Device and method for calibrating an irradiation system of an apparatus for producing a three-dimensional work piece

An apparatus for associating a position in a construction data set with a position in a building section of the apparatus, comprising:

• a building section for generating a three-dimensional work piece, configured to receive a base element comprising a boundary surface;
• an irradiation unit configured to generate a radiation beam and to scan the radiation beam over a predefined scanning field, wherein the predefined scanning field comprises at least part of the boundary surface of the base element;
• a detecting unit configured to detect time-dependent electromagnetic radiation intensity of electromagnetic radiation emitted at a spot position of the radiation beam while the radiation beam is scanned over the scanning field;
• and
• a controller configured to:
• associate the detected electromagnetic radiation intensity with position information indicative of a current position of the radiation beam;
• determine a position of the boundary surface of the base element with regard to the scanning field, based on intensity variations of the detected time-dependent electromagnetic radiation intensity and based on the position information, such that abrupt intensity variations over time are identified as corresponding to edges of the boundary surface;
• associate a position in a construction data set with a position in the building section, based on the determined position of the boundary surface;
• and
• associate a position of an additive boundary surface of an additive element defined by the construction data set with the determined position of the boundary surface of the base element.