Target material spectral measurement device based on fs-ns DP-LIBS

Abstract

The utility model discloses a target material spectrum measuring device based on fs-ns DP-LIBS, which comprises an fs laser, an ns laser, a light path adjusting device, a spectroscope, a lens I and a scattered spectrum collecting device, and laser emitted by the fs laser sequentially passes through the spectroscope and the lens I and then bombards a target material to generate plasma cloud. Laser emitted by the ns laser sequentially passes through the light path adjusting device, the spectroscope and the lens I and then bombards the plasma cloud, the light path adjusting device can enable laser emitted by the ns laser and laser emitted by the fs laser to generate light path difference, and the spectroscope can enable the laser emitted by the ns laser and the laser emitted by the fs laser to be coaxial and then enter the lens I; the scattered spectrum collecting device is used for collecting and analyzing scattered light generated after the laser emitted by the ns laser bombards the plasma cloud. According to the utility model, the fs laser pulse firstly reaches the surface of the target material to generate the plasma cloud, and then the ns laser pulse bombards the plasma cloud, so that the signal-to-noise ratio is remarkably improved, and the lower limit of detection is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of optical detection, and particularly relates to a target material spectrum measuring device based on fs-ns DP-LIBS. Background Art

[0002] Laser-induced breakdown spectroscopy (LIBS) technology refers to forming a plasma by focusing an ultrashort pulse laser on the surface of a sample, and using a spectrometer to analyze the emission spectrum of the plasma to identify the elemental composition of the sample, and then material identification, classification, qualitative and quantitative analysis can be carried out. The double-pulse laser-induced breakdown spectroscopy (DP-LIBS) technology is an improved laser-induced breakdown spectroscopy technology. This technology uses two laser pulses to improve the quality and stability of the plasma, thereby improving the analysis performance. However, in the devices currently used for the double-pulse laser-induced breakdown spectroscopy technology, there is only one laser. The laser emitted by the laser hits a beam splitter, and the beam splitter divides the laser into two beams, and the two beams of laser are respectively made to bombard the target material through the optical path difference. However, since there is only one type of laser, either the single fs laser has a high power density or the ns laser has a high energy, which will instead affect the detection limit and the improvement of the signal-to-noise ratio. Therefore, how to provide a device that can combine the advantages of fs lasers and ns lasers, improve the detection limit and improve the signal-to-noise ratio, needs further consideration. Summary of the Utility Model

[0003] Aiming at the above deficiencies of the prior art, the technical problem to be solved by the utility model is: how to provide a target material spectrum measuring device based on fs-ns DP-LIBS that can improve the detection limit and the signal-to-noise ratio.

[0004] To solve the above technical problems, the utility model adopts the following technical solutions:

[0005] A target material spectrum measuring device based on fs-ns DP-LIBS includes an fs laser, an ns laser, an optical path adjusting device, a beam splitter, a lens I, and a scattered spectrum collecting device. The laser emitted by the fs laser is focused on the target material through the beam splitter and the lens I in sequence to generate a plasma cloud. The laser emitted by the ns laser is focused on the plasma cloud after passing through the optical path adjusting device, the beam splitter, and the lens I in sequence. The optical path adjusting device can make an optical path difference between the laser emitted by the ns laser and the laser emitted by the fs laser. The beam splitter can make the laser emitted by the ns laser and the laser emitted by the fs laser coaxial and then enter the lens I. The scattered spectrum collecting device is used to collect and analyze the scattered light of the laser emitted by the ns laser bombarding the plasma cloud.

[0006] First, the fs pulse bombards the surface of the target. Due to the short ablation time, it can significantly increase the power density on the premise of relatively low output energy, couple with the target to generate plasma, and the plasma density is relatively high. Then, the ns pulse bombards the plasma cloud generated by the former. Since the ns pulse has a larger time scale compared to the fs pulse, although the power density is not high, the pulse energy is high, which just meets the requirements of our work, enabling the ns pulse energy to be absorbed by the plasma cloud and greatly increasing the spectral intensity. The fs pulse has a high power density and can generate a plasma cloud faster, and the density of the plasma cloud is also very high. The power density of the ns pulse is smaller than that of the fs pulse, so it will not generate supersaturation faster, and due to its large time scale, it can be fully absorbed of energy.

[0007] As an optimization, the optical path adjustment device includes a first mirror, a second mirror, a third mirror, a fourth mirror, an adjustment bracket, and a moving drive device. The laser emitted by the ns laser can sequentially pass through the first mirror, the second mirror, the third mirror, and the fourth mirror and then be projected onto the beam splitter. The second mirror and the third mirror are placed on the adjustment bracket, and the moving drive device is used to drive the adjustment bracket to move so that the second mirror and the third mirror approach or move away from the first mirror and the fourth mirror. By moving the adjustment bracket to adjust and control the optical path, the laser emitted by the fs laser and the laser emitted by the ns laser can generate different optical path differences, optimizing the detection performance.

[0008] As an optimization, the first mirror, the second mirror, the third mirror, and the fourth mirror are all coated high-reflection mirrors. The coated high-reflection mirrors can reduce light scattering and contribute to improving the detection performance of the system.

[0009] As an optimization, the scattered spectrum collection device includes a second lens and a spectrometer. The second lens is used to collect the scattered light of the laser emitted by the ns laser bombarding the plasma cloud. A fiber optic probe is arranged at the focus on the side of the second lens away from the target, and the input end of the spectrometer is connected to the fiber optic probe through an optical fiber.

[0010] As an optimization, an attenuation filter group is also arranged on the optical path of the laser emitted by the ns laser. By observing the heating degree of the plasma by pulsed lasers with different energies through attenuation, it can prevent heat supersaturation, otherwise the signal-to-noise ratio will be affected.

[0011] Compared with the prior art, the present utility model has the following beneficial effects: The present utility model first generates a plasma cloud on the surface of the target by the fs laser pulse, and then the ns laser pulse bombards the plasma cloud, enabling the ns pulse energy to be absorbed by the plasma cloud, thereby significantly improving the signal-to-noise ratio and lowering the detection limit. Description of the Drawings

[0012] Figure 1 It is a schematic structural diagram of the present utility model. Detailed implementation manners

[0013] 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. Apparently, the described embodiments are some but not all of the embodiments of the present utility model. Components of the embodiments of the present utility model usually described and illustrated in the accompanying drawings here can be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of the present utility model provided in the accompanying 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. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts fall within the scope of protection of the present utility model.

[0014] It should be noted that: similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. In the description of the present utility model, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship when the product of this utility model is normally placed. This 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 therefore cannot be understood 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, 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 defined 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 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.

[0015] Such as Figure 1As shown in the figure, the target spectral measurement device based on fs-ns DP-LIBS in this specific embodiment includes an fs laser 1, an ns laser 2, an optical path adjustment device, a beam splitter 3, a lens I 4, and a scattered spectrum collection device. The laser emitted by the fs laser 1 can generate a plasma cloud after passing through the beam splitter 3 and the lens I 4 in sequence and bombarding the target. The laser emitted by the ns laser 2 can bombard the plasma cloud after passing through the optical path adjustment device, the beam splitter 3, and the lens I 4 in sequence. The optical path adjustment device can generate an optical path difference between the laser emitted by the ns laser 2 and the laser emitted by the fs laser 1. The beam splitter 3 can make the laser emitted by the ns laser 2 and the laser emitted by the fs laser 1 coaxial and then enter the lens I 4. The scattered spectrum collection device is used to collect and analyze the scattered light of the laser emitted by the ns laser bombarding the plasma cloud.

[0016] In this specific embodiment, the optical path adjustment device includes a mirror I 5, a mirror II 6, a mirror III 7, a mirror IV 8, an adjustment bracket, and a moving drive device. The laser emitted by the ns laser 2 can pass through the mirror I 5, the mirror II 6, the mirror III 7, and the mirror IV 8 in sequence and then be incident on the beam splitter 3. The mirror II 6 and the mirror III 7 are placed on the adjustment bracket. The moving drive device is used to drive the adjustment bracket to move so that the mirror II 6 and the mirror III 7 are close to or away from the mirror I 5 and the mirror IV 8.

[0017] In this specific embodiment, the mirror I 5, the mirror II 6, the mirror III 7, and the mirror IV 8 are all coated high-reflection mirrors.

[0018] In this specific embodiment, the scattered spectrum collection device includes a lens II 9 and a spectrometer 10. The lens II 9 is used to collect the scattered light of the laser emitted by the ns laser 2 bombarding the plasma cloud. A fiber optic probe 11 is arranged at the focal point on the side of the lens II 9 away from the target. The input end of the spectrometer 10 is connected to the fiber optic probe 11 through a fiber optic cable.

[0019] In this specific embodiment, an attenuation sheet group is also arranged on the optical path of the laser emitted by the ns laser.

[0020] In the specific implementation method, for the fs laser: the pulse half-height width is 10 1 fs, the central wavelength is 10 2 nm, and the frequency is 10 3 Hz; for the ns laser: the pulse half-height width is 10 0 ns, the central wavelength is 10 2 nm, and the frequency is 10 3Hz. First, the fs pulse bombards the surface of the target. Since the ablation time is short, the power density can be significantly increased on the premise of a small output energy, generating plasma by coupling with the target, and the plasma density is relatively high. Then, the ns pulse bombards the plasma cloud generated by the former. Since the ns pulse has a larger time scale than the fs pulse, although the power density is not high, the pulse energy is high, just meeting the working requirements, so that the ns pulse energy is absorbed by the plasma cloud, greatly increasing the spectral intensity. By combining the two, the advantages of both are effectively utilized.

[0021] 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 spirit and scope of the present technical solution shall be covered by the scope of the claims of the present invention.

Claims

1. A target spectral measurement device based on fs-ns DP-LIBS, characterized in that: It includes a fs laser, a ns laser, an optical path adjustment device, a beam splitter, a lens I, and a scattered spectrum collection device. The laser emitted by the fs laser can generate a plasma cloud after passing through the beam splitter and being focused by the lens I in sequence and bombarding the target material. The laser emitted by the ns laser can bombard the plasma cloud after passing through the optical path adjustment device, the beam splitter, and being focused by the lens I in sequence. The optical path adjustment device can create an optical path difference between the laser emitted by the ns laser and the laser emitted by the fs laser. The beam splitter can make the laser emitted by the ns laser and the laser emitted by the fs laser coaxial and then enter the lens I. The scattered spectrum collection device is used to collect and analyze the scattered light of the laser emitted by the ns laser bombarding the plasma cloud.

2. The target spectral measurement device based on fs-ns DP-LIBS according to claim 1, wherein: The optical path adjustment device includes a mirror I, a mirror II, a mirror III, a mirror IV, an adjustment bracket, and a moving drive device. The laser emitted by the ns laser can be reflected by the mirror I, the mirror II, the mirror III, and the mirror IV in sequence and then be incident on the beam splitter. The mirror II and the mirror III are placed on the adjustment bracket. The moving drive device is used to drive the adjustment bracket to move so that the mirror II and the mirror III are close to or away from the mirror I and the mirror IV.

3. The target spectral measurement device based on fs-ns DP-LIBS according to claim 2, wherein: The mirror I, the mirror II, the mirror III, and the mirror IV are all high-reflection coated mirrors.

4. The target spectral measurement device based on fs-ns DP-LIBS according to claim 1, characterized in that: The scattered spectrum collection device includes a lens II and a spectrometer. The lens II is used to collect the scattered light of the laser emitted by the ns laser bombarding the plasma cloud. An optical fiber probe is arranged at the focal point on the side of the lens II away from the target material. The input end of the spectrometer is connected to the optical fiber probe through an optical fiber.

5. The target spectral measurement device based on fs-ns DP-LIBS according to claim 1, wherein: An attenuation filter set is also arranged on the optical path of the laser emitted by the ns laser.

Images