Forakam: Imaging photothermal radiometry

Photothermal radiometry is being used e.g. for characterization of changes in the microstructure of metals. It is non-destructive, non-contact and much faster than a metallographic analysis. However, this method uses only one detector element, therefore the inspection of areas requires time-consuming scanning. In this paper, we will show that infrared cameras can be used for detection as well. With an exact synchronization between the excitation laser and the IR image grabbing, reproducible phase contrast values can be obtained, thus converting photothermal radiometry into an imaging method. This is demonstrated on samples with different case hardening depths and grinding burn respectively.