A look on thermography: from passive to active NDT & E surveys

Infrared thermography is a condition monitoring technique that, from a measurement of the radiant heat pattern emitted by a material, is able to determine regions or points, of increased or reduced heat emission that can indicate the presence of an imperfection in the investigated material. Thermographic approaches, passive and active, are widely used due to the outstanding advantages that offer in a number of applications and particularly for the assessment of materials. Nonetheless, there are limitations; depending upon the approach used, as well as on the materials thermal, optical and physical properties, proper assessment (detection and/or quantification) is feasible. Different applications, employing either passive or transient thermographic testing, concerning the assessment of various materials are presented.