Abstract: An apparatus and a method using said apparatus for producing an object by means of additive manufacturing layer by layer in a layer sequence, said apparatus comprising: a process chamber for receiving a bath of powdered material which can be solidified by exposure to electromagnetic radiation; a support for positioning a part of said object in relation to a surface level of said bath of powdered material; a solidifying device arranged for generating a beam of electromagnetic radiation for solidifying a selective part of a layer of said powdered material; a deflection device arranged for moving said beam of electromagnetic radiation along said surface level; and a control device arranged for controlling said solidifying device and said deflection device, during solidification of said selective part of said layer, taking into account a first section thermal resistance for conducting heat away from a first section of said selective part of said layer and a second section thermal resistance, that is higher tha

Abstract: An additive layer manufacturing method comprising applying a material, for example a strong Raman scatterer material, treating the applied material using a laser, monitoring a characteristic of the applied material using a vibrational spectroscopy technique, for example a Raman technique, and using the output of the monitoring operation in controlling the treatment of the material. An apparatus for use in the method is also described.