Optical fiber probe and optical fiber LIBS remote detection system and method

Abstract

The invention discloses an optical fiber probe and an optical fiber LIBS remote detection system and method, and relates to the technical field of laser detection, the optical fiber probe comprises a shell, and a collimating mirror, a focusing mirror and a quadric surface reflection cavity which are sequentially arranged in the shell along the laser incidence direction; the quadric surface reflection cavity comprises an upper end face and a lower end face, the lower end face is in contact with a sample, and the upper end face is in contact with the focus lens; the center of the lower end face is the focus of the focus lens, and the focus of the focus lens coincides with the first focus of the quadric surface reflection cavity. In the spectrum excitation stage, after being incident, laser is collimated by a collimating mirror and focused on the surface of a sample by a focusing mirror, plasma is excited and generated, and a quadric surface reflection cavity generates spatial constraint on the plasma; in the spectrum collection stage, radiation light generated by the plasma is directly converged and collected by the focus lens or reflected to the focus lens through the quadric surface reflection cavity to be converged and collected. According to the invention, the sensitivity of optical fiber LIBS detection is improved, and automatic focusing is realized.

Description

Technical Field

[0001] The present application relates to the field of laser detection technology, and in particular to a fiber optic probe, a fiber optic LIBS remote detection system and a method. Background Art

[0002] Laser-induced breakdown spectroscopy (LIBS) is an atomic emission spectroscopy analysis method that focuses high-energy pulsed laser directly on a sample, ablates the sample to generate plasma, and detects its emission characteristic spectral lines. LIBS technology has the characteristics of non-contact, no sample pretreatment, spatial resolution and element "fingerprint" characteristics, and has attracted widespread attention in the fields of chemical industry, metallurgy, exploration, archaeology, etc.

[0003] Fiber-optic LIBS technology is an improvement and innovation on traditional LIBS technology. This technology is suitable for extreme environments such as high temperature, high pressure, high humidity, and high radiation. It can be used in places that are difficult for conventional instruments to reach, such as pipelines and narrow alleys. It has been used in nuclear power plants, thermal power plants, spent fuel processing plants and other places.

[0004] However, the fiber-optic LIBS technology still has the following shortcomings: the energy density of the pulsed laser emitted by the optical fiber is much lower than that of the traditional LIBS technology, resulting in a lower intensity of the emission spectrum of the excited plasma. Therefore, the sensitivity of element detection is limited, making it difficult to detect trace elements. Summary of the invention

[0005] The main purpose of this application is to provide a fiber optic probe, a fiber optic LIBS remote detection system and method, which aims to solve the technical problem of limited detection sensitivity due to low pulse laser energy density and can achieve automatic focusing.

[0006] To achieve the above objectives, the present application proposes a fiber optic probe, comprising: A housing, and a collimating mirror, a focusing mirror and a quadratic curved surface reflection cavity sequentially arranged in the housing along the incident direction of the laser; The quadratic curved surface reflection cavity comprises an upper end surface and a lower end surface, the lower end surface is in contact with the sample, and the upper end surface is in contact with the focusing mirror; The center of the lower end surface is the focus of the focusing mirror, and the focus of the focusing mirror coincides with the first focus of the quadratic curved surface reflection cavity; In the spectral excitation stage, the laser is collimated by the collimator after being incident, and is focused on the sample surface by the focusing mirror to excite and generate plasma, and the quadratic curved surface reflection cavity generates spatial constraints on the plasma; In the spectrum collection stage, the radiation light generated by the plasma is directly collected by the focusing mirror, or is reflected by the quadratic surface reflection cavity to the focusing mirror for collection.

[0007] In some embodiments, the quadratic curved surface reflection cavity is parabolic, and the surface parameters of the quadratic curved surface reflection cavity are determined according to the working aperture and focal length of the focusing mirror.

[0008] In some embodiments, the cavity wall of the quadratic curved reflective cavity is enclosed by the tail portion of the shell, and the tail portion is formed in an integrated form.

[0009] In some embodiments, the quadratic curved surface reflection cavity is ellipsoidal, and the surface parameters of the quadratic curved surface reflection cavity are determined according to the working aperture and focal length of the focusing mirror. The quadratic curved surface reflection cavity includes a first focus and a second focus, and the second focus coincides with the center of the working aperture.

[0010] In some embodiments, the cavity wall of the quadratic curved reflective cavity is enclosed by the tail portion of the shell, and the tail portion includes a first shell and a second shell.

[0011] In some embodiments, the quadratic curved surface reflection cavity is a double parabola type, and the surface parameters of the quadratic curved surface reflection cavity are determined according to the working aperture and focal length of the focusing mirror. The quadratic curved surface reflection cavity includes a first focus and a second focus, and the second focus coincides with the center of the working aperture.

[0012] In some embodiments, the cavity wall of the quadratic curved reflective cavity is enclosed by the tail portion of the shell, and the tail portion includes a first shell and a second shell, and the cavity walls of the first shell and the second shell are symmetrical in shape.

[0013] In addition, to achieve the above-mentioned purpose, the present application also proposes a fiber LIBS remote detection system, comprising the fiber optic probe as described above, and also comprising a main control module, and a fiber optic pulse laser, a spectrometer and a timing control generator respectively connected to the main control module for communication; The timing control generator is also communicatively connected to the fiber pulse laser and the spectrometer respectively; The fiber pulse laser and the spectrometer are connected to the fiber probe via a two-core Y-type optical fiber.

[0014] In addition, to achieve the above-mentioned purpose, the present application also proposes a fiber LIBS remote detection method, which is applied to the fiber LIBS remote detection system as described above, comprising: Setting the laser generation parameters of the fiber pulse laser and the spectrum acquisition parameters of the spectrometer; The main control module sends a detection instruction to the timing control generator, and the timing control generator controls the fiber pulse laser to emit laser according to the detection instruction. The laser enters the fiber probe through the two-core Y-type optical fiber, converges on the sample surface, and excites and generates plasma; The radiation light of the plasma is enhanced by the optical fiber probe and detected by the spectrometer through the two-core Y-type optical fiber.

[0015] In some embodiments, the main control module sends a detection instruction to the timing control generator, and the timing control generator controls the fiber pulse laser to emit laser according to the detection instruction, and the laser enters the fiber probe through the two-core Y-type optical fiber and converges on the sample surface. After the step of exciting and generating plasma, the step further includes: Obtaining the change in LIBS spectrum intensity of the plasma over time, and determining spectrum collection adjustment parameters; The spectrum acquisition parameters are adjusted according to the spectrum collection adjustment parameters to optimize spectrum collection of the spectrometer under time constraints.

[0016] In addition, to achieve the above-mentioned purpose, the present application also proposes an electronic device, which includes: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the computer program is configured to implement the steps of the optical fiber LIBS remote detection method as described above.

[0017] In addition, to achieve the above-mentioned purpose, the present application also proposes a storage medium, which is a computer-readable storage medium, and a computer program is stored on the storage medium. When the computer program is executed by the processor, the steps of the optical fiber LIBS remote detection method as described above are implemented.

[0018] In addition, to achieve the above-mentioned purpose, the present application also provides a computer program product, which includes a computer program, and when the computer program is executed by a processor, it implements the steps of the optical fiber LIBS remote detection method as described above.

[0019] The optical fiber probe proposed in the present application comprises a shell, and a collimator, a focusing mirror and a quadratic surface reflection cavity which are sequentially arranged in the shell along the laser incident direction; the quadratic surface reflection cavity comprises an upper end face and a lower end face, the lower end face is in contact with a sample, and the upper end face is in contact with the focusing mirror; the center of the lower end face is the focus of the focusing mirror, and the focus of the focusing mirror coincides with the first focus of the quadratic surface reflection cavity; in the spectrum excitation stage, the laser is collimated by the collimator after being incident, and is focused on the sample surface by the focusing mirror to excite and generate plasma, and the quadratic surface reflection cavity generates spatial constraints on the plasma; in the spectrum collection stage, the radiation light generated by the plasma is directly converged and collected by the focusing mirror, or is reflected to the focusing mirror through the quadratic surface reflection cavity for convergence and collection. The technical solution of the embodiment of the present application, on the one hand, generates spatial constraints on the plasma through the quadratic surface reflection cavity in the spectral excitation stage, so that the sound waves generated by the plasma evolution process are reflected by the inner wall of the cavity, compressing the formed plasma, increasing the plasma electron density and temperature, improving the plasma radiation process, and thus improving the LIBS spectrum intensity. On the other hand, in the spectrum collection stage, the quadratic surface reflection cavity is used to reflect the plasma radiation light outside the focusing mirror convergence angle into the focusing mirror for collection and detection, expanding the spectrum collection angle, greatly improving the spectrum collection efficiency, and thus improving the sensitivity of LIBS detection. At the same time, since the center of the lower end face of the optical fiber probe is the focus of the focusing mirror, that is, the lower end face is the focal plane of the focusing mirror, there is no need for a complex automatic focusing process, and the probe can directly contact the sample surface to carry out LIBS measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings herein are incorporated into the specification and constitute a part of the specification, showing embodiments consistent with the present application, and together with the specification, are used to explain the principles of the present application. In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the prior art description will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 A schematic cross-sectional view of an optical fiber probe provided in an embodiment of the present application; Figure 2 A scene comparison diagram of the technology related to the spectral excitation stage and the embodiment of the present application; Figure 3 A scene comparison diagram of the technology related to the spectrum collection stage and the embodiment of the present application; Figure 4 A cross-sectional view of the parabolic optical fiber probe provided in an embodiment of the present application taken along the AA direction; Figure 5A schematic diagram of the simplified structure of a parabolic quadratic reflective cavity provided in an embodiment of the present application; Figure 6 A cross-sectional view of the BB direction of the ellipsoidal optical fiber probe provided in an embodiment of the present application; Figure 7 A schematic diagram of the simplified structure of the ellipsoidal quadratic reflective cavity provided in the embodiment of the present application; Figure 8 The CC direction cross-sectional view of the double parabolic optical fiber probe provided in the embodiment of the present application Fig. 9 A schematic diagram of the structure of a double-parabolic quadratic reflective cavity provided in an embodiment of the present application; Fig.10 This is a main concept diagram of a fiber LIBS remote detection system according to an embodiment of the present application; Fig.11 This is a host structure diagram of a fiber LIBS remote detection system according to an embodiment of the present application; Fig.12 This is an experimental scene diagram of an optical fiber LIBS remote detection system according to an embodiment of the present application; Fig.13 This is a flow chart of an embodiment of the optical fiber LIBS remote detection method of the present application; Fig.14 A schematic diagram of the time evolution of the Cu plasma emission spectrum under spatial confinement provided in an embodiment of the present application; Fig.15 Schematic diagram of the equipment structure of the hardware operating environment involved in the optical fiber LIBS remote detection method in the embodiment of the present application.

[0022] Description of Figure Numbers: S1, upper end surface; S2, lower end surface; H1, first focus; H2, second focus; P, plasma; 100, optical fiber probe; 110, housing; 120, collimating lens; 130, focusing lens; 140, quadratic curved surface reflection cavity; 200. Sample; 300. Main control module; 400. Fiber pulse laser; 500. Spectrometer; 600. Timing control generator; 700. Two-core Y-type optical fiber; 800. Main unit housing.

[0023] The purpose, features and advantages of this application will be further described in conjunction with the embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0024] It should be understood that the specific embodiments described herein are only used to explain the technical solution of the present application and are not used to limit the present application. In order to better understand the technical solution of the present application, the following will be described in detail in conjunction with the accompanying drawings and specific implementation methods.

[0025] The present application embodiment provides a fiber optic probe, Figure 1 This is a cross-sectional schematic diagram of an optical fiber probe according to an embodiment of the present application, such as Figure 1 As shown, the optical fiber probe 100 includes: a housing 110, and a collimating mirror 120, a focusing mirror 130 and a quadratic surface reflection cavity 140 which are sequentially arranged in the housing 110 along the laser incident direction; the quadratic surface reflection cavity 140 includes an upper end surface S1 and a lower end surface S2, the lower end surface S2 is in contact with the sample 200, and the upper end surface S1 is in contact with the focusing mirror 130; the center of the lower end surface S2 is the focus of the focusing mirror 130, and the focus of the focusing mirror 130 coincides with the first focus H1 of the quadratic surface reflection cavity 140; in the spectrum excitation stage, the laser is collimated by the collimating mirror 120 after being incident, and is focused on the surface of the sample 200 by the focusing mirror 130, so as to excite and generate plasma P, and the quadratic surface reflection cavity 140 generates spatial constraints on the plasma P; in the spectrum collection stage, the radiation light generated by the plasma P is directly converged and collected by the focusing mirror 130, or is reflected to the focusing mirror 130 through the quadratic surface reflection cavity 140 for convergence and collection.

[0026] A quadratic surface refers to a surface represented by a ternary quadratic equation. The quadratic surface reflection cavity 140 in the embodiment of the present application has an upper end surface S1 in contact with the focusing mirror 130, and a lower end surface S2 in contact with the sample 200. The laser is focused on the surface of the sample 200 through the focusing mirror 130. Since the center of the lower end surface S2 is set as the focus of the focusing mirror 130, the focal plane of the focusing mirror 130 is the surface of the sample 200, and can be automatically focused. The focused laser excites the surface of the sample 200 to generate plasma P.

[0027] Figure 2 The following is a scene comparison diagram of the related technology and the embodiment of the present application at the spectral excitation stage, wherein (a) is the spectral excitation stage of the related technology, and (b) is the spectral excitation stage of the embodiment of the present application. Figure 2 It can be seen that the fiber optic probe 100 of the present application is provided with a quadratic curved reflection cavity 140 at the end for spatial constraint. The sound waves generated during the evolution of the plasma P are reflected by the inner wall of the cavity, compressing the formed plasma P, increasing the electron density and temperature of the plasma P, improving the radiation process of the plasma P, and thus increasing the LIBS spectrum intensity. The LIBS method in the related art excites the surface of the sample 200 through the focusing mirror 130, and does not perform any constraint processing after the plasma P is generated, so the spectrum intensity is relatively weak.

[0028] Figure 3The following is a scene comparison diagram of the related technology and the embodiment of the present application at the spectrum collection stage, wherein (a) is the spectrum collection stage of the related technology, and (b) is the spectrum collection stage of the embodiment of the present application. Figure 3 It can be seen that the spectral collection method of the related art is limited by the convergence angle of the focusing mirror 130, and the spectral collection efficiency is low; while the embodiment of the present application adopts a quadratic curved surface reflection cavity 140 to reflect the plasma P radiation light outside the convergence angle of the focusing mirror 130 into the focusing mirror 130 for collection and detection, which expands the spectral collection angle, greatly improves the spectral collection efficiency, and thus improves the detection sensitivity.

[0029] Exemplarily, the quadratic reflection cavity 140 is an aspherical reflection cavity having at least one focus, which is the first focus H1, and the first focus H1 coincides with the focus position of the focusing mirror 130. According to the characteristics of the quadratic surface, most of the radiation light of the plasma P can be reflected to the focusing mirror 130 and collected.

[0030] In a feasible implementation manner, the quadratic curved surface reflection cavity 140 is a parabola, and the surface parameters of the quadratic curved surface reflection cavity 140 are determined according to the working aperture and focal length of the focusing mirror 130 .

[0031] Figure 4 The AA direction cross-sectional view of the parabolic optical fiber probe 100 provided in the embodiment of the present application is shown in FIG. Figure 4 As shown, the lower end surface S2 can be regarded as a cross section of the parabola, which passes through the first focus H1 of the parabola and coincides with the focal plane of the focusing mirror 130. The position of the plasma P basically coincides with the position of the first focus H1. The radiation light emitted from the first focus H1 is reflected from any point of the parabola-shaped quadratic reflection cavity 140 as parallel light and is collected by the focusing mirror 130.

[0032] In this embodiment, the surface parameters of the quadratic reflective cavity 140 refer to the parameters that determine the size of its parabola, for example, the coordinate values ​​of the points on the parabola. It can be understood that the parabola can be regarded as a parabola rotated around the axis of its focus and vertex. On the basis of determining that the first focus H1 of the quadratic reflective cavity 140 coincides with the focus of the focusing mirror 130, the positions of the two points on the same side of the parabola are calculated according to the working aperture and focal length of the focusing mirror 130, and the shape of the parabola can be obtained.

[0033] Figure 5 A schematic diagram of the simplified structure of the parabolic quadratic reflective cavity 140 provided in the embodiment of the present application is shown in FIG. Figure 5 As shown, in the cross section of the parabolic quadratic reflective cavity 140, AB on the parabola is the working aperture of the focusing mirror 130, CD is the lower end surface S2, which is also the focal plane of the focusing mirror 130, and H1 is the focus of the focusing mirror 130, which is also the first focus. The equation of the parabola can be expressed as , Figure 5 for z=0 The equation of the parabola can be expressed as x 2 =2py , the coordinates of its focus H1 can be expressed as ( 0, p / 2 ).

[0034] Therefore, when the working aperture of the focusing lens 130 is known to be l , the focal length is f When the CD of the lower end surface of the reflection cavity is m , then the coordinates of point C are ( m / 2, p / 2 ), the coordinates of point B are , substituting the coordinates into the parabola equation, we can get the following formula 1.

[0035] Formula 1: .

[0036] According to formula 1, the following formula 2 can be obtained.

[0037] Formula 2: .

[0038] Therefore, the surface shape of the quadratic curved reflective cavity 140 can be determined by the known working aperture and focal length of the focusing mirror 130 .

[0039] Optionally, the cavity wall of the quadratic curved surface reflection cavity 140 is enclosed by the tail of the housing 110, and the tail is formed in an integrated form. Figure 4 The quadratic curved surface reflection cavity 140 is hollow and is composed of a cavity wall and a housing 110. The housing 110 as a whole may include different parts, and different parts are installed at different positions of the housing 110. The quadratic curved surface reflection cavity 140 is located at the tail, forming an integrated structure. The integrated structure is not easy to leak laser.

[0040] In a feasible implementation, the quadratic curved surface reflection cavity 140 is ellipsoidal, and the surface parameters of the quadratic curved surface reflection cavity 140 are determined according to the working aperture and focal length of the focusing mirror 130. The quadratic curved surface reflection cavity 140 includes a first focus H1 and a second focus H2, and the second focus H2 coincides with the center of the working aperture.

[0041] Figure 6 The BB direction cross-sectional view of the ellipsoidal optical fiber probe 100 provided in the embodiment of the present application is as follows: Figure 6As shown, the upper end surface S1 and the lower end surface S2 can be regarded as the cross section of the ellipsoidal surface, and the ellipsoidal surface includes a first focus H1 and a second focus H2. When the focus of the focusing mirror 130 coincides with the first focus H1, and the aperture center of the focusing mirror 130 coincides with the second focus H2, it can be ensured that the light emitted from the focus of the focusing mirror 130 will pass through the aperture center of the focusing mirror 130 after being reflected by the ellipsoidal cavity, thereby expanding the spectrum collection angle and improving the spectrum collection efficiency.

[0042] In this embodiment, the surface parameters of the quadratic reflective cavity 140 refer to the parameters that determine the size of its ellipsoidal surface, for example, the coordinate values ​​of the points on the ellipsoidal surface. It can be understood that the ellipsoidal surface can be regarded as being obtained by rotating the ellipse around the axis of its two foci. On the basis of determining the relationship between the first focus H1 and the second focus H2 of the quadratic reflective cavity 140 and the ellipsoidal surface, the position of the point on the ellipse can be calculated according to the working aperture and focal length of the focusing lens 130 to obtain the shape of the ellipsoidal surface.

[0043] Figure 7 A schematic diagram of the structure of the ellipsoidal quadratic surface reflection cavity 140 provided in the embodiment of the present application is shown in FIG. Figure 7 As shown, in the cross section of the ellipsoidal quadratic reflective cavity 140, AB on the ellipse is the working aperture of the focusing mirror 130; CD is the lower end surface S2, which is also the focal plane of the focusing mirror 130; H1 is the focus of the focusing mirror 130 and also the focus of the ellipse; H2 is the center of the working aperture of the focusing mirror 130 and also another focus of the ellipse.

[0044] The equation of the ellipsoid can be expressed by the following equation 3.

[0045] Formula 3: .

[0046] and Figure 7 The equation of the median ellipse can be expressed by the following formula 4.

[0047] Formula 4: .

[0048] When the working aperture of the focusing lens 130 is known to be l , the focal length is f When , the coordinates of point B are ( l / 2, b+c ),in c 2 = b 2 - a 2 ; The distance H1H2 is the focal length, that is , substituting the coordinates into the ellipse equation, we can obtain the following formula 5.

[0049] Formula 5: .

[0050] Then, the following formula 6 can be obtained through formula 5.

[0051] Formula 6: .

[0052] Therefore, the surface shape of the quadratic curved reflective cavity 140 can be determined by the known working aperture and focal length of the focusing mirror 130 .

[0053] Optionally, the cavity wall of the quadratic curved surface reflection cavity is enclosed by the tail portion of the housing, and the tail portion includes a first shell and a second shell. Figure 6 The quadratic curved surface reflection cavity 140 is hollow and is composed of a cavity wall and a housing 110. The housing 110 as a whole may include different parts, and different parts are installed at different positions of the housing 110. The quadratic curved surface reflection cavity 140 is located at the tail and may include a first shell and a second shell to facilitate processing into an ellipsoidal shape.

[0054] In a feasible implementation, the quadratic curved surface reflection cavity 140 is a double parabola type, and the surface parameters of the quadratic curved surface reflection cavity 140 are determined according to the working aperture and focal length of the focusing mirror 130. The quadratic curved surface reflection cavity 140 includes a first focus H1 and a second focus H2, and the second focus H2 coincides with the center of the working aperture.

[0055] Figure 8 The CC direction cross-sectional view of the double parabolic optical fiber probe 100 provided in the embodiment of the present application is as follows: Figure 8 As shown, the embodiment of the present application simplifies the double paraboloid structure design and adopts a top-bottom symmetrical structure, so the surface shapes of the two paraboloids are the same. In fact, the surface shapes of the two paraboloids can be different. Figure 8 For example, when the focus of the focusing mirror 130 is the focus of the lower parabola, that is, the first focus H1, and the center of the aperture of the focusing mirror 130 is the focus of the upper parabola, that is, the second focus H2, the light emitted from the focus of the focusing mirror 130 is reflected by the lower parabola cavity into parallel light, and then reflected by the upper parabola cavity to the center of the aperture of the focusing mirror 130, thereby expanding the spectral collection angle and improving the spectral collection efficiency.

[0056] In this embodiment, the surface parameters of the quadratic reflective cavity 140 refer to the parameters that determine the size of its double parabola, for example, the coordinate values ​​of the points on the double parabola. It can be understood that the double parabola can be regarded as being obtained by rotating two parabolas around the axes of their foci, and on the basis of determining the relationship between the first focus H1 and the second focus H2 of the quadratic reflective cavity 140 and the double parabola, the positions of the points on each parabola can be calculated according to the working aperture and focal length of the focusing mirror 130 to obtain the shape of the ellipsoidal surface.

[0057] Fig. 9A schematic diagram of the structure of the double parabola quadratic reflective cavity 140 provided in the embodiment of the present application is shown in FIG. Fig. 9 As shown, in the cross section of the double parabola-shaped reflection cavity, AB in the upper parabola is the working aperture of the focusing mirror 130; CD in the lower parabola is the lower end surface S2, which is also the focal plane of the focusing mirror 130; H1 is the focus of the focusing mirror 130, which is also the first focus; H2 is the center of the working aperture of the focusing mirror 130, which is also the second focus.

[0058] The embodiment of the present application adopts a simplified double paraboloid structure design, and adopts a top-bottom symmetrical structure, so the two paraboloids have the same surface shape. Take the paraboloid represented by the following formula 7 as an example.

[0059] Formula 7: .

[0060] Fig. 9 The equation of the parabola can be expressed as follows:

[0061] Formula 8: .

[0062] When the working aperture of the focusing lens is known to be l and the focal length is f, the coordinates of point C are (l / 2, p / 2). Substituting the coordinates into the parabola equation, the following formula 9 is obtained.

[0063] Formula 9: .

[0064] The following formula 10 is calculated.

[0065] Formula 10: .

[0066] Optionally, the cavity wall of the quadratic curved surface reflection cavity 140 is enclosed by the tail portion of the housing 110, the tail portion includes a first shell and a second shell, and the cavity walls of the first shell and the second shell are symmetrical in shape. Figure 8 The quadratic curved surface reflection cavity 140 is hollow and is composed of a cavity wall and a shell 110. The shell 110 as a whole may include different parts, and different parts are installed at different positions of the shell 110. The quadratic curved surface reflection cavity 140 is located at the tail, and may include a first shell and a second shell. The shapes of the cavity walls of the first shell and the second shell are symmetrical to reduce the difficulty of processing.

[0067] In this embodiment, on the one hand, in the spectral excitation stage, the plasma P is spatially constrained by the quadratic surface reflection cavity 140, so that the sound waves generated by the evolution process of the plasma P are reflected by the inner wall of the cavity, and the formed plasma P is compressed, thereby increasing the electron density and temperature of the plasma P, improving the radiation process of the plasma P, and thus improving the LIBS spectrum intensity. On the other hand, in the spectral collection stage, the quadratic surface reflection cavity 140 is used to reflect the radiation light of the plasma P outside the convergence angle of the focusing mirror 130 into the focusing mirror 130 for collection and detection, thereby expanding the spectral collection angle and greatly improving the spectral collection efficiency, thereby improving the sensitivity of LIBS detection. At the same time, since the center of the lower end surface S2 of the optical fiber probe 100 is the focus of the focusing mirror 130, that is, the lower end surface S2 is the focal plane of the focusing mirror, there is no need for a complex automatic focusing process, and the optical fiber probe 100 can directly contact the surface of the sample 200 to carry out LIBS measurement.

[0068] The present application embodiment provides a fiber LIBS remote detection system, Fig.10 This is a main concept diagram of a fiber LIBS remote detection system according to an embodiment of the present application, as shown in FIG. Fig.10 As shown, the fiber LIBS remote detection system includes a fiber optic probe 100, a main control module 300, and a fiber optic pulse laser 400, a spectrometer 500 and a timing control generator 600 respectively connected to the main control module 300 for communication; the timing control generator 600 is also connected to the fiber optic pulse laser 400 and the spectrometer 500 for communication respectively; the fiber optic pulse laser 400 and the spectrometer 500 are connected to the fiber optic probe 100 via a two-core Y-type optical fiber 700.

[0069] The fiber pulse laser 400 is used to emit pulsed laser light, which reaches the fiber probe 100 through the two-core Y-type optical fiber 700, excites plasma on the sample surface, generates radiation light, and then reaches the spectrometer 500 through the two-core Y-type optical fiber 700 to be collected and analyzed. The timing control generator 600 can control the pulse setting of the pulsed laser light.

[0070] Fig.11 This is a host structure diagram of a fiber LIBS remote detection system according to an embodiment of the present application, such as Fig.11 As shown, the fiber LIBS remote detection system in this embodiment can be divided into a system host and a main control module 300. The system host can include a fiber optic probe 100, a fiber pulse laser 400, a spectrometer 500, a timing control generator 600 and a two-core Y-type optical fiber 700. These components are housed in a host housing 800 through a suitable arrangement. Fig.12 This is an experimental scene diagram of an optical fiber LIBS remote detection system according to an embodiment of the present application, such as Fig.12As shown, when working, the two-core Y-type optical fiber 700 is taken out, one end is connected to the fiber pulse laser 400 and the spectrometer 500, and the other end is connected to the fiber probe 100, and the measurement can be quickly started.

[0071] The fiber optic probe 100 with a quadratic reflection cavity 140 is used for LIBS remote detection. On the one hand, in the spectral excitation stage, the quadratic reflection cavity 140 is used to generate spatial constraints on the plasma P, so that the sound waves generated by the evolution process of the plasma P are reflected by the inner wall of the cavity, and the formed plasma P is compressed, thereby increasing the electron density and temperature of the plasma P, improving the radiation process of the plasma P, and thus increasing the LIBS spectrum intensity. On the other hand, in the spectral collection stage, the quadratic reflection cavity 140 is used to reflect the radiation light of the plasma P outside the convergence angle of the focusing mirror 130 into the focusing mirror 130 for collection and detection, thereby expanding the spectral collection angle and greatly improving the spectral collection efficiency, thereby improving the sensitivity of LIBS detection. At the same time, since the center of the lower end surface S2 of the fiber optic probe 100 is the focus of the focusing mirror 130, that is, the lower end surface S2 is the focal plane of the focusing mirror, so there is no need for a complex automatic focusing process, and the fiber optic probe 100 can directly contact the surface of the sample 200 to carry out LIBS measurement.

[0072] The present application embodiment provides a fiber LIBS remote detection method, referring to Fig.13 , Fig.13 This is a flow chart of an embodiment of the optical fiber LIBS remote detection method of the present application.

[0073] In this embodiment, the optical fiber LIBS remote detection method includes steps S10 to S30: Step S10, setting the laser generation parameters of the fiber pulse laser and the spectrum acquisition parameters of the spectrometer; Before setting the relevant parameters, the experiment preparation can be performed first. The main control module 300 is connected to the system host for communication. The main control module 300 can be an electronic device with computing processing capabilities, such as a computer. Then one end of the two-core Y-type optical fiber 700 is connected to the fiber pulse laser 400 and the spectrometer 500, and the other end is connected to the fiber probe 100. The fiber probe 100 measures the area to be tested of the sample 200. Start the computer and the system host, and the fiber pulse laser 400, the spectrometer 500 and the timing control generator 600 are started accordingly. Then set the laser generation parameters and the spectrum acquisition parameters.

[0074] Laser generation parameters refer to parameters related to the emission of pulsed laser by the fiber pulse laser 400. For example, the laser generation parameters may include pulsed laser energy and frequency. Spectral acquisition parameters refer to parameters related to the acquisition of radiation light signals by the spectrometer 500. For example, the acquisition delay, integration time, and total acquisition times of the spectrometer 500 may be included.

[0075] Step S20, the main control module sends a detection instruction to the timing control generator, and the timing control generator controls the fiber pulse laser to emit laser according to the detection instruction. The laser enters the fiber probe through the two-core Y-type optical fiber, converges on the sample surface, and excites and generates plasma; Different detection parameters can be set through the main control module 300, so that the timing control generator 600 can control the laser emission mode of the fiber pulse laser 400 after receiving the detection command. The fiber pulse laser 400 emits laser light, which converges on the surface of the sample 200 after passing through the two-core Y-type optical fiber 700 and the optical fiber probe 100, and excites and generates plasma P.

[0076] Step S30: The radiation light of the plasma is enhanced by the optical fiber probe and detected by the spectrometer through the two-core Y-type optical fiber.

[0077] The radiation light of the plasma P is spatially confined by the quadratic curved surface reflection cavity 140, and the radiation light is enhanced. The radiation light is collected by the optical fiber probe 100 and transmitted to the spectrometer 500 for detection, wherein the quadratic curved surface reflection cavity 140 improves the spectrum collection efficiency.

[0078] This embodiment provides a fiber LIBS remote detection method, which uses a fiber LIBS remote detection system with a quadratic surface reflection cavity 140. On the one hand, in the spectrum excitation stage, the quadratic surface reflection cavity 140 generates spatial constraints on the plasma P, so that the sound waves generated by the evolution process of the plasma P are reflected by the inner wall of the cavity, and the formed plasma P is compressed, thereby increasing the electron density and temperature of the plasma P, improving the radiation process of the plasma P, and thus improving the LIBS spectrum intensity. On the other hand, in the spectrum collection stage, the quadratic surface reflection cavity 140 is used to reflect the plasma P radiation light outside the convergence angle of the focusing mirror 130 into the focusing mirror 130 for collection and detection, thereby expanding the spectrum collection angle and greatly improving the spectrum collection efficiency, thereby improving the sensitivity of LIBS detection. At the same time, since the center of the lower end surface S2 of the optical fiber probe 100 is the focus of the focusing mirror 130, that is, the lower end surface S2 is the focal plane of the focusing mirror, so there is no need for a complex automatic focusing process, and the optical fiber probe 100 can directly contact the surface of the sample 200 to carry out LIBS measurement.

[0079] In a feasible implementation manner, step S20 may include steps S21-S22: Step S21, obtaining the change of LIBS spectrum intensity of plasma over time and determining the spectrum collection adjustment parameters; It can be understood that the quadratic curved surface reflection cavity 140 not only constrains the plasma P in space, but also affects the radiation process of the plasma P in time. Fig.14 Schematic diagram of the time evolution of the Cu plasma emission spectrum under spatial confinement provided in an embodiment of the present application. Fig.14 The LIBS spectrum intensity changes at different times after laser excitation of the sample are shown. It can be seen that the difference in spectrum intensity at different delay times can reach a maximum of 2.09 times when spatial constraints are added. The relationship curve between the spectrum intensity and delay time of plasma P generated by different samples can be obtained to determine the appropriate spectrum acquisition time as a spectrum collection adjustment parameter.

[0080] Step S22, adjusting the spectrum collection parameters according to the spectrum collection adjustment parameters to optimize the spectrum collection of the spectrometer through time constraints.

[0081] Selecting the appropriate spectral acquisition time, adjusting the spectral acquisition delay and integration settings, and optimizing spectral collection through time constraints can effectively improve the LIBS spectral intensity and signal-to-noise ratio.

[0082] In this embodiment, on the basis of space constraint, time constraint is further performed by adjusting the spectrum acquisition parameters to optimize spectrum collection, thereby improving the spectrum acquisition effect.

[0083] It should be noted that the above examples are only used to understand the present application and do not constitute a limitation of the present application. More simple transformations based on this technical concept are all within the scope of protection of the present application.

[0084] The present application also provides an electronic device that can be used as the main control module 300 in the above embodiment, and the electronic device includes: at least one processor; and a memory that is communicatively connected to the at least one processor; wherein the memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the optical fiber LIBS remote detection method in the above embodiment.

[0085] Reference below Fig.15 , which shows a schematic diagram of the structure of an electronic device suitable for implementing the embodiments of the present application. The electronic devices in the embodiments of the present application may include but are not limited to mobile terminals such as mobile phones, laptop computers, digital broadcast receivers, PDAs (Personal Digital Assistants), PADs (Portable Application Descriptions), PMPs (Portable Media Players), etc., and fixed terminals such as digital TVs and desktop computers. Fig.15 The electronic device shown is merely an example and should not bring any limitation to the functions and scope of use of the embodiments of the present application.

[0086] like Fig.15As shown, the electronic device may include a processing device 1001 (e.g., a central processing unit, a graphics processor, etc.), which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM: Read Only Memory) 1002 or a program loaded from a storage device 1003 to a random access memory (RAM: Random Access Memory) 1004. In RAM1004, various programs and data required for the operation of the electronic device are also stored. The processing device 1001, ROM1002, and RAM1004 are connected to each other through a bus 1005. An input / output (I / O) interface 1006 is also connected to the bus. Generally, the following systems can be connected to the I / O interface 1006: an input device 1007 including, for example, a touch screen, a touch pad, a keyboard, a mouse, an image sensor, a microphone, etc.; an output device 1008 including, for example, a liquid crystal display (LCD: Liquid Crystal Display), a speaker, a vibrator, etc.; a storage device 1003 including, for example, a magnetic tape, a hard disk, etc.; and a communication device 1009. The communication device 1009 can allow the electronic device to communicate with other devices wirelessly or by wire to exchange data. Although the figure shows an electronic device with various systems, it should be understood that it is not required to implement or have all the systems shown. More or fewer systems can be implemented or have alternatively.

[0087] In particular, according to the embodiments disclosed in the present application, the process described above with reference to the flowchart can be implemented as a computer software program. For example, the embodiments disclosed in the present application include a computer program product, which includes a computer program carried on a computer-readable medium, and the computer program includes a program code for executing the method shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed from a network through a communication device, or installed from a storage device 1003, or installed from a ROM 1002. When the computer program is executed by the processing device 1001, the above-mentioned functions defined in the method of the embodiment disclosed in the present application are executed.

[0088] The electronic device provided by the present application adopts the optical fiber LIBS remote detection method in the above embodiment, which can solve the technical problem of limited detection sensitivity caused by low pulse laser energy density. Compared with the prior art, the beneficial effects of the electronic device provided by the present application are the same as the beneficial effects of the optical fiber LIBS remote detection method provided by the above embodiment, and the other technical features in the electronic device are the same as the features disclosed in the previous embodiment method, which will not be repeated here.

[0089] It should be understood that the various parts disclosed in this application can be implemented by hardware, software, firmware or a combination thereof. In the description of the above embodiments, specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0090] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

[0091] The present application also provides a computer-readable storage medium having computer-readable program instructions (ie, computer programs) stored thereon, and the computer-readable program instructions are used to execute the optical fiber LIBS remote detection method in the above-mentioned embodiment.

[0092] The computer-readable storage medium provided in the present application may be, for example, a USB flash drive, but is not limited to electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems or devices, or any combination of the above. More specific examples of computer-readable storage media may include, but are not limited to: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM: Random Access Memory), a read-only memory (ROM: Read Only Memory), an erasable programmable read-only memory (EPROM: Erasable Programmable Read Only Memory or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM: CD-Read Only Memory), an optical storage device, a magnetic storage device, or any suitable combination of the above. In this embodiment, the computer-readable storage medium may be any tangible medium containing or storing a program, which may be used by or in combination with an instruction execution system or device. The program code contained on the computer-readable storage medium may be transmitted using any appropriate medium, including but not limited to: wires, optical cables, RF (Radio Frequency: Radio Frequency), etc., or any suitable combination of the above.

[0093] The computer-readable storage medium may be included in the electronic device, or may exist independently without being installed in the electronic device.

[0094] Computer program code for performing the operations of the present application may be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, C++, and conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may be executed entirely on the user's computer, partially on the user's computer, as a separate software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0095] The flow chart and block diagram in the accompanying drawings illustrate the possible architecture, function and operation of the system, method and computer program product according to various embodiments of the present application. In this regard, each square box in the flow chart or block diagram can represent a module, a program segment or a part of a code, and the module, the program segment or a part of the code contains one or more executable instructions for realizing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the square box can also occur in a sequence different from that marked in the accompanying drawings. For example, two square boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each square box in the block diagram and / or flow chart, and the combination of the square boxes in the block diagram and / or flow chart can be implemented with a dedicated hardware-based system that performs a specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0096] The modules involved in the embodiments described in this application may be implemented by software or hardware, wherein the name of the module does not constitute a limitation on the unit itself in some cases.

[0097] The readable storage medium provided in the present application is a computer-readable storage medium, which stores computer-readable program instructions (i.e., computer programs) for executing the above-mentioned optical fiber LIBS remote detection method, and can solve the technical problem of limited detection sensitivity due to low pulse laser energy density. Compared with the prior art, the beneficial effects of the computer-readable storage medium provided in the present application are the same as the beneficial effects of the optical fiber LIBS remote detection method provided in the above-mentioned embodiment, and will not be described in detail here.

[0098] The present application also provides a computer program product, including a computer program, which implements the steps of the above-mentioned optical fiber LIBS remote detection method when executed by a processor.

[0099] The computer program product provided by the present application can solve the technical problem of limited detection sensitivity caused by low pulse laser energy density. Compared with the prior art, the beneficial effects of the computer program product provided by the present application are the same as the beneficial effects of the optical fiber LIBS remote detection method provided by the above embodiment, which will not be repeated here.

[0100] The above descriptions are only some embodiments of the present application, and are not intended to limit the patent scope of the present application. All equivalent structural changes made using the contents of the present application specification and drawings under the technical concept of the present application, or direct / indirect applications in other related technical fields are included in the patent protection scope of the present application.

Claims

1. A fiber optic probe, characterized in that: The optical fiber probe comprises: a housing, and a collimating mirror, a focusing mirror and a quadratic curved surface reflection cavity which are sequentially arranged in the housing along the incident direction of the laser; The quadratic curved surface reflection cavity comprises an upper end surface and a lower end surface, the lower end surface is in contact with the sample, and the upper end surface is in contact with the focusing mirror; The center of the lower end surface is the focus of the focusing mirror, and the focus of the focusing mirror coincides with the first focus of the quadratic curved surface reflection cavity; In the spectral excitation stage, the laser is collimated by the collimator after being incident, and is focused on the sample surface by the focusing mirror to excite and generate plasma, and the quadratic curved surface reflection cavity generates spatial constraints on the plasma; In the spectrum collection stage, the radiation light generated by the plasma is directly collected by the focusing mirror, or is reflected by the quadratic surface reflection cavity to the focusing mirror for collection.

2. The optical fiber probe according to claim 1, characterized in that The quadratic curved surface reflection cavity is a parabola, and the surface parameters of the quadratic curved surface reflection cavity are determined according to the working aperture and focal length of the focusing mirror.

3. The optical fiber probe according to claim 2, characterized in that The cavity wall of the quadratic curved surface reflection cavity is formed by enclosing the tail portion of the shell, and the tail portion is formed in an integrated form.

4. The optical fiber probe according to claim 1, characterized in that The quadratic curved surface reflection cavity is ellipsoidal, and the surface parameters of the quadratic curved surface reflection cavity are determined according to the working aperture and focal length of the focusing mirror. The quadratic curved surface reflection cavity includes a first focus and a second focus, and the second focus coincides with the center of the working aperture.

5. The optical fiber probe according to claim 4, characterized in that: The cavity wall of the quadratic curved surface reflection cavity is enclosed by the tail portion of the shell, and the tail portion includes a first shell and a second shell.

6. The optical fiber probe according to claim 1, characterized in that The quadratic curved surface reflection cavity is a double parabola type, and the surface parameters of the quadratic curved surface reflection cavity are determined according to the working aperture and focal length of the focusing mirror. The quadratic curved surface reflection cavity includes a first focus and a second focus, and the second focus coincides with the center of the working aperture.

7. The optical fiber probe according to claim 6, characterized in that The cavity wall of the quadratic curved surface reflection cavity is enclosed by the tail portion of the shell, and the tail portion includes a first shell and a second shell, and the cavity walls of the first shell and the second shell are symmetrical in shape.

8. A fiber LIBS remote detection system, characterized in that: The optical fiber probe comprises the optical fiber probe as claimed in any one of claims 1 to 7, and further comprises a main control module, and an optical fiber pulse laser, a spectrometer and a timing control generator respectively connected to the main control module for communication; The timing control generator is also communicatively connected to the fiber pulse laser and the spectrometer respectively; The fiber pulse laser and the spectrometer are connected to the fiber probe via a two-core Y-type optical fiber.

9. A fiber LIBS remote detection method, characterized in that: The optical fiber LIBS remote detection system as claimed in claim 8 comprises: Setting the laser generation parameters of the fiber pulse laser and the spectrum acquisition parameters of the spectrometer; The main control module sends a detection instruction to the timing control generator, and the timing control generator controls the fiber pulse laser to emit laser according to the detection instruction. The laser enters the fiber probe through the two-core Y-type optical fiber, converges on the sample surface, and excites and generates plasma; The radiation light of the plasma is enhanced by the optical fiber probe and detected by the spectrometer through the two-core Y-type optical fiber.

10. The optical fiber LIBS remote detection method according to claim 9, characterized in that: The main control module sends a detection instruction to the timing control generator, and the timing control generator controls the fiber pulse laser to emit laser according to the detection instruction. The laser enters the fiber probe through the two-core Y-type optical fiber and converges on the sample surface. After the step of exciting and generating plasma, the method further includes: Obtaining the change in LIBS spectrum intensity of the plasma over time, and determining spectrum collection adjustment parameters; The spectrum acquisition parameters are adjusted according to the spectrum collection adjustment parameters to optimize spectrum collection of the spectrometer under time constraints.

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