Detecting gun for online detection of molten steel components based on LIBS (Laser-induced Breakdown Spectroscopy) technology

Abstract

The invention discloses an LIBS (laser-induced breakdown spectroscopy) technology-based probe gun for online detection of molten steel components, comprising: a cylindrical shell, an upper cylinder opening of which is provided with an optical fiber receiving head electrically connected with a spectrometer; the laser emitting system is used for emitting high-energy pulse laser to penetrate through a lower barrel opening of the barrel-shaped shell to excite atoms on the surface of the molten steel, and plasma is formed; the signal acquisition system is used for coupling a spectral signal emitted by the plasma to the optical fiber receiving head, and an acquisition light path is formed between the plasma and the optical fiber receiving head; and the gas protection system is used for carrying out coaxial purging on the laser action area and the signal acquisition area so as to form an inert gas protection barrier around the plasma and on the peripheral side of the acquisition light path. The probe gun adopts inert gas to protect a barrier, has multiple effects of inhibiting generation of an oxide layer, reducing local temperature, reducing steam scattering and weakening continuous background radiation, and can improve the signal acquisition capability of the probe gun.

Description

Technical Field

[0001] The present invention relates to the technical field of on-line detection of molten steel composition in a casting metallurgical process, and more particularly to a probe gun for on-line detection of molten steel composition based on LIBS technology. Background Art

[0002] During the steelmaking process, real-time and accurate detection of molten steel elements directly determines the quality of the steel, while traditional offline sampling and cooling detection is time-consuming and energy-consuming.

[0003] Laser-induced breakdown spectroscopy (LIBS) is a spectral analysis technique that uses a high-energy laser to excite a sample surface to generate plasma. The technique then analyzes the plasma's emission spectrum to determine the sample's elemental composition and concentration. Laser light is focused on the sample surface. When the laser energy exceeds a threshold, the sample is ablated to produce a high-temperature plasma. As the plasma decays, atoms or ions emit a spectrum. By measuring the wavelength and intensity of these spectra, qualitative and quantitative elemental analysis can be performed.

[0004] LIBS technology has the potential for online detection, but it still faces many bottlenecks. Most of them do not consider the effective transmission of light emitted in the wavelength range below 200nm. Conventional optical components and optical coatings generally have low transmittance and reflectivity for ultraviolet light below 200nm, which limits the LIBS technology's ability to detect elements that emit ultraviolet light, such as carbon (C), phosphorus (P), sulfur (S) and other key elements in steel. Although some technologies have proposed coupling solutions for light emitted in the wavelength range below 200nm, they all use dichroic mirror technology, which results in the disadvantages of light loss and low damage threshold. Given the above problems with existing technologies, the widespread application of LIBS technology in the steel industry is constrained. Summary of the Invention

[0005] In view of this, the present invention avoids the defects of light loss (>30%) and low damage threshold of dichroic mirrors, and proposes a probe gun for online detection of molten steel composition based on LIBS technology. The probe gun has low light loss, stable performance and high signal acquisition capability.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A probe gun for online detection of molten steel composition based on LIBS technology, comprising:

[0008] A cylindrical housing, wherein an upper opening of the cylindrical housing is provided with an optical fiber receiving head electrically connected to the spectrometer;

[0009] a laser emission system, the laser emission system being disposed on one side of the cylindrical shell and configured to emit a high-energy pulsed laser through the lower opening of the cylindrical shell to excite atoms on the surface of the molten steel to form plasma, wherein an emission light path is formed between the laser emission system and the plasma;

[0010] a signal acquisition system, the signal acquisition system being disposed within the cylindrical housing and configured to couple the spectral signal emitted by the plasma to the optical fiber receiving head, wherein a collection optical path is formed between the plasma and the optical fiber receiving head;

[0011] A gas protection system is provided on the cylindrical shell and is used for coaxially purging the laser action area and the signal collection area to form an inert gas protection barrier around the plasma and on the outer peripheral side of the collection light path.

[0012] It can be seen from the above technical solution that compared with the existing technology, the present invention discloses a probe gun for online detection of molten steel composition based on LIBS technology. In order to address the background light noise generated by the high-temperature environment of molten steel, an inert gas protection barrier is adopted, and the laser action area and the signal acquisition area are coaxially purged with a dynamically adjustable Ar gas flow rate of 0.5-2L / min. This design has the multiple functions of inhibiting the formation of oxide layer, lowering local temperature, reducing steam scattering and weakening continuous background radiation, which can improve the signal acquisition capability of the probe gun.

[0013] Furthermore, the laser emission system includes:

[0014] An installation shell is fixed to an outer wall of one side of the cylindrical shell, and a laser passage hole is opened on the outer wall of one side of the cylindrical shell;

[0015] a laser emitter, wherein the laser emitter is fixed on the mounting housing;

[0016] A focusing and beam expanding lens assembly, wherein the focusing and beam expanding lens assembly is fixed inside the mounting housing and is used for focusing and expanding the laser beam of the laser transmitter;

[0017] a first reflector, the first reflector being fixed inside the mounting housing via a right-angle optical adjustment mount and being used to guide the focused and expanded laser beam into the cylindrical housing through the laser passage hole;

[0018] a second reflecting mirror, fixed inside the cylindrical shell via a right-angle optical adjustment mount, and configured to guide the laser beam reflected by the first reflecting mirror through the lower opening of the cylindrical shell to excite atoms on the surface of the molten steel to form the plasma;

[0019] The second reflector is coaxially placed with the signal acquisition system, and minimizes the mirror size while meeting the focusing requirements of the receiving light path, thereby avoiding blocking the signal light emitted by the plasma and avoiding light loss.

[0020] Furthermore, the focusing and beam expanding lens assembly includes a first plano-concave lens, a second plano-concave lens, and two groups of biconvex lenses that are arranged sequentially and coaxially along the laser light path. The curvature radii and spacing of the first plano-concave lens, the second plano-concave lens, and the two groups of biconvex lenses are optimized and matched by optical simulation software; the first plano-concave lens, the second plano-concave lens, the two groups of biconvex lenses, between the biconvex lens and the first reflector, and between the first reflector and the second reflector are rigidly connected by connecting rods.

[0021] Furthermore, the laser emitter outputs near-infrared laser light with an output wavelength of 1064 nm.

[0022] Furthermore, the signal acquisition system is a coaxial dual-mirror assembly consisting of a concave reflector and a convex reflector arranged in sequence up and down. The dual-mirror assembly is fixed to the inside of a cylindrical housing by a retaining ring. The dual-mirror assembly uses a simulation model to optimize the mirror curvature matching relationship and spatial arrangement angle to significantly reduce optical path deflection loss. The concave reflector has an optical path hole in the middle. The spectral signal emitted by the plasma is reflected by the concave reflector and the convex reflector in sequence, and then focused through the optical path hole and coupled to the optical fiber receiving head, thereby achieving efficient transmission and precise convergence of the optical path.

[0023] The second reflector is coaxially placed with the concave reflector and the convex reflector, and the second reflector is located directly below the convex reflector.

[0024] Furthermore, the reflective film layers of the concave reflector and the convex reflector cover a wide spectral range of 190-800 nm.

[0025] Furthermore, the optical fiber core diameter of the optical fiber receiving head is expanded from 200 μm to 600 μm, and the optical fiber is a 190-1200 nm wide-spectrum UV-resistant optical fiber.

[0026] Furthermore, the cylindrical shell includes a first cylindrical body, a second cylindrical body, and a third cylindrical body which are arranged in sequence and connected to each other.

[0027] The wall of the first cylinder has an annular air inlet passage, the upper end of the annular air inlet passage is provided with an inert gas inlet valve, and the lower end of the annular air inlet passage is a first-stage annular gas nozzle for spraying inert gas into the first cylinder;

[0028] A first conical spray hood and a second conical spray hood are fixed to the inner wall of the second cylinder along the upper and lower directions thereof. The large opening end of the first conical spray hood is connected to the lower cylinder opening of the first cylinder. The small opening end of the first conical spray hood is a second-stage annular gas nozzle for spraying inert gas into the large opening end of the second conical spray hood. The small opening end of the second conical spray hood is a third-stage annular gas nozzle for spraying inert gas into the third cylinder. An outlet channel connected to the third cylinder is provided between the second conical spray hood and the inner wall of the second cylinder. An inert gas outlet valve is provided on the outlet channel.

[0029] The spectral signal emitted by the plasma passes through the third-stage annular gas nozzle, the second-stage annular gas nozzle, and the first-stage annular gas nozzle in sequence and is transmitted to the concave reflector. The first-stage annular gas nozzle, the second-stage annular gas nozzle, and the third-stage annular gas nozzle constitute the gas protection system to construct the laminar inert gas protection barrier around the plasma and on the outer peripheral side of the collection light path.

[0030] Furthermore, sealing gaskets are provided between the first cylinder and the second cylinder, and between the second cylinder and the third cylinder.

[0031] Furthermore, the third cylinder is made of high-temperature resistant ceramics. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0033] Figure 1 This is a structural schematic diagram of a probe gun for online detection of molten steel composition based on LIBS technology provided by the present invention.

[0034] Figure 2 Schematic diagram of the laser emission system.

[0035] Figure 3 Simulated image of a focusing and beam expander lens assembly.

[0036] Figure 4 Schematic diagram of the optical path of the signal acquisition system.

[0037] Figure 5 Simulate an image for the signal acquisition system. DETAILED DESCRIPTION

[0038] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention.

[0039] In the description of the present invention, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the present invention.

[0040] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0041] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0042] The present invention ensures the precision of optical components through optical simulation based on LIBS technology, and designs a coaxial integrated immersion molten steel probe gun, which can be used for real-time, non-contact online detection of molten steel composition.

[0043] Specifically, the embodiment of the present invention discloses a probe gun for online detection of molten steel composition based on LIBS technology, comprising:

[0044] A cylindrical shell 1, the upper end of which is provided with an optical fiber receiving head 2 electrically connected to the spectrometer;

[0045] A laser emission system 3 is arranged on one side of the cylindrical shell 1, and is configured to emit high-energy pulsed laser to excite atoms on the surface of the molten steel to form the plasma 4 through the lower opening of the cylindrical shell 1, wherein a compact emission light path 100 with a total length of 1000mm is formed between the laser emission system 3 and the plasma 4.

[0046] A signal acquisition system 5 is arranged in the cylindrical shell 1, and is configured to couple the spectral signal emitted by the plasma 4 to the optical fiber receiving head 2, wherein an acquisition light path 200 is formed between the plasma 4 and the optical fiber receiving head 2.

[0047] A gas protection system is arranged on the cylindrical shell 1, and is configured to coaxially blow the laser action area and the signal acquisition area to form an inert gas protection barrier 300 around the plasma 4 and outside the acquisition light path 200.

[0048] The laser emission system 3 comprises:

[0049] A mounting shell 31 is fixed on the outer wall of one side of the cylindrical shell 1, and a laser passing hole is formed on the outer wall of one side of the cylindrical shell 1;

[0050] A laser emitter 32 is fixed on the mounting shell 31;

[0051] A focusing and expanding lens assembly 33 is fixed inside the mounting shell 31, and is configured to focus and expand the laser beam emitted by the laser emitter 32;

[0052] A first mirror 34 is fixed inside the mounting shell 31 through a right-angle optical adjusting frame 18, and is configured to guide the focused and expanded laser beam to enter the cylindrical shell 1 through the laser passing hole;

[0053] A second mirror 35 is fixed inside the cylindrical shell 1 through the right-angle optical adjusting frame 18, and is configured to guide the laser beam reflected by the first mirror 34 to excite atoms on the surface of the molten steel to form the plasma 4 through the lower opening of the cylindrical shell 1;

[0054] The second mirror 35 is coaxially arranged with the signal acquisition system 5, and the size of the mirror is minimized to meet the focusing requirement of the receiving light path, so as to avoid blocking the signal light emitted by the plasma 4 and avoid light loss.

[0055] The focusing and beam expanding lens assembly 33 includes a first plano-concave lens 331 with a diameter of 25 mm, a second plano-concave lens 332, and two groups of biconvex lenses 333, which are sequentially and coaxially arranged along the laser optical path. The curvature radii and spacing of the first plano-concave lens 331, the second plano-concave lens 332 with a diameter of 10 mm, and the two groups of biconvex lenses 333 with a diameter of 25 mm are optimized and matched using optical simulation software (i.e., the first plano-concave lens 331 has a curvature radius of 38.6 mm; the second plano-concave lens 332 has a curvature radius of 25.7 mm; and the two biconvex lenses 333 have a curvature radius of 179.8 mm and a curvature radius of 205.6 mm, respectively). The distance between the first plano-concave lens 331 and the second plano-concave lens 332 is 1.794 mm, the distance between the second plano-concave lens 332 and the front biconvex lens 333 is 66.361 mm, and the distance between the front and rear biconvex lenses 333 is 12.390 mm); the first plano-concave lens 331, the second plano-concave lens 332, the two groups of biconvex lenses 333, the biconvex lens 333 and the first reflector 34, and the first reflector 34 and the second reflector 35 are all rigidly connected by a connecting rod 19, which can ensure the precise positioning of each optical element, so that the optical path offset is less than 5 μm, ensuring the coaxiality and stability of the optical elements.

[0056] The laser emitter 32 is equipped with a laser generator module with a single-pulse energy of 1-3 mJ and a repetition rate of 10-40 kHz. It preferably outputs near-infrared laser light with a wavelength of 1064 nm, which has the physical properties of penetrating the oxide layer on the surface of molten steel. By precisely controlling the laser focus to a depth of 0.5-1 mm below the liquid surface, it achieves a stable output with an effective spot diameter of 3-5 mm.

[0057] The above design can form a characteristic light spot with Gaussian energy distribution on the surface of molten steel. Numerical simulations have verified that the energy density in the focal plane reaches the molten pool excitation threshold, which can effectively solve the problem of low laser coupling efficiency on the surface of high-temperature liquid metal.

[0058] The signal collection system 5 is a coaxial double mirror group composed of a concave mirror 51 and a convex mirror 52 arranged in sequence from top to bottom, which is fixed in the cylindrical shell 1 by a snap ring 20, and the double mirror group adopts a simulation model to optimize the mirror curvature matching relationship and the spatial arrangement angle (i.e. the curvature radius of the concave mirror 51 is 677.12 mm, the curvature radius of the convex mirror 52 is 897.76 mm, and the matching distance between the two is 87.259 mm), so as to significantly reduce the light path deflection loss, so that the plasma radiation signal is converged to the optical fiber receiving head 2 with a transmission efficiency of >90%. The middle part of the mirror 51 (Φ150mm) has a light path hole 511 (aperture 40mm), and the spectrum signal emitted by the plasma 4 is reflected by the concave mirror 51 and the convex mirror 52 (Φ86mm) in turn, and then focused and coupled to the optical fiber receiving head 2 through the light path hole 511, realizing efficient transmission and precise convergence of the light path. The design of the light path hole 511 maximizes the utilization rate of the reflecting surface while ensuring unobstructed transmission of the light path.

[0059] The second mirror 35 is coaxially arranged with the concave mirror 51 and the convex mirror 52, and the second mirror 35 is located directly below the convex mirror 52.

[0060] The reflective film layer of the concave mirror 51 and the convex mirror 52 covers a wide spectrum range of 190-800nm, effectively improving the spectral response capability of the system.

[0061] The fiber core diameter of the optical fiber receiving head 2 is expanded from 200μm to 600μm, the receiving end light flux is improved by 9 times, and the collection efficiency of the plasma radiation light is significantly improved. According to the characteristics that the characteristic spectral lines of trace elements C, S and P (<220nm) affecting the quality of molten steel are concentrated in the deep ultraviolet region, a 190-1200nm wide spectrum ultraviolet resistant optical fiber is selected to reduce the optical fiber loss. Through large core diameter energy capture and ultraviolet resistant wide spectrum transmission, the signal-to-noise ratio of the spectral signal is greatly reduced, and the working stability of the whole system is improved.

[0062] The cylindrical shell 1 includes a first cylinder 11, a second cylinder 12 and a third cylinder 13 arranged in sequence and connected;

[0063] The cylinder wall of the first cylinder 11 has an annular gas inlet passage 111, the upper end of the annular gas inlet passage 111 is provided with an inert gas inlet valve 6, and the lower end of the annular gas inlet passage 111 is a first-stage annular gas nozzle 7 for spraying inert gas into the first cylinder 11;

[0064] A first conical spray hood 8 and a second conical spray hood 9 are fixed to the inner wall of the second cylinder 12 along the upper and lower directions thereof. The large opening end of the first conical spray hood 8 is connected to the lower cylinder opening of the first cylinder 11. The small opening end of the first conical spray hood 8 is a second-stage annular gas nozzle 10 for spraying inert gas into the large opening end of the second conical spray hood 9. The small opening end of the second conical spray hood 9 is a third-stage annular gas nozzle 14 for spraying inert gas into the third cylinder 13. An outlet channel 15 connected to the third cylinder 13 is provided between the second conical spray hood 9 and the inner wall of the second cylinder 12. The outlet channel 15 is provided with an inert gas outlet valve 16.

[0065] The spectral signal emitted by the plasma 4 passes through the third-stage annular gas nozzle 14, the second-stage annular gas nozzle 10, and the first-stage annular gas nozzle 7 in sequence and is then transmitted to the concave reflector 51. The first-stage annular gas nozzle 7, the second-stage annular gas nozzle 10, and the third-stage annular gas nozzle 14 form a gas protection system to construct a laminar inert gas protection barrier 300 around the plasma 4 and on the outer periphery of the collection optical path 200. This design has the multiple functions of inhibiting the formation of an oxide layer, lowering local temperature, reducing vapor scattering, and weakening continuous background radiation. If the probe is immersed in the molten steel at a 45° angle, so that the vapor scattering direction forms a spatial orthogonal intersection with the spectrum collection optical path, maintaining the stability of the plasma morphology, the characteristic peak recognition rate will be increased by 20%. Through this optical path structure design and gas barrier, the signal-to-noise ratio of the characteristic spectral signal will be significantly improved.

[0066] Sealing gaskets 17 are provided between the first cylinder 11 and the second cylinder 12 , and between the second cylinder 12 and the third cylinder 13 to ensure sealing.

[0067] The third cylinder 13 is made of high-temperature resistant ceramics, which prolongs the service life and avoids high-temperature ablation.

[0068] The workflow of the present invention is as follows:

[0069] Laser pulses are emitted from a fundamental frequency laser transmitter and passed through a plano-concave lens (first, second, biconvex, and second) to focus the emission angle. A reflector assembly (first, second, and third) then deflects and focuses the pulses 10-15 mm below the molten steel surface, stimulating the plasma. The signal light is focused by a concave reflector onto a convex reflector. After secondary focusing, the light passes through the optical path aperture of the concave reflector and is captured by a UV-resistant optical fiber for transmission to the spectrometer.

[0070] Gas protection system: Before the probe gun is immersed in the molten steel, Ar gas is blown directly out of the high-temperature resistant ceramic tube from the inlet valve to pre-exhaust the air; after being immersed in the molten steel, the outlet valve is opened to construct a coaxial laminar flow barrier to cool the optical window, stabilize the plasma morphology, and suppress vapor scattering.

[0071] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0072] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A probe gun for online detection of molten steel composition based on LIBS technology, characterized in that: include: A cylindrical housing (1), wherein an upper opening of the cylindrical housing (1) is provided with an optical fiber receiving head (2) electrically connected to the spectrometer; A laser emitting system (3), the laser emitting system (3) being arranged on one side of the cylindrical shell (1) and configured to emit high-energy pulsed laser light through the lower opening of the cylindrical shell (1) to excite atoms on the surface of the molten steel to form plasma (4), wherein an emission light path (100) is formed between the laser emitting system (3) and the plasma (4); a signal acquisition system (5), the signal acquisition system (5) being arranged in the cylindrical housing (1) and being used for coupling the spectral signal emitted by the plasma (4) to the optical fiber receiving head (2), wherein a collection optical path (200) is formed between the plasma (4) and the optical fiber receiving head (2); A gas protection system is provided on the cylindrical housing (1) and is used for coaxially purging the laser action area and the signal collection area to form an inert gas protection barrier (300) around the plasma (4) and on the outer peripheral side of the collection optical path (200).

2. The probe gun for online detection of molten steel composition based on LIBS technology according to claim 1, characterized in that: The laser emission system (3) comprises: An installation shell (31), wherein the installation shell (31) is fixed on one side outer wall of the cylindrical shell (1), and a laser passage hole is provided on one side outer wall of the cylindrical shell (1); a laser emitter (32), wherein the laser emitter (32) is fixed on the mounting housing (31); a focusing and beam-expanding lens assembly (33), the focusing and beam-expanding lens assembly (33) being fixed inside the mounting housing (31) and being used for focusing and beam-expanding the laser beam of the laser emitter (32); a first reflecting mirror (34), the first reflecting mirror (34) being fixed inside the mounting housing (31) via a right-angle optical adjustment frame (18), and being used for guiding the focused and expanded laser beam to enter the cylindrical housing (1) through the laser passage hole; a second reflecting mirror (35), the second reflecting mirror (35) being fixed inside the cylindrical shell (1) via a right-angle optical adjustment frame (18), and being used for guiding the laser beam reflected by the first reflecting mirror (34) through the lower barrel opening of the cylindrical shell (1) to excite atoms on the surface of the molten steel to form the plasma (4); The second reflector (35) is coaxially placed with the signal acquisition system (5), and minimizes the mirror size while meeting the focusing requirements of the receiving light path, thereby avoiding blocking the signal light emitted by the plasma (4) and avoiding light loss.

3. The probe gun for online detection of molten steel composition based on LIBS technology according to claim 2, characterized in that: The focusing and beam expanding lens assembly (33) comprises a first plano-concave lens (331), a second plano-concave lens (332), and two groups of biconvex lenses (333) which are sequentially and coaxially arranged along the laser light path. The curvature radii and spacings of the first plano-concave lens (331), the second plano-concave lens (332), and the two groups of biconvex lenses (333) are optimized and matched by optical simulation software. The first plano-concave lens (331), the second plano-concave lens (332), the two groups of biconvex lenses (333), the biconvex lens (333) and the first reflector (34), and the first reflector (34) and the second reflector (35) are rigidly connected via a connecting rod (19).

4. The probe gun for online detection of molten steel composition based on LIBS technology according to claim 2, characterized in that: The laser emitter (32) outputs near-infrared laser light with a wavelength of 1064 nm.

5. The probe gun for online detection of molten steel composition based on LIBS technology according to claim 2, characterized in that: The signal acquisition system (5) is a coaxial double-reflector group consisting of a concave reflector (51) and a convex reflector (52) arranged in sequence up and down. The double-reflector group is fixed inside the cylindrical shell (1) via a retaining ring (20). The double-reflector group uses a simulation model to optimize the curvature matching relationship and spatial arrangement angle of the reflectors to significantly reduce the optical path deflection loss. The concave reflector (51) has an optical path hole (511) in the middle. The spectral signal emitted by the plasma (4) is sequentially reflected by the concave reflector (51) and the convex reflector (52), and then focused through the optical path hole (511) and coupled to the optical fiber receiving head (2), thereby achieving efficient transmission and precise convergence of the optical path. The second reflector (35) is coaxially placed with the concave reflector (51) and the convex reflector (52), and the second reflector (35) is located directly below the convex reflector (52).

6. The probe gun for online detection of molten steel composition based on LIBS technology according to claim 5, characterized in that: The reflective film layers of the concave reflector (51) and the convex reflector (52) cover a wide spectral range of 190-800 nm.

7. A probe gun for online detection of molten steel composition based on LIBS technology according to any one of claims 1 to 6, characterized in that: The optical fiber core diameter of the optical fiber receiving head (2) is enlarged from 200 μm to 600 μm, and the optical fiber is a 190-1200 nm wide-spectrum anti-ultraviolet optical fiber.

8. The probe gun for online detection of molten steel composition based on LIBS technology according to any one of claims 1 to 6, characterized in that: The cylindrical shell (1) comprises a first cylindrical body (11), a second cylindrical body (12), and a third cylindrical body (13) which are arranged in sequence and communicated with each other. The wall of the first cylinder (11) has an annular air inlet channel (111), an inert gas inlet valve (6) is provided at the upper end of the annular air inlet channel (111), and a first-stage annular gas nozzle (7) for spraying inert gas into the first cylinder (11) is provided at the lower end of the annular air inlet channel (111); A first conical spray hood (8) and a second conical spray hood (9) are fixed on the inner wall of the second cylinder (12) along the upper and lower directions thereof; the large opening end of the first conical spray hood (8) is communicated with the lower opening of the first cylinder (11); the small opening end of the first conical spray hood (8) is a second-stage annular gas nozzle (10) for spraying inert gas into the large opening end of the second conical spray hood (9); the small opening end of the second conical spray hood (9) is a third-stage annular gas nozzle (14) for spraying inert gas into the third cylinder (13); an outlet passage (15) communicating with the third cylinder (13) is provided between the second conical spray hood (9) and the inner wall of the second cylinder (12); and an inert gas outlet valve (16) is provided on the outlet passage (15); The spectral signal emitted by the plasma (4) passes through the third-stage annular gas nozzle (14), the second-stage annular gas nozzle (10), and the first-stage annular gas nozzle (7) in sequence and is transmitted to the concave reflector (51), and the first-stage annular gas nozzle (7), the second-stage annular gas nozzle (10), and the third-stage annular gas nozzle (14) construct the gas protection system to construct the laminar inert gas protection barrier (300) around the plasma (4) and on the outer peripheral side of the collection light path (200).

9. The probe gun for online detection of molten steel composition based on LIBS technology according to claim 8, characterized in that: Sealing gaskets (17) are provided between the first cylinder (11) and the second cylinder (12), and between the second cylinder (12) and the third cylinder (13).

10. The probe gun for online detection of molten steel composition based on LIBS technology according to claim 8, characterized in that: The third cylinder (13) is made of high-temperature resistant ceramics.

Images