Qcs fiber head water-cooled beam expander and focusing mirror

Abstract

The utility model provides a kind of QCS optical fiber head water-cooling beam expanding focusing mirror, belong to laser processing equipment technical field.The QCS optical fiber head water-cooling beam expanding focusing mirror includes QCS optical fiber head, beam expanding module, focusing objective group and locking mechanism of connecting QCS optical fiber head and beam expanding module in turn along optical path.The locking mechanism includes locking sleeve body and locking nut, and radial centering clamping force is generated by the inner taper surface of locking nut and QCS optical fiber head cylindrical surface cooperation, so that QCS optical fiber head optical axis is aligned with subsequent optical path.The beam expanding module includes beam expanding negative, beam expanding positive and rotating hand wheel for driving beam expanding positive to move, to change beam divergence angle, realize focal point position adjustment;Beam expanding module further includes cooling channel of water-cooling lens barrel and water-cooling connector, for heat dissipation.Focusing objective group adopts the combined structure including multiple lenses and spacer, for beam focusing.The utility model improves optical path coaxiality, focal point adjustability and thermal stability under high-power work.

Description

Technical Field

[0001] This utility model relates to the field of laser processing equipment technology, and in particular to a QCS fiber head water-cooled beam expander and focusing lens. Background Technology

[0002] In laser precision machining processes such as micro-cutting, drilling, and surface treatment, the processing quality directly depends on the size, energy distribution, and stability of the focused laser spot. To achieve high-quality processing results, the laser beam must maintain good coaxiality throughout its entire journey from source output, through optical path transmission, to final focusing. Any deviation in the optical axis at any stage can lead to focused spot deformation, energy dispersion, or positional drift, thereby affecting processing accuracy and consistency.

[0003] To achieve the aforementioned optical path coaxiality, the beam output from the fiber laser typically needs to be expanded using a beam expander group and then focused onto the workpiece surface using a focusing lens group. In this process, the connection and alignment between the fiber output head and the subsequent beam expander and focusing components are crucial. While existing connection methods can achieve basic fixation, they still face challenges in ensuring long-term stable and high-precision coaxiality, especially under conditions of frequent assembly / disassembly or vibration, where the optical axis is prone to misalignment. Summary of the Invention

[0004] This invention overcomes the shortcomings of the prior art and provides a QCS fiber optic head water-cooled beam expander and focusing lens.

[0005] To achieve the above objectives, the technical solution adopted by this utility model is: a QCS fiber optic head water-cooled beam expander and focusing lens, comprising:

[0006] QCS fiber optic connector, used to output laser beam;

[0007] The beam expander module is positioned behind the QCS fiber head along the optical path to increase the spot diameter of the laser beam.

[0008] The focusing objective lens group is positioned behind the beam expander module along the optical path to focus the expanded laser beam onto the working surface;

[0009] In addition, a locking mechanism is provided, which connects the QCS fiber head and the beam expander module along the optical path, and is used to fix the QCS fiber head by centering and clamping, so that the QCS fiber head is aligned with the optical axis of the beam expander module and the focusing objective lens group.

[0010] Preferably, the locking mechanism includes a locking sleeve body and a locking nut;

[0011] The locking sleeve body has a guide hole inside, which is clearance-fitted with the outer diameter of the cylindrical section of the QCS fiber optic head;

[0012] The locking nut has a first internal thread on its inner side, which mates with a first external thread located at the end of the locking sleeve body; the inner section of the locking nut near the locking sleeve body is an inner conical surface, and the minimum diameter of the inner conical surface is smaller than the outer diameter of the QCS fiber optic head.

[0013] Preferably, the taper of the inner conical surface ranges from 0.5° to 3°.

[0014] Preferably, the radial gap on one side between the guide hole and the cylindrical section of the QCS fiber head is 5μm to 25μm.

[0015] Preferably, the focusing objective lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens arranged sequentially along the optical path;

[0016] The first lens is a biconcave lens, the second lens is a biconvex lens, and the first lens and the second lens are cemented together.

[0017] The third lens is a meniscus positive lens;

[0018] The fourth lens is a biconvex lens;

[0019] The fifth lens is a plano-convex lens;

[0020] The sixth lens is a biconvex lens.

[0021] Preferably, the first lens is made of ZF2 series optical glass, and the second, third, fourth, fifth and sixth lenses are all made of fused silica.

[0022] Preferably, spacers for controlling the air gap are provided between the second lens and the third lens, between the third lens and the fourth lens, between the fourth lens and the fifth lens, and between the fifth lens and the sixth lens.

[0023] Preferably, the beam expander module includes a beam expander negative lens holder, a beam expander negative lens, a beam expander positive lens holder, a beam expander positive lens, and a rotating handwheel;

[0024] The beam expander negative is located in the beam expander negative holder, and the beam expander positive is located in the beam expander positive lens holder;

[0025] The rotating handwheel is mounted on the outside of the beam expander positive lens mount and is connected via a threaded pair;

[0026] A fixing screw is provided between the beam expander negative plate fixing seat and the rotating handwheel. The fixing screw restricts the axial movement of the rotating handwheel and allows the rotating handwheel to rotate.

[0027] Preferably, the beam expander module further includes a limiting and fixing component, which is installed at the tail end of the rotating handwheel or the beam expander positive lens mount for axial limiting.

[0028] Preferably, the axial movement of the beam expander is within the range of ±5mm.

[0029] Preferably, the beam expander module further includes a water-cooled mirror barrel and at least one water-cooled connector;

[0030] The front end of the water-cooled microscope tube is connected to the rear end of the beam expander negative film holder, and the rear end is connected to the limiting and fixing component.

[0031] A cooling channel is formed between the inner wall of the water-cooled microscope tube and the outer surface of the tail of the beam expander negative holder;

[0032] The water-cooled connector is installed on the water-cooled mirror tube and is connected to the cooling channel.

[0033] This utility model solves the defects existing in the background technology, and has the following beneficial effects:

[0034] The water-cooled beam expander and focusing lens with a QCS fiber optic head provided by this utility model includes a QCS fiber optic head, a beam expander module, a focusing objective lens group, and a locking mechanism connecting the QCS fiber optic head and the beam expander module, all arranged along the optical path. The locking mechanism fixes the QCS fiber optic head by centering and clamping, aligning the optical axis of the QCS fiber optic head with the optical axis of the beam expander module and the focusing objective lens group, ensuring that the beam remains coaxial from output to focusing and that the beam spot position is stable.

[0035] The locking mechanism includes a locking sleeve body with a guide hole and a locking nut with an inner conical surface. When the locking nut is tightened, the inner conical surface of the locking nut slides on the cylindrical surface of the QCS fiber optic head, generating a uniform radial clamping force. This allows the QCS fiber optic head to be automatically positioned at the center of the guide hole in the locking sleeve body, avoiding the optical axis tilting problem caused by uneven point contact force in the lateral set screw fixing method.

[0036] The focusing objective lens group includes lenses one through six and spacers. The first lens is cemented to the second lens, and the remaining lenses are made of fused silica and arranged sequentially at intervals. As the light beam passes through the focusing objective lens group, various aberrations are reduced. Compared to lens groups with fewer lenses or simpler structures, the focusing objective lens group outputs a smaller and more circular focused spot.

[0037] The beam expander module includes a negative expander holder, a negative expander, a positive expander lens holder, a positive expander, a rotating handwheel, and fixing screws. The rotating handwheel drives the positive expander lens holder to move linearly via a thread, changing the distance between the positive and negative expanders, thereby adjusting the divergence angle of the emitted beam and achieving continuous adjustment of the focal position. This overcomes the limitation of fixed beam expanders, which require moving the entire lens body or workpiece to zoom.

[0038] The beam expander module also includes a water-cooled lens barrel and a water-cooled connector, forming a cooling channel surrounding the beam expander negative holder. The coolant flows through the channel to carry away the heat generated by the beam expander negative, reducing the lens operating temperature and suppressing focal position drift caused by lens thermal effects, thus enabling the lens assembly to maintain stable optical performance during continuous high-power operation. Attached Figure Description

[0039] The present invention will be further described below with reference to the accompanying drawings and embodiments;

[0040] Figure 1 This is a schematic diagram of a QCS fiber optic head water-cooled beam expander and focusing mirror;

[0041] Figure 2 This is a schematic diagram of the locking mechanism;

[0042] Figure 3 This is a schematic diagram of the focusing objective lens assembly;

[0043] Figure 4 This is a schematic diagram of the beam expander module;

[0044] In the diagram: 1. QCS fiber optic head; 2. Beam expander module; 3. Focusing objective lens group; 4. Locking mechanism; 21. Beam expander negative plate holder; 22. Beam expander negative plate; 23. Beam expander positive plate holder; 24. Beam expander positive plate; 25. Rotary handwheel; 26. Fixing screw; 27. Limiting fastener; 28. Water-cooled lens barrel; 29. ​​Water-cooled connector; 31. First lens; 32. Second lens; 33. Third lens; 34. Fourth lens; 35. Fifth lens; 36. Sixth lens; 37. Spacer; 41. Locking sleeve body; 42. Locking nut; 411. Guide hole; 412. First external thread; 421. First internal thread; 422. Inner conical surface. Detailed Implementation

[0045] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. These drawings are simplified schematic diagrams, which are only used to illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0046] like Figure 1 As shown, a QCS fiber optic head water-cooled beam expander and focusing lens includes:

[0047] QCS fiber optic connector 1, used to output laser beam;

[0048] The beam expander module 2 is positioned behind the QCS fiber head 1 along the optical path to expand the spot diameter of the laser beam.

[0049] The focusing objective lens group 3 is positioned behind the beam expander module 2 along the optical path to focus the expanded laser beam onto the working surface.

[0050] Additionally, the locking mechanism 4 connects the QCS fiber head 1 and the beam expander module 2 along the optical path, and fixes the QCS fiber head 1 by centering and clamping, so that the QCS fiber head 1 is aligned with the optical axis of the beam expander module 2 and the focusing objective lens group 3.

[0051] In existing technologies, the QCS fiber optic head 1 is fixed by lateral screw tightening. This lateral screw tightening creates point or line contact, causing the optical axis of the QCS fiber optic head 1 to become off-center. By introducing a locking mechanism 4 that generates a centering clamping force, during the locking process, the QCS fiber optic head 1 can be automatically forced or guided to align with the optical axis of the subsequent optical path components (beam expander module 2 and focusing objective lens group 3), thereby structurally ensuring coaxiality.

[0052] The following will describe in detail the specific implementation methods and working processes with reference to the accompanying drawings and multiple embodiments.

[0053] Example 1:

[0054] A water-cooled beam expander and focusing lens with a QCS fiber optic connector includes a QCS fiber optic connector 1, a beam expander module 2, and a focusing objective lens group 3 arranged sequentially along the optical path, forming a complete laser focusing optical path. The QCS fiber optic connector 1 is a standard cylindrical interface with an optically polished output end face, used to stably output a parallel laser beam and serving as the laser emission source for the entire optical path. The beam expander module 2 is located behind the QCS fiber optic connector 1 and is used to expand the laser beam spot diameter, reducing the beam divergence angle to minimize optical aberrations and increasing the beam cross-sectional area to meet the requirements of high-power laser loads. The focusing objective lens group 3 is located behind the beam expander module 2 and is used to converge the expanded laser beam onto the processing surface, forming a high-energy-density focused spot.

[0055] In actual assembly and application, the fixing accuracy of the QCS fiber optic head 1 directly determines the coaxiality of the entire optical path. It is necessary to ensure reliable fixing of the QCS fiber optic head 1 while ensuring that the optical axis of the QCS fiber optic head 1 is strictly aligned with the optical axes of the beam expander module 2 and the focusing objective lens group 3. If a set screw structure is used for radial locking on the side of the QCS fiber optic head 1, i.e., a threaded hole is opened on the side of the lens mount supporting the QCS fiber optic head 1, and the cylindrical side of the QCS fiber optic head 1 is radially tightened by screwing in the set screw, two problems arise: First, the set screw forms point contact or short-line contact with the side of the fiber optic head, resulting in uneven distribution of radial force, forcing the QCS fiber optic head 1 to tilt slightly, thus disrupting the parallelism of the optical axis; second, local pressure concentration at the tightening point easily causes surface damage such as scratches and indentations on the outer cylindrical surface of the QCS fiber optic head 1, and may even cause minute displacement of the internal optical components of the QCS fiber optic head 1. Both will directly cause the optical axis of the output beam of QCS fiber head 1 to become off-center, destroying the coaxiality of the entire laser focusing optical path, which in turn causes the focused spot to be deformed or the energy distribution to be uneven, affecting the processing accuracy.

[0056] To structurally address the aforementioned optical axis eccentricity problem, this embodiment provides a locking mechanism 4 capable of generating a radial centering clamping force. During the locking action, a radial constraint force is generated uniformly acting on the circumference of the QCS fiber head 1, forcing the optical axis of the QCS fiber head 1 to automatically align with and maintain the optical axis of the laser focusing optical path, thereby structurally ensuring coaxiality.

[0057] like Figure 2 As shown, in this embodiment, the locking mechanism 4 includes a locking sleeve body 41 and a locking nut 42.

[0058] The locking sleeve body 41 is a hollow stepped sleeve with a sealing thread at its front end (near the expansion module 2) for threaded connection and sealing with the expansion module 2. An axial guide hole 411 is provided inside the locking sleeve body 41. The diameter of the guide hole 411 is clearance-fitted with the outer diameter of the cylindrical section of the QCS fiber optic head 1, providing radial positioning for the inserted QCS fiber optic head 1, allowing for smooth insertion and slight self-alignment adjustment before locking. A first external thread 412 is provided on the outer circumference of the end of the locking sleeve body 41 (away from the expansion module 2, i.e., the insertion end of the QCS fiber optic head 1).

[0059] The locking nut 42 is a ring-shaped part with a first internal thread 421 on its inner side (near the end of the locking sleeve body 41) for engaging with the first external thread 412 at the end of the locking sleeve body 41. Crucially, the inner bore of the locking nut 42 is not a uniform-diameter cylindrical surface; rather, the diameter of the inner bore gradually decreases near the locking sleeve body 41 (i.e., in the tightening direction or optical path direction), forming an inner conical surface 422. The minimum diameter of the inner conical surface 422 is slightly smaller than the outer diameter of the QCS fiber optic head 1.

[0060] In this embodiment, during the assembly process, the locking mechanism 4 involves placing a locking nut 42 on the tail of the QCS fiber optic head 1, engaging the first internal thread 421 of the locking nut 42 with the initial section of the first external thread 412 of the locking sleeve body 41, and inserting the cylindrical section of the QCS fiber optic head 1 into the guide hole 411 of the locking sleeve body 41 to complete the initial radial positioning. At this time, the inner conical surface 422 of the locking nut 42 and the outer cylindrical surface of the QCS fiber optic head 1 are in initial contact.

[0061] During the tightening of the locking nut 42, driven by the engagement of the first internal thread 421 of the locking nut 42 and the first external thread 412 of the locking sleeve body 41, the locking nut 42 moves along the axis toward the locking sleeve body 41 (optical path direction). Because the inner conical surface 422 of the locking nut 42 has a taper and its minimum aperture is smaller than the outer diameter of the fiber optic head, the axial movement of the inner conical surface 422 relative to the cylindrical surface of the QCS fiber optic head 1 will result in a gradually increasing radial interference due to geometric interference. Specifically, as the locking nut 42 is screwed in, the inner conical surface 422 gradually aligns with the outer cylindrical surface of the QCS fiber optic head 1, causing a continuous and gradual increase in radial compression.

[0062] The tightening of the locking nut 42 utilizes the wedge principle. The axial displacement of the locking nut 42 is converted into a continuously and uniformly increasing radial clamping force through the geometric interference between the inner conical surface 422 and the cylindrical surface of the QCS fiber head 1. This radial clamping force acts simultaneously and uniformly on the QCS fiber head 1 from the entire circumference, forcing the QCS fiber head 1 to produce a slight elastic deformation. Through the automatic centering of the inner conical surface 422, the outer cylindrical surface of the QCS fiber head 1 is tightly fitted and aligned with the center of the guide hole 411 of the locking sleeve body 41. Since the guide hole 411 has been pre-aligned with the subsequent optical path components (beam expander module 2 and focusing objective lens group 3), the optical axis of the QCS fiber head 1 is forcibly corrected to be consistent with the optical axis of the laser focusing optical path when the locking nut 42 is tightened.

[0063] For example, the sealing between the locking sleeve body 41 and the beam expander module 2 can be achieved using a combination of threaded seals and end face seals. An annular sealing groove is formed on the front end face of the locking sleeve body 41, and a sealing ring is placed inside. After tightening, the sealing ring is pressed between the mating surfaces of the locking sleeve body 41 and the beam expander module 2, preventing external dust and impurities from entering the optical path. Alternatively, leak prevention can be achieved by applying thread sealant to the threaded surface of the locking sleeve body 41.

[0064] For example, the taper of the inner conical surface 422 ranges from 0.5° to 3°, preferably from 1° to 2°; the corresponding taper ratio (the ratio of diameter difference to axial length) is approximately 1:57 to 1:19, preferably approximately 1:28 to 1:14. The taper of the inner conical surface 422 can provide sufficient radial clamping force and self-locking while ensuring a smooth locking process and avoiding excessive assembly stress on the QCS fiber head 1.

[0065] For example, the guide hole 411 and the cylindrical section of the QCS fiber head 1 are fitted with a clearance of H7 / g6, and the radial clearance on one side is preferably 5μm to 25μm to ensure smooth assembly and provide accurate initial positioning for centering and locking.

[0066] Example 2:

[0067] Based on the QCS fiber-optic water-cooled beam expander and focusing lens provided in Example 1, this embodiment further optimizes the internal optical structure of the focusing objective lens group 3 to solve the problem of reduced focusing spot quality caused by aberrations, thereby obtaining a high-quality processing spot with more concentrated energy and a more regular shape.

[0068] In laser precision machining, extremely high requirements are placed on the size, roundness, and energy distribution uniformity of the focused spot. If the focusing objective group 3 uses a single lens or a simple combination of two lenses, its ability to correct optical aberrations is limited, especially when dealing with collimated beams with a larger diameter after beam expansion. This can easily lead to significant aberrations such as spherical aberration and coma. These aberrations result in an increased focused spot size, energy dispersion, blurred edges, or shape distortion, making it impossible to form an ideal diffraction-limited spot. Consequently, this directly affects the accuracy and effectiveness of processes such as micro-cutting and drilling.

[0069] like Figure 3 As shown, the focusing objective lens group 3 in this embodiment includes a first lens 31, a second lens 32, a third lens 33, a fourth lens 34, a fifth lens 35 and a sixth lens 36 arranged coaxially along the optical path from front to back (i.e. from the beam expander module 2 side to the working surface side).

[0070] For example, the lenses are configured as follows:

[0071] The first lens 31 is a biconcave lens, and the second lens 32 is a biconvex lens. The first lens 31 and the second lens 32 are combined using an optical cementing process to form a first cemented lens group, which can effectively correct chromatic aberration and spherical aberration of the system. Specifically, the radii of curvature R1 and R2 on both sides of the first lens 31 are -30mm and 30mm, respectively, and the center thickness is 2mm; the radii of curvature R2 and R3 on both sides of the second lens 32 are 30mm and -34mm, respectively, and the center thickness is 7.5mm.

[0072] The third lens 33 is a meniscus positive lens (meniscus biconvex lens) with radii of curvature R4 and R5 on both sides of 72mm and 41.3mm respectively, and a center thickness of 1.9mm. The third lens 33 further corrects spherical aberration and astigmatism, and helps to smooth the direction of light rays in the optical path.

[0073] The fourth lens 34 is a biconvex lens with radii of curvature R6 and R7 on both sides of 126mm and -50mm respectively, and a center thickness of 5mm. The fourth lens 34 undertakes the main converging function and works with the front and rear lenses to balance the curvature of the image field.

[0074] The fifth lens 35 is a plano-convex lens, with one side near the working surface being flat (radius of curvature R9 being infinite), and the other side having a radius of curvature R8 of 35mm, and a center thickness of 5mm. The fifth lens 35 further compresses the beam and provides good image plane flatness for final focusing.

[0075] The sixth lens 36 is a biconvex lens with radii of curvature R10 and R11 on both sides of 20mm and -232mm, respectively. The sixth lens 36 is the last lens used to finally correct residual aberrations and converge the beam to the smallest focal point.

[0076] The first lens 31 can be made of ZF2 series optical glass (e.g., refractive index nd≈1.6727, Abbe number vd≈32.178), which utilizes high dispersion characteristics in conjunction with subsequent low dispersion materials to correct chromatic aberration.

[0077] The second lens 32, the third lens 33, the fourth lens 34, the fifth lens 35, and the sixth lens 36 are all preferably made of fused silica, which exhibits high transmittance, low absorption, low coefficient of thermal expansion, and excellent thermal stability in the near-infrared laser band. Its refractive index nd is approximately 1.46, and its Abbe number vd is approximately 67.82. This high Abbe number (low dispersion) characteristic, combined with the high dispersion material of the first lens 31, constitutes an effective achromatic combination.

[0078] like Figure 1 As shown, the first lens 31, second lens 32, third lens 33, fourth lens 34, fifth lens 35, and sixth lens 36 are not in close contact, but are maintained by spacers 37 to maintain the required air gap. For example, spacers 37 are provided between the second lens 32 and the third lens 33, between the third lens 33 and the fourth lens 34, between the fourth lens 34 and the fifth lens 35, and between the fifth lens 35 and the sixth lens 36. By controlling the thickness of the spacers 37, the air gaps D3 (1.5 mm), D4 (2 mm), D6 (0.5 mm), and D8 (0.3 mm) are ensured, thereby controlling aberrations, especially higher-order aberrations.

[0079] In this embodiment, the focusing objective lens group 3 corrects various optical aberrations, including spherical aberration, coma, astigmatism, field curvature, and chromatic aberration, through a specific sequential arrangement of lenses with different surface shapes and materials, and controlled air gaps. Specifically, the first cemented lens group, formed by cementing the first lens 31 and the second lens 32, uses positive and negative lens cementation to cancel axial chromatic aberration and part of spherical aberration. The curvature, thickness, and spacing of the third lens 33, fourth lens 34, fifth lens 35, and sixth lens 36 are optimized to balance aberrations in each field of view, ensuring a near-diffraction-limited focused spot not only at the optical axis center but also within a certain field of view. The extensive use of quartz material ensures the thermal stability and long-term reliability of each lens under high-power laser conditions, avoiding focus drift caused by thermal lensing effects.

[0080] Example 3:

[0081] Based on the QCS fiber head water-cooled beam expander and focusing lens provided in Example 1, this embodiment further expands the functionality of the beam expander module 2 by introducing a focus adjustment mechanism integrated into the beam expander module 2. Without changing the laser focusing optical path, the focus position can be changed during operation, so that the same device can adapt to the different needs of focus position for materials of different thicknesses or different processes.

[0082] In laser processing, for materials of different thicknesses or types, it is often necessary to adjust the laser focus to a specific depth on the workpiece surface or inside. If the beam expander module adopts a fixed-gap optical structure, the focal length of the entire laser focusing optical path is fixed. Adjusting the focus position requires moving the entire focusing lens or workpiece stage, which is cumbersome and may introduce new mechanical errors, making it unsuitable for rapid and precise process adaptation.

[0083] To address the aforementioned problems, this embodiment provides a beam expander module 2 with focus adjustment functionality. For example... Figure 4 As shown, the beam expander module 2 in this embodiment includes a beam expander negative lens holder 21, a beam expander negative lens 22, a beam expander positive lens holder 23, a beam expander positive lens 24, and a rotating handwheel 25. The beam expander negative lens holder 21 is a cylindrical structure with one end open, and the front end (near the locking mechanism 4) is threaded for threaded connection with the front end of the locking sleeve body 41 of the locking mechanism 4, thereby realizing the optical path docking between the beam expander module 2 and the locking mechanism 4; the beam expander negative lens 22 is a negative lens (concave lens) and is installed at the front end of the inner cavity of the beam expander negative lens holder 21; the beam expander positive lens holder 23 is a cylindrical lens holder with external threads machined on the outside and is installed behind the beam expander negative lens holder 21 along the optical path; the beam expander positive lens 24 is a positive lens (convex lens) and is installed in the inner cavity of the beam expander positive lens holder 23; the rotating handwheel 25 is fitted on the outside of the beam expander positive lens holder 23, and the inner ring is machined with an internal thread that matches the external thread of the beam expander positive lens holder 23.

[0084] To ensure that the expander positive lens mount 23 moves only in a straight line without rotation, and to prevent the rotating handwheel 23 from accidentally dislodging from the threaded joint during use, the expander module 2 provided in this embodiment also includes fixing screws 26 and limiting fasteners 27; the inner wall of the rotating handwheel 25 is also provided with at least one axially extending guide groove along the circumference. The number of fixing screws 26 corresponds to the number of guide grooves in the rotating handwheel 25. The screw portion of the fixing screw 26 is radially screwed into the threaded hole on the side wall of the expander negative lens mount 21, while the head or shaft portion extends into and is locked in the guide groove of the rotating handwheel 25. The limiting fastener 27 is a stop ring, installed in a slot at the tail end of the rotating handwheel 25 (away from the expander negative lens 22), used to axially limit the rotating handwheel 25 and prevent the rotating handwheel 25 from dislodging from the expander negative lens mount 21.

[0085] The beam expander negative film holder 21 is connected to the locking mechanism 4 via a front thread, and the rear end (near the focusing objective lens group 3) is connected to the focusing objective lens group 3 via another thread, thereby connecting and fixing the beam expander module 2 in series between the locking mechanism 4 and the focusing objective lens group 3, forming a continuous optical path. The beam expander positive film holder 23 engages with the internal thread of the rotating handwheel 25 via an external thread; at the same time, the fixing screw 26 couples the beam expander negative film holder 21 and the rotating handwheel 25 together: the fixing screw 26 restricts the axial movement freedom of the rotating handwheel 25 relative to the beam expander negative film holder 21, but allows the rotating handwheel 25 to rotate freely around the optical axis.

[0086] When the handwheel 25 is manually rotated, it cannot move axially due to the constraint of the fixing screw 26. However, through the engagement of the internal thread of the handwheel 25 with the external thread of the expander lens mount 23, the rotational motion of the handwheel 25 is converted into the linear reciprocating motion of the expander lens mount 23 (together with the expander lens 24 fixed inside it) along the optical axis.

[0087] When the handwheel 25 is rotated clockwise, causing the positive beam expander mount 23 and the positive beam expander 24 to move closer to the negative beam expander 22, the distance between the positive beam expander 24 (positive lens) and the negative beam expander 22 (negative lens) decreases. According to the principles of geometric optics, the divergence angle of the emitted beam increases. After passing through the fixed focusing objective group 3, the focal point of the beam with the increased divergence angle will move away from the focusing objective group 3 (i.e., the focal point is elongated and moves deeper into the working surface).

[0088] When the rotating handwheel 25 is rotated in the opposite direction, driving the positive beam expander 24 to move away from the negative beam expander 22, the distance between the positive beam expander 24 (positive lens) and the negative beam expander 22 (negative lens) increases, the divergence angle of the emitted beam decreases, and after passing through the focusing objective lens group 3, the focal point will be closer to the focusing objective lens group 3 (i.e. the focal point is pulled closer and moves towards the working surface).

[0089] Furthermore, by limiting the effective stroke of the threaded fastener 27, the movement stroke of the beam expander 24 is limited to within ±5mm, enabling fine, continuous, and repeatable adjustment of the focal position.

[0090] Example 4:

[0091] This embodiment, based on the QCS fiber-optic water-cooled beam expander and focusing lens with focus adjustment function provided in Embodiment 3, further introduces an active heat dissipation structure into the beam expander module 2 to prevent the beam expander negative plate 22 from heating up due to absorbing laser energy during long-term operation of high-power lasers. In high-power laser processing at the kilowatt level and above, even when using quartz lenses with extremely high transmittance, the beam expander negative plate 22 and the beam expander positive plate 24 will still absorb a small amount of laser energy and convert it into heat. If the heat cannot be dissipated in time, it will cause the lens temperature to rise, further leading to thermal damage to the lens, thermal lensing effect, and focus position drift.

[0092] To address the aforementioned heat dissipation issue, this embodiment introduces a highly efficient water-cooling structure in the beam expander module 2. For example... Figure 4 As shown, the beam expander module 2 in this embodiment also includes a water-cooled lens barrel 28 and a water-cooled connector 29. The water-cooled lens barrel 28 is a hollow cylindrical structure made of a thermally conductive metal (such as aluminum alloy or stainless steel). The inner wall of the front end of the water-cooled lens barrel 28 is threaded for engaging with the external thread of the tail end of the beam expander negative film holder 21; the inner wall of the rear end is also threaded or has a groove for fixing to the limiting and fixing member 27 (which serves as both axial limiting and rear end sealing). Multiple threaded holes are machined on the outer wall of the water-cooled lens barrel 28; an annular cavity or spiral flow channel surrounding the optical path is provided between the inner wall of the water-cooled lens barrel 28 and the outer cylindrical surface of the tail end of the beam expander negative film holder 21, together forming a sealed cooling channel. The water-cooled connector 29 is a standard quick-connect or threaded cooling water connector, the number of which corresponds to the number of threaded holes on the outer wall of the water-cooled lens barrel 28. The water-cooled connector 29 is screwed into the threaded hole of the water-cooled mirror barrel 28, and the flow channel of the water-cooled connector 29 is connected to the cooling flow channel inside the water-cooled mirror barrel 28.

[0093] In this embodiment, the water-cooled microscope tube 28 serves as the outer shell, and its inner cavity houses and encloses the beam expander negative holder 21, the beam expander negative 22, the beam expander positive lens holder 23, and the beam expander positive 24. The tail of the beam expander negative holder 21 is screwed into and fixed to the front end of the water-cooled microscope tube 28, while the front end of the beam expander negative holder 21, where the beam expander negative 22 is mounted, protrudes outside the water-cooled microscope tube 28 and is used to connect the locking mechanism 4. The beam expander positive lens holder 23 (which mounts the beam expander positive 24) is entirely located within the inner cavity of the water-cooled microscope tube 28. The rotating handwheel 25 is fitted onto the outside of the water-cooled microscope barrel 28, corresponding to the axial position of the expanding positive lens mount 23. The fixing screw 26 passes radially through the corresponding elongated hole or guide groove on the wall of the water-cooled microscope barrel 28, with one end screwed into the threaded hole on the side of the expanding positive lens mount 23 to lock it in place, and the other end engaged in the guide groove on the inner wall of the rotating handwheel 25. Thus, the fixing screw 26 acts as a transmission key, coupling the rotational movement of the external rotating handwheel 25 to the internal expanding positive lens mount 23. A limiting and fixing component 27 is installed at the rear end of the water-cooled microscope barrel 28 to axially limit the movement of the internal expanding positive lens mount 23 and to assist in sealing.

[0094] When an external cooling water source is connected to the water-cooling connector 29 via a water pipe, the cooling water is pumped into the cooling channel. Since the beam expander negative 22 is in close contact with the beam expander negative 21, and the tail of the beam expander negative 21 is completely submerged in the circulating cooling water, the heat generated by the laser energy absorbed by the beam expander negative 22 is rapidly conducted to the tail through the metal material of the beam expander negative 21 and then continuously carried away by the flowing cooling water. Simultaneously, the beam expander positive mirror mount 23, located in the same inner cavity, also receives good cooling. After sufficient heat exchange within the channel, the cooling water flows out from another water-cooling connector 29, completing one cycle.

[0095] Based on the preferred embodiments of this utility model described above, those skilled in the art can make various changes and modifications without departing from the technical concept of this utility model. The technical scope of this utility model is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A QCS fiber optic head water-cooled beam expander and focusing lens, characterized in that, include: QCS fiber optic head (1) is used to output a laser beam; The beam expander module (2) is positioned behind the QCS fiber head (1) along the optical path to expand the spot diameter of the laser beam; The focusing objective lens group (3) is arranged behind the beam expander module (2) along the optical path to focus the expanded laser beam onto the working surface; In addition, a locking mechanism (4) connects the QCS fiber head (1) and the beam expander module (2) along the optical path, and is used to fix the QCS fiber head (1) in a centering clamping manner so that the QCS fiber head (1) is aligned with the optical axis of the beam expander module (2) and the focusing objective lens group (3).

2. The QCS fiber optic head water-cooled beam expander and focusing lens according to claim 1, characterized in that, The locking mechanism (4) includes a locking sleeve body (41) and a locking nut (42). The locking sleeve body (41) is provided with a guide hole (411) inside, and the guide hole (411) is in clearance fit with the outer diameter of the cylindrical section of the QCS fiber head (1). The locking nut (42) has a first internal thread (421) on its inner side, which is engaged with the first external thread (412) at the end of the locking sleeve body (41); the inner hole section of the locking nut (42) near the locking sleeve body (41) is an inner conical surface (422), and the minimum diameter of the inner conical surface (422) is smaller than the outer diameter of the QCS fiber head (1).

3. The QCS fiber optic head water-cooled beam expander and focusing lens according to claim 2, characterized in that, The taper of the inner conical surface (422) ranges from 0.5° to 3°; and / or the single-sided radial gap between the guide hole (411) and the cylindrical section of the QCS fiber head (1) is from 5 μm to 25 μm.

4. The QCS fiber optic head water-cooled beam expander and focusing lens according to claim 1, characterized in that, The focusing objective lens group (3) includes a first lens (31), a second lens (32), a third lens (33), a fourth lens (34), a fifth lens (35), and a sixth lens (36) arranged sequentially along the optical path. The first lens (31) is a biconcave lens, the second lens (32) is a biconvex lens, and the first lens (31) and the second lens (32) are cemented together; The third lens (33) is a meniscus positive lens; The fourth lens (34) is a biconvex lens; The fifth lens (35) is a plano-convex lens; The sixth lens (36) is a biconvex lens.

5. The QCS fiber optic head water-cooled beam expander and focusing lens according to claim 4, characterized in that, The first lens (31) is made of ZF2 series optical glass, and the second lens (32), third lens (33), fourth lens (34), fifth lens (35) and sixth lens (36) are all made of fused silica.

6. The QCS fiber optic head water-cooled beam expander and focusing lens according to claim 4, characterized in that, A spacer (37) for controlling the air gap is provided between the second lens (32) and the third lens (33), between the third lens (33) and the fourth lens (34), between the fourth lens (34) and the fifth lens (35), and between the fifth lens (35) and the sixth lens (36).

7. The QCS fiber optic head water-cooled beam expander and focusing lens according to claim 1, characterized in that, The beam expander module (2) includes a beam expander negative film holder (21), a beam expander negative film (22), a beam expander positive film holder (23), a beam expander positive film (24), and a rotating handwheel (25). The beam expander negative (22) is disposed in the beam expander negative fixing base (21), and the beam expander positive (24) is disposed in the beam expander positive lens base (23); The rotating handwheel (25) is fitted outside the beam expander positive lens mount (23) and is connected by a threaded pair; A fixing screw (26) is provided between the beam expander negative plate fixing seat (21) and the rotating handwheel (25). The fixing screw (26) restricts the axial movement of the rotating handwheel (25) and allows the rotating handwheel (25) to rotate.

8. The QCS fiber optic head water-cooled beam expander and focusing lens according to claim 7, characterized in that, The beam expander module (2) also includes a limiting and fixing component (27), which is installed at the tail end of the rotating handwheel (25) or the beam expander positive lens mount (23) for axial limiting.

9. The QCS fiber optic head water-cooled beam expander and focusing lens according to claim 8, characterized in that, The axial movement of the beam expander (24) is within the range of ±5mm.

10. The QCS fiber optic head water-cooled beam expander and focusing lens according to claim 8, characterized in that, The beam expander module (2) also includes a water-cooled mirror tube (28) and at least one water-cooled connector (29). The front end of the water-cooled lens tube (28) is connected to the rear end of the beam expander negative film holder (21), and the rear end is connected to the limiting and fixing member (27). A cooling channel is formed between the inner wall of the water-cooled mirror tube (28) and the outer surface of the tail of the beam expander negative plate holder (21); The water-cooled connector (29) is installed on the water-cooled mirror tube (28) and is connected to the cooling channel.

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