CN112025100B

CN112025100B - Laser ablation method and device

Info

Publication number: CN112025100B
Application number: CN202010917417.XA
Authority: CN
Inventors: 高剑峰
Original assignee: Institute of Geochemistry of CAS
Current assignee: Institute of Geochemistry of CAS
Priority date: 2020-09-03
Filing date: 2020-09-03
Publication date: 2021-09-17
Anticipated expiration: 2040-09-03
Also published as: CN112025100A

Abstract

The invention discloses a laser ablation method, which adopts nonlinear laser to ablate a sample. The invention also discloses a laser ablation device adopting the laser ablation method, which comprises a laser emitting component for emitting the nonlinear laser, a light path system for the nonlinear laser to pass through and an ablation pool for ablating a sample by utilizing the nonlinear laser. The invention uses the nonlinear laser as a laser source, and achieves the maximum power density at the focal point by utilizing the self-focusing of the nonlinear laser, thereby leading the laser energy to be concentrated in a specific depth in a sample. The invention takes nonlinear laser ablation as a basis, reduces the influence of host mineral ablation on fluid inclusion analysis to the maximum extent, and realizes high-precision analysis of fluid inclusion components.

Description

Laser ablation method and device

Technical Field

The invention relates to the field of laser ablation analysis, in particular to a laser ablation method and a laser ablation device.

Background

The laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS) can realize the measurement of micron-scale element-isotope and the high-precision in-situ determination of geological age, thereby becoming one of the most common and leading-edge analysis techniques in the current solid earth science research. The principle of the laser ablation-inductively coupled plasma mass spectrometry is that a laser generator generates high-energy laser to act on the surface of a geological sample, so that the geological sample is decomposed into micro-particle particles, then a carrier gas (such as helium) is used for transporting the ablated particles to an inductively coupled plasma mass spectrometer in an aerosol form, and the aerosol is ionized into ions through high-temperature plasma and then the mass spectrometry is used for quantitative analysis of elements and isotopes. The laser ablation system is used as a sampling part of the analysis method, and directly influences the analysis result on the ablation mode and efficiency of the sample.

At present, all laser ablation systems applied to earth science research can only carry out gradual ablation from the outside to the inside on geological samples, and can not realize host-free mineral interference sampling on certain special research objects such as fluid inclusion in minerals, thereby greatly restricting the high-precision research on geological fluids, particularly mineral-forming fluids. Because the laser ablation system can only carry out gradual ablation from the outside to the inside, the signal of the fluid inclusion is seriously interfered by host minerals, particularly the elements of the fluid inclusion in minerals with complex components can not be detected or the detection limit is increased due to the interference of the host minerals, and the application range and the analysis precision of the laser ablation-inductive coupling plasma mass spectrometry of the fluid inclusion are greatly restricted.

Disclosure of Invention

Therefore, the invention provides a laser ablation method and a device thereof, aiming at solving the technical problem that the existing laser ablation system can only carry out gradual ablation from the outside to the inside and can be interfered by host minerals.

Therefore, the invention adopts the following technical scheme:

the invention provides a laser ablation method, which is characterized in that a sample is ablated by adopting nonlinear laser, the focus of the nonlinear laser is concentrated in the sample, and fixed-point focusing and blasting are carried out in the sample.

Further, the air conditioner is provided with a fan,

and adjusting a laser light path according to different samples, wherein the pulse width of nonlinear laser is less than 1ns, the wavelength is less than 1100nm, the frequency is 1-50000 Hz, the power is 0-15W, the ablation depth of the sample is 1-20 mu m, and the ablation time is 5-40 s.

The invention also provides a laser ablation device adopting the laser ablation method, which comprises

The laser emission assembly is used for emitting nonlinear laser, and comprises a nonlinear laser and an energy controller for adjusting the energy of the nonlinear laser, wherein the energy controller is arranged on one side of the nonlinear laser;

an optical path system for the nonlinear laser to pass through; and

and the nonlinear laser is injected into the sample cell through the optical path system.

Further, the optical path system comprises a sealed shell, a laser inlet for the nonlinear laser to enter and a laser outlet for the nonlinear laser to exit are respectively arranged on the sealed shell, and protective gas is filled in the sealed shell.

The optical path system further comprises a plurality of laser adjusting mirrors arranged in the sealed shell, the laser adjusting mirrors face the nonlinear laser and reflect the nonlinear laser to face another laser adjusting mirror or a laser outlet, and meanwhile, the laser adjusting mirrors are further used for adjusting the length of the optical path to enable the nonlinear laser to be capable of denudated at the specified depth of the sample.

And a gas control system for controlling the protective gas is further arranged on one side of the sealing shell and is communicated with the sealing shell.

And a slit is arranged on the outer side of a laser outlet of the light path system and used for adjusting the size of a laser beam spot.

Further, the ablation cell includes:

the device comprises a sample cell for containing a sample, and a lens group arranged above the sample cell and used for converging the nonlinear laser, wherein the lens group faces the sample cell.

The denudation pool further comprises:

the sample control platform is arranged below the sample pool and used for controlling the horizontal movement of the sample pool; and

and the control devices are arranged on two sides of the sample console and are used for controlling the movement of the sample pool in the vertical direction.

The denudation pool further comprises: and a light source for illuminating the sample is arranged right below the sample cell.

Preferably, the light source is a red-natural light double light source

The observation system comprises a laser reflector for reflecting the nonlinear laser to the sample and a camera and/or an ocular lens facing the laser reflector, wherein the laser reflector can be penetrated by the light emitted by a lower light source, so that the camera and/or the ocular lens can observe the sample

Preferably, the camera is an infrared camera.

The gas control system can also accurately control the flow of the laser gas and the sample carrier gas through different gas flow controllers.

The laser ablation device can further comprise a circuit control system and a safety protection system, wherein the circuit control system can adopt a distributed and modularized design, and a central controller controls the nonlinear laser, the sample console, the control device and the like; the safety protection system includes an automatic protection switch, which can safely protect against a possible malfunction or accident. The intelligent operation can be realized through the gas circuit control system, the safety protection system and the like, one-key processing operation is realized on different minerals, the laser energy is automatically optimized, accurate fixed-point sample denudation is realized, meanwhile, the automatic operation is supported, and unmanned analysis is realized.

The technical scheme of the invention has the following advantages:

(1) the invention uses the nonlinear laser as the laser source, the fast laser generated by the femtosecond or picosecond laser has obvious nonlinear effect, different from the conventional linear laser, the nonlinear laser can generate self-focusing when passing through a sample if the laser energy is higher than the threshold value of the sample, and the maximum power density is reached at the focus, so that the laser energy is concentrated in the sample at a specific depth.

(2) The invention takes nonlinear laser ablation as a basis, carries out accurate positioning ablation on the fluid inclusion in the mineral, can focus and heat and open the fluid inclusion at fixed points under the condition of not or little host mineral ablation, furthest reduces the influence of host mineral ablation on fluid inclusion analysis, and realizes high-precision analysis of the fluid inclusion components.

(3) The bottom of the denudation pool is provided with the high-precision vertical direction movement control device, so that the height of the denudation pool can be controlled, the precision of the focusing depth of a sample is controlled to be 0.5 micron grade, and the internal fixed point heating of minerals is realized.

(4) The denudation pool is provided with an infrared-visible light double light source, and can identify and position fluid inclusion in semitransparent and opaque minerals by matching with a CCD camera with an infrared camera shooting function, so that the effect of monitoring the whole denudation process is achieved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

Fig. 1 is a schematic structural view of a nonlinear laser ablation apparatus according to embodiment 2 of the present invention;

FIG. 2 is a photograph showing a zincblende sample when the nonlinear laser ablation apparatus of example 1 was used to ablate in example 3 of the present invention;

FIG. 3 is a diagram of an element signal collected by an inductively coupled plasma mass spectrometry when a zincblende sample is ablated by using the nonlinear laser ablation apparatus of example 1 in example 3 of the present invention;

FIG. 4 is a diagram of the element signals collected by the inductively coupled plasma mass spectrometry when the linear laser ablation device is used for ablating the sphalerite sample in the comparative example of the invention.

Reference numerals:

1-nonlinear laser; 2-a non-linear laser; 3-an energy controller; 4-an optical path system; 5-a slit; 6-denudation pool; 7-a viewing system; 8-a gas control system; 9-a circuit control system; 10-a safety protection system;

41-laser adjusting mirror;

61-sample cell; 62-sample console; 63-a control device; 64-a light source; 65-lens group;

71-laser mirror; 72-a camera; 73-eyepiece.

Detailed Description

The following examples are provided to further understand the present invention, not to limit the scope of the present invention, but to provide the best mode, not to limit the content and the protection scope of the present invention, and any product similar or similar to the present invention, which is obtained by combining the present invention with other prior art features, falls within the protection scope of the present invention.

The examples do not show the specific experimental steps or conditions, and can be performed according to the conventional experimental steps described in the literature in the field.

The following specific examples are further illustrative of the present invention, and the examples do not exemplify all the embodiments of the present invention, but only some of the embodiments are exemplified, and the specific examples are as follows:

example 1

The embodiment provides a laser ablation method, which comprises the following steps:

s1, cleaning the sample to be tested, determining the position of the sample to be corroded, and then placing the sample into a sample pool;

and S2, eroding the sample by using a nonlinear laser, wherein the nonlinear laser focuses on the inside of the sample, and fixed-point focusing and blasting are carried out on the inside of the sample.

Wherein, the laser light path is adjusted according to different samples, the nonlinear laser pulse width is less than 1ns, the wavelength is less than 1100nm, the frequency is 1-50000 Hz, the power is 0-15W, the ablation depth of the sample is 1-20 μm, and the ablation time is 5-40 s.

And S3, observing the denudation process in the whole process through a camera and/or an eyepiece, simultaneously acquiring denudation signals through equipment such as an inductively coupled plasma mass spectrometer and the like, and analyzing the denudation process and the denudation results.

The invention uses a nonlinear laser as a laser source, utilizes the nonlinear effect of fast laser, can generate self-focusing when laser energy is higher than the threshold value of a sample when passing through the sample, and reaches maximum power density at the focal point, so that the laser energy is concentrated in the sample at a specific depth, thereby accurately positioning and eroding a fluid inclusion in minerals, and can focus and heat and open the fluid inclusion at a fixed point under the condition of not eroding or little eroding host minerals, thereby furthest reducing the influence of host mineral erosion on fluid inclusion analysis and realizing high-precision analysis of fluid inclusion components.

Example 2

The present invention provides a nonlinear laser ablation apparatus, as shown in fig. 1, using a nonlinear laser 2 as a laser source.

The laser ablation device comprises a laser emitting component, an optical path system 4, an observation system 7 and an ablation pool 6, wherein nonlinear laser 1 emitted by the laser emitting component enters the ablation pool 6 after being adjusted by the optical path system 4, samples in the ablation pool 6 are subjected to laser ablation, then the samples in the ablation pool 6 are observed through the observation system 7, and the state of the laser ablation is observed.

The laser emission component comprises a nonlinear laser 2 and an energy adjuster 3 for adjusting the energy of the nonlinear laser, wherein the energy adjuster 3 is arranged on one side of the nonlinear laser 2. The nonlinear laser 2 can emit nonlinear laser 1, which can generally adopt a femtosecond laser or a picosecond laser, and laser ablation is carried out by utilizing the nonlinear laser 1 in the femtosecond laser or the picosecond laser.

Although some of the prior art uses femtosecond laser or picosecond laser for ablation, it only uses the characteristics of high stability and high energy. In the application, the nonlinear effect of the fast laser is utilized, so that the fixed-point focusing and blasting effects are performed in the sample.

The main function of the energy adjuster 3 is to adjust the energy in the nonlinear laser light 1 emitted by the nonlinear laser 2 so that it can just reach the effect of the capability threshold of the sample to be ablated. Preferably, an attenuator is generally used for the energy adjuster 3, so that when the energy of the laser emitted by the nonlinear laser 2 is too high, the energy can be attenuated to a certain extent, so that the transmission stability in the optical path system 4 is higher. Of course, according to practical situations and specific needs, in other embodiments of the present invention, the energy regulator 3 may also employ other frequency multipliers, such as a booster for boosting the laser energy emitted by the nonlinear laser 2, which is not limited herein.

For the optical path system 4, the nonlinear laser 1 is used to pass through, that is, the nonlinear laser 1 can be transmitted inside the optical path system 4, and meanwhile, the optical path system 4 can extend the length of the nonlinear laser 1 reaching the ablation pool 6, so that the nonlinear laser can realize accurate focusing, and a fixed-point blasting ablation effect is achieved.

The optical path system 4 is a sealed housing, a laser inlet through which the nonlinear laser 1 is injected and a laser outlet through which the nonlinear laser 1 is injected are respectively formed in the sealed housing, and the nonlinear laser 1 can be injected from the nonlinear laser 2, enter through the laser inlet, and be injected through the laser outlet.

The energy adjuster 3 can be arranged inside the sealed shell, so that the space is saved, the nonlinear laser 1 emitted from the nonlinear laser 2 can be ensured to enter the optical path system 4 completely, and the waste of the laser is avoided. Of course, the position of the energy regulator 3 may be set outside the sealed housing according to specific setting requirements, and is not limited herein.

Preferably, the laser inlet and the laser inlet are not on the same straight line of the sealed housing, that is, a laser adjusting mirror 41 for adjusting the path of the laser needs to be disposed inside the sealed housing, wherein the laser adjusting mirror 41 needs to face the nonlinear laser 1 and reflect the nonlinear laser 1 toward another laser adjusting mirror 41 or the laser outlet.

In this embodiment, the laser adjusting mirrors 41 are two, and this is set to ensure that the laser can realize turning, and can reach the longest path, and at the same time, can ensure that the laser energy center is at the optical path center.

Preferably, the sealed housing is filled with a protective gas. The protective gas is generally nitrogen or argon, the gas control system 8 is arranged outside the sealed shell, and the gas control system 8 can control the density, pressure and the like of the protective gas inside the sealed shell, so that the transmission of the nonlinear laser 1 cannot be influenced by the amount of the gas inside the sealed shell.

The gas control system 8 can control not only the protective gas inside the sealed housing, but also the laser gas and the sample carrier gas.

Furthermore, a slit 5 is arranged outside a laser outlet of the optical path system 4, the nonlinear laser can penetrate through the slit, and the slit is a group of round holes with different apertures and can be automatically adjusted. Different aperture diameters correspond to the size of the ablation beam spot (1-40 μm) after the laser is focused.

For the ablation cell 6, which includes a sample cell 61 and a lens group 65, wherein the sample cell 61 is a holding cavity with an opening at the top end, and a sample is disposed in the holding cavity, the nonlinear laser 1 can directly or indirectly irradiate into the sample cell 61 after propagating through the optical path system 4, so as to ablate the sample inside the sample cell 61. The lens group 65 is disposed above the sample cell, and generally adopts a convex lens group, which can converge all the nonlinear laser light 1 passing through the lens group 65, so as to realize accurate focusing, and concentrate the energy of the nonlinear laser light 1 to the focus inside the sample, so as to realize fixed-point ablation.

Wherein, the specific position of the sample cell 61 can be adjusted according to the actual situation, a sample console 62 for controlling the horizontal movement of the sample cell is arranged below the sample cell 61, control devices 63 for controlling the vertical movement of the sample cell are arranged at two sides of the sample console 62, and the horizontal direction and the height direction of the sample cell 61 are automatically adjusted through the sample console 62 and the control devices 63. Among them, as for the structures of the sample console 62 and the control device 63, a horizontal moving device and a lifting device conventionally used in the art can be directly employed.

Wherein, a light source 64 is further disposed below the sample cell 61, the light source 64 emits light toward the sample, and the light source 64 can directly adopt a red light-natural light double light source.

In order to facilitate the observation of the sample, an observation system 7 for observing the sample is further provided, the observation system 7 faces the sample cell 61, and the observation system 7 includes a laser reflector 71 for reflecting the nonlinear laser light 1 to the sample, a camera 72 facing the laser reflector 71, and an eyepiece 73 facing the laser reflector 71. The laser reflector 71 reflects the laser 1 to the sample, and the light passing through the sample may be transmitted to the eyepiece 73 and the camera 72.

Wherein, eyepiece 73 and camera 72 can set up simultaneously, also can only set up the eyepiece as required to directly carry out real-time observation through people's eye, can also only set up the camera, thereby can be the continuation carry out the record to it.

Preferably, in order to guarantee a better recording effect, the camera adopts an infrared camera which can still collect the state of the sample when the brightness is lower, so that a better observation and recording effect is achieved.

In this embodiment, the nonlinear laser ablation apparatus further includes a circuit control system 9 and a safety protection system 10, wherein the circuit control system 9 may adopt a distributed and modular design, and a central controller controls the nonlinear laser 1, the sample console 62, the control apparatus 63, and the like; the safety protection system 10 includes an automatic protection switch that can safely protect against a possible malfunction or accident. The gas circuit control system 8, the circuit control system 9, the safety protection system 10 and the like can realize intelligent operation, realize one-key processing operation on different minerals, automatically optimize laser energy, realize accurate fixed-point sample ablation, simultaneously support automatic operation and realize unmanned analysis.

Example 3

In this example, the nonlinear laser ablation apparatus in example 2 was used to ablate the fluid inclusions in the zincblende sample by the ablation method in example 1, the photograph is shown in fig. 2, and the elemental signal chart for the inductively coupled plasma mass spectrometry acquisition during the ablation of the sample is shown in fig. 3.

Comparative example

This comparative example was conducted by using a conventional linear laser ablation apparatus to ablate the sample of example 3, and as shown in fig. 4, an elemental signal plot was collected for inductively coupled plasma mass spectrometry performed on the sample.

It can be known from the comparison between fig. 2 and fig. 3 that, compared with the example 2, when the Zn element in the zinc blende is linear laser, the laser starts to degrade and there is a Zn signal, when the fluid inclusion is opened, the Zn signal intensity does not change greatly, so that the Zn concentration in the fluid inclusion cannot be tested, when the nonlinear laser is used for fixed-point blasting sampling, and when the fluid inclusion is not opened by laser heating, the laser energy is focused on the fluid inclusion, and the zinc blende is not degraded, so there is no Zn signal of the zinc blende, until the fluid inclusion in the zinc blende is detected because of the Zn signal in the fluid inclusion after the heating blasting, so the Zn in the zinc blende does not affect the Zn element test in the fluid inclusion.

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.

Claims

1. A laser ablation device is characterized in that a nonlinear laser is adopted to ablate a sample, the focus of the nonlinear laser is concentrated in the sample, fixed-point focusing and blasting are carried out in the sample, the laser path is adjusted according to different samples, the nonlinear laser pulse width is less than 1ns, the wavelength is less than 1100nm, the frequency is 1-50000 Hz, the power is 0-15W, the ablation depth of the sample is 1-20 mu m, and the ablation time is 5-40 s, the laser ablation device comprises,

the laser emission assembly is used for emitting nonlinear laser, and comprises a nonlinear laser and an energy adjuster for adjusting the energy of the nonlinear laser, wherein the energy adjuster is arranged on one side of the nonlinear laser;

an optical path system for the nonlinear laser to pass through; and

and the nonlinear laser is injected into the ablation tank through the optical path system.

2. The laser ablation apparatus according to claim 1, wherein the optical path system comprises a sealed housing, the sealed housing is respectively provided with a laser inlet for the nonlinear laser to enter and a laser outlet for the nonlinear laser to exit, and the sealed housing is filled with a protective gas.

3. The laser ablation device of claim 2, wherein the optical path system further comprises a plurality of laser adjustment mirrors disposed within the sealed housing, the laser adjustment mirrors facing the nonlinear laser light and reflecting the nonlinear laser light toward another laser adjustment mirror or a laser exit.

4. The laser ablation device of claim 3, wherein a gas control system for controlling the shielding gas is further disposed on one side of the sealed housing, the gas control system being in communication with the sealed housing.

5. The laser ablation device of claim 4, wherein a slit is provided outside the laser exit.

6. The laser ablation device of claim 1, wherein the ablation tank comprises:

the device comprises a sample cell for containing a sample, and a lens group arranged above the sample cell and used for converging the nonlinear laser, wherein the lens group is arranged towards the sample cell;

7. The laser ablation device of claim 6, wherein a light source for illuminating the sample is further arranged below the sample cell, and the light source is a red light-natural light double light source.

8. The laser ablation apparatus of claim 7, further comprising a viewing system for viewing the sample, the viewing system comprising a laser mirror for reflecting the nonlinear laser light to the sample and a camera and/or an eyepiece facing the laser mirror, the camera employing an infrared camera.