Induced water-jet guided laser generating device

Abstract

The invention discloses an induced water-guided laser generating device. A high-pressure water cavity is formed in a shell of a water-optical coupler of the induced water-guided laser generating device; a light-transmitting window is formed in the middle of a top plate of the shell and used for laser incidence. A water inlet is formed in the side wall of the shell and used for injecting water into the high-pressure water cavity. An induction channel coaxial with the light-transmitting window is formed in a bottom plate of the shell; the induction channel is in a frustum shape which is gradually reduced from top to bottom; the inner wall of the induction channel is plated with a mirror reflection film; high-pressure water in the high-pressure water cavity is jetted out from the lower end of the induction channel to form micro-jet, and the periphery of the micro-jet is surrounded by gas to form a water-gas interface. According to the induction type water-guided laser generating device, water-guided laser microjet with the outer diameter smaller than the diameter of a laser spot can be manufactured, the alignment requirement of the laser spot and an induction channel can be greatly lowered, and the water-guided laser coupling efficiency can be improved.

Description

Technical Field

[0001] The invention relates to laser processing technology, in particular to an induction type water-conducting laser generating device. Background Art

[0002] Water-guided laser is a laser processing method that combines laser with a "hair-thin" microjet to accurately guide the laser beam to the processing position through total reflection of pulses in the microjet in a manner similar to optical fiber. The water-guided laser microjet continuously cools the cutting area and effectively removes processing debris. As a unique "cooling, cleaning, and controllable" laser processing technology, it avoids major problems in conventional dry laser processing, such as thermal damage, contamination, processing speed, deformation, debris deposition, oxidation, microcracks, and taper.

[0003] Because traditional lasers are divergent beams, the working distance of focused laser beams is limited to only a few millimeters to a fraction of a millimeter, which not only requires precise focusing and distance control, but also limits the ratio of incision width to depth. Water-guided lasers use laser beams that are completely reflected at the air-water interface. The laser beam can be guided within a length of up to 100mm, thereby achieving high depth-to-diameter ratio incisions with parallel cutting edges, without the need for focusing or distance control during the processing process.

[0004] Due to the cooling capacity of the micro jet, the water-guided laser has almost no thermal damage (no heat-affected zone) and material microstructure changes in the processed material. The ablated material debris is washed away with the water flow, leaving a clean surface with no sediment or bottom burrs. Water-guided laser technology can effectively cut materials of various thicknesses. It can cut diamonds or silicon carbide up to 30mm thick, or drill high-temperature alloys up to 15mm thick with an aperture of 800µm. The water-guided laser beam is a cylindrical laser beam that can achieve tight, parallel incisions (incision size>25µm), the cut surface is parallel and has no taper, and the processing accuracy is as low as + / -1.5µm, which can significantly save material loss. The use of high-power lasers can achieve relatively higher cutting speeds while ensuring better quality. For example, the cutting speed for 7mm thick silicon is 45mm / min, and the cutting speed for 4mm thick chemical vapor deposition (CVD) grown diamonds is up to 5mm / min. Water-guided laser can process different types of materials (conductive or non-conductive). The processing process is a warm processing process, so water-guided laser technology is particularly suitable for processing brittle and hard materials or various composite materials that are easily damaged using traditional cutting processes, such as: ceramics, composite materials, metals, metal alloys, diamonds, hard materials, semiconductor materials, etc.

[0005] In the 1990s, Dr. Richerzhagen of the Swiss Federal Institute of Technology in Lausanne successfully coupled lasers with microjets as thin as a hair, so that the laser beam was transmitted to the processing point in the microjets in a manner similar to total internal reflection in the optical fiber. He became the first person in history to complete this work, and founded SYNOVA and developed the world's first laser microjet processing system, which is a milestone in the history of laser microjet processing technology. The advantages of this unique processing technology are very significant: ultra-precise, fast, clean and efficient processing, narrower incisions, and almost no thermal damage, contamination, and taper caused by beam divergence. This new "wet" laser processing method is superior to existing conventional processing technologies in many aspects, such as traditional "dry" lasers, electrical discharge machining (EDM), diamond saw blades, chemical processing, high-pressure water jet processing, milling and grinding.

[0006] As we all know, it is very difficult to combine laser with micro jet as thin as hair. The diameter of micro jet outlet is generally 25um~100um, while the minimum diameter of laser spot at the jet outlet of water optical coupler obtained in engineering is generally 10um~20um, which puts extremely high requirements on the alignment of laser and jet outlet. In addition, various factors such as errors and vibrations in equipment operation can easily cause the laser to hit the inner wall of the coupler and damage the coupler. The basic principle of Dr. Richerzhagen's coupling of laser with micro jet as thin as hair is that the minimum diameter of laser spot must be smaller than the diameter of micro jet, which means that the diameter of micro jet outlet is subject to the minimum diameter of laser spot actually obtained in existing engineering. It is impossible to produce a laser micro jet with a smaller diameter than the minimum diameter of laser spot actually obtained in engineering, which greatly limits the possibility of further reducing the diameter of water-guided laser micro jet.

[0007] At present, water-guided laser equipment is basically designed according to the water-light coupling model of Dr. Richerzhagen of the Swiss Federal Institute of Technology in Lausanne, that is, how to align the laser spot with the smallest diameter to the jet outlet which is very close to its diameter. This is a very difficult task and the technical cost of engineering implementation is also very high.

[0008] The Chinese invention patent document with the publication number CN107662046B discloses a water-guided laser processing coupling device for off-axis optical path, including a CCD (Charge Coupled Device), a Z-axis lens, a nozzle built into a coupling cavity and capable of XY movement with the coupling cavity as a whole, and a focusing lens. The CCD realizes the alignment imaging of the laser and the jet outlet, and then the Z-axis lens is adjusted in a closed loop to adjust the Z-axis position of the focal plane of the laser spot, and the XY displacement of the coupling cavity is adjusted to realize the alignment of the jet outlet of the coupling cavity and the laser spot on the XY plane. This scheme is basically similar to the visual alignment scheme currently used in the SYNOVA series of products founded by Dr. Richerzhagen. It realizes the alignment of the minimum diameter laser spot to the jet outlet very close to its diameter through expensive computer vision combined with closed-loop mechanical motion adjustment engineering technology, but does not realize low-cost, high robustness and high fault tolerance water-light coupling from the basic coupling principle, and cannot break through how to realize a water-guided laser microjet smaller than the minimum spot on the laser focal plane.

[0009] The Chinese utility model patent document with publication number CN216502987U discloses a water-guided laser water jet calibration device based on machine vision. Although this patent also provides a laser water jet calibration device based on vision, it is different from the Chinese invention patent document with publication number CN107662046B. It adds a laser lighting lamp and synthesizes the laser lighting light source into the laser processing optical circuit through a beam splitter prism. In addition, a camera is added above the processing platform next to the coupler at a certain observation angle to observe the processing light spot. This solution does not adopt the off-axis optical path of the Chinese invention patent document with publication number CN107662046B, but uses the shape of the processing light spot to reversely evaluate the coupling of the laser water jet and calibrate it. In actual operation, the camera has a certain observation angle, which will cause the light spot image distortion. In addition, the light spot shape will be randomly scattered during the process of laser processing the workpiece, making it difficult to evaluate this solution in real time and difficult to achieve real-time calibration of the laser water jet coupling during the workpiece processing. This solution is basically similar to the visual alignment solution currently used in the SYNOVA product series founded by Dr. Richerzhagen. It uses expensive computer vision combined with closed-loop mechanical motion adjustment to align the minimum diameter laser spot to a jet outlet that is very close to its diameter. It also fails to achieve low-cost, high-robustness and high-tolerance water-light coupling from the basic coupling principle, and cannot break through how to achieve a water-guided laser microjet smaller than the minimum spot on the laser focusing plane. Summary of the invention

[0010] The technical problem to be solved by the present invention is to provide an induced water-guided laser generating device, which can produce a water-guided laser microjet with an outer diameter smaller than the laser spot diameter, which can greatly reduce the alignment requirements between the laser spot and the jet channel and improve the water-guided laser coupling efficiency.

[0011] In order to solve the above technical problems, the present invention provides an induction type water-guided laser generating device, which includes a water-optical coupler; A high-pressure water chamber is formed in the housing of the water-optical coupler; A light-transmitting window is formed in the middle of the top plate of the shell for incident laser light; The side wall of the shell is formed with a water inlet for injecting water into the high-pressure water chamber; The bottom plate of the housing is formed with an induction channel coaxial with the light-transmitting window; The induction channel is in the shape of a cone that gradually shrinks from top to bottom; The inner wall of the induction channel is plated with a mirror reflection film; The high-pressure water in the high-pressure water chamber is ejected from the lower end of the induction channel to form a micro-jet, and the micro-jet is surrounded by gas to form a water-gas interface.

[0012] Preferably, the bottom plate of the shell is further formed with coaxial jet holes under the induction channel; The inner diameter of the jet hole is larger than the inner diameter of the lower end of the induction channel; High-pressure gas is injected into the jet hole to form a high-pressure gas cavity; The high-pressure water is sprayed from the lower end of the induction channel into the micro-jet in the jet hole, and the micro-jet is surrounded by the high-pressure gas to form a water-gas interface; The micro jet passes through the high-pressure air cavity in the jet hole and then shoots to the bottom of the bottom plate.

[0013] Preferably, the inner diameter of the jet hole increases first and then decreases from the upper end to the lower end; The inner diameter of the upper end of the jet hole is smaller than the inner diameter of the lower end of the jet hole; The bottom plate of the shell is formed with an air inlet which is laterally connected to the middle of the side wall of the jet hole and is used to inject high-pressure gas into the jet hole to form a high-pressure gas cavity in the jet hole.

[0014] Preferably, the induced water-conducting laser generating device further comprises a focusing lens; The focusing lens is coaxially arranged directly above the light-transmitting window; The collimated laser is irradiated coaxially downward from above the focusing lens.

[0015] Preferably, the angle between the side wall generatrix of the frustum-shaped induction channel and the axis is less than ; is the optically dense medium refractive index of water, is the optically thinning medium refractive index of the gas.

[0016] Preferably, the angle between the side wall generatrix of the frustum-shaped induction channel and the axis is greater than 3°.

[0017] Preferably, the gas is air, and the angle between the side wall generatrix of the frustum-shaped induction channel and the axis is less than 20.6°.

[0018] Preferably, the axial length of the induction channel is greater than the inner diameter of the upper end of the induction channel; The inner diameter of the upper end of the induction channel is 100um to 500um; The inner diameter of the lower end of the induction channel is 20um to 100um.

[0019] Preferably, the water pressure in the high-pressure water chamber is greater than the air pressure in the high-pressure air chamber; The water pressure in the high-pressure water chamber is greater than 2MPa; The air pressure in the high-pressure air cavity is greater than 2 KPa.

[0020] Preferably, the air pressure in the high-pressure air chamber is 1 / 8 to 1 / 12 of the water pressure in the high-pressure water chamber; The light-transmitting window is sealed and equipped with anti-reflection glass.

[0021] The induction channel of the induction type water-guided laser generating device of the present invention is in the shape of a cone, so that water in the high-pressure water chamber is more easily introduced into the laser induction channel, and fluid pressure mutation is not likely to occur at the entrance, and turbulence is not likely to occur. The high-pressure water in the high-pressure water chamber can form a more stable microjet after being ejected from the lower end of the induction channel; the induction channel is in the shape of a cone, so that a laser with a larger spot can be introduced into the microjet, breaking through the current limitation that the minimum laser spot diameter must be smaller than the outer diameter of the microjet, and a water-guided laser microjet with a smaller diameter than the laser spot can be obtained; the induction channel is in the shape of a cone, which greatly reduces the alignment accuracy requirement of the laser and the induction channel, and reduces the accuracy requirement and alignment difficulty during water-guided laser coupling. The induced water-guided laser generating device not only improves the alignment tolerance of the laser and the induced channel during the operation of the equipment, greatly reduces the alignment accuracy requirements of the laser and the induced channel, but also breaks through the basic principle that the laser spot must be smaller than the outer diameter of the microjet during water-light coupling. It can produce a water-guided laser microjet with an outer diameter smaller than the laser spot diameter, and can introduce more energy from the outer circle of the laser spot into the water-guided laser microjet, thereby improving the water-guided laser coupling efficiency, reducing multiple reflections and absorption of the outer circle energy in the water-light coupler, and maintaining a lower water temperature and a better water-light coupling effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for use in the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 It is a structural schematic diagram of an embodiment of an induction type water-conducting laser generating device of the present invention; Figure 2 yes Figure 1 Schematic diagram of local structures related to laser-induced channels; Figure 3 It is a schematic diagram and a partial close-up diagram of the induction effect of the axis-parallel incident laser of one embodiment of the induction-type water-conducting laser generating device of the present invention; Figure 4 It is a schematic diagram and a partial close-up diagram of the induction effect of the non-parallel incident laser of an embodiment of the induction type water-guided laser generating device of the present invention; Figure 5 It is a schematic diagram of the critical angle analysis of total reflection between water and air medium; Figure 6 It is a schematic diagram of the analysis of the laser-induced critical angle with parallel and non-parallel axes.

[0024] Description of reference numerals: 1. Water-optical coupler; 2. High-pressure water chamber; 3. Focusing lens; 4. Collimated laser; 5. Microjet; 10. Shell; 11. Light-transmitting window; 12. Water inlet; 13. Air inlet; 15. Jet hole; 16. Induction channel; 17. High-pressure air chamber. DETAILED DESCRIPTION

[0025] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] Embodiment 1: An induction type water-conducting laser generating device Figure 1 As shown, it includes a water optical coupler 1; A high-pressure water chamber 2 is formed in the housing 10 of the water-optical coupler 1; A light-transmitting window 11 is formed in the middle of the top plate of the housing 10 for incident laser light; The side wall of the housing 10 is formed with a water inlet 12 for injecting water into the high-pressure water chamber 2; The bottom plate of the housing 10 is formed with an induction channel 16 coaxial with the light-transmitting window 11; The induction channel 16 is in the shape of a cone that gradually shrinks from top to bottom; The inner wall of the induction channel 16 is plated with a mirror reflection film; The high-pressure water in the high-pressure water chamber 2 is ejected from the lower end of the induction channel 16 to form a micro jet 5, and the micro jet 5 is surrounded by gas to form a water-gas interface.

[0027] like Figure 3 As shown, the angle between the incident laser and the axis parallel to the axis is The angle between the side wall generatrix of the frustum-shaped induction channel 16 and the axis is The angle between the axis parallel incident laser and the generatrix of the side wall of the frustum-shaped induction channel 16 is , after being reflected by the mirror surface of the side wall of the induction channel 16, the laser entering the microjet 5 forms a total reflection at the water-gas interface of the microjet 5. The angle between the laser entering the microjet 5 and the generatrix of the microjet 5 is .

[0028] like Figure 4 As shown, the angle between the side wall generatrix of the frustum-shaped induction channel 16 and the axis is After the mirror reflection of the side wall of the induction channel 16, the laser forms a total reflection at the water-air interface of the microjet 5, and the angle between the laser and the microjet generatrix is .

[0029] like Figure 5 As shown, according to Snell's law, we know that: ; but ; but ; Since the refractive index of water is 1.33, .

[0030] like Figure 6 As shown, the geometric relationship of the left half of the axis parallel to the incident laser is: ; .

[0031] The geometric relationship of the non-parallel incident laser in the right half is: ; ; .

[0032] Depend on Figure 6 It can be seen that: ; .

[0033] According to the above derivation process, assuming that the refractive index of the optically dense medium of water is The refractive index of the light-scarce medium of the gas is , with the axis of the frustum-shaped induction channel 16 as a reference, the angle between the side wall generatrix of the frustum-shaped induction channel 16 and the axis should be less than .

[0034] like Figure 6 As shown, taking water and air as specific media, the angle between the side wall generatrix of the frustum-shaped induction channel 16 and the axis should be less than 20.6°. Under this angle condition, the frustum-shaped induction channel 16 not only meets the induction conditions of axis-parallel laser, but also meets the induction conditions of axis-non-parallel laser, and the axis-parallel light is the induction boundary condition, that is, the axis-non-parallel incident laser is easier to be induced, and it is easier to achieve total reflection of the laser in the microjet formed at the jet outlet 15.

[0035] Preferably, the angle between the side wall generatrix of the frustum-shaped induction channel 16 and the axis is greater than 3°.

[0036] In the induced water-guided laser generating device of the first embodiment, the induction channel 16 is in the shape of a cone, the water in the high-pressure water chamber 2 is more easily introduced into the laser induction channel 16, the fluid pressure mutation is not easy to occur at the entrance, and turbulence is not easy to occur. The high-pressure water in the high-pressure water chamber 2 can form a more stable microjet 5 after being ejected from the lower end of the induction channel 16; the induction channel 16 is in the shape of a cone, and a larger spot of laser light can be introduced into the microjet 5, breaking through the current limitation that the minimum spot diameter of the laser must be smaller than the outer diameter of the microjet 5, and a water-guided laser microjet 5 with a smaller spot diameter than the laser can be obtained; the induction channel 16 is in the shape of a cone, which greatly reduces the alignment accuracy requirements of the laser and the induction channel 16, and reduces the accuracy requirements and alignment difficulty during water-guided laser coupling.

[0037] The induced water-conducting laser generating device of the first embodiment not only improves the alignment tolerance of the laser and the induction channel 16 during the operation of the device, greatly reduces the alignment accuracy requirements of the laser and the induction channel 16, but also breaks through the basic principle that the laser spot must be smaller than the outer diameter of the microjet 5 during water-light coupling. A water-conducting laser microjet 5 with an outer diameter smaller than the laser spot diameter can be produced, and more energy of the outer circle of the laser spot can be introduced into the water-conducting laser microjet 5, thereby improving the water-conducting laser coupling efficiency, reducing multiple reflections and absorption of the outer circle energy in the water-light coupler 1, and maintaining a lower water temperature and a better water-light coupling effect.

[0038] Embodiment 2: Based on the induction type water-conducting laser generating device of embodiment 1, Figure 2As shown, the bottom plate of the housing 10 is also formed with a coaxial jet hole 15 under the induction channel 16; The inner diameter of the jet hole 15 is larger than the inner diameter of the lower end of the induction channel 16; High-pressure gas is injected into the jet hole 15 to form a high-pressure gas cavity 17; The high-pressure water is sprayed from the lower end of the induction channel 16 to the micro jet 5 in the jet hole 15, and the micro jet 5 is surrounded by the high-pressure gas to form a water-gas interface; The micro jet 5 passes through the high pressure air cavity 17 in the jet hole 15 and then is ejected toward the bottom of the bottom plate.

[0039] Preferably, the inner diameter of the jet hole 15 increases first and then decreases from the upper end to the lower end; The inner diameter of the upper end of the jet hole 15 is smaller than the inner diameter of the lower end of the jet hole 15; The bottom plate of the housing 10 is formed with an air inlet 13 which is laterally connected to the middle of the side wall of the jet hole 15 and is used to inject high-pressure gas into the jet hole 15 to form a high-pressure gas cavity 17 in the jet hole 15 .

[0040] In the induction water-guided laser generating device of the second embodiment, the bottom plate of the water-optical coupler 1 housing 10 is further formed with a coaxial jet hole 15 under the induction channel 16 , and the jet hole 15 is used to inject high-pressure gas to form a high-pressure gas cavity 17 .

[0041] Embodiment 3: Based on the induction type water-conducting laser generating device of embodiment 2, the induction type water-conducting laser generating device further includes a focusing lens 3; The focusing lens 3 is coaxially arranged just above the light-transmitting window 11; The collimated laser 4 is irradiated coaxially downward from above the focusing lens 3 .

[0042] Embodiment 4: Based on the induction type water-guided laser generating device of embodiment 2, the axial length of the induction channel 16 is greater than the inner diameter of the upper end of the induction channel 16 .

[0043] Preferably, the inner diameter of the upper end of the induction channel 16 is 100um to 500um.

[0044] Preferably, the inner diameter of the lower end of the induction channel 16 is 20um to 100um.

[0045] Preferably, the water pressure in the high-pressure water chamber 2 is greater than the air pressure in the high-pressure air chamber 17 .

[0046] Preferably, the water pressure in the high-pressure water chamber 2 is greater than 2 MPa.

[0047] The air pressure in the high-pressure air chamber 17 is greater than 2 KPa.

[0048] Preferably, the air pressure in the high-pressure air chamber 17 is 1 / 8 to 1 / 12 of the water pressure in the high-pressure water chamber 2 .

[0049] Preferably, the light-transmitting window 11 is sealed with anti-reflection glass.

[0050] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An induction water-guided laser generating device, characterized in that: comprising a water optical coupler (1); A high-pressure water chamber (2) is formed in the housing (10) of the water-optical coupler (1); A light-transmitting window (11) is formed in the middle of the top plate of the housing (10) for incident laser light; The side wall of the housing (10) is formed with a water inlet (12) for injecting water into the high-pressure water chamber (2); The bottom plate of the housing (10) is formed with an induction channel (16) coaxial with the light-transmitting window (11); The induction channel (16) is in the shape of a cone that gradually shrinks from top to bottom; The inner wall of the induction channel (16) is coated with a mirror reflection film; The high-pressure water in the high-pressure water chamber (2) is ejected from the lower end of the induction channel (16) to form a micro jet (5), and the micro jet (5) is surrounded by gas to form a water-gas interface; The angle between the side wall generatrix of the frustum-shaped induction channel (16) and the axis is less than ; is the optically dense medium refractive index of water, is the optically thinning medium refractive index of the gas.

2. The induction water-guided laser generating device according to claim 1, characterized in that: The bottom plate of the housing (10) is further formed with coaxial jet holes (15) below the induction channel (16); The inner diameter of the jet hole (15) is larger than the inner diameter of the lower end of the induction channel (16); High-pressure gas is injected into the jet hole (15) to form a high-pressure gas cavity (17); High-pressure water is sprayed from the lower end of the induction channel (16) into the micro jet (5) in the jet hole (15), and the micro jet (5) is surrounded by high-pressure gas to form a water-gas interface; The micro jet (5) passes through the high-pressure air cavity (17) in the jet hole (15) and then is ejected toward the bottom of the bottom plate.

3. The induction water-guided laser generating device according to claim 2, characterized in that: The inner diameter of the jet hole (15) increases first and then decreases from the upper end to the lower end; The inner diameter of the upper end of the jet hole (15) is smaller than the inner diameter of the lower end of the jet hole (15); The bottom plate of the housing (10) is formed with an air inlet (13) which is laterally connected to the middle of the side wall of the jet hole (15) and is used to inject high-pressure gas into the jet hole (15) to form a high-pressure gas cavity (17) in the jet hole (15).

4. The induction water-guided laser generating device according to claim 1, characterized in that: The induced water-conducting laser generating device further comprises a focusing lens (3); The focusing lens (3) is coaxially arranged directly above the light-transmitting window (11); The collimated laser (4) is irradiated coaxially downward from above the focusing lens (3).

5. The induction water-guided laser generating device according to claim 1, characterized in that: The axial length of the induction channel (16) is greater than the inner diameter of the upper end of the induction channel (16).

6. The induction water-guided laser generating device according to claim 1, characterized in that: The angle between the side wall generatrix of the frustum-shaped induction channel (16) and the axis is greater than 3°.

7. The induction water-guided laser generating device according to claim 1, characterized in that: The gas is air, and the angle between the side wall generatrix of the frustum-shaped induction channel (16) and the axis is less than 20.6°.

8. The induction water-guided laser generating device according to claim 1, characterized in that: The inner diameter of the upper end of the induction channel (16) is 100um to 500um; The inner diameter of the lower end of the induction channel (16) is 20 um to 100 um.

9. The induction water-guided laser generating device according to claim 2, characterized in that: The water pressure in the high-pressure water chamber (2) is greater than the air pressure in the high-pressure air chamber (17); The water pressure in the high-pressure water chamber (2) is greater than 2 MPa; The air pressure in the high-pressure air cavity (17) is greater than 2 KPa.

10. The induction water-guided laser generating device according to claim 2, characterized in that: The air pressure in the high-pressure air chamber (17) is 1 / 8 to 1 / 12 of the water pressure in the high-pressure water chamber (2); The light-transmitting window (11) is sealed with anti-reflection glass.

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