Device for measuring time-space characteristics of LIBS (laser-induced breakdown spectroscopy) orthogonal pulse

Abstract

The utility model discloses an LIBS (Laser-induced Breakdown Spectroscopy) orthogonal pulse space-time characteristic measuring device which comprises a laser device, a light path adjusting device, a spectroscope, a lens I, a lens II and a scattered spectrum collecting device, and laser emitted by the laser device is divided into a laser beam I and a laser beam II after passing through the spectroscope; the laser beam I is focused through the light path adjusting device and the lens I and then bombards a target material to generate plasma cloud, the laser beam II is bombarded on the plasma cloud after passing through the lens II, the scattered spectrum collecting device comprises a lens III, a plane moving device, an ICCD device and a computer, and the lens III collects scattered light generated by the plasma cloud. The output end of the ICCD device is connected with the input end of a computer, the input end of the ICCD device is connected with an optical fiber probe through an optical fiber, the optical fiber probe is fixed to a plane moving device, and the moving plane of the optical fiber probe is perpendicular to the optical axis of scattered light generated by the plasma cloud after the scattered light penetrates through a lens III. A focusing focus on one side, far away from the plasma cloud, of the lens III is positioned on a moving plane of the optical fiber probe.

Description

Technical Field

[0001] The utility model relates to the technical field of optical detection, and particularly relates to a measuring device for the spatio-temporal characteristics of LIBS orthogonal pulses. Background Art

[0002] Laser-induced breakdown spectroscopy (LIBS) technology refers to forming a plasma by focusing an ultrashort pulsed laser on the surface of a sample, and analyzing the emission spectrum of the plasma using a spectrometer to identify the elemental composition components in the sample, and then material identification, classification, qualitative and quantitative analysis can be carried out. The spatio-temporal characteristics of the plasma plume refer to the changes of the plasma over time and space during its formation and development. The spatio-temporal characteristics of the laser-induced breakdown spectroscopy technology are crucial for the detection quality and accuracy. By controlling the spatio-temporal characteristics of the laser pulse, the influence of background signals and matrix effects can be reduced, and the accuracy of the analysis results can be improved. Therefore, it is necessary to provide a measuring device for the spatio-temporal characteristics of LIBS orthogonal pulses that is convenient and reliable to use and can accurately understand the changes in the spatio-temporal characteristics of the plasma plume. Summary of the Utility Model

[0003] Aiming at the deficiencies of the above-mentioned prior art, the technical problem to be solved by the utility model is: how to provide a measuring device for the spatio-temporal characteristics of LIBS orthogonal pulses that is convenient and reliable to use and can accurately understand the changes in the spatio-temporal characteristics of the plasma plume.

[0004] To solve the above technical problem, the utility model adopts the following technical scheme:

[0005] A measuring device for the spatio-temporal characteristics of LIBS orthogonal pulses includes a laser, an optical path adjusting device, a beam splitter, a lens I, a lens II and a scattered spectrum collecting device. The laser emitted by the laser can be divided into a laser beam I and a laser beam II after passing through the beam splitter. The laser beam I passes through the optical path adjusting device and the lens I in sequence and is vertically bombarded on the target material to generate a plasma plume. The laser beam II can be focused and bombarded on the plasma plume after reflection and passing through the lens II. The optical path adjusting device can generate an optical path difference between the laser beam I and the laser beam II. The optical axis of the laser beam I bombarding the target material is orthogonal to the optical axis of the laser beam II bombarding the plasma plume. The scattered spectrum collecting device includes a lens III, a planar moving device, an ICCD device and a computer. The lens III is used to collect the scattered light generated by the plasma plume. The output end of the ICCD device is connected to the input end of the computer. The input end of the ICCD device is connected with an optical fiber probe through an optical fiber. The optical fiber probe is located on the side of the lens III facing away from the plasma plume. The optical fiber probe is fixed on the planar moving device. The planar moving device can drive the optical fiber probe to move in a plane. The moving plane of the optical fiber probe is perpendicular to the optical axis of the scattered light generated by the plasma plume after passing through the lens III, and the focusing focus on the side of the lens III away from the plasma plume is located on the moving plane of the optical fiber probe.

[0006] As an optimization, the optical path adjusting device includes a first mirror, a second mirror, a third mirror, a fourth mirror, an adjusting bracket and a moving driving device. The first laser beam can be projected onto the first lens after passing through the first mirror, the second mirror, the third mirror and the fourth mirror in sequence. The second mirror and the third mirror are placed on the adjusting bracket, and the moving driving device is used to drive the adjusting bracket to move so that the second mirror and the third mirror approach or move away from the first mirror and the fourth mirror.

[0007] As an optimization, the first mirror, the second mirror, the third mirror and the fourth mirror are all coated high-reflection mirrors.

[0008] As an optimization, the splitting ratio of the beam splitter for the first laser beam and the second laser beam is 5:5.

[0009] As an optimization, a diaphragm is further arranged on the optical path between the laser and the beam splitter.

[0010] Compared with the prior art, the present utility model has the following beneficial effects:

[0011] (1) By using orthogonal double-pulse lasers, the plasma spectral intensity can be increased through laser pulse superposition, greatly improving the signal-to-noise ratio of LIBS measurement and enhancing the overall detection limit.

[0012] (2) By fixing the collection lens for collecting the plasma cloud spectrum, moving the plane of the optical fiber probe, and simultaneously fixing the entire pulse lifetime of the plasma cloud spectrum collection by the ICCD device, the spatio-temporal characteristics of the LIBS spectrum can be detected. Description of the Drawings

[0013] Figure 1 It is a schematic structural diagram of the present utility model. Detailed Embodiments

[0014] To make the objectives, technical solutions and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are some, but not all, of the embodiments of the present utility model. Usually, the components of the embodiments of the present utility model described and illustrated herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present utility model provided in the drawings is not intended to limit the scope of the present utility model to be protected, but merely represents the selected embodiments of the present utility model. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model.

[0015] It should be noted that like reference numerals and letters denote like items in the following figures. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. In the description of the present utility model, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the figures, or the orientation or positional relationship in which the utility model product is customarily placed during use. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present utility model. In addition, the terms "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance. In addition, terms such as "horizontal" and "vertical" do not mean that the components are required to be absolutely horizontal or hanging vertically, but can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined. In the description of the present utility model, it should also be noted that unless otherwise clearly specified and limited, the terms "set", "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0016] Such as Figure 1As shown in the figure, the measurement device for the spatio-temporal characteristics of LIBS orthogonal pulses in this specific embodiment includes a laser 1, an optical path adjustment device, a beam splitter 2, a lens I 3, a lens II 4, and a scattered spectrum collection device. The laser emitted by the laser 1 can be divided into a laser beam I and a laser beam II after passing through the beam splitter 2. The laser beam I can vertically bombard the target material to generate a plasma cloud after passing through the optical path adjustment device and being focused by the lens I 3 in sequence. The laser beam II can be focused and bombarded on the plasma cloud after reflection and passing through the lens II 4. The optical path adjustment device can generate an optical path difference between the laser beam I and the laser beam II. The optical axis of the laser beam I bombarding the target material is orthogonal to the optical axis of the laser beam II bombarding the plasma cloud. The scattered spectrum collection device includes a lens III 5, a planar moving device, an ICCD device 6, and a computer 7. The lens III 5 is used to collect the scattered light generated by the plasma cloud. The output end of the ICCD device 6 is connected to the input end of the computer 7. The input end of the ICCD device 6 is connected with an optical fiber probe 8 through an optical fiber. The optical fiber probe 8 is located on one side of the lens III 5 facing away from the direction where the plasma cloud is located. The optical fiber probe 8 is fixed on the planar moving device. The planar moving device can drive the optical fiber probe 8 to move within a plane. The moving plane of the optical fiber probe 8 is perpendicular to the optical axis of the scattered light generated by the plasma cloud after passing through the lens III 5. And the focusing focus on the side of the lens III 5 away from the plasma cloud is located on the moving plane of the optical fiber probe 8.

[0017] In this specific embodiment, the optical path adjustment device includes a mirror I 9, a mirror II 10, a mirror III 11, a mirror IV 12, an adjustment bracket, and a moving driving device. The laser beam I can be projected onto the lens I 3 after passing through the mirror I 9, the mirror II 10, the mirror III 11, and the mirror IV 12 in sequence. The mirror II 10 and the mirror III 11 are placed on the adjustment bracket. The moving driving device is used to drive the adjustment bracket to move so that the mirror II 10 and the mirror III 11 are close to or away from the mirror I 9 and the mirror IV 12.

[0018] In this specific embodiment, the mirror I 9, the mirror II 10, the mirror III 11, and the mirror IV 12 are all coated high-reflection mirrors.

[0019] In this specific embodiment, the beam splitting ratio of the beam splitter 2 for the laser beam I and the laser beam II is 5:5.

[0020] In this specific embodiment, a diaphragm 13 is further provided on the optical path between the laser 1 and the beam splitter 2.

[0021] The femtosecond pulse laser emits a near-infrared femtosecond pulse laser with a beam spot diameter of 8 mm, a power of 400 mW, a central wavelength of 810 nm, a frequency of 1000 Hz, and a pulse width of 33 fs. The beam is limited by a diaphragm, shaped into a parallel beam, and split by a beam splitter. After the optical path of the first beam of pulsed light is adjusted by an optical path adjustment device, it passes through a lens and is focused vertically onto the target surface to ablate the target material to generate a high-temperature and high-density plasma cloud. The other beam of pulsed light arrives at the plasma cloud generated by the previous beam in an orthogonal direction, thereby generating a dual-pulse enhanced spectrum.

[0022] A phase difference is formed between the orthogonal dual-pulse lasers, which arrive at the target surface successively, achieving the effect of enhancing the plasma cloud spectrum.

[0023] This application uses the laser-induced breakdown spectroscopy (LIBS) method to excite the atomic and different valence state ion excitation spectra of several specific target material samples, and inversely deduce the composition of the specific target material samples; calculate the content of the specific target material through the ratio of the peak areas of the excited characteristic spectral peaks, so as to qualitatively and quantitatively calibrate the content of different substances in the specific target material.

[0024] Through the LIBS spectral experimental data, the influence and contribution of different specific target material contents to the entire detection sample can be further obtained. Here, by measuring the LIBS spectral characteristics and combining with the NIST database, an ordered screening method for specific target material molecules can be obtained, which can quickly and non-destructively detect and simultaneously detect multiple elements of the target material.

[0025] The spectrum of the plasma cloud is collected into an ICCD device for further analysis. Since the plasma cloud presents an ellipsoidal shape and has a certain spatial distribution, this application needs to fix the collection fiber optic probe on a stepping motor combination console that can move freely in a two-dimensional plane, keep the focal distance between the fiber optic probe and the collection lens unchanged, and control the stepping motor to make the fiber optic probe move on the plane according to the set route to measure the distribution of the plasma cloud at different spatial positions. In further calculations, the plasma temperature and plasma density at different spatial points of the plasma cloud can be obtained, laying an experimental foundation for later analysis and discussion of the gradient change of the plasma spatial distribution.

[0026] The plasma cloud at different spatial distribution points is focused by a collection lens, then conducted to an ICCD device through a fiber optic probe, the gate width is fixed, and the initial timing time is set. The change trend of the entire plasma cloud from generation to annihilation at different spatial distribution points can be analyzed (measured on a time scale). Combining the changes in the plasma temperature and density of the plasma cloud with the spatial scale distribution and the ICCD analysis with the time scale changes can well give the spatio-temporal characteristic changes of the plasma cloud.

[0027] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Those of ordinary skill in the art should understand that any modifications or equivalent replacements made to the technical solutions of the present invention without departing from the purpose and scope of the technical solutions should be covered within the scope of the claims of the present invention.

Claims

1. A measuring device for the spatio-temporal characteristics of LIBS orthogonal pulses, characterized in that: It includes a laser, an optical path adjusting device, a beam splitter, lens I, lens II and a scattered spectrum collecting device. The laser beam emitted by the laser can be divided into laser beam I and laser beam II after passing through the beam splitter. Laser beam I can vertically bombard the target to generate a plasma cloud after passing through the optical path adjusting device and being focused by lens I in sequence. Laser beam II can be focused and bombarded on the plasma cloud after reflection and passing through lens II. The optical path adjusting device can create an optical path difference between laser beam I and laser beam II. The optical axis of laser beam I bombarding the target is orthogonal to the optical axis of laser beam II bombarding the plasma cloud. The scattered spectrum collecting device includes lens III, a planar moving device, an ICCD device and a computer. Lens III is used to collect the scattered light generated by the plasma cloud. The output end of the ICCD device is connected to the input end of the computer. The input end of the ICCD device is connected with an optical fiber probe through an optical fiber. The optical fiber probe is located on the side of lens III facing away from the direction where the plasma cloud is located. The optical fiber probe is fixed on the planar moving device. The planar moving device can drive the optical fiber probe to move within a plane. The moving plane of the optical fiber probe is perpendicular to the optical axis of the scattered light generated by the plasma cloud after passing through lens III, and the focusing focus on the side of lens III away from the plasma cloud is located on the moving plane of the optical fiber probe.

2. The measurement device for the spatio-temporal characteristics of LIBS orthogonal pulses according to claim 1, characterized in that: The optical path adjusting device includes mirror I, mirror II, mirror III, mirror IV, an adjusting bracket and a moving driving device. Laser beam I can be incident on lens I after passing through mirror I, mirror II, mirror III and mirror IV in sequence. Mirror II and mirror III are placed on the adjusting bracket. The moving driving device is used to drive the adjusting bracket to move so that mirror II and mirror III are close to or away from mirror I and mirror IV.

3. The measurement device for the spatio-temporal characteristics of LIBS orthogonal pulses according to claim 2, wherein: Mirror I, mirror II, mirror III and mirror IV are all coated high-reflection mirrors.

4. The measuring device for the spatio-temporal characteristics of LIBS orthogonal pulses according to claim 1, characterized in that: The beam splitting ratio of the beam splitter for laser beam I and laser beam II is 5∶5.

5. The measurement device for the spatio-temporal characteristics of LIBS orthogonal pulses according to claim 1, characterized in that: A diaphragm is also provided on the optical path between the laser and the beam splitter.

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