CN115016107A - Double-telecentric optical machine structure and light path system for coal quality analysis - Google Patents

Abstract

The invention discloses a double telecentric optical machine structure and an optical path system for coal quality analysis, belonging to the technical field of measurement, the double telecentric optical machine structure comprises a dichroic mirror and a collimating lens group, wherein the collimating lens group is aligned with the reflecting surface of the dichroic mirror, the double telecentric optical machine structure is characterized in that the collimating lens group comprises a first collimating lens, a second collimating lens and an aperture diaphragm, the first collimating lens is arranged to be aligned with the reflecting surface of the dichroic mirror, the second collimating lens is arranged at one side of the first collimating lens far away from the dichroic mirror, the aperture diaphragm is arranged at one side of the second collimating lens far away from the first collimating lens, the second collimating lens, the first collimating lens and the aperture diaphragm are coaxial, the double telecentric optical machine structure is used in the optical path system for coal quality analysis, so that when the system is used for continuous coal quality analysis, the spectrum signal of the coal dust can be stably collected, and the problem of signal drift of coal quality collection is solved.

Description

Double-telecentric optical machine structure and optical path system for coal quality analysis

Technical Field

The invention relates to the technical field of measurement, in particular to a double-telecentric optical machine structure and an optical path system for coal quality analysis.

Background

In a thermal power plant for coal-fired power generation, the quality of coal entering a combustion furnace needs to be detected, the main detection mode is field sampling, and then the coal is sent to a laboratory for sample preparation and offline analysis, the detection process is long, the efficiency is low, and the optimal operation requirement of a boiler based on an online rapid coal detection result is difficult to meet. In recent years, Laser Induced Breakdown Spectroscopy (LIBS) has been widely used for direct measurement of pulverized coal in a particle flow state. The LIBS directly measures the particle flow by focusing a pulse laser beam on the center of the free falling coal powder particle flow to ablate certain coal powder particles and further excite the coal powder particles to generate plasma, the spectrometer detects the spectral signal radiated by the plasma in the attenuation cooling process, and the species and the specific concentration data of the coal powder are obtained by analyzing the spectrum with specific wavelength and intensity.

Although LIBS direct measurement of particle flow has the advantage of sample preparation-free for coal dust detection, numerous studies have found that such measurement schemes have poor spectral signal stability. Because the number, the particle size and the spatial distribution of the particles near the laser focus are randomly changed, the interaction between the laser and the particles is very complicated, the generated plasma has obvious difference in form, and the central position of the plasma can drift back and forth of the laser focus.

The prior patent application with publication number CN112334484A discloses a method and a device for rapidly testing coal quality components of a coal-fired power plant on line. The method comprises the following steps: extracting coal powder from a coal powder pipeline of a coal-fired power plant, separating and trapping coal powder particles by using a cyclone separator, and uniformly mixing the coal powder particles and the coal powder particles to form two parts; measuring the moisture, ash content, volatile matter content and fixed carbon content of a part of the pulverized coal through industrial analysis based on temperature programmed weighing measurement; measuring the concentration of C, H, O, N, S element in another part of the coal powder through element analysis based on laser-induced breakdown spectroscopy; the method for measuring the dynamic flowing coal dust has the advantages that the sampling range is small, signal fluctuation caused by drift of the center position of the particle flow plasma cannot be compensated, data drift occurs, and the accuracy of the obtained result is limited.

In addition, patent application publication No. CN104931299A discloses a uniform continuous industrial powder sampling device and method for laser-induced detection. The problem that the solid powder cannot be uniformly and continuously sampled when the laser induction detection technology is applied to the online detection of the solid powder in industrial production is solved. The corresponding device comprises a sampling pipeline, a jet valve, a gas vibrator, a measuring chamber, a dustproof system and a powder concentration change measuring and compensating device, and the device and the method also have the problems of small sampling range and drift of data and have certain limitation.

Disclosure of Invention

One of the objectives of the present invention is to provide a double telecentric optical system structure, which solves the problem of mutual interference of optical signals caused by the deviation of collected light rays in a certain range.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

the utility model provides a two telecentric mirror structures, includes dichroic mirror and collimating lens group, collimating lens group aligns the plane of reflection of dichroic mirror, collimating lens group includes first collimating lens, second collimating lens and aperture diaphragm, first collimating lens sets to the alignment the plane of reflection of dichroic mirror, and second collimating lens sets up first collimating lens is kept away from one side of dichroic mirror, the aperture diaphragm sets up second collimating lens is kept away from one side of first collimating lens, second collimating lens first collimating lens with the aperture diaphragm is coaxial.

Preferably, the first collimating lens adopts a quartz meniscus concave-convex lens, and the second collimating lens adopts a quartz single convex lens, so that the light rays far away from the axis of the collimating lens group can be deflected and collimated.

Preferably, the focusing lens further comprises a focusing lens, the focusing lens comprises a first focusing lens and a second focusing lens, the first focusing lens is arranged to be aligned with the transmission surface of the dichroic mirror, the second focusing lens is arranged between the first focusing lens and the dichroic mirror, the first focusing lens is a quartz meniscus concave-convex lens, and the second focusing lens is a quartz plano-convex lens and is used for converging parallel light rays and controlling the position of a focus.

Preferably, the light source further comprises a receiving lens, and the receiving lens is arranged on one side of the collimating lens group away from the dichroic mirror and is used for receiving light and converging the light into a stable light spot.

Preferably, the receiving lens is a plano-convex lens, and the light converging effect is good.

Preferably, the optical-mechanical structure further comprises a right-angle prism, wherein the right-angle prism is arranged on one side, far away from the second collimating lens, of the aperture diaphragm and used for vertically deflecting light rays, changing the direction of light ray transmission and reducing the volume of the optical-mechanical structure.

Preferably, the protection lens is arranged to be aligned with the reflection surface of the dichroic mirror, and is used for protecting the dichroic mirror from being influenced by the external environment when the dichroic mirror reflects light.

Preferably, the receiving lens is a plano-convex lens, and the transmitted light is converged into light spots again and then is transmitted.

Preferably, the optical-mechanical system further comprises a case, wherein the case is used for protecting the dichroic mirror, the collimating lens group, the receiving lens and the reflecting mirror, preventing external environment from polluting the optical-mechanical structure, prolonging the service life of the optical-mechanical structure and reducing the failure rate.

The invention also aims to provide a light path system for coal quality analysis, which solves the problem that plasma light for continuous coal powder detection drifts in a certain range and improves the stability and accuracy of signal acquisition.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

an optical path system for coal quality analysis comprises a double telecentric optical machine structure, a first incident light ray, a second incident light ray and a spectrometer, wherein the first incident light ray is incident perpendicular to a reflection optical axis collinear with the axis of a collimating lens group and then passes through a transmission surface of a dichroic mirror and a protective lens, the focus of the first incident light ray is projected out of the protective lens, the second incident light ray is emitted from the focus of the first incident light ray and enters the machine box through the protective lens, the second incident light ray passes through the reflection surface of the dichroic mirror and is reflected into the collimating lens group, is collimated when passing through the first collimating lens and the second collimating lens and then is filtered by an aperture diaphragm, the rest part at the center is reflected into a receiving lens by the right-angle prism and is focused into convergent light rays by the receiving lens, and finally, the light is emitted to a receiving end of the spectrometer.

Preferably, the included angle between the dichroic mirror and the first incident light is 45 degrees, the first incident light is emitted by the pulse laser generator, the second incident light is plasma light formed by burning coal dust particles, the size of the optical path system can be reduced by a proper reflection angle, and the application range of the optical path system is improved.

The invention has the beneficial effects that:

(1) this two telecentric optical machine structures possess the two telecentric optical structures that receiving lens and collimating lens group constitute, buggy plasma can take place to drift, the radiation light of plasma only has the certain parallel propagation of chief ray part, and other parts exist certain contained angle with parallel light, when the position of plasma light changes, the contained angle of this part light changes, the facula size that forms at last also can change, two telecentric optical structures can be to the chief ray part collimation of plasma and collect, and block other non-parallel light parts, can stabilize the plasma light of central point drift in certain extent, clear collection.

(2) The collimating lens group of the double-telecentric optical machine structure is internally provided with the aperture diaphragm which can filter the pulverized coal plasma light, reduce the penetration of other interference light rays and improve the accuracy of spectrum collection.

(3) The incident light of the light path system is coaxial with the collected plasma light signal, and the plasma light signal is reflected twice by 90 degrees, so that the structural volume of the whole light path system is reduced, and the application range is improved.

Drawings

FIG. 1 is a diagram of a double telecentric optical system according to the present invention;

fig. 2 is a diagram of an optical path system for coal quality analysis according to the present invention.

Reference numerals:

1. a focusing lens; 11. a first focusing lens; 12. a second focusing lens; 2. a dichroic mirror; 3. a collimating lens group; 31. a first collimating lens; 32. a second collimating lens; 33. an aperture diaphragm; 4. a right-angle prism; 5. a chassis; 6. receiving a lens; 7. a fiber coupler; 8. protecting the lens; 9. a powder supply device; 91. powder falling port; r1, first incident ray; r2, second incident ray; r3, converging light rays; a1, incident optical axis; a2, reflection optic axis; a3, an exit optical axis; 101. a laser; 102. a spectrometer.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without inventive step based on the embodiments of the present invention, are within the scope of protection of the present invention.

As shown in fig. 1-2, an optical path system for coal analysis, mainly used for coal composition detection, includes a double telecentric optical structure, a laser 101, a spectrometer 102 and a powder supply device 9, the double telecentric optical structure includes a dichroic mirror 2 and a collimating lens group 3, the collimating lens group 3 is aligned with a reflective surface of the dichroic mirror 2, the collimating lens group 3 includes a first collimating lens 31, a second collimating lens 32 and an aperture stop 33, the first collimating lens 31 is disposed to be aligned with the reflective surface of the dichroic mirror 2, the second collimating lens 32 is disposed on a side of the first collimating lens 31 away from the dichroic mirror 2, the aperture stop 33 is disposed on a side of the second collimating lens 32 away from the first collimating lens 31, the second collimating lens 32, the first collimating lens 31 and the aperture stop 33 are coaxial, the powder supply device 9 is provided with a powder drop port 91, laser emitted by the laser 101 is aligned with a powder drop port 92, and is perpendicular to the powder discharging direction of the pulverized coal, the dichroic mirror 2 is positioned between the laser 101 and the powder supply device 9, and the spectrometer 102 is used for receiving plasma light generated by ablating pulverized coal particles passing through the collimating lens group 3.

Preferably, the first incident light ray R1 is incident perpendicularly to the reflection optical axis a2, sequentially passes through the transmission surface of the dichroic mirror 2 and the protective lens 8, the focal point of the first incident light ray R1 projects outside the protective lens 8, the second incident light ray R2 is emitted from the focal point of the first incident light ray R1, passes through the protective lens 8 and enters the case 5, the second incident light ray R2 passes through the reflection surface of the dichroic mirror 2, is reflected by 90 ° and enters the collimating lens group 3, passes through the first collimating lens 31 and the second collimating lens 32, is collimated, is partially filtered by the aperture stop 33, the central residual part is reflected by the right-angle prism 4 into the receiving lens 6, is condensed by the receiving lens 6 into a condensed light ray R3, and finally is incident on the receiving end of the spectrometer 102.

Preferably, the included angle between the mirror surface on one side of the dichroic mirror 2 and the incident optical axis a1 is 45 °, the included angle between the mirror surface on the other side of the dichroic mirror 2 and the reflection optical axis a2 is 45 °, the surface of the dichroic mirror 2 is coated with a film, light in a specific wavelength range can be completely reflected, meanwhile, light with a certain wavelength almost completely penetrates through the surface, the surface is used for the position, laser emitted by the laser 101 can be penetrated through the transmission surface of the dichroic mirror 2, plasma light formed by coal powder ablation can be completely reflected by the reflection surface of the dichroic mirror 2, the laser and the plasma light are on the same axis, the accuracy of spectrum sampling is guaranteed, and the system structure is simplified.

Preferably, the powder supply device 9 uses a vibration feeder to spray the pulverized coal particles from the powder dropping port 91, the particle diameter of the pulverized coal is smaller than 200 μm, the pulverized coal is transported to the powder dropping port 91 under high-frequency vibration, a cylindrical pulverized coal particle flow stream with a diameter of about 4mm is formed through free falling, the flow stream has a fixed central axis, and the analysis result is faster and more accurate due to the stable pulverized coal particle flow stream.

Preferably, the first collimating lens 31 is a quartz concave-convex lens, the second collimating lens 32 is a quartz single-convex lens, the quartz glass lens has high light transmittance, and good transmittance in ultraviolet to infrared bands, and experimental tests show that the parameter of the first collimating lens 31 is r1 ═ 204.921 mm; r2 ═ 140.425 mm; f is 886.953mm and the parameter of the second collimating lens is r1 is 122.061 mm; r2 ═ 297.481 mm; the best effect is achieved when f is 175.557 mm.

Preferably, this optical path system still is equipped with quick-witted case 5 and protective glass piece 8, and dichroic mirror 2, collimating lens group 3 and rectangular prism 4 are all installed in quick-witted case 5, and protective glass piece 8 adopts plane fused quartz glass lens, inlays on quick-witted case 5 is close to the lateral wall that supplies powder device 9, is in supplying between powder device 9 and dichroic mirror 2 for precision optics in the protective machine case 5 can not receive the influence of buggy dust when accepting buggy granule plasma light, has guaranteed received signal's stability and life.

Preferably, the spectrometer 102 is a multi-color spectrometer, which comprises an entrance slit, a dispersion system, an imaging system and one or more exit slits, wherein the dispersion element separates the electromagnetic radiation of the radiation source into the desired wavelength or wavelength region, and measures the intensity at the selected wavelength, and the photo-detectors such as photomultiplier tube measure the intensities at different wavelength positions of the spectral line, so as to analyze and measure the substance types of the pulverized coal according to the wavelength differences of different substances.

Furthermore, a focusing lens 1 is arranged on the coal light path system, the focusing lens 1 is arranged between a laser 101 and a dichroic mirror 2 and is used for converging light emitted by the laser to project the focus of the laser to the rear half part of a coal dust particle stream central shaft far away from the laser 101, the axis of the focusing lens 1 is superposed with an incident light axis A1, the focusing lens 1 consists of a first focusing lens 11 and a second focusing lens 12, the first focusing lens 11 is arranged to be aligned with a transmission surface of the dichroic mirror 2, the second focusing lens 12 is arranged between the first focusing lens 11 and the dichroic mirror 2, the first focusing lens 11 adopts a quartz concave-convex lens, the second focusing lens 12 adopts a quartz single convex lens and has the function of converging the laser energy to a space with the size of 100 mu m around the focus which is called as a focus volume, and the energy density in the focus volume exceeds the breakdown threshold value of the coal dust particle stream, the coal dust particles are broken down and ablated to generate plasma.

Preferably, the laser 101 is a pulse laser, the pulse laser refers to a laser in which a single laser pulse is less than 0.25 second and works once at intervals of a certain time, and has the characteristic of high output power, the laser used here outputs a gaussian laser beam with a wavelength of 1064nm, a pulse width of 8ns and a spot diameter, the laser beam is emitted into a focusing lens 1 formed by combining a first focusing lens 11 and a second focusing lens 12 in parallel, the laser beam is changed from a parallel state to a focusing state, during the focusing process, the laser beam penetrates through a dichroic mirror 2 and then penetrates through a protective lens 8, finally, a laser theoretical focus is formed at a rear half part of a coal dust particle stream central axis far away from the laser 101, thereby fully ablating coal dust particles in a short time and forming plasma, the laser theoretical focus of the focusing lens 1 is positioned behind the coal dust particle stream central axis, namely, the coal dust particles are ablated in the coal dust area of the laser beam, the interaction space of the light beam and the particle flow is enlarged, the number of particles ablated by the laser is increased, and the probability of serious drift of the central position of the plasma can be reduced.

Preferably, the centers of the circular light-emitting window of the laser 101, the laser focusing lens 1, the dichroic mirror 2 and the protective lens 8 should be strictly coaxial with the laser focus, that is, the centers of the above elements are all located on a laser incident optical axis a1, and the incident optical axis is perpendicular to the central axis of the pulverized coal particle stream, so that the laser can be vertically focused to the central axis of the pulverized coal particle stream.

Preferably, the optical path system is further provided with a right-angle prism 4, the right-angle prism 4 is a triangular reflecting mirror, and is arranged between the collimating lens group 3 and the spectrometer 102, and the collimated first incident light ray R1 is used for adjusting the angle of the collected light ray and reducing the volume of the optical path system.

Preferably, the centers of the right-angle prism 4, the collimating lens group 3 and the dichroic mirror 2 are coaxial with the reflection optical axis a2, the right-angle prism 4, the optical fiber coupler 7 and the receiving lens 6 also need to be coaxial, that is, the centers of the above elements are all overlapped with the exit optical axis A3, in addition, the pulverized coal plasma light is reflected twice by 90 ° before being converged to the receiving lens 6, the included angles between the dichroic mirror 2 and the laser incident optical axis a1 and the collimating lens group axis a2 are all kept at 45 °, and the included angles between the inclined plane of the right-angle prism 4 and the collimating lens group axis a2 and the exit optical axis A3 are all strictly kept at 45 °, so that the plasma light can be converged to the receiving end of the spectrometer 102.

Preferably, the receiving lens 6 is disposed on a side of the collimating lens group 3 away from the dichroic mirror 2, the receiving lens 6 is connected to the spectrometer 102 through an optical fiber, the spectral signal collected by the receiving lens 6 is transmitted to the spectrometer 102, so that the uniform transmission of the optical signal is realized, the attenuation in the transmission of the optical signal is reduced, the receiving lens 6 is a plano-convex lens made of quartz, and can receive the reflected light from the rectangular prism 4 and converge to form a light spot, the size of the light spot passing through the collimating lens group 3 is stable, the size of the light spot converged by the receiving lens 6 is also kept unchanged, and the plasma light converging optical axis a3 falls to the center of the receiving lens 6 and is projected to the receiving end of the spectrometer 102 through the optical fiber for analysis.

Preferably, the optical fiber coupler 7 is connected with the receiving lens 6 and the optical fiber, the optical fiber coupler 7 realizes detachable connection between the optical fiber and the optical fiber, two end faces of the optical fiber are precisely butted, so that light energy output by the transmitting optical fiber can be coupled into the receiving optical fiber to the maximum extent, and the influence of an intervening optical link on a system is small, the optical fiber coupler 7 is installed on an optical fiber installation adjusting frame, the position of an optical fiber connecting line can be adjusted, and the spectrometer 102 is convenient to install and observe by an operator.

The specific process of coal quality detection is as follows:

powder discharging: the powder supply device 9 discharges coal powder at a constant flow rate and flow velocity, and the flow section of the coal powder particle flow is in a regular shape; laser focusing: focusing the laser to the side of the pulverized coal stream axis far away from the laser 101; the laser positive and negative defocusing areas cover the coal powder flow beam; spectrum collection: starting a laser 101 to ablate coal dust particle flow, and collecting spectral information of coal dust plasma from the incidence direction of laser; the laser ablates the coal dust particle flow in a pulse mode; the coal dust plasma light is reflected by the dichroic mirror 2 and separated from the laser; information transmission: the spectral information is sent into the spectrometer 102 after the depth of field is expanded by the collimating lens group 3; and (3) information processing: the spectrometer 102 processes the spectral information to obtain the material composition and fraction data of the pulverized coal.

The plasma light transfer process is as follows:

laser emitted by a laser 101 passes through a focusing lens 1 along the direction of an incident light axis A1, passes through a transmission surface of a dichroic mirror 2, is converged on a pulverized coal particle flow and is ablated, strong light radiated by plasma of the pulverized coal particle flow firstly passes through a protective lens 8, enters a case 5, is deflected by a reflection surface of the dichroic mirror 2 for 90 degrees and is reflected into a collimating lens group 3, only light rays in a certain range of the center of drifting plasma light are transmitted in parallel to a reflection light axis A2, and the rest parts of the drifting plasma light and the reflection light axis A2 have certain included angles, when the position of the plasma light changes, the included angles also change, the size of light spots also changes, the collimating lens group 3 converts all the plasma light into light rays in parallel to the reflection light axis A2, the parallel plasma light passes through a right-angle prism 4, is reflected to a receiving lens 6 for 90 degrees and then is converged on an optical fiber coupler 7, the plasma light is transmitted to the multichannel spectrometer 102 through the optical fiber for light splitting and photoelectric conversion processing, and finally the characteristic spectrum of the pulverized coal particle flow is obtained through calculation.

The invention has the following effects:

the coal light path system adopts a double telecentric optical structure consisting of a receiving lens 6 and a collimating lens group 3, can collimate, converge and filter coal powder plasma light, the coal powder plasma can drift in a certain range along the direction of a reflection optical axis A2 when seen along the direction of a laser incidence optical axis A1, after collimation, the double telecentric optical structure can still stably and clearly collect the coal powder plasma light to the core optical fiber 3, the diameter of a light spot is kept not to be obviously changed after collection, the double telecentric optical structure can well adapt to the condition that the coal powder particle flow plasma drifts back and forth at the focus, when the drift range of the plasma light at the laser incidence optical axis A1 is +/-3 mm, the double telecentric optical detection structure can ensure that the size of the collected light spot at the receiving end of the optical fiber is not changed, thereby effectively overcoming the problem that the plasma light intensity received by the optical fiber drifts obviously along with the center position of the plasma, the stability of the spectral signal is improved.

The double-telecentric optical machine structure reduces the drift range of the particle flow coal powder plasma center position by reducing the spherical aberration of the focusing lens 1 and exciting coal powder particles in a laser defocusing area, and can be used for online component detection of materials without stable surfaces and moving states, such as solid powder, aerosol, liquid jet and the like by combining with other types of discharging devices.

Variations and modifications to the above-described embodiments may occur to those skilled in the art, which fall within the scope and spirit of the above description. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and modifications and variations of the present invention are also intended to fall within the scope of the appended claims. Furthermore, although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims (10)

1. The utility model provides a two telecentric mirror structures, includes dichroic mirror (2) and collimating lens group (3), collimating lens group (3) are aimed at the plane of reflection of dichroic mirror (2), characterized in that, collimating lens group (3) include first collimating lens (31), second collimating lens (32) and aperture stop (33), first collimating lens (31) set to aim at the plane of reflection of dichroic mirror (2), and second collimating lens (32) set up first collimating lens (31) are kept away from one side of dichroic mirror (2), aperture stop (33) set up second collimating lens (32) are kept away from one side of first collimating lens (31), second collimating lens (32) first collimating lens (31) with aperture stop (33) are coaxial.

2. The double telecentric optical engine arrangement of claim 1, wherein:

the first collimating lens (31) adopts a quartz meniscus concave-convex lens, and the second collimating lens (32) adopts a quartz single convex lens.

3. The double telecentric optical engine arrangement of claim 1, wherein:

still include focus lens (1), focus lens (1) includes first focus lens (11) and second focus lens (12), first focus lens (11) set up to aim at the transmission face of dichroic mirror (2), second focus lens (12) set up first focus lens (11) with between dichroic mirror (2), first focus lens (11) adopt quartzy meniscus concave-convex lens, second focus lens (12) adopt quartzy plano-convex lens.

4. A double telecentric optical machine configuration according to any one of the claims 1 to 3, characterized in that:

the device further comprises a receiving lens (6), and the receiving lens (6) is arranged on one side, far away from the dichroic mirror (2), of the collimating lens group (3).

5. The double telecentric optical engine arrangement of claim 4, wherein:

the receiving lens (6) is arranged as a plano-convex lens.

6. The double telecentric optical engine arrangement of claim 5, wherein:

the collimator further comprises a right-angle prism (4), and the right-angle prism (4) is arranged on one side, far away from the second collimating lens (32), of the aperture diaphragm (33).

7. The double telecentric optical engine arrangement of claim 6, wherein:

further comprising a protective lens (8), said protective lens (8) being arranged to be aligned with the reflective surface of said dichroic mirror (2).

8. The double telecentric optical engine arrangement of claim 7, wherein:

the device is characterized by further comprising a case (5), wherein the case (5) is used for protecting the dichroic mirror (2), the collimating lens group (3), the receiving lens (6) and the reflecting mirror (4).

9. An optical path system for coal quality analysis, comprising a double telecentric optical mechanism, a first incident ray (R1), a second incident ray (R2) and a spectrometer (102), wherein the double telecentric optical mechanism is the double telecentric optical mechanism of claim 8, the first incident ray (R1) is incident perpendicularly to the reflection optical axis (A2) collinear with the axis of the collimating lens group (3) and passes through the transmission surface of the dichroic mirror (2) and the protection lens (8), the focus of the first incident ray (R1) is projected outside the protection lens (8), the second incident ray (R2) is emitted from the focus of the first incident ray (R1) and passes through the protection lens (8) to enter the case (5), the second incident ray (R2) passes through the reflection surface of the dichroic mirror (2), is reflected into the collimating lens group (3), is collimated when passing through the first collimating lens (31) and the second collimating lens (32), is partially filtered by the aperture stop (33), is reflected into the receiving lens (6) by the right-angle prism (4), is condensed into convergent light rays (R3) by the receiving lens (6), and finally is emitted to the receiving end of the spectrometer (102).

10. The optical path system for coal quality analysis according to claim 9, characterized in that:

the included angle between the dichroic mirror (2) and the first incident light (R1) is 45 degrees, the first incident light (R1) is emitted by a pulse laser generator, and the second incident light (R2) is plasma light formed by ablation of pulverized coal particles.

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