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Process and device for the simultaneous non-destructive characterization of several characteristics of surface-modified materials
: Schneider, D.; Brenner, B.; Schwarz, T.

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DE 1993-4305064 A: 19930219
DE 1993-4305064 A: 19930219
DE 4305064 C1: 19940519
Patent, Electronic Publication
Fraunhofer IWS ()

The invention relates to the field of non-destructive materials testing. It is based on the technical problem of providing a simple and transportable device for the simultaneous and non-destructive determination of several characteristics of surface-modified materials. The problem is solved by a process in which frequency ranges are cut out by frequency filters from the signal curve of two ultrasonic surface wave pulses excited by laser beams, their cross-correlation function is then calculated and from this the ultrasonic delay times and the ultrasonic speeds are measured and the characteristic to be measured is determined by known correlations. The problem is also solved by a device which comprises a pulse laser, a beam splitter unit, a probe, an ultrasonic surface wave receiver, a signal storage unit and a computer, whereby the beam splitter unit and the probe are linked by optical fibre, in the probe are two laser beam manipulation units comprising a transverse adjustment and rotat ing elements and spacers are arranged on the unit-under-test side of the probe.