IR Thermography

R thermography (IRT) is a non-destructive inspection technique that measures the electromagnetic energy emitted from a surface in the infrared (IR) radiation band, which is normally referred to as thermal radiation. By measuring the emissivity of the surface, which depends mainly on its color and on the reflectivity of the surrounding environment, it converts the thermal radiation to temperature, and therefore is able to display temperature distribution, which is represented as an image in false colors. Information is obtained by building on the fact that the radiation effect is closely correlated to the temperature of the radiating object. This is possible since thermography provides temperature monitoring of different sample surface areas, allowing a time-resolved analysis of the heat diffusion process in the sample including its subsurface structure. As regards these measurements, disturbance effects are offered by air temperature, solar radiation, and plant physiological parameters. Applications of IRT are widespread in various fields from science, civil and military industries to medical diagnostics, fire rescue and maintenance, and so on, in some cases offering indications, normally over a very short timeframe, of the effect of the application of a stress (mechanical or thermal). The duration of the thermal stress introduced can in some cases be very short, so that it can be described as a pulse (“pulse thermography”). Lockin thermography, where the infrared wave signal is produced in response to an excitation, normally created by eddy current or ultrasound techniques, has recently generated interest for archaeological surveys. s