Thermochromic Paint, is paint that changes color with temperature. The paint is used to assist in the engineering of jet engine combustors. The paint is applied to the combustor, the combustor is installed into an engine, the engine is run through a test cycle, then the combustor is removed, and the paint color is interpreted to read the temperature of the fuel burn. However reading the temperature by interpreting the paint color by eye is imprecise and not repeatable.
Twin Coast Metrology developed a system to directly read the temperature of thermochromic paint. The system observes the part in multiple color wavelengths, then uses a neural network to convert paint color to an accurate temperature measurement. The system then maps the calculated temperature to the 3D surface of the combustor, outputting a 3D temperature map that can be directly imported into the computational fluid dynamics (CFD) package.
The system final system included a rotary table, engineered LED ambient lighting, a light tent, a custom camera head with optical filters, and a custom software application.