The invention concerns an apparatus and a method for layered manufacture of a three-dimensional product (4) with an optical system (2) that contains at least one beam source (9) to generate an energy beam (6) and corresponding scanning means (10) to move this beam (6), where the apparatus contains a calibration device (3) for said beam source (9) and/or said scanning means (10), wherein at least the scanning means (10) can be moved with respect to the build chamber (1) between a production position and a calibration position, in which the beam (6) can strike a calibration device (3) and thus work in combination with the latter.