CN101587074B - Component analyzer for laser probe micro-area - Google Patents

Abstract

The invention belongs to the technical field of laser detection, in particular to a laser probe micro-area component analyzer. Its structure is: the laser, the beam expander and the first total reflection mirror are located on the same horizontal optical path in turn; the angle between the reflection surface of the first total reflection mirror and the horizontal optical path is 45 degrees; the industrial CCD is located above the first total reflection mirror , the industrial CCD and the first focusing objective lens are placed sequentially from top to bottom with the optical axes coincident; the working surface of the three-dimensional workbench is located below the first focusing objective lens; the total reflection mirror is movable on the reflection optical path of the sample, and the fiber optic probe is located The reflected optical path of the mirror; the industrial CCD is connected to the computer with a display through the optical fiber, and the optical fiber probe is connected to the grating spectrometer, the enhanced CCD and the computer. The laser probe instrument can perform non-destructive detection of elements in the micro-area of the material, and can meet the rapid qualitative analysis of elemental components of devices of various materials and sizes, and can also perform high-precision quantitative analysis of trace or even trace elements in the micro-area of the sample.

Description

A Laser Probe Micro-area Composition Analyzer

technical field

The invention belongs to the technical field of laser precision detection, and specifically relates to a laser probe micro-area component analyzer (laser probe instrument for short), which is mainly used for qualitative and precise quantitative analysis of material micro-area element components.

Background technique

In different fields such as metallurgy, machinery, energy, chemical industry, environmental protection, biopharmaceuticals, etc., qualitative or precise quantitative analysis of material components is often required. Commonly used analytical instruments mainly include electron probes and scanning electron microscope energy spectrometers, which can more accurately detect the elemental composition of substances, especially the micro-composition of the phase under high magnification conditions. However, the disadvantages of these two instruments are: firstly, the equipment is bulky and has high requirements for the environment where the equipment is placed, such as constant temperature and humidity, etc., so it is impossible to move the instrument to the production site for analysis; All kinds of analysis equipment use electron beam as the means of phase composition analysis, and to reduce the scattering effect of electron beam, the analyzed sample must be placed in a high vacuum environment for analysis and detection, so the space size of the sample chamber is greatly limited , especially the component analysis of large-scale samples cannot be completed; again, for a long time, the accuracy of electron probe analysis has been hovering around 1%, and the accuracy of scanning electron microscope energy spectrum analysis is only 1%-5%, which is difficult to meet the requirements of some micro-area objects. Requirements for accurate quantitative analysis of phases; Finally, in electronic probe and energy spectrum analysis, the analyte must be conductive, so it is impossible to analyze the composition of non-conductive ceramics, glass, organics and other insulating materials.

The Chinese patent document "Laser-Induced Plasma Spectroscopic Analyzer" (the announcement is CN2869853, and the announcement date is February 14, 2007) discloses a laser-induced plasma spectroscopic analyzer suitable for the analysis of trace elements in gases, liquids and solids. It is divided into three parts: laser, micro analyzer and host computer. In actual use, start the laser to emit a pulsed laser beam, focus the laser beam on the surface of the sample to be tested on the sample stage through the condenser, and make the sample to be tested generate plasma. The spectral signals emitted by the excited atoms are focused to the receiving end of the optical fiber on the side of the sample stage, and the emission spectrum of the element is guided to the micro-spectrometer through the optical fiber. , the results of qualitative analysis and quantitative analysis of elements are output by the computer.

The above technique is an example of material element analysis using laser-induced breakdown spectroscopy (LIBS), which can quickly measure the element content of gas, liquid and solid samples in the field. However, this device can only be used as a component analysis device for bulk or a large number of substances (including solids, gases and liquids), that is, the analyzed material composition is actually the comprehensive average result of bulk substances, and cannot analyze the micro-area of substances. chemical composition. Furthermore, this patent document makes no mention of the analytical precision and sensitivity of the substances that can be analyzed.

After 1996, some foreign scholars proposed the method of using LIBS to analyze the micro-area analysis of solid material components, which is referred to as MicroLIBS or laser microanalysis technology (see K.Y.Yamamoto, D.A.Cremers, M.J.Ferris and L.E.Foster.Appl.Determination of copper in A533b steel for the assessment of radiation embrittlement using laser-induced breakdown spectroscopy Spectrosc. 50(1996), pp. 222-233.). Its essence is to combine the LIBS device with an optical microscope. After observing the surface structure of the bulk material, the laser beam in the LIBS is focused and irradiated directly at the observed area. A breakdown plasma spectrum is generated, and a grating spectrum analyzer is used to detect and analyze the laser-excited atomic and ion spectra, and the detected material composition corresponds to the chemical composition of the micro-area. This MicroLIBS is the first to propose a technical route that combines optical microscopy and LIBS, making it possible to analyze the composition of specified micro-regions in an atmospheric environment.

From 1996 until now, various forms of MicroLIBS have been developed. Although these MicroLIBS technologies can analyze the microscopic components of substances, they have the following deficiencies: First, the structural design of MicroLIBS ignores the influence of the laser beam quality on the minimum resolution of the analysis area, and the focused laser spot has a large diameter , affecting the precision of its micro-area analysis. For example, described in comparative literature (J.M.Mermet a, P.Mauchien b, et al, Processing of shot-to-shotraw data to improve precision in laser-induced breakdown spectrometrymicroprobe, Spectrochimica Acta Part B 63(2008)999-) MicroLIBS minimum analysis domain size range is 5-10 microns. This value is even larger than the smallest area analyzed by current electron probe and scanning electron microscopy. Second, in the comparative literature mentioned above, no effective measures have been taken to improve the component analysis accuracy of the MicroLIBS system. At present, the highest precision of composition resolution achieved by MicroLIBS technology is 1%, which is equivalent to the analysis precision of the existing electron probe and slightly higher than that of the scanning electron microscope. Therefore, compared with the well-developed electronic probe and scanning electron microscope analysis equipment, the application of MicroLIBS is still greatly restricted.

Contents of the invention

The object of the present invention is to provide a laser probe micro-area composition analyzer, which has high analysis precision, a small range of the minimum micro-area size that can be analyzed, does not need a vacuum environment, and is sensitive to the size and conductivity of the analyzed sample. Unlimited flexibility and high analysis efficiency.

The laser probe micro-area component analyzer provided by the invention is characterized in that:

The laser, the beam expander and the first total reflection mirror are sequentially located on the same horizontal optical path, and the included angle between the reflection surface of the first total reflection mirror and the horizontal optical path is 45 degrees;

The industrial CCD is located above the first total reflection mirror, the first focusing objective lens is located below the first total reflection mirror, and the optical axes of the first focusing objective lens and the industrial CCD coincide;

The worktable of the three-dimensional workbench is located under the first focusing objective lens for placing samples;

The second total reflection mirror is movably installed on the reflected light path of the sample, and the fiber optic probe is located on the reflected light path of the second total reflection mirror;

The industrial CCD is connected to a computer with a display through an optical fiber, and the fiber optic probe is connected to a grating spectrometer and an enhanced CCD through an optical fiber in turn, and the latter is connected to a computer through a coaxial cable.

As an improvement of the present invention, the laser adopts a tunable pulse laser. The laser has a small hole diaphragm or its light outlet is provided with a small hole diaphragm. Between the laser and the beam expander, a half-wave plate and a first , the second polarizer. The composition analyzer of this structure can not only perform more accurate qualitative analysis, but also perform high-precision quantitative analysis.

As another improvement of the present invention, a constraining mechanism is installed under each focusing objective lens. The constraining mechanism can be a thin-walled cylindrical member or composed of two parallel thin-walled pieces, and its material is preferably a magnetic material.

Due to various shortcomings in the existing MicroLIBS technology, the present invention provides the above-mentioned technical solution, which can achieve the purpose of qualitative or precise quantitative analysis of the components of the micro-region of the laser probe. Specifically, the present invention has the following technical characteristics:

(1) In the present invention, when performing qualitative detection and analysis on simple elements or only a small amount of elements, a laser with a fixed wavelength can be used as the excitation light source. When multiple elements need to be detected and the trace elements in them need to be accurately quantitatively analyzed, a wavelength-tunable all-solid-state pulsed laser (hereinafter referred to as tunable laser) is generally used as the excitation light source. The main purpose of using tunable lasers is to improve the compositional analysis accuracy of laser probes. One of the key factors for the low analysis accuracy of traditional LIBS technology is that when the laser excites the plasma spectrum of the substance, the plasma spectrum signal of the element with a large content in the analyzed substance will annihilate the spectrum of the element with a small content under the condition of a fixed laser wavelength. signal, thus reducing the accuracy of compositional analysis of trace or trace elements. The main reason for this phenomenon is that the laser wavelengths used in LIBS or MicroLIBS systems at home and abroad are single or fixed. When the laser beam excites the spectrum of the material, different elements in the material are irradiated by laser beams of different wavelengths, and the degree of excitation produced is very different. Especially when the photon energy of the laser beam is equivalent to the energy required for the intrinsic excitation of the detected substance, the spectral excitation intensity of the element is much greater than that of other elements, so that the spectral signal intensity of other elements can be suppressed. Increase the spectral signal intensity of the set element. This excitation process is called resonance excitation, which is of great significance for improving the analysis accuracy of each element in the substance, especially for greatly improving the analysis accuracy of trace or trace elements. One of the characteristics of the present invention is to utilize the technical characteristics of material resonance excitation, and change the single-wavelength all-solid-state laser commonly used in the existing LIBS analysis into a wavelength-tunable all-solid-state pulsed laser, and use different substances to generate resonance excitation The difference in the energy state of the time characteristic spectrum and its corresponding photon energy difference (corresponding to different wavelengths) maximize the excitation of the characteristic spectrum of the specified element in the analyte, while suppressing the characteristic spectrum of other elements to a minimum, thereby improving the quality of the analyte. The analysis accuracy of elements with relatively small content in the medium, especially the analysis accuracy of trace elements or even trace elements.

(2) Two measures have been adopted in the present invention to ensure that the spot diameter of the laser beam after focusing reaches the minimum state: the one is to use a beam expander to expand the spot diameter of the laser beam to a large enough size so that the focusing system of large numerical aperture can be fully utilized , to obtain a smaller spot diameter after focusing; the second is to use multiple focusing objectives with different magnifications, which are suitable for various analysis precision. When the focusing objective lens with the highest magnification is selected, the spot diameter of the focused laser beam can be made smaller. One of the biggest disadvantages of the existing MicroLIBS technology is that the spot diameter is still too large (generally 5-10 microns), so it is impossible to obtain a smaller micro-area analysis space.

(3) In the present invention, the plasma spectrum signal is collected from the coaxial optical axis, which ensures the analysis accuracy of the laser probe plasma spectrum. Traditional MicroLIBS technology generally collects spectral signals from the side of the laser-induced plasma. Since a certain space needs to be left between the focusing objective lens and the sample to install the detector, the focal length of the focusing objective lens cannot be too short, otherwise the relevant signals cannot be effectively detected. , which is also one of the fundamental reasons why the diameter of the laser beam spot cannot be further reduced in the previous MicroLIBS technology. In the present invention, the plasma signal is collected from the optical axis, and the signal is transmitted to a grating spectrometer and an enhanced charge-coupled detector (i.e., an enhanced CCD) through a quartz optical fiber. The intensity characteristics and distribution of the spectrum are displayed on the display terminal. Since the signal is collected on the same axis, there is no need to consider leaving enough space to install the side-facing spectral probe. Therefore, a short focal length objective lens can be used to make the diameter of the laser beam spot smaller, so that the minimum micro-area size that the laser probe instrument can analyze can be larger. Smaller, higher resolution. In the present invention, by taking the above three measures, the diameter of the laser beam spot can reach about 1 micron, and the analysis accuracy is not only much higher than that of the existing MicroLIBS system, but also much higher than that of the existing electronic probe and scanning electron microscope energy spectrum analysis. The instrument makes the laser probe instrument more competitive in high-precision micro-area component analysis.

(4) One of the biggest features of the laser probe instrument is that it can perform fixed-point component analysis on the observed microstructure. In order to ensure that the obtained component analysis results correspond to the chemical components of the observed micro-regions, the present invention adopts a coaxial optical system, that is, the light guide system of the laser beam and the sample optical observation system are integrated into the same set of optical paths. The optical axis is coaxial, and some optical components are shared. After focusing, a confocal plane is formed on the surface of the sample to observe and analyze the micro-area surface morphology of the sample to be tested. In other words, the laser beam generated by the laser coincides with the optical axis of the focusing objective lens and industrial CCD, and after observing the morphology of the micro-area through the objective lens and industrial camera (CCD), the laser is directly activated to generate high The energy pulse laser beam excites the plasma in the observed area, and through the analysis of the plasma spectral characteristics, the composition analysis of the area can be completed in situ, ensuring the consistency of the microstructure analysis and composition analysis process.

(5) In the process of material composition analysis, it is often necessary to analyze the average composition of a large micro-area, or the variation law of composition along a certain line, etc. Both electron probes and scanning electron microscopes have this function, which are called Component surface scan and component line scan. The existing MicroLIBS technology does not have this function because it does not have a motion mechanism. The invention has the functions of laser component analysis, optical focusing, three-axis movement and computer control, and the formed laser probe instrument can complete line scanning of the components of each element of the analyzed substance like an electronic probe and a scanning electron microscope energy spectrum analysis. and surface scan analysis. In other words, after observing and analyzing the surface topography of the analyte by using a microscopic focusing device (including industrial CCD and focusing objective lens), the corresponding control program can be programmed to set the area to be analyzed (including the linear area) or surface area), and then directly start the laser, generate the plasma spectrum, and obtain the relevant analysis results. At the same time, the workbench scans the focused laser beam on the surface of the sample according to the requirements of the analysis program to complete the line scan and surface scan analysis of the substance.

In the improved solution of the present invention, it is considered that sometimes it is necessary to conduct more precise non-destructive detection of trace or even trace elements in the micro-area of the sample. In the present invention, a laser with a small hole diaphragm is used or a small hole diaphragm is added at the light outlet of the laser. The high-order mode in the laser beam is removed, and at the same time, a half-wave plate and a polarizer are added to the laser optical path to further filter the laser beam output by the laser, so that the laser beam becomes an ideal Gaussian 00 mode.

In the improved solution of the present invention, it is also considered that when the spot diameter of the laser beam becomes smaller, the range of the excited plasma signal will also become smaller, and the signal will become weaker. A specially designed plasma confinement mechanism can also be used to restrict the movement direction and expansion range of the plasma, thereby prolonging the life of the plasma signal and improving the accuracy of the analyzed elements.

In summary, compared with electron probes, scanning electron microscopes, and MicroLIBS, which are widely used in material composition analysis, laser probes have the following technical effects:

First, the minimum excitation area of the laser probe instrument can reach less than 1 μm, and its minimum spatial resolution is much better than that of electron probes, scanning electron microscopes and MicroLIBS; second, the absolute analysis accuracy of the laser probe instrument can reach up to ppm level, which is unmatched by scanning electron microscopes and electron probes; third, the laser probe instrument is suitable for high-precision micro-area composition analysis of conductive and non-conductive substances, so this equipment can be used for metals, ceramics, glass, plastics Composition analysis of almost all solid substances; while electronic probes and scanning electron microscopes can only complete the composition analysis of conductive materials; fourth, the laser probe instrument does not require vacuum, the size of material samples is not limited, and has low environmental requirements, which can Transported to the site of large parts for micro-component analysis; finally, the laser probe instrument has a large expansion space, and can be developed into a series of special component detection instruments to meet the detection requirements of different purposes, especially for non-destructive detection of devices.

The laser probe instrument can replace the existing electron probe and scanning electron microscope. It is not only suitable for the micro-composition analysis of metal materials, but also suitable for the micro-composition analysis of non-metallic materials such as ceramics, glass, plastics, etc. It can be used in materials science and Engineering, machinery manufacturing, metallurgy, petrochemical industry, biological engineering, electronic engineering, nuclear physics, agriculture and safety testing and many other fields.

Description of drawings

Fig. 1 is the structural representation of the first specific embodiment of the laser probe micro-area component analyzer of the present invention;

Figure 2 is an enlarged schematic view of area A in Figure 1;

Fig. 3 is the structure schematic diagram of the first kind of improved embodiment of the laser probe micro-area composition analyzer of the present invention;

Fig. 4 is the structural representation of the second improved specific embodiment of the laser probe micro-area component analyzer of the present invention;

Fig. 5 is a schematic structural view of a third improved embodiment of the laser probe micro-area component analyzer of the present invention.

Detailed ways

The present invention is described in more detail below by means of examples, but the following examples are only illustrative, and the protection scope of the present invention is not limited by these examples.

As shown in Figure 1, the laser probe micro-area component analyzer of the present invention includes a component analysis system (LIBS system), a sample optical observation system, a three-dimensional workbench, and a laser probe integrated control system. FIG. 2 is an enlarged schematic diagram of point A in FIG. 1 .

The component analysis system includes a laser 1, a laser beam shaping light guide component, and a spectrum acquisition and analysis component.

Laser 1 usually adopts a tunable laser, and its wavelength range is continuously adjustable within the range of 215nm-2550nm; in the case of qualitative detection of some specific elements, a fixed wavelength laser can be used. The laser 1 is a laser with a small hole diaphragm, or the mode selection can be realized by adding a small hole diaphragm at the light outlet.

The laser beam shaping light guide assembly includes a beam expander mirror 5 , a first total reflection mirror 7 and a first focusing objective lens 19 sequentially located on the same optical path. The included angle between the reflection surface of the first total reflection mirror 7 and the horizontal optical path is 45 degrees.

The laser 1 and the beam expander 5 are directly fixed on the substrate 13 by screw connections, the first total reflection mirror 7 is installed on the first rotating electromagnet 16, and the first rotating electromagnet 16 is connected with the fixed bracket of the microscopic observation assembly. 11, wherein the fixed bracket 11 of the microscopic observation assembly is fixedly installed on the base plate 13.

A movable support 12 is installed below the fixed support 11 of the microscopic observation assembly. A lens holder turntable 17 is installed below the mobile support 12, and a plurality of lens holders can be installed on the lens holder turntable 17, and a gathering objective lens is all installed on each lens holder. This example is equipped with three lens holders, and the lens holder interior is respectively equipped with the first focusing objective lens 19 and the second and the third focusing objective lens 18,20 as standby, and they are objective lenses of different magnifications respectively, can be rotated by rotating the lens holder rotating disk 17 Make a free choice. In FIG. 1 , the selection of the first focusing objective lens 19 is taken as an example for illustration.

The spectrum acquisition and analysis component includes a constraint mechanism 21 , a second total reflection mirror 9 , an optical fiber probe 8 , a quartz optical fiber 25 , a grating spectrometer 27 , an enhanced CCD 28 , and a second display 30 .

An optical signal confinement mechanism 21 is installed below the first focusing objective lens 19 and the second and third focusing objective lenses 18 and 20 . The shape of the constraining mechanism 21 can be a thin-walled cylindrical structure, or can be composed of two parallel thin-walled members. When only qualitative analysis is performed on the sample, the constraint mechanism 21 can also be omitted.

The second total reflection mirror 9 is located between the first total reflection mirror 7 and the first focusing objective lens 19, and is installed on the second rotating electromagnet 36, and the second rotating electromagnet 36 is installed on the mobile support 12, and the second total reflection The mirror 9 is mounted at an angle of 45° to the vertical path of the laser beam 6 and it reflects the optical signal of the plasma 22 horizontally.

The optical fiber probe 8 is located on the reflection optical path of the second total reflection mirror 9, and is fixedly installed on the side of the mobile support 12 for collecting the optical signal of the plasma 22, which is reflected by the second total reflection mirror 9 through the restraint mechanism 21 Enter the optical fiber probe 8, and then transmit to the grating spectrometer 27 and the enhanced CCD 28 through the quartz optical fiber 25, then process the data through the host computer 29, and finally display the collected characteristic spectrum results on the second display 30.

The sample optical observation system includes an industrial CCD10, an optical fiber 26, and a first display 32.

The industrial CCD 10 is located above the first total reflection mirror 7 , and is connected to the lower computer 31 through the optical fiber 26 , and the first display 32 is connected to the lower computer 31 .

The focusing objective lens 19 picks up the image of the surface topography of the analyzed sample 23 , and after being amplified by the industrial CCD 10 , it is transmitted to the lower computer 31 through the optical fiber 26 and displayed on the first display 32 .

The three-dimensional workbench includes a moving bracket 12 of a microscopic observation component, a two-dimensional numerical control machine tool 24 , a screw, a guide rail 14 , a motor 15 and a controller 34 .

The moving support 12 of the microscopic observation assembly is located under the fixed support 11 of the microscopic observation assembly, and is connected with the screw rod and the guide rail 14 installed on the side of the substrate 13 .

The two-dimensional numerical control machine tool 24 is a standard plane workbench, which is placed on the marble or granite base 35 and fixed thereto by screws. The controller 34 is used to control the movement of the plane worktable in the x-y direction, and is connected with the motor 15 at the same time. By controlling the motor 15, the screw rod and the guide rail 14 drive the moving bracket 12 to move up and down, so as to adjust the microscopic observation component and the surface of the analyzed sample. distance. In other words, the two-dimensional CNC machine tool 24 (i.e. the x-y axis) together with the motor 15, the screw and the guide rail 14 (i.e. the z-axis) installed on the moving bracket 12 of the microscopic observation system constitute an x-y-z three-axis motion system. Driven by the controller 34, by compiling corresponding control software, the composition analysis of the surface micro-area of samples with complex shapes can be completed;

The laser probe integrated control system is the core of the entire laser probe composition analyzer, including the lower computer 31 and the upper computer 29 .

The lower computer 31 is connected with the two-dimensional numerical control machine tool 24 and is connected with the controller 34 at the same time. A three-dimensional motion is formed to scan and analyze the surface micro-regions of the sample 23 to be analyzed.

The control system software installed in the upper computer 29 can control the laser power supply control module 33 connected to the upper computer 29, the control module of the grating spectrometer 27, the control module of the enhanced CCD28, the driver module of the numerically controlled machine tool, etc. to be connected by synchronous signal lines. Specially compiled control software completes various complex analysis and test functions of the laser probe instrument.

As a typical example of qualitative analysis, the laser 1 generally adopts a laser with a fixed wavelength of 532 nm, and its laser pulse width is less than 10 ns; the pulse energy of a single pulse is 10-50 mJ, and the pulse repetition frequency is 10 Hz.

The beam expander 5 expands the diameter of the laser beam 6 output by the laser 1 to reduce the divergence angle of the laser beam 6, fully utilizes the numerical aperture of the focusing objective lens 19, and obtains a laser beam spot with a smaller spot diameter after focusing, thereby improving laser detection. The minimum spatial resolution accuracy of the needle instrument.

The first and second total reflection mirrors 7 and 9 are all movable installations. The first total reflection mirror 7 is mainly used to reflect the horizontal optical path of the laser beam downward to a vertical optical path, and the second total reflection mirror 9 is mainly used to reflect the optical signal of the plasma 22 into the fiber optic probe 8 .

The focusing objective lens 19 has three functions: one is to directly observe the optical topography of the sample surface; the other is to serve as a part of the light guide system to directly irradiate the laser beam spot 6 onto the surface of the analyzed sample 23 after focusing; the third is to collect the laser beam The signal of the plasma 22 excited by the beam 6 is reversely transmitted along the optical path of the laser beam to the fiber optic probe 8 for spectral analysis.

The constraining mechanism 21 is a key mechanism to ensure the analysis accuracy of the laser probe composition. The materials used for the confinement mechanism 21 can be magnetic or non-magnetic materials, and the life of the plasma 22 can be further extended by using magnetic materials. The constraint mechanism 21 neither hinders the normal output of the laser beam 6 nor blocks the optical signal of the laser-induced plasma 22 from entering the light guide system. At the same time, since the confinement mechanism 21 is a thin-walled structure with a small space and is very close to the surface of the sample 23, it can effectively limit the movement direction and speed of the plasma 22, prolong its life, and improve the analysis accuracy of the laser probe instrument.

The substrate 13 can be preferably made of marble or granite to ensure its hardness and flatness, and has good shock absorption and shock resistance.

Described screw mandrel, guide rail 14 are connected with motor 15, can move up and down under the drive of motor 15, adjust the distance between focusing objective lens 19 and this analysis sample 23 as required, make the focal point of laser beam 6 always fall on to be analyzed The surface of sample 23.

The main functions of the CCD 10 are: together with the focusing objective lens 19, it constitutes a high-magnification observation system for the sample, which is used for observation and analysis of the surface topography of the sample. By changing the distance between the focusing objective lens 19 and the industrial CCD 10 , the magnification of the surface topography of the observed sample on the first display 32 can be changed.

The central positions of the industrial CCD 10 , the first total reflection mirror 7 , the second total reflection mirror 9 and the thin-walled plasma confinement mechanism 21 should be on the same axis. The optical system after the laser beam 6 is reflected by the first total reflection mirror 7 shares the optical path of the optical system of the observation part completely.

The grating spectrometer 27 mainly decomposes the plasma light into spectral lines of various elements, and the enhanced CCD 28 mainly amplifies the signals of the spectral lines.

The laser probe instrument micro-area component analysis process is as follows.

First is the preliminary analysis, triggering the switches of the first and second rotating electromagnets 16 and 36 makes the first and second total reflection mirrors 7 and 9 in the state of deviating from the optical path of the laser beam 6, when the analyzed sample 23 is placed on a two-dimensional numerical control machine tool 24, adjust the position of the two-dimensional numerical control machine tool 24 in the horizontal (x-y axis direction), the height of the focusing objective lens 19 on the microscopic observation assembly moving bracket 12 (z axis direction), and properly adjust the distance between the focusing objective lens 19 and the industrial CCD10 so that the sample surface is at the focal point of the observation system, the surface microscopic topography and structure of the sample material 23 can be observed and analyzed on the first display 32 . The optical path of the laser beam in the three-dimensional worktable and the LIBS system is precisely matched, and then aligned and locked to the micro-region of the sample to be analyzed.

After the characteristic micro-regions of the analyzed sample 23 are aligned and locked, the switch of the first rotating electromagnet 16 is triggered so that the first total reflection mirror 7 is located in the optical path of the laser beam 6 and forms an angle of 45 degrees with it, and the laser 1 is turned on. Make it emit a pulsed laser beam 6 with a wavelength of 532 nm. After the pulsed laser beam 6 is expanded by the beam expander 5, it is totally reflected on the reflective surface of the first total reflection mirror 7, and then focused on the sample 23 by the focusing objective lens 19 for ablation to generate plasma 22, and the plasma 22 is confined The mechanism 21 expands and diffuses, gradually cools down and releases the spectra of various elements. Since there is a certain delay in the generation of plasma 22, when the laser beam 6 is emitted immediately, the second rotating electromagnet 36 is triggered to make the second full The reflection mirror 9 returns to the reflection optical path of the sample 23, and the spectrum released by the plasma of various elements passes through the focusing objective lens 19 and is totally reflected on the reflection surface of the second total reflection mirror 9, enters the optical fiber probe 8, and is then coupled to At the receiving end of the optical fiber 25, the photon spectrum is input to the grating spectrometer 27 through the optical fiber 25, and the spectral signal is amplified through the enhanced CCD28, and then the relevant information is transmitted to the upper computer 29, and the upper computer 29 passes through the second display 30. The spectra of various wavelengths are displayed, and the various constituent elements of the sample are qualitatively analyzed by comparing the wavelengths of the spectra, thus completing the qualitative analysis of the composition of the micro-region of the sample.

On the basis of the preliminary qualitative analysis, if further precise quantitative analysis of some specific trace or even trace elements is required, a precise quantitative analysis method can be used. For specific implementation, the improved specific implementation as shown in Figure 3 is adopted. way of structure. Figure 3 mainly makes the following improvements on the basis of Figure 1. First, the laser 1 uses a wavelength-tunable laser, whose wavelength tuning range is 215nm-2550nm continuously adjustable, laser pulse width <10ns; single pulse pulse energy 10-50mJ, Pulse repetition frequency 10Hz. During the laser detection process, the wavelength of the laser beam is gradually tuned, multiple scans are completed and the relevant spectral signals are recorded; secondly, a small hole diaphragm is installed in the resonant cavity of the laser 1 or on the output optical path of the laser. In this example, the A pinhole diaphragm is installed in the cavity of the laser 1, and finally a half-wave plate 2, the first and second polarizers 3 and 4 are added in the optical path of the laser beam.

The wavelength tunable laser 1 selected in Fig. 3 can change the wavelength of the output laser beam 6, so that the wavelength matching the element to be analyzed can be selected in accurate quantitative detection, so as to maximize the excitation of the plasma of the element to be analyzed, that is, greatly The enhancement corresponds to the photon spectral signal of the element. Using the pinhole diaphragm, half-wave plate 2, polarizer 3 and 4 can make the output laser beam mode close to the ideal Gaussian 00 mode, and can better filter the laser beam.

By adopting the improved laser probe structure shown in Figure 3, the detection accuracy of trace or even trace elements can be greatly enhanced. The specific operation steps for precise quantitative analysis of micro-area characteristic elements are as follows:

First insert half-wave plate 2, polarizers 3 and 4 corresponding to the wavelength. Activating the switch of the second rotating electromagnet 36 makes the second total reflection mirror 9 deviate from the optical path of the laser beam 6 . Laser 1 selects the wavelength corresponding to trace and trace elements, so that the wavelength corresponding to trace and trace elements can be excited to the greatest extent, suppressing the influence of other elements on the wavelength of the element, and enhancing the spectral signal corresponding to trace and trace elements, and then Improve its detection accuracy. Then turn on the laser 1 and send the laser beam 6 through the mode selection of the pinhole diaphragm. The laser beam 6 is close to the Gaussian 00 mode. To be more ideal, after the beam expander 5, the diameter of the spot is enlarged several times, and at this time the second total reflection mirror 9 is in a position deviated from the optical axis of the laser beam 6, which has no influence on the transmission process of the laser beam 6. Therefore, the laser beam 6 is directly reflected at the first total reflection mirror 7 , then focused by the focusing objective lens 19 and directly bombards the micro-region of the analyzed sample 23 for ablation to generate plasma 22 . The confinement structure 21 at the laser beam exit can control the movement range of the generated plasma 22 within the detectable range, reduce its movement speed, and prolong its residence time in the detection area, thereby significantly improving the concentration of trace elements and trace elements. detection accuracy.

Instantly after the laser beam 6 is launched, the center of the second total reflection mirror 9 is returned to the optical path by triggering the second rotating electromagnet 36, and the light signal of the plasma 22 is reflected by the focusing objective lens 19 at the second total reflection mirror 9. After entering the optical fiber probe 8, then coupled to the receiving end of the optical fiber 25, the photon spectrum is input to the grating spectrometer 27 through the optical fiber 25, and the spectral signal is amplified by the enhanced CCD28, and then the relevant information is transmitted to the host computer 29, and by The host computer 29 displays the quantitative analysis results of the corresponding characteristic element spectra through the second display 30 .

The upper computer 29 can be connected with the signal acquisition and processing circuit of the enhanced CCD28 through a USB interface or a network cable by using a desktop computer or a notebook computer. The software of the computer has functions such as automatic scanning, searching for atomic spectrum peaks, qualitative identification and quantitative conversion calculation.

The operation analysis using the high-precision laser probe micro-area component analyzer provided by the present invention is divided into preliminary qualitative analysis and precise quantitative analysis. The specific preliminary qualitative analysis operation steps are as follows:

1. Set the control switches of the first and second rotating electromagnets 16 and 36 so that the first and second total reflection mirrors 7 and 9 are in the state of deviating from the optical path of the laser beam 6 . And the half-wave plate 2, polarizing plates 3 and 4 are extracted.

2. Fix the sample 23 to be analyzed on the two-dimensional numerical control machine tool 24, observe the surface of the sample 23 to be measured through the industrial CCD10 and the focusing objective lens 19, adjust the focusing objective lens 19 in the mobile support 12 of the two-dimensional numerical control machine tool 24 and the microscopic observation system The height of the sample to be analyzed is precisely positioned and locked;

3. Trigger the switch of the first rotating electromagnet 16 to move the first total reflection mirror 7 into the optical path of the laser beam 6 .

4. Turn on the laser 1 to emit a short-pulse, high-energy laser beam 6 with a wavelength of 532nm; the laser beam 6 is expanded by the beam expander 5, reflected at the first total reflection mirror 7, and then focused to the sample to be analyzed by the focusing objective lens 19 The surface of 23 ablates the micro-region of the sample to generate plasma.

5. The short-pulse high-energy laser rapidly heats the micro-area of the sample to a very high temperature, so that the micro-area is ablated and the plasma 22 is excited, and the moment the laser beam 6 is emitted, the trigger switch of the second rotating electromagnet 36 is turned on, so that The second total reflection mirror 9 is located in the reflection circuit of the sample 23, the plasma 22 is restricted by the confinement mechanism 21, the expansion and diffusion are restricted, and gradually cools down and releases the characteristic wavelength spectrum corresponding to the contained elements. The spectrum of the plasma 22 is After total reflection at the second total reflection mirror 9 , it enters the optical fiber probe 8 , and the optical fiber probe 8 transmits the collected spectral signals to the grating spectrometer 27 through the quartz optical fiber 25 .

6. The grating spectrometer 27 detects and analyzes the atomic and ion spectra excited by the laser, amplifies the detected spectral signals through the enhanced CCD 28 and converts them into electrical signals and transmits them to the host computer 29 for judgment and analysis.

7. The upper computer 29 compares and analyzes the collected spectral wavelengths with the spectral wavelengths of the elements in the spectral database, analyzes and determines the composition of micro-region elements, and displays them on the second display 30 . To achieve the purpose of qualitative analysis of micro-area elements.

After the qualitative analysis, when it is necessary to further accurately analyze the specific trace and trace elements contained in the sample, the quantitative analysis operation is used. The specific quantitative analysis operation steps are as follows:

8. For the selected element, set the laser 1 to adopt the laser beam wavelength corresponding to the micro and trace elements. Insert the half-wave plate 2, polarizer 3 and 4 corresponding to the wavelength of trace and trace elements.

9. Trigger the switch of the second rotating electromagnet 36 to make the second total reflection mirror 9 deviate from the optical path of the laser beam.

10. Start the laser 1 to emit laser pulses. After the laser beam 6 is filtered by the half-wave plate 2, the polarizer 3 and 4, the beam is expanded at the beam expander 5, and then it is totally reflected on the reflection surface of the total reflection mirror 7 and passes through the The focusing objective 19 is focused on the sample 23 . The micro-regions of the sample are ablated on the surface of the analyzed sample 23 .

11. The laser beam 6 of the corresponding wavelength can generate tuned excitation with the corresponding element, so that trace and trace elements can be excited to the maximum. The sample domain will be rapidly heated to a very high temperature, and the plasma 22 will be excited.

12. At the moment when the laser beam 6 is emitted, turn on the trigger switch of the second rotating electromagnet 36, so that the second total reflection mirror 9 is located in the reflection circuit of the sample 23, the plasma 22 is restricted by the restraint mechanism 21, and the expansion and diffusion are restricted , and gradually cool down and release the characteristic wavelength spectrum corresponding to the contained elements. The spectrum of the plasma 22 enters the optical fiber probe 8 after total reflection at the second total reflection mirror 9, and the optical fiber probe 8 passes the collected spectral signal through the quartz optical fiber 25 is transmitted to a grating spectrometer 27.

13. The grating spectrometer 27 detects and analyzes the laser-excited atomic and ion spectra, amplifies the detected spectral signals through the enhanced CCD 28 and converts them into electrical signals and transmits them to the host computer 29 for judgment and analysis.

14. Quantitatively calculate the content of the collected spectrum by the host computer 29 through computer software, and display it.

Through the above steps, a qualitative analysis of fixed-point components and a quantitative analysis of specific trace and trace elements of the laser probe composition analyzer are completed. When it is necessary to continue to further analyze other trace and trace elements, adjust the laser The wavelength of 1 is matched with the wavelength of the element to be measured, and a half-wave plate and polarizer matching the wavelength are inserted at the same time, and then precise quantitative analysis is performed. When it is necessary to detect other characteristic micro-regions, the laser probe device can be moved along the surface contour of the sample through the linkage control of the x, y, and z axes to complete the composition analysis of the micro-regions in different parts of the sample.

When performing line-scan and surface-scan analysis on the chemical composition of the surface, the program should first be programmed according to the surface morphology of the sample, the area and path of the micro-area required for qualitative or quantitative analysis, and the laser wavelength of the tunable laser should be paid attention to when programming , laser power, output mode, pulse repetition frequency and the matching of the moving speed of the two-dimensional CNC machine tool. The high-power pulsed laser beam output by the laser is coordinated with the movement of the worktable and the spectral analysis process to complete the line-scanning and surface-scanning component analysis of the sample surface.

The present invention can also adopt the embodiment shown in Figure 4, for example can move the second rotating electromagnet 36, the second total reflection mirror 9 between the first total reflection mirror 7 and the industrial CCD10, and the second total reflection The reflective surface of the mirror 9 and the reflective surface of the first total reflection mirror 7 are installed at an angle of 90 degrees, and are fixed on the fixed bracket of the microfocus system. The fiber optic probe 8 is installed horizontally on the fixed bracket of the microfocus system, and is the same as the optical axis of the reflected light path of the second total reflection mirror 9 . Also can adopt the embodiment shown in Figure 5, the rotating electromagnet 36, the second total reflection mirror 9 are moved between the beam expander mirror 5 and the first total reflection mirror 7, and the first total reflection mirror 7 and the second total reflection mirror The total reflection mirror 9 is installed in parallel, and the fiber optic probe 8 is above the second total reflection mirror 9 . Can also adopt the embodiment shown in Figure 5, the rotating electromagnet 36, the second total reflection mirror 9 are moved between the beam expander mirror 5 and the first total reflection mirror 7, and the first total reflection mirror 7 and the second total reflection mirror The total reflection mirror 9 is installed in parallel, and the fiber optic probe 8 is above the second total reflection mirror 9 .

For samples with complex shapes, a small rotatable worktable can also be added to the two-dimensional CNC machine tool. It can rotate with the A axis parallel to the x axis or the B axis parallel to the y axis as the rotation axis, and with x-y-z three The movement linkage of three axes becomes a five-axis linkage system, so the incident direction of the laser beam can always be perpendicular to the analyzed surface of the sample, ensuring the intensity and analysis accuracy of the collected plasma photoelectric signal.

The three-dimensional workbench can also directly adopt the three-dimensional numerical control machine tool. In addition, the upper computer and the lower computer in the present invention can be combined, that is, all the functions of the upper computer and the lower computer can be completed by one computer, for example, when it is necessary to observe the surface of the micro-region of the material, through the display of the computer Display; when it is necessary to analyze the substance, the spectrum of the element can be displayed by switching the interface on the display, or the observation image of the sample and the spectrum of the element can be displayed on the display at the same time through the method of split-screen display.

The laser probe instrument manufactured according to the present invention can reach the highest ppm level of analysis accuracy of material components, and the minimum spatial resolution can reach 1 micron, making the device a high detection accuracy, large-scale range, no need for vacuum, and accurate phase analysis Multifunctional Laser Probe Composition Analyzer.

The laser probe micro-area component analyzer of the present invention has the function of precise detection of material micro-areas, and has a high positioning and alignment degree for material micro-areas, and can perform micro-area composition analysis on the surface morphology and microstructural characteristics of the object phase. Accurate quantitative analysis meets the chemical composition and phase analysis requirements of large metal parts, ceramic parts, and polymer material parts.

The present invention can also directly adopt the analyzer with the structure shown in Fig. 3, Fig. 4 or Fig. 5 for qualitative analysis.

The above description is only a preferred embodiment of the present invention, but the present invention should not be limited to the content disclosed in this embodiment and the accompanying drawings. Therefore, all equivalents or modifications that do not deviate from the spirit disclosed in the present invention fall within the protection scope of the present invention.

Claims (10)

1. A laser probe micro-area component analyzer, characterized in that: The laser (1), the beam expander (5) and the first total reflection mirror (7) are successively located on the same horizontal optical path, and the angle between the reflection surface of the first total reflection mirror (7) and the horizontal optical path is 45 degrees; The laser (1) is a tunable pulse laser, and the laser (1) has a small hole diaphragm inside or its light outlet is provided with a small hole diaphragm; Industrial CCD (10) is positioned at the top of the first total reflection mirror (7), and the first focusing objective lens (19) is positioned at the first total reflection mirror (7) below, and the light of the first focusing objective lens (19) and industrial CCD (10) Axis coincidence; The worktable of the three-dimensional workbench is located below the first focusing objective lens (19), for placing the sample (23); The second total reflection mirror (9) is movably installed on the reflection light path of the sample (23), and the fiber optic probe (8) is located on the reflection light path of the second total reflection mirror (9); The industrial CCD (10) is connected with the computer with display through the optical fiber, and the optical fiber probe (8) is connected with the grating spectrometer (27) and the enhanced CCD (28) successively through the optical fiber (25), and the latter is connected with the computer through the coaxial cable . 2. laser probe micro-area component analyzer according to claim 1, is characterized in that: half-wave plate (2) and first, first, A second polarizer (3, 4). 3. laser probe micro-area component analyzer according to claim 2, is characterized in that: laser device (1), half-wave plate (2), first and second polarizer (3,4), beam expander (5) installed on the substrate (13); Described three-dimensional workbench comprises two-dimensional numerical control machine tool (24) and mobile support (12); Lens frame turntable (17) is installed in the bottom of mobile support (12), and the first focusing objective lens (19) is installed in lens support turntable (17) ), the lens holder turntable (17) is also equipped with a spare focusing objective lens; the mobile bracket (12) is installed on the side of the base plate (13) by a screw mandrel and a guide rail (14), and the motor (15) is connected with the screw mandrel and the guide rail (14) ) connected. the 4. The laser probe micro-area component analyzer according to claim 1 or 2, characterized in that: a constraining mechanism (21) is installed below the first focusing objective lens. 5. laser probe micro-area component analyzer according to claim 4, is characterized in that: constraint mechanism (21) is thin-walled cylindrical member or is made up of parallel two thin-walled, 6 . The laser probe micro-area component analyzer according to claim 5 , characterized in that: the material used for the constraining mechanism ( 21 ) is a magnetic material. 7. according to the arbitrary described laser probe microarea composition analyzer of claim 1 to 3, it is characterized in that: the second total reflection mirror (9) is movable and positioned at the first total reflection mirror (7) and the first focusing objective lens ( 19) or the industrial CCD (10), the included angle between the reflection surface of the second total reflection mirror (9) and the reflection surface of the first total reflection mirror (7) is 90 degrees. 8. according to the laser probe micro-area component analyzer described in any one of claims 1 to 3, it is characterized in that: the second total reflection mirror (9) is movably placed in the beam expander mirror (5) and the first total reflection mirror Between (7), the angle between the reflective surface of the second total reflection mirror (9) and the horizontal optical path is 45 degrees. 9. The laser probe micro-area component analyzer according to claim 7, characterized in that: the first and second total reflection mirrors (7, 9) pass through the first and second rotating electromagnets (16, 36) respectively Install. 10. The laser probe micro-area component analyzer according to claim 8, characterized in that: the first and second total reflection mirrors (7, 9) pass through the first and second rotating electromagnets (16, 36) respectively Install. the

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