JP2018079495A - Objective lens drive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To drive an objective lens at a high speed.SOLUTION: An objective lens drive device 440 includes a fixing member 10 fixed to a laser beam machine, a mounting member 20 on which a condensing lens unit 430 is mounted, a piezoelectric element 30 which is displaced by application of a voltage, and a pair of drive housings 40 for housing the piezoelectric element 30. The drive housing 40 includes a first connection part 41 connected to the fixing member 10 and a second connection part 42 connected to the mounting member 20. The second connection part 42A of the one drive housing 40A, which deforms so that the second connection part 42 relatively moves along a Z axis with respect to the first connection part 41 by displacement of the piezoelectric element 30, is connected to one side in an X axis direction of the mounting member 20 than the condensing lens unit 430. The second connection part 42B of the other drive housing 40B is connected to the other side in the X axis direction of the mounting member 20 than the condensing lens unit 430.SELECTED DRAWING: Figure 16

Description

  The present invention relates to an objective lens driving device.

  2. Description of the Related Art Conventionally, in a laser light irradiation apparatus that irradiates an object with laser light, an objective lens driving device (drive unit) that moves an objective lens that focuses the laser light onto the object along the optical axis direction of the objective lens is known. (For example, refer to Patent Document 1).

JP 2011-51011 A

  In the objective lens driving device, when the objective lens is driven at a high speed, vibrations in a low frequency range that causes the objective lens to swing, for example, become prominent, and it may be difficult to realize the high speed driving.

  An object of this invention is to provide the objective lens drive device which can drive an objective lens at high speed.

  An objective lens driving device according to the present invention is a laser light irradiation device that irradiates an object with laser light, and an objective lens that moves the objective lens that focuses the laser light onto the object along the optical axis direction of the objective lens. A driving device, a fixing member fixed to the laser light irradiation device, an attachment member to which an objective lens is attached, a piezoelectric element that is displaced by application of a voltage, a first connection portion and an attachment member connected to the fixing member A second coupling portion that is coupled to the piezoelectric element, accommodates the piezoelectric element, and is deformed so that the second coupling portion moves relative to the first coupling portion along the optical axis direction by displacement of the piezoelectric element. A pair of drive housings, wherein the second connecting portion of one of the pair of drive housings is connected to one side of the mounting member in a predetermined direction with respect to the objective lens, and the pair of drive housings Other Second connecting portion of the drive housing is connected to the other side of the predetermined direction from the objective lens in the mounting member.

  In this objective lens driving device, a pair of driving housings fixed to the laser beam irradiation device via a fixing member are connected to one side and the other side in a predetermined direction with respect to the objective lens in the mounting member. Thereby, an objective lens can be hold | maintained with the both-ends support structure in a predetermined direction. The resonance frequency of the objective lens can be set to a high frequency range, and vibration in a low frequency range that becomes an obstacle for realizing high-speed driving of the objective lens can be suppressed. As a result, the objective lens can be driven at high speed.

  In the objective lens driving device according to the present invention, the laser beam irradiation device is a device that scans the laser beam along the planned irradiation line, and the displacement direction in which the piezoelectric element is displaced is the extension of the irradiation planned line that scans the laser beam. The direction orthogonal to the current direction may be used. When the displacement direction of the piezoelectric element is perpendicular to the extending direction of the irradiation line to be scanned with the laser light, when the piezoelectric element is displaced, the drive housing is hardly deformed in the extending direction ( It becomes difficult to distort). Thereby, it can suppress that the optical axis of an objective lens shift | deviates to the said extension direction resulting from a deformation | transformation of a drive housing | casing. The positional accuracy of the optical axis in the extending direction of the planned irradiation line is important in the present invention where dynamic characteristics are required as a focus correction technique, so the effect of shifting the optical axis of the objective lens in the extending direction is particularly effective. It is.

  In the objective lens driving device according to the present invention, the second connecting portions of the pair of driving housings may be connected to positions where the optical axis of the objective lens is sandwiched between the attachment members. When the second connecting portion relatively moves along the optical axis direction due to the displacement of the piezoelectric element, a force is applied to the mounting member in the optical axis direction via the second connecting portion. At this time, since the second connecting portion is connected to the attachment member at a position sandwiching the optical axis of the objective lens, it is possible to prevent the objective lens from generating a moment that swings the optical axis due to the force. Is possible.

  In the objective lens driving device according to the present invention, the first and second connection portions are block-shaped portions that are provided apart from each other in the drive housing, and the drive housing is second from the first connection portion. A pair of plate portions extending toward the coupling portion and defining a housing space for housing the piezoelectric element, and one end portion of the piezoelectric element in the displacement direction, disposed in the housing space and coupled to the first coupling portion A first rotation support portion that rotates and supports the second rotation support portion that is disposed in the accommodation space and is connected to the second connection portion and that rotatably supports the other end portion in the displacement direction of the piezoelectric element, The thickness of both end portions in the extending direction of the plate portion may be thinner than the thickness of the plate portion other than the both end portions. With such a configuration, it is possible to specifically realize that the drive housing is deformed so that the second connection portion moves relative to the first connection portion along the optical axis direction due to the displacement of the piezoelectric element. .

  In the objective lens driving device according to the present invention, the fixing member, the mounting member, and the driving housing may be integrally formed. In this case, the rigidity of the device can be increased and the resonance frequency can be further increased.

  In the objective lens driving device according to the present invention, at least a part of the piezoelectric element may not be covered with resin. Thereby, it is possible to suppress the dielectric breakdown of the piezoelectric element due to moisture contained in the resin covering the piezoelectric element, increase the allowable voltage applied to the piezoelectric element, and increase the displacement range of the piezoelectric element. As a result, the driving range (stroke) along the optical axis direction of the objective lens can be increased.

  The objective lens driving device according to the present invention may have a plane-symmetric structure in which a plane passing through the optical axis of the objective lens and perpendicular to a predetermined direction is a symmetric plane. Such a plane-symmetric structure can suppress the vibration of the objective lens.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the objective lens drive device which can drive an objective lens at high speed.

It is a schematic block diagram of the laser processing apparatus used for formation of a modification area | region. It is a top view of the processing target object used as the object of formation of a modification field. It is sectional drawing along the III-III line of the workpiece of FIG. It is a top view of the processing target after laser processing. It is sectional drawing along the VV line of the workpiece of FIG. It is sectional drawing along the VI-VI line of the processing target object of FIG. It is a perspective view of the laser processing apparatus concerning an embodiment. It is a perspective view of the processing target attached to the support stand of the laser processing apparatus of FIG. It is sectional drawing of the laser output part along the ZX plane of FIG. It is a perspective view of a part of laser output part and laser condensing part in the laser processing apparatus of FIG. It is sectional drawing of the laser condensing part along XY plane of FIG. It is sectional drawing of the laser condensing part along the XII-XII line | wire of FIG. It is sectional drawing of the laser condensing part along the XIII-XIII line | wire of FIG. It is a fragmentary sectional view of the reflection type spatial light modulator in the laser processing apparatus of FIG. It is a figure which shows the optical arrangement | positioning relationship of the reflection type spatial light modulator in the laser condensing part of FIG. 11, a 4f lens unit, and a condensing lens unit. It is a perspective view which shows the objective lens drive device which concerns on 1st Embodiment. FIG. 17 is a perspective view showing a state where the condenser lens unit is not held in the objective lens driving device of FIG. 16. It is another perspective view which shows the objective lens drive device of FIG. FIG. 18 is still another perspective view showing the objective lens driving device of FIG. 17. It is a side view which shows the objective lens drive device of FIG. (A) is the figure which modeled the structure of the drive housing | casing at the time of the non-expansion of a piezoelectric element. (B) is the figure which modeled the structure of the drive housing at the time of expansion | extension of a piezoelectric element. It is a side view which shows the objective lens drive device of FIG. 17 at the time of expansion | extension of a piezoelectric element. It is a perspective view which shows the objective lens drive device which concerns on 2nd Embodiment. FIG. 24 is a perspective view showing a state where the condenser lens unit is not held in the objective lens driving device of FIG. 23. It is a disassembled perspective view of the objective lens drive device of FIG. It is a perspective view which shows the fixing member of the objective lens drive device of FIG. It is a perspective view which shows the attachment member of the objective lens drive device of FIG. (A) is a perspective view which shows one drive housing | casing of the objective lens drive device of FIG. FIG. 25B is a perspective view showing the other drive housing of the objective lens drive device of FIG. 24.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the same or an equivalent part, and the overlapping description is abbreviate | omitted.

  The objective lens driving device according to the embodiment is mounted on a laser processing device (laser light irradiation device) that forms a modified region on a processing target along a line to be cut by condensing the laser light on the processing target. ing. First, the formation of the modified region will be described with reference to FIGS.

  As shown in FIG. 1, a laser processing apparatus 100 includes a laser light source 101 that oscillates a laser beam L, a dichroic mirror 103 that is arranged to change the direction of the optical axis (optical path) of the laser beam L by 90 °, and And a condensing lens (objective lens) 105 for condensing the laser light L. Further, the laser processing apparatus 100 includes a support base 107 for supporting the processing object 1 that is an object to be irradiated with the laser light L, a stage 111 that is a moving mechanism for moving the support base 107, and a laser beam. A laser light source control unit 102 that controls the laser light source 101 to adjust the L output, pulse width, pulse waveform, and the like, and a stage control unit 115 that controls the movement of the stage 111 are provided.

  In the laser processing apparatus 100, the laser light L emitted from the laser light source 101 is changed in the direction of its optical axis by 90 ° by the dichroic mirror 103, and is placed inside the processing object 1 placed on the support base 107. The light is condensed by the condensing lens 105. At the same time, the stage 111 is moved, and the workpiece 1 is moved relative to the laser beam L along the planned cutting line 5. Thereby, a modified region along the planned cutting line 5 is formed on the workpiece 1. Here, the stage 111 is moved in order to move the laser light L relatively, but the condensing lens 105 may be moved, or both of them may be moved.

  As the processing object 1, a plate-like member (for example, a substrate, a wafer, or the like) including a semiconductor substrate formed of a semiconductor material, a piezoelectric substrate formed of a piezoelectric material, or the like is used. As shown in FIG. 2, a scheduled cutting line 5 for cutting the workpiece 1 is set in the workpiece 1. The planned cutting line 5 is a virtual line extending linearly. When the modified region is formed inside the workpiece 1, the laser beam L is cut in a state where the condensing point (condensing position) P is aligned with the inside of the workpiece 1 as shown in FIG. 3. It moves relatively along the planned line 5 (that is, in the direction of arrow A in FIG. 2). Thereby, as shown in FIGS. 4, 5, and 6, the modified region 7 is formed on the workpiece 1 along the planned cutting line 5, and the modified region formed along the planned cutting line 5. 7 becomes the cutting start region 8. The planned cutting line 5 corresponds to the planned irradiation line.

  The condensing point P is a part where the laser light L is condensed. The planned cutting line 5 is not limited to a straight line, but may be a curved line, a three-dimensional shape in which these lines are combined, or a coordinate designated. The planned cutting line 5 is not limited to a virtual line but may be a line actually drawn on the surface 3 of the workpiece 1. The modified region 7 may be formed continuously or intermittently. The modified region 7 may be in the form of a line or a dot. In short, the modified region 7 only needs to be formed at least inside the processing object 1, the front surface 3, or the back surface. A crack may be formed starting from the modified region 7, and the crack and modified region 7 may be exposed on the outer surface (front surface 3, back surface, or outer peripheral surface) of the workpiece 1. The laser light incident surface when forming the modified region 7 is not limited to the front surface 3 of the workpiece 1 and may be the back surface of the workpiece 1.

  Incidentally, when the modified region 7 is formed inside the workpiece 1, the laser light L passes through the workpiece 1 and is near the condensing point P located inside the workpiece 1. Especially absorbed. Thereby, the modified region 7 is formed in the workpiece 1 (that is, internal absorption laser processing). In this case, since the laser beam L is hardly absorbed by the surface 3 of the workpiece 1, the surface 3 of the workpiece 1 is not melted. On the other hand, when the modified region 7 is formed on the front surface 3 or the back surface of the workpiece 1, the laser light L is absorbed particularly near the condensing point P located on the front surface 3 or the back surface, and the front surface 3 or the back surface Then, a removed portion such as a hole or a groove is formed (surface absorption laser processing).

  The modified region 7 is a region where the density, refractive index, mechanical strength, and other physical characteristics are different from the surroundings. Examples of the modified region 7 include a melt treatment region (meaning at least one of a region once solidified after melting, a region in a molten state, and a region in a state of being resolidified from melting), a crack region, and the like. In addition, there are a dielectric breakdown region, a refractive index change region, and the like, and there is a region in which these are mixed. Further, the modified region 7 includes a region where the density of the modified region 7 in the material of the workpiece 1 is changed compared to the density of the non-modified region, and a region where lattice defects are formed. When the material of the workpiece 1 is single crystal silicon, the modified region 7 can be said to be a high dislocation density region.

The area where the density of the melt processing area, the refractive index changing area, the density of the modified area 7 is changed as compared with the density of the non-modified area, and the area where lattice defects are formed are further included in the interior of these areas or the modified areas In some cases, cracks (cracks, microcracks) are included in the interface between the region 7 and the non-modified region. The included crack may be formed over the entire surface of the modified region 7, or may be formed in only a part or a plurality of parts. The workpiece 1 includes a substrate made of a crystal material having a crystal structure. For example, the workpiece 1 includes a substrate formed of at least one of gallium nitride (GaN), silicon (Si), silicon carbide (SiC), LiTaO ₃ , and sapphire (Al ₂ O ₃ ). In other words, the workpiece 1 includes, for example, a gallium nitride substrate, a silicon substrate, a SiC substrate, a LiTaO ₃ substrate, or a sapphire substrate. The crystal material may be either an anisotropic crystal or an isotropic crystal. Moreover, the workpiece 1 may include a substrate made of an amorphous material having an amorphous structure (amorphous structure), for example, a glass substrate.

  In the embodiment, the modified region 7 can be formed by forming a plurality of modified spots (processing marks) along the planned cutting line 5. In this case, the modified region 7 is formed by collecting a plurality of modified spots. The modified spot is a modified portion formed by one pulse shot of pulse laser light (that is, one pulse laser beam irradiation: laser shot). Examples of the modified spot include a crack spot, a melting treatment spot, a refractive index change spot, or a mixture of at least one of these. For the modified spot, the size and length of cracks to be generated are appropriately determined in consideration of the required cutting accuracy, required flatness of the cut surface, thickness, type, crystal orientation, etc. of the workpiece 1. Can be controlled. In the embodiment, the modified spot can be formed as the modified region 7 along the planned cutting line 5.

Next, a laser processing apparatus equipped with the objective lens driving device according to the embodiment will be described in detail. In the following description, directions orthogonal to each other in the horizontal plane are defined as an X-axis direction and a Y-axis direction, and a vertical direction is defined as a Z-axis direction. The Z-axis direction is the optical axis direction of the condenser lens unit 430 constituting the objective lens.
[Overall configuration of laser processing equipment]

  As shown in FIG. 7, the laser processing apparatus 200 includes an apparatus frame 210, a first moving mechanism 220, a support base 230, and a second moving mechanism 240. Further, the laser processing apparatus 200 includes a laser output unit 300, a laser condensing unit 400, and a control unit 500.

  The first moving mechanism 220 is attached to the device frame 210. The first moving mechanism 220 includes a first rail unit 221, a second rail unit 222, and a movable base 223. The first rail unit 221 is attached to the device frame 210. The first rail unit 221 is provided with a pair of rails 221a and 221b extending along the Y-axis direction. The second rail unit 222 is attached to the pair of rails 221a and 221b of the first rail unit 221 so as to be movable along the Y-axis direction. The second rail unit 222 is provided with a pair of rails 222a and 222b extending along the X-axis direction. The movable base 223 is attached to the pair of rails 222a and 222b of the second rail unit 222 so as to be movable along the X-axis direction. The movable base 223 can rotate around an axis parallel to the Z-axis direction as a center line.

  The support base 230 is attached to the movable base 223. The support base 230 supports the workpiece 1. The workpiece 1 includes, for example, a plurality of functional elements (a light receiving element such as a photodiode, a light emitting element such as a laser diode, or a circuit element formed as a circuit) on the surface side of a substrate made of a semiconductor material such as silicon. It is formed in a matrix. When the workpiece 1 is supported on the support base 230, for example, the surface 1a (a plurality of functional elements) of the workpiece 1 is formed on the film 12 stretched on the annular frame 11 as shown in FIG. Side surface) is affixed. The support base 230 supports the workpiece 1 by holding the frame 11 with a clamp and adsorbing the film 12 with a vacuum chuck table. On the support base 230, a plurality of cutting lines 5 a parallel to each other and a plurality of cutting lines 5 b parallel to each other are set on the workpiece 1 in a lattice shape so as to pass between adjacent functional elements. The

  As shown in FIG. 7, the support base 230 is moved along the Y-axis direction by the operation of the second rail unit 222 in the first moving mechanism 220. Further, the support base 230 is moved along the X-axis direction when the movable base 223 operates in the first moving mechanism 220. Further, the support base 230 is rotated about the axis parallel to the Z-axis direction as the center line by the movement of the movable base 223 in the first moving mechanism 220. As described above, the support base 230 is attached to the apparatus frame 210 so as to be movable along the X-axis direction and the Y-axis direction and to be rotatable about an axis parallel to the Z-axis direction.

  The laser output unit 300 is attached to the apparatus frame 210. The laser condensing unit 400 is attached to the apparatus frame 210 via the second moving mechanism 240. The laser condensing unit 400 is moved along the Z-axis direction by the operation of the second moving mechanism 240. As described above, the laser condensing unit 400 is attached to the apparatus frame 210 so as to be movable along the Z-axis direction with respect to the laser output unit 300.

  The control unit 500 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The control unit 500 controls the operation of each unit of the laser processing apparatus 200.

  As an example, in the laser processing apparatus 200, a modified region is formed inside the processing target 1 along each scheduled cutting line 5a, 5b (see FIG. 8) as follows.

  First, the processing object 1 is supported on the support base 230 so that the back surface 1b (see FIG. 8) of the processing object 1 becomes a laser light incident surface, and each scheduled cutting line 5a of the processing object 1 is in the X-axis direction. In the direction parallel to Subsequently, the laser condensing unit is moved by the second moving mechanism 240 so that the condensing point of the laser light L is located at a position separated from the laser light incident surface of the processing object 1 by a predetermined distance inside the processing object 1. 400 is moved. Subsequently, the focusing point of the laser beam L relatively moves along each scheduled cutting line 5a while the distance between the laser beam incident surface of the workpiece 1 and the focusing point of the laser beam L is maintained constant. Be made. As a result, a modified region is formed in the workpiece 1 along each planned cutting line 5a.

  When the formation of the modified region along each scheduled cutting line 5a is completed, the support base 230 is rotated by the first moving mechanism 220, and each scheduled cutting line 5b of the workpiece 1 is parallel to the X-axis direction. Adapted to. Subsequently, the laser condensing unit is moved by the second moving mechanism 240 so that the condensing point of the laser light L is located at a position separated from the laser light incident surface of the processing object 1 by a predetermined distance inside the processing object 1. 400 is moved. Subsequently, the focusing point of the laser beam L relatively moves along each scheduled cutting line 5b while the distance between the laser beam incident surface of the workpiece 1 and the focusing point of the laser beam L is maintained constant. Be made. As a result, a modified region is formed in the workpiece 1 along each planned cutting line 5b.

  Thus, in the laser processing apparatus 200, the direction parallel to the X-axis direction is the processing direction (scanning direction of the laser light L). In the laser processing apparatus 200, the X-axis direction is the extending direction of the planned cutting line 5 that scans the laser beam L. The scanning of the laser beam L is to move relatively along the planned cutting line 5 while irradiating the laser beam L.

  The relative movement of the condensing point of the laser beam L along each planned cutting line 5a and the relative movement of the condensing point of the laser beam L along each planned cutting line 5b are the first moving mechanism. This is implemented by moving the support base 230 along the X-axis direction by 220. Further, the relative movement of the condensing point of the laser beam L between each scheduled cutting line 5a and the relative movement of the condensing point of the laser beam L between each scheduled cutting line 5b are performed by the first moving mechanism 220. This is implemented by moving the support base 230 along the Y-axis direction.

  As shown in FIG. 9, the laser output unit 300 includes a mounting base 301, a cover 302, and a plurality of mirrors 303 and 304. Further, the laser output unit 300 includes a laser oscillator 310, a shutter 320, a λ / 2 wavelength plate unit 330, a polarizing plate unit 340, a beam expander 350, and a mirror unit 360.

  The mounting base 301 supports a plurality of mirrors 303, 304, a laser oscillator 310, a shutter 320, a λ / 2 wavelength plate unit 330, a polarizing plate unit 340, a beam expander 350, and a mirror unit 360. The plurality of mirrors 303 and 304, the laser oscillator 310, the shutter 320, the λ / 2 wavelength plate unit 330, the polarizing plate unit 340, the beam expander 350 and the mirror unit 360 are attached to the main surface 301 a of the attachment base 301. The mounting base 301 is a plate-like member and can be attached to and detached from the apparatus frame 210 (see FIG. 7). The laser output unit 300 is attached to the apparatus frame 210 via the attachment base 301. That is, the laser output unit 300 can be attached to and detached from the apparatus frame 210.

  The cover 302 includes a plurality of mirrors 303 and 304, a laser oscillator 310, a shutter 320, a λ / 2 wavelength plate unit 330, a polarizing plate unit 340, a beam expander 350, and a mirror unit 360 on the main surface 301a of the mounting base 301. Covering. The cover 302 can be attached to and detached from the mounting base 301.

  The laser oscillator 310 oscillates a pulse of the linearly polarized laser beam L along the X-axis direction. The wavelength of the laser beam L emitted from the laser oscillator 310 is included in any of the wavelength bands of 500 to 550 nm, 1000 to 1150 nm, or 1300 to 1400 nm. Laser light L having a wavelength band of 500 to 550 nm is suitable for internal absorption laser processing for a substrate made of, for example, sapphire. The laser light L in each wavelength band of 1000 to 1150 nm and 1300 to 1400 nm is suitable for internal absorption laser processing for a substrate made of silicon, for example. The polarization direction of the laser light L emitted from the laser oscillator 310 is, for example, a direction parallel to the Y-axis direction. The laser beam L emitted from the laser oscillator 310 is reflected by the mirror 303 and enters the shutter 320 along the Y-axis direction.

  In the laser oscillator 310, ON / OFF of the output of the laser beam L is switched as follows. When the laser oscillator 310 is configured by a solid-state laser, ON / OFF of a Q switch (AOM (acousto-optic modulator), EOM (electro-optic modulator), etc.) provided in the resonator is switched, ON / OFF of the output of the laser beam L is switched at high speed. When the laser oscillator 310 is composed of a fiber laser, the output of the laser light L can be turned on and off at high speed by switching the output of the semiconductor laser constituting the seed laser and the amplifier (excitation) laser. Can be switched to. When the laser oscillator 310 uses an external modulation element, ON / OFF of the output of the laser beam L can be performed at a high speed by switching ON / OFF of the external modulation element (AOM, EOM, etc.) provided outside the resonator. Can be switched to.

  The shutter 320 opens and closes the optical path of the laser light L by a mechanical mechanism. As described above, ON / OFF switching of the output of the laser light L from the laser output unit 300 is performed by ON / OFF switching of the output of the laser light L in the laser oscillator 310, but a shutter 320 is provided. For example, the laser output L is prevented from being unexpectedly emitted from the laser output unit 300. The laser light L that has passed through the shutter 320 is reflected by the mirror 304 and sequentially enters the λ / 2 wavelength plate unit 330 and the polarizing plate unit 340 along the X-axis direction.

  The λ / 2 wavelength plate unit 330 and the polarizing plate unit 340 function as an output adjusting unit that adjusts the output (light intensity) of the laser light L. Further, the λ / 2 wavelength plate unit 330 and the polarizing plate unit 340 function as a polarization direction adjusting unit that adjusts the polarization direction of the laser light L. The laser light L that has sequentially passed through the λ / 2 wavelength plate unit 330 and the polarizing plate unit 340 enters the beam expander 350 along the X-axis direction.

  The beam expander 350 collimates (collimates) the laser light L while adjusting the diameter of the laser light L. The beam expander 350 includes a diverging lens and a collimating lens, and the collimating lens is configured to be movable along the optical axis direction (details will be described later). The laser light L that has passed through the beam expander 350 enters the mirror unit 360 along the X-axis direction.

  The mirror unit 360 includes a support base 361 and a plurality of mirrors 362 and 363. The support base 361 supports a plurality of mirrors 362 and 363. The support base 361 is attached to the attachment base 301 so that the position can be adjusted along the X-axis direction and the Y-axis direction. The mirror 362 reflects the laser light L that has passed through the beam expander 350 in the Y-axis direction. The mirror 362 is attached to the support base 361 so that the reflection surface thereof can be adjusted in angle around an axis parallel to the Z axis, for example. The mirror 363 reflects the laser light L reflected by the mirror 362 in the Z-axis direction. The mirror 363 is attached to the support base 361 so that the reflection surface thereof can be angle-adjusted around an axis parallel to the X-axis, for example, and the position can be adjusted along the Y-axis direction. The laser light L reflected by the mirror 363 passes through an opening 361a formed in the support base 361 and enters the laser condensing unit 400 (see FIG. 7) along the Z-axis direction. In other words, the emission direction of the laser light L from the laser output unit 300 matches the moving direction of the laser condensing unit 400. As described above, each of the mirrors 362 and 363 has a mechanism for adjusting the angle of the reflecting surface. In the mirror unit 360, the position adjustment of the support base 361 relative to the mounting base 301, the position adjustment of the mirror 363 relative to the support base 361, and the angle adjustment of the reflection surfaces of the mirrors 362 and 363 are performed. The position and angle of the optical axis of the emitted laser light L are matched with the laser condensing unit 400. That is, the plurality of mirrors 362 and 363 are configured to adjust the optical axis of the laser light L emitted from the laser output unit 300.

  As shown in FIG. 10, the laser condensing unit 400 has a housing 401. The casing 401 has a rectangular parallelepiped shape whose longitudinal direction is the Y-axis direction. A second moving mechanism 240 is attached to one side surface 401e of the housing 401 (see FIGS. 11 and 13). The casing 401 is provided with a cylindrical light incident portion 401a so as to face the opening 361a of the mirror unit 360 in the Z-axis direction. The light incident part 401 a causes the laser light L emitted from the laser output part 300 to enter the housing 401. The mirror unit 360 and the light incident part 401a are separated from each other by a distance that does not contact each other when the laser condensing part 400 is moved along the Z-axis direction by the second moving mechanism 240.

  As shown in FIGS. 11 and 12, the laser condensing unit 400 includes a mirror 402 and a dichroic mirror 403. Further, the laser condensing unit 400 includes a reflective spatial light modulator 410, a 4f lens unit 420, a condensing lens unit 430, an objective lens driving device 440, and a pair of distance measuring sensors 450. Yes.

  The mirror 402 is attached to the bottom surface 401b of the housing 401 so as to face the light incident portion 401a in the Z-axis direction. The mirror 402 reflects the laser light L incident in the housing 401 via the light incident portion 401a in a direction parallel to the XY plane. Laser light L collimated by the beam expander 350 of the laser output unit 300 enters the mirror 402 along the Z-axis direction. That is, the laser beam L enters the mirror 402 as parallel light along the Z-axis direction. Therefore, even if the laser focusing unit 400 is moved along the Z-axis direction by the second moving mechanism 240, the state of the laser light L incident on the mirror 402 along the Z-axis direction is maintained constant. The laser beam L reflected by the mirror 402 is incident on the reflective spatial light modulator 410.

  The reflective spatial light modulator 410 is attached to the end 401c of the housing 401 in the Y-axis direction with the reflective surface 410a facing the housing 401. The reflective spatial light modulator 410 is, for example, a liquid crystal on silicon (LCOS) spatial light modulator (SLM), which modulates the laser light L and converts the laser light L to the Y axis. Reflect in the direction. The laser beam L modulated and reflected by the reflective spatial light modulator 410 is incident on the 4f lens unit 420 along the Y-axis direction. Here, in the plane parallel to the XY plane, the optical axis of the laser light L incident on the reflective spatial light modulator 410 and the optical axis of the laser light L emitted from the reflective spatial light modulator 410 are formed. The angle α is an acute angle (for example, 10 to 60 °). That is, the laser light L is reflected at an acute angle along the XY plane by the reflective spatial light modulator 410. This is because the incident angle and the reflection angle of the laser light L are suppressed to suppress the decrease in diffraction efficiency, and the performance of the reflective spatial light modulator 410 is sufficiently exhibited. In the reflective spatial light modulator 410, for example, the thickness of the light modulation layer in which liquid crystal is used is extremely thin, about several μm to several tens of μm. Therefore, the reflection surface 410a is a light incident / exit surface of the light modulation layer. Can be regarded as substantially the same.

  The 4f lens unit 420 includes a holder 421, a lens 422 on the reflective spatial light modulator 410 side, a lens 423 on the condenser lens unit 430 side, and a slit member 424. The holder 421 holds a pair of lenses 422 and 423 and a slit member 424. The holder 421 maintains a constant positional relationship between the pair of lenses 422 and 423 and the slit member 424 in the direction along the optical axis of the laser light L. The pair of lenses 422 and 423 constitute a double-sided telecentric optical system in which the reflecting surface 410a of the reflective spatial light modulator 410 and the entrance pupil surface 430a of the condenser lens unit 430 are in an imaging relationship. As a result, the image of the laser beam L on the reflection surface 410a of the reflective spatial light modulator 410 is transferred (imaged) to the entrance pupil plane 430a of the condenser lens unit 430. A slit 424 a is formed in the slit member 424. The slit 424 a is located between the lens 422 and the lens 423 and in the vicinity of the focal plane of the lens 422. An unnecessary portion of the laser light L modulated and reflected by the reflective spatial light modulator 410 is blocked by the slit member 424. The laser light L that has passed through the 4f lens unit 420 enters the dichroic mirror 403 along the Y-axis direction.

  The dichroic mirror 403 reflects most of the laser light L (for example, 95 to 99.5%) in the Z-axis direction, and partially (for example, 0.5 to 5%) of the laser light L in the Y-axis direction. Permeate along. Most of the laser light L is reflected by the dichroic mirror 403 at a right angle along the ZX plane. The laser beam L reflected by the dichroic mirror 403 enters the condenser lens unit 430 along the Z-axis direction.

  The condensing lens unit 430 constitutes an objective lens that condenses the laser light L onto the workpiece 1. The condenser lens unit 430 is attached to the end 401d of the housing 401 in the Y-axis direction (the end opposite to the end 401c) via the objective lens driving device 440. The condenser lens unit 430 has a cylindrical outer shape whose axial direction is the Z-axis direction. The condenser lens unit 430 includes a holder 431 and a plurality of lenses 432. The holder 431 holds a plurality of lenses 432. The plurality of lenses 432 focuses the laser light L on the workpiece 1 (see FIG. 7) supported by the support base 230. The objective lens driving device 440 is a driving mechanism that drives the condenser lens unit 430 in the laser processing device 200. The objective lens driving device 440 moves the condenser lens unit 430 along the Z-axis direction, which is the optical axis direction, by the driving force of the piezoelectric element (details will be described later).

  The pair of distance measuring sensors 450 are attached to the end portion 401d of the housing 401 so as to be positioned on both sides of the condenser lens unit 430 in the X-axis direction. Each distance measuring sensor 450 emits distance measuring light (for example, laser light) to the laser light incident surface of the workpiece 1 (see FIG. 7) supported by the support base 230, and the laser light is incident thereon. By detecting the distance measuring light reflected by the surface, the displacement data of the laser light incident surface of the workpiece 1 is acquired. As the distance measuring sensor 450, a sensor such as a triangular distance measuring method, a laser confocal method, a white confocal method, a spectral interference method, an astigmatism method, or the like can be used.

  In the laser processing apparatus 200, as described above, the direction parallel to the X-axis direction is the processing direction (scanning direction of the laser light L). Therefore, when the condensing point of the laser beam L is moved relatively along each of the scheduled cutting lines 5 a and 5 b, the pair of distance measuring sensors 450 precedes the condensing lens unit 430. The distance measuring sensor 450 acquires displacement data of the laser light incident surface of the workpiece 1 along the respective scheduled cutting lines 5a and 5b. Then, the objective lens driving device 440 is based on the displacement data acquired by the distance measuring sensor 450 so that the distance between the laser light incident surface of the workpiece 1 and the condensing point of the laser light L is maintained constant. Then, the condenser lens unit 430 is moved along the Z-axis direction.

  The laser condensing unit 400 includes a beam splitter 461, a pair of lenses 462 and 463, and a profile acquisition camera 464. The beam splitter 461 divides the laser light L transmitted through the dichroic mirror 403 into a reflection component and a transmission component. The laser light L reflected by the beam splitter 461 sequentially enters the pair of lenses 462 and 463 and the profile acquisition camera 464 along the Z-axis direction. The pair of lenses 462 and 463 constitute a bilateral telecentric optical system in which the entrance pupil plane 430a of the condenser lens unit 430 and the imaging plane of the profile acquisition camera 464 are in an imaging relationship. Thereby, the image of the laser beam L on the entrance pupil plane 430a of the condenser lens unit 430 is transferred to the imaging plane of the profile acquisition camera 464. As described above, the image of the laser beam L on the entrance pupil plane 430a of the condenser lens unit 430 is an image of the laser beam L modulated by the reflective spatial light modulator 410. Therefore, the laser processing apparatus 200 can grasp the operating state of the reflective spatial light modulator 410 by monitoring the imaging result of the profile acquisition camera 464.

  Further, the laser condensing unit 400 includes a beam splitter 471, a lens 472, and a spot observation camera 473 which is an imaging device for observing the spot position (pointing) of the laser light L. The beam splitter 471 divides the laser light L transmitted through the beam splitter 461 into a reflection component and a transmission component. The laser beam L reflected by the beam splitter 471 sequentially enters the lens 472 and the spot observation camera 473 along the Z-axis direction. The lens 472 collects the incident laser light L toward the imaging surface of the spot observation camera 473. In the laser processing apparatus 200, while monitoring the imaging results of the profile acquisition camera 464 and the spot observation camera 473, the mirror unit 360 adjusts the position of the support base 361 relative to the mounting base 301 and the mirror 363 relative to the support base 361. By adjusting the position and adjusting the angle of the reflecting surfaces of the mirrors 362 and 363 (see FIGS. 9 and 10), the optical axis shift of the laser beam L incident on the condenser lens unit 430 (the condenser lens unit). The positional deviation of the intensity distribution of the laser light with respect to 430 and the angular deviation of the optical axis of the laser light L with respect to the condenser lens unit 430 can be corrected.

  The plurality of beam splitters 461 and 471 are disposed in a cylindrical body 404 that extends from the end 401 d of the housing 401 along the Y-axis direction. The pair of lenses 462 and 463 are arranged in a cylinder 405 erected on the cylinder 404 along the Z-axis direction, and the profile acquisition camera 464 is arranged at the end of the cylinder 405. Yes. The lens 472 is arranged in a cylinder 406 erected on the cylinder 404 along the Z-axis direction, and the spot observation camera 473 is arranged at the end of the cylinder 406. The cylinder body 405 and the cylinder body 406 are arranged in parallel with each other in the Y-axis direction. The laser light L that has passed through the beam splitter 471 may be absorbed by a damper or the like provided at the end of the cylindrical body 404, or may be used for an appropriate application. .

  As shown in FIGS. 12 and 13, the laser condensing unit 400 includes a visible light source 481, a plurality of lenses 482, a reticle 483, a mirror 484, a half mirror 485, a beam splitter 486, and a lens 487. And an observation camera 488. The visible light source 481 emits visible light V along the Z-axis direction. The plurality of lenses 482 collimate the visible light V emitted from the visible light source 481. The reticle 483 gives a scale line to the visible light V. The mirror 484 reflects the visible light V collimated by the plurality of lenses 482 in the X-axis direction. The half mirror 485 divides the visible light V reflected by the mirror 484 into a reflection component and a transmission component. The visible light V reflected by the half mirror 485 sequentially passes through the beam splitter 486 and the dichroic mirror 403 along the Z-axis direction, and is processed object 1 supported by the support base 230 via the condenser lens unit 430. (See FIG. 7).

  The visible light V irradiated to the workpiece 1 is reflected by the laser light incident surface of the workpiece 1, enters the dichroic mirror 403 through the condenser lens unit 430, and reaches the dichroic mirror 403 along the Z-axis direction. Transparent. The beam splitter 486 divides the visible light V transmitted through the dichroic mirror 403 into a reflection component and a transmission component. The visible light V that has passed through the beam splitter 486 passes through the half mirror 485, and sequentially enters the lens 487 and the observation camera 488 along the Z-axis direction. The lens 487 collects the incident visible light V on the imaging surface of the observation camera 488. In the laser processing apparatus 200, the state of the processing target object 1 can be grasped by observing the imaging result of the observation camera 488.

  The mirror 484, the half mirror 485, and the beam splitter 486 are disposed in a holder 407 attached on the end 401 d of the housing 401. The plurality of lenses 482 and the reticle 483 are arranged in a cylinder 408 erected on the holder 407 along the Z-axis direction, and the visible light source 481 is arranged at the end of the cylinder 408. The lens 487 is disposed in a cylindrical body 409 erected on the holder 407 along the Z-axis direction, and the observation camera 488 is disposed at the end of the cylindrical body 409. The cylinder body 408 and the cylinder body 409 are arranged side by side in the X-axis direction. The visible light V transmitted through the half mirror 485 along the X-axis direction and the visible light V reflected in the X-axis direction by the beam splitter 486 are absorbed by a damper or the like provided on the wall portion of the holder 407, respectively. Or may be used for an appropriate application.

  In the laser processing apparatus 200, replacement of the laser output unit 300 (particularly the laser oscillator 310) is assumed. This is because the wavelength of the laser beam L suitable for processing varies depending on the specification, processing conditions, and the like of the processing object 1. Therefore, a plurality of laser output units 300 having different wavelengths of the emitted laser light L are prepared. Here, the laser output unit 300 included in the wavelength band of the emitted laser light L in the wavelength band of 500 to 550 nm, the laser output unit 300 included in the wavelength band of the wavelength of the emitted laser light L in the range of 1000 to 1150 nm, and emitted. A laser output unit 300 is prepared in which the wavelength of the laser light L is included in a wavelength band of 1300 to 1400 nm.

On the other hand, in the laser processing apparatus 200, replacement of the laser condensing unit 400 is not assumed. This is because the laser condensing unit 400 supports multiple wavelengths (corresponding to a plurality of wavelength bands that are not continuous with each other). Specifically, the mirror 402, the reflective spatial light modulator 410, the pair of lenses 422 and 423 of the 4f lens unit 420, the dichroic mirror 403, the lens 432 of the condenser lens unit 430, and the like correspond to multiple wavelengths. . Here, the laser condensing unit 400 corresponds to wavelength bands of 500 to 550 nm, 1000 to 1150 nm, and 1300 to 1400 nm. This is realized by designing each configuration of the laser focusing section 400 so that desired optical performance is satisfied, such as coating each configuration of the laser focusing section 400 with a predetermined dielectric multilayer film. The In the laser output unit 300, the λ / 2 wavelength plate unit 330 has a λ / 2 wavelength plate, and the polarizing plate unit 340 has a polarizing plate. The λ / 2 wavelength plate and the polarizing plate are optical elements having high wavelength dependency. Therefore, the λ / 2 wavelength plate unit 330 and the polarizing plate unit 340 are provided in the laser output unit 300 as different configurations for each wavelength band.
[Optical path and polarization direction of laser light in laser processing equipment]

  In the laser processing apparatus 200, the polarization direction of the laser light L focused on the workpiece 1 supported by the support base 230 is a direction parallel to the X-axis direction as shown in FIG. It corresponds to the processing direction (scanning direction of the laser beam L). Here, in the reflective spatial light modulator 410, the laser light L is reflected as P-polarized light. This is because the surface parallel to the plane including the optical axis of the laser beam L entering and exiting the reflective spatial light modulator 410 when liquid crystal is used in the light modulation layer of the reflective spatial light modulator 410. This is because when the liquid crystal is oriented so that the liquid crystal molecules are tilted, the phase modulation is applied to the laser light L with the rotation of the polarization plane being suppressed (for example, Japanese Patent No. 3878758). reference). On the other hand, the dichroic mirror 403 reflects the laser light L as S-polarized light. This is because when the laser beam L is reflected as S-polarized light rather than the laser beam L as P-polarized light, the number of coatings of the dielectric multilayer film for making the dichroic mirror 403 compatible with multiple wavelengths decreases. This is because the design of the dichroic mirror 403 is facilitated.

  Therefore, in the laser condensing unit 400, the optical path from the mirror 402 to the dichroic mirror 403 via the reflective spatial light modulator 410 and the 4f lens unit 420 is set along the XY plane. The optical path reaching the condenser lens unit 430 is set along the Z-axis direction.

  As shown in FIG. 9, in the laser output unit 300, the optical path of the laser light L is set along the X-axis direction or the Y-axis direction. Specifically, the optical path from the laser oscillator 310 to the mirror 303 and the optical path from the mirror 304 to the mirror unit 360 via the λ / 2 wavelength plate unit 330, the polarizing plate unit 340, and the beam expander 350 are the X axis. The optical path from the mirror 303 to the mirror 304 via the shutter 320 and the optical path from the mirror 362 to the mirror 363 in the mirror unit 360 are set to be along the Y-axis direction. Yes.

  The laser light L traveling from the laser output unit 300 to the laser condensing unit 400 along the Z-axis direction is reflected in a direction parallel to the XY plane by the mirror 402 as shown in FIG. Incident on the vessel 410. At this time, in a plane parallel to the XY plane, the optical axis of the laser light L incident on the reflective spatial light modulator 410 and the optical axis of the laser light L emitted from the reflective spatial light modulator 410 are: The angle α is an acute angle. On the other hand, as described above, in the laser output unit 300, the optical path of the laser light L is set along the X-axis direction or the Y-axis direction.

Therefore, in the laser output unit 300, the λ / 2 wavelength plate unit 330 and the polarizing plate unit 340 are not only used as an output adjustment unit that adjusts the output of the laser light L, but also the polarization direction adjustment that adjusts the polarization direction of the laser light L. It is necessary to function as a part.
[Reflective spatial light modulator]

  As shown in FIG. 14, the reflective spatial light modulator 410 includes a silicon substrate 213, a drive circuit layer 914, a plurality of pixel electrodes 214, a reflective film 215 such as a dielectric multilayer mirror, an alignment film 999a, a liquid crystal layer ( Display portion) 216, an alignment film 999b, a transparent conductive film 217, and a transparent substrate 218 such as a glass substrate are stacked in this order.

  The transparent substrate 218 has a surface 218a along the XY plane. This surface 218a constitutes a reflective surface 410a of the reflective spatial light modulator 410. The transparent substrate 218 is made of a light transmissive material such as glass, for example, and transmits the laser light L having a predetermined wavelength incident from the surface 218 a of the reflective spatial light modulator 410 into the reflective spatial light modulator 410. The transparent conductive film 217 is formed on the back surface of the transparent substrate 218 and is made of a conductive material (for example, ITO) that transmits the laser light L.

  The plurality of pixel electrodes 214 are arranged in a matrix on the silicon substrate 213 along the transparent conductive film 217. Each pixel electrode 214 is made of a metal material such as aluminum. The surfaces 214a of the plurality of pixel electrodes 214 are processed flat and smoothly. The plurality of pixel electrodes 214 are driven by an active matrix circuit provided in the drive circuit layer 914.

  The active matrix circuit is provided between the plurality of pixel electrodes 214 and the silicon substrate 213. The active matrix circuit controls the voltage applied to each pixel electrode 214 in accordance with the light image to be output from the reflective spatial light modulator 410. Such an active matrix circuit includes, for example, a first driver circuit that controls the applied voltage of each pixel column arranged in the X-axis direction (not shown) and a second driver circuit that controls the applied voltage of each pixel column arranged in the Y-axis direction. A driver circuit is configured so that a predetermined voltage is applied to the pixel electrode 214 of the pixel designated by the controller 500 in both driver circuits.

  The alignment films 999a and 999b are disposed on both end faces of the liquid crystal layer 216, and align liquid crystal molecule groups in a certain direction. The alignment films 999a and 999b are made of, for example, a polymer material such as polyimide, and a contact surface with the liquid crystal layer 216 is subjected to a rubbing process or the like.

  The liquid crystal layer 216 is disposed between the plurality of pixel electrodes 214 and the transparent conductive film 217, and modulates the laser light L according to the electric field formed by each pixel electrode 214 and the transparent conductive film 217. That is, when a voltage is applied to each pixel electrode 214 by the active matrix circuit of the drive circuit layer 914, an electric field is formed between the transparent conductive film 217 and each pixel electrode 214, and the electric field formed in the liquid crystal layer 216. The alignment direction of the liquid crystal molecules 216a changes depending on the size of the liquid crystal molecules. When the laser light L passes through the transparent substrate 218 and the transparent conductive film 217 and enters the liquid crystal layer 216, the laser light L is modulated by the liquid crystal molecules 216 a while passing through the liquid crystal layer 216, and is reflected on the reflective film 215. After the reflection, the light is again modulated by the liquid crystal layer 216 and emitted.

At this time, a voltage applied to each pixel electrode 214 is controlled by the control unit 500 (see FIG. 7), and a portion sandwiched between the transparent conductive film 217 and each pixel electrode 214 in the liquid crystal layer 216 according to the voltage. The refractive index of the liquid crystal layer 216 at the position corresponding to each pixel changes. With this change in refractive index, the phase of the laser light L can be changed for each pixel of the liquid crystal layer 216 in accordance with the applied voltage. That is, phase modulation corresponding to the hologram pattern can be applied to each pixel by the liquid crystal layer 216. In other words, a modulation pattern as a hologram pattern for applying modulation can be displayed on the liquid crystal layer 216 of the reflective spatial light modulator 410. The wavefront of the laser light L that enters and passes through the modulation pattern is adjusted, and the phase of the component in the direction orthogonal to the traveling direction is shifted in each light beam constituting the laser light L. Therefore, by appropriately setting the modulation pattern to be displayed on the reflective spatial light modulator 410, the laser light L can be modulated (for example, the intensity, amplitude, phase, polarization, etc. of the laser light L can be modulated).
[4f lens unit]

  As described above, the pair of lenses 422 and 423 of the 4f lens unit 420 includes both-side telecentric optics in which the reflecting surface 410a of the reflective spatial light modulator 410 and the entrance pupil plane 430a of the condenser lens unit 430 are in an imaging relationship. The system is configured. Specifically, as shown in FIG. 15, the distance of the optical path between the center of the lens 422 on the reflective spatial light modulator 410 side and the reflective surface 410a of the reflective spatial light modulator 410 is the first of the lenses 422. The focal length f1 is obtained, and the distance of the optical path between the center of the lens 423 on the condenser lens unit 430 side and the entrance pupil plane 430a of the condenser lens unit 430 is the second focal length f2 of the lens 423, and the center of the lens 422 is obtained. And the center of the lens 423 is the sum of the first focal length f1 and the second focal length f2 (ie, f1 + f2). Of the optical path from the reflective spatial light modulator 410 to the condenser lens unit 430, the optical path between the pair of lenses 422 and 423 is a straight line.

  In the laser processing apparatus 200, from the viewpoint of increasing the effective diameter of the laser light L on the reflecting surface 410a of the reflective spatial light modulator 410, the magnification M of the both-side telecentric optical system is 0.5 <M <1 (reducing system). ) Is satisfied. As the effective diameter of the laser beam L on the reflecting surface 410a of the reflective spatial light modulator 410 is larger, the laser beam L is modulated with a finer phase pattern. From the standpoint of suppressing an increase in the optical path of the laser light L from the reflective spatial light modulator 410 to the condenser lens unit 430, it is more preferable that 0.6 ≦ M ≦ 0.95. Here, (magnification M of both-side telecentric optical system) = (size of image on entrance pupil plane 430a of condenser lens unit 430) / (size of object on reflection plane 410a of reflective spatial light modulator 410) ). In the case of the laser processing apparatus 200, the magnification M of the both-side telecentric optical system, the first focal length f1 of the lens 422, and the second focal length f2 of the lens 423 satisfy M = f2 / f1.

From the viewpoint of reducing the effective diameter of the laser light L on the reflection surface 410a of the reflective spatial light modulator 410, even if the magnification M of the double-sided telecentric optical system satisfies 1 <M <2 (enlargement system). Good. The smaller the effective diameter of the laser light L at the reflection surface 410a of the reflection type spatial light modulator 410, the smaller the magnification of the beam expander 350 (see FIG. 9), and the reflection type in the plane parallel to the XY plane. The angle α (see FIG. 11) formed by the optical axis of the laser light L incident on the spatial light modulator 410 and the optical axis of the laser light L emitted from the reflective spatial light modulator 410 becomes small. From the standpoint of suppressing an increase in the optical path of the laser light L from the reflective spatial light modulator 410 to the condenser lens unit 430, it is more preferable that 1.05 ≦ M ≦ 1.7.
[Objective lens drive unit]

  Next, the objective lens driving device 440 according to the first embodiment will be described in detail. For convenience, in the objective lens driving device 440, the processing object 1 side in the Z-axis direction will be described as the lower side, and the opposite side will be described as the upper side.

  As shown in FIGS. 16 to 20, the objective lens driving device 440 holds the condensing lens unit 430 in the laser processing apparatus 200 (see FIG. 7) and moves the condensing lens unit 430 along the Z-axis direction. It is a device to move. The objective lens driving device 440 has a plane-symmetric structure with a YZ plane passing through the optical axis G (hereinafter also simply referred to as “optical axis G”) of the condenser lens unit 430 to be held and orthogonal to the X direction as a symmetry plane. Has been. The objective lens driving device 440 includes a fixing member 10, a mounting member 20, a piezoelectric element 30, and a pair of driving housings 40.

  The fixing member 10, the mounting member 20, and the pair of drive housings 40 are integrally formed. The fixing member 10, the mounting member 20, and the pair of drive housings 40 are integrally molded products that are integrally formed with each other by cutting using, for example, wire electric discharge machining without using bonding and mechanical joining. As a material for the fixing member 10, the mounting member 20, and the pair of drive housings 40, a stainless alloy is used.

  The fixing member 10 has a rectangular parallelepiped shape in which the X-axis direction is the longitudinal direction and the Y-axis direction is the thickness direction. The fixing member 10 is fixed to the casing 401 (see FIG. 12) of the laser condensing unit 400 in the laser processing apparatus 200 with a screw or the like.

  The attachment member 20 is a member to which the condenser lens unit 430 is attached. The attachment member 20 has an annular plate-shaped ring portion 21 whose axial direction is the Z-axis direction. The inner diameter of the ring portion 21 corresponds to the outer diameter of the condenser lens unit 430. A condenser lens unit 430 is coaxially inserted and screwed into the ring portion 21 (attached by a screwing action).

  The piezoelectric element 30 is a power source of the objective lens driving device 440. As the piezoelectric element 30, a laminated piezoelectric element is used. The piezoelectric element 30 is formed in a long column shape. The piezoelectric element 30 is displaced (elongated in this case) in the axial direction of the piezoelectric element 30 according to the electric power when the electric power is applied. The piezoelectric element 30 is not potted with a resin such as silicone resin, and at least a part of the piezoelectric element 30 is not covered with the resin. That is, at least a part of the piezoelectric element 30 is exposed and exposed to air. The piezoelectric element 30 is connected to a control unit 500 (see FIG. 7), and the displacement amount is controlled by the control unit 500.

  The drive housing 40 is a housing that houses the piezoelectric element 30 therein. The drive housing 40 includes a first connection portion 41 connected to the fixing member 10, a second connection portion 42 connected to the attachment member 20, and a pair of first and second connection portions 41 and 42. And a plate portion 43. The drive housing 40 moves in the optical axis direction with respect to the fixed member 10 by being distorted in the optical axis direction by a force acting by extending the piezoelectric element 30.

  The first connection portion 41 constitutes the fixed side (non-moving portion) of the drive housing 40. The first connection portion 41 is provided so as to be continuous with the fixing member 10. The second connection portion 42 constitutes the movable side of the drive housing 40. The second connecting portion 42 is provided so as to be continuous with the mounting member 20. The first connection portion 41 and the second connection portion 42 are block-like (lumped) portions having high rigidity in the drive housing 40. The 1st connection part 41 and the 2nd connection part 42 are mutually spaced apart and provided in the Y-axis direction. Specifically, the first connection portion 41 is disposed on one end side in the Y-axis direction of the drive housing 40, and the second connection portion 42 is disposed on the other end side in the Y direction of the drive housing 40. .

  The pair of plate portions 43 has a plate shape whose thickness direction is the Z-axis direction, and extends in the Y-axis direction from the first connection portion 41 toward the second connection portion 42. The pair of plate portions 43 oppose each other. The thickness of both end portions in the Y-axis direction (extending direction) of the plate portion 43 is thinner than the thickness of the plate portion 43 other than the both end portions. Thereby, the rigidity of the both ends of the board part 43 is lower than the other than that. The first connection portion 41, the second connection portion 42, and the pair of plate portions 43 define an accommodation space R that accommodates the piezoelectric element 30.

  The drive housing 40 is disposed in the accommodation space R and is connected to the first connection portion 41, and is disposed in the accommodation space R and is connected to the second connection portion 42. And a second rotation support portion 46.

  The first rotation support portion 45 rotatably supports one end portion of the piezoelectric element 30 in the longitudinal direction. The first rotation support portion 45 is attached so as to come into contact with one end surface of the piezoelectric element 30. The first rotation support portion 45 is swingably provided on the lower side of the wall surface forming the accommodation space R of the first connection portion 41. The second rotation support unit 46 rotatably supports the other end portion of the piezoelectric element 30 in the longitudinal direction. The second rotation support portion 46 is attached so as to contact the other end surface of the piezoelectric element 30. The second rotation support portion 46 is swingably provided on the upper side of the wall surface forming the accommodation space R of the second connection portion 42. Accordingly, the drive housing 40 accommodates the piezoelectric element 30 in the accommodation space R in a state where the displacement direction (longitudinal direction) of the piezoelectric element 30 is inclined in the Z-axis direction with respect to the Y-axis. . That is, the displacement direction of the piezoelectric element 30 is a direction orthogonal to the X-axis direction along the planned cutting line 5, and specifically, a direction intersecting the Y-axis direction on the YZ plane. The drive housing 40 may be provided with a cover so as to close the accommodation space R from the outside.

  FIG. 21 is a diagram modeling the structure of the drive housing 40. FIG. 21A shows the piezoelectric element 30 when it is not extended, and FIG. 21B shows the piezoelectric element 30 when it is extended. As shown in FIGS. 21A and 21B, the drive housing 40 can be modeled by a structural model ML having a pivot that is a pivot axis. In the structural model ML, columns 51 and 52 facing in the Y-axis direction and beams 53 and 54 facing in the Z-axis direction are connected by a pivot 55 to form a rectangular frame 56. An elongating member 57 that extends and extends in the Z-axis direction with respect to the Y-axis is connected to the columns 51 and 52 via pivots 58 and 59 in the rectangular frame 56. The columns 51 and 52 and the beams 53 and 54 can be regarded as rigid bodies that cannot be deformed.

  The column 51 corresponds to the first connection portion 41, and the column 52 corresponds to the second connection portion 42. The beams 53 and 54 correspond to portions other than the high-rigidity end portions (thick plate portions) in the plate portion 43, and the pivot 55 corresponds to lower-end portions (thin plate portions) in the plate portion 43. The extension member 57 corresponds to the piezoelectric element 30. The pivot 58 corresponds to the first rotation support portion 45, and the pivot 59 corresponds to the second rotation support portion 46.

  As shown in the structural model ML, when the extension member 57 extends, the rectangular frame 56 is distorted into a parallelogram shape, and the movable side column 52 moves upward with respect to the fixed side column 51. That is, as shown in FIG. 22, a distortion force is given to the drive housing 40 by the expansion (displacement) of the piezoelectric element 30 incorporated in the drive housing 40, and the second connection portion is based on the first connection portion 41. The drive housing 40 is deformed so that 42 moves relatively along the Z-axis direction. By deforming the drive housing 40 in this way, the attachment member 20 can be moved in the Z-axis direction, and the condenser lens unit 430 can be moved in the Z-axis direction.

  Returning to FIGS. 16 to 20, in one drive housing 40 </ b> A of the pair of drive housings 40, the first connection portion 41 </ b> A is connected to one end of the fixing member 10 in the X-axis direction. In the other drive housing 40B of the pair of drive housings 40, the first connection portion 41B is connected to the other end portion of the fixing member 10 in the X-axis direction.

  In one drive housing 40A of the pair of drive housings 40, the second connection portion 42A is connected to one side of the ring portion 21 in the X-axis direction. In the other drive housing 40B of the pair of drive housings 40, the second connecting portion 42B is connected to the other side of the ring portion 21 in the X-axis direction. The second coupling portions 42A and 42B are coupled to the ring portion 21 at positions facing each other in the X-axis direction with the optical axis G of the condenser lens unit 430 interposed therebetween. Here, the second connecting portion 42 includes a protrusion 48 that protrudes upward from the upper plate portion 43, and is connected to the ring portion 21 via the protrusion 48. Thereby, the ring part 21 is located above the upper plate part 43.

  As described above, in the objective lens driving device 440, the pair of driving housings 40 </ b> A and 40 </ b> B fixed to the laser processing device 200 via the fixing member 10 is one side of the mounting member 20 in the X-axis direction with respect to the condenser lens unit 430. And the other side. Thereby, the condensing lens unit 430 can be hold | maintained with the both-ends support structure in a X-axis direction. As a result, the resonance frequency of the condensing lens unit 430 can be increased to a high frequency region, and vibrations in a low frequency region that becomes an obstacle for realizing high-speed driving of the condensing lens unit 430 can be suppressed. For example, while the resonance frequency is 370 Hz in the conventional structure, the objective lens driving device 440 can increase the resonance frequency to 550 Hz.

  Therefore, according to the objective lens driving device 440, the condenser lens unit 430 can be driven at high speed. Moreover, the quick response of the condensing lens unit 430 can be improved. These effects are particularly effective in the laser processing apparatus 200 that requires dynamic characteristics as a focus correction technique in the nanotechnology field.

  The laser processing device 200 on which the objective lens driving device 440 is mounted is a device that scans the laser light L along the scheduled cutting line 5. The displacement direction of the piezoelectric element 30 in the objective lens driving device 440 is a direction orthogonal to the X-axis direction that is the extending direction (processing direction) of the planned cutting line 5 that scans the laser light L. . If the displacement direction is perpendicular to the X-axis direction, the drive housing 40 is less likely to be deformed (is less likely to be distorted) in the X-axis direction when the piezoelectric element 30 is displaced. Thereby, it can suppress that the optical axis G of the condensing lens unit 430 shifts along an X-axis direction by deformation | transformation of the drive housing | casing 40. FIG. Since the positional accuracy of the optical axis G in the X-axis direction, which is the processing direction, is important in the objective lens driving device 440 that requires dynamic characteristics as a focus correction technique, this effect is particularly effective.

  As the drive housing 40 is deformed, the drive housing 40 may be slightly deformed in the Y-axis direction and the optical axis G may be slightly shifted in the Y-axis direction. The deviation of the axis G is smaller by one digit or more than the allowable error of the optical axis adjustment in actual use of the laser processing apparatus 200 and does not cause a problem.

  In the objective lens driving device 440, when the second connecting portion 42 moves relatively along the Z-axis direction due to the extension of the piezoelectric element 30, a force is applied to the attachment member 20 in the Z-axis direction via the second connecting portion 42. Will be added. At this time, since the second connecting portion 42 is connected to the attachment member 20 at a position sandwiching the optical axis G of the condenser lens unit 430, a moment (angle fluctuation) that causes the optical axis G to swing is caused by the force. As a result, it is possible to suppress the occurrence in the condensing lens unit 430 and suppress the response delay of the condensing lens unit 430.

  The driving housing 40 of the objective lens driving device 440 has a structure modeled by a structural model ML (see FIG. 21) having a pivot. That is, the first and second connecting portions 41 and 42 are formed in a block shape provided to be separated from each other, and a pair of plate portions 43 and 43 are provided between the first and second connecting portions 41 and 42. The piezoelectric element 30 is rotationally supported by the first and second connecting portions 41 and 42 in the housing space R defined by the above. The thickness of both end portions in the extending direction of the plate portion 43 is made thinner than the thickness of the plate portion 43 other than the both end portions. Thus, it is possible to specifically realize that the drive housing 40 is deformed so that the second connecting portion 42 is relatively moved along the Z-axis direction due to the displacement of the piezoelectric element 30.

  In the objective lens driving device 440, the fixing member 10, the mounting member 20, and the driving housing 40 are integrally formed. Thereby, the rigidity of the objective lens driving device 440 can be increased, and the resonance frequency can be further increased.

  In the objective lens driving device 440, at least a part of the piezoelectric element 30 is not covered with resin. Thereby, it is possible to suppress the dielectric breakdown of the piezoelectric element 30 due to moisture contained in the resin covering the piezoelectric element 30, increase the allowable voltage applied to the piezoelectric element 30, and increase the displacement range of the piezoelectric element 30. . As a result, the driving range (stroke) along the optical axis direction of the condenser lens unit 430 can be increased.

  The objective lens driving device 440 has a plane-symmetric structure with a YZ plane passing through the optical axis G of the condenser lens unit 430 and orthogonal to the X-axis direction as a symmetry plane. Such a plane-symmetric structure can suppress the vibration of the condenser lens unit 430.

  In the objective lens driving device 440, a pair of driving housings 40 are provided, and two piezoelectric elements 30 are used. The two piezoelectric elements 30 are controlled by the control unit 500 so as to be displaced synchronously. By using the two piezoelectric elements 30 in this way, it becomes possible to increase the driving force and the quick response of the condenser lens unit 430.

  In the objective lens driving device 440, the ring portion 21 is positioned above the upper plate portion 43. As a result, the fixing member 10, the mounting member 20, and the pair of drive housings 40 can be easily formed integrally. For example, it is possible to facilitate integral molding of the fixing member 10, the mounting member 20, and the pair of drive housings 40 by cutting.

  Next, an objective lens driving device 600 according to the second embodiment will be described. In the description of this embodiment, the description similar to that of the objective lens driving device 440 is omitted, and different points are mainly described.

  As shown in FIGS. 23 to 25, the objective lens driving device 600 has a rectangular parallelepiped outer shape. The objective lens driving device 600 includes a fixing member 610, a mounting member 620, the piezoelectric element 30, and a pair of driving housings 640A and 640B. The fixing member 610, the mounting member 620, and the pair of drive housings 640 are configured separately.

  The fixing member 610 and the mounting member 620 are coupled to the pair of drive housings 640A and 640B by screws or the like in a state of being combined with each other so as to have a rectangular parallelepiped shape. As shown in FIGS. 25 and 26, the fixing member 610 includes a ring portion 611 and a base portion 612 that continues to one side of the ring portion 611 in the Y-axis direction.

  The ring portion 611 is formed in an annular plate shape having the Z-axis direction as the axial direction. A fixed clamp 650 (see FIG. 23) having a through hole 651 along the optical axis G is attached to the inner peripheral surface of the ring portion 611. The fixing member 610 is fixed to the laser processing apparatus 200 (see FIG. 7) via a fixing clamp 650.

  The base 612 is a part that is connected to the drive housing 640 in the fixing member 610. The base 612 is provided so as to protrude below the ring portion 611. An inner wall surface 612 a in the Y-axis direction of the base portion 612 is a curved surface along the outer edge of the ring portion 611. On the other hand, the outer wall surface 612b of the base portion 612 in the Y-axis direction is a flat surface along the XZ plane. Further, the base portion 612 has a wall surface 612c that is a flat surface in contact with the drive housing 640 and extends along the YZ plane on both end surfaces in the X-axis direction.

  As shown in FIGS. 25 and 27, the attachment member 620 includes a ring portion 621 and a base portion 622 that continues to the other side of the ring portion 621 in the Y-axis direction. The ring portion 621 is formed in an annular plate shape whose axial direction is the Z-axis direction. A condenser lens unit 430 is coaxially inserted and screwed into the ring portion 621 (see FIG. 23). The inner diameter of the ring portion 621 is the same as the inner diameter of the fixing member 610.

  The base 622 is a portion that is connected to the drive housing 640 in the mounting member 620. The base portion 622 is provided so as to protrude upward from the ring portion 621. An inner wall surface 622 a of the base portion 622 in the Y-axis direction is a curved surface along the outer edge of the ring portion 621. On the other hand, the outer wall surface 622b of the base 622 in the Y-axis direction is a flat surface along the XZ plane. Further, the base portion 622 has a wall surface 622c that is a flat surface in contact with the drive housing 640 and along the YZ plane on both end surfaces in the X-axis direction.

  As shown in FIGS. 24 and 25, the attachment member 620 is overlapped so that the ring portion 621 faces the ring portion 611 of the fixing member 610 coaxially. The outer peripheral surface of the ring portion 621 of the attachment member 620 is in contact with or close to the wall surface 612 a of the base portion 612 of the fixing member 610. A wall surface 622 a of the base 622 of the attachment member 620 is in contact with or close to the outer peripheral surface of the ring portion 611 of the fixing member 610. Thereby, the fixing member 610 and the attachment member 620 are combined with each other so as to have a rectangular parallelepiped shape.

  As shown in FIGS. 24, 25, and 28, the drive housings 640A and 640B (drive housing 640) are housings that house the piezoelectric element 30 therein. The drive housing 640 is connected to the fixing member 610 and the attachment member 620. The drive housing 640 includes a first connection portion 641 connected to the base portion 612 of the fixing member 610 with a screw or the like, a second connection portion 642 connected to the base portion 622 of the mounting member 620 with a screw or the like, and the first and first connections. It has a pair of board part 643 constructed by 2 connection part 641,642, and the 1st and 2nd rotation support part 645,646 arrange | positioned in the accommodation space R. As shown in FIG.

  The first connection portion 641 constitutes the fixed side of the drive housing 640. The second connection portion 642 constitutes the movable side of the drive housing 640. The first connection portion 641 and the second connection portion 642 are block-like portions having high rigidity in the drive housing 640. The first connection portion 641 is disposed on one end side in the Y-axis direction of the drive housing 640, and the second connection portion 641 is disposed on the other end side in the Y direction of the drive housing 640. Similar to the plate portion 43, the plate portion 643 is installed on the first and second connection portions 641 and 642. The first and second rotation support portions 645 and 646 are swingably provided in the accommodation space R, similarly to the first and second rotation support portions 45 and 46.

  As shown in FIGS. 24 and 25, the pair of drive housings 640A and 640B are in contact with the combined fixing member 610 and mounting member 620 so as to be sandwiched in the X-axis direction. The first connecting portion 641 is connected to the base 612 of the fixing member 610 with a screw or the like. At the same time, the second connecting portion 642 is connected to the base 622 of the mounting member 620 with a screw or the like. Accordingly, the pair of drive housings 640A and 640B, the fixing member 610, and the attachment member 620 are combined with each other so as to have a rectangular parallelepiped shape.

  As described above, in the objective lens driving device 600, the pair of driving housings 640 </ b> A and 640 </ b> B fixed to the laser processing device 200 via the fixing member 610 is on one side in the X-axis direction with respect to the condensing lens unit 430 in the mounting member 620. And the other side. Thereby, the condensing lens unit 430 can be hold | maintained with the both-ends support structure in a X-axis direction. As a result, also in the objective lens driving device 600, the resonance frequency of the condensing lens unit 430 can be increased to a high frequency region, and vibrations in a low frequency region that becomes an obstacle for realizing high speed driving of the condensing lens unit 430 can be suppressed. . The condensing lens unit 430 can be driven at high speed.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to embodiment mentioned above.

  The laser processing apparatuses 100 and 200 of the above embodiments may be apparatuses that perform other laser processing such as ablation. The laser processing apparatuses 100 and 200 of the above-described embodiment are not limited to apparatuses used for laser processing for condensing the laser light L inside the processing target 1, and are applied to the front surfaces 1 a and 3 or the back surface 1 b of the processing target 1. The apparatus used for the laser processing which condenses the laser beam L may be sufficient. Furthermore, the laser beam irradiation apparatus to which the present invention is applied is not limited to the laser processing apparatuses 100 and 200, and various laser beam irradiation apparatuses may be used as long as they irradiate the target with the laser beam L. . In the above embodiment, the planned cutting line 5 is an irradiation planned line. However, the planned irradiation line is not limited to the planned cutting line 5, and may be a line along which the irradiated laser beam L is aligned.

  In the objective lens driving devices 440 and 600 of the above-described embodiment, a double-supported structure is provided in the X-axis direction that is the processing direction of the laser processing device 200, and the direction orthogonal to the X-axis direction is the displacement direction of the piezoelectric element 30. The structure of the objective lens driving device is not limited to the relationship with the processing direction. In the objective lens driving device, it is only necessary to have a double-sided structure in any predetermined direction. The displacement direction of the piezoelectric element only needs to be a direction in which the drive housing is deformed so that the displacement of the piezoelectric element causes the second connection portion to move relative to the first connection portion along the Z-axis direction.

  The objective lens driving devices 440 and 600 of the above embodiment have a plane-symmetric structure, but may have an asymmetric structure. The symmetric structure here includes not only a completely symmetric structure but also a substantially symmetric structure and a substantially symmetric structure. In the above embodiment, the drive housings 40 and 640 are deformed by the extension of the piezoelectric element 30, but the drive housings 40 and 640 may be deformed by the reduction of the piezoelectric element 30.

  DESCRIPTION OF SYMBOLS 1 ... Processing object (object), 5 ... Planned cutting line (irradiation scheduled line) 10,610 ... Fixed member, 20,620 ... Mounting member, 30 ... Piezoelectric element, 40,640 ... Drive housing, 40A, 640A: one drive housing, 40B, 640B ... the other drive housing, 41, 41A, 41B, 641 ... first connection portion, 42, 42A, 42B, 641 ... second connection portion, 43, 643 ... plate portion 45,645 ... first rotation support, 46,646 ... second rotation support, 100,200 ... laser processing device (laser beam irradiation device), 100 ... condensing lens (objective lens), 430 ... condensation Lens unit (objective lens), 440, 600 ... objective lens driving device, G ... optical axis, L ... laser beam, R ... accommodation space.

Claims (7)

In a laser light irradiation apparatus for irradiating an object with laser light, an objective lens driving apparatus that moves an objective lens that focuses the laser light on the object along the optical axis direction of the objective lens,
A fixing member fixed to the laser beam irradiation device;
An attachment member to which the objective lens is attached;
A piezoelectric element that is displaced by application of a voltage;
A first connecting portion connected to the fixing member; and a second connecting portion connected to the mounting member; accommodating the piezoelectric element; and displacement of the piezoelectric element to the second connecting portion. A pair of drive housings that are deformed so that the connecting portion relatively moves along the optical axis direction, and
The second connection part of one of the drive housings of the pair of drive housings is connected to one side of the attachment member in a predetermined direction with respect to the objective lens,
The objective lens driving device, wherein the second connecting portion of the other driving casing of the pair of driving casings is connected to the other side of the mounting member in a predetermined direction with respect to the objective lens. The laser beam irradiation device is a device that scans the laser beam along an irradiation schedule line,
2. The objective lens driving device according to claim 1, wherein a displacement direction in which the piezoelectric element is displaced is a direction orthogonal to an extending direction of the irradiation scheduled line for scanning the laser light.   3. The objective lens driving device according to claim 1, wherein the second connection portions of the pair of drive housings are respectively connected to positions where the optical axis of the objective lens is sandwiched in the attachment member. The first and second connecting portions are portions that are formed in a block shape that are spaced apart from each other in the drive housing,
The drive housing is
A pair of plate portions extending from the first connection portion toward the second connection portion and defining a storage space for storing the piezoelectric element;
A first rotation support portion disposed in the housing space and connected to the first connection portion and configured to rotate and support one end portion in the displacement direction of the piezoelectric element;
A second rotation support portion disposed in the accommodating space and connected to the second connection portion and configured to rotate and support the other end portion in the displacement direction of the piezoelectric element,
4. The objective lens driving device according to claim 1, wherein thicknesses of both end portions in the extending direction of the plate portion are thinner than thicknesses of the plate portion other than the both end portions. 5.   The objective lens driving device according to claim 1, wherein the fixing member, the mounting member, and the drive housing are integrally configured.   The objective lens driving device according to claim 1, wherein at least a part of the piezoelectric element is not covered with a resin.   The objective lens driving device according to claim 1, wherein the objective lens driving device has a plane-symmetric structure in which a plane that passes through the optical axis of the objective lens and is orthogonal to the predetermined direction is a plane of symmetry.

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