A device (10) for calibrating an irradiation system (12) of an apparatus (14) for producing a three-dimensional work piece is suggested, the irradiation system (12) comprising a first irradiation unit (16) for selectively irradiating a first irradiation beam (18) along a first operating axis (20) onto an irradiation plane (22) and a second irradiation unit (24) for selectively irradiating a second irradiation beam (26) along a second operating axis (28) onto the irradiation plane (22), wherein the device (10) comprises: control unit (30) adapted to control the first irradiation unit (16) so as to irradiate the first irradiation beam (18) onto the irradiation plane (22) according to an irradiation pattern (32) and to control the second irradiation unit (24) so as to displace the second operating axis (28) relative to the irradiation plane (22) such that the second operating axis (28) traverses the irradiation pattern (32) produced by the first irradiation unit (16) onto the irradiation plane (22); and a detecting unit (34) adapted to detect process emissions emitted from a region of an impingement point (36) on the irradiation plane (22) at which the second operating axis (28) of the second irradiation unit (24) passes the irradiation plane (22) and to output signals indicative of the detected process emissions to the control unit (30); and wherein the control unit (30) is further adapted to determine a position (x1 . . . n, y1 . . . n) of the irradiation pattern (32) produced by the first irradiation unit (16) on the irradiation plane (22); determine a position (x1 . . . n, y1 . . . n) of at least one intersection point (38) between the irradiation pattern (22) produced by the first irradiation unit (16) and the second operating axis (28) of the second irradiation unit (24) based on the signals output by the detecting unit (34); and calibrate the irradiation system (12) based on the determined position (x1 . . . n, y1 . . . n) of the irradiation pattern (32) produced by the first irradiation unit (16) and the determined position (x′S1, y′S1) of the at least one intersection point.