A pulsed fiber laser with adjustable transverse mode for cleaning

Abstract

The present invention relates to a pulsed fiber laser for cleaning with adjustable transverse mode, comprising a pulsed laser seed source, a fiber laser beam splitter, a pulsed laser amplifier, a mode-adjustable laser beam combiner and a laser output end cap, wherein the pulsed laser seed source is connected to the fiber laser beam splitter, the fiber laser beam splitter is connected to a plurality of pulsed laser amplifiers, the pulsed laser amplifiers are all individually controlled, the plurality of pulsed laser amplifiers are connected to the mode-adjustable laser beam combiner, and the mode-adjustable laser beam combiner is connected to the laser output end cap. The output light spot mode field distribution is controlled by the mode-adjustable laser beam combiner, and a plurality of individually controlled pulsed lasers are combined by the mode-adjustable laser beam combiner. By controlling the power of each laser beam, the power of the output laser fiber core and cladding laser is regulated, and the transverse energy density distribution of the output laser is modulated, the interaction process between the laser and the substance is optimized, and different complex cleaning scenes are adapted.

Description

Technical Field

[0001] The invention relates to the technical field of laser cleaning, in particular to a cleaning pulse optical fiber laser with adjustable transverse mode. Background Art

[0002] As a new and efficient surface cleaning technology, laser cleaning technology has developed rapidly since 1965. The advantages of laser cleaning technology are as follows: (1) There is no physical contact with the workpiece, no chemical reagents are required, and the surface coating of the material can be selectively removed by controlling the laser process parameters; (2) It can remove various coatings on the surface of the substrate and achieve a high degree of cleanliness, and its application range is very wide; (3) It can clean the surfaces of various complex structures; (4) The small amount of smoke and dust generated during the cleaning process can be processed by the dust collection system, and basically does not cause pollution to the environment; (5) When the laser irradiates the coating, a series of thermal effects (ablation, thermal shock, vibration, plasma shock wave, etc.) can be generated, which can improve the roughness, microhardness and corrosion resistance of the substrate surface. Thanks to these technical advantages, laser cleaning technology has been applied to industrial processing, high-end manufacturing, cultural relics protection and other fields.

[0003] With the continuous deepening of laser cleaning technology in different application fields, the objects of laser cleaning have gradually expanded from single simple materials to complex materials such as titanium alloys, carbon fibers, and composite materials. The application scenarios have also gradually expanded from single rust removal to precision processing technology scenarios such as paint removal, surface oxide layer removal, and surface coating removal. The current principle of laser cleaning technology is mainly the chemical and physical reactions such as ablation and vibration produced by the material to be cleaned under the action of laser, thereby achieving the purpose of cleaning the material. Therefore, the interaction process between the laser and the material to be cleaned plays a decisive role in the laser cleaning effect.

[0004] At present, the laser light sources of laser cleaning technology are all transverse mode non-adjustable light sources, and the transverse light field distribution of the laser output by the laser presents a Gaussian distribution or a flat-top distribution. For the Gaussian distribution, the energy is concentrated in the center of the spot, and the laser energy gradually decreases toward the edge of the spot, resulting in uneven cleaning effect within the spot range when the laser interacts with the material to be cleaned, and it is easy to cause damage to the base material at the center of the spot energy concentration; for the flat-top distribution, although the energy density can be uniformed, it inevitably causes a decrease in cleaning efficiency and a decrease in cleaning depth. Summary of the invention

[0005] (1) Technical issues to be solved

[0006] The embodiment of the present invention provides a pulsed fiber laser for cleaning with adjustable transverse mode, which solves the technical problems of uneven spot energy distribution, resulting in damage to the substrate, low cleaning efficiency and difficulty in adapting to cleaning in complex situations.

[0007] (2) Technical solution

[0008] An embodiment of the present invention proposes a pulsed fiber laser for cleaning with adjustable transverse mode, comprising: a pulsed laser seed source, a fiber laser beam splitter, a pulsed laser amplifier, a mode-adjustable laser beam combiner and a laser output end cap, wherein the pulsed laser seed source is connected to the fiber laser beam splitter, the fiber laser beam splitter is connected to a plurality of the pulsed laser amplifiers, the pulsed laser amplifiers are all controlled individually, the plurality of the pulsed laser amplifiers are connected to the mode-adjustable laser beam combiner, and the mode-adjustable laser beam combiner is connected to the laser output end cap.

[0009] Furthermore, the mode-adjustable laser beam combiner comprises an input fiber bundle and an output fiber, and the input fiber bundle and the output fiber are matched by taper and fused into a fiber beam combiner.

[0010] Furthermore, the input fiber bundle comprises a central input fiber, a peripheral input fiber and a glass sleeve, wherein the central input fiber is arranged at the center of the glass sleeve, and a plurality of the peripheral input fibers are arranged in a ring array between the central input fiber and the glass sleeve.

[0011] Furthermore, the central light beam optical fiber size is larger than the peripheral optical fiber size.

[0012] Furthermore, the central input optical fiber comprises a central input optical fiber core and a central input optical fiber cladding, and the central input optical fiber cladding is sleeved on the central input optical fiber core.

[0013] Furthermore, the peripheral input optical fiber comprises a peripheral input optical fiber core and a peripheral input optical fiber cladding, and the peripheral input optical fiber cladding is sleeved on the peripheral input optical fiber core.

[0014] Furthermore, the output optical fiber comprises an output optical fiber core and an output optical fiber inner cladding, and the output optical fiber inner cladding is sleeved on the output optical fiber core.

[0015] Furthermore, the power of each laser beam in the input fiber bundle is individually controlled to regulate the distribution of the output laser spot energy, the laser output from the central input fiber is coupled to the output fiber core, and the laser output from the peripheral input fiber is coupled to the inner cladding of the output fiber. The lateral energy density distribution of the output laser is regulated by controlling the ratio of the laser coupled from the inner cladding of the output fiber and the core of the output fiber.

[0016] (3) Beneficial effects

[0017] In summary, the present invention controls the output light spot mode field distribution through a mode-adjustable laser combiner, and multiple individually controlled pulsed lasers are combined through the mode-adjustable laser combiner. By controlling the power of each laser beam, the output laser fiber core and cladding laser power can be regulated, and the lateral energy density distribution of the output laser can be further modulated. Not only can uniformly distributed light field energy be achieved, but the energy density distribution of the output laser can also be regulated according to specific application scenarios to optimize the interaction process between the laser and the material, and adapt to different complex cleaning scenarios. On the basis of avoiding damage to the substrate, the cleaning efficiency is improved, and it is suitable for high-efficiency special material cleaning application scenarios, and has a good reference value for the cleaning of other materials, and has a wide applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments of the present invention are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 It is a schematic diagram of the structure of a pulsed fiber laser for cleaning with adjustable transverse mode;

[0020] Figure 2 is a transverse cross-sectional view of the input fiber bundle of the mode-tunable laser beam combiner;

[0021] Figure 3 is a transverse cross-sectional view of the output optical fiber of the mode-tunable laser combiner;

[0022] In the figure: 1. Pulse laser seed source; 2. Fiber laser beam splitter; 3. Pulse laser amplifier; 4. Mode-tunable laser combiner; 5. Laser output end cap; 4-1. Input fiber bundle; 4-2. Output fiber; 4-11. Central input fiber; 4-12. Peripheral input fiber; 4-13. Glass sleeve; 4-14. Central input fiber core; 4-15. Peripheral input fiber core; 4-16. Central input fiber cladding; 4-17. Peripheral input fiber cladding; 4-21. Output fiber core; 4-22. Output fiber inner cladding. DETAILED DESCRIPTION

[0023] The following is a further detailed description of the embodiments of the present invention in conjunction with the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to exemplarily illustrate the principles of the present invention, but cannot be used to limit the scope of the present invention, that is, the present invention is not limited to the described embodiments, and covers any modification, replacement and improvement of parts, components and connection modes without departing from the spirit of the present invention.

[0024] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0025] Please refer to Figure 1 The embodiment of the present invention proposes a transverse mode adjustable pulse fiber laser for cleaning, comprising: a pulse laser seed source 1, a fiber laser beam splitter 2, a pulse laser amplifier 3, a mode adjustable laser beam combiner 4 and a laser output end cap 5, wherein the pulse laser seed source 1 is connected to the fiber laser beam splitter 2, the fiber laser beam splitter 2 is connected to a plurality of the pulse laser amplifiers 3, the pulse laser amplifiers 3 are all individually controlled, the plurality of the pulse laser amplifiers 3 are connected to the mode adjustable laser beam combiner 4, and the mode adjustable laser beam combiner 4 is connected to the laser output end cap 5. The pulse laser seed source 1 generates laser pulses, and when the number of the pulse laser amplifiers 3 is n, the pulse seed laser is divided into n beams by the fiber laser beam splitter 2, each beam of pulse laser is amplified by the pulse laser amplifier 3, the power of each pulse laser amplifier 3 is individually controlled, the amplified laser pulses are combined by the mode adjustable laser beam combiner, and then output through the output end cap.

[0026] Please refer to Figure 2 and Figure 3 In some embodiments, the mode-adjustable laser combiner 4 includes an input fiber bundle 4-1 and an output fiber 4-2. The input fiber bundle 4-1 and the output fiber 4-2 are matched by taper and fused to form a fiber combiner. Further, the input fiber bundle 4-1 includes a central input fiber 4-11, a peripheral input fiber 4-12 and a glass sleeve 4-13. The central input fiber 4-11 is arranged at the center of the glass sleeve 4-13. A plurality of peripheral input fibers 4-12 are arranged in a ring array between the central input fiber 4-11 and the glass sleeve 4-13. When the number of the pulse laser amplifiers 3 is n, the number of the peripheral input fibers 4-12 is n-1. The size of the central beam fiber can be larger than the size of the peripheral fiber.

[0027] Please refer to Figure 2 and Figure 3In some embodiments, the central input optical fiber 4-11 includes a central input optical fiber core 4-14 and a central input optical fiber cladding 4-16, and the central input optical fiber cladding 4-16 is sleeved on the central input optical fiber core 4-14. The peripheral input optical fiber 4-12 includes a peripheral input optical fiber core 4-15 and a peripheral input optical fiber cladding 4-17, and the peripheral input optical fiber cladding 4-17 is sleeved on the peripheral input optical fiber core 4-15. The output optical fiber 4-2 includes an output optical fiber core 4-21 and an output optical fiber inner cladding 4-22, and the output optical fiber inner cladding 4-22 is sleeved on the output optical fiber core 4-21.

[0028] In some embodiments, the power of each laser beam in the input fiber bundle 4-1 is individually controlled to regulate the distribution of the output laser spot energy, the laser output from the central input fiber 4-11 is coupled to the output fiber core 4-21, and the laser output from the peripheral input fiber 4-12 is coupled to the output fiber inner cladding 4-22. The lateral energy density distribution of the output laser is regulated by controlling the ratio of the coupled lasers between the output fiber inner cladding 4-22 and the output fiber core 4-21.

[0029] The mode-adjustable laser combiner 4 is used to control the output light spot mode field distribution, and multiple individually controlled pulsed lasers are combined through the mode-adjustable laser combiner 4. By controlling the power of each laser beam, the output laser fiber core and cladding laser power can be regulated, and the lateral energy density distribution of the output laser can be further modulated. Not only can uniformly distributed light field energy be achieved, but the energy density distribution of the output laser can also be regulated according to specific application scenarios to optimize the interaction process between the laser and the material, adapt to different complex cleaning scenarios, and improve the cleaning efficiency while avoiding damage to the substrate. It is suitable for high-efficiency special material cleaning application scenarios, and has a good reference value for the cleaning of other materials, and has a wide applicability.

[0030] Example:

[0031] according to Figure 1 As shown in the figure, a pulse fiber laser system is built, using a Q-switched pulse fiber laser as a pulse laser seed source 1, with a single pulse energy of 0.5 mJ, a repetition frequency adjustable from 20 kHz to 100 kHz, and an output fiber size of 10 / 130 microns.

[0032] The fiber laser beam splitter 2 is a 1-to-7 type fiber laser beam splitter, which divides the pulse laser seed into 7 beams with equal energy. The size of the input / output optical fiber is 10 / 130 microns. After the pulse laser seed is split, it is injected into the pulse laser amplifier 3-1 to 3-7 for power amplification. In each amplification channel, a 2-stage cladding amplification is configured to amplify the pulse energy to 8mJ. The size of the amplifier output optical fiber is 50 / 400 microns. The 7 channels of 8mJ laser pulses are combined by the mode-adjustable laser combiner 4.

[0033] There are 7 optical fiber bundles in the mode-adjustable laser combiner 4, and the optical fiber claddings are closely arranged into a hexagon, the diameter of the circumscribed circle of the hexagon is 1200 microns, and the inner diameter of the glass sleeve 4-13 matches the size of the optical fiber bundle, which is also 1200 microns; the size of the central input optical fiber 4-11 is the same as the size of the peripheral input optical fiber 4-12, the central input optical fiber core 4-14 is 50 microns, the peripheral input optical fiber core 4-15 is 50 microns, the central input optical fiber cladding 4-16 is 400 microns, and the peripheral input optical fiber cladding 4-17 is 400 microns; the size of the output optical fiber core 4-2 is 100 / 400 microns, of which the output optical fiber core 4-21 is 100 microns, and the size of the output optical fiber inner layer 4-22 is 400 microns. The optical fiber bundle 4-1 is tapered so that the outer diameter of the glass tube 4-13 is less than 400 microns, and is further fused with the output optical fiber 4-2. The laser output from the central input optical fiber 4-11 is coupled to the core 4-21 of the output optical fiber, and the laser output from the peripheral input optical fiber 4-12 is coupled to the cladding 4-22 of the output optical fiber. The ratio of the cladding and core coupled lasers can be controlled to regulate the lateral energy density distribution of the output laser.

[0034] It should be clear that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. The present invention is not limited to the specific steps and structures described above and shown in the figures. In addition, for the sake of brevity, a detailed description of known methods and technologies is omitted here.

[0035] The above is only an embodiment of the present application and is not limited to the present application. For those skilled in the art, the present application may have various changes and variations without departing from the scope of the present invention. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A pulsed fiber laser for cleaning with adjustable transverse mode, characterized in that: include: A pulse laser seed source, a fiber laser beam splitter, a pulse laser amplifier, a mode-adjustable laser beam combiner and a laser output end cap, wherein the pulse laser seed source is connected to the fiber laser beam splitter, the fiber laser beam splitter is connected to a plurality of the pulse laser amplifiers, the pulse laser amplifiers are all individually controlled, the plurality of the pulse laser amplifiers are connected to the mode-adjustable laser beam combiner, and the mode-adjustable laser beam combiner is connected to the laser output end cap; The mode-adjustable laser beam combiner comprises an input fiber bundle and an output fiber, wherein the input fiber bundle and the output fiber are matched by taper and fused to form a fiber beam combiner; The input optical fiber bundle comprises a central input optical fiber, a peripheral input optical fiber and a glass sleeve, wherein the central input optical fiber is arranged at the center of the glass sleeve, and a plurality of the peripheral input optical fibers are arranged in a ring array between the central input optical fiber and the glass sleeve; The output optical fiber comprises an output optical fiber core and an output optical fiber inner cladding, and the output optical fiber inner cladding is sleeved on the output optical fiber core; The power of each laser beam in the input fiber bundle is individually controlled to regulate the distribution of the output laser spot energy. The laser output from the central input fiber is coupled to the core of the output fiber, and the laser output from the peripheral input fiber is coupled to the inner cladding of the output fiber. The lateral energy density distribution of the output laser is regulated by controlling the ratio of the laser coupled from the inner cladding of the output fiber and the core of the output fiber.

2. The cleaning pulsed fiber laser with adjustable transverse mode according to claim 1, characterized in that: The central input optical fiber size is larger than the peripheral input optical fiber size.

3. A cleaning pulsed fiber laser with adjustable transverse mode according to claim 1 or 2, characterized in that: The central input optical fiber comprises a central input optical fiber core and a central input optical fiber cladding, and the central input optical fiber cladding is sleeved on the central input optical fiber core.

4. A cleaning pulsed fiber laser with adjustable transverse mode according to claim 1 or 2, characterized in that: The peripheral input optical fiber comprises a peripheral input optical fiber core and a peripheral input optical fiber cladding, and the peripheral input optical fiber cladding is sleeved on the peripheral input optical fiber core.

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