The ability to study the interior of an object without destroying it is an important industrial tool. One method of recent interest is thermal imaging . The idea is to use heat energy as a kind of ''x-ray'', to form an image of the interior of an object without causing damage to the object. More precisely, one applies a controlled source of heat energy to the exterior boundary of the object, then monitors the temperature of the object's boundary over time. This measured boundary temperature is influenced by the internal structure of the object. For example, an internal crack or void may block the flow of heat energy, and the heat is forced to flow around the defect. The goal is to determine the internal structure---e.g., locate cracks---from this exterior temperature data.
Talbott, Shannon and Spring, Hilary
"Thermal Imaging of Circular Inclusions within a Two-Dimensinoal Region,"
Rose-Hulman Undergraduate Mathematics Journal: Vol. 7:
1, Article 1.
Available at: https://scholar.rose-hulman.edu/rhumj/vol7/iss1/1