Estimation of the thickness of thin metal sheet using laser generated ultrasound

Abstract

A noncontacting technique has been developed to measure the thickness of thin metal sheet by using a pulsed laser to generate both symmetric and antisymmetric Lamb waves. These have been detected with a laser interferometer. Analysis of the waveforms allows an estimation of the sheet thickness and accuracies to within 2% are attainable on sheets as thin as 27 μm.