LIBS optical measurement system based on sCMOS and image processing method thereof

Abstract

According to the invention, a scientific-grade CMOS (sCMOS) sensor is adopted as a photoelectric detector to build an LIBS optical measurement system, and a processing method for converting a plasma image into a plasma spectrum is provided. According to the invention, in the construction process of the LIBS measurement system, the area array sCMOS sensor is used, and secondary imaging is carried out through the optical lens, so that the capture and spectral analysis of the plasma radiation signal by the whole measurement system are completed, the technical requirements of the LIBS measurement system are met, and the application field of the sCMOS as a photoelectric detector is broadened; in addition, more selectivity is provided for construction of an LIBS measurement system, a possibility is provided for cost reduction and system structure optimization, and the whole measurement system also has the original advantages of the spectrum technology, such as high sensitivity, high stability, rapid sampling and analysis capability, layer-by-layer analysis capability and multi-element simultaneous analysis capability. Damage to samples is small, and operation is easy.

Description

Technical Field

[0001] The invention relates to the technical field of laser induced breakdown spectroscopy, and in particular to a sCMOS-based LIBS optical measurement system and an image processing method thereof. Background Art

[0002] Laser-induced breakdown spectroscopy (LIBS), also known as laser-induced plasma spectroscopy, is a typical atomic emission spectrum. LIBS technology is the product of the combination of laser technology and spectroscopy technology. It has strong technical advantages and application potential in analyzing the elemental composition of substances. It is a rapid, in-situ analysis and detection technology for the elements of substances in any state (solid, liquid and gas). Its working principle is: when the laser emits a laser pulse, the high-power pulsed laser beam is focused on the sample to be tested with the help of a lens. The sample to be tested is ablated and excited, and plasma is instantly generated and formed on its surface. By collecting and analyzing the wavelength and intensity information of the atomic or ion spectrum in the plasma, the qualitative and quantitative analysis of the elements in the sample to be tested is achieved. LIBS has a wide range of applications, whether it is solid, liquid or gas, and it can be performed in the air without pretreatment of the sample. In addition, it can detect multiple elements at the same time and obtain analysis results in a very short time. It is used in environmental monitoring, industrial online real-time monitoring, safety detection and national defense. Since the laser can be focused on a micron-scale spot, the mass of the ablated material is extremely small, so it is almost non-destructive detection. At the same time, it has long-distance detection capabilities and has broad application prospects in the fields of hazardous material detection, field measurement, and space exploration. Compared with other types of atomic emission spectroscopy, the technology has many incomparable advantages.

[0003] The LIBS optical measurement system is generally composed of three major components, namely: the light source generation system (laser), the plasma radiation signal acquisition system (optical path system and light receiving system) and the spectral signal detection system (spectrometer and photodetector). The light source generation system provides laser emission pulses, the acquisition system composed of the optical path system and the light receiving system is used to collect plasma signals, and the acquisition system composed of the spectrometer and the photodetector is used to collect and analyze the radiation spectrum of the laser-induced plasma and perform photoelectric conversion on it. In the LIBS experimental measurement system, the photodetector converts the optical signal into an electrical signal that can be directly read and recorded by the computer. Currently, the commonly used photodetectors include photomultiplier tubes PMT, photodiode arrays PDA, charge-coupled devices CCD and enhanced charge-coupled devices ICCD. The PMT detector has the characteristics of high sensitivity, fast detection speed, and single wavelength detection, which is suitable for LIBS industrial applications of a specific element; the CCD detector is composed of a series of photosensitive units and can detect spectral signals in a certain spectral range; the ICCD detector is composed of a microchannel plate and a CCD detector; among them, CCD and ICCD are widely used in experimental LIBS basic research and LIBS detection with high performance requirements. The present invention adopts scientific-grade CMOS (sCMOS) sensors as photosensitive elements for photoelectric signal conversion for the first time, and the emitted light signals of the plasma are focused to the photoelectric detection surface through a large-target optical lens, stimulating an optical image, and then undergoing photoelectric conversion to achieve spectrum detection. The invention of this photoelectric detector not only expands the application field of sCMOS sensors, but also has the characteristics of being able to achieve time-resolved detection, high sensitivity, high signal-to-noise ratio, and high detection accuracy, meeting the measurement requirements of the LIBS optical system for simultaneous and rapid detection of multiple elements. Summary of the invention

[0004] In order to achieve the above-mentioned purpose and other advantages of the present invention, the first purpose of the present invention is to provide a LIBS optical measurement system based on sCMOS, including a laser, a reflector, a focusing lens, a sample displacement stage, a collecting lens, an optical fiber, a spectrometer, an optical lens, and a sCMOS sensor;

[0005] The laser pulse emitted by the laser changes the direction of the optical path through the reflector, propagates downward, and is focused on the sample placed on the sample displacement stage through the focusing lens to generate plasma. The spectral signal generated by the plasma is collected by the collecting lens and transmitted to the spectrometer through the optical fiber. The spectrometer, as a spectroscopic system, separates the composite light of the plasma into monochromatic light arranged in different wavelengths, and images are formed on the sCMOS sensor through the optical lens from its output port, thereby realizing the detection and identification of the plasma spectral signal.

[0006] Furthermore, the laser is a pulsed solid-state laser.

[0007] Furthermore, the reflector is a plane reflector with an incident angle of 45°.

[0008] Furthermore, the focusing lens is a non-coated plano-convex lens, and the focusing lens moves forward and backward along the direction of the turned laser beam.

[0009] Furthermore, the sample displacement stage moves in three directions, X, Y, and Z, to achieve height control and horizontal scanning movement control, thereby optimizing the laser focusing depth of the sample.

[0010] Furthermore, the collecting lens is at an angle of 45° to the horizontal plane to collect plasma signals. A quartz lens is used at one end of the collecting lens and an optical fiber connector is used at the other end to couple the plasma radiation signal into the optical fiber.

[0011] Furthermore, one end of the optical fiber adopts an optical fiber connector to match the collecting lens, and the other end of the optical fiber is an optical fiber connector with a slit of a preset size to match the spectrometer interface. Multimode optical fiber is used in the middle of both ends of the optical fiber, and its operating wavelength spans the ultraviolet to near-infrared band.

[0012] Furthermore, the spectrometer adopts a CT structure spectrometer or a mid-step spectrometer.

[0013] Furthermore, the optical lens adopts a large target surface lens.

[0014] Furthermore, the working mode of the sCMOS sensor is external trigger or internal trigger.

[0015] Furthermore, a timing controller is included, and the timing controller is used to control the time interval between the action of the laser and the sCMOS sensor, so as to realize the simultaneous action of the laser and the sCMOS sensor.

[0016] Furthermore, the timing controller is implemented using a signal generator, which provides two separate pulse waves for external triggering control of the laser and the sCMOS respectively.

[0017] A second object of the present invention is to provide an image processing method of a LIBS optical measurement system based on sCMOS, based on the above system, comprising the following steps:

[0018] The sCMOS sensor is set to obtain a plasma emission spectrum image with high contrast; wherein the abscissa of the plasma emission spectrum image represents the wavelength range, and the ordinate represents the radiation intensity;

[0019] Each pixel point in the plasma emission spectrum image is traversed, the gray value of each pixel point is read, and its vertical coordinate is accumulated along the horizontal axis direction to obtain an atomic spectrum line diagram of plasma radiation intensity varying with wavelength.

[0020] Furthermore, after obtaining a plasma emission spectrum image with high contrast, the method further comprises the following steps:

[0021] The plasma emission spectrum image is intercepted to reveal the plasma region.

[0022] A third object of the present invention is to provide a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the above method when executing the computer program.

[0023] A fourth object of the present invention is to provide a computer-readable storage medium having a computer program stored thereon, wherein the computer program implements the steps of the above method when executed by a processor.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention uses a scientific-grade CMOS (sCMOS) sensor as a photodetector to build a LIBS optical measurement system, and provides a processing method for converting a plasma image into a plasma spectrum. In the process of building the LIBS measurement system, the present invention uses a planar array sCMOS sensor and completes the capture and spectrum analysis of the plasma radiation signal by the entire measurement system through secondary imaging of an optical lens, meeting the technical requirements of the LIBS measurement system, not only broadening the use field of sCMOS as a photodetector, but also providing more selectivity for building the LIBS measurement system, and also providing a possibility for cost reduction and optimization of the system structure, and the entire measurement system also has the original advantages of the spectral technology: high sensitivity, high stability, fast sampling and analysis capabilities, layer-by-layer analysis capabilities, multi-element simultaneous analysis capabilities, little damage to samples, simple operation, etc.

[0026] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. The specific implementation of the present invention is given in detail by the following embodiments and their accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0028] Figure 1 Schematic diagram of the sCMOS-based LIBS optical measurement system of Example 1;

[0029] Figure 2 Schematic diagram of the sCMOS sensor and optical lens of Example 1;

[0030] Figure 3 This is a schematic diagram of plasma spectrum signal detection in Example 1;

[0031] Figure 4 This is the LIBS plasma emission signal spectrum of a soil sample;

[0032] Figure 5 This is a flow chart of the sCMOS-based LIBS optical measurement method of Example 2;

[0033] Figure 6 This is a schematic diagram of a computer device in Example 3;

[0034] Figure 7 This is a schematic diagram of a computer-readable storage medium of Example 4.

[0035] In the figure: 1. laser; 2. reflector; 3. focusing lens; 4. sample displacement stage; 5. collecting lens; 6. optical fiber; 7. spectrometer; 8. optical lens; 81. aperture; 82. lens group; 9. sCMOS sensor; 91. shutter; 92. photosensitive element; 10. timing controller; 11. plasma radiation signal after being split by the spectrometer; 12. image of the plasma radiation signal after being split by the spectrometer; 13. sample; 14. plasma. DETAILED DESCRIPTION

[0036] The present invention is further described below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. It should be noted that, under the premise of no conflict, the embodiments or technical features described below can be arbitrarily combined to form a new embodiment.

[0037] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making any creative work shall fall within the scope of protection of the present invention.

[0038] The figure numbers in this application are only used to distinguish the various steps in the scheme and are not used to limit the execution order of the various steps. The specific execution order is subject to the description in the specification.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0040] Example 1

[0041] A LIBS optical measurement system based on sCMOS, specifically a LIBS optical measurement system using sCMOS as a photodetector, which increases the selectivity of the photodetector required by the LIBS optical measurement system while ensuring the measurement accuracy, and expands the application field of sCMOS. Figure 1-Figure 3 As shown, the system includes a laser 1, a reflector 2, a focusing lens 3, a sample displacement stage 4, a collecting lens 5, an optical fiber 6, a spectrometer 7, an optical lens 8, and a sCMOS sensor 9;

[0042] The laser pulse emitted by the laser changes the direction of the optical path through the reflector, propagates downward, and is focused on the sample 13 placed on the sample displacement stage through the focusing lens to generate plasma 14. The spectral signal generated by the plasma is collected by the collecting lens and transmitted to the spectrometer through the optical fiber. The emitted light of the laser plasma is a superposition of a continuous spectrum and a discrete spectrum, and is white light as a whole. The spectrometer, as a spectroscopic system, separates the composite light of the plasma into monochromatic light arranged in different wavelengths, and images the light from its output port onto the sCMOS sensor through the optical lens, thereby realizing the detection and identification of the plasma spectral signal.

[0043] Optionally, the laser adopts ND:YAG pulsed solid-state laser, whose activating material is yttrium aluminum garnet crystal (YAG crystal) into which a small amount of neodymium (Nd) is doped. The laser adopts crystal electro-optical Q-switching method to generate pulses, and adopts air-cooling cooling system to carry away the heat generated by the laser through heat exchange with internal circulating water. It has the characteristics of high reliability, compact structure, good beam quality, high power density and wide laser wavelength range (ultraviolet to infrared), and is often used in LIBS measurement.

[0044] For example, the laser uses a Nd:YAG pulsed solid-state laser with a wavelength of 1064nm, uses an active pressurized Q-switching method to generate pulses, and uses internal circulating water cooling for heat exchange to remove the heat generated by the laser; the laser's maximum output energy can reach up to 200mJ, and the pulse frequency can be adjusted between 1 and 20Hz through the interface control software. The spot diameter is about 5mm, the pulse width is about 10ns, the divergence angle of the laser beam is less than 3.5mrad, the size is about 250*80*90mm3, and the energy stability is excellent.

[0045] The reflector is used to reflect light, change the direction of the light path, and realize the steering propagation of the light beam. Optionally, the reflector is a plane reflector with a size of 25.4 mm, an incident angle of 45°, and a reflectivity of greater than 99.5% at a wavelength of 1064 nm. In actual use, the entire LIBS optical measurement system is built on an optical platform, and the laser 1 is raised to a certain appropriate height. The laser pulse emitted by it enters the reflector 2 with an incident angle of 45° parallel to the optical platform, and enters the focusing lens 3 vertically after being turned.

[0046] The focusing lens is used to focus the pulsed light beam on the sample surface or other positions of the sample, so that the energy is concentrated to complete the ablation to form plasma, and it can be finely moved forward and backward along the direction of the turned laser beam. Optionally, the focusing lens is an uncoated plano-convex lens made of H-K9L material, with a focal length of 150mm, a center thickness of 4mm, a size of 25.4mm, a transmittance of more than 90% at a wavelength of 1064nm, a smooth surface, and high optical performance.

[0047] The sample displacement stage is used to place the test sample. Generally, there are two options: an electric displacement stage and a manual displacement stage. The displacement stage can move in three directions: X, Y, and Z to achieve height control and horizontal scanning movement control, which is convenient for optimizing the laser focus depth of the sample (focus depth refers to the distance between the focus point below the surface and the sample surface for solid and liquid samples). Among them, the electric displacement stage can accurately control the displacement of various stepper motors, and control the movement of the displacement stage through remote control, program control, or manual setting of various parameters of the controller panel through its own software.

[0048] For example, the sample translation stage 4 can adopt a manual XYZ axis three-dimensional translation stage, which is made of aluminum alloy, can bear a load of 5Kg, has a minimum scale of 0.01mm, an accuracy of up to 0.03mm, an XY axis stroke of ±12.5mm, a Z axis stroke of 10mm, accurate readings, and stable performance.

[0049] The collecting lens is used to collect the emission spectrum signal of the plasma, and couple it into the optical fiber and transmit it into the spectrometer. Optionally, the collecting lens is at a 45° angle to the horizontal plane to collect the plasma signal. One end of the collecting lens uses a quartz lens with a wavelength in the range of 200nm-2500nm, and the other end uses an SMA905 optical fiber connector, which can couple the plasma radiation signal into the optical fiber.

[0050] The optical fiber transmits the spectral signal of the plasma through the slit into the spectrometer. During experimental measurement, it is necessary to optimize the relative position of the optical fiber in the plasma image to find the best position for measuring the corresponding element. Optionally, one end of the optical fiber uses an SMA905 optical fiber connector to match the collecting lens, and the other end of the optical fiber is an optical fiber connector with an 11μm slit to match the spectrometer interface. Multimode optical fiber is used in the middle of the two ends of the optical fiber, for example, a multimode optical fiber with a length of 1m is used, the working wavelength spans the ultraviolet to near-infrared band, the optical fiber core diameter is 200μm, and the numerical aperture is 0.22. It has the characteristics of good coupling, high transmittance, and good anti-fatigue performance, and is an ideal choice for the application of LIBS measurement system.

[0051] The spectrometer splits the spectral signal generated by the LIBS plasma. At present, the spectrum acquisition system in the LIBS system mainly includes two types: Czerny-Turner (CT) structure spectrometer and mid-step spectrometer. The LIBS plasma signal is incident on the surface of the collimating lens through a slit, becomes parallel light, and enters the diffraction light grating. The grating splits the light signal according to the wavelength, and then focuses the image at its outlet focal plane through a focusing lens. A detector is installed on its focal plane, and the detection system can obtain the spectral information of the LIBS plasma after the splitting. The single-channel CT spectrometer splits the light by rotating the grating, and the coverage band range is relatively narrow, but the resolution is high. The mid-step spectrometer can obtain a spectrum within a large detection range at one time, with a wide coverage band range and good dispersion rate.

[0052] For example, the spectrometer uses a single-channel CT grating spectrometer with three gratings, a focal length of 500mm, an operating wavelength of 200nm-1400nm, a wavelength accuracy of 0.04nm, a resolution of 0.06nm, a clear aperture of F / 6.5, and both the light inlet and the light outlet have 10μm-2mm adjustable slits. It has stable working performance, fast analysis speed, high resolution, good repeatability and sensitivity, and ensures the accuracy of the analysis results.

[0053] The optical lens is used to perform secondary imaging of the split LIBS plasma signal on the surface of the detector. A large target surface lens can be used. The large target surface lens has a large light receiving area, has high optical resolution, and can maintain high resolution and high precision within a large field of view.

[0054] For example, the optical lens 8 uses a large-target UV lens with a focal length of 50 mm and a maximum sensor size of 21 mm, the interface type is C-Mout, the working distance is greater than 0.17 m, the F / # is F3.0-F22, the field of view (diagonal*horizontal*vertical) is 17.6°*14.2°*10.6° when the sensor size is 1 inch, and the working wavelength is 200-1100 nm. Figure 2 As shown, the lens group 82 is used to focus and constrain light, and the aperture 81 is used to control the amount of light passing through the lens and entering the photosensitive surface in the body, which also affects the depth of field and exposure of the photo. The optical lens 8 has high resolution and accuracy, a large field of view, excellent optical performance and low light performance, and is suitable for LIBS measurement system.

[0055] In combination with the above embodiments, Figure 2 As shown, the plasma radiation signal 11 after being split by the spectrometer is imaged by the large-target ultraviolet optical lens onto the photosensitive element 92 of the sCMOS sensor, thereby obtaining an image 12 of the plasma radiation signal after being split by the spectrometer, that is, a plasma spectrum image.

[0056] The sCMOS sensor is used as a detector of the LIBS optical measurement system, and its purpose is to convert the obtained plasma light signal after the light splitting into an electrical signal, which is then recorded and analyzed by a computer. The sCMOS sensor technology combines the high speed and digital characteristics of CMOS technology with the accuracy and sensitivity of optical sensors. The main components include a CMOS image sensor, an analog signal processor, a digital signal processor, and an output interface. The image captured by the optical lens is converted into an electrical signal, and then the electrical signal is processed, and finally the processed image is output through the output interface. Two-dimensional light intensity spatial information can be provided, and the detected light intensity is the integral within the readout time. The vertical plane element of the pixel signal is used to perform simultaneous detection within a spectral range, and it can be matched with a spectrometer to realize simultaneous and rapid measurement of multiple elements. The spectrum or image signal in almost any time period in the LIBS spectrum can be collected by adjusting the delay time, exposure time, integration time, etc., with high stability and high sensitivity, and time-resolved detection can be achieved.

[0057] The sCMOS sensor has two working modes: external trigger and internal trigger. The number of pixels is 2048*2048, the pixel size is 6.5μm*6.5μm, and the frame rate is 40fps. Figure 2As shown, the photosensitive element 92 in the component is composed of a series of photosensitive units, which can detect spectral signals in a certain spectral range, and the response range is 200nm-1100nm. The shutter 91 in the component realizes precise control of the exposure time. Therefore, the sCMOS sensor 9 can flexibly control the trigger delay time, exposure time and integration time, thereby filtering out the interference of LIBS background radiation to the maximum extent, obtaining the best atomic radiation signal, and improving the sensitivity of LIBS detection.

[0058] In some embodiments, Figure 1 As shown, a timing controller 10 is also included, and the timing controller is used to control the time interval between the laser and the sCMOS sensor, so as to realize the simultaneous operation of the laser and the sCMOS sensor, thereby improving the collection efficiency of the laser plasma. Specifically, the timing controller 10 provides two separate pulse outputs to enter the laser 1 and the sCMOS sensor 9 respectively. By reasonably controlling the time interval between the two channel pulses, it is possible to ensure that all plasma signals are collected, thereby improving the collection efficiency of the laser plasma.

[0059] Optionally, the timing controller is implemented using a signal generator to provide two separate pulse waves for external triggering control of the laser and the sCMOS respectively, with a frequency range of 100μMHz-10MHz, a delay range of 0-1000s, a resolution of 5ps, and an accuracy of 1ns, which is used for timing control of the laser and sCMOS sensor.

[0060] The LIBS plasma emission signal spectrum of a soil sample obtained using sCMOS as a detector is shown in the figure below. Figure 4 As shown, the plasma image is converted into a plasma spectrum by the processing method provided in Example 2 to obtain a plasma spectrum diagram.

[0061] sCMOS sensors are faster, can better respond to fast events, have higher sensitivity, can obtain clear images under low light conditions, and also have the characteristics of low noise and wide dynamic range. Based on these advantages, this embodiment uses scientific-grade CMOS (sCMOS) sensors as photodetectors for the first time to build a LIBS optical measurement system, and provides a processing method for converting plasma images into plasma spectra. This embodiment skips the method of using linear array CCD or ICCD sensors as detectors in the process of building a LIBS measurement system, uses a planar array sCMOS sensor and completes the capture and spectral analysis of plasma radiation signals by the entire measurement system through secondary imaging of optical lenses, meets the technical requirements of the LIBS measurement system, not only broadens the use of sCMOS as a photodetector, but also provides more selectivity for the construction of the LIBS measurement system, and also provides a possibility for cost reduction and optimization of the system structure, and the entire measurement system also has the original advantages of the spectral technology: high sensitivity, high stability, fast sampling and analysis capabilities, layer-by-layer analysis capabilities, multi-element simultaneous analysis capabilities, little damage to samples, simple operation, etc.

[0062] Example 2

[0063] An image processing method of a LIBS optical measurement system based on sCMOS is provided. Based on the above system, the detailed description of the system can refer to the corresponding description in the above system embodiment, which will not be repeated here. Figure 5 As shown, the method comprises the following steps:

[0064] S1. Obtaining a plasma emission spectrum image with high contrast by setting the sCMOS sensor to obtain a suitable black and white degree of the image; wherein the abscissa of the plasma emission spectrum image represents the band range, and the ordinate represents the radiation intensity;

[0065] S2. Traverse each pixel point in the plasma emission spectrum image, read the grayscale value of each pixel point (the grayscale value represents the brightness or darkness of each pixel in the image, usually ranging from 0 to 255, white is 255, and black is 0), and accumulate its vertical coordinate along the horizontal axis direction to obtain an atomic spectrum line diagram of plasma radiation intensity varying with wavelength, that is, a plasma spectrum diagram.

[0066] When performing image processing, operations such as filtering, enhancement, cropping, feature extraction, etc. may be performed. In some embodiments, after obtaining a plasma emission spectrum image with high contrast, the following steps are also included:

[0067] The plasma region in the plasma emission spectrum image is intercepted. For example, the number of pixels in the intercepted plasma region is 1024*200, the horizontal axis (band range) contains 1024 pixels, and the vertical axis (radiation intensity) contains 200 pixels. The grayscale values ​​of the vertical axis pixels in the corresponding direction are accumulated in units of the total number of horizontal axis pixels to achieve a one-to-one correspondence between light radiation intensity and wavelength, laying the foundation for finally obtaining the plasma spectrum map, that is,

[0068] i represents the number of vertical pixels, n=200.

[0069] Example 3

[0070] A computer device 150, such as Figure 6 As shown, it includes a memory 151, a processor 152, and a computer program 153 stored in the memory and executable on the processor. When the processor executes the computer program, the steps of an image processing method of a LIBS optical measurement system based on sCMOS are implemented. For a detailed description of the method, reference may be made to the corresponding description in the above method embodiment, which will not be repeated here.

[0071] Example 4

[0072] A computer readable storage medium such as Figure 7 As shown, a computer program is stored thereon, and when the computer program is executed by the processor, the steps of an image processing method of a LIBS optical measurement system based on sCMOS are implemented. For a detailed description of the method, reference may be made to the corresponding description in the above method embodiment, and no further description is given here.

[0073] Example 5

[0074] A computer program product, comprising a computer program, wherein when the computer program is executed by a processor, the steps of an image processing method for a LIBS optical measurement system based on sCMOS are implemented. For a detailed description of the method, reference may be made to the corresponding description in the above method embodiment, which will not be repeated here.

[0075] The number of devices and processing scales described here are used to simplify the description of the present invention. Applications, modifications and variations of the present invention will be obvious to those skilled in the art.

[0076] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and implementation modes. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

[0077] The apparatus, computer device, non-volatile computer storage medium and method provided in the embodiments of this specification correspond to each other, and therefore, the apparatus, computer device and non-volatile computer storage medium also have similar beneficial technical effects as the corresponding method. Since the beneficial technical effects of the method have been described in detail above, the beneficial technical effects of the corresponding apparatus, computer device and non-volatile computer storage medium will not be repeated here.

[0078] Those skilled in the art also know that, in addition to implementing the controller in a purely computer-readable program code, the controller can be made to implement the same function in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method steps. Therefore, such a controller can be considered as a hardware component, and the devices for implementing various functions included therein can also be considered as structures within the hardware component. Or even, the devices for implementing various functions can be considered as both software units for implementing the method and structures within the hardware component.

[0079] The systems, devices or units described in the above embodiments can be implemented by computer chips or entities, or by products with certain functions. For the convenience of description, the above devices are described separately by functions in various units. Of course, when implementing one or more embodiments of this specification, the functions of each unit can be implemented in the same or more software and / or hardware.

[0080] Those skilled in the art will appreciate that the embodiments of this specification may be provided as methods, systems, or computer program products. Therefore, the embodiments of this specification may be in the form of complete hardware embodiments, complete software embodiments, or embodiments in combination with software and hardware. Moreover, the embodiments of this specification may be in the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0081] This specification is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of this specification. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0082] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0083] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0084] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0085] The specification may be described in the general context of computer-executable instructions executed by a computer, such as program units. Generally, program units include routines, programs, objects, components, data structures, etc. that perform specific tasks or implement specific abstract data types. The specification may also be practiced in distributed computing environments where tasks are performed by remote processing devices connected via a communications network. In a distributed computing environment, program units may be located in local and remote computer storage media, including storage devices.

[0086] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0087] The above description is only an embodiment of this specification and is not intended to limit one or more embodiments of this specification. For those skilled in the art, one or more embodiments of this specification may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of one or more embodiments of this specification shall be included in the scope of the claims of one or more embodiments of this specification.

Claims

1. A LIBS optical measurement system based on sCMOS, characterized in that: Including laser, reflector, focusing lens, sample translation stage, collection lens, optical fiber, spectrometer, optical lens, sCMOS sensor; The laser pulse emitted by the laser changes the direction of the optical path through the reflector, propagates downward, and is focused on the sample placed on the sample displacement stage through the focusing lens to generate plasma. The spectral signal generated by the plasma is collected by the collecting lens and transmitted to the spectrometer through the optical fiber. The spectrometer, as a spectroscopic system, separates the composite light of the plasma into monochromatic light arranged in different wavelengths, and images are formed on the sCMOS sensor through the optical lens from its output port, thereby realizing the detection and identification of the plasma spectral signal.

2. The sCMOS-based LIBS optical measurement system according to claim 1, characterized in that: The laser is a pulsed solid-state laser.

3. The sCMOS-based LIBS optical measurement system according to claim 1, characterized in that: The reflector is a plane reflector with an incident angle of 45°.

4. The sCMOS-based LIBS optical measurement system according to claim 1, characterized in that: The focusing lens is a non-coated plano-convex lens, and the focusing lens moves forward and backward along the direction of the turned laser beam.

5. The sCMOS-based LIBS optical measurement system according to claim 1, characterized in that: The sample displacement stage moves in three directions, X, Y, and Z, to achieve height control and horizontal scanning movement control, thereby optimizing the laser focusing depth of the sample.

6. The sCMOS-based LIBS optical measurement system according to claim 1, characterized in that: The collecting lens is at an angle of 45° to the horizontal plane to collect plasma signals. A quartz lens is used at one end of the collecting lens and an optical fiber connector is used at the other end to couple the plasma radiation signal into the optical fiber.

7. A LIBS optical measurement system based on sCMOS as claimed in claim 6, characterized in that: One end of the optical fiber adopts an optical fiber connector to match the collecting lens, and the other end of the optical fiber is an optical fiber connector with a slit of preset size to match the interface of the spectrometer. Multimode optical fiber is used in the middle of the two ends of the optical fiber, and its operating wavelength spans the ultraviolet to near-infrared band.

8. The sCMOS-based LIBS optical measurement system according to claim 1, characterized in that: The spectrometer adopts a CT structure spectrometer or a mid-step spectrometer.

9. The sCMOS-based LIBS optical measurement system according to claim 1, characterized in that: The optical lens adopts a large target surface lens.

10. The sCMOS-based LIBS optical measurement system according to claim 1, characterized in that: The working mode of the sCMOS sensor is external trigger or internal trigger.

11. The sCMOS-based LIBS optical measurement system according to claim 1, characterized in that: It also includes a timing controller, which is used to control the time interval between the action of the laser and the sCMOS sensor, so as to realize the simultaneous action of the laser and the sCMOS sensor.

12. The sCMOS-based LIBS optical measurement system according to claim 11, characterized in that: The timing controller is implemented using a signal generator, which provides two separate pulse waves to perform external triggering control on the laser and the sCMOS respectively.

13. An image processing method for a LIBS optical measurement system based on sCMOS, based on the system according to any one of claims 1 to 12, characterized in that: The following steps are involved: The sCMOS sensor is set to obtain a plasma emission spectrum image with high contrast; wherein the abscissa of the plasma emission spectrum image represents the wavelength range, and the ordinate represents the radiation intensity; Each pixel point in the plasma emission spectrum image is traversed, the gray value of each pixel point is read, and its vertical coordinate is accumulated along the horizontal axis direction to obtain an atomic spectrum line diagram of plasma radiation intensity varying with wavelength.

14. The image processing method of the LIBS optical measurement system based on sCMOS according to claim 13, characterized in that: After obtaining a plasma emission spectrum image with high contrast, the method further includes the following steps: The plasma emission spectrum image is intercepted to reveal the plasma region.

15. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 13 to 14 are implemented.

16. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 13 to 14 are implemented.

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