Apparatus for additively manufacturing three-dimensional objects

Apparatus (1) for additively manufacturing three-dimensional objects (2) by means of successive layerwise selective irradiation and consolidation of layers of a build material (3) which can be consolidated by means of an energy beam (4), the apparatus (1) comprising:

• a process chamber (8) comprising a build plane (7) in which layers of build material (3) are successively layerwise selectively irradiated and consolidated by means of an energy beam (4) during operation of the apparatus (1);
• a gas stream generating device (9) configured to generate a gas stream at least partly streaming through the process chamber (8) during operation of the apparatus (1), the gas stream being capable of being charged with non-consolidated build material particles (25), particularly smoke or smoke residues generated during operation of the apparatus (1), while streaming through the process chamber (8);
• and
• an optical determining device (12) configured to optically determine at least one parameter suitable for characterizing the streaming properties of the gas stream streaming through the process chamber (8) during operation of the apparatus (1) at at least one defined location within the process chamber (8).