WO2021184558A1 - 一种多气体混合libs信号增强装置和重金属检测方法 - Google Patents

一种多气体混合libs信号增强装置和重金属检测方法 Download PDF

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WO2021184558A1
WO2021184558A1 PCT/CN2020/095372 CN2020095372W WO2021184558A1 WO 2021184558 A1 WO2021184558 A1 WO 2021184558A1 CN 2020095372 W CN2020095372 W CN 2020095372W WO 2021184558 A1 WO2021184558 A1 WO 2021184558A1
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gas
laser
libs
sample
chamber
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French (fr)
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刘飞
申婷婷
王唯
孔汶汶
刘小丹
陈榕钦
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Zhejiang University
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Zhejiang University
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J49/00—Particle spectrometers or separator tubes
    • H01J49/004—Combinations of spectrometers, tandem spectrometers, e.g. MS/MS, MSn
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/71—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light thermally excited
    • G01N21/718—Laser microanalysis, i.e. with formation of sample plasma
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J49/00—Particle spectrometers or separator tubes
    • H01J49/0027—Methods for using particle spectrometers
    • H01J49/0036—Step by step routines describing the handling of the data generated during a measurement
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J49/00—Particle spectrometers or separator tubes
    • H01J49/02—Details
    • H01J49/10—Ion sources; Ion guns
    • H01J49/105—Ion sources; Ion guns using high-frequency excitation, e.g. microwave excitation, Inductively Coupled Plasma [ICP]
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum
    • G01J3/443—Emission spectrometry
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00—Sampling; Preparing specimens for investigation
    • G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
    • G01N1/38—Diluting, dispersing or mixing samples
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2201/00—Features of devices classified in G01N21/00
    • G01N2201/06—Illumination; Optics
    • G01N2201/061—Sources
    • G01N2201/06113—Coherent sources; lasers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2201/00—Features of devices classified in G01N21/00
    • G01N2201/08—Optical fibres; light guides

Definitions

  • the invention relates to the technical field of LIBS spectral information detection, in particular to a multi-gas mixed LIBS signal enhancement device and a heavy metal detection method.
  • LIBS laser induced breakdown spectroscopy
  • LIBS signal enhancement technology is the focus of research in this hotspot.
  • the plasma expands from heating to cooling, producing energy level transition emission spectrum signals.
  • the change of the environment atmosphere will affect the evolution mechanism of laser-induced plasma over time.
  • the purpose of the present invention is to provide a multi-gas mixed LIBS signal enhancement device and heavy metal detection method, which can enhance the LIBS spectral information and improve the accuracy of heavy metal content determination by changing the atmosphere environment where the plasma is located.
  • the present invention provides a multi-gas hybrid LIBS signal enhancement device, which includes:
  • Solid-state pulsed laser used to generate laser
  • the optical path system is connected with the solid-state pulsed laser for transmitting laser light
  • the multi-gas mixing spherical gas chamber is arranged corresponding to the optical path system, and is used to provide a uniform mixed gas atmosphere environment for the sample to be tested;
  • An optical fiber collector is arranged corresponding to the multi-gas mixing spherical gas chamber, and is used to receive the optical signal generated during the diffusion process of the plasma signal; the plasma signal is generated based on the laser ablating the sample to be detected;
  • a spectrometer connected to the optical fiber collector, and configured to determine laser-induced breakdown spectrum information according to the optical signal received by the optical fiber collector;
  • the controller is respectively connected to the spectrometer and the solid-state pulsed laser, and is used to determine the LIBS spectrum information in the form of a graph according to the received laser-induced breakdown spectrum information; and is also used to obtain instrument parameters and generate them according to the instrument parameters
  • the control instruction controls the solid-state pulsed laser to generate laser light; the instrument parameters include the distance from the lens in the optical path system to the surface of the sample to be tested and the laser energy.
  • the device further includes:
  • the delay integral generator is respectively connected with the controller and the spectrometer, and is used for controlling the working sequence of the spectrometer according to the delay time and the integration time in the instrument parameters.
  • the multi-gas mixing spherical gas chamber includes:
  • the first gas storage tank is used to store argon
  • the second gas storage tank is used to store helium
  • the third gas storage tank is used to store nitrogen
  • a gas splitter connected to the gas mixing tank through a pipeline, for splitting the mixed gas in the gas mixing tank;
  • An air chamber with a sample stage used to place the sample to be tested on the sample stage, and to set the sample to be tested and the optical path system correspondingly;
  • a plurality of gas transmission pipes are respectively connected to the gas splitter and the gas chamber chamber, and are used to transmit the mixed gas in the gas storage tank to the gas chamber chamber, so as to provide the sample to be tested Provide a homogeneous mixed gas atmosphere environment;
  • the vacuum pump is connected to the gas mixing tank through a pipeline, and is used for vacuuming the gas mixing tank.
  • the multi-gas mixing spherical gas chamber further includes:
  • the quartz window is set on the top of the gas chamber and has the same normal as the optical fiber collector, and is used to transmit the plasma signal generated by the laser ablating the sample to be detected, so that the optical fiber collects
  • the sensor receives the optical signal generated during the diffusion process of the plasma signal.
  • a control valve is arranged on the pipeline between the gas splitter and the gas mixing tank, connected to the controller, and used for controlling the mixed gas in the gas mixing tank to flow out according to the control command generated by the controller The gas flow rate.
  • the multi-gas mixing spherical gas chamber further includes:
  • the exhaust valve is arranged at the bottom of the air chamber cabin. When the air pressure in the air chamber cabin is higher than the atmospheric pressure, the exhaust valve will automatically discharge part of the mixed gas to keep the air pressure in the air chamber cabin stable.
  • the air chamber is a sphere with a diameter of 20 cm, and the top of the sphere is inlaid with the quartz window; the quartz window is a circle with a diameter of 3 cm, and the upper half of the sphere is evenly distributed.
  • the present invention also provides a heavy metal detection method, which includes:
  • the LIBS spectrum information is input into a multiple linear regression model to determine the true content of heavy metals.
  • the establishment of a multiple linear regression model of emission spectral line intensity-heavy metal content specifically includes:
  • the determining the sample to be tested specifically includes:
  • the plants to be tested are collected, washed, dried, ground, sieved, and tableted to obtain samples to be tested.
  • the present invention discloses the following technical effects:
  • the present invention provides a multi-gas hybrid LIBS signal enhancement device and a heavy metal detection method.
  • the device includes: a solid-state pulsed laser, an optical path system, a multi-gas mixing spherical gas chamber, an optical fiber collector, a spectrometer and a controller; an optical path system and a solid Pulse laser connection, the multi-gas mixing spherical gas chamber is set corresponding to the optical path system, the fiber collector is set corresponding to the multi-gas mixing spherical gas chamber, the spectrometer is connected with the fiber collector, the controller is connected with the spectrometer and the solid-state pulse laser respectively, and the spectrometer is based on the fiber
  • the optical signal received by the collector determines the laser-induced breakdown spectrum information; the controller determines the spectrum form LIBS spectrum information according to the received laser-induced breakdown spectrum information; the present invention provides uniform mixing of multiple gases for the laser ablation of the sample to be tested to generate plasma The ability of the ambient atmosphere to adjust the gas input and the ratio of air according
  • FIG. 1 is a schematic structural diagram of a signal enhancement device according to an embodiment of the present invention.
  • FIG. 2 is a top view of the spherical air chamber in the signal enhancement device according to the embodiment of the present invention.
  • Figure 3 is a side view of the spherical air chamber in the signal enhancement device of the embodiment of the present invention.
  • FIG. 4 is a schematic diagram of the structure when a signal enhancement device is used in an embodiment of the present invention.
  • the purpose of the present invention is to provide a multi-gas mixed LIBS signal enhancement device and heavy metal detection method, which can enhance the LIBS spectral information and improve the accuracy of heavy metal content determination by changing the atmosphere environment where the plasma is located.
  • Fig. 1 is a schematic structural diagram of a signal enhancement device according to an embodiment of the present invention.
  • the present invention provides a multi-gas hybrid LIBS signal enhancement device.
  • the device includes: a solid-state pulsed laser 1, an optical path system 2, a multi-gas hybrid
  • the optical path system 2 is connected to the solid-state pulsed laser 1
  • the multi-gas mixing spherical gas chamber 3 is arranged corresponding to the optical path system.
  • the optical fiber collector 4 is arranged corresponding to the multi-gas mixing spherical gas chamber 3, the spectrometer 5 is connected to the optical fiber collector 4 through a wire 7, and the controller 8 is connected to the spectrometer 5 and the spectrometer 5 through a wire 7 respectively.
  • the solid pulse laser 1 is connected.
  • the solid-state pulsed laser 1 is used to generate laser light; the optical path system 2 is used to transmit laser light; the multi-gas mixing spherical gas chamber 3 is used to provide a uniform mixed gas atmosphere environment for the sample to be tested; the optical fiber collector 4 is used The optical signal generated in the process of receiving the plasma signal diffusion; the plasma signal is generated based on the laser ablation of the sample to be detected; the spectrometer 5 is used for the optical signal received by the optical fiber collector 4 Determine the laser-induced breakdown spectrum information; the controller 8 is used to determine the spectrum form LIBS spectrum information according to the received laser-induced breakdown spectrum information; it is also used to obtain instrument parameters and generate control commands according to the instrument parameters.
  • the solid-state pulsed laser 1 generates laser light; the instrument parameters include the distance from the lens in the optical path system 2 to the surface of the sample to be tested and the laser energy.
  • the device of the present invention further includes:
  • the delay integration generator 6 is respectively connected to the controller 8 and the spectrometer 5 through wires 7 and is used to control the working sequence of the spectrometer 5 according to the delay time and the integration time in the instrument parameters.
  • the multi-gas mixing spherical gas chamber 3 of the present invention includes: a first gas storage tank 3-1, a second gas storage tank 3-2, a third gas storage tank 3-3, gas Mixing tank 3-12, gas splitter 3-6, gas chamber 3-11 with sample stage 3-9, multiple gas transmission pipes 3-7 and vacuum pump 3-5; the gas mixing tank 3-12 Connected to the first gas storage tank 3-1, the second gas storage tank 3-2 and the third gas storage tank 3-3 through pipelines, the gas splitter 3-6 Connected to the gas mixing tank 3-12 through pipelines, the multiple gas transmission pipes 3-7 are respectively connected to the gas splitter 3-6 and the gas chamber compartment 3-11, and the vacuum pump 3- 5 is connected to the gas mixing tank 3-12 through a pipeline.
  • the first gas storage tank 3-1 is used for storing argon; the second gas storage tank 3-2 is used for storing helium; the third gas storage tank 3-3 is used for Store nitrogen; the gas mixing tank 3-12 is used to mix argon, helium, and nitrogen to obtain a mixed gas; the gas splitter 3-6 is used to control the gas in the gas mixing tank 3-12 The mixed gas is split; the gas chamber 3-11 with the sample stage 3-9 is used to place the sample to be tested on the sample stage 3-9, and combine the sample to be tested with the
  • the optical path system 2 is correspondingly arranged; the multiple gas transmission pipes 3-7 are used to transmit the mixed gas in the gas storage tank to the gas chamber 3-11, so as to provide uniformity for the sample to be tested Mixed gas atmosphere environment; the vacuum pump 3-5 is used to vacuum the gas mixing tank 3-12; the surface of the optical fiber collector 4 and the sample stage 3-9 are at 90°.
  • the multi-gas mixing spherical gas chamber 3 of the present invention further includes:
  • the quartz window 3-13 is set on the top of the gas chamber 3-11, and has the same normal as the optical fiber collector 4, and is used to transmit the plasma signal generated by the laser ablating the sample to be detected , So that the optical fiber collector 4 receives the optical signal generated during the spreading of the plasma signal.
  • the multi-gas mixing spherical gas chamber 3 of the present invention further includes:
  • the control valve 3-4 is arranged on the pipeline between the gas splitter 3-6 and the gas mixing tank 3-12, and is connected to the controller 8, and is used to control the control generated by the controller 8
  • the command controls the gas flow rate of the mixed gas flowing out of the gas mixing tank 3-12.
  • the multi-gas mixing spherical gas chamber 3 of the present invention further includes:
  • the exhaust valve 3-10 is arranged at the bottom of the air chamber compartment 3-11. When the air pressure in the air chamber compartment 3-11 is higher than the atmospheric pressure, the exhaust valve 3-10 will automatically discharge part of the mixed gas , To keep the air pressure in the air chamber compartment 3-11 stable.
  • FIG. 2 is a top view of the spherical air chamber in the signal enhancement device according to the embodiment of the present invention
  • Figure 3 is a side view of the spherical air chamber in the signal enhancement device according to the embodiment of the present invention, as shown in Figures 2 to 3, the present invention
  • the air chamber 3-11 is a sphere with a diameter of 20 cm, and the top of the sphere is inlaid with the quartz window 3-13 with a light transmittance of more than 99%
  • the quartz window 3-13 is a circle with a diameter of 3 cm
  • a plurality of air inlets 3-8 connected to the gas transmission pipe 3-7 are evenly distributed, and the plurality of air inlets 3-8 are on the same plane.
  • the stage 3-9 and the quartz window 3-13 are parallel; the number of the air inlets 3-8 is the same as the number of the gas transmission pipes 3-7, and a plurality of the gas transmission pipes 3- 7 Insert the air chamber 3-11 through the air inlet 3-8; there is a sample table 3-9 that can be taken out on the lower side 5 cm from the center of the bottom of the sphere, and there is a pull ring on the side for easy pulling out The sample stage 3-9.
  • the exhaust valve 3-10 will automatically discharge part of the mixed gas.
  • Fig. 4 is a schematic diagram of the structure when a signal enhancement device is used in an embodiment of the present invention, as shown in Fig. 4:
  • the instrument parameters include the delay time It is 2 ⁇ s, the integration time is 18 ⁇ s, the distance from the lens to the sample surface is 98mm, and the laser energy is 80mJ.
  • the solid-state pulsed laser 1 is turned on by the controller 8 to generate a 532nm laser, which reaches the surface of the sample to be tested in the gas chamber 3-11 through the optical path system 2, and the laser ablates the sample to be tested to generate plasma.
  • the optical signal generated during the bulk diffusion process is collected by the optical fiber collector 4.
  • the optical fiber collector 4 transfers the optical signal to the spectrometer 5, and after processing by the spectrometer 5, the laser-induced breakdown spectrum information is obtained and transmitted to the spectrum information acquisition software of the controller 8 to obtain LIBS spectrum information .
  • Obtaining the LIBS spectral information of the sample to be tested requires that the focal point of the fiber collector 4 coincides with the focal point generated by the laser passing through the lens in the optical path system 2, and must pass through the quartz window above the air chamber 3-11 3-13. Avoid being blocked by the stainless steel body on the side wall.
  • FIG. 5 is a flowchart of a heavy metal detection method according to an embodiment of the present invention. As shown in FIG. 5, the present invention also provides a heavy metal detection method, which includes:
  • Step S1 Determine the sample to be tested.
  • Step S2 After setting the instrument parameters of the above-mentioned multi-gas hybrid LIBS signal enhancement device, use the above-mentioned multi-gas hybrid LIBS signal enhancement device to detect the sample to be tested to obtain laser-induced breakdown spectrum information; the instrument parameter setting delay time is 2 ⁇ s, integration time 18 ⁇ s, distance from lens to sample surface is 98mm and laser energy is 80mJ.
  • Step S3 Perform standard normal transformation processing on the laser-induced breakdown spectrum information to determine the LIBS spectrum information.
  • Step S4 Establish a multiple linear regression model of emission spectral line intensity-heavy metal content.
  • Step S5 Input the LIBS spectrum information into a multiple linear regression model to determine the true content of heavy metals.
  • the determination of the sample to be tested in the present invention specifically includes:
  • Step S12 Perform stress treatment with multiple gradients of CuCl 2 solution on the plant to be tested ; the CuCl 2 solution for stressing the plant to be tested has 5 gradients, which are 0 ⁇ M, 5 ⁇ M, 30 ⁇ M, 70 ⁇ M, and 100 ⁇ M, respectively.
  • Step S13 Collect the plants to be tested after a set day, and perform washing, drying, grinding, sieving, and tableting treatments to obtain a sample to be tested.
  • the mass of the tableted sample is 0.20 g, and the length, width, and height are 10 ⁇ 10 ⁇ 2 mm.
  • Step S41 Obtain multiple test set samples.
  • Step S42 Use inductively coupled plasma mass spectrometry to measure the true content of heavy metals in each test set sample.
  • Step S43 Use the above-mentioned multi-gas hybrid LIBS signal enhancement device to detect each of the test set samples, and obtain the laser-induced breakdown spectrum information corresponding to each of the test set samples.
  • Step S44 Perform standard normal transformation processing on the laser induced breakdown spectrum information corresponding to each test set sample, and determine the LIBS spectrum information corresponding to each test set sample.
  • Step S45 Use a genetic algorithm to screen the characteristic bands that are correlated with heavy metals in the LIBS spectrum information corresponding to each of the test set samples.
  • Step S46 According to the NIST database, multiple emission spectra of heavy metals are selected from multiple characteristic wavebands.
  • Step S47 using a multiple linear regression method, taking multiple emission spectrum lines of heavy metals as input, and taking the true content of heavy metals in each test set sample as output, establishing a multiple linear regression model of emission spectrum intensity-heavy metal content.
  • the specific method used by the device of the present invention to detect the accumulation of heavy metal copper in rice leaves includes:
  • Step S1 Cultivate rice leaf plants, select the same growing plants and subject them to different CuCl 2 solution stress treatments. After 20 days, collect the samples for cleaning, quickly dry, grind, sieving, and press as the samples to be tested; stress the CuCl 2 of the rice leaf plants There are 5 gradients in the solution, which are 0 ⁇ M, 5 ⁇ M, 30 ⁇ M, 70 ⁇ M and 100 ⁇ M. After washing the rice leaf samples with 20mM Na 2 EDTA and distilled water successively, the samples are dried in an oven at 80°C; in the automatic grinder Fast pulverization, frequency 60Hz, time 80s; the mass of the compressed sample is 0.20g, and the length, width and height are 10 ⁇ 10 ⁇ 2mm.
  • Step S2 After setting the instrument parameters of the signal enhancement device, use the multi-gas hybrid LIBS signal enhancement device to obtain the laser-induced breakdown spectrum data X of the sample to be tested in step S1; the instrument parameters include a delay time of 2 ⁇ s, an integration time of 18 ⁇ s, and a lens to The sample surface distance is 98mm and the laser energy is 80mJ.
  • Step S3 Perform standard normal transformation processing on the laser-induced breakdown spectrum information X to obtain LIBS spectrum information X1.
  • Step S4 Establish a multiple linear regression model of the intensity of the emission spectrum of the sample copper element and the content of the copper element.
  • Step S5 Input the LIBS spectrum information into a multiple linear regression model of the sample copper emission line intensity-copper content to determine the true content of heavy metal copper.
  • Step S4 Establish a multiple linear regression model of the sample copper emission line intensity-copper content, which specifically includes:
  • Step S41 Use inductively coupled plasma mass spectrometry to measure the true content y of heavy metal copper in each test set sample;
  • Step S42 Use genetic algorithm to screen the characteristic band x in the LIBS spectral information X1 corresponding to each test set sample that is correlated with the Cu of rice leaves.
  • Step S43 According to the NIST database, locate two emission spectral lines of copper element from the characteristic band x, and record the spectral lines as CuI 324.87nm and CuI 327.46nm.
  • the present invention has the following advantages:
  • the present invention adds a multi-gas mixing spherical gas chamber, which has the ability to provide a uniform mixed environment atmosphere of multiple gases for the plasma generated by laser ablation of the sample, adjust the mixed gas ratio according to the detection requirement, and change the atmosphere environment where the plasma is located Then enhance the LIBS spectral information and improve the accuracy of heavy metal content determination.
  • the multi-gas mixed LIBS signal enhancement device disclosed in the present invention has the characteristics of no contact with strong acid and alkali reagents, simple and quick operation, low cost and the like.
  • the present invention can control the mixing ratio of multiple gases, and realize the required gas mixing of different ratios.
  • the present invention uses a multi-gas mixed environment atmosphere to enhance LIBS spectral information, thereby improving the accuracy and sensitivity of quantitative detection of heavy metal content.

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Abstract

一种多气体混合LIBS信号增强装置和重金属检测方法，装置包括：固体脉冲激光器(1)、光路系统(2)、多气体混合球形气室(3)、光纤收集器(4)、光谱仪(5)和控制器(8)；光路系统(2)与固体脉冲激光器(1)连接，多气体混合球形气室(3)与光路系统(2)对应设置，光纤收集器(4)与多气体混合球形气室(3)对应设置，光谱仪(5)与光纤收集器(4)连接，控制器(8)分别与光谱仪(5)和固体脉冲激光器(1)连接，光谱仪(5)根据光纤收集器(4)接收的光信号确定激光诱导击穿光谱信息；控制器(8)根据接收的激光诱导击穿光谱信息确定LIBS光谱信息；该装置为激光烧蚀待检测样品产生的等离子体提供多种气体均匀混合环境气氛，能够根据检测需求调节气体输入量和空气比例，从而增强LIBS光谱信息以及提高确定重金属含量的准确性。

Description

一种多气体混合LIBS信号增强装置和重金属检测方法
本申请要求于2020年3月17日提交中国专利局、申请号为202010187094.3、发明名称为“一种多气体混合LIBS信号增强装置和重金属检测方法”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本发明涉及LIBS光谱信息检测技术领域，特别是涉及一种多气体混合LIBS信号增强装置和重金属检测方法。
背景技术
随着工业、农业和城市污染等人类活动，造成环境中重金属含量持续累积。以农业为例，农业生态系统中过量的重金属元素不仅会对作物的生理生化过程产生影响，在一定程度上甚至会抑制作物生长，引起细胞死亡，也会通过食物链的传递进入动物和人体，造成严重的健康问题。因此快速检测农业生态环境如土壤和作物中的重金属含量，有利于判断作物及其接触环境中重金属状况，可为研究植物重金属吸收积累规律提供技术手段，对农业粮食安全监管有重要意义。
传统的重金属检测方法多采用实验室化学检测，样本预处理需要高温高酸环境，人为误差大，成本高，效率低。作为一种有效的金属元素检测技术，激光诱导击穿光谱技术(Laser induced breakdown spectroscopy,LIBS)利用高能激光脉冲烧蚀待测样品，在样品表面瞬间产生具有极高温度和亮度的激光等离子体，等离子体光谱与物质元素一一对应，且有一定的量化关系。LIBS技术具有方便快捷、微痕量、多元素同时检测等优点，已在航天、环境、食品等领域有所应用。
然而相比其他领域，LIBS在农业领域的检测应用更有挑战性。主要是由于土壤、作物和部分农产品的样本成分复杂，差异大，最终形成复杂的基体效应，干扰LIBS检测性能。如何提高LIBS对微量元素的定量分析性能则持续成为研究的热点领域。LIBS信号增强技术则是这个热点领域中的研究重点。等离子体从升温扩展到冷却，产生能级跃迁发射光谱信号，环境气氛的改变会影响激光诱导等离子体随时间的演化机制。有研究 者发现等离子体的状态和其所在的环境气氛有密切的关系，通过改变等离子体所在的气氛环境，最终达到增强LIBS光谱信息的作用，但具体如何利用混合气体环境气氛实现提高LIBS光谱信息并未公开。
发明内容
基于此，本发明的目的是提供一种多气体混合LIBS信号增强装置和重金属检测方法，通过改变等离子体所在的气氛环境进而增强LIBS光谱信息以及提高重金属含量确定的准确性。
为实现上述目的，本发明提供了一种多气体混合LIBS信号增强装置，所述装置包括：
固体脉冲激光器，用于产生激光；
光路系统，与所述固体脉冲激光器连接，用于传递激光；
多气体混合球形气室，与所述光路系统对应设置，用于为待检测样品提供均匀混合气体气氛环境；
光纤收集器，与所述多气体混合球形气室对应设置，用于接收等离子体信号扩散过程中产生的光信号；所述等离子体信号是基于所述激光烧蚀所述待检测样品产生的；
光谱仪，与所述光纤收集器连接，用于根据所述光纤收集器接收的光信号确定激光诱导击穿光谱信息；
控制器，分别与所述光谱仪和所述固体脉冲激光器连接，用于根据接收的所述激光诱导击穿光谱信息确定图谱形式LIBS光谱信息；还用于获取仪器参数，并根据所述仪器参数生成控制指令控制所述固体脉冲激光器产生激光；所述仪器参数包括所述光路系统中透镜到所述待检测样品表面距离和激光能量。
可选的，所述装置还包括：
延时积分发生器，分别与所述控制器和所述光谱仪连接，用于根据所述仪器参数中的延时时间和积分时间控制所述光谱仪的工作时序。
可选的，所述多气体混合球形气室包括：
第一气体储气罐，用于存储氩气；
第二气体储气罐，用于存储氦气；
第三气体储气罐，用于存储氮气；
气体混合罐，通过管路分别与所述第一气体储气罐、所述第二气体储气罐和所述第三气体储气罐连接，用于将氩气、氦气和氮气混合，获得混合气体；
气体分流器，通过管路与所述气体混合罐连接，用于对所述气体混合罐内的所述混合气体进行分流；
带有样品台的气室舱，用于将所述待检测样品放置在所述样品台上，并将所述待检测样品与所述光路系统对应设置；
多根气体传输管，分别与所述气体分流器和所述气室舱连接，用于将所述储气罐内的所述混合气体传输至所述气室舱，从而给所述待检测样品提供均匀混合气体气氛环境；
真空泵，通过管路与所述气体混合罐连接，用于对所述气体混合罐进行抽真空。
可选的，所述多气体混合球形气室还包括：
石英窗口片，设置在所述气室舱的顶部，与所述光纤收集器同一法线，用于透过所述激光烧蚀所述待检测样品产生的等离子体信号，以使所述光纤收集器接收等离子体信号扩散过程中产生的光信号。
可选的，所述多气体混合球形气室还包括：
控制阀，设置在所述气体分流器与所述气体混合罐之间的管路上，与所述控制器连接，用于根据所述控制器生成的控制指令控制所述气体混合罐内混合气体流出的气体流速。
可选的，所述多气体混合球形气室还包括：
排气阀，设置在所述气室舱的底部，当所述气室舱中气压高于大气压时，所述排气阀会自动排放部分混合气体，保持所述气室舱内气压稳定。
可选的，所述气室舱为直径20cm的圆球体，所述圆球体的顶端由所述石英窗口片镶嵌；所述石英窗口片为直径3cm的圆形，圆球体上半侧平均分布多个与所述气体传输管道连接的进气口，多个所述进气口在同一平面上，该平面与所述样品台和所述石英窗口片均平行；所述进气口的个数与所述气体传输管的根数相同，多根所述气体传输管通过所述进气口插入所述气室舱。
本发明还提供一种重金属检测方法，所述方法包括：
确定待检测样本；
利用上述多气体混合LIBS信号增强装置检测所述待检测样本，获得激光诱导击穿光谱信息；
对所述激光诱导击穿光谱信息进行标准正态变换处理，确定LIBS光谱信息；
建立发射谱线强度-重金属含量的多元线性回归模型；
将所述LIBS光谱信息输入多元线性回归模型，确定重金属的真实含量。
可选的，所述建立发射谱线强度-重金属含量的多元线性回归模型，具体包括：
获取多个测试集样本；
采用电感耦合等离子体质谱法测量各测试集样本中重金属的真实含量；
利用上述多气体混合LIBS信号增强装置检测各所述测试集样本，获得各所述测试集样本对应的激光诱导击穿光谱信息；
对各所述测试集样本对应的所述激光诱导击穿光谱信息进行标准正态变换处理，确定各所述测试集样本对应的LIBS光谱信息；
采用遗传算法筛选各所述测试集样本对应的LIBS光谱信息中与重金属有相关性的特征波段；
依据NIST数据库，从多个特征波段中选取多条重金属的发射谱线；
采用多元线性回归法，以多条重金属的发射谱线为输入，以各测试集样本中重金属的真实含量为输出，建立发射谱线强度-重金属含量的多元线性回归模型。
可选的，所述确定待检测样本，具体包括：
挑选长势相同的待检测植株；
对所述待检测植株进行多种梯度CuCl 2溶液胁迫处理；
设定天后收集待检测植株，并进行清洗、烘干、研磨、过筛、压片处理，获得待检测样本。
根据本发明提供的具体实施例，本发明公开了以下技术效果：
本发明提供了一种多气体混合LIBS信号增强装置和重金属检 测方法，所述装置包括：固体脉冲激光器、光路系统、多气体混合球形气室、光纤收集器、光谱仪和控制器；光路系统与固体脉冲激光器连接，多气体混合球形气室与光路系统对应设置，光纤收集器与多气体混合球形气室对应设置，光谱仪与光纤收集器连接，控制器分别与光谱仪和固体脉冲激光器连接，光谱仪根据光纤收集器接收的光信号确定激光诱导击穿光谱信息；控制器根据接收的激光诱导击穿光谱信息确定图谱形式LIBS光谱信息；本发明为激光烧蚀待检测样品产生等离子体提供多种气体均匀混合环境气氛的能力，根据检测需求调节气体的输入量和空气的比例，调节压强，进而增强LIBS光谱信息以及提高重金属含量确定的准确性。
说明书附图
为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动性的前提下，还可以根据这些附图获得其他的附图。
图1为本发明实施例信号增强装置的结构示意图；
图2为本发明实施例信号增强装置中球形气室舱的俯视图；
图3为本发明实施例信号增强装置中球形气室舱的侧视图；
图4为本发明实施例使用信号增强装置时的结构示意图；
图5为本发明实施例重金属检测方法流程图；
其中，1、固体脉冲激光器；2、光路系统；3、多气体混合球形气室；4、光纤收集器；5、光谱仪；6、延时积分发生器；7、导线；8、控制器；3-1、第一气体储气罐；3-2、第二气体储气罐；3-3、第三气体储气罐；3-4、控制阀；3-5、真空泵；3-6、气体分流器；3-7、气体传输管；3-8、进气口；3-9、样品台；3-10、排气阀；3-11、气室舱；3-12、气体混合罐；3-13、石英窗口片。
具体实施方式
下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没 有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
本发明的目的是提供一种多气体混合LIBS信号增强装置和重金属检测方法，通过改变等离子体所在的气氛环境进而增强LIBS光谱信息以及提高重金属含量确定的准确性。
为使本发明的上述目的、特征和优点能够更加明显易懂，下面结合附图和具体实施方式对本发明作进一步详细的说明。
图1为本发明实施例信号增强装置的结构示意图，如图1所示，本发明提供一种多气体混合LIBS信号增强装置，所述装置包括：固体脉冲激光器1、光路系统2、多气体混合球形气室3、光纤收集器4、光谱仪5和控制器8；所述光路系统2与所述固体脉冲激光器1连接，所述多气体混合球形气室3与所述光路系统对应设置，所述光纤收集器4与所述多气体混合球形气室3对应设置，所述光谱仪5通过导线7与所述光纤收集器4连接，所述控制器8通过导线7分别与所述光谱仪5和所述固体脉冲激光器1连接。
所述固体脉冲激光器1用于产生激光；所述光路系统2用于传递激光；所述多气体混合球形气室3用于为待检测样品提供均匀混合气体气氛环境；所述光纤收集器4用于接收等离子体信号扩散过程中产生的光信号；所述等离子体信号是基于所述激光烧蚀所述待检测样品产生的；所述光谱仪5用于根据所述光纤收集器4接收的光信号确定激光诱导击穿光谱信息；所述控制器8用于根据接收的所述激光诱导击穿光谱信息确定图谱形式LIBS光谱信息；还用于获取仪器参数，并根据所述仪器参数生成控制指令控制所述固体脉冲激光器1产生激光；所述仪器参数包括所述光路系统2中透镜到所述待检测样品表面距离和激光能量。
作为一种实施方式，本发明所述装置还包括：
延时积分发生器6，通过导线7分别与所述控制器8和所述光谱仪5连接，用于根据所述仪器参数中的延时时间和积分时间控制所述光谱仪5的工作时序。
作为一种实施方式，本发明所述多气体混合球形气室3包括：第一气体储气罐3-1、第二气体储气罐3-2、第三气体储气罐3-3、气体混合罐3-12、 气体分流器3-6、带有样品台3-9的气室舱3-11、多根气体传输管3-7和真空泵3-5；所述气体混合罐3-12通过管路分别与所述第一气体储气罐3-1、所述第二气体储气罐3-2和所述第三气体储气罐3-3连接，所述气体分流器3-6通过管路与所述气体混合罐3-12连接，所述多根气体传输管3-7分别与所述气体分流器3-6和所述气室舱3-11连接，所述真空泵3-5通过管路与所述气体混合罐3-12连接。
所述第一气体储气罐3-1，用于存储氩气；所述第二气体储气罐3-2，用于存储氦气；所述第三气体储气罐3-3，用于存储氮气；所述气体混合罐3-12用于将氩气、氦气和氮气混合，获得混合气体；所述气体分流器3-6用于对所述气体混合罐3-12内的所述混合气体进行分流；所述带有样品台3-9的气室舱3-11用于将所述待检测样品放置在所述样品台3-9上，并将所述待检测样品与所述光路系统2对应设置；所述多根气体传输管3-7用于将所述储气罐内的所述混合气体传输至所述气室舱3-11，从而给所述待检测样品提供均匀混合气体气氛环境；所述真空泵3-5，用于对所述气体混合罐3-12进行抽真空；所述光纤收集器4与所述样品台3-9表面呈90°。
作为一种实施方式，本发明所述多气体混合球形气室3还包括：
石英窗口片3-13，设置在所述气室舱3-11的顶部，与所述光纤收集器4同一法线，用于透过所述激光烧蚀所述待检测样品产生的等离子体信号，以使所述光纤收集器4接收等离子体信号扩散过程中产生的光信号。
作为一种实施方式，本发明所述多气体混合球形气室3还包括：
控制阀3-4，设置在所述气体分流器3-6与所述气体混合罐3-12之间的管路上，与所述控制器8连接，用于根据所述控制器8生成的控制指令控制所述气体混合罐3-12内混合气体流出的气体流速。
作为一种实施方式，本发明所述多气体混合球形气室3还包括：
排气阀3-10，设置在所述气室舱3-11的底部，当所述气室舱3-11中气压高于大气压时，所述排气阀3-10会自动排放部分混合气体，保持所述气室舱3-11内气压稳定。
图2为本发明实施例信号增强装置中球形气室舱的俯视图，图3为本发明实施例信号增强装置中球形气室舱的侧视图，如图2-图3所示，本 发明所述气室舱3-11为直径20cm的圆球体，所述圆球体的顶端由透光率99％以上的所述石英窗口片3-13镶嵌；所述石英窗口片3-13为直径3cm的圆形，圆球体上半侧平均分布多个与所述气体传输管道3-7连接的进气口3-8，多个所述进气口3-8在同一平面上，该平面与所述样品台3-9和所述石英窗口片3-13均平行；所述进气口3-8的个数与所述气体传输管3-7的根数相同，多根所述气体传输管3-7通过所述进气口3-8插入所述气室舱3-11；距离圆球体底部中心5cm的下侧有一个能够取出的所述样品台3-9，侧面有一个拉环便于拉出所述样品台3-9。当所述气室舱3-11中气压高于大气压时，所述排气阀3-10会自动排放部分混合气体。
图4为本发明实施例使用信号增强装置时的结构示意图，如图4所示：
设置所述仪器参数：先后开启所述固体脉冲激光器1、所述光谱仪5、所述延时积分发生器6后，然后开启所述控制器8，等待仪器稳定；所述仪器参数包括延时时间为2μs、积分时间18μs、透镜到样品表面距离为98mm和激光能量80mJ。
获取均匀氩气、氦气和氮气混合气氛环境：首先打开真空泵3-5，将气体混合罐3-12抽真空；其次打开所述第一气体储气罐3-1、所述第二气体储气罐3-2、所述第三气体储气罐3-3的阀门，流速均设置为2L/min，向所述气体混合罐3-12同时充入氩气、氦气和氮气三种气体，待混合后，打开所述控制阀3-4且流速设置为6L/min，通过气体分流器3-6将混合气体均匀分流为4管道气体通过所述气体传输管3-7输入所述气室舱3-11，待所述气室舱3-11底部排气阀3-10门被自动顶开后，获得可进行实验的均匀氩气、氦气和氮气混合气氛环境。
获取样本LIBS光谱信息：将所述样品台3-9从所述气室舱3-11的底部取出，装置待检测样品后重新插入所述气室舱3-11中。通过所述控制器8开启所述固体脉冲激光器1产生532nm激光，通过所述光路系统2到达所述气室舱3-11中的待检测样品表面，激光烧蚀待检测样品产生等离子体，等离子体扩散过程中产生的光信号被光纤收集器4收集。所述光纤收集器4将光信号转递给所述光谱仪5，经所述光谱仪5处理后获得激光诱导击穿光谱信息并传输给所述控制器8的光谱信息采集软件中，获得LIBS光谱信息。
获取待检测样品的LIBS光谱信息要求光纤收集器4的焦点与激光通过所述光路系统2中的透镜产生的焦点重合，且必须透过所述气室舱3-11上方的所述石英窗口片3-13，避免被侧壁的不锈钢体遮挡信号。
图5为本发明实施例重金属检测方法流程图，如图5所示，本发明还提供一种重金属检测方法，所述方法包括：
步骤S1：确定待检测样本。
步骤S2：设置上述多气体混合LIBS信号增强装置的仪器参数后，利用上述多气体混合LIBS信号增强装置检测所述待检测样本，获得激光诱导击穿光谱信息；所述仪器参数设置延时时间为2μs、积分时间18μs、透镜到样品表面距离为98mm和激光能量80mJ。
步骤S3：对所述激光诱导击穿光谱信息进行标准正态变换处理，确定LIBS光谱信息。
步骤S4：建立发射谱线强度-重金属含量的多元线性回归模型。
步骤S5：将所述LIBS光谱信息输入多元线性回归模型，确定重金属的真实含量。
作为一种实施方式，本发明所述确定待检测样本，具体包括：
步骤S11：挑选长势相同的待检测植株。
步骤S12：对所述待检测植株进行多种梯度CuCl 2溶液胁迫处理；胁迫所述待检测植株的CuCl 2溶液共有5个梯度，分别为0μM，5μM，30μM，70μM和100μM共5个梯度。
步骤S13：设定天后收集待检测植株，并进行清洗、烘干、研磨、过筛、压片处理，获得待检测样本，压片样品质量为0.20g，长宽高为10×10×2mm。
作为一种实施方式，本发明所述建立发射谱线强度-重金属含量的多元线性回归模型，具体包括：
步骤S41：获取多个测试集样本。
步骤S42：采用电感耦合等离子体质谱法测量各测试集样本中重金属的真实含量。
步骤S43：利用上述多气体混合LIBS信号增强装置检测各所述测试集样本，获得各所述测试集样本对应的激光诱导击穿光谱信息。
步骤S44：对各所述测试集样本对应的所述激光诱导击穿光谱信息进行标准正态变换处理，确定各所述测试集样本对应的LIBS光谱信息。
步骤S45：采用遗传算法筛选各所述测试集样本对应的LIBS光谱信息中与重金属有相关性的特征波段。
步骤S46：依据NIST数据库，从多个特征波段中选取多条重金属的发射谱线。
步骤S47：采用多元线性回归法，以多条重金属的发射谱线为输入，以各测试集样本中重金属的真实含量为输出，建立发射谱线强度-重金属含量的多元线性回归模型。
本发明装置用于检测水稻叶片重金属铜积累量的具体方法包括：
步骤S1：栽培水稻叶片植株，挑选长势相同植株进行不同CuCl 2溶液胁迫处理，20天后收集样本进行清洗，快速烘干、研磨、过筛、压片作为待检测样本；胁迫水稻叶片植株的CuCl 2溶液共有5个梯度，分别为0μM，5μM，30μM，70μM和100μM共5个梯度；用20mM的Na 2EDTA和蒸馏水先后清洗水稻叶片样品后，在80℃烘箱中烘干样品；在自动研磨仪进行快速粉碎，频率60Hz，时间80s；压片样品质量为0.20g，长宽高为10×10×2mm。
步骤S2：设置信号增强装置的仪器参数后采用多气体混合LIBS信号增强装置获取步骤S1中待测样本的激光诱导击穿光谱数据X；仪器参数包括延时时间为2μs、积分时间18μs、透镜到样品表面距离为98mm和激光能量80mJ。
步骤S3：对所述激光诱导击穿光谱信息X进行标准正态变换处理，得到LIBS光谱信息X1。
步骤S4：建立样本铜元素发射谱线强度-铜元素含量的多元线性回归模型。
步骤S5：将所述LIBS光谱信息输入样本铜元素发射谱线强度-铜元素含量的多元线性回归模型，确定重金属铜元素的真实含量。
步骤S4：建立样本铜元素发射谱线强度-铜元素含量的多元线性回归模型，具体包括：
步骤S41：采用电感耦合等离子体质谱法测量各测试集样本中重金属 铜元素的真实含量y；。
步骤S42：采用遗传算法筛选各测试集样本对应的LIBS光谱信息X1中与水稻叶片Cu有相关性的特征波段x。
步骤S43：依据NIST数据库，从特征波段x中定位2条铜元素的发射谱线，记录谱线为Cu I 324.87nm和CuI 327.46nm。
步骤S44：采用多元线性回归法，以铜元素发射谱线强度分别以I 324和I 327为输入向量，真实值y为输出向量，建立样本铜元素发射谱线强度-铜元素含量的多元线性回归模型：yd＝0.7506I 327-0.3489I 324-198.5752；相关性达到0.96。
与现有技术相比，本发明具有以下优点：
(1)本发明增加了多气体混合球形气室，具有为激光烧蚀样品产生等离子体提供多种气体均匀混合环境气氛的能力，根据检测需求调节混合气体比例，通过改变等离子体所在的气氛环境进而增强LIBS光谱信息以及提高重金属含量确定的准确性。
(2)本发明公开的多气体混合LIBS信号增强装置具有不接触强酸碱试剂、操作简便快捷、低成本等特点。
(3)本发明能够控制多种气体的混合比例，实现需要的不同比例气体混合。
(4)本发明利用多气体混合环境气氛增强LIBS光谱信息，进而提高定量化检测重金属含量的精度和灵敏性。
(5)利用多气体混合LIBS信号增强装置实现了重金属元素的快速、准确、大批量检测检测。
本说明书中各个实施例采用递进的方式描述，每个实施例重点说明的都是与其他实施例的不同之处，各个实施例之间相同相似部分互相参见即可。
本文中应用了具体个例对本发明的原理及实施方式进行了阐述，以上实施例的说明只是用于帮助理解本发明的方法及其核心思想；同时，对于本领域的一般技术人员，依据本发明的思想，在具体实施方式及应用范围上均会有改变之处。综上所述，本说明书内容不应理解为对本发明的限制。

Claims (10)

  1. 一种多气体混合LIBS信号增强装置，其特征在于，所述装置包括：
    固体脉冲激光器，用于产生激光；
    光路系统，与所述固体脉冲激光器连接，用于传递激光；
    多气体混合球形气室，与所述光路系统对应设置，用于为待检测样品提供均匀混合气体气氛环境；
    光纤收集器，与所述多气体混合球形气室对应设置，用于接收等离子体信号扩散过程中产生的光信号；所述等离子体信号是基于所述激光烧蚀所述待检测样品产生的；
    光谱仪，与所述光纤收集器连接，用于根据所述光纤收集器接收的光信号确定激光诱导击穿光谱信息；
    控制器，分别与所述光谱仪和所述固体脉冲激光器连接，用于根据接收的所述激光诱导击穿光谱信息确定LIBS光谱信息；还用于获取仪器参数，并根据所述仪器参数生成控制指令控制所述固体脉冲激光器产生激光；所述仪器参数包括所述光路系统中透镜到所述待检测样品表面距离和激光能量。
  2. 根据权利要求1所述的多气体混合LIBS信号增强装置，其特征在于，所述装置还包括：
    延时积分发生器，分别与所述控制器和所述光谱仪连接，用于根据所述仪器参数中的延时时间和积分时间控制所述光谱仪的工作时序。
  3. 根据权利要求1所述的多气体混合LIBS信号增强装置，其特征在于，所述多气体混合球形气室包括：
    第一气体储气罐，用于存储氩气；
    第二气体储气罐，用于存储氦气；
    第三气体储气罐，用于存储氮气；
    气体混合罐，通过管路分别与所述第一气体储气罐、所述第二气体储气罐和所述第三气体储气罐连接，用于将氩气、氦气和氮气混合，获得混合气体；
    气体分流器，通过管路与所述气体混合罐连接，用于对所述气体混合罐内的所述混合气体进行分流；
    带有样品台的气室舱，用于将所述待检测样品放置在所述样品台上，并将所述待检测样品与所述光路系统对应设置；
    多根气体传输管，分别与所述气体分流器和所述气室舱连接，用于将所述储气罐内的所述混合气体传输至所述气室舱，从而给所述待检测样品提供均匀混合气体气氛环境；
    真空泵，通过管路与所述气体混合罐连接，用于对所述气体混合罐进行抽真空。
  4. 根据权利要求3所述的多气体混合LIBS信号增强装置，其特征在于，所述多气体混合球形气室还包括：
    石英窗口片，设置在所述气室舱的顶部，与所述光纤收集器同一法线，用于透过所述激光烧蚀所述待检测样品产生的等离子体信号，以使所述光纤收集器接收等离子体信号扩散过程中产生的光信号。
  5. 根据权利要求3所述的多气体混合LIBS信号增强装置，其特征在于，所述多气体混合球形气室还包括：
    控制阀，设置在所述气体分流器与所述气体混合罐之间的管路上，与所述控制器连接，用于根据所述控制器生成的控制指令控制所述气体混合罐内混合气体流出的气体流速。
  6. 根据权利要求3所述的多气体混合LIBS信号增强装置，其特征在于，所述多气体混合球形气室还包括：
    排气阀，设置在所述气室舱的底部，当所述气室舱中气压高于大气压时，所述排气阀会自动排放部分混合气体，保持所述气室舱内气压稳定。
  7. 根据权利要求3所述的多气体混合LIBS信号增强装置，其特征在于，所述气室舱为直径20cm的圆球体，所述圆球体的顶端由所述石英窗口片镶嵌；所述石英窗口片为直径3cm的圆形，圆球体上半侧平均分布多个与所述气体传输管道连接的进气口，多个所述进气口在同一平面上，该平面与所述样品台和所述石英窗口片均平行；所述进气口的个数与所述气体传输管的根数相同，多根所述气体传输管通过所述进气口插入所述气室舱。
  8. 一种重金属检测方法，其特征在于，所述方法包括：
    确定待检测样本；
    利用权利要求1-7任一项所述的多气体混合LIBS信号增强装置检测所述待检测样本，获得激光诱导击穿光谱信息；
    对所述激光诱导击穿光谱信息进行标准正态变换处理，确定LIBS光谱信息；
    建立发射谱线强度-重金属含量的多元线性回归模型；
    将所述LIBS光谱信息输入多元线性回归模型，确定重金属的真实含量。
  9. 根据权利要求8所述的重金属检测方法，其特征在于，所述建立发射谱线强度-重金属含量的多元线性回归模型，具体包括：
    获取多个测试集样本；
    采用电感耦合等离子体质谱法测量各测试集样本中重金属的真实含量；
    利用权利要求1-7任一项所述的多气体混合LIBS信号增强装置检测各所述测试集样本，获得各所述测试集样本对应的激光诱导击穿光谱信息；
    对各所述测试集样本对应的所述激光诱导击穿光谱信息进行标准正态变换处理，确定各所述测试集样本对应的LIBS光谱信息；
    采用遗传算法筛选各所述测试集样本对应的LIBS光谱信息中与重金属有相关性的特征波段；
    依据NIST数据库，从多个特征波段中选取多条重金属的发射谱线；
    采用多元线性回归法，以多条重金属的发射谱线为输入，以各测试集样本中重金属的真实含量为输出，建立发射谱线强度-重金属含量的多元线性回归模型。
  10. 根据权利要求7所述的重金属检测方法，其特征在于，所述确定待检测样本，具体包括：
    挑选长势相同的待检测植株；
    对所述待检测植株进行多种梯度CuCl 2溶液胁迫处理；
    设定天后收集待检测植株，并进行清洗、烘干、研磨、过筛、压片处理，获得待检测样本。
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