Removable image-capture apparatus for capturing at least one image, the image-capture apparatus comprising: a casing comprising a surround delimiting an opening intended to receive a calibration plate bearing at least one reference marking and possibly at least one test marking, retaining members for holding the calibration plate in the opening, characterized in that the image-capture apparatus further comprises: at least one source of backlighting visible light situated beneath the opening, a sensor for acquiring at least one image, in the backlighting visible light, of the calibration plate, a guiding and supporting device for positioning the sensor above the opening relative to the surround, a calculation device configured to analyse the at least one image acquired by the sensor, recognise the at least one reference marking and the possible at least one test marking in the at least one image acquired by the sensor, and calculate aiming-command corrections intended for a firing system firing at least one powerful incident-radiation beam, which system belongs to an additive manufacturing apparatus, distinct and separate from the image-capture apparatus, the image-capture apparatus and/or the calculation device comprising a first memory in which there have been pre-recorded, in association with a determined unique identification of the calibration plate, absolute coordinates (X3, Y3) of the at least one reference marking, which coordinates have been determined beforehand, the calculation device being configured to calculate the aiming-command corrections for the aiming of the firing system firing the at least one powerful incident-radiation beam, which system belongs to the additive manufacturing apparatus, on the basis of coordinates (X4, Y4) of the at least one test marking, that were calculated for the at least one reference marking, and on the basis of the absolute coordinates (X3, Y3) of the at least one reference marking. a casing comprising a surround delimiting an opening intended to receive a calibration plate bearing at least one reference marking and possibly at least one test marking, retaining members for holding the calibration plate in the opening, characterized in that the image-capture apparatus further comprises: at least one source of backlighting visible light situated beneath the opening, a sensor for acquiring at least one image, in the backlighting visible light, of the calibration plate, a guiding and supporting device for positioning the sensor above the opening relative to the surround, a calculation device configured to analyse the at least one image acquired by the sensor, recognise the at least one reference marking and the possible at least one test marking in the at least one image acquired by the sensor, and calculate aiming-command corrections intended for a firing system firing at least one powerful incident-radiation beam, which system belongs to an additive manufacturing apparatus, distinct and separate from the image-capture apparatus, the image-capture apparatus and/or the calculation device comprising a first memory in which there have been pre-recorded, in association with a determined unique identification of the calibration plate, absolute coordinates (X3, Y3) of the at least one reference marking, which coordinates have been determined beforehand, the calculation device being configured to calculate the aiming-command corrections for the aiming of the firing system firing the at least one powerful incident-radiation beam, which system belongs to the additive manufacturing apparatus, on the basis of coordinates (X4, Y4) of the at least one test marking, that were calculated for the at least one reference marking, and on the basis of the absolute coordinates (X3, Y3) of the at least one reference marking. at least one source of backlighting visible light situated beneath the opening, a sensor for acquiring at least one image, in the backlighting visible light, of the calibration plate, a guiding and supporting device for positioning the sensor above the opening relative to the surround, a calculation device configured to analyse the at least one image acquired by the sensor, recognise the at least one reference marking and the possible at least one test marking in the at least one image acquired by the sensor, and calculate aiming-command corrections intended for a firing system firing at least one powerful incident-radiation beam, which system belongs to an additive manufacturing apparatus, distinct and separate from the image-capture apparatus, the image-capture apparatus and/or the calculation device comprising a first memory in which there have been pre-recorded, in association with a determined unique identification of the calibration plate, absolute coordinates (X3, Y3) of the at least one reference marking, which coordinates have been determined beforehand, the calculation device being configured to calculate the aiming-command corrections for the aiming of the firing system firing the at least one powerful incident-radiation beam, which system belongs to the additive manufacturing apparatus, on the basis of coordinates (X4, Y4) of the at least one test marking, that were calculated for the at least one reference marking, and on the basis of the absolute coordinates (X3, Y3) of the at least one reference marking.