Laser beam coupling device and method

Abstract

The invention relates to a laser beam coupling device and method, relates to the technical field of laser coupling, and aims to solve the problems that an existing disc laser needs a position sensor to sense the rotation angle in real time, the rotation angle and the laser splitting distribution proportion need complex experiment debugging, and the use and production cost is greatly improved. The invention provides a laser beam coupling device which comprises an optical fiber coupler, a diaphragm and a beam splitting module, the optical fiber coupler and the diaphragm are connected with each other, the beam splitting module is connected to the end of the diaphragm and used for splitting laser entering the beam splitting module and coupling the laser into an optical fiber through the diaphragm and the optical fiber coupler, and the beam splitting module comprises a wedge prism and a deflection device. The wedge-shaped prism is driven by the deflection device to perform angle deflection, so that the laser entering the light splitting module is divided into two laser beams according to a required proportion, and the output power proportion of the optical fiber coupler to the inner core and the outer core of the cladding optical fiber is simply adjusted at low cost.

Description

Technical Field

[0001] This invention belongs to the field of laser coupling technology, and specifically relates to a laser beam coupling device. Background Technology

[0002] Like single-core fiber, multi-clad fiber transmits a laser beam from the light source to the processing head. The processing head collimates, focuses, or shapes the laser beam before using it to process the workpiece, such as cutting or welding. Different processing techniques typically have different requirements for the characteristic parameters of the laser beam, such as focusing diameter, intensity distribution, and beam profile.

[0003] The varying ratios of the inner and outer cores of a laser beam coupled into a ring fiber affect the beam characteristics and quality of the laser beam at the fiber's output. Existing designs primarily fall into two technical categories: fiber lasers and disk lasers. In fiber lasers, the fiber core and cladding are two fibers fused together, and the laser power within the core and cladding is fixed and unadjustable; the concept of laser beam splitting is not inherently involved. Trumpf's disk lasers, on the other hand, utilize a wedge mirror to distribute the beam to the fiber core and cladding, thus automatically allocating power. However, because the wedge mirror is driven by a stepper motor, a position sensor is required in real-time to detect the rotation angle. Furthermore, the stepper motor's rotation resolution must be at least 0.01 degrees. The rotation angle and the laser beam splitting ratio require complex experimental adjustments, significantly increasing both usage and production costs.

[0004] To address this problem, this application provides a low-cost laser beam coupling device to reduce usage and production costs. Summary of the Invention

[0005] To address the shortcomings of the existing technology, the present invention aims to provide a laser beam coupling device, comprising an optical fiber coupler, an aperture, and a beam splitter module. The aperture is connected between the optical fiber coupler and the beam splitter module. In use, an optical fiber is inserted into the end of the optical fiber coupler. The laser beam enters from the beam splitter module and is split into two beams. The aperture absorbs the omnidirectional laser beam from the split beam, allowing only the directional laser beam to enter the optical fiber coupler and be coupled to the inner and outer cores of the optical fiber. This device allows adjustment of the beam splitting ratio via the beam splitter module, thereby regulating the laser beam coupled into the optical fiber and adjusting the output power ratio between the inner and outer cores of the optical fiber.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A laser beam coupling device includes an optical fiber coupler, an aperture, and a beam splitter connected in sequence, wherein the beam splitter includes: The outer casing is connected to the end of the aperture. A wedge prism is housed inside the casing and connected to the deflection device; The deflection device, inserted inside the housing, is used to drive the wedge prism to rotate, thereby adjusting the laser beam splitting ratio.

[0007] Preferably, the deflection device includes: The rotating rod is rotatably inserted into the housing and is used to drive the transmission gear; The transmission gear is housed within the outer casing; The drive shaft is rotatably connected to the drive gear and also to the mechanical frame on the wedge prism.

[0008] Preferably, a small gear that meshes with the transmission gear is fitted on the rotating rod.

[0009] Preferably, the transmission ratio between the transmission gear and the pinion is 1:15 to 1:50.

[0010] Preferably, the wedge prism is made of quartz glass or quartz glass.

[0011] A second objective of this invention is to provide an operating method for a laser beam coupling device, characterized in that the operating method includes: The deflection device is activated, and the angle of the wedge prism is changed to split the laser beam entering the beam splitter into two laser beams according to the required ratio. The aperture allows the directional laser beams of the two laser beams to pass through, and the fiber coupler couples the two laser beams that have passed through the aperture into the optical fiber.

[0012] The beneficial effects of this invention are: This invention discloses a laser beam coupling device, and compared with the prior art, the improvement of this invention lies in: The beam splitting module in the laser beam coupling device of this invention can split the laser entering it into two laser beams according to different beam splitting ratios, so that the fiber coupler can couple the two laser beams into the optical fiber. The beam splitting module realizes the beam splitting and beam splitting ratio adjustment through a deflection device and a wedge prism. When the deflection device drives the wedge prism to adjust the angle, the ratio of the laser passing through the planar part and the wedge angle part of the wedge prism is adjusted to realize the beam splitting ratio adjustment, and finally realize the output power matching of the inner core and outer core of the optical fiber.

[0013] The deflection device uses a set of high-module gears to control the rotation angle with a large gear ratio. The small outer diameter gear is mainly used for debugging, while the large outer diameter gear is mainly used to fix the wedge prism through a central shaft and to perform the deflection of the wedge prism. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the laser beam coupling device of the present invention; Figure 2This is a schematic diagram of the beam splitting module structure of the present invention. Figure 1 ; Figure 3 This is a schematic diagram of the beam splitting module structure of the present invention. Figure 2 ; Figure 4 This is a schematic diagram of the beam splitting module structure of the present invention. Figure 3 ; Figure 5 This is a schematic diagram of the wedge-shaped prism structure of the present invention; Figure 6 This is a structural diagram of the internal structure of the beam splitting module of the present invention; Figure 7 This is a diagram showing the result of the laser not passing through the wedge angle of the wedge prism in this invention; Figure (a) shows the state of the laser beam before it passes through the wedge corner of the wedge prism; Figure (b) shows the dot array diagram of the fiber coupling point where the laser beam does not pass through the wedge corner of the wedge prism; Figure (c) shows the position of the laser beam before it passes through the wedge corner of the wedge prism. Figure 8 This is a diagram showing the result of most of the laser beam passing through the upper half of the central axis of the wedge-shaped prism's wedge angle portion in this invention. Figure (a) shows the state of the laser beam passing through the upper half of the central axis of the wedge corner of the wedge prism; Figure (b) shows the dot array diagram of the fiber coupling point where the laser beam passes through the upper half of the central axis of the wedge corner of the wedge prism; Figure (c) shows the position of the laser beam passing through the upper half of the central axis of the wedge corner of the wedge prism. Figure 9 This is a diagram showing the central axis result of half of the laser beam passing through the wedge prism in this invention; Figure (a) shows the state of the laser beam passing through the central axis of the wedge corner of the wedge prism; Figure (b) shows the dot array diagram of the fiber coupling point where half of the laser beam passes through the central axis of the wedge corner of the wedge prism; Figure (c) shows the position of the central axis where half of the laser beam passes through the wedge corner of the wedge prism. Figure 10 Figure 1 shows the result of the laser beam passing through the lower half of the central axis of the wedge corner portion of the wedge prism. Figure 2 shows the state of the laser beam passing through the lower half of the central axis of the wedge corner portion of the wedge prism. Figure 3 shows the dot array diagram of the fiber coupling point where the laser beam passes through the lower half of the central axis of the wedge corner portion of the wedge prism. Figure 4 shows the position of the laser beam passing through the lower half of the central axis of the wedge corner portion of the wedge prism. Figure 11 This is a diagram showing the lower half of the central axis of the wedge-shaped prism's wedge angle portion, after the laser beam of this invention has passed through the entire wedge angle portion. Figure (a) shows the state of the laser beam passing through the lower half of the central axis of the wedge corner of the wedge prism; Figure (b) shows the dot array diagram of the fiber coupling point of the lower half of the central axis of the wedge corner of the wedge prism; Figure (c) shows the position diagram of the laser beam passing through the lower half of the central axis of the wedge corner of the wedge prism.

[0015] Explanation of reference numerals in the attached drawings: 1. Fiber optic coupler; 2. Aperture; 3. Beam splitter module; 301. Housing; 3011. Hole; 302. Wedge prism; 303. Deflection device; 3031. Rotating rod; 3032. Transmission gear; 3033. Transmission shaft; 3034. High-module pinion; 304. Mechanical frame. Detailed Implementation

[0016] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments. The following embodiments are used for... This invention is described, but should not be used to limit its scope.

[0017] Example 1: See attached document Figures 1-6 The laser beam coupling device shown includes an optical fiber coupler 1, an aperture 2, and a beam splitter 3. The aperture 2 is connected between the optical fiber coupler 1 and the beam splitter 3. In use, an optical fiber is inserted into the end of the optical fiber coupler 1. The laser beam enters from the beam splitter 3 and is split into two laser beams. The aperture 2 is used to absorb the non-directional laser beam in the split laser beam, allowing only the directional laser beam to enter the optical fiber coupler 1 and be coupled to the inner core and outer core of the optical fiber.

[0018] In the embodiments of this application, both the fiber coupler 1 and the aperture 2 are existing mature products, and their coupling laser beam and absorption of omnidirectional laser are based on existing technologies and principles.

[0019] The existing fiber optic coupler 1 includes a lens system. This lens system can focus and couple a parallel beam into the optical fiber for long-distance transmission. The function of the fiber optic coupler 1 is to focus the split laser beam into two beams onto the cross-sections of the fiber core and the fiber cladding, respectively. It is a mature product with existing technology in terms of operating principle and components. The fiber optic coupler 1 can be a fiber optic coupler from manufacturer Thorlabs such as TT600R5S1B or topticaFiberDockTM.

[0020] In the embodiments of this application, reference is made to the appendix. Figures 2-4As shown, the beam splitting module 3 includes a housing 301, a wedge prism 302, and a deflection device 303. The housing 301 is connected to the aperture 2, and a hole 3011 for laser to pass through is provided on the housing 301. The hole 3011 is connected to the aperture 2. The wedge prism 302 is disposed inside the housing 301 through the deflection device 303 to split the laser entering the housing 301. The deflection device 303 is movably inserted into the housing 301 to adjust the angle of the wedge prism 302, thereby changing the beam splitting ratio.

[0021] The base thickness of the wedge prism 302 is 1mm-50mm, preferably 1mm-10mm, and it is used to split the incident laser beam into two, ultimately achieving the purpose of beam splitting.

[0022] The specific connection between the wedge prism 302 and the deflection device 303 is as follows: the wedge prism 302 is glued to the mechanical frame 304 with UV glue. The mechanical frame 304 is rotatably mounted on the inner wall of the outer shell 301 and is fixedly connected to the deflection device 303. The deflection device 303 can drive the mechanical frame 304 to rotate relative to the outer shell 301, thereby causing the mechanical frame 304 to drive the wedge prism 302 to rotate, thus realizing the angle adjustment of the wedge prism.

[0023] See attached document Figure 5 As shown, the wedge prism 302 is designed with one side being a flat parallel plate and the other side being a wedge angle. The wedge angle can be set with a deflection angle. Different deflection angles allow the laser to hit different positions on the wedge prism 302, achieving beam splitting with different energy ratios, thereby adjusting the output power ratio of the inner and outer cores of the multi-clad fiber. The optical wedge prism uses Corning 7979 or Corning 8655 as the substrate to enhance the transmittance to the colored laser band.

[0024] The wedge prism 302 is made of or contains quartz glass. Quartz glass has a high laser damage threshold, making it suitable for laser material processing. Furthermore, quartz glass is easy to process, thus reducing manufacturing costs. In use, the quartz glass requires double-sided anti-reflection coatings to reduce laser loss at the glass interface due to internal refraction or reflection. The use of an ultra-smooth surface and an ultra-low loss coating significantly suppresses scattering loss caused by surface roughness.

[0025] See attached document Figure 6 As shown, the deflection device 303 is used to drive the wedge prism 302 to deflect, thereby adjusting the beam splitting ratio of the laser beam coupled to the inner and outer cores of the double-clad fiber. Its advantage is that it can achieve continuous adjustment, realize rapid switching of different processing application requirements, and reduce mechanical workload.

[0026] The deflection device 303 is manually controlled. Its main principle is to achieve high-ratio rotation angle control through a set of high-module gears. The small outer diameter gear is mainly used for adjustment, while the large outer diameter gear mainly uses a central shaft to fix the wedge prism 302 and execute its deflection. In specific embodiments, such as during the production and debugging of the beam splitter module, the small outer diameter gear can integrate an electrically driven micro-motion head through mechanical meshing at its hexagonal end, achieving active rotation of the wedge prism 302. Its electronic control function supports continuously rotating the sub-beam deflection from its initial state to the target termination state.

[0027] Specifically, the deflection device 302 includes a rotating rod 3031, a transmission gear 3032, and a transmission shaft 3033. The rotating rod 3031 is rotatably inserted into the housing 301 through a bearing, and a high-module pinion 3034 is fixedly sleeved at its end. The high-module pinion 3034 meshes with the transmission gear 3032.

[0028] The transmission gear 3032 is a high-module large gear. One end of the transmission shaft 3033 is rotatably mounted on the transmission gear 3032 through a bearing, and the other end is fixedly connected to the mechanical frame 304. That is, the transmission gear 3032 can rotate relative to the transmission shaft 3033. The rotation of the transmission shaft 3033 can drive the mechanical frame 304 to rotate, but will not drive the transmission gear 3032 to rotate.

[0029] By manually rotating the lever 3031, the pinion 3034 can be driven to rotate. The pinion 3034 is also a high-module gear. The pinion 3034 drives the transmission gear 3032 to rotate. The rotation of the transmission gear 3032 drives the transmission shaft 3033 to rotate. The transmission shaft 3033 drives the mechanical frame 304 to rotate, which in turn drives the wedge prism 302 to rotate, thereby realizing the angle adjustment of the wedge prism 302.

[0030] The angle of the wedge prism can be adjusted by the transmission ratio of the pinion 3034 and the transmission gear 3032. In use, it can be set that for every revolution of the pinion, the transmission gear drives the wedge prism to rotate by 0.06°. If it continues to rotate for another revolution, the angle of the wedge prism will increase by 0.06°. In this embodiment, the transmission ratio of the transmission gear 3032 and the pinion 3034 is 1:15-1:50.

[0031] In this application, the laser provided is a laser device, which is a light source for providing a laser beam. The light source can be a continuous wave laser or a pulsed laser, especially an ultrashort pulse laser. The wavelength of the laser beam can be between 200nm and 2000nm, preferably 257nm, 295nm, 343nm, 515nm, 530nm, 550nm, 555nm, 580nm, 589nm, 595nm, 1030nm, 1070nm, or 1080nm.

[0032] Example 2: Example 2 shows the distribution of the light beam in the fiber core after the light beam passes through different parts of the wedge prism 302. This demonstrates that by adjusting the angle of the optical wedge prism 302, the light beam can pass through different parts of the optical wedge prism 302, thereby adjusting the range of laser coupling into the inner and outer core of the fiber.

[0033] For details, please refer to the attached document. Figure 7 As shown, when the light beam does not pass through the wedge angle portion of the wedge prism 302 in Embodiment 1, but is focused by only a focusing lens, the light spot can be seen to be concentrated into a circular spot. At this time, the laser will be completely coupled into the fiber core.

[0034] See attached document Figure 8 As shown, when most of the beam passes through the upper half of the central axis of the wedge angle portion of the wedge prism 302 and is focused by a focusing lens, the beam energy is divided into two parts. At this time, most of the laser energy is coupled into the inner core, and a small part of the energy is coupled into the outer core.

[0035] See attached document Figure 9 As shown, when half of the beam passes through the central axis of the wedge angle portion of the wedge prism 302, the beam energy is split into two parts. At this time, half of the laser energy is coupled into the inner core and half of the energy is coupled into the outer core. See attached document Figure 10 As shown, when most of the beam passes through the lower half of the central axis of the wedge angle portion of the wedge prism 302, the beam energy is divided into two parts. At this time, a small portion of the laser energy is coupled into the inner core, and most of the energy is coupled into the outer core.

[0036] See attached document Figure 11 As shown in the diagram, when the entire beam passes through the lower half of the central axis of the wedge angle portion of the wedge prism 302, the laser is completely coupled into the outer core.

[0037] In this embodiment, the dual-core, double-clad optical fiber comprises an inner core surrounded by an inner cladding layer with the lowest possible refractive index and the thinnest possible thickness. Outside the inner cladding is a single-layer annular outer core, also surrounded by a low-refractive-index outer cladding layer. Additionally, an outer cladding layer (or outer coating layer) may be included, which primarily determines the outer diameter of the fiber but has no effect on its light-guiding characteristics. The outermost layer is typically a protective coating made of silicone resin and / or plastic materials such as nylon, used to provide mechanical protection.

[0038] By using double-clad optical fiber, the laser can be fully coupled into the inner core, fully coupled into the outer core, or partially coupled into both the inner and outer cores. When the laser propagates entirely through the planar portion of the wedge-shaped ridge 302, it will be fully coupled into the inner core. When the laser propagates entirely through the wedge-shaped portion of the wedge-shaped ridge 302, it will be fully coupled into the outer core. When the laser propagates entirely through the middle portion of the wedge-shaped ridge 302, it will be partially coupled into both the inner and outer cores.

[0039] To obtain high-quality laser output, the laser beam needs to be coupled into the inner core of a double-core, double-clad fiber. In this case, the waveguide characteristics of the fiber are similar to those of a conventional step-index single-mode fiber—a single-core structure encased in a low-refractive-index inner cladding. However, when a large spot size or a specific intensity distribution (e.g., a flat-top uniform distribution) is required, the laser beam needs to be coupled to the outer ring core, or dual-channel coupling (simultaneously coupled to both the inner and outer ring cores) can be used. Depending on the coupling method required for different applications, the following typical beam profiles can be obtained at the fiber output: Inner core coupling: solid circular spot (diameter determined by the inner core mode field); Outer ring core coupling: ring spot; Dual-channel coupling: solid circular spot and ring spot (due to the obstruction of the inner cladding, a narrow ring dark region exists in the central area of ​​both spots).

[0040] When using laser radiation for material processing, especially with kilowatt (kW) high-power lasers, dynamic beam mode switching technology allows operators to flexibly select modes according to process requirements. For example: High beam quality mode: provides sharp focusing (forming a small focal spot), meeting the high energy density and precision requirements of processes such as laser cutting. Homogenized beam mode (or flat-top beam mode): presents a nearly uniform intensity distribution within the beam cross-section; this specific beam characteristic (sometimes referred to as "tunable beam quality") is particularly suitable for processes requiring a wide and uniform heat input, such as laser welding.

[0041] The substrate thickness is defined as the length of the longest side in the cross-section of the optical element. This cross-section must meet the following conditions: it must not contain the incident and exit surfaces of the laser beam; the incident laser beam and its split sub-beams must all lie within this cross-sectional plane. This substrate thickness design ensures the optical wedge has excellent structural stability.

[0042] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A laser beam coupling device, comprising an optical fiber coupler (1), an aperture (2), and a beam splitter (3) connected in sequence, characterized in that, The beam splitting module (3) includes: The outer casing (301) is connected to the end of the aperture (2); A wedge prism (302) is disposed inside the housing (301) and connected to the deflection device (303); The deflection device (303) is inserted inside the housing (301) and is used to drive the wedge prism (302) to rotate, thereby adjusting the laser beam splitting ratio.

2. A laser beam coupling device according to claim 1, characterized in that, The deflection device (303) includes: The rotating rod (3031) is rotatably inserted into the housing (301) and is used to drive the transmission gear (3032). The transmission gear (3032) is disposed inside the housing (301); The drive shaft (3033) is rotatably connected to the drive gear (3032) and is also connected to the mechanical frame (304) on the wedge prism (302).

3. A laser beam coupling device according to claim 2, characterized in that, A small gear (3034) is fitted on the rotating rod (3031) to mesh with the transmission gear (3032).

4. A laser beam coupling device according to claim 3, characterized in that, The transmission ratio between the transmission gear (3032) and the pinion (3034) is 1:15-1:

50.

5. A laser beam coupling device according to claim 1, characterized in that, The wedge prism (302) is made of quartz glass or quartz glass.

6. The method of operating a laser beam coupling device as described in any one of claims 1-5, characterized in that, The operation method includes: Turn on the deflection device (303) and change the angle of the wedge prism (302) to split the laser beam entering the beam splitting module (3) into two laser beams according to the required ratio; the aperture (2) allows the directional laser beam in the two laser beams to pass through, and the fiber coupler (1) couples the two laser beams that have passed through the aperture (2) into the fiber.

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