Laser induced breakdown spectroscopy enhanced detection device and detection method thereof

Abstract

The present invention relates to a laser induced breakdown spectrum enhancement detection device and a detection method thereof, which solves the defect of low sensitivity of laser induced breakdown spectrum compared with the prior art. The present invention includes a laser excitation system and a spectrum collection system. The light beam output by the laser excitation system is shaped into a linear light beam by a beam shaper, and also includes a spectrum enhancement component. The spectrum enhancement component includes a micro-focusing lens array and a micro-cavity. The linear light beam is divided into a plurality of focal points by the micro-focusing lens array and forms a focusing line array on the surface of the sample to be measured after passing through the micro-cavity. The present invention uses a spectrum enhancement component to integrate dual-pulse excitation, linear excitation and cavity confinement, and is assisted by an inert gas environment, thereby improving the accuracy of laser breakdown spectrum measurement and improving the detection sensitivity and accuracy of laser induced breakdown spectroscopy technology.

Description

Technical Field

[0001] The invention relates to the technical field of spectral equipment, in particular to a laser induced breakdown spectrum enhancement detection device and a detection method thereof. Background Art

[0002] At present, environmental pollution problems are becoming increasingly prominent, especially heavy metal pollution. Mining, metal smelting, discharge of industrial "three wastes", irrational application of pesticides and fertilizers, etc., have caused a large amount of heavy metals to enter the soil and water environment through various channels. Heavy metals are difficult to degrade and easy to enrich in the environment. They are also highly concealed and toxic. They can enter the human body through the food chain and cause great harm to human health. Accurate detection of heavy metal content in the environment is the basis for environmental pollution prevention and control. However, the composition and form of heavy metal pollutants in the environment are easily affected by environmental factors. Therefore, the on-site rapid and accurate analysis of heavy metal pollutants is of great scientific significance for the pollution assessment of heavy metals in the environment, the analysis of pollution processes, and the guarantee of regional environmental quality and safety.

[0003] Traditional heavy metal analysis methods include atomic absorption, inductively coupled plasma mass spectrometry, X-ray fluorescence, atomic fluorescence and other methods. These methods are highly accurate, but have problems such as cumbersome sample pretreatment and complex operation, and cannot be analyzed on site.

[0004] Laser-induced breakdown spectroscopy has attracted much attention in the field of rapid in-situ detection of heavy metal pollutants due to its advantages such as simple sample preparation, convenient operation, fast analysis speed, and in-situ detection. However, due to the complexity of the physical process of laser-matter interaction, its quantitative analysis still faces huge challenges. The main reasons are: 1. The matrix of environmental samples is complex, and the composition of samples from different regions may be very different; 2. The sensitivity of laser-induced breakdown spectroscopy detection is not high enough (ppm level), and the actual detection of heavy metal pollutants needs to reach the sub-ppm level.

[0005] The existence of these objective factors directly affects the accuracy and development of laser-induced breakdown spectroscopy analysis of heavy metal pollutants in the environment. Therefore, how to design a detection device that can enhance laser-induced breakdown spectroscopy has become a technical problem that needs to be solved urgently. Summary of the invention

[0006] The purpose of the present invention is to solve the defect of low sensitivity of laser induced breakdown spectroscopy in the prior art and to provide a laser induced breakdown spectroscopy enhanced detection device and a control method thereof to solve the above problem.

[0007] In order to achieve the above object, the technical solution of the present invention is as follows:

[0008] A laser induced breakdown spectrum enhanced detection device comprises a laser excitation system and a spectrum collection system. The light beam output by the laser excitation system is shaped into a linear light beam by a beam shaper.

[0009] It also includes a spectrum enhancement component, which includes a micro-focusing lens array and a micro-cavity. The line light beam is divided into a plurality of focus points by the micro-focusing lens array and forms a focus line array on the surface of the sample to be measured after passing through the micro-cavity.

[0010] The micro cavity is a semi-cylinder, and a front slit groove, an upper slit groove and a rear slit groove are equally spaced on the arc surface of the micro cavity, the upper slit groove is located at the top of the micro cavity, the front slit groove and the rear slit groove are respectively located on both sides of the upper slit groove, a transparent glass is fixedly installed in the upper slit groove, and a spectrum collecting lens is fixedly installed in the front slit groove and the rear slit groove, and the focus point forms a focusing line array through the transparent glass of the micro cavity and focuses on the sample to be tested;

[0011] The spectrum collection system comprises two spectrum collection lenses, a spectrometer and a detector. The two spectrum collection lenses are connected to the spectrometer through optical fibers. The spectrometer transmits the optical signal after the collected light beam is split to the detector.

[0012] It also includes a three-dimensional translation stage A and a three-dimensional translation stage B, wherein the micro cavity is mounted on the three-dimensional translation stage A, and the sample to be measured is mounted on the three-dimensional translation stage B.

[0013] The laser excitation system includes a laser driver A and a laser driver B. The laser driver A is connected to the laser A, and the laser driver B is connected to the laser B. The light beam of the laser A is output after passing through a reflector and a beam of the laser B together through a beam combining mirror. The control signal output ends of the delayed pulse generator and the laser controller are connected to the control signal input ends of the laser driver A and the laser driver B. The control signal output end of the spectrometer is connected to the control signal input end of the delayed pulse generator.

[0014] The beam shaper is a cylindrical mirror, the micro focusing lens array is a micro plano-convex lens linear array, the number of focusing points is 5, 10, 20, 30 or 40, and the detector is a CCD, ICCD or sCMOS detector.

[0015] Inert gas access holes are provided on the micro cavity at the front slit through groove, the upper slit through groove and the rear slit through groove.

[0016] A detection method of a laser induced breakdown spectroscopy enhanced detection device comprises the following steps:

[0017] Flushing the micro-cavity: Inert gas is introduced into the micro-cavity through the inert gas access hole to flush the front slit groove, the upper slit groove and the rear slit groove of the micro-cavity, and the cavity is kept in an inert gas environment;

[0018] The emission of line beam signal: the spectrometer triggers the delayed pulse generator, which controls the laser driver A and laser driver B to emit pulsed laser at intervals. The laser beam passes through the beam shaper to become a line pulse light source, and then passes through the micro-focusing lens array and the transparent glass of the micro-cavity to focus on the sample surface, forming a line focus.

[0019] Plasma collection: Plasma generated by the micro-cavity confinement is excited at multiple points on the sample surface, and the two spectrum collection lenses of the micro-cavity collect the generated plasma spectrum;

[0020] Adjustment of the three-dimensional translation stage: adjust the three-dimensional translation stage A and the three-dimensional translation stage B to change the distance between the sample under test and the micro-cavity, so that the emission spectrum intensity of the sample under test is maximized;

[0021] Acquisition of test data: The plasma spectrum is transmitted to the data processing system through the spectrometer to obtain the element concentration in the tested sample.

[0022] Beneficial Effects

[0023] Compared with the prior art, the laser induced breakdown spectroscopy enhanced detection device and detection method of the present invention integrate dual pulse excitation, line excitation and cavity confinement by using a spectrum enhancement component, and assisted by an inert gas environment, thereby improving the accuracy of laser breakdown spectroscopy measurement and improving the detection sensitivity and detection accuracy of laser induced breakdown spectroscopy technology.

[0024] The present invention adopts a beam shaper to convert a point light source into a line light source, and uses a micro linear array focusing lens to focus and excite the sample, thereby enhancing the contact points between the excitation light source and the sample to be measured and focusing the points in multiple points, thereby exciting multiple points to generate line plasma with high excitation efficiency, enhancing the spectral signal, and thus improving the accuracy of the measurement results of the laser induced breakdown spectroscopy.

[0025] At the same time, the plasma generated by the micro-cavity confinement and the shock wave generated by the plasma plume are reflected back to the plasma region by the cavity wall, causing the plasma to be reheated, which can improve the excitation conditions and atomization of the sample under test; the plasma spectrum is collected on both sides using two spectral acquisition systems, which further improves the spectral signal and thus improves the accuracy of laser breakdown spectroscopy measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is the structural connection principle diagram of the present invention;

[0027] Figure 2It is a schematic diagram of the line excitation principle involved in the present invention;

[0028] Figure 3 It is a schematic diagram of the micro-cavity structure involved in the present invention;

[0029] Figure 4 This is a flow chart of the detection method involved in the present invention;

[0030] Among them, 1-micro cavity, 2-upper slit groove, 3-front slit groove, 4-rear slit groove. DETAILED DESCRIPTION

[0031] In order to have a further understanding and recognition of the structural features and the effects achieved by the present invention, a preferred embodiment and accompanying drawings are used for detailed description as follows:

[0032] like Figure 1 As shown, the laser induced breakdown spectrum enhancement detection device described in the present invention includes a laser excitation system and a spectrum collection system. The light beam output by the laser excitation system is shaped into a linear beam by a beam shaper. In order to produce a spectrum enhancement effect, a spectrum enhancement component is specially designed. The spectrum enhancement component includes a micro-focusing lens array and a micro-cavity 1. The linear beam is divided into a plurality of focal points by the micro-focusing lens array and forms a focusing line array on the surface of the sample to be tested after passing through the micro-cavity 1.

[0033] In practical applications, the biggest technical difficulty lies in how to improve the spectral effect. Here, we consider integrating dual-pulse excitation, line excitation and cavity confinement through experiments, assisted by an inert gas environment, and realize the improvement of the laser breakdown spectrum through the joint cooperation of the three components at the emission end (laser excitation system), the focusing end (microcavity) and the collection end (spectral collection system). Therefore, the spectral signal is enhanced through the joint cooperation of dual laser delayed triggering, microcavity and dual spectrum collection lenses.

[0034] like Figure 3 As shown, the micro cavity 1 is a semi-cylinder, and a front slit groove 3, an upper slit groove 2 and a rear slit groove 4 are equally spaced on the arc surface of the micro cavity 1. The upper slit groove 2 is located at the top of the micro cavity 1, and a transparent glass is fixedly installed in the upper slit groove 2. Spectral collecting lenses are fixedly installed in the front slit groove 3 and the rear slit groove 4. The focusing point forms a focusing line array through the transparent glass of the micro cavity 1 and focuses on the sample to be measured.

[0035] The spectrum collection system includes two spectrum collection lenses, a spectrometer and a detector. The two spectrum collection lenses are connected to the spectrometer through optical fibers. The spectrometer transmits the optical signal after the collected light beam is split to the detector. Collecting plasma signals from both sides of the cavity at the same time can enhance the collected spectrum signal.

[0036] In order to further realize the enhancement of laser induced breakdown spectrum, the laser excitation system includes laser driver A and laser driver B. Laser driver A is connected to laser A, and laser driver B is connected to laser B. The light beam of laser A is output after passing through a reflector and a beam combiner together with the light beam of laser B. The control signal output ends of the delay pulse generator and the laser controller are respectively connected to the control signal input ends of laser driver A and laser driver B. The control signal output end of the spectrometer is connected to the control signal input end of the delay pulse generator. The two lasers are co-linearly delayed and triggered. The laser pulse of the first laser generates a plasma signal, and the laser pulse of the second laser reheats the plasma signal to increase the intensity of the plasma signal.

[0037] In order to facilitate practical use, a three-dimensional translation stage A and a three-dimensional translation stage B can also be designed, the micro cavity 1 is mounted on the three-dimensional translation stage A, and the sample to be measured is mounted on the three-dimensional translation stage B to achieve automatic control. At the same time, the beam shaper can be a cylindrical mirror, the micro focusing lens array can be a micro plano-convex lens linear array, and the number of focusing points is 5, 10, 20, 30 or 40, and the detector can be a CCD, ICCD or sCMOS detector.

[0038] To facilitate cleaning of the micro cavity 1, inert gas access holes may be provided at the front slit groove 3, the upper slit groove 2 and the rear slit groove 4 on the micro cavity 1, and argon gas may be used to clean the cavity and exhaust the air in the cavity to maintain an inert gas environment in the cavity.

[0039] like Figure 4 As shown, a detection method of a laser induced breakdown spectroscopy enhanced detection device is also provided. First, the cavity is flushed with inert gas and the inert gas environment is maintained; then the spectrometer triggers the delayed pulse generator, which controls the two lasers to emit pulsed lasers at a certain interval, which pass through the beam shaper to become a linear pulse light source, and then focus on the sample surface through a micro-line lens array to form a linear focus, excite and generate multi-point plasma, and the micro-cavity 1 constrains the generated plasma. Two spectrum collection systems collect the generated plasma spectrum from two sides; the three-dimensional translation stage A and the three-dimensional translation stage B are adjusted to change the distance between the sample and the micro-cavity 1 so that the sample emission spectrum intensity is maximized; finally, the data is processed by the data processing system to obtain the element concentration in the sample being tested. After each sample is tested, the cavity is flushed with inert gas and the next test is performed.

[0040] The specific steps are as follows:

[0041] The first step is flushing the micro chamber 1 : inert gas is introduced into the micro chamber 1 through the inert gas access hole to flush the front slit channel 3 , the upper slit channel 2 and the rear slit channel 4 of the micro chamber 1 .

[0042] The second step is the issuance of wiring harness signals: Figure 2 As shown, the spectrometer triggers the delayed pulse generator, and the delayed pulse generator controls the laser driver A and the laser driver B to emit pulsed lasers at intervals, which pass through the beam shaper to become a linear pulse light source (linear beam), and then pass through the micro linear lens array and the transparent glass of the micro cavity 1 to focus on the sample surface, forming a linear focus (focusing linear array).

[0043] The third step is plasma collection: the plasma generated by excitation and confinement in the micro-cavity 1 is generated at multiple points, and the two spectrum collection lenses of the micro-cavity 1 collect the generated plasma spectrum.

[0044] Step 4: Adjustment of the three-dimensional translation stage: adjust the three-dimensional translation stage A and the three-dimensional translation stage B to change the distance between the sample under test and the micro-cavity 1 so as to maximize the emission spectrum intensity of the sample under test.

[0045] The fifth step is to obtain the detection data: the plasma spectrum is transmitted to the data processing system through the spectrometer to obtain the element concentration in the tested sample.

[0046] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. A laser induced breakdown spectroscopy enhanced detection device, comprising a laser excitation system and a spectrum collection system, wherein the light beam output by the laser excitation system is shaped into a linear light beam by a beam shaper, and characterized in that: It also includes a spectrum enhancement component, the spectrum enhancement component including a micro-focusing lens array and a micro-cavity (1), the line light beam is divided into a plurality of focus points by the micro-focusing lens array, and then forms a focus line array on the surface of the sample to be measured after passing through the micro-cavity (1); The micro cavity (1) is a semi-cylindrical body, and a front slit groove (3), an upper slit groove (2) and a rear slit groove (4) are equally spaced on the arc surface of the micro cavity (1), the upper slit groove (2) is located at the top of the micro cavity (1), the front slit groove (3) and the rear slit groove (4) are respectively located on both sides of the upper slit groove (2), a transparent glass is fixedly installed in the upper slit groove (2), and a spectrum collecting lens is fixedly installed in the front slit groove (3) and the rear slit groove (4), and the focusing point forms a focusing line array through the transparent glass of the micro cavity (1) and focuses on the sample to be measured; The spectrum collection system includes two spectrum collection lenses, a spectrometer and a detector. The two spectrum collection lenses are connected to the spectrometer through optical fibers. The spectrometer transmits the optical signal after the collected light beam is split to the detector. The laser excitation system includes a laser driver A and a laser driver B, wherein the laser driver A is connected to the laser A, and the laser driver B is connected to the laser B. The light beam of the laser A is transmitted through a reflector and the light beam of the laser B is transmitted through a beam combining mirror to output a light beam, and the control signal output ends of the delay pulse generator and the laser controller are connected to the control signal input ends of the laser driver A and the laser driver B, and the control signal output end of the spectrometer is connected to the control signal input end of the delay pulse generator; The micro cavity (1) is provided with inert gas access holes at the front slit through groove (3), the upper slit through groove (2) and the rear slit through groove (4).

2. The laser induced breakdown spectroscopy enhanced detection device according to claim 1, characterized in that: It also includes a three-dimensional translation stage A and a three-dimensional translation stage B, wherein the micro cavity (1) is mounted on the three-dimensional translation stage A, and the sample to be measured is mounted on the three-dimensional translation stage B.

3. The laser induced breakdown spectroscopy enhanced detection device according to claim 1, characterized in that: The beam shaper is a cylindrical mirror, the micro focusing lens array is a micro plano-convex lens linear array, the number of focusing points is 5, 10, 20, 30 or 40, and the detector is a CCD, ICCD or sCMOS detector.

4. The detection method of the laser induced breakdown spectroscopy enhanced detection device according to claim 3, characterized in that: The following steps are involved: 41) Flushing the micro cavity (1): Inert gas is introduced into the micro cavity (1) through the inert gas access hole to flush the front slit groove (3), the upper slit groove (2) and the rear slit groove (4) of the micro cavity (1), so that the cavity maintains an inert gas environment; 42) The emission of the line beam signal: the spectrometer triggers the delayed pulse generator, which controls the laser driver A and the laser driver B to emit pulsed lasers at intervals. The pulsed lasers are then emitted through the beam shaper to become line pulse light sources. The line pulses are then focused on the sample surface through the micro focusing lens array and the transparent glass of the micro cavity (1), forming a line focus. 43) Collection of plasma: plasma is generated at multiple points on the sample surface and is confined by the micro-cavity (1). The two spectrum collection lenses of the micro-cavity (1) collect the generated plasma spectrum; 44) Adjustment of the three-dimensional translation stage: Adjust the three-dimensional translation stage A and the three-dimensional translation stage B to change the distance between the sample under test and the micro-cavity (1) so that the emission spectrum intensity of the sample under test is maximized; 45) Acquisition of test data: The plasma spectrum is transmitted to the data processing system through the spectrometer to obtain the element concentration in the sample being tested.

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