Sub-gigahertz laser resonant ultrasound spectroscopy for the evaluation of elastic properties of micrometric fibers

• Cross-section vibration modes of an aluminium fiber in the 50–500 MHz range.
• Laser ultrasonics system for the measurement of vibrations up to 1 GHz.
• Resonant ultrasound spectroscopy applied to a cylindrical structure.

The cross-section eigenmodes of micrometric cylinders were measured in the range of several tens of MHz to about 0.5 GHz. The vibrations were excited using subnanosecond laser pulses. The cross-section eigenmodes were simulated using finite element modeling in a 2D geometry. Using the method of resonant ultrasound spectroscopy, the vibration spectrum of an aluminum wire of diameter 33μm served to determine Young’s modulus and Poisson’s ratio with a precision of 0.7% and 0.3%, respectively. The calculated and measured frequencies of cross-section eigenmodes were fitted with a precision better than 0.5% in the 50–500 MHz range.