Patent ID: 6504617
Filing Date: 2003-01-07
Classification: G01B,G01N

Abstract:
A method of determining a surface property of paper or paperboard, the method comprisingilluminating the paper or paperboard surface with collimated light substantially parallel with the normal of the paper or paperboard surface; imaging the illuminated paper or paperboard surface onto the pixels of a camera's detector surface; controlling the reflected optical radiation with an aperture of the desired size before the camera; producing an image of the paper or paperboard surface onto the pixels of the camera's detector surface by means of the reflected optical radiation, each of the pixels imaging a surface area in the order of micrometers of the paper or paperboard; focusing the image of the paper or paperboard surface in depth at different distances by changing the optical distance between the camera and the paper or paperboard surface and measuring at least the gloss of the paper or paperboard surface at different optical distances on the basis of the intensity of the pixels on the camera's detector surface.