SYSTEM FOR ANALYZING AND SORTING A MATERIAL PART

Description

[0001] The invention relates to a system for analyzing and sorting a material part, in particular a scrap piece made of aluminum, comprising a feeding means for transporting the material part, a sorting unit configured to feed the material part to one of two fractions, a laser device configured to generate a plasma on a surface of the material part with a laser beam propagating along a beam axis, a spectrometer system configured to perform a spectral analysis of plasma light emitted by the laser-induced plasma and to generate an output signal corresponding to a result of the spectral analysis performed, and a control device configured to receive the output signal and to operate the sorting unit based on the output signal and a sorting criterion.wherein the spectrometer system comprises a spectrometer and a detection unit optically connected to the spectrometer, the detection unit comprising a lens to which a detection cone is associated which forms a plasma detection region in an overlap region with the laser beam.

[0002] A system of the aforementioned type is known from EP 3 352 919 B1. This previously known system enables the sorting of material parts, particularly scrap aluminum, based on laser-induced plasma spectroscopy, also known as LIBS (laser-induced breakdown spectroscopy). In this process, laser-induced plasma spectroscopy is used to determine the element-specific composition of a material part, i.e., a sample, using a plasma. The plasma is generated on a surface of the material part using high-intensity, focused laser radiation. Light emitted by the plasma is detected and spectrally analyzed to deduce the elemental composition of the material part.

[0003] According to the previously known system, material parts to be sorted are fed to a feeding device. The feeding device can, for example, be vibrating plates that provide a feeding surface along which the material parts are moved.

[0004] Using the feeding device, the material parts to be analyzed and sorted are fed into a chute in accordance with EP 3 352 919 B1. Following the force of gravity, the material parts slide down the chute and exit via a lower edge. From there, the material parts to be analyzed and sorted continue to fall freely through the surrounding atmosphere, still under the force of gravity. The feeding device and the chute serve to separate the material parts and move them in free fall through a spatially defined fall corridor.

[0005] During free fall, each piece of material exiting the slide undergoes laser-induced plasma spectroscopy. For this purpose, a laser device is provided, configured to generate a plasma on the surface of a material piece using a laser beam propagating along a beam axis. Furthermore, a spectrometer system is provided, configured to perform a spectral analysis of the plasma light emitted by the laser-induced plasma and to generate an output signal based on the results of this spectral analysis.

[0006] This output signal, in combination with a sorting criterion, is then used by a sorting unit to direct the material particles exiting the chute into one of two fractions. For example, an air nozzle can be used as the sorting unit, controlled accordingly by the control device. Under the influence of air pressure, specific material particles can be sorted out from the stream of particles leaving the chute. The result is one fraction of sorted and one fraction of unsorted material particles.

[0007] Typically, the known system serves to identify material components of a specific composition and separate them from material components of a different composition. This separation occurs either because a material component with an undesired composition is identified and rejected by the sorting unit, or because the composition of a material component could not be reliably determined, leading to its rejection by the sorting unit. The fraction of rejected material components thus consists of, on the one hand, material components whose composition is clearly identified and undesired, and, on the other hand, material components whose composition is not clearly identified.

[0008] Although the system described above has proven effective in everyday practical use, there is room for improvement. In particular, it has been observed that, despite a defined fall corridor, material particles are sometimes rejected because their composition cannot be clearly identified. This includes material particles that would not have been rejected had their composition been clearly identified. This erroneous rejection is primarily due to the fact that, because of their geometric shape, material particles fall past the plasma detection area of ​​the detection unit's objective lens, even when the fall corridor is adhered to. This is especially true for spherical or semi-spherical material particles.

[0009] Incorrect sorting leads to a detrimental reduction in sorting efficiency. This could potentially be increased by narrowing the drop corridor. However, this is technically complex and also results in a slower sorting speed. Furthermore, this does not reliably guarantee that material samples will not fall past the plasma detection area, because spherical or semi-spherical material samples, in particular, are guided securely by both the feeder and the chute, but can then assume an orientation during free fall that no longer allows for reliable detection of the material composition.

[0010] Another system of this type is known from US 10,088,425 B2. This prior art document also describes an embodiment in which a perforated mirror arrangement is used. Specifically, a mirror is provided between a focusing lens and a laser, which has a hole through which a laser beam generated by the laser is guided to the focusing lens. A detection cone is associated with the focusing lens, which forms a plasma detection area in an overlap region with the laser beam. This prior art system has a further focusing lens to which a detection cone interacting with a detector is associated. In this system, backlight emanating from a plasma is directed parallel by the first focusing lens, deflected by the mirror, and then focused onto the detector in the direction of the beam by the further focusing lens.

[0011] Therefore, starting from the aforementioned state of the art, theTask the invention to constructively further develop a system of the type mentioned above in such a way as to achieve increased sorting efficiency.

[0012] To Solution For this task, a system according to claim 1 is proposed.

[0013] The inventive design advantageously provides an enlarged detection range, resulting in the reliable identification of a greater number of material components with regard to their composition. Consequently, the sorting result is improved, as incorrect sorting is minimized. The result is a more efficient sorting process.

[0014] The increased detection range results from the fact that, unlike the prior art, not just one lens is provided, but several lenses, at least two lenses. However, more than two lenses are preferred, for example three, four or even more lenses.

[0015] Each lens establishes a plasma detection area. With four lenses, there are therefore four plasma detection areas. According to the invention, the lenses are further arranged and / or aligned relative to each other such that the plasma detection areas are offset along the beam axis of the laser beam and together form the field of view of the detection unit. The field of view represents the overall detection area, which is composed of the individual plasma detection areas and is therefore significantly larger than in the prior art.

[0016] According to the prior art, the detection area is thus formed by only one plasma detection area of ​​a lens. Along the beam axis of the laser beam, such a plasma detection area typically extends over a distance of 8 to 10 mm. The composition of the detection unit's field of view according to the invention, consisting of individual plasma detection areas arranged offset along the beam axis, results in a total detection area that extends 20 mm, 30 mm, 40 mm or more in the direction of the beam axis. This advantageously ensures that material parts that would otherwise be undetectable due to their geometric design can be reliably detected, including, in particular, spherically or partially spherically shaped material parts.

[0017] As a result, the system according to the invention allows for improved sorting, since the proportion of rejected material parts, which are rejected because their composition cannot be reliably identified, is minimized.

[0018] According to a further feature of the invention, a plasma detection area is configured such that, in the event of plasma being present within the plasma detection area, a measurement component of the plasma light is detected by the associated lens. Thus, if a laser-induced plasma is present, at least partially, within a plasma area, a measurement component of the emitted plasma light is detected by the associated lens. With multiple lenses according to the invention, this allows the detection unit to detect plasma light in the form of measurement components from individual lenses.

[0019] According to a further feature of the invention, the detection unit has a lens holder that jointly supports a plurality of lenses. This embodiment achieves a compact design. The detection unit has only one lens holder, which supports all the lenses, even those arranged close to one another. This ensures an easy-to-use and compact design.

[0020] According to a further feature of the invention, the plasma detection areas are arranged to merge seamlessly or to be spaced apart along the beam axis. Alternatively or additionally, the plasma detection areas can each extend over 1 / 10 to 1 / 4 of the viewing area along the beam axis. It is therefore possible, particularly after sorting, to create a total detection area by appropriately arranging the plasma detection areas.

[0021] According to a further feature of the invention, the lens holder provides an optical through-opening through which the beam axis passes. The lens holder thus has a through-opening through which the laser beam is guided along the beam axis in the intended use. This further promotes a compact design.

[0022] According to a further feature of the invention, the lens holder has a mounting plate which provides several lens holder openings for receiving a lens and the optical passage opening for the laser beam, wherein the lens holder openings are arranged distributed around the passage opening.

[0023] According to this preferred embodiment, the lens holder has a mounting plate. This mounting plate serves to arrange the individual lenses. Each lens has an opening through which it is inserted and attached to the mounting plate. The mounting plate also has a passage opening for the laser beam. It is particularly preferred to arrange the lens mounting openings around the passage opening for the laser beam. This design feature also contributes to a compact form.

[0024] According to a further feature of the invention, a detection cone extends along an observation axis that runs at an observation angle to the beam axis, wherein the observation angle is between 0° and 90°, preferably between 3° and 60°, and even more preferably between 5° and 25°. The arrangement of the observation angles serves to form an optimized plasma detection area for each objective lens, particularly with regard to its geometric positioning. Depending on the design of the desired viewing window, different observation angles can be selected for the individual objectives, possibly even such that some plasma detection areas are closer to each other than others. However, it is preferred that the observation angles of the individual objectives be approximately the same, for example, with a maximum deviation from each other of less than 3°.

[0025] According to a further feature of the invention, the spectrometer system has a light guidance system that optically connects the detection unit to the spectrometer.

[0026] The spectrometer system thus comprises a spectrometer, a detection unit, and a light guide system, the light guide system serving to optically couple the detection unit to the spectrometer. The plasma light captured by the detection unit is therefore transmitted to the spectrometer via the light guide system, where spectral analysis can then take place.

[0027] According to a further feature of the invention, the light guidance system has a plurality of optical inputs. Preferably, the light guidance system provides a number of optical inputs corresponding to the number of lenses, with each optical input of the light guidance system being assigned to a lens.

[0028] The light guidance system also features an optical output. This optical output serves to transmit the measurement data captured by the lenses. The measurement data acquired by each lens are thus transmitted collectively to the spectrometer via this single optical output.

[0029] The advantage of this design is that all plasma light measurements captured by the lenses for each material part arrive at the spectrometer simultaneously. This allows for the simultaneous processing of all measured values. This significantly reduces the required computing power compared to a separate analysis of the individual measurements.

[0030] According to a further feature of the invention, the optical fiber system comprises several optical fibers, each providing an optical input and combined into a common optical output. Accordingly, optical fibers are provided that are each coupled to a lens on the input side. On the output side, the optical fibers are connected to a common optical output, which terminates optically in the spectrometer as previously described.

[0031] According to a further feature of the invention, it is provided that the laser device, the spectrometer system and the control device are housed in a common housing and form a LIBS module.

[0032] Such a LIBS module is easy to handle, especially to install and maintain. It is also compact in design and, thanks to its housing, robust and protected from external mechanical influences.

[0033] According to a further feature of the invention, the feeding device for transporting the material is configured to transport the material along a feeding surface to an upper section of a chute. In this preferred embodiment, the material is fed to the feeding device. From there, it travels along a feeding surface of the feeding device to an upper section of the chute. Once the material reaches the chute, it moves down it under the force of gravity. The feeding device can, for example, be designed as a vibrating plate, which separates the material pieces fed to the feeding device. The purpose of the chute is, in particular, to align the material and transfer it into a defined drop path.

[0034] According to an alternative embodiment, the feeding device can also be designed as a circulating conveyor belt. In this case, the material parts to be analyzed and sorted lie on the conveyor belt and are moved along by it.

[0035] According to a further feature of the invention, the sorting unit is assigned to a lower edge of the chute opposite the upper section of the chute, wherein the sorting unit is configured to feed the portion of material leaving the chute via the lower edge of the chute to one of two fractions.

[0036] According to this preferred embodiment, a material component leaves the chute in free fall and is subjected to analysis and sorting during this free fall. For this purpose, the laser device and the spectrometer system are arranged vertically below the lower edge of the chute.

[0037] Alternatively, the laser device and / or the spectrometer system can be positioned above the chute and / or the feeder. If, for example, the feeder is a conveyor belt, detection preferably takes place from above. Subsequent sorting can then be carried out either by lateral air bombardment relative to the conveyor belt, or by inspecting the material particles from above, but sorting only occurs after the material particles have left the conveyor belt at the discharge end and are in free fall. In this case, sorting can be performed from any direction.

[0038] Further features and advantages of the invention will become apparent from the following description with reference to the figures. These show Fig. 1 shows a schematic representation of the system according to the invention; Fig. 2 shows a schematic representation of the operation of the LIBS module according to the invention; Fig. 3 shows a further schematic representation of the operation of the LIBS module according to the invention; Fig. 4 shows a schematic representation of the LIBS module according to the invention; Figs. 5a and 5b show a top view and a side view of a first embodiment of a detection unit; Figs. 6a and 6b show a top view and a side view of a second embodiment of a detection unit; and Fig. 7 shows an enlarged schematic representation of the spectrometer system according to the system according to the invention. Fig. 1 .

[0039] Fig. 1 The schematic representation shows the system 100 according to the invention.

[0040] System 100 is configured to subject a material part 120 to laser-induced plasma spectroscopy and to sort it according to the results of the spectral analysis. In the illustrated embodiment, two fractions, F1 and F2, are provided, to which the material part 120 can be assigned. Collection points 170, for example in the form of containers, serve to receive the respective fractions F1 and F2.

[0041] As the schematic representation according Figure 1 As can be further seen, the system 100 has a feeder 110 followed by a chute 130. In its intended use, a material part 120 is fed to the feeder 110. The feeder 110 serves to transport the material part 120 along a feed surface 111 provided by the feeder, up to an upper section 131 of the chute 130. Here, the material part 120 is transferred from the feeder 110 to the chute 130.

[0042] The feeder 110 can be designed as a vibrating plate. It serves in particular to separate a plurality of material parts 120 placed on the feeder 110, so that these can then be fed to the chute 130 at intervals.

[0043] A material component 120, transferred to slide 130, slides down the slide 130 under the influence of gravity until it reaches the lower edge 132 of the slide, which is located opposite the upper section 131 of the slide 130. The primary function of slide 130 is to align the material component 120 and transfer it into a defined fall corridor.

[0044] Upon exiting chute 130, the material part 120 continues to move under the influence of gravity in free fall through the bypass atmosphere. During this fall, it passes through the spectrometer system 1 according to the invention. This system analyzes the material part 120, as will be described in more detail below. Based on the results of a spectral analysis, the spectrometer system 1 generates an output signal. This signal is fed to a control unit 150, which, depending on this output signal and a sorting criterion, operates (i.e., controls) a sorting unit 160. By means of this sorting unit 160, the material part 120 is either deflected during its free fall or no deflection occurs. If no deflection takes place, the material part 120 reaches the collection point 170 of fraction F2.Otherwise, if sorting takes place using sorting unit 160, the material part 120 goes to collection point 170 for fraction F1.

[0045] The spectrometer system 1, which is part of a LIBS module 180 according to the invention, is used to analyze the composition of the material part 120. The LIBS module 180 also includes a laser device 140 and the control device 150. Preferably, the laser device 140, the spectrometer system 1, and the control device 150 are housed in a common casing, which in Figure 1 not shown in detail.

[0046] The laser device 140 in turn consists of further individual components, for example a laser beam source 9, an optical fiber 9A and a focusing optic 11, as can be seen in particular from the exemplary embodiment according to Figure 2 can be seen.

[0047] As will be shown in more detail below, particularly with regard to the Figures 2and 3 As will be explained, the spectrometer system 1 has a detection unit 21, which in turn provides several lenses. Each of these lenses is assigned a detection cone 35, which, in an overlap region with the laser beam 5, each forms a plasma detection area 39. These plasma detection areas 39 are arranged offset from one another along the beam axis of the laser beam 5 and together form a viewing area 41 of the detection unit 21. The viewing area 41 is thus composed of the individual plasma detection areas 39, thereby defining the total detection area covered by the detection unit.

[0048] Fig. 2Figure 1 shows a schematic overview of a spectrometer system 1 for the spectral analysis of plasma light 3A emitted by a laser-induced plasma 3 (schematically represented by a filled circle). Detectable plasma light 3A lies, for example, in the wavelength range of UV light, visible light, near-infrared light, and / or infrared light; in particular, detectable plasma light can lie in the spectral range from approximately 190 nm to approximately 920 nm. In LIBS, the plasma 3 is generated with a laser beam 5 on a surface 7A of a sample 7.

[0049] To generate the laser beam 5, e.g., pulsed, the spectrometer system 1 includes a laser beam source 9. The laser beam source 9 is configured to provide the laser beam parameters required for plasma generation. The laser beam 5 is fed, e.g., via an optical fiber 9A, to a focusing optic 11 and from there onto the surface 7A of the sample 7 (material part 120 according to [reference]). Figure 1The focusing optics 11 can be configured, in particular, as a laser head component with a focusing function, such as an active laser component with a focusing function that specifically affects the spectrum, pulse duration, or pulse energy. The propagation of the laser beam 5 between the focusing optics 11 and the sample 7 occurs along a beam axis 5A. Exemplary focus diameters (1 / e 2 < beam diameter at the beam waist) and focus lengths (twice the Rayleigh lengths) are in the range of <50 µm to >250 µm and in the range of <5 mm to >1,000 mm, respectively.

[0050] Laser parameters can be set / selected in such a way that an area in which plasma generation can take place (also called ignition area) extends, for example, over a length in the range of approximately 5 mm to approximately 50 mm, for example over a length of 10 mm, 20 mm or 30 mm, along the beam axis 5A.

[0051] Fig. 2Figure 1 schematically shows a focal zone 11A elongated along the beam axis 5A, as it forms in the region of the surface 7A of sample 7. The plasma 3 forms due to the interaction of the laser radiation with the material at the surface of sample 7A. In LIBS, typical dimensions (average diameter) of a plasma 3 range from, for example, 0.1 mm to 5 mm (depending on the sample material and laser parameters).

[0052] The spectrometer system 1 further comprises an optical spectrometer 13 for spectral analysis of the plasma light 3A. The optical spectrometer 13 is in Fig. 2The spectrometer 13 is exemplified as a grating spectrometer. In general, the spectrometer 13 comprises at least one dispersive element 13A, e.g., a grating, a prism, or a grating prism, and a pixel-based detector 13B, onto which the plasma light is spectrally spread. Spectral components of the plasma light 3A to be analyzed are assigned to the pixels of the detector 13B. The detector 13B outputs intensity values ​​of the irradiated pixels to an evaluation unit 15, typically a computer with a processor and memory. The evaluation unit 15 outputs a measured spectral distribution 17 and compares it, for example, with stored reference spectra, in order to assign the elements contributing to the plasma light 3A, and thus to the sample 3 under investigation, and to output this as the result of the spectral analysis.

[0053] In the spectrometer 13, a (spectral-dependent) beam input for the plasma light to be analyzed is defined by an entrance aperture 19, usually an entrance slit 19A.

[0054] The spectrometer system 1 further comprises a detection unit 21 with a lens holder 23 and several lenses 25A, 25B, 25C, which are held by the lens holder 23. Three lenses are shown as examples in the figures: two in the image plane and one behind it. The number of lenses used can be selected depending on spatial and optical parameters as well as parameters of the material of the sample to be examined; it is, for example, in the range of 2 to 20, such as 4, 5, 8, 9, or 15 lenses.

[0055] The spectrometer system 1, in particular the detection unit 21, further comprises an optical light guide system 27 that optically connects the objectives 25A, 25B, 25C to the spectrometer 13. The light guide system 27 provides several optical inputs 29, each optically assigned to one of the objectives 25A, 25B, 25C, and one optical output 31 (common to all objectives), which is optically assigned to the entrance aperture 19.

[0056] Each of the lenses 25A, 25B, 25C is configured to detect a measurement component 33 of the plasma light 3A and includes at least one focusing optical element, such as a converging lens or a concave mirror. A detection cone 35 is assigned to each of the lenses 25A, 25B, 25C. The beam axis 5A passes through the detection cones 35, which have a set minimum size in the region of the laser beam 5. Each of the detection cones 35 includes a plasma detection area 39 in an overlap region with the laser beam 5, which is assigned to the corresponding lens 25A, 25B, 25C. For example, the detection cones 35 have a length from an entrance aperture of a lens to the laser beam in the range of 200 mm to 400 mm. As an example, in Fig. 2The plasma 3 is generated in the plasma detection area 39 of the lens 25B, such that the corresponding measurement component 33 of the plasma light 3A is detected by the lens 25B and imaged onto the associated optical input 29 of the light guidance system 27. Measurement components 33 detected by one or more lenses are guided by the optical light guidance system 27 to the common optical output 31 and coupled through the entrance aperture 19 into the optical spectrometer 13 for spectral analysis.

[0057] Fig. 2 Figure 1 shows three lenses, 25A, 25B, and 25C, arranged azimuthally around the beam axis 5A. Lenses 25A and 25B are located on opposite sides of the beam axis 5A and are thus directed towards it from opposite sides. Lens 25C is directed towards the beam axis 5A from behind.

[0058] Another lens (in Fig. 2(not shown) can, for example, be directed from the front onto beam axis 5A or, using a beam splitter, directed along beam axis 5A towards focus zone 11A. For clarification, in Fig. 2 The detection cones 35 are indicated by dashed lines conically conically towards the beam axis 5A, with the focus zone 11A, the plasma 3 and the plasma detection areas 39 being shown oversized in comparison to the detection cones 35 for clarity.

[0059] Fig. 3Figure 23A shows a mounting plate 23A of the detection unit 21 of the LIBS system to illustrate the arrangement and orientation of the lenses 25A, 25B, and 25C. For fixed mounting of the lenses, the mounting plate 23A has lens mounting openings for receiving the lenses 25A, 25B, and 25C. The lens mounting openings are each arranged at a radial distance from the beam axis 5A and are designed for an oblique orientation of the lenses 25A, 25B, and 25C relative to the beam axis 5A. To illustrate the oblique orientation, observation axes 35A of the lenses 25A, 25B, and 25C are shown. In the example shown, the observation axes 35A run at an observation angle α to the beam axis 5A.

[0060] To implement the multifocal concept, the lenses 25A, 25B, and 25C are mounted in the mounting plate 23A (generally arranged and aligned within the mount 23) such that the plasma detection areas 39 are offset along the beam axis 5A. Particularly at comparable viewing angles α, the offset in the direction of the beam axis 5A can be achieved by varying the radial distance of the lenses 25A, 25B, and 25C from the beam axis 5A (optionally with varying insertion depth). Examples of different radial distances R1 and R2 for lenses 25A and 25B are shown in [reference to relevant figure]. Fig. 3 indicated. Alternatively (optionally with a comparable radial distance) the observation angle of at least some of the objectives can be adjusted to the desired offset of the plasma detection areas 39 in the direction of the beam axis 5A (see e.g. Fig. 6B Mixed configurations are also possible.

[0061] In general, the observation angle α can be in the range from 0° (via beam splitter along the laser beam) to 90° (observation orthogonal to the laser beam). The observation angles α shown as examples in the disclosure are in the range of 5° to 15°, for example, in the range of 5° to 10°. The observation axes 35A of adjacent objectives 25A, 25B, 25C converge on the beam axis 5A from different azimuthal directions (azimuthal angle in the plane perpendicular to the beam axis 5A). In the Fig. 3 In the case shown, the observation angles α are comparable for all lenses and do not deviate from each other by more than, for example, 5° or 1° (deviation due, for example, to permissible manufacturing tolerances of the lens mounting openings and lenses). However, the arrangement of the Fig. 3the radial distances to the beam axis 5A. Accordingly, comparable spectra can be recorded from the plasma detection areas 39 of the different objectives for a sample at different positions of the sample surface along the beam axis 5A (corresponding to different measurement constellations within a measurement process), for example from objective 25B with a surface profile according to the solid line (surface 7A of sample 7 from Fig. 2 ) or from lens 25A in the case of a surface gradient according to the dashed line 7A' or from lens 25C in the case of a surface gradient according to the dashed line 7A".

[0062] As in Fig. 3 As indicated, the plasma detection areas 39 together form a viewing area 41 of the detection unit 21. The viewing area 41 extends along the beam axis 5A in the region of the focus zone 11A.

[0063] Each of the plasma detection areas 39 is assigned a measurement depth along the beam axis 5A. The measurement depth corresponds in Fig. 3 e.g., the diameter of the circles that illustrate the plasma detection areas 39. For a lens, the measurement depth is a specific characteristic determined by optical parameters such as the focus length and aperture of the lens, as well as by the arrangement and orientation of the lens (e.g., geometric position parameters of the lens with respect to the beam axis 5A – distance and angle). For example, the plasma detection areas 39 along the beam axis 5A can each extend over a measurement depth of approximately 5 mm to approximately 15 mm, and in particular over a measurement depth of approximately 5 mm to approximately 12 mm. In some embodiments, the plasma detection areas 39 along the beam axis 5A can extend over 1 / 10 to 1 / 4 of the viewing area 41. Fig. 3In the multifocal concept, the plasma detection areas 39, which are arranged offset along the beam axis 5A, are, for example, spaced apart at a distance D on the order of the measurement depth (here approximately twice the diameter of the plasma detection areas 39). Alternatively, the plasma detection areas 39 can be adjacent to one another or partially overlap (for example, in the range of 10% of the measurement depth). In this way, the lenses can detect plasma light from different sections of the viewing area 41 along the beam axis 5A.

[0064] Furthermore, one can recognize in Fig. 3 an optional protective window 43A, which can be provided in the area of ​​an optical through-hole 43 in the mounting plate 23A, in order to direct the laser beam through the mounting 23 and past the lenses 25A, 25B, 25C onto the sample 7.

[0065] Fig. 4Figure 1 shows a perspective view of an exemplary LIBS measuring head 51, which is connected to a laser beam source via an optical fiber 9A. The mounting 23 of the LIBS measuring head 51 comprises a longitudinal support plate 23B, on which a mounting for the optical fiber 9A and the focusing optics 11 (laser head with beam shaping) is provided on the input side. The optical spectrometer 13 is also attached to the longitudinal support plate 23B, as is the mounting plate 23A for the four lenses 25A, 25B, 25C, 25D (generally an n>1-fold entrance optic). The lenses 25A, 25B, 25C, and 25D are configured to detect plasma light components from plasma detection areas 39, which are arranged offset from one another along the beam axis 5A, and to transmit them via the light guidance system 27 (for example, a fiber bundle with n>1 inputs and one functional output – an "n-to-1 fiber bundle") to the spectrometer 13 for spectral analysis. Examples are shown in Fig. 4Two optical fibers 45 of the light guidance system 27 are shown, which optically connect the lenses 25B and 25C to the common spectrometer 13. The light guidance system 27 allows the measurement components in the spectrometer 13 (or optionally before coupling into the spectrometer 13) to be combined for a single measurement process.

[0066] The n-fold viewing of the field of view with multiple (in Fig. 4 Four objectives allow for a significant increase in depth of field, achieved by aligning the plasma detection areas of the objectives. This makes it possible to efficiently analyze even structured, non-uniform samples. Furthermore, the sample is viewed from different angles, which reduces shadowing effects. The acquired measurement data is combined at a common output of the optical system (sum of all observations) and subjected to a single spectral analysis.

[0067] An n-on-1 fiber bundle allows multiple lenses to be fed into a spectrometer, and multiple n-on-1 bundles can be used for feeding into multiple spectrometers.

[0068] The exemplary design in the Fig. 3 The detection unit 21 shown is further illustrated by Figures 4A and 4B. Fig. 5A Figure 1 shows a top view of the mounting plate 23A. The optical aperture 43 in the center allows the laser beam to pass through (laser beam axis 5A). Four lens mounting openings 53A, 53B, 53C, 53D are arranged azimuthally around the aperture 43 at varying radial distances from the beam axis 5A. They are equally spaced azimuthally, so that two lens mounting openings are always opposite each other in pairs. In the perspective view of the Fig. 5BFour identical lenses 25A, 25B, 25C, 25D are inserted into the lens mounting openings 53A, 53B, 53C, 53D. The lenses 25A, 25B, 25C, 25D were inserted to different depths into the lens mounting openings 53A, 53B, 53C, 53D, so that, depending on the radial distance, the associated plasma detection areas 39 are arranged side by side in the direction of the beam axis and thus form the viewing area 41 of the detection unit 21, which determines the depth of field.

[0069] An alternative design will be presented in the Figures 6A and 6B This is illustrated. In the top view of the mounting plate 23A, four lens mounting openings 55A, 55B, 55C, 55D can be seen, which are arranged symmetrically at the same radial distance from the through-hole 43 and distributed evenly around it. As in the perspective view of the Fig. 6BAs indicated, the offset of the plasma detection areas 39 in the direction of the beam axis 5A is caused by different viewing angles of the lenses 25A, 25B, 25C, and 25D used. For example, at a radial distance of 30 mm, the viewing angles can range from 3° to 15°, so that the viewing area 41 is formed at a distance of approximately 100 mm from the mounting plate 23A. With different viewing angles (and optionally viewing heights), the detected spectral distributions can vary in the case of a large-volume plasma. However, especially with a small-volume plasma, such as that usually generated for LIBS, these differences in the spectral distribution are negligible, since essentially the entire plasma lies within a single plasma detection area 39.

[0070] Fig. 7 shows once again a detailed view of the system 100 according to the invention. Fig. 1It can be seen here that different material components are provided in their composition, namely material components 120B made of plastic and material components 120A made of aluminum. As previously described, sorting can take place using the spectrometer system 1 according to the invention, such that the material components 120A are separated from the material components 120B. For this purpose, the sorting unit 160 removes a plastic material component 120B if it is detected. The sorting unit 160 has an air pressure nozzle for this purpose, by means of which a plastic component 120B can be removed from the stream of material components. As a result of such sorting, the plastic material components 120B and the aluminum material components 120A collect separately at the collection points 170. Reference sign 1 Spectrometer system 35 Detection cone 3 plasma 35A Observation axes 3A Plasma light 37 Overlap area 5 laser beam 39 Plasma detection range 5A Beam axis 41 Visible area 7 sample 43 optical opening 7A surface 43A Protective window 7A' dashed line 45 optical fiber 7A" dashed line 51 LIBS measuring head 9 Laser beam source 53A Lens mount opening 9A optical fiber 53B Lens mount opening 11 Focusing optics 53C Lens mount opening 11A Focus zone 53D Lens mount opening 13 optical spectrometer 55A Lens mount opening 13A dispersive element 55B Lens mount opening 13B detector 55C Lens mount opening 15 Evaluation unit 55D Lens mount opening 17 spectral distribution 57A Lens mount opening 19 Entrance aperture 57B Lens mount opening 19A Entry gap 57C Lens mount opening 21 Detection unit 57D Lens mount opening 23 lens mount D Distance 23A Mounting plate R1,R2 radial distances 23B longitudinal beam plate α Observation angle 25A lens 100 system 25B lens 110 Feeding agent 25C lens 111 Feed area 25D lens 120 Material part 27 Light guidance system 120A aluminum part 29 optical input 120B plastic part 31 optical output 130 slide 33 Measurement component 131 upper section 132 lower edge 140 laser device 150 Control device 160 Sorting unit 170 Collection point 180 LIBS module

Claims

1. System for analyzing and sorting a piece of material, in particular an aluminum scrap piece, comprising: - a feeder (110) for conveying the piece of material (120), - a sorting unit (160) configured to supply the piece of material (120) to one of two fractions (F1, F2), - a laser device (140) configured to generate a plasma (3) on a surface 7A of the piece of material (120) by means of a laser beam (5) propagating along a beam axis (5A), - a spectrometer system (1) configured to perform a spectral analysis of plasma light (3A) emitted from the laser-induced plasma (3) and to generate an output signal corresponding to a result of the spectral analysis performed, and - a control device (150) configured to receive the output signal and to operate the sorting unit (160) based on the output signal and a sorting criterion, - wherein the spectrometer system (1) comprises a spectrometer (13) and a detection unit (21) optically coupled to the spectrometer (13), - wherein the detection unit (21) comprises a first objective (25A, 25B, 25C, 25D) having a first detection cone (35) assigned to it, which creates a plasma detection zone (39) in an overlap region (37) with the laser beam (5), wherein the first objective (25A, 25B, 25C, 25D) has a radial distance (R1, R2) to the beam axis (5A) of the laser beam (5) and a first observation angle (α) relative to the beam axis (5A) of the laser beam (5), characterized in that the detection unit (21) comprises a further objective (25A, 25B, 25C, 25D) having a further detection cone (35) assigned to it, which creates a further plasma detection zone (39) in a further overlap region (37) with the laser beam (5), wherein the beam axis (5A) of the laser beam (5) runs through the first detection cone (35) of the first objective (25A, 25B, 25C, 25D) and through the further detection cone (35) of the further objective (25A, 25B, 25C, 25D), wherein the further objective (25A, 25B, 25C, 25D) has a further radial distance (R1, R2) to the beam axis (5A) of the laser beam (5) which is different from the first radial distance (R1, R2) of the first objective (25A, 25B, 25C, 25D) and / or wherein the further objective (25A, 25B, 25C, 25D) has a further observation angle (α) relative to the beam axis (5A) of the laser beam (5), which is different from the first observation angle (α) of the first objective (25A, 25B, 25C, 25D).

2. System according to claim 1, characterized in that a plasma detection zone (39) is configured such that when a plasma (3) is present in the plasma detection zone (39), a measurement share (33) of the plasma light (3A) is detected by the associated objective (25A, 25B, 25C, 25D).

3. System according to claim 1 or 2, characterized in that the detection unit (21) comprises an objective holder (23) which holds a plurality of objective (25A, 25B, 25C, 25D) jointly.

4. System according to any of the preceding claims, characterized in that the plasma detection zones (39) are arranged along the beam axis (5A) such that they merge into each other or are spaced from each other.

5. System according to claim 3 or 4, characterized in that the objective holder (23) provides an optical passage opening (43) through which the beam axis (5A) passes.

6. System according to any of the preceding claims 3 to 5, characterized in that the objective holder (23) comprises a mounting plate (23A) which provides several objective mounting openings for the respective mounting of an objective (25A, 25B, 25C, 25D) and the optical passage opening (43) for the laser beam (5), wherein the objective mounting openings are distributed around the passage opening (43).

7. System according to any of the preceding claims, characterized in that a detection cone (35) extends along an observation axis (35A) which extends at an observation angle α, wherein the observation angle α is between 0° and 90°, preferably between 3° and 60°, more preferably between 5° and 25°.

8. System according to any of the preceding claims, characterized in that the spectrometer system (1) includes a light guide system (27) which optically couples the detection unit (21) to the spectrometer (13).

9. System according to claim 8, characterized in that the light guide system (27) provides a number of optical inputs (29) corresponding to the number of objectives (25A, 25B, 25C, 25D) and an optical output (31), wherein the optical inputs (29) are each configured to receive the measurement share (33) captured by the associated objective (25A, 25B, 25C, 25D) and wherein the optical output (31) is configured to deliver the measurement shares (33) captured by the objectives (25A, 25B, 25C, 25D).

10. System according to claim 9, characterized in that the light guide system (27) comprises several optical fibers (45) which each provide an optical input (29) and which are combined into a common optical output (31).

11. System according to any of the preceding claims, characterized in that the laser device (160), the spectrometer system (1) and the control device (150) are accommodated in a common housing and constitute a LIBS module.

12. System according to any of the preceding claims, characterized in that the feeder (110) is configured to convey the piece of material (120) along a feed surface (111) toward an upper section (131) of a chute.

13. System according to claim 12, characterized in that the sorting unit (160) is assigned to a lower edge (132) of the chute (130) opposite the upper section (131) of the chute (130), wherein the sorting unit (160) is configured to supply the piece of material (120) leaving the chute (130) via the lower edge (132) of the chute (130) to one of two fractions (F1, F2).