Described is a method for analyzing a build layer (1; 11) in an additive manufacturing machine when forming a three-dimensional article layer by layer by successive fusion of selected areas of powder layers, which selected areas correspond to successive layers of the three-dimensional article. The method comprises the steps of radiating a portion (4; 14) of the build layer (1; 11) by an energy beam and detecting particles emitted, backscattered or reflected from the radiated portion of the build layer, and scanning the portion (4; 14) of the build layer by moving the energy beam along a main path (5; 15) and simultaneously moving the energy beam back-and-forth across the main path in a meandering pattern (6; 16).