Photothermal inspection of rough steel surfaces

Surface roughness effects have a remarkable influence on photothermal measu rements from steel samples and seriously distort hardness depth profiling. The thermal response of rough surfaces is described by an effective layer w hose properties are defined by global roughness numbers like root- mean squ are roughness and peak-to-valley-roughness. Calculations of roughness effec ts as well as measurements from rough steel samples were performed and comp ared to each other. A good correspondence between the model and experiment was found which demonstrates the suitability of the effective layer model f or a description of roughness. (C) 2001 American Institute of Physics.