Microscopic characterization of metallic surfaces by photoinduced thermoelastic bumps
A non contact technique is presented, that provides information on thermal properties at the cubic micron scale in metal surfaces. It makes use of the appearance of bumps originated in the thermoelastic deformation of the surface induced by laser heating with a modulated beam. The heat diffusion and...
Guardado en:
| Autores principales: | , , |
|---|---|
| Formato: | CONF |
| Materias: | |
| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_39013841_v_n_p490_Martinez |
| Aporte de: |
| Sumario: | A non contact technique is presented, that provides information on thermal properties at the cubic micron scale in metal surfaces. It makes use of the appearance of bumps originated in the thermoelastic deformation of the surface induced by laser heating with a modulated beam. The heat diffusion and thermal expansion give rise to a surface deformation shaping a modulated bump at the laser modulation frequency. A second beam is reflected at the bump and the collected amplitude depends both on the change in reflectivity with temperature (thermoreflectance) and the deflection of the beam due to the surface deformation (photodeflection). Filtering the reflected signal with an adjusTable knife edge the photodeflection signal can be enhanced. A complete analytical model is presented that takes into account both mechanisms. A critical modulating frequency appears at which the heat diffuses the entire laser beam diameter in one modulation period. From the determination of that critical frequency the local heat diffusivity can be determined. Experimental results are presented on poor conducting metallic glasses, confirming the theoretical predictions. |
|---|