Characteristics of Laser Resonant Ultrasonic Spectroscopy System for Measuring Elastic Constants of Materials

Resonant ultrasound spectroscopy (RUS) is a useful technique for measuring the elastic properties of materials. In this study, two experimental approaches for performing RUS are experimentally analyzed and compared: 1) contact transduction using piezoelectric transducers (PZT) and 2) laser transduction using pulse laser excitation and laser interferometric detection. A single Zircaloy sample cut from a nuclear pressure tube was used for this study. By virtue of the non-contact nature, the quality factor, Q, for laser RUS is shown to be higher than the contact RUS. In addition, the probe beam for laser-RUS can be scanned to form a 2D image of each vibrational mode, which in turn enables unique mode identification. These defining characteristics of laser-RUS enable straightforward discrimination of closely spaced resonant modes and provide key advantages for improving the resolution of resonant ultrasound spectroscopy.