Complex finite element analysis applied to photothermal and thermoelastic microscopies

Photothermal and thermoelastic microscopes are non-destructive systems that generally work with lock-in detection. Experimental results are typically given for one modulation frequency. In order to understand related magnitude and phase images obtained with complex geometries, we have developed a finite element analysis (FEA) dynamic method. Particularly, it enables to directly obtain both thermal and thermoelastic harmonic fields for one modulation frequency. It has been applied to thermoelastic microscopy and has shown very good agreement with experiments. Numerical results from a 3D complex geometry model are presented and show the influence of both excitation size radius and modulation frequency on thermoelastic normal displacements.