Photothermal Study of Anisotropic Media
Photothermal techniques are based on the illumination of the sample under study by a modulated light beam (pump beam). In absorbing media, light is converted into heat and induces thermal waves within the sample. This heat flow produces a refractive index gradient in the adjacent air medium, close to the sample surface. In the probe beam deflection technique , a second laser beam is directed through the heated region and is deflected by the mirage effect. The analysis of this deflection gives the temperature distribution in the sample and information about its thermal properties. The 3d photothermal deflection has been extensively reported in the literature for isotropic media  but only a few results are related to anisotropic ones .