CN217505627U - Self-focusing device for laser-induced breakdown spectroscopy remote detection - Google Patents

Abstract

The utility model discloses a self-focusing device for laser-induced breakdown spectroscopy remote detection, which comprises a laser range finder, a laser, a beam expanding lens group, a first laser reflector, a dichroic mirror, a main mirror and a multi-pair mirror zooming structure, wherein the laser, the beam expanding lens group, the first laser reflector, the dichroic mirror, the main mirror and the multi-pair mirror zooming structure are sequentially arranged along the propagation direction of a laser beam; a focusing system is arranged on one side of the dichroic mirror, which is far away from the main mirror, and the focusing system is connected with the spectrometer; the main mirror is a concave spherical reflector with a round hole in the center; the multi-lens zooming structure comprises a guide rail and a grating ruler which are parallel; the guide rail is provided with a second laser reflector, two motors and a plurality of rotating arms capable of rotating around the axis of the guide rail in a reciprocating manner, the rotating arms are provided with a limiting rod and a rotating arm supporting rod, the rotating arm supporting rod is provided with secondary mirrors, the secondary mirrors are convex spherical lenses, the convex surfaces of all the secondary mirrors face the primary mirror, and the curvature radiuses of all the secondary mirrors are different. The self-focusing device has higher zooming precision and can be applied to the analysis and measurement of the composition of the object to be measured in extreme environments which are inconvenient to directly contact in a short distance.

Description

Self-focusing device for laser-induced breakdown spectroscopy remote detection

Technical Field

The utility model belongs to the technical field of spectral measurement, a detection device based on laser-induced breakdown spectroscopy is related to, concretely relates to laser-induced breakdown spectroscopy self-focusing device that can remote detection.

Background

Laser-Induced Breakdown Spectroscopy (LIBS), also known as Laser-Induced Plasma Spectroscopy (LIPS) or Laser Spark Spectroscopy (LSS), is an element detection technique developed in recent years that belongs to atomic emission Spectroscopy. The LIBS is based on the principle that high-energy pulse laser light is focused on the surface of an object to be detected to ablate the object to generate plasma, in the process of cooling and expanding the laser-induced plasma, a characteristic spectrum of the object to be detected can be obtained through a focusing system and a spectrometer system, and after data processing is carried out, the content of constituent elements of the object to be detected can be obtained.

In recent years, with the rapid development of LIBS technology, important research results have been obtained in the fields of medical treatment, industrial production, deep sea and space exploration, nuclear environment and explosive element detection, and the like.

Although LIBS has been developed, most LIBS is short-range detection, and there are many scenes in reality where short-range detection cannot be directly performed. For example, in high temperature, high radiation hazardous environments, cliff, deep sea in space. The application requirements of remote LIBS are enormous.

The most remarkable characteristic of the LIBS is that sample preparation is not needed, and the LIBS is convenient to operate in practical application; the LIBS has little influence on the measured object due to the fact that the working medium of the LIBS is pulse laser, and the LIBS is close to nondestructive detection; and because the optical signal emitted by the laser-induced plasma is strong enough, it provides the possibility for the feasibility of a remote LIBS.

In actual use, the area of a measured object is large, the distance between the measured object and the detection device is not fixed, and the common laboratory fixed focus LIBS cannot meet the requirement. Moreover, the common laboratory LIBS is manually zoomed, the zooming speed is low, the difficulty in debugging the optical path is high, and the requirement on equipment users is high; some LIBS focusing systems and condensing systems are designed into separate structures, so that the size is relatively large, the space utilization rate is low, integration is not easy, and the workload of equipment users is increased.

Most of the existing remote focusing optical structures of remote LIBS use a Cassegrain structure, when the remote zooming is carried out, only a mode of moving a secondary lens to zoom is used, and the zooming curve of the remote focusing optical structure is smoother at the middle end and the tail end, namely, the lens moves for a short distance, but the focusing distance is greatly changed. However, this increases the accuracy requirements for the displacement system, increases the cost of use, and its actual zoom range tends to be smaller than the theoretically designed zoom range.

Disclosure of Invention

The utility model aims at providing a can automatic zoom be used for laser-induced breakdown spectroscopy remote detection's self-focusing device.

In order to achieve the above object, the utility model adopts the following technical scheme: a self-focusing device for laser-induced breakdown spectroscopy remote detection comprises a laser range finder, and a laser, a beam expanding lens group, a first laser mirror, a dichroic mirror, a main mirror and a multi-auxiliary-mirror zooming structure which are sequentially arranged along the propagation direction of a laser beam; the first laser mirror and the dichroic mirror are arranged in parallel up and down, included angles between the first laser mirror and the dichroic mirror and a horizontal plane are both 45 degrees, and a focusing system is arranged on one side of the dichroic mirror, which is far away from the main mirror, and is connected with a spectrometer; the laser, the multi-lens zooming structure, the laser range finder and the spectrometer are all connected with the computer;

the main mirror adopts a concave spherical reflector with a circular hole in the center, and the concave spherical surface of the main mirror faces to the multi-pair mirror zooming structure;

the multi-lens zooming structure comprises a guide rail and a grating ruler which are arranged in parallel, a grating ruler sliding block which can reciprocate along the length direction of the grating ruler is arranged on the grating ruler, and the grating ruler sliding block is connected with the guide rail through a first connecting support rod; a plurality of rotating arms capable of rotating around the axis of the guide rail in a reciprocating manner are sequentially arranged on the guide rail along the axis direction of the guide rail, the rotating arms adopt electromagnetic clutches, limiting rods and rotating arm supporting rods are fixedly connected onto the rotating arms, secondary mirrors are arranged on the rotating arm supporting rods, the secondary mirrors are convex spherical lenses, the convex surfaces of all the secondary mirrors face the primary mirror, and the curvature radiuses of all the secondary mirrors are different; a first motor and a second motor are respectively installed at two ends of the guide rail, control modules are installed on the first motor and the second motor, and all the control modules are in signal connection with a computer; a second connecting support rod is fixedly connected to a guide rail between the first motor and the rotating arm adjacent to the first motor, the second connecting support rod is positioned below the guide rail, a second laser reflector with the inclination direction opposite to that of the first laser reflector is mounted at the lower end of the second connecting support rod, and the included angle between the second laser reflector and the horizontal plane is 45 degrees;

all the rotating arms are connected with a computer through a control circuit; limit switches with the same number as the rotating arms are arranged on the grating ruler; the first motor adopts a linear motor;

the beam expanding lens group comprises a first biconcave lens and a plano-convex lens which are arranged side by side, and the convex surface of the plano-convex lens is arranged away from the first biconcave lens; the first biconcave lens is adjacent to the laser.

The focusing system comprises a second biconcave lens, a first biconvex lens, a second biconvex lens and a negative meniscus lens which are arranged in sequence side by side, wherein the concave surface of the negative meniscus lens faces the second biconvex lens; the negative meniscus lens is adjacent to the spectrometer.

The utility model discloses self-focusing device has following advantage:

1) and (4) measuring at a long distance. The zoom range is 1-20 m, the applicability is strong, the method can be used for most of field remote measurement operations, the field real-time online detection is realized, the time is saved, and the detection efficiency is improved; the problem of in the actual measuring, the article that awaits measuring is unset with detection device distance is solved.

2) The optical-mechanical-electrical integration technology realizes automatic zooming. And the system error caused by manually adjusting the lens is avoided during zooming, and the measurement precision and efficiency are improved.

3) The zoom precision is higher. Using a multi-pair (each having a different radius of curvature) zoom configuration improves the zoom curve compared to single curvature pair zooming. Zooming with a single curvature secondary mirror, the zooming curve of which is very smooth at the end (i.e. the zooming distance varies greatly when the secondary mirror moves for a short distance); the working auxiliary lenses with different curvatures have different zooming ranges, and ideal parts in the zooming curves of the auxiliary lenses with different curvatures are selected to form a new continuous zooming curve. Namely, the multi-auxiliary-lens zooming structure increases the change of the distance between the main lens and the working auxiliary lens in the Y direction in the same zooming range, so that the zooming is more stable and more accurate in actual operation. Meanwhile, the precision requirement of a mechanical system is reduced, and the cost is saved.

4) Compact structure and easy integration. The collecting system and the focusing system are coaxial, the utilization rate of the lens is high, and the structures of all parts are tightly connected, so that the space utilization rate is high, namely the structure is small, and the lens is convenient to be integrated with other devices for use.

5) The method can be applied to the analysis and measurement of the composition of the object to be measured in extreme environments which are inconvenient to directly contact in close range, such as: in industrial metallurgy, the component measurement of the molten metal in a short distance is not easy to realize due to overhigh temperature; or element measurement is carried out in the strong magnetic radiation environment of a nuclear power station and the like; or elemental measurements in an explosive environment, etc. The utility model discloses self-focusing device can also carry on some automatic mechanical device (unmanned aerial vehicle, unmanned car, cloud platform etc.), realizes the long-term automatic detection of the article that awaits measuring, for example: and carrying on an unmanned aerial vehicle to carry out long-term automatic real-time online detection on the element component content of the sample to be detected.

Drawings

Fig. 1 is a schematic diagram of the self-focusing detection device of the present invention.

Fig. 2 is a schematic diagram of the zoom structure of the multiple pairs of lenses in the self-focusing detection apparatus of the present invention.

Fig. 3 is a schematic diagram of the beam expanding lens set in the self-focusing detection apparatus of the present invention.

Fig. 4 is a schematic diagram of a focusing system in the self-focusing detection apparatus of the present invention.

Fig. 5 is a usage status diagram of the multi-pair zoom structure in the self-focusing detection apparatus of the present invention.

FIG. 6 is a graph comparing single pair zooming and multi-pair zooming.

In the figure: 1. the system comprises a computer, 2, a laser, 3, a beam expanding lens group, 4, a first laser reflector, 5, a primary mirror, 6, a multi-secondary-mirror zooming structure, 7, an object to be measured, 8, a distance measuring system, 9, a dichroic mirror, 10, a focusing system, 11, a spectrometer, 12, a secondary mirror, 13, a second laser reflector, 14, a guide rail, 15, a grating ruler, 16, a first connecting supporting rod, 17, a limiting rod, 18, a grating ruler sliding block, 19, a first motor, 20, a second connecting supporting rod, 21, a rotating arm supporting rod, 22, a rotating arm, 23, a second motor, 24, a working secondary mirror, 25, a first biconcave lens, 26, a plano-convex lens, 27, a second biconcave lens, 28, a first biconvex lens, 29, a second biconvex lens and 30, a negative meniscus lens.

Detailed Description

The invention is further explained below with reference to the drawings and the detailed description.

As shown in fig. 1, the self-focusing detection device of the present invention comprises a laser range finder 8, and a laser 2, a beam expanding lens group 3, a first laser mirror 4, a dichroic mirror 9, a main mirror 5 and a multi-pair lens zooming structure 6 sequentially arranged along the propagation direction of a laser beam; the first laser reflector 4 and the dichroic mirror 9 are arranged in parallel up and down, included angles between the first laser reflector 4 and the dichroic mirror 9 and a horizontal plane are both 45 degrees, a focusing system 10 is arranged on one side of the dichroic mirror 9, which is far away from the main mirror 5, and the focusing system 10 is connected with a spectrometer 11; the laser 2, the multi-lens zooming structure 6, the laser range finder 8 and the spectrometer 11 are all connected with the computer 1.

The main mirror 5 adopts a concave spherical reflector with a round hole with the diameter of 4mm at the center, and the concave spherical surface of the main mirror 5 faces the multi-pair mirror zooming structure 6.

As shown in fig. 2, the multi-lens zoom structure 6 of the self-focusing detection device of the present invention includes a guide rail 14 and a grating ruler 15 which are arranged in parallel, a grating ruler slider 18 which can reciprocate along the length direction of the grating ruler 15 is installed on the grating ruler 15, and the grating ruler slider 18 is connected with the guide rail 14 through a first connecting support rod 16; a plurality of rotating arms 22 capable of rotating around the axis of the guide rail 14 in a reciprocating manner are sequentially arranged on the guide rail 14 along the axis direction of the guide rail 14, a limiting rod 17 and a rotating arm supporting rod 21 are fixedly connected onto the rotating arms 22, one end of the limiting rod 17 is fixedly connected with the rotating arms 22, the other end of the limiting rod 17 is a free end, the lower end of the rotating arm supporting rod 21 is fixedly connected with the rotating arms 22, the upper end of the rotating arm supporting rod 21 is provided with a secondary mirror 12, the secondary mirrors 12 are convex spherical lenses, the convex surfaces of all the secondary mirrors 12 face the primary mirror 5, and the curvature radiuses of all the secondary mirrors 12 are different; a first motor 19 and a second motor 23 are respectively installed at two ends of the guide rail 14, control modules are installed on the first motor 19 and the second motor 23, and all the control modules are in signal connection with the computer 1; the second motor 23 is connected to the guide rail 14 by spline coupling. A second connecting support rod 20 is fixedly connected to the guide rail 14 between the first motor 19 and the rotating arm 22 adjacent to the first motor 19, the second connecting support rod 20 is positioned below the guide rail 14, the upper end of the second connecting support rod 20 is fixedly connected with the guide rail 14, a second laser reflector 13 is installed at the lower end of the second connecting support rod 20, the included angle between the second laser reflector 13 and the horizontal plane is 45 degrees, and the inclination direction of the second laser reflector 13 is opposite to that of the first laser reflector 4.

The rotary arm 22 is an electromagnetic clutch, preferably a DC24V electromagnetic clutch (a mini high torque clutch of Sinfonia, japan). A limiting rod 17 and a rotating arm supporting rod 21 are fixedly connected to the outer wall of a driven rotor of the electromagnetic clutch, and an included angle between the limiting rod 17 and the rotating arm supporting rod 21 is 90 degrees; the driving rotor of the electromagnetic clutch is fitted around the guide rail 14.

All the rotating arms 22 are connected to the computer 1 via a control circuit.

The grating ruler 15 is provided with limit switches with the same number as the rotating arms 22.

The first motor 19 is a linear motor.

All the swivel arms 22 are located between the first connecting strut 16 and the second connecting strut 20.

The length of the internal spline and the length of the external spline in the spline coupling are different. The external spline is installed on the guide rail 14, the internal spline is installed on the motor shaft of the second motor 23, and a gap is formed between the end surface of the external spline facing the second motor 23 and the end surface of the motor shaft of the second motor 23 extending into the internal spline.

As shown in fig. 3, the beam expanding lens set 3 of the self-focusing detection device of the present invention includes a first biconcave lens 25 and a plano-convex lens 26 disposed side by side, and the convex surface of the plano-convex lens 26 deviates from the setting of the first biconcave lens 25. A first biconcave lens 25 is adjacent the laser 2 and a plano-convex lens 26 is adjacent the first laser mirror 4.

As shown in fig. 4, the focusing system 10 of the present invention comprises a second biconcave lens 27, a first biconvex lens 28, a second biconvex lens 29 and a negative meniscus lens 30, which are arranged side by side in sequence, wherein the concave surface of the negative meniscus lens 30 faces the second biconvex lens 29; a negative meniscus lens 30 is adjacent the spectrometer 11 and a second biconcave lens 27 is adjacent the dichroic mirror 9.

Use the utility model discloses during article 7 that awaits measuring are surveyed to the self-focusing device long-range:

1) when the self-focusing device is not in operation, all the limiting rods 17 are arranged along the positive direction of the X axis, all the rotating arm supporting rods 21 are arranged along the positive direction of the Z axis, and the guide rail 14 is arranged along the direction of the Y axis;

placing an object to be detected 7 at a pre-designed position, then starting the computer 1 and the laser range finder 8, and at the moment, not electrifying all the rotating arms 22;

2) obtaining a zooming parameter: a working instruction is sent to the laser range finder 8 through the computer 1, the laser range finder 8 sends a laser beam A, and the laser beam A irradiates to the multi-pair zoom structure 6, is reflected by a second laser reflector 13 in the multi-pair zoom structure 6 and irradiates to an object 7 to be measured; the surface of the object 7 to be measured is reflected back to a beam of signal light A, the signal light A irradiates to the second laser reflector 13 and is reflected to the laser range finder 8 through the second laser reflector 13, the laser range finder 8 receives the returned signal light A and then calculates to obtain the distance from the main mirror 5 to the object 7 to be measured (the actual distance measured by the range finder 8 is the distance from the range finder 8 to the second reflector 13 and the distance from the second reflector 13 to the object 7 to be measured, and because the working auxiliary mirror 24 returns to the original position after each measurement, the distance between the main mirror 5 and the second reflector 13 is determined, only the actual distance measured by the range finder 8 is required to subtract the distance from the range finder 8 to the second reflector 13 and the distance from the main mirror 5 to the second reflector 13 is required to obtain the distance from the main mirror 5 to the object 7 to be measured), and the calculation result is sent to the computer 1, the computer 1 calculates the corresponding working parameters, i.e. determining which sub-mirror 12 is selected for operation and the distance and direction that the guide 14 moves;

3) the computer 1 sends out an instruction to start the second motor 23, the second motor 23 drives the guide rail 14 to rotate through spline connection, the guide rail 14 drives the driving rotors in all the rotating arms 22 to rotate, meanwhile, the computer 1 powers on the selected rotating arm 22 through a control circuit according to the obtained working parameters, the driving rotor in the powered rotating arm 22 is combined with the driven rotor, the driving rotor drives the driven rotor to rotate, the driven rotor drives the limiting rod 17 and the rotating arm support rod 21 thereon to rotate around a horizontal shaft, after the limiting rod 17 and the rotating arm support rod 21 rotate 180 degrees, the limiting rod 17 is contacted with a limiting switch on the grating ruler 15, the limiting switch sends out a signal, the computer 1 sends out an instruction to turn off the second motor 23, the selected rotating arm 22 is still in a powered state, at the moment, the secondary mirror 12 fixedly connected on the rotating arm 22 is coaxial with the primary mirror 5, the sub-mirror 12 becomes a working sub-mirror 24, completing coarse zooming, as shown in fig. 5; then, the computer 1 sends out an instruction, the first motor 19 is started, the first motor 19 drives the guide rail 14 to drive the working auxiliary mirror 24 to displace along the axial direction of the guide rail 14 to the direction determined by the computer 1, in the displacement process, the grating ruler 15 continuously measures the position of the working auxiliary mirror 24, after the working auxiliary mirror 24 meets the displacement distance, the computer 1 judges whether the fine zooming is finished or not by reading the data of the grating ruler 15, if the fine zooming is judged to be finished, the computer 1 closes the first motor 19, and the displacement of the working auxiliary mirror 24 is finished;

4) the computer 1 starts the laser 2, the laser 2 emits a pulse laser beam, and the pulse laser beam sequentially passes through the first biconcave lens 25 and the plano-convex lens 26 to enlarge the laser spot by 2.5 times; the amplified laser facula sequentially passes through the first laser reflector 4 and the dichroic mirror 9, then is emitted to the working secondary mirror 24 through a central circular hole of the primary mirror 5, is diverged by a convex surface of the working secondary mirror 24 and is reflected to a concave surface of the primary mirror 5, and is reflected by the concave surface of the primary mirror 5 to be converged to the object 7 to be measured; when the energy density of the converged laser reaches the material threshold of the object 7 to be detected, plasma can be excited on the surface of the object 7 to be detected, and the plasma emits signal light B outwards in the cooling and expanding process

5) The signal light B is converged to the working secondary mirror 24 by the concave surface of the primary mirror 5, reflected by the working secondary mirror 24 and then emitted to the dichroic mirror 9 through the central circular hole of the primary mirror 5, a part of the signal light B passes through the dichroic mirror 9 and then sequentially passes through the second biconcave lens 27, the first biconvex lens 28, the second biconvex lens 29 and the negative meniscus lens 30 to enter the spectrometer 11, the spectrometer 11 is combined with the computer 1 to analyze a part of the received signal light B, and the computer 1 measures the material composition and the content of the object 7 to be measured through a LIBS (laser induced breakdown spectroscopy) quantitative analysis algorithm.

After the measurement is finished, the computer 1 starts the first motor 19 to drive the guide rail 14 to move reversely, so that the rotating arm 22 returns to the original position before the linear movement, then the computer 1 starts the second motor 23 to drive the guide rail 14 to rotate reversely, so that the selected rotating arm rotates reversely by 180 degrees, the working auxiliary mirror 24 returns to the original position, then the computer 1 sends out an electric signal, the control circuit cuts off the power of the selected rotating arm 22, and the rotating arm 22 returns to the separation state.

The signal light B may be a visible light having a wavelength of 200nm to 800nm, which transmits a part of the dichroic mirror 9. The visible light band in the signal light B passes through the dichroic mirror 9 and is emitted to the focusing system 10, which eliminates the interference of the pulsed laser on the spectrometer 11.

The visible light transmitted by the dichroic mirror 9 is converged to an optical fiber connected with a spectrometer 11 by a focusing system 10; the spectrometer 11 generates spectral data according to the collected signal light, and finally obtains the composition of the object 7 to be measured through software analysis.

The focusing system 10, the primary mirror 5 and the working secondary mirror 24 are coaxial; the working secondary mirror 24 and the primary mirror 5 form a cassegrain system.

During the detection, since the first motor 19 is small, when the second motor 23 drives the guide rail 14 to rotate, the first motor 19 rotates together with the guide rail 14. When the first motor 19 works, the second motor 23 stops working, the first motor 19 drives the guide rail 14 to move linearly, and because the lengths of the inner spline and the outer spline in spline connection are different and the linear movement distance of the guide rail 14 is not large, the inner spline and the outer spline can not be disengaged in the moving process, and the moving distance of the guide rail 14 can be ensured by the gap between the end surface of the outer spline and the end surface of the motor shaft of the second motor 23.

As shown in fig. 5, the distance D between the main mirror 5 and the working sub-mirror 24 is:

D=d1+d2+d3+(n－1)Δd（1）

(1) in the formula, d1 is the zero point of the grating scale 15, that is, the distance between the end surface of the grating scale 15 facing the primary mirror 5 and the plane of the primary mirror 5 in the Y direction;

d2 is the relative distance between the zero point of the grating ruler 15 (the end surface of the grating ruler 15 facing the primary mirror 5) and the end of the grating ruler slide block 18 facing the zero point of the grating ruler 15 in the Y direction, and is the reading of the grating ruler at the same time;

d3 is the distance between one end of the grating ruler slide block 18 facing the zero point of the grating ruler 15 and the axis of the rotary arm support rod 21 of the secondary mirror 12 adjacent to the grating ruler slide block 18 in the Y direction;

Δ d is a distance in the Y direction between the axes of the rotating arm poles 21 where the adjacent two sub mirrors 12 are located;

n is the number of the rotating sub-mirrors 12 sorted among all the sub-mirrors (sorted in order from the main mirror 5 to the first motor 19 direction, the number of the sub-mirror 12 closest to the main mirror 5 is 1, and so on).

The utility model discloses carry out thick zoom through selected secondary mirror 12 among the detection method, mean through selecting different secondary mirror 12, change the value of n in formula (1) promptly. The utility model discloses thin zooming in the detection method is computer 1 sends the motor module of order for first motor 19, and first motor 19 drives 14 rectilinear movement of guide rail, changes d 2's value in formula (1) promptly.

The utility model discloses light beam is diverged to work secondary mirror 24 among the self-focusing device, and primary mirror 5 assembles the light beam, can zoom through changing distance D in the Y side between primary mirror 5 and the work secondary mirror 24: after obtaining the zoom parameters, the second motor 23 is used to select a suitable sub-mirror 12 from the plurality of sub-mirrors 12 for coarse zooming, and then the first motor 19 is used to drive the guide rail 14 to drive the working sub-mirror 24 to move for fine zooming.

The first biconcave lens 25 and the plano-convex lens 26 are arranged in parallel and are both vertical to the propagation direction of light, and the beam expanding lens group 3 of the device can expand the light by 2.5 times.

The first biconvex lens 28 and the second biconcave lens 27 are used to eliminate aberrations. A second biconvex lens 29 and a negative meniscus lens 30 are used to focus the light beam.

Under the condition that the laser 2 emits a light spot with the radius of 4mm, the diameter of the focused light spot is smaller than 1mm, so that the laser energy can be gathered in a small enough space range, and the laser can excite high-temperature and high-density plasma on the surface of an object 7 to be detected.

The focusing light path (the first biconcave lens 25 and the planoconvex lens 26) and the collecting light path (the second biconcave lens 27, the first biconvex lens 28, the second biconvex lens 29 and the negative meniscus lens 30) are coaxially arranged, the optimization of focusing and collecting at different distances can be controlled by using the least adjustment amount, the diameter of a focusing light spot of the collected light coupled into the optical fiber is smaller than 0.6mm after the collected light passes through the coaxial collecting system, and the telescopic focusing collecting system can be used for ensuring that the spectral signals of a wide range of wave bands can be focused into the core diameter of the optical fiber at different distances.

The utility model discloses self-focusing device uses a plurality of secondary lenses 12 to select to zoom, has improved self-focusing device's zooming curve resolution, same focus distance variation promptly, and the primary mirror 5 that many lenses zoom system corresponds and the change of work secondary lens 24 distance are bigger than the primary mirror of single lens piece zoom system in prior art and the work secondary lens apart from the variation in Y direction, and this can reduce the error of zooming, makes the measuring result more accurate.

The utility model discloses many secondary mirrors of self-focusing device zoom and the curve contrast picture of the zoom of single secondary mirror in the prior art, as shown in FIG. 6, wherein the abscissa is the focus distance, and the ordinate is the distance between primary mirror 5 and the vice mirror 24 of work on the Y direction. As can be seen from the figure, the resolution of the multi-lens zoom curve is greater than that of the single-lens zoom curve, that is, the same amount of change in the focusing distance, and the amount of change in the distance between the main lens 5 and the working auxiliary lens 24 corresponding to the multi-lens zoom system in the Y direction is greater than the amount of change in the distance between the main lens 5 and the working auxiliary lens 24 of the single-lens zoom system in the Y direction, which can reduce the error of zooming and make the measurement result more accurate.

The utility model discloses auto focus device is a coaxial long-range LIBS auto zoom device that uses many lenses to zoom. The entire apparatus is controlled by the computer 1.

Claims (3)

1. A self-focusing device for laser-induced breakdown spectroscopy remote detection is characterized by comprising a laser range finder (8), and a laser (2), a beam expanding lens group (3), a first laser mirror (4), a dichroic mirror (9), a main mirror (5) and a multi-pair-mirror zooming structure (6) which are sequentially arranged along the propagation direction of a laser beam; the first laser reflector (4) and the dichroic mirror (9) are arranged in parallel up and down, included angles between the first laser reflector (4) and the dichroic mirror (9) and a horizontal plane are both 45 degrees, a focusing system (10) is arranged on one side, away from the main mirror (5), of the dichroic mirror (9), and the focusing system (10) is connected with the spectrometer (11); the laser (2), the multi-pair lens zooming structure (6), the laser range finder (8) and the spectrometer (11) are all connected with the computer (1);

the main mirror (5) adopts a concave spherical reflector with a round hole in the center, and the concave spherical surface of the main mirror (5) faces the multi-pair mirror zooming structure (6);

the multi-auxiliary-lens zooming structure (6) comprises a guide rail (14) and a grating ruler (15) which are arranged in parallel, a grating ruler sliding block (18) which can reciprocate along the length direction of the grating ruler (15) is arranged on the grating ruler (15), and the grating ruler sliding block (18) is connected with the guide rail (14) through a first connecting support rod (16); a plurality of rotating arms (22) capable of rotating around the axis of the guide rail (14) in a reciprocating manner are sequentially installed on the guide rail (14) along the axis direction of the guide rail (14), the rotating arms (22) adopt electromagnetic clutches, limiting rods (17) and rotating arm supporting rods (21) are fixedly connected to the rotating arms (22), secondary mirrors (12) are installed on the rotating arm supporting rods (21), the secondary mirrors (12) are convex spherical lenses, the convex surfaces of all the secondary mirrors (12) face the primary mirror (5), and the curvature radiuses of all the secondary mirrors (12) are different; a first motor (19) and a second motor (23) are respectively installed at two ends of the guide rail (14), control modules are installed on the first motor (19) and the second motor (23), and all the control modules are in signal connection with the computer (1); a second connecting support rod (20) is fixedly connected to the guide rail (14) between the first motor (19) and the rotating arm (22) adjacent to the first motor (19), the second connecting support rod (20) is positioned below the guide rail (14), a second laser reflector (13) with the inclination direction opposite to that of the first laser reflector (4) is arranged at the lower end of the second connecting support rod (20), and the included angle between the second laser reflector (13) and the horizontal plane is 45 degrees;

all the rotating arms (22) are connected with the computer (1) through a control circuit; limit switches with the same number as that of the rotating arms (22) are arranged on the grating ruler (15); the first motor (19) adopts a linear motor;

the beam expanding lens group (3) comprises a first biconcave lens (25) and a plano-convex lens (26) which are arranged side by side, and the convex surface of the plano-convex lens (26) is arranged away from the first biconcave lens (25); the first biconcave lens (25) is adjacent to the laser (2);

the focusing system (10) comprises a second biconcave lens (27), a first biconvex lens (28), a second biconvex lens (29) and a negative meniscus lens (30) which are arranged side by side in sequence, wherein the concave surface of the negative meniscus lens (30) faces to the second biconvex lens (29); the negative meniscus lens (30) is adjacent to the spectrometer (11).

2. The self-focusing device for laser-induced breakdown spectroscopy remote detection according to claim 1, wherein a limit rod (17) and a rotating arm support rod (21) are fixedly connected to an outer wall of a driven rotor of the electromagnetic clutch, and an included angle between the limit rod (17) and the rotating arm support rod (21) is 90 degrees; the driving rotor of the electromagnetic clutch is sleeved on the guide rail (14).

3. The self-focusing device for the remote detection of laser induced breakdown spectroscopy according to claim 1, wherein the second motor (23) is connected to the guide rail (14) by a spline coupling; the length of the internal spline and the length of the external spline in the spline coupling are different.

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