Ring beam shaping element and laser beam machine

Abstract

To provide a ring beam shaping element that can shape a laser beam into a ring shape at an inexpensive price.SOLUTION: A ring beam shaping element 31s comprises: a first surface that is a flat surface and is one of an incident surface and an emission surface of a laser beam; a second surface that is the other of the incident surface and the emission surface; and an uneven pattern that is formed on the second surface and consists of a plurality of projections 311 and recesses 312 formed in a radial direction at positions at an even angle in a circumferential direction. The uneven pattern includes at least one of a projection pattern in which the height of the uppermost position of the projection 311 from a first surface is gradually increased from a center side toward the outside in a radial direction, and a recess pattern in which the height of the lowermost position of the recess 312 from the first surface is gradually decreased from the center side toward the outside in the radial direction. The uppermost position of the projection 311 and the lowermost position of the recess 312 have an inclined surface therebetween.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a ring beam shaping element and a laser processing machine. [Background technology]

[0002] When cutting or welding sheet metal with a laser processing machine, a laser beam may be shaped into a ring shape using an axicon lens as described in Patent Document 1. In the laser processing machine described in Patent Document 1, a collimating lens converts a diverging laser beam emitted from an optical fiber into a collimated beam, and an axicon lens shapes the collimated laser beam into a ring shape. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-85939 Summary of the Invention [Problem to be solved by the invention]

[0004] Axicon lenses are expensive because they need to be manufactured by polishing glass material, and therefore laser processing machines equipped with axicon lenses are expensive. There is a need for a ring beam shaping element and a laser processing machine that can shape a laser beam into a ring shape inexpensively without using an axicon lens. [Means for solving the problem]

[0005] A first aspect of one or more embodiments provides a ring beam shaping element comprising: a first surface which is one of an entrance surface and an exit surface of a laser beam and is a flat surface; a second surface which is the other of the entrance surface and the exit surface; and an unevenness pattern formed on the second surface, the unevenness pattern consisting of a plurality of convex portions and concave portions formed in a radial direction at positions with equal angles in the circumferential direction, the unevenness pattern including at least one of a first convex portion pattern in which the height of the uppermost positions of the convex portions from the first surface gradually increases as it moves from the center side to the outside in the radial direction, and a first concave portion pattern in which the height of the lowermost positions of the concave portions from the first surface gradually decreases as it moves from the center side to the outside in the radial direction, and the area between the uppermost positions of the convex portions and the lowermost positions of the concave portions forms an inclined surface.

[0006] A second aspect of one or more of the embodiments includes a laser oscillator that emits a laser beam, an optical fiber that transmits the laser beam emitted from the laser oscillator, and a processing head into which a diverging laser beam having a Gaussian beam profile emitted from an emission end of the optical fiber is incident, the processing head includes a collimating lens that converts the diverging laser beam into collimated light, a focusing lens that focuses the collimated laser beam emitted from the collimating lens and irradiates a workpiece with the focused laser beam, and a ring beam shaping element that is disposed at a position between the emission end of the optical fiber and the collimating lens, between the collimating lens and the focusing lens, or on the side of the focusing lens that is closer to the workpiece, and converts the Gaussian beam profile into a ring beam profile, and the ring beam shaping element is disposed at a position between the emission end of the optical fiber and the collimating lens, between the collimating lens and the focusing lens, or on the side of the focusing lens that is closer to the workpiece. The beam shaping element has a first surface which is a flat surface and is one of the entrance surface and exit surface of the laser beam emitted from either the exit end of the optical fiber, the collimator lens, or the focusing lens, a second surface which is the other of the entrance surface and the exit surface, and an unevenness pattern formed on the second surface and consisting of a plurality of convex portions and concave portions formed in the radial direction at positions of equal angles in the circumferential direction, the unevenness pattern including at least one of a first convex portion pattern in which the height from the first surface of the uppermost positions of the convex portions gradually increases as it moves from the center side to the outside in the radial direction, and a first concave portion pattern in which the height from the first surface of the lowermost positions of the concave portions gradually decreases as it moves from the center side to the outside in the radial direction, and the area between the uppermost positions of the convex portions and the lowermost positions of the concave portions is an inclined surface. Effect of the Invention

[0007] According to one or more embodiments of the ring beam shaping element and laser processing machine, a laser beam can be shaped into a ring shape at low cost. [Brief description of the drawings]

[0008] [Figure 1]FIG. 1 is a diagram showing a laser processing machine according to a first embodiment. [Diagram 2] FIG. 2 is a plan view showing the ring beam shaping element according to the first embodiment. [Diagram 3] FIG. 3 is a cross-sectional view showing the ring beam shaping element according to the first embodiment. [Figure 4] FIG. 4 is a diagram showing a Gaussian beam profile of a laser beam incident on the ring beam shaping element according to the first and second embodiments. [Diagram 5] FIG. 5 is a diagram showing a ring-shaped beam profile of a laser beam emitted from the ring beam shaping element according to the first embodiment. [Figure 6] FIG. 6 is a diagram showing ring beams obtained at various positions in the traveling direction of the laser beam from the surface of the workpiece in the laser processing machine according to the first embodiment. [Figure 7] FIG. 7 is a diagram showing the results of a simulation comparing the effects of shaping a laser beam into a ring shape of the ring beam shaping element according to the first embodiment and an axicon lens. [Figure 8] FIG. 8 is a diagram showing a laser processing machine according to the second embodiment. [Figure 9] FIG. 9 is a plan view showing the ring beam shaping element according to the second embodiment. [Figure 10] FIG. 10 is a cross-sectional view showing the ring beam shaping element according to the second embodiment. [Figure 11] FIG. 11 is a diagram showing a ring-shaped beam profile of a laser beam emitted from the ring beam shaping element according to the second embodiment. [Figure 12] FIG. 12 is a diagram comparing the ring-shaped beam profile of a laser beam emitted from the ring beam shaping element according to the first embodiment with the ring-shaped beam profile of a laser beam emitted from the ring beam shaping element according to the second embodiment. [Figure 13] FIG. 13 is a diagram showing a laser processing machine according to the third embodiment. [Figure 14]FIG. 14 is a diagram showing an example of the configuration of a rotation mechanism that rotates the ring beam shaping element in the laser processing machine according to the third embodiment. [Figure 15] FIG. 15 is a diagram showing a beam profile that changes in response to rotation of the ring beam shaping element in the laser processing machine according to the third embodiment. [Figure 16] FIG. 16 is a diagram showing a laser processing machine according to the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the ring beam shaping element and the laser processing machine according to each embodiment will be described with reference to the accompanying drawings.

[0010] First Embodiment FIG. 1 shows a laser processing machine 100 according to the first embodiment. The laser processing machine 100 may be a laser cutting machine that cuts a workpiece W, or may be a laser welding machine that welds the workpiece W. In the former case, the workpiece W is, for example, one metal sheet, and in the latter case, the workpiece W is, for example, two metal sheets. The laser processing machine 100 includes an NC device 10, a laser oscillator 20, and a processing head 30. The laser oscillator 20 and the processing head 30 are connected by an optical fiber 25 that transmits a laser beam emitted from the laser oscillator 20.

[0011] The NC device 10 controls the laser oscillator 20. Typically, the laser oscillator 20 is a fiber laser oscillator. The laser oscillator 20 is not limited to a fiber laser oscillator. The laser processing machine 100 may include a moving mechanism (not shown) for moving the processing head 30. In this case, the NC device 10 controls the moving mechanism to move the processing head 30.

[0012] The processing head 30 has a ring beam shaping element 31s according to the first embodiment, a collimator lens 32, and a focusing lens 33. The optical fiber 25 emits a diverging laser beam from the emission end. The diverging laser beam is incident on the ring beam shaping element 31s. The laser beam incident on the ring beam shaping element 31s has a Gaussian beam profile. The beam profile is a characteristic that indicates the intensity distribution of the laser beam. As described later, the ring beam shaping element 31s shapes the incident laser beam into a ring shape and converts the beam profile into a ring shape.

[0013] The collimator lens 32 converts the laser beam emitted from the ring beam shaping element 31s into collimated light. The focusing lens 33 focuses the collimated laser beam and irradiates the workpiece W with the focused laser beam.

[0014] 1, the ring beam shaping element 31s is disposed between the exit end of the optical fiber 25 and the collimator lens 32, but it may be disposed between the collimator lens 32 and the focusing lens 33. Furthermore, the ring beam shaping element 31s may be disposed closer to the workpiece W than the focusing lens 33. When the ring beam shaping element 31s is disposed between the exit end of the optical fiber 25 and the collimator lens 32, the ring beam shaping element 31s can be made smaller, so it is most preferable to dispose the ring beam shaping element 31s between the exit end of the optical fiber 25 and the collimator lens 32.

[0015] The configuration of the ring beam shaping element 31s will be described in detail with reference to Figs. 2 and 3. Fig. 2 is a plan view of the ring beam shaping element 31s, and Fig. 3 is a cross-sectional view of the ring beam shaping element 31s cut in the diameter direction. In the case where the ring beam shaping element 31s is disposed between the exit end of the optical fiber 25 and the collimator lens 32, the ring beam shaping element 31s can be formed of a circular glass plate such as a highly transparent synthetic quartz plate having a plate thickness of 0.5 mm and a diameter of about 20 mm. In Fig. 1, one of the flat surfaces of the entrance surface and the exit surface of the laser beam in the ring beam shaping element 31s is called the first surface, and the other of the entrance surface and the exit surface is called the second surface. In Fig. 1, the entrance surface of the laser beam is called the first surface which is a flat surface, and the exit surface is called the second surface, but the exit surface may be called the first surface which is a flat surface, and the entrance surface may be called the second surface.

[0016] As shown in Fig. 2 and Fig. 3, a concave-convex pattern is formed on the second surface of the ring beam shaping element 31s, in which a plurality of convex portions 311 and concave portions 312 are arranged in the circumferential direction. The plurality of convex portions 311 and concave portions 312 are formed at equal angular positions in the circumferential direction of the second surface. Each convex portion 311 and each concave portion 312 is formed in the radial direction at each angular position from the center 310. In Fig. 2 and Fig. 3, the convex portions 311 and the concave portions 312 are formed from the center 310 to the end portions in the radial direction, but the convex portions 311 and the concave portions 312 may be formed in a range of 5 mm to 9 mm from the center 310 within a radius of 10 mm.

[0017] The convex portions 311 and the concave portions 312 may be formed in a range from the center 310 side to a predetermined position in the radial direction. The ring beam shaping element 31s shown in Figures 2 and 3 is an example in which the convex portions 311 and the concave portions 312 are formed over the entire range from the center 310 to the ends in the radial direction. In Figure 3, the height of the convex portions 311 and the depth of the concave portions 312 are exaggerated to make it easier to understand the concave-convex pattern.

[0018] In the example shown in FIG. 2, the number of the convex portions 311 and the concave portions 312 formed in the circumferential direction is 24, and the convex portions 311 and the concave portions 312 are formed at positions at an angle of 15 degrees each. The number of the convex portions 311 and the concave portions 312 is not limited to 24. The number of the convex portions 311 and the concave portions 312 may be 6 or more. The height of the straight uppermost position of the convex portions 311 from the first surface increases in order from the center 310 toward the outside in the radial direction. The height of the straight lowermost position of the concave portions 312 from the first surface decreases in order from the center 310 toward the outside in the radial direction. That is, the convex portions 311 are higher toward the outside in the radial direction, and the concave portions 312 are deeper toward the outside in the radial direction. Between the uppermost position of the convex portions 311 and the lowermost position of the concave portions 312, a slope with a single angle is formed.

[0019] 3, the difference in height between the end of convex portion 311 on the side of center 310 and the outermost end in the radial direction is 1.5 μm, and the difference in height between the end of concave portion 312 on the side of center 310 and the outermost end in the radial direction is 1.5 μm. The groove depth, which is the difference between the uppermost position of convex portion 311 and the lowermost position of concave portion 312, is a maximum of 3.0 μm. The position of center 310 in the height direction is preferably located midway between the uppermost position of convex portion 311 and the lowermost position of concave portion 312, as indicated by the dashed dotted line.

[0020] The concave-convex pattern of the ring beam shaping element 31s preferably includes both a first convex pattern in which the uppermost positions of the convex portions 311 become higher as they move radially outward from the center 310, and a first concave pattern in which the lowermost positions of the concave portions 312 become lower as they move radially outward from the center 310. However, the concave-convex pattern of the ring beam shaping element 31s is not limited to including both the first convex pattern and the first concave pattern.

[0021] The ring beam shaping element 31s includes at least a first convex pattern. In this case, the lowermost position of the concave portion 312 may have a constant height in the radial direction. Alternatively, the ring beam shaping element 31s includes at least a first concave pattern. In this case, the uppermost position of the convex portion 311 may have a constant height in the radial direction.

[0022] The ring beam shaping element 31s can be fabricated by utilizing photolithography technology used in semiconductor processes. A photoresist is applied to a circular glass plate, and a pattern corresponding to the concave-convex pattern is formed in the resist by exposing and developing it, and the pattern is transferred to the glass plate by dry etching, thereby fabricating the ring beam shaping element 31s having the concave-convex pattern. A technique called grayscale exposure can be used as the exposure. Grayscale exposure is a technique that can change the resist thickness after development by controlling the light intensity of the exposure.

[0023] The ring beam shaping element 31s, which can be fabricated using photolithography technology, is significantly less expensive than an axicon lens, which must be fabricated by polishing a glass material. Therefore, the laser processing machine 100 equipped with the ring beam shaping element 31s is less expensive than a configuration equipped with an axicon lens.

[0024] The laser beam emitted from the exit end of the optical fiber 25 and incident on the ring beam shaping element 31s has a Gaussian beam profile as shown in Fig. 4. In the area surrounded by the dashed line, the relative intensity of the laser beam is circular with the largest at the center. The Gaussian laser beam incident on the ring beam shaping element 31s is refracted by the circumferential inclination of the uneven pattern, and the angle of the traveling direction is corrected to the outside in the radial direction. Therefore, the laser beam incident on the ring beam shaping element 31s is shaped into a ring shape, and the beam profile of the laser beam emitted from the ring beam shaping element 31s becomes a ring shape as shown in Fig. 5.

[0025] The beam profiles shown in FIGS. 4 and 5 can be measured by a profiler disposed at the position of the workpiece W in FIG.

[0026] 5, the ring beam generated by the ring beam shaping element 31s includes an outer ring-shaped beam Brr and a central beam Brc located at the center of the outer ring-shaped beam Brr in the area surrounded by a dashed line. The reason why the central beam Brc with a high relative intensity is generated at the center of the ring beam generated by the ring beam shaping element 31s is that near the center 310 of the ring beam shaping element 31s, the convex portion 311 is low and the concave portion 312 is shallow, so that the effects of refraction and angle correction due to the concave-convex pattern are weak.

[0027] For example, when the laser processing machine 100 is a laser cutting machine, when the workpiece W has a large thickness, cutting with a ring-shaped laser beam improves the cutting speed and cutting quality compared to cutting with a Gaussian-shaped laser beam. The ring beam generated by the ring beam shaping element 31s has a central beam Brc, but this does not have a significant effect on the effect of improving the cutting speed and cutting quality.

[0028] Assume that the core diameter of the optical fiber 25 is 100 μm, the beam parameter product (BPP) indicating the beam quality is 3.7 mm mrad, the focal position of the collimator lens 32 is 100 mm, and the focal position of the focusing lens 33 is 150 mm. Assume that the ring beam shaping element 31s is disposed at a position 50 mm from the exit end of the optical fiber 25. The surface of the workpiece W is taken as the focal position (0 mm), and a ring beam having a shape as shown in FIG. 6 is obtained at positions 0 mm, +4 mm, and +10 mm from the surface of the workpiece W in the traveling direction of the laser beam. As a result of verification by the inventor, it has been confirmed that the ring beam is maintained within a range of +10 mm or more from the focal position.

[0029] Since the ring beam shaping element 31s has a shape that is symmetrical about the center 310, the concave-convex pattern does not change in the circumferential direction, but changes only depending on the distance from the center 310 in the radial direction. In Fig. 1, the center 310 of the ring beam shaping element 31s preferably coincides with the optical axis of the laser beam. Through verification by the present inventor, it has been confirmed that the allowable deviation of the center 310 from the optical axis of the laser beam is ±0.3 mm, and that it is preferable that the center 310 is located within ±0.3 mm from the optical axis of the laser beam.

[0030] As described above, the ring beam shaping element 31s can be manufactured more inexpensively than an axicon lens, so the laser beam can be shaped into a ring shape inexpensively. The laser processing machine 100 includes the inexpensive ring beam shaping element 31s without using an axicon lens, so the laser beam can be shaped into a ring shape inexpensively. The laser processing machine 100 can generate a ring beam simply by disposing the ring beam shaping element 31s in the processing head 30, so the processing head 30 does not become large.

[0031] FIG. 7 shows the results of a simulation comparing the effect of the ring beam shaping element 31s and the axicon lens in shaping a laser beam into a ring shape. The ring beam shaping element 31s or the axicon lens is placed at a position 50 mm from the exit end of the optical fiber 25. As shown in FIG. 7, whether the ring beam shaping element 31s or the axicon lens is used, the ring beam is maintained in the range from the focal position (0 mm) to +20 mm. However, when the axicon lens is used, it can be seen that the width of the ring beam increases with distance from the focal position, and the ring shape becomes blurred. When the ring beam shaping element 31s is used, it can be seen that the width of the ring beam does not increase much even when it is far from the focal position, and the ring shape is maintained.

[0032] Therefore, when the ring beam shaping element 31s is used rather than the axicon lens, it is expected that the cutting quality will be improved when cutting a thick workpiece W.

[0033] <Second embodiment> FIG. 8 shows a laser processing machine 200 according to the second embodiment. In FIG. 8, the same parts as those in FIG. 1 are given the same reference numerals, and the description thereof will be omitted. The processing head 30 in the laser processing machine 200 is provided with a ring beam shaping element 31w instead of the ring beam shaping element 31s. FIG. 9 is a plan view of the ring beam shaping element 31w, and FIG. 10 is a cross-sectional view of the ring beam shaping element 31w cut in the diameter direction. The definitions of the first and second surfaces in the ring beam shaping element 31w are the same as the definitions of the first and second surfaces in the ring beam shaping element 31s.

[0034] 9 and 10, the ring beam shaping element 31w has an outer circumferential portion 31wo and an inner circumferential portion 31wi on the second surface. The inner circumferential portion 31wi is a region from the center 310 to a predetermined position in the radial direction, and the outer circumferential portion 31wo is a region radially outward of the inner circumferential portion 31wi.

[0035] As shown in Fig. 9, an outer peripheral concave-convex pattern is formed on the outer peripheral portion 31wo of the second surface of the ring beam shaping element 31w, in which a plurality of convex portions 311 (first convex portions) and concave portions 312 (first concave portions) are arranged in the circumferential direction. In the example shown in Fig. 9, the number of convex portions 311 and concave portions 312 formed in the circumferential direction is 36, and the convex portions 311 and concave portions 312 are formed at positions at an angle of 10 degrees each. The number of convex portions 311 and concave portions 312 is not limited to 36. When the end portion of the uppermost position of the convex portion 311 on the inner peripheral portion 31wi side and the end portion of the lowermost position of the concave portion 312 on the inner peripheral portion 31wi side are extended, the uppermost positions of all the convex portions 311 and the lowermost positions of the concave portions 312 are gathered at the center 310.

[0036] Similar to the ring beam shaping element 31s, the height of the uppermost position of the convex portion 311 from the first surface gradually increases from the end on the inner circumferential portion 31wi side toward the outside in the radial direction. The height of the lowermost position of the concave portion 312 from the first surface gradually decreases from the end on the inner circumferential portion 31wi side toward the outside in the radial direction. Between the uppermost position of the convex portion 311 and the lowermost position of the concave portion 312, an inclined surface with a single angle is formed.

[0037] An inner peripheral concave-convex pattern is formed on the inner peripheral portion 31wi of the second surface of the ring beam shaping element 31w, in which a plurality of convex portions 313 (second convex portions) and concave portions 314 (second concave portions) are arranged in the circumferential direction. In the example shown in FIG. 9, the number of convex portions 313 and concave portions 314 formed in the circumferential direction is 12, and the convex portions 313 and concave portions 314 are formed at angular positions of 30 degrees each. The convex portions 313 and concave portions 314 are formed in the radial direction at each angular position from the center 310. The number of convex portions 313 and concave portions 314 is not limited to 12. The number of convex portions 313 and concave portions 314 may be 6 or more. The number of convex portions 311 and concave portions 312 may be greater than the number of convex portions 313 and concave portions 314. Each of the projections 313 and recesses 314 is positioned at the same angle as one of the three projections 311 and recesses 312 that are in the range of an angle of 30 degrees.

[0038] The number of protrusions 313 and recesses 314 on the inner circumferential portion 31wi may be smaller than the number of protrusions 311 and recesses 312 on the outer circumferential portion 31wo. The circumferential period of the protrusions 313 and recesses 314 on the inner circumferential portion 31wi is longer than the circumferential period of the protrusions 311 and recesses 312 on the outer circumferential portion 31wo.

[0039] The height of the linear uppermost position of the convex portion 313 from the first surface increases from the center 310 toward the outside in the radial direction. The height of the linear lowermost position of the concave portion 314 from the first surface decreases from the end portion on the center 310 side toward the outside in the radial direction. The inclination angle of the uppermost position of the convex portion 313 is larger than the inclination angle of the uppermost position of the convex portion 311, and the inclination angle of the lowermost position of the concave portion 314 is larger than the inclination angle of the lowermost position of the concave portion 312. The uppermost position of the end portion of the convex portion 313 on the outer circumferential portion 31wo side is higher from the first surface than the uppermost position of the end portion of the convex portion 311 on the inner circumferential portion 31wi side. The lowermost position of the end portion of the concave portion 314 on the outer circumferential portion 31wo side is lower from the first surface than the lowermost position of the end portion of the concave portion 312 on the inner circumferential portion 31wi side.

[0040] There is an inclined surface with a single angle between the uppermost position of convex portion 313 and the lowermost position of concave portion 314. The inclination angle of the inclined surface between the uppermost position of convex portion 313 and the lowermost position of concave portion 314 is the same as the inclination angle of the inclined surface between the uppermost position of convex portion 311 and the lowermost position of concave portion 312.

[0041] The outer circumferential uneven pattern preferably includes both a second convex pattern in which the uppermost positions of the convex portions 311 become higher from the end on the inner circumferential portion 31wi side toward the outside in the radial direction, and a second concave pattern in which the lowermost positions of the concave portions 312 become lower from the end on the inner circumferential portion 31wi side toward the outside in the radial direction. The inner circumferential uneven pattern preferably includes both a third convex pattern in which the uppermost positions of the convex portions 313 become higher from the center 310 toward the outside in the radial direction, and a third concave pattern in which the lowermost positions of the concave portions 314 become lower from the center 310 toward the outside in the radial direction.

[0042] However, the outer circumferential uneven pattern of the ring beam shaping element 31w is not limited to including both the second convex pattern and the second concave pattern, and the inner circumferential uneven pattern is not limited to including both the third convex pattern and the third concave pattern.

[0043] The outer circumferential uneven pattern includes at least a second convex pattern. In this case, the lowest position of the concave portion 312 may be at a constant height in the radial direction. Alternatively, the outer circumferential uneven pattern includes at least a second concave pattern. In this case, the highest position of the convex portion 311 may be at a constant height in the radial direction. The inner circumferential uneven pattern includes at least a third convex pattern. In this case, the lowest position of the concave portion 314 may be at a constant height in the radial direction. Alternatively, the inner circumferential uneven pattern includes at least a third concave pattern. In this case, the highest position of the convex portion 313 may be at a constant height in the radial direction. If the outer circumferential uneven pattern includes a second convex pattern, the inner circumferential uneven pattern includes a third convex pattern. If the outer circumferential uneven pattern includes a second concave pattern, the inner circumferential uneven pattern includes a third concave pattern.

[0044] Like the ring beam shaping element 31s, the ring beam shaping element 31w can be fabricated by utilizing photolithography techniques used in semiconductor processes.

[0045] As shown in Fig. 11, the ring beam generated by the ring beam shaping element 31w includes an outer ring-shaped beam Brr and a central beam Brc' located at the center of the outer ring-shaped beam Brr in the area surrounded by a dashed line. Fig. 12 shows a beam profile obtained when the ring beam shaping element 31s shown in Fig. 5 is used and a beam profile obtained when the ring beam shaping element 31w shown in Fig. 11 is used, superimposed on each other. Since the ring beam shaping element 31w has an inner peripheral portion 31wi, the relative intensity of the central beam Brc' is significantly smaller than that of the central beam Brc when the ring beam shaping element 31s is used.

[0046] As in the first embodiment, the ring beam shaping element 31w has an axially symmetric shape with the center 310 as the axis, and therefore, in Fig. 8, the center 310 of the ring beam shaping element 31w preferably coincides with the optical axis of the laser beam. The allowable deviation of the center 310 from the optical axis of the laser beam is ±0.3 mm, and the center 310 is preferably located within ±0.3 mm from the optical axis of the laser beam.

[0047] As described above, the ring beam shaping element 31w can be manufactured more inexpensively than an axicon lens, so that the laser beam can be shaped into a ring shape inexpensively. The laser processing machine 200 includes the inexpensive ring beam shaping element 31w without using an axicon lens, so that the laser beam can be shaped into a ring shape inexpensively. The ring beam shaping element 31w includes the inner peripheral portion 31wi having the convex portion 313 and the concave portion 314 with a large inclination angle from the center 310 toward the outer peripheral portion 31wo side, so that a ring beam with a small relative intensity of the central beam Brc' can be generated. The processing head 30 of the laser processing machine 200 does not become large in size either.

[0048] The ring beam shaping element 31w has two regions on its second surface divided radially into an outer peripheral portion 31wo and an inner peripheral portion 31wi, but it is also possible to provide three or more regions divided radially on the second surface and form an uneven pattern consisting of convex and concave portions in each region.

[0049] <Third embodiment> FIG. 13 shows a laser processing machine 300 according to a third embodiment. In FIG. 13, the same parts as those in FIG. 1 are given the same reference numerals, and their description will be omitted. The processing head 30 in the laser processing machine 300 is provided with ring beam shaping elements 31s1 and 31s2 instead of the ring beam shaping element 31s. The ring beam shaping elements 31s1 and 31s2 have the same shape as the ring beam shaping element 31s shown in FIG. 2 and FIG. 3. That is, the laser processing machine 300 is provided with two ring beam shaping elements 31s.

[0050] The ring beam shaping elements 31s1 and 31s2 are arranged in the processing head 30 so that the second surfaces on which the convex portion 311 and the concave portion 312 are formed face each other. In the ring beam shaping element 31s2, the incident surface of the laser beam is the second surface, and the exit surface is the first surface which is a flat surface. The ring beam shaping element 31s1 and the ring beam shaping element 31s2 are preferably as close to each other as possible within a range in which the ring beam shaping element 31s2 can rotate. Through verification by the present inventor, it has been confirmed that the interval between the ring beam shaping element 31s1 and the ring beam shaping element 31s2 is preferably 1.5 mm or less.

[0051] The laser processing machine 300 includes a rotation drive unit 40 that drives, for example, the ring beam shaping element 31s2 of the ring beam shaping elements 31s1 and 31s2 to rotate in a plane perpendicular to the optical axis. The ring beam shaping element 31s1 has a fixed rotation direction and a fixed position in the optical axis direction, and the ring beam shaping element 31s2 has a fixed position in the optical axis direction. The ring beam shaping element 31s1 may be rotatable, and the rotation drive unit 40 may drive the ring beam shaping element 31s1 to rotate.

[0052] 14, the rotation drive unit 40 can be configured by, for example, a motor 40M. As an example, a gear 34 is provided around the ring beam shaping element 31s2, and the ring beam shaping element 31s2 can be rotated by rotating a gear 35 meshing with the gear 34 by the motor 40M. The ring beam shaping element 31s2 provided with the gear 34 may be positioned by a predetermined positioning mechanism.

[0053] Fig. 15 shows a beam profile that changes in response to the rotation of the ring beam shaping element 31s2. Fig. 15 shows an example in which the number of convex portions 311 and concave portions 312 of the ring beam shaping elements 31s1 and 31s2 is 24. The state in which the uppermost position of the convex portion 311 of the ring beam shaping element 31s1 and the lowermost position of the concave portion 312 of the ring beam shaping element 31s2 exactly face each other is defined as the angle of the ring beam shaping element 31s2 with respect to the ring beam shaping element 31s1 being 0 degrees.

[0054] When the angle of the ring beam shaping element 31s2 with respect to the ring beam shaping element 31s1 is 0 degrees, the action of the ring beam shaping element 31s1 and the action of the ring beam shaping element 31s2 cancel each other out. Therefore, the ring beam shaping elements 31s1 and 31s2 are equivalent to two flat glass plates on which the convex portion 311 and the concave portion 312 are not formed. Therefore, as shown in FIG. 15, when the angle of the ring beam shaping element 31s2 is 0 degrees, the beam profile is not ring-shaped at any focal position between +0 mm and +12 mm. The beam profile is Gaussian-shaped or top-hat-shaped.

[0055] When the angle of the ring beam shaping element 31s2 with respect to the ring beam shaping element 31s1 is 15 degrees, the uppermost position of the convex portion 311 of the ring beam shaping element 31s1 and the uppermost position of the convex portion 311 of the ring beam shaping element 31s2 are exactly opposite to each other. Therefore, the action of the ring beam shaping element 31s1 and the action of the ring beam shaping element 31s2 act so as to overlap each other, so that a ring beam with an enhanced ring beam shown in Fig. 5 is generated. In the example shown in Fig. 15, the beam profile is ring-shaped at each focal position from +4 mm to +12 mm.

[0056] When the angle of the ring beam shaping element 31s2 with respect to the ring beam shaping element 31s1 is 7.5 degrees, a beam profile can be obtained that is intermediate between the beam profile when the angle is 0 degrees and the beam profile when the angle is 15 degrees.

[0057] According to the laser processing machine 300, various beam profiles can be selected by changing the angle of the ring beam shaping element 31s2 relative to the ring beam shaping element 31s1. When the workpiece W has a thin thickness, the laser processing machine 300 cuts the workpiece W with a Gaussian laser beam, and when the workpiece W has a thick thickness, the laser processing machine 300 cuts the workpiece W with a ring laser beam.

[0058] <Fourth embodiment> FIG. 16 shows a laser processing machine 400 according to a fourth embodiment. In FIG. 16, the same parts as those in FIG. 13 are given the same reference numerals, and the description thereof will be omitted. The processing head 30 in the laser processing machine 400 is provided with ring beam shaping elements 31w1 and 31w2 instead of the ring beam shaping elements 31s1 and 31s2 provided in the processing head 30 in the laser processing machine 300. The ring beam shaping elements 31w1 and 31w2 have the same shape as the ring beam shaping element 31w shown in FIG. 9 and FIG. 10. That is, the laser processing machine 400 is provided with two ring beam shaping elements 31w.

[0059] The ring beam shaping elements 31w1 and 31w2 are disposed in the processing head 30 so that the second surfaces on which the convex portions 311 and 313 and the concave portions 312 and 314 are formed face each other. In the laser processing machine 400 as well, the ring beam shaping elements 31w1 and 31w2 are preferably spaced apart by 1.5 mm or less.

[0060] The rotation drive unit 40 drives, for example, the ring beam shaping element 31w2 of the ring beam shaping elements 31w1 and 31w2 to rotate. The ring beam shaping element 31w1 has a fixed rotation direction and a fixed position in the optical axis direction, and the ring beam shaping element 31w2 has a fixed position in the optical axis direction. The ring beam shaping element 31w1 may be rotatable, and the rotation drive unit 40 may drive the ring beam shaping element 31w1 to rotate. The configuration in which the rotation drive unit 40 rotates the ring beam shaping element 31w1 may be the same as that shown in FIG. 14.

[0061] 9 and 10, the number (first number) of the convex portions 311 and the concave portions 312 of the ring beam shaping elements 31w1 and 31w2 is 36, and the number (second number) of the convex portions 313 and the concave portions 314 of the ring beam shaping element 31w2 is 12. In the laser processing machine 400, the angle at which the uppermost positions of the convex portions 311 and 313 of the ring beam shaping element 31w1 exactly face the lowermost positions of the concave portions 312 and 314 of the ring beam shaping element 31w2 is defined as 0 degrees. By setting the angle of the ring beam shaping element 31w2 with respect to the ring beam shaping element 31w1 to 0 degrees, the beam profile can be made Gaussian type or top hat type.

[0062] When the angle of the ring beam shaping element 31w2 with respect to the ring beam shaping element 31w1 is 30 degrees, the uppermost positions of the convex portions 311 and 313 of the ring beam shaping element 31w1 exactly face the uppermost positions of the convex portions 311 and 313 of the ring beam shaping element 31w2. Therefore, the action of the ring beam shaping element 31w1 and the action of the ring beam shaping element 31w2 act so as to overlap each other, so that a ring beam with an emphasized ring beam shown in FIG.

[0063] An intermediate beam profile can be obtained by setting the angle of the ring beam shaping element 31w2 relative to the ring beam shaping element 31w1 to any angle between 0 degrees and 30 degrees.

[0064] In the laser processing machine 400, if the ratio of the number of convex portions 311 and concave portions 312 on the outer circumferential portion 31wo to the number of convex portions 313 and concave portions 314 on the inner circumferential portion 31wi is an odd number such as 3:1, a beam profile of only the center beam Brc' can be obtained. The beam profile of only the center beam Brc' is preferably used when the thickness of the workpiece W is thin.

[0065] According to the laser processing machine 400, various beam profiles can be selected by changing the angle of the ring beam shaping element 31w2 relative to the ring beam shaping element 31w1. According to the laser processing machine 400, since the ring beam shaping elements 31w1 and 31w2 can generate a ring beam with a small relative intensity of the center beam Brc', it is possible to generate a ring beam in which the ring beam with a small relative intensity of the center beam Brc' is emphasized.

[0066] The present invention is not limited to one or more of the embodiments described above, and various modifications can be made without departing from the gist of the present invention. [Explanation of symbols]

[0067] 10 NC device 20 Laser Oscillator 25 Optical Fiber 30 Processing head 31s, 31s1, 31s2, 31w, 31w1, 31w2 Ring beam shaping element 31wi inner circumference 31wo outer circumference 32 Collimating Lens 33 Focusing Lens 40 Rotation drive unit 310 center 311,313 Convex 312,314 Recess W Work material

Claims

1. a first surface which is one of an incidence surface and an emission surface of the laser beam and is a flat surface; a second surface which is the other of the entrance surface and the exit surface; a concave-convex pattern formed on the second surface, the concave-convex pattern being formed in a radial direction at positions spaced at equal angles in a circumferential direction; Equipped with The concave-convex pattern includes at least one of a first convex pattern in which the height of the uppermost positions of the convex portions from the first surface gradually increases from the center side toward the outside in the radial direction, and a first concave pattern in which the height of the lowermost positions of the concave portions from the first surface gradually decreases from the center side toward the outside in the radial direction, and an inclined surface is formed between the uppermost positions of the convex portions and the lowermost positions of the concave portions. Ring beam shaping element.

2. The ring beam shaping element according to claim 1 , wherein the concave-convex pattern includes both the first convex pattern and the first concave pattern.

3. 3. The ring beam shaping element according to claim 1, wherein the convex portion and the concave portion are formed in a range from the center to a predetermined position in the radial direction.

4. the second surface has an inner circumferential portion which is a region from the center to a predetermined position in the radial direction, and an outer circumferential portion which is a region outside the inner circumferential portion in the radial direction, the outer circumferential portion has an outer circumferential concave-convex pattern including a first number of first convex portions and first concave portions formed in the radial direction at positions spaced at equal angles in the circumferential direction, the inner circumferential portion has an inner circumferential concave-convex pattern including a second number of second convex portions and second concave portions, the second number being less than the first number, formed in the radial direction at positions spaced at equal angles in the circumferential direction; The outer circumferential uneven pattern is a second convex portion pattern in which the height of an uppermost position of the first convex portion from the first surface gradually increases from the end portion on the inner circumferential portion side toward the outside in the radial direction, and a second concave portion pattern in which the height of a lowermost position of the first concave portion from the first surface gradually decreases from the end portion on the inner circumferential portion side toward the outside in the radial direction, a slope is formed between the uppermost position of the first protrusion and the lowermost position of the first recess, The inner peripheral uneven pattern is If the outer circumferential uneven pattern includes the second convex pattern, the uppermost positions of the second convex portions include a third convex pattern in which the height from the first surface gradually increases from the center toward the outside in the radial direction, and if the outer circumferential uneven pattern includes the second concave pattern, the lowermost positions of the second concave portions include a third concave pattern in which the height from the first surface gradually decreases from the center toward the outside in the radial direction, an uppermost position of an end portion on the outer periphery side of the second convex portion is higher in height from the first surface than an uppermost position of an end portion on the inner periphery side of the first convex portion, and a lowermost position of an end portion on the outer periphery side of the second concave portion is lower in height from the first surface than a lowermost position of an end portion on the inner periphery side of the first concave portion; An inclined surface is formed between the uppermost position of the second protrusion and the lowermost position of the second recess.

2. The ring beam shaping element according to claim 1.

5. the outer circumferential concave-convex pattern includes both the second convex pattern and the second concave pattern, The inner peripheral concave-convex pattern includes both the third convex pattern and the third concave pattern. The ring beam shaping element according to claim 4 .

6. a laser oscillator that emits a laser beam; an optical fiber for transmitting a laser beam emitted from the laser oscillator; a processing head into which a diverging laser beam having a Gaussian beam profile emitted from an exit end of the optical fiber is incident; Equipped with The processing head includes: a collimating lens for converting the diverging laser beam into collimated light; a focusing lens that focuses the collimated laser beam emitted from the collimating lens and irradiates the focused laser beam onto a workpiece; a ring beam shaping element that is disposed at a position between the exit end of the optical fiber and the collimator lens, between the collimator lens and the focusing lens, or on the workpiece side of the focusing lens, and that converts the Gaussian beam profile into a ring beam profile; having The ring beam shaping element is a first surface which is one of an incident surface and an exit surface of a laser beam emitted from the exit end of the optical fiber, the collimator lens, or the focusing lens, and which is a flat surface; a second surface which is the other of the entrance surface and the exit surface; a concave-convex pattern formed on the second surface, the concave-convex pattern being formed in a radial direction at positions spaced at equal angles in a circumferential direction; having The concave-convex pattern includes at least one of a first convex pattern in which the height of the uppermost positions of the convex portions from the first surface gradually increases from the center side toward the outside in the radial direction, and a first concave pattern in which the height of the lowermost positions of the concave portions from the first surface gradually decreases from the center side toward the outside in the radial direction, and an inclined surface is formed between the uppermost positions of the convex portions and the lowermost positions of the concave portions. Laser processing machine.

7. The laser processing machine according to claim 6 , wherein the concave-convex pattern includes both the first convex pattern and the first concave pattern.

8. 8. The laser processing machine according to claim 6, wherein the convex portion and the concave portion are formed in a range from the center to a predetermined position in the radial direction.

9. the second surface has an inner circumferential portion which is a region from the center to a predetermined position in the radial direction, and an outer circumferential portion which is a region outside the inner circumferential portion in the radial direction, the outer circumferential portion has an outer circumferential concave-convex pattern including a first number of first convex portions and first concave portions formed in the radial direction at positions spaced at equal angles in the circumferential direction, the inner circumferential portion has an inner circumferential concave-convex pattern including a second number of second convex portions and second concave portions, the second number being less than the first number, formed in the radial direction at positions spaced at equal angles in the circumferential direction; The outer circumferential uneven pattern is a second convex portion pattern in which the height of an uppermost position of the first convex portion from the first surface gradually increases from the end portion on the inner circumferential portion side toward the outside in the radial direction, and a second concave portion pattern in which the height of a lowermost position of the first concave portion from the first surface gradually decreases from the end portion on the inner circumferential portion side toward the outside in the radial direction, a slope is formed between the uppermost position of the first protrusion and the lowermost position of the first recess, The inner peripheral uneven pattern is If the outer circumferential uneven pattern includes the second convex pattern, the uppermost positions of the second convex portions include a third convex pattern in which the height from the first surface gradually increases from the center toward the outside in the radial direction, and if the outer circumferential uneven pattern includes the second concave pattern, the lowermost positions of the second concave portions include a third concave pattern in which the height from the first surface gradually decreases from the center toward the outside in the radial direction, an uppermost position of an end portion on the outer periphery side of the second convex portion is higher in height from the first surface than an uppermost position of an end portion on the inner periphery side of the first convex portion, and a lowermost position of an end portion on the outer periphery side of the second concave portion is lower in height from the first surface than a lowermost position of an end portion on the inner periphery side of the first concave portion; An inclined surface is formed between the uppermost position of the second protrusion and the lowermost position of the second recess.

7. The laser processing machine according to claim 6.

10. the outer circumferential concave-convex pattern includes both the second convex pattern and the second concave pattern, The inner peripheral concave-convex pattern includes both the third convex pattern and the third concave pattern. The laser processing machine according to claim 9.

11. the processing head has two of the ring beam shaping elements arranged closely to each other with the second surfaces facing each other, The laser processing machine further includes a rotation drive unit that drives one of the two ring beam shaping elements to rotate in a plane perpendicular to the optical axis.

11. The laser processing machine according to claim 6, 7, 9 or 10.

12. a ratio of the number of the first protrusions and the first recesses to the number of the second protrusions and the second recesses is an odd number to an odd number; the processing head has two of the ring beam shaping elements arranged closely to each other with the second surfaces facing each other, The laser processing machine further includes a rotation drive unit that drives one of the two ring beam shaping elements to rotate in a plane perpendicular to the optical axis. The laser processing machine according to claim 9 or 10.

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