Deflection unit

Abstract

Deflection unit (10, 110, 210) comprising - a first window (12) through which an optical working beam (14) can enter the deflection unit (10, 110, 210), - a second window (24) through which the working beam can exit the deflection unit (10, 110, 210) and through which detection beams (32) from a working area (34) can enter the deflection unit (10, 110, 210) along the respective path of the exiting working beam (14) and in the opposite direction to it, - a first detection device (30), - an optical element (20) that reflects at least a first wavelength at least partially and transmits at least a second wavelength at least partially, where the deflection unit (10, 110, 210) - defines a working beam path through which the working beam (14) passes from the first window (12) to the second window (24) via a reflection at the optical element (20), and - defines a detection beam path through which the detection beams (32) pass from the second window (24) to the first detection device (30), wherein the detection beams (32) are at least partially transmitted through the optical element (20), wherein the deflection unit (10, 110, 210) further comprises the following - an XY deflection device (22) arranged between the second window (24) and the optical element (20) in the working beam path and in the detection beam path to deflect the working beam (14) to scan the exiting working beam and simultaneously to deflect the detection beams (32) so that they pass through the detection beam path through the optical element (20) to the first detection device (30), - a focusing device (16) for focusing the working beam (14), wherein the focusing device has a variable focal length and is arranged in the working beam path between the first window (12) and the optical element (20), and - an optical device (39) which is arranged in the detection beam path between the optical element (20) and the first detection device (30) and which is configured to change a focal length for the detection beams (32).

Description

TECHNICAL AREA

[0001] The present invention lies in the field of laser manufacturing and laser processing technology and relates to a deflection unit. BACKGROUND

[0002] Deflection units are used in a variety of industrial manufacturing and processing processes to manipulate the path of laser beams spatially and temporally, thereby scanning them across a work surface within a work area.

[0003] One exemplary application of deflection units is laser-based additive manufacturing. Additive manufacturing offers a great deal of design freedom in component conception and is particularly well suited for rapid model making, also known as "rapid prototyping".

[0004] Besides its use in rapid prototyping, additive manufacturing is increasingly being used for industrial production with larger quantities, thus expanding its application area from rapid prototyping to industrial mass production, or so-called "rapid manufacturing." Additive manufacturing is gaining more and more importance in industrial production, for example in metal processing and in the aerospace and medical technology sectors. Furthermore, it has the potential to replace many classic industrial manufacturing processes, such as casting.

[0005] Laser-based additive manufacturing encompasses the processes of "Direct Powder Fusion," a method in which a powder bed is locally and selectively melted using a laser beam, such as a high-energy laser beam; "Vat Photopolymerization," a method in which a bath of material, such as a resin, is selectively and locally exposed to a laser and thus cured; and "Direct Energy Deposition," a method in which powder is deposited parallel to, or in the same direction as, the laser beam. These processes are area-based build processes in which a volume is created layer by layer.In this process, the laser beam, guided by the deflection unit, is scanned across a planar work surface, such as the surface of a plastic bath (vat photopolymerization) or a powder bed (direct powder fusion), to induce laser-induced polymerization of the plastic or fusion or sintering of the powder grains in desired areas of the surface layer. This creates a new component layer or layer and bonds it to the layer below. This process is repeated layer by layer, with the already produced component layers being lowered relative to the deflection unit and a new layer of loose material, such as unpolymerized plastic or powder, being applied over the most recently produced layer. The laser scanning process is then applied to the new layer according to the shape of the component being manufactured.

[0006] Such laser- and surface-based additive manufacturing processes can progress relatively quickly within a single plane, for example up to 4 m / s. However, due to the large number of layers required to produce a component, they can take several days, during which the process runs around the clock. Accuracy requirements, which can be in the range of 10-20 µm and below, are very high.

[0007] Even the smallest process deviations can lead to the required accuracy not being maintained across the entire component volume. This can either necessitate time-consuming rework, if possible. If this is not readily feasible, for example, in the case of defects within the component volume, it may also be necessary to manufacture the entire component again. Furthermore, process deviations can sometimes go undetected.

[0008] To avoid this and to be able to intervene immediately when process errors occur, it is necessary to observe and monitor the process during manufacturing. Such online quality control, in combination with process regulation and / or process control, allows process-related component defects to be rectified immediately or avoided altogether. This can significantly increase process efficiency, reliability, and throughput, and replace traditional, volume-based manufacturing processes such as casting.

[0009] For example, DE 10 2013 017 795 B3 discloses a laser scanner welding device comprising a deflection unit for scanning a laser beam and an internal camera for online quality control. In this device, the working beam path is superimposed on the camera's field of view using a dichroic mirror, so that when scanning with a scan mirror, the camera's field of view on the workpiece moves synchronously with the working laser beam. A movable focusing lens is arranged between the dichroic mirror and the scan mirror in both the working beam path and the image beam path to adjust the focal point of the laser beam.

[0010] A laser welding machine is known from KR 10 2012 0 114 651 A, into which laser light enters through a first window in the vertical direction. The laser light is then collimated by a collimating lens, deflected into a horizontal direction by a first mirror, deflected back into the vertical direction by a second mirror, and focused by an F-theta lens. The collimating lens can be raised and lowered. The F-theta lens is arranged in both the working beam path and the detection beam path.

[0011] From DE 10 2011 119 478 A1 a deflection unit is known in which a processing beam and a visualization beam are focused by respective adjustable collimator lenses and by a common adjustable focusing lens, wherein the focusing lens is arranged in the common beam path of the processing beam and the visualization beam between a coupling element and a scanner mirror.

[0012] A deflection unit with a similar configuration is known from EP 1 716 963 B1, in which a working beam collimated by an adjustable collimator is focused by a focusing device. The focusing device is arranged in both the working beam path and the detection beam path.

[0013] US patent 2014 / 0263221A1 discloses a laser decontamination device with a Z-axis scanning device with adjustable focal length. SUMMARY OF THE INVENTION

[0014] The present invention is based on the objective of providing a deflection unit which allows for an improved laser working process and improved process observation, process monitoring, process control and process control, particularly in a laser-based additive manufacturing process.

[0015] This problem is solved by the subject matter of claim 1. Advantageous embodiments and further developments are specified in the dependent claims.

[0016] The present invention relates to a deflection unit, in particular for laser manufacturing and for monitoring a laser manufacturing process. The deflection unit according to the invention comprises a first window through which an optical working beam can enter the deflection unit, a second window through which the working beam can exit the deflection unit and through which detection beams from a working area can enter the deflection unit along the respective path of the exiting working beam and in the opposite direction to it, a first detection device, preferably within the deflection unit, and an optical element that at least partially reflects a first wavelength and at least partially transmits at least another second wavelength.The deflection unit defines a working beam path, which the working beam travels from the first window to the second window via reflection at the optical element, and defines a detection beam path, which the detection beams travel from the second window to the first detection device, whereby the detection beams are at least partially transmitted through the optical element.The deflection unit further comprises an XY deflection device arranged between the second window and the optical element in the working beam path and in the detection beam path to deflect the working beam in order to scan the exiting working beam and simultaneously to deflect the detection beams so that they pass through the detection beam path through the optical element to the first detection device, a focusing device for focusing the working beam, wherein the focusing device has a variable focal length and is arranged in the working beam path between the first window and the optical element, and an optical device arranged in the detection beam path between the optical element and the first detection device and configured to change a focal length for the detection beams (32).

[0017] The variable focal lengths, when controlled accordingly, allow for adjustment to different deflection angles at the same working distance, i.e., a so-called plane field compensation, as well as adaptation to different working distances. "Variable focal length" can mean, in particular, that the focal length is adjustable and / or that focus tracking during the process is possible. A rigid fixed optic with a fixed focal length, therefore, does not have a variable focal length. The possibility of plane field compensation is particularly advantageous for laser-based additive manufacturing, in which the laser scans a flat, planar work area and can always remain focused on the surface of the work area.

[0018] In contrast to the prior art mentioned above, the deflection unit according to the invention comprises a focusing device and an optical device for a variable focal length for the working beams and for the detection beams to be detected, respectively. The focusing device is arranged only in the working beam, and the optical device is arranged only in the detection beam path. This decoupling makes it possible to change or adjust the focus position of the working beam without simultaneously affecting the detection by the first detection device, and to adjust and change the detection by the first detection device without simultaneously affecting the laser working process.This allows the process monitoring with the first detection device to always be optimized with regard to the respective monitoring requirements, which may also change during the process, and at the same time allows the laser process to always be optimized with regard to the respective process requirements, which may also include a variation of the focus position and / or the focus shape during the process.

[0019] Decoupling allows the focusing device and the optical device to be controlled independently, enabling the optimization of different requirements. Furthermore, the respective controls do not need to consider or compensate for any influence on the other, as the decoupling eliminates the need for interaction between adaptive detection with the first detection device and adaptive focusing of the working beam. Therefore, the deflection unit according to the invention enables a more flexible and thus more efficient workflow with optimized process monitoring, as well as a more robust, less error-prone, more reliable, and more accurate workflow and observation process during simultaneous process execution, which is essential for effective process observation, monitoring, control, and / or regulation.

[0020] Preferably, the focusing device is configured to change the focal length depending on the setting of the XY deflection device and / or a working distance. This allows the focal length to be adjusted to the respective deflection angle, enabling plane field compensation and maintaining focus in a plane during scanning. Alternatively or additionally, the working distance can be changed by altering the focal length, for example, by a comparatively large offset value.

[0021] The focusing device can include one or more movable lenses and be configured to move one or more lenses together along the working beam path. This allows the focal length and, consequently, the focus position to be changed.

[0022] In one or more of the aforementioned embodiments, the focusing device can be configured to change the focus diameter of the working beam without simultaneously changing the focus position. In other words, the focus size, and thus the intensity on the respective work surface, can be increased or decreased without altering the beam caustics or the focus position. This allows the intensity on the work surface to be adjusted to different conditions during scanning without the focus moving away from the work surface. This increases the flexibility and efficiency of the laser process.

[0023] In the aforementioned embodiments, the focusing device can, for example, comprise several movable lenses, and the deflection unit can be configured to move at least two lenses simultaneously and independently of one another. This allows the at least two lenses to be moved in opposite directions simultaneously. This makes it possible to change the focus size without simultaneously changing the focus position. In some embodiments, the lens movement can consist of a combination of an opposing movement and a common, co-directional, non-opposing movement, so that, with appropriate control, the focus position and focus size can be changed simultaneously.

[0024] The optical element can possess one or more of the following optical properties: a reflectance of ≥ 80%, preferably ≥ 90%, particularly preferably ≥ 99% for a working wavelength, especially a wavelength between 1020 nm and 1080 nm; a transmittance of ≥ 20%, preferably ≥ 70%, particularly preferably ≥ 90% for wavelengths between 400 nm and 900 nm; and a transmittance of >20%, preferably >70%, particularly preferably >90% for wavelengths between 1300 nm and 2100 nm. This makes it possible to guide a high-energy working beam with the working wavelength exclusively or almost exclusively through the deflection unit by reflection, so that little or no absorption heat is generated in the deflection unit. Low-energy detection beams with wavelength spectra in the range of 1300 nm to 2100 nm, i.e. above a possible working wavelength between 1020 and 1080 nm, and in the range of 400 nm to 900 nm, i.e.Below a possible operating wavelength between 1020 and 1080 nm, including possible illumination beams at, for example, 850 nm, these beams can be transmitted through the optical element and thus spatially separated from the working beam. The aforementioned operating wavelength range (reflection range) is particularly advantageous for material processing. The wavelength ranges for possible detection beams (transmission ranges) allow for a comprehensive evaluation of detection beams that originate on the work surface and / or are reflected from the work surface.

[0025] According to an advantageous embodiment of the deflection unit according to the invention, the optical element is arranged at an angle in the detection beam path, and an optical compensation element is further arranged in the detection beam path between the optical element and the first detection device. This compensation element at least partially compensates for optical distortion, in particular aberration and / or astigmatism, resulting from transmission through the angled optical element. Due to the transmission and reflection properties of the optical element and its angle, the detection beams can be separated from the working beam. However, transmission through an angled optical element, i.e., one not perpendicular to the beam, can lead to optical distortion or astigmatism, which can result in blurred or inaccurate detection with the first detection device.This image error can be directly compensated for or at least reduced through compensation. If the detection device is, for example, a camera, this can improve the spatial resolution of the image and avoid the need for subsequent electronic correction. However, even with other detection devices, such as an optical coherence tomograph, the detection accuracy and / or sensitivity can be significantly increased. This enables further improvements in process efficiency, accuracy, and reliability.

[0026] In some embodiments, the optical element is formed by a first plane-parallel plate, and the compensation element is formed by a second plane-parallel plate, with both plates inclined to the detection beam path. This enables a particularly simple, straightforward, accurate, passive, and fast compensation.

[0027] In preferred embodiments, the optical device is configured or controllable for adjusting the collimation, focusing, or beam expansion depending on the setting of the XY deflection device and / or a working distance. This allows working areas—i.e., imaged sections of the work surface at the laser process location—whose detection beams travel different paths to the first detection device due to varying deflection angles and / or working distances, to be detected and observed with equal accuracy and sensitivity. This enables flexible, versatile, and precise observation.

[0028] According to some embodiments, the deflection units are configured for processing with a working distance or distances between 238 mm and 671 mm, preferably between 300 mm and 548 mm. The working distance corresponds to the distance between the exit or entry surface of the second window and a flat working surface below the second window, at which, in the operating orientation of the deflection unit, a flat working area within the working surface can be processed and observed by the deflection unit. "Processed" presupposes that the deflection unit can focus the working beam across the entire flat working area. "Observed" presupposes that the deflection unit can detect, or project onto a detection surface of the first detection device, any working area within the working area that corresponds to the field of view of the first detection device.

[0029] In some or more of the aforementioned embodiments, the deflection units have a working area of ​​200x200 mm. 2 up to 500x500 mm 2 The working field corresponds to a planar area available for processing with the deflection unit at the respective working distance, and which the deflection unit can scan with the focus of the working beam. The working field can vary in size for different working distances.

[0030] Preferably, the deflection unit according to the invention is dimensioned and designed such that, in its operating orientation, its projection surface extends beyond the work area on at least one, two, three, and / or four sides. In other words, the work area can extend only partially beyond the footprint or be completely contained within it. On each side where the work area extends beyond the footprint, the work area, which can be rectangular or square, for example, can be seamlessly combined with a work area of ​​another deflection unit if the deflection units are arranged accordingly side by side. This is particularly advantageous for parallelized processing, which further reduces production time and facilitates mass production.

[0031] Some of the aforementioned deflection units can also be dimensioned and designed so that four of these deflection units can be arranged in such a way that, for one or more working distances, their working areas combine to form an uninterrupted, flat overall working area 3.5 to 4 times the size of the individual working areas. In laser-based additive manufacturing, this allows for the production of components up to four times larger or a reduction in production time by up to four times. This can make it possible to achieve, or even eventually eliminate, the typically high output rates of established processes such as casting.

[0032] According to some embodiments, the deflection units can also be dimensioned and designed such that two of these deflection units can be arranged so that their working areas overlap on a common working area, wherein the common working area has an area that is at least 50%, preferably at least 60%, particularly preferably at least 70% of the area of ​​each individual working area. Accordingly, deflection units operating in parallel do not necessarily have to operate in parallel on their own adjacent working areas, but can also operate in parallel on a common working area or a common part of a working area. This can further increase process efficiency and also improve the quality of the components, for example, if one of the deflection units operating in parallel is used to correct the errors of the other deflection unit.

[0033] In some embodiments, the first detection device is a camera or includes a camera. These embodiments include imaging optics for imaging the work area onto the camera, wherein the imaging optics comprise the aforementioned optical device. In these embodiments, the optical device is configured to change the focal length of the imaging optics. This allows the process to be visually observed and monitored.

[0034] In the aforementioned embodiments, the imaging ratio of the area of ​​the work area imaged onto the camera at the working distance to the area of ​​the camera chip can be between 1.7 and 0.5, preferably 0.8. These ratios allow for a particularly advantageous compromise between the required spatial resolution for sufficiently accurate process monitoring, the smallest possible number of camera pixels for sufficiently fast readout, a larger camera chip (imaging in the 1:1 range) for good light intensity and efficiency, a sufficiently large field of view of the camera on the work surface to monitor a sufficiently large work area, and the shortest possible imaging path length for a compact design of the deflection unit.

[0035] In some advantageous embodiments, the camera has a 2 / 3" or 8.8 mm x 6.6 mm chip, which in particular has 1280 x 1024 pixels, and the imaged area of ​​the working area, which corresponds to the camera's field of view at the working distance, has a size between 6 mm x 8 mm and 10.5 mm x 14 mm. This chip size allows for a sufficiently high frame rate or temporal resolution for monitoring. Furthermore, the imaged area is sufficiently large for process evaluation, and a sufficiently high optical or spatial resolution is enabled.

[0036] In some of the aforementioned embodiments, the imaging path length, which the detection or image beams travel from the entrance to the imaging optics to the camera chip, is between 400 mm and 700 mm, preferably between 420 mm and 600 mm, and particularly preferably between 450 mm and 510 mm, especially 480 mm. Such path lengths enable a comparatively compact design while simultaneously achieving an optimal compromise between spatial resolution (which is related to the imaging ratio, sharpness or degree of distortion-free image, and the number of pixels), speed or frame rate (which is related to the number of pixels), the size of the imaged area (which is related to the imaging ratio and the chip size), and the simplest possible imaging optics (number and type of lenses), which can therefore be comparatively robust and cost-effective. A compact design is particularly advantageous for parallelized laser processes, i.e.,The manufacturing or processing of a component simultaneously using multiple laser beams and deflection units, because the deflection units can be arranged closer together, so that their working areas partially overlap or are adjacent to each other.

[0037] In one or more of the aforementioned embodiments, the camera allows an image acquisition rate of ≥ 500 Hz, preferably ≥ 1 kHz, particularly preferably ≥ 1.5 kHz, and especially ≥ 2 kHz. This allows the process to be observed and examined with high temporal resolution, so that even the smallest errors can be detected, investigated, and, if necessary, corrected.

[0038] Furthermore, the deflection unit according to the invention can include a lighting device arranged and aligned to illuminate the entire working field simultaneously with the second wavelength, in particular with a homogeneity of ≥ 80%. This eliminates the need to scan the illumination beams, allowing for static illumination in the direction of and relative to the working field. Compared to scanned illumination, the process in these embodiments can exhibit high reliability and robustness. Moreover, illumination can be achieved with a comparatively high degree of homogeneity, ensuring uniform imaging conditions for different areas.

[0039] In the aforementioned embodiments, the lighting device can also be configured for flashing illumination. This allows the light intensity to be increased and, with increased light intensity, a longer lamp lifespan can be achieved.

[0040] In some embodiments, the illumination is flashed in such a way that the camera takes each picture during a flash of light, and the flash duration is longer than or equal to the camera's image capture time. This ensures that sufficient light intensity is available for image capture, even when only a small section of the illuminated area is being photographed.

[0041] Preferably, the off-time of the lighting is greater than or equal to the on-time. This prevents excessive heating, thereby increasing the service life, process accuracy, and reliability.

[0042] Some of the aforementioned embodiments also include a frame grabber to which the camera is connected. The frame grabber allows for faster reading and processing of the camera images, thereby further refining and improving process monitoring and consequently increasing process efficiency.

[0043] In some alternative embodiments, the first detection device is or includes an optical coherence tomograph (OCT). The optical coherence tomograph allows the detection and observation of existing height differences and / or height differences that arise during or as a result of the process. This is an alternative to process monitoring using a camera. In other embodiments, the first detection device may also include other detection devices that can advantageously be operated with the adaptable optical device.

[0044] Some of the aforementioned embodiments of the deflection unit according to the invention further comprise a second optical element and a second detection device, wherein the second optical element is arranged in the detection beam path between the optical element and the first detection device, reflects the second wavelength at least partially for transmission to the first detection device, and at least partially transmits other wavelengths for transmission to the second detection device. This allows, in addition to direct observation and monitoring by means of the first detection device, further process monitoring to be carried out continuously throughout the production period, which can provide additional information or monitor other process parameters. Controlling or regulating process intervention based on this extended monitoring can thus contribute to a further improvement in process efficiency and quality.

[0045] The second optical element can possess one or more of the following optical properties: a reflectance of ≥ 80%, preferably ≥ 90%, particularly preferably ≥ 95% for an illumination wavelength between 820 nm and 870 nm, preferably at an angle of incidence of 45°; a transmittance of >20%, preferably >70%, particularly preferably >90% for wavelengths between 400 nm and 700 nm; and a transmittance of >20%, preferably >70%, particularly preferably >90% for wavelengths between 1300 nm and 2100 nm. The aforementioned spectrally extended transmittance ranges of the first and second optical elements enable, in addition to observation with the first detection device, a further parallel observation, either locally at specific wavelengths or integratively over one or more larger wavelength ranges, such as the integrative method of measuring light intensity using a photodiode.

[0046] The second detection device may include a photodiode, a pyrometer, a second camera, preferably a VIR camera and / or multispectral camera for generating a radiation and / or heat map, a thermal image sensor and / or an optical coherence tomograph.

[0047] The deflection unit according to the invention and its aforementioned embodiments are particularly well suited for additive manufacturing, especially for direct powder fusion, vapor photopolymerization, and / or direct energy deposition. These processes also include selective laser melting (SLM) and laser metal deposition (LMD). However, they can also be used for other applications. The present invention is not limited to these applications.

[0048] The present invention further relates to the use of a deflection unit according to one or more of the aforementioned embodiments for additive manufacturing, in particular for “Direct Powder Fusion”, Vat Photopolymerisation and / or “Direct Energy Deposition”. BRIEF DESCRIPTION OF THE FIGURES

[0049] Further advantages and features of the present invention are explained in more detail in the following description with reference to the accompanying figures. Fig. Figure 1 shows the schematic structure of a deflection unit according to an embodiment of the invention. Fig. Figure 2 shows a deflection unit according to a further embodiment of the invention. Fig. Figure 3 shows a deflection unit according to a further embodiment of the invention. Fig. Figure 4 shows an external view of a deflection unit according to an embodiment of the invention. Fig. Figure 5 shows a schematic top view of an arrangement of four deflection units according to an embodiment of the invention for parallelized manufacturing. Fig. Figure 6 shows a schematic top view of an arrangement of two deflection units according to an embodiment of the invention for parallelized manufacturing.

[0050] The figures have identical features marked with the same reference symbols. DETAILED DESCRIPTION OF EXAMPLE FORMS OF EXECUTION

[0051] Fig. Figure 1 shows a schematic diagram of a deflection unit 10 according to an embodiment of the invention. The deflection unit 10 comprises a first window 12 through which an optical working beam 14 can enter the deflection unit 10. The first window 12 is arranged within a fiber optic connector, via which a fiber laser or a fiber optic link can be connected to the deflection unit 10. In other embodiments, the working beam 14 can enter the deflection unit 10 as a free beam without a fiber optic connector.

[0052] The deflection unit 10 further comprises a focusing device 16 for focusing the working beam 14 onto a work surface 18, an optical element 20 for reflecting the working beam 14, an XY deflection device 22 for scanning the working beam across the work surface 18, and a second window 24 through which the working beam can exit the deflection unit 14. The aforementioned elements 16, 20, 22, 24 are arranged along a working beam path in the deflection unit 10 and are traversed by a working beam 14 entering the deflection unit 10 in the aforementioned sequence, or they reflect the working beam 14 in the aforementioned sequence.

[0053] The XY deflection device 22 comprises a first scan mirror 26 and a second scan mirror 28, which are configured to deflect and scan the working beam 14 in an X direction and a Y direction, respectively.

[0054] Furthermore, the deflection unit 10 comprises a first detection device in the form of a camera 30, which is arranged within the deflection unit 10 to detect detection or image rays 32 that are reflected from a working area 34 within the working surface 18. The detected image rays 32 travel from the working surface 18 to the camera 30 along a detection or image path, on which the image rays 32 successively pass through or are reflected by the following elements: the second window 24, the XY deflection device 22, the optical element 20, a compensation element 36, a second optical element 38, and an optical device 39. The optical device 39 is part of an imaging optic 40. The optical device 39 is configured to change the focal length of the imaging optic 40.

[0055] In some embodiments, the optical device 39 is a collimation device that ensures that the image rays 32 are collimated at a specific point in the image path between the device 39 and the camera 30 at different image distances. In other embodiments, however, the image rays 32 do not need to be collimated, or not everywhere, between the device 39 and the camera 30. Due to the adaptability, adjustability, or modifiability of the device 39, it is variable and can maintain a constant collimation, widening, and / or focusing of the image rays 32 between the device 39 and the camera 30 even with changing image distances.

[0056] The second window 24 can comprise a pane transparent to the working beam 14 and the image beams 32. This pane can protect the interior of the deflection unit 10 from dirt or contamination and also provide thermal insulation to prevent excessive heat transfer from the working surface 18 into the deflection unit 10. In other embodiments, the second window 24 can also comprise an opening without any material in it, through which an air or fluid connection is established between the interior and exterior of the deflection unit 10.

[0057] In the embodiment of the Fig. 1 includes the imaging optics 40, as in Fig. Figure 1 shows two lenses 42, 46, the optical device 39, which includes a further lens 44, and two deflecting mirrors 48, 50, to image the working area 34 onto a chip of the camera 30 via an imaging path length of the imaging optics 40. The imaging path length is defined by the optical path length that the image rays 32 travel from the entrance to the imaging optics 40 until they strike the chip of the camera 30. Fig. 1. The imaging path length corresponds to the optical path that the image rays travel from the entrance lens 42 to the camera chip. It should be noted that in other embodiments the imaging optics 40 may have a different design, and in particular may comprise more or fewer lenses and / or mirrors, which may be arranged differently than shown in [reference]. Fig. 1 is shown.

[0058] In the deflection unit 10, the variable focal length of the imaging optics 40 is achieved by moving the lens 44. The lens 44 is part of the optical device 39, which can be, for example, a high-speed collimation, expansion, or focusing device. The lens 44 can be moved back and forth at high speed along the direction of the image rays 32 at the location of the lens 44. This ensures consistently sharp imaging even with rapid changes in the path length from the work area 34 to the camera 30 for the image rays 32 during scanning, and while maintaining high temporal resolution for monitoring.

[0059] The focusing device 16 also includes a variable focal length. In the embodiment of the Fig. The focusing device 16 comprises a fixed lens 52 for pre-focusing the working beam 14, and two movable lenses 54, 56. The focusing device 16 can be controlled such that only one of the lenses 54, 56 moves along the working beam path, or that both lenses move together and in the same direction along the working beam path. This changes the focal length of the working beam 14, i.e., the distance of the focus of the working beam 14 from the reflection point of the second scan mirror 28 changes. This is particularly advantageous because, when scanning the working beam 14 across the work surface 18, the distance from the respective work area 34 to the XY deflection device 22, and thus the optical path length that the working beam 14 travels from the focusing device 16 to the respective work area 34, changes.This change in optical path length can be compensated for by adjusting the focal length, ensuring that the working beam 14 remains focused on the work surface 18 throughout the entire scanning process. With a flat work surface 18, this is also referred to as "plane field compensation." Furthermore, the variable focal length allows for adjustment to different working distances between the work surface 18 and the deflection unit 10.

[0060] The selection of the lens 52 for prefocusing determines the range within which the working distance can be adjusted and for which the deflection unit 10 is designed. If the lens 52 has a shorter focal length, the working distance can be adjusted around a shorter mean working distance, and vice versa. The working distance range corresponds to the range of distances between the plane of the second window 24 and the work surface 18 for which the working beam 14 can be focused on a corresponding work area within the work surface 18 and for which an image can be projected from the work area onto the plane of the camera chip 30 via the respective image rays 32. The size of the work area is determined by the respective working distance and the angular range within which the working beam 14 can be deflected by means of the XY deflection device 22.

[0061] In one exemplary embodiment, the working area can be any size from 200x200 mm. 2 up to 500x500 mm 2 exhibiting, whereby the adjustment to the respective size of the working field can be made using the focusing device 16.

[0062] In the embodiment of the Fig. 1. The movable lenses 54, 56 can also be controlled in such a way that they move in opposite directions along the working beam path, so that only the focus diameter changes and the focus position or the distance from the focus to the XY deflection device 22 does not change. In other words, the focus diameter can be changed without simultaneously changing the beam caustic.

[0063] The two aforementioned control methods can also be combined to ensure that the working beam remains focused on the work surface 18 throughout the entire scanning process, depending on the respective working distance and the current deflection angle or scan angle, which is determined by the current setting of the XY deflection device 22. Simultaneously, the focus diameter can be varied independently of the focus position throughout the entire scanning process. This enables a highly flexible and advantageous process design because the intensity of the working beam on the work surface 18 can be quickly and precisely adjusted to changing process conditions or requirements, such as a change in the powder particle size during the additive manufacturing process or a change in the scanning speed.

[0064] In other less preferred embodiments, the focusing device 16 may also comprise only a movable lens for adjusting the focal length.

[0065] The aforementioned design of the deflection unit 10 according to the invention allows for a particularly advantageous combined execution of a laser working process, for example additive manufacturing by fusion, sintering or melting of powder grains in a powder bed, and simultaneous process observation and process monitoring of the laser working process by means of the camera 30.

[0066] The functionality and advantages of the deflection unit 10 are explained in more detail below.

[0067] The optical element 20, which is arranged in both the working beam path and the image beam path, reflects the wavelength of the working beam 14 and is at least partially transparent to the wavelength of the image rays 32. This causes the image rays 32, which initially enter the deflection unit 10 through the second window 24 in the working beam path opposite to the working beam 14, to be spatially separated from the working beam 14 and, after separation, are directed to the camera 30 via the optical device 39. In other words, the image beam path and the working beam path are superimposed downstream of the optical element 20 in the direction of the working beam 14 (downstream direction) and separated upstream of the optical element 20 in the opposite direction of the working beam 14 (upstream direction).

[0068] In some embodiments, the optical element (20) reflects not only a first wavelength at least partially, but a first wavelength range at least partially, and / or transmits not only another second wavelength at least partially, but one or more other wavelength ranges at least partially. These one or more other wavelength ranges can lie below and / or above the first wavelength range or the first wavelength.

[0069] In the example of the Fig. 1. The optical element 20 consists of a plane-parallel plate that is arranged at an angle in the image beam path. The angle between the surface normal of the plane-parallel plate and the image beam path can, for example, be 45°.

[0070] In some embodiments, the operating wavelength for which the optical element 20 is reflective lies in the range between 1020 nm and 1080 nm, for example at 1070 nm. In some embodiments, the image rays 32 are illuminated by an illuminator (not shown in [reference]). Fig. 1) provided, which can be arranged below the XY deflection device 22 around the working beam path and which illuminates the working surface 18. In some embodiments, illumination is provided with a wavelength of 850 nm, for which the optical element 20 is transparent or at least partially transmitting.

[0071] In an exemplary embodiment, the reflectivity of the optical element 20 at 45° for a wavelength of 1070 nm is over 99%, and the transmission in the wavelength range from 400 nm to 900 nm is >20%, preferably >70%, particularly preferably >90%, and the transmission for the wavelength range from 1300 nm to 2100 nm is >20%, preferably >70%, particularly preferably >90%. Because wavelengths other than the illumination wavelength of, for example, 850 nm can also be transmitted, further properties can be observed and documented, which will be discussed below.

[0072] Since the working beam path and the image beam path are superimposed downstream of the optical element 20, the XY deflection device 22 is used simultaneously for scanning the working beam 14 and for deflecting the image beams 32, which are reflected from the location of the respective working area 34 to the XY deflection device 22, towards the camera 30. This allows the field of view of the camera 30 to be scanned together and synchronously with the working beam 14 across the working surface 18 during the work process, so that the respective working area 34, in the size of the field of view of the camera 30 on the working surface 18, is imaged onto the camera chip, and the process can be monitored and controlled online.

[0073] It is noted that the parameters "camera field of view", "working field", and "working distance" (at which focusing of the working beam 14 is possible) are defined by the deflection unit and are not dependent on the presence of a working surface 18. The camera field of view and the working field correspond to angular ranges with respect to incoming and outgoing rays, respectively, with each of these angular ranges corresponding to a specific surface at a given working distance.

[0074] During scanning, as previously described, the work process can be flexibly designed and varied using the focusing device 16. In particular, plane field compensation and variation of the focus size on the work surface 18 can be carried out independently of one another. It should be noted that the focusing device 16 can also ensure that the focus remains on the work surface 18 during scanning, even on non-flat work surfaces 18, and that the focus can be increased and decreased independently of the focus position.

[0075] Similarly, during scanning, the focal length of the imaging optics 40 can be changed by appropriately controlling the movable lens 44. This allows the focal length to be adjusted for different deflection angles of the XY deflection device 22 during scanning and for different working distances between the deflection unit 10 and the work surface 18, ensuring that the working area 34, at varying distances from the XY deflection device 22, is sharply imaged onto the camera chip. In other words, the optical device 39 of the imaging optics 40 ensures that the image plane always coincides with the chip plane, thereby enabling the respective working area to be sharply imaged onto the camera chip plane with high spatial resolution.

[0076] In the present description, the optical device 39 and the focusing device 16 refer to such elements that are arranged in one of the separate beam paths, i.e. in the upstream direction of the optical element 20, regardless of whether further lenses are arranged together in the working and image beam path in the downstream direction of the optical element 20, which influence the focusing of the working beam 14 and collimation of the image beams 32 but do not change or adjust them over time.

[0077] Because the optical device 39 and the focusing device 16 are spatially separated from each other and each is located only in the image beam path or only in the working beam path, respectively, the adjustment of the working beam 14 by the focusing device 16 does not affect the image beams 32 to be imaged, and the adjustment of the image by the optical device 39 does not affect the working beam 14. This decoupling allows the work process and its observation to be varied simultaneously and independently of each other, without the need to consider the control of the optical device 39 when controlling the focusing device 16, and vice versa. This allows both the work process and the observation to be combined more efficiently, flexibly, robustly, and with less susceptibility to interference.

[0078] Due to the transmission of the image rays 32 through the optical element 20, which is inclined in the image beam path, optical distortion can occur, for example in the form of astigmatism. This can impair the spatial resolution of the image of the working area 34 onto the camera chip. The compensation element 36 serves to compensate for this optical distortion.

[0079] In the deflection unit 10 of the Fig. In the optical element 20, which consists of a plane-parallel plate, the compensation element 36 also consists of a plane-parallel plate with a corresponding optical thickness for the image rays 32. This plate is arranged in the image path with the same inclination but is rotated at an angle of 90° around the optical axis of the image path relative to the optical element 20. In other words, the plane formed by the surface normal of the optical element 20 and the optical axis of the image rays at the location of the optical element 20 is perpendicular to the plane formed by the surface normal of the compensation element 36 and the same optical axis of the image rays at the location of the compensation element 36. This allows the distortion to be compensated or at least reduced, and the working area 34 to be imaged at least approximately without distortion, thus improving the spatial resolution of the process observation.

[0080] The inclination of the compensation element 36 and / or the optical element 20 to the optical axis of the image rays can, for example, be 45°.

[0081] In deflection unit 10, the camera's field of view measures 6 mm x 8 mm at a working distance of 300 mm. The chip measures 2 / 3" or 8.8 mm x 6.6 mm and has 1280 x 1024 pixels. The pixel resolution is therefore approximately 6 µm. The inventors have found that this achieves an optimal compromise between spatial image resolution and temporal resolution for process monitoring, particularly for applications in additive manufacturing. While the spatial resolution can be further increased with a larger number of pixels, a greater imaging path length, a larger chip, or more complex imaging optics, the temporal resolution deteriorates with an increase in the pixel count.

[0082] The working distance corresponds to the distance between the second window 24 and the work surface 18 during the work process. The working area 34, measuring 6 mm x 8 mm, is imaged onto the 8.8 mm x 6.6 mm camera chip using the imaging optics 40, with an imaging ratio (= (6 mm x 8 mm) / (8.8 mm x 6.6 mm) of approximately 0.8). The image path length, which the image rays 32 travel from the entrance to the imaging optics 40, i.e., from the lens 42, until they strike the camera chip, is 480 mm. This image path length of only 480 mm allows the working area 34, measuring 6 mm x 8 mm, to be imaged onto the camera chip with a simple and robust optic at an optical resolution of approximately 15 µm. A longer imaging path length allows for a higher spatial optical resolution, but does not permit such a compact design of the deflection unit 10.The aforementioned imaging path length enables a sufficiently and optimally sharp image and, in particular, a sufficiently high light intensity or illuminance on the chip.

[0083] The 480 mm imaging path length offers a particularly advantageous compromise between a compact design, a sufficiently large camera field of view at the working distance, a sufficiently high image acquisition rate during the workflow, and imaging with the highest possible spatial resolution. This imaging path length enables a sufficiently sharp and optimized image and, in particular, a sufficiently high light intensity for illuminating the chip.

[0084] An area of ​​6 mm x 8 mm is sufficiently large to allow observation of the process itself within a sufficiently large process environment during a reader work process, especially a laser-based additive manufacturing process.

[0085] For good structural representation, the imaged structures should be at least twice the size of the spatial resolution. The optical resolution of 15 µm therefore allows structures down to approximately 30 µm to be displayed with spatial resolution. This is particularly advantageous in additive manufacturing processes with powders, where the particle size can be as small as 45 µm, but is not usually lower. The imaging path length of 480 mm thus provides the necessary spatial resolution for a reliable and accurate spatial evaluation of such processes.

[0086] At the same time, the imaging path length of only 480 mm allows for a high degree of compactness of the deflection unit 10, which is particularly necessary for parallel processing. In parallel processing, several deflection units participate simultaneously in a common building process and must therefore be arranged relatively close to one another.

[0087] The high image acquisition speed, made possible by the 480 mm imaging path length combined with the 2 / 3" camera chip, is also particularly advantageous for laser-based additive manufacturing processes. The scan speed at which the working beam scans across the powder grains or other material can be comparatively high, e.g., 4 m / s, necessitating high image acquisition to ensure continuous process monitoring.

[0088] Camera 30, for example, consists of a high-speed CMOS camera with an image acquisition rate of 1 kHz to 2 kHz. To ensure a continuous and constant high image acquisition rate over a long period, camera 30 can be connected to a frame grabber.

[0089] The illumination is preferably provided by flash and synchronized with the image acquisition of the camera 30. The duration of an illumination flash is preferably longer than the image acquisition time of the camera 30 in the case of the deflection unit 10. This allows each illumination flash to homogeneously illuminate the entire working area available for processing by the deflection unit 10, while simultaneously capturing each image, which may only represent a small portion of the illuminated area, with sufficiently high brightness.

[0090] Furthermore, the off-time of the lighting is preferably longer than the on-time. This prevents excessive heating, which in turn extends the service life and increases process reliability.

[0091] A static, i.e., non-scanned, simultaneous illumination of the entire work area, which is preferably used, enables robust operation and uniform lighting conditions for the entire work area.

[0092] Preferably, the deflection unit 10 also includes one or more control units (not shown) which are configured to control the focusing device 16 and the optical device 39 depending on the setting of the XY deflection device 22 and / or the working distance, and thus to adapt or control the work process and the observation process as described above.

[0093] In addition to process monitoring using camera 30, the deflection unit 10 includes Fig. 1. An additional monitoring option is provided by means of a photodiode 58. The photodiode 58 is arranged behind the second optical element 38, which spatially divides the image beam path into a first beam path to the camera 30 and a second beam path to the photodiode 58. The illumination wavelength, which can be, for example, 850 nm, is reflected by the second optical element 38 as described above, and other wavelengths transmitted by the first optical element 30 are also transmitted by the second optical element 38, so that they can be detected integratively using the photodiode 58.

[0094] In an exemplary embodiment, the second optical element 38 exhibits a reflection of over 99% in the wavelength range of 820 nm to 870 nm and at an angle of incidence of 45°, a transmission of over 94% in the wavelength range of 400 nm to 700 nm, and a transmission of over 93% in the wavelength range of 1200 nm to 2100 nm. This allows the photodiode 58 to monitor the radiation intensity generated at the work process location in these wavelength ranges (400–700 nm and 1200–2100 nm) or parts thereof, thereby enabling the monitoring of additional properties and parameters of the work process.

[0095] In other embodiments, instead of the photodiode 58, another detection device may be provided, for example a pyrometer, a VIR camera sensitive to the visible and infrared wavelength range, and / or a multispectral camera for creating a radiation map or heat map, a thermal image sensor or an optical coherence tomograph.

[0096] In embodiments where the other detection device comprises an optical coherence tomograph, coherence detection can be performed by sending a first illumination beam from the coherence tomograph through the second optical element 38. After passing through the first optical element 20, this beam is superimposed on the working beam and, after reflection from the working surface 18, is directed back to the optical coherence tomograph. There, the reflected first illumination beam is superimposed on a second illumination beam, and an interference pattern is detected using a photodiode. By analyzing the interference pattern, it is possible to determine the surface topography. The surface topography can be determined both immediately before and immediately after the work process, thus providing an additional monitoring capability for the work process.

[0097] Other embodiments include only a camera 30 for process monitoring and lack a photodiode 58 and any other detector device for additional process monitoring. In these embodiments, the second optical element 38 can consist of a mirror that only reflects but does not transmit.

[0098] Other embodiments of the deflection unit according to the invention, not shown, comprise only an optical coherence tomograph for process monitoring and / or process observation, as the first detection device instead of the one described in Fig. The camera 30 shown in Figure 1. These embodiments therefore do not need to include a photodiode 58 or any other detector device for additional process monitoring. In these embodiments, the second optical element 38 can consist of a mirror that only reflects but does not transmit. Coherence detection can be performed as described above, except that the first illumination beam sent by the coherence tomograph is not transmitted through the second optical element 38, but is reflected by it and then directed towards the work surface 18.

[0099] Fig. Figure 2 shows a sectional view of such a deflection unit 110, which has only one camera 30 for process monitoring. As in the Fig. As shown in Figure 2, a more compact design of the deflection unit 110 with the smallest possible imaging path length, which offers the advantages described above, is made possible by deflecting the image beam path within the imaging optics 40 using the deflection mirrors 48, 50.

[0100] Fig. Figure 3 shows a sectional view of a deflection unit 210 according to a further embodiment, which, unlike the deflection unit 10, includes a thermal image sensor instead of the photodiode 58, with which a thermal map of the process environment can be created. The Fig. The camera module 62 shown in Figure 3 comprises the optical device 39 described above and the camera 30. Instead of the camera module 62, an OCT module may also be provided, which comprises an OCT and the optical device 39 described above.

[0101] Fig. Figure 4 shows an external view of the deflection unit 110, including a lighting element 64 arranged in a ring shape, for example, in a circular, square, or other ring shape, around the working beam path. This lighting element is designed to illuminate the work surface 18 homogeneously and with flashing light through the second window 24. The second window 24 includes a protective glass panel held by a bracket 66 within a support frame 68. The support frame 68 may include water cooling to prevent the interior of the deflection unit 10 from overheating.

[0102] As in Fig. As shown in Figure 4, the lighting 64 is preferably arranged externally, i.e., outside the interior of the deflection unit 110, so that the illuminating beams do not illuminate the work surface 18 through the deflection unit 110—or rather, not through its interior. Furthermore, the lighting 64 is statically mounted relative to the housing of the deflection unit 110, and the illuminating beams are not scanned. This avoids or reduces scattered radiation and heating within the deflection unit 110 and makes the process more robust and reliable.

[0103] Fig. Figure 5 shows a top view of four deflection units 110 arranged side by side for parallel processing. In the depicted arrangement, the working areas of adjacent deflection units 110 border seamlessly and can partially overlap in the transition area. This allows the working areas of the deflection units to be combined into a total working area that can be up to four times the size of a single working area. Within this combined total working area, each of the deflection units 110 can process its own sub-area during parallel processing to manufacture a corresponding part of a comparatively large component.This arrangement and the corresponding possibility of parallelized operation are made possible by the fact that each of the deflection units 110 has a working area that extends beyond the projection surface of the deflection unit 110 in the top-down direction onto the plane of the working area. Parallelized operation on a larger working area using multiple deflection units allows for the production of larger components in less time.

[0104] Another possibility for parallel work is in Fig. 6 shown. Fig. Figure 6 shows a top view of two deflection units 110 arranged side by side such that their working areas overlap onto a common working area that can be processed jointly and simultaneously by both deflection units 110. The design of the deflection unit can be so compact, in particular, the projection area of ​​the deflection unit 110 in the top view, also referred to as the "footprint," can be so small compared to the working area, and the working area can extend so far beyond the footprint that the common superimposed working area corresponds to at least 50% of the size of the working area of ​​a single deflection unit 110. In some embodiments, the common superimposed working area can even comprise 70% or more of the area of ​​a single working area.This allows the deflection units to be used particularly efficiently for the accelerated production of components that can also be manufactured with a single deflection unit, but not in such a short period of time or with such good quality.

[0105] In other embodiments, the projection surface of the deflection unit onto the plane of the working field can also lie entirely within the working field. Unlike in the Fig. 5 and Fig. As shown in Figure 6, these deflection units can be arranged so that their working fields overlap with a working field of another of these deflection units on all four sides. LIST OF REFERENCE MARKS 10, 110, 210 Deflection unit 12 first window 14 working beam 16 Focusing device 18 work surface 20 optical element 22 XY deflection device 24 second window 26 first scan mirror 28 second scan mirror 30 Camera 32 image rays 34 Work area 36 Compensation element 38 second optical element 40 Imaging optics 39 Optical device 42, 44, 46 lens 48, 50 deflecting mirrors 52, 54, 56 lens 58 photodiode 60 thermal image sensor 62 camera module 64 Lighting 66 bracket 68 support frames

Claims

Deflection unit (10, 110, 210) comprising: - a first window (12) through which an optical working beam (14) can enter the deflection unit (10, 110, 210); - a second window (24) through which the working beam can exit the deflection unit (10, 110, 210) and through which detection beams (32) from a working area (34) can enter the deflection unit (10, 110, 210) along the respective path of the exiting working beam (14) and in the opposite direction to it; - a first detection device (30); - an optical element (20) that at least partially reflects a first wavelength and at least partially transmits another second wavelength; wherein the deflection unit (10, 110, 210) defines a working beam path that the working beam (14) travels from the first window (12) to the second window. (24) passes through a reflection at the optical element (20), and defines a detection beam path,the detection beams (32) pass through from the second window (24) to the first detection device (30), wherein the detection beams (32) are at least partially transmitted through the optical element (20), wherein the deflection unit (10, 110, 210) further comprises: - an XY deflection device (22) arranged between the second window (24) and the optical element (20) in the working beam path and in the detection beam path to deflect the working beam (14) in order to scan the exiting working beam and simultaneously to deflect the detection beams (32) so that they pass through the detection beam path through the optical element (20) to the first detection device (30); - a focusing device (16) for focusing the working beam (14), wherein the focusing device has a variable focal length and is located in the working beam path between the first window (12) and is arranged the optical element (20),and- an optical device (39) which is arranged in the detection beam path between the optical element (20) and the first detection device (30) and which is configured to change a focal length for the detection beams (32). Deflection unit (10, 110, 210) according to claim 1, wherein the focusing device (16) is configured to change the focal length depending on a setting of the XY deflection device (22) and / or a working distance. Deflection unit (10, 110, 210) according to claim 1 or 2, wherein the focusing device (16) comprises one or more movable lenses (54, 56) and is configured to move one or more of the lenses (54, 56) together along the working beam path. Deflection unit (10, 110, 210) according to one of the preceding claims, wherein the focusing device (16) is configured to change the focus diameter of the working beam (14) without simultaneously changing the focus position. Deflection unit (10, 110, 210) according to claim 4, wherein the focusing device comprises several movable lenses (54, 56) and is configured to move at least two lenses (54, 56) simultaneously and independently of each other. Deflection unit (10, 110, 210) according to one of the preceding claims, wherein the optical element (20) has one or more of the following optical properties: - a reflectance of ≥ 80%, preferably ≥ 90%, particularly preferably ≥ 99% for a working wavelength, in particular a wavelength between 1020 and 1080 nm, - a transmittance of > 20%, preferably > 70%, particularly preferably > 90% for wavelengths between 400 nm to 900 nm, - a transmittance of > 20%, preferably > 70%, particularly preferably > 90% for wavelengths between 1300 nm to 2100 nm. Deflection unit (10, 110, 210) according to one of the preceding claims, wherein the optical element (20) is arranged inclined in the detection beam path and which further comprises an optical compensation element (36) in the detection beam path between the optical element (20) and the first detection device (30), which at least partially compensates for an optical distortion due to transmission through the inclined optical element (20). Deflection unit (10, 110, 210) according to claim 7, wherein the optical element (20) is formed by a first plane-parallel plate and the compensation element (36) is formed by a second plane-parallel plate and both plates are inclined to the detection beam path. Deflection unit (10, 110, 210) according to one of the preceding claims, wherein the optical device (39) is configured for adjusting the collimation, focusing or beam expansion depending on a setting of the XY deflection device (22) and / or a working distance. Deflection unit (10, 110, 210) according to one of the preceding claims, which is configured for machining with a working distance or working distances between 238 mm and 671 mm, preferably between 300 mm and 548 mm. Deflection unit (10, 110, 210) according to one of the preceding claims, which has a working area of ​​size 200x200 mm2 to 500x500 mm2. Deflection unit (10, 110, 210) according to one of the preceding claims, which is dimensioned and designed such that, in operating orientation, its projection surface extends beyond the working field on at least one side, at least two sides, at least three sides or four sides. Deflection unit (10, 110, 210) according to one of the preceding claims, which is dimensioned and designed such that four of these deflection units can be arranged in such a way that, for one or more working distances, their working fields combine to form an uninterrupted, planar overall working field of 3.5 to 4 times the size of the individual working fields. Deflection unit (10, 110, 210) according to one of the preceding claims, which is dimensioned and designed such that two of these deflection units can be arranged such that their working fields overlap on a common working field, wherein the common working field has an area which is at least 50%, preferably at least 60%, particularly preferably at least 70% of the area of ​​a respective individual working field. Deflection unit (10, 110, 210) according to one of the preceding claims, wherein the first detection device is or comprises a camera (30) and which comprises an imaging optic (40) for imaging the working area (34) onto the camera (30), wherein the imaging optic (40) comprises the optical device (39) and the optical device (39) is configured to change the focal length of the imaging optic (40). Deflection unit (10, 110, 210) according to claim 15, wherein the imaging ratio of the imaged area of ​​the working area (34) at the working distance and the area of ​​a camera chip is between 1.7 and 0.5, preferably 0.

8. Deflection unit (10, 110, 210) according to claim 15 or 16, wherein the camera (30) has a chip of size 2 / 3" or 8.8 mm x 6.6 mm, which in particular has 1280 x 1024 pixels, and wherein the imaged area of ​​the working area (34) at the working distance has a size between 6 mm x 8 mm and 10.5 mm x 14 mm. Deflection unit (10, 110, 210) according to one of claims 15 to 17, wherein an imaging path length, which the detection beams (32) traverse from the entrance to the imaging optics (40) to the camera chip, is between 400 mm and 700 mm, preferably between 420 mm and 600 mm, particularly preferably between 450 mm and 510 mm, and in particular 480 mm. Deflection unit (10, 110, 210) according to one of claims 15 to 18, wherein the camera (30) allows an image acquisition rate of ≥ 500 Hz, preferably ≥ 1 kHz, particularly preferably ≥ 1.5 kHz, in particular ≥ 2 kHz. Deflection unit (10, 110, 210) according to one of claims 15 to 19, which further comprises a lighting device (64) to illuminate the entire working field simultaneously with the second wavelength, in particular to illuminate with a homogeneity ≥ 80%. Deflection unit (10, 110, 210) according to claim 20, wherein the lighting device is configured for flashing illumination. Deflection unit (10, 110, 210) according to claim 21, wherein the illumination is flashed such that the image recordings of the camera (30) are each made during an illumination flash and the flash duration is greater than or corresponds to the image acquisition time of the camera (30), and wherein preferably the off time of the illumination is greater than or corresponds to the on time of the illumination. Deflection unit (10, 110, 210) according to one of claims 15 to 22, which further comprises a frame grabber to which the camera (30) is connected. Deflection unit (10, 110, 210) according to one of claims 1 to 14, wherein the first detection device is or comprises an optical coherence tomograph. Deflection unit (10, 210) according to one of the preceding claims, further comprising a second optical element (38) and a second detection device (58), wherein the second optical element (38) is arranged in the image beam path between the optical element (20) and the first detection device (30), reflects at least partially the second wavelength for transmission to the first detection device (30), and transmits at least partially other wavelengths for transmission to the second detection device (58). Deflection unit (10, 210) according to claim 25, wherein the second optical element (38) has one or more of the following optical properties: - a reflectance of ≥ 80%, preferably ≥ 90%, particularly preferably ≥ 95% for an illumination wavelength between 820 nm and 870 nm, preferably at an angle of incidence of 45°, - a transmittance of > 20%, preferably > 70%, particularly preferably > 90% for wavelengths between 400 nm and 700 nm, - a transmittance of > 20%, preferably > 70%, particularly preferably > 90% for wavelengths between 1300 nm and 2100 nm. Deflection unit (10, 110, 210) according to claim 25 or 26, wherein the second detection device comprises a photodiode (58), a pyrometer, a second camera, preferably a VIR camera (60) and / or a multispectral camera for creating a radiation and / or heat map, a thermal image sensor and / or an optical coherence tomograph. Use of a deflection unit (10, 110, 210) according to one of the preceding claims for additive manufacturing, in particular for “Direct Powder Fusion”, Vat Photopolymerization and / or “Direct Energy Deposition”.

Images