Infrared cameras permit fast, contact-less and non-destructive measurements of materials and parts. The measurement methods are easy to automate and can be integrated into production lines.
To determine the quality of a part under test the temperature can be an important figure of merit. But, more often than the absolute temperature the relative, temporal temperature change is relevant for characterization of a part.
One distinguishes between passive and active measurement methods. With the passive measurement methods, the infrared contrasts are used which exist without application of an external heat source. For active measurement methods, an external excitation source is used to generate spatial and temporal changes (transients) in the sample under test. One common active IR measurement method is the so-called pulse thermography.
Other methods are the IR lock-in technique and thermoelastic stress analysis. As excitation sources e.g. halogen lamps, flash lamps, lasers, ultrasound, electric and magnetic fields and microwaves can be used.