JP6689649B2 - Laser light irradiation apparatus and profile acquisition method - Google Patents

Description

  The present invention relates to a laser light irradiation device and a profile acquisition method.

  Patent Document 1 describes a laser processing apparatus that performs laser processing on a processing target object by irradiating the processing target object with laser light. In such laser light processing, the laser light output from the laser light source is modulated by the spatial light modulator and then focused on the object to be processed by the objective lens.

JP, 2011-51011, A

  In the laser beam irradiation device such as the laser processing device described above, there is a demand for measuring the profile of the laser beam. However, depending on the wavelength of the laser light, there are problems that the camera for profile measurement is expensive and is subject to export control. Even if this problem does not occur, a special measuring instrument for profile measurement may be required in addition to the above configuration.

  Therefore, it is an object of the present invention to provide a laser light irradiation device capable of acquiring a laser light profile using a spatial light modulator, and a profile measurement method.

  The laser light irradiation device according to the present invention includes a laser output unit that outputs laser light and a modulation layer that displays a phase pattern, and reflects the laser light output from the laser output unit while modulating the laser light according to the phase pattern. A spatial light modulator that emits the laser light, a condenser lens that condenses the laser light emitted from the spatial light modulator, and a slit member that is arranged at the focal position on the rear side of the condenser lens in the optical path of the laser light, An acquisition unit that acquires the intensity of the laser light measured in the latter stage of the slit member in the optical path of the laser light, a holding unit that holds the phase pattern, and a display control unit that performs a display process for displaying the phase pattern on the modulation layer, And the holding unit holds a plurality of diffraction grating patterns having pattern edges at different positions of the modulation layer as a phase pattern, and the display control unit displays the display process. Then, the diffraction grating patterns are sequentially displayed on the modulation layer so that the edges are shifted, and the slit member blocks and acquires the ± 1st-order or more diffracted light of the laser light diffracted according to the diffraction grating pattern. The section acquires intensity data of each laser beam modulated by each of the diffraction grating patterns.

  The profile acquisition method according to the present invention includes a spatial light modulator that includes a modulation layer that displays a phase pattern, and that reflects and emits laser light while modulating the laser light according to the phase pattern, and a laser emitted from the spatial light modulator. Obtaining a profile for obtaining a profile of laser light in a laser light irradiation device that includes a condenser lens that condenses light and a slit member that is arranged at a focal point on the rear side of the condenser lens in the optical path of the laser light. In the method, a display step of sequentially displaying a plurality of diffraction grating patterns as a phase pattern on the modulation layer, and intensity data of each laser beam modulated by each of the diffraction grating patterns displayed on the modulation layer in the display step. Profile to acquire the profile of the laser light based on the intensity acquisition step and intensity data The slit member blocks the diffracted light of ± 1st order or more of the laser light diffracted according to the diffraction grating pattern, and each of the diffraction grating patterns has an edge at a different position of the modulation layer. In the display step, the diffraction grating pattern is sequentially displayed on the modulation layer so that the edges are shifted, and in the intensity acquisition step, the intensity of the laser beam measured in the latter stage of the slit member in the optical path of the laser beam. To get.

  In the laser light irradiation device and the profile acquisition method, the laser light is modulated by the condensing lens after being modulated according to the phase pattern displayed on the modulation layer of the spatial light modulator. As the phase pattern, a plurality of diffraction grating patterns having pattern edges at different positions of the modulation layer are used. Having the pattern edges at different positions in the modulation layer means that the size of the region functioning as the diffraction grating is different in each of the diffraction grating patterns. Here, when a certain diffraction grating pattern is displayed on the modulation layer, diffracted light that is diffracted by the diffraction grating and emitted, and non-diffracted light that is reflected without being diffracted are generated with respect to the laser light. It will be. The non-diffracted light of the laser light is condensed by the condenser lens and passes through the slit member at the rear stage of the condenser lens. On the other hand, ± 1 or more diffracted light of the laser light is blocked by the slit member.

  That is, when the diffraction grating pattern on the modulation layer is displayed, intensity data of only the non-diffracted light and the 0th-order light of the laser light are acquired. Then, the value of the intensity data changes according to the position of the edge of the diffraction grating pattern, that is, according to the size of the region functioning as the diffraction grating. More specifically, the smaller the area that functions as a diffraction grating, the smaller the proportion of diffracted light that is blocked by the slit member, and the larger the value of intensity data.

  Therefore, if the diffraction grating patterns are sequentially displayed on the modulation layer so that the edges of the diffraction grating patterns are shifted, and the intensity data of each laser beam modulated by each of the diffraction grating patterns is acquired. , The intensity distribution of the laser beam associated with the position of the edge of the diffraction grating pattern can be obtained. Therefore, according to the laser light irradiation device and the profile acquisition method, it is possible to acquire the profile of the laser light using the spatial light modulator based on the intensity distribution.

  In the laser light irradiation apparatus according to the present invention, the modulation layer is arranged along the first direction and the second direction intersecting the first direction, and includes a plurality of pixel regions that display a phase pattern, and the holding unit includes: The display control unit holds a diffraction grating pattern having an edge extending in the first direction and a diffraction grating pattern having an edge extending in the second direction, and the display control unit performs the display processing in which the edge extending in the first direction is in the second direction. A first display process of sequentially displaying the diffraction grating pattern on the modulation layer so as to shift, and a first display process of sequentially displaying the diffraction grating pattern on the modulation layer so that an edge extending in the second direction shifts in the first direction. 2 Display processing may be performed. In this case, the intensity distribution of the laser light associated with the position of the edge is obtained along the two directions. Therefore, it is possible to obtain a more accurate laser light profile.

  The laser light irradiation device according to the present invention may include a calculation unit that performs a calculation for removing the intensity component corresponding to the 0th-order diffracted light of the laser light from the intensity data acquired by the acquisition unit. In this case, a more accurate laser light profile can be acquired.

  In the laser light irradiation apparatus according to the present invention, the diffraction grating pattern may include another edge facing the edge and a slit formed between the edge and the other edge. In this case, the intensity distribution of the laser beam associated with the position of the slit can be obtained.

  According to the present invention, it is possible to provide a laser light irradiation device and a profile measuring method capable of acquiring a laser light profile using a spatial light modulator.

It is a schematic block diagram of a laser processing apparatus used for forming a modified region. It is a top view of the processing object used as the object of formation of a modification area. FIG. 3 is a sectional view taken along the line III-III of the processing object in FIG. 2. It is a top view of the processing object after laser processing. FIG. 5 is a sectional view taken along the line VV of the object to be processed in FIG. 4. FIG. 6 is a cross-sectional view taken along line VI-VI of the processing object of FIG. 4. It is a perspective view of the laser processing apparatus which concerns on embodiment. FIG. 8 is a perspective view of an object to be processed attached to a support base of the laser processing apparatus of FIG. 7. FIG. 8 is a cross-sectional view of the laser output section taken along the ZX plane of FIG. 7. FIG. 8 is a perspective view of a part of a laser output unit and a laser condensing unit in the laser processing device of FIG. 7. FIG. 8 is a cross-sectional view of the laser condensing unit taken along the XY plane of FIG. 7. It is sectional drawing of the laser condensing part along the XII-XII line of FIG. FIG. 13 is a cross-sectional view of the laser condensing unit taken along line XIII-XIII in FIG. 12. It is a figure which shows the optical arrangement relationship of the reflection type spatial light modulator in a laser condensing part of FIG. 11, a 4f lens unit, and a condensing lens unit. FIG. 8 is a partial cross-sectional view of a reflective spatial light modulator in the laser processing device of FIG. 7. It is a schematic structure figure showing an important section of a laser processing device concerning one embodiment. It is a figure which shows an example of the some phase pattern which the holding part shown by FIG. 16 hold | maintains. It is a figure which shows an example of the some phase pattern which the holding part shown by FIG. 16 hold | maintains. It is a figure which shows the mode of diffraction in the laser processing apparatus shown in FIG. FIG. 17 is a diagram showing an example of a display process of the display control section shown in FIG. 16. It is a graph which shows the differential value of the acquired intensity data. 6 is a graph for explaining an analysis for obtaining a beam diameter. It is a graph for demonstrating the analysis for calculating | requiring a strength center. It is a graph for explaining the offset component of the intensity distribution. It is a figure for demonstrating the principle which 0th-order light generate | occur | produces. It is a figure for demonstrating the calculation method which removes the intensity component according to 0th-order light. It is a figure for demonstrating the calculation method which removes the intensity component according to 0th-order light. It is a figure for demonstrating the calculation method which removes the intensity component according to 0th-order light. 7 is a flowchart showing a profile acquisition method when the first calculation method is used. It is a flowchart which shows the profile acquisition method at the time of using a 2nd calculating method or a 3rd calculating method. It is a figure which shows the phase pattern which concerns on a modification.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In each drawing, the same elements or the elements corresponding to each other are denoted by the same reference numerals, and redundant description may be omitted.

  In the laser processing apparatus according to the embodiment, the modified region is formed on the object to be processed along the planned cutting line by focusing the laser light on the object to be processed. Therefore, first, 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 pulse-oscillates a laser light L, and a dichroic mirror 103 that is arranged so as to change the direction of an optical axis (optical path) of the laser light L by 90 °. , A condenser lens 105 for condensing the laser light L. Further, the laser processing apparatus 100 moves the support base 107 for supporting the processing target 1 which is the target to which the laser light L focused by the focusing lens 105 is irradiated, and the support base 107. 111 which is a moving mechanism of the laser, a laser light source control unit 102 which controls the laser light source 101 to adjust the output, pulse width, pulse waveform, etc. of the laser light L, and a stage control unit 115 which controls the movement of the stage 111. And are equipped with.

  In the laser processing apparatus 100, the laser light L emitted from the laser light source 101 has its optical axis direction changed by 90 ° by the dichroic mirror 103, and enters the processing target 1 placed on the support 107. It is condensed by the condenser lens 105. At the same time, the stage 111 is moved, and the workpiece 1 is moved relative to the laser light L along the planned cutting line 5. As a result, the modified region along the planned cutting line 5 is formed in the object 1 to be processed. Although the stage 111 is moved here to move the laser beam L relatively, the condenser lens 105 may be moved, or both of them may be moved.

  A plate-shaped member (for example, a substrate, a wafer, etc.) including a semiconductor substrate formed of a semiconductor material, a piezoelectric substrate formed of a piezoelectric material, or the like is used as the processing target 1. As shown in FIG. 2, the processing target object 1 is set with a planned cutting line 5 for cutting the processing target object 1. The planned cutting line 5 is an imaginary line extending linearly. When the modified region is formed inside the object to be processed 1, the laser light L is cut in a state where the converging point (condensing position) P is aligned inside the object to be processed 1 as shown in FIG. It is moved relatively along the scheduled line 5 (that is, in the direction of arrow A in FIG. 2). As a result, 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 is formed along the planned cutting line 5. 7 is the cutting start area 8. The planned cutting line 5 corresponds to the planned irradiation line.

  The converging point P is a portion 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 line in which these lines are combined, or a line whose coordinates are designated. The planned cutting line 5 is not limited to an imaginary line, and may be a line actually drawn on the surface 3 of the processing object 1. The modified region 7 may be formed continuously or intermittently. The modified regions 7 may be arranged in rows or dots, and in short, the modified regions 7 may be formed at least inside the 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 the modified region 7 may be exposed on the outer surface (front surface 3, back surface, or outer peripheral surface) of the processing target 1. The laser light incident surface when forming the modified region 7 is not limited to the front surface 3 of the processing object 1, and may be the back surface of the processing object 1.

  By the way, when the modified region 7 is formed inside the object to be processed 1, the laser beam L is transmitted through the object to be processed 1 and near the condensing point P located inside the object to be processed 1. Especially absorbed. As a result, the modified region 7 is formed in the processing target 1 (that is, internal absorption laser processing). In this case, since the laser beam L is hardly absorbed on the surface 3 of the processing object 1, the surface 3 of the processing object 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 processing object 1, the laser light L is particularly absorbed in the vicinity of the condensing point P located on the front surface 3 or the back surface, and the front surface 3 or the back surface is formed. Then, it is melted and removed to form a removed portion such as a hole or groove (surface absorption laser processing).

  The modified region 7 is a region in which the density, refractive index, mechanical strength, and other physical characteristics are different from those of the surroundings. The modified region 7 is, for example, a melt-processed region (meaning at least one of a region once melted and then re-solidified, a region in a molten state, and a region in a state of being re-solidified from molten), a crack region. , A dielectric breakdown region, a refractive index change region, and the like, and there is a region in which these are mixed. Further, as the modified region 7, there is a region in which the density of the modified region 7 is changed in comparison with the density of the non-modified region in the material of the processing object 1 and a region in which lattice defects are formed. When the material of the processing target 1 is single crystal silicon, the modified region 7 can be said to be a high dislocation density region.

  The melt-processed region, the refractive index changing region, the region in which the density of the modified region 7 is changed as compared with the density of the non-modified region, and the region in which the lattice defect is formed are further included in the region and the modified region. A crack (crack, microcrack) may be included in the interface between the region 7 and the non-modified region. The contained cracks may extend over the entire surface of the modified region 7, or may be formed only in a part or in a plurality of parts. The processing target 1 includes a substrate made of a crystalline material having a crystalline structure. For example, the processing target 1 includes a substrate formed of at least one of gallium nitride (GaN), silicon (Si), silicon carbide (SiC), LiTaO3, and sapphire (Al2O3). In other words, the processing target 1 includes, for example, a gallium nitride substrate, a silicon substrate, a SiC substrate, a LiTaO3 substrate, or a sapphire substrate. The crystal material may be either an anisotropic crystal or an isotropic crystal. Moreover, the processing target 1 may include a substrate made of an amorphous material having an amorphous structure (amorphous structure), and may include, for example, a glass substrate.

In the embodiment, the modified region 7 can be formed by forming a plurality of modified spots (working marks) along the planned cutting line 5. In this case, the modified region 7 is formed by gathering a plurality of modified spots. The modified spot is a modified portion formed by one pulse shot of pulsed laser light (that is, laser irradiation of one pulse: laser shot). Examples of the modified spot include a crack spot, a melt-processed spot, a refractive index change spot, or a mixture of at least one of these spots. Regarding the modified spot, considering the required cutting accuracy, the required flatness of the cut surface, the thickness, type, crystal orientation, etc. of the workpiece 1, the size and the length of the crack to be generated are appropriately selected. Can be controlled. Further, in the embodiment, the modified spot can be formed as the modified region 7 along the planned cutting line 5.
[Laser processing apparatus according to the embodiment]

Next, the laser processing apparatus according to the embodiment will be described. In the following description, the directions orthogonal to each other in the horizontal plane are the X-axis direction and the Y-axis direction, and the vertical direction is the Z-axis direction.
[Overall configuration of laser processing equipment]

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

  The first moving mechanism 220 is attached to the device frame 210. The first moving mechanism 220 has 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 is rotatable about an axis parallel to the Z-axis direction.

  The support base 230 is attached to the movable base 223. The support table 230 supports the processing target 1. The workpiece 1 has, for example, a plurality of functional elements (light receiving elements such as photodiodes, light emitting elements such as laser diodes, or circuit elements formed as a circuit) on the front surface side of a substrate made of a semiconductor material such as silicon. It is formed in a matrix. When the object 1 to be processed is supported by the support table 230, as shown in FIG. 8, for example, the surface 1 a (a plurality of functional elements) of the object 1 to be processed is formed on the film 12 stretched on the annular frame 11. Side surface) is attached. The support table 230 holds the frame 11 by a clamp and adsorbs the film 12 by a vacuum chuck table to support the processing target 1. On the support table 230, a plurality of lines to be cut 5a parallel to each other and a plurality of lines 5b to be cut parallel to each other are set in the object 1 in a lattice shape so as to pass between the adjacent functional elements. It

  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 by the operation of the movable base 223 in the first moving mechanism 220. Furthermore, the support base 230 is rotated about an axis parallel to the Z-axis direction as a center line by the movable base 223 operating in the first moving mechanism 220. In this way, the support base 230 is attached to the device frame 210 so as to be movable along the X-axis direction and the Y-axis direction and rotatable about an axis parallel to the Z-axis direction as a center line.

  The laser output unit 300 is attached to the device frame 210. The laser condensing unit 400 is attached to the device frame 210 via the second moving mechanism 240. The laser focusing section 400 is moved along the Z-axis direction by the operation of the second moving mechanism 240. In this way, the laser condensing unit 400 is attached to the device frame 210 so as to be movable with respect to the laser output unit 300 along the Z-axis direction.

  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 device 200.

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

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

  When the formation of the modified region along each of the planned cutting lines 5a is completed, the support 230 is rotated by the first moving mechanism 220, and each of the planned cutting lines 5b of the workpiece 1 is in a direction parallel to the X-axis direction. Is adapted to. Then, the laser focusing unit is moved by the second moving mechanism 240 so that the focusing point of the laser light L is located inside the processing target 1 at a position separated from the laser light incident surface of the processing target 1 by a predetermined distance. 400 is moved. Subsequently, while the distance between the laser light incident surface of the object to be processed 1 and the focal point of the laser light L is kept constant, the focal point of the laser light L relatively moves along each planned cutting line 5b. To be made. As a result, a modified region is formed inside 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). The relative movement of the focal point of the laser light L along each planned cutting line 5a and the relative movement of the focal point of the laser light L along each planned cutting line 5b are performed by the first moving mechanism. This is performed by moving the support base 230 along the X-axis direction by the 220. Further, the relative movement of the focal point of the laser light L between the planned cutting lines 5 a and the relative movement of the focal point of the laser light L between the planned cutting lines 5 b are performed by the first moving mechanism 220. This is performed by moving the support table 230 along the Y-axis direction.

  As shown in FIG. 9, the laser output unit 300 has 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 (laser light source) 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. ing.

  The mounting base 301 supports 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. 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-shaped member and is attachable to and detachable from the device frame 210 (see FIG. 7). The laser output unit 300 is attached to the device frame 210 via the attachment base 301. That is, the laser output unit 300 is attachable to and detachable from the device 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 is removable from the mounting base 301.

  The laser oscillator 310 pulse-oscillates the linearly polarized laser light L along the X-axis direction. The wavelength of the laser light L emitted from the laser oscillator 310 is included in any wavelength band of 500 to 550 nm, 1000 to 1150 nm, or 1300 to 1400 nm. The laser light L in the wavelength band of 500 to 550 nm is suitable for internal absorption laser processing on 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 on a substrate made of, for example, silicon. 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 light 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, the output of the laser light L is switched ON / OFF as follows. When the laser oscillator 310 is composed of a solid-state laser, by switching ON / OFF of a Q switch (AOM (acousto-optic modulator), EOM (electro-optic modulator), etc.) provided in the resonator, ON / OFF of the output of the laser light L can be switched at high speed. When the laser oscillator 310 is composed of a fiber laser, the ON / OFF of the output of the laser light L is high-speed by switching the ON / OFF of the output of the semiconductor laser that constitutes the seed laser and the amplifier (excitation) laser. Can be switched to. When the laser oscillator 310 uses an external modulation element, the external modulation element (AOM, EOM, etc.) provided outside the resonator can be switched ON / OFF, so that the output of the laser light L can be turned ON / OFF at high speed. Can be switched to.

  The shutter 320 opens and closes the optical path of the laser light L by a mechanical mechanism. The ON / OFF switching of the output of the laser light L from the laser output unit 300 is performed by the ON / OFF switching of the output of the laser light L in the laser oscillator 310 as described above, but the shutter 320 is provided. By doing so, for example, the laser light 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 adjustment unit that adjusts the output (light intensity) of the laser light L. In addition, 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 the laser light L while adjusting the diameter of the laser light L. 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 has a support base 361 and a plurality of mirrors 362 and 363. The support base 361 supports the plurality of mirrors 362 and 363. The support base 361 is attached to the attachment base 301 so that its position can be adjusted along the X-axis direction and the Y-axis direction. The mirror (first 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 of the mirror 362 can be adjusted about the axis parallel to the Z axis.

  The mirror (second 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 such that the reflection surface of the mirror 363 can be angle-adjusted around an axis parallel to the X-axis and the position can be adjusted along the Y-axis direction. The laser light L reflected by the mirror 363 passes through the opening 361a formed in the support base 361 and is incident on the laser condensing unit 400 (see FIG. 7) along the Z-axis direction. That is, the emitting 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 with respect to the mounting base 301, the position adjustment of the mirror 363 with respect to the support base 361, and the angle adjustment of the reflecting surfaces of the mirrors 362 and 363 are performed, so that the laser output section 300 The position and angle of the optical axis of the emitted laser light L are aligned 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 housing 401 has a rectangular parallelepiped shape whose longitudinal direction is the Y-axis direction. The second moving mechanism 240 is attached to one side surface 401e of the housing 401 (see FIGS. 11 and 13). The housing 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 section 401a causes the laser light L emitted from the laser output section 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 has a mirror 402 and a dichroic mirror 403. Further, the laser condensing unit 400 has a reflective spatial light modulator 410, a 4f lens unit 420, a condensing lens unit (objective lens) 430, a driving mechanism 440, and a pair of distance measuring sensors 450. is doing.

  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 that has entered the housing 401 via the light incident section 401a in a direction parallel to the XY plane. The laser light L collimated by the beam expander 350 of the laser output unit 300 is incident on the mirror 402 along the Z-axis direction. That is, the laser light L is incident on the mirror 402 as parallel light along the Z-axis direction. Therefore, even if the second moving mechanism 240 moves the laser condensing unit 400 along the Z-axis direction, the state of the laser light L incident on the mirror 402 along the Z-axis direction is maintained constant. The laser light L reflected by the mirror 402 enters the reflective spatial light modulator 410.

  The reflective spatial light modulator 410 is attached to the end portion 401c of the housing 401 in the Y-axis direction with the reflective surface 410a facing the housing 401. The reflection-type spatial light modulator 410 is, for example, a reflection-type liquid crystal (LCOS: Liquid Crystal on Silicon) spatial light modulator (SLM: Spatial Light Modulator). Reflect in the direction. The laser light L modulated and reflected by the reflective spatial light modulator 410 enters the 4f lens unit 420 along the Y-axis direction. Here, 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 form. The angle α is an acute angle (for example, 10 to 60 °). That is, the laser light L is reflected by the reflective spatial light modulator 410 along the XY plane at an acute angle. This is because the incident angle and the reflection angle of the laser light L are suppressed to suppress the decrease of the diffraction efficiency, and the performance of the reflective spatial light modulator 410 is sufficiently exhibited. In the reflective spatial light modulator 410, for example, since the thickness of the light modulation layer using liquid crystal is as thin as several μm to several tens of μm, the reflection surface 410a is the light input / output surface of the light modulation layer. Can be regarded as substantially the same as.

  The 4f lens unit 420 has 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 form a two-sided telecentric optical system in which the reflecting surface 410a of the reflective spatial light modulator 410 and the entrance pupil surface (pupil surface) 430a of the condenser lens unit 430 are in an image forming relationship. .

  As a result, the image of the laser light L on the reflection surface 410 a of the reflection-type spatial light modulator 410 (the image of the laser light L modulated by the reflection-type spatial light modulator 410) becomes the entrance pupil surface of the condenser lens unit 430. An image is formed (imaged) on 430a. The slit member 424 is formed with a slit 424a. The slit 424a is located between the lens 422 and the lens 423 and near 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 is incident on 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 part of the laser light L (for example, 0.5 to 5%) in the Y-axis direction. Permeate along. Most of the laser light L is reflected at a right angle along the ZX plane by the dichroic mirror 403. The laser light L reflected by the dichroic mirror 403 enters the condenser lens unit 430 along the Z-axis direction.

  The condenser lens unit 430 is attached to an end portion 401d (an end portion on the opposite side of the end portion 401c) of the housing 401 in the Y-axis direction via a drive mechanism 440. The condenser lens unit 430 has a holder 431 and a plurality of lenses 432. The holder 431 holds a plurality of lenses 432. The plurality of lenses 432 focus the laser light L on the processing object 1 (see FIG. 7) supported by the support table 230. The driving mechanism 440 moves the condenser lens unit 430 along the Z-axis direction by the driving force of the piezoelectric element.

  The pair of distance measuring sensors 450 are attached to the end portion 401d of the housing 401 so as to be located on both sides of the condenser lens unit 430 in the X-axis direction. Each distance measuring sensor 450 emits light for distance measurement (for example, laser light) to the laser light incident surface of the processing object 1 (see FIG. 7) supported by the support table 230, and the laser light incident By detecting the light for distance measurement reflected by the surface, displacement data of the laser light incident surface of the processing object 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 device 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 focusing point of the laser light L is relatively moved along each of the planned cutting lines 5a and 5b, the focusing lens unit 430 of the pair of distance measuring sensors 450 relatively precedes. The distance measuring sensor 450 acquires displacement data of the laser light incident surface of the processing target 1 along each of the planned cutting lines 5a and 5b. Then, the driving mechanism 440 collects data based on the displacement data acquired by the distance measuring sensor 450 so that the distance between the laser light incident surface of the processing object 1 and the condensing point of the laser light L is maintained constant. The optical 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 (intensity distribution acquisition unit) 464. The beam splitter 461 splits 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 form a double-sided telecentric optical system in which the entrance pupil plane 430a of the condenser lens unit 430 and the imaging surface of the profile acquisition camera 464 are in an image-forming relationship. As a result, the image of the laser light L on the entrance pupil plane 430a of the condenser lens unit 430 is transferred (imaged) to the imaging surface of the profile acquisition camera 464. As described above, the image of the laser light L on the entrance pupil plane 430a of the condenser lens unit 430 is the image of the laser light L modulated by the reflective spatial light modulator 410. Therefore, in the laser processing apparatus 200, the operating state of the reflective spatial light modulator 410 can be grasped by monitoring the image pickup result by the profile acquisition camera 464.

  Further, the laser condensing unit 400 has a beam splitter 471, a lens 472, and a camera 473 for monitoring the optical axis position 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 light L reflected by the beam splitter 471 sequentially enters the lens 472 and the camera 473 along the Z-axis direction. The lens 472 focuses the incident laser light L on the imaging surface of the camera 473. In the laser processing apparatus 200, while monitoring the imaging results of the cameras 464 and 473, the mirror unit 360 adjusts the position of the support base 361 with respect to the mounting base 301, the position of the mirror 363 with respect to the support base 361, and each mirror. By adjusting the angles of the reflecting surfaces of 362 and 363 (see FIGS. 9 and 10), the optical axis of the laser light L entering the condenser lens unit 430 is displaced (the intensity of the laser light with respect to the condenser lens unit 430). It is possible to correct the positional deviation of the distribution and the angular deviation of the optical axis of the laser light L with respect to the condenser lens unit 430.

  The plurality of beam splitters 461 and 471 are arranged in a cylindrical body 404 extending from the end portion 401d of the housing 401 along the Y-axis direction. The pair of lenses 462 and 463 are arranged inside a cylindrical body 405 that is erected on the cylindrical body 404 along the Z-axis direction, and the profile acquisition camera 464 is arranged at the end of the cylindrical body 405. There is. The lens 472 is arranged inside a cylindrical body 406 that is erected on the cylindrical body 404 along the Z-axis direction, and the camera 473 is arranged at the end of the cylindrical body 406. The tubular body 405 and the tubular body 406 are arranged in parallel 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 purpose. .

  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 passes through the condensing lens unit 430 and the workpiece 1 supported by the support 230. (See FIG. 7).

  The visible light V applied to the object 1 to be processed is reflected by the laser light incident surface of the object 1 to be processed, enters the dichroic mirror 403 via the condenser lens unit 430, and dichroic mirror 403 along the Z-axis direction. Through. The beam splitter 486 splits the visible light V transmitted through the dichroic mirror 403 into a reflection component and a transmission component. The visible light V transmitted through the beam splitter 486 is transmitted through the half mirror 485 and is sequentially incident on 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 by the observation camera 488.

  The mirror 484, the half mirror 485, and the beam splitter 486 are arranged in a holder 407 mounted on the end portion 401d of the housing 401. The plurality of lenses 482 and the reticle 483 are arranged inside a cylindrical body 408 that is erected on the holder 407 along the Z-axis direction, and the visible light source 481 is arranged at the end of the cylindrical body 408. The lens 487 is arranged inside a cylindrical body 409 standing on the holder 407 along the Z-axis direction, and the observation camera 488 is arranged at the end of the cylindrical body 409. The cylindrical body 408 and the cylindrical 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 by the beam splitter 486 in the X-axis direction are respectively absorbed by a damper or the like provided on the wall portion of the holder 407. Alternatively, it may be used for an appropriate purpose.

  In the laser processing device 200, the laser output unit 300 is supposed to be replaced. This is because the wavelength of the laser beam L suitable for processing differs depending on the specifications of the processing target 1, the processing conditions, and the like. 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 in which the wavelength of the emitted laser light L is included in the wavelength band of 500 to 550 nm, the laser output unit 300 in which the wavelength of the emitted laser light L is included in the wavelength band of 1000 to 1150 nm, and the emission is performed. A laser output unit 300 in which the wavelength of the laser light L is included in the wavelength band of 1300 to 1400 nm is prepared.

  On the other hand, in the laser processing device 200, replacement of the laser condensing unit 400 is not expected. This is because the laser condensing unit 400 is compatible with 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 condensing lens unit 430, and the like are compatible with multiple wavelengths. .

Here, the laser condensing unit 400 corresponds to the wavelength bands of 500 to 550 nm, 1000 to 1150 nm, and 1300 to 1400 nm. This is realized by designing each component of the laser condensing unit 400 so that desired optical performance is satisfied, such as coating each component of the laser condensing unit 400 with a predetermined dielectric multilayer film. It 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 dependence. Therefore, the λ / 2 wavelength plate unit 330 and the polarizing plate unit 340 are provided in the laser output section 300 as different configurations for each wavelength band.
[Optical path and polarization direction of laser light in laser processing equipment]

  In the laser processing device 200, the polarization direction of the laser light L focused on the processing target 1 supported by the support 230 is a direction parallel to the X-axis direction, as shown in FIG. It coincides with 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 a plane parallel to the plane including the optical axis of the laser light L entering and exiting the reflective spatial light modulator 410 when liquid crystal is used for the optical 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 therein, the laser light L is subjected to phase modulation while the rotation of the plane of polarization is 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 light L is reflected as S-polarized light rather than the laser light L is reflected as P-polarized light, the number of coatings of the dielectric multilayer film for making the dichroic mirror 403 correspond to multiple wavelengths decreases. This is because the dichroic mirror 403 can be easily designed.

  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 so as to be along the XY plane, and from the dichroic mirror 403. The optical path to the condenser lens unit 430 is set so as to be 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 so as to be 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 follow the Y-axis direction. There is.

  Here, the laser light L traveling from the laser output unit 300 to the laser condensing unit 400 along the Z-axis direction is reflected by the mirror 402 in a direction parallel to the XY plane, as shown in FIG. The light enters the spatial light modulator 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 It forms an acute angle α. On the other hand, as described above, in the laser output section 300, the optical path of the laser light L is set so as to be 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 the output adjustment unit for adjusting the output of the laser light L, but also the polarization direction adjustment for adjusting the polarization direction of the laser light L. It must also function as a department.
[4f lens unit]

  As described above, the pair of lenses 422 and 423 of the 4f lens unit 420 has the two-sided telecentric optics 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 image forming relationship. It constitutes the system. Specifically, as shown in FIG. 14, 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 410 a of the reflective spatial light modulator 410 is the first distance of the lens 422. 1 focal length f1, 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 becomes the second focal length f2 of the lens 423, and the center of the lens 422 The distance of the optical path between the lens and the center of the lens 423 is the sum of the first focal length f1 and the second focal length f2 (that is, f1 + f2). Among the optical paths 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 device 200, the magnification M of the both-side telecentric optical system is 0.5 <M <1 (reduction system) 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. ) Is met. The larger the effective diameter of the laser light L on the reflection surface 410a of the reflective spatial light modulator 410, the more the laser light L is modulated with a finer phase pattern. From the viewpoint of suppressing the lengthening of 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 the two-sided telecentric optical system) = (image size on the entrance pupil plane 430a of the condensing lens unit 430) / (size of the object on the reflection surface 410a of the reflection-type spatial light modulator 410) ). In the case of the laser processing device 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 reflecting surface 410a of the reflective spatial light modulator 410, even if the magnification M of the both-side telecentric optical system satisfies 1 <M <2 (enlargement system). Good. The smaller the effective diameter of the laser light L on the reflection surface 410a of the reflection-type spatial light modulator 410, the smaller the magnification of the beam expander 350 (see FIG. 9), which is 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 viewpoint of suppressing the lengthening of the optical path of the laser light L from the reflective spatial light modulator 410 to the condenser lens unit 430, 1.05 ≦ M ≦ 1.7 is more preferable.
[Reflective spatial light modulator]

  As shown in FIG. 15, 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 film mirror, an alignment film 999a, a liquid crystal layer ( A modulation layer) 216, an alignment film 999b, a transparent conductive film 217, and a transparent substrate 218 such as a glass substrate are laminated in this order.

  The transparent substrate 218 has a surface 218a. As described above, the surface 218a can be regarded as substantially forming the reflective surface 410a of the reflective spatial light modulator 410, but more specifically, the surface 218a is an incident surface on which the laser light L is incident. . That is, the transparent substrate 218 is made of a light transmissive material such as glass, and transmits the laser light L incident from the surface 218 a of the reflective spatial light modulator 410 to the inside of 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, for example, a metal material such as aluminum, and its surface 214a is processed to be flat and smooth. The surface 214a reflects the laser light L incident from the surface 218a of the transparent substrate 218 toward the surface 218a. That is, the reflective spatial light modulator 410 includes a surface 218a on which the laser light L is incident and a surface 214a that reflects the laser light L incident from the surface 218a toward the surface 218a. The plurality of pixel electrodes 214 are driven by the active matrix circuit provided in the driving circuit layer 914.

  The active matrix circuit is provided between the plurality of pixel electrodes 214 and the silicon substrate 213, and applies an applied voltage to each pixel electrode 214 according to an optical image to be output from the reflective spatial light modulator 410. Control. 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. The control unit 500 is configured to apply a predetermined voltage to the pixel electrodes 214 of the pixels designated by both driver circuits.

  The alignment films 999a and 999b are arranged on both end surfaces of the liquid crystal layer 216, and align the liquid crystal molecule group in a fixed direction. The alignment films 999a and 999b are made of, for example, a polymer material such as polyimide, and the contact surface with the liquid crystal layer 216 is rubbed.

  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 driving circuit layer 914, an electric field is formed between the transparent conductive film 217 and each pixel electrode 214, and an electric field formed in the liquid crystal layer 216. The arrangement direction of the liquid crystal molecules 216a changes according to the size of the. Then, 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 by the reflective film 215. After being reflected, it is modulated again by the liquid crystal layer 216 and emitted.

  At this time, the voltage applied to each pixel electrode 214 is controlled by the control unit 500, and the refractive index of the portion of the liquid crystal layer 216 sandwiched between the transparent conductive film 217 and each pixel electrode 214 changes according to the voltage. (The refractive index of the liquid crystal layer 216 at the position corresponding to each pixel changes). Due to this change in the refractive index, the phase of the laser light L can be changed for each pixel of the liquid crystal layer 216 according to the applied voltage. That is, the phase modulation according to the hologram pattern can be provided by the liquid crystal layer 216 for each pixel.

  In other words, a modulation pattern as a hologram pattern that imparts 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 is incident on and transmitted through the modulation pattern is adjusted, and the phase of the component in a predetermined direction orthogonal to the traveling direction is shifted in each light beam that constitutes the laser light L. Therefore, the laser light L can be modulated (for example, the intensity, amplitude, phase, polarization, etc. of the laser light L can be modulated) by appropriately setting the modulation pattern to be displayed on the reflective spatial light modulator 410.

  In other words, in accordance with the voltage applied to each pixel electrode 214, a refractive index distribution is generated in the liquid crystal layer 216 along the arrangement direction of the pixel electrode 214, and a phase pattern capable of imparting phase modulation to the laser light L is generated. It is displayed on the liquid crystal layer 216. That is, the reflective spatial light modulator 410 includes a liquid crystal layer (modulation layer) 216 arranged between the surface 218a and the surface 214a and displaying a phase pattern to modulate the laser light L.

  Here, as described above, the pixel electrodes 214 are arranged in a matrix. That is, the pixel electrodes 214 are arranged along the first direction and the second direction intersecting (orthogonal to) the first direction. In the liquid crystal layer 216, the refractive index is changed for each region corresponding to each pixel electrode 214 between each pixel electrode 214 and the transparent conductive film 217. Therefore, the liquid crystal layer 216 includes a plurality of pixel regions 216p arranged along the first direction and the second direction corresponding to the arrangement of the pixel electrodes 214 and displaying the phase pattern. As an example, one pixel region 216p is a region sandwiched between one pixel electrode 214 and the transparent conductive film 217. Therefore, in the following, one pixel electrode 214 and one corresponding pixel region 216p may be simply referred to as “pixel”.

  Next, a main part of the laser processing apparatus 200 according to the embodiment will be described in detail.

  FIG. 16 is a schematic configuration diagram showing a main part of the laser processing apparatus 200 according to the embodiment. As shown in FIG. 16, the laser light L output from the laser output unit 300 is incident on the reflective spatial light modulator 410. The reflective spatial light modulator 410 modulates the incident laser light L according to the phase pattern displayed on the liquid crystal layer 216 and reflects and emits the laser light L. The laser light L emitted from the reflective spatial light modulator 410 is condensed by a lens (condensing lens) 422 which is a relay lens of the 4f lens unit 420, and then is condensed by a lens 423 which is a relay lens of the 4f lens unit 420. Collimated.

  Here, the dichroic mirror 403 in the rear stage of the lens 423, the condenser lens unit 430, and the like are omitted, and the power meter 520 is disposed in the rear stage of the lens 423 in the optical path of the laser light L. Therefore, the laser light L collimated by the lens 423 enters the power meter 520. The pair of lenses 422 and 423 relay the wavefront of the laser light L on the reflection surface 410a to the incident surface of the laser light L of the power meter 520. As a result, the reflecting surface 410a and the entrance surface of the power meter 520 have a conjugate relationship with each other.

  A slit member 424 is arranged at the focal position on the rear side of the lens 422 in the optical path of the laser light L. The slit member 424 blocks the spatial frequency component (wide-angle diffracted light) of the laser light L that is equal to or higher than a certain value, and allows the spatial frequency component of the laser light L that is less than the certain value to pass. For example, in the slit member 424, the size of the opening is set so as to shield the spatial frequency component of a certain value or more. For example, when the diffraction grating pattern is displayed as the phase pattern on the reflective spatial light modulator 410 (the liquid crystal layer 216), the slit member 424 causes the diffracted light of the laser light L diffracted according to the diffraction grating pattern. At least a part (eg, ± 1st order or higher diffracted light) is blocked.

  The control unit 500 includes the laser light source control unit 102, the display control unit (acquisition unit, calculation unit) 501, the SLM drive unit 502, and the holding unit 503. The laser light source control unit 102 controls at least the operation of the laser output unit 300. Further, the laser light source control unit 102 determines and sets the output of the laser light L generated by the laser oscillator 310 based on the processing conditions (irradiation conditions) for each laser processing along the one planned cutting line 5. The processing conditions are input by the operator through an input unit such as an external PC 600 or a touch panel of the control unit 500. The processing conditions are, for example, the depth position where the modified region 7 is formed in the processing object 1, the laser output, and the like.

  The display controller 501 controls the phase pattern displayed on the liquid crystal layer 216 of the reflective spatial light modulator 410. That is, the display control unit 501 performs a display process of displaying the phase pattern on the liquid crystal layer 216. As an example, the display control unit 501 selects a predetermined phase pattern from the phase patterns held by the holding unit 503, and causes the liquid crystal layer 216 to display the predetermined phase pattern via the SLM driving unit 502. The holding unit 503 holds a plurality of phase patterns. 17 and 18 are diagrams showing an example of a plurality of phase patterns held by the holding unit shown in FIG. 16.

  As shown in FIGS. 17 and 18, the holding unit 503 holds a plurality of diffraction grating patterns P1 and P2 having pattern edges E1 and E2 at different positions of the liquid crystal layer 216 as phase patterns. The diffraction grating patterns P1 and P2 include a diffraction grating region RG and a black region RB. The diffraction grating region RG is a region in which a plurality of groove-shaped patterns forming the diffraction grating are formed, and functions as a diffraction grating. Therefore, the laser light L incident on the diffraction grating region RG is reflected and emitted while being branched into a plurality of diffracted lights by diffraction.

  On the other hand, the black region RB is, for example, a region in which a voltage is not applied to the pixel region 216p of the liquid crystal layer 216 and a refractive index distribution is not substantially generated. Therefore, the laser light L incident on the black region RB is reflected by the pixel electrode 214 and emitted without being phase-modulated. The edges E1 and E2 are boundaries between the diffraction grating region RG and the black region RB. The holding unit 503 further holds a reference pattern in which the entire liquid crystal layer 216 is a groove-shaped pattern that forms a diffraction grating (that is, has no edges).

  As shown in FIG. 17, the holding unit 503 holds a plurality of diffraction grating patterns P1 having edges E1 extending in the first direction D1. In the plurality of diffraction grating patterns P1, the positions of the edges E1 in the second direction D2 are different from each other (for example, 10 pixels are shifted in the second direction D2). Further, as shown in FIG. 18, the holding portion 503 holds a plurality of diffraction grating patterns P2 having an edge E2 extending in the second direction. In the plurality of diffraction grating patterns P2, the positions of the edge E2 in the first direction D1 are different from each other (for example, 10 pixels are shifted in the first direction D1). In addition, between the diffraction grating pattern P1 and the diffraction grating pattern P2, all the groove-shaped patterns forming the diffraction grating region RG extend in the same direction (that is, the branching direction of light by diffraction is the same). Is).

  When these diffraction grating patterns P1 and P2 are displayed on the liquid crystal layer 216, a part of the laser light L that is incident on the diffraction grating region RG is branched into a plurality of diffracted lights. FIG. 19 is a schematic diagram showing how laser light is diffracted. As shown in FIG. 19, the laser light L that has entered the reflective spatial light modulator 410 that functions as a diffraction grating G (that is, a diffraction grating pattern is displayed) is branched into a plurality of diffracted lights by diffraction. Here, only the 0th-order light L0, the 1st-order light L1, and the -1st-order light L2 are shown, and the higher-order diffracted light is omitted.

  As shown in (c) of FIG. 19, the first-order light L1 and the −1st-order light L2 are diffracted with respect to the 0th-order light L0 at a diffraction angle of θ (and −θ). The diffraction angle θ is expressed as d · sin θ = n · λ by the groove spacing d of the diffraction grating G, the refractive index n, and the wavelength λ of the laser light L. As an example, as shown in FIG. 19B, the 0th-order light L0 is condensed by the lens 422, passes through the slit member 424, and reaches the power meter 520. On the other hand, the first-order light (and the −first-order light, ± second-order or higher-order light) is condensed and deflected by the lens 422, blocked by the slit member 424, and does not reach the power meter 520.

  That is, the slit member 424 blocks the diffracted light of ± 1st order or more of the laser light L diffracted according to the diffraction grating patterns P1 and P2. Therefore, when the diffraction grating patterns P1 and P2 are displayed on the liquid crystal layer 216, the 0th order light of the laser light L that has entered the diffraction grating region RG and the laser light L that has entered the black region RB (that is, non-diffracted light). ) Is incident on the power meter 520.

  Subsequently, the display process of the display control unit 501 will be described. As the display processing, the display control unit 501 sequentially displays the diffraction grating patterns P1 and P2 on the liquid crystal layer 216 so that the edges E1 and E2 of the diffraction grating patterns P1 and P2 are shifted. More specifically, as the display process, the display control unit 501 firstly, as shown in FIG. 20, the diffraction grating pattern so that the edge E1 extending in the first direction D1 is shifted in the second direction D2. A first display process of sequentially displaying P1 on the liquid crystal layer 216 is performed. As a result, of the laser light L incident on the liquid crystal layer 216, a part of the laser light L incident on the diffraction grating region RG and diffracted, and a remaining portion of the laser light L incident on the black region RB and not diffracted along the second direction D2. The ratio changes as the edge E1 shifts.

  After that, the display control unit 501 performs, as a display process, a second display process in which the diffraction grating patterns are sequentially displayed on the liquid crystal layer 216 so that the edge E2 extending in the second direction D2 is shifted in the first direction D1. Thus, of the laser light L incident on the liquid crystal layer 216, a part of the laser light L incident on the diffraction grating region RG and diffracted and a remaining portion of the laser light L incident on the black region RB and not diffracted are along the first direction D1. The ratio changes as the edge E2 shifts.

  While performing such display processing, the display control unit 501 outputs the intensity of the laser light L measured by the power meter 520 downstream of the slit member 424 in the optical path of the laser light L via the laser light source control unit 102. Acquire (that is, the acquisition unit). More specifically, for example, the display control unit 501 controls the laser light L modulated by each of the diffraction grating patterns P1 and P2 during the display process (the first display process and the second display process). Acquire intensity data for each. The display processing and the acquisition of the intensity data correspond to acquiring the intensity distribution of the laser light L by the knife edge method.

  FIG. 21 is a graph showing the differential value of the acquired intensity data. While the display control unit 501 is performing the display process, as described above, the diffracted light that is incident on the diffraction grating region RG and diffracted and the non-diffracted light that is incident on the black region RB and is not diffracted. The ratio changes with the shift of the edges E1 and E2. Therefore, the value of the intensity data (for example, the plot in FIG. 21) changes according to the positions of the edges E1 and E2, that is, according to the size of the diffraction grating region RG.

  Therefore, during the display process, as the edges E1 and E2 shift and the diffraction grating region RG becomes smaller, the ratio of the diffracted light blocked by the slit member 424 becomes smaller, so that the value of the intensity data is reduced. Grows larger. Actually, in the knife edge method, when the edges E1 and E2 pass the intensity center of the laser beam L, the rate of increase in intensity due to the reduction of the diffraction grating region RG gradually decreases, and the diffraction grating region RG is reduced. 22 is asymptotic to the intensity value when the magnitude becomes 0 (entirely becomes the black region RB) (see (a) in FIG. 22). Therefore, by differentiating the intensity distribution thus obtained, a normally distributed intensity distribution as shown in FIG. 21 is obtained.

These intensity distributions are associated with the positions (pixel numbers) of the edges E1 and E2. Therefore, the profile of the laser light L can be acquired based on the analysis of these intensity distributions. This analysis will be described. Here, for example, the display control unit 501 performs analysis. Specifically, first, the display control unit 501 analyzes for obtaining the beam diameter of the laser light L. That is, the normal distribution function f (x) of the following equation (1) is fitted to the plot group showing the measurement result after differentiation in FIG. Accordingly, the beam diameter of the laser light L on the reflecting surface 410a can be obtained as 4 · σ. Alternatively, as shown in FIG. 22B, the beam diameter of the laser light L on the reflecting surface 410a can be obtained as a width S3 of 1 / e ^{2 which} is 13.5% from the peak.

  On the other hand, as shown in (a) of FIG. 22, the beam diameter can be obtained as follows from the intensity distribution (intensity distribution before differentiation) acquired by the knife edge method. That is, the beam diameter of the laser beam L on the reflecting surface 410a can be obtained by measuring the distance S1 between the pixel having the intensity of 10% and the pixel having the intensity of 90%, and calculating the distance of 1.561 × the distance S1. Alternatively, the beam diameter of the laser light L on the reflecting surface 410a can be obtained by 2 × distance S2 by measuring the distance S2 between the pixel having the intensity of 16% and the pixel having the intensity of 84%. When the laser light L is an ideal Gaussian beam, the beam diameter using the above normal distribution function f (x) and the beam diameter obtained from the intensity distribution obtained by the knife edge method match each other. To do.

  Subsequently, the display control unit 501 performs an analysis for obtaining the intensity center of the laser light L by analyzing the intensity distribution. That is, as shown in (a) of FIG. 23, the intensity center of the laser light L on the reflecting surface 410a is the position of the pixel where the intensity reaches 50% in the intensity distribution acquired by the knife edge method. This is also the center of gravity of the laser light L. On the other hand, as shown in FIG. 23B, the intensity center of the laser light L on the reflecting surface 410a is obtained from the normal distribution function f (x) as the position of the pixel having the maximum intensity. These intensity centers coincide with each other when the laser light L is an ideal Gaussian beam.

  Here, as shown in FIG. 24, the intensity distribution acquired by the above method actually includes the offset component Lf. That is, the intensity of the portion of the laser light L incident on the diffraction grating region RG is ideally 0, but due to the principle of the reflective spatial light modulator 410, some leakage light is generated. Most of the offset component Lf is derived from the intensity component of the 0th-order light L0. Therefore, the display control unit 501 performs an operation (that is, an operation unit) for removing the intensity component corresponding to the 0th-order light L0 from the intensity distribution actually obtained.

  In the first place, the 0th-order light L0 is generated for the following reason. That is, first, the theoretical maximum efficiency of the diffraction grating is when the modulation amount is π (= λ / 2: 128 gradations). Then, as shown in FIGS. 25A and 25C, it is ideal to display a rectangular phase pattern having a height (modulation amount) of π on the liquid crystal layer 216. However, as shown in (b) and (d) of FIG. 25, the phase pattern actually displayed on the liquid crystal layer 216 is affected by the refractive index distribution between adjacent pixels, and therefore the modulation amount Rise and fall slow down.

  In particular, as shown in (d) of FIG. 25, when the groove spacing d is relatively small, this effect cannot be ignored, and the diffraction efficiency is reduced to generate 0th-order light (intensity of 0th-order light increases. ). On the other hand, as shown in (e) of FIG. 25, it is possible to suppress the decrease in diffraction efficiency by adjusting the coefficient a of the modulation amount π. Therefore, by adjusting the coefficient a of the modulation amount π in this way to maximize the diffraction efficiency, it is possible to remove the intensity component corresponding to the 0th-order light L0 (first calculation method). It should be noted that the above 128 gradations are gradation values of luminance in the image signal for displaying the phase pattern on the liquid crystal layer 216.

  The description of another calculation method for removing the intensity component according to the 0th-order light L0 will be continued. As shown in (a) of FIG. 26, when the diffraction grating pattern P1 in the liquid crystal layer 216 is displayed and the entire laser light L is incident on the diffraction grating region RG (first case), it is measured. Most of the intensity of the laser light L that is emitted is leakage light (zero-order light). The strength at this time is set to I0 (see (a) of FIG. 27). In the first case, the intensity component corresponding to the 0th-order light L0 can be removed by subtracting the intensity I0.

  On the other hand, as shown in FIG. 26B, when a certain diffraction grating pattern P1 is displayed on the liquid crystal layer 216 and some portion of the laser light L is incident on the diffraction grating region RG (second). In this case), in order to remove the intensity component according to the 0th-order light L0, it is necessary to subtract the intensity according to the ratio R incident on the diffraction grating region RG. Further, as shown in (c) of FIG. 26, when a certain diffraction grating pattern P1 is displayed on the liquid crystal layer 216, but the entire laser light L is not incident on the diffraction grating region RG (first 3). The intensity in the third case is Im (see FIG. 27A). In the third case, since the measured intensity is not affected by the diffraction grating, it is not necessary to subtract the intensity.

The subtraction amount in each pixel is calculated in accordance with the above situation. First, as described above, the intensity in the first case where the entire laser light L is incident on the diffraction grating region RG is set to I0. Subsequently, the intensity in the third case in which the entire laser light L does not enter the diffraction grating region RG is Im. Then, in the second case where a part of the laser light L is incident on the diffraction grating region RG, the intensity before correction (before subtraction) at a certain pixel number (x [pixel]) where the edge E1 is located is y (x). And The corrected intensity (after subtraction) at the same position is Y (x). Then, in the second case, the ratio R is used to obtain Y (x) as shown in the following equation (2).

Regarding the ratio R, it is necessary to obtain the ratio from the final data with R = Y (x) / Im. By calculating the formula of this ratio R and the above formula (2), the formula finally obtained is the following formula (3). As described above, in the second case, the corrected intensity Y (x) is obtained by the following formula (3), and the intensity I0 is subtracted in the first case, and the subtraction is unnecessary in the third case. By doing so, as shown in (b) of FIG. 27, it is possible to acquire the intensity distribution in which the intensity component is removed according to the 0th-order light L0 (second calculation method).

  On the other hand, it is also possible to remove the intensity component according to the 0th-order light L0 by another calculation method. That is, first, the intensity distribution including the intensity component (offset component Lf) obtained by the knife edge method as shown in (a) of FIG. 28 and corresponding to the 0th-order light L0 is shown in (b) of FIG. Differentiate as shown to obtain a normal distribution intensity distribution. At this stage, since the gradient component is extracted by differentiation, the offset component Lf whose gradient is substantially 0 is removed.

  Then, by integrating again the intensity distribution obtained by the differentiation, as shown in (c) of FIG. 28, the intensity distribution in a state in which the offset component Lf (the intensity component corresponding to the 0th-order light L0) is removed. Is obtained (third calculation method). The plot in (c) of FIG. 28 shows the measured original intensity data, and the curve shows the intensity distribution obtained by integration. As described above, the intensity components corresponding to the 0th-order light L0 can be removed by a plurality of calculation methods. The timing of removing the intensity component according to the 0th-order light L0 differs depending on which of these calculation methods is used. Therefore, as will be described later, the flow of the profile acquisition method is different.

  Subsequently, a profile acquisition method according to one embodiment will be described. FIG. 29 is a flowchart showing a profile acquisition method when the first calculation method is used. As shown in FIG. 29, in this method, first, the measurement of the intensity of the laser light L is prepared (step S1). In this step S1, for example, the power meter 520 is arranged at the subsequent stage of the slit member 424 (and the lens 423), cables at various places are connected, and the program of the control unit 500 is started.

  Then, the phase modulation amount that maximizes the diffraction efficiency is confirmed (step S2). More specifically, in this step S2, the calculation for removing the intensity component according to the 0th order light is performed by the first calculation method. That is, in this step S2, first, the liquid crystal layer 216 is caused to display a reference pattern which is a groove-shaped pattern in which the entire liquid crystal layer 216 constitutes a diffraction grating.

  After that, while adjusting the coefficient a, the power meter 520 measures the intensity of the laser light L to identify the coefficient a that minimizes the intensity. Thereby, the phase modulation amount that maximizes the diffraction efficiency is confirmed (specified) as π × a. Further, the gradation value of the luminance of the image signal that gives the phase modulation amount is specified. As a result, the subsequent steps can be performed while substantially eliminating the influence of the intensity component corresponding to the 0th-order light.

  Subsequently, the diffraction grating pattern is displayed on the liquid crystal layer 216 (step S3, display step). Here, first, a reference pattern is displayed as a diffraction grating pattern (that is, the entire surface is a diffraction grating). Then, the intensity of the laser beam L modulated according to the diffraction grating pattern displayed in step S3 is acquired (step S4, intensity acquisition step). Then, it is determined whether or not the edge of the diffraction grating pattern has reached the pixel at the end of the liquid crystal layer 216 (step S5).

  As a result of the determination in step S5, steps S3 to S5 are repeated until it is determined that the edge reaches the pixel at the end of the liquid crystal layer 216. At that time, in step S3, the diffraction grating patterns are sequentially displayed on the liquid crystal layer 216 so that the edges of the diffraction grating patterns are shifted. Then, in step S4, each intensity data of the laser light L modulated by each of the diffraction grating patterns displayed on the liquid crystal layer 216 is acquired. As a result, the intensity data associated with the edge position is sequentially acquired.

  Then, as a result of the determination in step S5, when it is determined that the edge has reached the pixel at the end of the liquid crystal layer 216, the above-described analysis is performed on the basis of the obtained intensity data to thereby obtain the reflection surface 410a. A profile such as the beam diameter and the intensity center of the laser light L at is acquired (step S6, profile acquisition step). Then, the process ends. When step S3 is repeated, for example, first, the diffraction grating pattern P1 in which the edge E1 extending in the first direction D1 shifts along the second direction D2 is sequentially displayed on the liquid crystal layer 216, and then, The diffraction grating pattern P2 can be sequentially displayed on the liquid crystal layer 216 so that the edge E2 extending in the second direction D2 shifts along the first direction D1.

  FIG. 30 is a flowchart showing a profile acquisition method when the second calculation method or the third calculation method is used. As shown in FIG. 30, in this method, first, the above step S1 is performed. Then, steps S3 to S5 are repeated as described above. Then, as a result of the determination in step S5, when it is determined that the edge has reached the pixel at the end of the liquid crystal layer 216, an operation of removing the intensity component corresponding to the 0th-order light from the obtained intensity data is performed. At this time, the above-mentioned second calculation method or third calculation method is used. Then, the profile such as the beam diameter and the intensity center of the laser light L on the reflecting surface 410a is acquired by performing the above-described analysis based on the obtained intensity data (step S6). Then, the process ends.

  As described above, in the laser processing apparatus 200 and the profile acquisition method thereof, the laser light L is modulated according to the phase pattern displayed on the liquid crystal layer 216 of the reflective spatial light modulator 410, and then the lens 422. Is collected by. As the phase pattern, a plurality of diffraction grating patterns P1 and P2 having pattern edges E1 and E2 at different positions in the liquid crystal layer 216 are used. Having the pattern edges E1 and E2 at different positions of the liquid crystal layer 216 means that the size of the diffraction grating region RG is different in each of the diffraction grating patterns P1 and P2.

  Here, in the state where certain diffraction grating patterns P1 and P2 are displayed on the liquid crystal layer 216, the laser light L is diffracted by the diffraction grating and emitted, and non-diffracted that is reflected without being diffracted. And light will be generated. The non-diffracted light of the laser light L is condensed by the lens 422 and passes through the slit member 424 in the subsequent stage of the lens 422. On the other hand, ± 1 or more diffracted light of the laser light L is blocked by the slit member 424.

  That is, when the diffraction grating patterns P1 and P2 in the liquid crystal layer 216 are displayed, intensity data of only the non-diffracted light and the 0th-order light of the laser light L are acquired. Then, the value of the intensity data changes according to the positions of the edges E1 and E2 of the diffraction grating patterns P1 and P2, that is, according to the size of the diffraction grating region RG. More specifically, the smaller the diffraction grating region RG, the smaller the proportion of the diffracted light blocked by the slit member 424, and the larger the value of the intensity data.

  Therefore, the diffraction grating patterns P1 and P2 are sequentially displayed on the liquid crystal layer 216 so that the edges E1 and E2 of the diffraction grating patterns P1 and P2 are shifted, and are modulated by the diffraction grating patterns P1 and P2, respectively. If each intensity data of the laser light L is acquired, the intensity distribution of the laser light L associated with the positions of the edges E1 and E2 of the diffraction grating patterns P1 and P2 can be obtained. Therefore, it is possible to acquire the profile of the laser light L using the reflective spatial light modulator 410 based on the intensity distribution. Further, since the profile of the laser light L on the reflection surface 410a (or the liquid crystal layer 216) of the reflective spatial light modulator 410 can be acquired, when the optical axis shift occurs, the reflective spatial light modulator 410 of the reflective spatial light modulator 410 can be obtained. It is possible to discriminate between the former stage and the latter stage.

  Further, in the laser processing apparatus 200, the liquid crystal layer 216 includes a plurality of pixel regions 216p arranged along the first direction D1 and the second direction D2 intersecting the first direction D1 and displaying the phase pattern. The holding unit 503 holds a diffraction grating pattern P1 having an edge E1 extending in the first direction D1 and a diffraction grating pattern P2 having an edge E2 extending in the second direction D2. Then, the display control unit 501 performs, as display processing, a first display processing for sequentially displaying the diffraction grating pattern P1 on the liquid crystal layer 216 so that the edge E1 extending in the first direction D1 is shifted in the second direction D2. A second display process of sequentially displaying the diffraction grating pattern P2 on the liquid crystal layer 216 is performed so that the edge E2 extending in the second direction D2 is shifted in the first direction D1. Therefore, the intensity distribution of the laser light L associated with the positions of the edges E1 and E2 along the two directions can be obtained. Therefore, it is possible to obtain a more accurate profile of the laser light L.

  Further, in the laser processing device 200, the display control unit 501 performs an operation of removing the intensity component corresponding to the 0th order diffracted light of the laser light L from the acquired intensity data. Therefore, a more accurate profile of the laser light L can be acquired.

  The above is one embodiment of the present invention. The present invention is not limited to the above embodiments, and may be modified or applied to other things without changing the scope of the claims.

  For example, the above-described embodiment is not limited to the one in which the modified region 7 is formed inside the object to be processed 1, and may be another laser processing such as ablation. The above-described embodiment is not limited to the laser processing apparatus used for laser processing that focuses the laser light L inside the processing object 1, and collects the laser light L on the front surface 1 a, 3 or the back surface 1 b of the processing object 1. It may be a laser processing device used for laser processing that causes light to be emitted. The device to which the present invention is applied is not limited to the laser processing device, and can be applied to various laser light irradiation devices as long as the object is irradiated with the laser light L. In the above-described embodiment, the planned cutting line 5 is the planned irradiation line, but the planned irradiation line is not limited to the planned cutting line 5 and may be any line along which the laser light L to be irradiated is guided.

  Here, the phase pattern held by the holding unit 503 is not limited to the diffraction grating patterns P1 and P2 described above. For example, the holding unit 503 can hold a plurality of diffraction grating patterns P3 having pattern edges E1 at different positions in the liquid crystal layer 216, as shown in FIG. The diffraction grating pattern P3 has, in addition to the edge E1, another edge E3 facing the edge E1 and a slit RS formed between the edge E1 and the edge E3. The slit RS is a long black region RB extending along the extending direction of the edges E1 and E3. Therefore, the edge E3 is a boundary between the diffraction grating region RG and the black region RB.

  The width of the slit RS is substantially constant over the plurality of diffraction grating patterns P3. Therefore, the difference in the position of the edge E1 across the plurality of diffraction grating patterns P3 means that the positions of the edge E3 and the slit RS are different. As a display process, the display control unit 501 sequentially displays the diffraction grating pattern P3 on the liquid crystal layer 216 so that the edge E1 (that is, the edge E3 and the slit RS) is shifted. This makes it possible to acquire the intensity distribution of the laser light L associated with the position of the slit RS. This is different from the knife edge method as described above, and corresponds to measuring the strength by the so-called slit method. In this case as well, the profile of the laser light L can be similarly obtained.

  100, 200 ... Laser processing device (laser light irradiation device), 216 ... Liquid crystal layer (modulation layer), 410 ... Reflective spatial light modulator (spatial light modulator), 422 ... Lens (condensing lens), 424 ... Slit Members, 501 ... Display control unit (acquisition unit, calculation unit), 503 ... Holding unit, E1, E2, E3 ... Edge, P1, P2, P3 ... Diffraction grating pattern, RS ... Slit, L ... Laser light.

Claims (5)

A laser output section for outputting a laser beam,
A spatial light modulator that includes a modulation layer that displays a phase pattern, emits the laser light output from the laser output unit while reflecting the laser light while modulating the laser light according to the phase pattern,
A condenser lens that condenses the laser light emitted from the spatial light modulator,
A slit member arranged at the focal position on the rear side of the condenser lens in the optical path of the laser beam,
An acquisition unit that acquires the intensity of the laser light measured in the latter stage of the slit member in the optical path of the laser light,
A holding unit that holds the phase pattern,
A display control unit that performs a display process for displaying the phase pattern on the modulation layer,
Equipped with
The holding unit holds, as the phase pattern, a plurality of diffraction grating patterns having pattern edges at different positions of the modulation layer,
The display control unit, as the display process, sequentially displays the diffraction grating pattern on the modulation layer so that the edges are shifted,
The slit member blocks ± 1st-order or more diffracted light of the laser light diffracted according to the diffraction grating pattern,
The acquisition unit acquires each intensity data of the laser light modulated by each of the diffraction grating patterns,
Laser light irradiation device. The modulation layer includes a plurality of pixel regions arranged along a first direction and a second direction intersecting the first direction and displaying the phase pattern.
The holding unit holds the diffraction grating pattern having the edge extending in the first direction and the diffraction grating pattern having the edge extending in the second direction,
The display control unit performs, as the display process, a first display process of sequentially displaying the diffraction grating pattern on the modulation layer so that the edge extending in the first direction shifts in the second direction, and A second display process of sequentially displaying the diffraction grating pattern on the modulation layer so that the edge extending in the second direction shifts in the first direction.
The laser light irradiation device according to claim 1. A calculation unit that performs a calculation to remove the intensity component corresponding to the 0th-order diffracted light of the laser light from the intensity data acquired by the acquisition unit;
The laser beam irradiation device according to claim 1 or 2. The diffraction grating pattern includes another edge facing the edge, and a slit formed between the edge and the other edge,
The laser beam irradiation device according to claim 1. A spatial light modulator that includes a modulation layer that displays a phase pattern and that reflects and emits laser light while modulating the laser light according to the phase pattern, and a collector that collects the laser light emitted from the spatial light modulator. A profile acquisition method for obtaining a profile of the laser light in a laser light irradiation device, comprising: a light lens; and a slit member arranged at a focal position on the rear side of a condenser lens in an optical path of the laser light. ,
A display step of sequentially displaying a plurality of diffraction grating patterns as the phase pattern on the modulation layer,
An intensity acquisition step of acquiring each intensity data of the laser light modulated by each of the diffraction grating patterns displayed on the modulation layer in the display step;
A profile acquisition step of acquiring a profile of the laser light based on the intensity data;
Equipped with
The slit member blocks ± 1st-order or more diffracted light of the laser light diffracted according to the diffraction grating pattern,
Each of the diffraction grating patterns has edges at different positions of the modulation layer,
In the displaying step, the diffraction grating pattern is sequentially displayed on the modulation layer so that the edges are shifted,
In the intensity acquisition step, the intensity of the laser light measured in the latter stage of the slit member in the optical path of the laser light is obtained,
Profile acquisition method.