Optical detection device, soil element detector and soil element detection method

Abstract

The invention provides an optical detection device, a soil element detector and a soil element detection method. The device is characterized in that a laser beam expanding and collimating system performs beam expanding and collimating on laser emitted by a laser and inputs the laser into a multiplexing folding light path system; the multiplexing folding light path system carries out light beam folding on the laser subjected to beam expansion and collimation to obtain folding system emergent laser, and the folding system emergent laser is input into the surface scanning light path system; the surface scanning light path system focuses laser emitted by the folding system on a surface scanning target surface window to generate plasma; the spectral signal acquisition light path system acquires signal light radiated by the plasma; and the imaging system is used for imaging the window of the surface scanning target surface window on the CMOS camera. According to the device, through the design of a multi-stage optical system, the functions of laser beam expanding, collimation, folding, focusing, signal acquisition and the like are modularized, and each module is independently optimized to improve the stability of the whole device, so that the stability of data is improved, rapid and accurate scanning type detection on a to-be-detected surface is realized, and the anti-disturbance capability is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of rapid element detection, and in particular to an optical detection device, a soil element detector and a soil element detection method. Background Art

[0002] Portable laser induced breakdown spectroscopy technology is also known as portable LIBS (Laser Induced Breakdown Spectroscopy, LIBS) technology or portable laser probe technology. It is an integrated and miniaturized LIBS technology that has gradually evolved from the continuous development of traditional LIBS technology. The principle of LIBS technology is to focus high-energy-density laser pulses on the surface of the target material of the sample to be tested, thereby ablating and exciting the generation of plasma. During the cooling and expansion of the laser-induced plasma, the spectrum generated by the plasma radiation is collected using a light collection system, a spectrometer, and a detector. These spectral signals are then analyzed to obtain the type and content information of each element contained in the sample to be tested.

[0003] The portable LIBS soil element detection instrument has a broad application space in the soil element detection industry, greatly shortening the detection cycle and effectively promoting the rapid development of smart agriculture (big data management and control).

[0004] However, the portable LIBS soil element detection instruments currently available have poor anti-disturbance capabilities in practical applications and are greatly affected by environmental factors. Summary of the invention

[0005] The present invention provides an optical detection device, a soil element detector and a soil element detection method, which are used to solve the defects of the portable LIBS soil element detection instrument introduced in the prior art in that the instrument has poor anti-disturbance ability and is greatly disturbed by environmental factors in practical applications.

[0006] The present invention provides an optical detection device, including a laser beam expansion and collimation system, a multiplexing and folding optical path system, an imaging system, a surface scanning optical path system, and a spectral signal collection optical path system; The laser beam expansion and collimation system expands and collides the laser light emitted by the laser and then inputs the laser light into the multiplexed folded optical path system; The multiplexed folded optical path system folds the laser beam after beam expansion and collimation to obtain the folded system output laser, and inputs the folded system output laser into the surface scanning optical path system; The surface scanning optical path system focuses the laser emitted by the folding system onto the surface scanning target window to generate plasma; The spectral signal collection optical path system collects the signal light radiated by the plasma; The imaging system images the window of the surface scanning target surface window on a CMOS camera.

[0007] According to an optical detection device provided by the present invention, the laser beam expansion and collimation system is provided with a variable aperture, a plano-concave lens and a first plano-convex lens in sequence along the incident direction of the incident laser; The variable iris adjusts the energy of the laser; The plano-concave lens and the first plano-convex lens expand and collimate the adjusted laser.

[0008] According to an optical detection device provided by the present invention, the multiplexed folded optical path system includes a half-inch laser line reflector, a dichroic mirror and a one-inch laser line reflector; The half-inch laser line reflector transmits the expanded and collimated laser horizontally; The lens of the dichroic mirror reflects laser light and transmits visible light, wherein the transmitted visible light includes illumination light and imaging light; The one-inch laser line reflector performs beam folding on the expanded and collimated laser to obtain the folded system output laser.

[0009] According to an optical detection device provided by the present invention, the surface scanning optical path system is provided with a laser scanning galvanometer assembly, a second plano-convex lens, a third plano-convex lens and a surface scanning target window in sequence along the incident direction of the incident laser; A focusing lens group performs laser surface scanning in the surface scanning target surface window; the focusing lens group includes a second plano-convex lens and a third plano-convex lens; The surface scanning target surface window is installed with quartz glass, and the scanning target surface is a square target surface, and the size of the square target surface is adjustable.

[0010] According to an optical detection device provided by the present invention, the imaging system is provided with a field illumination light source, a first biconvex lens, a beam splitter, a second biconvex lens and a CMOS camera in sequence along the incident direction of the incident laser; The field of view illumination light source generates light that illuminates the surface scanning target window, and the field of view illumination light source controls the illumination time through a circuit switch; The first biconvex lens converts the light emitted by the field illumination light source into parallel light; The beam splitter reflects the parallel light into the multiplexed folded optical path system; The second biconvex lens collects imaging light from the surface scanning target window; The CMOS camera displays the imaging light.

[0011] According to an optical detection device provided by the present invention, the spectral signal collection optical path system includes a fourth plano-convex lens and an off-axis parabolic reflector; The surface scanning target surface window is located between the focus of the fourth plano-convex lens and the fourth plano-convex lens, and all signal lights radiated by the plasma between the focus and the edge light of the fourth plano-convex lens are collected; The off-axis parabolic reflector collects the signal light.

[0012] The present invention also provides a soil element detector, comprising the above optical detection device.

[0013] A soil element detector provided by the present invention is characterized by further comprising a laser, a spectrometer, an embedded main control board and a sensor; The laser emits laser light; The optical detection device generates plasma by scanning and ablating the detection surface of soil at different detection depths through the laser, and collects the signal light radiated by the plasma; The spectrometer converts the spectral signal obtained by the signal light transmission into spectral data; The sensor collects location information and environmental information of the soil; The embedded main control board is connected to the spectrometer and the sensor respectively, and is used to display the position information and the environmental information, as well as the soil element composition and soil element content corresponding to the spectral data.

[0014] The present invention also provides a soil element detection method, comprising: During the operation of the soil element detector, a spectral signal emitted by the plasma is received, and the spectral signal is converted into spectral data. The plasma is obtained by a laser emitting a laser to the soil to be tested by the soil element detector. Based on the spectral data, the element composition and element content of the soil corresponding to the soil to be tested are determined.

[0015] According to a soil element detection method provided by the present invention, determining the element composition and element content of the soil corresponding to the soil to be tested based on the spectral data includes: Performing image recognition on the spectral data to obtain recognized spectral data; the image recognition is used to eliminate abnormal spectral data in the spectral data; Performing average processing on the identified spectrum data to obtain average spectrum data; Performing background subtraction processing on the average spectral data, and splicing the average spectral data after the background subtraction processing to obtain target spectral data; The target spectral data is smoothed, and characteristic peaks are extracted from the smoothed target spectral data to obtain elemental composition and element content of the soil.

[0016] The present invention also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, any of the soil element detection methods described above is implemented.

[0017] The present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the soil element detection method as described in any one of the above is implemented.

[0018] The present invention also provides a computer program product, comprising a computer program, wherein when the computer program is executed by a processor, the computer program implements any of the soil element detection methods described above.

[0019] The optical detection device, soil element detector and soil element detection method provided by the present invention are as follows: the laser beam expansion and collimation system expands and collides the laser emitted by the laser and then inputs it into the multiplexing folding optical path system; the multiplexing folding optical path system folds the laser beam after the expansion and collimation to obtain the folding system output laser, and the folding system output laser is input into the surface scanning optical path system; the surface scanning optical path system focuses the folding system output laser onto the surface scanning target window to generate plasma; the spectral signal acquisition optical path system acquires the signal light radiated by the plasma; and the imaging system images the window of the surface scanning target window on the CMOS camera. The device modularizes the functions of laser beam expansion, collimation, folding, focusing and signal acquisition through the design of a multi-stage optical system; each module can improve the stability of the overall device through independent optimization, thereby improving the stability of the data, realizing fast and accurate scanning detection of the surface to be tested, and further improving the anti-disturbance capability. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 It is a schematic structural diagram of the optical detection device provided by the present invention.

[0022] Figure 2 It is a structural schematic diagram of the optical system installation cavity in the soil element detector provided by the present invention.

[0023] Figure 3 It is a schematic diagram of the multiplexed folded optical path system provided by the present invention.

[0024] Figure 4 It is a schematic diagram of the surface scanning optical path system provided by the present invention.

[0025] Figure 5 This is a simulation diagram of the focusing spot of the surface scanning light provided by the present invention.

[0026] Figure 6 It is a schematic diagram of the spectral signal collection optical path system provided by the present invention.

[0027] Figure 7 This is a simulation diagram of the signal light focusing spot provided by the present invention.

[0028] Figure 8 Schematic diagram of the imaging system provided by the present invention.

[0029] Fig. 9 This is one of the external structural schematic diagrams of the soil element detector provided by the present invention.

[0030] Fig.10 This is one of the flow charts of the soil element detection method provided by the present invention.

[0031] Fig.11 The present invention provides a flow chart of the soil element detector.

[0032] Fig.12 This is a working mode diagram of the galvanometer assembly provided by the present invention.

[0033] Fig.13 This is the second flow chart of the soil element detection method provided by the present invention.

[0034] Fig.14 It is an industrial control schematic diagram of the soil element detector provided by the present invention.

[0035] Fig.15 It is a schematic diagram of a spectrum obtained by the soil element detector provided by the present invention for soil detection.

[0036] Fig.16 It is a fitting curve diagram of spectral intensity and drilling speed obtained by the soil element detector provided by the present invention using two detection methods: fixed-point detection and drilling detection.

[0037] Fig.17 It is an intensity comparison diagram of the characteristic spectrum line of the Al element obtained by the soil element detector provided by the present invention using two detection methods: fixed-point detection and drilling detection.

[0038] Fig.18 It is a structural schematic diagram of the electronic device provided by the present invention. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] Among the related technologies, LIBS technology has been widely used in soil analysis, environmental monitoring, industrial metallurgy, biomedicine, food safety and many other fields in recent years due to its advantages such as fast analysis speed, simple sample preparation, minimal or even non-destructive, and simultaneous detection of multiple elements. The detection capability of LIBS technology has been confirmed many times in laboratory environments. However, due to the large size and high power consumption of traditional LIBS systems, they do not meet the needs of field operations and industrial production online detection and diversified sample characteristics, which limits their flexibility and convenience in practical applications and makes it difficult to give full play to their advantages of in-situ and rapid detection. With the rapid development and continuous progress of instrument technology and computer technology, the size and power consumption of core components such as lasers, spectrometers, optical path systems and microcomputers have gradually decreased, making LIBS systems gradually instrumented, specialized and portable. Portable LIBS devices have the advantages of small size, light weight and easy use, and have better applicability in industrial sites and harsh conditions in the field. Portable LIBS technology is significantly different from traditional desktop LIBS technology in terms of system composition, system performance, and application characteristics. It generally has the characteristics of compact system components, easy mobility of the whole machine, conducive to automated integration and carrying, and integrated detection and analysis. According to the needs of the detection site, its system composition has gradually become more streamlined and efficient, and the system form has gradually changed from a single system to a diversified system. According to the application needs of the detection site, its system has gradually developed into a variety of styles such as suitcase type, backpack type, handheld type, and wearable type with greatly improved portability.

[0041] With the continuous advancement of urbanization and industrialization, people pay more and more attention to environmental testing, soil science research, and agricultural production. Environmental problems such as soil heavy metal pollution are becoming increasingly prominent. Therefore, it is particularly important to establish a complete soil element detection system. In this context, the emergence of portable LIBS element detection instruments provides convenience for the rapid and accurate detection of soil element content information. Although portable LIBS equipment has been widely used in coal, mining, metallurgy and other fields and has been widely reported, in terms of soil element detection, most reports are still based on the completion of laboratory testing after collecting soil samples, and there are relatively few reports on soil element detection at the work site.

[0042] Portable LIBS soil element detection instruments have a broad application space in the soil element detection industry, greatly shortening the detection cycle and effectively promoting the rapid development of smart agriculture (big data management). However, the portable LIBS soil element detection instruments currently launched are greatly affected by environmental factors in actual applications: portable LIBS soil element detection instruments are affected by environmental conditions: temperature, humidity, and soil texture will affect performance, and operators need to use them in a controlled environment to ensure accuracy.

[0043] Based on the above problems, the present invention provides an optical detection device. Figure 1 is a schematic diagram of the structure of the optical detection device provided by the present invention, Figure 2 Schematic diagram of the structure of the optical system installation cavity in the soil element detector provided by the present invention. Figure 1 , Figure 2 As shown, the optical detection device 40 includes a laser beam expansion and collimation system 10, a multiplexing and folding optical path system 11, an imaging system 12, a surface scanning optical path system 13, and a spectral signal collection optical path system 14; The laser beam expansion and collimation system 10 expands and collimates the laser light emitted by the laser 9 and then inputs the laser light into the multiplexing folded optical path system 11; The multiplexing folding optical path system 11 folds the laser beam after beam expansion and collimation to obtain the folding system output laser, and inputs the folding system output laser into the surface scanning optical path system 13; The surface scanning optical path system 13 focuses the laser emitted by the folding system onto the surface scanning target window to generate plasma; The spectrum signal collection optical path system 14 collects the signal light radiated by the plasma; The imaging system 12 images the window of the surface scanning target surface window on a CMOS camera.

[0044] Specifically, the laser beam expansion and collimation system 10 expands and collimates the laser light emitted by the laser 9 and then inputs the laser light into the multiplexing folded optical path system 11 .

[0045] like Figure 2 As shown, the laser beam expansion and collimation system 10 includes a variable aperture 22, a plano-concave lens 23 and a first plano-convex lens 24, wherein the variable aperture 22 adjusts the energy of the laser by changing the size of the light-clearing aperture. By adjusting the energy of the laser, it is possible to avoid the laser energy being too small to cause a weak spectral signal and to avoid the laser energy being too large to cause an oversaturated spectral signal.

[0046] The plano-concave lens 23 and the first plano-convex lens 24 work together to achieve laser beam expansion and collimation (reducing the divergence angle of the laser beam, facilitating long-distance transmission of the laser, and improving the laser focusing quality).

[0047] The multiplexed folded optical path system 11 is used to fold the laser beam after beam expansion and collimation to compress the optical path volume, obtain the folded system output laser, and input the folded system output laser into the surface scanning optical path system 13.

[0048] Figure 3 is a schematic diagram of the multiplexed folded optical path system provided by the present invention, such as Figure 3 As shown, the multiplexing folded optical path system 11 includes a half-inch laser line reflector 25 , a dichroic mirror 26 and a one-inch laser line reflector 27 .

[0049] The optical path system mainly has two functions: the first function is to realize the coaxial transmission of three light beams: laser scanning focusing light, target surface illumination light and target surface imaging light; the second function is to fold the light beams and compress the volume of the overall optical path system. Among them, the half-inch laser line reflector 25 is installed at a 45-degree angle to the horizontal plane, so that the laser after beam expansion and collimation is transmitted horizontally. The dichroic mirror 26 is installed at a 45-degree angle to the horizontal plane and is connected to the imaging system (illumination and CMOS imaging multiplexing optical path system) 12. The lens of the dichroic mirror 26 can reflect laser and transmit visible light. Here, the transmitted visible light includes illumination light and imaging light.

[0050] It should be noted that the imaging system 12 also includes a CMOS camera 21 .

[0051] The one-inch laser line reflector 27 is installed at an angle of 60 degrees to the horizontal plane, and is used to fold the laser beam after expansion and collimation to compress the optical path volume, obtain the folded system output laser, and input the folded system output laser into the surface scanning optical path system 13.

[0052] Here, the main function of the surface scanning optical path system 13 is to realize the surface scanning of the laser, which is used to focus the laser emitted by the folding system onto the surface scanning target window to generate plasma.

[0053] Figure 4 is a schematic diagram of the surface scanning optical path system provided by the present invention, Figure 5 This is a simulated image of the focused spot of the surface scanning light provided by the present invention, such as Figure 4 , Figure 5 As shown, the surface scanning optical path system 13 includes a laser scanning galvanometer assembly 28 , a second plano-convex lens 29 , a third plano-convex lens 30 and a surface scanning target surface window 31 .

[0054] The laser scanning galvanometer assembly 28 is installed at an angle of 70 degrees to the horizontal plane (initial angle), and the angle change of the galvanometer in the laser scanning galvanometer assembly is achieved through the embedded main control board 16 .

[0055] The second plano-convex lens 29 and the third plano-convex lens 30 are focusing lens groups to realize laser surface scanning, so as to achieve the focusing of the laser and the position compensation of the focusing point.

[0056] The surface scanning target window 31 is installed with quartz glass, and the scanning target surface is a square target surface, the size of the square target surface is adjustable, and the maximum target surface is a square target surface of 2cm×2cm. The area of ​​the surface scanning target window 31 will be larger than the actual scanning target surface area.

[0057] The surface scanning optical path system 13 can be realized by a galvanometer, which includes a first detection mode and a second detection mode. The first detection mode is a fixed-point surface scanning mode of the galvanometer movement, which is used to realize multi-point data collection at the same detection position in the soil, and can extract more comprehensive sample information, effectively reduce external interference, and further improve measurement accuracy and stability, ensuring accurate and reliable detection results even in complex environments.

[0058] The second detection mode is a drilling scanning mode when the galvanometer is fixed, which is used to realize drilling, and the drilling is a detection mode of measuring while drilling. These two detection methods can be applied to different detection requirements in actual application scenarios. In addition, the galvanometer motor can also be controlled by the control board to drive the galvanometer to rotate, thereby realizing surface scanning.

[0059] Figure 6 is a schematic diagram of the spectral signal collection optical path system provided by the present invention, Figure 7 is a simulation diagram of the signal light focusing spot provided by the present invention, such as Figure 6 , Figure 7 As shown, the spectral signal collection optical path system 14 is used to transmit the collected signal light to the spectrometer 15 through optical fiber. The spectral signal collection optical path system 14 includes a fourth plano-convex lens 32 and an off-axis parabolic reflector 34. The main function of the spectral signal collection optical path system 14 is to collect signal light and convert the signal light into a spectral signal.

[0060] Among them, the fourth plano-convex lens 32 is used to collect signal light, the surface scanning target window 31 is between the focus 33 of the fourth plano-convex lens and the fourth plano-convex lens 32, and all signal lights radiated by the plasma between the focus 33 of the fourth plano-convex lens and the edge light of the fourth plano-convex lens 32 are collected.

[0061] The off-axis parabolic reflector 34 transmits the collected signal light to the spectrometer 15 via an optical fiber.

[0062] Here, the illumination and CMOS imaging multiplexing optical path system 12 is used to image the surface scanning target window 31 on the CMOS camera 21, and transmit the image of the surface scanning target window 31 to the embedded main control board 16 to analyze whether there is foreign matter in the surface scanning target window 31.

[0063] Figure 8 Schematic diagram of the imaging system provided by the present invention, such as Figure 8As shown, the imaging system (illumination and CMOS imaging multiplexing optical path system) multiplexing optical path system 12 includes a beam splitter 17, a first biconvex lens 18, a second biconvex lens 19, a field of view illumination light source 20 and a CMOS camera 21.

[0064] The beam splitter 17 is installed at an angle of 45 degrees to the horizontal plane, and is used to reflect a portion of the light emitted by the field illumination light source 20 into the multiplexed folded optical path system 11, and at the same time transmit the imaging light of the surface scanning target surface window 31 into the CMOS camera 21.

[0065] The first biconvex lens 18 is used to convert the light emitted by the field illumination light source 20 into parallel light for long-distance transmission.

[0066] The second biconvex lens 19 is used to collect imaging light of the surface scanning target window 31 .

[0067] The field illumination light source 20 is used to generate light that illuminates the surface scanning target window 31, and the field illumination light source 20 controls the illumination time through a circuit switch. The CMOS camera 21 is used to image the surface scanning target window 31, to feedback imaging information, and to transmit the imaging of the surface scanning target window 31 to the embedded main control board 16 to analyze whether there is a foreign object in the surface scanning target window 31.

[0068] In the optical detection device provided by the embodiment of the present invention, the laser beam expansion and collimation system expands and collides the laser emitted by the laser and then inputs it into the multiplexing folding optical path system. The multiplexing folding optical path system folds the laser beam after the expansion and collimation to obtain the output laser of the folding system, and inputs the output laser of the folding system into the surface scanning optical path system. The surface scanning optical path system focuses the output laser of the folding system onto the surface scanning target window to generate plasma. The spectral signal collection optical path system collects the signal light radiated by the plasma, and the imaging system images the window of the surface scanning target window on the CMOS camera. The device modularizes the functions of laser beam expansion, collimation, folding, focusing and signal collection through the design of a multi-level optical system. Each module can improve the stability of the overall device through independent optimization, thereby improving the stability of the data, realizing fast and accurate scanning detection of the surface to be tested, and further improving the anti-disturbance capability.

[0069] Among the related technologies, portable LIBS soil element detection instruments have a broad application space in the soil element detection industry, greatly shortening the detection cycle and effectively promoting the rapid development of smart agriculture (big data management). However, the portable LIBS soil element detection instruments that have been launched have also exposed some shortcomings in practical applications, as described below: (1) The operation process is cumbersome and lacks portability: Existing portable LIBS soil element detection instruments usually perform simple on-site sample preparation and are unable to fully carry out field measurements. This not only increases the complexity of the operation, but also easily causes contamination and interference problems, affecting the accuracy of the analysis results.

[0070] (2) The accuracy of the measurement data is not high: When the portable LIBS soil element detection instrument ablates the sample to be tested, the ablation range is fixed and it is easily affected by other debris and equipment stability issues, resulting in relatively little spectral data obtained, which affects the precision and accuracy of the detection.

[0071] (3) Poor scalability: The existing portable LIBS technology has a relatively narrow detection range and is limited to small-scale local detection. It is difficult to meet the application requirements in wide-area scenarios. At the same time, it lacks compatibility with other equipment, which greatly limits its wide application in many fields such as environmental monitoring, agricultural analysis, and geological exploration.

[0072] Based on the above problems, the present invention provides a soil element detector. Fig. 9 is a schematic diagram of the external structure of the soil element detector provided by the present invention, such as Fig. 9 As shown, the soil element detector includes an optical detection device 40 , and the optical system mounting cavity includes a laser 9 , a spectrometer 15 , an embedded main control board 16 , and the optical detection device 40 .

[0073] It should be noted that the multifunctional portable surface and shallow soil LIBS rapid detection instrument in the embodiment of the present invention is a soil element detection device.

[0074] The external structure of the multifunctional portable surface and shallow soil LIBS rapid tester generally includes a lever arm handle 1, a control panel 2, a telescopic rod 3, an electronic device mounting cavity 4, a power supply 5, an optical system mounting cavity 6, a sensor 7 and an auxiliary detection structure 8.

[0075] The internal structure of the multifunctional portable surface and shallow soil LIBS rapid tester includes a laser 9, a spectrometer 15, an embedded main control board 16, a sensor 7, an optical detection device 40 and a control panel 2. Among them, the drilling button 35 is used to assist the structural drill 8 to drill into the soil; the unscrewing button 36 is used to start the auxiliary structural drill 8 to unscrew the soil; the detection button 37 is used to actually issue an instruction to start detection; the power button 38 is a device switch, which is used to power on and off the entire device; The above four buttons are used to simplify the operation process and make the detection operation more convenient.

[0076] During the drilling process (two detection modes), the user presses the drill button to start the measurement, and the system immediately records the time. As the drill gradually penetrates into the soil, the user releases the button to end the measurement, and the system stops timing. The measurement time is calculated from the time points of releasing and pressing the button, representing the duration of the drill's movement in the soil. This time is the measurement time t. This time data is accurately recorded, providing an important reference for the subsequent calculation of the depth and the average speed of the drill bit drilling into the soil. At the same time, the control board program monitors and ensures the accuracy of the measurement time.

[0077] The external displacement sensor is placed at an angle, and the angle is preset according to the area of ​​soil turned over during drilling. , the distance measured by the displacement sensor is , the distance from the optical signal output port of the displacement sensor to the center of the detection window is , the depth of drilling into the soil It can be calculated by the following formula: The process can directly calculate the depth of the drill into the soil through program calculation. Combined with the time required for measurement. By measuring the time and the calculated depth information, the average speed of the drill bit can be further calculated. Average speed ( ) can be calculated by the following formula: Based on the relationship between depth and time, the control panel's built-in program calculates the average speed of the drill bit as it penetrates the soil.

[0078] Ultimately, the program controls these calculations and displays the average speed of the drill bit's descent directly on the device's display, providing users with real-time measurement results.

[0079] Through the above process, the variable depth soil element detector can realize the function of drilling and measuring, accurately measuring the depth and average speed of the drill bit during drilling. The design of the control part ensures the stability and accuracy of the system, allowing users to easily obtain the required data and analyze it. This intelligent design greatly simplifies the operation process of soil element detection and improves the efficiency and accuracy of measurement.

[0080] Considering the limited measurement range of soil vertical depth, in terms of soil measurement depth, the existing portable LIBS soil element detectors can usually only measure within the range of several hundred microns to several millimeters (i.e., the soil surface layer). There is almost no design for soil element detection equipment at different depths, or to ensure its detection accuracy while taking into account soil detection at different depths. Most of them cannot penetrate deep into the soil, resulting in limitations in the detection of elements in the vertical distribution of soil, and it is impossible to accurately measure uneven soil samples. Therefore, the portable LIBS fast detection instrument of the embodiment of the present invention adds an auxiliary detection structure 8.

[0081] In addition, the telescopic rod 3 can be adjusted in length according to the soil detection depth and the needs of the operator during measurement. It should be noted that the telescopic rod 3 and the auxiliary detection structure 8 are used to insert the detection instrument into the shallow surface (the deepest distance is 25 cm).

[0082] The sensor 7 is used to install and place sensor components such as environmental temperature and humidity sensors, displacement sensors, and GPS positioning sensors. The sensors can obtain soil position information and environmental information.

[0083] Among them, the detection depth of the auxiliary detection structure 8 is determined based on the displacement sensor, and the auxiliary detection structure can realize the function of measuring while drilling. It should be noted that for different soil texture environments, the appropriate auxiliary detection structure can be replaced at any time to ensure that the LIBS rapid detection instrument can complete the drilling task efficiently and accurately. The portable LIBS rapid detection instrument can be taken directly to the detection site, making full use of the in-situ analysis and rapid response capabilities of the LIBS technology, greatly improving the detection efficiency and flexibility.

[0084] It should be noted that the auxiliary detection structure 8 in the "drilling integration" surface and shallow soil LIBS rapid tester is equipped with a small drill bit that can drill into the shallow soil layer. The rapid tester can detect both the surface and shallow layers of the soil, making the soil detection data more accurate and comprehensive. The maximum detectable soil depth is 25cm, and the displacement sensor can be used to grasp the detected soil depth in real time.

[0085] The main part of the portable LIBS rapid tester is composed of a cylindrical structure. With the cooperation of the auxiliary detection structure 8 (a soil drill with a shock-absorbing device), it can detect the vertically distributed elements of the soil within the limited range. The displacement sensor in the auxiliary detection structure 8 can transmit the real-time soil depth and composition information to the user end.

[0086] The optical system installation cavity includes a laser 9 , a spectrometer 15 , an embedded main control board 16 , a sensor 7 and an optical detection device 40 .

[0087] Among them, the laser 9 is used to emit laser, and the laser scans and ablates the detection surface of the soil at different detection depths through the optical detection device 40 to generate plasma, and collects the signal light radiated by the plasma, and transmits the signal light to the spectrometer through the optical fiber. Among them, the detection depth is determined based on the auxiliary detection structure, and the auxiliary detection structure can realize the function of measuring while drilling. Here, the optical detection device 40 includes a laser beam expansion and collimation system 10, a multiplexed folded optical path system 11, an illumination and CMOS imaging multiplexed optical path system 12, a surface scanning optical path system 13, and a spectral signal acquisition optical path system 14. It should be noted that the optical detection device 40 can maintain a stable structure and facilitate installation and debugging.

[0088] Here, the wavelength of the laser emitted by the laser 9 is 1064nm, which has the advantages of safety and no radiation, and the detection process does not involve the use, generation and emission of other pollutants, reducing the risks to operators and the environment. That is, compared with traditional analysis methods, the portable LIBS rapid detection instrument is safer during operation.

[0089] The spectral signal collection optical path system 14 is connected to the spectrometer 15 using optical fiber to transmit the optical signal.

[0090] The spectrometer 15 is used to convert the transmitted spectral signal into spectral data, and send the spectral data to the embedded main control board. It can be understood that the spectral signal is converted into spectral data, thereby enhancing the intuitiveness. In addition, compared with the original spectral signal, the spectral data is easier to qualitatively and quantitatively analyze. Researchers can identify information such as composition differences, concentration changes or structural changes between samples by comparing the differences between different spectral data. Furthermore, the spectral data can also be matched with a known spectral database to quickly determine the composition of unknown samples.

[0091] The sensor 7 is used to collect the position information and environmental information of the soil, and send the position information and the environmental information to the embedded main control board 16 .

[0092] Among them, the sensor 7 includes an environmental temperature and humidity sensor, a displacement sensor and a GPS sensor. The displacement sensor and the GPS sensor are used to collect soil position information, and the environmental temperature and humidity sensor is used to collect environmental information.

[0093] It can be understood that the sensor 7 includes an environmental temperature and humidity sensor, a displacement sensor and a GPS sensor, thereby improving the accuracy and reliability of the location information and environmental information.

[0094] The embedded main control board 16 sends the spectral data, location information and environmental information to the control panel so that the control panel displays the element composition and element content of the soil corresponding to the spectral data, the location information and environmental information of the soil, and the soil detection and analysis results determined based on the spectral data, the location information and environmental information of the soil.

[0095] In addition, portable LIBS rapid detection instruments are able to perform sensitive analysis at low concentrations, usually reaching a detection limit of ppm (parts per million). This makes it very useful in applications such as tracking and detecting low-concentration elements, i.e., portable LIBS rapid detection instruments have high sensitivity.

[0096] Furthermore, the test can be completed without the need for professional operation. Compared with other analytical technologies, the portable LIBS rapid tester does not require cumbersome sample preparation steps, and the instrument has an easy-to-use user interface and operating guide, which makes the analysis process simpler and more efficient, so the test can be completed without the need for professional operation. Non-professionals only need to turn on the device, aim at the target, start the measurement, and wait for the test results to be displayed.

[0097] The optical detection device 40 uses the illumination and CMOS imaging multiplexing optical path system and image recognition algorithm to intelligently distinguish the soil environment to be tested, determine the characteristics and conditions of the soil sample, and judge whether it meets the detection requirements, so that it can automatically eliminate data affected by debris before performing elemental spectrum analysis. Secondly, by accurately controlling the rotation angle of the laser scanning galvanometer to achieve surface scanning of the soil to be tested, a single spectrum measurement integrates multi-point data collection and average calculation, which can extract more comprehensive sample information, effectively reduce external interference, improve measurement accuracy and stability, and ensure accurate and reliable detection results even in complex environments.

[0098] It should be noted that the LIBS rapid tester provided in the embodiment of the present invention does not require sample preparation, that is, does not require a complicated sample preparation process, and can directly analyze actual samples, saving time and avoiding interference problems caused by sample contamination, thereby ensuring the accuracy of soil test results.

[0099] The portable LIBS rapid tester provided in the embodiment of the present invention completes soil detection at different depths through an auxiliary detection structure, uses an optical detection device to improve the stability of the device, thereby improving the stability of the data, and realizing fast and accurate scanning detection of the test surface, and also improves the anti-disturbance ability of the portable LIBS rapid tester. At the same time, the LIBS rapid tester meets the requirements of portability. In summary, the portable LIBS rapid tester meets the needs of modern intelligent agriculture for fast and accurate detection of soil at different depths in a wide area.

[0100] It should be noted that the optical detection device and spectrometer in the portable LIBS rapid tester have built-in data processing and analysis functions, which can perform real-time data processing and result analysis after on-site detection, provide immediate feedback and judgment, and reduce the time waiting for laboratory analysis after sample collection. The real-time and rapid characteristics of this data analysis enable users to quickly obtain results in the field or field environment and make timely decisions. It realizes the application of soil detection in wide-area scenarios, which can realize both large-scale detection and vertical depth layered detection. It can make the soil detection mode more three-dimensional and the soil detection data more comprehensive, and finally form a more intelligent soil element rapid detection method integrating "measurement, control and analysis". In addition, it can realize multi-element synchronous detection: LIBS technology can analyze multiple elements at the same time, including metals, non-metals and rare earth elements, and can obtain information on multiple elements in one test without multiple tests.

[0101] Highly integrated: The LIBS rapid tester has a small overall size, low power consumption and light weight. Compared with the traditional LIBS system, the portable LIBS rapid tester is small, simple and lightweight, and can be easily carried to the work site for testing. Due to its mobility and flexibility, it is not only easy to carry manually, but can also be mounted on intelligent equipment such as unmanned vehicles, providing more possibilities for some harsh environments or high-efficiency work scenarios, greatly broadening the application scope and practicality of LIBS element detection technology.

[0102] The integrated structure design makes it easy to carry to the work site for in-situ testing. The LIBS rapid tester adopts an integrated structure design, that is, the laser, spectrometer, detachable power supply, and embedded main control board are designed as a "probe-type" structure, and a hard soil drill bit is used as an auxiliary detection structure. Ensure that the LIBS rapid tester can complete the drilling task efficiently and accurately. The portable detection device can be taken directly to the inspection site, making full use of the in-situ analysis and rapid response capabilities of LIBS technology, greatly improving the detection efficiency and flexibility.

[0103] The soil element detector provided in the embodiment of the present invention is a surface scanning element detection device based on laser induced breakdown spectroscopy technology, which does not require sample preparation, can detect soil elements at different depths, can cope with different soil environments (the sensor monitors environmental information in real time), has accurate analysis, is highly integrated, intelligent, and has an integrated structure. This portable rapid detection instrument takes into account both portability and integration. It can be used as a manual portable device carried by operators to the work site for use, or as part of an integrated device, carried on unmanned vehicles and other equipment, and integrated into the automation and intelligent operation system of modern agriculture to achieve a more efficient and intelligent operation mode.

[0104] It should be noted that the detection depth of the auxiliary detection structure 8 in the soil element detector provided by the embodiment of the present invention is determined based on the displacement sensor, and the auxiliary detection structure can realize the function of measuring while drilling. According to different soil texture environments, the appropriate auxiliary detection structure can be replaced at any time to ensure that the portable LIBS rapid detection instrument can complete the drilling task efficiently and accurately. Thereby, the depth of soil detection is improved, and the optical detection device 40 in the portable LIBS rapid detection instrument improves the accuracy of soil detection, which further improves the breadth of soil detection, and is suitable for the needs of rapid and large-area detection in modern intelligent agriculture.

[0105] The soil element detection method provided by the present invention is described below. The soil element detection method described below and the soil element detector described above can be referenced to each other.

[0106] Based on any of the above embodiments, the present invention provides a soil element detection method. Fig.10 This is one of the flow charts of the soil element detection method provided by the present invention, such as Fig.10 As shown, the method includes: Step 1010, during the operation of the soil element detector, receiving a spectrum signal emitted by a plasma, and converting the spectrum signal into spectrum data, wherein the plasma is obtained by a laser emitting a laser to the soil to be tested by the soil element detector; Step 1020: Determine the element composition and element content of the soil corresponding to the soil to be tested based on the spectral data.

[0107] Specifically, during the operation of the soil element detector, the spectral signal emitted by the plasma is received and converted into spectral data. The plasma is obtained by the laser 9 emitting laser to the soil to be tested of the soil element detector.

[0108] After the spectral data is obtained, the element composition and element content of the soil corresponding to the soil to be tested can be determined based on the spectral data.

[0109] Fig.11 It is the working flow chart of the soil element detector provided by the present invention, such as Fig.11 As shown in the figure, the device has two detection modes: the first one is the fixed-point surface scanning mode when the galvanometer moves, and the second one is the drilling scanning mode when the galvanometer is fixed.

[0110] 1. In the fixed-point second scanning mode, the position of each fixed-point detection is fed back to the main control system through the displacement sensor before the scan starts. After clicking to start the detection, the CMOS camera first takes a picture of the scanning area, and then the laser 9 emits a laser to complete the surface scanning in conjunction with the galvanometer movement. Subsequently, the multiple sets of spectral information collected by the spectrometer are averaged and converted into a spectrum graph and saved in the same folder (named by the data of the detection depth) with the photos taken before the start of the scan. At the same time, the image recognition algorithm will call the photo information in the folder to automatically distinguish whether there are impurities that interfere with the detection results at the detection position. If there are, all information in the folder will be deleted and the detection position will be prompted to adjust; if not, the qualitative and quantitative analysis algorithms will call the spectral graph information in the folder, calculate the types and contents of elements present in the soil, and display them on the interface together with the location, temperature, humidity and other information. Finally, after the end of this detection, all equipment enters the working state and waits for the next operation instruction.

[0111] 2. In the drilling scanning mode, the drill bit is used to work deep into the soil while scanning. In this mode, the galvanometer is fixed in the initial position and does not rotate. After the detection window is immersed in the soil, click to start the detection. The CMOS camera will take a picture of the scanned target surface before each laser 9 emits light (the light emission frequency can be set by yourself), and then the laser 9 emits a laser to complete a fixed point scan of the galvanometer. Then, a set of spectral information collected by the spectrometer 15 is converted into a spectral graph and saved in the same folder with the photo taken before the start of the scan. At the same time, the image recognition algorithm will call the photo information in the folder to automatically distinguish whether there are impurities that interfere with the detection results at the detection position. If there are, all information in the folder will be deleted and the detection position will be prompted to adjust; if not, the quantitative analysis algorithm will call the spectral graph information in the folder, calculate the type and content of elements in the soil, and display it on the interface together with the position, temperature, humidity and other information. In this mode, the number of detections needs to be set in advance, and the corresponding number of detections will be performed as the drill bit works deep into the soil, and then each useful detection data will be displayed separately according to the different detection positions. After drilling is completed, click the drill button to remove the equipment from the soil, and all equipment will enter the standby state and wait for the next operation instruction.

[0112] Fig.12 is a working mode diagram of the galvanometer assembly provided by the present invention, such as Fig.12 As shown, the entire galvanometer assembly consists of four parts: a galvanometer A that can rotate in the X-axis direction, a motor A that controls the rotation of the galvanometer A, a galvanometer B that can rotate in the Y-axis direction, and a motor B that controls the rotation of the galvanometer B.

[0113] The Raspberry Pi sends the preset coordinate information (X, Y values) to the MCU control board. After receiving the information, the MCU extracts these values ​​and calculates the corresponding analog voltage. The X value controls motor A, and the Y value controls motor B. The MCU outputs the calculated analog voltage signal to the corresponding motor. By changing the voltage value of the input motor, the galvanometer can be controlled to move at different angles in the corresponding X-axis or Y-axis direction. For example, when the input voltage value is 3V, the galvanometer will rotate at an angle of 3°. When performing the surface scanning mode, galvanometer A first rotates in the X-axis direction to move the laser focus point on the X-axis. Then, after galvanometer A stops rotating, galvanometer B rotates in the Y-axis direction to move the laser focus point on the Y-axis. Finally, after galvanometer B stops rotating, galvanometer A rotates again in the opposite direction at the same angle to scan along the preset path. The laser focus point moves back and forth on the X-axis at different Y-axis coordinates to complete the surface scanning (snake-like motion such as Figure 1 In the initial stage, the area size of our surface scan is set to 1cm A 1cm square, with a 5Hz laser frequency, scans a total of 25 points within 5S.

[0114] It can be understood that the above-mentioned portable LIBS rapid detection instrument (soil element detector) can perform automatic image recognition and can perform in-situ and rapid detection.

[0115] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a portable soil element detection device which adopts soil image recognition technology, laser galvanometer scanning technology, highly integrated spatial coupling optical structure and based on drilling and measurement synchronization.

[0116] Fig.13 This is the second flow chart of the soil element detection method provided by the present invention, such as Fig.13 As shown, the method comprises the following steps: 1. Through image recognition algorithms, for example, the Convolutional Neural Network (CNN) algorithm, the abnormal spectral data that has been identified is eliminated to avoid the influence of soil impurities on data accuracy; the Convolutional Neural Network algorithm mainly transforms the original image into a hyperplane coordinate system through a trained network model, and then extracts the features of each image to identify and classify similar images to the greatest extent. In our detection, we take photos of each scanned target surface and save them. Before data analysis and processing, we will use the Convolutional Neural Network algorithm to classify the pictures with stones, dead branches, garbage and other debris in the pictures, and then delete the spectral data in the folder to which the removed pictures belong.

[0117] 2. By simply averaging multiple sets of spectral data (fixed-point detection mode) of a scanned target surface, the random errors that may exist at a single measurement point are reduced, the impact of environmental factors and equipment noise is reduced, and the impact of uneven distribution of element content on the accuracy of the final data is weakened, thereby improving the accuracy and reliability of spectral data. In the fixed-point detection mode, each scanned target surface will collect 25 sets of spectral data, and then the 25 sets of data will be integrated and averaged to form a set of data. The obtained spectral data is a set of data with one-to-one correspondence between wavelength and spectral intensity. We will test the 25 sets of spectral data (merge them into multiple sets of spectral intensity data corresponding to one wavelength), and then average the 25 sets of spectral intensity data corresponding to each wavelength to obtain a set of average spectral data E for subsequent algorithm processing.

[0118] E = 3. The spectrum formed by averaging the spectral data is processed by background subtraction to eliminate the influence of interference signals such as ambient light and lighting sources on the spectrum, highlight the target signal, and reduce data noise to improve the accuracy and reliability of the spectral data; a method for baseline correction using a polynomial fitting method is now provided. By fitting the baseline signal and subtracting the background signal, the spectral data after final analysis can be effectively improved in terms of data quality and accuracy, providing a reliable basis for further spectral analysis.

[0119] 4. Perform background subtraction on the spectrum formed by averaging the spectral data to eliminate the influence of interference signals such as ambient light and lighting sources on the spectrum, highlight the target signal, and reduce data noise to improve the accuracy and reliability of the spectral data. A spectral splicing method is now provided, which integrates different spectral data sets into a single light spectrum based on background subtraction and uses wavelength alignment and intensity correction technology to obtain comprehensive spectral characteristics by integrating information from each band.

[0120] 5. Use the sliding average filter algorithm to smooth the spectrometer data to reduce noise and fluctuations. In a set of experimental data, select N consecutive data points, then calculate the average value of these points, and finally assign the average value to the center point of these N data points. The formula is as follows: in, is the sliding average of the ith data point, N is the window length, Represents the jth data point in the window. By calculating this average value, the data series can be smoothed.

[0121] 6. Use the peak-finding algorithm (local maximum algorithm) to find the peak spectral data, and then determine the type of elements contained in the soil by comparing each characteristic peak with the element characteristic database. The basic principle of the local maximum algorithm is to treat the intensity value of a set of LIBS spectral data as a discrete sequence. If the data satisfy the relationship, then arrive There is a maximum value between them. If it is a Gaussian distribution, the value of k is 1.5.

[0122] Qualitative analysis is completed by determining the types of elements contained in the sample.

[0123] 7. Quantitative analysis algorithm Finally, the detection equipment uses the free calibration method (Calibration-Free Laser-Induced Breakdown Spectroscopy, CF-LIBS) to quantitatively analyze the content of each element in the soil. The free calibration method uses the spectral intensity of the sample to calculate the element concentration of the sample. When using the free calibration method to predict the concentration, the plasma needs to meet the local thermodynamic equilibrium conditions, and the atomic spectral line intensity when the transition occurs between the energy levels Ek and Ei (Taking into account the influence of the efficiency of the optical receiving system) can be expressed as: in, represents the instrument response parameter, Indicates the relative content of an element. represents the transition probability of the spectral line, represents the partition function of the element to be measured, represents the plasma temperature, represents the energy level of the electron, represents the degeneracy of energy levels, is the Boltzmann constant.

[0124] make: , , , . Then the above formula can be described as: (1) Above It represents a parameter related to the plasma temperature, the instrument response parameter F It can be obtained by the normalized equation: (2) The calculation formula for the relative content of elements obtained by reverse deduction is: Generally speaking, the radiation from neutral atoms and primary ionized ions will be measured experimentally. The above formula is the relative content of neutral atoms. For primary ionized ions, it is generally obtained by the Saha equation, so the total relative content can be written as: (3) The steps for measuring the relative content of elements using the free calibration method are summarized as follows: (1) Determine the plasma electron temperature; (2) Obtain the intercept of the measured element on the Y axis of formula (1) ; (3) Obtain the partition function of the element to be measured at the electron temperature by searching the NIST database ; (4) Calculate the instrument response parameters using formula (2): F ; (5) Calculate the response parameters F Then, the relative content of the measured element is calculated by formula (3).

[0125] Fig.14 It is a schematic diagram of the industrial control of the soil element detector provided by the present invention, such as Fig.14 As shown, the system as a whole realizes the control of mechanical equipment and the transmission of information through the embedded main control board 16 (the embedded main control board 16 consists of two parts: the Linux embedded control board and the MCU control board). The MCU control board controls the work of the auxiliary detection structure 8, the laser 9, and the laser scanning galvanometer assembly 28 by driving their drivers; at the same time, it also controls the work and information transmission of the displacement sensor, temperature sensor, GPS positioning module and other sensors installed in the sensor 7 installation cavity and the spectrometer 15; and then transmits the information to the Linux embedded control board. The Linux embedded control board is equipped with a core operating system that can control the camera of the CMOS camera 21 to take pictures for the screening of the detection environment, and at the same time, all the information is analyzed and sorted and transmitted to the superior control panel 2 or APP and other display screen modules for display. Fig.15 is a schematic diagram of a spectrum obtained by the soil element detector provided by the present invention for soil detection, such as Fig.15 As shown, the horizontal axis is wavelength and the vertical axis is relative intensity. It can be seen that the detection instrument can extract effective spectral lines for elements such as Fe, Mg, Al, Ca, and Pb and use them for subsequent content analysis, proving the feasibility of using portable LIBS rapid detection instrument for soil element detection.

[0126] Fig.16It is a fitting curve diagram of spectral intensity and drilling speed obtained by the soil element detector provided by the present invention using two detection methods: fixed-point detection and drilling detection. Fig.17 The intensity comparison diagram of the characteristic spectrum line of Al element obtained by the soil element detector provided by the present invention using two detection methods: fixed-point detection and drilling detection. Fig.16 , Fig.17 As shown in the figure, it can be seen from these data graphs that both fixed-point detection and drilling detection at different speeds can effectively obtain spectral data and perform content analysis, but the drilling speed cannot be too fast (cannot exceed 5cm / s), otherwise the spectral data intensity will be too low, and the final element content result will have a large error. From the fitting curve of spectral intensity and drilling speed, it can be seen that within a reasonable drilling speed range, the intensity of the characteristic spectral line is negatively correlated with the drilling speed (approximately a linear function).

[0127] The embodiment of the present invention provides a method for performing in-situ, rapid soil testing operations in the field using the portable testing device, which is specifically performed in the following steps: Step 1. Before using the detection device, first turn on the power switch of the device, and then click the device self-test on the control panel 2 to ensure that all components in the device can work normally. If a device fails, the self-test fails and the faulty component is displayed.

[0128] Step 2, select different auxiliary detection structures 8 according to the texture of the soil to be tested, and then the operator uses the arm handle 1, telescopic rod 3 and the adapted auxiliary detection structure 8 to make the portable rapid detection instrument enter the shallow soil, and at the same time determine the detection depth according to the feedback data of the displacement sensor.

[0129] Step 3, after determining the detection depth, adjust the length of the telescopic rod 3 to adjust the entire portable rapid tester to a height suitable for the operator. After the adjustment is completed, turn on the field illumination light source 20 to illuminate the surface scanning target window 31, and then image the surface scanning target window 31 on the CMOS camera 21, and then send the imaging information to the control panel 2 through the embedded main control board 16, and then automatically analyze the transmitted target surface image through the image recognition program (manual re-inspection) to confirm whether there is any debris in the detection target window that affects the detection result. According to the analysis results, if there is no debris in the surface scanning target window 31 at this moment, proceed to the next step; if there is debris, change the detection position and repeat steps 2 and 3.

[0130] It should be noted that the image recognition program is deployed on a software end electrically connected to the portable LIBS rapid tester. The image recognition program can be determined based on a machine learning or deep learning algorithm, and the embodiment of the present invention does not specifically limit this.

[0131] Step 4, after confirming that there is no debris in the surface scanning target window 31, turn off the field illumination light source 20, and then set the laser energy by changing the size of the variable aperture 22 to avoid the laser energy being too small to cause a weak spectral signal and to avoid the laser energy being too large to cause an oversaturated spectral signal. Then click the parameter setting option on the control panel 2 to enter the device parameter setting interface, and change the light output frequency of the laser 9 and the rotation speed of the laser scanning galvanometer assembly 28 to meet the actual surface scanning point requirements (at the same time, the size of the scanning target surface can be set by changing the rotation angle of the galvanometer). Finally, set the spectral integration time and spectral average times of the spectrometer 15 according to the actual number of surface scanning points.

[0132] Among them, the detection modes can include two types. One is the surface scanning focusing detection mode of the galvanometer movement, which can realize multi-point data collection at the same detection position, can extract more comprehensive sample information, effectively reduce external interference, further improve measurement accuracy and stability, and ensure accurate and reliable detection results even in complex environments.

[0133] The second is the fixed-point focus detection mode where the galvanometer does not move, which is mainly used in the rapid detection mode of drilling (the equipment drills deep into the soil while performing soil detection). These two detection methods can be applied to different detection needs in actual application scenarios.

[0134] It should be noted that the detection method includes an image recognition algorithm. Each time the soil is tested, each detection point will be photographed and recorded by a CMOS camera, and then the image recognition algorithm will be used to determine whether there are any interfering debris that affects the detection at the detection point. If there are any, the measurement data will be automatically deleted. This method can effectively improve the accuracy and reliability of the detection, and at the same time effectively avoid the problem that the measurement position does not meet the detection conditions due to the lack of sample preparation.

[0135] Step 5, after the detection parameters are set, click the Start Detection option on the control panel 2, and the laser 9, spectrometer 15 and laser scanning galvanometer assembly 28 perform soil detection according to the set parameters. After completing a surface scan in the surface scanning target window 31, the laser 9 stops emitting light and automatically powers off (safety protection), the laser scanning galvanometer assembly 28 restores the initial installation angle and stops rotating, and the spectrometer 15 converts the transmitted spectral signal into spectral data and sends it to the control panel 2 through the embedded main control board 16, and then calculates the element composition and content contained in the soil through the built-in LIBS quantitative analysis program and displays it on the control panel 2. At the same time, the environmental temperature and humidity sensor, displacement sensor, GPS sensor and other sensor components carried by the equipment also send the location information and environmental information of the detected soil to the control panel 2 through the embedded main control board 16 in real time, and display it together with the qualitative and quantitative analysis results.

[0136] Step 6. After the measurement is completed, the measurement results can be saved. The measurement results can be viewed anytime and anywhere in the local "Query" of the instrument and the APP. The measurement results include spectral images, soil environmental information, and qualitative and quantitative analysis results.

[0137] In summary, the above steps 1 to 6 can be summarized into the following four steps: 1. Confirm the detection position (detection depth and scanning target surface); 2. Set the detection parameters; 3. Start detection (collect spectral signals of the scanning target surface); 4. Data analysis (qualitative and quantitative analysis of soil elements through spectral data calculation).

[0138] It is understandable that the detection method includes a multi-element quantitative analysis algorithm based on spectroscopy, which uses the collected spectral data for calculation and analysis to obtain the content of each element. At the same time, the algorithm adds the influencing factors of temperature and humidity, which can correct the final calculated element content according to the temperature and humidity information detected by the sensor in real time, thereby further improving the detection accuracy.

[0139] In order to ensure that the portable element detection instrument of the present invention receives enough light signals for accurate element quantitative analysis, it is necessary to ensure that the spot diameter of the focused laser for surface scanning is less than 0.5mm, and the spot diameter of the signal light coupled into the optical fiber is less than 0.3mm. We simulated and emulated the optical structure through the optical design software Zemax, and the results obtained are as follows: Figure 5 , Figure 7 According to the simulation results of the software, it can be seen that the maximum spot diameter of the focused laser in the maximum surface scan (2cm×2cm) is 243.881μm, and the maximum spot diameter of the signal light coupled into the optical fiber is 72.155μm, both of which meet the design requirements.

[0140] According to the test steps and methods described in the embodiments of the present invention, we successfully obtained and sorted out a set of detailed data. The following table lists the data results under some test conditions in detail: Table 1 shows the corresponding relationship between the drill bit drilling speed and the element concentration when the same piece of soil is tested under different detection modes; Table 2 further analyzes the corresponding element concentration prediction error value when the drill bit drilling speed is within a certain range and exceeds the controllable range.

[0141] Table 1 Table 2 The data in the above two tables show that the drilling feasibility (it can detect the concentration of elements both at fixed points and when moving) has an error of about 5%, but the speed cannot be too fast. From the error comparison analysis table shown in Table 2, it can be seen that when the drilling speed of the drill bit is within a certain range (≤5cm / s or so), the error detected is about 5%, which is within the controllable error range. However, when the speed is too fast (10cm / s), the error will increase, resulting in inaccurate analysis results.

[0142] These data not only verify the accuracy and reliability of the method described in the present invention, but also provide a solid experimental basis for subsequent application and optimization.

[0143] Fig.18 is a schematic diagram of the structure of the electronic device provided by the present invention, such as Fig.18 As shown, the electronic device may include: a processor 1810, a communication interface 1820, a memory 1830 and a communication bus 1840, wherein the processor 1810, the communication interface 1820 and the memory 1830 communicate with each other through the communication bus 1840. The processor 1810 may call the logic instructions in the memory 1830 to execute the soil element detection method, which includes: during the operation of the soil element detector, receiving a spectrum signal emitted by a plasma, and converting the spectrum signal into spectrum data, wherein the plasma is obtained by a laser emitting a laser to the soil to be detected by the soil element detector; and determining the element composition and element content of the soil corresponding to the soil to be detected based on the spectrum data.

[0144] In addition, the logic instructions in the above-mentioned memory 1830 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0145] On the other hand, the present invention also provides a computer program product, which includes a computer program. The computer program can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the soil element detection method provided by the above methods. The method includes: during the operation of the soil element detector, receiving a spectral signal emitted by a plasma, and converting the spectral signal into spectral data, wherein the plasma is obtained by a laser emitting a laser to the soil to be tested of the soil element detector; based on the spectral data, determining the elemental composition and element content of the soil corresponding to the soil to be tested.

[0146] On the other hand, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the soil element detection method provided by the above methods is implemented. The method includes: during the operation of the soil element detector, receiving a spectral signal emitted by a plasma, and converting the spectral signal into spectral data, wherein the plasma is obtained by a laser emitting a laser to the soil to be tested of the soil element detector; based on the spectral data, determining the elemental composition and element content of the soil corresponding to the soil to be tested.

[0147] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0148] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0149] 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 it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An optical detection device, characterized in that: Including laser beam expansion and collimation system, multiplexing folding optical path system, imaging system, surface scanning optical path system, spectral signal collection optical path system; The laser beam expansion and collimation system expands and collides the laser light emitted by the laser and then inputs the laser light into the multiplexed folded optical path system; The multiplexed folded optical path system folds the laser beam after beam expansion and collimation to obtain the folded system output laser, and inputs the folded system output laser into the surface scanning optical path system; The surface scanning optical path system focuses the laser emitted by the folding system onto the surface scanning target window to generate plasma; The spectral signal collection optical path system collects the signal light radiated by the plasma; The imaging system images the window of the surface scanning target surface window on a CMOS camera.

2. The optical detection device according to claim 1, characterized in that: The laser beam expansion and collimation system is provided with a variable aperture, a plano-concave lens and a first plano-convex lens in sequence along the incident direction of the incident laser; The variable iris adjusts the energy of the laser; The plano-concave lens and the first plano-convex lens expand and collimate the adjusted laser.

3. The optical detection device according to claim 1, characterized in that: The multiplexed folded optical path system includes a half-inch laser line reflector, a dichroic mirror and a one-inch laser line reflector; The half-inch laser line reflector transmits the expanded and collimated laser horizontally; The lens of the dichroic mirror reflects laser light and transmits visible light, wherein the transmitted visible light includes illumination light and imaging light; The one-inch laser line reflector performs beam folding on the expanded and collimated laser to obtain the folded system output laser.

4. The optical detection device according to any one of claims 1 to 3, characterized in that: The surface scanning optical path system is provided with a laser scanning galvanometer assembly, a second plano-convex lens, a third plano-convex lens and a surface scanning target window in sequence along the incident direction of the incident laser; A focusing lens group performs laser surface scanning in the surface scanning target surface window; the focusing lens group includes a second plano-convex lens and a third plano-convex lens; The surface scanning target surface window is installed with quartz glass, and the scanning target surface is a square target surface, and the size of the square target surface is adjustable.

5. The optical detection device according to any one of claims 1 to 3, characterized in that: The imaging system is provided with a field illumination light source, a first double convex lens, a beam splitter, a second double convex lens and a CMOS camera in sequence along the incident direction of the incident laser; The field of view illumination light source generates light that illuminates the surface scanning target window, and the field of view illumination light source controls the illumination time through a circuit switch; The first biconvex lens converts the light emitted by the field illumination light source into parallel light; The beam splitter reflects the parallel light into the multiplexed folded optical path system; The second biconvex lens collects imaging light from the surface scanning target window; The CMOS camera displays the imaging light.

6. The optical detection device according to any one of claims 1 to 3, characterized in that: The spectral signal collection optical path system includes a fourth plano-convex lens and an off-axis parabolic reflector; The surface scanning target surface window is located between the focus of the fourth plano-convex lens and the fourth plano-convex lens, and all signal lights radiated by the plasma between the focus and the edge light of the fourth plano-convex lens are collected; The off-axis parabolic reflector collects the signal light.

7. A soil element detector, characterized in that: include: An optical detection device as claimed in any one of claims 1 to 6.

8. The soil element detector according to claim 7, characterized in that: It also includes lasers, spectrometers, embedded main control boards and sensors; The laser emits laser light; The optical detection device generates plasma by scanning and ablating the detection surface of soil at different detection depths through the laser, and collects the signal light radiated by the plasma; The spectrometer converts the spectral signal obtained by the signal light transmission into spectral data; The sensor collects location information and environmental information of the soil; The embedded main control board is connected to the spectrometer and the sensor respectively, and is used to display the position information and the environmental information, as well as the soil element composition and soil element content corresponding to the spectral data.

9. A soil element detection method, characterized in that: include: During the operation of the soil element detector, a spectral signal emitted by the plasma is received, and the spectral signal is converted into spectral data. The plasma is obtained by a laser emitting a laser to the soil to be tested by the soil element detector. Based on the spectral data, the element composition and element content of the soil corresponding to the soil to be tested are determined.

10. The soil element detection method according to claim 9, characterized in that: The step of determining the element composition and element content of the soil corresponding to the soil to be tested based on the spectral data includes: Performing image recognition on the spectral data to obtain recognized spectral data; the image recognition is used to eliminate abnormal spectral data in the spectral data; Performing average processing on the identified spectrum data to obtain average spectrum data; Performing background subtraction processing on the average spectral data, and splicing the average spectral data after the background subtraction processing to obtain target spectral data; The target spectral data is smoothed, and characteristic peaks are extracted from the smoothed target spectral data to obtain elemental composition and element content of the soil.

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