Scanner system for use in an apparatus for producing three-dimensional workpieces

Abstract

The invention relates to a scanner system (10) for use in an apparatus (100) for producing three-dimensional workpieces by applying electromagnetic radiation or particle radiation to raw material powder layers, the scanner system (10) comprising a pivotable scanner mirror (12) having a first surface (14) configured to be impinged upon by an irradiation beam (116) emitted by a radiation source (114). Furthermore, the scanner system (10) comprises a scanner mirror cooling device (22) having first coolant supply equipment (26) configured to conduct a first coolant flow (28) over and / or on the first surface (14) of the scanner mirror (12).

Description

[0001] Scanner system for use in a plant for the production of three-dimensional workpieces

[0002] The invention relates to a scanner system for use in a system for producing three-dimensional workpieces using a generative layer-by-layer manufacturing process. Furthermore, the invention relates to a method for operating such a scanner system and a system equipped with such a scanner system for producing three-dimensional workpieces using a generative layer-by-layer manufacturing process.

[0003] In generative layered construction processes for the production of three-dimensional workpieces, particularly powder bed fusion, a raw material powder is applied layer by layer to a substrate and, depending on the desired geometry of the workpiece to be created, is selectively exposed to electromagnetic radiation, such as laser radiation or particle radiation. The radiation penetrating the powder layer causes heating and, consequently, fusion or sintering of the raw material powder particles. Subsequently, further layers of raw material powder are successively applied to the already radiation-treated layer on the substrate until the workpiece achieves the desired shape and size. The raw material powder can comprise ceramic, metal, or plastic materials, but also mixtures of these materials.Additive layering processes and in particular powder bed fusion processes can be used, for example, to produce prototypes, tools, spare parts or medical prostheses, such as dental or orthopedic prostheses, as well as to repair components based on CAD data.

[0004] A system for producing three-dimensional workpieces by selectively irradiating a raw material powder, known, for example, from EP 2 335 848 B1, comprises a process chamber sealed from the ambient atmosphere and a carrier arranged in the process chamber for receiving the raw material powder to be irradiated. Furthermore, the system comprises an irradiation device equipped with a radiation source, in particular a laser source, and an optical unit. The optical unit serves to selectively guide an irradiation beam generated by the radiation source over the raw material powder layers applied to the carrier, depending on the geometry of the workpiece to be produced. For this purpose, the optical unit typically has a beam expander and a scanner system.The scanner system can be provided with diffractive optical elements that can be introduced into the beam path to split the irradiation beam supplied to the scanner system into a plurality of sub-beams. Furthermore, the scanner system comprises a pivotable mirror that serves to direct an irradiation beam incident on the mirror to a desired position on the powder bed. The irradiation beam emitted by the scanner system is finally guided to an objective lens, which can be configured, for example, in the form of an f-theta lens.

[0005] When building a three-dimensional workpiece by selectively irradiating the powder layers applied to the substrate, the radiation energy introduced into the raw material powder causes the powder particles to melt and / or sinter. Typically, a melt pool of molten raw material powder forms in the area of ​​the application point of the irradiation beam on the raw material powder layer. Due to the thermal radiation emitted by the irradiated powder bed, the temperature in the process chamber and the optical unit typically increases during the buildup of a workpiece. The pivoting mirror of the scanner system also experiences a temperature increase due to direct irradiation with the irradiation beam deflected by the mirror.

[0006] As described in EP 3 067 132 A1, temperature changes in the optical unit can result in temperature-dependent changes in specific optical properties of the optical elements of the optical unit. For example, the refractive index or geometry of an optical element can change depending on the temperature of the optical element. This can lead to a shift in the focus position of the irradiation beam radiated onto the raw material powder layers.

[0007] To limit the temperature increase in the optical unit caused by thermal radiation emitted by the irradiated powder bed, WO 2022 / 096304 A1 proposes arranging absorption elements and reflection elements in the process chamber and / or the optical unit. Furthermore, WO 2022 / 096304 A1 describes cooling channels integrated into the walls of the process chamber and the optical unit, as well as the absorption elements.

[0008] The invention is directed to the object of providing a scanner system that can be used in a system for producing high-quality three-dimensional workpieces using a generative layer-by-layer manufacturing process. Furthermore, the invention is directed to the object of specifying a method for operating such a scanner system and a system equipped with such a scanner system for producing three-dimensional workpieces using a generative layer-by-layer manufacturing process.

[0009] This object is achieved by a scanner system having the features of claim 1, a method for operating a scanner system having the features of claim 13 and a system for producing three-dimensional workpieces using a generative layer construction process having the features of claim 18.

[0010] A scanner system suitable for use in a system for producing three-dimensional workpieces by exposing layers of raw material powder to electromagnetic radiation or particle radiation comprises at least one pivotable scanner mirror. During operation of the scanner system, the scanner mirror serves to deflect an irradiation beam, in particular a laser beam, emitted by a radiation source such that the beam impinges on a layer of raw material powder applied to a carrier of the system for producing three-dimensional workpieces at a desired position. The scanner mirror comprises a first surface configured to receive the irradiation beam emitted by the radiation source. For example, the first surface of the scanner mirror can be a front side of the scanner mirror facing the radiation source.The first surface of the scanner mirror is preferably formed in the form of a reflective surface.

[0011] During operation of the scanner system, the scanner mirror is exposed to thermal radiation emitted by the irradiated powder bed. In addition, the scanner mirror is heated by the irradiation beam impinging on the first surface of the scanner mirror. The scanner system therefore comprises a scanner mirror cooling device with a first coolant supply device that is configured to direct a first coolant flow over and / or onto the first surface of the scanner mirror. As a result, the thermal energy introduced into the first surface of the scanner mirror by the irradiation beam can be dissipated directly at the point of entry, i.e. at the point where the irradiation beam hits the scanner mirror. This allows particularly effective cooling of the scanner mirror and in particular of the first surface of the scanner mirror that is subject to particularly high thermal stress.In particular, thermally induced shifts of a focus position of the irradiation beam radiated onto the raw material powder layers in an xy irradiation plane can be reduced.

[0012] The scanner system is therefore particularly advantageous for use in a system for the production of three-dimensional workpieces, where raw material powder layers are irradiated with high power and / or multiple radiation beams. Especially in multi-laser systems, effective cooling of the scanner mirror enables improved multi-laser alignment and thus the production of high-quality workpieces.

[0013] In principle, the scanner system can comprise only one scanner mirror. However, it is also conceivable for the scanner system to comprise two or more pivotable scanner mirrors. Two scanner mirrors can be used to deflect the processing beam in the x and y directions. If the scanner system comprises two pivotable scanner mirrors, each of the scanner mirrors can be designed as described here, i.e., comprise a first surface configured to be exposed to the irradiation beam emitted by the radiation source and to be cooled by a first coolant flow directed over and / or onto the first surface of the scanner mirror. Each scanner mirror can be assigned a separate scanner mirror cooling device and / or a separate first coolant supply device.However, the scanner mirror cooling device and / or the first coolant supply device may also be configured to direct a first coolant flow or multiple first coolant flows over and / or onto the first surfaces of a plurality of scanner mirrors. Furthermore, each or some of the existing scanner mirrors may have the features discussed below.

[0014] The first coolant supply device is preferably configured to direct the first coolant flow at an angle of approximately 0° to approximately 30°, preferably at an angle of approximately 0° to approximately 25°, and particularly preferably at an angle of approximately 0° to approximately 20° to the first surface over and / or onto the first surface of the scanner mirror. Flowing onto the first surface of the scanner mirror at a "flat" angle allows the first coolant flow to flow evenly over the first surface of the scanner mirror. This creates minimal turbulence and correspondingly minimal variations in the refractive indices in the first coolant flow. Furthermore, dirt particles can be directed over the first surface of the scanner mirror and removed, thus preventing the transport of dirt particles from one optical element to another (optical) element of the scanner system.The first coolant supply device may, for example, comprise outlet openings arranged and oriented such that the first coolant flow impinges on the first surface of the scanner mirror at the desired "flat" angle.

[0015] In a particularly preferred embodiment of the scanner system, the scanner mirror cooling device further comprises a second coolant supply device configured to direct a second coolant flow over and / or onto a second surface of the scanner mirror opposite the first surface. The second surface of the scanner mirror can, for example, be a rear side of the scanner mirror that is not directly exposed to the irradiation beam emitted by the radiation source and faces away from the radiation source. If the scanner system comprises two or more pivotable scanner mirrors, a second coolant supply device can be assigned to each scanner mirror. However, the second coolant supply device can also be configured to direct a second coolant flow or multiple second coolant flows over and / or onto the second surfaces of a plurality of scanner mirrors.

[0016] By cooling both the first and second surfaces of the scanner mirror, the scanner mirror is cooled homogeneously. This prevents or at least reduces temporal fluctuations in the scanner mirror temperature as well as a temperature gradient within the scanner mirror. Consequently, thermally induced deformations of the scanner mirror and the resulting influences on the optical properties of the scanner mirror can be avoided. Furthermore, by cooling both the first and second surfaces of the scanner mirror, greater amounts of thermal energy can be dissipated from the scanner mirror.Equipping the scanner mirror cooling device with both a first and a second coolant supply device is therefore particularly suitable when the scanner mirror is exposed to particularly high thermal loads, for example when the scanner system is used in a multi-laser system and / or when radiation sources are used to generate and emit radiation beams with particularly high powers, which lead to high intensities on the surface of the scanner mirror.

[0017] Cooling fins can be provided in the area of ​​the second surface of the scanner mirror. For example, the second surface of the scanner mirror can be partially or completely covered with cooling fins. This enables particularly good heat dissipation from the scanner mirror and, consequently, particularly effective cooling of the scanner mirror.

[0018] The second coolant supply device is preferably configured to direct the second coolant flow over and / or onto the second surface of the scanner mirror at an angle of approximately 40° to approximately 90°, preferably at an angle of approximately 45° to approximately 90°, and particularly preferably at an angle of approximately 50° to approximately 90° to the second surface. To enable this, the second coolant supply device can, for example, comprise first outlet openings arranged and aligned such that the second coolant flow impinges on the second surface of the scanner mirror at the desired "steep" angle.

[0019] Additionally or alternatively, the second coolant supply device can also be configured to direct the second coolant flow at an angle of approximately 0° to approximately 30°, preferably at an angle of approximately 0° to approximately 25°, and particularly preferably at an angle of approximately 0° to approximately 20° to the second surface, over and / or onto the second surface of the scanner mirror. Thus, similar to the first coolant supply device, the second coolant supply device can also provide a flow onto the second surface of the scanner mirror at a "flat" angle. For this purpose, the second coolant supply device can comprise second outlet openings arranged and aligned such that the second coolant flow impinges on the second surface of the scanner mirror at the desired "flat" angle.

[0020] The first and second coolant supply devices can be configured to direct the first and second coolant flows at equal angles to the first and second surfaces, respectively, over and / or onto the first and second surfaces of the scanner mirror, respectively, such that any torques acting on the scanner mirror caused by the coolant flows cancel each other out. For example, the first and second coolant supply devices can be arranged symmetrically relative to the first and second surfaces of the scanner mirror such that the first and second coolant flows are directed over and / or onto the first and second surfaces of the scanner mirror, respectively, at equal angles to the first and second surfaces, respectively.

[0021] Preferably, the first coolant supply device is configured to direct a first coolant flow, adjustable in terms of a volume flow and / or a flow rate, over and / or onto the first surface of the scanner mirror. Additionally or alternatively, the second coolant supply device can be configured to direct a second coolant flow, adjustable in terms of a flow rate and / or a flow rate, over and / or onto the second surface of the scanner mirror. In particular, the first and second coolant supply devices can be configured to deliver coolant flows with independently adjustable volume flows and / or flow rates.A corresponding control of the volume flows and / or flow velocities of the coolant flows delivered by the first and the second coolant supply device can then be used to ensure mutual cancellation or at least a reduction of the torques acting on the scanner mirror at different, non-symmetrical angles of incidence of the coolant flows relative to the first or second surface of the scanner mirror.

[0022] The second coolant supply device can comprise a first coolant supply element facing the second surface of the scanner mirror. Furthermore, the first coolant supply element can be arranged at an angle of approximately 70° to approximately 110°, preferably at an angle of approximately 80° to 100°, and particularly preferably at an angle of approximately 90°, to the second surface of the scanner mirror. In particular, a longitudinal axis of the first coolant supply element can be arranged at an angle of approximately 70° to approximately 110°, preferably at an angle of approximately 80° to 100°, and particularly preferably at an angle of approximately 90°, to the second surface of the scanner mirror. This allows the flow to the second surface of the scanner mirror to be realized at a "steep" angle.

[0023] Furthermore, the second coolant supply device can comprise a second coolant supply element arranged at an angle of approximately 0° to approximately 30°, preferably at an angle of approximately 0° to approximately 25°, and particularly preferably at an angle of approximately 0° to approximately 20°, to the second surface of the scanner mirror. In particular, a longitudinal axis of the first coolant supply element can be arranged at an angle of approximately 0° to approximately 30°, preferably at an angle of approximately 0° to approximately 25°, and particularly preferably at an angle of approximately 0° to approximately 20°, to the second surface of the scanner mirror. As a result, the flow to the second surface of the scanner mirror can be realized at a "flat" angle.

[0024] The first coolant supply device can, for example, be designed in the form of a nozzle. Additionally or alternatively, the first coolant supply element and / or the second coolant supply element of the second coolant supply device can be designed in the form of a nozzle. One or more of these nozzles can be designed as a two-jet nozzle or T-piece in order to increase the accessibility of the coolant or nozzle(s) to the scanner mirror to be cooled. Furthermore, the first coolant supply device and / or the second coolant supply device, or in particular the first coolant supply element and / or the second coolant supply element of the second coolant supply device, can be designed to be movable and configured to be moved depending on the movements of the scanner mirror. This ensures optimal cooling of the scanner mirror in all positions.

[0025] The first and second coolant supply devices can be at least partially integrated with one another. In particular, the second coolant supply element of the second coolant supply device can be integrated into the first coolant supply device. The first coolant supply device is then not only configured to direct a first coolant flow over and / or onto the first surface of the scanner mirror, but is additionally equipped with a second coolant supply element associated with the second coolant supply device, which in turn is configured to direct a second coolant flow over and / or onto the second surface of the scanner mirror.

[0026] The first coolant supply device is preferably arranged at an angle of approximately 0° to approximately 30° to the first surface of the scanner mirror. In particular, a longitudinal axis of the first coolant supply device can be arranged at an angle of approximately 0° to approximately 30° to the first surface of the scanner mirror. This allows the flow onto the first surface of the scanner mirror to be particularly well realized at the desired "flat" angle. Additionally or alternatively, the first coolant supply device can be arranged offset from the scanner mirror along the pivot axis of the scanner mirror. In other words, the first coolant supply device can be arranged "in front of" or "behind" the scanner mirror, viewed along the pivot axis of the scanner mirror. This ensures that the irradiation beam directed onto the first surface of the scanner mirror is not shadowed by the first coolant supply device.

[0027] The scanner mirror can be connected to a drive device, e.g., in the form of a galvanometer motor, via a drive shaft extending along the scanner mirror's pivot axis. The first coolant supply device can be arranged on a side of the scanner mirror facing away from the drive device, i.e., "behind" the scanner mirror as viewed along the pivot axis. Alternatively, however, it is also conceivable to arrange the first coolant supply device on a side of the scanner mirror facing the drive device. The first coolant supply device is then arranged "in front" of the scanner mirror as viewed along the pivot axis.

[0028] As described above, the first coolant supply device can be arranged at an angle > 0°, for example at an angle of approximately 20°, to the first surface of the scanner mirror. However, the first coolant supply device can also be arranged at an angle of approximately 0° to the first surface of the scanner mirror. In particular, the first coolant supply device can be arranged coaxially or parallel to a longitudinal axis of the drive shaft and / or integrated into the drive shaft. The first coolant supply device then provides a first coolant flow that flows over the first surface of the scanner mirror at an angle of approximately 0°, i.e. parallel to the first surface. The first coolant supply device is then particularly well suited to being integrated with a second coolant supply element of the second coolant supply device.

[0029] In particular, the first coolant supply device can then comprise a second coolant supply element of the second coolant supply device, which provides a second coolant flow that flows over the second surface of the scanner mirror at an angle of approximately 0°, ie parallel to the second surface.

[0030] Preferably, the first coolant supply device is configured to direct the first coolant flow symmetrically relative to a pivot axis of the scanner mirror over and / or onto the first surface such that substantially no torque acts on the scanner mirror due to the first coolant flow. This prevents undesired deflections of the scanner mirror caused by the first coolant flow. For example, the outlet openings of the first coolant supply device can be arranged and aligned such that the first coolant flow impinges on the first surface of the scanner mirror symmetrically relative to the pivot axis of the scanner mirror.

[0031] Additionally or alternatively, the second coolant supply device can be configured to direct the second coolant flow over and / or onto the second surface symmetrically to a pivot axis of the scanner mirror such that substantially no torque acts on the scanner mirror due to the second coolant flow. This prevents undesired deflections of the scanner mirror caused by the second coolant flow. For example, in the second coolant supply device, the first and / or second outlet openings of the second coolant supply device can be arranged and aligned such that the second coolant flow impinges on the second surface of the scanner mirror symmetrically to the pivot axis of the scanner mirror.

[0032] The first coolant stream and / or the second coolant stream preferably contains / contain a gas, for example purified air or an inert gas such as helium, argon, nitrogen or a gas mixture. Helium is particularly suitable as an inert cooling gas because helium has a high thermal conductivity and therefore enables effective heat dissipation. When using helium as the cooling gas, the first and / or the second coolant stream can be implemented with small volume flows because even a small coolant volume flow is sufficient to cool the first and / or the second surface of the scanner mirror as desired. When using only a small coolant volume flow, the scanner system or a scanner housing of the scanner system should be sealed as well as possible in order to keep coolant loss as low as possible.

[0033] In a preferred embodiment, the scanner system further comprises a cooling system for cooling the interior of a housing accommodating the scanner system. In addition to the scanner mirror cooling device, the scanner system is then equipped with a "superordinate" cooling system that cools all components arranged within the housing. The cooling system can be configured to supply a gaseous coolant, in particular an inert gas such as helium, to the housing accommodating the scanner system.

[0034] In principle, the cooling system can be designed such that the housing accommodating the scanner system is continuously flushed with coolant, which is fed into the housing via a coolant supply line and discharged from the housing via a coolant discharge line. Preferably, however, the cooling system comprises a recirculation line connected to a coolant inlet and a coolant outlet of the housing, so that the coolant can be circulated through the housing. In a circuit closed to the environment, no (or significantly reduced) further contamination from the environment and / or from the continuously supplied coolant is to be expected. This means that less contamination is introduced into the housing than with continuous flushing with coolant.A heat exchanger can be arranged in the recirculation line to cool the coolant flowing through the recirculation line before it is returned to the housing. Furthermore, a filter can be arranged in the recirculation line to remove dirt particles, oil, and / or moisture from the coolant circulating in the circuit.

[0035] A cooling system equipped with a recirculation line can also include a coolant supply line, which can be connected to the recirculation line or the housing. New or additional coolant can then be added or replenished into the closed circuit via the coolant supply line. This allows, for example, lost coolant to be replaced in the event of leaks in the housing or other components of the cooling system.

[0036] Changes in the coolant flow supplied to the housing can cause pressure fluctuations in the housing. Such pressure fluctuations can lead to vibrations, expansions, displacements, etc. of the housing and / or the scanner mirror, which can reduce the positioning accuracy of the scanner. In the area of ​​the coolant outlet of the housing, i.e. downstream of the coolant outlet, a check valve can therefore be provided in the coolant supply line or the recirculation line. The check valve is preferably designed to allow gas to escape from the housing into the environment when a pressure prevailing in the housing exceeds an activation pressure of the check valve. This can prevent or at least significantly reduce undesirable pressure fluctuations in the housing.

[0037] The check valve is preferably also designed to prevent gas from entering the housing. In particular, the check valve is designed to prevent gas from entering the housing even when the pressure in the housing is negative, i.e., for example, when the pressure is below ambient pressure. This prevents potentially contaminated air from the environment from entering the housing.

[0038] The scanner mirror cooling device and the "higher-level" cooling system can be designed separately from one another. However, partial or complete integration of the scanner mirror cooling device into the cooling system is also conceivable. For example, a coolant supply line and / or a recirculation line of the cooling system can also supply the scanner mirror cooling device with cooling medium. The scanner mirror cooling device and the cooling system then share a common coolant supply line and / or recirculation line. The coolant flowing through the coolant supply line and / or the recirculation line can be guided into the housing accommodating the scanner system via a single coolant inlet. In the housing, the coolant can then be directed to the desired locations or outlets via several outlet openings of the coolant supply line and / or the recirculation line.to the components to be cooled, such as mirrors, lenses, mounts, cooling elements, etc. However, it is also conceivable to direct the coolant flowing through the coolant supply line and / or the recirculation line via several coolant inlets into the housing accommodating the scanner system.

[0039] The scanner system preferably further comprises at least one flow control device configured to implement or at least support a controlled removal of the coolant provided by the first and / or second coolant supply device and / or the coolant provided by the "superordinate" cooling system from the environment of components to be cooled, for example, the scanner mirror. The at least one flow control device prevents coolant that has already been heated by heat transfer from one component to be cooled from coming into thermal contact with another component to be cooled.In other words, regardless of whether the coolant is provided by the first or the second coolant supply device or the "superordinate" cooling system, the at least one flow generation device prevents several components to be cooled from being successively overflowed by the same coolant flow and the heated coolant is held between the components to be cooled.

[0040] The at least one flow control device can, for example, comprise at least one flow guide element, such as a baffle or a shielding element, and / or at least one coolant guide channel. Furthermore, the flow control device can be movable. For example, the flow control device can be movable such that a position and / or orientation of the flow control device can be adjusted as desired depending on the position of the scanner mirror.

[0041] The at least one flow control device can optionally be configured such that the coolant flow also flows toward other optical components arranged in and / or on the housing, such as lenses, protective glasses, or deflecting mirrors. Furthermore, the flow control device is advantageously configured to prevent coolant that has already been heated by heat transfer from one component to be cooled from coming into thermal contact with another component to be cooled. This allows for a uniform temperature distribution across the optical components.

[0042] A cooling fin structure provided in the region of the second surface of the scanner mirror can act as a flow control device. The cooling fins can then be designed as flow guide elements that direct a coolant flow flowing towards the second surface of the scanner mirror in a desired direction. For example, the cooling fins can direct the coolant flow such that other components or cooling elements arranged in and / or on the housing are also exposed to the coolant flow. Additionally or alternatively, however, the cooling fins can also be designed such that the coolant flow, after flowing over the second surface of the scanner mirror, is guided past other (optical) components or towards an inner housing wall in order to prevent several components to be cooled from being successively exposed to the same coolant flow.

[0043] A control unit of the scanner system, which controls the operation of the first and / or second coolant supply device and / or the "superordinate" cooling system and in particular the volume flow and / or the flow rate of the first coolant flow, the second coolant flow and / or the coolant flow provided by the "superordinate" cooling system, is preferably configured to take into account control parameters relevant to the state of the overall system when controlling the individual coolant flows. Such relevant control parameters can be, for example, the temperature and in particular the temperature distribution or the pressure and in particular the pressure distribution in the housing accommodating the scanner system.

[0044] For example, the control unit can be configured to evaluate signals transmitted by corresponding temperature and / or pressure sensors and use them as control parameters for controlling the individual coolant flows. The temperature and / or pressure sensors can either measure the temperature and / or pressure in the entire housing accommodating the scanner system or detect local temperature and / or pressure values ​​prevailing at specific points within the housing. Furthermore, one or more temperature sensors can be present to detect the temperature(s) of one or more coolant flows and transmit corresponding signals to the control unit, which the control unit can then take into account when controlling the coolant flows.Furthermore, the control unit can be configured to use a simulation of the relevant control parameters and the heat transfer in the housing accommodating the scanner system at all relevant positions (i.e., angles of adjustment) of the scanner mirror(s) when controlling the coolant flows.

[0045] Furthermore, the control unit of the scanner system can be configured to monitor the cleanliness of the coolant supplied by the first and / or second coolant supply device and / or the "superordinate" cooling system. For this purpose, the control unit can evaluate the signals of a particle counter and / or examine an optical reference surface against which the coolant to be monitored for cleanliness flows for contamination. A scattered light sensor, for example, can be used for this purpose.

[0046] In a method for operating a scanner system for use in a system for producing three-dimensional workpieces by exposing raw material powder layers to electromagnetic radiation or particle radiation, a first surface of at least one pivotable scanner mirror is exposed to an irradiation beam emitted by a radiation source. A first coolant flow is directed over and / or onto the first surface of the scanner mirror by means of a first coolant supply device of a scanner mirror cooling device.

[0047] The first coolant supply device preferably directs the first coolant flow at an angle of approximately 0° to approximately 30°, preferably at an angle of approximately 0° to approximately 25°, and particularly preferably at an angle of approximately 0° to approximately 20° to the first surface and / or onto the first surface of the scanner mirror.

[0048] Furthermore, by means of a second coolant supply device of the scanner mirror cooling device, a second coolant flow can be directed over and / or onto a second surface of the scanner mirror opposite the first surface.

[0049] The second coolant supply device can direct the second coolant flow at an angle of approximately 40° to approximately 90°, preferably at an angle of approximately 45° to approximately 90°, and particularly preferably at an angle of approximately 50° to approximately 90° to the second surface over and / or onto the second surface of the scanner mirror. Alternatively or additionally, the second coolant supply device can direct the second coolant flow at an angle of approximately 0° to approximately 30°, preferably at an angle of approximately 0° to approximately 25°, and particularly preferably at an angle of approximately 0° to approximately 20° to the second surface over and / or onto the second surface of the scanner mirror.

[0050] The first coolant supply device preferably directs the first coolant flow symmetrically relative to a pivot axis of the scanner mirror and / or onto the first surface such that substantially no torque acts on the scanner mirror due to the first coolant flow. Furthermore, the second coolant supply device can also direct the second coolant flow symmetrically relative to a pivot axis of the scanner mirror and / or onto the second surface such that substantially no torque acts on the scanner mirror due to the second coolant flow.

[0051] Furthermore, the method for operating a scanner system may include all of the features described above in connection with the scanner system.

[0052] A system for producing three-dimensional workpieces by exposing layers of raw material powder to electromagnetic radiation or particle radiation comprises a scanner system as described above. Furthermore, the system can comprise a process chamber, which is sealed in particular from the ambient atmosphere, and a carrier for receiving the raw material powder to be irradiated. The carrier can be arranged in the process chamber. However, it is also conceivable for the process chamber to be movable via the carrier. The carrier can be a rigidly fixed carrier. Preferably, however, the carrier is displaceable in the vertical direction, so that the carrier can be moved step by step downwards in the vertical direction as the structural height of a workpiece built on the carrier increases. The raw material powder applied to the carrier is preferably a metal powder, in particular a metal alloy powder.The raw material powder can also be a ceramic powder or a powder containing various materials. The powder can have any suitable particle size or particle size distribution. However, it is preferred to process powders with a particle size of less than 100 pm.

[0053] The system preferably further comprises an irradiation device, which serves to selectively direct electromagnetic radiation or particle radiation onto the powder bed applied to the carrier. The scanner system described above preferably forms a component of the irradiation device. In addition to the scanner system, the irradiation device preferably further comprises a radiation source, in particular a laser source. Furthermore, in addition to the scanner system, the irradiation device can comprise further optical elements for directing and / or processing the irradiation beam provided by the radiation source. The beam emitted by the scanner system is preferably guided through an objective lens of the irradiation device, which can be designed in particular in the form of an f-theta lens.

[0054] Preferred embodiments of the invention will now be explained in more detail with reference to the accompanying schematic drawings, of which

[0055] Figure 1 shows a system for producing three-dimensional workpieces by exposing raw material powder layers to electromagnetic radiation or particle radiation, which is equipped with a first embodiment of a scanner system,

[0056] Figure 2 shows a detailed view of the first embodiment of the scanner system illustrated in Figure 1,

[0057] Figure 3 shows a detailed view of a second embodiment of a scanner system,

[0058] Figure 4 shows a detailed view of a third embodiment of a scanner system,

[0059] Figure 5 shows a detailed view of a fourth embodiment of a scanner system, and

[0060] Figure 6 shows a detailed view of a fifth embodiment of a scanner system.

[0061] A system 100 shown in Figure 1 for producing three-dimensional workpieces by exposing raw material powder layers to electromagnetic radiation or particle radiation comprises a process chamber 102 that is sealed from the ambient atmosphere. A powder application device 104 arranged in the process chamber 102 serves to apply raw material powder layers to a carrier 106. The carrier 106 is displaceable in the vertical direction, so that the carrier 106 can be moved step by step in the vertical direction downwards into a construction chamber 109 as the construction height of a workpiece 108 built on the carrier 106 increases. The process chamber 102 is provided with a gas inlet 110 for supplying an inert gas (e.g., argon) into the process chamber 102. Furthermore, a gas outlet 112 is provided so that a continuous gas flow can be generated through the process chamber 102.The gas flow may serve to remove melt splashes and / or other unwanted contaminants, such as welding fumes, from the process chamber 102.

[0062] The system 100 further comprises an irradiation device 112, which serves to selectively direct electromagnetic radiation or particle radiation onto the powder bed applied to the carrier 106. The exemplary system 100 shown in Figure 1 comprises only one irradiation device 112. However, the system 100 can also have a plurality of irradiation devices 112.

[0063] The irradiation device 112 comprises a radiation source 114, here in particular in the form of a laser source. The radiation source 114, which may, for example, comprise a diode-pumped ytterbium fiber laser emitting laser light with a wavelength of approximately 1070 to 1080 nm, may be integrated into the irradiation device 112. In the system 100 shown in Figure 1, however, the radiation source 114 is arranged outside the irradiation device 112, with a laser beam 116 emitted by the radiation source 114 being guided into the irradiation device 112 via an optical fiber 118.

[0064] The irradiation unit 112 further comprises two lenses 120 and 122. In the embodiment of an irradiation unit 112 shown in Figure 1, both lenses 120 and 122 have a positive refractive power. The lens 120 collimates the laser light emitted by the optical fiber 118 to generate a collimated or substantially collimated laser beam 116. The lens 122, on the other hand, is configured to focus the collimated (or substantially collimated) laser beam 116 to a desired z-position along a z-axis.

[0065] Finally, the irradiation unit 112 comprises a scanner system 10 with a scanner mirror 12 pivotable about a pivot axis S. During operation of the system 100, the scanner system 10 and in particular the scanner mirror 12 serve to deflect the laser beam 116 emitted by the radiation source 114 such that the beam 116 strikes the raw material powder layer applied to the carrier 106 at a desired position.

[0066] The scanner mirror 12 comprises a first surface 14, which, during operation of the system 100, is exposed to the laser beam 116 emitted by the radiation source 114. In particular, the first surface 14 of the scanner mirror 12 is a front side of the scanner mirror 12 facing the radiation source 114, which is designed in the form of a reflective surface. Furthermore, the scanner mirror 12 comprises a second surface 16 opposite the first surface 14. The second surface 16 of the scanner mirror 12 is, in particular, a rear side of the scanner mirror 12 facing away from the radiation source 114 and thus not directly exposed to the laser beam 116 emitted by the radiation source 114. The second surface 16 of the scanner mirror 12 is provided with cooling fins 17.

[0067] The scanner mirror 12 is connected to a drive device 20, embodied, for example, in the form of a galvanometer motor, via a drive shaft 18 extending along the pivot axis S of the scanner mirror 12. During operation of the system 100, the drive device 20 drives the scanner mirror 12 under the control of a control unit not illustrated in Figure 1, so that the scanner mirror 12 directs the laser beam 116 across the raw material powder layer on the carrier 106 in a location-selective manner and according to a desired irradiation pattern, depending on the geometry of the workpiece 108 to be produced.

[0068] When the laser beam 116 strikes the raw material powder layer on the carrier 116, the radiation energy introduced into the raw material powder causes the powder particles to melt and / or sinter. During operation of the system 100, the components of the irradiation system 112 are exposed to thermal radiation emitted by the irradiated powder bed. The scanner mirror 12 of the scanner system 10 is also heated by the laser beam 116 impinging on the first surface 14 of the scanner mirror 12.To counteract temperature-related changes in the optical properties of the scanner mirror 12 and a resulting shift in the focus position of the laser beam 116 in an xy irradiation plane extending parallel to a surface of the carrier 106, the scanner system 10 comprises a scanner mirror cooling device 22, which is only schematically indicated in Figure 1 and is described in more detail below with reference to Figures 2 to 6. Furthermore, the scanner system 10 comprises a cooling system 24, which is also only schematically indicated in Figure 1 and is also explained in more detail below.

[0069] As is clear from Figures 2 to 4, the scanner mirror cooling device 22 comprises a first coolant supply device 26, which is configured to direct a first coolant flow 28 over and / or onto the first surface 14 of the scanner mirror 12. In the first embodiment of a scanner system 10 illustrated in Figure 2, the first coolant supply device 26, which is designed, for example, in the form of a nozzle, is configured to direct the first coolant flow 28 at an angle of approximately 10° to approximately 20° to the first surface 14 over and / or onto the first surface 14 of the scanner mirror 12.

[0070] For this purpose, the first coolant supply device 26 is arranged at an angle of approximately 15° to the first surface 14 of the scanner mirror 12, i.e. a longitudinal axis of the first coolant supply device 26 forms an angle of approximately 15° with the first surface 14 of the scanner mirror 12. Outlet openings of the first coolant supply device 26, not shown in detail in Figure 1, thus enable a flow onto the first surface 14 of the scanner mirror 12 at an angle of approximately 10° to approximately 20°. The first coolant flow 28 effectively dissipates the thermal energy introduced into the first surface 14 of the scanner mirror 12 by the laser beam 116 directly at the point of introduction.

[0071] The first coolant supply device 26 is arranged on a side of the scanner mirror 12 facing away from the drive device 20, i.e., "behind" the scanner mirror 12 as viewed from the drive device 20 along the pivot axis S. This ensures that the laser beam 116 directed onto the first surface 14 of the scanner mirror 12 is not shadowed by the first coolant supply device 26.

[0072] Furthermore, the first coolant supply device 26 is configured to direct the first coolant flow 28 symmetrically relative to the pivot axis S of the scanner mirror 12 over and / or onto the first surface 14 of the scanner mirror 12 such that substantially no torque acts on the scanner mirror 12 due to the first coolant flow 28. To ensure this, the outlet openings of the first coolant supply device 26 are arranged and aligned such that the first coolant flow 28 impinges on the first surface 14 of the scanner mirror 12 symmetrically to the pivot axis S of the scanner mirror 12. This prevents the first coolant flow 28 impinging on the first surface 14 of the scanner mirror 12 from causing undesired deflections of the scanner mirror 12 about the pivot axis S.

[0073] The scanner mirror cooling device 22 further comprises a second coolant supply device 30 configured to direct a second coolant flow 32 over and / or onto the second surface 16 of the scanner mirror 12 opposite the first surface 14. In the first embodiment of a scanner system 10 illustrated in Figure 2, the second coolant supply device 30 is configured to direct the second coolant flow 32 over and / or onto the second surface 16 of the scanner mirror 12 at an angle of approximately 55° to approximately 90° to the second surface 16.

[0074] To enable this, the second coolant supply device 30 comprises a first coolant supply element 34, designed for example in the form of a nozzle, which faces the second surface 14 of the scanner mirror 12. The first coolant supply element 34 is arranged at an angle of approximately 90° to the second surface 16 of the scanner mirror 12, i.e. a longitudinal axis of the first coolant supply element 34 of the second coolant supply device 30 of the first coolant supply device 26 forms an angle of approximately 90° with the second surface 16 of the scanner mirror 12. First outlet openings of the first coolant supply element 34, not illustrated in detail in Figure 1, thus enable an airflow onto the second surface 16 of the scanner mirror 12 at an angle of approximately 55° to approximately 90°.The cooling of both the first and the second surface 14, 16 of the scanner mirror 12 enables a homogeneous cooling of the scanner mirror, so that temporal fluctuations of the scanner mirror temperature as well as a temperature gradient within the scanner mirror 12 can be avoided or at least reduced.

[0075] Similar to the first coolant supply device 26, the second coolant supply device 30, i.e. the first coolant supply element 34 in the scanner system 10 shown in Figure 1, is configured to direct the second coolant flow 32 symmetrically to the pivot axis S of the scanner mirror 12 over and / or onto the second surface 16 of the scanner mirror 12 such that substantially no torque acts on the scanner mirror 12 due to the second coolant flow 32. To ensure this, the outlet openings of the first coolant supply element 34 of the second coolant supply device 30 are arranged and aligned such that the second coolant flow 32 impinges on the second surface 16 of the scanner mirror 12 symmetrically to the pivot axis S of the scanner mirror 12.This prevents the second coolant flow 32 impinging on the second surface 16 of the scanner mirror 12 from causing undesired deflections of the scanner mirror 12 about the pivot axis S.

[0076] The first coolant stream 28 and / or the second coolant stream 32 contain / contain a gas, for example, purified air or an inert gas. Helium is particularly suitable as an inert cooling gas because helium has high thermal conductivity and thus enables effective heat dissipation.

[0077] Finally, the cooling system 24 serves to cool the interior of a housing 36 accommodating the scanner system 10. Thus, in addition to the scanner mirror cooling device 22, which ensures targeted local cooling of the scanner mirror 12, the scanner system 10 is equipped with a "superordinate" cooling system 24 that cools all components arranged within the housing 36. The housing 36 can be a scanner housing that only accommodates the components of the scanner system 10. Alternatively, the housing 36 can also accommodate other or all components of the irradiation device 112.

[0078] The cooling system 24 supplies a gaseous coolant from a coolant source 38 to the interior of the housing 36. The gaseous coolant is in particular an inert gas, such as helium. A coolant inlet 40 of the housing 36 is connected to a coolant outlet 44 of the housing 36 via a recirculation line 42, so that the coolant can be circulated through the housing 36. A coolant supply line 45 connects the coolant source 38 to the recirculation line 42. This means that less contaminants are introduced into the housing 36 than with continuous flushing with coolant. A heat exchanger 46 is arranged in the recirculation line 42 and ensures that the coolant flowing through the recirculation line 42 is cooled before it is returned to the housing 36.Furthermore, filters (not shown in Figure 1) may be provided in the recirculation line 42 to remove impurities from the coolant before it is returned to the housing 36. As best seen in Figure 1, the recirculation line 42 supplies coolant not only to the cooling system 24 but also to the scanner mirror cooling device 22.

[0079] In the area of ​​the coolant outlet 44, i.e., downstream of the coolant outlet 44, a check valve 47 is provided in the recirculation line 42. The check valve 47 is configured to allow gas to escape from the housing 36 into the environment when the pressure in the housing 36 exceeds an activation pressure of the check valve 47. Furthermore, the check valve 47 is configured to prevent gas from entering the housing 36, even when the pressure in the housing 36 is below the ambient pressure. The check valve 47 reduces or prevents pressure fluctuations in the housing 36.

[0080] The cooling fin structure provided in the region of the second surface 16 of the scanner mirror 12 acts as a flow control device. In particular, the individual cooling fins 17 act as flow guide elements that direct the coolant flow 32 flowing toward the second surface 16 of the scanner mirror 12 in a desired direction after flowing over the second surface 16 of the scanner mirror 12. For example, the cooling fins 17 can direct the coolant flow 32 such that the coolant flow, after flowing over the second surface 16 of the scanner mirror 12, is guided past other (optical) components provided in the housing 32. In addition to the cooling fins 17, further flow control devices and / or flow guide elements (not shown in the figures) can be present, which ensure the desired direction of the coolant flows 28, 32 and the coolant flows guided by the cooling system 24 into and through the housing 36.

[0081] The second embodiment of a scanner system 10 shown in Figure 3 differs from the arrangement according to Figure 2 in that the first coolant supply device 26, as viewed from the drive device 20 along the pivot axis S, is not arranged on the side of the scanner mirror 12 facing away from the drive device 20, but rather on the side facing the drive device 20. In other words, in the arrangement according to Figure 3, the first coolant supply device 26, as viewed from the drive device 20 along the pivot axis S, is not arranged "behind" the scanner mirror, but rather adjacent to the drive device 20 "in front of" the scanner mirror. This also ensures that the laser beam 116 impinging on the first surface 14 of the scanner mirror 12 is not shadowed by the first coolant supply device 26.Otherwise, the structure and functioning of the scanner system 10 shown in Figure 3 correspond to the structure and functioning of the arrangement according to Figure 2.

[0082] In the third embodiment of a scanner system 10 shown in Figure 4, the first coolant supply device 26 is arranged at an angle of approximately 0° to the first surface 14 of the scanner mirror 12, i.e. coaxial with a longitudinal axis of the drive shaft 18. Outlet openings of the first coolant supply device 26, not shown in detail in Figure 4, face the scanner mirror 12, so that the first coolant supply device 26 provides a first coolant flow 28 which flows over the first surface 14 of the scanner mirror 12 at an angle of approximately 0°, i.e. parallel to the first surface 14 and substantially parallel to the drive shaft 18.

[0083] Furthermore, in the scanner system 10 shown in Figure 4, the first and second coolant supply devices 26, 30 are at least partially integrated with one another. In particular, a second coolant supply element 48 of the second coolant supply device 30 is integrated with the first coolant supply device 26, so that the first coolant supply device 26 and the second coolant supply element 48 of the second coolant supply device 30 form a type of "showerhead nozzle."

[0084] The second coolant supply element 48 of the second coolant supply device 30 is arranged at an angle of approximately 0° to the second surface 16 of the scanner mirror 12, i.e. coaxial with the longitudinal axis of the drive shaft 18, wherein outlet openings of the second coolant supply element 48 (not shown in detail in Figure 4) face the scanner mirror 12. As a result, the second coolant supply element 48 of the second coolant supply device 30 provides a second coolant flow 32 which flows over the second surface 16 of the scanner mirror 12 at an angle of approximately 0°, i.e. parallel to the second surface 16 and substantially parallel to the drive shaft 18.

[0085] The first coolant supply device 26 and the second coolant supply element 48 of the second coolant supply device 30 are arranged on the side of the scanner mirror 12 facing away from the drive device 20 along the pivot axis S, i.e., the first coolant supply device 26 and the second coolant supply element 48 of the second coolant supply device 30 are arranged "behind" the scanner mirror, as viewed from the drive device 20 along the pivot axis S. This in turn ensures that the laser beam 116 impinging on the first surface 14 of the scanner mirror 12 is not shadowed. Otherwise, the structure and operation of the scanner system 10 shown in Figure 4 correspond to the structure and operation of the arrangement according to Figures 2 and 3.

[0086] In the scanner system 10 shown in Figure 4, the first coolant supply element 34 of the second coolant supply device 30 illustrated in Figures 1 and 2 was omitted. However, it is conceivable to additionally equip the scanner system 10 according to Figure 4 with a first coolant supply element 34 of the second coolant supply device 30 or an additional first coolant supply device 26.

[0087] The fourth embodiment of a scanner system 10 shown in Figure 5 differs from the arrangement according to Figure 4 in that the first coolant supply device 26 and the second coolant supply element 48 of the second coolant supply device 30, which is integrated with the first coolant supply device 26, are arranged in the region of the drive device 20, as viewed from the drive device 20 along the pivot axis S, not on the side of the scanner mirror 12 facing away from the drive device 20, but on the side facing the drive device 20. However, the first coolant supply device 26 and the second coolant supply element 48 of the second coolant supply device 30, which is integrated with the first coolant supply device 26, are still arranged at an angle of approximately 0° to the first and second surfaces 14, 16 of the scanner mirror 12, i.e. coaxial with the longitudinal axis of the drive shaft 18.

[0088] Furthermore, a first coolant supply element 34 of the second coolant supply device 30, already described in connection with Figures 2 and 3, is present, which is arranged at an angle of approximately 90° to the second surface 16 of the scanner mirror 12, and directs a first component 32a of the second coolant flow 32 at an angle of approximately 55° to approximately 90° to the second surface 16 over and / or onto the second surface 16 of the scanner mirror 12.

[0089] An outlet 50 of the first coolant supply device 26 is directed toward the first surface 14 of the scanner mirror 12 and directs the first cooling air stream 28 at an angle of approximately 0° to approximately 10° to the first surface 14 of the scanner mirror 12 and / or onto the first surface 14. Similarly, an outlet 52 of the second coolant supply element 48 of the second coolant supply device 30 is directed toward the second surface 16 of the scanner mirror 12 and directs a second component 32b of the second cooling air stream 32 at an angle of approximately 0° to approximately 10° to the second surface 16 of the scanner mirror 12 and / or onto the second surface 16. Otherwise, the structure and functioning of the scanner system 10 shown in Figure 5 correspond to the structure and functioning of the arrangements according to Figures 2 to 4.

[0090] The fifth embodiment of a scanner system 10 shown in Figure 6 differs from the arrangement according to Figure 5 in that the first coolant supply device 26 and the second coolant supply element 48 of the second coolant supply device 30, which is integrated with the first coolant supply device 26, are integrated into the drive shaft 18. Otherwise, the structure and operation of the scanner system 10 shown in Figure 6 correspond to the structure and operation of the arrangement according to Figure 5.

Claims

Patent claims 1. Scanner system (10) for use in a system (100) for producing three-dimensional workpieces by exposing raw material powder layers to electromagnetic radiation or particle radiation, the scanner system (10) comprising: - at least one pivotable scanner mirror (12) having a first surface (14) configured to be exposed to an irradiation beam (116) emitted by a radiation source (114); and - a scanner mirror cooling device (22) having a first coolant supply device (26) configured to direct a first coolant flow (28) over and / or onto the first surface (14) of the scanner mirror (12).

2. Scanner system (10) according to claim 1, wherein the first coolant supply device (26) is configured to direct the first coolant flow (28) at an angle of approximately 0° to approximately 30°, preferably at an angle of approximately 0° to approximately 25° and particularly preferably at an angle of approximately 0° to approximately 20° to the first surface (14) over and / or onto the first surface (14) of the scanner mirror (12).

3. Scanner system (10) according to claim 1 or 2, wherein the scanner mirror cooling device (22) further comprises a second coolant supply device (30) configured to direct a second coolant flow (32) over and / or onto a second surface (16) of the scanner mirror (12) opposite the first surface (14).

4. Scanner system (10) according to claim 3, wherein: - the second coolant supply device (30) is configured to direct the second coolant flow (32) at an angle of approximately 40° to approximately 90°, preferably at an angle of approximately 45° to approximately 90°, and particularly preferably at an angle of approximately 50° to approximately 90° to the second surface (16) over and / or onto the second surface (16) of the scanner mirror (12); and / or - the second coolant supply device (30) is configured to direct the second coolant flow (32) at an angle of approximately 0° to approximately 30°, preferably at an angle of approximately 0° to approximately 25° and particularly preferably at an angle of approximately 0° to approximately 20° to the second surface (16) over and / or onto the second surface (16) of the scanner mirror (12).

5. Scanner system (10) according to claim 3 or 4, wherein the second coolant supply device (30) comprises a first coolant supply element (34) which faces the second surface (16) of the scanner mirror (12) and is arranged at an angle of approximately 70° to approximately 110°, preferably at an angle of approximately 80° to 100° and particularly preferably at an angle of approximately 90° to the second surface (16) of the scanner mirror (12).

6. Scanner system (10) according to one of claims 3 to 5, wherein the second coolant supply device (30) comprises a second coolant supply element (48) which is arranged at an angle of approximately 0° to approximately 30°, preferably at an angle of approximately 0° to approximately 25° and particularly preferably at an angle of approximately 0° to approximately 20° to the second surface (16) of the scanner mirror (12).

7. Scanner system (10) according to one of claims 3 to 6, wherein the first and second coolant supply devices (26, 30) are at least partially integrated with one another.

8. Scanner system (10) according to one of claims 1 to 7, wherein: - the first coolant supply device (26) is arranged at an angle of approximately 0° to approximately 30° to the first surface (14) of the scanner mirror (12) and / or offset from the scanner mirror (12) along the pivot axis (S) of the scanner mirror (12).

9. Scanner system (10) according to one of claims 1 to 8, wherein the scanner mirror (12) is connected to a drive device (20) via a drive shaft (18) extending along the pivot axis (S) of the scanner mirror (12), and wherein: - the first coolant supply device (26) is arranged on a side of the scanner mirror (12) facing away from the drive device (20) or on a side facing the drive unit (20), and / or - the first coolant supply device (26) is arranged coaxially or parallel to a longitudinal axis of the drive shaft (18) and / or is integrated into the drive shaft (18).

10. Scanner system (10) according to one of claims 1 to 9, where: - the first coolant supply device (26) is configured to direct the first coolant flow (28) symmetrically relative to a pivot axis (S) of the scanner mirror (12) over and / or onto the first surface (14) such that substantially no torque acts on the scanner mirror (12) due to the first coolant flow (28); and / or - the second coolant supply device (30) is configured to guide the second coolant flow (32) symmetrically relative to a pivot axis (S) of the scanner mirror (12) over and / or onto the second surface (16) such that substantially no torque acts on the scanner mirror (12) due to the second coolant flow (32).

11. Scanner system (10) according to one of claims 1 to 10, wherein the first coolant stream (28) and / or the second coolant stream (32) contains / contain purified air or an inert gas, in particular helium, argon, nitrogen or a gas mixture.

12. Scanner system (10) according to one of claims 1 to 11, further comprising a cooling system (24) for cooling an interior of a housing (36) accommodating the scanner system (10), wherein the cooling system (24) in particular comprises a recirculation line (42) connected to a coolant inlet (40) and a coolant outlet (44) of the housing (36).

13. A method for operating a scanner system (10) for use in a system (100) for producing three-dimensional workpieces by exposing raw material powder layers to electromagnetic radiation or particle radiation, the method comprising the steps of: - applying a radiation beam (116) emitted by a radiation source (114) to a first surface (14) of at least one pivotable scanner mirror (12); and - guiding a first coolant flow (28) over and / or onto the first surface (14) of the scanner mirror (12) by means of a first coolant supply device (26) of a scanner mirror cooling device (22).

14. The method according to claim 13, wherein the first coolant supply device (26) supplies the first coolant flow (28) at an angle of approximately 0° to approximately 30°, preferably at an angle of approximately 0° to approximately 25° and particularly preferably at an angle of approximately 0° to approximately 20° to the first Surface (14) over and / or onto the first surface (14) of the scanner mirror (12).

15. The method of claim 13 or 14, further comprising the step of: - guiding a second coolant flow (32) over and / or onto a second surface (16) of the scanner mirror (12) opposite the first surface (14) by means of a second coolant supply device (30) of the scanner mirror cooling device (22).

16. The method according to claim 15, wherein: - the second coolant supply device (30) directs the second coolant flow (32) at an angle of approximately 40° to approximately 90°, preferably at an angle of approximately 45° to approximately 90°, and particularly preferably at an angle of approximately 50° to approximately 90° to the second surface (16) over and / or onto the second surface (16) of the scanner mirror (12); and / or - the second coolant supply device (30) directs the second coolant flow (32) at an angle of approximately 0° to approximately 30°, preferably at an angle of approximately 0° to approximately 25° and particularly preferably at an angle of approximately 0° to approximately 20° to the second surface (16) over and / or onto the second surface (16) of the scanner mirror (12).

17. The method according to any one of claims 13 to 16, wherein: - the first coolant supply device (26) directs the first coolant flow (28) symmetrically relative to a pivot axis (S) of the scanner mirror (12) over and / or onto the first surface (14) such that substantially no torque acts on the scanner mirror (12) due to the first coolant flow (28); and / or - the second coolant supply device (30) directs the second coolant flow (32) symmetrically relative to a pivot axis (S) of the scanner mirror (12) over and / or onto the second surface (16) such that substantially no torque acts on the scanner mirror (12) due to the second coolant flow (32).

18. Plant (100) for producing three-dimensional workpieces by exposing raw material powder layers to electromagnetic radiation or particle radiation, which comprises a scanner system (10) according to one of claims 1 to 12.

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