METHOD AND ARRANGEMENT FOR PRODUCING AN ENLARGED MEASUREMENT VOLUME FOR THE PURPOSE OF DETERMINING THE STRUCTURE AND/OR WINDING SPEED OF TEXTILE FIBRES ON THE BASIS OF LASER DOPPLER ANEMOMETRY

摘要

The invention relates to a method and an apparatus for contactlessly determining the structure and/or speed of a thread (8) running in the thread run (6) of a textile machine using a sensor device, wherein a laser beam (3) is produced by a light source (1, 2) and is divided into at least two partial beams (5a, 5b), which meet again at the thread (8), using a device (4) for dividing and guiding the laser beam (3), wherein the laser beam (3) which is produced by the light source (1, 2) is divided into a reference beam (5a) and a scattering beam (5b) by the dividing and guiding device (4), wherein the intensity of the scattering beam (5b) is at least twice as high as the intensity of the reference beam (5a), wherein the beams are oriented at an angle (ß) with respect to one another, even when emerging from the dividing and guiding device (4), such that they cross at the thread (8), and wherein the transverse dimension of the reference beam (5a) is greater than the transverse dimension of the running thread (8), wherein that portion of the reference beam (5a) which passes the thread (8) is guided into the optical sensor device (9, 10, 11) which is provided for carrying out the laser Doppler anemometry method.