# US 10,974,457 B2 · Device and method for calibrating an irradiation system of an apparatus for producing a three-dimensional work piece > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,974,457 B2 - Document ID: US10974457B2 - Status: Granted - Kind: B2 - Application number: 16/180,692 - Filed: 2018-11-05 - Published: 2019-03-07 - Granted: 2021-04-13 - Earliest claimed: 2016-05-04 - Assignees: SLM Solutions Group AG - Applicants: SLM Solutions Group AG - Inventors: Lukas Roesgen; Jan Wilkes - Web page: https://patentgrep.com/patent/US10974457B2 ## CPC - G05B 19/401: characterised by control arrangements for measuring, e.g. calibration and initialisation, measuring workpiece for machining purposes (G05B19/19 takes precedence) - B22F 10/00: Additive manufacturing of workpieces or articles from metallic powder (apparatus or devices therefor B22F12/00) - B22F 10/28: Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM] - B22F 10/31: Calibration of process steps or apparatus settings, e.g. before or during manufacturing - B22F 12/90: Means for process control, e.g. cameras or sensors - B28B 1/001: {Rapid manufacturing of 3D objects by additive depositing, agglomerating or laminating of material (selective deposition modelling of metallic powder B22F10/00; rapid manufacturing of 3D objects in general and in particular of plastics B29C64/00)} - B28B 17/0081: {Process control} - B29C 64/153: using layers of powder being selectively joined, e.g. by selective laser sintering or melting - B29C 64/268: using laser beams; using electron beams [EB] - B29C 64/386: Data acquisition or data processing for additive manufacturing - B29C 64/393: for controlling or regulating additive manufacturing processes - B33Y 10/00: Processes of additive manufacturing - B33Y 30/00: Apparatus for additive manufacturing; Details thereof or accessories therefor - B33Y 50/02: for controlling or regulating additive manufacturing processes - B22F 10/32: of the atmosphere, e.g. composition or pressure in a building chamber - B22F 12/38: {Housings, e.g. machine housings} - B22F 12/41: characterised by the type, e.g. laser or electron beam - B22F 12/44: characterised by the configuration of the radiation means - G05B 2219/37067: Calibrate work surface, reference markings on object, work surface - G05B 2219/37068: Setting reference coordinate frame - G05B 2219/37555: Camera detects orientation, position workpiece, points of workpiece - G05B 2219/37572: Camera, tv, vision - G05B 2219/49007: Making, forming 3-D object, model, surface - Y02P 10/25: Process efficiency - G05B: CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS (systems for controlling or regulating non-electric variables G05D; systems for regulating electric or magnetic variables G05F; control devices or systems insofar as characterised by mechanical features only G05G) - B22F: WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER (making alloys by powder metallurgy C22C); APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER - B28B: SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER (foundry moulding B22C; working stone or stone-like material B28D; shaping of substances in a plastic state, in general B29C; making layered products not composed wholly of these substances B32B) - B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00) - B33Y: ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING - Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS ## Abstract A device for calibrating an irradiation system of an apparatus for producing a three-dimensional work piece includes a control unit to control the irradiation system so as to irradiate a radiation beam onto an irradiation plane according to a calibration pattern. The device also includes a sensor arrangement arranged in the irradiation plane to output signals to the control unit in response to being irradiated with the radiation beam according to the calibration pattern. The control unit generates a digital image of an actual irradiation pattern produced by the radiation beam incident on the sensor arrangement based on the signals output by the sensor arrangement, compares the digital image of the actual irradiation pattern with a digital image of a reference pattern so as to determine a deviation between the actual irradiation pattern and the reference pattern, and calibrates the irradiation system based on the determined deviation between the actual irradiation pattern and the reference pattern. ## Claims ### Claim 1 An apparatus for producing a three-dimensional work piece, comprising: an irradiation system; a carrier which, during normal operation of the apparatus, carries a raw material powder to be irradiated; and a device for calibrating the irradiation system of the apparatus, the device comprising: a control unit adapted to control the irradiation system so as to irradiate a radiation beam onto an irradiation plane according to a calibration pattern, and a sensor arrangement adapted to be arranged in the irradiation plane and to output signals to the control unit in response to being irradiated with the radiation beam according to the calibration pattern, wherein the control unit further is adapted to: generate a digital image of an actual irradiation pattern produced by the radiation beam incident on the sensor arrangement based on the signals output by the sensor arrangement, compare the digital image of the actual irradiation pattern with a digital image of a reference pattern so as to determine a deviation between the actual irradiation pattern and the reference pattern, and calibrate the irradiation system based on the determined deviation between the actual irradiation pattern and the reference pattern, wherein the sensor arrangement is integrated into the carrier which, during normal operation of the apparatus, carries the raw material powder to be irradiated, or wherein the sensor arrangement is integrated into a calibration carrier which is adapted to replace, during calibrating the irradiation system, the carrier which, during normal operation of the apparatus, carries the raw material powder to be irradiated. ### Claim 2 (depends on 1) The apparatus according to claim 1, wherein the control unit is adapted to calibrate the irradiation system based on the determined deviation between the actual irradiation pattern and the reference pattern in such a manner that the deviation between the actual irradiation pattern and the reference pattern is eliminated. ### Claim 3 (depends on 2) The apparatus according to claim 2, wherein the sensor arrangement comprises a plurality of sensors which are arranged at discrete positions within the irradiation plane, wherein a detection area of each of the sensors is selected such that the sensors are irradiated with the radiation beam emitted by the irradiation system according to the calibration pattern even if the irradiation system is decalibrated. ### Claim 4 (depends on 2) The apparatus according to claim 2, wherein the sensor arrangement comprises a single sensor, wherein a detection area of the single sensor is selected so as to substantially cover the irradiation plane. ### Claim 5 (depends on 4) The apparatus according to claim 4, wherein the digital image of the reference pattern is stored in a memory of the control unit, and/or wherein the control unit is adapted to display the digital image of the reference pattern and/or the digital image of the actual irradiation pattern on a display device, and/or wherein the control unit is adapted to control the irradiation system in such a manner that a power of the radiation beam, during calibrating the irradiation system, is lower than during normal operation of the apparatus. ### Claim 6 (depends on 5) The apparatus according to claim 5, wherein the control unit is adapted to: determine a width of a line of the actual irradiation pattern produced by the radiation beam incident on the sensor arrangement, compare the determined line width with a reference line width, and calibrate the irradiation system so as to focus the radiation beam based on the comparison between the determined line width and the reference line width. ### Claim 7 (depends on 6) The apparatus according to claim 6, wherein the control unit is adapted to: determine a shape of a spot of the radiation beam incident on the sensor arrangement, compare the determined shape with a reference shape, and calibrate the irradiation system so as compensate for an elliptic distortion of the radiation beam based on the comparison between the determined shape and the reference shape. ### Claim 8 (depends on 1) The apparatus according to claim 1, wherein the sensor arrangement comprises a plurality of sensors which are arranged at discrete positions within the irradiation plane, wherein a detection area of each of the sensors is selected such that the sensors are irradiated with the radiation beam emitted by the irradiation system according to the calibration pattern even if the irradiation system is decalibrated. ### Claim 9 (depends on 1) The apparatus according to claim 1, wherein the sensor arrangement comprises a single sensor, wherein a detection area of the single sensor is selected so as to substantially cover the irradiation plane. ### Claim 10 (depends on 1) The apparatus according to claim 1, wherein the digital image of the reference pattern is stored in a memory of the control unit, and/or wherein the control unit is adapted to display the digital image of the reference pattern and/or the digital image of the actual irradiation pattern on a display device, and/or wherein the control unit is adapted to control the irradiation system in such a manner that a power of the radiation beam, during calibrating the irradiation system, is lower than during normal operation of the apparatus. ### Claim 11 (depends on 1) The apparatus according to claim 1, wherein the control unit is adapted to: determine a width of a line of the actual irradiation pattern produced by the radiation beam incident on the sensor arrangement, compare the determined line width with a reference line width, and calibrate the irradiation system so as to focus the radiation beam based on the comparison between the determined line width and the reference line width. ### Claim 12 (depends on 1) The apparatus according to claim 1, wherein the control unit is adapted to: determine a shape of a spot of the radiation beam incident on the sensor arrangement, compare the determined shape with a reference shape, and calibrate the irradiation system so as compensate for an elliptic distortion of the radiation beam based on the comparison between the determined shape and the reference shape. ### Claim 13 (depends on 1) The apparatus according to claim 1, wherein the irradiation system of the apparatus for producing a three-dimensional work piece comprises a plurality of irradiation units, each irradiation unit being adapted to irradiate a radiation beam onto an associated irradiation area of the irradiation plane and onto an overlap area arranged between adjacent irradiation areas, and wherein the control unit is adapted to: control the plurality of irradiation units so as to irradiate a selected overlap area with a plurality of radiation beams according to respective calibration patterns, generate a digital image of the actual irradiation patterns produced by the radiation beams incident on the sensor arrangement based on the signals output by the sensor arrangement, compare the digital image of the actual irradiation patterns with a digital image of respective reference patterns so as to determine a deviation between the actual irradiation patterns and the respective reference patterns, and calibrate the irradiation units based on the determined deviation between the actual irradiation patterns and the reference patterns. ### Claim 14 A method for calibrating an irradiation system of an apparatus for producing a three-dimensional work piece, the method comprising the steps of: controlling the irradiation system so as to irradiate a radiation beam onto an irradiation plane according to a calibration pattern, and arranging a sensor arrangement in the irradiation plane which outputs signals in response to being irradiated with the radiation beam according to the calibration pattern, generating a digital image of an actual irradiation pattern produced by the radiation beam incident on the sensor arrangement based on the signals output by the sensor arrangement, comparing the digital image of the actual irradiation pattern with a digital image of a reference pattern so as to determine a deviation between the actual irradiation pattern and the reference pattern, calibrating the irradiation system based on the determined deviation between the actual irradiation pattern and the reference pattern, and wherein the sensor arrangement is integrated into a carrier of the apparatus which, during normal operation of the apparatus, carries a raw material powder to be irradiated, or wherein the sensor arrangement is integrated into a calibration carrier which is adapted to replace, during calibrating the irradiation system, a carrier of the apparatus which, during normal operation of the apparatus, carries a raw material powder to be irradiated. ### Claim 15 (depends on 14) The method according to claim 14, wherein the irradiation system is calibrated based on the determined deviation between the actual irradiation pattern and the reference pattern in such a manner that the deviation between the actual irradiation pattern and the reference pattern is eliminated. ### Claim 16 (depends on 14) The method according to claim 14, wherein the sensor arrangement comprises a plurality of sensors which are arranged at discrete positions within the irradiation plane, wherein a detection area of each of the sensors is selected such that the sensors are irradiated with the radiation beam emitted by the irradiation system according to the calibration pattern even if the irradiation system is decalibrated, or wherein the sensor arrangement comprises a single sensor which is arranged in the irradiation plane, wherein a detection area of the single sensor is selected so as to substantially cover the irradiation plane. ### Claim 17 (depends on 14) The method according to claim 14, wherein the digital image of the reference pattern is stored in a memory of the control unit, and/or wherein the digital image of the reference pattern and/or the digital image of the actual irradiation pattern is displayed on a display device, and/or wherein the irradiation system is controlled in such a manner that a power of the radiation beam, during calibrating the irradiation system, is lower than during normal operation of the apparatus. ### Claim 18 (depends on 14) The method according to claim 14, further comprising: determining a width of a line of the actual irradiation pattern produced by the radiation beam incident on the sensor arrangement, comparing the determined line width with a reference line width, and calibrating the irradiation system so as to focus the radiation beam based on the comparison between the determined line width and the reference line width. ### Claim 19 (depends on 14) The method according to claim 14, further comprising: determining a shape of a spot of the radiation beam incident on the sensor arrangement, comparing the determined shape with a reference shape, and calibrating the irradiation system so as compensate for an elliptic distortion of the radiation beam based on the comparison between the determined shape and the reference shape. ### Claim 20 (depends on 14) The method according to claim 14, wherein the irradiation system of the apparatus for producing a three-dimensional work piece comprises a plurality of irradiation units, each irradiation unit being adapted to irradiate a radiation beam onto an associated irradiation area of the irradiation plane and onto an overlap area arranged between adjacent irradiation areas, and wherein the method comprises the steps of: controlling the plurality of irradiation units so as to irradiate a selected overlap area with a plurality of radiation beams according to respective calibration patterns, generating a digital image of actual irradiation patterns produced by the radiation beams incident on the sensor arrangement based on the signals output by the sensor arrangement, comparing the digital image of the actual irradiation patterns with a digital image of respective reference patterns so as to determine a deviation between the actual irradiation patterns and the respective reference patterns, and calibrating the irradiation units based on the determined deviation between the actual irradiation patterns and the reference patterns.