Features of low-frequency nondestructive photothermal testing of the thickness of thin metallic films on glass

摘要

It is shown theoretically and experimentally that the thickness of metallic films on the surface of an insulator can be measured at modulation frequencies of the heating laser radiation to a few kilohertz. The heating and probe laser radiation do not need to be strongly focused-the diameter of both beams on the surface of the test samples can reach tens of micrometers.