CN217586921U - LIBS light path adjusting device without visible indication light source - Google Patents

Abstract

A LIBS light path adjusting device without a visible indicating light source comprises a pulse laser, a laser reflector, a reflector bracket, a focusing mirror, a sample to be detected, a sample stage and a translation stage; the pulse laser is horizontally placed, the laser reflector is installed on the reflector bracket, pulse laser emitted by the pulse laser is reflected to the focusing mirror below the reflector bracket through the laser reflector, a sample table is arranged below the focusing mirror, and a sample to be detected is fixed on the sample table; the sample table is arranged on the translation table and can slide up and down along the translation table; the pulse laser emitted by the pulse laser can directly ablate traces on a sample to be detected, and whether the traces ablated by the pulse laser on the sample to be detected coincide or not is judged when the sample stage is at different positions to adjust the angle of the reflector bracket.

Description

LIBS light path adjusting device without visible indication light source

Technical Field

The utility model relates to a LIBS device, concretely relates to LIBS light path adjusting device who need not visible indicator light source.

Background

In a laser-induced breakdown spectroscopy system, the positions of a reflector, a focusing lens and a sample stage need to be accurately adjusted to realize rapid position positioning and calibration of an LIBS optical system, and finally, an invisible LIBS infrared laser light source is accurately focused at the correct position of a sample, and when the sample stage is required to drive the sample to be detected to move axially, the hitting position of the laser on the sample to be detected cannot deviate, but in the prior art, the positions of the reflector, the focusing lens and the sample translation stage can be accurately adjusted on the premise of indicating the light source.

The LIBS technique uses a high peak power pulse laser to irradiate a measured object, and a light beam is focused to form a light spot with high power density, so that a substance on the surface of the measured sample is excited into plasma and is rapidly attenuated, photons with specific wavelengths are formed in the attenuation process, and the characteristic wavelength and intensity information of the photons contain the element components and corresponding concentration information of the measured substance. The technology has the advantages of simultaneous detection of various elements, simple sample preparation or no preparation, real-time analysis, in-situ detection, remote detection and the like, and is widely applied to a plurality of fields of material processing, food safety, artwork identification, biomedicine, deep space detection, energy development and the like.

In the process of testing a sample by the LIBS device, the sample sometimes moves axially, and the moving direction of the sample is required to be parallel to the optical axis during moving so as to ensure that the laser strikes the surface of the sample at the same position and the spectrometer receives the plasma spectrum at the same position. If the two are not parallel, the striking position shifts when the sample moves, and the spectrum receiving device changes accordingly, so that the data testing condition changes and comparison cannot be carried out. Therefore, when the LIBS apparatus is subjected to optical path adjustment, the sample stage must be moved in the optical path direction in parallel with the optical axis of the laser. The laser light source of the LIBS device is usually infrared light, which cannot be seen by human eyes, so that when the light path is adjusted, visible light is often used to replace infrared light. One of the methods is that when a manufacturer manufactures a laser, a small visible laser is installed near a light outlet, the light path is parallel to the infrared light direction, and visible light is used when the light path is adjusted. Most lasers do not use the design of a visible light indicating light path, and the method for adjusting the light path comprises the steps of firstly detecting the irradiation direction of infrared laser, then placing the visible laser in front of the infrared laser, replacing the infrared laser with the visible laser, removing the visible laser after adjusting the light path, so that the condition that the infrared laser passes through an optical element is the same as that of the visible laser, and how to ensure that the direction of the visible laser is strictly consistent with that of the infrared laser in the infrared light path of the visible laser in the method is a difficult problem.

For example, chinese patent CN 207675651U discloses a portable underwater sediment and rock component detection device based on LIBS technology, an analysis module comprises a laser (2), a concave lens (3), a convex lens (4), a laser reflector (5), a dichroic mirror (6), a double-cemented lens (7), a sample tank (8), an electric rotating table (9), a lifting table (10) and an infrared positioning lamp (15), and a laser head of the laser is over against the concave lens (3); the concave lens (3), the convex lens (4) and the laser reflector (5) are sequentially and coaxially arranged in the horizontal direction; the laser reflector (5), the dichroic mirror (6) and the double-cemented lens (7) are sequentially and coaxially arranged in the vertical direction; the laser reflector (5) and the convex lens (4) form an included angle of 45 degrees; the dichroic mirror (6) and the convex lens (4) form an included angle of 45 degrees; the double cemented lens (7) and the convex lens (4) form an included angle of 90 degrees; the infrared positioning lamp (15) and the double cemented lens (7) form an included angle of 45 degrees; the sample groove (8) is arranged on the electric rotating table (9); the electric rotating platform (9) is arranged on the lifting platform (10); the collection module comprises a collection lens (11), a fiber probe (12), a fiber (13) and a spectrometer (14), wherein the fiber probe is positioned at the focus of the collection lens (11); the optical fiber probe (12) is connected with the spectrometer (14) through an optical fiber (13); the power supply module comprises a laser power supply (16) and a power supply box (17); the laser power supply (16) is connected with the laser (2) through a first cable (18) and is connected with the spectrometer (14) through a second cable (19); the laser power supply (16) controls the working mode of the laser (2) and triggers the spectrometer (14) to work; the power supply box (17) is connected with the laser power supply (16) through a third cable (20) and is connected with the electric turntable (9) through a fourth cable (21); the spectrometer (14) and the electric turntable (9) are respectively connected with a computer; the analysis module, collection module and power module are integrated within a suitcase (1) of 502mm x 138mm x 450 mm. The device can realize the rapid detection of underwater sediments and rocks on a ship. An infrared positioning lamp is arranged in the analysis module, infrared rays emitted by the infrared positioning lamp laterally pass through the focus of the double-cemented lens, the position of the point formed by the infrared rays on the surface of the sample when the point is coincided with the laser-induced plasma body is the focus position, the distance between the lens and the sample can be adjusted by the lifting platform, the position of the focus of the lens on the surface of the sample can be found, and the optimal spectrum signal can be obtained. The analysis module is provided with an electric rotating table which can change the position of laser focusing on the surface of the sample, so that the laser can puncture different positions on the surface of the sample, and the detection of components at different positions on the surface of the sample is realized. However, the patent still needs to arrange an infrared positioning lamp to emit an auxiliary light source, and the light path of the LIBS device cannot be relied on for debugging.

For another example, chinese patent CN 114245871A discloses an automatic focusing LIBS device, which provides an LIBS analysis system, comprising: a focusing lens having a focal plane; a laser configured to propagate a laser beam through a focusing lens in a direction along an optical path to focus on a focal plane; a detector having an output proportional to the intensity of the incident electromagnetic radiation; a sample holder for holding a sample, an upper surface of which intersects with the optical path; a translation mechanism operable to effect relative movement of the sample holder and the focusing lens to change the location of the focal plane relative to the sample holder along the optical path; and a controller configured to automatically control operation of the translation mechanism to effect relative movement to achieve an optimal position at which the focal plane and an analysis region of the upper surface intersecting the optical path are at or near coincidence, wherein the controller is further configured to calculate the optimal position from a mathematical transformation stored in a memory accessible to the controller, the transformation relating measurement data of the region of the upper surface intersecting the optical path to the optimal position and generated using output obtained from electromagnetic radiation from a plasma produced by the laser beam impinging on one or more other regions of the upper surface of the sample. By employing calculations rather than measuring the transformation of the optimal position of the laser at each sampling region, the number of non-analytical measurements is reduced. The controller is configured to control the LIBS analysis system to perform a profile generation cycle during which the controller is configured to operate the translation mechanism to effect the relative movement to achieve a plurality of different positions of the focal plane relative to the sample holder along the optical path at the first further region of the upper surface; the laser is operated to generate a plasma at each of a plurality of different locations and a representation of detector output obtained from electromagnetic radiation from the plasma generated at each of the plurality of different locations is retrieved into memory as intensity data indexed with location for generating a mathematical transformation. In some embodiments, the controller is configured to process the intensity data to generate a mathematical expression relating the detector output to the position of the focal plane and to store the mathematical expression as a mathematical transformation in the memory. Thus, the number of plasma generation events performed at the sampling region for auto-focusing purposes is reduced, preferably to one event. The controller is configured to operate the translation mechanism to move the sample stage in a plane perpendicular to the optical path to successively intersect a plurality of different other regions of the upper surface with the optical axis, each different other region having a different known location point in the plane; the laser beam is operated to produce a plasma at each of a plurality of different other regions and a mathematical transform is generated from a comparison of the detector output and intensity data at each of different known locations in the plane. The mathematical transformation relates information identifying the optimal position to the location points of the area in a plane perpendicular to the optical path, and the controller is configured to operate the LIBS device to collect the location points of the analysis area as measurement data. This has the advantage that the optimum location of an area on the sample surface can be calculated from knowledge of the location of that area without having to first ablate that area. Therefore, LIBS analysis measurements can be performed on the non-ablated areas of the sample surface. According to a second aspect of the present invention, there is provided a method of operating a LIBS analysis system according to the first aspect, comprising automatically adjusting the focal point of a laser beam output by a laser of the LIBS analysis system to an optimum point to reach an optimum point at which the focal plane and a region of the upper surface intersecting the optical path are at or near coincidence by automatically controlling the operation of a translation mechanism to effect relative movement, wherein the method further comprises using a controller to generate a mathematical transform that mathematically relates measurement data of the region of the upper surface intersecting the optical path to the optimum and is generated using output obtained from electromagnetic radiation from a plasma produced by the laser beam impinging on one or more other regions of the upper surface of the sample; measurement data for the upper surface region is obtained and a mathematical transformation is applied to the measurement data to determine the optimal location points. Thus, advantages corresponding to the first aspect can be achieved. But the structure is complex and the focusing process is complicated to operate.

Problem to prior art exists, the utility model provides a need not LIBS light path adjusting device of visible indicator light source, this device need not be with the help of extra visible light, but directly debugs the light path with LIBS laser source, can simplify LIBS light path adjustment step, both reduce cost have avoided the visible light to replace the inconsistent problem of both light paths in the infrared light time again.

SUMMERY OF THE UTILITY MODEL

In order to solve the problem, the utility model provides a need not LIBS light path adjusting device of visible indicator light source, it has solved the technical problem that LIBS laser lamp-house debugging light path needs the auxiliary light.

An LIBS light path adjusting apparatus without a visible indication light source, comprising: the device comprises a pulse laser, a reflector bracket and a laser reflector, wherein the reflector bracket and the laser reflector are arranged along the laser path direction of the pulse laser at a certain angle, the laser reflector reflects laser, a focusing mirror is arranged below the reflector, a sample stage for placing a sample to be detected is arranged below the focusing mirror, and a translation stage for bearing the sample stage and moving; the laser emitted by the pulse laser is horizontally transmitted, reflected by a laser reflector, penetrates through the focusing mirror and is emitted to a sample to be detected on the sample stage; the sample table can slide up and down along the translation table; and when the sample stage is at different positions, determining whether the ablated traces on the sample to be detected by the laser emitted by the pulse laser coincide with each other to serve as a basis for adjusting the angle of the reflector bracket 3.

Preferably, the surface of the sample stage is horizontal.

Preferably, the translation stage drives the sample stage to perform up-and-down translation motion along the vertical direction, and the motion direction of the sample stage is the same as the direction of the laser optical axis.

Preferably, a pulse laser is placed and fixed according to a planned light path, a reflector bracket provided with a laser reflector is placed in front of the pulse laser emission according to a certain angle, the laser transmission direction is changed by 90 degrees and then the laser is vertically transmitted downwards, and the reflector bracket is fixed.

Preferably, the sample stage is placed on the translation stage, so that the laser is shot on the surface of the sample to be detected placed on the sample stage in a dot shape, and the moving direction of the sample stage is the same as the optical axis direction of the laser.

Preferably, the pulse laser device emits pulse laser to ablate a first ablation trace on a sample to be detected, a light path is shielded to prevent the laser from irradiating on the surface of the sample to be detected, the sample stage is driven by the translation stage to move upwards or downwards for a certain distance, then the laser is irradiated on the sample to ablate a second ablation trace, whether the first ablation trace and the second ablation trace coincide is determined, and if the first ablation trace and the second ablation trace coincide, the translation stage is proved to drive the motion direction of the sample stage to be parallel to the optical axis direction of the laser, and adjustment is not needed.

Preferably, if the first ablation trace and the second ablation trace do not coincide with each other, the angle adjusting knob on the reflector bracket is adjusted, the angle of the laser reflector is changed to adjust the transmission direction of the reflected laser until the two ablation traces ablated by the laser on the sample to be detected back and forth coincide with each other, and the adjustment of the knob on the reflector bracket is stopped.

Preferably, the pulse laser emits laser to ablate a third ablation trace on the sample to be measured, the sample to be measured is kept still on the sample stage, the focusing mirror is placed between the reflecting mirror and the sample stage, the sample stage is driven to move by the translation stage, so that the upper surface of the sample to be measured is stopped at the focal position of the focusing mirror, the position of the focusing mirror is adjusted to enable the focused focal point to be at the central position of the ablated third ablation trace, and the laser optical axis focused by the focusing mirror is parallel to the movement direction of the sample stage.

Preferably, the mirror support is a three-knob type mirror support.

Preferably, the mirror support is a two-knob type mirror support.

The utility model discloses following beneficial effect has:

1. a LIBS light path adjusting device who need not visible indicator light source, be provided with the sample platform that awaits measuring and mobilizable, when different positions through the sample platform, whether the ablation vestige of laser on the sample that awaits measuring coincides, adjust the angle of speculum, need not be with the help of extra visible light, but direct with LIBS laser source debugging light path, both reduce cost have avoided the problem that both light paths are inconsistent when visible light replaces the infrared light again.

2. A need not LIBS light path adjusting device of visible indicator light source, the focusing mirror can be adjusted, adjusts the position of focusing mirror and sample platform through making the ablation vestige coincidence on focus and the sample that awaits measuring.

Drawings

The above and/or additional aspects and advantages of the present application will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a schematic diagram of a LIBS apparatus;

FIG. 2 is a schematic illustration of an ablation trace on a sample by a laser;

FIG. 3 is a schematic diagram of the focal point of the focusing lens and the ablation trace on the sample.

The reference numbers are as follows:

1-pulse laser, 2-reflector, 3-reflector bracket, 4-focusing mirror, 5-sample to be measured, 501-first ablation trace, 502-second ablation trace, 503-third ablation trace, 504-focusing point, 6-sample stage and 7-translation stage.

Detailed Description

The present invention will be described in detail below with reference to specific embodiments shown in the drawings. However, these embodiments do not limit the present invention, and structural, method, or functional changes that can be made by those skilled in the art according to these embodiments are all included in the scope of the present invention.

The utility model relates to a need not LIBS light path adjusting device of visible indicator light source, as shown in fig. 1-3, include: the device comprises a pulse laser 1, a reflector bracket 3 and a laser reflector 2, wherein the reflector bracket 3 and the laser reflector 2 are arranged along the laser path direction of the pulse laser at a certain angle, the laser reflector 2 is used for reflecting laser, a focusing mirror 4 is arranged below the reflector 2, a sample table 6 is arranged below the focusing mirror and used for placing a sample to be tested, and a translation table 7 capable of moving the sample table 6 is borne. The laser emitted by the pulse laser 1 is horizontally transmitted, and the emitted laser is reflected by the laser reflector 2, penetrates the focusing mirror 4 and is emitted to a sample to be detected on the sample stage 6. The sample stage 6 can slide up and down along the translation stage 7. The method comprises the steps that traces are ablated on a sample 5 to be measured by laser emitted by the pulse laser 1, and when the sample stage 6 is located at different positions, whether the traces ablated on the sample 5 to be measured by the laser emitted by the pulse laser 1 coincide or not is determined to serve as a basis for adjusting the angle of the reflector bracket 3. According to the technical scheme, the LIBS laser light source is directly used for debugging the light path without the help of extra visible light, so that the cost is reduced, and the problem that the light path is inconsistent when the visible light replaces the infrared light is solved.

Further, the surface of the sample stage 6 is horizontal. The sample to be tested may be a briquette.

Further, the translation stage 7 drives the sample stage 6 to move up and down in a translation manner along the vertical direction, and the movement direction of the sample stage 6 is the same as the direction of the laser optical axis.

Further, the pulse laser 1 is placed and fixed according to a planned light path, the reflector support 3 provided with the laser reflector 2 is placed in front of the pulse laser emission of the pulse laser 1 according to a certain angle, the laser transmission direction is changed by 90 degrees and then is vertically transmitted downwards, and the reflector support 3 is fixed.

Further, the sample stage 6 is placed on the translation stage 7, laser is made to be shot on the surface of the sample 5 to be measured placed on the sample stage 6 in a dot shape through the circular focusing mirror 4, and the moving direction of the sample stage 6 is the same as the direction of the optical axis of the laser.

Further, the pulse laser 1 emits pulse laser to ablate a first ablation trace 501 on the sample 5 to be measured, the light path is blocked to prevent the laser from irradiating on the surface of the sample 5 to be measured, the sample stage 6 is driven by the translation stage 7 to move upwards or downwards for a certain distance, then the laser is irradiated on the sample 5 to ablate a second ablation trace 502 again, whether the first and second ablation traces 501 and 502 are overlapped is determined, if so, the translation stage 7 drives the movement direction of the sample stage 6 to be parallel to the optical axis direction of the laser, and adjustment is not needed.

Further, if the first ablation trace 501 and the second ablation trace 502 do not coincide, the angle adjusting knob on the reflector bracket 3 is adjusted, the angle of the laser reflector 2 is changed to adjust the transmission direction of the reflected laser until the two ablation traces ablated by the laser on the sample 5 to be measured before and after coincide, and the adjusting knob on the reflector bracket 3 is stopped.

Further, the pulse laser 1 emits laser to ablate a third ablation trace 503 on the sample 5 to be measured, the sample 5 to be measured is kept stationary on the sample stage 6, the focusing mirror 4 is placed between the reflecting mirror 2 and the sample stage 6, the sample stage 6 is driven to move by the translation stage 7, so that the upper surface of the sample 5 to be measured is stopped at the focal position of the focusing mirror 4, the position of the focusing mirror 4 is adjusted to enable the focused focal point 504 to be located at the central position of the ablated third ablation trace 503, and at this time, the laser optical axis focused by the focusing mirror 4 is parallel to the moving direction of the sample stage 6.

Further, the reflector holder 3 is a three-knob reflector holder.

Further, the mirror holder 3 may be a two-knob type mirror holder.

The technical scheme of the utility model the theory of operation as follows: firstly, the relative position of the reflector 2 and the sample stage 6 is adjusted, and then the relative position of the focusing mirror 4 and the sample stage 6 is adjusted. Firstly, an LIBS optical path is planned, the pulse laser 1 is placed according to the planned optical path, and then the pulse laser 1 is fixed. The reflector bracket 3 provided with the laser reflector 2 is placed, so that the laser transmission direction is changed by 90 degrees and then is vertically transmitted downwards, and then the reflector bracket 3 is fixed. Fixing the sample table 6 on the translation table 7, and placing the translation table 7 at a proper position; at this time, the focusing mirror 4 is not installed, so that the laser directly hits on the sample 5 to be measured placed on the sample stage 6, and the moving direction of the sample stage 6 is the same as the optical axis direction of the laser. The pulse laser 1 emits pulse laser to ablate an ablation trace 501 on a sample 5 to be measured, then the light path is shielded to prevent the laser from irradiating on the sample 5, the translation stage 7 drives the sample stage 6 to move upwards or downwards for a certain distance, and then the laser irradiates on the sample 5 to ablate an ablation trace 502. The two ablation traces 501 and 502 are observed to coincide. If the two ablation traces are coincident, the translation table 7 drives the sample table 6 to move in a direction parallel to the optical axis direction of the laser, if the two ablation traces are not coincident, the knob on the reflector bracket 3 is finely adjusted to adjust the transmission direction of the reflected laser until the two ablation traces 501 and 502 ablated by the laser on the sample 5 to be measured are coincident, and at the moment, the translation table 7 drives the sample table 3 to move in a direction parallel to the optical axis direction of the laser, and the knob on the reflector bracket 3 is stopped being adjusted.

Then, the relative position of the focusing mirror 4 and the sample stage 6 is adjusted, the pulse laser 1 emits pulse laser to ablate an ablation trace 503 on the sample 5 to be measured, the sample 5 to be measured is kept to be immobile on the sample stage 6, the focusing mirror 4 is placed at a proper position between the reflecting mirror 2 and the sample stage 6, the sample stage 6 is driven by the translation stage 7 to enable the upper surface of the sample 5 to be at the focal position of the focusing mirror 4, the focusing mirror 4 is adjusted to enable the focused focal point 504 to be positioned at the central position of the ablation trace 503, and at the moment, the laser optical axis focused by the focusing mirror 4 is parallel to the moving direction of the sample stage 6.

It should be understood that although the present description refers to embodiments, not every embodiment contains only a single technical solution, and such description is for clarity only, and those skilled in the art should make the description as a whole, and the technical solutions in the embodiments can also be combined appropriately to form other embodiments understood by those skilled in the art. The above list of details is only for the practical implementation of the present invention, and they are not intended to limit the scope of the present invention, and all equivalent implementations or modifications that do not depart from the technical spirit of the present invention should be included in the scope of the present invention.

Claims (10)

1. An LIBS light path adjusting apparatus without a visible indication light source, comprising: the device comprises a pulse laser (1), a reflector bracket (3) and a laser reflector (2) which are arranged along the laser path direction of the pulse laser at a certain angle, a focusing mirror (4) below the laser reflector (2), a sample stage (6) which is used for placing a sample to be tested and is arranged below the focusing mirror, and a translation stage (7) which can bear the sample stage (6) and is movable; the laser emitted by the pulse laser (1) is horizontally transmitted, and the emitted laser is reflected by the laser reflector (2), penetrates the focusing mirror (4) and is emitted to a sample to be detected on the sample stage (6); the sample table (6) can slide up and down along the translation table (7); the method comprises the steps that a mark is ablated on a sample (5) to be detected by laser emitted by the pulse laser (1), and when the sample table (6) is located at different positions, whether the mark ablated on the sample (5) to be detected by the laser emitted by the pulse laser (1) is overlapped or not is determined to serve as a basis for adjusting the angle of the reflector support (3).

2. The LIBS optical path adjusting apparatus without a visual indicating light source as claimed in claim 1, wherein the surface of the sample stage (6) is horizontal.

3. The LIBS optical path adjusting apparatus without a visible indication light source as claimed in claim 1, wherein the translation stage (7) drives the sample stage (6) to move up and down in a vertical direction, and the movement direction of the sample stage (6) is the same as the direction of the laser optical axis.

4. The LIBS optical path adjusting device without a visible indication light source according to claim 1, wherein the pulse laser (1) is placed and fixed according to a planned optical path, the reflector bracket (3) provided with the laser reflector (2) is placed in front of the pulse laser (1) for emitting the pulse laser at a certain angle, the laser transmission direction is changed by 90 degrees and then the laser is vertically transmitted downwards, and the reflector bracket (3) is fixed.

5. The LIBS optical path adjusting apparatus without a visible indication light source of claim 4, wherein the sample stage (6) is placed on the translation stage (7), the laser is projected onto the surface of the sample (5) to be measured placed on the sample stage (6) in a dot shape, and the moving direction of the sample stage (6) is the same as the optical axis direction of the laser.

6. The LIBS optical path adjusting device without a visible indication light source of claim 5, wherein the pulsed laser (1) emits pulsed laser to ablate a first ablation trace (501) on the sample (5) to be measured, the optical path is blocked to prevent the laser from irradiating on the surface of the sample (5) to be measured, the translation stage (7) drives the sample stage (6) to move up or down for a certain distance, then the laser irradiates on the sample (5) to ablate a second ablation trace (502), whether the first ablation trace (501) and the second ablation trace (502) are overlapped is determined, and if the first ablation trace and the second ablation trace are overlapped, it is proved that the moving direction of the translation stage (7) driving the sample stage (6) is parallel to the optical axis direction of the laser, and no adjustment is needed.

7. The LIBS optical path adjusting device without a visible indication light source as claimed in claim 6, wherein if the first ablation trace (501) and the second ablation trace (502) do not coincide, the angle adjusting knob on the reflector bracket (3) is adjusted, the angle of the laser reflector (2) is changed to adjust the transmission direction of the reflected laser until the two ablation traces ablated by the laser on the sample (5) to be measured back and forth coincide, and the adjusting knob on the reflector bracket (3) is stopped.

8. The LIBS optical path adjusting device without a visible indication light source of claim 7, wherein the pulsed laser (1) emits laser to ablate a third ablation trace (503) on the sample (5) to be measured, the sample (5) to be measured is kept stationary on the sample stage (6), the focusing mirror (4) is placed between the laser reflecting mirror (2) and the sample stage (6), the sample stage (6) is driven by the translation stage (7) to move so that the upper surface of the sample (5) to be measured stays at the focal position of the focusing mirror (4), the position of the focusing mirror (4) is adjusted so that the focused focal point (504) is at the central position of the ablated third ablation trace (503), and at the moment, the laser optical axis focused by the focusing mirror (4) is parallel to the moving direction of the sample stage (6).

9. The LIBS light path adjustment device without a visible indication light source as claimed in claim 1, wherein the reflector holder (3) is a three-knob type reflector holder.

10. The LIBS light path adjustment device without a visible indication light source as claimed in claim 1, wherein the reflector holder (3) is a two-knob type reflector holder.

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