Coating thickness inspection with a flash lamp and an infrared detector

Thickness is one of important characteristics of coatings such as thermal barrier coatings, anticorrosion paints and others. The thickness of these coatings and its homogeneity can influence their properties and it is often measured quantity in industrial applications. Commonly used techniques are limited to a certain combination of coating and substrate. Thus, new techniques are still being developed. One of the new promising techniques for coating thickness estimation is flash pulse thermography. Its principle is in thermal excitation of a specimen with a flash lamp and capturing of thermal response with a high-speed infrared camera. Nowadays, the price of those cameras limits the usability of this technique only to scientific and high-tech purposes. This paper describes a possibility of replacing highspeed infrared cameras with infrared detectors, whose technical parameters are sufficient for this application and which price is significantly lower than the price of the suitable infrared cameras. Flash pulse thermographic inspection was applied for a thickness determination of thermally sprayed coatings using a high-speed infrared camera and a highspeed infrared detector. A comparison of both configurations showed benefits of replacing the high-speed infrared camera with the infrared detector. Advantages and disadvantages of both proposed procedures are discussed