A method for evaluating a fresnel diffraction seam courses

摘要

The invention relates to a method for determining the position of at least one edge of an object, in particular of a strand, comprising the steps of illuminating the object with light at least one coherent light source, wherein at the two geometrical limits of the shadow, caused by the object diffraction margins are produced, receiving the spatial intensity curve of at least one diffraction hem with at least one single or multi-line optical sensor, the at least one recorded intensity curve is differentiated according to the location and, by means of a square spatial is applied, comparing said differentiated according to the location and by means of the square spatial applied at least one recorded intensity curve and at least one periodic reference intensity profile, determining the position of at least one edge of the article on the basis of the comparison.