DIN 54185:2018-10

This document specifies how lock-in thermography is to be performed for the purpose of non-destructive testing and condition analysis. These tests enable - the detection of material defects and other irregularities; - the determination of geometries/shapes parallel to the surface under investigation; - the determination of the coverage of defects and of layer thicknesses; - the determination of thermal material properties. Lock-in thermography is applied by using halogen lamps, infrared radiators, LED arrays or a sufficiently intense and widened laser source in reflection or transmission configuration. For materials with high thermal diffusivity, sources should be used for heating which can also be modulated at higher frequencies. In this document, only the excitation with optical radiation sources is considered. Further standards are being planned for mechanical and inductive heating. Lock-in thermography is used in industrial manufacturing (polymers, composites, ceramics, metals, components of vehicle, engines and power plants, joining technology, additive manufacturing, electronic components, etc.) and in maintenance (aerospace, power plants, supply engineering, civil engineering, etc.). The method is only partially suitable for testing materials with a very high porosity (e. g. insulating materials) and partially transparent materials.