A study of the photothermal effect induced by an ir laser impulse

In this article, we study the spatial and temporal IR distribution of the temperature in an absorbant material, while periodically exposing it to IR luminescent radiation. We compare our results with those obtained experimentally from semiconductor materials. An understanding of the form of the signal permits us to determine the ratio of the penetration depth of the IR radiation to the thermal diffusion length into the material. In the case of weak concentration of absorbant impurities in a homogeneous material, the thermal properties are slightly modified and absorption is proportional to concentration. With this method, we satisfactorily found it possible to determine the rate of the impurities distributed in the material.