of the surface of said superficial layer from said thermal radiation measured by said sensor and processed by a signal acquisition and processing system; analyzing predetermined heating and cooling time regimes by comparing measurements acquired by the signal acquisition and processing system with theoretical values given by a heat equation adapted to the physical characteristics of said block of material, and matching series of measured and theoretical values by varying at least one physical parameter associated with said block of material, so as to derive predetermined thermophysical properties of said block of material for characterizing said superficial layer.