This Letter proposes a mechanical impedance (MI) measurement technique using noncontact laser ultrasound. The ultrasound is generated by shooting a pulse laser beam onto a target structure, and its response is measured using a laser vibrometer. Once ultrasound propagation converges to structural vibration, MI is formed over the entire structure. Because noncontact lasers are utilized, this technique is applicable in harsh environments, free of electromagnetic interference, and able to perform wide-range scanning. The formation of MI and its feasibility for damage detection are verified through thermo-mechanical finite element analysis and lab-scale experiments.
© 2014 Optical Society of America
Remote Sensing and Sensors
Original Manuscript: December 17, 2013
Manuscript Accepted: April 6, 2014
Published: May 19, 2014
Hyeonseok Lee, Hyeong Uk Lim, Jung-Wuk Hong, and Hoon Sohn, "Mechanical impedance measurement and damage detection using noncontact laser ultrasound," Opt. Lett. 39, 3130-3133 (2014)