Abstract: A nondestructive workpiece testing method and apparatus are provided, wherein an electromagnetic, intensity modulated excitation beam is directed at a point of examination on a workpiece surface, and wherein thermal radiation emitted by the point of examination is detected and evaluated, the excitation beam being guided periodically in different directions in each one of which it is directed at a different point of examination on a workpiece surface. Moreover, an apparatus is provided for nondestructive workpiece testing, comprising an excitation source for the emission of an electromagnetic excitation beam, an optical means to modulate the intensity of the excitation beam and to direct the excitation beam at a point of examination on a workpiece surface, further comprising a detector means to detect the thermal radiation emitted by the point of examination.

Abstract: In a device for photothermically testing a surface (1) of a moving test specimen (2), an excitation beam (5) may be applied to a test area (13). The excitation beam (5) passes through an aperture (12) in a collecting lens (11) that reproduces the thermal radiation generated in a measuring area (14), so that the collecting lens (11) may be adapted to a wavelength of the excitation beam (5) passed to a detector (20). A coupling mirror (9) mounted in the path of excitation beam (5) has practically total reflectivity for the wavelength of the excitation beam (5) and is arranged in such a way that it is very small near the focal area of the excitation beam (5), so that together with the aperture (12) of the collecting lens (11) it only masks a small part of the thermal radiation (17) passed to the detector (20).

Abstract: A method for photothermally testing workpieces, which includes the steps of directing an electromagnetic excitation beam to a desired measuring point on the workpiece surface, detecting and evaluating the heat in the form of thermal radiation which is generated by the excitation beam at the measuring point with the aid of a measuring head; directing two visible locating beams to the workpiece surface, the two locating beams intersecting at a point of intersection; and correcting the relative position between the workpiece and the measuring head so that the point of intersection and the desired measuring point coincide on the workpiece surface.