High-pressure water-guided laser system

Abstract

The present invention discloses a high-pressure water-guided laser system, and its water-light coupler includes an upper structural member, an intermediate structural member and a lower structural member which are fixedly connected together in sequence from top to bottom; a high-pressure water cavity is formed between the upper structural member and the intermediate structural member; a high-pressure gas cavity is formed between the intermediate structural member and the lower structural member; an output optical fiber is vertically fixedly assembled at the center of the top plate of the upper structural member, and the lower ends 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 intermediate structural member; a through 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 through hole are coaxial; the minimum inner diameter of the nozzle is smaller than the minimum inner diameter of the through hole and larger than the outer diameter of the core. The high-pressure water-guided laser system of the present invention has the advantages that the cladding and the core are not easily deformed or damaged, the reliability is high, the structure is simple, the assembly is convenient, the cost is low, and the 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 uses 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 many fields such as automotive manufacturing, aerospace, and the electronics industry.

[0003] Water-guided laser technology couples a laser beam into a high-pressure micro water beam (jet), and uses the total reflection phenomenon at the water-air interface to enable the laser to be transmitted in the water beam and accurately guided to the surface of the material to be processed. High-precision and high-quality processing can be achieved without fine focusing. The water beam not only serves as a conductor for the laser, but also has cooling and cleaning functions, which can effectively reduce the heat-affected zone and material damage during the processing.

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

[0005] A direct-coupling type water-guided laser coupling system disclosed in Chinese Patent Document CN112775540A requires an optical fiber to be coupled with a jet after passing through an optical lens, and the structure is relatively complex;

[0006] A medical water-guided laser system disclosed in Chinese Patent Document CN118141510A uses a direct water-light coupling structure, which has low precision and low jet water pressure (less than 0.5 MPa), is only applicable to the medical field, and is difficult to apply to industrial applications that require high-pressure jets. Summary of the Invention

[0007] 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, the reliability is high, the structure is simple, it is convenient for assembly, the cost is low, and water explosion can be effectively reduced.

[0008] 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;

[0009] 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;

[0010] 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;

[0011] A high-pressure air cavity is formed between the middle structural member and the lower structural member, and 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;

[0012] The output optical fiber is vertically and fixedly assembled at the center of the top plate of the upper structural member, and the lower end faces of the cladding and the core body of the output optical fiber are flush with the lower side of the top plate of the upper structural member;

[0013] A nozzle penetrating up and down is formed at the center of the middle structural member;

[0014] An outlet hole penetrating up and down is formed at the center of the bottom plate of the lower structural member;

[0015] The core, the nozzle and the outlet hole are coaxial;

[0016] 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.

[0017] Preferably, the output optical fiber is directly vertically and fixedly assembled at the center of the top plate of the upper structural member;

[0018] A circular plate-shaped transparent protection lens is provided at the lower ends of the cladding and the core of the output optical fiber;

[0019] The outer diameter of the transparent protection lens is greater than the outer diameter of the cladding of the output optical fiber;

[0020] The lower side of the transparent protection lens is flush with the lower side of the top plate of the upper structural member.

[0021] Preferably, a screw hole is formed at the center of the top plate of the upper structural member;

[0022] The output optical fiber is fixed at the center of a metal tube with an external thread;

[0023] The lower ends of the cladding and the core body of the output optical fiber are flush with the lower end face of the metal tube;

[0024] The metal tube is threadedly fitted and fixed to the top plate of the upper structural member through the screw hole.

[0025] Preferably, a crown portion extending radially outward is formed at the upper end of the metal tube;

[0026] A washer is provided between the crown portion and the top plate of the upper structural member;

[0027] The washer is used for sealing to ensure that the water in the high-pressure water cavity will not leak out;

[0028] A circular plate-shaped transparent protection lens is provided at the lower ends of the cladding and the core of the output optical fiber;

[0029] The outer diameter of the transparent protection lens is greater than the outer diameter of the cladding of the output optical fiber;

[0030] 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;

[0031] The upper side surface of the transparent protective lens is attached to the lower end surface of the metal tube.

[0032] Preferably, the material of the transparent protective lens is sapphire, ruby or diamond;

[0033] A water inlet is formed on the side wall of the upper structural member for injecting high-pressure water into the high-pressure water chamber;

[0034] An air inlet is formed on the side wall of the lower structural member for injecting high-pressure air into the high-pressure air chamber;

[0035] The output optical fiber is composed of a coating, a cladding and a core;

[0036] The coating and the cladding are wrapped outside the core, and the cladding is located between the coating and the core.

[0037] Preferably, the minimum inner diameter of the nozzle is greater than the outer diameter of the core body of the output optical fiber.

[0038] Preferably, the nozzle is divided into a cylindrical upper part and a frustum-shaped lower part with a larger upper part and a smaller lower part;

[0039] The minimum inner diameter of the nozzle is the inner diameter of the cylindrical upper part.

[0040] Preferably, the high-pressure water in the high-pressure water chamber flows to the nozzle and then shoots downward to form a high-pressure micro water beam;

[0041] The high-pressure micro water beam is composed of a constriction section and a stable section in the water-light coupler;

[0042] The constriction section is located at the top of the high-pressure micro water beam, and its diameter gradually decreases from top to bottom;

[0043] The stable section is cylindrical;

[0044] The diameter of the stable section is 0.2 to 0.95 times the minimum inner diameter of the nozzle;

[0045] The marginal light 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 lasers are transmitted to the stable section and are totally emitted in the stable section;

[0046] ;

[0047] Among them, is the critical angle of total reflection of 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 fiber core and the water-vapor interface at the first reflection point in the flow constriction section, is the angle between the marginal ray and the water-vapor interface at the (N - 1)-th reflection point in the flow constriction section, is the angle between the marginal ray and the water-vapor interface at the last reflection point in the flow constriction section.

[0048] Preferably, a downward protruding portion is formed at the lower end of the fiber core body of the output optical fiber;

[0049] The protruding portion is in the shape of a spherical crown or a cone with a larger upper part and a smaller lower part;

[0050] The height h of the protruding portion is less than the outer diameter of the fiber core body of the output optical fiber.

[0051] 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;

[0052] The input optical fiber, the collimating lens, the focusing lens, and the output optical fiber are coaxially arranged in sequence from top to bottom;

[0053] The beam splitter is arranged between the collimating lens and the focusing lens, and the beam splitter is arranged at an angle of 45° with respect to the axis;

[0054] 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;

[0055] The divergent beam emitted from the lower end of the input optical fiber forms a collimated beam through the collimating lens, passes downward through the beam splitter, and is coupled into the output optical fiber by the focusing lens;

[0056] The detection device is used to convert the laser beam fed back by the beam splitter into an electrical signal;

[0057] 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, the reflected beam is separated by the beam splitter and enters the detection device;

[0058] 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 to be processed;

[0059] The detection device includes an imaging lens group and a photoelectric conversion element;

[0060] The photoelectric conversion element is at least one of an array CCD, a CMOS array, a single photodiode, or a silicon photocell.

[0061] 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 beam (jet) at the nozzle to achieve coupling. The high-pressure micro-water beam (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 beam (jet). The high-pressure micro-water beam (jet) after coupling the laser falls on the processing 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 beam (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 surface of the core 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 prone 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 laser energy coupled by the jet. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] 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 also be obtained based on these drawings.

[0063] Figure 1 FIG. is a schematic structural diagram of an embodiment of the high-pressure water-guided laser system of the present invention;

[0064] 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;

[0065] Figure 3 FIG. is a schematic diagram of a spherical crown-shaped protrusion formed at the lower end of the core body of an embodiment of the high-pressure water-guided laser system of the present invention;

[0066] Figure 4Schematic diagram of a conical protrusion formed at the lower end of the core body of an embodiment of the high-pressure water-guided laser system of the present invention;

[0067] Figure 5 Schematic diagram of directly vertically fixing and assembling the output optical fiber of an embodiment of the high-pressure water-guided laser system of the present invention at the center of the top plate of the upper structural member;

[0068] Figure 6 Schematic diagram of fixing and assembling the output optical fiber of an embodiment of the high-pressure water-guided laser system of the present invention at the center of the top plate of the upper structural member through a metal tube with external threads;

[0069] Figure 7 Schematic diagram of fixing and assembling the output optical fiber of an embodiment of the high-pressure water-guided laser system of the present invention at the center of the top plate of the upper structural member through a metal tube with external threads and provided with a transparent protective lens;

[0070] Figure 8 Schematic diagram of flow reduction coupling of an embodiment of the high-pressure water-guided laser system of the present invention.

[0071] Explanation of reference numerals:

[0072] 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 cavity; 23 Intermediate structural member; 24 High-pressure gas cavity; 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 specific embodiment

[0073] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts shall fall within the protection scope of the present invention.

[0074] Embodiment 1: A high-pressure water-guided laser system, as Figure 1 shown, which includes an output optical fiber 16 and a water-light coupler 2;

[0075] The water-light 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;

[0076] A high-pressure water cavity 22 is formed between the upper structural member 21 and the middle structural member 23, and the water pressure in the high-pressure water cavity 22 is 1 MPa to 200 MPa;

[0077] A high-pressure gas cavity 24 is formed between the middle structural member 23 and the lower structural member 25. The air pressure in the high-pressure gas cavity 24 is less than the water pressure in the high-pressure water cavity 22 and greater than 0.2 MPa;

[0078] The output optical fiber 16 is vertically and fixedly assembled at the center of the top plate of the upper structural member 21. The lower end surfaces of the cladding 162 and the core 161 main body of the output optical fiber 16 are flush with the lower side surface of the top plate of the upper structural member 21, as Figure 2 、 Figure 3 、 Figure 4 shown;

[0079] A nozzle 28 penetrating up and down is formed at the center of the middle structural member 23;

[0080] An outlet hole 251 penetrating up and down is formed at the center of the bottom plate of the lower structural member 25;

[0081] The core 161, the nozzle 28 and the outlet hole 251 are coaxial;

[0082] 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.

[0083] 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 cavity 22, which can achieve better coupling effect.

[0084] The upper structural member 21, the middle structural member 23 and the lower structural member 25 can be integrally formed.

[0085] The upper structural member 21, the middle structural member 23 and the lower structural member 25 can also each include multiple components.

[0086] In the high-pressure water-guided laser system of the first embodiment, 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 cavity 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.

[0087] 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.

[0088] Embodiment 2: Based on the high-pressure water-guided laser system of the first embodiment, as Figure 5 shown, the output optical fiber 16 is directly fixedly assembled vertically at the center of the top plate of the upper structural member 21;

[0089] 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;

[0090] 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;

[0091] 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.

[0092] In the high-pressure water-guided laser system of Embodiment 2, the transparent protective lens 211 is arranged at the lower ends of the cladding 162 and the core 161 of the output optical fiber 16, ensuring that the laser beam reliably enters the high-pressure water chamber 22 from the output optical fiber 16 through the transparent protective lens 211, and can extend the service life of the output optical fiber 16.

[0093] 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;

[0094] The output optical fiber 16 is fixed in the center of a metal tube 29 with an external thread;

[0095] The lower ends of the main bodies of the cladding 162 and the core 161 of the output optical fiber 16 are flush with the lower end face of the metal tube 29;

[0096] The metal tube 29 is threadedly fitted and fixed to the top plate of the upper structural member 21 through the screw hole.

[0097] Preferably, a crown portion extending radially outward is formed at the upper end of the metal tube 29;

[0098] A washer 210 is arranged between the crown portion and the top plate of the upper structural member 21;

[0099] The washer 210 is used for sealing to ensure that the water in the high-pressure water chamber 22 does not leak.

[0100] Preferably, as Figure 7 shown, a disc-shaped transparent protective lens 211 is arranged at the lower ends of the cladding 162 and the core 161 of the output optical fiber 16;

[0101] 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;

[0102] 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;

[0103] The upper side surface of the transparent protective lens 211 is attached to the lower end face of the metal tube 29.

[0104] In the high-pressure water-guided laser system of Embodiment 3, the output optical fiber 16 is fixed in an independent metal tube 29 with 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, making the assembly more flexible.

[0105] 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.

[0106] 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;

[0107] The minimum inner diameter of the nozzle 28 is the inner diameter of the cylindrical upper part.

[0108] Preferably, the material of the transparent protective lens 211 is sapphire, ruby or diamond.

[0109] 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.

[0110] Preferably, an air inlet is formed on the side wall of the lower structural member 25 for injecting high-pressure air into the high-pressure air chamber 24.

[0111] Preferably, the output optical fiber 16 is composed of a coating 163, a cladding 162 and a core 161;

[0112] 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.

[0113] The coating 163 mainly plays a protective role and does not directly affect the laser transmission performance. It can be removed at joints or other places according to needs, or can be made of a metal material.

[0114] Example 5: Based on the high-pressure water-guided laser system of Example 1, the high-pressure water 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;

[0115] 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;

[0116] 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;

[0117] The stable section 262 is cylindrical;

[0118] 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;

[0119] The marginal light 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.

[0120] When the high-pressure water flow in the high-pressure water chamber 22 enters the nozzle 28, a flow constriction phenomenon occurs. It leaves the inner wall of the nozzle, forming 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 flow constriction section 261 and a stable section 262. The edge light of the laser beam falling on the water-vapor interface of the flow constriction section 261 for the first time and undergoing total internal reflection should satisfy:

[0121] ;

[0122] Among them, is the critical angle of total internal reflection of the water-vapor 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 fiber core 161 into the water; is the angle between the edge light of the laser beam emitted from the fiber core 161 and the water-vapor interface at the first reflection point in the flow constriction section 261.

[0123] Subsequent edge lights also need to satisfy the total internal 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 edge light and the water-vapor interface needs to satisfy the condition:

[0124] ;

[0125] Among them, is the angle between the edge light 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 internal reflection in the stable section 262 is determined by the angle of the edge light 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 internal reflection condition. If the Nth reflection point of the edge light 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:

[0126] ;

[0127] Usually, 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 to:

[0128] ;

[0129] 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 structures such as the high-pressure water chamber and the nozzle can be optimized. At this time, the jet diameter of the stable section 262 can be close to or even smaller than the diameter of the fiber core 161 of the output optical fiber 16.

[0130] When the conditions of formula (3) or formula (4) are to be met, 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 rays of the laser beam. The optical path of the marginal rays of the laser beam to the first landing point is shorter, and the divergence diameter is smaller. And through the beam narrowing of the flow constriction section 261, a water jet with a smaller diameter can finally be formed.

[0131] Embodiment Six: Based on the high-pressure water-guided laser system of Embodiment One to Five, a downward convex portion is formed at the lower end of the main body of the core 161 of the output optical fiber 16;

[0132] The convex portion is in the shape of a spherical crown with a larger upper part and a smaller lower part (as Figure 3 shown) or a conical shape (as Figure 4 shown);

[0133] The height h of the convex portion is smaller than the outer diameter of the main body of the core 161 of the output optical fiber 16.

[0134] For the high-pressure water-guided laser system of Embodiment Six, a slightly downward convex portion is formed at the lower end of the main body of the output optical fiber 16. By changing the angle of the convex portion, the direction of the laser beam emitted from the core 161 can be changed, and the exit angle can be effectively reduced , and a more concentrated laser beam can be obtained, and even a collimated beam or a focused beam.

[0135] 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;

[0136] 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;

[0137] The beam splitter 13 is arranged between the collimating lens 12 and the focusing lens 15, and the beam splitter 13 is arranged at an angle of 45° with the axis;

[0138] The beam splitter 13 is used 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;

[0139] The divergent beam emitted from the lower end of the input optical fiber 11 forms a collimated beam 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;

[0140] The detection device 14 is used to convert the laser beam fed back by the beam splitter 13 into an electrical signal.

[0141] Preferably, the reflected light beam emitted upward by the output optical fiber 16 through the focusing lens 15 includes at least one of the laser light reflected back from the end face of the output optical fiber 16 and the laser light reflected back by the output optical fiber 16. After the reflected light beam is focused by the focusing lens 15, it passes through the beam splitter 13 to separate the reflected light beam and enters the detection device 14;

[0142] 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.

[0143] Preferably, the detection device 14 includes an imaging lens group 141 and a photoelectric conversion element 142;

[0144] The photoelectric conversion element 142 can be a linear or two-dimensional array device, such as a CCD, CMOS array, etc., or a single photoelectric device, such as a single photodiode, a silicon photocell, etc.

[0145] In the high-pressure water-guided laser system of Embodiment 7, the laser emitted by the laser passes through the input optical fiber 11. 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 light 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 processing surface 31 of the workpiece 3, according to the condition of the processing surface 31, part of the laser will also be reflected. The energy magnitude and distribution of these reflected laser lights are affected by the coupling quality of the output optical fiber 16 and the water jet and the state of the processing surface 31. These reflected laser lights return along the original optical path, are reflected by the beam splitter 13 into the detection device 14, are imaged on the photoelectric conversion element 142 through the imaging lens group 141, and are converted into electrical signals. The output signal of the detection device 14 reflects the state of the reflected light beam. By processing these output signals, it is possible to numerically evaluate 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, realize the real-time detection of the coupling quality of the end face, the coupling quality of the laser jet, and / or the state of the processing surface 31 of the workpiece 3, 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 processing parameters, providing a reliable basis for the real-time diagnosis of equipment failures and the real-time judgment of processing progress.

Claims

1. A high-pressure water-guided laser system, characterized in that, It includes an output optical fiber (16) and a water-light coupler (2); The water-light coupler (2) includes an upper structural member (21), a middle structural member (23) and a lower structural member (25) which 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 middle 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 middle structural member (23) and the lower structural member (25), and 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), and the lower end faces of the cladding (162) and the core (161) body of the output optical fiber (16) are flush with the lower side of the top plate of the upper structural member (21); A divergent laser beam is emitted from the lower end of the core (161); A nozzle (28) penetrating up and down is formed at the center of the middle structural member (23); An outlet hole (251) penetrating 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).

2. The high-pressure water-guided laser system according to claim 1, wherein The output optical fiber (16) is directly vertically fixedly assembled at the center of the top plate of the upper structural member (21).

3. The high-pressure water-guided laser system according to claim 1, wherein A screw hole is formed at the center of the top plate of the upper structural member (21); The output optical fiber (16) is fixed at the center of a metal tube (29) having an external thread; The lower end faces of the cladding (162) and the core (161) body of the output optical fiber (16) are flush with the lower end face 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).

4. The high-pressure water-guided laser system according to claim 3, wherein 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 portion and the top plate of the upper structural member (21); The gasket (210) is used for sealing to ensure that the water in the high-pressure water chamber (22) will not leak out.

5. The high-pressure water-guided laser system according to claim 2 or 4, wherein 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); 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); 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).

6. The high-pressure water-guided laser system according to claim 1, wherein The minimum inner diameter of the nozzle (28) is greater than the outer diameter of the core (161) body 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 part and a frustum-shaped lower 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.

8. The high-pressure water-guided laser system according to claim 1, characterized in that The high-pressure water in the high-pressure water cavity (22) flows to the nozzle (28) and then shoots downward to form a high-pressure micro water beam (26); The high-pressure micro water beam (26) is composed of a constriction section (261) and a stable section (262) in the water-optical coupler; The constriction section (261) is located at the top of the high-pressure micro water beam (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 marginal light 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 lasers are transmitted to the stable section (262) and are totally emitted in the stable section (262); ； wherein, is the critical angle of total reflection at the water-vapor interface, 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-vapor interface at the first reflection point in the flow constriction section (261), is the angle between the marginal ray and the water-vapor interface at the (N - 1)-th reflection point in the flow constriction section (261), is the angle between the marginal ray and the water-vapor interface at the last reflection point in the flow constriction section (261).

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 core (161) body of the output optical fiber (16); The protrusion is a spherical crown shape or a conical shape with a larger upper part and a smaller lower part; The height h of the protrusion is less than the outer diameter of the core (161) body 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-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 arranged between the collimating lens (12) and the focusing lens (15), and the beam splitter (13) is arranged at an angle of 45° to the axis; The beam splitter (13) is used to guide 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 used to convert the laser beam fed back by the beam splitter (13) into an electrical signal; The reflected beam emitted upward by the output optical fiber (16) through the focusing lens (15) includes at least one of the laser beam reflected back from the end face of the output optical fiber (16) and the laser beam reflected back by the output optical fiber (16). After the reflected beam is focused by the focusing lens (15), it passes through the beam splitter (13) to separate the reflected beam 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 machining surface (31) of the workpiece (3); The detection device (14) includes 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.

Images