Apparatus (1) for additively producing three-dimensional objects (2) by successive layer-by-layer selective exposure and, accompanying this, successive layer-by-layer selective solidification of construction material layers made of a construction material (3) that can be solidified by means of an energy beam (4), including an exposure device (6) which is configured to produce an energy beam (4) for successive layer-by-layer selective exposure and, accompanying this, successive layer-by-layer selective solidification of construction material layers made of a construction material (3) that can be solidified by means of the energy beam (4), a measuring device (13) that is assignable or assigned to the exposure device (6) and configured to measure the power of the energy beam (4) that is produced by the exposure device (6), wherein the measuring device (13) comprises a measuring element (15) that comprises an energy beam input face (16), and at least an energy beam widening device (17).