Fast photothermal measurement system for inspection of weak adhesion defects

Abstract

A simple and fast photothermal measurement system for nondestructive evaluation of coatings is presented. The sample surface is scanned with a focused laser beam and the resulting temperature rise is monitored with a focused infrared detector. The laser light scattered from the sample surface is measured with a photodiode and so both the optical and the thermal image of the sample can be obtained simultaneously. The functionality of the measurement system is demonstrated with two plasma-spray-coated samples.