Method and apparatus for non-contact evaluation of the surface condition of a wafer

A method and apparatus for non-contact evaluation of the surface texture of a workpiece (W) by the angle-resolved scattered light measurement comprises an optical sensor (10) which illuminates a measurement spot (14). The back-reflected intensity of the radiation is detected by a line sensor (16) and determines an intensity characteristic value (Ig). It is determined a horizontal initial angle of rotation (θ), wherein the intensity characteristic value (Ig) is maximum. In a measurement mode, surface characteristics, taking into account this initial angle of rotation (θ) are calculated. The measuring method is characterized by extremely high lateral and vertical spatial resolution in the sub-nanometer range, and high measurement speed.