Laser output head with controllable output spot

Abstract

The present application relates to the technical field of laser equipment, and particularly relates to a laser output head with controllable output light spot. The laser output head comprises a crystal end cap, a main body and a transmission optical fiber, wherein the main body is provided with an optical fiber accommodating cavity in the axial direction; the transmission optical fiber is accommodated in the optical fiber accommodating cavity; the crystal end cap is embedded in the front end of the main body and connected with the transmission optical fiber; the convex lens end cap of the crystal end cap; the distance between the virtual focal point of the convex lens end cap and the end face of the convex lens end cap is greater than the length of the convex lens end cap. The present application realizes the purpose of controllable numerical aperture adjustment and light spot size adjustment of the output light spot by controlling the convex lens curvature; by controlling the length of the convex lens end cap and the convex lens curvature and the design of the laser output head, the virtual focal point position of the laser output head is ensured unchanged, and the laser output head can be normally used in the existing laser application equipment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser equipment, in particular to a laser output head with controllable output light spot. BACKGROUND

[0002] With the continuous maturity of high-power fiber laser technology, the mainstream high-power fiber laser is generally realized through a larger core fiber scheme, a main oscillation power amplification scheme or a high-power beam combination scheme. Consequently, the output performance of the laser is sacrificed, resulting in a larger output light spot or a larger output laser NA. However, in actual applications, the output performance of the laser is closely related to the configuration requirements of the laser processing head or the whole machine device. Sacrificing the output performance of the laser (light spot size or output laser divergence angle NA) will cause abnormality of other system components, such as heating of the cutting head nozzle, heating of the collimating lens, poor cutting effect and the like. Figure 1 As shown in FIG. 1, when the beam divergence angle NA output by the transmission fiber 110 is large, the beam energy will irradiate the edge of the collimating lens M and the focusing lens N, and even irradiate the inner wall of the cutting head, thereby causing heating of the lenses, heating of the inner wall of the cutting head, poor focusing of the focal point light spot and the like. Meanwhile, on the cutting head, there is generally a small aperture diaphragm with a millimeter-level diameter near the focal point Q. When the beam divergence angle NA is large, the edge of the beam will irradiate the diaphragm, thereby causing heating and even damage of the diaphragm, affecting the cutting quality. Using the imaging principle of the convex lens can to some extent make up for the problems of large light spot or NA divergence, but will cause problems such as failure to normally adjust the focal point or deviation of the virtual focal point after the quartz end cap assembly laser output head, thereby bringing new troubles to actual laser processing applications. SUMMARY

[0003] The embodiment of the present application provides a laser output head with controllable output light spot, which can effectively solve the problems of large output light spot and large divergence angle of high-power fiber laser, which are easy to cause heating of the cutting head or the collimating lens, poor cutting and the like.

[0004] In order to achieve the above-mentioned purpose, the present application adopts the following technical scheme:

[0005] A laser output head with controllable output light spot, comprising a crystal end cap, a main body and a transmission fiber, wherein the main body is provided with a fiber accommodating cavity in the axial direction; the transmission fiber is accommodated in the fiber accommodating cavity; the crystal end cap is embedded in the front end of the main body and is fused to the transmission fiber.

[0006] The crystal end cap is a convex lens end cap, and the distance between the virtual focal point of the emitted light beam of the convex lens end cap and the end face of the convex lens end cap is greater than the length of the convex lens end cap.

[0007] In a possible implementation manner, the convex lens end cap narrows and outputs the input light beam.

[0008] In a possible implementation, the divergence angle of the emitted light beam is reduced by reducing the radius of curvature of the convex lens end cap.

[0009] In a possible implementation, the convex lens end cap comprises a fiber fusion surface, a first tapered surface, a second tapered surface, a quartz cylindrical surface, and a convex lens output surface. The quartz cylindrical surface is a cylindrical structure, the front end of which is provided with the convex lens output surface, and the rear end of which is sequentially provided with the second tapered surface, the first tapered surface, and the fiber fusion surface in the axial direction. The fiber fusion surface is fused with the transmission optical fiber.

[0010] In a possible implementation, the convex lens output surface is coated.

[0011] In a possible implementation, the output spot controllable laser output head, the rear end of the main body is connected with the support part, the support part is connected with the armored cable, and the other end of the transmission optical fiber enters the armored cable through the support part;

[0012] The rear end of the main body is connected with two water nozzles, the two water nozzles are respectively connected with two water pipes, and the two water pipes enter the armored cable through the support part.

[0013] In a possible implementation, the main body comprises an inner water pipe and a water nozzle fixing part. The center of the inner water pipe is the optical fiber containing cavity, and a mechanical small hole which is radially contracted is arranged in the optical fiber containing cavity. The front end of the main body is provided with a groove which is in communication with the optical fiber containing cavity, and the crystal end cap is embedded in the groove.

[0014] A sandwich cavity is arranged in the side wall of the inner water pipe for injecting cooling medium. The water nozzle fixing part is arranged on the outside of the inner water pipe for mounting the two water nozzles. The water nozzles are in communication with the sandwich cavity of the inner water pipe.

[0015] In a possible implementation, the support part comprises an internal support part, an armored cable fixing part, and a plurality of support columns. One end of the internal support part is connected with the rear end of the main body, and the other end is connected with the armored cable fixing part.

[0016] The plurality of support columns are distributed on the outside of the internal support part in the circumferential direction. Two ends of each of the support columns are respectively connected with the main body and the armored cable fixing part.

[0017] The armored cable is connected with the armored cable fixing part.

[0018] In a possible implementation, the outside of the support part is provided with a sleeve. Two ends of the sleeve are respectively connected with the main body and the armored cable.

[0019] In a possible implementation, the outer side of the main body is alternatively sleeved with an insulating ring and an electrode ring, and the insulating ring and the electrode ring are fixed by a clamping piece threadedly connected with the main body.

[0020] The present application has the advantages and beneficial effects that:

[0021] The laser output head with controllable output light spots provided by the embodiment of the present application can realize the controllable numerical aperture adjustment and light spot size adjustment of the output light spots according to the convex lens imaging principle by controlling the convex lens curvature; the convex lens end cap, the laser output head and the internal design of the cutting head are combined, the convex lens end cap length and the convex lens curvature are controlled, and the design of the laser output head can ensure that the virtual focal point position of the laser output head is unchanged, so that the laser output head can be normally used in the existing laser application equipment.

[0022] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art, and will be learned from practice of the present application. The objects and other advantages of the present application will be realized and achieved by the structures particularly pointed out in the written description and the appended drawings.

[0023] The technical solutions of the present application will be further described in detail below with the help of the drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0024] The accompanying drawings are included to provide a further understanding of the present application, and constitute a part of the specification, illustrate the present application, and are used to explain the present application, and do not constitute a limitation on the present application. In the drawings:

[0025] Figure 1 The schematic diagram of the light beam when the existing laser head is assembled with the cutting head;

[0026] Figure 2 The schematic structural diagram of the laser output head with controllable output light spots in the embodiment of the present application;

[0027] Figure 3 The schematic structural diagram of the crystal end cap in the embodiment of the present application;

[0028] Figure 4 The schematic structural diagram of the support part in the embodiment of the present application;

[0029] Figure 5 The schematic structural diagram of the main body in the present application;

[0030] Figure 6 The schematic diagram of the light beam when the laser output head of the present application is assembled with the cutting head.

[0031] In the figure: 101 is a crystal end cap, 1011 is a fiber fusion surface, 1012 is a first taper surface, 1013 is a second taper surface, 1014 is a quartz cylindrical surface, 1015 is a convex lens output surface, 102 is a main body, 1021 is an inner water pipe, 1022 is a water nozzle fixing part I, 1023 is a water nozzle fixing part II, 1024 is a mechanical small hole, 1025 is a welding point I, 1026 is a welding point II, 1027 is a groove, 103 is a clamping part, 1041 is an electrode ring I, 1042 is an electrode ring II, 1051 is an insulating ring I, 1052 is an insulating ring II, 1053 is an insulating ring III, 106 is a water nozzle, 107 is a water pipe, 108 is an internal support part, 109 is a sleeve, 110 is a transmission optical fiber, 111 is an armored cable fixing part, 112 is an armored cable, 113 is a support column, M is a collimating lens, N is a focusing lens, and Q is a focal point. DETAILED DESCRIPTION

[0032] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0033] In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features referred to. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified and limited.

[0034] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0035] The preferred embodiments of the present application are described below in conjunction with the accompanying drawings, and it should be understood that the preferred embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0036] One embodiment of the present invention provides a laser output head with controllable output spot size. By controlling the curvature of the convex lens at the crystal end cap, the numerical aperture of the output spot can be adjusted, and the spot size can be adjusted accordingly. See also... Figures 2 to 4 As shown, this laser output head with controllable output spot includes a crystal end cap 101, a main body 102, and a transmission optical fiber 110. The main body 102 has an axially arranged fiber optic cavity; the transmission optical fiber 110 is housed within the fiber optic cavity; the crystal end cap 101 is embedded at the front end of the main body 102 and fused to the transmission optical fiber 110; the crystal end cap 101 is a convex lens end cap, and the distance L' between the virtual focal point of the emitted beam and the end face of the convex lens end cap is greater than the length L of the convex lens end cap. Specifically, the focal point of the backward extension of the emitted beam is the virtual focal point of the emitted beam.

[0037] In embodiments of the present invention, the convex lens end cap narrows the input beam before outputting it, that is, the divergence angle NA of the emitted beam is smaller than the divergence angle NA of the incident beam, and the divergence angle NA of the emitted beam is reduced by decreasing the radius of curvature of the convex lens end cap; that is, the divergence angle NA of the emitted beam from the convex lens end cap decreases as the radius of curvature R of the convex lens end cap decreases, and the distance L' from the virtual focal point of the emitted beam to the end face of the convex lens end cap increases as the radius of curvature R of the convex lens end cap decreases.

[0038] In an embodiment of the present invention, the end cap of the convex lens is made of quartz crystal. See also Figure 3 As shown, the convex lens end cap includes an optical fiber splicing surface 1011, a first conical surface 1012, a second conical surface 1013, a quartz cylindrical surface 1014, and a convex lens output surface 1015. The quartz cylindrical surface 1014 has a cylindrical structure, with the convex lens output surface 1015 at its front end and the second conical surface 1013, the first conical surface 1012, and the optical fiber splicing surface 1011 sequentially arranged along the axial direction at its rear end. The optical fiber splicing surface 1011 is spliced ​​to the transmission optical fiber 110. The input optical fiber splicing end cap can reduce the power density of the output end face and solve the problem of burn-in at the output optical fiber end face.

[0039] Furthermore, the cone angle of the first cone 1012 is smaller than that of the second cone 1013. Specifically, the cone angle of the second cone 1013 is 90 degrees. When the reflected light is incident on the second cone 1013 at a small angle that is approximately parallel to the light, most of the light will undergo total internal reflection on its 45-degree cone surface. After two reflections, it is approximately reflected back along the original light path, which can effectively intercept the reflected light and greatly improve the product's ability to resist high reflected light.

[0040] Further, the convex lens output face 1015 is coated to reduce the end face reflection of the crystal end cap 101. In the embodiment, the transmission optical fiber 110 can be a single mode optical fiber or a multi-mode optical fiber; can be a single optical fiber, a plurality of optical fibers or a fused taper fiber bundle; can be a solid optical fiber or a hollow optical fiber; and can be a passive optical fiber or an active optical fiber. The transmission optical fiber 110 is fused to the crystal end cap 101 by using a hydrogen-oxygen flame, a graphite wire, an electrode or a laser discharge to achieve heating and fusing. The transmission optical fiber 110 is fused to the crystal end cap 101 by using a homogenized light spot to achieve uniform energy distribution, and the convex lens end cap is used to reduce the light spot and the numerical aperture, thereby effectively solving the cutting problem.

[0041] Referring to FIG. 1, in the embodiment of the present application, the rear end of the main body 102 is connected to a support part, the support part is connected to the armored cable 112, the other end of the transmission optical fiber 110 passes through the support part and enters the armored cable 112, and the rear end of the main body 102 is connected to two water nozzles 106. Figure 2 、 Figure 4 Referring to FIG. 1, in the embodiment of the present application, the rear end of the main body 102 is connected to a support part, the support part is connected to the armored cable 112, the other end of the transmission optical fiber 110 passes through the support part and enters the armored cable 112, and the rear end of the main body 102 is connected to two water nozzles 106.

[0042] Referring to FIG. 1, in the embodiment of the present application, the rear end of the main body 102 is connected to a support part, the support part is connected to the armored cable 112, the other end of the transmission optical fiber 110 passes through the support part and enters the armored cable 112, and the rear end of the main body 102 is connected to two water nozzles 106. Figure 5 、 Figure 4 Referring to FIG. 1, in the embodiment of the present application, the rear end of the main body 102 is connected to a support part, the support part is connected to the armored cable 112, the other end of the transmission optical fiber 110 passes through the support part and enters the armored cable 112, and the rear end of the main body 102 is connected to two water nozzles 106.

[0043] In the embodiment of the present application, the support part includes an internal support part 108, an armored cable fixing part 111 and a plurality of support columns 113, one end of the internal support part 108 is connected to the rear end of the main body 102, the other end is connected to the armored cable fixing part 111, the plurality of support columns 113 are distributed on the outer side of the internal support part 108 in the circumferential direction, and the two ends of each support column 113 are respectively connected to the main body 102 and the armored cable fixing part 111, and the armored cable 112 is connected to the armored cable fixing part 111.

[0044] Further, the outer side of the support part is provided with a sleeve 109, the two ends of the sleeve 109 are respectively connected to the main body 102 and the armored cable 112, and the sleeve 109 is used to protect the support part and the water pipe 107 in the sleeve 109.

[0045] In the embodiment of the present application, the outer side of the main body 102 is alternately sleeved with an insulating ring and an electrode ring, and the insulating ring and the electrode ring are fixed by a clamping part 103 which is screwed with the main body 102.

[0046] Specifically, the electrode rings include electrode ring I 1041 and electrode ring II 1042, the insulating rings include insulating ring I 1051, insulating ring II 1052 and insulating ring III 1053, the insulating ring I 1051 and the insulating ring III 1053 are respectively arranged outside the electrode ring I 1041 and the electrode ring II 1042, and the insulating ring II 1052 is arranged between the electrode ring I 1041 and the electrode ring II 1042. The electrode ring is respectively connected with a wire, and the wire is connected to an external circuit board. When the laser head QBH is inserted into the laser processing head, the electrode ring and the laser processing head are in contact to form a path, and the laser processing head can be normally used. When the QBH is inserted into the laser processing head, the electrode ring and the laser processing head are in contact but do not form a path, and the laser processing head will alarm. The electrode ring is a safety measure for conduction function judgment.

[0047] In the embodiment, the convex lens end cap materials with different lengths and radii of curvature can be high-purity fused quartz, calcium fluoride, sapphire, calcium fluoride, magnesium fluoride or zinc selenide; the convex lens end cap shape can be realized by laser cutting, end face grinding or quartz growth; the convex lens end cap controls the length and radius of curvature of the lens according to the requirements of the outgoing and incoming light beams and the virtual focal point.

[0048] Referring to Figure 3 The main design idea of the present application is based on the principle of convex lens imaging, R is the radius of curvature of the convex lens end cap, L is the length of the convex lens end cap, d is the output spot radius of the convex lens end face, and L' is the length of the virtual focal point distance of the emitted light beam from the convex lens end face. Specifically, the design of the convex lens end cap is as follows:

[0049]

[0050] The above table shows that by changing the radius of curvature of the convex lens end cap, the NA of the outgoing light and the virtual focal point change accordingly for a certain incident light of NA. In addition, with the same end cap length and radius of curvature, input beams of different NA are all narrowed, but the virtual focal point position remains unchanged. Example 1 shows that in the case of serial numbers 3 and 4, with the same end cap length of 15 mm and radius of curvature of 14.58 mm, the 0.22 NA input beam is narrowed to a 0.15 NA output beam after passing through the convex lens end cap, and the 0.12 NA input beam is narrowed to a 0.0818 NA output beam, and the virtual focal point position remains unchanged at 15.2 mm. Example 2 shows that in the case of serial numbers 6 and 7, with the same end cap length of 15 mm and radius of curvature of 10.556 mm, the 0.22 NA input beam is narrowed to a 0.123 NA output beam after passing through the convex lens end cap, and the 0.15 NA input beam is narrowed to a 0.084 NA output beam, and the virtual focal point position remains unchanged at 18.5 mm. The above two examples show that changing the radius of curvature of the convex lens end cap can change the compression ratio of the input and output beams, and also change the virtual focal point position, which is important for improving the beam divergence angle (compression ratio) and the assembly of the output head (virtual focal point position). Example 3 shows that in the case of serial numbers 8 and 9, with an end cap length of 18 mm, the radius of curvature is 5.6 mm, and for different NA incident beams, collimated beams can be obtained. Specifically, the convex lens end cap controls the length of the convex lens end cap and the radius of curvature of the lens according to the requirements of the outgoing, incoming light beams and the virtual focal point.

[0051] Figure 6 is a schematic diagram of the laser output head when assembled with the cutting head; as shown in Figure 6 The output head structure with convex lens end cap 101 is adopted, the large divergence angle beam output by transmission optical fiber 110 is compressed to a small divergence angle beam by the convex lens structure of crystal end cap 101, the beam energy will not irradiate the edge of collimating lens M and focusing lens N, and will not irradiate the inner wall of the cutting head, so that in high-power laser application, the problems of cutting head nozzle heating, collimating mirror heating, and poor cutting effect are not caused. By changing the length and radius of curvature of the crystal end cap 101, the divergence angle of the emitted beam can be adjusted, and the divergence angle NA (spot numerical aperture) of the emitted beam can also be adjusted according to the internal structure of the cutting head. Moreover, by narrowing the divergence angle of the beam, a higher energy density focusing spot can be obtained at the focusing point Q, which is beneficial for cutting thicker metal materials.

[0052] The output fiber fusion end cap can greatly reduce the power density of the output end face, solve the problem of output fiber end face burning, but the output light beam will cause the output spot to become large due to the numerical aperture limitation, and in high-power laser applications, it is easy to cause the cutting head nozzle to heat, the collimating mirror to heat, and the cutting effect to be poor. The present application realizes the purpose of controllable numerical aperture adjustment and spot size adjustment of the output spot according to the convex lens imaging principle and in combination with the quartz end cap, the laser output head and the internal design of the cutting head by controlling the length and curvature of the convex lens end cap; at the same time, the convex lens output surface 1015 is coated, the quartz end cap end face reflection is reduced, and the above problems can be effectively solved. In addition, by controlling the length and curvature of the convex lens end cap and the design of the laser output head, the position of the virtual focal point of the laser output head can be ensured unchanged, and the laser output head can be normally used in existing laser application equipment. The laser output head provided by the present application has the advantages of simple design, compact structure, and can effectively solve the problems of large output spot of high-power fiber laser, large divergence angle, easy to cause the cutting head or collimating mirror to heat, poor cutting and the like.

[0053] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application belong to the scope of the claims of the present application and their equivalent technologies, the present application also intends to include these modifications and variations.

Claims

1. A laser output head with controllable output spot, characterized in that, The crystal end cap (101), the main body (102) and the transmission optical fiber (110) are included, wherein the main body (102) is provided with an optical fiber accommodating cavity in the axial direction; the transmission optical fiber (110) is accommodated in the optical fiber accommodating cavity; the crystal end cap (101) is embedded in the front end of the main body (102) and is fused with the transmission optical fiber (110); The crystal end cap (101) is a convex lens end cap, the virtual focal point of the emitted light beam of the convex lens end cap is farther from the end face of the convex lens end cap than the length of the convex lens end cap; The convex lens end cap narrows the input light beam and then outputs, and the divergence angle of the emitted light beam is reduced by reducing the curvature radius of the convex lens end cap; The convex lens end cap includes a fiber fusion surface (1011), a first tapered surface (1012), a second tapered surface (1013), a quartz cylindrical surface (1014) and a convex lens output surface (1015), wherein the quartz cylindrical surface (1014) is a cylindrical structure, the front end of which is provided with the convex lens output surface (1015), the rear end of which is sequentially provided with the second tapered surface (1013), the first tapered surface (1012) and the fiber fusion surface (1011) in the axial direction, the fiber fusion surface (1011) is fused with the transmission optical fiber (110), the taper angle of the first tapered surface (1012) is smaller than the taper angle of the second tapered surface (1013), and the taper angle of the second tapered surface (1013) is 90 degrees.

2. The laser output head according to claim 1, wherein The convex lens output surface (1015) is coated.

3. The laser output head according to any one of claims 1 to 2, wherein The rear end of the main body (102) is connected with a support part, the support part is connected with an armored cable (112), and the other end of the transmission optical fiber (110) enters the armored cable (112) through the support part; The rear end of the main body (102) is connected with two water nozzles (106); the two water nozzles (106) are respectively connected with two water pipes (107), and the two water pipes (107) enter the armored cable (112) through the support part.

4. The laser output head according to claim 3, wherein The main body (102) includes an inner water pipe (1021) and a water nozzle fixing part, wherein the center of the inner water pipe (1021) is the optical fiber accommodating cavity, the optical fiber accommodating cavity is provided with a mechanical small hole (1024) which is radially contracted; the front end of the main body (102) is provided with a groove (1027) which is in communication with the optical fiber accommodating cavity, and the crystal end cap (101) is embedded in the groove (1027); A sandwich cavity is arranged in the side wall of the inner water pipe (1021) for injecting a cooling medium; the water nozzle fixing part is arranged outside the inner water pipe (1021) for mounting the two water nozzles (106), and the water nozzles (106) are in communication with the sandwich cavity of the inner water pipe (1021).

5. The laser output head according to claim 3, wherein The support part includes an internal support part (108), an armored cable fixing part (111) and a plurality of support columns (113), wherein one end of the internal support part (108) is connected with the rear end of the main body (102), and the other end is connected with the armored cable fixing part (111); A plurality of support columns (113) are distributed on the outer side of the internal support part (108) in the circumferential direction, and the two ends of each support column (113) are respectively connected with the main body (102) and the armored cable fixing part (111); The support part includes an internal support part (108), an armored cable fixing part (111) and a plurality of support columns (113), wherein one end of the internal support part (108) is connected with the rear end of the main body (102), and the other end is connected with the armored cable fixing part (111); The armored cable (112) is connected with the armored cable fixing member (111).

6. The laser output head according to claim 3, wherein The outer side of the support part is provided with a sleeve (109), and two ends of the sleeve (109) are connected with the main body (102) and the armored cable (112) respectively.

7. The laser output head according to claim 1, wherein The outer side of the main body (102) is alternately sleeved with an insulating ring and an electrode ring, and the insulating ring and the electrode ring are fixed through a clamping piece (103) which is screwed with the main body (102).

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