Cross stitching control by QMM3D

A method of calibrating an apparatus for additively manufacturing three-dimensional objects, the method comprising:

• guiding a plurality of energy beams generated by at least one irradiation device across at least one calibration unit, the at least one calibration unit comprising at least one calibration region arranged in the beam guiding plane comprising a plurality of scan fields, wherein the at least one calibration region comprises a plurality of sub-regions differing in respect of at least one optical property;
• determining with a determination device, a plurality of calibration signals generated by the plurality of sub-regions being irradiated with the plurality of energy beams;
• and
• determining with the determination device, a calibration status of the irradiation device based at least in part on the determined plurality of calibration signals, wherein the plurality of energy beams comprises a first energy beam and a second energy beam, and wherein the plurality of sub-regions comprises a first sub-region and a second sub-region, and wherein the plurality of calibration signals comprises a first calibration signal and a second calibration signal;
• wherein the first energy beam is scanned via a first beam guiding unit across a first beam path comprising a first sub-path in the first sub-region, generating the first calibration signal, and the second energy beam is scanned via a second beam guiding unit along a second beam path comprising a second sub-path in the second sub-region, generating the second calibration signal;
• wherein both the first energy beam and the second energy beam are scanned along the same nominal beam path which comprises both the first sub-path and the second sub-path, wherein by scanning the first energy beam and the second energy beam along the respective beam paths across the calibration region, the first calibration signal corresponding to the first energy beam and the second calibration signal corresponding to the second energy beam are generated;
• wherein the first calibration signal and the second calibration signal are determined, wherein the first calibration signal comprises a first intensity signal and the second calibration signal comprises a second intensity signal, wherein the first calibration signal is compared to the second calibration signal;
• and
• determining a first status of a first alignment of a first coordinate system of the first beam guiding unit with a second coordinate system of the second beam guiding unit based on the comparison of the first calibration signal to the second calibration signal, and
• further determining a second status of a second alignment of a first scan field of the plurality of scan fields with a second scan field of the plurality of scan fields based on the comparison of the first calibration signal to the second calibration signal.

A computer-readable medium comprising computer-executable instructions, which when executed by a processor associated with an apparatus for additively manufacturing three-dimensional objects, causes the apparatus to perform a method comprising:

• guiding a plurality of energy beams generated by at least one irradiation device across at least one calibration unit, the at least one calibration unit comprising at least one calibration region arranged in the beam guiding plane comprising a plurality of scan fields, wherein the at least one calibration region comprises a plurality of sub-regions differing in respect of at least one optical property;
• determining with a determination device, a plurality of calibration signals generated by the plurality of sub-regions being irradiated with the plurality of energy beams;
• and
• determining with the determination device, a calibration status of the irradiation device based at least in part on the determined plurality of calibration signals, wherein the plurality of energy beams comprises a first energy beam and a second energy beam, and wherein the plurality of sub-regions comprises a first sub-region and a second sub-region, and wherein the plurality of calibration signals comprises a first calibration signal and a second calibration signal;
• wherein the first energy beam is scanned via a first beam guiding unit across a first beam path comprising a first sub-path in the first sub-region, generating the first calibration signal, and the second energy beam is scanned via a second beam guiding unit along a second beam path comprising a second sub-path in the second sub-region, generating the second calibration signal;
• wherein both the first energy beam and the second energy beam are scanned along the same nominal beam path which comprises both the first sub-path and the second sub-path, wherein by scanning the first energy beam and the second energy beam along the respective beam paths across the calibration region, the first calibration signal corresponding to the first energy beam and the second calibration signal corresponding to the second energy beam are generated;
• and
• wherein the first calibration signal and the second calibration signal are determined, wherein the first calibration signal comprises a first intensity signal and the second calibration signal comprises a second intensity signal, wherein the first calibration signal is compared to the second calibration signal, and
• wherein a first determination is made of a first status of a first alignment of a first coordinate system of the first beam guiding unit with a second coordinate system of the second beam guiding unit based on the comparison of the first calibration signal to the second calibration signal, and
• further wherein a second determination is made of a second status of a second alignment of a first scan field of the plurality of scan fields with a second scan field of the plurality of scan fields based on the comparison of the first calibration signal to the second calibration signal.