A5.3 - Laser-Acoustic Characterization of Coatings
- AMA Conferences 2015
2015-05-19 - 2015-05-21
- Proceedings SENSOR 2015
- A5 - Acoustic Sensing
- F. Singer - Institute of Sensor and Actuator Technology, Coburg (Germany)
- 119 - 123
Non-destructive, contactless and robust characterization of coatings is an ongoing and challenging task in the development of measurement technologies. The determination of elastic material parameters of coating and substrate can serve as a convenient method for the characterization of coatings. In our measurement system, elastic material parameters were derived from the dispersion of surface acoustic waves. The ultrasound waves were excited in the thermoelastic regime using a pulsed laser and were measured in the near-field of the excitation region using a heterodyne Mach-Zehnder interferometer. The dispersion of the surface waves was calculated from the measured time-domain traces using the phase spectral analysis method. The dispersion curves were simulated using a single-layer model. The simulation of the dispersion of Rayleigh waves on a layered half-space was then fitted to the measured dispersion curves using a least-squares algorithm. With this measurement method it was possible to measure the average thickness and thickness distribution of polymer coated aluminum specimen with high accuracy in a scanning manner.