Abstract: A method for identifying timber surface properties by using linearly polarized light. The polarization plane of the incident radiation is selected according to the object. The intensity components I.sub.min and I.sub.max having perpendicular polarization planes of the scattered radiation are measured, where the polarization plane of the component I.sub.max is the same as that of the incident radiation. On the basis of the quantities I.sub.min and ##EQU1## conclusions are drawn about the surface properties of the examined surface.