Betriebsforschungsinstitut Vdeh Institut Fur Angewandte Forschung Gmbh

Betriesbsforschungsinstitut Vdeh Institut Fur Angewandte Forschung Gmbh

Betriebsforschungsinstitut Vdeh Institut for Angewandete Forschung Gmbh

Roland Keck

Dietmar Oberhoff

Ernst Luhn

Bertold Kruger

Gunther Coen

Fritz Isselstein

The invention relates to a process and a device for the interferometric detection of surface displacements of solids, particularly in test material which is excited with ultrasonic waves, in which an illumination laser 10 radiates the test material surface 2, and a portion of the reflected light, after passing through a differing optical path length, is brought into a state of interference, while the interference is identified by an installed detector 9. In arrangements of this type known to the prior art, a very expensive apparatus and control system is needed to assure that demodulation of the reflected laser light is performed with maximum sensitivity. This is improved by the invention in that a joint illumination laser 10 is employed to operate several interferometer equipped with waveguides 5, 7, which in bundled fashion terminate in a common transmitter and receiver lens 4 positioned at a distance from the test material, from which lens detector-waveguides also emerge; here allocations which are dependent on the phase relation arise and whose signals are at the least added quantitatively and are employed to identify the ultrasonic events.

Method and apparatus for interferometric detection of surface

There is disclosed an electromagnetic transducer for the transmission and ception of ultrasonic waves in the touchless testing of metal workpieces, particularly made of steel, in the shape of sheet and strip material. The transducer is arranged for continuous testing, particularly as applied to continuously advancing material, by wavelength spectroscopy and particularly modal spectroscopy of received ultrasonic waves. To this end, the transducer comprises a pair of transducer segments each of which has a set of mutually parallel conductor tracks formed on a substantially planar printed circuit board in which the frequencies and wavelengths for each segment can be preset in a matrix logic circuit having a short time sequence. The conductor tracks comprise windings arranged to be connected for operation through a set of switching elements in such a manner as to produce in various switching states of the switching elements a plurality of wavelengths for each frequency. The wavelengths being proportionally related to each other by small integral numbers.

Electromagnet transducer

An arrangement for measuring forces and pressures comprises a high-pressure ensitivity metal wire embedded in a low shear force material, such as flexible rubber, which is compressible within a load cell by means of a movable piston. The ends of the metal wire are connected to shank(s) of a jacket thermo-element which can be drawn out of the load cell under internal pressure.

Device for the measurement of forces or pressures

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Dusseldorf, Germany

Roland Keck