Flexible and adjustable laser spot generation method

Abstract

The invention provides a flexible and adjustable laser spot generation method, and the method comprises the following steps: S1, providing a laser which can generate an Airy beam; s2, providing a focusing lens, and focusing the Airy beam through the focusing lens; s3, providing a multi-core optical fiber, wherein the multi-core optical fiber at least sequentially comprises a first fiber core, a second fiber core, a first cladding, a second cladding and a low-refractive-index coating from inside to outside; and S4, moving the multi-core optical fiber back and forth along the Z-axis direction. According to the laser spot generation method provided by the invention, the focusing lens and the multi-core optical fiber are adjusted to move back and forth along the Z-axis direction, so that when the Airy beam is coupled into the multi-core optical fiber and then is output, laser beams with various spot energy distribution forms can be obtained, the process technology level of an existing laser processing technology can be improved, and the production efficiency is improved. And the application scene of the laser optical system is expanded.

Description

Technical Field

[0001] The present invention relates to the field of laser technology, and more specifically, to a method for generating a flexible and adjustable laser spot. Background Art

[0002] In recent years, with the continuous development of laser processing technology, in the field of industrial processing, laser processing has been increasingly widely used. At the same time, higher requirements have been continuously put forward for laser processing technology.

[0003] The spot energy distribution of the laser beam generated by the traditional laser optical system is generally Gaussian distribution. The Gaussian distribution laser optical system has many application scenarios, such as laser cutting, laser welding, laser cladding, laser marking, and so on.

[0004] In order to expand the application range of the laser optical system, current technicians have developed a laser optical system with an annular spot. The laser optical system with an annular spot also has some advantages in some laser processing fields such as laser cutting, laser cladding, and laser internal engraving. However, the central energy of the annular spot is low, and it also has some limitations in many laser processing applications.

[0005] In order to expand the application scenarios of the laser optical system, it is very necessary to improve the process technology level of the existing technology and invent a method for generating a flexible and adjustable laser spot. Summary of the Invention

[0006] The purpose of this application is to provide a method for generating a flexible and adjustable laser spot with convenient operation to solve the problems raised in the above background art.

[0007] To achieve the above purpose, this application provides the following technical solution: This application provides a method for generating a flexible and adjustable laser spot.

[0008] The method for generating a flexible and adjustable laser spot includes the following steps:

[0009] S1: Provide a laser that can generate an Airy beam;

[0010] S2: Provide a focusing lens to focus the Airy beam through the focusing lens;

[0011] S3: Provide a multi-core optical fiber that at least sequentially includes, from the inside to the outside: a first core, a second core, a first cladding, a second cladding, and a low-refractive-index coating;

[0012] S4: Move the multi-core optical fiber back and forth along the Z-axis direction.

[0013] The method for generating a laser spot provided by the present application can control the spot diameter of the Airy beam by adjusting the focusing lens. At the same time, by adjusting the front and back movement of the multi-core optical fiber along the Z-axis direction, the distance between the end face of the multi-core optical fiber and the focus of the Airy beam can be changed. Furthermore, when the Airy beam is coupled into the multi-core optical fiber and then output, laser beams with various spot energy distribution forms such as Gaussian beams, flat-top beams, annular beams, and composite beams can be obtained, improving the technical level of existing laser processing technologies and expanding the application scenarios of the laser optical system. Description of the Drawings

[0014] To more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0015] Figure 1 Structural schematic diagram of the laser optical system provided by the present application;

[0017] Figure 2 Spot energy distribution diagram under the first embodiment of the Airy beam;

[0018] Figure 3 Spot energy distribution diagram under the second embodiment of the Airy beam;

[0019] Figure 4 Spot energy distribution diagram under the third embodiment of the Airy beam;

[0020] Figure 5 Structural schematic diagram of the end face of the multi-core optical fiber in the laser optical system provided by the present application;

[0021] Figure 6 Schematic diagram of the method for generating a flexible and adjustable laser spot provided by the present application;

[0022] Figure 7 Energy distribution diagram of the first spot generated by the method for generating a laser spot provided by the present application;

[0023] Figure 8 Energy distribution diagram of the second spot generated by the method for generating a laser spot provided by the present application;

[0024] Figure 9 Energy distribution diagram of the third spot generated by the method for generating a laser spot provided by the present application;

[0025] Figure 10 Energy distribution diagram of the fourth spot generated by the method for generating a laser spot provided by the present application;

[0026] Figure 11 Energy distribution diagram of the fifth light spot generated by the laser spot generation method provided for this application;

[0027] Figure 12 Energy distribution diagram of the sixth light spot generated by the laser spot generation method provided for this application.

[0028] Reference numerals: 1, laser; 2, focusing lens; 3, multi-core optical fiber; 31, first core; 33, second core; 32, first cladding; 34, second cladding; 35, low-refractive coating. Detailed implementation manners

[0029] To enable those skilled in the art to better understand the solution of this application, the following further elaborates on this application in conjunction with the accompanying drawings and specific implementation manners. Obviously, the described embodiments are only a part of the embodiments of this application, rather than a limitation on the scope of rights of this application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts shall fall within the scope of protection of this application.

[0030] Please refer to Figure 1 , Figure 1 which is a schematic structural diagram of a laser optical system for generating a flexibly adjustable laser spot provided for this application. This laser optical system sequentially includes: a laser 1, a focusing lens 2, and a multi-core optical fiber 3. The laser 1 can generate an Airy beam, and the focusing lens 2 focuses the Airy beam to the position of the focal point f.

[0031] In a specific embodiment, generally, the laser 1 outputs an Airy beam by means of spatial laser transmission. Specifically: The laser 1 includes a laser light source (not shown in the figure), a collimator (not shown in the figure), and a beam shaping mirror (not shown in the figure). The laser light source can generate a Gaussian beam, the collimator is used to adjust the Gaussian beam emitted by the laser light source into a collimated parallel light, and the beam shaping mirror is used to shape the collimated parallel light output by the collimator into an Airy beam.

[0032] To clearly illustrate the characteristics of the Airy beam, the following combines Figures 2 to 4 to illustrate the characteristics of the Airy beam.

[0033] As Figures 2 to 4 shown, Figures 2 to 4 are respectively the spot energy distribution diagrams of three embodiments of the Airy beam.

[0034] As Figure 2 shown, Figure 2It is the spot energy distribution diagram under the first embodiment of the Airy beam. The focused spot of the Airy beam at the focus f is a Gaussian spot, and its energy distribution conforms to the Gaussian distribution.

[0035] As Figure 3 shown, Figure 3 It is the spot energy distribution diagram under the second embodiment of the Airy beam. As it moves left or right from the focus f, the central energy of its spot will gradually weaken until it reaches the position of f1 or f2 which is 1 Rayleigh length away from the focus f. At this position, the spot energy distribution becomes a flat-top spot distribution.

[0036] As Figure 4 shown, Figure 4 It is the spot energy distribution diagram under the third embodiment of the Airy beam. If it continues to move left from the position of f1 which is 1 Rayleigh length to the left of the focus f, the central energy of the spot will continue to weaken. Furthermore, an annular spot is formed at the position of f3 which is 2 Rayleigh lengths to the left of the focus f.

[0037] If it continues to move left, the central energy will gradually increase again, and a flat-top beam or a Gaussian beam, etc. will be formed again. The above embodiments are only for better explaining the characteristics of the Airy beam, and other specific changes will not be elaborated.

[0038] Since the current Airy beams are all in the form of spatial laser output that transmits laser through various lenses, in actual use, if different spot energy distribution forms are to be used for industrial processing, the control difficulty is large, and the stability for processing operations is also poor. Moreover, this type of laser form cannot obtain a composite spot formed by the combination of Gaussian spots / flat-top spots and annular spots.

[0039] The special feature of this application is that it also provides a multi-core optical fiber 3.

[0040] Please refer to Figure 5 , Figure 5 It is a schematic diagram of the end face structure of the multi-core optical fiber in the laser optical system provided by this application. The multi-core optical fiber 3 at least sequentially includes from the inside to the outside: a first core 31, a second core 33, a first cladding 32, a second cladding 34, and a low-refractive coating 35, and the multi-core optical fiber 3 can move back and forth along the Z-axis direction. By adjusting the back-and-forth movement of the multi-core optical fiber 3 along the Z-axis direction, the distance between the end face of the multi-core optical fiber 3 and the focus f of the Airy beam is changed. Furthermore, when the Airy beam is coupled into the multi-core optical fiber 3 and then output, laser beams with various spot energy distribution forms can be obtained, expanding the application scenarios of the laser optical system.

[0041] Please refer to Figure 6 , Figure 6 It is a schematic diagram of the method for generating a flexible and adjustable laser spot provided by this application.

[0042] The method for generating a flexible and adjustable laser spot provided by this application includes the following steps:

[0043] S1: Provide a laser 1, which can generate an Airy beam;

[0044] S2: Provide a focusing lens 2, and focus the Airy beam through this focusing lens 2;

[0045] S3: Provide a multi-core optical fiber 3, which at least sequentially includes from inside to outside: a first core 31, a second core 33, a first cladding 32, a second cladding 34, and a low-refractive-index coating 35;

[0046] S4: Move the multi-core optical fiber 3 back and forth along the Z-axis direction.

[0047] Please refer to Figure 7 , Figure 7 , which is the energy distribution diagram of the first spot generated by the laser spot generation method provided by this application. When the multi-core optical fiber 3 is a single-mode optical fiber, the Airy beam is focused and adjusted through the focusing lens 2. By changing the spot diameter of the Airy beam at the end face of the multi-core optical fiber 3, the diameter of the first core 31 is made larger than the diameter of the spot of the Airy beam at the end face of the first core 31. At this time, regardless of whether the end face of the multi-core optical fiber 3 is located at the focus f of the integer-shaped focused Airy beam or other positions, all the energy of the focused light will be received by the first core 31. For example, the position of the end face of the multi-core optical fiber 3 can be at the focus f or at positions f1, f2, f3, etc. that are 1 or 2 times the Rayleigh length to the left of the focus f of the Airy beam. As Figure 7 shown, the laser beam output through this multi-core optical fiber 3 will become a Gaussian beam, and its spot energy distribution will follow the characteristics of a Gaussian beam.

[0048] Please refer to Figure 8 , Figure 8 , which is the energy distribution diagram of the second spot generated by the laser spot generation method provided by this application. The multi-core optical fiber 3 is still a single-mode optical fiber. If the multi-core optical fiber 3 is adjusted to be movable back and forth along the Z-axis direction so that its end face is located at the position f3 that is 2 times the Rayleigh length to the left of the focus f of the integer-shaped focused Airy beam. If the inner diameter size of the annular spot at the f3 position is adjusted to be larger than the inner diameter size of the second annular core 33 and the outer diameter size of the annular spot is smaller than the outer diameter size of the second annular core 33 through the focusing lens 2, the energy of the focused light will be basically all received by the second annular core 33. As Figure 8 shown, the laser output from the multi-core optical fiber 3 can only be in the form of an annular beam and cannot form the form of a Gaussian beam.

[0049] Please refer to Figure 9 , Figure 9Energy distribution diagram of the third light spot generated by the laser light spot generation method provided in this application. The multi-core optical fiber 3 is still a single-mode optical fiber. The Airy beam is focused and adjusted by the focusing lens 2. By changing the spot diameter of the Airy beam at the end face of the multi-core optical fiber 3, the outer diameter of the spot at the end face of the first core 31 of the Airy beam is made larger than the inner diameter of the second annular core 33, and the inner diameter of the spot at the end face of the first core 31 of the Airy beam is made smaller than the diameter of the first core 31. Then, part of the energy of the focused light will be received by the first core 31, and part will be received by the second annular core 33. At this time, the laser output by the multi-core optical fiber 3 is a composite beam of a Gaussian beam and an annular beam, that is, the Gaussian beam is output through the first core 31, and the annular beam is output through the second annular core 33.

[0050] Please refer to Figure 10 , Figure 10 Energy distribution diagram of the fourth light spot generated by the laser light spot generation method provided in this application. When the multi-core optical fiber 3 is a multi-mode optical fiber, the Airy beam is focused and adjusted by the focusing lens 2. By changing the spot diameter of the Airy beam at the end face of the multi-core optical fiber 3, the diameter of the first core 31 is made larger than the diameter of the spot of the Airy beam at the end face of the first core 31. At this time, regardless of whether the end face of the multi-core optical fiber 3 is located at the focal point f of the integer-focused Airy beam or other positions, all the energy of the focused light will also be received by the first core 31. As Figure 10 shown, since the multi-mode optical fiber has the effect of homogenizing the laser beam, the Airy beam will output a flat-top beam after transmission in the multi-mode optical fiber, and the energy distribution of the laser light spot generated in this embodiment will follow the characteristics of the flat-top beam.

[0051] Please refer to Figure 11 , Figure 11 Energy distribution diagram of the fifth light spot generated by the laser light spot generation method provided in this application. The multi-core optical fiber 3 is still a multi-mode optical fiber. If the multi-core optical fiber 3 can be adjusted to move back and forth along the Z-axis direction so that its end face is located at a position f3 which is 2 times the Rayleigh length to the left of the focal point f of the integer-focused Airy beam. If the inner diameter size of the annular spot at the f3 position is adjusted to be larger than the inner diameter of the second annular core 33 through the focusing lens 2, and the outer diameter size of the annular spot is smaller than the outer diameter of the second annular core 33, the energy of the focused light will be basically all received by the second annular core 33. As Figure 8 shown, the laser output by the multi-core optical fiber 3 will only be in the form of an annular beam and cannot form a flat-top beam form.

[0052] Please refer to Figure 12 , Figure 12Energy distribution diagram of the sixth light spot generated by the laser light spot generation method provided in this application. The multi-core optical fiber 3 is still a multi-mode optical fiber. The Airy beam is focused and adjusted by the focusing lens 2. By changing the spot diameter of the Airy beam at the end face of the multi-core optical fiber 3, the outer diameter of the spot of the Airy beam at the end face of the first core 31 is made larger than the inner diameter of the second annular core 33, and the inner diameter of the spot of the Airy beam at the end face of the first core 31 is smaller than the diameter of the first core 31. Then, part of the energy of the focused light will be received by the first core 31, and part will be received by the second annular core 33. At this time, the laser output by the multi-core optical fiber 3 is a composite beam of a Gaussian beam and an annular beam, that is, a flat-top beam is output through the first core 31, and an annular beam is output through the second annular core 33.

[0053] This application Figure 9 and Figure 12 The composite beams shown in the embodiments of can also be divided into several cases. Specifically, when the spot of the Airy beam at the end face of the first core 31 is a non-annular spot, such as a Gaussian spot, a flat-top spot, etc., the inner diameter of the spot of the Airy beam at the end face of the first core 31 can be equal to zero. When the spot of the Airy beam at the end face of the first core 31 is an annular spot, the projection of the annular spot on the end face of the multi-core optical fiber 3 covers at least part of the end face regions of the first core 31 and the second annular core 33 and all of the end face region of the first cladding 32. Undoubtedly, by moving the multi-core optical fiber 3 back and forth along the Z-axis direction, when the distance position between the end face of the multi-core optical fiber 3 and the focus of the Airy beam changes, the spot of the Airy beam at the end face of the first core 31 will present different spot morphologies, and different spot morphologies will cause changes in the energy distribution ratio of the Airy beam entering the first core 31 and the second annular core 33 of the multi-core optical fiber 3, and further, the energy ratio of the Gaussian beam / flat-top beam and the annular beam of the output composite beam can be adjusted.

[0054] Of course, the above composite spot can also adjust the focusing of the Airy beam by adjusting the focusing lens 2, thereby changing the spot diameter of the Airy beam at the end face of the multi-core optical fiber 3, and then flexibly allocating the energy ratio of the Gaussian beam / flat-top beam output by the first core 31 and the annular beam output by the second annular core 33. That is, the flexible and adjustable laser spot generation method provided in this application can form a composite beam with a variety of flexibly changing spot morphologies.

[0055] Due to the excessively high temperature of the processing center of a single Gaussian-distributed laser beam, it is easy to generate splashes during laser processing, which may damage the electronic components around the workpiece. At the same time, due to the large temperature difference between the processing center and its surroundings during the processing, a temperature gradient is formed, resulting in uneven heating of the workpiece and various problems such as deformation, bubbles, and cracks in the workpiece.

[0056] However, in laser processing applications, a composite beam that simultaneously includes a Gaussian beam / flat-top beam and an annular beam can reduce the temperature gradient because an annular heating field is formed around the original processing position of the workpiece, thereby alleviating problems such as multi-core fiber curling, splashing, bubbles, and cracks during laser processing. The composite beam generated by the laser spot generation method provided in this application can also achieve high-quality laser processing operations in various application scenarios by adjusting the energy ratio distribution of the Gaussian beam / flat-top beam and the annular beam.

[0057] Based on the characteristic that the spot energy distribution of an Airy beam forms a completely different energy distribution at different positions, after the Airy beam is coupled by the multi-core fiber 3 in the laser spot generation method provided in this application, the output spot can form more energy distribution patterns. Compared with the spatially output Airy beam, the laser beam obtained in this application is output in the form of an optical fiber for industrial processing, with less manipulation difficulty and lower stability for processing operations. At the same time, the laser spot generation method provided in this application also has advantages such as simple operation and low cost.

[0058] It should be noted that the multi-core fiber in the above embodiment is a dual-core fiber. However, in actual embodiments, the multi-core fiber can also be a triple-core fiber with an additional core layer and a cladding layer added on the basis of the dual-core fiber, or a multi-core fiber with more core layers and cladding layers added, which can generate laser beams with more spot patterns. For example, the multi-core fiber 3 can also be a triple-core fiber with an additional third annular core (not shown in the figure) and a third cladding layer (not shown in the figure) added on the basis of the dual-core fiber. The core layer and the cladding layer are arranged at intervals, and a new composite beam containing 2 annular beams can be formed. Taking the dual-core fiber as an example here is only because the dual-core fiber structure is simpler and easier to explain and understand, and this embodiment does not constitute a limitation on the scope of rights of this application.

[0059] The method for generating a flexible and adjustable laser spot described in this application can be used in various laser processing application fields such as laser cutting, laser welding, laser engraving, laser cleaning, and laser additive manufacturing, greatly expanding the application range of the existing laser optical system.

[0060] It should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that the elements inherent in a process, method, article or device comprising a series of elements. Without further limitation, an element defined by the statement "comprising a..." does not exclude the existence of additional identical elements in the process, method, article or device comprising the said element. In addition, the parts of the above technical solutions provided by the embodiments of the present application that are consistent with the corresponding technical solutions in the prior art are not described in detail to avoid excessive repetition.

[0061] Specific examples are used in this text to elaborate on the principles and implementation manners of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application. It should be noted that for those of ordinary skill in the art, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and the various embodiments of the present application can be combined. These improvements, modifications and combinations also fall within the protection scope of the claims of the present application.

Claims

1. A method for generating a flexible and adjustable laser spot, characterized in that , including the following steps: S1: Provide a laser (1) that can generate an Airy beam; S2: Provide a focusing lens (2) to focus the Airy beam through the focusing lens (2); S3: Provide a multi-core optical fiber (3) that at least sequentially includes, from the inside to the outside: a first core (31), a second core (33), a first cladding (32), a second cladding (34), and a low-index coating (35); S4: Move the multi-core optical fiber (3) back and forth along the Z-axis direction.

2. The method for generating a flexible and adjustable laser spot according to claim 1, wherein , the multi-core optical fiber (3) is a single-mode optical fiber, and the focusing lens (2) is used to adjust the focusing of the Airy beam so that the diameter of the first core (31) is larger than the diameter of the spot of the Airy beam at the end face of the first core (31).

3. The method for generating a flexible and adjustable laser spot according to claim 1, wherein , the multi-core optical fiber (3) is a single-mode optical fiber, and the multi-core optical fiber (3) is adjusted to be movable back and forth along the Z-axis direction so that its end face is located at a position 2 times the Rayleigh length to the left of the focus of the integer-shaped and focused Airy beam, and an annular spot is formed on the end face of the multi-core optical fiber (3); Adjust the size of the annular spot on the end face through the focusing lens (2) so that the inner diameter size of the annular spot is larger than the inner diameter size of the second annular core (33), and the outer diameter size of the annular spot is smaller than the outer diameter size of the second annular core (33).

4. The method for generating a flexible and adjustable laser spot according to claim 1, wherein , the multi-core optical fiber (3) is a single-mode optical fiber, and the focusing lens (2) is used to adjust the focusing of the Airy beam so that the outer diameter of the spot of the Airy beam at the end face of the first core (31) is larger than the inner diameter of the second annular core (33), and the inner diameter of the spot of the Airy beam at the end face of the first core (31) is smaller than the diameter of the first core (31).

5. The method for generating a flexible and adjustable laser spot according to claim 4, wherein , by moving the multi-core optical fiber (3) back and forth along the Z-axis direction or by adjusting the focusing lens (2) to change the diameter size of the spot of the Airy beam at the end face of the multi-core optical fiber (3), thereby changing the energy ratio of the Gaussian beam output by the first core (31) and the annular beam output by the second annular core (33).

6. The method for generating a flexible and adjustable laser spot according to claim 1, characterized in that , the multi-core optical fiber (3) is a multi-mode optical fiber, and the focusing lens (2) is used to adjust the focusing of the Airy beam so that the diameter of the first core (31) is larger than the diameter of the spot of the Airy beam at the end face of the first core (31).

7. The method for generating a flexibly adjustable laser spot according to claim 1, wherein , the multi-core optical fiber (3) is a multi-mode optical fiber, and the multi-core optical fiber (3) is adjusted to be movable back and forth along the Z-axis direction so that its end face is located at a position 2 times the Rayleigh length to the left of the focus of the integer-shaped and focused Airy beam, and an annular spot is formed on the end face of the multi-core optical fiber (3); Adjust the size of the annular spot on the end face through the focusing lens (2) so that the inner diameter size of the annular spot is larger than the inner diameter size of the second annular core (33), and the outer diameter size of the annular spot is smaller than the outer diameter size of the second annular core (33).

8. The method for generating a flexibly adjustable laser spot according to claim 1, wherein , The multi-core optical fiber (3) is a multi-mode optical fiber. The Airy beam is focused and adjusted by the focusing lens (2) so that the outer diameter of the spot at the end face of the first core (31) of the Airy beam is larger than the inner diameter of the second annular core (33), and the inner diameter of the spot at the end face of the first core (31) of the Airy beam is smaller than the diameter of the first core (31).

9. The method for generating a flexible and adjustable laser spot according to claim 8, wherein , By moving the multi-core optical fiber (3) back and forth along the Z-axis direction or by adjusting the focusing lens (2), the spot diameter of the Airy beam at the end face of the multi-core optical fiber (3) is changed, thereby changing the energy ratio of the flattened beam output from the first core (31) and the annular beam output from the second annular core (33).

10. The method for generating a flexible and adjustable laser spot according to claim 1, characterized in that , The multi-core optical fiber (3) is a three-core optical fiber, and a third annular core and a third cladding are additionally added on the basis of the double-core optical fiber.

Images