Patent ID: 8155426

Claim:
A method for optical inspection of surface roughness, comprising: directing an unfocussed light beam (B) to a surface ( 2 ) of a piece of wood to be inspected in a direction (D), which deviates from the normal to said surface; shifting said surface and light beam relative to each other; receiving light (R) reflected from said surface with an optoelectronic detector ( 3 ); calculating values corresponding to the surface roughness on the electronic signal produced by the detector, wherein said surface roughness is hirsuteness of the wooden surface, using as the optoelectronic detector a camera ( 8 ) having an image plane ( 9 ) formed of several light-sensitive optoelectronic pixels; taking at predetermined intervals images (i−n . . . i+n) of said surface ( 2 ) of the piece of wood moving relative to the camera ( 8 ), each image having the form of electronic image data; subtracting the image data of two consecutive electronic images from each other, yielding a set of pixel-related difference data ((i−n)−(i−(n− 1 )) . . . (i+(n−))−(i+n)), which describes the wooden surface under study; and using the difference data for stating variations in the surface hirsuteness of the surface under study.