A coaxial light source with observable interior

Abstract

The utility model discloses a kind of coaxial light sources of observable interior, including coaxial light source body, the coaxial light source body includes bottom plate, PCB board is equipped on the bottom plate, array arrangement LED lamp pearl is equipped on PCB board, LED lamp pearl side is equipped with diffuser plate, diffuser plate side away from LED lamp pearl is equipped with beam splitter, the beam splitter is obliquely arranged, LED lamp pearl horizontal light ray is emitted, light ray is sequentially passed through diffuser plate and beam splitter and is emitted downward, light ray is photographed and collected by the camera being set in upper portion after the reflection of the product to be detected;At least one side of the bottom plate is equipped with transparent side plate, unidirectional light film is plated in the transparent side plate, the light ray emitted by the LED lamp pearl cannot penetrate the transparent side plate, but external light ray passes through transparent side plate and unidirectional light film and enters interior, observe the PCB board and LED lamp pearl in interior;The utility model provides a kind of coaxial light source, which can observe internal working condition and is convenient for debugging and maintenance.

Description

Technical Field

[0001] This utility model relates to the field of coaxial light source technology, and in particular to a coaxial light source that allows for internal observation. Background Technology

[0002] Coaxial light sources provide more uniform illumination than traditional light sources while avoiding reflections from objects, thus improving the accuracy and reproducibility of machine vision.

[0003] Traditional coaxial light sources typically use metal or opaque plastic housings. Specifically, metal housings facilitate good heat dissipation, while opaque plastic housings help reduce costs and prevent internal light from escaping. However, neither of these structures allows observation of the internal working state of the light source, which is not conducive to debugging and troubleshooting.

[0004] Although the aluminum alloy casing has a certain heat dissipation performance, its thermal conductivity is still insufficient to quickly dissipate the heat generated by the LED array during long-term operation, which can easily lead to overheating and damage to the LED beads, affecting the stability and lifespan of the light source. In particular, under high-brightness operating mode, it will significantly shorten the lifespan of the light source.

[0005] Furthermore, when the internal LED beads malfunction, the fault location cannot be visually determined due to the obstruction of the outer casing. The casing must be disassembled for manual inspection, resulting in low maintenance efficiency and prolonged downtime, which affects production progress. Utility Model Content

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies, such as the inability to observe internal working conditions, insufficient heat dissipation, and inconvenient maintenance, and to provide a coaxial light source that allows observation of internal working conditions, has excellent heat dissipation, and is easy to debug and maintain.

[0007] To achieve the above objectives, this utility model provides a coaxial light source capable of observing the interior, comprising a coaxial light source body, a base plate, a PCB board mounted on the base plate, an array of LED beads mounted on the PCB board, a diffuser plate mounted on one side of each LED bead, and a beam splitter mounted on the side of the diffuser plate away from the LED bead, the beam splitter being tilted, the LED bead emitting light horizontally, the light passing sequentially through the diffuser plate and the beam splitter and exiting downwards, the light being reflected by the product under test and captured by a camera positioned above; at least one side of the base plate is equipped with a transparent side plate, the transparent side plate having a one-way light film coated inside, the light emitted by the LED bead cannot pass through the transparent side plate, but external light passes through the transparent side plate and the one-way light film to enter the interior, allowing observation of the internal PCB board and LED beads.

[0008] Preferably, the transparent side panel is made of high-temperature resistant transparent ceramic-coated polycarbonate, and the inner wall is coated with a nano-level transparent ceramic coating and a one-way transparent optical film.

[0009] Preferably, the PCB board is a transparent PCB board made of transparent thermally conductive material, and the PCB board has embedded conductive metal lines made of transparent conductive material to achieve electrical connection with the arrayed LED beads.

[0010] Preferably, a heat dissipation component is installed on the side of the PCB board away from the diffuser plate. The inner side of the heat dissipation component is in contact with the back of the PCB board, and the outer side is provided with heat dissipation protrusions. The heat dissipation protrusions are square and arranged in an array, and heat dissipation grooves are provided between the heat dissipation protrusions.

[0011] Preferably, the heat dissipation component and the PCB board are also equipped with a thermally conductive silicone pad. The thermally conductive silicone pad is filled between the heat dissipation component and the PCB board to transfer the heat generated on the PCB board to the heat dissipation component, and then transfer it to the external environment through the synergistic effect of the heat dissipation protrusions and heat dissipation grooves.

[0012] Preferably, the upper part of the base plate is provided with a top cover plate, and the end of the top cover plate away from the PCB board is provided with an intensifying lens. The light reflected by the product to be tested passes through the intensifying lens and is captured by the camera set on the top. The top cover plate is provided with a through groove for light to pass through, and a receiving groove is provided around the through groove. The intensifying lens is bonded inside the receiving groove.

[0013] Preferably, a heat dissipation component is installed between the base plate and the top cover plate. The upper part of the heat dissipation component is connected to the top cover plate by connecting bolts, and the lower part is connected to the base plate by connecting bolts. A rear end plate is also installed between the base plate and the top cover plate. The rear end plate is arranged opposite to the heat dissipation component. The base plate and the top cover plate form a receiving cavity through the support of the heat dissipation component and the rear end plate. The receiving cavity houses a PCB board, LED beads, a diffuser plate, and a beam splitter.

[0014] Preferably, the coaxial light source body also includes a power cord, the heat dissipation component is provided with a U-shaped groove, one end of the power cord is snapped into the U-shaped groove, and the end of the power cord is electrically connected to the PCB board to drive the LED beads to emit light.

[0015] Preferably, the transparent side panel includes a left side panel and a right side panel; the front ends of the left side panel and the right side panel are provided with a first mounting surface for installing heat dissipation components and a first mounting groove for installing a PCB board, the middle part is provided with a second mounting groove for installing a diffuser, and the rear end is provided with an inclined mounting groove for installing a beam splitter and a second mounting surface for installing a rear end panel.

[0016] Preferably, the lower part of the rear end plate is provided with a third mounting groove, the lower part of the beam splitter is inserted into the third mounting groove, and the upper part is resting against the upper part of the diffuser plate; the upper part of the inclined mounting groove is provided with a guide inclined surface, and the guide inclined surface guides the beam splitter to be inserted into the inclined mounting groove.

[0017] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0018] 1. This utility model, by setting a transparent side plate and coating a one-way light film on the inner side of the transparent side plate, prevents the light emitted by the LED beads from scattering outward through the transparent side plate, allowing it to only illuminate the diffuser plate. However, external light can pass through the transparent side plate and the one-way light film to enter the interior, enabling observation of the internal PCB board and LED beads. This allows for direct observation of the internal component status, such as the working status of the LED beads, circuit connections, and the integrity of optical components. This facilitates timely detection of abnormalities such as component aging, poor soldering, or light path misalignment, quickly identifying anomalies and reducing maintenance time. Simultaneously, the one-way light film design effectively improves the utilization efficiency of the light source and avoids brightness loss caused by light leakage.

[0019] 2. This utility model effectively improves the heat dissipation efficiency of LED beads during operation and extends the lifespan of the light source through the synergistic cooperation of heat dissipation components and thermally conductive silicone pads. In addition, the thermally conductive silicone pads are tightly attached to the LED beads and heat dissipation components, further strengthening the heat conduction path and ensuring rapid heat dissipation. Furthermore, the heat dissipation components are provided with heat dissipation protrusions, which increase the surface area in contact with air. At the same time, the heat dissipation grooves improve the air convection efficiency, accelerate heat dissipation, avoid local overheating, extend the lifespan of LED beads, and maintain optical stability.

[0020] 3. This utility model uses a U-shaped groove to secure the power cord, effectively preventing the power cord from loosening or shifting, ensuring a stable and reliable electrical connection, while also simplifying the assembly process and improving production efficiency. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the upper part of a coaxial light source that allows observation of its internal structure, provided by this utility model.

[0023] Figure 2This is a bottom schematic diagram of a coaxial light source with an observable interior, provided by this utility model;

[0024] Figure 3 This is a schematic diagram of the left side plate of a coaxial light source that allows for internal observation, provided by this utility model.

[0025] Figure 4 This is an internal schematic diagram of a coaxial light source with observable internal structure provided by this utility model;

[0026] Figure 5 This is a schematic diagram of the optical path of a coaxial light source that allows for internal observation, provided by this utility model;

[0027] Figure 6 This is an exploded view of a coaxial light source with an observable interior, provided by this utility model.

[0028] Figure 7 This is a schematic diagram of a coaxial light source with an observable interior, provided by this utility model, with the top cover removed.

[0029] Figure 8 This is an exploded view of the left side plate of a coaxial light source that allows observation of its internal components, provided by this utility model.

[0030] The diagram includes:

[0031] 1. Coaxial light source body; 11. Base plate; 12. PCB board; 13. LED beads; 14. Diffuser plate; 15. Beam splitter; 10. Product to be tested; 9. Camera; 2. Transparent side plate; 3. Heat dissipation component; 31. Heat dissipation protrusion; 32. Heat dissipation groove; 8. Thermal conductive silicone pad; 4. Top cover plate; 41. Intensifying lens; 42. Through groove; 43. Receiving groove; 6. Rear end plate; 5. Receiving cavity; 7. Power cord; 33. U-shaped groove; 21. Left side plate; 22. Right side plate; 23. First mounting surface; 24. First mounting groove; 25. Second mounting groove; 26. Inclined mounting groove; 27. Second mounting surface; 61. Third mounting groove; 261. Guide inclined surface. Detailed Implementation

[0032] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are one embodiment of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Please refer to Figures 1 to 8 This invention provides a coaxial light source that allows for internal observation.

[0034] like Figure 1 As shown, the coaxial light source body 1 has a cuboid structure, consisting of six plates bolted together. These six plates are a base plate 11, a top cover plate 4, transparent side plates 2, a heat dissipation component 3, and a rear end plate 6. The transparent side plates 2 include a left side plate 21 and a right side plate 22, with at least one side plate made of transparent material for easy observation of the internal structure of the light source. However, in this embodiment, both the left side plate 21 and the right side plate 22 are made of transparent material to allow for comprehensive observation of the assembly status and operation of the internal components from both sides. The design of the transparent side plates 2 not only facilitates real-time monitoring of the internal optical path alignment during assembly and debugging but also allows for intuitive judgment of the luminous uniformity of the LED beads 13 and the reflection state of the beam splitter 15 during equipment operation.

[0035] like Figure 3 As shown, the coaxial light source body 1 includes a base plate 11 at the bottom, and a PCB board 12 is mounted on its upper surface. Multiple LED beads 13 are arranged in an array on the PCB board 12 to provide uniform light source output. The arrayed LED beads 13 emit light horizontally, and the light diffuses horizontally and uniformly, improving the consistency of lighting.

[0036] Since the light is emitted horizontally by the array of LED beads 13, a diffuser plate 14 is provided in front of the LED beads 13. The diffuser plate 14 is used to uniformly scatter the light emitted by the LED beads 13 to form a uniform surface light source output.

[0037] like Figure 3 As shown, a beam splitter 15 is installed on the side of the diffuser plate 14 away from the LED beads 13. The beam splitter 15 is tilted at an angle of 45 degrees to reflect horizontally propagating light to the vertical direction, thereby achieving a coaxial lighting effect. The LED beads 13 emit light horizontally, and the light passes through the diffuser plate 14 and the beam splitter 15 in sequence before being emitted downwards. The light is reflected by the product to be tested 10 and captured by the camera 9 located at the top.

[0038] like Figure 3 As shown, at least one side of the base plate 11 is equipped with a transparent side plate 2. In this embodiment, the transparent side plate 2 is coated with a one-way light film, which prevents the light emitted by the LED beads 13 from passing through the transparent side plate 2, thereby avoiding light leakage that could interfere with imaging. At the same time, it allows external observers to clearly observe the luminous state of the LED beads 13, the light diffusion effect of the diffuser plate 14, and the reflection path of the beam splitter 15 through the transparent side plate 2, facilitating the rapid location of optical path deviations or component malfunctions during debugging and maintenance. The transparent side plate 2 is similar to a one-way viewing window in a prison, allowing only external vision to enter while preventing internal light from escaping, effectively ensuring the optical sealing of the light source cavity.

[0039] like Figure 3 As shown, the transparent side panel 2 is made of high-temperature resistant transparent ceramic-coated polycarbonate, such as Covestro PC2805, with a light transmittance greater than 90% and a heat distortion temperature ≥145°C. The inner wall of the transparent side panel 2 is coated with a nano-level transparent ceramic coating and a one-way transparent optical film layer. The nano-level transparent ceramic coating is TL2401, which combines high hardness and scratch resistance, with a hardness of up to 9H, providing wear resistance, corrosion resistance, and heat insulation protection. The one-way transparent optical film layer is composed of multiple dielectric films, achieving one-way light transmission based on the principle of optical interference, ensuring unobstructed visual access for light output and circuit management.

[0040] like Figure 3 As shown, the PCB board 12 is a transparent PCB board, and the PCB board 12 uses a transparent thermally conductive material, such as SABICLEXANLUX resin or KONDUIT compound, with a thermal conductivity as high as 15W / mK. The PCB board 12 has embedded conductive metal lines, which are made of transparent conductive materials, such as indium tin oxide (ITO), to achieve electrical connection with the arrayed LED beads 13 under high transparency.

[0041] Furthermore, the array distribution of the LED beads 13 can be optimized to ensure uniform heat distribution, reduce the risk of local heat accumulation, and improve heat dissipation efficiency.

[0042] Furthermore, to further improve heat dissipation efficiency, a heat dissipation component 3 is installed on the side of the PCB board 12 away from the diffuser plate 14. In one embodiment, the inner side of the heat dissipation component 3 contacts the back of the PCB board 12, and the outer side is provided with heat dissipation protrusions 31. The heat dissipation protrusions 31 are square and arranged in an array, with heat dissipation grooves 32 between them. The heat dissipation grooves 32 and heat dissipation protrusions 31 are arranged alternately, increasing the contact area between the heat dissipation component 3 and the air and promoting heat convection efficiency. At the same time, the heat dissipation component 3 is made of high thermal conductivity aluminum alloy material and has a microporous channel structure inside, further improving the heat conduction rate. Under continuous working conditions, heat is quickly transferred to the heat dissipation component 3 through the transparent PCB board 12, and is efficiently dissipated through the synergistic effect of the heat dissipation protrusions 31 and heat dissipation grooves 32, ensuring that the LED beads 13 operate stably within a safe temperature range and extending the service life of the light source system.

[0043] In this embodiment, to improve the thermal conductivity between the heat dissipation component 3 and the PCB board 12, a thermally conductive silicone pad 8 is installed between them. The thermally conductive silicone pad 8 fills the microscopic gap between the PCB board 12 and the heat dissipation component 3, effectively eliminating interfacial air stagnation and significantly reducing thermal resistance. The heat generated on the PCB board 12 is transferred to the heat dissipation component 3, and then transferred to the external environment through the synergistic effect of the heat dissipation protrusion 31 and the heat dissipation groove 32, achieving efficient heat dissipation.

[0044] like Figure 6 As shown, an upper cover plate 4 is installed on the upper part of the base plate 11. An intensifying lens 41 is installed on the end of the upper cover plate 4 away from the PCB board 12. The intensifying lens 41 is made of high light transmittance optical resin and has an anti-reflection film layer on its surface, which effectively reduces the reflection loss when light is incident and improves the overall light output efficiency.

[0045] like Figure 6 As shown, the light reflected from the product 10 under test passes through the intensifying lens 41 and is captured by the camera 9 located on the upper part. Further, to better facilitate the light's passage into the camera 9, the upper cover plate 4 has a through groove 42 for light to pass through. To accommodate the intensifying lens 41, a receiving groove 43 is provided around the through groove 42, and the intensifying lens 41 is bonded inside the receiving groove 43. In this embodiment, the receiving groove 43 is located at the lower part of the upper cover plate 4 and communicates with the through groove 42, ensuring a stable and well-sealed installation between the intensifying lens 41 and the upper cover plate 4, preventing dust or impurities from affecting optical performance. The edge of the intensifying lens 41 is completely embedded in the receiving groove 43 and bonded using optical adhesive, improving the overall structural integrity and long-term operational stability. After passing through the intensifying lens 41, the light passes through the through groove 42 without distortion and with low loss, accurately reaching the photosensitive element of the camera 9, ensuring image clarity and detection accuracy.

[0046] like Figure 3 As shown, a heat dissipation component 3 is installed between the base plate 11 and the upper cover plate 4. The upper part of the heat dissipation component 3 is connected to the upper cover plate 4 by connecting bolts, and the lower part is connected to the base plate 11 by connecting bolts. One side is connected to the left side plate 21 by connecting bolts, and the other side is connected to the right side plate 22 by connecting bolts, ensuring the stable positioning of the heat dissipation component 3 in the overall structure. Correspondingly, a rear end plate 6 is also installed between the base plate 11 and the upper cover plate 4. The rear end plate 6 is arranged opposite to the heat dissipation component 3. The base plate 11 and the upper cover plate 4 form a receiving cavity 5 through the support of the heat dissipation component 3 and the rear end plate 6. The receiving cavity 5 houses the PCB board 12, LED beads 13, diffuser plate 14, and beam splitter 15.

[0047] like Figure 7As shown, the coaxial light source body 1 also includes a power cord 7. The heat dissipation component 3 has a U-shaped groove 33, and one end of the power cord 7 is secured inside the U-shaped groove 33 to prevent displacement during installation or vibration, ensuring reliable electrical connection. The end of the power cord 7 is electrically connected to the PCB board 12, driving the LED beads 13 to emit light. After being emitted by the LED beads 13, the light is uniformly scattered by the diffuser plate 14 and then reflected by the beam splitter 15 to form a coaxial illumination path, ensuring uniform illumination and no shadows on the surface of the product 10 under test. The beam splitter 15 is fixed at a 45° angle inside the receiving cavity 5, with its coated surface facing the LED beads 13. Its transmittance is not less than 90%, and its reflectivity is adapted to lighting requirements, effectively improving light utilization.

[0048] like Figure 1 As shown, there are two transparent side panels 2, namely the left side panel 21 and the right side panel 22. They are installed on both sides of the base plate 11 and together with the base plate 11, the top cover plate 4, the heat dissipation component 3 and the rear end plate 6, they form a closed shell structure, which effectively protects the internal components from the influence of the external environment.

[0049] The left side plate 21 and the right side plate 22 have the same structure. The front end of each plate is provided with a first mounting surface 23 for mounting heat dissipation component 3 and a first mounting groove 24 for mounting PCB board 12. The middle part is provided with a second mounting groove 25 for mounting diffuser plate 14. The rear end is provided with an inclined mounting groove 26 for mounting beam splitter 15 and a second mounting surface 27 for mounting rear end plate 6.

[0050] The tilt angle of the inclined mounting groove 26 matches the 45° mounting angle of the beam splitter 15, ensuring that it is securely embedded and optically aligned.

[0051] Furthermore, the lower part of the rear end plate 6 is provided with a third mounting groove 61, into which the lower part of the beam splitter 15 is inserted and the upper part rests against the upper part of the diffuser plate 14; at the same time, the depth of the third mounting groove 61 is adapted to the thickness of the beam splitter 15 to ensure that it remains stable in position under vibration. Even further, the upper part of the inclined mounting groove 26 is provided with a guiding inclined surface 261, which guides the beam splitter 15 to be inserted into the inclined mounting groove 26.

[0052] The above embodiments are preferred embodiments of the present utility model, but the embodiments of the present utility model are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present utility model shall be considered equivalent substitutions and shall be included within the protection scope of the present utility model.

Claims

1. A coaxial light source capable of observing internal structures, characterized in that: The system includes a coaxial light source body (1), which includes a base plate (11). A PCB board (12) is mounted on the base plate (11). An array of LED beads (13) is mounted on the PCB board (12). A diffuser plate (14) is mounted on one side of each LED bead (13). A beam splitter (15) is mounted on the side of the diffuser plate (14) away from the LED beads (13). The beam splitter (15) is tilted. The LED beads (13) emit light horizontally. The light is emitted downwards through the diffuser (14) and beam splitter (15) in sequence. The light is reflected by the product to be tested (10) and captured by the camera (9) set on the top. At least one side of the base plate (11) is equipped with a transparent side plate (2). The transparent side plate (2) is coated with a one-way light film. The light emitted by the LED beads (13) cannot pass through the transparent side plate (2), but the external light passes through the transparent side plate (2) and the one-way light film to enter the interior and observe the PCB board (12) and LED beads (13) inside.

2. The coaxial light source capable of observing the interior according to claim 1, characterized in that: The transparent side panel (2) is made of high-temperature resistant transparent ceramic coated polycarbonate, and the inner wall is coated with a nano-level transparent ceramic coating and a one-way transparent optical film.

3. The coaxial light source capable of observing the interior according to claim 1, characterized in that: The PCB board (12) is a transparent PCB board. The PCB board (12) is made of transparent thermal conductive material. The PCB board (12) has an embedded conductive metal line. The conductive metal line is made of transparent conductive material to achieve electrical connection with the arrayed LED beads (13).

4. The coaxial light source capable of observing the interior according to claim 1, characterized in that: The PCB board (12) is provided with a heat dissipation component (3) on the side away from the diffuser plate (14). The inner side of the heat dissipation component (3) is in contact with the back of the PCB board (12), and the outer side is provided with heat dissipation protrusions (31). The heat dissipation protrusions (31) are square and arranged in an array. Heat dissipation grooves (32) are provided between the heat dissipation protrusions (31).

5. A coaxial light source capable of observing the interior according to claim 4, characterized in that: The heat dissipation component (3) and the PCB board (12) are also equipped with a thermally conductive silicone pad (8). The thermally conductive silicone pad (8) is filled between the heat dissipation component (3) and the PCB board (12) to transfer the heat generated on the PCB board (12) to the heat dissipation component (3) and to the external environment through the synergistic effect of the heat dissipation protrusion (31) and the heat dissipation groove (32).

6. A coaxial light source capable of observing the interior according to claim 4, characterized in that: The base plate (11) is equipped with an upper cover plate (4). An intensifying lens (41) is installed at the end of the upper cover plate (4) away from the PCB board (12). The light reflected by the product to be tested (10) passes through the intensifying lens (41) and is captured by the camera (9) set on the upper part. The upper cover plate (4) is provided with a through groove (42) for light to pass through. A receiving groove (43) is provided around the through groove (42). The intensifying lens (41) is bonded inside the receiving groove (43).

7. A coaxial light source capable of observing the interior according to claim 6, characterized in that: A heat dissipation component (3) is installed between the base plate (11) and the top cover plate (4). The upper part of the heat dissipation component (3) is connected to the top cover plate (4) by connecting bolts, and the lower part is connected to the base plate (11) by connecting bolts. A rear end plate (6) is also installed between the base plate (11) and the top cover plate (4). The rear end plate (6) is arranged opposite to the heat dissipation component (3). The base plate (11) and the top cover plate (4) form a receiving cavity (5) through the support of the heat dissipation component (3) and the rear end plate (6). The receiving cavity (5) contains a PCB board (12), LED beads (13), a diffuser plate (14), and a beam splitter (15).

8. A coaxial light source capable of observing the interior according to claim 4, characterized in that: The coaxial light source body (1) also includes a power cord (7). The heat dissipation component (3) is provided with a U-shaped groove (33). One end of the power cord (7) is inserted into the U-shaped groove (33). The end of the power cord (7) is electrically connected to the PCB board (12) to drive the LED beads (13) to emit light.

9. A coaxial light source capable of observing the interior according to claim 7, characterized in that: The transparent side panel (2) includes a left side panel (21) and a right side panel (22); the front ends of the left side panel (21) and the right side panel (22) are provided with a first mounting surface (23) for mounting heat dissipation components (3) and a first mounting groove (24) for mounting PCB board (12), the middle part is provided with a second mounting groove (25) for mounting diffuser (14), and the rear end is provided with an inclined mounting groove (26) for mounting beam splitter (15) and a second mounting surface (27) for mounting rear end panel (6).

10. A coaxial light source capable of observing the interior according to claim 9, characterized in that: The lower part of the rear end plate (6) is provided with a third mounting groove (61), the lower part of the beam splitter (15) is inserted into the third mounting groove (61), and the upper part is placed against the upper part of the diffuser plate (14); the upper part of the inclined mounting groove (26) is provided with a guide inclined surface (261), and the guide inclined surface (261) guides the beam splitter (15) to be inserted into the inclined mounting groove (26).

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