Determining a position of a building platform within a process chamber of an additive manufacturing device

A method for determining a position data of a building platform provided at a support plate within a process chamber of an additive manufacturing device, the additive manufacturing device comprising scanner optics for scanning a laser beam across a working plane over a powder bed for additive manufacturing of a workpiece, wherein the position data of the building platform relates to a coordinate system of the scanner optics, and the support plate comprising:

• a plurality of building platform holes configured to respectively receive at least one building platform holder for holding the building platform,
• a plurality of optically detectable reference marks distributed on a surface of the support plate in reference to the building platform holes, and
• at least two receptors configured to receive respectively one of laser target parts, the method comprising:
• obtaining a first position dataset comprising a precision position of the at least one building platform holder inserted in one of the plurality of building platform holes with respect to the reference marks;
• upon the support plate being mounted in the process chamber and the building platform is inserted into the at least one building platform holder, marking a laser mark on the laser target parts provided in the receptors using the laser beam and the scanner optics, wherein the laser marks are marked in the working plane at respective laser mark positions defined in the coordinate system of the scanner optics;
• acquiring a pre-manufacturing image of the support plate that has the laser marks on the laser target parts and is mounted within the process chamber;
• obtaining from the pre-manufacturing image a second position dataset comprising positions of the reference marks with respect to the laser marks;
• and
• determining the position data of the building platform within the coordinate system of the scanner optics from the first position dataset, the second position dataset, and the laser mark positions.