Iwk Regler Und Kompensatoren Gmbh

Gunter Taux

Dietrich Dopheide

Gerhard Reim

Michael Faber

Laser Doppler anemometer with a wavelength-stabilized laser diode (1) whose beam after splitting (7) is so concentrated in a definite area (9) of a particle-containing flow of a fluid with the velocity (17) that in this area (9) an interference fringe pattern is produced, and with at least one semiconductor photodiode (13) on which the laser beams (10, 11) progressing from the area (9) are refocussed after elimination of scattered light fractions by a scattered light trap (diaphragm stop) (14), for the detection of the difference signal I between incident light intensity I.sub.o and scattered light intensity I.sub.scatter which the particles contained in the fluid emit into the whole solid angle 4.pi., where I=I.sub.o -I.sub.scatter. By detection of the laser beam of the intensity I which is modulated with the Doppler frequency after having passed through the point of measurement (9), the whole light intensity I.sub.scatter emitted by the particle into the solid angle 4.pi. can be utilized for the signal-to-noise ratio at the photodetector, and if suitable semiconductor photodiodes are used, the direction of flow can be identified.

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Braunschweig, Germany

Gunter Taux