A procedure for measuring the relative quantities of pulp components in wood or paper pulp, wherein for the pulp components (a,b) present in the pulp, for each one separately, is measured the distribution, or probability density, function (b.sub.a, b.sub.b) of a given fibre-specific characteristic thereof, from the distribution functions are by calculation formed distribution functions (b.sub.a/b) corresponding to the pulp mixture, the distribution function (b.sub.x/y) of the corresponding chara...

The invention relates to a method for measuring particles in suspension and a measuring instrument. In the solution the length of each fiber-like particle in suspension is one by one optically measured by a line camera in a thin equilateral capillary tube. The fiber-like particles in particular are imaged by two or more cameras in the capillary tube one or more times for measuring such properties as fiber thickness, wall-thickness and fibrillation.

The invention relates to a method and a measuring arrangement for determining roughness of paper or paperboard. The paper or paperboard surface is illuminated with collimated light substantially parallel with the normal of the paper or paperboard surface. An image is produced from the paper or paperboard surface by means of reflected optical radiation. The reflected optical radiation is used for producing an image of the paper or paperboard surface onto the pixels of the camera's detector surfac...

The invention relates to a method and a measuring arrangement for determining gloss of paper or paperboard. The paper or paperboard surface is illuminated with collimated light substantially parallel with the normal of the paper or paperboard surface. An image is produced from the paper or paperboard surface by means of reflected optical radiation. The reflected optical radiation is used for producing an image of the paper or paperboard surface onto the pixels of the camera's detector surface, e...