Laser Processing Equipment

Abstract

This laser processing device (10) comprises a plurality of laser sources (11), optical fibers (12) connected to each of the plurality of laser sources (11), and an optical diffraction element (15) on which is incident respective laser lights (1) emitted from the optical fibers (12). The laser processing device (10) moreover comprises a feature in which diffraction lights (2) reflected by the optical diffraction element (15) form an image on an object (101) in substantially the same intensity distribution and at substantially the same focal position.　The present invention thereby provides a laser processing device in which there is used high-output laser light that has been propagated over a long distance by optical fibers.

Description

[Technical field]

[0001] The present invention relates to a laser processing device that uses a laser beam transmitted through an optical fiber. [Background technology]

[0002] Equipment that uses high-power lasers for cutting, drilling, welding, and other processing of metal materials is becoming more and more widespread. This laser processing equipment can concentrate high energy locally and perform processing without contact, making it possible to perform fine processing and suppress thermal effects. In addition, fiber lasers, which have become increasingly high-powered, are being used to improve processing throughput in mass production factories and to process large structural materials.

[0003] In addition to increasing the output of lasers, peripheral technologies to improve the performance of laser processing equipment are also being actively researched and developed. Optical fibers that transmit lasers are now capable of transmitting kilowatt (kW) class lasers over distances of several tens to several hundred meters, enabling work with fewer restrictions on the position of the laser source.

[0004] Regarding the technology for controlling the shape of a laser beam to irradiate the workpiece, there has been active development of technology that uses not only combinations of concave lenses, convex lenses, and prisms, but also diffractive optical elements (DOEs) to increase the freedom of laser irradiation patterns (Patent Document 1).

[0005] DOE laser irradiation pattern technology includes a technology for uniformly irradiating a high-power laser beam over a large area to shorten processing time, and a technology for uniformly distributing the power within the beam at the focal point to improve the efficiency of dismantling large structures and processing composite materials.

[0006] In a laser processing apparatus using this optical diffraction element (DOE), as shown in FIG. 5, laser light emitted from a single high-output laser source 51 is incident on an optical diffraction element 55 via an optical fiber 52, and the reflected (diffracted) light 2 is irradiated onto an object 101 for processing. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2019-203960 A [Non-patent literature]

[0008] [Non-Patent Document 1] https: / / www.ntt.co.jp / journal / 1904 / files / pdf / JN201904all.pdf Summary of the Invention [Problem to be solved by the invention]

[0009] However, when transmitting high-power laser light through an optical fiber, there is a problem that the transmission distance is short, and that bending the optical fiber causes heat generation due to the influence of light leakage at the bent point, which damages the optical fiber, and therefore there is a limit to how far the optical fiber can be bent.

[0010] Furthermore, there is also the problem that the incidence of high-power laser light generates heat in optical components such as a diffractive optical element (DOE), causing positional displacement and resulting in focal shift. [Means for solving the problem]

[0011] In order to solve the above-mentioned problems, a laser processing apparatus according to the present invention includes a light source that emits laser light with a predetermined laser output, an optical fiber connected to the light source, and an optical diffraction element into which the laser light emitted from the optical fiber is incident, the light source includes a plurality of laser sources, the optical fiber is connected to each of the plurality of laser sources, each of the laser lights emitted from the optical fiber is incident on the optical diffraction element, diffracted lights reflected by each of the optical diffraction elements are imaged on an object with substantially the same intensity distribution and substantially the same focal position, the transmission distance of the laser light emitted from one laser source of the plurality of laser sources is longer than that of the laser light emitted from a light source that is composed of a single laser and emits a laser output equivalent to that of the plurality of laser sources. Possible Long compared to the distance The length of the optical fiber is 50 m or more and 300 m or less. Characterized by 。 Effect of the Invention

[0012] According to the present invention, it is possible to provide a laser processing device that uses a high-power laser beam transmitted over a long distance through an optical fiber. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram of a laser processing device according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram of a laser processing device according to a second embodiment of the present invention. [Diagram 3] FIG. 3 is a schematic diagram of a laser processing device according to a third embodiment of the present invention. [Figure 4] FIG. 4 is a schematic diagram showing a transmission type optical diffraction element in the laser processing apparatus according to the first embodiment of the present invention. [Diagram 5] FIG. 5 is a schematic diagram of a conventional laser processing device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] <First embodiment> A first embodiment of the present invention will be described with reference to FIG.

[0015] <Laser processing equipment configuration> FIG. 1 shows a laser processing apparatus 10 according to a first embodiment.

[0016] The laser processing apparatus 10 includes a laser source 11, an optical fiber 12, and a laser head 13.

[0017] The laser source 11 is made up of nine fiber lasers arranged in parallel. The output of each laser source 11 is 1 kW, and the wavelength of the laser light is 1064 to 1070 nm. The size of each laser source 11 is 15 cm x 40 cm on the end face on the emission end side, and the length is 40 cm, and these laser sources are fixed at predetermined positions for use.

[0018] The optical fibers 12 propagate the output of each laser source 11. The length of the optical fibers 12 is 100 m. A collimating lens 14 is mounted on the tip of the optical fiber 12. The collimating lens 14 outputs the output from each optical fiber 12 as a parallel beam.

[0019] The tip of the optical fiber 12 is connected to the laser head 13, and the laser head 13 is equipped with a diffractive optical element (DOE) 15. The laser head 13 has a rectangular parallelepiped shape with each side measuring approximately 10 cm to 20 cm.

[0020] The diffractive optical element (DOE) 15 is of a reflective type and has nine elements corresponding to the number of laser sources. The nine elements reflect the laser light 1 emitted from the nine laser sources via the optical fibers 12, and focus the light on the surface of the object.

[0021] Each optical diffraction element 15 is about 15 mm x 15 mm, and is formed by integration on one substrate. A fine uneven structure is formed on the surface of the optical diffraction element 15. The material of the optical diffraction element 15 (substrate) can be gold, silver, copper, aluminum, silicon carbide, diamond, aluminum nitride, silicon, etc., and a material with good thermal conductivity is preferable.

[0022] Here, the distance from the tip of the optical fiber 12 to the optical diffraction element 15 is about 10 cm, and the distance from the optical diffraction element 15 to the object can be designed arbitrarily by designing the uneven structure of the optical diffraction element; for example, in a laser processing device, the distance is designed to be several tens of centimeters to about 100 cm.

[0023] The laser beam 1 emitted from the tip of the optical fiber 12 is a plane wave whose wavefront is a straight line perpendicular to the traveling direction, and its intensity has a Gaussian distribution. The laser beam 1 is reflected and diffracted by the optical diffraction element 15, and the diffracted light 2 forms an image on the surface of the object 101, thereby processing the object 101.

[0024] At this time, the cross-sectional shape and light intensity distribution of the light beam 3 at the imaging position can be shaped by the uneven structure formed on the surface of each optical diffraction element 15. Hereinafter, the uneven structure includes the uneven shape and the uneven layout (arrangement) of the unevenness.

[0025] In this way, by providing a predetermined uneven structure on the surface of each of the optical diffraction elements 15, each light (diffracted light) 2 diffracted by this uneven structure is imaged in a predetermined pattern on the surface of the object 101. As a result, multiple predetermined patterns are imaged in an overlapping manner. In other words, the uneven structure on the surface of the optical diffraction element 15 can be designed so that an image is formed in a predetermined pattern on the surface of the object 101.

[0026] In this embodiment, the uneven structure on the surface of the optical diffraction element 15 is designed so that each of the nine light beams 2 diffracted by the optical diffraction elements 15 has a uniform intensity distribution in the beam 3 imaged on the surface of the object 101, and is imaged with approximately the same intensity distribution and at approximately the same focal position. Here, the shape of the beam 3 imaged on the surface of the object 101 is a rectangle of approximately 0.2 mm x 0.2 mm or a circle with a diameter of approximately 0.2 mm.

[0027] In the conventional technology, when multiple laser sources and multiple optical components such as lenses and mirrors are used without using an optical diffraction element, the intensity distribution in the beam imaged on the surface of the object 101 becomes non-uniform. As a result, when processing by overlapping multiple beams, it is difficult to focus each beam and increase the light intensity in a specified area.

[0028] On the other hand, according to this embodiment, each beam has a uniform intensity distribution, so that each beam can be easily focused to increase the light intensity in a predetermined area, thereby enabling laser processing to be performed.

[0029] <Effects of laser processing equipment> The effects of the laser processing apparatus 10 according to the present embodiment will be described.

[0030] The transmission distance of a high-power laser through an optical fiber is estimated based on the product of the laser power and distance. For example, if the product of the laser power and distance is 300 km·W, the optical fiber transmission distance of a laser processing device equipped with a single laser source and with an output of 6.3 kW is 300 km·W ÷6.3 kW =47.6m.

[0031] Thus, in a conventional 10 kW class laser processing device, the distance from the laser source to the laser head is limited to at most several tens of meters.

[0032] In addition, when transmitting high-power laser light of about 10 kW through an optical fiber, bending the optical fiber can cause heat generation due to light leakage at the bent point, resulting in damage to the optical fiber, and there are restrictions such as not allowing the bending radius of the optical fiber to be less than a few tens of centimeters.

[0033] On the other hand, in the laser processing device according to the present embodiment, the light source is composed of nine laser sources, and therefore, assuming that each laser source has an output of 1 kW, a total of 9 kW of laser light is emitted. Taking into account the pattern conversion loss (approximately 30%) in the DOE element, the emitted laser light is irradiated onto the target with an output of 6.3 kW. In this case, the transmission distance for one laser is 300 km·W÷1 kW =300m.

[0034] From the above, when the transmission distance of the fiber in the conventional laser processing device is taken into consideration, the fiber of the laser processing device according to the present embodiment is effective when it is 50 m or longer, and a length of 100 m or more and 300 m or less is desirable.

[0035] Furthermore, since the output of the laser light propagating through the optical fiber is about 1 kW, damage caused by heat generation at the bent points of the optical fiber can be suppressed.

[0036] In this way, the laser processing device according to the present embodiment can extend the optical fiber transmission distance, so that the distance from the laser source to the laser head can be extended in a 10 kW output laser processing device. As a result, optical fibers of several hundred meters can be used, the degree of freedom of the bending radius of the optical fiber can be increased, and the risk of the optical fiber breaking due to heat generation caused by optical loss in the optical fiber can be reduced.

[0037] Furthermore, according to the laser processing device of this embodiment, by dividing the output into a plurality of laser sources, even if some components such as optical fibers and DOE elements break down in each path along which the emitted light from, for example, nine laser sources propagates, it is possible to operate the other paths that do not include the broken components. Therefore, the laser processing can be performed while minimizing the decrease in the total laser output. As a result, parts replacement and maintenance can be performed while maintaining the throughput of the laser processing.

[0038] In addition, since the individual laser outputs can be superimposed to produce a desired laser processing output, the laser output can be easily adjusted and maintenance of the laser source, etc. can be performed periodically, enabling highly redundant use.

[0039] As described above, the laser processing device of this embodiment can diffract laser light using an optical diffraction element from multiple laser sources located remotely via optical fiber and a small laser head, and can therefore introduce laser light into enclosed spaces, such as inside abandoned buildings or tanks on ships, to perform laser processing work.

[0040] Furthermore, since the laser processing device according to the present embodiment is small and lightweight, it can be mounted on a robot arm and used to perform laser processing operations by remote control within an enclosed space.

[0041] Furthermore, when a single laser source is used, the incidence of high-power laser light causes optical components such as a diffractive optical element (DOE) to heat up, resulting in misalignment and focus shift. According to the laser processing device of the present embodiment, the output is divided into a plurality of laser sources, so high-power laser light is not incident on optical components such as a diffractive optical element (DOE). As a result, the misalignment of optical components due to heat generation is suppressed, and focus shift is also suppressed.

[0042] Furthermore, in this embodiment, since a material with good thermal conductivity is used for the material of the optical diffraction element (DOE), the influence of heat generation can be further suppressed.

[0043] <Second embodiment> A laser processing device according to a second embodiment of the present invention will be described with reference to Fig. 2. The laser processing device according to this embodiment has substantially the same configuration as the laser processing device according to the first embodiment and achieves substantially the same effects, but the focal position of the diffracted light on the target object is different.

[0044] <Laser processing equipment configuration> FIG. 2 shows a laser processing apparatus 20 according to the second embodiment.

[0045] The laser processing device 20 includes a laser source 21, an optical fiber 22, and a laser head 23. The tip of the optical fiber 22 is connected to the laser head 23, and the laser head 23 includes a diffractive optical element (DOE) 25.

[0046] Here, by providing a predetermined uneven structure on the surface of each of the optical diffraction elements 25, each light (diffracted light) 2 diffracted by this uneven structure is imaged in a predetermined pattern on the surface of the object 101. As a result, a plurality of predetermined patterns are imaged in an overlapping manner. In other words, the uneven structure on the surface of the optical diffraction element 25 can be designed so that an image is formed in a predetermined pattern on the surface of the object 101.

[0047] In this embodiment, the uneven structure on the surface of the optical diffraction element 25 is designed so that the focal points 3 of the beams that form images on the surface of the object 101 for the respective diffracted lights 2 are located over a predetermined depth of the object 101. As a result, the focal points are located at equal intervals over a depth of about 10 mm from the surface of the object 101.

[0048] Thus, in this embodiment, the uneven structure on the surface of the optical diffraction element 25 is designed so that each of the light 2 diffracted by the nine optical diffraction elements 25 is imaged at a predetermined, approximately identical focal position across the depth direction of the object 101, and the beam can also be controlled in the depth direction of the processing plane (depth direction of the object 101).

[0049] In this manner, according to the present embodiment, the focal points of the beams are positioned over a predetermined depth of the object, so that the laser processing can be performed. As a result, the object can be efficiently processed over a predetermined depth, so that a thick-layered structure can be processed (cut) at high speed.

[0050] As described above, the laser processing device according to this embodiment can diffract laser light using an optical diffraction element via an optical fiber and a small laser head from multiple laser sources located remotely, thereby enabling laser processing work to be performed by introducing laser light into enclosed spaces such as inside a furnace or a tank on a ship.

[0051] <Third embodiment> A laser processing device according to a third embodiment of the present invention will be described with reference to Fig. 3. The laser processing device according to this embodiment has substantially the same configuration as the laser processing device according to the first embodiment and achieves substantially the same effects, but differs in that it has a movable stage. Details will be described below.

[0052] <Laser processing equipment configuration> FIG. 3 shows a laser processing apparatus 30 according to a third embodiment.

[0053] The laser processing device 30 includes a laser source 31, an optical fiber 32, a laser head 33, an optical diffraction element 35, and a stage 36 on which an object (workpiece) 101 is placed.

[0054] An object 101 is placed on the stage 36, and by driving the stage 36 electrically or otherwise from the outside in the horizontal directions (x and y directions), the focal position of the beam 3 on the object 101 is moved to process the object 101. Here, the stage may be driven in the vertical direction (z direction).

[0055] The laser beam 1 emitted from the optical fiber is a plane wave whose wavefront is a straight line perpendicular to the traveling direction, and its intensity has a Gaussian distribution. The laser beam is reflected by the optical diffraction element 35 to become diffracted beam 2, which is focused on the surface of the object 101 to process the object 101.

[0056] With the diffracted light thus formed on the object, the stage is driven to move the focal point of the diffraction grating within the object, thereby processing the object.

[0057] Here, by providing a predetermined uneven structure on the surface of each of the optical diffraction elements 35, each light (diffracted light) 2 diffracted by this uneven structure is imaged in a predetermined pattern on the surface of the object 101. As a result, a plurality of predetermined patterns are imaged in an overlapping manner. In other words, the uneven structure on the surface of the optical diffraction element 35 can be designed so that an image of a predetermined pattern is formed on the surface of the object 101. A variety of patterns, such as a circular, rectangular, or ring-shaped pattern, can be formed as the pattern imaged on the surface of the object.

[0058] In this embodiment, the uneven structure of the surface of the optical diffraction element can be designed so that the beams focused on the surface of the object form a plurality of predetermined patterns.

[0059] As described above, in this embodiment, the uneven structure on the surface of the optical diffraction element 15 is designed so that each light diffracted by the optical diffraction element forms an image in a plurality of predetermined patterns (shapes) on the surface of the object.

[0060] In conventional technology, when performing processing by superimposing multiple beams using optical components such as multiple lenses and mirrors for multiple laser sources without using an optical diffraction element, it is necessary to adjust a complex optical system along with a large number of optical components.

[0061] On the other hand, according to this embodiment, each beam has a plurality of predetermined patterns, and therefore, by combining a plurality of predetermined patterns, laser processing can be easily performed with high accuracy of submicrons to several microns.

[0062] As described above, the laser processing apparatus according to this embodiment can perform high-precision laser processing by diffracting laser light from multiple laser sources located remotely via optical fibers and a small laser head using an optical diffraction element.

[0063] In the embodiment of the present invention, a reflective optical diffraction element is used, but as shown in FIG. 4, a transmissive optical diffraction element may also be used.

[0064] In the embodiment of the present invention, nine laser sources are used, but the number is not limited and may be any number. Also, while an example in which nine laser sources are arranged in parallel is shown, the arrangement is not limited thereto, and may be any arrangement in which laser light can be incident on the optical diffraction element via an optical fiber.

[0065] Here, the laser source used in the embodiment of the present invention has a maximum output of 5 kW because the output of a conventional high-power laser, 10 kW, is divided into multiple parts (at least two parts). Also, in consideration of processing objects such as metals and resins, an output of 0.5 kW is required. Therefore, the output of the laser source used in the embodiment of the present invention is preferably 0.5 kW or more and 5 kW or less.

[0066] In the embodiment of the present invention, an example in which nine optical diffraction elements are provided in accordance with the number of laser sources has been shown, but this is not limiting, and multiple optical diffraction elements may be provided. Even if not in accordance with the number of laser sources, multiple laser beams may be incident on one optical diffraction element, or the laser beam may be split and incident on multiple optical diffraction elements.

[0067] In the embodiment of the present invention, an example has been shown in which nine optical diffraction elements are integrated on one substrate, but the present invention is not limited to this, and each optical diffraction element may be arranged without being integrated on a single substrate.

[0068] In the embodiment of the present invention, the structure, dimensions, materials, etc. of each component in the configuration of the laser processing device and the manufacturing method thereof are shown as examples, but the present invention is not limited to these. Anything that can exert the function and effect of the laser processing device may be used. [Industrial Applicability]

[0069] The present invention can be applied to the processing of metals, resins, etc. in the industrial field and the cutting of buildings in the construction field. [Explanation of symbols]

[0070] 10 Laser processing equipment 11 Laser source 12 Optical Fiber 13 Laser Head 14 Collimating lens 15 Optical Diffraction Element

Claims

1. A light source that emits a laser beam with a predetermined laser output; an optical fiber connected to the light source; an optical diffraction element onto which the laser light emitted from the optical fiber is incident, the light source comprises a plurality of laser sources; the optical fiber is connected to each of the plurality of laser sources; The laser light emitted from the optical fiber is incident on the optical diffraction element, the diffracted light reflected by each of the optical diffraction elements forms an image on an object with substantially the same intensity distribution and substantially the same focal position; a transmission distance of a laser beam emitted from one of the plurality of laser sources is longer than a transmission distance of a laser beam emitted from a light source that is composed of a single laser and emits a laser output equivalent to that of the plurality of laser sources; A laser processing device, wherein the length of the optical fiber is 50 m or more and 300 m or less.

2. The output of the laser source is 0.5 kW or more and 5 kW or less.

2. The laser processing apparatus according to claim 1.

3. The uneven structure of the surface of the optical diffraction element is designed so that the intensity distribution in the beam when the diffracted light is imaged on the object is uniform.

3. The laser processing apparatus according to claim 1 or 2.

4. The uneven surface structure of the optical diffraction element is designed so that the focal point of the diffracted light is located over a predetermined depth of the object. The laser processing apparatus according to any one of claims 1 to 3.

5. Equipped with a movable stage, The uneven structure of the surface of the optical diffraction element is designed so that the diffracted light is imaged in a predetermined pattern on the object. The laser processing apparatus according to any one of claims 1 to 4.

6. The optical diffraction element is of a reflective type. The laser processing apparatus according to any one of claims 1 to 5.

7. The laser processing apparatus according to claim 1 , wherein the optical diffraction element is integrated on a single substrate.

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