Abstract: Method for calibrating an irradiation device (2) for additively manufacturing three-dimensional objects which irradiation device (2) comprises at least two irradiation units (3, 4), comprising: guiding one of the at least two energy beams (6, 10) via the corresponding irradiation unit (3, 4) to a determination region (15), preferably a part of a build plane (8), for generating a calibration pattern (18, 19); imaging at least one part of the determination region (15) to an on-axis determination unit (12, 14) of the at least one other irradiation unit (3, 4); determining a position of the calibration pattern (18, 19) in the determination region (15) on basis of the image of the at least one part of the determination region (15); generating calibration information relating to a calibration status of at least one part of the irradiation device (2) based on the position of the calibration pattern (18, 19).

Abstract: An apparatus for additively manufacturing three-dimensional objects may include a process chamber within which an additive manufacturing process is to be performed, and a determination device. The determination device may include a wave generator and a receiving unit. The wave generator may be configured to generate an acoustic wave and to cause the acoustic wave to propagate across a surface within the process chamber. The receiving unit may be configured to receive the acoustic wave after having propagated across the surface within the process chamber. The determination device may be configured to determine a wave parameter of the acoustic wave having been received and to determine a surface parameter of the surface within the process chamber based at least in part on the wave parameter.

Abstract: Method for calibrating an irradiation device (2) for additively manufacturing three-dimensional objects which irradiation device (2) comprises at least two irradiation units (3, 4), comprising: guiding one of the at least two energy beams (6, 10) via the corresponding irradiation unit (3, 4) to a determination region (15), preferably a part of a build plane (8), for generating a calibration pattern (18, 19); imaging at least one part of the determination region (15) to an on-axis determination unit (12, 14) of the at least one other irradiation unit (3, 4); determining a position of the calibration pattern (18, 19) in the determination region (15) on basis of the image of the at least one part of the determination region (15); generating calibration information relating to a calibration status of at least one part of the irradiation device (2) based on the position of the calibration pattern (18, 19).