Deformable mirror, laser processing device, and method of manufacturing deformable mirror

Abstract

This shape-variable mirror comprises: a reflective mirror having a reflective surface; a first support member which has a first plate section and a first fixing member and supports the reflective mirror; a second support member which has a second plate section and a second fixing member and supports the reflective mirror; and an adjustment member which changes the distance between the first plate section and the second plate section. The first plate section is disposed at a predetermined distance from the rear surface of the reflective mirror. The first fixing member is connected to the first plate section and fixes the reflective mirror at m first fixing positions of the reflective mirror, where m is an integer of no less than 2. The second plate section is disposed at a predetermined distance from the rear surface of the reflective mirror with the first plate section therebetween. The second fixing member is connected to the second plate section and fixes the reflective mirror at n second fixing positions of the reflective mirror which are different from the first fixing positions, where n is an integer of no less than 2. The shape-variable mirror has at least one among: a first protruding section which is in contact with the first fixing member and is provided to the first support member; and a second protruding section which is in contact with the second fixing member and is provided to the second support member.

Description

[Technical Field]

[0001] The present disclosure relates to a deformable mirror that corrects wavefront aberration of a light wave, a laser processing device, and a method for manufacturing the deformable mirror. [Background technology]

[0002] Deformable mirrors correct wavefront aberrations of light waves and are used in various optical instruments. Patent Document 1 describes examples of deformable mirrors applied to astronomical telescopes, laser processing devices, and the like. In astronomical telescopes, deformable mirrors are used to correct wavefront aberrations caused by atmospheric turbulence and improve image quality. In laser processing devices, deformable mirrors are used to correct wavefront aberrations caused by shape errors in mirrors and lenses and improve processing quality. Deformable mirrors, which have a large degree of freedom of deformation to correct wavefront aberrations of arbitrary shapes, are complex and expensive. Therefore, depending on the application, it may be sufficient to correct only astigmatism among wavefront aberrations. Astigmatism is an aberration that changes the focal length of the meridional plane and the focal length of the sagittal plane, where the plane containing the optical axis and the chief ray is called the meridional plane and the plane containing the chief ray and perpendicular to the meridional plane is called the sagittal plane. Patent Document 2 proposes a deformable mirror structure that corrects astigmatism. Patent Document 2 discloses a deformable mirror including a reflecting mirror having a reflective surface, a first shaft member having two legs fixed to the back surface of the reflecting mirror, a second shaft member having two legs fixed to the back surface of the reflecting mirror and spanning the first shaft member, and a distance change mechanism that changes the distance between the second shaft member and the first shaft member. In the deformable mirror described in Patent Document 2, the distance change mechanism changes the distance between the first shaft member and the second shaft member, thereby deforming the reflective surface of the reflecting mirror into a saddle shape and correcting astigmatism. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 7-66463 [Patent Document 2] Patent No. 4552848 Summary of the Invention [Problem to be solved by the invention]

[0004] Due to increasing demands on laser processing equipment, the number of mirrors and lenses used in the optical path is on the rise. As a result, the astigmatism accumulated in the light waves also increases, making it difficult for conventional deformable mirrors to adequately correct it. To correct larger astigmatism, it is necessary to reduce the rigidity of the reflecting mirror and increase the amount of saddle deformation compared to conventional methods. However, reducing the rigidity of the reflecting mirror increases the distortion that occurs on the reflecting surface when the back surface of the reflecting mirror and the legs are fixed to assemble the deformable mirror, thereby increasing the wavefront aberration of the light waves reflected by the reflecting surface. This can potentially cause a deterioration in processing quality.

[0005] The present disclosure has been made in view of the above, and has an object to provide a deformable mirror that can suppress distortion that occurs on the reflecting surface during assembly. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the deformable mirror according to the present disclosure comprises a reflector having a reflective surface that reflects light, a first support member having a first plate and a first fixing member and supporting the reflector, a second support member having a second plate and a second fixing member and supporting the reflector, and an adjustment member that changes the distance between the first plate and the second plate. The first plate is disposed at a predetermined distance from the rear surface of the reflector. The first fixing member is connected to the first plate and fixes the reflector at m first fixing points on the reflector, where m is an integer equal to or greater than 2. The second plate is disposed at a predetermined distance from the rear surface of the reflector, sandwiching the first plate. The second fixing member is connected to the second plate and fixes the reflector at n second fixing points different from the first fixing points on the reflector, where n is an integer equal to or greater than 2. The deformable mirror comprises a first fixing member The outer periphery of contacting the first support member The first plate The first protrusion and the second fixing member are provided on the The outer periphery of contacts the second support member The second plate The second protrusions are provided on at least one of the first and second protrusions. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to suppress distortion that occurs on the reflecting surface during assembly. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram schematically illustrating an example of the configuration of a laser processing device according to a first embodiment. [Figure 2] FIG. 1 is a perspective view schematically illustrating an example of the configuration of a deformable mirror according to a first embodiment; [Figure 3] FIG. 1 is a perspective view schematically illustrating an example of a configuration in which the deformable mirror according to the first embodiment is disassembled into individual components; [Figure 4] FIG. 1 is a perspective view schematically showing an example of the configuration of a first support member of a deformable mirror according to a first embodiment; [Figure 5] FIG. 10 is a perspective view schematically showing another example of the configuration of the first support member of the deformable mirror according to the first embodiment; [Figure 6] FIG. 10 is a perspective view schematically showing an example of the configuration of a second support member of the deformable mirror according to the first embodiment; [Figure 7] FIG. 10 is a perspective view schematically showing another example of the configuration of the second support member of the deformable mirror according to the first embodiment; [Figure 8] 1 is a contour diagram showing an example of the surface shape of a reflecting mirror when the deformable mirror according to the first embodiment is assembled. [Figure 9] 1 is a contour diagram showing an example of the surface shape of a reflecting mirror in a manufacturing method of a deformable mirror according to embodiment 1. [Figure 10] 1 is a contour diagram showing an example of deformation of a reflecting mirror of a deformable mirror according to embodiment 1. [Figure 11] 1 is a contour diagram showing an example of deformation of a reflecting mirror of a deformable mirror according to embodiment 1. [Figure 12]FIG. 10 is a contour diagram showing an example of the surface shape of the reflecting surface of the reflecting mirror when the deformable mirror is assembled in a case where there are no protrusions on the outer peripheral side of the plate portion adjacent to the through-hole of the first support member and on the outer peripheral side of the plate portion adjacent to the through-hole of the second support member. [Figure 13] FIG. 10 is a contour diagram showing an example of the surface shape of the reflecting surface of the reflecting mirror when the deformable mirror is assembled in a case where there are no protrusions on the outer peripheral side of the plate portion adjacent to the through-hole of the first support member and on the outer peripheral side of the plate portion adjacent to the through-hole of the second support member. [Figure 14] FIG. 10 is a contour diagram showing an example of the surface shape of the reflecting surface of the reflecting mirror when the deformable mirror is assembled in a case where there are no protrusions on the outer peripheral side of the plate portion adjacent to the through-hole of the first support member and on the outer peripheral side of the plate portion adjacent to the through-hole of the second support member. [Figure 15] FIG. 10 is a contour diagram showing an example of the surface shape of the reflecting surface of the reflecting mirror when the deformable mirror is assembled in a case where there are no protrusions on the outer peripheral side of the plate portion adjacent to the through-hole of the first support member and on the outer peripheral side of the plate portion adjacent to the through-hole of the second support member. [Figure 16] FIG. 10 is a perspective view schematically illustrating an example of a configuration in which a deformable mirror according to a second embodiment is disassembled into individual components. [Figure 17] FIG. 10 is a perspective view schematically illustrating an example of a configuration in which a deformable mirror according to a third embodiment is disassembled into individual components. [Figure 18] 10 is a contour diagram showing an example of deformation of a reflecting mirror of a deformable mirror according to a third embodiment. [Figure 19] FIG. 10 is a perspective view schematically illustrating an example of a configuration in which a deformable mirror according to a fourth embodiment is disassembled into individual components. [Figure 20] FIG. 13 is a perspective view schematically illustrating an example of a configuration in which a deformable mirror according to a fifth embodiment is disassembled into individual components. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A deformable mirror, a laser processing apparatus, and a method for manufacturing a deformable mirror according to embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0010] Embodiment 1 FIG. 1 is a diagram schematically illustrating an example of the configuration of a laser processing apparatus according to a first embodiment. The laser processing apparatus 1 includes a processing table 2, a laser oscillator 3, and an optical unit 4. A workpiece 7, which is a workpiece to be processed by the laser processing apparatus 1, is placed on the processing table 2. In one example, the processing table 2 can be moved horizontally by a drive mechanism while the workpiece 7 is fixed thereto. The laser oscillator 3 emits a laser beam L. The laser oscillator 3 is a light source that emits the laser beam L, such as a solid-state laser, gas laser, or semiconductor laser. The optical unit 4 is an optical system that focuses the laser beam L emitted from the laser oscillator 3 and irradiates the workpiece 7 with the laser beam L. The optical unit 4 includes optical elements such as lenses, mirrors, and diffraction gratings. In the example of FIG. 1, the optical unit 4 includes a mirror 5 and a deformable mirror 10 that reflect the laser beam L, and a focusing lens 6 that focuses the laser beam L on the workpiece 7. It should be noted that FIG. 1 shows an example of the configuration of the laser processing device 1, and the optical unit 4 may have other optical elements such as a collimator lens that collimates the laser beam L emitted from the laser oscillator 3.

[0011] In the laser processing apparatus 1 configured as described above, the laser beam L emitted from the laser oscillator 3 is incident on the optical unit 4. The laser beam L incident on the optical unit 4 propagates a long distance, passing through a mirror 5, a deformable mirror 10, and optical elements such as lenses and diffraction gratings (not shown). The laser beam L then passes through a condenser lens 6 and is condensed near the position of a workpiece 7 placed on the processing table 2. In this way, the workpiece 7 is subjected to processing such as cutting, drilling, and welding. The deformable mirror 10 is installed in the optical path along which the laser beam L propagates, and has the function of correcting astigmatism and reflecting the laser beam L toward the next optical element.

[0012] 2 is a perspective view schematically showing an example of the configuration of a deformable mirror according to embodiment 1. The deformable mirror 10 includes a reflecting mirror 11, a first support member 21, a second support member 31, and an adjustment screw 41.

[0013] In one example, the reflecting mirror 11 is formed of a disk-shaped member. The reflecting mirror 11 has a reflecting surface 11a, which is the front surface and reflects the laser beam L (light), a back surface 11b, which is the surface opposite to the reflecting surface 11a, and a side surface 11c connecting the reflecting surface 11a and the back surface 11b. A first support member 21 and a second support member 31 are provided on the back surface 11b. In the example of FIG. 2, on the reflecting surface 11a of the reflecting mirror 11, an axis passing through the center 11o of the outer circumferential circle that forms the reflecting mirror 11 is defined as the X-axis, and an axis perpendicular to the X-axis and passing through the center 11o of the outer circumferential circle is defined as the Y-axis. Furthermore, an axis perpendicular to both the X-axis and the Y-axis and passing through the center 11o of the outer circumferential circle is defined as the Z-axis. The positive direction of the Z-axis is the direction from the back surface 11b of the reflecting mirror 11 toward the reflecting surface 11a. The X-axis is an example of the first axis, and the Y-axis is an example of the second axis.

[0014] The first support member 21 is a member that supports the reflecting mirror 11 while being fixed at two first fixing points of the reflecting mirror 11, and has the function of deforming the shape of the reflecting mirror 11 in the ZX plane. The first support member 21 has a plate portion 22 and two fixing members 23 that extend in the Z-axis direction. The plate portion 22 is arranged at a predetermined distance from the back surface 11b of the reflecting mirror 11. The two fixing members 23 are connected to the plate portion 22 and fix the reflecting mirror 11 at the two first fixing points of the reflecting mirror 11. In this example, the two first fixing points are arranged at positions on the X-axis. The plate portion 22 corresponds to the first plate portion. The fixing members 23 correspond to the first fixing members.

[0015] The second support member 31 supports the reflecting mirror 11 while being fixed at two second fixing points different from the first fixing points of the reflecting mirror 11, and has the function of deforming the shape of the reflecting mirror 11 in the YZ plane. The second support member 31 has a plate portion 32 and two fixing members 33 extending in the Z-axis direction. The plate portion 32 is arranged at a predetermined distance from the back surface 11b of the reflecting mirror 11, sandwiching the plate portion 22 of the first support member 21. The two fixing members 33 fix the reflecting mirror 11 at the two second fixing points of the reflecting mirror 11. In this example, the two second fixing points are arranged at positions on the Y-axis. The plate portion 32 corresponds to the second plate portion. The fixing members 33 correspond to the second fixing members.

[0016] The fixing members 23 of the first support member 21 and the fixing members 33 of the second support member 31 are arranged so that a line segment connecting first fixing points, which are positions where the two fixing members 23 of the first support member 21 contact the back surface 11b of the reflecting mirror 11, and a line segment connecting second fixing points, which are positions where the two fixing members 33 of the second support member 31 contact the back surface 11b of the reflecting mirror 11, intersect on the back surface 11b of the reflecting mirror 11. The intersection of the two line segments is preferably at the center 11o of the back surface 11b of the reflecting mirror 11, but does not have to be at the center 11o of the back surface 11b. If the intersection of the two line segments does not coincide with the center 11o of the back surface 11b, the line segment connecting the two first fixing points on the back surface 11b of the reflecting mirror 11 will not be on the X-axis, or the line segment connecting the two second fixing points on the back surface 11b of the reflecting mirror 11 will not be on the Y-axis. However, even in this case, it is desirable that the line segment connecting the two first fixing points on the back surface 11b of the reflecting mirror 11 is parallel to the X-axis, and the line segment connecting the two second fixing points on the back surface 11b of the reflecting mirror 11 is parallel to the Y-axis.

[0017] The adjustment screw 41 is an adjustment member that connects the first support member 21 and the second support member 31 and changes the distance between the first support member 21 and the second support member 31. By expanding or contracting the distance between the first support member 21 and the second support member 31, the force applied in the Z-axis direction at the positions where the fixing members 23 of the first support member 21 and the fixing members 33 of the second support member 31 contact the rear surface 11b of the reflecting mirror 11 changes, thereby deforming the reflecting mirror 11. In other words, the adjustment screw 41 is a member that changes the distance between the first support member 21 and the second support member 31 to adjust the deformation of the reflecting mirror 11. In the example of FIG. 2 , the line segment connecting the positions where the two fixing members 23 of the first support member 21 contact the rear surface 11b of the reflecting mirror 11 corresponds to the X-axis, and the line segment connecting the positions where the two fixing members 33 of the second support member 31 contact the rear surface 11b of the reflecting mirror 11 corresponds to the Y-axis.

[0018] Next, the configuration of the deformable mirror 10 will be described in detail. Fig. 3 is a perspective view that schematically shows an example of the configuration of the deformable mirror according to embodiment 1, disassembled into individual components. In Fig. 3, the X-axis, Y-axis, and Z-axis are the same as those described in Fig. 2. Furthermore, the X1-axis and Y1-axis parallel to the X-axis and Y-axis are provided on the front surface 22a of the plate portion 22 of the first support member 21, and the X2-axis and Y2-axis parallel to the X-axis and Y-axis are provided on the front surface 32a of the plate portion 32 of the second support member 31.

[0019] Reflecting mirror 11 has two screw holes 13x provided on the X-axis at a predetermined distance from center 11o of reflecting mirror 11. Reflecting mirror 11 also has two screw holes 13y provided on the Y-axis at a predetermined distance from center 11o of reflecting mirror 11. Screw holes 13x are located at positions that come into contact with fixing member 23, i.e., first fixing locations, and screw holes 13y are located at positions that come into contact with fixing member 33, i.e., second fixing locations. In the example of FIG. 3, screw holes 13x and 13y penetrate reflecting mirror 11 in the thickness direction.

[0020] The first support member 21 has a plate portion 22, two spacers 24, and two fixing screws 25. The plate portion 22 is a disk-shaped member having approximately the same size as the reflecting mirror 11. The plate portion 22 has a front surface 22a that faces the reflecting mirror 11, a back surface 22b that is the surface opposite the front surface 22a, and a side surface 22c that connects the front surface 22a and the back surface 22b. The plate portion 22 has an adjustment screw hole 221 near its center. The thread pitch of the adjustment screw hole 221 is a first pitch. One end of an adjustment screw 41 is screwed into the adjustment screw hole 221. It is to be noted that the adjustment screw hole 221 is ideally located near the center of the plate portion 22, but it may be located at a position other than near the center.

[0021] Plate portion 22 has two through holes 222x provided at positions on the X1 axis a predetermined distance from the center of plate portion 22, and protrusions 26 provided on the side surfaces 22c of plate portion 22, i.e., on the outer periphery, of the two through holes 222x, adjacent to through holes 222x. In the example of FIG. 3, protrusions 26 are provided on front surface 22a of plate portion 22. Fixing screws 25 are inserted through through holes 222x. Through holes 222x are provided in plate portion 22 so that they coincide with the positions of screw holes 13x of reflecting mirror 11 when the center of plate portion 22 of first support member 21 and the center 11o of reflecting mirror 11 are aligned.

[0022] The plate portion 22 has two through holes 222y provided on the Y1 axis at positions a predetermined distance from the center of the plate portion 22. A spacer 34 constituting the second support member 31 is inserted into the through holes 222y. The through holes 222y are provided in the plate portion 22 so that the positions of the screw holes 13y of the reflecting mirror 11 coincide with the positions of the screw holes 13y of the reflecting mirror 11 when the center of the plate portion 22 of the first support member 21 and the center 11o of the reflecting mirror 11 are aligned.

[0023] The spacer 24 is a cylindrical member that is disposed between the rear surface 11b of the reflecting mirror 11 and the front surface 22a of the plate portion 22 at the position of the through-hole 222x of the plate portion 22, and that provides a predetermined distance between the front surface 22a of the plate portion 22 and the rear surface 11b of the reflecting mirror 11. The spacer 24 is disposed so as to come into contact with a protrusion 26 that is provided adjacent to the through-hole 222x of the plate portion 22. The protrusion 26 is provided on the outer periphery of the plate portion 22 on the spacer 24. The spacer 24 has a hollow portion through which the fixing screw 25 can be inserted in the Z-axis direction. In the example of FIG. 3, the spacer 24 is cylindrical, but it may have another shape, such as a rectangular tube.

[0024] Fixing screw 25 is inserted from the rear surface 22b side of plate portion 22 into the hollow portion of spacer 24 arranged between plate portion 22 and reflecting mirror 11 at the position of through hole 222x of plate portion 22, and is screwed into threaded hole 13x in rear surface 11b of reflecting mirror 11, thereby fixing reflecting mirror 11. Spacer 24 and fixing screw 25 correspond to fixing member 23.

[0025] The protrusions 26 are provided so as to come into contact with the fixing members 23 when the deformable mirror 10 is assembled. More specifically, the protrusions 26 come into contact with the spacers 24.

[0026] The protrusions 26 may be integral with the plate portion 22 of the first support member 21, or may be provided by post-processing such as bonding, welding, or additive manufacturing (AM). FIG. 4 is a perspective view schematically illustrating an example of the configuration of the first support member of the deformable mirror according to the first embodiment. As shown in FIG. 4, the protrusions 26 may be provided by cutting the periphery of the through-hole 222x of the plate portion 22 of the first support member 21 so as to leave the protrusions 26, and forming grooves 27. It is desirable that the grooves 27 are machined on the front surface 22a of the plate portion 22 so as to extend to the side surface 22c on the outer periphery of the plate portion 22. In the example of FIG. 4, the protrusions 26 are arranged in an island shape adjacent to the through-hole 222x in the region between the through-hole 222x and the side surface 22c. In the example of FIG. 4, the protrusions 26 have a prismatic shape. The grooves 27 correspond to the first grooves. The first groove is provided in an area including an area where the fixing member 23 is to be disposed, leaving the protrusion 26 uncovered.

[0027] Fig. 5 is a perspective view schematically showing another example of the configuration of the first support member of the deformable mirror according to embodiment 1. In Fig. 4, island-shaped protrusions 26 are arranged on the side surface 22c of plate portion 22 of first support member 21 in through-hole 222x, but in Fig. 5, beam-shaped protrusions 26 are arranged to connect the end of through-hole 222x on the side surface 22c side of plate portion 22 to side surface 22c. In the cases of Figs. 4 and 5, the area and shape of groove 27 are determined so that the step portion of groove 27 does not come into contact with fixing member 23 after deformable mirror 10 is assembled.

[0028] The protrusions 26 may be island-shaped as shown in Fig. 4, or may be elongated beam-shaped or rod-shaped as shown in Fig. 5. The shape of the protrusions 26 may be cylindrical, rectangular parallelepiped, prismatic, or another three-dimensional shape. However, if the cross-sectional area perpendicular to the Z axis is too small, stress concentration occurs, leading to creep deformation. Therefore, a three-dimensional shape with a cross-sectional area that can avoid creep deformation is preferable to a needle-like structure with a small cross-sectional area.

[0029] It is desirable that protrusion 26 is located on a straight line connecting two through-holes 222x. The surface of protrusion 26 that comes into contact with fixing member 23 is desirably a flat surface, but may be a rounded surface or a hemispherical surface. It is also desirable that the edge of protrusion 26 is chamfered.

[0030] Returning to FIG. 3 , the second support member 31 includes a plate portion 32, two spacers 34, and two fixing screws 35. The plate portion 32 is a disk-shaped member having approximately the same size as the reflecting mirror 11. The plate portion 32 includes a front surface 32a that faces the first support member 21, a back surface 32b that is the surface opposite the front surface 32a, and a side surface 32c that connects the front surface 32a and the back surface 32b. The plate portion 32 includes an adjustment screw hole 321 near the center. The thread pitch of the adjustment screw hole 321 is a second pitch that is different from the first pitch. The relationship between the first pitch and the second pitch is not limited. However, in the first embodiment, for convenience of explanation, the second pitch is assumed to be larger than the first pitch. The other end of the adjustment screw 41 is threaded into the adjustment screw hole 321. It is ideal that the adjustment screw hole 321 is located near the center of the plate portion 32, but it may be located at a position other than near the center. However, the X and Y coordinates of the adjustment screw hole 221 of the first support member 21 and the X and Y coordinates of the adjustment screw hole 321 of the second support member 31 must match.

[0031] The plate portion 32 has two through holes 322 provided at positions on the Y2 axis at a predetermined distance from the center of the plate portion 32, and protrusions 36 provided at positions adjacent to the through holes 322 on the side surface 32c of the plate portion 32 of the second support member 31, i.e., on the outer periphery. In the example of FIG. 3 , the protrusions 36 are provided on the front surface 32a of the plate portion 32. Fixing screws 35 are inserted into the through holes 322. The through holes 322 are provided in the plate portion 32 so that when the center of the plate portion 32 of the second support member 31, the center of the plate portion 22 of the first support member 21, and the center 11o of the reflector 11 are aligned, the positions of the screw hole 13y of the reflector 11 and the through hole 222y of the first support member 21 coincide with each other.

[0032] The spacer 34 is a cylindrical member that is disposed between the rear surface 11b of the reflecting mirror 11 and the front surface 32a of the plate portion 32 at the position of the through-hole 322 of the plate portion 32, and that provides a predetermined distance between the front surface 32a of the plate portion 32 and the rear surface 11b of the reflecting mirror 11. The spacer 34 is disposed so as to come into contact with a protrusion 36 that is provided adjacent to the through-hole 322 of the plate portion 32. The protrusion 36 is provided on the outer periphery of the plate portion 32 on the spacer 34. The spacer 34 has a hollow portion through which the fixing screw 35 can be inserted in the Z-axis direction. In the example of FIG. 3, the spacer 34 is cylindrical, but it may have another shape, such as a rectangular tube.

[0033] Fixing screw 35 is inserted from the rear surface 32b side of plate portion 32 into the hollow portion of spacer 34 arranged between plate portion 32 and reflecting mirror 11 at the position of through hole 322 of plate portion 32, and is screwed into threaded hole 13y in rear surface 11b of reflecting mirror 11, thereby fixing reflecting mirror 11. Spacer 34 and fixing screw 35 correspond to fixing member 33.

[0034] The protrusions are provided so as to come into contact with the fixing members 33 when the deformable mirror 10 is assembled. More specifically, the protrusions are in contact with the spacers .

[0035] The protrusions 36 may be integral with the plate portion 32 of the second support member 31, or may be provided by post-processing such as bonding, welding, or additive manufacturing. FIG. 6 is a perspective view schematically illustrating an example of the configuration of the second support member of the deformable mirror according to the first embodiment. As shown in FIG. 6, the protrusions 36 may be provided by cutting the periphery of the through hole 322 of the plate portion 32 of the second support member 31 so as to leave the protrusions 36, and then forming grooves 37. It is desirable that the grooves 37 are machined on the front surface 32a of the plate portion 32 so as to extend to the side surface 32c on the outer periphery of the plate portion 32. In the example of FIG. 6, the protrusions 36 are arranged in an island shape adjacent to the through hole 322 in the region between the through hole 322 and the side surface 32c. In the example of FIG. 6, the protrusions 36 have a prismatic shape. The grooves 37 correspond to the second grooves. The second grooves are provided in a region including the region where the fixing member 33 is disposed, leaving the protrusions 36.

[0036] Fig. 7 is a perspective view schematically showing another example of the configuration of the second support member of the deformable mirror according to embodiment 1. In Fig. 6, an island-shaped protrusion 36 is arranged on the side surface 32c of the plate portion 32 of the second support member 31 in the through-hole 322, but in Fig. 7, a beam-like protrusion 36 is arranged to connect the end of the plate portion 32 on the side surface 32c side of the through-hole 322 to the side surface 32c. In the cases of Figs. 6 and 7, the area and shape of the groove 37 are determined so that the step portion of the groove 37 does not come into contact with the fixing member 33 after the deformable mirror 10 has been assembled.

[0037] The protrusions 36 may be island-shaped as shown in Fig. 6, or may be elongated beam-shaped or rod-shaped as shown in Fig. 7. The shape of the protrusions 36 may be cylindrical, rectangular parallelepiped, prismatic, or another three-dimensional shape. However, if the cross-sectional area perpendicular to the Z axis is too small, stress concentration occurs, leading to creep deformation. Therefore, a three-dimensional shape with a cross-sectional area that can avoid creep deformation is preferable to a needle-like structure with a small cross-sectional area.

[0038] It is desirable that the protrusion 36 is located on a straight line connecting the two through holes 322. The surface of the protrusion 36 that comes into contact with the fixing member 33 is desirably a flat surface, but may be a rounded surface or a hemispherical surface. It is also desirable that the edge of the protrusion 36 is chamfered.

[0039] 3, it is preferable that the first support member 21 has the protrusion 26 and the second support member 31 has the protrusion 36, but it is also possible for only one of them to have the protrusion 26. In one example, only the first support member 21 may have the protrusion 26 and the second support member 31 may not have the protrusion 36, or only the second support member 31 may have the protrusion 36 and the first support member 21 may not have the protrusion 26. The protrusion 26 corresponds to the first protrusion, and the protrusion 36 corresponds to the second protrusion.

[0040] Returning to FIG. 3 , the adjustment screw 41 is made longer than the distance between the back surface 22b of the plate portion 22 of the first support member 21 and the front surface 32a of the plate portion 32 of the second support member 31. Male threads 42, 43 are provided on both ends of the adjustment screw 41. The thread pitch of the male thread 42 at the end on the positive side of the Z axis is a first pitch that is the same as the adjustment screw hole 221 provided in the plate portion 22 of the first support member 21, and the pitch of the male thread 43 at the end on the negative side of the Z axis is a second pitch that is the same as the adjustment screw hole 321 provided in the plate portion 32 of the second support member 31. The male thread 42 corresponds to the first male thread, and the male thread 43 corresponds to the second male thread. The male thread 42 of the adjustment screw 41 is screwed into the adjustment screw hole 221 from the back surface 22b of the plate portion 22 of the first support member 21, and the male thread 43 of the adjustment screw 41 is screwed into the adjustment screw hole 321 from the front surface 32a of the plate portion 32 of the second support member 31.

[0041] In Figure 3, an adjustment screw 41 is used in which the diameter of the male thread 42 is smaller than the diameter of the male thread 43. By making the diameters of the male threads 42 and 43 at both ends different in this way, it is possible to reduce the possibility of an operational error such as installing the adjustment screw 41 in the wrong direction. It is also possible to make the diameters of the male threads 42 and 43 at both ends the same, that is, to make the diameters the same. If the diameters are made the same, the manufacturing cost of the adjustment screw 41 can be reduced compared to when the diameters are not made the same.

[0042] Next, an example of a manufacturing method for the deformable mirror 10 will be described with reference to FIG. 3 . First, a step of fixing the reflecting mirror 11 to the first support member 21 is performed. This step corresponds to a first fixing step in which the reflecting mirror 11 and the plate portion 22 of the first support member 21 are fixed to each other by two fixing members 23 so as to maintain a predetermined distance between them. Specifically, a spacer 24 is placed at the position of the screw hole 13x on the back surface 11b of the reflecting mirror 11. After aligning the position of the hollow portion of the spacer 24 with the position of the through hole 222x of the plate portion 22 of the first support member 21, a fixing screw 25 is inserted from the back surface 22b of the plate portion 22 into the through hole 222x of the plate portion 22 and the spacer 24, and the fixing screw 25 is screwed into the screw hole 13x. At this time, the outer periphery of the spacer 24 on the outer periphery side of the plate portion 22 of the first support member 21 comes into contact with the protrusion 26 of the first support member 21. This fixes first support member 21 and reflecting mirror 11. The length of spacer 24 is set in advance so that it comes into contact with reflecting mirror 11 and first support member 21 in this state.

[0043] Next, a step of connecting the adjustment screw 41 to the first support member 21 is performed. Specifically, the male thread 42 of the adjustment screw 41 is screwed into the adjustment screw hole 221 in the back surface 22b of the plate portion 22 of the first support member 21. In addition, the spacer 34 is inserted into the through hole 222y of the plate portion 22 of the first support member 21 from the back surface 22b side of the first support member 21. At this time, the outer periphery of the spacer 34 on the outer periphery side of the plate portion 32 of the second support member 31 comes into contact with the protrusion 36 of the second support member 31.

[0044] Thereafter, a step of connecting the adjustment screw 41 to the second support member 31 is performed. Specifically, the male thread 43 of the adjustment screw 41 is screwed into the adjustment screw hole 321 on the front surface 32a of the plate portion 32 of the second support member 31. At this time, the plate portion 32 of the second support member 31 is rotated so that the through hole 322 of the plate portion 32 of the second support member 31 coincides with the position of the hollow portion of the spacer 34. The step of connecting the adjustment screw 41 to the first support member 21 and the step of connecting the adjustment screw 41 to the second support member 31 correspond to a connecting step of connecting an adjustment member that changes the distance between the plate portion 22 and the plate portion 32.

[0045] Subsequently, a step of fixing the reflecting mirror 11 to the second support member 31 is performed. This step corresponds to a second fixing step in which the reflecting mirror 11 and the plate portion 32 of the second support member 31 are fixed with two fixing members 33 so that a predetermined distance is maintained between them with the plate portion 22 sandwiched therebetween. Specifically, a fixing screw 35 is inserted into the through hole 322 from the rear surface 32b side of the plate portion 32 of the second support member 31. The fixing screw 35 reaches the threaded hole 13y in the rear surface 11b of the reflecting mirror 11 via the spacer 34. The fixing screw 35 is then screwed into the threaded hole 13y of the reflecting mirror 11. The length of the spacer 34 is preset so that it contacts the reflecting mirror 11 and the second support member 31 in this state. This fixes the second support member 31 and the reflecting mirror 11. In this manner, the structure of the deformable mirror 10 shown in FIG. 2 is obtained.

[0046] In the above manufacturing method, when reflecting mirror 11 is fixed to first support member 21 with fixing screw 25 and reflecting mirror 11 is fixed to second support member 31 with fixing screw 35, a force in the -Z direction is generated at the positions of screw holes 13x and 13y of reflecting mirror 11. Furthermore, when spacer 24 comes into contact with protrusion 26 of first support member 21 and spacer 34 comes into contact with protrusion 36 of second support member 31, a force in the +Z direction is generated at protrusions 26 and 36. In this way, the force generated by contact of spacers 24 and 34 with protrusions 26 and 36 can suppress torsional deformation of reflecting mirror 11. Furthermore, in the first embodiment, protrusion 26 is located on the outer periphery of plate portion 22 of first support member 21 at a position on plate portion 22 corresponding to screw hole 13x, and protrusion 36 is located on the outer periphery of plate portion 32 of second support member 31 at a position on plate portion 32 corresponding to screw hole 13y. That is, the position where the force in the -Z direction acts is closer to the center 11o of reflecting mirror 11 than the position where the force in the +Z direction acts via spacers 24 and 34. As a result, the deformed shape of reflecting mirror 11 becomes a concave spherical shape with center 11o recessed in the negative direction of the Z axis.

[0047] FIG. 8 is a contour diagram showing an example of the surface shape of the reflecting mirror when the deformable mirror according to embodiment 1 is assembled. In this diagram, the position in the Z-axis direction at each position on the reflecting surface 11a when the reflecting surface 11a is viewed from the positive direction of the Z axis is indicated by hatching, and in one example, the displacement from when the reflecting surface 11a is flat is indicated. As shown in FIG. 8, the surface shape of the reflecting mirror 11 when the deformable mirror 10 is assembled can be controlled to a concave spherical shape. In addition, the amount of deformation due to torsion on the reflecting surface 11a of the reflecting mirror 11 can be controlled to be small.

[0048] If the manufacturing method for the deformable mirror 10 includes other processes, such as a polishing process for polishing the reflecting surface 11a of the reflecting mirror 11 or a reflective film forming process for forming a reflective film on the reflecting surface 11a of the reflecting mirror 11, it is desirable that the surface shape of the reflecting surface 11a after the other processes be a convex spherical shape. That is, it is desirable that the reflecting surface 11a of the reflecting mirror 11 be a convex spherical shape when not fixed by the fixing members 23 and 33. FIG. 9 is a contour diagram showing an example of the surface shape of a reflecting mirror in the manufacturing method for the deformable mirror according to the first embodiment. As with FIG. 8, this diagram also uses hatching to indicate displacement in the Z-axis direction at each position on the reflecting surface 11a when viewed from the positive direction of the Z-axis. As shown in FIG. 9, by controlling the surface shape of the reflecting surface 11a to be a convex spherical shape, it is possible to cancel out the concave spherical shape when the deformable mirror 10 is assembled, specifically, when the reflecting mirror 11 is fixed to the first support member 21 and the second support member 31 by the fixing screws 25 and 35. That is, the convex spherical shape of reflecting mirror 11 before assembly is corrected by deformation to a concave spherical shape when reflecting mirror 11 is fixed using fixing screws 25, 35. This makes it possible to obtain an ideal, distortion-free reflecting surface 11a. As a result, the wavefront aberration of laser beam L reflected by reflecting surface 11a is not aggravated, and processing quality can be improved.

[0049] Next, the operation of the deformable mirror 10 having such a structure will be described. In the deformable mirror 10 assembled as shown in FIGS. 2 and 3, the adjustment screw 41 is rotated clockwise as viewed from the negative side of the Z axis. FIG. 10 is a contour diagram showing an example of deformation of the reflecting mirror of the deformable mirror according to embodiment 1. FIG. 10 illustrates the deformation of the reflecting mirror 11 when the adjustment screw 41 is rotated clockwise in the deformable mirror 10 shown in FIG. 2. As with FIG. 8, this diagram also uses hatching to indicate displacement in the Z axis direction at each position on the reflecting surface 11a when viewed from the positive side of the Z axis. Because the second pitch, which is the thread pitch of the second support member 31, is larger than the first pitch, which is the thread pitch of the first support member 21, rotating the adjustment screw 41 clockwise widens the gap between the plate portion 22 of the first support member 21 and the plate portion 32 of the second support member 31 compared to before the adjustment screw 41 was rotated. A force in the +Z direction acts on reflecting mirror 11 at the position where it contacts fixing member 23 of first support member 21, and a force in the -Z direction acts on reflecting mirror 11 at the position where it contacts fixing member 33 of second support member 31. As a result, the surface shape of reflecting mirror 11 becomes a saddle shape that is concave on the ZX cross section and convex on the YZ cross section, as shown in Fig. 10.

[0050] 2 and 3, the adjustment screw 41 is rotated counterclockwise as viewed from the negative direction of the Z axis. FIG. 11 is a contour diagram showing an example of deformation of the reflecting mirror of the deformable mirror according to embodiment 1. FIG. 11 shows the deformation of the reflecting mirror 11 when the adjustment screw 41 is rotated counterclockwise in the deformable mirror 10 shown in FIG. 2. As with FIG. 8, this diagram also uses hatching to indicate displacement in the Z axis direction at each position on the reflecting surface 11a when viewed from the positive direction of the Z axis. Because the second pitch, which is the thread pitch of the second support member 31, is larger than the first pitch, which is the thread pitch of the first support member 21, rotating the adjustment screw 41 counterclockwise narrows the gap between the plate portion 22 of the first support member 21 and the plate portion 32 of the second support member 31 compared to before the adjustment screw 41 was rotated. A force in the -Z direction acts on reflecting mirror 11 at the position where it contacts fixing member 23 of first support member 21, and a force in the +Z direction acts on reflecting mirror 11 at the position where it contacts fixing member 33 of second support member 31. As a result, the surface shape of reflecting mirror 11 becomes a saddle shape that is convex on the ZX cross section and concave on the YZ cross section, as shown in Fig. 11.

[0051] In this way, the surface shape of reflecting mirror 11 of deformable mirror 10 can be deformed into a saddle shape by rotating adjustment screw 41. Therefore, by appropriately setting the orientation when attaching deformable mirror 10 to laser processing apparatus 1, the amount of rotation of adjustment screw 41, and the rotation direction, it is possible to correct the wavefront aberration contained in laser beam L and improve processing quality.

[0052] Next, the effects of the first embodiment will be described in comparison with a case in which the first support member 21 does not have protrusions 26 on the outer periphery of the plate portion 22 adjacent to the through-hole 222x of the plate portion 22, and the second support member 31 does not have protrusions 36 on the outer periphery of the plate portion 32 adjacent to the through-hole 322 of the plate portion 32. When the deformable mirror 10 is assembled without providing protrusions 26 on the outer periphery of the plate portion 22 adjacent to the through-hole 222x of the first support member 21 and without providing protrusions 36 on the outer periphery of the plate portion 32 adjacent to the through-hole 322 of the second support member 31, the surface shape of the reflecting mirror 11 will be irregularly deformed with each assembly. Figures 12 to 15 are contour diagrams showing an example of the surface shape of the reflective surface of the deformable mirror when assembled when there are no protrusions on the outer periphery of the plate portion adjacent to the through-hole of the first support member or the second support member. As in FIG. 8, this figure also uses hatching to indicate displacement in the Z-axis direction at each position on reflecting surface 11a when viewed from the negative direction of the Z-axis. As shown in FIG. 8, it is possible to obtain a concave surface shape, as in the case of embodiment 1, in which protrusions 26 are provided on first support member 21 and protrusions 36 are provided on second support member 31. However, this type of deformable mirror 10 is not always obtained. As shown in FIGS. 12, 13, and 15, a saddle-shaped surface shape may be obtained but with an indeterminate orientation; as shown in FIG. 14, the amount of deformation due to torsion may be large; or the surface may be convex, as shown in FIG. 9. These results are not reproducible, and the exact surface shape of reflecting mirror 11 is unknown until deformable mirror 10 is assembled. In other words, the surface shape of reflecting surface 11a may deform irregularly with each assembly, and the amount of deformation due to torsion may also be large. When such a deformable mirror 10 is applied to the laser processing device 1 shown in FIG. 1, the wavefront aberration of the laser beam L reflected by the reflecting surface 11a worsens, resulting in a decrease in processing quality.

[0053] On the other hand, the deformable mirror 10 of embodiment 1 comprises a reflecting mirror 11 having a reflective surface 11a that reflects light, a first support member 21 that supports the reflecting mirror 11 and has a plate portion 22 arranged at a predetermined distance from the back surface 11b of the reflecting mirror 11 and a fixing member 23 connected to the plate portion 22 and fixing the reflecting mirror 11 at two first fixing points of the reflecting mirror 11, a second support member 31 that supports the reflecting mirror 11 and has a plate portion 32 arranged at a predetermined distance from the back surface 11b of the reflecting mirror 11 across the first support member 21 and a fixing member 33 connected to the plate portion 32 and fixing the reflecting mirror 11 at two second fixing points different from the first fixing points of the reflecting mirror 11, and an adjustment screw 41 that changes the distance between the plate portion 22 and the plate portion 32. Furthermore, first support member 21 has protrusions 26 that contact fixing member 23 fixed to plate 22, and second support member 31 has protrusions 36 that contact fixing member 33 fixed to plate 32. As a result, during assembly of deformable mirror 10, forces generated at the first and second fixing points of reflector 11 where fixing member 23 and fixing member 33 are fixed, as well as forces generated at the contact positions of protrusions 26 of first support member 21 and fixing member 23, and forces generated at the contact positions of protrusions 36 of second support member 31 and fixing member 33, control the deformation of reflector 11 and suppress torsional deformation. This has the effect of controlling the magnitude and shape of distortion generated on reflecting surface 11a and suppressing large distortion. Furthermore, each time deformable mirror 10 is assembled, the surface shape of reflecting surface 11a as shown in FIG. 8 can be reproducibly obtained.

[0054] Furthermore, by bringing protrusion 26 into contact with the outer periphery of plate 22 of first support member 21 of fixed member 23, and bringing protrusion 36 into contact with the outer periphery of plate 32 of second support member 31 of fixed member 33, it is possible to deform reflecting mirror 11 into a concave shape compared to its pre-assembly state when assembling deformable mirror 10. In other words, it is possible to control reflecting mirror 11 into a concave shape.

[0055] In the above description, the reflecting mirror 11 is in the shape of a disk, but it may be in other shapes such as a polyhedron including a rectangular flat plate.

[0056] Furthermore, while FIG. 3 shows a case where the threaded holes 13x and 13y of the reflecting mirror 11 into which the fixing screws 25 and 35 are threaded penetrate the reflecting mirror 11, the threaded holes 13x and 13y do not have to penetrate the reflecting mirror 11. If the threaded holes 13x and 13y penetrate the reflecting mirror 11, it is possible to reduce the thickness of the reflecting mirror 11 and increase the amount of saddle-shaped deformation required to correct astigmatism. However, in this case, the threaded holes 13x and 13y penetrate the reflecting surface 11a of the reflecting mirror 11, and therefore this portion cannot be used as a mirror. On the other hand, if the threaded holes 13x and 13y do not penetrate the reflecting mirror 11, the reflecting surface 11a of the reflecting mirror 11 does not have any through-holes, and therefore the entire reflecting surface 11a of the reflecting mirror 11 can be used as a mirror. In other words, if the threaded holes 13x and 13y do not penetrate the reflecting mirror 11, it is possible to reflect a laser beam L with a larger diameter than if the threaded holes penetrate the reflecting mirror 11.

[0057] The reflecting mirror 11 is fixed to the first support member 21 and the second support member 31 by screwing fixing screws 25, 35 into screw holes 13x, 13y provided in the back surface 11b of the reflecting mirror 11, but an adhesive may also be used when fixing. If an adhesive is used in addition, the torque when fastening the screws can be reduced and the amount of deformation due to assembly can be minimized. Furthermore, if there is no or only a small possibility of creep deformation, the members may be fixed using only an adhesive.

[0058] In the above explanation, the through holes 222x, 222y, 322 provided in the plate portions 22, 32 of the first support member 21 and the second support member 31 are shown to be cylindrical in shape, but they may also be other shapes such as polyhedral shapes, or may have a structure such as a notch.

[0059] In the above description, the first support member 21 supports the reflector 11 while being fixed at two first fixing points on the reflector 11. However, the first support member 21 may support the reflector 11 while being fixed at three or more first fixing points on the reflector 11. That is, when m is an integer greater than or equal to two, the first support member 21 may fix the reflector 11 at m first fixing points on the reflector 11. In the example where the reflector 11 is fixed at three first fixing points, the first fixing points may be arranged so that, when a line connecting two second fixing points is taken as the boundary, a line connecting the centers of the two first fixing points on one side and the one first fixing point on the other side passes through the center 11o of the reflector 11. Furthermore, stable performance can be obtained by arranging the first fixing points at positions that are m-fold symmetric with respect to the center 11o of the reflector 11.

[0060] In the above description, the second support member 31 supports the reflector 11 while being fixed at two second fixing points of the reflector 11. However, the second support member 31 may also support the reflector 11 while being fixed at three or more second fixing points of the reflector 11. That is, when n is an integer greater than or equal to two, the second support member 31 may fix the reflector 11 at n second fixing points of the reflector 11. In the example where the reflector 11 is fixed at three second fixing points, the second fixing points may be arranged so that, when a line connecting two first fixing points is taken as the boundary, a line connecting the centers of two second fixing points on one side and one second fixing point on the other side passes through the center 11o of the reflector 11. Furthermore, stable performance can be obtained by arranging the second fixing points at positions that are n-fold symmetric with respect to the center 11o of the reflector 11.

[0061] m and n may be the same or different. The first and second fixing points are arranged so that they do not overlap and so that they do not have the same angle relative to the X-axis or Y-axis from the center 11o of reflecting mirror 11.

[0062] It is desirable that the two protrusions 26 of the first support member 21 have the same height, but they may be different. If the heights of the two protrusions 26 are different, the lengths of the spacers 24 can be adjusted. Specifically, they are adjusted so that the sum of the heights of the protrusions 26 and the lengths of the spacers 24 is the same. In other words, the length of the spacer 24 with the taller protrusion 26 is shortened. Similarly, it is desirable that the two protrusions 36 of the second support member 31 have the same height, but they may be different. If the heights of the two protrusions 36 are different, the lengths of the spacers 34 can be adjusted. Specifically, they are adjusted so that the sum of the heights of the protrusions 36 and the lengths of the spacers 34 is the same. In other words, the length of the spacer 34 with the taller protrusion 36 is shortened.

[0063] In the above description, an example has been shown in which the protrusion 26 is provided on the front surface 22a of the plate portion 22 of the first support member 21, and the protrusion 36 is provided on the front surface 32a of the plate portion 32 of the second support member 31. However, the position of the protrusion 36 is not limited to this. As an example, the protrusion 26 may be provided on the back surface 22b of the plate portion 22 of the first support member 21, and the protrusion 36 may be provided on the back surface 32b of the plate portion 32 of the second support member 31.

[0064] In order to correct the large astigmatism of laser beam L, the amount of saddle-shaped deformation of reflecting mirror 11 needs to be large, so it is preferable that reflecting mirror 11 be thin. As an example, the thickness of reflecting mirror 11 is desirably 15 mm or less. On the other hand, if reflecting mirror 11 is too thin, deformation due to twisting when fixing members 23, 33 to reflecting mirror 11 will be large, so it is desirably a thickness equal to or greater than a specified value in order to keep this deformation below a specified value. As an example, the thickness of reflecting mirror 11 is desirably 1 mm or more. For the above reasons, the thickness of reflecting mirror 11 is desirably 1 mm or more and 15 mm or less.

[0065] Embodiment 2 In the first embodiment, a deformable mirror 10 was described in which a protrusion 26 is provided at a position on the outer periphery of plate portion 22 of first support member 21 adjacent to through-hole 222x of plate portion 22, a protrusion 36 is provided at a position on the outer periphery of plate portion 32 of second support member 31 adjacent to through-hole 322 of plate portion 32, and fixing members 23, 33 are brought into contact with protrusions 26, 36, respectively, so that reflecting mirror 11 is deformed into a concave shape during assembly compared to its pre-assembly state. In the second embodiment, a deformable mirror 10 is described in which a reflecting mirror 11 is deformed into a convex shape during assembly compared to its pre-assembly state.

[0066] Fig. 16 is a perspective view showing a schematic example of the configuration of a deformable mirror according to embodiment 2 disassembled into its individual components. In Fig. 16, the X-axis, Y-axis, and Z-axis are the same as those described in Fig. 2. Furthermore, X1-axis and Y1-axis parallel to the X-axis and Y-axis are provided on front surface 22a of plate portion 22 of first support member 21, and X2-axis and Y2-axis parallel to the X-axis and Y-axis are provided on front surface 32a of plate portion 32 of second support member 31. Furthermore, the same components as those in embodiment 1 are denoted by the same reference numerals, and their description will be omitted. Only the parts different from embodiment 1 will be described.

[0067] In the second embodiment, the first support member 21 has a protrusion 26a provided on the X1 axis at a position adjacent to the through hole 222x, closer to the center of the plate portion 22 than the two through holes 222x. In the example of FIG. 16, the protrusion 26a is provided on the front surface 22a of the plate portion 22. The second support member 31 has a protrusion 36a provided on the Y2 axis at a position adjacent to the through hole 322, closer to the center of the plate portion 32 than the two through holes 322. In the example of FIG. 16, the protrusion 36a is provided on the front surface 32a of the plate portion 32. The protrusions 26a, 36a are provided so as to come into contact with the fixing members 23, 33, i.e., the spacers 24, 34, respectively, when the deformable mirror 10 is assembled. More specifically, the protrusions 26a, 36a are in contact with the spacers 24, 34.

[0068] As described above, when the reflecting mirror 11 is fixed to the first support member 21 with the fixing screw 25 and the reflecting mirror 11 is fixed to the second support member 31 with the fixing screw 35, a force in the -Z direction is generated at the positions of the screw holes 13x and 13y of the reflecting mirror 11. Furthermore, when the spacer 24 comes into contact with the protrusion 26a of the first support member 21 and the spacer 34 comes into contact with the protrusion 36a of the second support member 31, a force in the +Z direction is generated in the protrusions 26a and 36a. In this way, the force generated by the contact of the spacers 24 and 34 with the protrusions 26a and 36a can suppress torsional deformation of the reflecting mirror 11. In the second embodiment, the protrusion 26a is located closer to the center of the plate portion 22 of the first support member 21 as viewed from the through hole 222x, and the protrusion 36a is located closer to the center of the plate portion 32 of the second support member 31 as viewed from the through hole 322. That is, the position where the force in the +Z direction via spacers 24, 34 acts is closer to the center 11o of reflecting mirror 11 than the position where the force in the -Z direction acts. As a result, the deformed shape of reflecting mirror 11 becomes a convex spherical shape with center 11o bulging in the positive direction of the Z axis. The surface shape of reflecting mirror 11 at this time is as shown in Figure 9. In this way, the amount of deformation due to twisting of reflecting surface 11a during assembly of deformable mirror 10 can also be controlled to be small.

[0069] The manufacturing method of the deformable mirror 10 is the same as that described in the first embodiment. However, if the manufacturing method of the deformable mirror 10 includes other processes such as a polishing process or a reflective film deposition process, it is desirable that the surface shape of the reflecting surface 11a after the other processes be a concave spherical shape as shown in FIG. 8. That is, it is desirable that the reflecting surface 11a of the reflecting mirror 11 be a concave spherical shape when it is not fixed by the fixing members 23 and 33. By controlling the surface shape of the reflecting mirror 11 to be a concave spherical shape, it is offset by the convex spherical shape when the deformable mirror 10 is assembled, specifically, when the reflecting mirror 11 is fixed to the first support member 21 and the second support member 31 by the fixing screws 25 and 35. That is, the concave spherical shape of the reflecting mirror 11 before assembly is corrected by the deformation to a convex spherical shape when the reflecting mirror 11 is fixed using the fixing screws 25 and 35. This makes it possible to obtain an ideal, distortion-free reflecting surface 11a. As a result, the wavefront aberration of the laser beam L reflected by the reflecting surface 11a is not aggravated, and the processing quality can be improved.

[0070] The same effects as those of the first embodiment can be obtained with the second embodiment. Furthermore, by bringing the protrusion 26a into contact with the center side of the plate portion 22 of the first support member 21 of the fixed member 23, and bringing the protrusion 36a into contact with the center side of the plate portion 32 of the second support member 31 of the fixed member 33, it is possible to deform the reflecting mirror 11 into a convex shape compared to the state before assembly when assembling the deformable mirror 10. In other words, it is possible to control the reflecting mirror 11 into a convex shape.

[0071] Embodiment 3 In the first embodiment, a deformable mirror 10 was described in which a protrusion 26 is provided at a position on the outer periphery of plate portion 22 of first support member 21 adjacent to through-hole 222x in plate portion 22, a protrusion 36 is provided at a position on the outer periphery of plate portion 32 of second support member 31 adjacent to through-hole 322 in plate portion 32, and fixing members 23, 33 are brought into contact with protrusions 26, 36, respectively, thereby causing reflecting mirror 11 to deform into a concave shape compared to the state before assembly. In the second embodiment, a deformable mirror 10 was described in which a protrusion 26a is provided at a position on the center of plate portion 22 of first support member 21 adjacent to through-hole 222x in plate portion 22, a protrusion 36a is provided at a position on the center of plate portion 32 of second support member 31 adjacent to through-hole 322 in plate portion 32, and fixing members 23, 33 are brought into contact with protrusions 26a, 36a, respectively, causing reflecting mirror 11 to deform into a convex shape compared to the state before assembly, during assembly. In the third embodiment, a deformable mirror 10 will be described in which the reflecting mirror 11 is deformed into a saddle shape during assembly compared to the state before assembly.

[0072] Fig. 17 is a perspective view showing a schematic example of the configuration of a deformable mirror according to embodiment 3 disassembled into its individual components. In Fig. 17, the X-axis, Y-axis, and Z-axis are the same as those described in Fig. 2. Furthermore, X1-axis and Y1-axis parallel to the X-axis and Y-axis are provided on front surface 22a of plate portion 22 of first support member 21, and X2-axis and Y2-axis parallel to the X-axis and Y-axis are provided on front surface 32a of plate portion 32 of second support member 31. Furthermore, the same components as those in embodiment 1 are denoted by the same reference numerals, and their description will be omitted. Only the parts different from embodiment 1 will be described.

[0073] In the third embodiment, the first support member 21 has protrusions 26b provided on the X1-axis at positions adjacent to the two through holes 222x on the side surface 22c of the plate portion 22. In the example of FIG. 17, the protrusions 26b are provided on the front surface 22a of the plate portion 22. The second support member 31 has protrusions 36b provided on the Y2-axis at positions adjacent to the two through holes 322 on the center side of the plate portion 32. In the example of FIG. 17, the protrusions 36b are provided on the front surface 32a of the plate portion 32. That is, the positions of the protrusions 26b and 36b are different between the through holes 222x of the first support member 21 arranged on the X1-axis and the through holes 322 of the second support member 31 arranged on the Y2-axis. The protrusions 26b and 36b are provided so as to come into contact with the fixing members 23 and 33, that is, the spacers 24 and 34, respectively, when the deformable mirror 10 is assembled.

[0074] FIG. 18 is a contour diagram showing an example of deformation of the reflecting mirror of the deformable mirror according to embodiment 3. As with FIG. 8, this diagram also uses hatching to indicate displacement in the Z-axis direction at each position on reflecting surface 11a when viewed from the positive direction of the Z axis. FIG. 18 shows deformation of reflecting mirror 11 when adjusting screw 41 is rotated counterclockwise when viewed from the negative direction of the Z axis after assembling deformable mirror 10 shown in FIG. 17. As described above, when reflecting mirror 11 is fixed to first support member 21 with fixing screw 25 and reflecting mirror 11 is fixed to second support member 31 with fixing screw 35, a force in the −Z direction is generated at the positions of screw holes 13x and 13y of reflecting mirror 11. Furthermore, when spacer 24 comes into contact with protrusion 26b of first support member 21 and spacer 34 comes into contact with protrusion 36b of second support member 31, a force in the +Z direction is generated at protrusions 26b and 36b. In this way, the force generated by the contact of the spacers 24, 34 with the protrusions 26b, 36b can suppress the occurrence of torsional deformation of the reflecting mirror 11. In the third embodiment, the protrusions 26b are arranged on the outer periphery of the plate portion 22 of the first support member 21 as viewed from the through hole 222x, and the position where the force in the -Z direction acts is closer to the center 11o of the reflecting mirror 11 than the position where the force in the +Z direction via the spacer 24 acts. Also, the protrusions 36b are arranged on the center side of the plate portion 32 of the second support member 31 as viewed from the through hole 322, and the position where the force in the +Z direction via the spacer 34 acts is closer to the center 11o of the reflecting mirror 11 than the position where the force in the -Z direction acts. As a result, the deformed form of the reflecting mirror 11 has a saddle-shaped surface that is concave on the ZX cross section and convex on the YZ cross section, as shown in FIG.

[0075] In this case, by rotating the adjustment screw 41 counterclockwise as viewed from the negative direction of the Z axis, the displacement amount near the center of the plate portion 32 of the second support member 31 becomes larger than the displacement amount near the center of the plate portion 22 of the first support member 21, and the distance between the plate portion 22 of the first support member 21 and the plate portion 32 of the second support member 31 at the attachment position of the adjustment screw 41 becomes narrower than before the adjustment screw 41 was rotated. A force in the -Z direction acts on the reflecting mirror 11 at the position where the first support member 21 contacts the fixing member 23, and a force in the +Z direction acts on the reflecting mirror 11 at the position where the second support member 31 contacts the fixing member 33. As a result, the saddle-shaped shape shown in FIG. 18 can be deformed into a saddle-shaped shape that is convex on the XZ cross section and concave on the YZ cross section as shown in FIG. 11. In other words, the saddle-shaped shape can be corrected to the shape shown in FIG. 18. This makes it possible to obtain an ideal, distortion-free reflecting surface 11a. Furthermore, by using such a deformable mirror 10 in the laser processing device 1, the wavefront aberration of the laser beam L reflected by the reflecting surface 11a is not aggravated, and processing quality can be improved.

[0076] Note that FIG. 17 shows a configuration example in which protrusion 26b is disposed on the outer periphery of plate portion 22 of first support member 21 as viewed from through hole 222x, and protrusion 36b is disposed on the center side of plate portion 32 of second support member 31 as viewed from through hole 322. However, protrusion 26b may be disposed on the center side of plate portion 22 of first support member 21 as viewed from through hole 222x, and protrusion 36b may be disposed on the outer periphery of plate portion 32 of second support member 31 as viewed from through hole 322. In this case, the surface shape of reflecting mirror 11 becomes a saddle shape as shown in FIG. 11. Then, by rotating adjustment screw 41 clockwise, the surface shape of reflecting surface 11a can be corrected to the saddle shape shown in FIG. 10. This makes it possible to obtain an ideal, distortion-free reflecting surface 11a.

[0077] The same effects as those of the first embodiment can be obtained with the third embodiment. Furthermore, by bringing protrusion 26b into contact with the outer periphery of plate portion 22 of first support member 21 of fixed member 23, and bringing protrusion 36b into contact with the center of plate portion 32 of second support member 31 of fixed member 33, it is possible to deform reflecting mirror 11 into a saddle shape when assembling deformable mirror 10 compared to its state before assembly. In other words, it is possible to control reflecting mirror 11 into a saddle shape.

[0078] Embodiment 4 In the first to third embodiments, the adjustment member is the adjustment screw 41, but in the fourth embodiment, a case will be described in which the adjustment member is configured by a member other than the adjustment screw 41.

[0079] FIG. 19 is a perspective view schematically illustrating an example of the configuration of a deformable mirror according to the fourth embodiment, disassembled into individual components. In FIG. 19, the X-axis, Y-axis, and Z-axis are the same as those described in FIG. 2. Furthermore, the X1-axis and Y1-axis parallel to the X-axis and Y-axis are provided on the front surface 22a of the plate portion 22 of the first support member 21, and the X2-axis and Y2-axis parallel to the X-axis and Y-axis are provided on the front surface 32a of the plate portion 32 of the second support member 31. Furthermore, the same components as those in the first embodiment are denoted by the same reference numerals, and their description will be omitted. Only differences from the first embodiment will be described. In addition, FIG. 19 will be described by taking as an example a case where the fourth embodiment is applied to the configuration of the first embodiment.

[0080] The deformable mirror 10 of the fourth embodiment includes a piezoelectric actuator 45 instead of the adjustment screw 41 of the first embodiment. The piezoelectric actuator 45 is an adjustment member that can expand and contract in the Z-axis direction by applying a voltage. The Z-axis direction corresponds to the arrangement direction of the plate portion 22 of the first support member 21 and the plate portion 32 of the second support member 31. The piezoelectric actuator 45 is disposed between the back surface 22b of the plate portion 22 of the first support member 21 and the front surface 32a of the plate portion 32 of the second support member 31. The piezoelectric actuator 45 is connected to the plate portion 22 of the first support member 21 and the plate portion 32 of the second support member 31 with an adhesive or the like. Although not shown, the piezoelectric actuator 45 is connected via wiring to a control unit that controls the operation of the piezoelectric actuator 45. The piezoelectric actuator 45 expands and contracts in accordance with instructions from the control unit.

[0081] Since the piezo actuator 45 is connected to the plate portion 22 of the first support member 21 and the plate portion 32 of the second support member 31 by adhesive or the like, the plate portions 22, 32 are not provided with adjustment screw holes 221, 321.

[0082] In the deformable mirror 10 configured as described above, when a voltage is applied so that the piezoelectric actuator 45 expands in the Z-axis direction, the gap between the plate portion 22 of the first support member 21 and the plate portion 32 of the second support member 31 becomes wider than before the voltage was applied. As a result, the surface shape of the reflecting mirror 11 deforms into a saddle shape that is concave on the ZX cross section and convex on the YZ cross section, as shown in FIG. 10. Furthermore, when a voltage is applied so that the piezoelectric actuator 45 contracts in the Z-axis direction, the gap between the plate portion 22 of the first support member 21 and the plate portion 32 of the second support member 31 becomes narrower than before the voltage was applied. As a result, the surface shape of the reflecting surface 11a deforms into a saddle shape that is convex on the ZX cross section and concave on the YZ cross section, as shown in FIG.

[0083] Although the case where the fourth embodiment is applied to the configuration of the first embodiment has been described above as an example, the fourth embodiment may also be applied to the configurations of the second and third embodiments.

[0084] In this way, by appropriately setting the orientation when attaching the deformable mirror 10 to the laser processing device 1 and the voltage applied to the piezoelectric actuator 45, it is possible to correct the wavefront aberration contained in the laser beam L and improve the processing quality.

[0085] The fourth embodiment can also achieve the same effect as the first embodiment. Furthermore, using the adjustment screw 41 as the adjustment member as in the first to third embodiments is effective when the astigmatism hardly changes over time, but is difficult to deal with when the astigmatism changes over time. On the other hand, the fourth embodiment uses the piezo actuator 45 as the adjustment member, making it possible to correct astigmatism that changes over time.

[0086] Embodiment 5 In embodiments 1 to 3, the adjustment member is an adjustment screw 41 having male threads 42, 43 at both ends, but in embodiment 5, we will explain the case where the adjustment member is a one-sided adjustment screw having a male thread at one end.

[0087] FIG. 20 is a perspective view schematically illustrating an example of the configuration of a deformable mirror according to embodiment 5, disassembled into individual components. In FIG. 20, the X-axis, Y-axis, and Z-axis are the same as those described in FIG. 2. Furthermore, the X1-axis and Y1-axis parallel to the X-axis and Y-axis are provided on the front surface 22a of the plate portion 22 of the first support member 21, and the X2-axis and Y2-axis parallel to the X-axis and Y-axis are provided on the front surface 32a of the plate portion 32 of the second support member 31. Furthermore, the same components as those in embodiment 1 are denoted by the same reference numerals, and their description will be omitted. Only differences from embodiment 1 will be described. In addition, FIG. 20 will be used to explain an example in which embodiment 5 is applied to the configuration of embodiment 1.

[0088] The deformable mirror 10 of the fifth embodiment has a one-sided adjustment screw 47 having a male thread 48 at only one end, instead of the adjustment screw 41 of the first embodiment. Furthermore, the plate portion 32 of the second support member 31 has a through-hole 321a near the center, rather than an adjustment screw hole 321, through which the one-sided adjustment screw 47 is inserted.

[0089] The one-sided adjustment screw 47 is inserted through the through hole 321a of the plate portion 32 of the second support member 31 from the back surface 32b side and is screwed into the adjustment screw hole 221 of the plate portion 22 of the first support member 21. The adjustment screw hole 221 of the first support member 21 and the through hole 321a of the second support member 31 have the same XY coordinates. Ideally, the adjustment screw hole 221 of the first support member 21 and the through hole 321a of the second support member 31 are located near the centers of the plate portions 22, 32, respectively, but they may be located in other positions. Furthermore, although it is desirable for the through hole 321a of the second support member 31 to be cylindrical, it may be other shapes such as a polyhedral shape, or may have a notched structure.

[0090] In the deformable mirror 10 configured as described above, when the one-side adjustment screw 47 is rotated clockwise as viewed from the negative direction of the Z axis, the gap between the plate portion 22 of the first support member 21 and the plate portion 32 of the second support member 31 narrows. As a result, the surface shape of the reflecting mirror 11 deforms into a saddle shape that is convex on the ZX cross section and concave on the YZ cross section, as shown in Figure 11.

[0091] Although the case where the fifth embodiment is applied to the configuration of the first embodiment has been described above as an example, the fifth embodiment may also be applied to the configurations of the second and third embodiments.

[0092] In this way, by appropriately setting the orientation when attaching the deformable mirror 10 to the laser processing device 1 and the amount of rotation of the one-side adjustment screw 47, it is possible to correct the wavefront aberration contained in the laser beam L and improve the processing quality.

[0093] The fifth embodiment can also achieve the same effects as the first embodiment.

[0094] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or different embodiments may be combined with each other. It is also possible to omit or modify parts of the configurations as long as they do not deviate from the gist of the invention. [Explanation of symbols]

[0095] 1 laser processing device, 2 processing table, 3 laser oscillator, 4 optical unit, 5 mirror, 6 condenser lens, 7 workpiece, 10 deformable mirror, 11 reflecting mirror, 11a reflecting surface, 11b, 22b, 32b back surface, 11c, 22c, 32c side surface, 11o center, 13x, 13y screw hole, 21 first support member, 22, 32 plate portion, 22a, 32a front surface, 23, 33 fixing member, 24, 34 spacer, 25, 35 fixing screw, 26, 26a, 26b, 36, 36a, 36b protrusion, 27, 37 groove, 31 second support member, 41 adjustment screw, 42, 43, 48 male thread, 45 piezo actuator, 47 one-side adjustment screw, 221, 321 Adjustment screw holes, 222x, 222y, 321a, 322 through holes, L laser beam.

Claims

1. a reflector having a reflecting surface that reflects light; a first support member for supporting the reflector, the first support member having a first plate portion disposed at a predetermined distance from the rear surface of the reflector, and a first fixing member connected to the first plate portion and fixing the reflector at m first fixing points of the reflector, where m is an integer of 2 or greater; a second support member for supporting the reflector, the second support member having: a second plate portion disposed at a predetermined distance from the rear surface of the reflector across the first plate portion; and a second fixing member connected to the second plate portion and fixing the reflector at n second fixing points, where n is an integer of 2 or greater, different from the first fixing points of the reflector; an adjustment member that changes the distance between the first plate portion and the second plate portion; Equipped with A deformable mirror characterized by having at least one of a first protrusion portion that contacts the outer periphery of the first fixing member and is provided on the first plate portion of the first support member, and a second protrusion portion that contacts the outer periphery of the second fixing member and is provided on the second plate portion of the second support member.

2. the first support member has the first protrusion, The deformable mirror according to claim 1 , wherein the second support member has the second protrusion.

3. the first protrusion is provided on the outer circumferential side of the first plate portion in a region where the first fixing member is disposed, The deformable mirror according to claim 2 , wherein the second protrusions are provided on an outer periphery of the second plate portion in a region where the second fixing member is disposed.

4. 4. The deformable mirror according to claim 3, wherein the reflecting surface of the reflecting mirror has a convex spherical shape when the reflecting mirror is not fixed by the first fixing member and the second fixing member.

5. the first protrusion is provided on the center side of the first plate portion in a region where the first fixing member is disposed, The deformable mirror according to claim 2 , wherein the second protrusion is provided on the center side of the second plate portion in a region where the second fixing member is disposed.

6. 6. The deformable mirror according to claim 5, wherein the reflecting surface of the reflecting mirror has a concave spherical shape when the reflecting mirror is not fixed by the first fixing member and the second fixing member.

7. the first protrusion is provided on the outer circumferential side of the first plate portion in a region where the first fixing member is disposed, The deformable mirror according to claim 2 , wherein the second protrusion is provided on the center side of the second plate portion in a region where the second fixing member is disposed.

8. the first plate portion has a first groove provided in a region including a region in which the first fixing member is disposed, leaving the first protrusion portion; The deformable mirror according to claim 2 , wherein the second plate portion has a second groove provided in an area including an area where the second fixing member is disposed, leaving the second protrusion.

9. The first groove is connected to a side surface on an outer circumferential side of the first plate portion, The deformable mirror according to claim 8 , wherein the second groove is connected to a side surface on the outer periphery of the second plate portion.

10. the adjustment member is an adjustment screw having a first male thread with a first pitch that is screwed into the first plate portion, and a second male thread with a second pitch that is screwed into the second plate portion, the second male thread having a second pitch that is different from the first pitch; the first plate portion has a screw hole corresponding to the first male screw, The deformable mirror according to claim 1 , wherein the second plate portion has a screw hole corresponding to the second male screw.

11. 2. The deformable mirror according to claim 1, wherein the adjustment member is a piezoelectric actuator that is expandable and contractible in the direction in which the first plate portion and the second plate portion are arranged.

12. the adjustment member is a one-sided adjustment screw having a male thread of a first pitch that is screwed into the first plate portion, the first plate portion has a screw hole corresponding to the male screw, the second plate portion has a through hole through which the one-side adjustment screw is inserted, The deformable mirror according to claim 1, wherein the one-side adjustment screw is inserted through the through-hole of the second plate portion and threaded into the screw hole of the first plate portion.

13. 2. The deformable mirror according to claim 1, wherein when m and n are 2, a line segment connecting two of the first fixing points intersects with a line segment connecting two of the second fixing points.

14. The deformable mirror according to claim 1, characterized in that, when m and n are integers greater than 2, the first fixing point is arranged at a position that is m-fold symmetric with respect to the center of the reflecting mirror, and the second fixing point is arranged at a position that is n-fold symmetric with respect to the center of the reflecting mirror.

15. the first fixing member has a first spacer that provides a predetermined distance between the rear surface of the reflecting mirror and the front surface of the first plate portion, the second fixing member has a second spacer that provides a predetermined distance between the rear surface of the reflecting mirror and the front surface of the second plate portion, 2. The deformable mirror according to claim 1, further comprising at least one of the first protrusion provided so as to contact an outer periphery of the first spacer and the second protrusion provided so as to contact an outer periphery of the second spacer.

16. the first fixing member includes the cylindrical first spacer and a first fixing screw that is inserted through the first spacer and fixes the reflecting mirror; the second fixing member includes the cylindrical second spacer and a second fixing screw that is inserted through the second spacer and fixes the reflecting mirror, the first plate portion has a first through hole through which the first fixing screw is inserted, the second plate portion has a second through hole through which the second fixing screw is inserted, 16. The deformable mirror according to claim 15, further comprising at least one of the first protrusion provided at a position adjacent to the first through hole and the second protrusion provided at a position adjacent to the second through hole.

17. A laser oscillator that emits laser light; an optical unit that focuses the laser light and irradiates the light onto a workpiece; Equipped with 17. A laser processing device, wherein the optical unit comprises a deformable mirror according to claim 1.

18. A first fixing step of fixing a reflector having a reflective surface that reflects light and a first plate portion by m first fixing members, where m is an integer of 2 or more, so as to form a predetermined distance between the reflector and the first plate portion; a second fixing step of fixing the reflecting mirror and the second plate portion by n second fixing members, where n is an integer of 2 or greater, so that the reflecting mirror and the second plate portion are spaced apart by a predetermined distance across the first plate portion; a connecting step of connecting an adjustment member that changes the distance between the first plate portion and the second plate portion; Including, In the first fixing step, an outer circumferential portion of the first fixing member is brought into contact with a first protrusion provided on the first plate portion, In the second fixing step, the outer periphery of the second fixing member is brought into contact with a second protrusion provided on the second plate portion.

19. The first protrusion portion is provided on the outer circumferential side of the first plate portion in an area where the first fixing member is arranged, the second protrusion is provided on the outer circumferential side of the second plate portion in a region where the second fixing member is disposed, the reflecting mirror is used in a state where the reflecting surface is not fixed by the first fixing member and the second fixing member, and the reflecting mirror has a convex spherical shape; 19. The method for manufacturing a deformable mirror according to claim 18, wherein the reflecting mirror is corrected by deforming it into a concave spherical shape that protrudes toward the back surface opposite the reflecting surface due to fixation in the first fixation process and the second fixation process.

20. the first protrusion is provided on the center side of the first plate portion in a region where the first fixing member is disposed, the second protrusion is provided on the center side of the second plate portion in a region where the second fixing member is disposed, the reflecting mirror is used in a state where the reflecting surface is not fixed by the first fixing member and the second fixing member, and the reflecting mirror has a concave spherical shape; 19. The method for manufacturing a deformable mirror according to claim 18, wherein the reflecting mirror is corrected by deforming it into a convex spherical shape that protrudes toward the reflecting surface by fixing in the first fixing step and the second fixing step.

Images