The use of periodic laser heating and phase sensitive thermography to evaluation the thickness of coatings

The phase-sensitive laser thermography method is highly sensitive and allows you to control the uniformity and thickness of coatings made of various materials. The use of robotic manipulators as a scanning device allows you to carefully examine the surfaces of objects of complex shape in automatic mode. The article provides information about the layout of a robotic complex for laser phase-sensitive thermography based on a five-axis robotic arm, a laser with a power of up to 8 watts and a wavelength of 450 nm, as well as a COX CG640 thermal imager. Methods of processing experimental data for determining the thickness of coatings made of materials with low thermal conductivity are proposed. To test the approach, control samples were made of aluminum oxide coated with polypropylene in the range from 40 to 500 microns. It is established that the unevenness of the coating is rationally determined by the phase distribution of temperature fluctuations with a frequency of 0,1—1 Hz.