KR100942085B1 - Shape variable mirror and laser processing apparatus using a shape variable mirror - Google Patents

Abstract

Shape-variable mirrors having a large number of drive elements have a high degree of freedom, but have a complicated structure.

According to the present invention, the reflection mirror 1 having the reflection surface 1A on one side, the first shaft member 4 fixed at two places on the back surface 1B of the reflection mirror 1, and the reflection The second shaft member 5 which has two legs 5B fixed to the rear surface 1B of the mirror 1 and spans the first shaft member 4, the second shaft member 5 and The line change mechanism 2 which changes the distance between the 1st shaft member 4, The line segment which connects the location which fixes the 1st shaft member 4, and the leg 5B of the 2nd shaft member 5 are provided. It is characterized in that the line segments connecting the parts to secure the intersection.

Description

SHAPE VARIABLE MIRROR AND LASER PROCESSING APPARATUS USING A SHAPE VARIABLE MIRROR}

1 is a view for explaining the concept of a shape variable mirror in the first embodiment of the present invention,

2 is an assembly view for explaining the structure of the shape-variable mirror in Embodiment 1 of the present invention;

3 is an assembly view illustrating the structure of a shape variable mirror in Embodiment 2 of the present invention;

4 is an assembly view illustrating a structure of a shape variable mirror in Embodiment 3 of the present invention;

5 is an assembly view for explaining the structure of the shape-variable mirror in the fourth embodiment of the present invention;

6 is an assembly view for explaining the structure of the shape-variable mirror in the fifth embodiment of the present invention;

7 is a view for explaining the concept of a shape variable mirror in the fifth embodiment of the present invention;

8 is an assembly view illustrating the structure of the shape variable mirror in the sixth embodiment of the present invention;

9 is a configuration diagram of a laser machining apparatus in a seventh embodiment of the present invention;

Fig. 10 is a photograph of the workpiece surface punched by the laser processing apparatus when the astigmatism correction is not performed in Example 7 of the present invention;

Fig. 11 is a photograph of a workpiece surface punched by a laser processing apparatus when correction of astigmatism caused by deformation of the shape-variable mirror in Example 7 of the present invention.

Explanation of symbols for the main parts of the drawings

1: circular reflection mirror (reflection mirror) 1A: mirror surface (reflection mirror)

1B: If

1C: Intersection between the outer circumference of the back surface (1B) and the X axis (X axis intersection)

1D: Intersection between the outer circumference of the back surface (1B) and the Y-axis (Y-axis intersection)

2: Piezo Actuator (distance change mechanism)

3: Deformation force generating mechanism 4: X-axis member (1st shaft member)

4A: X axis displacement 4B: X axis leg

4C: Bottom of X-axis leg 4D: Notch

4E: X-axis platen center 4F: Screw hole

5: Y-axis member (second axis member) 5A: Y-axis release plate

5B: Y axis leg 5C: Y axis leg bottom

5E: Y-axis seat center 5F: Screw hole

5G: through hole 6: mirror holder

7: Screw part (distance change mechanism) 8: Screw (distance change mechanism)

9: structural member (first shaft member) 9A: back plate

9B: Leg 9C: Leg Bottom

9D: end 50 on Y axis: laser oscillator

51: laser beam

52: reflection mirror (shape variable mirror) 53: galvanometer

54: galvano scanner mirror

55: condenser lens 56: the workpiece

57: Injectable Range 58: Table

59: table driving device A: load

B: load

The present invention relates to a laser processing apparatus using a shape variable mirror and a shape variable mirror for correcting wavefront distortion, particularly astigmatism, of light waves such as a laser beam.

Shape-variable mirrors compensate for wavefront distortion of light waves and are used in various optical products. For example, in the astronomical telescope, it is used to correct the distortion (aberration) of the wavefront due to the shaking of the atmosphere or the like and to improve the image quality (see Patent Document 1, for example). In addition, optical pickups such as compact discs (CDs) and digital video discs (DVDs) are used to correct aberrations caused by tilting or bending of the disc surface (for example, patent documents). 2). Moreover, in a laser processing machine, it is used to correct the wavefront distortion of the laser beam by the distortion of a lens, a reflection mirror, etc. so that a laser beam with a high roundness and a small spot diameter can be obtained (for example, See Patent Document 1).

Shape-variable mirrors include an integral mirror type (see Patent Document 1, for example) and a split mirror type (see Patent Document 3, for example), both of which drive a plurality of drive elements, such as a Piezo Actuator. The mirror surface shape is changing. It is also reported to use a drive element driven by electrostatic force (see Patent Document 2, for example). Since they have many drive elements, when the degree of freedom of deformation is high and the number of drive elements is large enough, a reflective surface of arbitrary shape can be created, and wavefront distortion of any shape can be corrected.

In order to adjust the focal length and the like of the laser beam, a shape-variable mirror that also applies a force by one drive element from the rear surface to a plate-shaped reflection mirror whose outer circumference is held is also reported (see Patent Document 4).

[Patent Document 1] Japanese Unexamined Patent Publication No. 1995-66463

[Patent Document 2] Japanese Unexamined Patent Publication No. 2005-122878

[Patent Document 3] Japanese Unexamined Patent Publication No. 1993-136509

[Patent Document 4] Japanese Unexamined Patent Publication No. 1997-293915

Since the shape-variable mirror having a large number of drive elements has a high degree of freedom in the method of applying a deformation force, it is possible to create a reflection surface of any shape and has an advantage of high degree of freedom of correction of wavefront distortion. However, the structure is complicated by the large number of driving elements. In the case of the split mirror type, a large number of parts is required in that a large number of mirrors are required, resulting in a complicated structure. Since a large number of parts are required and need to be manufactured precisely, a shape-variable mirror having a large number of drive elements becomes expensive.

Depending on the application, the astigmatism may only need to be corrected without the high degree of freedom of correction of the wavefront distortion. For example, in the processing of cutting, boring, welding, etc. by a laser beam, a reflective mirror or lens constituting a transmission optical path to a laser oscillator or a processing point is used in manufacturing processes such as cutting, grinding, and polishing. In addition, manufacturing errors that cause astigmatism are likely to occur. In the case where the uniaxial direction perpendicular to the optical axis is in the X direction and the direction perpendicular to both the optical axis and the X direction is in the Y direction, astigmatism occurs when the focal length is different from each other in the X and Y directions. The quality of processing is often degraded. If astigmatism can be corrected, the quality in laser processing can be improved.

The shape-variable mirrors exerting a force by one drive element have only been used to change the focal length and the like, and there has been no shape-variable mirror using one drive element for the purpose of correcting the astigmatism of light waves.

An object of the present invention is to obtain a shape variable mirror capable of correcting astigmatism.

The shape-variable mirror according to the present invention comprises a reflective mirror having a reflective surface on one side, a first shaft member fixed at two positions on the rear surface of the reflective mirror, and two legs fixed on the rear surface of the reflective mirror. And a second shaft member that traverses the first shaft member, and a distance changing mechanism that changes the distance between the second shaft member and the first shaft member, and connects a portion to fix the first shaft member. The line segment and the line segment connecting the part which fixes the said leg of a said 2nd shaft member cross | intersect, It is characterized by the above-mentioned.

In addition, a reflective mirror having a reflective surface on one side, a first shaft member fixed at two positions on the rear surface of the reflective mirror, one end is fixed to the first shaft member, and one end is reflected on the other end. A first and second distance changing mechanism fixed to the rear surface of the mirror, and a line segment connecting a portion for fixing the first shaft member and a line connecting a portion for fixing the first and second distance changing mechanism intersect each other; It is characterized by.

Example  One

In FIG. 1, the figure explaining the concept of the shape variable mirror in Example 1 of this invention is shown. The circular reflection mirror 1, which is a reflection mirror, is a plane in which the mirror surface 1A and the rear surface 1B, which are reflection surfaces that reflect light, are circular and parallel to each other. On the back surface 1B, an X axis, which is the first axis passing through the center of the outer circumference circle, and a Y axis, which is a second axis intersecting at the center of the outer circumference circle at right angles to the X axis, are defined. A load A is applied in a direction pushing perpendicularly to the back surface 1B near two X axis intersections 1C, which are intersections of the outer circumferential circle of the back surface 1B and the X axis. On the other hand, in the vicinity of two Y-axis intersections 1D, which are the intersections of the outer circumferential circle of the rear surface 1B and the Y-axis, a load B is applied in the direction of pulling perpendicularly to the rear surface 1B. In this way, the mirror surface 1A of the circular reflection mirror 1 is concave in the center on a straight line parallel to the X axis, and the mirror surface 1A in a saddle shape in which the center protrudes on a straight line parallel to the Y axis. ) Is transformed. Moreover, the magnitude | size of the load A and the load B is the same, and the concave curved shape on the X axis | shaft and the convex curved shape on the Y axis | shaft turn into the same shape in the opposite direction.

When the focal length of the light reflected by the circular reflecting mirror 1 is short in the Y axis, the focal length of the reflected light becomes longer because it is a convex surface on the Y axis, and the focal length of the reflected light because it is a concave surface on the X axis. Becomes shorter. This means reducing the difference between the focal lengths of the X and Y axes. In other words, if the degree of deformation of the saddle shape is properly adjusted, the astigmatism can be corrected by making the focal lengths of the X and Y axes equal. The degree of deformation of the circular reflecting mirror 1 assumes about 0.1-10 micrometers with respect to the circular reflective mirror 1 of several tens of millimeters in diameter. In addition, the present invention can be applied even when the degree of deformation is larger or smaller than this assumed. The Y axis may be convex and the Y axis may be concave.

The assembly drawing explaining the structure of the shape-variable mirror in Example 1 is shown in FIG. The shape-variable mirror in the first embodiment has two places shown in FIG. 1 by one piezo actuator 2 capable of precisely controlling the length by applying a voltage by the inverse piezoelectric effect. The load A in the direction pushing the circular reflection mirror 1 in the vicinity of the X-axis intersection point 1C, and the load B in the direction pulling the circular reflection mirror 1 in the vicinity of the two Y-axis intersections 1D can be generated. . On the back side of the circular reflection mirror 1, there is a deformation force generating mechanism 3 that generates a force for deforming the mirror surface 1A of the circular reflection mirror 1 into a saddle shape. The deformation force generating mechanism 3 is a first shaft member fixed to the rear surface 1B of the circular reflection mirror 1 at two positions corresponding to the vicinity of the X-axis intersection point 1C on the X-axis in FIG. 1. It is fixed to the back surface 1B of the circular reflection mirror 1 at two positions corresponding to the X-axis member 4 and the vicinity of the Y-axis intersection 1D on the Y-axis, and arrange | positions the X-axis member 4 across. It consists of the Y-axis member 5 which is a 2nd axial member to become, and the piezo actuator 2 which is a distance change mechanism arrange | positioned between the X-axis member 4 and the Y-axis member 5, and changes the distance therebetween. . In this manner, the circular reflection mirror 1 can be deformed into a saddle shape by the deformation force generating mechanism 3 having a simple structure that applies force to four points.

The X-axis member 4 is an X-axis back plate 4A having a circular and predetermined thickness of approximately the same diameter as the circular reflection mirror 1, and a circular reflection mirror 1 of the X-axis back plate 4A. It consists of two X-axis legs 4B of the prismatic shape which were erected perpendicularly to the X-axis backplate 4A from the side surface. Since the lengths of the two X-axis legs 4B are the same, in the state fixed to the circular reflection mirror 1, the X-axis release plate 4A is parallel to the circular reflection mirror 1. The shape in the cross section perpendicular | vertical to the longitudinal direction of the X-axis leg 4B is substantially square, and is made into the same cross-sectional shape in a longitudinal direction. The bottom face of the X-axis leg 4B is called X-axis leg bottom surface 4C. The two X-axis legs 4B are at the end of the X-axis back plate 4A, and the line segments connecting the centers of the two X-axis leg bottoms 4C pass through the center of the X-axis back board 4A. Here, the straight line which connects the center of two X-axis leg bottom surfaces 4C becomes an X-axis. A notch 4D for passing the Y-axis member 5 is provided near the intersection of the Y-axis perpendicular to the X-axis and the outer circumferential circle passing through the center of the X-axis release plate 4A. The X-axis release plate 4A and the X-axis leg 4B may be formed integrally, or may be a joint formed of a separate component. The X-axis member 4 and the circular reflection mirror 1 may be formed of the same material by cutting or the like. The same applies to the Y-axis member 5.

The X-axis leg bottom surface 4C is a plane perpendicular to the X-axis leg 4B and has a substantially square shape. The two X-axis leg bottom surfaces 4C have the fixed surface peeled off by a tensile force by a suitable method such as screwing, brazing, or bonding with an adhesive to the rear surface 1B of the circular reflecting mirror 1. It is fixed so that nothing happens. Note the same thing in the fixing method in another place.

The Y-axis member 5 is the same shape as the X-axis member 4, and is comprised from the Y-axis back plate 5A and the two Y-axis legs 5B. Two Y-axis leg bottom surfaces 5C of the Y-axis member 5 are fixed to the rear surface 1B of the circular reflection mirror 1. The point where the shape of the Y-axis member 5 differs from the X-axis member 4 is the following two points. (1) The length of the Y-axis leg 5B is longer than the X-axis leg 4B. (2) The Y-axis backplate 5A has no notch. The straight line connecting the center of two Y-axis bridge bottom surfaces 5C is called Y-axis. Moreover, since the straight line which ties the center of the two notches 4D of the X-axis release plate 4A is orthogonal to the X-axis, it is prescribed | regulated from the two Y-axis legs 5B which enter each of these two notches 4D one by one. The Y axis is orthogonal to the X axis.

Here, with respect to the X-axis separating plate 4A and the Y-axis separating plate 5A, the first surface and the second surface are defined as follows. A 1st surface shall be a surface on the opposite side to the circular reflection mirror 1 side. A 2nd surface shall be a surface in the back surface side of a 1st surface. The piezoelectric actuator 2 includes the X-axis platen center 4E (not shown) of the first surface of the X-axis platen 4A and the Y-axis platen center 5E of the second surface of the Y-axis platen 5A. Each end is fixed. Since both the X-axis backbone center 4E and the Y-axis backbone center 5E are in a straight line perpendicular to the circular reflection mirror 1 past the center of the circular reflection mirror 1, the piezo actuator 2 also has On a straight line. That is, the piezo actuator 2 changes the distance of the both ends on the straight line perpendicular to the circular reflection mirror 1.

The difference between the length of the X-axis leg 4B and the Y-axis leg 5B is such that the length of the piezo actuator 2 is equal to the length when it is approximately in the middle of the changeable range. A predetermined voltage is applied to the piezo actuator 2 so that the length of the piezo actuator 2 is equal to the difference between the lengths of the X-axis legs 4B and Y-axis legs 5B. 4C and the Y-axis leg bottom surface 5C are fixed to the back surface 1B of the circular reflection mirror 1. In this case, when the length of the piezo actuator 2 is increased, the mirror surface 1A is deformed into a saddle shape by concave on the X axis and convex on the Y axis, and when the length of the piezo actuator 2 is short, it is convex on the X axis. Concave in the Y axis, the mirror surface 1A is deformed into a saddle shape.

The shape and size of the cross section of the X-axis leg 4B and the thickness of the X-axis back plate 4A are appropriately adjusted so that the strength which is not broken by the applied force is obtained. In addition, the shape and the area of the bottom surface 4C of the X-axis leg can be fixed to the rear surface 1B of the circular reflection mirror 1, the saddle shape can be appropriately modified, and the tensile force on the fixed surface Adjust so that the fixed surface does not peel off. The same applies to the Y-axis back plate 5A and the Y-axis leg 5B, and are adjusted.

The rigidity of the circular reflecting mirror 1, the X-axis member 4, and the Y-axis member 5 allows an appropriate deformation | transformation to occur. When the rigidity of the X-axis member 4 and the Y-axis member 5 is made smaller than that of the circular reflection mirror 1, the ratio of the deformation of the circular reflection mirror 1 to the change of the distance by the distance change mechanism is compared. Becomes small, and control of the fine deformation of the circular reflection mirror 1 becomes easy.

The shape-variable mirror has a cylindrical shape, including the deformation force generating mechanism 3, and is rotatably housed relative to the mirror holder 6 in a cylindrical mirror holder 6 (not shown). For this reason, a shape-variable mirror can be provided at arbitrary rotation angles, and astigmatism can be corrected with better precision. Moreover, the hole (not shown) which passes the wiring for sending electricity which drives the piezo actuator 2 is provided in 5 A of Y-axis transfer plates.

Next, the operation will be described taking the case where the astigmatism of the laser beam of the laser processing apparatus is corrected by the shape variable mirror as an example. Although the structure of a laser processing apparatus is not shown in figure, it is assumed that the shape-variable mirror is provided in the middle of the transmission optical path from a laser oscillator to a processing point. Moreover, also when it applies to other than a laser processing apparatus, astigmatism can be corrected by the same operation.

In the case of astigmatism, the laser beam shape becomes an ellipse. The cylindrical variable mirror is rotated in the mirror holder 6 so that the long or short diameter of the laser beam shape coincides with the X or Y axis of the variable mirror. The length of the piezo actuator 2 is changed by a predetermined amount in the direction of lengthening or shortening. When the laser beam shape is changed to a circle from an ellipse by changing by a predetermined amount, the length of the piezo actuator 2 is changed in the same direction as it is, and the laser beam shape is set to the length that is closest to the circle. When the length of the piezo actuator 2 is changed by a predetermined amount, when the flatness of the laser beam shape is increased, the length of the piezo actuator 2 is changed in the opposite direction so that the laser beam shape is closest to the origin. Set it. At the time of laser processing, a laser beam shape is always monitored, and when it shifts from a source, the length of the piezo actuator 2 is changed and correct | amended so that it may be closest to a source. In addition, closest to the origin means that it is in a state of a predetermined allowable range from the state that is closest to the origin.

In order to explain the effect of being able to adjust the length of the piezo actuator 2 in all directions in the long direction and the short direction from the initial state, the length of the piezo actuator 2 in one direction of the long direction and the short direction from the initial state. The operation in the case where only change can be made will also be described. The cylindrical variable mirror is rotated in the mirror holder 6 so that the long or short diameter of the laser beam shape coincides with the X or Y axis of the variable mirror. When the length of the piezo actuator 2 is changed by a predetermined amount in a direction that can change the length of the piezo actuator 2, the length of the piezo actuator 2 is changed in the same direction as it is when the shape of the laser beam approaches an ellipse. When the length of the piezo actuator 2 is changed by a predetermined amount, when the degree of flatness of the laser beam shape is increased, the length is changed after rotating the shape-variable mirror 90 degrees in the mirror holder 6. The length of the piezo actuator 2 is changed while monitoring the laser beam shape, and the laser beam shape is set to the length closest to the circle.

Since the length of the piezo actuator 2 can be changed from the initial state in all directions in the long direction and the short direction, the shape for correcting the astigmatism is more than in the case where only the one in the long direction and the short direction can be changed. The operation of the variable mirror is simplified. In order to be able to change the length of the piezo actuator 2 from the initial state in all directions in the long direction and the short direction, the piezo actuator 2 and the deformation force generating mechanism 3 are attached to the circular reflection mirror 1, The mirror surface 1A of the circular reflecting mirror 1 may be processed into a plane in a state where the piezo actuator 2 is energized to have an approximately mid length of the adjustable range.

By using the piezo actuator 2, even when the magnitude of the astigmatism changes with time, the piezo actuator 2 can be continuously controlled and the astigmatism can be corrected. If the astigmatism hardly changes with time, the astigmatism is corrected by using any mechanism as long as it is a distance change mechanism capable of adjusting the length such as a screw instead of the piezo actuator 2 and maintaining the length. can do.

Although one distance changing mechanism is used, two or more distance changing mechanisms may be used.

Although the shape-variable mirror is circular here, it may not be circular. Further, there is an advantage that the circularly shaped mirror can be easily rotated so as to align one of two axes in which the shape of the variable mirror is deformed in the direction in which the focal length is at the maximum or minimum.

Although the two axes in which the shape-variable mirrors are deformed are orthogonal, they do not necessarily have to be orthogonal. Even when the two axes to be deformed are not perpendicular to each other, the angle difference between the point where the deformation becomes concave and the convex maximum becomes approximately 90 °, and X is a straight line passing through the point where the deformation becomes concave and maximum. Think of it as the axis, and consider the straight line passing through the point where the deformation is convex to the maximum as the Y axis, and adjust either the X axis or the Y axis to the longer or shorter direction of the shape of the light, By deforming, astigmatism can be corrected.

The intersection between the line connecting the two fixed points of the first shaft member and the line connecting the two fixed points of the second shaft member is positioned at the midpoint of the line segment, but at least one of the segments There may be no intersection at the location. In the case where the intersection point is not at the intermediate point in the line segment connecting the fixed point of the first shaft member, the force acting on both ends of the line segment is determined by the distance from the intersection point so that the rotation moments on both sides of the intersection point are the same. It is proportional to the inverse. The same applies to the fixing position of the second shaft member. In terms of the balance of the forces, the sum of the forces acting on the fixed points of the two first shaft members and the sum of the forces acting on the fixed points of the two second shaft members are equal.

Since the force acting on the fixed position of the first shaft member and the fixed position of the second shaft member is to act perpendicular to the reflecting mirror, the possibility of unnecessary deformation is small. In addition, if the rigidity of the reflection mirror and the deformation force generating mechanism is made large enough so that unnecessary deformation does not occur, the force acting on the fixing position of the first shaft member and the fixing position of the second shaft member is not perpendicular to the reflection mirror. You don't have to. In addition, if a component of a non-vertical force is useful in order to generate a desirable deformation in the shape-variable mirror, the force may be applied in a predetermined non-vertical direction.

Since the piezo actuator 2 is disposed on a straight line perpendicular to the circular reflecting mirror 1 and passing through the intersection of the X and Y axes, it is possible to reduce the unnecessary or obstructive force in order to deform the shape-variable mirror to the desired shape. Can be. If unnecessary or obstructive forces can be reduced or harmless by any means in order to deform the shape-variable mirror to the desired shape, the piezo actuator 2 passes two points on both ends of which change the distance. The straight line does not have to be perpendicular to the reflecting mirror or cross the intersection of the X and Y axes.

As a 1st shaft member and a 2nd shaft member, although the thing of the shape which has two legs in the back plate was used, it may be a shape other than that. The first shaft member may be any as long as the position where one end of the piezo actuator 2 is fixed is disposed at a predetermined position with respect to the fixed position of the first shaft member. The same applies to the second shaft member.

The reflective surface of the reflective mirror may be a predetermined shape suitable for the application such as a convex surface or a concave surface.

The above is also applicable to other Example.

Example  2

This Embodiment 2 is a case where Embodiment 1 is changed so that a screw component may be used as a distance change mechanism instead of a piezo actuator. 3, the assembly drawing explaining the structure of the shape-variable mirror in Example 2 is shown. Compared with FIG. 2 in the case of Example 1, only a different point is demonstrated.

Instead of one piezo actuator, there is one screw part 7 which forms male screws of different pitches at both ends.

In the X-axis platen center 4E (not shown) of the first surface of the X-axis platen 4A, a screw hole 4F having a female screw screwed to one of the screws 7 is provided. ) Is provided so that its center is matched with the X-axis platen center 4E. In the Y-axis platen center 5E (not shown) of the second surface of the Y-axis platen 5A, a screw hole 5F having a female screw for screwing into the other screw of the screw component 7 is provided. The center is provided in accordance with the Y-axis platen center 5E.

The screw part 7 is screwed into the screw hole 4F of the X-axis member 4, the other side of the screw part 7 is screwed into the screw hole 5F of the Y-axis member 5, and the screw part 7 ) In a predetermined direction so that the X-axis leg bottom surface 4C and the Y-axis leg bottom surface 5C are on the same plane, and the screw part 7 is in a position capable of as much rotation as necessary in both directions. Adjust In order to enable such adjustment, the difference between the lengths of the X-axis legs 4B and the Y-axis legs 5B, the length of the screw portions on both sides of the screw component 7, the difference in the pitch of the screws on both sides, The entire length of the screw parts 7 and the like are appropriately produced. In this state, the bottom surface of the X-axis leg 4C and the bottom surface of the Y-axis leg 5C are fixed to the rear surface 1B of the circular reflection mirror 1.

Next, the operation will be described. As in the first embodiment, the long direction or the short diameter of the laser beam shape coincides with the X or Y axis of the shape-variable mirror. The screw component 7 is rotated by a predetermined amount. When the laser beam shape is close to the original from the ellipse, the screw component 7 is rotated in the same direction as it is, and the laser beam shape is set to the length that is closest to the original. When the screw component 7 is rotated by a predetermined amount, when the flatness of the laser beam shape is increased, the screw component 7 is rotated in the opposite direction, and the screw component 7 is positioned to the position where the laser beam shape is closest to the origin. Rotate).

In this manner, even when the screw component is used, the astigmatism of the light reflected by the shape-variable mirror can be corrected by saddle-shaping the shape-variable mirror.

By using the screw component, the structure of the deformation force generating mechanism of the shape-variable mirror is simplified. Moreover, since a screw part is used, it is necessary to apply it to the object which astigmatism hardly changes with time.

The screws on both sides of the screw component 7 may have a predetermined pitch difference, or may create a difference in pitch by a right screw and a left screw. When the difference in pitch is made small, it becomes easy to delicately adjust the saddle shape deformation of the shape-variable mirror. Moreover, you may use the screw component provided with the screw hole from which pitch differs in both sides, and may provide the rod-shaped part which provided the male screw in the X-axis member and the Y-axis member, and insert it into the screw hole of a screw component.

The above is also applicable to other Example.

Example  3

In the third embodiment, the second embodiment is changed to use a normal screw as the distance change mechanism. 4, the assembly drawing explaining the structure of the shape-variable mirror in Example 3 is shown. Only differences from FIG. 3 in the case of the second embodiment will be described.

A conventional screw 8 with a screw formed on one side and a head on the other is used. The Y-axis member 5, which is the member farther from the reflecting mirror, has a through hole 5G having a diameter slightly smaller than the diameter of the screw 8 and smaller than the diameter of the head of the screw 8 instead of the screw hole 5F. It is provided in the center of the shaft back plate 5A. With the X-axis leg bottom surface 4C and the Y-axis leg bottom surface 5C fixed to the rear surface 1B of the circular reflection mirror 1, the screw 8 passes through this through hole 5G, and the X-axis back plate It is screwed into the screw hole 4F which formed the female screw which screwed together with the male screw of the screw 8 provided in the center of (4A). When the back of the head of the screw 8 is brought into contact with the Y-axis back plate 5A and the screw 8 is further turned, the circular reflecting mirror 1 is deformed into a saddle shape.

If the back of the head of the screw 8 and the Y-axis back plate 5A do not come into contact with each other, a force for deforming the reflective mirror to a saddle shape cannot be generated, so that the saddle shape deformation is impossible only in the direction in which the X axis becomes convex. Do.

Next, the operation will be described. As in the first embodiment, the long direction or the short diameter of the laser beam shape coincides with the X or Y axis of the shape-variable mirror. The screw 8 is rotated by a predetermined amount. When the shape of the laser beam approaches the circle from the ellipse, the screw 8 is rotated in the same direction as it is. When the screw 8 is rotated by a predetermined amount, when the flatness of the laser beam shape is increased, the screw 8 is rotated in the same direction after the shape variable mirror is rotated 90 degrees in the mirror holder 6. The screw 8 is rotated while monitoring the shape of the laser beam, and the screw 8 is turned to the position where the laser beam shape is closest to the circle.

As described above, even when a conventional screw is used, the astigmatism of the light reflected by the shape variable mirror can be corrected by deforming the shape variable mirror to a saddle shape.

Example  4

In the fourth embodiment, two piezo actuators are used. 5, the assembly drawing explaining the structure of the shape-variable mirror in Example 4 is shown.

The circular reflecting mirror 1 is the same as in the case of the first to third embodiments. The deformation force generating mechanism 3 is composed of a structural member 9 and two piezo actuators 2. The shape of the structural member 9 is substantially the same as the shape of the X-axis member 4 in the case of Example 1, and has a back plate 9A and two legs 9B. However, there is no notch 4D in the X-axis member 4 in the case of Example 1, and the piezo actuator 2 is fixed to the position where the notch existed. The length of the two legs 9B is the same and is equal to the length when the length of the piezo actuator 2 is approximately in the middle of the changeable range.

The bottom of the leg 9B is called leg bottom 9C. The straight line which connects the center of two leg bottom surfaces 9C is called X-axis, and the straight line orthogonal to the center of X-axis and the back plate 9A is called Y-axis. One end of each piezo actuator 2 is fixed to the end portions 9D of both sides of the back plate 9A on the Y axis. The other end of the piezo actuator 2 and the bottom face 9C of the piezo actuator 2 are circularly reflected mirror 1 while the piezo actuator 2 is energized and the length of the piezo actuator 2 is equal to the leg 9B. On the back surface 1B of the. In addition, the length of the two legs 9B may be the same as the length when the piezo actuator 2 is the shortest, and when doing so, the piezo actuator ( No need to energize 2). However, only the saddle shape deformation which entered the center part in the Y-axis becomes impossible, or it is necessary to grind the mirror surface 1A to the plane in the state which let the piezo actuator 2 energize.

Here, the structural member 9 is a first shaft member, and the piezo actuator 2 is a first and second distance changing mechanism. On the back surface 1B of the circular reflecting mirror 1, the line segment connecting the part which fixes two legs 9B, and the line segment which connects the part to which one end of two piezo actuators 2 are fixed intersect.

Next, the operation will be described. The shape variable mirror can be deformed into a saddle shape by adjusting the length while keeping the restriction that the lengths of the two piezo actuators 2 are the same. Astigmatism can be corrected by appropriately adjusting the degree of saddle shape deformation by matching the direction of the shape-variable mirror with the direction in which astigmatism occurs.

In this way, by using the two piezo actuators 2 to deform the shaping mirror to a saddle shape, the astigmatism of the light reflected by the shaping mirror can be corrected.

Instead of the piezo actuator, a screw component or the like may be used as the distance changing mechanism. As long as one end is fixed to a 1st shaft member, the other end is fixed to the back surface of a reflection mirror, and what kind of thing may be sufficient as it is a distance change mechanism which can change the length.

The above also applies to other embodiments using the first and second distance changing mechanisms.

Example  5

The fifth embodiment is a case where the second embodiment is modified so that the shape-variable mirror is not deformed into a saddle shape but into a columnar shape with a center or recess. 6, the assembly drawing explaining the structure of the shape-variable mirror in Example 5 is shown. Only differences from FIG. 3 in the case of the second embodiment will be described. 7 is a figure for demonstrating the concept of the shape-variable mirror in Example 5. FIG.

The horizontal width of the X-axis leg 4B is long, and the X-axis leg 4B is provided in the part which is not the screw hole 4F on the X-axis. Therefore, since the load A is applied evenly to almost the whole on the X-axis, the displacement becomes the same on a straight line parallel to the X-axis, and the shape-variable mirror is not a saddle shape, but has a center as shown in FIG. 7. It is deformed into a columnar shape. In addition, not only the deformation such that the displacement is the same on the straight line parallel to the Y axis as shown in FIG. 7 and the straight line parallel to the X axis, but also the center enters the X axis on the straight line parallel to the Y axis. The deformation such that the displacement becomes the same on the parallel straight line is also called the deformation in the columnar shape.

Since the X-axis leg 4B is horizontally long, the X-axis leg 4B is fixed to the back surface 1B of the circular reflecting mirror 1 at points other than the screw hole 4F on the X-axis, and the X-axis leg The X-axis member 4 is fixed to the rear surface 1B of the circular reflection mirror 1 even near the intersection with the Y axis of the center of the line segment connecting both ends of 4B. In the case where the X-axis member 4 is not fixed to the intersection with the Y-axis and is deformed into a saddle shape, the vicinity of the intersection with the Y-axis by the load B acting on two fixed points of the Y-axis leg 5B. In comparison with the both ends, the displacement is the largest on the X axis. On the other hand, if the X-axis member 4 is fixed near the intersection with the Y-axis on the X-axis, it can hardly be displaced at this fixed position, so that the displacement on the X-axis and on a straight line parallel to the X-axis is in position. Regardless, they are about the same.

When the focal length of the light reflected by the circular reflecting mirror 1 deformed into the columnar shape is shortened to the Y axis, the focal length of the reflected light becomes longer because it is a convex surface on the Y axis, and the plane is reflected on the X axis. The focal length of the light being made does not change. This means that the difference in the focal length is reduced by bringing the focal length of the Y axis closer to the focal length of the X axis. In other words, if the degree of deformation of the columnar shape is appropriately adjusted, the astigmatism can be corrected by making the focal lengths of the X and Y axes the same.

Also in the fifth embodiment, the point of changing the shape-variable mirror into a columnar shape instead of a saddle shape is different, but operates in the same manner as in the second embodiment.

Thus, by transforming the shape-variable mirror into the columnar shape, the astigmatism of the light reflected by the shape-variable mirror can be corrected.

In addition, a piezo actuator may be used instead of the screw component 7.

Although the X-axis member 4 has two horizontally long X-axis legs 4B, and the force of the same direction was applied to substantially the whole on the X-axis other than the screw hole 4F, either X-axis leg Only 4B may be lengthened horizontally, the number of X-axis legs 4B may be extended, and the X-axis member 4 may be fixed to the back surface of a reflection mirror in three or more places on the X-axis. In addition, at least one place other than the both ends is near the intersection with the Y axis of the center of the line segment connecting the X-axis legs 4B at both ends, that is, in the case of saddle shape deformation so that a difference in displacement hardly occurs on the X axis. On the X-axis near the position where the displacement is greatest compared to both ends. In addition, when the screw hole 4F is unnecessary, you may fix the X-axis member 4 to the back surface of the reflecting mirror in substantially the whole on the X-axis with one linear X-axis leg 4B.

The above is also applicable to other embodiments.

Example  6

In the sixth embodiment, the fourth embodiment is modified to deform the shape-variable mirror into a columnar shape using two piezo actuators. 8, the assembly drawing explaining the structure of the shape-variable mirror in Example 6 is shown. Only differences from FIG. 5 in the case of the fourth embodiment will be described.

There are three legs 9B of the structural member 9, and the legs 9B are fixed to the rear surface 1B of the circular reflecting mirror 1 near the intersection with the central Y axis in addition to both ends on the X axis. In addition, the heights of the legs 9B are all the same. Since there is a leg 9B in the middle, even if the lengths of the two piezo actuators 2 are changed, the displacement becomes substantially the same on a straight line parallel to the X axis, and the shape-variable mirror is deformed into a columnar shape.

Also in the sixth embodiment, by changing the lengths of the two piezo actuators 2, the shape-variable mirror can be deformed into a columnar shape, and by changing into the columnar shape, astigmatism of light reflected by the shape-variable mirror is reflected. Can be corrected.

Example  7

This Example 7 is a case where the shape variable mirror of any one of Examples 1 to 6 is applied to a laser processing apparatus. The structural diagram of a laser processing apparatus is shown in FIG. The laser beam 51 emitted from the laser oscillator 50 is transmitted by the reflecting mirror 52 etc. in the middle of an optical path, and the rotation of the two galvanometer 53 and the galvanometer 53 is performed. It is scanned two-dimensionally by the galvano scanner mirror 54 which is rotationally driven by it, and is positioned and irradiated on the to-be-processed object 56 by the condenser lens 55. As shown in FIG. The range of rectangles enclosed by the dotted lines on the workpiece 56 is the scannable range 57. The workpiece 56 is mounted on the table 58, and the table 58 is movable in a predetermined range in two dimensions by the two table driving devices 59.

In FIG. 10, the photograph of the to-be-processed workpiece surface with the laser processing apparatus in the case of not correcting astigmatism is shown. In the up-down direction in the figure, drilling was performed while changing the focal position at equal intervals in the optical axis direction (moving the condenser lens 55 or the workpiece 56 at equal intervals along the optical axis direction). Since it is difficult to judge the good and bad of processing precision only once, it is implemented in multiple times on the same conditions. Therefore, in FIG. 10, there are a plurality of rows of perforated holes. In Fig. 10, only the first row of the fourth row from the top can be accepted as the laser beam. Whether or not it is acceptable as a laser beam is determined according to a predetermined criterion such as the roundness of the punched hole is, for example, 90% or more.

As the focal position is changed, the processing hole shape is changed from a longitudinally long ellipse to a laterally long ellipse. The shape of the processing hole represents the form of a laser beam spot on the surface of the workpiece. In other words, astigmatism that cannot be ignored is generated in this processing optical system.

For this processing optical system, astigmatism is corrected by using the shape-variable mirror of any one of Examples 1 to 6 as the reflection mirror 52. In the long axis direction or short axis direction of the ellipse of the processing hole shown in FIG. 10, the shape changing mirror is provided so as to align the X-axis or the Y-axis of the shape-variable mirror, and the deformation amount of the shape-variable mirror so that the processing hole of the ellipse is close to the circle. Is controlled according to the driving voltage of the piezo actuator or the amount of rotation of the screw. In this way, after correcting astigmatism, a photograph of a hole in the surface of the workpiece obtained by performing a punching under the same conditions as in FIG. 10 is shown in FIG. In FIG. 11, what can be accepted as a laser beam is the fifth column of the third to seventh rows from above. It can be seen that the astigmatism is reduced and the depth of focus is expanding.

By expanding the depth of focus, stable laser processing can be realized even if there is bending or the like on the surface of the workpiece. Moreover, you may use the mirror in the optical path other than the reflecting mirror 52 as a shape-variable mirror.

In the seventh embodiment, although the laser beam 51 and the table 58 holding the workpiece 56 are also two-dimensionally scanned as shown in FIG. The effect acts on the astigmatism of the processing optical system and does not depend on the scanning method. That is, the same effect is acquired also in the laser processing apparatus in which the laser beam 51, the condenser lens 55, and the table 58 do not scan one-dimensional, two-dimensional, or three-dimensional, or does not scan. The laser beam may be any one of short pulses, multiple pulses, and continuous oscillation. The content of the processing is not limited to drilling, and may be any type as long as it can be processed by laser such as cutting, deformation, welding, heat treatment, or marking. In addition, any change may be made to the workpiece as long as it can be changed by laser such as combustion, melting, sublimation, or discoloration.

By positioning and irradiating a laser beam of short pulse, multiple pulses or continuous oscillation on the workpiece surface, the workpiece is burned, melted, sublimed or discolored, and cut, drilled, deformed, welded, heat treated or marked. In the laser processing apparatus performed, if it is a laser processing apparatus provided with the astigmatism correction mechanism which has a shape variable mirror which can be deformed so that a reflective surface may become a saddle shape or a columnar shape, the astigmatism of a laser beam can be corrected, Machining precision can be improved.

Further, the laser beam of short pulse, plural pulses or continuous oscillation is irradiated on the workpiece surface to burn, melt, sublimate or discolor the workpiece, cutting, drilling, deformation, welding, heat treatment, marking or the like. According to a laser processing method for processing a laser beam, according to a laser processing method for correcting astigmatism of a laser beam by modifying a reflecting mirror in the transmission optical path such that the reflecting surface becomes a saddle shape or a columnar shape, the astigmatism of the laser beam Can be corrected, and the machining accuracy can be improved.

The shape-variable mirror according to the present invention includes a reflective mirror having a reflective surface on one side, a first shaft member fixed at two positions on the rear surface of the reflective mirror, and two legs fixed on the rear surface of the reflective mirror. A line segment comprising a second shaft member that spans the first shaft member, a distance changing mechanism for changing a distance between the second shaft member and the first shaft member, and connecting a portion to fix the first shaft member; Since the line segments connecting the points fixing the legs of the second shaft member intersect, the astigmatism of the light reflected by the reflection mirror is corrected.

In addition, a reflective mirror having a reflective surface on one side, a first shaft member fixed at two positions on the rear surface of the reflective mirror, one end is fixed to the first shaft member, and the other end is fixed to the rear surface of the reflective mirror. Since it is provided with the 1st and 2nd distance changing mechanism which becomes, and the line segment which connects the location which fixes the said 1st shaft member, and the line segment which connects the location which fixes the said 1st and 2nd distance change mechanism crosses, Therefore, there is an effect that can correct the astigmatism of the light reflected by the reflection mirror.

Claims (13)

A reflective mirror having a reflective surface on one side, A first shaft member fixed at two places on the rear surface of the reflection mirror, A second shaft member having two legs fixed to the rear surface of the reflective mirror and crossing the first shaft member; One distance changing mechanism for changing a distance between the second shaft member and the first shaft member, The line segment connecting the part which fixes the said 1st shaft member and the line segment which connects the part which fixes the said leg of the said 2nd shaft member are substantially orthogonal, The distance changing mechanism is disposed on a straight line perpendicular to the reflection mirror after crossing the intersection of a line segment connecting the position fixing the first shaft member and a line segment fixing the leg of the second shaft member. Characterized Shape variable mirror. delete A reflective mirror having a reflective surface on one side, A first shaft member fixed in a line shape on the back surface of the reflective mirror, A second shaft member having two legs fixed to the rear surface of the reflective mirror and crossing the first shaft member; One distance changing mechanism for changing a distance between the second shaft member and the first shaft member, The line segment connecting the position fixing the first shaft member and the location fixing the leg of the second shaft member is substantially orthogonal, The distance changing mechanism is disposed on a straight line perpendicular to the reflection mirror after crossing the intersection of a line segment connecting the position fixing the first shaft member and a line segment fixing the leg of the second shaft member. Characterized Shape variable mirror. delete The method of claim 1, The first shaft member is fixed to the rear surface of the reflecting mirror even in the vicinity of the intersection with the line segment connecting the position of the leg of the second shaft member on the line segment connecting the position fixing the first shaft member. doing Shape variable mirror. delete The method according to any one of claims 1, 3 or 5, A piezo actuator is used for the distance changing mechanism. Shape variable mirror. The method according to any one of claims 1, 3 or 5, A screw is used for the distance changing mechanism. Shape variable mirror. The method according to any one of claims 1, 3 or 5, It is characterized by using a screw part provided with screws having different pitches on both sides of the distance changing mechanism. Shape variable mirror. A laser processing apparatus having a laser oscillator for oscillating a laser beam, and a processing optical system for transmitting a laser beam from the laser oscillator to a workpiece. The said processing optical system has the shape-variable mirror of any one of Claims 1, 3, or 5 characterized by the above-mentioned. Laser processing device. A laser processing apparatus having a laser oscillator for oscillating a laser beam, and a processing optical system for transmitting a laser beam from the laser oscillator to a workpiece. It has the shape variable mirror of Claim 7 in the said processing optical system, It is characterized by the above-mentioned. Laser processing device. A laser processing apparatus having a laser oscillator for oscillating a laser beam, and a processing optical system for transmitting a laser beam from the laser oscillator to a workpiece. It has the shape variable mirror of Claim 8 in the said processing optical system, It is characterized by the above-mentioned. Laser processing device. A laser processing apparatus having a laser oscillator for oscillating a laser beam, and a processing optical system for transmitting a laser beam from the laser oscillator to a workpiece. It has the shape-variable mirror of Claim 9 in the said processing optical system, It is characterized by the above-mentioned. Laser processing device.

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