Characterization of the thickness and mechanical properties of thin films and hard coatings is of vital importance in a wide range of areas such as microelectronic devices, machine tools, and engine components. While conventional contact methods such as mechanical indentation are currently in vogue, laser ultrasonic (LU) methods offer several benefits including non-contact rapid operation, couplant independence, high fidelity, and the ability to perform in hostile environments. This project aims to:
1. Develop theoretical models for laser generated ultrasound in multi-layered structures allowing for the calculation of time domain surface displacements; 2. Devise experimental procedures for efficient generation of ultrasound and implement an adaptive optical detection system capable of working with good sensitivity on rough and smooth coatings; and 3. Validate the theoretical models with LU experiments on a range of technologically relevant multi-layered structures with a focus on transition metal nitrides and carbides (ie. TiN, TiC, ZrN, CrN);
The goal of the project is to develop the next generation methodologies necessary for laser ultrasonic characterization of thickness and elastic moduli of thin films and coatings.