Signal processing unit for photothermal surface testing device

摘要

The invention concerns a signal processing unit of a device for photothermally testing a surface of a test piece (6) which has a speed measuring device (11, 26, 27) that can be used to determine the relative speed of a test piece (6) in relation to the optical part (1). The unit also has a detector (11) firmly attached to it. Using the thus calculated measured value of speed the variation in time of the thermal radiation (8) induced by the excitation radiation (3) on a static testing area (7) can be corrected. The speed measuring device preferably has a segmented detector (11) with output signals allocated to the segments (18, 19) which can be evaluated by means of a cumulative or comparative function.