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 part made of aluminum, comprising a feed 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 using a laser beam propagating along a beam axis, a spectrometer system configured to perform a spectral analysis of a plasma light emitted by the laser-induced plasma and to generate an output signal in accordance with a result of the performed spectral analysis, and a control device configured to receive the output signal and 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, wherein the detection unit comprises an objective lens to which a detection cone is assigned, which forms a plasma detection region in an overlap region with the laser beam.

[0002] A system of the type described above, i.e. of the generic type, is known from EP 3 352 919 B1. The previously known system enables the sorting of material parts, in particular aluminum scrap parts, based on laser-induced plasma spectroscopy, also known as LIBS (laser-induced breakdown spectroscopy). 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 determine the elemental composition of the material part.

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

[0004] According to EP 3 352 919 B1, the material pieces to be analyzed and sorted are fed into a chute by means of the feeder. Following gravity, the material pieces slide down the chute and exit via a lower edge of the chute. From there, the material pieces to be analyzed and sorted continue to fall freely through the ambient atmosphere, still subject to the force of gravity. The feeder and the chute serve to separate the material pieces and move them in free fall through a spatially defined drop corridor.

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

[0006] This output signal, in combination with a sorting criterion, is then used by a sorting unit to direct the material parts leaving the chute into one of two fractions. For example, an air nozzle can be used as a sorting unit, which is controlled accordingly by the control device. From the stream of material parts leaving the chute, certain material parts can be sorted out under the influence of air pressure. The result is a fraction of sorted-out material parts and a fraction of non-sorted material parts.

[0007] Typically, the known system is used to identify material components of a specific composition and separate them from material components of a different composition. Such separation occurs either because a material component of an undesired composition is identified and rejected by the sorting unit, or because the composition of a material component could not be reliably determined and therefore rejected by the sorting unit. The fraction of rejected material components is therefore composed of material components whose composition is clearly identified as undesirable, on the one hand, and material components whose composition is not clearly identified, on the other.

[0008] Although the system described above has proven itself in everyday practical use, there is room for improvement. In particular, it has been found that, despite a defined drop corridor, material parts are rejected because their composition cannot be clearly identified. This also results in the rejection of material parts that would not have been rejected had they been clearly identified. This incorrect rejection is primarily due to the fact that, due to their geometric shape, material parts fall past the plasma detection area of ​​the detection unit's lens despite adhering to the drop corridor. This is particularly the case with spherical or partially spherical material parts.

[0009] Incorrect sorting disadvantageously leads to reduced sorting efficiency. This could possibly be further improved by narrowing the drop corridor. However, this is technically complex and also leads to a slowing of the sorting speed. Furthermore, this approach cannot be reliably guaranteed that material pieces to be analyzed will not fall past the plasma detection area. Spherical or hemispherical material pieces, in particular, are guided securely by both the feeder and the chute, but can then assume an orientation in free fall that no longer allows reliable detection of the material composition.

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

[0011] Therefore, based on the above-described state of the art,Task The invention is to further develop a system of the type mentioned at the outset in such a way that increased sorting efficiency is achieved.

[0012] To Solution To achieve this object, the invention proposes that the detection unit has a further objective lens to which a further detection cone is assigned, which forms a further plasma detection area in a further overlap area with the laser beam, wherein the objectives are arranged and / or aligned in relation to one another such that the plasma detection area and the further plasma detection area are arranged offset along the beam axis of the laser beam and together form a field of view of the detection unit.

[0013] The inventive design advantageously provides an enlarged detection range, resulting in a greater number of material components being reliably identified with regard to their composition. Consequently, the sorting result is improved because incorrect sorting is minimized. The result is increased sorting efficiency.

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

[0015] Each lens creates one plasma detection area. Four lenses therefore create four plasma detection areas. According to the invention, the lenses are further arranged and / or aligned relative to one another 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 formed by only one plasma detection area of ​​a lens. Along the beam axis of the laser beam, such a plasma detection area can typically extend over a distance of 8 to 10 mm. The inventive composition of the field of view of the detection unit from individual plasma detection areas arranged offset along the beam axis results in an overall detection area that has an extension of 20 mm, 30 mm, 40 mm, or more in the direction of the beam axis. This advantageously ensures that otherwise undetectable material parts can be reliably detected due to their geometric configuration, including, in particular, spherical or partially spherical material parts.

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

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

[0019] According to a further feature of the invention, the detection unit comprises a lens mount that collectively supports a plurality of lenses. This refinement achieves a compact design. The detection unit has only one lens mount. This mount supports all lenses, which can be arranged in close proximity to one another. This ensures an easy-to-handle and compact design.

[0020] According to a further feature of the invention, the plasma detection regions are arranged along the beam axis so that they merge into one another or are spaced apart from one another. Alternatively or additionally, the plasma detection regions can each extend along the beam axis over 1 / 10 to 1 / 4 of the field of view. It is thus possible, particularly after the sorting task, to form an overall resulting detection region by appropriately arranging the plasma detection regions.

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

[0022] According to a further feature of the invention, the lens holder comprises a holder plate which provides a plurality of lens holder openings for respectively receiving a lens and the optical through-opening for the laser beam, wherein the lens holder openings are arranged distributed around the through-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 the lens is guided and secured to the mounting plate. The mounting plate also has the through-opening for the laser beam. It is particularly preferred to distribute the lens holder openings around the through-opening for the laser beam. This design feature also supports the creation of a compact design.

[0024] According to a further feature of the invention, a detection cone extends along an observation axis which runs at an observation angle to the beam axis, wherein the observation angle is between 0° and 90°, preferably between 3° and 60°, even more preferably between 5° and 25°. The establishment of the observation angles serves to form an optimized plasma detection area for each objective, in particular 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 one another than others. However, it is preferred to design the observation angles of the individual objectives to be approximately the same size, for example with a maximum deviation from one another of less than 3°.

[0025] According to a further feature of the invention, it is provided that the spectrometer system has a fiber optic system that optically connects the detection unit to the spectrometer.

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

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

[0028] The fiber optic system also features an optical output. This output serves to transmit the measurement components captured by the lenses. The measurement components captured at the input side by each lens are thus transmitted jointly to the spectrometer via the 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 simultaneous processing of all measurements. This significantly reduces the required computing power compared to separate analysis of the individual measurements.

[0030] According to a further feature of the invention, the fiber optic system comprises a plurality of optical fibers, each providing an optical input and combined to form a common optical output. Accordingly, optical fibers are provided, each coupled to a lens on the input side. On the output side, the optical fibers are connected to a common optical output, which optically terminates in the spectrometer in the manner already 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 accommodated in a common housing and form a LIBS module.

[0032] Such a LIBS module is easy to handle, especially when installed and maintained. 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 feed means for transporting the material part is designed to transport the material part along a feed surface up to an upper section of a chute. According to this preferred embodiment, the material part is fed to the feed means. From there, it reaches a chute, where it is transported along a feed surface of the feed means up to an upper section of the chute. As soon as the material part has reached the chute, it moves down the chute following the force of gravity. The feed means can, for example, be designed as an oscillating plate, which causes the material parts fed to the feed means to be separated. The purpose of the chute is, in particular, to align the material part and transfer it into a defined drop corridor.

[0034] According to an alternative embodiment, the feed means can also be designed as a revolving conveyor belt. In this case, the material parts to be analyzed and sorted rest on the conveyor belt and are moved forward by it.

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

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

[0037] Alternatively, the laser device and / or the spectrometer system can also be arranged above the chute and / or the feeder. For example, if the feeder is designed as a conveyor belt, detection preferably occurs from above, with subsequent sorting then taking place either by arranging air spray from the side of the conveyor belt, or by observing the material pieces from above, but sorting only taking place after the material pieces have left the conveyor belt at the discharge end and are in free fall. In this case, sorting can take place from any direction.

[0038] Further features and advantages of the invention will become apparent from the following description with reference to the figures. Fig. 1 shows a schematic representation of the system according to the invention; Fig. 2 shows a schematic representation of the functioning of the LIBS module according to the invention; Fig. 3 shows a further schematic representation of the functioning 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 plan view and a side view of a first embodiment of a detection unit; Figs. 6a and 6b show a plan 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 according to Fig. 1 .

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

[0040] The system 100 is configured to subject a material part 120 to laser-induced plasma spectroscopy and to sort it depending on the result 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 to Figure 1 As can also be seen, the system 100 has a feeding means 110 followed by a chute 130. In the intended use, a material part 120 is fed to the feeding means 110. The feeding means 110 serves to transport the material part 120 along a feed surface 111 provided by the feeding means, specifically up to an upper section 131 of the chute 130. Here, the material part 120 is transferred from the feeding means 110 to the chute 130.

[0042] The feed means 110 can be designed as a vibrating plate. It serves, in particular, to separate a plurality of material pieces 120 placed on the feed means 110, so that they can then be fed to the chute 130 at a distance from one another.

[0043] A material part 120 transferred to the chute 130 slides down the chute 130 following gravity until it reaches the lower edge 132 of the chute, which is opposite the upper section 131 of the chute 130. The particular task of the chute 130 is to align the material part 120 and transfer it into a defined fall corridor.

[0044] Upon leaving the chute 130, the material part 120 continues to fall freely through the bypass atmosphere under the influence of gravity. In doing so, it passes through the spectrometer system 1 according to the invention. This ensures an analysis of the material part 120, as will be described in more detail below. In accordance with the result of a performed spectral analysis, the spectrometer system 1 generates an output signal. This is fed to a control device 150, which operates, i.e., controls, a sorting unit 160 as a function of this output signal on the one hand and a sorting criterion on the other. By means of this sorting unit 160, the material part 120 is either deflected in its free fall or no deflection occurs. If no deflection occurs, the material part 120 reaches the collection point 170 of fraction F2.Otherwise, if sorting takes place by means of the sorting unit 160, the material part 120 reaches the collection point 170 for the 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 accommodated in a common housing, which in Figure 1 is 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 optics 11, as is particularly evident from the embodiment according to Figure 2 can be seen.

[0047] As will be shown in more detail below, particularly with regard to Figures 2and 3 As will be explained, the spectrometer system 1 has a detection unit 21, which in turn provides several objectives. Each of these objectives is assigned a detection cone 35, which each form a plasma detection area 39 in an overlap area with the laser beam 5. 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 therefore composed of the individual plasma detection areas 39, thereby defining the detection area covered by the detection unit as a whole.

[0048] Fig. 2shows a schematic overview of a spectrometer system 1 for the spectral analysis of a plasma light 3A emitted by a laser-induced plasma 3 (schematically indicated as 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, plasma light to be detected 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, e.g., pulsed, laser beam 5, the spectrometer system 1 comprises a laser beam source 9. The laser beam source 9 is designed 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 optics 11 and from there onto the surface 7A of the sample 7 (material part 120 according to Figure 1). The focusing optics 11 can be designed, in particular, as a laser head component with a focusing function, such as an active laser component with a focusing function that acts, in particular, on the spectrum or the pulse duration or the pulse energy. The propagation of the laser beam 5 between the focusing optics 11 and the sample 7 occurs along a beam axis 5A. Example focus diameters (1 / e 2< -beam diameter in the beam waist) and focus lengths (double Rayleigh lengths) are in the range from <50 µm to >250 µm and in the range from <5 mm to >1,000 mm, respectively.

[0050] Laser parameters can in particular be set / selected such that a region in which plasma generation can take place (also referred to as ignition region) 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. 2schematically shows a focal zone 11A elongated along the beam axis 5A, as it is formed in the area of ​​the surface 7A of the sample 7. The plasma 3 forms due to the interaction of the laser radiation with the material on the surface of the sample 7A. In LIBS, typical dimensions (average diameter) of a plasma 3 are in the range of, 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. 2exemplified 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 impinges in a spectrally expanded manner. 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 a memory. The evaluation unit 15 outputs a measured spectral distribution 17 and compares it, for example, with stored comparison spectra in order to assign the elements contributing to the plasma light 3A to the plasma light 3A and thus to the sample 3 under investigation and to output them as the result of the spectral analysis.

[0053] In the spectrometer 13, a (spectral-dependent) beam entrance 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 an objective mount 23 and a plurality of objectives 25A, 25B, 25C held by the objective mount 23. Three objectives are shown in the figures as an example: two in the image plane and one behind it. The number of objectives 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, for example, 4, 5, 8, 9, or 15 objectives.

[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 a plurality of optical inputs 29, each optically associated with one of the objectives 25A, 25B, 25C, and an optical output 31 (functionally common to the objectives) that is optically associated with the entrance aperture 19.

[0056] Each of the objectives 25A, 25B, 25C is configured to capture a measurement portion 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 objectives 25A, 25B, 25C. The beam axis 5A extends through the detection cones 35, with the detection cones 35 having a set minimum size in the region of the laser beam 5. Each of the detection cones 35 includes, in an overlap region with the laser beam 5, a plasma detection region 39 that is assigned to the corresponding objective 25A, 25B, 25C. For example, the detection cones 35 have a length from an entrance aperture of an objective to the laser beam in the range of 200 mm to 400 mm. For example, Fig. 2the plasma 3 is generated in the plasma detection area 39 of the lens 25B, so that the associated measurement portion 33 of the plasma light 3A is detected by the lens 25B and imaged onto the associated optical input 29 of the light guide system 27. Measurement portions 33 detected by one or more lenses are guided by the optical light guide 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 shows, as an example, three lenses 25A, 25B, 25C, which are arranged azimuthally distributed around the beam axis 5A. The lenses 25A and 25B are located on opposite sides of the beam axis 5A and are thus directed onto the beam axis 5A from opposite sides. The lens 25C is directed onto the beam axis 5A from behind. Another lens (in Fig. 2not shown) can, for example, be directed from the front onto the beam axis 5A or, using a beam splitter, along the beam axis 5A onto the focus zone 11A. For clarification, Fig. 2 the detection cones 35 are indicated by dashed lines as tapering conically towards the beam axis 5A, whereby the focus zone 11A, the plasma 3 and the plasma detection areas 39 are shown oversized compared to the detection cones 35 for clarity.

[0058] Fig. 3shows a mounting plate 23A of the detection unit 21 of the LIBS system to illustrate the arrangement and alignment of the lenses 25A, 25B, 25C. For stationary mounting of the lenses, the mounting plate 23A has lens mounting openings for receiving the lenses 25A, 25B, 25C. The lens mounting openings are each arranged at a radial distance from the beam axis 5A and are designed for an oblique alignment of the lenses 25A, 25B, 25C to the beam axis 5A. To illustrate the oblique alignment, observation axes 35A of the lenses 25A, 25B, 25C are shown. In the example shown, the observation axes 35A run at an observation angle α to the beam axis 5A.

[0059] To implement the multifocal concept, the lenses 25A, 25B, 25C are mounted in the mounting plate 23A (generally arranged and aligned in the mount 23) such that the plasma detection areas 39 are offset along the beam axis 5A. Particularly with comparable observation 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, 25C from the beam axis 5A (optionally with varying insertion). Different radial distances R1 and R2 for the lenses 25A and 25B are shown in Fig. 3 Alternatively (optionally with a comparable radial distance) the observation angle of at least some of the lenses can be adapted 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.

[0060] In general, the observation angle α can be in the range from 0° (via beam splitters along the laser beam) to 90° (observation orthogonal to the laser beam). The observation angles α shown as examples within the scope of the disclosure are in the range from 5° to 15°, for example in the range from 5° to 10°. The observation axes 35A of adjacent lenses 25A, 25B, 25C converge from different azimuthal directions towards the beam axis 5A (azimuthal angle in the plane perpendicular to the beam axis 5A). In Fig. 3 In the case shown, the observation angles α are comparable for all lenses and do not differ by more than 5° or 1° (deviation given, for example, by permitted manufacturing tolerances of the lens holder openings and lenses). However, the arrangement of the Fig. 3the radial distances to the beam axis 5A. Accordingly, comparable spectra can be recorded by 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 by the objective 25B for a surface profile according to the solid line (surface 7A of the sample 7 from Fig. 2 ) or by the lens 25A in the case of a surface profile according to the dot-dash line 7A' or by the lens 25C in the case of a surface profile according to the dot-dash line 7A".

[0061] 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.

[0062] Each of the plasma detection areas 39 is assigned a measuring depth along the beam axis 5A. The measuring depth corresponds in Fig. 3 e.g., a diameter of the circles that illustrate the plasma detection areas 39. For a lens, the measurement depth is a specific feature that is determined by optical parameters such as the focal 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, 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 field of view 41. In Fig. 3In the multifocal concept, the plasma detection regions 39, which are offset along the beam axis 5A, are arranged, for example, at a distance D in the order of magnitude of the measurement depth (here approximately twice the diameter of the plasma detection regions 39). Alternatively, the plasma detection regions 39 can be adjacent to one another or partially overlap (for example, within 10% of the measurement depth). In this way, the lenses can detect plasma light from different sections of the field of view 41 along the beam axis 5A.

[0063] Furthermore, one can see in Fig. 3 an optional protective window 43A, which can be provided in the region of an optical through-opening 43 in the mounting plate 23A in order to be able to direct the laser beam through the mounting 23 and past the objectives 25A, 25B, 25C onto the sample 7.

[0064] Fig. 4shows a perspective view of an exemplary LIBS measuring head 51, which is connected to a laser beam source via an optical fiber 9A. The holder 23 of the LIBS measuring head 51 comprises a longitudinal support plate 23B, on which a fastening for the optical fiber 9A and the focusing optics 11 (laser head with beam shaping) is provided on the input side. Furthermore, the optical spectrometer 13 is attached to the longitudinal support plate 23B, as well as the mounting plate 23A for the four objectives 25A, 25B, 25C, 25D (generally an n>1-fold entrance optics). The lenses 25A, 25B, 25C, 25D are configured to capture measurement components of plasma light from plasma detection areas 39, which are arranged offset from one another along the beam axis 5A, and to feed them to the spectrometer 13 for spectral analysis via the fiber optic system 27 (for example, a fiber bundle with n>1 inputs and one functional output - "n-to-1 fiber bundle"). Examples are shown in Fig. 4Two optical fibers 45 of the optical fiber system 27 are shown, which optically connect the lenses 25B and 25C with the common spectrometer 13. With the optical fiber system 27, the measurement components can be combined in the spectrometer 13 (or optionally before coupling into the spectrometer 13) for a measurement process.

[0065] The n-fold observation of the field of view with several (in Fig. 4 Four) lenses allow for a significant increase in depth of field, achieved by arranging the plasma detection areas of the lenses side by side. This makes it possible to efficiently analyze even samples with structured, irregular surfaces. Furthermore, the sample is viewed from different angles, which can reduce shadowing effects. The acquired measurement components are combined at a common output of the fiber optic system (sum of all observations) and fed into a common spectral analysis.

[0066] An n-to-1 fiber bundle allows multiple lenses to be fed into a spectrometer, whereby multiple n-to-1 bundles can be used to feed multiple spectrometers.

[0067] The exemplary design in the Fig. 3 The detection unit 21 shown is further illustrated in Figures 4A and 4B. Fig. 5A shows a top view of the mounting plate 23A. The optical through-opening 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 through-opening 43 at varying radial distances from the beam axis 5A. They are evenly distributed azimuthally, so that two lens mounting openings are opposite each other in pairs. In the perspective view of the Fig. 5BFour identical lenses 25A, 25B, 25C, 25D are inserted into the lens holder openings 53A, 53B, 53C, 53D. The lenses 25A, 25B, 25C, 25D were inserted into the lens holder openings 53A, 53B, 53C, 53D to different depths, so that, depending on the radial distance, the associated plasma detection areas 39 are arranged next to one another in the direction of the beam axis and thus form the field of view 41 of the detection unit 21, which creates the depth of field.

[0068] An alternative design is described in the Figures 6A and 6B 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-opening 43 and are evenly distributed around it. As can be seen 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 observation angles of the lenses 25A, 25B, 25C, 25D used. For example, the observation angles can be in the range of 3° to 15° at a radial distance of 30 mm, so that the field of view 41 is formed at a distance of approximately 100 mm from the mounting plate 23A. With different observation angles (and optionally viewing heights), the detected spectral distributions can vary for a large-volume plasma. However, particularly with a small-volume plasma, as is usually generated for LIBS, these differences in the spectral distribution are negligible, since essentially the entire plasma lies in a plasma detection area 39.

[0069] Fig. 7 shows once again a detailed view of the inventive system 100 according to Fig. 1It can be seen here that different material parts are provided in their composition, namely material parts 120B made of plastic and material parts 120A made of aluminum. In the manner already described, sorting can take place by means of the spectrometer system 1 according to the invention such that the material parts 120A are separated from the material parts 120B. For this purpose, if a material part 120B made of plastic is detected, this is ejected by means of the sorting unit 160. For this purpose, the sorting unit 160 has an air pressure nozzle by means of which a plastic part 120B can be ejected from the stream of material parts. As a result of such sorting, material parts 120B made of plastic on the one hand and material parts 120A made of aluminum on the other hand collect separately at the collection points 170. Reference symbol 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 Field of view 7 sample 43 optical through hole 7A surface 43A protective window 7A' dotted 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 Entrance slit 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 member plate α Observation angle 25A lens 100 system 25B lens 110 Feeding agent 25C lens 111 Feed area 25D lens 120 Material part 27 Fiber optic system 120A aluminum part 29 optical input 120B plastic part 31 optical output 130 slide 33 Measurement share 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 part, the system comprising: - a feeder (110) for transporting the piece of material (120); - a sorting unit (160) configured to feed 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 carry out a spectral analysis of the plasma light (3A) emitted from the laser-induced plasma (3) and to generate an output signal corresponding to the result of the spectral analysis that has been carried out, and - a control device (150) configured to receive the output signal and to operate the sorting unit (160) based on the output signal and on a sorting criterion, - wherein the spectrometer system (1) comprises a spectrometer (13) and a detecting unit (21) optically coupled with the spectrometer (13), - wherein the detection unit (21) has an objective (25A, 25B, 25C, 25D) to which a detection cone (35) is assigned, which detection cone creates a plasma detection region (39) in an overlapping region (37) with the laser beam (5), characterized in that the detection unit (21) comprises a further objective (25A, 25B, 25C, 25D) to which a further detection cone (35) is assigned, which detection cone forms a further plasma detection region (39) in a further overlapping region (37) with the laser beam (5), wherein the objectives (25A, 25B, 25C, 25D) are arranged in relation to one another and / or aligned in such a way that the plasma detection region (39) and the further plasma detection region (39) are offset from each other along the beam axis (5A) of the laser beam (5) and together form a field of vision of the detection unit (21).

2. System according to claim 1, characterized in that a plasma detection region (39) is configured in such a way that in the case of a plasma (3) present in the plasma detection region (39) a measuring 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) has an objective holder (23) which carries a plurality of objectives (25A, 25B, 25C, 25D) jointly.

4. System according to any one of the preceding claims, characterized in that the plasma detection regions (39) pass into each other or a spaced from each other along the beam axis (5A).

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) extends.

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

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

8. System according to any one of the preceding claims, characterized in that the spectrometer system (1) comprises a fiber optic system (27), which optically connects the detection unit (21) to the spectrometer (13).

9. System according to claim 8, characterized in that the fiber optic 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 designed for receiving the measuring share (33) detected by the associated objective (25A, 25B, 25C 25D) and wherein the optical output (31) is designed for outputting the measuring shares (33) detected by the objectives (25A, 25B, 25C, 25D).

10. System according to claim 9, characterized in that the optical fiber 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 one of the preceding claims, characterized in that the laser device (160), the spectrometer system (160), and the control device (150) are accommodated in a common housing and form a LIBS module.

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

13. System according to claim 12, characterized 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 feed 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).