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EP-3914415-B1 - LASER CONTROL SYSTEMS FOR ADDITIVE MANUFACTURING

EP3914415B1EP 3914415 B1EP3914415 B1EP 3914415B1EP-3914415-B1

Inventors

  • KOMSTA, Jan, Pawel
  • DUNBAR, ALEXANDER
  • SWEETLAND, MATTHEW

Dates

Publication Date
20260506
Application Date
20200122

Claims (15)

  1. A laser control system (400) for controlling a laser array (520), the system comprising: a position sensor (410, 810) configured to detect a position of the laser array within a two-dimensional plane and generate a position signal, wherein the laser array comprises a plurality of laser energy sources (450); and a plurality of laser control modules, wherein each laser control module is configured to control operation of a subset of the plurality of laser energy sources of the laser array, and wherein each laser control module includes at least one processor configured to trigger one or more laser energy sources of the plurality of laser energy sources based at least in part on the position signal received from the position sensor.
  2. The system (400) of claim 1, wherein the at least one processor of each laser control module comprises: a first processor operatively coupled to the position sensor (410, 810), wherein the first processor is configured to: receive the position signal, compare the position signal to a list of laser trigger positions, and generate a trigger signal based at least in part on the comparison of the position signal to the list of laser trigger positions; and a second processor operatively coupled to the first processor and to the plurality of laser energy sources (450), wherein the second processor is configured to: receive the trigger signal, and send a firing signal to the associated subset of the plurality of laser energy sources upon receiving the trigger signal.
  3. The system (400) of claim 2, wherein the laser array (520) forms a portion of an additive manufacturing system (100) comprising a build surface (4) and an optics assembly (1) movable relative to the build surface and configured to direct laser energy from the laser array towards the build surface to form an array of laser energy pixels on the build surface.
  4. The system (400) of claim 3, wherein the additive manufacturing system (100) comprises a system for moving the optics assembly relative to the build surface.
  5. The system (400) of claim 2, wherein each laser control module is configured to select the subset of the plurality of laser energy sources based on a first laser pattern corresponding to a first laser trigger position of the list of laser trigger positions.
  6. The system (400) of claim 5, wherein the second control is further configured to transition to a second laser pattern corresponding to a second laser trigger position of the list of laser trigger positions after sending the firing signal.
  7. The system (400) of claim 2, wherein the second processor is configured to control individual laser energy sources of the plurality of laser energy sources (450).
  8. The system (400) of claim 2, wherein each laser energy source of the subset of the plurality of laser energy sources (450) is configured to toggle a power setting upon receiving the firing signal from the second processor.
  9. A method of controlling a laser array (520), the method comprising: determining a position of a laser array within a two-dimensional plane, the laser array comprising a plurality of laser energy sources (450); receiving a position signal corresponding to the position of the laser array from a position sensor (410, 810); and selectively controlling the operation of the plurality of laser energy sources of the laser array using a plurality of laser control modules, wherein each laser control module of the plurality of laser control modules is configured to selectively control the operation of a subset of the plurality of laser energy sources, and wherein at least one of the plurality of laser control modules is configured to trigger one or more of the laser energy sources of the plurality of laser energy sources based at least in part on the position signal.
  10. The method of claim 9, wherein selectively controlling the operation of the plurality of laser energy sources (450) comprises: comparing the position signal to a list of laser trigger positions; generating a trigger signal based at least in part on the comparison of the position signal to the list of laser trigger positions; receiving the trigger signal with a processor; and sending a firing signal to the associated subset of the plurality of laser energy sources upon receiving the trigger signal.
  11. The method of claim 10, further comprising: directing laser energy from the subset of laser energy sources (450) towards a build surface (4) of an additive manufacturing system (100).
  12. The method of claim 10, wherein the subset of the plurality of laser energy sources (450) is selected based on a first laser pattern corresponding to a first laser trigger position of the list of laser trigger positions.
  13. The method of claim 10, further comprising transitioning to a second laser pattern corresponding to a second laser trigger position of the list of laser trigger positions after sending the firing signal.
  14. The method of claim 10, further comprising toggling a power setting of each laser energy source of the subset of the plurality of laser energy sources (450) upon receiving the firing signal from the processor.
  15. The method of claim 9, wherein determining the position of the laser array (520) comprises estimating a position of the laser array based on a timing signal.

Description

FIELD The invention relates to laser control systems and related methods. Some embodiments relate to laser control systems for additive manufacturing systems. BACKGROUND Powder bed fusion processes are an example of additive manufacturing processes in which a three-dimensional shape is formed by selectively joining material in a layer-by-layer process. In metal powder bed fusion processes, one or multiple laser beams are scanned over a thin layer of metal powder. If the various laser parameters, such as laser power, laser spot size, and/or laser scanning speed are in a regime in which the delivered energy is sufficient to melt the particles of metal powder, one or more melt pools may be established on a build surface. The laser beams are scanned along predefined trajectories such that solidified melt pool tracks create shapes corresponding to a two-dimensional slice of a three-dimensional printed part. After completion of a layer, the powder surface is indexed by a defined distance, the next layer of powder is spread onto the build surface, and the laser scanning process is repeated. In many applications, the layer thickness and laser power density may be set to provide partial re-melting of an underlying layer and fusion of consecutive layers. The layer indexing and scanning is repeated multiple times until a desired three-dimensional shape is fabricated. Both single laser and multi-laser systems are used. Some systems use a pair of galvanometer mounted mirrors to scan each laser beam over the desired pattern on the build surface. Some systems use motion stages to scan the laser over the build surface. Some systems use a combination of motion stages and galvanometers to scan the laser over the build surface. Systems that use galvanometers as part of the scanning method often use f-theta or telecentric lens to help keep the incident angle of the laser beam onto the build surface as close to perpendicular as possible for a given build surface size. The spacing between the final optical component of any laser path (e.g., final optics, galvanometer, mirror, telecentric lens or f-theta lens) may be on the order of a few millimeters up to a hundred or more centimeters. US 6,180,050 discloses a solid model creation apparatus comprising a multiplicity of blue LEDS, optical fibers connected thereto, and GRIN lenses arranged at the ends of the tips of the respective optical fibers to constitute an exposing head. The exposing head forms images of the end faces of the respective optical fibers in a photocurable resin exposure region as light spots. The multiplicity of optical fibers at the exposing head are arrayed in a matrix such that they are displaced in staggered fashion so that respective light spots are lined up at the pitch of pixels in the primary scan direction. As the exposing head scans the exposure region in the secondary scan direction, all the light spots capable of directing light onto appropriate pixels, these being the respective pixels to be cured within the exposure region, are turned on and multiple exposure is carried out. US 2017/021455 discloses a system and method for multiple beam additive manufacturing, using multiple beams of light (e.g., laser light) to expose layers of powder material in selected regions until the powder material fuses to form voxels, which form build layers of a three-dimensional structure. The light may be generated from selected light sources and coupled into an array of optical fibers having output ends arranged in an optical head in at least one line such that multiple beams are sequentially directed by the optical head to the same powder region providing multiple beam sequential exposures (e.g., with preheating, melting and controlled cool down) to fuse the powder region. The multiple sequential beams may be moved using various techniques (e.g., by moving the optical head) and according to various scan patterns such that a plurality of fused regions form each build layer. SUMMARY According to the invention, a laser control system for controlling a laser array comprises a position sensor configured to detect a position of a laser array within a two-dimensional plane and generate a position signal. The laser array comprises a plurality of laser sources. The laser control system further comprises a plurality of laser energy sources of the laser array, and each laser control module includes at least one processor configured to trigger one or more laser energy sources of the plurality of laser energy sources based at least in part on the position signal received from the position sensor. In some embodiments, the at least one processor of each laser module may comprise a first processor operatively coupled to the position sensor, wherein the first processor is configured to receive the position signal, compare the position signal to a list of laser trigger positions, and generate a trigger signal based at least in part on the comparison of the position signal to the list