Reference-free Coating Thickness Quantification using Laser Thermography under Various Exterior Temperature Conditions

Abstract

This paper presents a reference-free paint-thickness visualization method using thermography. When thermal-waves generated by a continuous-wave laser are applied to a paint-surface, the thermal-waves propagate through the paint-layer and the resultant thermal-waves are measured by an infrared camera. The propagating characteristics of thermal-waves through the paint-layer are altered from the changes on the thickness of paint-layer. Accordingly, the alternation can be mapped as the paint-thickness regardless of varying exterior temperature conditions by analysing the phase and amplitude of the thermal-waves acquired by the infrared camera, and the accuracy of the thickness quantification can be further enhanced by additional image processes.