CN210090311U

CN210090311U - Aerosol detection aiming device for laser-induced breakdown spectroscopy technology

Info

Publication number: CN210090311U
Application number: CN201920586064.2U
Authority: CN
Inventors: 丁宇; 陈冠宇; 胡悦雯
Original assignee: Nanjing University of Information Science and Technology
Current assignee: Nanjing University of Information Science and Technology
Priority date: 2019-04-26
Filing date: 2019-04-26
Publication date: 2020-02-18
Anticipated expiration: 2029-04-26

Abstract

The utility model relates to an aerosol detection area especially relates to an aerosol detects sighting device for laser-induced breakdown spectroscopy technique, and the device includes: the laser aiming module is a cross two-group scattering laser and a photomultiplier, laser generated by the scattering laser passes through an aerosol tube and is received by the photomultiplier, and the intersection point of the light path of the generated laser is used as a check point; the laser excitation module is focused on the light path cross point of the laser emitted by the two groups of scattering lasers in the laser aiming module so that the aerosol generates plasma; and the spectral signal receiving module is used for detecting the spectral data of the plasma generated by the aerosol. The problem of whether high-energy laser can accurately focus on aerosol particles is solved, the intensity of obtained spectral data is large enough, and processing such as element identification can be carried out.

Description

Aerosol detection aiming device for laser-induced breakdown spectroscopy technology

Technical Field

The invention relates to the field of aerosol detection, in particular to an aerosol detection aiming device for a laser-induced breakdown spectroscopy technology.

Background

The aerosol is a colloid dispersion system formed by dispersing and suspending small solid or liquid particles in a gas medium, and the size of the colloid dispersion system is 0.001-100 mu m. Aerosols are divided into smoke, fog and dust, and may be naturally occurring or artificially formed. It can drift to a long distance along with the air, causing atmospheric pollution and having great influence on the living environment of human beings.

Libs (laser Induced Breakdown spectroscopy), a laser Induced Breakdown spectroscopy technique, focuses ultra-short pulse laser on the surface of a sample to form plasma, and then analyzes the emission spectrum of the plasma to determine the material composition and content of the sample. The energy density of the ultra-short pulse laser is high after the ultra-short pulse laser is focused, and the ultra-short pulse laser can excite a sample in any physical state (solid state, liquid state and gas state) to form plasma, so that the ultra-short pulse laser can be used for detecting aerosol. The technology has the advantages that: the method can simultaneously analyze multiple elements, has simple sample pretreatment, high detection rate, less sample loss and high sensitivity.

Because the core of the LIBS technology is that high-energy laser is focused on the surface of a sample for ablation, how to successfully focus the high-energy laser on the surface of the sample is particularly critical. This is especially true when aerosol detection is performed using LIBS technology. The aerosol is small in volume and gas-shaped, and whether the laser is accurately focused or not is difficult to confirm by naked eyes. In addition, because the LIBS technology has poor repeatability and a strong matrix effect, in an LIBS experiment, the control on the laser incidence direction and the spectrum signal acquisition direction is particularly critical, a plurality of groups of sample data can be obtained by adjusting the laser incidence direction and the spectrum signal acquisition direction, and the accuracy of an algorithm result is improved during data processing.

Disclosure of Invention

The invention aims to provide an aerosol detection aiming device for a laser-induced breakdown spectroscopy technology, which solves the problem of whether high-energy laser can be accurately focused on aerosol particles or not, so that the obtained spectral data has enough intensity and can be used for element identification and other processing.

The present invention is achieved in such a way that,

an aerosol detection targeting device for laser induced breakdown spectroscopy, the device comprising:

the laser aiming module is a cross two-group scattering laser and a photomultiplier, laser generated by the scattering laser passes through an aerosol tube and is received by the photomultiplier, and the intersection point of the light path of the generated laser is used as a check point;

the laser excitation module is focused on the light path cross point of the laser emitted by the two groups of scattering lasers in the laser aiming module so that the aerosol generates plasma;

and the spectral signal receiving module is used for detecting the spectral data of the plasma generated by the aerosol.

Further, the laser excitation module rotates around the cross point, and the spectrum signal receiving module rotates around the cross point.

Furthermore, the aerosol tube is arranged in the transparent hollow rotating shaft, two ends of the rotating shaft are respectively connected with a first rotating base and a second rotating base through rotating bearings, the laser excitation module is arranged on the first rotating base, the spectrum signal receiving module is arranged on the second rotating base, and excitation and detection in different directions are realized through rotation of the first rotating base and the second rotating base around the rotating shaft.

Further, be provided with a dwang on first rotating base and the second rotating base respectively, through the dwang drives first rotating base and second rotating base and rotates round the pivot.

Further, the laser aiming module is arranged in an intermediate layer between the first rotating base and the second rotating base, and the intermediate layer is fixed on the rotating shaft.

Furthermore, the rotating shaft is connected with a positioning module, and the positioning module is used for moving to change the position of the check point.

Furthermore, the positioning module comprises two vertical first transmission belts and a second transmission belt which are respectively driven by a motor, a clamping seat is arranged on each transmission belt, a supporting rod is connected with each clamping seat in a threaded manner and fixed on the rotating shaft through the other end of the supporting rod, the supporting rods can be driven to move in a self-adaptive threaded manner when the clamping seats move, and two-axis scanning can be carried out in the horizontal direction at the detection points.

Compared with the prior art, the invention has the beneficial effects that: the method utilizes the laser-induced breakdown spectroscopy technology to detect the aerosol, and has the advantages of simultaneous identification of multiple elements and no need of sample pretreatment. And a two-dimensional structure design is adopted to accurately focus the pulse laser to the aerosol, so that the hit rate and hit efficiency of the pulse laser are greatly increased. Meanwhile, the sample can be excited from different directions, and spectral data can be acquired from different directions of the plasma, so that the problem of poor repeatability of the LIBS technology is greatly reduced, and the accuracy of detection is improved.

Drawings

FIG. 1 is a schematic diagram of the general structure of the present invention;

FIG. 2 is a schematic diagram of the laser targeting module of FIG. 1;

FIG. 3 is a schematic diagram of the laser excitation module of FIG. 1;

FIG. 4 is a schematic diagram of the structure of the spectral acceptance module of FIG. 1;

FIG. 5 is a schematic structural diagram of the orientation module of FIG. 1;

wherein the reference numbers in the figures are: 1. the laser spectrometer comprises a laser excitation module, 2, a laser aiming module, 3, a spectral signal receiving module, 4, a positioning module, 5 and a pulse laser, wherein A is a rotating shaft, 6, a first rotating base, 7, a scattering laser group, 8, a photomultiplier group, 9, a spectrometer CCD, 10, a second rotating base, 11, an aerosol tube, 12, a detection point, 13, a first scattering laser, 14, a second scattering laser, 15, a first photomultiplier, 16, a second photomultiplier, 17, a first rotating rod, 18, a second rotating rod, 19, a first motor, 20, a second motor, 21, a first conveying belt, 22, a second conveying belt, 23, a first clamping seat, 24, a second clamping seat, 25, a first supporting rod, 26 and a second supporting rod.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

As shown in fig. 1, an aerosol detection aiming device for laser-induced breakdown spectroscopy includes a laser aiming module 2, a laser excitation module 1, a spectral signal receiving module 3, and a positioning module 4.

The laser aiming module, the laser excitation module and the spectrum signal receiving module are respectively arranged on a rotating shaft A from top to bottom in spatial position and are all in coaxial ring structures, and the laser excitation module 1 and the spectrum signal receiving module 3 can rotate around a shaft.

The rotating shaft A is connected with the positioning module 4, and the rotating shaft can drive the laser aiming module, the laser excitation module and the spectral signal receiving module to move along two axes in the horizontal direction through controlling the positioning module 4, so that two-axis scanning can be carried out on a detection point in the horizontal direction.

Laser aims module 2, laser excitation module 1 and spectral signal receiving module 3 and connects through a diameter is 150 ~ 200 mm's pivot A, divide into the three-layer altogether in the pivot, and the first layer is laser excitation module, and the second floor is laser and aims the module, and the third layer is spectral signal receiving module. The second layer is a fixed layer, and the first layer and the third layer can rotate through the rotating base. The thickness of each layer is determined by the volume of the detection device mounted on the shaft. The rotating shaft is made of transparent materials or a support structure is arranged between every two layers. The gas rubber tube is arranged in the rotating shaft.

As shown in fig. 2, which is a schematic diagram of a laser aiming module, a detection device is composed of a scattering laser group 7 and a photomultiplier group 8, and the two groups include a first scattering laser 13 corresponding to a first photomultiplier 15, a second scattering laser 14 corresponding to a second photomultiplier 16, and the two groups form a vertical 90 ° structure and are fixed on a disk in the middle layer, and the disk is fixedly connected with a rotating shaft. And the intersection points of the light paths of the laser emitted by the two groups of scattering lasers in the laser aiming module are detection points 12. The scattering laser continuously emits laser to the photomultiplier, and when passing through the aerosol, the aerosol particles shield the laser, so that the photomultiplier cannot receive the laser and generate light pulses. Since the peak-to-peak voltage of the electrical pulse needs to reach 5V before the pulse laser can be successfully triggered, the peak-to-peak value of the optical pulse needs to be large enough, that is, the shielded area of the laser is large enough, that is, the aerosol concentration is large enough, before the pulse laser can be successfully triggered. The photomultiplier tube converts the light pulses into electrical pulses.

The switching time of the photomultiplier tube was chosen to be 36 μ s, and the aerosol particles flowed a negligible distance in the response time. And the intersection point of the laser light paths formed by the two groups of scattering lasers and the photomultiplier, namely a detection point. When the electric pulses generated by the two groups of photomultiplier tubes are large enough, aerosol particles with high enough concentration are shown at the detection point, and at the moment, the laser excitation module is started to emit laser pulses to focus on the detection point to generate plasma.

As shown in fig. 3, which is a schematic view of a laser excitation module, the laser excitation module includes a pulse laser 5 and a focusing lens, the pulse laser 5 is fixed on a first rotating base 6, and laser emitted by the pulse laser 5 passes through the focusing lens and is always at a detection point position. The first rotating rod 17 is fixed on the first rotating base 6, the first rotating base 6 is driven to rotate around the rotating shaft through the first rotating rod 17, and the function of exciting aerosol particles from different directions can be achieved by using the structure.

As shown in fig. 4, which is a schematic diagram of a spectrum signal receiving module, the spectrum signal receiving module includes a spectrometer CCD9, a fiber optic probe of the spectrometer CCD9 is fixed to the second rotary base 10, the second rotary base 10 can be rotated by the second rotating rod 18, and the fiber optic is always opposite to the detection point to perform spectrum detection on the plasma. The structure can be used for detecting plasmas from different directions.

Fig. 5 is a schematic diagram of the positioning module. The positioning module is connected with the rotating shaft and drives the rotating shaft to move horizontally. The diameter of the aerosol tube 11 matched with the invention in the embodiment is 50mm (therefore, the movable range of the double-shaft motor in the positioning module is a square area with the side length of 60mm, which can meet the detection requirement), the structure is that the first motor 19 and the second motor 20 control the horizontal two-shaft motion, respectively transmit through the first transmission belt 21 and the second transmission belt 22, respectively fix on the first transmission belt 21 and the second transmission belt 22 through the first clamping seat 23 and the second clamping seat 24, respectively, are in threaded connection with the first clamping seat and the second clamping seat through the first support rod 25 and the second support rod 26, respectively, the movement of the clamping seat can be in self-adaptive threaded movement, the two support rods are fixed on the rotating shaft, the threaded shaft connected with the support rods is arranged in the center of the clamping seat, when the support rods move towards or depart from the clamping seat, the support rods rotate through the clamping seat by using the rotation of the threaded shaft, the self-adaptive function with the supporting rod is achieved, and free movement in one direction and calibration in the other direction are guaranteed. The conveying belt is driven by the two motors to drive the clamping seat to control the change of the horizontal position of the rotating shaft, the rotating shaft connected with the laser aiming module, the laser excitation module and the spectrum signal receiving module can be driven to move by controlling the rotation of the motors, so that the positions of the detection points are changed, and aerosol particles can be captured more accurately.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims

1. An aerosol detection aiming device for laser induced breakdown spectroscopy, the device comprising:

2. The aiming device of claim 1, wherein the laser excitation module rotates about the intersection point and the spectral signal receiving module rotates about the intersection point.

3. The aiming device as claimed in claim 1 or 2, wherein the aerosol tube is arranged in a transparent inner hollow rotating shaft, the two ends of the rotating shaft are respectively connected with a first rotating base and a second rotating base through rotating bearings, the laser excitation module is arranged on the first rotating base, the spectral signal receiving module is arranged on the second rotating base, and excitation and detection in different directions are realized through rotation of the first rotating base and the second rotating base around the rotating shaft.

4. The aiming device as recited in claim 3, wherein the first and second rotating bases are respectively provided with a rotating rod, and the first and second rotating bases are driven to rotate around the rotating shaft by the rotating rod.

5. The aiming device of claim 3, wherein the laser aiming module is arranged in an intermediate layer between the first rotating mount and the second rotating mount, said intermediate layer being fixed to the shaft.

6. The aiming device as recited in claim 3, wherein the pivot is connected to a positioning module, and the movement is accomplished by the positioning module to change the position of the inspection point.

7. The aiming device as claimed in claim 6, wherein the positioning module comprises two vertical first and second belts, each driven by a motor, a holder is disposed on each belt, a rod is screwed on each holder, and fixed on the rotating shaft through the other end of the rod, the holder is movable to drive the rod to move adaptively through screw threads, so that two-axis scanning can be performed horizontally at the detection point.