Surface crack detection using infrared thermography and ultraviolet excitation

High signal to noise ratio is important within non-destructive testing. To achieve automatic inspection, including automatic evaluation, it is even more important. Infrared thermography is a suitable method for automatic inspection. One drawback with thermography of metallic structures is that due to shiny surfaces the reflectance is high and the signal to noise ratio will be low. This paper presents results from surface crack detection with thermography using ultraviolet excitation. The tested component is a welded Inconel plate with a highly reflective surface. Ultraviolet excitation is shown to be a suitable excitation method and high signal to noise is achieved.