High-pressure water guide laser system

Abstract

The invention discloses a high-pressure water-guided laser system. A water-optical coupler of the high-pressure water-guided laser system comprises an upper structural member, a middle structural member and a lower structural member which are sequentially fixed together from top to bottom; a high-pressure water cavity is formed between the upper structural part and the middle structural part; a high-pressure air cavity is formed between the middle structural part and the lower structural part; the output fiber is vertically and fixedly assembled in the center of the upper structural member top plate; the cladding of the output fiber and the lower end of the fiber core main body are flush with the lower side surface of the upper structural member top plate; a vertically-through nozzle is formed in the center of the middle structural part. A vertically-through outlet hole is formed in the center of a bottom plate of the lower structural part. The fiber core, the nozzle and the outlet hole are coaxial; the minimum inner diameter of the nozzle is smaller than the minimum inner diameter of the outlet hole and larger than the outer diameter of the fiber core. According to the high-pressure water-guided laser system, the cladding and the fiber core are not prone to deformation or damage, reliability is high, the structure is simple, assembling is convenient, cost is low, and water explosion can be effectively reduced.

Description

Technical Field

[0001] The present invention relates to laser processing technology, and particularly to a high-pressure water-guided laser system. Background Art

[0002] Laser processing utilizes the high energy density of a laser beam to irradiate a material, causing the material to rapidly heat up locally and undergo melting, vaporization, or chemical changes, thereby achieving processing effects such as material cutting, welding, and marking. Laser processing has the characteristics of non-contact, high precision, strong material applicability, high processing speed, and high flexibility, and is currently widely used in multiple fields such as automobile manufacturing, aerospace, and the electronics industry.

[0003] Water-guided laser technology couples a laser beam into a high-pressure micro water beam (jet), and utilizes the total reflection phenomenon at the water-air interface to enable the laser to transmit in the water beam and be precisely guided to the surface of the material to be processed. Without the need for fine focusing, high-precision and high-quality processing can be achieved. The water beam not only plays a role in conducting the laser, but also has cooling and cleaning functions, which can effectively reduce the heat affected zone and material damage during the processing.

[0004] Due to the high precision requirements for the coupling of the laser and the high-pressure micro water beam (jet), existing laser jet coupling structures are often complex in structure, difficult to assemble, and high in manufacturing and maintenance costs.

[0005] A direct-coupled water-guided laser coupling system disclosed in Chinese patent document CN112775540A requires the optical fiber to be coupled with the jet after passing through an optical lens, and the structure is relatively complex; A medical water-guided laser system disclosed in Chinese patent document CN118141510A uses a direct water-light coupling structure, with low precision and low jet water pressure (less than 0.5 MPa), and is only applicable to the medical field and difficult to be applied to industrial applications that require high-pressure jets. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a high-pressure water-guided laser system, in which the cladding and the core are not easily deformed or damaged, with high reliability, simple structure, convenient assembly, low cost, and can effectively reduce water explosion.

[0007] To solve the above technical problem, the high-pressure water-guided laser system provided by the present invention includes an output optical fiber and a water-light coupler; The water-light coupler includes an upper structural member, an intermediate structural member, and a lower structural member that are fixedly connected together in sequence from top to bottom; A high-pressure water chamber is formed between the upper structural member and the intermediate structural member, and the water pressure in the high-pressure water chamber is 1 MPa to 200 MPa; A high-pressure air cavity is formed between the middle structural member and the lower structural member. The air pressure in the high-pressure air cavity is less than the water pressure in the high-pressure water cavity and greater than 0.2 MPa. The output optical fiber is vertically and fixedly assembled at the center of the top plate of the upper structural member. The lower end faces of the cladding and the core body of the output optical fiber are flush with the lower side surface of the top plate of the upper structural member. A nozzle penetrating up and down is formed at the center of the middle structural member. An outlet hole penetrating up and down is formed at the center of the bottom plate of the lower structural member. The core, the nozzle and the outlet hole are coaxial. The minimum inner diameter of the nozzle is less than the minimum inner diameter of the outlet hole and greater than the outer diameter of the core.

[0008] Preferably, the output optical fiber is directly vertically and fixedly assembled at the center of the top plate of the upper structural member. A circular plate-shaped transparent protective lens is provided at the lower ends of the cladding and the core of the output optical fiber. The outer diameter of the transparent protective lens is greater than the outer diameter of the cladding of the output optical fiber. The lower side surface of the transparent protective lens is flush with the lower side surface of the top plate of the upper structural member.

[0009] Preferably, a screw hole is formed at the center of the top plate of the upper structural member. The output optical fiber is fixed at the center of a metal tube with an external thread. The lower ends of the cladding and the core body of the output optical fiber are flush with the lower end surface of the metal tube. The metal tube is threadedly fitted with the screw hole and assembled and fixed to the top plate of the upper structural member.

[0010] Preferably, a crown portion extending radially outward is formed at the upper end of the metal tube. A washer is provided between the crown portion and the top plate of the upper structural member. The washer is used for sealing to ensure that the water in the high-pressure water cavity will not leak out. A circular plate-shaped transparent protective lens is provided at the lower ends of the cladding and the core of the output optical fiber. The outer diameter of the transparent protective lens is greater than the outer diameter of the cladding of the output optical fiber. The lower side surface of the transparent protective lens is flush with the lower side surface of the top plate of the upper structural member. The upper side surface of the transparent protective lens is attached to the lower end surface of the metal tube.

[0011] Preferably, the material of the transparent protective lens is sapphire, ruby or diamond. An inlet for injecting high-pressure water into the high-pressure water cavity is formed on the side wall of the upper structural member. An air inlet for injecting high-pressure air into the high-pressure air cavity is formed on the side wall of the lower structural member. The output optical fiber consists of a coating, a cladding, and a core; The coating and the cladding are wrapped around the core, and the cladding is located between the coating and the core.

[0012] Preferably, the minimum inner diameter of the nozzle is greater than the outer diameter of the core body of the output optical fiber.

[0013] Preferably, the nozzle is divided into a cylindrical upper part and a frustum-shaped lower part with a larger upper diameter and a smaller lower diameter; The minimum inner diameter of the nozzle is the inner diameter of the cylindrical upper part.

[0014] Preferably, the high-pressure water flow in the high-pressure water chamber flows downward after reaching the nozzle to form a high-pressure micro water beam; The high-pressure micro water beam consists of a constriction section and a stabilization section in the water-light coupler; The constriction section is at the top of the high-pressure micro water beam, and its diameter gradually decreases from top to bottom; The stabilization section is cylindrical; The diameter of the stabilization section is 0.2 to 0.95 times the minimum inner diameter of the nozzle; The marginal rays of the laser beam emitted from the core of the output optical fiber will fall on the water-vapor interface of the constriction section. After at least one total reflection in the constriction section, finally all the laser light is transmitted to the stabilization section and undergoes total internal reflection in the stabilization section; ; Among them, is the critical angle of total reflection at the water-vapor interface, is the exit angle of the laser beam from the core to the water; is the angle between the marginal ray of the laser beam emitted from the core and the water-vapor interface at the first reflection point in the constriction section, is the angle between the marginal ray at the (N - 1)-th reflection point and the water-vapor interface in the constriction section, is the angle between the marginal ray at the last reflection point and the water-vapor interface in the constriction section.

[0015] Preferably, a downward protrusion is formed at the lower end of the core body of the output optical fiber; The protrusion is a spherical crown shape or a conical shape with a larger upper diameter and a smaller lower diameter; The height h of the protrusion is less than the outer diameter of the core body of the output optical fiber.

[0016] Preferably, the high-pressure water-guided laser system further includes an input optical fiber, a collimating lens, a beam splitter, a focusing lens, and a detection device; The input optical fiber, the collimating lens, the focusing lens, and the output optical fiber are arranged coaxially from top to bottom in sequence; The beam splitter is arranged between the collimating lens and the focusing lens, and the beam splitter is arranged at an angle of 45° to the axis; The beam splitter is used to direct the laser beam emitted downward by the collimating lens to the output optical fiber through the focusing lens, and separate the reflected beam emitted upward by the output optical fiber through the focusing lens to the detection device; The divergent beam emitted from the lower end of the input optical fiber forms a collimated beam after passing through the collimating lens, passes downward through the beam splitter, and is coupled into the output optical fiber by the focusing lens; The detection device is used to convert the laser beam fed back by the beam splitter into an electrical signal; The reflected beam emitted upward by the output optical fiber through the focusing lens includes at least one of the laser beam fed back from the end face of the output optical fiber and the laser beam fed back by the output optical fiber. After the reflected beam is focused by the focusing lens, it passes through the beam splitter to separate the reflected beam and enters the detection device; The electrical signal is used to reflect the coupling quality of the output optical fiber end face, the laser jet coupling quality, and / or the state of the processed surface of the workpiece; The detection device includes an imaging lens group and a photoelectric conversion element; The photoelectric conversion element is at least one of an array CCD, a CMOS array, a single photodiode, or a silicon photocell.

[0017] In the high-pressure water-guided laser system of the present invention, the lower end of the core of the output optical fiber fixedly assembled at the center of the top plate of the upper structural member emits a laser beam at a small angle. The laser beam passes through the high-pressure water chamber and enters the downwardly ejected high-pressure micro water jet (jet) at the nozzle to achieve coupling. The high-pressure micro water jet (jet) after coupling the laser passes through the high-pressure gas chamber, and the outer layer is wrapped with high-pressure protective gas to form a water-gas interface. The laser beam emitted from the lower end of the core of the output optical fiber satisfies the total reflection condition of the water-gas interface, and its energy is completely coupled into the high-pressure micro water jet (jet). The high-pressure micro water jet (jet) after coupling the laser falls on the processed surface of the workpiece through the outlet hole; since the minimum inner diameter of the nozzle is smaller than the minimum inner diameter of the outlet hole, the high-pressure protective gas will be ejected from the periphery of the high-pressure micro water jet (jet) to form a high-pressure gas protection layer. In this high-pressure water-guided laser system, since the cladding of the output optical fiber fixedly assembled on the top plate of the upper structural member and the lower end face of the core main body are flush with the lower side surface of the top plate of the upper structural member, the core is not easily affected by the high-pressure water flow in the high-pressure water chamber. Even if the water pressure in the high-pressure water chamber is as high as 100 MPa, the core is not easily deformed or damaged, and the equipment has high reliability; the laser beam is directly emitted from the lower end of the core of the output optical fiber fixedly assembled at the center of the top plate of the upper structural member at a small angle and enters the high-pressure water chamber. In the design and assembly of the components, only the concentricity of the output optical fiber and the nozzle needs to be ensured. The number of components to be adjusted is small, the structure is simple, it is convenient for assembly, and the cost is low; moreover, the laser beam is directly emitted from the lower end of the core of the output optical fiber fixedly assembled at the center of the top plate of the upper structural member at a small angle and enters the high-pressure water chamber. The laser energy density distribution is more uniform, avoiding the problem that the focusing lens is likely to cause too high local energy density, effectively reducing problems such as water explosion caused by too concentrated local energy, and increasing the upper limit of the laser energy coupled by the jet. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the present invention, the following briefly introduces the drawings required for the present invention. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0019] Figure 1 FIG. is a schematic structural diagram of an embodiment of the high-pressure water-guided laser system of the present invention; Figure 2 FIG. is a schematic diagram of the shape of the core body of an embodiment of the high-pressure water-guided laser system of the present invention; Figure 3 FIG. is a schematic diagram of a spherical crown-shaped convex portion formed at the lower end of the core body of an embodiment of the high-pressure water-guided laser system of the present invention; Figure 4 FIG. is a schematic diagram of a conical convex portion formed at the lower end of the core body of an embodiment of the high-pressure water-guided laser system of the present invention; Figure 5 FIG. is a schematic diagram of directly vertically fixing and assembling the output optical fiber at the center of the top plate of the upper structural member in an embodiment of the high-pressure water-guided laser system of the present invention; Figure 6 FIG. is a schematic diagram of fixing and assembling the output optical fiber at the center of the top plate of the upper structural member through a metal tube with an external thread in an embodiment of the high-pressure water-guided laser system of the present invention; Figure 7 FIG. is a schematic diagram of fixing and assembling the output optical fiber at the center of the top plate of the upper structural member through a metal tube with an external thread and provided with a transparent protective lens in an embodiment of the high-pressure water-guided laser system of the present invention; Figure 8 FIG. is a schematic diagram of flow reduction coupling in an embodiment of the high-pressure water-guided laser system of the present invention.

[0020] DESCRIPTION OF THE REFERENCE NUMERALS: 11 Input optical fiber; 12 Collimating lens; 13 Beam splitter; 14 Detection device; 141 Imaging lens group; 142 Photoelectric conversion element; 15 Focusing lens; 16 Output optical fiber; 161 Core; 162 Cladding; 163 Coating; 2 Water-light coupler; 21 Upper structural member; 22 High-pressure water chamber; 23 Intermediate structural member; 24 High-pressure gas chamber; 25 Lower structural member; 26 High-pressure micro water beam; 27 High-pressure gas protection layer; 28 Nozzle; 29 Metal tube; 210 Washer; 211 Transparent protective lens; 3 Workpiece to be processed; 31 Processing surface. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] The technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0022] Embodiment 1: A high-pressure water-guided laser system, as Figure 1 shown, which includes an output optical fiber 16 and a water-optical coupler 2; The water-optical coupler 2 includes an upper structural member 21, an intermediate structural member 23, and a lower structural member 25 that are fixedly connected together in sequence from top to bottom; A high-pressure water chamber 22 is formed between the upper structural member 21 and the intermediate structural member 23, and the water pressure in the high-pressure water chamber 22 is 1 MPa to 200 MPa; A high-pressure gas chamber 24 is formed between the intermediate structural member 23 and the lower structural member 25. The air pressure in the high-pressure gas chamber 24 is less than the water pressure in the high-pressure water chamber 22 and greater than 0.2 MPa; The output optical fiber 16 is vertically fixedly assembled at the center of the top plate of the upper structural member 21. The cladding 162 and the lower end face of the main body of the core 161 of the output optical fiber 16 are flush with the lower side of the top plate of the upper structural member 21, as Figure 2 、 Figure 3 、 Figure 4 shown; A nozzle 28 that penetrates up and down is formed at the center of the intermediate structural member 23; An outlet hole 251 that penetrates up and down is formed at the center of the bottom plate of the lower structural member 25; The core 161, the nozzle 28, and the outlet hole 251 are coaxial; The minimum inner diameter of the nozzle 28 is less than the minimum inner diameter of the outlet hole 251 and greater than the outer diameter of the core 161.

[0023] The core 161 of the output optical fiber 16 selects appropriate parameters according to the inner diameter of the nozzle 28 and the thickness of the high-pressure water chamber 22, which can achieve better coupling effect.

[0024] The upper structural member 21, the intermediate structural member 23, and the lower structural member 25 can be integrally formed.

[0025] The upper structural member 21, the intermediate structural member 23, and the lower structural member 25 can also each include multiple components.

[0026] For the high-pressure water-guided laser system of Embodiment 1, the lower end of the core 161 of the output optical fiber 16 fixedly assembled at the center of the top plate of the upper structural member 21 has a small angle (when the numerical aperture NA of the output optical fiber is 0.22, the emission angle of the laser entering the water chamber A laser beam is emitted at an angle (about 9.5°). The laser beam passes through the high-pressure water chamber 22 and enters the downwardly ejected high-pressure micro-water beam (jet) 26 at the nozzle 28 to achieve coupling. The high-pressure micro-water beam (jet) 26 after coupling the laser passes through the high-pressure gas chamber 24, and a water-gas interface is formed by wrapping the outer layer with high-pressure protective gas. The laser beam emitted from the lower end of the core 161 of the output optical fiber 16 satisfies the total reflection condition of the water-gas interface, and its energy is completely coupled into the high-pressure micro-water beam (jet) 26. The high-pressure micro-water beam (jet) 26 after coupling the laser falls on the processing surface 31 of the workpiece 3 through the hole 251. Since the minimum inner diameter of the nozzle 28 is smaller than the minimum inner diameter of the hole 251, the high-pressure protective gas will be ejected from the periphery of the high-pressure micro-water beam (jet) 26 to form a high-pressure gas protection layer 27.

[0027] In the high-pressure water-guided laser system of the first embodiment, since the cladding 162 of the output optical fiber 16 fixedly assembled on the top plate of the upper structural member 21 and the lower end surface of the main body of the core 161 are flush with the lower side surface of the top plate of the upper structural member 21, the core 161 is not easily affected by the high-pressure water flow in the high-pressure water chamber 22. Even if the water pressure in the high-pressure water chamber 22 is as high as 100 MPa, the core 161 is not easily deformed or damaged, and the equipment has high reliability. The laser beam is directly emitted from the lower end of the core 161 of the output optical fiber 16 fixedly assembled at the center of the top plate of the upper structural member 21 at a small angle and enters the high-pressure water chamber 22. In the design and assembly of the components, only the concentricity of the output optical fiber 16 and the nozzle 28 needs to be ensured. The number of components to be adjusted is small, the structure is simple, it is convenient for assembly, and the cost is low. Moreover, the laser beam is directly emitted from the lower end of the core 161 of the output optical fiber 16 fixedly assembled at the center of the top plate of the upper structural member 21 at a small angle and enters the high-pressure water chamber 22. The laser energy density distribution is more uniform, avoiding the problem that the focusing lens is likely to cause too high local energy density, and can effectively reduce problems such as water explosion caused by too concentrated local energy, and improve the upper limit of the jet-coupled laser energy.

[0028] Embodiment 2: Based on the high-pressure water-guided laser system of Embodiment 1, as Figure 5 shown, the output optical fiber 16 is directly vertically fixedly assembled at the center of the top plate of the upper structural member 21; A circular plate-shaped transparent protective lens 211 is provided at the lower ends of the cladding 162 and the core 161 of the output optical fiber 16; The outer diameter of the transparent protective lens 211 is larger than the outer diameter of the cladding 162 of the output optical fiber 16; The lower side surface of the transparent protective lens 211 is flush with the lower side surface of the top plate of the upper structural member 21.

[0029] In the high-pressure water-guided laser system of Embodiment 2, the transparent protective lens 211 is provided at the lower ends of the cladding 162 and the core 161 of the output optical fiber 16 to ensure that the laser beam reliably passes through the transparent protective lens 211 from the output optical fiber 16 and enters the high-pressure water chamber 22, and can extend the service life of the output optical fiber 16.

[0030] Embodiment 3: Based on the high-pressure water-guided laser system of Embodiment 1, as Figure 6 shown, a screw hole is formed in the center of the top plate of the upper structural member 21; The output optical fiber 16 is fixed in the center of a metal tube 29 having an external thread; The cladding 162 and the main body of the core 161 of the output optical fiber 16 are flush with the lower end surface of the metal tube 29; The metal tube 29 is threadedly fitted with the screw hole and assembled and fixed to the top plate of the upper structural member 21.

[0031] Preferably, a crown portion extending radially outward is formed at the upper end of the metal tube 29; A washer 210 is provided between the crown portion and the top plate of the upper structural member 21; The washer 210 is used for sealing to ensure that the water in the high-pressure water chamber 22 does not leak out.

[0032] Preferably, as Figure 7 shown, a circular plate-shaped transparent protective lens 211 is provided at the lower ends of the cladding 162 and the core 161 of the output optical fiber 16; The outer diameter of the transparent protective lens 211 is larger than the outer diameter of the cladding 162 of the output optical fiber 16; The lower side surface of the transparent protective lens 211 is flush with the lower side surface of the top plate of the upper structural member 21; The upper side surface of the transparent protective lens 211 is attached to the lower end surface of the metal tube 29.

[0033] For the high-pressure water-guided laser system of Embodiment 3, the output optical fiber 16 is fixed in an independent metal tube 29 having an external thread, and then assembled and fixed to the center of the top plate of the upper structural member 21 through the metal tube 29, and the assembly is more flexible.

[0034] Embodiment 4: Based on the high-pressure water-guided laser system of Embodiment 2 or 3, the minimum inner diameter of the nozzle 28 is larger than the outer diameter of the main body of the core 161 of the output optical fiber 16.

[0035] Preferably, the nozzle 28 is divided into a cylindrical upper part and a lower frustum-shaped part with a larger upper part and a smaller lower part; The minimum inner diameter of the nozzle 28 is the inner diameter of the cylindrical upper part.

[0036] Preferably, the material of the transparent protective lens 211 is sapphire, ruby or diamond.

[0037] Preferably, a water inlet is formed on the side wall of the upper structural member 21 for injecting high-pressure water into the high-pressure water chamber 22.

[0038] Preferably, an air inlet is formed on the side wall of the lower structural member 25 for injecting high-pressure gas into the high-pressure gas chamber 24.

[0039] Preferably, the output optical fiber 16 is composed of a coating 163, a cladding 162, and a core 161; The coating 163 and the cladding 162 are wrapped outside the core 161, and the cladding 162 is located between the coating 163 and the core 161.

[0040] The coating 163 mainly plays a protective role and does not directly affect the laser transmission performance. It can be removed at joints or the like according to needs, or can be made of a metal material.

[0041] Embodiment 5: Based on the high-pressure water-guided laser system of Embodiment 1, the high-pressure water flow in the high-pressure water chamber 22 flows to the nozzle 28 and then shoots downward to form a high-pressure micro water beam (jet) 26; As Figure 8 shown, the high-pressure micro water beam (jet) 26 is composed of a constriction section 261 and a stable section 262 in the water-light coupler; The constriction section 261 is located at the top of the high-pressure micro water beam (jet) 26, and its diameter gradually decreases from top to bottom; The stable section 262 is cylindrical; The diameter of the stable section 262 is 0.2 to 0.95 times the minimum inner diameter of the nozzle; the diameter of the stable section 262 is closely related to factors such as water pressure, air pressure, and cavity structure; The marginal rays of the laser beam emitted from the core 161 of the output optical fiber 16 will fall on the water-gas interface of the constriction section 261. After at least one total reflection in the constriction section 261, finally all the laser light is transmitted to the stable section 262 and undergoes total internal reflection in the stable section 26.

[0042] When the high-pressure water flow in the high-pressure water chamber 22 enters the nozzle 28, a constriction phenomenon will occur, and it will leave the inner wall of the nozzle to form a stable high-pressure micro water beam (jet) 26 with a diameter smaller than the inner diameter of the nozzle 28. Therefore, the high-pressure micro water beam (jet) 26 can be divided into a constriction section 261 and a stable section 262. The marginal rays of the laser beam should satisfy the following conditions when they first fall on the water-gas interface of the constriction section 261 and undergo total reflection: ; Among them, is the critical angle of total reflection at the water-gas interface. According to the refractive indices of water and air , the angle is about 48.8°; is the exit angle of the laser beam from the core 161 into the water; is the angle between the marginal ray of the laser beam emitted from the core 161 and the water-gas interface at the first reflection point in the constriction section 261.

[0043] The subsequent marginal rays also need to satisfy the total reflection condition at the water-vapor interface. At the last reflection point (the Nth reflection point) of the flow constriction section 261, the angle between the marginal ray and the water-vapor interface needs to satisfy the condition: ; where is the angle between the marginal ray and the water-vapor interface from the first to the last reflection point (the Nth reflection point) of the flow constriction section 261. It can be seen from Equation (2) that the condition for total reflection in the stable section 262 is determined by the angle of the marginal ray of the first landing point on the water-vapor interface of the stable section 262, and it is required that all previous landing points satisfy the total reflection condition. If the Nth reflection point of the marginal ray starting from the flow constriction section 261 is the first reflection point on the water-vapor interface of the stable section 262, it can be seen from Equation (2) that the condition for complete coupling at this time is: ; Generally, the divergence angle of the laser beam is small, and the second reflection point can reach the stable section of the jet. At this time, Equation (3) can be simplified as: ; According to Equation (3) or Equation (4), the critical condition for complete coupling of the laser jet in the flow constriction coupling mode can be calculated, and then the parameters of the high-pressure water cavity, nozzle and other structures can be optimized. At this time, the jet diameter in the stable section 262 can be close to or even smaller than the core diameter 161 of the output optical fiber 16.

[0044] When the conditions of Equation (3) or Equation (4) need to be satisfied, the jet diameter D1 is not only smaller than the minimum inner diameter D1 of the nozzle, but also smaller than the divergence diameter D2 of the first landing point of the marginal ray of the laser beam. The optical path from the marginal ray of the laser beam to the first landing point is shorter, the divergence diameter is smaller, and through the beam constriction of the flow constriction section 261, a water jet with a smaller diameter can finally be formed.

[0045] Example 6: Based on the high-pressure water-guided laser system of Examples 1 to 5, a downward protrusion is formed at the lower end of the main body of the core 161 of the output optical fiber 16; The protrusion is a spherical crown shape with a larger upper part and a smaller lower part (as shown in Figure 3 ) or a conical shape (as shown in Figure 4 ); The height h of the protrusion is smaller than the outer diameter of the main body of the core 161 of the output optical fiber 16.

[0046] In the high-pressure water-guided laser system of Example 6, a slightly downward protrusion is formed at the lower end of the main body of the output optical fiber 16. By changing the angle of the protrusion, the direction of the laser beam emitted from the core 161 can be changed, and the emission angle can be effectively reduced, and a more concentrated laser beam, even a collimated beam or a focused beam, can be obtained.

[0047] Embodiment Seven: Based on Embodiment One, as Figure 1 shown, the high-pressure water-guided laser system further includes an input optical fiber 11, a collimating lens 12, a beam splitter 13, a focusing lens 15, and a detection device 14; The input optical fiber 11, the collimating lens 12, the focusing lens 15, and the output optical fiber 16 are arranged coaxially from top to bottom in sequence; The beam splitter 13 is disposed between the collimating lens 12 and the focusing lens 15, and the beam splitter 13 is arranged at an angle of 45° with respect to the axis; The beam splitter 13 is configured to direct the laser beam emitted downward by the collimating lens 12 to the output optical fiber 16 through the focusing lens 15, and separate the reflected beam emitted upward by the output optical fiber 16 through the focusing lens 15 to the detection device 14; The divergent beam emitted from the lower end of the input optical fiber 11 forms a collimated beam after passing through the collimating lens 12, passes downward through the beam splitter 13, and is coupled into the output optical fiber 16 by the focusing lens 15; The detection device 14 is configured to convert the laser beam fed back by the beam splitter 13 into an electrical signal.

[0048] Preferably, the reflected beam emitted upward by the output optical fiber 16 through the focusing lens 15 includes at least one of the laser beam fed back from the end face of the output optical fiber 16 and the laser beam fed back by the output optical fiber 16. After the reflected beam is focused by the focusing lens 15, the reflected beam is separated by the beam splitter 13 and enters the detection device 14; The electrical signal is used to reflect the coupling quality of the end face of the output optical fiber 16, the coupling quality of the laser jet, and / or the state of the processing surface 31 of the workpiece 3.

[0049] Preferably, the detection device 14 includes an imaging lens group 141 and a photoelectric conversion element 142; The photoelectric conversion element 142, the photoelectric conversion element 142, can be a linear or two-dimensional array device, such as a CCD, a CMOS array, etc., or a single optoelectronic device, such as a single-body photodiode, a silicon photovoltaic cell, etc.

[0050] The high-pressure water-guided laser system of Embodiment 7. The laser emitted by the laser passes through the input optical fiber 11 and emits. The light beam emitted by the input optical fiber 11 is coupled into the output optical fiber 16 through the collimating lens 12, the beam splitter 13 and the focusing lens 15. The beam splitter 13 reflects the feedback beam in the optical path to the detection device 14. When the laser cannot be well coupled into the output optical fiber 16 and the water jet, reflection will occur. When the laser jet reaches the machining surface 31 of the workpiece 3, according to the condition of the machining surface 31, part of the laser will also be reflected. The energy magnitude and distribution of these reflected lasers are affected by the coupling quality of the output optical fiber 16 and the water jet, and the state of the machining surface 31. These reflected lasers return along the original optical path, are reflected by the beam splitter 13 into the detection device 14, and are imaged on the photoelectric conversion element 142 through the imaging lens group 141 and converted into electrical signals. The output signal of the detection device 14 reflects the state of the reflected beam. By processing these output signals, a numerical evaluation of the coupling quality of the end face of the output optical fiber 16, the coupling quality of the laser jet, and / or the state of the machining surface 31 of the workpiece 3 can be realized, and the real-time detection of the end face coupling quality, the laser jet coupling quality, and / or the state of the machining surface 31 of the workpiece 3 can be realized. It can be used to adjust the two links of the end face coupling of the output optical fiber and the laser jet coupling, improve the coupling quality, and can provide real-time data basis for the intelligent adjustment of machining parameters, providing a reliable basis for the real-time diagnosis of equipment failures and the real-time judgment of machining progress.

Claims

1. A high-pressure water-guided laser system, characterized in that: It includes an output optical fiber (16) and a water optical coupler (2); The water-light coupler (2) comprises an upper structural component (21), an intermediate structural component (23), and a lower structural component (25) which are fixed together in sequence from top to bottom; A high-pressure water chamber (22) is formed between the upper structural member (21) and the middle structural member (23), and the water pressure in the high-pressure water chamber (22) is 1 MPa to 200 MPa; A high-pressure air chamber (24) is formed between the middle structural member (23) and the lower structural member (25), wherein the air pressure in the high-pressure air chamber (24) is lower than the water pressure in the high-pressure water chamber (22) and is greater than 0.2 MPa; The output optical fiber (16) is vertically fixedly mounted in the center of the top plate of the upper structural component (21), and the cladding (162) and the lower end surface of the core (161) of the output optical fiber (16) are flush with the lower side surface of the top plate of the upper structural component (21); A nozzle (28) is formed in the center of the intermediate structure (23) and passes through the middle and the middle structure (23); An outlet hole (251) is formed in the center of the bottom plate of the lower structure (25) and passes through from top to bottom. The fiber core (161), the nozzle (28) and the outlet hole (251) are coaxial; The minimum inner diameter of the nozzle (28) is smaller than the minimum inner diameter of the outlet hole (251), and is larger than the outer diameter of the fiber core (161).

2. The high-pressure water-guided laser system according to claim 1, characterized in that: The output optical fiber (16) is directly and vertically fixedly assembled in the center of the top plate of the upper structural member (21); The cladding (162) and the lower end of the fiber core (161) of the output optical fiber (16) are provided with a circular plate-shaped transparent protective lens (211); The outer diameter of the transparent protective lens (211) is greater than the outer diameter of the cladding (162) of the output optical fiber (16); The lower side surface of the transparent protective lens (211) is flush with the lower side surface of the top plate of the upper structural component (21).

3. The high-pressure water-guided laser system according to claim 1, characterized in that: A screw hole is formed in the center of the top plate of the upper structure (21); The output optical fiber (16) is fixed in the center of a metal tube (29) having an external thread; The cladding (162) and the lower end of the main body of the fiber core (161) of the output optical fiber (16) are flush with the lower end surface of the metal tube (29); The metal tube (29) is threadably matched with the screw hole and assembled to be fixed to the top plate of the upper structural member (21).

4. The high-pressure water-guided laser system according to claim 3, characterized in that: A crown portion extending radially outward is formed at the upper end of the metal tube (29); A gasket (210) is provided between the crown and the top plate of the upper structural member (21); The gasket (210) is used for sealing to ensure that water in the high-pressure water chamber (22) does not leak out; The cladding (162) and the lower end of the fiber core (161) of the output optical fiber (16) are provided with a circular plate-shaped transparent protective lens (211); The outer diameter of the transparent protective lens (211) is greater than the outer diameter of the cladding (162) of the output optical fiber (16); The lower side surface of the transparent protective lens (211) is flush with the lower side surface of the top plate of the upper structural member (21); The upper side surface of the transparent protective lens (211) is bonded to the lower end surface of the metal tube (29).

5. The high-pressure water-guided laser system according to claim 2 or 4, characterized in that: The material of the transparent protective lens (211) is sapphire, ruby ​​or diamond; A water inlet is formed on the side wall of the upper structure (21) for injecting high-pressure water into the high-pressure water chamber (22); A gas inlet is formed on the side wall of the lower structural member (25) for injecting high-pressure gas into the high-pressure gas cavity (24); The output optical fiber (16) is composed of a coating (163), a cladding (162) and a core (161); The coating (163) and the cladding (162) are wrapped around the fiber core (161), and the cladding (162) is located between the coating (163) and the fiber core (161).

6. The high-pressure water-guided laser system according to claim 1, characterized in that: The minimum inner diameter of the nozzle (28) is greater than the outer diameter of the core (161) of the output optical fiber (16).

7. The high-pressure water-guided laser system according to claim 1, characterized in that: The nozzle (28) is divided into a cylindrical upper portion and a frustum-shaped lower portion which is larger at the top and smaller at the bottom; The minimum inner diameter of the nozzle (28) is the inner diameter of the cylindrical upper part.

8. The high-pressure water-guided laser system according to claim 1, characterized in that: The high-pressure water in the high-pressure water chamber (22) flows to the nozzle (28) and is ejected downward to form a high-pressure micro-water jet (26); The high-pressure micro water jet (26) is composed of a contraction section (261) and a stabilization section (262) in the water-light coupler; The contraction section (261) is located at the top of the high-pressure micro-water jet (26), and its diameter gradually decreases from top to bottom; The stabilizing section (262) is cylindrical; The diameter of the stabilizing section (262) is 0.2 to 0.95 times the minimum inner diameter of the nozzle; The edge light of the laser beam emitted from the core (161) of the output optical fiber (16) falls on the water-air interface of the contraction section (261), and after at least one total reflection in the contraction section (261), all the laser light is finally transmitted to the stable section (262) and fully emitted in the stable section (262); ； in, is the critical angle of total reflection at the water-air interface, is the exit angle of the laser beam from the fiber core (161) into the water; is the angle between the edge ray of the laser beam emitted from the fiber core (161) and the water-air interface at the first reflection point in the contraction section (261), is the angle between the edge ray of the N-1th reflection point of the contraction section (261) and the water-air interface, is the angle between the edge light of the last reflection point of the contraction section (261) and the water-air interface.

9. The high-pressure water-guided laser system according to claim 1, characterized in that: A downward protrusion is formed at the lower end of the main body of the fiber core (161) of the output optical fiber (16); The protrusion is in the shape of a spherical cap or a cone, which is larger at the top and smaller at the bottom. The height h of the protruding portion is smaller than the outer diameter of the main body of the fiber core (161) of the output optical fiber (16).

10. The high-pressure water-guided laser system according to claim 1, characterized in that: The high-pressure water-conducting laser system further comprises an input optical fiber (11), a collimating lens (12), a beam splitter (13), a focusing lens (15) and a detection device (14); The input optical fiber (11), the collimating lens (12), the focusing lens (15), and the output optical fiber (16) are coaxially arranged in sequence from top to bottom; The beam splitter (13) is arranged between the collimating lens (12) and the focusing lens (15), and the beam splitter (13) is arranged at 45 degrees to the axis; The beam splitter (13) is used to guide the laser beam emitted downward from the collimating lens (12) to the output optical fiber (16) via the focusing lens (15), and to separate the reflected light beam emitted upward from the output optical fiber (16) via the focusing lens (15) to the detection device (14); The divergent light beam emitted from the lower end of the input optical fiber (11) passes through the collimating lens (12) to form a collimated light beam, passes downward through the beam splitter (13), and is coupled into the output optical fiber (16) by the focusing lens (15); The detection device (14) is used to convert the laser light fed back by the spectroscope (13) into an electrical signal; The reflected light beam emitted upward by the output optical fiber (16) through the focusing lens (15) includes at least one of laser light fed back from the end face of the output optical fiber (16) and laser light fed back from the output optical fiber (16); after being focused by the focusing lens (15), the reflected light beam is separated by a beam splitter (13) and enters a detection device (14); The electrical signal is used to reflect the coupling quality of the end face of the output optical fiber (16), the coupling quality of the laser jet and / or the state of the processing surface (31) of the processed workpiece (3); The detection device (14) comprises an imaging lens group (141) and a photoelectric conversion element (142); The photoelectric conversion element (142) is at least one of an array CCD, a CMOS array, a single photodiode or a silicon photocell.

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