JP2010040784A - Laser processing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensively-manufacturable laser processing device including a reflecting mirror having a curved mirror surface or a reflecting mirror having variable curvature and shape. <P>SOLUTION: On an optical path of a laser beam from a laser oscillator to a processing object, a reflecting mirror 1 is arranged. The reflecting mirror 1 is formed with a plate-like member forming a mirror surface, and the mirror surface is curved by a load application mechanism 15 for curving the plate-like member by applying force to the plate-like member to generate bending moment in one direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a laser processing apparatus, and more particularly to a laser processing apparatus in which a reflecting mirror having a curved mirror surface is arranged on an optical path to a workpiece of a laser beam generated by a laser oscillator.

  Generally, a laser processing apparatus has a laser oscillator and a member that forms an optical path that guides a laser beam output from the laser oscillator to a workpiece disposed at a processing point. Currently, in laser processing apparatuses that are widely used in practice, several reflecting mirrors are generally used as members forming the optical path between the inside of an oscillator and a processing point. This is the same even when an optical fiber is used in the middle of the optical path.

  The mirror surfaces of these reflecting mirrors are usually constituted by planes. However, a reflecting mirror having a curved mirror surface may be used for the following two purposes.

  The first purpose in which a reflecting mirror having a curved mirror surface is used is to appropriately maintain the size and shape of the laser beam at the processing point. That is, even when the laser beam is finally focused on the processing point using the condensing optical system, the focused laser beam depends on the size and shape of the laser beam incident on the condensing optical system. The size and shape of the irradiated spot changes. Therefore, in order to control the irradiated spot, it is necessary to control the size and shape of the laser beam incident on the condensing optical system, and a reflecting mirror may be used for this control.

  The second purpose of using a reflecting mirror having a curved mirror surface is to make the characteristics of the laser beam output from the laser oscillator suitable for the purpose. That is, by changing the curvature of the reflecting mirror constituting the laser oscillator inside the laser oscillator, it is possible to change characteristics such as the focusing characteristics, stability, and output efficiency of the output laser beam.

  Thus, the reflecting mirror having a curved mirror surface can be effectively used to control the characteristics of the laser processing apparatus. Therefore, Patent Documents 1 to 3 disclose techniques for variably controlling the characteristics of a laser processing apparatus by dynamically changing and controlling the curvature and shape of the mirror surface of such a reflecting mirror.

  In the techniques disclosed in Patent Documents 1 to 3, an actuator using mechanical displacement such as a piezo element is used to dynamically change the curvature and shape of the mirror surface of the reflecting mirror. On the other hand, Patent Documents 4 and 5 disclose techniques for changing the curvature of a reflecting mirror by applying a fluid pressure of about 1 MPa to the reflecting mirror.

JP 2000-08489 A Japanese Patent Laid-Open No. 11-14945 Japanese Patent Laid-Open No. 06-222300 JP 2004-181532 A Japanese Patent Laid-Open No. 08-039281

  Conventionally, a curved mirror surface is formed by polishing or cutting controlled to have a desired shape. Such processing takes time and effort compared to forming a flat mirror surface. For this reason, a reflecting mirror having a curved mirror surface is more expensive than a plane mirror.

  A reflecting mirror having a curved mirror surface is usually required to have a certain thickness in order to prevent deformation and heat resistance. In particular, since a laser processing apparatus handles a high-power laser, a relatively thick mirror is usually used as a reflecting mirror disposed in the optical path in order to avoid burning. This is because when a laser is incident on the reflecting mirror, light loss is unavoidable on the surface of the reflecting mirror, and heat generated by the loss cannot be avoided.

  FIG. 14 shows an example in which the temperature rise is measured when the reflecting mirror is irradiated with a laser beam. As shown in FIG. 14A, a copper mirror made of copper having an outer diameter of φ50 mm and a thickness of t was used, and a laser beam 165 having a diameter of φ5 mm was made incident near the center of the reflecting mirror 160. And the temperature rise was measured with the temperature sensor 161 arrange | positioned in the center of the back surface of the reflective mirror 160, and the temperature when a temperature rise was no longer observed was calculated | required. FIG. 14B shows a change in temperature when the temperature rise is no longer observed when the laser power of the laser beam is changed.

  As can be seen from FIG. 14 (b), when t = 1 mm or less, the laser power reaches a high temperature that causes burning when the power is several kw. For this reason, a reflecting mirror used in a laser processing apparatus that requires a high-power laser usually requires a thickness of several millimeters or more, and a practical one having a thickness of 3 mm or more is used. In FIG. 14B, only the laser power is shown up to 4 kW, but at t = 4 mm, the reflecting mirror was not burned even when the laser power was 8 kW.

  On the other hand, a reflector having a variable curvature and shape according to the prior art (hereinafter referred to as a variable curvature reflector) is deformed in axial symmetry, i.e., deformed along both two orthogonal axes along the mirror surface. Are done at the same time. In order to cause such a deformation to generate a smooth curved surface, the member to be deformed needs to be made very thin.

  For this reason, it is difficult to construct a variable curvature reflecting mirror according to the prior art so thick that it can sufficiently suppress the adverse effects of heat generation, and requires a cooling mechanism. Therefore, in the variable curvature reflector, liquid cooling using water as a refrigerant is usually performed, and this also increases the cost. Further, the variable curvature reflecting mirror needs to be mirror-finished on a very thin reflecting mirror, and in order to control the deformation, the thickness thereof is finished to be controlled with extremely high accuracy. Due to these factors, it takes a lot of time to manufacture the variable curvature reflector. For this reason, the variable curvature reflector is about ten times as expensive as an ordinary reflector.

  An object of the present invention is to provide a laser processing apparatus including a reflecting mirror having a curved mirror surface that can be manufactured at low cost, or a reflecting mirror having a variable curvature and shape.

  In order to achieve the above-described object, a laser processing apparatus according to the present invention includes a laser oscillator having a resonant reflector and an optical reflector disposed on an optical path of a laser beam from the laser oscillator to a workpiece. At least one of the resonance reflecting mirror and the optical system reflecting mirror is composed of a plate-like member forming a mirror surface, and the plate-like member is bent by applying a force so as to generate a bending moment in one direction on the plate-like member. It further has a load loading mechanism.

  In this configuration, the plate-like member is bent by applying a force so as to generate a bending moment in only one direction. Therefore, even if a relatively thick member is used, the plate-like member can be smoothly smoothed compared to the case where the plate-like member is bent symmetrically. Bend can be generated, and the bend can be easily controlled. Further, since the mirror surface is curved by curving the plate-like member, it is not necessary to form the mirror surface into a curved surface from the beginning.

  In the reflecting mirror curved by the load loading mechanism according to the present invention, the curved surface is not axisymmetric. However, by arranging a plurality of reflecting mirrors bent by the load loading mechanism so that the bending directions are different from each other, the non-axisymmetric property is corrected by the plurality of reflecting mirrors, and the laser beam is adjusted. It can be deformed in a form close to axial symmetry.

  When the angle of incidence of the laser beam on the reflecting mirror is relatively large, the mirror surface of the reflecting mirror curved by the load mechanism is preferably curved along the parabola, and the angle of incidence is relatively When it is small, it is preferable to have a curved shape along an arc. As a result, the distortion of the laser beam after reflection can be kept small.

  The curved shape of the mirror surface can change the ease of deformation by changing the structure and material of the members that make up the reflector, such as thickness and width, or change the distribution of the force applied by the load-loading mechanism. By doing so, it can be adjusted to various shapes. Furthermore, by providing a holding member that comes into contact with the reflecting mirror and curves together with the reflecting mirror, the elasticity of the holding member can be used to control the curved shape of the mirror surface.

  According to the present invention, since the reflecting mirror having a curved mirror surface is formed by curving the plate-like member, it is not necessary to form the mirror surface in a curved shape from the beginning, and the manufacturing of the reflecting mirror can be facilitated. And cost reduction can be achieved. In addition, since the bending is caused only in one direction by applying a force so as to generate a bending moment in one direction, the reflecting mirror does not need to be cooled even when a relatively high power laser is handled. A thick structure can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1A and 1B are schematic views showing a reflecting mirror of the present embodiment, in which FIG. 1A is a perspective view and FIGS. 1B and 1C are side views.

  As shown in FIG. 1 (a), the reflecting mirror 1 of the present embodiment has a disk-like form, and has two fulcrum points 5 on the periphery (the left and right end portions in FIG. 1) facing each other. Thus, it is supported by a machine frame (not shown). As schematically shown in FIGS. 1 (a) and 1 (c), the reflecting mirror 1 has two load points (upper and lower ends in FIG. 1) at 90 degrees from the respective fulcrums 5 on the periphery. 10 is loaded. Thereby, the reflecting mirror 1 is curved so as to draw an arc along the direction connecting the two load points 10 (vertical direction in FIG. 1), and is formed into a cylindrical shape as a whole (a part of the cylinder is formed). To) is curved.

  It should be noted that the reflecting state of the reflecting mirror 1 is not necessarily strictly cylindrical depending on the shape of the reflecting mirror 1, the surface distribution of thickness and rigidity, and the mirror surface is generally curved along one direction. In the direction orthogonal to the curved direction, the shape is not curved. Hereinafter, for the sake of convenience, such a curved shape may be referred to as a cylindrical shape.

  As shown in FIG. 1B, the reflecting mirror 1 of the present embodiment is in a flat state when no load is applied. In other words, the reflecting mirror 1 is originally a plane mirror, and therefore is easier to manufacture than forming a curved mirror surface from the beginning.

  Further, the reflecting mirror 1 of the present embodiment is deformed into a cylindrical shape, that is, the deformation is caused only along one direction. Such deformation is easier to control than the axially symmetric deformation in the prior art, and the reflecting mirror 1 of this embodiment is also easy to manufacture from this point.

  In addition, the cylindrical deformation can be performed so that a smooth curved surface is easily generated even for a relatively thick member as compared with the axially symmetric deformation. For this reason, in this embodiment, the reflective mirror 1 can be made into a comparatively thick structure.

  In a laser processing apparatus with an output of 0.5 W to 10 kW used for laser cutting of a metal plate material, the reflecting mirror 1 is used inside the laser oscillator (resonant reflecting mirror) or on the optical path outside the laser oscillator (optical system reflecting mirror). The thickness of the reflecting mirror 1 is preferably about 3 mm to 20 mm. Accordingly, it is possible to suppress the heating due to the heat generated by the loss at the time of reflection of the laser light and to suppress the adverse effect.

  As a material of the reflecting mirror 1, a surface that becomes a mirror surface with silicon crystal or copper as a substrate is coated with gold, silver, or molybdenum, and a dielectric multilayer film is further formed in some cases to increase the reflectance. Can do. The cross section of the laser beam in the laser processing apparatus is often a circle having a diameter of φ1 mm to φ50 mm, but may be an ellipse or a rectangle, and the size of the reflecting mirror 1 is the size and shape of the laser beam. It can be appropriately selected depending on the case.

  In a typical example, the output of the laser is 5 kW, and the size of the laser beam inside the laser oscillator is 50 mm in diameter. In this case, the reflecting mirror 1 using a circular silicon having a diameter of 75 mm as a substrate is used for the optical path to the processing point, and the thickness of the reflecting mirror 1 is 5 mm to 8 mm.

  As a load loading mechanism 15 that applies a force to deform the reflecting mirror 1 into a cylindrical shape, for example, as schematically illustrated in FIG. A mechanism having a member 17 that transmits force to the load point 10 can be used. By using the spring 16, the force applied to the load point 10 can be directly adjusted, whereby the curvature of the cylindrical mirror surface of the reflecting mirror 1 is changed to the frictional force when the torque generating mechanism is used. Can be adjusted accurately without causing any disturbance.

  Next, the effect | action of the reflective mirror 1 of this embodiment is demonstrated with reference to FIG. 2 schematically shows how the laser beam 20 is reflected by the reflecting mirror 1. FIG. 2A is a perspective view, and FIG. 2B is a plan view.

  By using the reflecting mirror 1 deformed into a cylindrical shape, the shape of the reflected laser beam can be deformed. The deformation varies depending on the incident angle and the incident direction, but typically, as shown in FIG. 2, the laser beam is incident in parallel to a plane perpendicular to the axis of the cylinder drawn by the mirror surface. Thereby, in the cross section of the laser beam, the laser beam is deformed so that no deformation occurs in the direction of the axis of the cylinder drawn by the mirror surface (Y direction), and only the direction perpendicular to the direction (X direction) is contracted. . That is, as shown in FIG. 2B, for example, if the cross-sectional shape 21 of the laser beam incident on the reflecting mirror 1 is circular, the cross-sectional shape 22 of the laser beam reflected by the reflecting mirror 1 has a long axis. It becomes an ellipse with the Y direction and the minor axis in the X direction.

  By deforming the laser beam in this way, the laser beam can be adjusted to be suitable for various processing. That is, for example, by changing the curvature of the reflecting mirror 1 in accordance with the thickness of the workpiece, the width of the laser beam incident on the condenser lens with respect to the workpiece is suitable for workpieces of various thicknesses. Can be adjusted as follows.

  In the reflecting mirror 1 of the present embodiment, the laser beam is contracted only in one direction and deformed into a flat shape, but the flat beam shape is, for example, a direction perpendicular to the contracted direction and a cutting line of the workpiece. It can be considered to be used in the form of being arranged in parallel with each other. Further, when the laser oscillator outputs a laser beam having a flat cross-sectional shape as its characteristic, the cross-sectional shape is corrected to a shape close to axial symmetry by the deformation action of the cross-sectional shape of the laser beam by the reflecting mirror 1. Can be considered. If the cross-sectional shape of the laser beam is made nearly axisymmetric, it is often advantageous to improve the energy utilization efficiency. Further, in the case of a configuration in which the cross-sectional shape of the laser beam is rectangular, a method of using the beam by contracting in a direction along any side of the rectangle may be considered.

  Alternatively, a plurality of reflecting mirrors deformed into a cylindrical shape may be arranged on the laser beam path so as to cancel out non-axisymmetric properties of the deformation of the laser beam by the reflecting mirrors. FIG. 3 is a schematic diagram showing a configuration of such an example of a laser processing apparatus.

  In the configuration shown in FIG. 3, the laser beam emitted from the output mirror 31 of the laser oscillator 30 is incident on the condenser lens 35 via the four reflecting mirrors 1 a, 1 b, 2, and 3, and is covered on the processing table 37. The workpiece is irradiated. Of the four reflecting mirrors 1a, 1b, 2 and 3, two reflecting mirrors 1a and 1b which are deformed into a cylindrical shape are used.

  The directions of incidence and emission of the laser beam to the reflecting mirrors 1a and 1b are set in a direction parallel to a plane perpendicular to the axis of the cylinder drawn by the mirror surfaces of the reflecting mirrors 1a and 1b, as in FIG. The mirror surfaces of the reflecting mirrors 1a and 1b are arranged such that the cylinder axes drawn by the reflecting mirrors 1a and 1b are in directions perpendicular to each other (twisted position). Therefore, the plane on which the center point of the output mirror 31 and the reflecting mirrors 1a and 1b is located and the plane on which the center point of the reflecting mirrors 1a, 1b and 2 is located are arranged to be orthogonal to each other.

  With this configuration, the laser beam is deformed so as to be contracted in one direction by the reflecting mirror 1a, and then contracted in a direction perpendicular to that contracted by the reflecting mirror 1a by the reflecting mirror 1b. Transformed into As a result, the laser beam as a whole can be deformed so as to be contracted in a form that is nearly axially symmetric. That is, by combining the two reflecting mirrors 1a and 1b, it is possible to obtain substantially the same operation as when using a conventional variable curvature reflecting mirror that is deformed in axial symmetry.

  As described above, when the laser beam is deformed substantially symmetrically with respect to the axis, the deformation amount of the laser beam by the reflecting mirrors 1a and 1b must be the same. In particular, this can be realized by making the curvatures of the mirror surfaces of the reflecting mirrors 1a and 1b the same, and making the incident angles of the laser beams to the reflecting mirrors 1a and 1b the same. In order to make the curvature of the mirror surfaces of the reflecting mirrors 1a and 1b the same, for example, the reflecting mirrors 1a and 1b may have the same specifications, and the load applied for deformation may be set to be the same. The incident angle can be set to 45 ° for both the reflecting mirrors 1a and 1b, for example.

  Moreover, even if more reflective mirrors that are deformed into a cylindrical shape are used, for example, two more reflective mirrors whose axis of the cylinder drawn by the mirror surface is shifted by 45 ° with respect to the reflective mirrors 1a and 1b are used. Well, it can increase the accuracy of axial symmetry.

Such axisymmetric deformation is particularly effective when a circular beam is used. Even when a rectangular beam is output from the laser oscillator, when a laser beam having a long wavelength such as a CO ₂ laser is used, a cross section of the laser beam is obtained after a long propagation distance due to the diffraction effect. Since the shape is rounded, axisymmetric deformation is often effective. However, for example, when the cross section of the laser beam output from the laser oscillator 30 is flat, the deformation by the reflecting mirrors 1a and 1b does not necessarily have to be the same, and the amount of deformation in each direction depends on the application. It is good also as a structure which adjusts appropriately.

  As described above, according to the present embodiment, it is possible to provide a reflecting mirror having a curved mirror surface that is easy to manufacture and, as a result, can be made inexpensive. In addition, the reflecting mirror having a curved mirror surface can be made thick enough to avoid the effects of heating due to the loss of light when the laser light is reflected, thereby eliminating the need for a cooling mechanism. This also makes the reflector more inexpensive.

  In addition, said embodiment illustrates this invention, A various change is possible within the scope of the present invention prescribed | regulated to a claim.

  For example, as the load load mechanism 15, a mechanism for applying a force for bending the reflecting mirror between the fulcrum 5 and the load point 10 has been shown. However, the reflecting mirror can be bent only in one direction. Any structure that applies a force, in other words, a force that generates a bending moment in one direction other than the thickness direction of the plate can be used. For example, in the above-described embodiment, the configuration in which the force to be applied is set using the spring 16 as the load load mechanism 15 that applies the load for deforming the reflecting mirror is illustrated, but instead of enabling the force to be set, the amount of deformation You may use the mechanism which can set. Moreover, these can also be set as the structure which can change the setting of a force and a deformation amount suitably according to a process use.

  Further, a mechanism capable of dynamically changing the deformation of the reflecting mirror may be used in order to dynamically control the propagation and oscillation mode of the laser beam. As such a mechanism, it is preferable to use an actuator such as an air cylinder capable of controlling the pressing force by controlling the pressure of the working fluid. Alternatively, a precise mechanical operation mechanism such as a gear mechanism capable of controlling the operation in submicron units can be used as a mechanism for dynamically changing the deformation of the reflecting mirror.

  Further, the deformation of the reflecting mirror is not limited to a cylindrical shape. For example, when the incident angle is large, it is preferable to deform the reflecting mirror along a parabola. The deformation of the reflecting mirror along the arc is preferable when the incident angle is shallow or the radius of curvature is large. Thereby, distortion of the laser beam after reflection can be suppressed to a small level. In any case, it is important to control the shape of the reflecting mirror when it is deformed.

  As a method of controlling the shape of the reflecting mirror when it is deformed, a method of changing the secondary coefficient of the cross section by changing the width and / or thickness of the reflecting mirror along the direction of deformation is conceivable. . Further, the deformation may be controlled by applying force to the reflecting mirror at a plurality of positions spaced along the direction of deformation and adjusting the force applied at each position.

  FIG. 4 shows such an example, FIG. 4 (a) is a front view, FIG. 4 (b) is a plan view, and FIG. 4 (c) is a plan view exaggerating a deformed shape. As shown in FIG. 4A, in this example, a rectangular reflecting mirror 41 is used, and a fulcrum 45 is provided at the center of the two opposite sides of the rectangle. As schematically shown by an arrow in FIG. 4B, seven actuators 47 a to 47 g are arranged at intervals on the back surface of the reflecting mirror 41 along a line connecting the two fulcrum points 45. .

  In the configuration shown in FIG. 4, the shape of the mirror surface of the reflecting mirror 41 can be adjusted to various shapes by adjusting the ratio of the force applied by the actuators 47a to 47g. FIG. 4C particularly shows a case where the force applied by the actuators 47a to 47g is equalized, and in this case, the mirror surface has a shape along an arc. Instead of using a plurality of actuators, the load applied to the reflecting mirror 41 is distributed in various directions along the direction in which the reflecting mirror 41 is deformed through an elastic member or the like, whereby the shape of the reflecting mirror 41 is desired. You may adjust to the shape.

  Further, a holding member that contacts the reflecting mirror and curves together with the reflecting mirror may be provided, and the elasticity of the holding member may be used to adjust the shape of the reflecting mirror. 5 to 8 show examples of such a configuration, in which (a) of each figure is a front view of the reflecting mirror viewed from the mirror surface side, and (b) is a side view.

  In the configuration shown in FIG. 5, the reflecting mirror 50 has two load points 63 facing each other on the periphery of the back surface of the reflecting mirror 50 by a load loading mechanism 60 that is arranged on the back surface and generates a load by a spring 61. Power is applied in. Thereby, the reflecting mirror 50 is held in contact with a holding member 55 arranged on the mirror surface side. The holding member 55 has a disk-like structure in which a circular opening 56 is formed. The holding member 55 is disposed so as to abut the peripheral edge of the mirror surface of the reflecting mirror 50 and to expose the mirror surface from the opening 56. . The holding member 55 is supported by a machine frame (not shown) or the like at two fulcrums 58 that are 90 ° apart from the load point 63 at the periphery.

  According to the configuration shown in FIG. 5, the reflecting mirror 50 is curved along the direction of the line connecting the two load points 63. This bending deformation is accompanied by elastic deformation of the holding member 55, and the elasticity of the holding member 55 affects the curved shape of the reflecting mirror 50. Therefore, the elasticity of the holding member 55 can be used for controlling the curved shape of the reflecting mirror 50.

  The configuration shown in FIG. 6 is substantially the same as the configuration shown in FIG. 5, but the holding member 70 has a configuration in which the opening 71 has an elliptical shape and the thickness increases toward the outer peripheral side. It is. Thus, by changing the structure such as the size and shape of the holding member 70, the elasticity of each part of the holding member 70 can be changed and used for controlling the shape of the reflecting mirror 50. Further, as the holding members 55 and 70, for example, metal members can be used, and the elasticity can be changed by heat treatment or the like, or the elasticity can be changed by changing the material for each part. Good.

  FIG. 6 shows an example in which an actuator 76, for example, an air cylinder, is used for the load load mechanism 75. As described above, the load load mechanism 60 using the spring 61 and the load load mechanism 75 using the actuator 76 can be appropriately selected and used depending on whether or not dynamic control is necessary.

  As shown in FIG. 5 and the like, it is simple in design to apply the load symmetrically on both sides of the reflecting mirror. However, as in the example shown in FIG. 7, only at one load point 80 at the periphery of the reflecting mirror 50. A load may be applied. That is, in the example shown in FIG. 7, on the periphery of the holding member 55, a fulcrum 83 is arranged at a position facing the load point 80 in addition to the two fulcrums 58 facing each other. A support member 84 is disposed on the back surface side of the reflecting mirror 50 at a position facing the fulcrum 83. As the load loading mechanism 85, a mechanism that applies a force to only one point is used, and this can be constituted by only the spring 86, for example. According to the configuration shown in FIG. 7, the displacement of the mirror surface of the reflecting mirror 50 is minimized, which is necessary when the setting accuracy of a part of the reflecting mirror 50 such as the optical axis needs to be kept high. May be useful to.

  In the example shown in FIG. 8, holding members 90 that hold the edges of the reflecting mirror 50 so as to sandwich the edges of the reflecting mirror 50 are provided at two points on the periphery of the reflecting mirror 50 that face each other. In this example, the force by the actuator 76 is not directly transmitted to the reflecting mirror 50 but is transmitted through the holding member 90. Similarly, the fulcrum is also formed by two other holding members 95 that sandwich the periphery of the reflecting mirror 50.

  In addition, basically, a force is applied to the plate-like reflecting mirror so that the mirror surface is curved along only one direction. However, by combining it with other members that come into contact with the reflecting mirror, A reflecting mirror having a configuration in which a curve is generated also in a direction intersecting with the direction in which the phenomenon occurs is also conceivable. An example of such a configuration is shown in FIGS. 9A is a view seen from the mirror surface side, FIG. 9B is a cross-sectional view taken along line BB in FIG. 9A, and FIG. 9C is a cross-sectional view taken along line C- in FIG. FIG. 9D is a cross-sectional view taken along line C in FIG. 9B, and FIG. 9D is a cross-sectional view taken along line DD in FIG. FIG. 10 is a conceptual diagram showing a deformed state of the reflecting mirror 100. 10A to 10C are diagrams assuming that the reflecting mirror 100 is not deformed, and FIG. 10A corresponds to a cross section taken along line BB in FIG. 9A. FIG. 10B is a view corresponding to the cross section along the line CC in FIG. 9A, and FIG. 10C is the cross section along the line DD in FIG. 9B. FIG. 10D and 10E are views showing a state in which the reflecting mirror 100 is deformed, and FIG. 10D corresponds to a cross section taken along line BB in FIG. 9A. FIG. 10E is a diagram corresponding to a cross section taken along line CC in FIG. 9A.

  In the example shown in FIGS. 9 and 10, the end wall 107 extends diametrically across an end wall 107 of a housing 105 having a cylindrical side wall 106 and an end wall 107 that closes one end of the side wall 106. A curved leaf spring 110 is arranged so that both ends are directed upward. A pressing member 111 is disposed on each end of the leaf spring 110, and the pressing member 111 is in contact with two opposite positions on the peripheral edge of the back surface of the disk-shaped reflecting mirror 100. .

  A holder 115 is fixed to the end of the side wall 106 of the housing 105 opposite to the end wall 107 by a stopper 120. The holder 115 has a cylindrical side wall 116 connected to the side wall 106 of the housing 105, and an end wall 117 that extends radially inward from the end of the side wall 116 opposite to the housing 105 side. The central side of the end wall 117 is a circular opening 118, and a protrusion 119 toward the housing 105 is formed at the edge of the end wall 117 of the opening 118. The back surface of the reflecting mirror 100 is pressed by the leaf spring 110 via the pressing member 111, the mirror surface is pressed against the protruding portion 119 of the holder 115, and the contact portion with the protruding portion 119 is a fulcrum Q. Curved. Thus, in this example, the load loading mechanism that applies a force to bend the reflecting mirror 100 along one direction is configured by the housing 111, the holder 115, the pressing member 111, and the leaf spring 110. .

  Mounts 108 are disposed on the periphery of the housing 105 at two positions facing each other, which are shifted by 90 degrees from the positions where the pressing members 111 are disposed. As shown in FIGS. 10A and 10B, the mount 108 has a height that does not contact the reflecting mirror 100 when the reflecting mirror 100 is not deformed. On the other hand, as described above, when the reflecting mirror 100 is deformed by the leaf spring 110, the contact points of the reflecting mirror 100 with the two pressing members 111 are set as shown in FIGS. The central portion viewed in the connecting direction is displaced to the housing 105 side, thereby coming into contact with the mount 108. Thereby, the reflecting mirror 100 is also curved along the direction connecting the contact points with the two mounts 108.

  As described above, according to the configuration shown in FIGS. 9 and 10, it is possible to cause the reflecting mirror 100 to simultaneously bend along both directions orthogonal to each other. However, the bending of the reflecting mirror 100 is mainly along the direction connecting the contact points with the two pressing members 111, and the bending along the direction connecting the contact points with the two mounts 108 is smaller. It will be a thing. Therefore, the curved mirror surface of the reflecting mirror 100 is substantially an ellipsoidal surface.

  This ellipsoidal mirror surface is extremely useful. This is because if this is used for a part that reflects the laser beam at a large incident angle such as 45 degrees, the reflection of the laser beam is controlled by the curvature of each direction of the mirror surface, unlike the case where it is reflected by a spherical surface or a cylindrical surface. This is because it is possible to realize propagation that eliminates the non-axisymmetric property caused by the direction. Conversely, it may be reflected so as to emphasize the non-axisymmetric property, and in this case, the cylindrical mirror condenses in a line segment shape, whereas according to the ellipsoidal mirror surface, An elliptical condensing spot shape can be obtained. That is, a desired elliptical heat input region can be configured by adjusting the curvature and the incident direction of each direction of the mirror surface.

  The reflecting mirror having a curved mirror surface according to the present invention can be used not only in the optical path of the laser beam output from the laser oscillator, but also as at least one of the reflecting mirrors constituting the laser oscillator itself. It can also be used. By using the reflecting mirror according to the present invention as a reflecting mirror constituting a laser oscillator, it becomes possible to control the shape, condensing characteristics, stability, and oscillation efficiency of the laser beam, which brings a great advantage. Such an example is shown in FIGS.

FIG. 11A shows an example in which a reflecting mirror having a curved mirror surface according to the present invention is used for a three-axis orthogonal CO ₂ laser oscillator. In the three-axis orthogonal CO ₂ laser oscillator, a laser gas is caused to flow between the two electrodes 130 as schematically shown by an arrow 132, thereby forming a discharge area 131 where the laser gas is discharged and excited. An output mirror 135 and a rear mirror 136 are respectively disposed at opposite ends of the discharge area 131, and a folding mirror 137 is disposed. Laser oscillation occurs between the output mirror 135, the rear mirror 136, and the folding mirror 137, and a laser beam is output from the output mirror 135 that is a partial reflection mirror.

In such a three-axis orthogonal CO ₂ laser oscillator, the laser gas flow and the excitation discharge current are not axisymmetric with respect to the optical axis cross section. Therefore, when a spherical mirror is used for the output mirror 135 and the rear mirror 136 and a plane mirror is used for the folding mirror 137, the cross-sectional shape of the emitted laser beam 139 is non-axisymmetric as schematically shown in FIG. In some cases, the shape becomes elliptical. Therefore, by using the reflecting mirror having a cylindrical mirror surface according to the present invention as the folding mirror 137, the cross-sectional shape of the emitted laser beam can be corrected to a shape close to a circle.

  Thus, by making the cross-sectional shape of the laser beam nearly circular, the laser beam component discarded for the aperture can be reduced, and the laser oscillation efficiency can be improved to some extent. . It is also conceivable that the rear mirror 136 is configured to improve non-axisymmetric property by applying a force that deforms the rear mirror 136 along one direction.

  FIG. 12A shows an example in which the reflecting mirror according to the present invention is used in a slab YAG laser oscillator. As shown in FIG. 12B, the slab YAG laser oscillator is known to have a configuration in which the laser light passes through the YAG 140 in a zigzag manner. In this case, the influence of the thermal lens effect is reduced. It is known that However, as shown in FIG. 12A, when the laser beam is configured to travel straight in the YAG 140, the oscillation efficiency and the concentration of the laser beam are collected due to the thermal lens effect as the operation time elapses. Changes in light properties occur.

  Therefore, one of the output mirror 141 and the rear mirror 142 constituting the slab YAG laser oscillator can be a reflecting mirror capable of dynamically changing the curvature according to the present invention. In FIG. 12A, the rear mirror is replaced with a reflecting mirror 145 that can dynamically change the curvature according to the present invention. Accordingly, by changing the curvature of the reflecting mirror 145 so as to cancel out the thermal lens effect caused by the partial change in the refractive index of the YAG 140 as the operation time elapses, the oscillation efficiency and the condensing property of the laser beam are improved. Stable laser output can be obtained by suppressing the change of.

  FIG. 13 shows an example in which a reflecting mirror having a curved mirror surface according to the present invention is used for a gas slab laser oscillator. That is, in the example shown in FIG. 13, one of the two folding mirrors 151 and 152 that constitute the gas slab laser oscillator, the folding mirror 152 on the side facing the output mirror 155 is connected via the actuator 157. The configuration is curved. In this way, by actively deforming the folding mirror 152, it is possible to provide a laser processing apparatus capable of changing the quality of the laser beam and outputting a laser beam suitable for various applications.

It is a schematic diagram which shows the reflecting mirror by one Embodiment of this invention, Fig.1 (a) is a perspective view, FIG.1 (b), (c) is a side view. It is a figure which shows a mode that a laser beam is reflected by the reflective mirror of FIG. 1, FIG. 2 (a) is a perspective view, FIG.2 (b) is a top view. It is a schematic diagram of the laser processing apparatus which has arrange | positioned two reflection mirrors of FIG. 1 on the optical path of a laser beam. It is a schematic diagram which shows the reflecting mirror of the structure which applies force with respect to a reflecting mirror in the several position along a deformation | transformation direction, FIG. 4 (a) is a front view, FIG.4 (b) is a top view, FIG. c) is a plan view showing the deformed shape in an exaggerated manner. It is a figure which shows an example reflective mirror which used the holding member for adjustment of a deformation | transformation. It is a figure which shows the reflective mirror of the other example which used the holding member for adjustment of a deformation | transformation. It is a figure which shows the reflective mirror of the further another example using the holding member for adjustment of a deformation | transformation. It is a figure which shows the reflective mirror of the further another example using the holding member for adjustment of a deformation | transformation. It is a schematic diagram which shows the reflective mirror of the modification by this invention. It is a schematic diagram for demonstrating a deformation | transformation of the reflective mirror of FIG. It is a schematic diagram showing a three-axis orthogonal CO ₂ laser oscillator using a reflecting mirror according to the present invention. It is a schematic diagram which shows the slab YAG laser oscillator using the reflective mirror by this invention. It is a schematic diagram which shows the gas slab laser oscillator using the reflective mirror by this invention. It is a figure which shows the example of a measurement of a temperature rise at the time of irradiating a laser beam to a reflective mirror.

Explanation of symbols

1 reflector 5 fulcrum 10 load point 15 load load mechanism

Claims (5)

A laser oscillator having a resonant reflector;
An optical reflector disposed on the optical path of a laser beam from the laser oscillator to the workpiece;
Have
At least one of the resonance reflecting mirror and the optical system reflecting mirror is composed of a plate-like member that forms a mirror surface,
A load-loading mechanism for bending the plate-like member by applying a force to cause a bending moment in one direction to the plate-like member;
Laser processing equipment.   The laser processing apparatus according to claim 1, wherein the laser processing apparatus includes a plurality of reflecting mirrors curved by the load loading mechanism, and the reflecting mirrors are arranged so that the bending directions are different from each other.   The laser processing apparatus according to claim 1, wherein the reflecting mirror curved by the load-loading mechanism includes a reflecting mirror that is curved so that a mirror surface extends along a parabola.   The laser processing apparatus according to any one of claims 1 to 3, wherein the reflecting mirror curved by the load loading mechanism includes a reflecting mirror that is curved so that a mirror surface extends along an arc.   5. The laser according to claim 1, further comprising a holding member that contacts the reflecting mirror curved by the load loading mechanism and curves together with the reflecting mirror by a force applied by the load loading mechanism. 6. Processing equipment.

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