Patent ID: 6643022
Filing Date: 2003-11-04
Classification: G01N

Abstract:
A method for determining fiber orientation in a paper sample comprising the steps of:providing a light sensor, the light sensor being spaced from the sample and facing a surface of the sample to receive light from an area on the surface of the sample viewed by the light sensor; arranging a plurality of light sources in circumferentially spaced positions at least partially around the light sensor, the light sources being radially spaced from the light sensor and being spaced from the sample; successively turning each of the light sources on and then off to cause each of the light sources, in turn, to sequentially and obliquely project a beam of light from the light source onto the area on the sample, the arcuate spacing of the light sources causing the light beam of each of the sources to illuminate the area from a different direction, the successive turning on and off of the light sources being at a common frequency in which a given light source is on while the other light sources are off and off while other light sources are on, the successive, repetitive turning on and off of the light sources at the common frequency creating a rotational effect in the illumination of the area of the sample; receiving, with the light sensor, a series of light signals comprising light obtained from the sample as a result of the sequential illumination of the area on the sample from different directions by the light projected from the light sources, the properties of the obtained light signals being dependent on the orientation of fibers in the sample and the direction of illumination of the sample by each of the light sources; measuring a property of each of the received light signals; using the properties of the received light signals and the associated directions of illumination to determine fiber orientation properties of the sample.