CN115684329A - Multi-wavelength laser coaxial micro-area in-situ ablation sampling system - Google Patents

Abstract

The invention discloses a multi-wavelength laser coaxial micro-area in-situ ablation sample injection system, wherein a multi-wavelength laser of the system is provided with a plurality of light outlets for outputting a plurality of paths of lasers with different wavelengths; a beam expander is arranged in front of each light outlet, and the expanded multi-path laser passes through a beam splitter or a reflector and the beam splitter and then is superposed on the same optical axis and is focused by a focusing mirror; the denudation pool is positioned on the three-dimensional moving platform and is internally provided with a sample; the three-dimensional moving platform and the camera are both connected with the machine vision control module, and the machine vision control module controls the three-dimensional moving platform to move to realize that the laser focus is arranged at the selected position on the surface of the sample so as to complete the automatic focusing of the ablation laser, the free selection and the automatic adjustment of the ablation point position; the carrier gas device is communicated with the denudation pool to realize aerosol particle transmission. The invention can make the multi-light path laser realize the output of multiple wavelengths by a single light path, and realize the automatic focusing ablation and the micro-area in-situ ablation sample injection of the sample.

Description

Multi-wavelength laser coaxial micro-area in-situ ablation sampling system

technical field

The invention belongs to the field of geochemical analysis, and in particular relates to a multi-wavelength laser coaxial micro-area in-situ ablation sampling system.

Background technique

Laser ablation system is an important part of laser ablation inductively coupled plasma mass spectrometry elemental analysis technology, combined with mass spectrometry analysis technology can realize micro-area, in-situ, rapid elemental detection and isotope analysis. The laser ablation system focuses a high-energy short-pulse or ultrashort-pulse laser on the surface of a solid material sample, and a small amount of sample is ablated to form aerosol particles under inert gas conditions, which are transported to the ionization device by the carrier gas to complete the sampling of the sample. Transport and ionization. However, some lasers can only output laser pulses of different wavelengths through multiple light outlets. When using lasers with different wavelengths, it is necessary to frequently adjust the optical path or build multiple optical paths to meet the research needs, making the entire laser ablation system cumbersome and complicated.

At present, geochemical analysis, especially solid micro-area geochemical analysis technology, relies on the combination of laser ablation sampling system and plasma mass spectrometer, which can measure the element and isotope content or ratio of the sample. In the laser ablation system, the laser wavelength often affects the experimental results as an important parameter. For example, in the laser ablation inductively coupled plasma mass spectrometry elemental analysis technology, the laser wavelength affects the single-photon energy and the degree of light absorption of the material, resulting in ablation depth, Changes in sample surface temperature, ablation speed, aerosol composition, etc. will affect the analysis signal sensitivity during micro-area analysis, and because the spatial position of the ablated sample and the ablation laser light path is fixed, the operation of switching wavelengths when using a multi-channel laser is too cumbersome , and it is easy to change the optical path conditions to affect the stability of the test; the focus of the ablation laser needs to accurately control the height of the sample, and the micro-area analysis needs to accurately locate the sampling point, and it is too difficult to manually complete the above precise operations.

Contents of the invention

The purpose of the present invention is to provide a multi-wavelength laser coaxial micro-area in-situ ablation sampling system, so that the multi-optical path laser can output multiple wavelengths in a single optical path, and realize automatic focus ablation and in-situ micro-area ablation of the sample. Sample.

In order to achieve the above object, the technical solution of the present invention is:

A multi-wavelength laser coaxial micro-area in-situ ablation sampling system, the system includes a multi-wavelength laser, a beam expander, a reflector, a beam splitter, a focusing mirror, an ablation pool, a three-dimensional mobile platform, a camera, and a machine vision control module and gas carrier;

Among them, the multi-wavelength laser is equipped with multiple light outlets for outputting multiple lasers of different wavelengths; each light outlet is equipped with a beam expander, and the expanded multi-channel laser passes through the reflector and the beam splitter twice. The reflections coincide on the same optical axis and are focused by the focusing mirror;

The ablation pool is located on the three-dimensional mobile platform with built-in samples; both the three-dimensional mobile platform and the camera are connected to the machine vision control module, and the machine vision control module controls the movement of the three-dimensional mobile platform so that the laser focus is placed on the selected position on the sample surface to complete Automatic focusing of ablation laser and in-situ ablation sampling of micro-areas;

The carrier gas device is connected to the denudation pool to realize micro-area in-situ denudation sampling.

Further, according to the user's ablation of different types of solid samples, laser pulses with different wavelengths and coaxial transmission are selected for ablation sampling.

Further, the beam expander is a high-magnification beam expander, and the beam splitter is a high-performance long-wave transparent, short-wave reflective or short-wave transparent, long-wave reflective beam splitter.

Furthermore, the machine vision control module realizes self-focusing of lasers with different wavelengths on the sample surface and automatic selection and positioning of ablation points.

Further, the system also includes a filter; the laser light coincident on the same optical axis is focused on the surface of the sample through the climbing frame equipped with reflectors and focusing mirrors and the glass window in turn, and the reflected light is sequentially passed through the window, focusing mirror, and splitter. Beam mirrors and filters enter the camera.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

The present invention adopts the combination of optical elements such as a beam expander, a beam splitter, and a reflector, so that the lasers of different wavelengths can be coaxial, so that a single optical path can output multi-wavelength laser pulses, and the wavelength of the ablation laser can be switched efficiently and conveniently. According to the light absorption characteristics of the material, select the appropriate wavelength to improve the ablation efficiency; short pulse or ultrashort pulse laser focus ablation, combined with precise movable platform, CCD camera and machine vision control module, can realize laser self-focusing; combined with The airtight denudation cell connected with the carrier gas device can realize micro-area in-situ sampling and injection of the sample, which helps to achieve high-resolution and high-sensitivity chemical analysis. The system is compact, fast and convenient, and is helpful for high-resolution and high-sensitivity element and isotope analysis. Therefore, the multi-wavelength laser coaxial micro-area in-situ ablation sampling system has important and wide applications in the fields of geoanalytical chemistry and other fields. prospect.

Description of drawings

Fig. 1 is a schematic structural view of the multi-wavelength laser coaxial micro-area in-situ ablation sampling system of the present invention.

In the figure: 1-laser, 2-light outlet, 3-beam expander, 41-first harmonic beam splitter, 42-second harmonic beam splitter, 43-third harmonic beam splitter, 51- First reflector, 52-second reflector, 53-third reflector, 54-fourth reflector, 6-focusing mirror, 7-filter, 8-ablation cell, 9-sample, 10-three-dimensional moving platform , 11-camera, 12-computer, 13-intake pipe, 14-outlet pipe, 15-window.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not constitute a conflict with each other.

The invention provides a set of multi-wavelength laser optical path coaxial output method and laser micro-area in-situ ablation sampling system, which can combine multiple output lasers to easily switch the wavelength of ablation laser; and through a set of machine vision Self-focusing system, including movable precision platform, CCD (charge coupled device) camera and machine vision control software on computer, can realize automatic focusing of ablation laser and observation and selection of ablation position; combined with airtight ablation with carrier gas The pool can complete micro-area in-situ ablation and sample injection operations. The inventive system is compact in structure, fast and convenient, and contributes to high-resolution and high-sensitivity element and isotope analysis.

The multi-wavelength laser optical path coaxial in-situ ablation sampling system of the present invention can realize different multi-wavelength short-pulse or ultrashort-pulse laser coaxiality according to specific conditions and requirements, and complete micro-area in-situ sampling and sample introduction. In the present invention, high-power beam expanders are used to expand the beams of different light outlets of the laser, and then the reflective mirror and the harmonic beam splitter are used to reflect twice to make the different laser light paths coincide. By selecting a suitable beam splitter and adjusting the reflection The angle of laser pulses with different wavelengths can be on the same optical axis; then the laser light path can be climbed through the reflector, and then the laser can be focused by the focusing mirror; the precise three-dimensional mobile platform can be made by combining the CCD camera with the machine vision control software Automatically adjust the position of the sample space, so that the laser focus is placed on the selected position on the upper surface of the sample to complete the in-situ ablation sampling of the micro-area; and then the aerosol generated by the ablation can be transmitted through the closed ablation pool and the carrier gas device to complete all the samples. process. The laser optical path system in the present invention only needs to combine standard optical elements such as beam expander, beam splitter and reflector, so that the multi-optical path laser can output multiple wavelengths in a single optical path, and realize automatic focus ablation and micro-area of the sample. In-situ ablation sampling is helpful for high-resolution and high-sensitivity analysis of elements and isotopes, with convenient installation and adjustment, simple structure, wide applicability and good repeatability.

The invention plays an important role in the fields of geochemical analysis and the like, and can complete the micro-area in-situ ablation, sampling and sample feeding operations of required multi-wavelength lasers on samples. On the one hand, laser wavelength as an important parameter affects the sampling performance of laser ablation, including the size and distribution of particles (aerosols) of ablation products, the ablation threshold for the same matrix material, ablation depth, ablation speed, etc., and some common short-term Pulse or ultra-short pulse lasers output lasers of different wavelengths through different frequency-doubling optical paths, making it difficult for a single optical path to pass through lasers of different wavelengths. It is cumbersome and difficult to switch ablation lasers of different wavelengths in scientific research applications. This invention can effectively solve the problem. The problem that lasers with different wavelengths cannot be output coaxially avoids repeated construction of optical paths and readjustments when switching laser wavelengths; An important part, the present invention combines short pulse (or ultrashort pulse) laser ablation, a movable precision platform, a CCD camera, machine vision control software and a complete system composed of a closed ablation pool connected with carrier gas, which can realize laser self-focusing It also automatically completes the in-situ sampling and injection functions of the micro-area, which has an important role and broad application prospects in the fields of geochemical analysis and other fields.

As shown in Figure 1, the output wavelengths of short pulse and ultrashort pulse laser 1 under different frequency doubling conditions range from infrared, visible to ultraviolet, such as 1064nm, 1030nm, 800nm, 532nm, 515nm, 400nm, 355nm, 193nm, etc. The present invention can be applicable (only need to choose suitable element). Taking the common Nd:YAG nanosecond laser as an example, the three light outlets 2 respectively output lasers with three different wavelengths: tripled frequency 355nm laser, fundamental frequency 1064nm laser and doubled frequency 532nm laser. The high-power beam expander 3 expands its beam, and outputs 355nm laser, 1064nm laser and 532nm laser after beam expansion. After the beam expansion, the 532nm laser passes through the first harmonic beam splitter 41 and the second harmonic beam splitter 42 and then continues to be output to the subsequent optical path; Harmonic beam splitter 41 turns the optical path, and achieves coaxiality with the 532nm laser optical path; after beam expansion, the 1064nm laser turns the optical path through the second reflector 52, and then passes through the second harmonic beam expander 42 to turn the optical path, and realizes the optical path with the 532nm laser coaxial. By controlling the working state of the laser, a 355nm laser, a 532nm laser or a 1064nm laser can be respectively output on the same channel; then the 355nm, 532nm and 1064nm lasers are all reflected by the third reflector 53 and the fourth reflector 54 to realize the optical path climbing, and then Reflected by the third harmonic beam splitter 43, it is focused vertically downward through the focusing mirror 6 on the surface of the sample to complete the ablation.

The sample 9 is placed in the airtight cavity of the denudation pool 8 on the precise three-dimensional mobile platform 10, the bottom of the denudation pool 8 is fixed with the precise three-dimensional mobile platform 10, and the window 15 is set above the denudation pool 8 to load optical glass (such as calcium fluoride glass, etc.) so that The laser light passes through; the reflected light passes through the window 15 and the third harmonic beam splitter 33 upwards, and then passes through the filter 7 to filter out the laser light, so that the CCD camera 11 can obtain a high-definition image in the erosion pool 8; the CCD camera 11 converts the image data It is transmitted to the computer 12, and then the machine vision software recognizes and transmits the control signal to the precise three-dimensional mobile platform 10, so as to automatically realize the precise focus of the laser on the surface of the sample. At the same time, accurately locate the denuded position, that is, to realize in-situ sampling of the micro-area of the sample. An air inlet and an air outlet are arranged on both sides of the denudation pool, and the air inlet pipe 13 and the air outlet pipe 14 are respectively connected to realize the aerosol transmission after sampling, that is, the sampling operation.

In summary, the present invention uses a combination of optical elements such as a beam expander, a beam splitter, and a reflector to coaxially align lasers of different wavelengths so that a single optical path can output multi-wavelength laser pulses, which can efficiently and conveniently switch ablation The wavelength of the laser, according to the light absorption characteristics of the material, select the appropriate wavelength to improve the ablation efficiency; short pulse or ultrashort pulse laser focus ablation, combined with precise movable platform, CCD camera and machine vision control software, can realize laser automatic Focusing; combined with a closed denudation cell connected with a carrier gas, it can realize micro-area in-situ sampling and injection of samples, which helps to achieve high-resolution and high-sensitivity chemical analysis. The invention can quickly and conveniently realize the functions of fast switching of laser wavelength, self-focusing of ablation laser and in-situ sampling and feeding of micro-regions at low cost.

Those skilled in the art can easily understand that the above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be Included within the protection scope of the present invention.

Claims (5)

1. A multi-wavelength laser coaxial micro-area in-situ ablation sample introduction system is characterized in that the system includes a multi-wavelength laser, a beam expander, a reflector, a beam splitter, a focusing mirror, an ablation pool, a three-dimensional mobile platform, Cameras, machine vision control modules and gas-carrying devices; Among them, the multi-wavelength laser is equipped with multiple light outlets for outputting multiple laser beams of different wavelengths; each light outlet is equipped with a beam expander, and the multi-channel laser after beam expansion passes through a beam splitter or reflector, beam splitter, etc. The mirrors coincide on the same optical axis and are focused by the focusing mirror; The ablation pool is located on the three-dimensional mobile platform with built-in samples; the three-dimensional mobile platform and the camera are connected to the machine vision control module, and the machine vision control module controls the movement of the three-dimensional mobile platform to place the laser focus on the selected position on the sample surface, and realize The ablation point can be freely selected and positioned to complete the automatic focus of the ablation laser and the in-situ ablation sampling of the micro area; The carrier gas device is connected to the denudation pool to realize micro-area in-situ denudation sampling. 2. The multi-wavelength laser coaxial micro-area in-situ ablation sampling system according to claim 1, characterized in that, according to the user's ablation of different types of solid samples, laser pulses with different wavelengths and coaxial transmission are selected for ablation sampling. 3. The multi-wavelength laser coaxial micro-area in-situ ablation sampling system according to claim 1, wherein the beam expander is a high-magnification beam expander, and the beam splitter is a high-performance long-wave transmission, short-wave reflection or short-wave Transmissive, long-wave reflective beamsplitters. 4. The multi-wavelength laser coaxial micro-area in-situ ablation sampling system according to claim 1, characterized in that the machine vision control module realizes self-focusing of different wavelength lasers on the sample surface and automatic selection and positioning of ablation points. 5. The multi-wavelength laser coaxial micro-area in-situ ablation sampling system according to claim 1 is characterized in that the system also includes a filter; The climbing frame of the focusing mirror and the glass window focus on the sample surface, and the reflected light enters the camera through the window, focusing mirror, beam splitter and filter in turn.

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