Laser beam synthesis apparatus and synthesis method

Abstract

The present invention provides a laser beam synthesis apparatus and synthesis method that can synthesize a larger number of laser beams while suppressing an increase in the size of the apparatus. [Solution] The laser beam synthesis device 1 includes a synthesis optical system 4 and a primary mirror 5. The synthesis optical system 4 synthesizes a first laser beam group L1, which includes multiple annular laser beams of different diameters with their exit axes on a common first axis AX1, and a second laser beam L2, which is emitted on a second axis AX2 different from the first axis AX1. The primary mirror 5 focuses the first laser beam group L1 and the second laser beam L2 toward a target. The synthesis optical system 4 causes the first laser beam group L1 to be incident on a first position P1 of the primary mirror 5, and causes the second laser beam L2 to be incident on a second position P2 different from the first position P1.

Description

Technical Field

[0001] The present disclosure relates to a laser beam combining apparatus and a combining method for combining a plurality of laser beams to generate a high-power laser beam.

Background Art

[0002] As a method for obtaining a high-power laser beam, there is a method of combining a plurality of laser beams to generate one laser beam. Patent Document 1 discloses a laser beam combining apparatus that arranges a plurality of annular laser beams having different diameters coaxially.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order to obtain a higher-power combined laser beam, it is necessary to combine a larger number of laser beams. In the laser beam combining apparatus of Patent Document 1, as the number of laser beams to be combined increases, the diameter of the annular laser beam arranged on the outer side in the radial direction increases. In this case, the size of the optical element constituting the irradiation optical system of the laser beam has to be increased. For this reason, not only does the combining apparatus become larger, but the manufacturing difficulty of the optical element increases to ensure the required optical performance, resulting in an increase in cost.

[0005] An object of the present disclosure is to provide a laser beam combining apparatus and a combining method capable of combining a larger number of laser beams while suppressing an increase in the size of the apparatus.

Means for Solving the Problems

[0006] A laser beam synthesis apparatus according to one aspect of the present disclosure includes: a first laser beam generator that emits a first laser beam group including a plurality of annular-shaped laser beams of different diameters whose emission axes lie on a common first axis; a second laser beam generator that emits a second laser beam on a second axis different from the first axis; an optical element disposed downstream of the first laser beam generator and the second laser beam generator in the optical path from which the first laser beam group and the second laser beam are emitted, and which focuses the first laser beam group and the second laser beam toward a target; and a synthesis optical system that causes the first laser beam group to be incident on a first position of the optical element and the second laser beam to be incident on a second position of the optical element different from the first position.

[0007] A laser beam synthesis method relating to another aspect of the present disclosure involves generating a first group of laser beams including multiple annular-shaped laser beams of different diameters whose emission axes lie on a common first axis; generating a second laser beam that emits on a second axis different from the first axis; and injecting the first group of laser beams into a first position of an optical element having the function of focusing multiple laser beams toward a target, and injecting the second laser beam into a second position different from the first position. [Effects of the Invention]

[0008] According to this disclosure, it is possible to provide a laser beam synthesis apparatus and synthesis method that can synthesize a larger number of laser beams while suppressing an increase in the size of the apparatus. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a block diagram showing the configuration of a laser beam synthesis apparatus according to an embodiment of this disclosure. [Figure 2] Figure 2 shows an example of a synthesized laser beam generated by the laser beam synthesis apparatus of this embodiment. [Figure 3] Figure 3 shows an example of a synthesized laser beam generated by the laser beam synthesis apparatus of this embodiment. [Figure 4]Figure 4 is an optical path diagram showing the first example of a composite optical system using a single scraper mirror. [Figure 5] Figure 5 is a schematic diagram showing the composite optical system of Figure 4 in three dimensions. [Figure 6] Figure 6 is an optical path diagram showing a second example of a composite optical system using two scraper mirrors. [Figure 7] Figure 7 is a schematic diagram showing the composite optical system of Figure 6 in three dimensions. [Figure 8] Figure 8 shows an optical path diagram illustrating a third example of a composite optical system using a beam rotation device, with a perspective view of the beam rotation device added. [Figure 9] Figure 9 is an optical path diagram showing a fourth example of a composite optical system using a beam rotation device. [Figure 10] Figure 10 is a three-dimensional optical path diagram of the composite optical system in Figure 8, with the laser beam incidence added. [Figure 11] Figure 11 is an optical path diagram showing the fifth example of a composite optical system using polygonal pyramidal mirrors. [Figure 12] Figure 12 shows the overall structure of the composite optical system shown in Figure 11. [Figure 13] Figure 13 shows a modified example of a synthesized laser beam. [Modes for carrying out the invention]

[0010] Embodiments of this disclosure will be described in detail below with reference to the drawings. To increase the power of a laser beam, it is effective to combine multiple laser beams to produce a single composite laser beam. However, the size of the apparatus tends to increase as the number of laser beams to be combined increases. The laser beam combining apparatus and method of this disclosure involve injecting the laser beams to be combined from different optical axes into an optical element that has the function of focusing the laser beam toward the irradiation target. By adopting this configuration, it is possible to generate a high-power composite laser beam while suppressing the increase in size of the apparatus. The combining apparatus and method of this disclosure can be applied to equipment in various technical fields that require high-power laser beams.

[0011] [Overall Configuration of Laser Beam Combining Device] FIG. 1 is a block diagram showing the configuration of a laser beam combining device 1 according to an embodiment of the present disclosure. The laser beam combining device 1 includes a first laser beam generator 2, a second laser beam generator 3, a combining optical system 4, and a main mirror 5 as an optical element. The laser beam combining device 1 irradiates a combined laser beam LM onto an irradiation target TG to perform required processes such as processing, cutting, heating, and modification of the irradiation target TG. The irradiation target TG is not particularly limited as long as it is an object that requires irradiation with a high-power laser beam.

[0012] The first laser beam generator 2 emits a first laser beam group L1. The first laser beam group L1 includes a plurality of annular laser beams having different diameters and having a common emission axis on a first axis AX1. The cross-sectional shape of the first laser beam group L1 is shown in the dotted frame A1 in FIG. 1. The first laser beam group L1 has a coaxial multi-ring shape in a cross-section orthogonal to the first axis AX1, that is, a cross-section orthogonal to the optical path.

[0013] As the first laser beam generator 2, for example, a known laser beam generator including a plurality of laser light sources, an axicon mirror, and a scraper mirror can be used. Examples of the laser light source include a fiber laser, a solid-state laser, and a semiconductor laser. The laser light source emits a solid laser beam. The axicon mirror converts the solid laser beam into an annular laser beam. The scraper mirror forms an optical path for superimposing a plurality of annular laser beams coaxially.

[0014] The second laser beam generator 3 emits a second laser beam L2. The second laser beam L2 is emitted on a second axis AX2 different from the first axis AX1. The cross-sectional shape of the second laser beam L2 orthogonal to the second axis AX2 is shown in the dotted frame A2 in FIG. 1. The light beam emitted by the second laser beam generator 3 as the second laser beam L2 may be either a solid second laser beam L2S or a coaxial multi-ring-shaped second laser beam group L20.

[0015] When emitting the solid second laser beam L2S, the second laser beam generator 3 is a light source device including a laser light source such as a fiber laser. When emitting a coaxially multiplexed annular second laser beam group L20, the second laser beam generator 3 is the same device as the first laser beam generator 2. The second laser beam generator 3 in this case emits a laser beam group including annular laser beams with different diameters having a common emission axis on the second axis AX2. In FIG. 1, a single second laser beam generator 3 is illustrated, but the second laser beam generators 3 are used in the number required for the second laser beam L2.

[0016] The combining optical system 4 combines the first laser beam group L1 and the second laser beam L2 and makes them incident on the main mirror 5. The combining optical system 4 is arranged on the downstream side of the first laser beam generator 2 and the second laser beam generator 3 on the optical path OP along which the first laser beam group L1 and the second laser beam L2 are emitted toward the irradiation target TG. Here, the downstream side of the optical path OP means the side in the direction in which the laser beam approaches the irradiation target TG from a reference point on the optical path OP in the laser beam flow along the optical path OP toward the irradiation target TG. The upstream side of the optical path OP means the side in the direction away from the irradiation target TG from the reference point. The combining optical system 4 makes the first laser beam group L1 incident on the first position P1 of the main mirror 5. The combining optical system 4 makes the second laser beam L2 incident on the second position P2 of the main mirror 5 different from the first position P1. A specific example of the combining optical system 4 will be described in detail later based on FIGS. 4 to 12.

[0017] The main mirror 5 is arranged on the downstream side of the combining optical system 4 on the optical path OP. The main mirror 5 condenses the combined laser beam LM of the first laser beam group L1 incident on the first position P1 and the second laser beam L2 incident on the second position P2 with respect to the irradiation target TG. The main mirror 5 includes a concave mirror surface that forms an image of the combined laser beam LM on the irradiation target TG. Instead of the main mirror 5, other optical elements capable of condensing the combined laser beam LM may be arranged. As other optical elements, for example, a convex lens can be used.

[0018] [Specific examples of synthesized laser beams] Figures 2 and 3 show the combined laser beams LM1 and LM2 as examples of laser beams generated by the laser beam combining device 1. In Figures 2 and 3, the combined laser beams LM1 and LM2 are shown as images incident on the concave surface of the primary mirror 5. That is, Figures 2 and 3 show the images formed on the primary mirror during the combining process of the combined laser beams LM1 and LM2. For convenience, in the explanation of Figures 2 and 3, these images will be referred to as the combined laser beams LM1 and LM2. The primary mirror 5 focuses these combined laser beams LM1 and LM2 into a single high-power laser beam and irradiates the target TG.

[0019] FIG. 2 shows a first example of the laser beam generated by the laser beam combining apparatus 1. The combined laser beam LM1 in FIG. 2 is composed of a first laser beam group L1 and a solid second laser beam L2S. The combined laser beam LM1 has a plurality of second laser beams L2S arranged in a ring around the first laser beam group L1. In the example of FIG. 2, the central region in the radial direction of the main mirror 5 is the first position P1, and the annular region near the outer peripheral edge in the radial direction of the main mirror 5 is the second position P2. In other words, any position in the central region is the first position P1, and any position in the annular region other than the central region is the second position P2. The first laser beam group L1 consists of five concentric circular laser beams L11, L12, L13, L14, and L15 with different diameters arranged coaxially. The relationship of the diameters of these laser beams is L11 < L12 < L13 < L14 < L15. FIG. 2 shows an example in which the first laser beam group L1 is composed of a five-layer circular laser beam, but the first laser beam group L1 may be composed of a plurality of circular laser beams with six or more layers or less than five layers. Also, in the first laser beam group L1, the five circular laser beams L11, L12, L13, L14, and L15 may or may not overlap with each other in the radial direction. In FIGS. 2 and 3, an example is shown in which the outer diameter and inner diameter of the concentric circles of the adjacent laser beams in the radial direction are arranged with a gap between them, for example, there is a gap between the outer diameter of the laser beam L11 and the inner diameter of the laser beam L12.

[0020] In the examples of FIGS. 2 and 3, the plurality of second laser beams L2S arranged in a ring closely surround the outer periphery of the first laser beam group L1 with almost no gap in the radial and circumferential directions. Even if it is not necessarily closely surrounded, the second laser beam L2S may be intermittently arranged in the circumferential direction on the outer periphery of the first laser beam group L1. Also, FIG. 2 shows an example in which the diameters of the images of the plurality of second laser beams L2S are the same, but the diameters of the images may be different. The plurality of second laser beams L2S may be arranged so as to surround the outer periphery of the first laser beam group L1 with two or more rings in the radial direction.

[0021] Figure 3 shows a second example of the laser beam generated by the laser beam synthesizing apparatus 1. The combined laser beam LM2 in Figure 3 is composed of a first laser beam group L1 and a second laser beam group L20. The combined laser beam LM2 has a plurality of second laser beam groups L20 arranged in a ring around the first laser beam group L1. The first laser beam group L1 is the same as the example in Figure 2. The second laser beam group L20 consists of two annular laser beams L201 and L202 with different diameters, which are arranged coaxially and superimposed. The relationship between the diameters of these laser beams is L201 < L202. The second laser beam group L20 may be composed of three or more annular laser beams.

[0022] As described above, in the laser beam synthesizing apparatus 1, the first laser beam group L1 and the second laser beam L2 emitted along the first axis AX1 and the second axis AX2, which are two different optical axes, are combined into one by the combining optical system 4 to generate the combined laser beams LM1 and LM2. The combined laser beams LM1 and LM2 are condensed by the main mirror 5 and irradiated onto the irradiation target TG. According to the present embodiment, compared with the case where a plurality of annular laser beams are arranged and combined on one axis, it is easier to combine more laser beams. Therefore, it is also easy to achieve suppression of the enlargement of the optical element that performs the condensing function, such as the main mirror 5.

[0023] The combined laser beams LM1 and LM2 have a shape in which a plurality of the second laser beams are arranged in a ring around the image of the first laser beam group L1. Therefore, a large number of laser beams can be arranged at a high density on the concave mirror surface of the main mirror 5. That is, more laser beams can be combined while suppressing the enlargement of the size of the main mirror 5. In particular, in the combined laser beam LM2 using the second laser beam group L20 as the second laser beam L2, it is possible to combine a larger number of laser beams.

[0024] [Specific Example of Combining Optical System] Next, we will explain specific examples of the composite optical system 4. Below, we will illustrate the first to fourth examples, which use one or more scraper mirrors, and the fifth example, which uses a polygonal pyramidal mirror. A scraper mirror is a flat plate equipped with an aperture through which the laser beam passes and a mirror surface that reflects the laser beam. A polygonal pyramidal mirror is a mirror in which the side surface of a polygonal pyramid or frustum of a polygon is used as a mirror surface that reflects the laser beam.

[0025] <Example 1> Figure 4 is an optical path diagram showing the composite optical system 4 according to the first example, using one scraper mirror 41. Figure 5 is a schematic diagram showing the composite optical system 4 of Figure 4 in three dimensions. In the first example and the second to fifth examples described later, the composite optical system 4 that generates the composite laser beam LM2 shown in Figure 3 is assumed. The composite optical system 4 includes a scraper mirror 41 placed on the optical path OP that irradiates the laser beam onto the irradiation target TG.

[0026] The scraper mirror 41 includes a body 411, an aperture 412, and a mirror surface 413. The body 411 is a circular flat plate. The body 411 may also be a shape other than circular, such as an ellipse, square, polygon, or rectangle. The aperture 412 is a circular opening concentric with the circular body 411 and located in the center of the body 411. The aperture 412 may also be a shape other than circular. The mirror surface 413 is a surface that reflects the laser beam and is provided on one side of the body 411. Since the aperture 412 is located in the center of the body 411, the mirror surface 413 is an annular surface located radially outward from the aperture 412.

[0027] The scraper mirror 41 is positioned at a predetermined angle with respect to the first axis AX1, which is the emission axis of the first laser beam group L1. The aperture 412 is opened to a size that allows the first laser beam group L1 to pass through. For example, if the scraper mirror 41 is positioned at a 45-degree angle with respect to the first axis AX1, the inner circumferential surface defining the aperture 412 becomes a cylindrical surface inclined at a 45-degree angle with respect to the flat portion of the main body 411. In the first example, the mirror surface 413 becomes a surface that reflects the required number of second laser beam groups L20.

[0028] The first laser beam group L1 passes through the aperture 412 without interfering with the scraper mirror 41 and heads toward the primary mirror 5 located downstream in the optical path. Multiple second laser beam groups L20 are incident on the mirror surface 413 from the second axis AX2, which is set to intersect with the first axis AX1. Multiple second laser beam groups L20 are reflected by the mirror surface 413 and head toward the primary mirror 5.

[0029] The mirror surface 413 is tilted by a predetermined angle with respect to the second axis AX2. The predetermined angle is selected to allow the second laser beam group L20 to be reflected parallel to the first laser beam group L1. Multiple second laser beam groups L20 are incident on the annular mirror surface 413 so as to be arranged in a ring shape on the mirror surface 413. In other words, the second axis AX2 of the second laser beam generator 3 is set so that each second laser beam group L20 is incident on different positions in the circumferential direction of the mirror surface 413. As a result, a composite laser beam LM2 is generated in which multiple second laser beam groups L20 are arranged in a ring shape around the first laser beam group L1.

[0030] As a modification of the first example, the second laser beam group L20 may be configured to pass through the aperture 412 of the scraper mirror 41, and the first laser beam group L1 may be reflected by the mirror surface 413. In the modification, for example, in Figure 5, a scraper mirror 41 is used which has an aperture 412 at each position where multiple second laser beam groups L20 are irradiated, and the position through which the first laser beam group L1 passes is the mirror surface 413. Multiple second laser beam generators 3 are arranged so that each second laser beam group L20 is incident on the optical path from the upstream side of the scraper mirror 41. The first laser beam generator 2 is arranged so that the first laser beam group L1 is incident on the side of the scraper mirror 41.

[0031] <Example 2> Figure 6 is an optical path diagram showing a composite optical system 4A according to the second example, which uses two scraper mirrors 42 and 43. Figure 7 is a schematic diagram showing the composite optical system 4A in three dimensions. In the first example, all of the second laser beam group L20 to be synthesized are incident on the mirror surface 413 of a single scraper mirror 41. If the configuration of the first example is adopted, it may be physically difficult to arrange the members that form the incident optical path from multiple second laser beam generators 3 to the scraper mirror 41. In the second example, in order to allow for more flexibility in the arrangement of the optical path forming members, two scraper mirrors 42 and 43 are used, and the second laser beam group L20 is merged with the first laser beam group L1 in two stages.

[0032] The composite optical system 4A includes a first scraper mirror 42 and a second scraper mirror 43 positioned downstream of the first scraper mirror 42 in the optical path. The first scraper mirror 42 includes a first body 421, a first aperture 422 and a first mirror surface 423, similar to the body 411, aperture 412 and mirror surface 413 of the scraper mirror 41 of the first example.

[0033] The second scraper mirror 43 includes a second body 431, a second opening 432, a third opening 433, and a second mirror surface 434. The second body 431 is a circular flat plate. The second opening 432 is a circular opening concentric with the circular second body 431 and located in the center of the second body 431. The third opening 433 is an opening in the second body 431 located radially outside the second opening 432. As an example, the third opening 433 is provided at four equally spaced locations around the second body 431. The shapes of the first opening 422, the second opening 432, and the third opening 433 may be set as appropriate, insofar as the reflective function of the first mirror surface 423 and the second mirror surface 434 is ensured.

[0034] The first scraper mirror 42 and the second scraper mirror 43 are positioned such that the first aperture 422 and the second aperture 432 are aligned on the same axis of the optical path of the first laser beam group L1. As a result, the first mirror surface 423 and the second mirror surface 434 are aligned in the direction of extension of the optical path OP. Furthermore, the first scraper mirror 42 and the second scraper mirror 43 are positioned at a predetermined angle with respect to the first axis AX1 of the first laser beam group L1. The angle of the first scraper mirror 42 with respect to the first axis AX1 may be the same as or different from the angle of the second scraper mirror 42 with respect to the first axis AX1. In the second example, four second laser beams L20 are incident on the first scraper mirror 42, and four second laser beams L20 are also incident on the second scraper mirror 43. The number of second laser beam groups L20 incident on each of the scraper mirrors 42 and 43 may be set as appropriate.

[0035] The first laser beam group L1, emitted along the first axis AX1, sequentially passes through the first aperture 422 and the second aperture 432, and heads toward the primary mirror 5. The second laser beam group L20, incident on the first scraper mirror 42, is reflected by the first mirror surface 423 so as to move downstream of the optical path OP along the outer circumference of the first laser beam group L1. The reflected second laser beam group L20 passes through the third aperture 433 of the second scraper mirror 43, and heads toward the primary mirror 5. The opening position of the third aperture 433 corresponds to the incident position of the second laser beam group L20 on the first mirror surface 423. The number of third apertures 433 and their arrangement on the second scraper mirror 43 are determined by the second laser beam group L20 that passes through the second scraper mirror 43. The third aperture 433 may have an aperture shape that allows multiple second laser beam groups L20 to pass through. Furthermore, part or all of the second aperture 432 and the third aperture 433 may be formed by a single aperture. In other words, the second body 431 may have an aperture through which part or all of the first laser beam group L1 and the multiple second laser beam groups L20 can pass together.

[0036] The second laser beam group L20 is incident on the second mirror surface 434, which is located between adjacent third apertures 433, with respect to the second scraper mirror 43. The second laser beam group L20 incident on the second scraper mirror 43 is reflected by the second mirror surface 434 along the outer circumference of the first laser beam group L1 and between the second laser beam groups L20 that have passed through the third apertures 433, so as to be directed downstream of the optical path OP. As a result, a composite laser beam LM is generated, in which the intended number of second laser beam groups L20 are arranged in a ring around the outer circumference of the first laser beam group L1.

[0037] In the second example of the composite optical system 4A, there are two confluence points where the second laser beam group L20 merges with the first laser beam group L1: the first scraper mirror 42 and the second scraper mirror 43. This allows for the construction of a composite optical system 4A with ample layout space, making it possible to combine a larger number of laser beams. Three or more scraper mirrors may be arranged to further increase the number of confluence points for the second laser beam group L20 with the first laser beam group L1.

[0038] <Example 3> The third example shows the second example described above, with the addition of a beam rotation device that rotates the beam cross-sections of the first laser beam group L1 and the second laser beam group L20 by a predetermined angle around the first axis AX1 before emission. By rotating the beam cross-section, the degree of freedom in the incidence manner of the first laser beam group L1 and the second laser beam group L20 to the composite optical system can be increased. Figure 8 is an optical path diagram of the composite optical system 4B according to the third example to which the beam rotation device 6 is applied. A perspective view of the beam rotation device 6 is attached to Figure 8.

[0039] The composite optical system 4B includes a beam rotating device 6 in addition to the first scraper mirror 42 and second scraper mirror 43, similar to those in the second example. The beam rotating device 6 is positioned between the first scraper mirror 42 and the second scraper mirror 43 on the optical path OP of the first laser beam group L1. In a plan view, the optical path OP is bent by 90 degrees at the position of the beam rotating device 6.

[0040] The beam rotating device 6 includes, as an example, a rectangular parallelepiped-shaped first mirror box 61 and a second mirror box 62. The first mirror box 61 includes an entrance opening 611 and a first mirror 612. The entrance opening 611 is an opening for taking in the first laser beam group L1 and the second laser beam group L20 reflected by the first scraper mirror 42 into the first mirror box 61. The first mirror 612 is located inside the first mirror box 61. The first mirror 612 has a first mirror surface M1 that is inclined at 45 degrees with respect to the optical path OP toward the first mirror 612. The first mirror 612 reflects the first laser beam group L1 and the second laser beam group L20 that have entered the first mirror box 61 so as to bend their direction of travel by 90 degrees. In the example shown in Figure 8, the first mirror surface M1 is tilted 45 degrees downward with respect to the optical path OP so as to reflect the laser beam groups L1 and L20, which are incident on the first mirror box 61 from the horizontal, vertically downward.

[0041] The second mirror box 62 includes an exit opening 621 and a second mirror 622. The second mirror box 62 is positioned adjacent to the exit surface of the laser beam group from the first mirror box 61. Figure 8 shows an example in which the second mirror box 62 is positioned directly below the first mirror box 61. The first mirror box 61 and the second mirror box 62 have openings on their adjacent surfaces that allow the laser beam groups L1 and L20 to pass through.

[0042] The second mirror 622 is located inside the second mirror box 62. The second mirror 622 has a second mirror surface M2 that is inclined at 45 degrees with respect to the optical path OP of the first laser beam group L1 and the second laser beam group L20 emitted from the first mirror box 61. The second mirror surface M2 is opposite the first mirror surface M1 in the vertical direction, but its surface direction is 90 degrees different from that of the first mirror surface M1. The second mirror 622 reflects the first laser beam group L1 and the second laser beam group L20 that are incident on the second mirror box 62, bending their direction of travel by 90 degrees and rotating their beam cross-sections by 90 degrees. The exit aperture 621 is an aperture through which the laser beam groups L1 and L20 reflected by the second mirror 622 are emitted outside the second mirror box 62. Figure 8 shows an example in which the exit aperture 621 is opened on the side perpendicular to the entrance aperture 611.

[0043] Figure 8 shows an example of a composite optical system 4B in which four second laser beam groups L21, L22, L23, and L24 are arranged along the periphery of the first laser beam group L1 as the second laser beam group L20. The first laser beam group L1 is emitted towards the first scraper mirror 42 along the first axis AX1. The two preceding second laser beam groups L21 and L22 are emitted towards the first scraper mirror 42 along the second axis AX21, which is perpendicular to the first axis AX1. The first scraper mirror 42 allows the first laser beam group L1 to pass through and reflects the preceding second laser beam groups L21 and L22, bending them by 90 degrees. As a result, the laser beams L1 and L20 are incident on the first mirror box 61 in a positional relationship where the two second laser beams L21 and L22 are aligned horizontally with the first laser beam group L1 at a 180-degree interval in the circumferential direction.

[0044] As the first laser beam group L1 and the second laser beam groups L21 and L22 pass through the beam rotation device 6 of this embodiment, the direction of travel of the first laser beam group L1 and the second laser beam groups L21 and L22 is first changed downward by 90 degrees, then changed horizontally by another 90 degrees, and in addition, the beam cross-section is rotated by 90 degrees around the first axis AX1. In other words, the two second laser beam groups L21 and L22 are positioned vertically aligned around the first laser beam group L1 as they head towards the second scraper mirror 43. At this time, the beam cross-section of the first laser beam group L1 also rotates, but since it is a rotation around the central axis of the concentric circles, i.e., the first axis AX1, no substantial change occurs. These first laser beam group L1 and the second laser beam groups L21 and L22 pass through the second scraper mirror 43.

[0045] The second scraper mirror 43 receives the two subsequent second laser beam groups L23 and L24 along the second axis AX22, which is perpendicular to the direction of propagation of the laser beam groups L1 and L20. The subsequent second laser beam groups L23 and L24 are reflected by the second scraper mirror 43 so as to align horizontally with the first laser beam group L1 at 180-degree intervals in the circumferential direction. As a result, a composite laser beam is generated in which the four second laser beam groups L21, L22, L23, and L24, both preceding and succeeding, align around the first laser beam group L1 at 90-degree intervals in the circumferential direction. According to the third example, there is an advantage in that the incident optical system of the second laser beam generator 3, which emits the preceding second laser beam groups L21 and L22 and the subsequent second laser beam groups L23 and L24, can be arranged in a planar rather than three-dimensional manner. This point will be further described with reference to Figure 10.

[0046] <Example 4> Figure 9 is an optical path diagram showing a composite optical system 4C according to a fourth example in which a beam rotating device 6 is applied. The basic configuration of the composite optical system 4C is the same as that of the third example described above, but it differs from the third example in that the beam rotating device 6 is arranged in multiple stages on the optical path. The composite optical system 4C includes a first scraper mirror 42 having a first mirror 612, a second scraper mirror 43 including a second mirror 622, and a plurality of beam rotating devices 6, 6A, 6B, and 6C.

[0047] The first scraper mirror 42, the second scraper mirror 43, and the beam rotating device 6 located at the uppermost stage of the optical path OP are substantially the same as in the third example. However, the first mirror 612 and the second mirror 622 of the beam rotating device 6 at the uppermost stage are positioned such that the beam cross-sections of the first laser beam group L1 and the second laser beam groups L21 and L22 are rotated by a predetermined angle, in this case 45 degrees, instead of 90 degrees. Therefore, the subsequent second laser beam groups L23 and L24, which merge from the second scraper mirror 43, are positioned around the first laser beam group L1 at a position shifted 45 degrees circumferentially relative to the preceding second laser beam groups L21 and L22, respectively.

[0048] Downstream of the second scraper mirror 43 on the optical path OP, the next stage beam rotating device 6A is positioned. The first mirror 612 and the second mirror 622 of the beam rotating device 6A are arranged in a relationship that rotates the beam cross-sections of the first laser beam group L1 and the second laser beam groups L21, L22, L23, and L24 by 45 degrees around the first axis AX1.

[0049] Downstream of the beam rotating device 6A, another scraper mirror is positioned, and yet another second laser beam group is merged into it. Subsequently, beam rotating devices 6B and 6C, positioned downstream on the optical path OP, sequentially rotate the beam cross-section and merge another second laser beam group. In this way, by sequentially bending the optical path OP and rotating the beam cross-section while merging the two laser beam groups one by one, a composite laser beam can be generated in which the required number of second laser beam groups L20 are densely arranged around the first laser beam group L1.

[0050] Figure 10 is a three-dimensional optical path diagram of the same composite optical system 4B as in Figure 8, with the laser beam incidence added. For ease of explanation, Figure 10 includes XYZ direction indicators. In Figure 10, the composite optical system 4B is depicted with the X direction as left and right, the Y direction as front and back, and the Z direction as up and down, but these are not intended to limit the installation direction in the actual device.

[0051] The first laser beam generator 2 is positioned on the +X side of the beam rotation device 6 and emits the first laser beam group L1 in the -X direction. The first axis AX1 is directed toward the first mirror 612 through the first aperture 422 of the first scraper mirror 42 and the entrance aperture 611 of the first mirror box 61. The two preceding second laser beam generators 3A and 3B are positioned on the -Y side of the first scraper mirror 42 and are placed side by side in the X direction. The second laser beam generators 3A and 3B emit the second laser beam groups L21 and L22 along the second axis AX21 which is oriented in the +Y direction. The second laser beam groups L21 and L22 are reflected toward the -X direction by the first scraper mirror 42. Downstream of the optical path OP of the first scraper mirror 42, a composite laser beam LM01 is formed by the confluence of the second laser beam groups L21 and L22 on the -Y and +Y sides of the first laser beam group L1, respectively.

[0052] The first mirror 612 is positioned at a 45-degree downward angle with respect to the optical path OP. The second mirror 622 is positioned on the -Z side of the first mirror 612 and is positioned at a 45-degree upward angle. The planes of the first mirror 612 and the second mirror 622 are 90 degrees apart. The composite laser beam LM01 is reflected in the -Z direction by the first mirror 612, and then reflected in the -Y direction after the beam cross-section is rotated by 90 degrees by the second mirror 622. Downstream of the optical path OP of the second mirror 622, the composite laser beam LM01 is formed by positioning the second laser beam groups L21 and L22 on the +Z and -Z sides, respectively, of the first laser beam group L1. The second scraper mirror 43A is positioned on the -Y side of the second mirror 622. The second scraper mirror 43A has an elliptical second aperture 432A that is elongated vertically in the Z direction, through which the composite laser beam LM01, whose beam cross-section has been rotated, passes. The second scraper mirror 43A may also be provided with an aperture that allows the first laser beam group L1 and the second laser beam groups L21 and L22 of the composite laser beam LM01 to pass through individually.

[0053] The two subsequent second laser beam generators 3C and 3D are positioned on the -X side of the second scraper mirror 43A and are arranged side by side in the Y direction. The second laser beam generators 3C and 3D emit second laser beam groups L23 and L24 along the second axis AX22 which is oriented in the +X direction. The second laser beam groups L23 and L24 are reflected in the -Y direction by the second scraper mirror 43A. Downstream of the optical path OP of the second scraper mirror 43A, a composite laser beam LM02 is formed by the further merging of the second laser beam groups L23 and L24 with the -X and +X sides of the first laser beam group L1.

[0054] According to this embodiment, by interposing the beam rotation device 6, the first laser beam generator 2, the preceding second laser beam generators 3A and 3B, and the subsequent second laser beam generators 3C and 3D can be arranged on the XY plane. If the beam rotation device 6 is not used, the subsequent second laser beam generators 3C and 3D or the second axis AX22 must be positioned on the +Z or -Z side with respect to the optical path OP, resulting in a three-dimensional arrangement of the incident optical systems for the second laser beam groups L23 and L24. In this case, the composite optical system 4B becomes larger and more complex. In contrast, in this embodiment, the two second axes AX21 and AX22 can be set on the same plane, so the incident optical systems, such as the mirrors that guide light to the scraper mirrors 41 and 42 of the second laser beam groups L21, L22, L23, and L24, can be arranged in a planar manner. Therefore, it is easier to make the composite optical system 4B more compact and simpler.

[0055] <Example 5> Figure 11 is an optical path diagram showing a composite optical system 4D according to the fifth example using a polygonal pyramidal mirror. A polygonal pyramidal mirror is a cube composed of one vertex, one polygonal base, and multiple sides connecting these bases and the vertex. The polygonal pyramidal mirror may also be in the form of a frustum without a vertex. The polygonal pyramidal mirror 44 applied to the composite optical system 4D includes a frustum 45 and a mirror surface 46.

[0056] The frustum of a polygon 45 includes a hexagonal upper base 451 and lower base 452, and six trapezoidal sides 453 connecting the upper base 451 and the lower base 452. The frustum of a polygon 45 may be a triangular, square, pentagonal, or heptagonal or more. The upper base 451 and lower base 452 are aperture surfaces through which the first laser beam group L1 passes. Mirror surfaces 46 are arranged on each of the sides 453. The mirror surfaces 46 reflect the second laser beam group L20. Examples of methods for forming the mirror surfaces 46 include attaching mirrors to the sides 453 or providing a reflective coating layer on the sides 453.

[0057] The first laser beam group L1 passes through the openings at the upper base 451 and lower base 452 of the polygonal pyramidal mirror 44 and heads toward the primary mirror 5 shown in Figure 1. The six second laser beam groups L20 are each reflected by the six mirror surfaces 46 so as to follow the outer circumference of the first laser beam group L1. The six mirror surfaces 46 are arranged to surround the first laser beam group L1 as it passes through the polygonal pyramidal mirror 44. As a result, a composite laser beam LM2 is generated in which the six second laser beam groups L20 are arranged in a ring around the first laser beam group L1. Alternatively, the first laser beam group L1 may be reflected by the mirror surfaces 46, and some or all of the multiple second laser beam groups L20 may pass through the polygonal pyramidal mirror 44.

[0058] Figure 12 shows the overall structure of the composite optical system 4D. In addition to the polygonal pyramidal mirror 44 described above, the composite optical system 4D includes a light guide tube 47, a light guide mirror 48, and a reflective mirror 49. The light guide tube 47 is a cylindrical body in which the polygonal pyramidal mirror 44 is arranged. Figure 12 includes a side cross-sectional view of the light guide tube 47 along the optical path OP and a front view seen from the downstream side of the optical path OP. The polygonal pyramidal mirror 44 is supported on the axis of the light guide tube 47 by a plurality of support bars 441 extending, for example, from the inner surface of the light guide tube 47.

[0059] The light guide mirrors 48 and reflective mirrors 49 are optical components for guiding the second laser beam group L20 to the polygonal pyramidal mirror 44. The light guide mirrors 48 are erected on a base 480. The same number of light guide mirrors 48 as the number of second laser beam groups L20 that merge with the first laser beam group L1 are erected on the base 480. Each light guide mirror 48 is set at an angle that reflects the second laser beam group L20 into the cylinder of the light guide tube 47. The reflective mirrors 49 are located on the inner surface of the light guide tube 47 and around the polygonal pyramidal mirror 44. The reflective mirrors 49 reflect the second laser beam group L20 introduced from the light guide mirrors 48 toward the mirror surface 46 of the polygonal pyramidal mirror 44. It is desirable that the reflective surface of the reflective mirrors 49 be adjustable in angle to control the reflection angle of the second laser beam group L20.

[0060] The first laser beam generator 2 is positioned opposite the light guide cylinder 47, and the first laser beam group L1 is emitted toward the aperture of the polygonal pyramidal mirror 44. Multiple second laser beam generators 3 emit second laser beam groups L20 toward their respective light guide mirrors 48. The second laser beam groups L20 are sequentially reflected by the light guide mirror 48, the reflection mirror 49, and the mirror surface 46 of the polygonal pyramidal mirror 44, and merge within the light guide cylinder 47 along the periphery of the first laser beam group L1 that has passed through the polygonal pyramidal mirror 44. This merging generates a composite laser beam LM2.

[0061] [Modified examples of synthesized laser beams] In the above embodiment, the composite laser beams LM1 and LM2 are shown in which a plurality of second laser beams L2 are arranged in a ring around the first laser beam group L1. There are no particular restrictions on the arrangement of the first laser beam group L1 and the second laser beams L2, and the composite laser beam may be formed in any arrangement. Figure 13 shows various modified examples of the composite laser beam. In Figure 13, six composite laser beams LM3, LM4, LM5, LM6, LM7, and LM8 are exemplified as images formed on the primary mirror 5.

[0062] The combined laser beam LM3 is formed by arranging one first laser beam group L1 and one solid second laser beam L2S side by side. The combined laser beam LM4 is formed by arranging one first laser beam group L1 and one coaxially multiplexed annular second laser beam group L20 side by side. These combined laser beams LM3 and LM4 are the simplest examples of combined laser beams.

[0063] The combined laser beam LM5 is configured such that the first laser beam group L1 is eccentric with respect to the center of the main mirror 5, and six solid second laser beams L2S are arranged in an arc shape in the space created by this eccentricity. The combined laser beam LM6 is configured such that three coaxially multiple annular second laser beam groups L20 are arranged in an arc shape in the space created by the eccentricity of the first laser beam group L1. The combined laser beam LM7 is configured such that solid second laser beams L2S and coaxially multiple annular second laser beam groups L20 are arranged alternately in an arc shape in the space created by the eccentricity of the first laser beam group L1.

[0064] The combined laser beam LM8 is configured such that a single solid second laser beam L2S is incident on the central space of the first laser beam group L1. The number of combined laser beams can also be increased by using the modified combined laser beam described above.

[0065] [Summary of this disclosure] The specific embodiments described above include disclosures having the following configurations.

[0066] A laser beam synthesis apparatus according to a first aspect of the present disclosure includes: a first laser beam generator that emits a first group of laser beams including a plurality of annular-shaped laser beams of different diameters whose emission axes lie on a common first axis; a second laser beam generator that emits a second laser beam on a second axis different from the first axis; an optical element disposed downstream of the first laser beam generator and the second laser beam generator in the optical path from which the first group of laser beams and the second laser beam are emitted, and which focuses the first group of laser beams and the second laser beam toward a target; and a synthesis optical system that causes the first group of laser beams to be incident on a first position of the optical element and the second laser beam to be incident on a second position of the optical element different from the first position.

[0067] According to the first embodiment, a first group of laser beams is incident on a first position of the optical element from the optical path of the first axis, and a second laser beam is incident on a second position from the optical path of the second axis. In other words, laser beams emitted along two different optical axes can be combined into one by a combining optical system, and the combined group of laser beams can be focused by the optical element. As a result, users can more easily combine more laser beams compared to the case where multiple annular laser beams are arranged on a single axis and combined, and it is also easier to suppress the increase in size of the optical element.

[0068] The laser beam synthesis apparatus according to the second embodiment is the laser beam synthesis apparatus according to the first embodiment, wherein the synthesis optical system causes the first laser beam group and the plurality of second laser beams to be incident on the optical element in such a manner that a plurality of second laser beams are arranged in a ring around the first laser beam group.

[0069] According to the second embodiment, since multiple second laser beams are arranged in a ring around the annular first laser beam group, many laser beams can be arranged at high density. In other words, the user can synthesize more laser beams while suppressing an increase in the size of the optical element.

[0070] A laser beam synthesis apparatus according to a third embodiment is a laser beam synthesis apparatus according to a first or second embodiment, wherein the second laser beam generator emits a group of laser beams, each containing multiple annular-shaped laser beams of different diameters with their emission axes on a common second axis, as the second laser beam.

[0071] According to the third embodiment, the second laser beam is also incident on the optical element as a group of multiple annular laser beams with the second axis as the emission axis. Therefore, the user can synthesize a larger number of laser beams.

[0072] A laser beam synthesis apparatus according to the fourth embodiment is a laser beam synthesis apparatus according to the first to third embodiments, wherein the synthesis optical system includes a first scraper mirror having a first body including a first aperture and a first mirror surface, and one of the first laser beam group or the second laser beam passes through the first aperture and the other is reflected by the first mirror surface.

[0073] According to the fourth aspect, the user can cause the optical element to be incident in a composite manner, in which the first laser beam or the second laser beam that has passed through the first aperture is followed by the other beam reflected by the first mirror surface.

[0074] A laser beam synthesis apparatus according to the fifth embodiment is a laser beam synthesis apparatus according to the first to fourth embodiments, wherein the synthesis optical system further includes a second body having a second aperture and a third aperture, and a second mirror surface, and is positioned downstream of the first scraper mirror in the optical path, the first aperture and the second aperture are aligned on the same axis of the optical path, the first group of laser beams passes through the first aperture and the second aperture, at least one of the second laser beams reflected by the first mirror surface passes through the third aperture, and at least one of the second laser beams is reflected by the second mirror surface.

[0075] According to the fifth embodiment, the points where the first and second laser beams, which have passed through the first aperture, are joined together are located at two locations: the first and second scraper mirrors. This allows for more flexibility in the layout of the combining optical system, enabling the user to combine more laser beams.

[0076] The laser beam synthesis apparatus according to the sixth embodiment is a laser beam synthesis apparatus according to the first to fifth embodiments, wherein the synthesis optical system includes a beam rotation device that rotates the beam cross-sections of the first laser beam group and the second laser beam by a predetermined angle before emission.

[0077] According to the sixth aspect, since the beam cross-section can be rotated, the degree of freedom in the incidence of the first laser beam group and the second laser beam onto the composite optical system can be increased.

[0078] The laser beam synthesis apparatus according to the seventh embodiment is a laser beam synthesis apparatus according to the first to sixth embodiments, wherein the synthesis optical system includes a polygonal pyramidal mirror in which a plurality of mirror surfaces are arranged on the side surface of a polygonal pyramid, and at least one of the first laser beam group and the second laser beam is reflected by the mirror surface and guided to the optical element.

[0079] According to the seventh embodiment, the user can utilize a polygonal pyramidal mirror to cause at least one of the first laser beam group and the second laser beam to be incident on an optical element in a desired optical path.

[0080] The laser beam synthesis apparatus according to the eighth embodiment is a laser beam synthesis apparatus according to the first to seventh embodiments, wherein the polygonal pyramidal mirror has a plurality of mirror surfaces, each arranged on the side surface of a frustum of polygons having an upper base and a lower base, the first group of laser beams passes through the upper and lower bases of the frustum of polygons, and the plurality of second laser beams are reflected by each of the plurality of mirror surfaces.

[0081] According to the eighth aspect, the user can form a ring-shaped group of second laser beams by reflecting each of the second laser beams off the mirror surface of a polygonal pyramidal mirror. Thus, the user can generate a composite laser beam in which the ring-shaped group of second laser beams is arranged around the group of first laser beams that have passed through a frustum of a polygon.

[0082] A laser beam synthesis method according to the ninth embodiment involves generating a first laser beam group including multiple annular laser beams of different diameters whose emission axes lie on a common first axis; generating a second laser beam that emits on a second axis different from the first axis; and injecting the first laser beam group into a first position of an optical element having the function of focusing multiple laser beams toward a target, and injecting the second laser beam into a second position different from the first position.

[0083] According to the ninth embodiment, a group of first laser beams is incident on the first position of the optical element from the optical path of the first axis, and a second laser beam is incident on the second position from the optical path of the second axis. In other words, laser beams emitted along two different optical axes can be focused by the optical element. This makes it easier for the user to combine more laser beams and also makes it easier to suppress the increase in size of the optical element.

[0084] The laser beam synthesis method according to the tenth embodiment is the laser beam synthesis method according to the ninth embodiment, wherein the first laser beam group and the plurality of second laser beams are incident on the optical element in such a manner that the plurality of second laser beams are arranged in a ring around the first laser beam group.

[0085] According to the tenth embodiment, the user arranges multiple second laser beams in a ring around a ring-shaped first group of laser beams, allowing for a high density of laser beams. In other words, the user can synthesize more laser beams while suppressing an increase in the size of the optical elements.

[0086] The laser beam synthesis method according to the 11th embodiment is a laser beam synthesis method according to the 9th or 10th embodiment, wherein the second laser beam is generated as a group of laser beams including multiple annular-shaped laser beams of different diameters whose emission axes are on the second axis which has a common emission axis.

[0087] According to the eleventh embodiment, the two laser beams are also incident on the optical element as a group of multiple annular laser beams with the second axis as the emission axis. Therefore, the user can synthesize more laser beams. [Explanation of symbols]

[0088] 1. Laser beam synthesis device 2. First laser beam generator 3. Second laser beam generator 4, 4A, 4B, 4C, 4D synthetic optical system 41. Scraper mirror (1st scraper mirror) 411, 412, 413 Main body (1st body), opening (1st opening), mirror surface (1st mirror surface) 42. First Scraper Mirror 421, 422, 423 1st body, 1st opening, 1st mirror surface 43. Second Scraper Mirror 431, 432, 433, 434 2nd body, 2nd opening, 3rd opening, 2nd mirror surface 44 Polygonal Pyramid Mirrors 451, 452, 453 Top bottom, bottom bottom, side 46 Mirror surface 5. Primary mirror (optical element) 6. Beam Rotation Device AX1, AX2 1st axis, 2nd axis P1, P2 1st position, 2nd position L1 First Laser Beam Group L2 Second laser beam L20 Second Laser Beam Group LM Synthetic Laser Beam LM OP optical path TG irradiation target

Claims

1. A first laser beam generator that emits a group of first laser beams, including multiple annular-shaped laser beams of different diameters whose emission axes lie on a common first axis, A second laser beam generator that emits a second laser beam on a second axis different from the first axis, An optical element is positioned downstream of the first laser beam generator and the second laser beam generator in the optical path from which the first laser beam group and the second laser beam are emitted, and focuses the first laser beam group and the second laser beam toward a target. A composite optical system that directs the first laser beam group to a first position of the optical element and directs the second laser beam to a second position of the optical element different from the first position, A laser beam synthesis device equipped with the following features.

2. In the laser beam synthesis apparatus according to claim 1, The aforementioned synthesis optical system is a laser beam synthesis device that causes the first laser beam group and the plurality of second laser beams to be incident on the optical element in a manner in which a plurality of second laser beams are arranged in a ring around the first laser beam group.

3. In the laser beam synthesis apparatus according to claim 1 or 2, The second laser beam generator is a laser beam synthesizer that emits a group of laser beams, including multiple annular-shaped laser beams of different diameters, with their emission axes on the common second axis, as the second laser beam.

4. In the laser beam synthesis apparatus according to claim 1 or 2, The composite optical system includes a first scraper mirror having a first body including a first aperture and a first mirror surface, A laser beam combining apparatus in which one of the first laser beam group or the second laser beam passes through the first aperture and the other is reflected by the first mirror surface.

5. In the laser beam synthesis apparatus according to claim 4, The composite optical system further includes a second body having a second aperture and a third aperture, and a second mirror surface, and a second scraper mirror positioned downstream of the first scraper mirror in the optical path. The first aperture and the second aperture are aligned on the same axis of the optical path, and the first laser beam group passes through the first aperture and the second aperture. At least one of the second laser beams reflected by the first mirror surface passes through the third aperture. A laser beam combining apparatus in which at least one other of the second laser beams is reflected by the second mirror surface.

6. In the laser beam synthesis apparatus according to claim 4, The laser beam synthesis apparatus includes a beam rotation device that rotates the beam cross-sections of the first laser beam group and the second laser beam by a predetermined angle before emission.

7. In the laser beam synthesis apparatus according to claim 1 or 2, The composite optical system includes a polygonal pyramidal mirror in which multiple mirror surfaces are arranged on the side surface of a polygonal pyramid, A laser beam combining apparatus in which at least one of the first laser beam group and the second laser beam is reflected by the mirror surface and guided to the optical element.

8. In the laser beam synthesis apparatus according to claim 7, The aforementioned polygonal pyramidal mirror has a plurality of mirror surfaces, each positioned on the side surface of a frustum of a polygon having an upper base and a lower base. A laser beam combining apparatus in which the first group of laser beams passes through the upper and lower bases of the frustum of a polygon, and the plurality of second laser beams are reflected by the plurality of mirror surfaces.

9. A first group of laser beams is generated, which includes multiple annular-shaped laser beams of different diameters with their emission axes on a common first axis. A second laser beam is generated that is emitted on a second axis different from the first axis, A laser beam synthesis method comprising injecting a group of first laser beams into a first position of an optical element having the function of focusing multiple laser beams toward a target, and injecting a second laser beam into a second position different from the first position.

10. In the laser beam synthesis method according to claim 9, A laser beam synthesis method comprising injecting the first laser beam group and the plurality of second laser beams into the optical element in a manner in which the plurality of second laser beams are arranged in a ring around the first laser beam group.

11. In the laser beam synthesis method according to claim 9, A laser beam synthesis method that generates the second laser beam as a group of laser beams including multiple annular-shaped laser beams of different diameters, the output axis of which is on the second axis which is common.

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