Laser processing device

Abstract

Laser processing device (1) with: a pulsed laser oscillator (51) configured to oscillate a pulsed laser beam (LB) at a predetermined repetition frequency; a main polarization beam splitter (53) which is arranged in a laser beam oscillation direction on a downstream side of the pulse laser oscillator (51); a quarter-wavelength plate (54) which is configured to convert a pulsed laser beam (LB) passing through the main polarization beam splitter (53) from P-polarized light into circularly polarized light; a photoelastic modulation element (55) which is configured to modulate a pulsed laser beam passing through the quarter-wavelength plate (54) into a P-polarized pulsed laser beam and an S-polarized pulsed laser beam; a frequency setting device (730a) which is configured to set a modulation frequency by means of the photoelastic modulation element (55); a subpolarization beam splitter (56) configured to split the P-polarized pulsed laser beam and the S-polarized pulsed laser beam, which are modulated by the photoelastic modulation element (55); a first reversing means (6a; 7a; 57a) for reversing the pulsed laser beam diverted from the P-polarized light by the subpolarization beam splitter (56) to cause the pulsed laser beam to move in the reverse direction thereafter along an optical path of a return path of the pulsed laser beam which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam; a second reversing means (6b; 7b; 57b) for reversing the pulsed laser beam diverted from the S-polarized light by the subpolarization beam splitter (56) to cause the pulsed laser beam to subsequently travel in the reverse direction along an optical path of a return path of the pulsed laser beam which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam; and a condenser (580; 580a) arranged in paths of the pulsed laser beams reflected by the main polarization beam splitter (53), after the pulsed laser beams inverted by the first inversion means (6a; 7a; 57a) and the second inversion means (6b; 7b; 57b) pass through the quarter-wavelength plate (54), whereupon the pulsed laser beams are converted into S-polarized pulsed laser beams.

Description

BACKGROUND OF THE INVENTION Area of ​​the invention

[0001] The present invention relates to a laser processing device that can perform laser processing on a workpiece, such as a semiconductor wafer. Description of the relevant state of the art

[0002] In a semiconductor device manufacturing process, a multitude of regions are subdivided by planned parting lines distributed as a grid across the surface of a semiconductor wafer, which has an essentially circular disk shape. A device, such as an IC or an LSI, is formed in each of the subdivided regions. By cutting the semiconductor wafer along the planned parting lines, the regions containing each device are then separated to produce individual semiconductor chips.

[0003] To achieve miniaturization and improved functionality of a device, a modular structure is used in practice. This structure consists of stacked semiconductor chips with their electrodes coupled together. Within the modular structure, a through-hole is formed at a specific location on the semiconductor wafer, where an electrode is located. A conductive material, such as copper or aluminum, coupled to the electrode, is embedded in the through-hole to form a transmission channel.

[0004] A laser processing device that performs the laser processing described above includes a workpiece holding device for holding a workpiece, a laser beam irradiator for laser processing the workpiece held by the workpiece holding device, and a motion device for moving the workpiece holding device and the laser beam irradiator relative to each other. A method for splitting a laser beam into a plurality of laser beams to form a plurality of compression points is being explored to improve the processing efficiency of the laser processing described above using a laser processing device just described. Reference is made, for example, to German Patent Application JP 2006 - 95 529 A or German Patent Application JP 2008 - 290 086 A.Further laser processing devices are proposed in the patent applications JP 2003 - 181 675 A, DE 10 2005 047 124 A1, DE 10 2008 025 381 A1, DE 10 2013 211 024 A1 and DE 10 2013 211 395 A1. SUMMARY OF THE INVENTION

[0005] However, a problem arises when a polarization beam splitter is used to divide a laser beam oscillated by a laser beam oscillator into a multitude of laser beams in order to form a multitude of concentration points, as in the laser beam irradiation devices disclosed in the publications described above. In this case, the laser beam is split into P-polarized and S-polarized light, and the energy density per pulse is reduced by half. Furthermore, since their polarization planes differ, the processing quality is not consistent.

[0006] The present invention was carried out in view of the facts described above, and the main technical object of the present invention is to provide a laser processing device capable of splitting a pulsed laser beam into a plurality of laser beams in order to form a plurality of compression points without reducing the energy density per pulse.

[0007] In accordance with one aspect of the present invention, a laser processing device is provided comprising: a pulsed laser oscillator configured to oscillate a pulsed laser beam at a predetermined repetition frequency; a main polarization beam splitter arranged in a laser beam oscillation direction on a downstream side of the pulsed laser oscillator; a quarter-wavelength plate configured to convert a pulsed laser beam passing through the main polarization beam splitter from P-polarized light into circularly polarized light; a photoelastic element configured to modulate a pulsed laser beam passing through the quarter-wavelength plate into a P-polarized pulsed laser beam and an S-polarized pulsed laser beam;a frequency-adjusting device configured to set a modulation frequency by means of the photoelastic modulating element; a subpolarization beam splitter configured to divert the P-polarized pulsed laser beam and the S-polarized pulsed laser beam modulated by the photoelastic modulating element; a first reversing means for reversing the pulsed laser beam diverted by the subpolarization beam splitter from the P-polarized light to cause the pulsed laser beam to subsequently travel in the reverse direction along an optical path of a return path of the pulsed laser beam, which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam;a second reversing means for reversing the laser beam diverted by the subpolarization beam splitter from the S-polarized light, to cause the pulsed laser beam to subsequently travel in the reverse direction along an optical path of a return path of the pulsed laser beam, which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam; and a condenser arranged in paths of the pulsed laser beams reflected by the main polarization beam splitter after the pulsed laser beams, reversed by the first reversing means and the second reversing means, have passed through the quarter-wavelength plate, whereupon the pulsed laser beams are converted into S-polarized pulsed laser beams.

[0008] If the predetermined repetition frequency of the pulsed laser beam oscillated by the pulsed laser oscillator is H Hz, the frequency adjustment device preferably sets a power frequency to be supplied to the photoelastic modulation element to H / 2 Hz, and the pulsed laser beam, which is oscillated by the pulsed laser oscillator with a maximum amplitude and a minimum amplitude, is modulated by the photoelastic modulation element into a pulsed laser beam of P-polarized light and a pulsed laser beam of S-polarized light. Preferably, the first reversing means includes an angle-adjustable first mirror and the second reversing means includes an angle-adjustable second mirror.

[0009] Preferably, the first reversing device is configured by: a first photoelastic modulating element configured to modulate the pulsed laser beam diverted by the subpolarization beam splitter from the P-polarized light into a pulsed laser beam of P-polarized light and a pulsed laser beam of S-polarized light; a first frequency-adjusting device configured to set a modulation frequency by means of the first photoelastic modulating element; a first polarization beam splitter configured to divert the P-polarized pulsed laser beam and the S-polarized pulsed laser beam that are modulated by the first photoelastic modulating element;a first mirror configured to reverse the pulsed laser beam diverted from the P-polarized light by the first polarization beam splitter, causing the pulsed laser beam to subsequently travel in the reverse direction along an optical path of a return path of the pulsed laser beam, which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam; and a second mirror configured to reverse the pulsed laser beam diverted from the S-polarized light by the first polarization beam splitter, causing the pulsed laser beam to subsequently travel in the reverse direction along an optical path of a return path of the pulsed laser beam, which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam;and the second reversing device is provided by: a second photoelastic modulating element, which is configured to modulate the pulsed laser beam from the S-polarized light, branched off by the subpolarization beam splitter, into a pulsed laser beam from the P-polarized light and a pulsed laser beam from the S-polarized light; a second frequency-adjusting device, which is configured to set a modulation frequency by means of the second photoelastic modulating element; a second polarization beam splitter, which is configured to branch off the pulsed laser beam from the P-polarized light and the pulsed laser beam from the S-polarized light, which are modulated by the second photoelastic modulating element;a third mirror configured to reverse the pulsed laser beam diverted from the P-polarized light by the second polarization beam splitter, causing the pulsed laser beam to subsequently travel in the reverse direction along an optical path of the pulsed laser beam that is slightly inclined with respect to an optical path of the forward path of the pulsed laser beam; and a fourth mirror configured to reverse the pulsed laser beam diverted from the S-polarized light by the second polarization beam splitter, causing the pulsed laser beam to subsequently travel in the reverse direction along an optical path of the pulsed laser beam that is slightly inclined with respect to an optical path of the forward path of the pulsed laser beam.

[0010] The first frequency adjustment device, which sets the first reversing means, preferably sets a power frequency to be supplied to the first photoelastic modulating element to H / 4 Hz; the first photoelastic modulating element modulates the pulsed laser beam from the P-polarized light, which is branched off by the subpolarization beam splitter with a maximum amplitude and a minimum amplitude, into a pulsed laser beam from the P-polarized light and a pulsed laser beam from the S-polarized light; the second frequency adjustment device, which sets the second reversing means, sets a power frequency to be supplied to the second photoelastic modulating element to H / 4 Hz;and the second photoelastic modulation element modulates the pulsed laser beam from the S-polarized light, which is branched off by the subpolarization beam splitter with a maximum amplitude and a minimum amplitude, into a pulsed laser beam from the P-polarized light and a pulsed laser beam from the S-polarized light.

[0011] Preferably, the first reversing device is configured by: a first resonant scanner configured to distribute the pulsed laser beam diverted from the P-polarized light by the subpolarization beam splitter onto a first path and a second path; a first frequency-adjusting device configured to set a distribution frequency of the first resonant scanner; an angle-adjustable first mirror arranged in the first path and configured to reverse the pulsed laser beam distributed from the P-polarized light by the first resonant scanner, causing the pulsed laser beam to subsequently travel along an optical path of a return path of the pulsed laser beam, which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam;and an angle-adjustable second mirror, arranged in the second path and configured to reverse the pulsed laser beam of P-polarized light distributed by the first resonant scanner, to cause the pulsed laser beam to subsequently travel along an optical path of a return path of the pulsed laser beam, which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam; and the second reversing means is configured by: a second resonant scanner configured to distribute the pulsed laser beam of S-polarized light distributed by the subpolarization beam splitter into a third path and a fourth path; a second frequency-adjusting device configured to adjust a distribution frequency of the second resonant scanner;an angle-adjustable third mirror, arranged in the third path and configured to reverse the pulsed laser beam distributed by the second resonance scanner from the S-polarized light, to cause the pulsed laser beam to subsequently travel along an optical path of a return path of the pulsed laser beam, which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam; and an angle-adjustable fourth mirror, arranged in the fourth path and configured to reverse the pulsed laser beam distributed by the second resonance scanner from the S-polarized light, to cause the pulsed laser beam to subsequently travel along an optical path of a return path of the pulsed laser beam, which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam.

[0012] Preferably, the first frequency-adjusting device, which sets the first reversing means, sets a power frequency to be supplied to the first resonant scanner to H / 4 Hz; the first resonant scanner distributes the pulsed laser beam from the P-polarized light, which is branched off by the subpolarization beam splitter with a maximum amplitude and a minimum amplitude, to the first path and the second path; the second frequency-adjusting device, which sets the second reversing means, sets a power frequency to be supplied to the second resonant scanner to H / 4 Hz; and the second resonant scanner distributes the pulsed laser beam from the S-polarized light, which is branched off by the subpolarization beam splitter with a maximum amplitude and a minimum amplitude, to the third path and the fourth path.

[0013] With the laser processing device of the present invention, it is possible to split a pulsed laser beam oscillated by the pulsed laser oscillator into a plurality of pulsed laser beams in a state in which the energy density of the oscillated pulsed laser beam is maintained, so that the plurality of pulsed laser beams can be emitted onto a plurality of locations of a workpiece and thereby improve productivity.

[0014] The above and other problems, features and advantages of the present invention and the manner of its implementation will become clearer by studying the following description and the attached claims with reference to the attached drawings, which show some preferred embodiments of the invention, and the invention itself will be best understood by this. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a perspective view of a laser processing device in accordance with an embodiment of the present invention; Fig. 2 is a block diagram of a laser beam irradiator used in the Fig. is integrated into the laser processing device shown in 1; Fig. Figure 3 is a block diagram illustrating another embodiment of a condenser that incorporates the in Fig. 2 laser beam irradiation devices shown; Fig. 4 is a block diagram representing a second embodiment of a first reversing device and a second reversing device, which is described in Fig. 2. Set up the laser beam irradiation devices shown; and Fig. 5 is a block diagram representing a third embodiment of the first reversing device and the second reversing device, which is described in Fig. Set up the 2 laser beam irradiation devices shown. DESCRIPTION OF PREFERRED EXECUTION FORMS

[0015] Suitable embodiments of the laser processing device, which are set up in accordance with the present invention, are described in detail below with reference to the attached drawings. Fig. Figure 1 shows a perspective view of a laser processing device 1 which includes a laser oscillation mechanism configured in accordance with the present invention. The in Fig. The laser processing device 1 shown includes a stationary base 2, a clamping table mechanism 3 which is arranged on the stationary base for movement in a processing feed direction (X-axis direction) indicated by an arrow marked with an X and which is set up to hold a workpiece on it, and a laser beam irradiation unit 4 arranged on the stationary base 2 as a laser beam irradiation means.

[0016] The clamping table mechanism 3 includes a pair of guide rails 31 arranged parallel along the X-axis direction on the stationary base 2, a first sliding or cam block 32 arranged on the pair of guide rails 31 for movement in the X-axis direction, a second cam block 33 arranged on the first cam block 32 for movement in a Y-axis direction indicated by an arrow marked with a Y and perpendicular to the X-axis direction, a support table 35 supported by a cylindrical element 34 on the second cam block 33, and a clamping table 36 as a workpiece holding device.The clamping table 36 includes a receiving clamping device 361, which is equipped with a porous material. For example, a circular semiconductor wafer, which is a workpiece, is held by a suction element (not shown) against a holding surface, which is an upper surface of the receiving clamping device 361. The clamping table 36, configured as just described, is rotated by a stepper motor (not shown) located in the cylindrical element 34. It should be noted that a clamp 362 for attaching an annular frame for supporting a workpiece, such as a semiconductor wafer, is arranged on the clamping table 36 via a protective band.

[0017] The first cam block 32 includes a pair of guide slots 321, which are provided on its lower surface for mounting with the pair of guide rails 31, and a pair of guide rails 322, which are formed parallel along the Y-axis direction and are provided on its upper surface. The first cam block 32, configured as just described, is set up for movement in the X-axis direction along the pair of guide rails 31 by mounting the guide slots 321 with the pair of guide rails 31. The holding table mechanism 3 includes an X-axis motion element 37 for moving the first cam block 32 in the X-axis direction along the pair of guide rails 31.The X-axis direction mover 37 includes an outer threaded rod 321, arranged parallel to and between the pair of guide rails 31, and a drive source, such as a stepper motor 372, for driving the outer threaded rod for rotation. The outer threaded rod 371 is supported at one end for rotation by a bearing block 373, which is attached to the stationary base 2, and at its other end is coupled to an output power shaft of the stepper motor 372. It should be noted that the outer threaded rod 371 is screwed into a penetrating inner threaded hole (not shown) formed in an inner threaded block that protrudes from the lower surface of a central section of the first cam block 32.By driving the outer threaded rod 371 by the stepper motor 372 for a forward rotation and a reverse rotation, the first cam block 32 is moved accordingly in the X-axis direction along the guide rails 31.

[0018] The second cam block 33 includes a pair of guide slots 331 on its lower surface for mounting with the pair of guide rails 322 provided on the upper surface of the first cam block 32, and is configured for movement in the Y-axis direction by mounting the guide slots 331 with the pair of guide rails 322. The holding table mechanism 3 includes a Y-axis direction mover 38 for moving the second cam block 33 in the Y-axis direction along the pair of guide rails 322 provided on the first cam block 32. The Y-axis direction mover 38 includes an outer threaded rod 381 arranged parallel to and between the pair of guide rails 322, and a drive source, such as a stepper motor 382, ​​for driving the outer threaded rod 381 for rotation.The outer threaded rod 381 is supported at one end for rotation by a bearing block 383, which is attached to the upper surface of the first cam block 32, and is coupled at its other end to an output power shaft of the stepper motor 382. It should be noted that the outer threaded rod 381 is screwed into a penetrating inner screw hole formed in an inner screw block (not shown) that protrudes from the lower side of a central section of the second cam block 33. By driving the outer threaded rod 381 forward and reverse, the stepper motor 382 moves the second cam block 33 accordingly along the guide rails 322 in the Y-axis direction.

[0019] The laser beam irradiation unit 4 includes a support element 41 arranged on the stationary base 2, a housing 42 supported by the support element 41 and extending substantially in a horizontal direction, a laser beam irradiation device 5 arranged on the housing 42, and an image acquisition device 50 arranged at a front end section of the housing 42 for acquiring a processing area in which laser processing is to be performed. It should be noted that the image acquisition device 50 comprises an illumination device for illuminating a workpiece, an optical system for acquiring an area illuminated by the illumination device, an image acquisition device (CCD) for acquiring an image captured by the optical system, and so on.

[0020] The first embodiment of the laser beam irradiation device 5 described above is described with reference to Fig. 2 described. The laser beam irradiator 5 includes a laser pulse oscillator 51, which oscillates a pulsed laser beam, a half-wavelength plate 52, a main polarization beam splitter 53, a quarter-wavelength plate 54, a photoelastic modulation element 55, and a subpolarization beam splitter 56, which are arranged sequentially on the downstream side in a laser beam oscillation direction of the pulsed laser oscillator 51. In the present embodiment, the pulsed laser oscillator 51 oscillates a pulsed laser beam LB having a repetition frequency H of 40 kHz with a wavelength (for example, 355 nm) with an absorption coefficient suitable for a workpiece, which is, for example, provided by a silicon wafer. The pulsed laser oscillator 51 is controlled by a control device 500.

[0021] The half-wavelength plate 52 described above rotates the polarization planes of the pulsed laser beam LB, which is oscillated by the pulsed laser oscillator 51, so that the P-polarized light passes through the main polarization beam splitter 53. The main polarization beam splitter 53 allows the pulsed laser beam LB, which is oscillated by the pulsed laser oscillator 51 and is adjusted through the half-wavelength plate 52 so that the P-polarized light passes through. The quarter-wavelength plate 54 converts the pulsed laser beam, which has passed through the main polarization beam splitter 53, from P-polarized light into circularly polarized light. It should be noted that the half-wavelength plate 52 is not necessarily required and alternatively the pulse laser oscillator 51 can be rotated about its optical axis so that the P-polarized light passes through the main polarization beam splitter 53.

[0022] The photoelastic modulating element 55 modulates the pulsed laser beam passing through the quarter-wavelength plate 54 into P-polarized and S-polarized light based on the modulation frequency, which is set by a frequency adjustment device 550. In the present embodiment, when the repetition frequency H of the pulsed laser beam oscillated by the pulse laser oscillator 51 is set to 40 kHz, the frequency of the power supplied to the photoelastic modulating element by the frequency adjustment device 550 is set to H / 2 Hz, i.e., 20 kHz, and the photoelastic modulating element 55 alternately modulates the pulsed laser beam, oscillated by the pulse laser oscillator 51 with a maximum amplitude and a minimum amplitude, into P-polarized and S-polarized light. It should be noted that the frequency setting device 550 is controlled by the control device 500.

[0023] The subpolarization beam splitter 56 diverts the P-polarized and S-polarized light modulated by the photoelastic modulation element 55 and directs the P-polarized and S-polarized light to a first reversing device 57a and a second reversing device 57b, respectively. The first reversing device 57a causes the pulsed laser beam of P-polarized light diverted by the subpolarization beam splitter 56 to propagate in reverse along an optical path of a return path of the pulsed laser beam, after a reflection from the P-polarized light is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam.Furthermore, the second reversing device 57b reverses the pulsed laser beam of S-polarized light diverted by the subpolarization beam splitter 56, causing the pulsed laser beam to propagate in the reverse direction along an optical path of the return path of the pulsed laser beam after a reflection is slightly inclined with respect to an optical path of the forward path of the pulsed laser beam from the S-polarized light. The first reversing device 57a and the second reversing device 57b are adjusted by angle-adjustable mirrors 571a and 571b, respectively, the angles of which can be adjusted and whose angles are set by a mirror angle control 572. It should be noted that the mirror angle control 572 can deflect the angle-adjustable mirrors 571a and 571b in an X-axis direction and a Y-axis direction, respectively, and is controlled by the control device 500.

[0024] The pulsed laser beams, which are reversed by the first reversing device 57a and the second reversing device 57b in order to then propagate in the opposite direction, are converted into S-polarized light as they pass through the quarter-wavelength plate 54 and are then directed to the main polarization beam splitter 53. The pulsed laser beams that are fed to the main polarization beam splitter 53 and converted into S-polarized light are diverted (reflected) to a laser beam emission path 58. A condenser 580 is arranged in the laser beam emission path 58 and includes a condenser lens 581, which condenses the pulsed laser beams introduced into the main polarization beam splitter 53 and emits the condensed pulsed laser beams onto a workpiece W held on the clamping table 36.

[0025] The in Fig. The laser beam irradiator 5 of the first embodiment, as illustrated in Figure 2, is configured as described above, and its operation is described below. A pulsed laser beam LB, oscillated by the pulsed laser oscillator 51 and having a repetition frequency H of 40 kHz, is adjusted by the half-wavelength plate 52 such that P-polarized light passes through the main polarization beam splitter 53. The pulsed laser beam of P-polarized light passing through the main polarization beam splitter 53 is converted into circularly polarized light by the quarter-wavelength plate 54 and fed to the photoelastic modulation element 55. The pulsed laser beam introduced into the photoelastic modulation element 55 is alternately modulated into P-polarized and S-polarized light.Since the frequency setting device 550 sets the power frequency to be supplied to the photoelastic modulation element 55 to H / 2 Hz, i.e. to 20 kHz, the P-polarized light and the S-polarized light have a frequency of 20 kHz in the present embodiment.

[0026] The P-polarized light and the S-polarized light, modulated by the photoelastic modulating element 55, are diverted by the subpolarization beam splitter 56. The P-polarized light is fed to the first reversing device 57a, and the S-polarized light is fed to the second reversing device 57b. The P-polarized light introduced into the first reversing device 57a is reflected by the angle-adjustable mirror 571a, as indicated by a dashed line alternating with long and short dashed lines, and then propagates in reverse along an optical path of a return path, which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam.Meanwhile, the S-polarized light introduced into the second reversing device 57b is reflected by the angle-adjustable mirror 571b, as indicated by a dashed line with alternating long and short lines, and then propagates in the reverse direction along an optical path of a return path, which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam. It should be noted that the angles and directions over and to which the pulsed laser beams are reflected by the angle-adjustable mirrors 571a and 571b with respect to the optical paths of the forward paths of the pulsed laser beams can be adjusted by the mirror angle control 572.

[0027] As described above, the pulsed laser beams, which propagate through the first reversing device 57a and the second reversing device 57b in the opposite direction at an angle to the optical paths of the forward paths of the pulsed laser beams, pass through the photoelastic modulation element 55 and are directed to the quarter-wavelength plate 54, as indicated by a dashed line with alternating long and short lines and a dashed line with alternating one long and two short lines. The pulsed laser beams directed to the quarter-wavelength plate 54 are converted into S-polarized light by reversing their polarization planes and are directed to the laser beam irradiation path 58 by the main polarization beam splitter 53, as indicated by a dashed line with alternating one long and one short line and a dashed line with alternating one long and two short lines.The pulsed laser beams supplied through the laser beam irradiation path 58 are concentrated by the condenser lens 581 of the condenser 580, as indicated by a dashed line with alternating long and short lines and a dashed line with alternating long and two short lines, and are emitted at predetermined intervals L onto the workpiece W, which is held on the clamping table 36. It should be noted that the directions of and the distance L between the pulsed laser beams, indicated by a dashed line with alternating long and short lines and a dashed line with alternating long and two short lines, are adjusted by the angle-adjustable mirror 571a and the angle-adjustable mirror 571b of the first reversing device 57a and the second reversing device 57b, respectively.Since the pulsed laser beams emitted onto the workpiece W held on the clamping table 36, i.e., in the present embodiment, the pulsed laser beams indicated by a dashed line with alternating long and short lines and a dashed line with alternating long and two short lines, have a repetition frequency of 20 kHz, the energy density of the pulsed laser beam LB, which is oscillated by the pulsed laser oscillator 51, is maintained in this way. Accordingly, in the case of the Fig. In the embodiment shown in Figure 2, by emitting the pulsed laser beams, indicated by a dashed line with alternating long and short lines and a dashed line with alternating long and two short lines, hole processing is carried out simultaneously at two locations while maintaining their energy density.

[0028] Now, with reference to Fig. 3 another embodiment of the condenser 580 is described.

[0029] A in Fig. The condenser 580a shown in Figure 3 is configured by a direction-conversion mirror 582, a galvanic scanner 583, and a condenser lens 581. The direction-conversion mirror 582 converts the direction of the pulsed laser beam supplied to the laser beam irradiation path 58 by the main polarization beam splitter 53. The galvanic scanner 583 serves as a deflector for deflecting the pulsed laser beam, the direction of which is converted to the X-axis direction by the direction-conversion mirror 582. The condenser lens 581 compresses the pulsed laser beam deflected by the galvanic scanner 583 and emits the compressed pulsed laser beam onto the workpiece held on the clamping table 36. It should be noted that the galvanic scanner 583 is controlled by the control device 500.The condenser 580a, configured as described above, deflects the pulsed laser beam by moving the electroplating scanner 583 from a position indicated by a solid line to another position indicated by a dashed line. The direction of the laser beam is converted in the X-axis direction by the direction-conversion mirror 582 from the position indicated by the solid line to the position indicated by the dashed line, in order to direct the pulsed laser beam to the condenser lens 581. The displacement speed of the electroplating scanner 583 from the position indicated by the solid line to the position indicated by the dashed line is synchronized with the speed of movement of the clamping table 36. Fig. 3 to the left, the pulsed laser beam can be used in the Fig. 2. Accordingly, in the embodiment shown, radiation is continuously emitted in a state at irradiation positions indicated by a dashed line with alternating long and short lines and a dashed line with alternating long and two short lines, in which the clamping table 36 is in Fig. 3 is fed to the left for processing.

[0030] It is now referred to Fig. 4 describes a second embodiment of the first reversing means and the second reversing means, which set up the laser beam irradiation means 5. A in Fig. The first reversing device 6a shown in Figure 4 includes a first photoelastic modulating element 61a, a first frequency-adjusting device 610a, a first polarization beam splitter 62a, an angle-adjustable first mirror 63a, and an angle-adjustable second mirror 64a. The first photoelastic modulating element 61a modulates the pulsed laser beam, which is branched off by the subpolarization beam splitter 56 described above, from P-polarized light to P-polarized light and S-polarized light. The first frequency-adjusting device 610a sets a modulation frequency to the first photoelastic modulating element 61a. The first polarization beam splitter 62a branches off the P-polarized light and the S-polarized light that have been modulated by the first photoelastic modulating element 61a.The first mirror 63a reflects the pulsed laser beam of P-polarized light, branched off by the first polarization beam splitter 62a, in such a way that the pulsed laser beam then propagates in the opposite direction along an optical path of a return path, which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam. The second mirror 64a reflects the pulsed laser beam of S-polarized light, branched off by the first polarization beam splitter 62a, in such a way that the pulsed laser beam then propagates in the opposite direction along an optical path of a return path of the pulsed laser beam, which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam.It should be noted that the first photoelastic modulating element 61a modulates the pulsed laser beam branched off by the subpolarization beam splitter 56 described above from the P-polarized light to P-polarized light and S-polarized light on the basis of the modulation frequency set by the first frequency adjustment device 610a.

[0031] Since the repetition frequency H of the pulsed laser beam oscillated by the pulsed laser oscillator 51 is set to 40 kHz, the repetition frequency of the pulsed laser beam branched off from the P-polarized light by the subpolarization beam splitter 56 is 20 kHz in the present embodiment. Therefore, the power frequency to be supplied to the first photoelastic modulation element 61a is set to H / 4 Hz, i.e., 10 kHz, by the first frequency setting device 610a, and the pulsed laser beam from the P-polarized light, which has been branched off by the subpolarization beam splitter 56 at a maximum amplitude and a minimum amplitude and has a repetition frequency of 20 kHz, is alternately modulated into P-polarized light and S-polarized light by the first photoelastic modulation element 61a. It should be noted that the first frequency setting device 610a is controlled by the control device 500.

[0032] A in Fig. The second reversing device 6B shown in Figure 4 includes a second photoelastic modulating element 61b, a second frequency-adjusting device 610b, a second polarization beam splitter 62b, an angle-adjustable third mirror 63b, and an angle-adjustable fourth mirror 64b. The second photoelastic modulating element 61b modulates the pulsed laser beam, branched off by the subpolarization beam splitter 56 described above, from S-polarized light into P-polarized light and S-polarized light. The second frequency-adjusting device 610b sets a modulation frequency for the second photoelastic modulating element 61b. The second polarization beam splitter 62b branches off the P-polarized light and the S-polarized light that have been modulated by the second photoelastic modulating element 61b.The third mirror 63b reflects the pulsed laser beam branched off from the P-polarized light by the second polarization beam splitter 62b in such a way that the pulsed laser beam then propagates in the opposite direction along an optical path of a return path, which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam. The fourth mirror 64b reflects the pulsed laser beam branched off from the S-polarized light by the second polarization beam splitter 62b in such a way that the pulsed laser beam then propagates in the opposite direction along an optical path of a return path, which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam.It should be noted that the second photoelastic modulating element 61b modulates the pulsed laser beam branched off from the S-polarized light by the subpolarization beam splitter 56 described above into P-polarized light and S-polarized light based on the modulation frequency set by the second frequency control device 610b. Since, in the present embodiment, the repetition frequency H of the pulsed laser beam oscillated by the pulse laser oscillator 51 is set to 40 kHz, the repetition frequency of the pulsed laser beam branched off from the S-polarized light by the subpolarization beam splitter 56 is 20 kHz. Therefore, the power frequency to be supplied to the second photoelastic modulating element 61b is set by the second frequency control device 610b to H / 4 Hz, i.e.,The pulsed laser beam, derived from the S-polarized light, is set to 10 kHz. This beam is branched off by the subpolarization beam splitter 56 with a maximum and minimum amplitude and has a repetition frequency of 20 kHz. It is alternately modulated into P-polarized and S-polarized light by the second photoelastic modulation element 61b. The second frequency-adjusting device 610b is controlled by the control device 500.

[0033] It should be noted that the angles of the first and second adjustable mirrors 63a and 64a and the third and fourth adjustable mirrors 63b and 64b, which set the first reversing device 6a and the second reversing device 6b respectively, are set by a mirror angle control 65. The mirror angle control 65 is controlled by the control device 500.

[0034] The first reversal agent 6a and the second reversal agent 6b, which are in Fig. The components shown in Figure 4 are set up as described above, and the operation of the reversing device is described below. The P-polarized light and the S-polarized light modulated by the first photoelastic modulating element 61a, which sets up the first reversing device 6a, are diverted by the first polarizing beam splitter 62a. The P-polarized light is fed to the first mirror 63a, while the S-polarized light is fed to the second mirror 64a. The P-polarized light fed to the first mirror 63a is reflected by the first mirror 63a, as indicated by a dashed line with alternating long and short lines, and then propagates in the opposite direction along an optical path of a return path, which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam.Meanwhile, the S-polarized light supplied to the second mirror 64a is reflected by the second mirror 64a, as indicated by a dashed line with alternating long and short lines, and then propagates in the opposite direction along an optical path of a return path, which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam. It should be noted that the angles and directions through which and to which the pulsed laser beams are reflected by the angle-adjustable first mirror 63a and second mirror 64a can be adjusted by the mirror angle control 65.

[0035] The P-polarized and S-polarized light, modulated by the second photoelastic modulating element 61b, which provides the second reversing device 6b, are diverted by the second polarizing beam splitter 62b. The P-polarized light is directed to the third mirror 63b, while the S-polarized light is directed to the fourth mirror 64b. The P-polarized light directed to the third mirror 63b is reflected by the third mirror 63b, as indicated by a dashed line with alternating long and short lines, and then propagates in the opposite direction along an optical path of a return path, which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam.Meanwhile, the S-polarized light supplied to the fourth mirror 64b is reflected by the fourth mirror 64b, as indicated by a dashed line with alternating long and two short lines, and then propagates in the opposite direction along an optical path of a return path, which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam. It should be noted that the angles and directions at which and to which the pulsed laser beams are inclined with respect to the optical axes of the pulsed laser beams by the angle-adjustable third mirror 63b and fourth mirror 64b can be adjusted by the mirror angle control 65.

[0036] The pulsed laser beams, which propagate in reverse along optical paths of the return paths, which are slightly inclined with respect to the optical paths of the forward paths of the pulsed laser beams through the first reversing means 6a and the second reversing means 6b, are fed to the subpolarization beam splitter 56 as a total of four pulsed laser beams, as indicated by a dashed line with alternating long and short lines and a dashed line with alternating long and two short lines. The four pulsed laser beams fed to the subpolarization beam splitter 56 are then modulated via the photoelastic modulation element 55, the quarter-wavelength plate 54, and the main polarization beam splitter 53, which are located in Fig. The pulsed laser beams, as shown in Figure 2, are fed to the laser beam irradiation path 58. The pulsed laser beams fed to the laser beam irradiation path 58 are concentrated by the condenser lens 581 of the condenser 580 and emitted onto the workpiece W held on the clamping table 36. Since each of the frequencies of the four pulsed laser beams emitted onto the workpiece W held on the clamping table 36 is 10 kHz in the present embodiment, the energy density of the pulsed laser beam LB oscillated by the pulse laser oscillator 51 is maintained in this way. Accordingly, hole machining by irradiation with the pulsed laser beams can be performed simultaneously at four locations, the energy density of which is maintained.

[0037] Now, with reference to Fig. 5 describes a third embodiment of the first reversing means and the second reversing means, which set up the laser beam irradiation means 5. A first in Fig. The reversing device 7a shown in Figure 5 includes a first resonant scanner 73a, a first frequency-adjusting device 730a, an angle-adjustable first mirror 74a, and an angle-adjustable second mirror 75a. The first resonant scanner 73a distributes the pulsed laser beam, branched from the P-polarized light by a subpolarization beam splitter 56, onto a first path 71a and a second path 72a. The first frequency-adjusting device 730a sets a distribution frequency for the first resonant scanner 73a. The first mirror 74a is located in the first path 71a and reflects the pulsed laser beam from the P-polarized light, distributed by the first resonant scanner 73a, in such a way as to cause the pulsed laser beam to propagate in the reverse direction along an optical path of a return path that is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam.The second mirror 75a is arranged in the second path 72a and reflects the pulsed laser beam distributed by the first resonance scanner 73a from the P-polarized light in such a way as to cause the pulsed laser beam to move in the opposite direction along an optical path of a return path which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam.

[0038] It should be noted that the first resonance scanner 73a distributes the pulsed laser beam, branched off from the P-polarized light by the subpolarization beam splitter 56, to the first path 71a and the second path 72a based on a distribution frequency set by the first frequency adjustment device 37a. In the present embodiment, if the repetition frequency H of the pulsed laser beam oscillated by the pulse laser oscillator 51 is set to 40 kHz, the repetition frequency of the pulsed laser beam from the P-polarized light branched off by the subpolarization beam splitter 56 is 20 kHz. Therefore, the power frequency supplied to the first resonance scanner 73a is set by the first frequency adjustment device 73a to H / 4 Hz, i.e., 10 kHz.The pulsed laser beam of P-polarized light, which has been branched off by the subpolarization beam splitter 56 at a maximum and a minimum amplitude, is distributed by the first resonance scanner 73a to the first path 71a and the second path 72a. It should be noted that the first frequency adjustment device 730a is controlled by the control device 500.

[0039] A second one in Fig. The reversing device 7b shown in Figure 5 includes a second resonant scanner 73b, a second frequency-adjusting device 730b, an angle-adjustable third mirror 74b, and an angle-adjustable fourth mirror 75b. The second resonant scanner 73b distributes the pulsed laser beam, branched off from the S-polarized light by the subpolarization beam splitter 56, onto a third path 71b and a fourth path 72b. The second frequency-adjusting device 730b sets a distribution frequency on the second resonant scanner 73b. The third mirror 74b is arranged in the third path 71b and reflects the pulsed laser beam from the S-polarized light distributed by the second resonant scanner 73b in such a way as to cause the pulsed laser beam to subsequently travel in the reverse direction along an optical path of a return path, which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam.The fourth mirror 75b is arranged in the fourth path 72b and reflects the pulsed laser beam distributed by the second resonance scanner 73b from the S-polarized light in such a way as to cause the S-polarized light to travel in the opposite direction along an optical path of a return path which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam.

[0040] It should be noted that the second resonance scanner 73b splits the pulsed laser beam distributed by the subpolarization beam splitter 56 from the S-polarized light into the third path 71b and the fourth path 72b based on the distribution frequency set by the second frequency control device 730b. In the present embodiment, if the repetition frequency H of the pulsed laser beam oscillated by the pulse laser oscillator 51 is set to 40 kHz, the repetition frequency of the pulsed laser beam branched off from the S-polarized light by the subpolarization beam splitter 56 is 20 kHz. Consequently, the power frequency to be supplied to the second resonance scanner 73b by the second frequency control device 730b is H / 4 Hz, i.e.,The pulsed laser beam, derived from the S-polarized light and branched off by the subpolarization beam splitter 56 with a maximum and minimum amplitude, is distributed by the second resonance scanner 73b to the third path 71b and the fourth path 72b. It should be noted that the second frequency setting device 730b is controlled by the control device 500.

[0041] It should be noted that the angles of the first and second adjustable mirrors 74a and 75a and the third and fourth adjustable mirrors 74b and 75b, which set the first reversing device 7a and the second reversing device 7b respectively, are set by a mirror angle control 76. The mirror angle control 76 is controlled by the control device 500.

[0042] The in Fig. The first reversing device 7a and the second reversing device 7b shown in Figure 5 are set up as described above, and the operation of the reversing device is described below. The pulsed laser beam diverted from the P-polarized light by the subpolarization beam splitter 56 is distributed by the first resonance scanner 73a, which sets up the first reversing device 7a, onto the first path 71a and the second path 72a. The pulsed laser beam distributed onto the first path 71a is fed to the first mirror 74a, and the pulsed laser beam distributed onto the second path 72a is fed to the second mirror 75a.The pulsed laser beam fed to the first mirror 74a is reflected by the first mirror 74a, as indicated by a dashed line with one long and one short line, and propagates in the opposite direction along an optical path of a return path, which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam. Meanwhile, the pulsed laser beam fed to the second mirror 75a is reflected by the second mirror 75a, as indicated by a dashed line with one long and two short lines, and propagates in the opposite direction along an optical path of a return path, which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam.It should be noted that the angles and directions by which and to which the optical paths of the return paths are inclined with respect to the optical paths of the forward paths of the pulsed laser beams through the angle-adjustable first mirror 74a and the second mirror 75a can be set by the mirror angle control 76.

[0043] The pulsed laser beam from the S-polarized light branched off by the subpolarization beam splitter 56 is distributed by the second resonance scanner 73b, which establishes the second reversing device 7b, to the third path 71b and the fourth path 72b. The pulsed laser beam distributed to the third path 71b is fed to the third mirror 74b, and the pulsed laser beam distributed to the fourth path 72b is fed to the fourth mirror 75b. The pulsed laser beam fed to the third mirror 74b is reflected by the third mirror 74b, as indicated by a dashed line with alternating long and short lines, and propagates in the reverse direction along an optical path of a return path, which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam.Meanwhile, the pulsed laser beam fed to the fourth mirror 75b is reflected by the fourth mirror 75b, as indicated by a dashed line with alternating long and short lines, and travels in the opposite direction along an optical path of a return path, which is slightly inclined relative to an optical path of a forward path of the pulsed laser beam. It should be noted that the angles and directions by which and to which the optical paths of the return paths are inclined relative to the optical paths of the forward paths of the pulsed laser beams by the angle-adjustable third mirror 74b and fourth mirror 75b can be adjusted by the angle control 76.

[0044] The pulsed laser beams, which are reversed by the first reversing device 7a and the second reversing device 7b and propagate in the opposite direction along the optical paths of the return paths, which are slightly inclined with respect to the optical paths of the forward paths of the pulsed laser beams, are fed as a total of four pulsed laser beams to the subpolarization beam splitter 56, as indicated by a dashed line with alternating long and short lines and a dashed line with alternating long and two short lines. Then, the four pulsed laser beams fed to the subpolarization beam splitter 56 are fed to the laser beam irradiation path 58 through the photoelastic modulation element 55, the quarter-wavelength plate 54, and the main polarization beam splitter 53, which are in Fig.Figure 2 shows the pulsed laser beams supplied to the laser beam irradiation path 58. These pulsed laser beams are concentrated by the condenser lens 581 of the condenser 580 and are emitted onto the workpiece W held on the clamping table 36. If each of the frequencies of the four pulsed laser beams emitted onto the workpiece W held on the clamping table 36 is 10 kHz in the present embodiment, the energy density of the pulsed laser beam LB oscillated by the pulse laser oscillator 51 is maintained.

[0045] Accordingly, hole processing can be performed simultaneously at four locations by emitting pulsed laser beams whose energy density is maintained.

[0046] The present invention is not limited to the details of the preferred embodiments described above. The scope of protection of the invention is defined by the appended claims, and all modifications and adaptations that fall within the equivalent scope of protection of the claims are thus included by the invention.

Claims

[1] Laser processing device (1) with: a pulsed laser oscillator (51) configured to oscillate a pulsed laser beam (LB) at a predetermined repetition frequency; a main polarization beam splitter (53) which is arranged in a laser beam oscillation direction on a downstream side of the pulse laser oscillator (51); a quarter-wavelength plate (54) which is configured to convert a pulsed laser beam (LB) passing through the main polarization beam splitter (53) from P-polarized light into circularly polarized light; a photoelastic modulation element (55) which is configured to modulate a pulsed laser beam passing through the quarter-wavelength plate (54) into a P-polarized pulsed laser beam and an S-polarized pulsed laser beam; a frequency setting device (730a) which is configured to set a modulation frequency by means of the photoelastic modulation element (55); a subpolarization beam splitter (56) configured to split the P-polarized pulsed laser beam and the S-polarized pulsed laser beam, which are modulated by the photoelastic modulation element (55); a first reversing means (6a; 7a; 57a) for reversing the pulsed laser beam diverted from the P-polarized light by the subpolarization beam splitter (56) to cause the pulsed laser beam to move in the reverse direction thereafter along an optical path of a return path of the pulsed laser beam which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam; a second reversing means (6b; 7b; 57b) for reversing the pulsed laser beam diverted from the S-polarized light by the subpolarization beam splitter (56) to cause the pulsed laser beam to subsequently travel in the reverse direction along an optical path of a return path of the pulsed laser beam which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam; and a condenser (580; 580a) arranged in paths of the pulsed laser beams reflected by the main polarization beam splitter (53), after the pulsed laser beams inverted by the first inversion means (6a; 7a; 57a) and the second inversion means (6b; 7b; 57b) pass through the quarter-wavelength plate (54), whereupon the pulsed laser beams are converted into S-polarized pulsed laser beams. [2] Laser processing device (1) according to claim 1, in which, when the predetermined repetition frequency of the pulsed laser beam oscillated by the pulsed laser oscillator (51) is H Hz, the frequency setting device (550) sets a power frequency to be supplied to the photoelastic modulation element (55) to H / 2 Hz, and the pulsed laser beam (LB), which is oscillated by the pulsed laser oscillator (51) with a maximum amplitude and a minimum amplitude, is modulated by the photoelastic modulation element (55) into a pulsed laser beam of P-polarized light and a pulsed laser beam of S-polarized light. [3] Laser processing device (1) according to claim 1 or 2, wherein the first reversing means (6a; 57a) has an angle-adjustable first mirror (571a) and the second reversing means (6b; 57b) has an angle-adjustable second mirror (571b). [4] Laser processing device (1) according to one of claims 1 to 3, wherein the first reversing means (6a) comprises: a first photoelastic modulation element (61a) which is configured to modulate the pulsed laser beam diverted from the P-polarized light by the subpolarization beam splitter (56) into a pulsed laser beam of P-polarized light and a pulsed laser beam of S-polarized light; a first frequency setting device (610a) configured to set a modulation frequency by means of the first photoelastic modulation element (61a); a first polarization beam splitter (62a) configured to split the P-polarized pulsed laser beam and the S-polarized pulsed laser beam, which are modulated by the first photoelastic modulation element (61a); a first mirror (63a) configured to reverse the pulsed laser beam diverted from the P-polarized light by the first polarization beam splitter (62a) to cause the pulsed laser beam to subsequently travel in the reverse direction along an optical path of a return path of the pulsed laser beam, which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam; and a second mirror (63b) configured to reverse the pulsed laser beam diverted from the S-polarized light by the first polarization beam splitter (62a) to cause the pulsed laser beam to subsequently travel in the reverse direction along an optical path of a return path of the pulsed laser beam, which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam; and where the second reversal agent (6b) exhibits: a second photoelastic modulation element (61b) which is configured to modulate the pulsed laser beam diverted from the S-polarized light by the subpolarization beam splitter (56) into a pulsed laser beam of P-polarized light and a pulsed laser beam of S-polarized light; a second frequency setting device (610b) configured to set a modulation frequency by means of the second photoelastic modulation element (61b); a second polarization beam splitter (62b) configured to split the pulsed laser beam from the P-polarized light and the pulsed laser beam from the S-polarized light modulated by the second photoelastic modulation element (61b); a third mirror (63b) configured to reverse the pulsed laser beam diverted from the P-polarized light by the second polarization beam splitter (62b) to cause the pulsed laser beam to subsequently travel in the reverse direction along an optical path of a return path of the pulsed laser beam, which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam; and a fourth mirror (64b) which is configured to reverse the pulsed laser beam diverted from the S-polarized light by the second polarization beam splitter (62b) in order to cause the pulsed laser beam to travel in the reverse direction along an optical path of a return path of the pulsed laser beam which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam. [5] Laser processing device (1) according to claim 4, wherein the first frequency setting device (610a) setting the first reversing means (6a) sets a power frequency to be supplied to the first photoelastic modulation element (61a) to H / 4 Hz; the first photoelastic modulation element (61a) modulates the pulsed laser beam from the P-polarized light, which is branched off by the subpolarization beam splitter (56) with a maximum amplitude and a minimum amplitude, into a pulsed laser beam of P-polarized light and a pulsed laser beam of S-polarized light; the second frequency setting device (610b), which sets the second reversing device (6b), sets a power frequency to be supplied to the second photoelastic modulating element (61b) to H / 4 Hz; and the second photoelastic modulation element (61b) modulates the pulsed laser beam from the S-polarized light, which is branched off by the subpolarization beam splitter (56) with a maximum amplitude and a minimum amplitude, into a pulsed laser beam of P-polarized light and a pulsed laser beam of S-polarized light. [6] Laser processing device (1) according to any one of claims 1 to 5, wherein the first reversing means (7a) comprises: a first resonance scanner (73a) which is set up to distribute the pulsed laser beam diverted from the P-polarized light by the subpolarization beam splitter (56) onto a first path and a second path; a first frequency setting device (730a) configured to set a distribution frequency of the first resonance scanner (73a); an angle-adjustable first mirror (74a) arranged in the first path and configured to reverse the pulsed laser beam distributed by the first resonance scanner (73a) from the P-polarized light, in order to cause the pulsed laser beam to subsequently travel along an optical path of a return path of the pulsed laser beam, which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam; and an angle-adjustable second mirror (75a) arranged in the second path and configured to reverse the pulsed laser beam distributed from the P-polarized light by the first resonance scanner (73a) to cause the pulsed laser beam to subsequently travel along an optical path of a return path of the pulsed laser beam, which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam; and where the second reversal agent (7b) exhibits: a second resonance scanner (73b) which is set up to distribute the pulsed laser beam diverted from the S-polarized light by the subpolarization beam splitter (56) onto a third path and a fourth path; a second frequency setting device (730b) configured to set a distribution frequency of the second resonance scanner (73b); an angle-adjustable third mirror (74b) arranged in the third path and configured to reverse the pulsed laser beam distributed by the second resonance scanner (73b) from the S-polarized light, in order to cause the pulsed laser beam to subsequently travel along an optical path of a return path of the pulsed laser beam, which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam; and an angle-adjustable fourth mirror (75b) which is arranged in the fourth path and is configured to reverse the pulsed laser beam distributed by the second resonance scanner (73b) from the S-polarized light in order to cause the pulsed laser beam to travel along an optical path of a return path of the pulsed laser beam which is slightly inclined with respect to an optical path of a forward path of the pulsed laser beam. [7] Laser processing device (1) according to claim 6, wherein the first frequency setting device (730a) setting the first reversing means (7a) sets a power frequency to be supplied to the first resonance scanner (73a) to H / 4 Hz; the first resonance scanner (73a) distributes the pulsed laser beam from the P-polarized light, which is branched off by the subpolarization beam splitter (56) with a maximum amplitude and a minimum amplitude, to the first path and the second path; the second frequency setting device (730b), which sets the second reversing device (7b), sets a power frequency to be supplied to the second resonance scanner (73b) to H / 4 Hz; and the second resonance scanner (73b) distributes the pulsed laser beam from the S-polarized light, which is branched off by the subpolarization beam splitter (56) with a maximum amplitude and a minimum amplitude, to the third path and the fourth path.

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