A photothermal microscope devoted to microscopic thermal and thermo-elastic
characterizations is presented. In thermal configuration, the sample is heated by an intensity
modulated laser beam and the periodic temperature increase at the sample surface is
detected using the photoreflectance technique. In thermo-elastic configuration, the periodic
elevation of the sample surface is measured using a Nomarski interferometer. The spatial
resolution is micrometric, the sensivity is better than 10−3 K/$\surd$
Hz in thermal configuration
and 10 pm/$\surd$
Hz in the interferometric one. Typical photoreflectance thermal properties
measurements are performed to evaluate the performance of the instrument. In thermo-elastic configuration, the interferometric signal has to be carefully analyzed to remove
spurious photothermal effects. The thermo-elastic response of isotropic and anisotropic
homogeneous samples during modulated photothermal experiments are then calculated to
demonstrate that interferometric measurements enable quantitative determination of some
of the sample thermo-elastic parameters such as thermal diffusivity, elastic anisotropy and
crystalline orientation.