JP2009063887A - Variable curvature mirror and optical apparatus using the variable curvature mirror - Google Patents

Abstract

An object of the present invention is to provide a variable curvature mirror that can change the curvature in a sagittal direction and a meridional direction while having only one drive element.
A reflecting mirror 1 having a reflecting surface 1A on one side, a structural member 2 for fixing a back surface 1B of the reflecting mirror 1 at four locations, one end being fixed near the center of the structural member 2, and the other end being a reflecting mirror Distance changing means 3 fixed to the vicinity of the center of the back surface 1B of the reflector 1, and one axis passing through the center of the back surface 1B within the back surface 1B of the reflector 1 is the X axis, and the back surface is also within the back surface 1B of the reflector 1 The axis passing through the center of 1B and orthogonal to the X axis is defined as the Y axis, and the four locations for fixing the back surface 1B of the reflecting mirror 1 of the structural member 2 are unequally distributed from the X axis and the Y axis, When the distance changing means 3 is driven, the reflecting surface 1 is deformed so that the curvature in the X-axis direction and the curvature in the Y-axis direction of the reflecting surface 1 are different.
[Selection] Figure 3

Description

  The present invention relates to a variable curvature mirror for adjusting a focal length, a beam diameter, or a beam mode in an optical apparatus using a laser beam and the like, and an optical apparatus using the variable curvature mirror.

  In an optical device using a laser beam, for example, a laser processing device, the variable curvature mirror changes the curvature of its reflecting surface, thereby changing the focal length of the entire optical system, the midway of the optical path, or the beam diameter and beam mode at the processing point. Can be adjusted. For example, as disclosed in Patent Document 1, the variable curvature mirror can continuously change the shape of the reflecting surface from a flat surface to a concave surface or a convex surface (a rotationally symmetric simple shape, particularly a spherical shape). .

  In an actual laser processing apparatus, this variable curvature mirror has an incident angle to the variable curvature mirror of 10 ° or less in order to suppress the occurrence of astigmatism during deformation, for example, as disclosed in Patent Document 2. It is used in a state close to normal incidence and vertical reflection. This is because the irregular deformation is in a rotationally symmetric simple shape such as a spherical shape.

  In this way, the rotationally symmetric variable mirror is separated into a plurality of laser beams by using polarized light as disclosed in, for example, Patent Document 3, and then combined again, so that a plurality of mirrors are combined in one optical system. It is difficult to use in a laser processing apparatus through which the laser beam passes. This is because the variable curvature mirror cannot be used in a state close to normal incidence and vertical reflection such as an incident angle of 10 ° or less. As disclosed in Patent Document 3 above, a difference in focal position may occur between the laser beams due to variations in the flatness of optical components through which each of the plurality of laser beams passes. A variable curvature mirror capable of adjusting the focal position is necessary.

  However, since the property of polarization is utilized, the reflecting mirror disposed between the polarizing beam splitter for spectroscopy and the polarizing beam splitter for synthesis has an incident angle of 45 ° and an angle of turning back by reflection of 90 °. Must be placed in If a rotationally symmetric variable curvature mirror is used for this, due to the generated aberrations, for example, when drilling a printed circuit board, the processing quality may be degraded, for example, the hole roundness may be deteriorated.

  In addition to the laser processing apparatus of such an optical system, the reflecting mirror is usually most used at an incident angle of 45 ° and a reflection folding angle of 90 °. This is because both design and manufacture are easy. In order to use a rotationally symmetric variable curvature mirror at an incident angle of 45 °, as shown in the above-mentioned Patent Document 3, a plurality of, for example, two, variable curvature mirrors are used, as shown in FIG. It is necessary to devise the above-mentioned problems such that the directions are twisted by 90 ° to cancel each other's astigmatism. In FIG. 9, reference numeral 10 denotes a rotationally symmetric variable mirror, and reference numeral 11 denotes a laser beam.

  Further, as a variable curvature mirror that is not rotationally symmetric, as disclosed in Patent Document 4, for example, there is a variable curvature mirror that is used for an optical pickup such as a CD or a DVD instead of a laser processing apparatus. In Patent Document 4, it is proposed that (curvature in the sagittal direction) :( curvature in the meridional direction) = 2: 1 under use conditions of an incident angle of 45 °. Then, by changing the curvature between the sagittal direction and the meridional direction, the aberration during deformation is suppressed without using a plurality of curvature variable mirrors.

Japanese Patent Laid-Open No. 9-293915 Japanese Patent No. 30009107 WO2004 / 102111 JP 2007-58921 A

  In the technique disclosed in Patent Document 1, the drive element of the rotationally symmetric variable curvature mirror is one and the control is simple, but the use conditions are limited, such as the incident angle must be 10 ° or less. . On the other hand, the variable-curvature mirror having the curvature changed between the sagittal direction and the meridional direction as disclosed in Patent Document 4 is deformed even under the most used conditions of, for example, an incident angle of 45 ° and a reflection folding angle of 90 °. However, the number of drive elements has increased to four.

  The present invention has been made to solve the above-described problems of the prior art, and obtains a variable curvature mirror capable of changing the curvature in the sagittal direction and the meridional direction while having only one drive element. For the purpose.

  Another object of the present invention is to obtain an optical device using a variable curvature mirror that can change the curvature in the sagittal direction and the meridional direction while having only one drive element.

  The variable curvature mirror according to the present invention includes a reflecting mirror having a reflecting surface on one side, a structural member that fixes the back surface of the reflecting mirror at four locations, one end fixed near the center of the structural member, and the other end Distance changing means fixed near the center of the back surface of the reflecting mirror, and a certain axis passing through the center of the back surface in the back surface of the reflecting mirror is the X axis, and also passes through the center of the back surface in the back surface of the reflecting mirror, and the X axis When the axis perpendicular to the Y axis is defined as the Y axis, and the four portions of the structural member that fix the back surface of the reflecting mirror are unequally distributed from the X axis and the Y axis, and the distance changing means is driven. The reflection surface is deformed so that the curvature in the X-axis direction and the curvature in the Y-axis direction of the reflection surface are different.

  An optical device according to another invention includes a reflecting mirror having a reflecting surface on one side, a structural member that fixes the back surface of the reflecting mirror at four locations, one end fixed near the center of the structural member, and the other end A distance changing means that is fixed in the vicinity of the back surface center of the reflecting mirror, and passing through the back surface center in the back surface of the reflecting mirror, the X axis, and passing through the back surface center in the back surface of the reflecting mirror, The axis orthogonal to the X axis is defined as the Y axis, and the four locations for fixing the back surface of the reflecting mirror of the structural member are unequally distributed from the X axis and the Y axis, and the distance changing means is driven. In this case, a variable curvature mirror that deforms the reflective surface so that the curvature in the X-axis direction and the curvature in the Y-axis direction of the reflective surface are different is used.

  According to the variable curvature mirror of the present invention, there is an effect that the focal length, the beam diameter, and the beam mode can be easily and inexpensively adjusted.

  The optical device according to another invention is advantageous in that it can provide an optical device that can easily adjust the focal length, beam diameter, and beam mode at low cost.

  Preferred embodiments of a variable curvature mirror and an optical apparatus using the variable curvature mirror according to the present invention will be described below with reference to the accompanying drawings.

Embodiment 1 FIG.
FIG. 1 is a diagram for explaining the concept of a variable curvature mirror according to Embodiment 1 of the present invention. The reflecting surface 1A and the back surface 1B of the circular reflecting mirror 1 constituting the variable curvature mirror are circular and are parallel to each other. One axis passing through the center 1E of the back surface 1B of the circular reflecting mirror 1 is defined as the X axis, and the axis passing through the center 1E and orthogonal to the X axis is defined as the Y axis.

  For example, the load is applied in the direction of pushing perpendicularly to the back surface 1B in the vicinity of the four intersections 1D formed by the two shafts 1C, which are distributed at 36.5 ° from the X axis and 53.5 ° from the Y axis. Add A. On the other hand, in the vicinity of the center 1E, the load B is applied in a direction that is perpendicular to the back surface 1B. The reflecting surface 1A of the circular reflecting mirror 1 has a concave shape with a recessed center, but there is a difference in the strength against bending of the circular reflecting mirror 1 in the X-axis direction and the Y-axis direction. The reflecting surface 1A is deformed into a shape in which the ratio of the curvature and the concave curvature in the Y-axis direction is approximately 2: 1. The magnitude of the load B is four times the load A.

  Conversely, when a load A is applied in the pulling direction near the point 1D and a load B is applied in the pushing direction near the center 1E, the reflecting surface 1A has a convex shape with a center and a convex curvature in the X-axis direction. Then, the reflecting surface 1A is deformed into a shape in which the ratio of convex curvatures in the Y-axis direction is approximately 2: 1.

  2 shows the ratio of the curvature in the X-axis direction and the curvature in the Y-axis direction when the angle of the two axes 1C in FIG. It is the figure which showed the change of the curvature of a direction / (curvature of a X-axis direction). From FIG. 2, the ratio of the curvature in the X-axis direction to the curvature in the Y-axis direction is 2: 1, that is, (curvature in the Y-axis direction) / (curvature in the X-axis direction) = 0.5. This is when the distribution angle from the X axis is 36 to 37 ° and the distribution angle from the Y axis is 54 to 53 °.

  As disclosed in Patent Document 4, the circular reflecting mirror 1 is arranged at an incident angle of 45 °, and the X-axis is aligned with the sagittal direction of the circular reflecting mirror 1 and the Y-axis is aligned with the meridional direction. By appropriately adjusting the degree of deformation, it is possible to adjust the focal length of the entire optical system, the beam diameter in the middle of the optical path, or the beam mode at the processing point while suppressing aberrations. The degree of deformation of the circular reflecting mirror 1 is assumed to be about 0.1 to 10 μm with respect to the circular reflecting mirror 1 having a diameter of several tens of millimeters. The present invention can be applied to cases where this degree is larger or smaller than this assumption.

  Next, an assembly diagram for explaining the structure of the variable curvature mirror according to the first embodiment is shown in FIG. In FIG. 3, a structural member 2 is provided on the back surface 1 </ b> B side of the circular reflecting mirror 1. The structural member 2 includes a circular back plate 2A having substantially the same diameter as the circular reflector 1, and four legs 2B standing vertically from the surface of the back plate 2A on the circular reflector 1 side. The lengths of the four legs 2B are the same, and the circular reflecting mirror 1 is screwed, brazed, or bonded to the bottom surface 2C of the four legs 2B near the four points 1D in FIG. Be joined.

  The circular reflecting mirror 1 and the structural member 2 sandwich one piezoelectric actuator 3 which is a distance changing means, and both end surfaces of the piezoelectric actuator 3 are the center 1E (not shown) of the circular reflecting mirror 1 and the back of the structural member 2, respectively. It is joined to the center 2E of the plate 2A.

  The length of the foot 2B is set to be approximately the same as the middle of the movable range of the piezo actuator 3. Accordingly, when the length of the piezo actuator 3 is shortened, a load A in the direction of pushing the circular reflecting mirror 1 near the four points 1D shown in FIG. 1 and a load B in the direction of pulling the circular reflecting mirror 1 near the center 1E. The reflective surface 1A is deformed into a concave shape having a curvature ratio of about 2: 1 in the X-axis direction and the Y-axis direction. On the contrary, if the length is increased, a load A in the direction of pulling near the point 1D and a load B in the direction of pushing near the center 1E can be generated, and the ratio of curvature between the reflection surface 1A in the X-axis direction and the Y-axis direction is about 2: 1. It is transformed into a convex shape.

  Alternatively, in order to make the circular reflecting mirror 1 deformable into both a concave shape and a convex shape, the piezoelectric actuator 3 and the structural member 2 are joined to the circular reflecting mirror 1, and then the piezoelectric actuator 3 is driven so as to be approximately in the middle of the movable range. The reflecting surface 1A of the circular reflecting mirror 1 may be processed into a flat surface such as polishing, grinding, and cutting in the length state.

  The material of the circular reflector 1 and the back plate 2A, the thickness, the material of the foot 2B, the cross-sectional shape, the cross-sectional area, etc. can be selected and set as long as it can be appropriately deformed and is not damaged by the load. Also good. If the rigidity of the structural member 2 is reduced, such as by reducing the thickness of the back plate 2A, the ratio of the deformation of the circular reflecting mirror 1 to the change in distance by the piezo actuator 3 is reduced, and fine deformation control of the circular reflecting mirror 1 is controlled. Can be done. The shape and area of the bottom surface 2C need not be the same as the cross-sectional shape and cross-sectional area of the foot 2B, and can also be appropriately deformed with respect to the load A in the direction in which the circular reflector 1 is pulled in the selected joining method. It is good if the joint surface does not peel off.

  The back plate 2A and the foot 2B of the structural member 2 may be integrally formed, or may be formed of separate parts. Further, the circular reflector 1 and the structural member 2 may be formed from the same material by cutting or the like. Further, the back plate 2A is provided with a hole (not shown) through which wiring for driving the piezoelectric actuator 3 is passed. In the first embodiment, the variable curvature mirror is circular, but it may not be circular.

  Further, as shown in FIG. 4, a circular seat 4 is provided between the circular reflecting mirror 1 and the piezo actuator 3, and both end faces 4A and 4B of the circular seat 4 are joined to the circular reflecting mirror 1 and the piezo actuator 3, respectively. By changing the diameter of the circular seat 4, the shape of the X-axis direction cross section and the Y-axis direction cross section of the reflecting surface 1A during deformation can be changed.

  More preferably, as shown in FIG. 5A, a counterbore process is performed near the center of the circular seat 4 on the surface 4A side, and the circular reflector 1 is joined in an arc shape. Alternatively, as shown in FIG. 5B, three or more legs 4C may be provided on the surface 4A side of the circular seat 4. By doing in this way, the deformation | transformation shape of the circular reflecting mirror 1 can be made into the shape connected more smoothly by the inside and the outside of the diameter of the circular seat 4. FIG.

  FIG. 5 is a diagram showing changes in the cross-sectional shape in the X-axis direction when the ratio (percentage) of the diameter of the circular seat 4 to the circular reflecting mirror 1 is changed using the countersunk processed circular seat 4 of FIG. 6 (a) and the change in the cross-sectional shape in the Y-axis direction are shown in FIG. 6 (b). The deformation amount of the cross section in the X-axis direction is normalized as 1 and illustrated. Thus, by setting the diameter of the circular seat 4 appropriately, the cross-sectional shape can be changed, and in particular, it can be approximated to an ellipse or a circle.

  The circular seat 4 and the foot 4C may be formed integrally or may be formed by joining those formed as separate parts. The circular seat 4 and the circular reflecting mirror 1 may be formed from the same material by cutting or the like. Furthermore, although the circular seat 4 is circular, it may be oval. The above also applies to other embodiments described later.

  Since the piezo actuator 3 can be controlled continuously in time, the focal position can be adjusted even when the focal position must be changed during the processing as disclosed in Patent Document 2. Further, when it is not necessary to control the focal position as disclosed in Patent Document 3 in a time-continuous manner, it is possible to adjust the length of a screw member or the like instead of the piezo actuator 3, and As long as the distance changing means can maintain the length, the focal position can be adjusted using any mechanism. In addition, what used the screw member as a distance change means instead of the piezoelectric actuator 3 is explained in full detail in Embodiment 2 mentioned later.

  As described above, according to the variable curvature mirror according to the first embodiment, the four places fixed to the back surface of the circular reflecting mirror 1 of the structural member 2 are unequally distributed from the X axis and the Y axis, that is, X When the piezoelectric actuator 3 is driven so that the angle is not 45 ° from the axis and the Y-axis, the X-axis direction curvature and the Y-axis direction curvature of the reflecting surface of the circular reflecting mirror 1 are deformed to be different. Thus, even when the incident angle of the circular reflecting mirror 1 is not small, the generated aberration can be suppressed and the focal length, beam diameter, and beam mode of the optical system can be adjusted.

  Further, the four places fixed to the back surface of the circular reflecting mirror 1 of the structural member 2 distribute the circular reflecting mirror 1 from 30 ° to 40 ° from the X axis and 50 ° to 60 ° from the Y axis. The curvature ratio in the X-axis direction and the Y-axis direction can be changed to be approximately 2: 1.

  Further, by using the piezo actuator 3 as the distance changing means, the focal length, beam diameter, and beam mode can be adjusted under real time.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described. In the second embodiment, a screw member is used as the distance changing means instead of the piezo actuator 3 in the first embodiment.

  7 is an assembly diagram for explaining the structure of the variable curvature mirror according to the second embodiment of the present invention. The same or corresponding parts as those in the first embodiment shown in FIG. To do. Instead of the piezo actuator 3 shown in FIG. 4, a screw member 5 provided with male screws having different pitches at both ends is used. In the center of the surface 4B of the circular seat 4, a female screw 4F that is screwed into a screw on one side of the screw member 5 is provided. In addition, a female screw 2F that engages with a screw on the other side of the screw member 5 is provided at the center 2E (not shown) of the back plate 2A.

  Since the male screw pitches at both ends of the screw member 5 are different, the interval between the circular reflecting mirror 1 and the structural member 2 can be changed by rotating the screw member 5 left or right. Thus, as in the case of using the piezo actuator 3, the reflecting surface 1A of the circular reflecting mirror 1 can be deformed into a concave shape or a convex shape in which the ratio of curvature is approximately 2: 1 between the X-axis direction and the Y-axis direction. it can.

  The screw member 5 is designed and manufactured by adjusting the range of motion of the screw member 5 so that it can be deformed as necessary on both the concave and convex sides. As described above, even if the screw member 5 is used, the circular reflecting mirror 1 can be deformed in an uneven manner, and the focal length of the entire optical system, the beam diameter in the middle of the optical path, or the processing point can be adjusted. In addition, since the screw member 5 is used, it is applied when it is not necessary to control the time continuously.

  The screws at both ends of the screw member 5 need only have a predetermined pitch difference, and the pitch difference may be generated by a right screw and a left screw. If the pitch difference is reduced, it becomes easy to finely adjust the unevenness of the circular reflecting mirror 1. Alternatively, the screw member 5 provided with female screws having different pitches on both sides may be used, the male screw may be provided on the circular seat 4 and the structural member 2 side, and the female screw of the screw member 5 may be screwed together.

  As described above, according to the variable curvature mirror according to the second embodiment, the circular or elliptical seat 4 is provided between the circular reflecting mirror 1 and the screw member 5 provided with male screws having different pitches at both ends. The both end surfaces of the seat 4 are fixed to the back surface of the circular reflecting mirror 1 and one end of the screw member 5, respectively, so that the shape of the X-axis direction cross section and the Y-axis direction cross section when the reflecting surface is deformed is more suitable. It can be.

  Furthermore, by using the screw member 5 provided with screws having different pitches on both sides, the focal length, beam diameter, and beam mode can be adjusted more inexpensively.

Embodiment 3 FIG.
Next, a third embodiment of the present invention will be described. In the third embodiment, any of the variable curvature mirrors described in the first or second embodiment is applied to a laser processing apparatus in which a plurality of laser beams are passed through one optical system described in Patent Document 3. The case of applying will be described.

  FIG. 8 is a configuration diagram of a laser processing apparatus showing Embodiment 3 of the present invention. A laser beam L emitted from a laser oscillator 20 is transmitted by a reflecting mirror 21 in the middle of an optical path, and is used for a polarizing beam splitter 22 for spectroscopy. Thus, the laser beam M and the laser beam N are separated.

  The laser beam M is transmitted to the combining polarization beam splitter 26 by the two sets of reflecting mirrors 23, and the laser beam N is transmitted by the galvano mirror 25 that is rotationally driven by the two sets of galvano scanners 24. Further, the laser beam M and the laser beam N are two-dimensionally scanned by a galvano mirror 28 that is rotationally driven by two sets of galvano scanners 27, and are positioned and irradiated on a workpiece 30 by a condenser lens 29. A square range surrounded by a dotted line on the workpiece 30 is a scannable range 31. The workpiece 30 is placed on a table 32, and the table 32 is configured to be movable in a predetermined range in two dimensions by two table drive mechanisms 33 in the X-axis and Y-axis directions.

  Due to variations in the flatness of the polarizing beam splitter 22, the reflecting mirror 23, the galvano mirror 25, and the combining polarizing beam splitter 26, where the optical paths of the laser beam M and the laser beam N are different, There may be a difference in focal position between the laser beams N. Therefore, the variable curvature mirror of either the first embodiment or the second embodiment is applied to one of the two sets of reflecting mirrors 23.

  Since the reflecting mirror 23 has an incident angle of 45 °, the X axis is arranged in the sagittal direction of the variable curvature mirror and the Y axis is arranged in the meridional direction. When the focal position of the laser beam M is farther from the condenser lens 29 than the focal position of the laser beam N, if the variable curvature mirror is deformed into a concave shape, the focal point of the laser beam M is suppressed while suppressing the generated aberration. The position and the focal position of the laser beam N can be matched. Further, when the focal position of the laser beam M is closer to the condenser lens 29 than the focal position of the laser beam N, if the variable curvature mirror is deformed into a convex shape, the laser beam M is suppressed while suppressing the generated aberration. And the focal position of the laser beam N can be matched.

  In the third embodiment, the case where the variable curvature mirror according to any of the first or second embodiment is used in the laser processing apparatus in FIG. 8 is illustrated and described. However, the effect of using the variable curvature mirror is optical. Since it acts on the focal length of the entire system, the beam diameter or beam mode in the middle of the optical path or at the processing point, it can be applied to optical devices other than the laser processing device.

  Further, the laser processing apparatus is not limited to a laser processing apparatus that performs two-dimensional scanning by passing a plurality of laser beams through one optical system. That is, only one laser beam may be used, and the same effect can be obtained even in a laser processing apparatus in which any of the galvano scanners 24 and 27 and the table 32 performs one-dimensional, two-dimensional or three-dimensional scanning or no scanning.

  Further, the laser beam may be any of a single pulse, a plurality of pulses, or continuous oscillation. The processing content is not limited to drilling, and any processing content can be used as long as it can be processed by laser such as cutting, deformation, welding, heat treatment, or marking. Further, any change may be generated in the workpiece as long as it can be generated by a laser such as combustion, melting, sublimation, or discoloration.

  As described above, according to the laser processing apparatus according to the third embodiment, the focal length and the beam in laser processing can be obtained by using the variable curvature mirror of either the first or second embodiment in the processing optical system. Diameter and beam mode can be adjusted.

  The variable curvature mirror and the optical apparatus using the variable curvature mirror according to the present invention can be used for a variable curvature mirror capable of adjusting a focal length, a beam diameter, and a beam mode, and a laser processing apparatus using the variable curvature mirror.

It is a figure explaining the concept of the curvature variable mirror which concerns on Embodiment 1 of this invention. It is the figure which showed the change of the ratio of the curvature of a X-axis direction, and the curvature of a Y-axis direction at the time of changing the angle which distributes from the X-axis and a Y-axis of two axes | shafts in FIG. FIG. 3 is an assembly diagram illustrating the structure of the curvature variable mirror according to the first embodiment. It is an assembly figure at the time of providing a circular seat in the back surface of the circular reflective mirror of the variable curvature mirror by Embodiment 1. FIG. It is a figure which shows Embodiment which changed the shape of the circular seat which concerns on Embodiment 1. FIG. It is the figure which showed a mode that the shape of the X-axis direction cross section and the Y-axis direction cross section changed when the diameter of the circular seat which concerns on Embodiment 1 was changed. It is an assembly drawing explaining the structure of the curvature variable mirror which concerns on Embodiment 2 of this invention. It is a block diagram of the laser processing apparatus which concerns on Embodiment 3 of this invention. It is a figure using two rotationally symmetric curvature mirrors in order to suppress aberration by a conventional device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Circular reflecting mirror 1A Reflecting surface 1B Back surface 1C The intersection 1E which the shaft 1C and the outer periphery circle | round | yen of the back surface 1B formed from the two axes 1D distributed from the X-axis and the Y-axis 2 Center 2 of the back surface 1B Structural member 2A Back plate 2B Foot 2C Foot Bottom 2E Center 2F of back plate 2A Screw hole 3 Piezo actuator 4 Circular seat 4A surface (circular reflector side)
4B side (piezo actuator side)
4C Foot 4F Screw hole 5 Screw member 10 Variable curvature mirror (rotational symmetry)
DESCRIPTION OF SYMBOLS 11 Laser beam 20 Laser oscillator 21 Reflector 22 Polarizing beam splitter 23 Reflector 24, 27 Galvano scanner 25, 28 Galvano mirror 26 Polarizing beam splitter 29 Condensing lens 30 Workpiece 31 Scanable range 32 Table 33 Table drive mechanism A, B Load L, M, N Laser beam

Claims (7)

A reflecting mirror having a reflecting surface on one side, a structural member for fixing the back surface of the reflecting mirror at four locations, one end fixed near the center of the structural member, and the other end fixed near the center of the back surface of the reflecting mirror And a distance changing means,
One axis passing through the back surface center in the back surface of the reflecting mirror is defined as the X axis, and similarly, the axis passing through the back surface center in the back surface of the reflecting mirror and perpendicular to the X axis is defined as the Y axis.
The curvature of the reflecting surface in the X-axis direction when the four positions fixing the back surface of the reflecting mirror of the structural member are unequally distributed from the X-axis and the Y-axis and the distance changing means is driven. The variable curvature mirror, wherein the reflecting surface is deformed so that the curvature in the Y-axis direction is different from that of the Y-axis.   4. The four places that fix the back surface of the reflecting mirror of the structural member are distributed at 30 ° to 40 ° from the X axis, and are distributed at 50 ° to 60 ° from the Y axis. Described curvature mirror.   A circular or elliptical seat is provided between the reflecting mirror and the distance changing means, and both end faces of the seat are fixed to the back surface of the reflecting mirror and one end of the distance changing means, respectively. The variable curvature mirror according to claim 1 or 2.   The variable curvature mirror according to any one of claims 1 to 3, wherein a piezo actuator is used as the distance changing means.   The variable curvature mirror according to any one of claims 1 to 3, wherein a screw member provided with screws having different pitches at both ends is used as the distance changing means.   An optical device using the variable curvature mirror according to claim 1.   The optical device positions, irradiates a single-pulse, multiple-pulse, or continuous-wave laser beam on the surface of the workpiece, and burns, melts, sublimates or discolors the workpiece, and cuts, drills, welds, heat-treats, or The optical apparatus according to claim 6, wherein the optical apparatus is a laser processing apparatus that performs processing such as marking.

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