Detection of Laser Generated Lamb Waves in Non-Metals by Capacitance Transducers

Abstract

A non-contacting technique has been developed to generate and detect Lamb waves in thin nonmetallic polyester films and composites like paper by using a TEA-C0 2 laser as generator and a suitably designed electrostatic capacitance transducer as detector. Analysis of these detected waveforms allows an estimation of sheet thickness with a reasonable accuracy in sheets as thin as 19 pm.