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WO2024176797A1 - Appareil de traitement laser - Google Patents

Appareil de traitement laser Download PDF

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Publication number
WO2024176797A1
WO2024176797A1 PCT/JP2024/003732 JP2024003732W WO2024176797A1 WO 2024176797 A1 WO2024176797 A1 WO 2024176797A1 JP 2024003732 W JP2024003732 W JP 2024003732W WO 2024176797 A1 WO2024176797 A1 WO 2024176797A1
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WO
WIPO (PCT)
Prior art keywords
order light
angle
acousto
zeroth
light
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/JP2024/003732
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English (en)
Japanese (ja)
Inventor
信高 小林
寛之 鈴木
靖弘 滝川
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mitsubishi Electric Corp
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Mitsubishi Electric Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mitsubishi Electric Corp filed Critical Mitsubishi Electric Corp
Priority to JP2025502234A priority Critical patent/JPWO2024176797A1/ja
Priority to TW113105612A priority patent/TWI893654B/zh
Publication of WO2024176797A1 publication Critical patent/WO2024176797A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/08—Devices involving relative movement between laser beam and workpiece
    • B23K26/082—Scanning systems, i.e. devices involving movement of the laser beam relative to the laser head
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/29—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the position or the direction of light beams, i.e. deflection
    • G02F1/33—Acousto-optical deflection devices

Definitions

  • This disclosure relates to a laser processing device that processes a workpiece by irradiating the workpiece with a laser beam.
  • laser processing devices equipped with a laser oscillator, a galvanometer, a focusing lens, and a table are known.
  • a laser beam emitted from the laser oscillator is reflected by the galvanometer's galvanometer mirror, and then irradiated onto the workpiece by the focusing lens, thereby processing the workpiece held on the table. Since the area in which the workpiece can be scanned by the galvanometer, i.e., the scan area, is limited to a few tens of mm square, the entire area of the workpiece is processed by moving the table holding the workpiece to switch the scan area.
  • Galvanometers have the advantage of a narrow scan area but a fast operating speed.
  • tables have the advantage of a slower operating speed than galvanometers, but a wider range of movement than the galvanometer's scan area.
  • an acousto-optical element is placed between the laser oscillator and the galvanometer on the optical path of the laser beam, and the acousto-optical element, galvanometer, and table are combined to change the irradiation position of the laser beam on the workpiece.
  • the acousto-optical element has a narrower scanning area than the scanning area of the galvanometer and the movement range of the table, but has the characteristic of being faster in operation than the galvanometer and the table.
  • the diffraction efficiency of an acousto-optical element is 80% to 90%.
  • a laser beam is incident on an acousto-optical element, in addition to the first-order light, zeroth-order light and second-order light also exit the acousto-optical element. If the zeroth-order light and second-order light reach the surface of the workpiece, undesired parts of the workpiece will be processed, resulting in defective processing of the workpiece.
  • Patent Document 1 discloses a method for blocking the zero-order light emitted from the acousto-optical element with a blocking plate.
  • the angular difference between the zeroth-order light and the first-order light emitted from the acousto-optical element is usually about 10 mrad to 100 mrad, and in order to block only the zeroth-order light using the method disclosed in Patent Document 1, the blocking plate needs to be placed about 1 m away from the acousto-optical element. This causes problems in that the laser processing device becomes larger and the optical path becomes longer.
  • the present disclosure has been made in consideration of the above, and aims to obtain a laser processing device that can suppress processing defects on the workpiece caused by the zero-order light and second-order light emitted from the acousto-optical element, while suppressing increases in size of the laser processing device and lengthening of the optical path compared to conventional devices.
  • the laser processing apparatus includes a laser oscillator that emits a laser beam, an acousto-optical element that diffracts the laser beam emitted from the laser oscillator, and an angle filter that separates at least one of zero-order light and second-order light from the laser beam emitted from the acousto-optical element and the first-order light.
  • the angle filter is configured so that the transmission rate of the first-order light passing through the angle filter is higher than at least one of the transmission rate of the zero-order light passing through the angle filter and the transmission rate of the second-order light passing through the angle filter.
  • the laser processing device disclosed herein has the advantage of being able to suppress processing defects in the workpiece caused by the zero-order light and second-order light emitted from the acousto-optical element, while suppressing increases in the size of the laser processing device and the length of the optical path compared to conventional devices.
  • FIG. 1 is a perspective view showing a laser processing apparatus according to a first embodiment
  • FIG. 1 is a diagram for explaining the operation of the angle filter according to the first embodiment
  • FIG. 13 is a diagram showing the relationship between the incident angle of a laser beam and the diffraction efficiency in the angle filter of the first embodiment.
  • FIG. 1 is a perspective view showing an example of a method for absorbing zero-order light and second-order light emitted from an acousto-optical element.
  • FIG. 13 is a diagram for explaining the operation of an angle filter according to a modification of the first embodiment;
  • FIG. 13 is a perspective view showing a laser processing apparatus according to a second embodiment.
  • FIG. 13 is a perspective view showing an angle filter according to a second embodiment;
  • FIG. 13 is a cross-sectional view of the angle filter for explaining the operation of the angle filter according to the second embodiment;
  • FIG. 13 is a perspective view showing an angle filter according to a first modified example of the second embodiment;
  • FIG. 13 is a perspective view showing an angle filter according to a second modification of the second embodiment;
  • FIG. 13 is a perspective view showing a laser processing apparatus according to a third embodiment.
  • 11 is a cross-sectional view of an angle filter according to a third embodiment of the present invention;
  • FIG. 11 is an angle characteristic diagram showing the relationship between the incident angle and the transmittance of the angle filter of the third embodiment at the wavelength of the laser beam when the gap is appropriately set.
  • FIG. 16 is a transmission spectrum diagram showing the relationship between wavelength and transmittance of the angle filter of the third embodiment at the incident angle of the transmission peak of the first-order light shown in FIG.
  • FIG. 13 is a perspective view showing a laser processing apparatus according to a fourth embodiment.
  • FIG. 13 is a diagram for explaining the operation of the angle filter according to the fourth embodiment.
  • FIG. 11 is an angle characteristic diagram showing the relationship between the angle of incidence on the wave plate of the angle filter of the fourth embodiment and the transmittance at the wavelength of the laser beam when the thickness of the wave plate is appropriately set.
  • FIG. 22 is a transmission spectrum diagram showing the relationship between wavelength and transmittance of the angle filter of the fourth embodiment at the incident angle of the transmission peak of the first-order light shown in FIG.
  • FIG. 1 is a perspective view showing a laser processing device 1 according to a first embodiment.
  • the laser processing device 1 is a device that processes a workpiece 11 by irradiating the workpiece 11 with a laser beam r.
  • the processing includes, for example, drilling and marking.
  • the workpiece 11 is, for example, a substrate.
  • the laser processing device 1 includes a laser oscillator 2, a mirror 3, a plurality of acousto-optical elements 4, a plurality of half-wave plates 5, a plurality of angle filters 6, a plurality of dampers 7, a plurality of galvanometers 8, a condenser lens 9, and a table 10.
  • the laser processing device 1 also includes a plurality of mirrors (not shown).
  • the laser beam r emitted from the laser oscillator 2 is reflected by the mirror 3 and passes through the acousto-optical element 4, the half-wave plate 5, and the angle filter 6.
  • the laser beam r is then reflected by the galvanometer 8, positioned on the workpiece 11 by the focusing lens 9, and irradiated onto the workpiece 11.
  • the workpiece 11 irradiated with the laser beam r is burned, melted, or sublimated.
  • the workpiece 11 is subjected to processing such as drilling and marking.
  • the X-axis direction, Y-axis direction, and Z-axis direction shown in FIG. 1 are used.
  • the X-axis direction and the Y-axis direction shown in FIG. 1 are parallel to the horizontal direction and perpendicular to each other.
  • the Z-axis direction shown in FIG. 1 is a vertical direction perpendicular to the X-axis direction and the Y-axis direction.
  • the laser oscillator 2 serves to emit a laser beam r.
  • the mirror 3 serves to reflect the laser beam r emitted from the laser oscillator 2 toward the acousto-optical element 4.
  • the acousto-optical element 4 diffracts the laser beam r emitted from the laser oscillator 2 to emit a first-order light.
  • the acousto-optical element 4 is a diffraction grating that changes the diffraction direction of the laser beam r.
  • a refractive index change occurs due to compression waves inside the transparent material that transmits the laser beam r.
  • the diffraction direction of the laser beam r can be changed by modulating the frequency of the ultrasonic waves applied to the acousto-optical element 4.
  • the acousto-optical element 4 also emits undesired zero-order light and second-order light in addition to the first-order light.
  • the transparent material is, for example, a glass material such as germanium, quartz, or synthetic quartz.
  • the number of acousto-optical elements 4 is two.
  • the two acousto-optical elements 4 are arranged at an interval from each other on the optical path of the laser beam r. In the following description, when the two acousto-optical elements 4 are to be distinguished from each other, they are referred to as acousto-optical element 4a and acousto-optical element 4b.
  • the acousto-optical element 4a diffracts the laser beam r emitted from the laser oscillator 2 when ultrasonic waves are applied.
  • the acousto-optical element 4a changes the irradiation position of the laser beam r on the workpiece 11 in the X-axis direction.
  • the acousto-optical element 4b diffracts the laser beam r emitted from the acousto-optical element 4a when ultrasonic waves are applied.
  • the acousto-optical element 4b changes the irradiation position of the laser beam r on the workpiece 11 in the Y-axis direction.
  • the laser processing device 1 can change the irradiation position of the laser beam r on the workpiece 11 in the X-axis direction and the Y-axis direction using the two acousto-optical elements 4a and 4b.
  • the laser processing device 1 can scan an area of 0.1 mm to several mm square on the workpiece 11 at a speed of several hundred m/s using the two acousto-optical elements 4a and 4b.
  • the half-wave plate 5 serves to rotate the polarization direction of the laser beam r emitted from the acousto-optical element 4 or the angle filter 6 by 90 degrees around the optical axis of the laser beam r.
  • the material of the half-wave plate 5 may be a birefringent material.
  • the birefringent material is, for example, quartz.
  • the number of half-wave plates 5 is two in this embodiment. In the following description, when the two half-wave plates 5 are to be distinguished, they are referred to as the half-wave plate 5a and the half-wave plate 5b.
  • the half-wave plate 5a is disposed between the multiple acousto-optical elements 4a and 4b.
  • the half-wave plate 5a serves to rotate the polarization direction of the laser beam r emitted from the acousto-optical element 4a by 90 degrees around the optical axis of the laser beam r.
  • the half-wave plate 5b is disposed between the multiple angle filters 6a and 6b.
  • the half-wave plate 5b serves to rotate the polarization direction of the laser beam r emitted from the angle filter 6a by 90 degrees around the optical axis of the laser beam r.
  • the angle filter 6 plays a role in separating the desired laser beam r, which is the first-order light, from the undesired zero-order light and second-order light, among the laser beam r emitted from the acousto-optical element 4.
  • the number of angle filters 6 is two.
  • the two angle filters 6 are arranged at an interval on the optical path of the laser beam r.
  • angle filters 6a and 6b when the two angle filters 6 are to be distinguished, they are referred to as angle filters 6a and 6b.
  • the angle filter 6a diffracts the first-order light of the laser beam r emitted from the acousto-optical element 4a.
  • the zero-order light and the second-order light pass through the angle filter 6a as they are without being diffracted by the angle filter 6a.
  • the first-order light emitted from the angle filter 6a passes through the half-wave plate 5b and enters the angle filter 6b.
  • the angle filter 6b diffracts the first-order light emitted from the acousto-optical element 4b.
  • the zero-order light and the second-order light pass through the angle filter 6b as they are without being diffracted by the angle filter 6b. Details of the angle filter 6 will be described later.
  • the damper 7 serves to absorb the zeroth and second order light of the laser beam r emitted from the acousto-optical element 4.
  • damper 7a and damper 7b are disposed near the angle filter 6a and absorbs the zeroth and second order light of the laser beam r emitted from the acousto-optical element 4a.
  • the damper 7b is disposed near the angle filter 6b and absorbs the zeroth and second order light of the laser beam r emitted from the acousto-optical element 4b.
  • the galvanometer 8 serves to reflect the laser beam r emitted from the angle filter 6.
  • the two galvanometers 8 are arranged at an interval on the optical path of the laser beam r.
  • galvanometer 8a and galvanometer 8b when the two galvanometers 8 need to be distinguished, they are referred to as galvanometer 8a and galvanometer 8b.
  • the galvanometer 8 has a galvanometer mirror 8c that reflects the laser beam r, and a galvanometer motor 8d that rotates the galvanometer mirror 8c.
  • the galvanometer 8a rotates the galvanometer mirror 8c within a specific range of oscillation angles to change the irradiation position of the laser beam r on the workpiece 11 in the X-axis direction.
  • the galvanometer 8b rotates the galvanometer mirror 8c within a specific range of oscillation angles to change the irradiation position of the laser beam r on the workpiece 11 in the Y-axis direction.
  • the laser processing device 1 can change the irradiation position of the laser beam r on the workpiece 11 in the X-axis direction and the Y-axis direction using the two galvanometers 8a and 8b.
  • the laser processing device 1 can scan an area of several tens of mm square on the workpiece 11 at a speed of several m/s using the two galvanometers 8a and 8b.
  • the focusing lens 9 focuses the laser beam r reflected by the galvanometer 8 and irradiates it onto the workpiece 11.
  • the focusing lens 9 is an f ⁇ lens.
  • the focusing lens 9 irradiates the focused laser beam r vertically onto the workpiece 11.
  • the table 10 holds the workpiece 11 and also plays a role in moving the position of the workpiece 11.
  • the table 10 holds the workpiece 11 by, for example, adsorbing the workpiece 11.
  • the table 10 is movable in the X-axis direction and the Y-axis direction, and can move the workpiece 11 in the X-axis direction and the Y-axis direction.
  • the table 10 has a drive mechanism and a guide mechanism (not shown).
  • the drive mechanism is, for example, a ball screw.
  • the guide mechanism is, for example, an LM Guide (registered trademark).
  • the laser processing device 1 can change the irradiation position of the laser beam r on the workpiece 11 in the X-axis direction and the Y-axis direction by using the table 10.
  • the laser processing device 1 can scan an area of several hundred mm by several hundred mm square on the workpiece 11 at a speed of about 1 m/s by using the table 10.
  • the table 10 may be movable in only one of the X-axis direction and the Y-axis direction.
  • the laser processing device 1 can change the irradiation position of the laser beam r on the workpiece 11 by using the acousto-optical element 4, the galvanometer 8, and the table 10.
  • the acousto-optical element 4, the galvanometer 8, and the table 10 constitute a beam scanning mechanism that changes the irradiation position of the laser beam r on the workpiece 11.
  • the acousto-optical element 4 has a narrower scan area than the scan area of the galvanometer 8 and the movement range of the table 10, but has a faster operating speed than the galvanometer 8 and the table 10.
  • the galvanometer 8 has a wider scan area than the scan area of the acousto-optical element 4 and a narrower scan area than the movement range of the table 10, but has a slower operating speed than the acousto-optical element 4 and a faster operating speed than the table 10.
  • the table 10 has a slower operating speed than the acousto-optical element 4 and the galvanometer 8, but has a wider movement range than the scan area of the acousto-optical element 4 and the galvanometer 8.
  • Figure 2 is a diagram for explaining the function of the angle filter 6 of embodiment 1.
  • Figure 3 is an enlarged view of part A shown in Figure 2.
  • the angle filter 6 is a transmission type diffraction grating that transmits the incident laser beam r to generate diffracted light. More specifically, the angle filter 6 is a transmission type diffraction grating that diffracts the first-order light rp so that the angular difference between the zeroth-order light ro and the first-order light rp emitted from the acousto-optical element 4 becomes large when the zeroth-order light ro and the first-order light rp pass through the angle filter 6, and so that the angular difference between the first-order light rp and the second-order light rq emitted from the acousto-optical element 4 becomes large when the first-order light rp and the second-order light rq pass through the angle filter 6.
  • the angle filter 6 is a blazed diffraction grating that can obtain maximum diffraction efficiency for the diffracted light of the first-order light rp.
  • a diffraction grating is designed with the direction of incidence of the laser beam incident on the diffraction grating and the direction of emission of the first-order light emitted from the diffraction grating set to specific directions, it is possible to achieve a diffraction efficiency of 95% or more for the first-order light. It is also possible to make the angular difference between the zeroth-order light and the first-order light emitted from the diffraction grating large, for example, 10 degrees or more.
  • the angular difference between the zeroth-order light ro and the first-order light rp emitted from the acousto-optical element 4, and the angular difference between the first-order light rp and the second-order light rq, are generally 0.1 degrees to several degrees.
  • the zero-order light ro and the second-order light rq emitted from the acousto-optical element 4 pass through the angle filter 6, the zero-order light ro and the second-order light rq pass through as is without being diffracted, and when the first-order light rp emitted from the acousto-optical element 4 passes through the angle filter 6, it is diffracted, so that the angular difference between the zero-order light ro and the first-order light rp, and the angular difference between the first-order light rp and the second-order light rq can be increased.
  • the angle filter 6 is a plate-shaped member.
  • the direction perpendicular to the thickness direction of the angle filter 6 shown in FIG. 3 is referred to as the vertical direction.
  • the line along the vertical direction passing through the center of the thickness direction of the angle filter 6 is referred to as the center line C.
  • the angle filter 6 includes a surface 6c on which the laser beam r is incident and a back surface 6d from which the laser beam r is emitted.
  • the surface 6c is one surface of the angle filter 6 in the thickness direction.
  • the back surface 6d is the other surface of the angle filter 6 in the thickness direction.
  • the surface 6c and the back surface 6d of the angle filter 6 are assumed to be linearly symmetrical with respect to the center line C.
  • the surface 6c and the back surface 6d are provided with a lattice pattern 6e at regular intervals. That is, a plurality of grooves 6f forming the lattice pattern 6e are engraved on each of the surface 6c and the back surface 6d.
  • the groove 6f is composed of a step surface 6g and a blazed surface 6h.
  • the step surface 6g extends in the plate thickness direction.
  • the blazed surface 6h is inclined so as to approach the center line C as it extends vertically from the tip of the step surface 6g.
  • the period T which is the vertical distance of the groove 6f, is constant.
  • the shapes of the front surface 6c and back surface 6d of the angle filter 6 are such that only the first-order light rp can be diffracted, but the zeroth-order light ro and the second-order light rq cannot be diffracted.
  • the zeroth-order light ro and the second-order light rq are emitted from the back surface 6d at the same angle as they were incident on the front surface 6c.
  • the action of the angle filter 6 of the first embodiment will be described.
  • the zeroth light ro, the first light rp, and the second light rq are incident on the same blaze surface 6i on the surface 6c of the angle filter 6.
  • the zeroth light ro, the first light rp, and the second light rq are each drawn with a single line.
  • the zeroth light ro, the first light rp, and the second light rq are laser beams that are wider than the vertical length of one blaze surface 6h, so the zeroth light ro, the first light rp, and the second light rq are incident on multiple blaze surfaces 6h.
  • FIG. 3 the zeroth light ro, the first light rp, and the second light rq are incident on multiple blaze surfaces 6h.
  • the blaze surface 6h on the back surface 6d that faces the blaze surface 6i in the plate thickness direction is called the blaze surface 6j.
  • the blaze surface 6h that is located next to the blaze surface 6j on one side of the vertical direction of the blaze surface 6j is called the blaze surface 6k.
  • the blaze surface 6h located next to the blaze surface 6j on the other side of the perpendicular direction of the blaze surface 6j is called the blaze surface 6m.
  • the first-order light rp is refracted by blaze surface 6i and travels only to blaze surface 6j.
  • the zeroth-order light ro is refracted by blaze surface 6i and travels to blaze surface 6j and blaze surface 6k.
  • the second-order light rq is refracted by blaze surface 6i and travels to blaze surface 6j and blaze surface 6m.
  • the wavefront of the zeroth-order light ro travels to both blaze surface 6j and blaze surface 6k
  • the wavefront is offset by the phase difference between blaze surfaces 6j, 6k, i.e., the path difference between blaze surfaces 6j, 6k, and the diffraction efficiency of the zeroth-order light ro is reduced to approximately 0%.
  • the wavefront of the second-order light rq travels to both the blaze surface 6j and the blaze surface 6m
  • the wavefront is offset by the phase difference between the blaze surfaces 6j and 6m, i.e., the path difference between the blaze surfaces 6j and 6m, and the diffraction efficiency of the second-order light rq is suppressed to approximately 0%.
  • the zeroth-order light ro and the second-order light rq emitted from the acousto-optical element 4 are not diffracted by the angle filter 6 and are emitted from the back surface 6d at the same angle at which they were incident on the front surface 6c.
  • the first-order light rp travels only to the blaze surface 6j and does not travel to the blaze surfaces 6k and 6m, so the first-order light rp is diffracted with high diffraction efficiency. Only the first-order light rp emitted from the acousto-optical element 4 is diffracted by the angle filter 6.
  • the thickness of the angle filter 6 is d
  • the refractive index of the angle filter 6 is n
  • the period which is the vertical distance of the grooves 6f is T
  • the angular difference between the zeroth-order light ro and the first-order light rp emitted from the acousto-optical element 4 and the angular difference between the first-order light rp and the second-order light rq emitted from the acousto-optical element 4 are ⁇ , respectively.
  • FIG. 4 shows the relationship between the angle of incidence of the laser beam r and the diffraction efficiency in the angle filter 6 of the first embodiment.
  • FIG. 4 also shows the angles of incidence of the zeroth-order light ro, the first-order light rp, and the second-order light rq emitted from the acousto-optical element 4. Since the acousto-optical element 4 is a diffraction grating with a variable diffraction direction, the angles of incidence of the first-order light rp and the second-order light rq have an angular range. As is clear from FIG.
  • the diffraction efficiency of the first-order light rp is higher than that of the zeroth-order light ro and the second-order light rq. In other words, the diffraction efficiency of the zeroth-order light ro and the second-order light rq is kept low compared to that of the first-order light rp.
  • FIG. 5 is a perspective view showing an example of a method for absorbing the zeroth light ro and the second light rq emitted from the acousto-optical element 4.
  • the laser processing device 1B is equipped with a Keplerian afocal lens 12 arranged between the acousto-optical element 4 and the galvanometer 8.
  • the afocal lens 12 has a pair of convex lenses 13, 14 and a damper 15 arranged between the pair of convex lenses 13, 14.
  • the damper 15 has an opening 15a.
  • the zeroth light ro, the first light rp, and the second light rq emitted from the acousto-optical element 4 are once narrowed by the convex lens 13, and only the first light rp passes through the damper 15 through the opening 15a in the narrowed portion.
  • the zeroth light ro and the second light rq are absorbed by the damper 15.
  • the opening 15a in order to prevent the zeroth-order light ro and the second-order light rq from processing the opening 15a, the opening 15a must be shifted in the optical axis direction from the focal point P of the zeroth-order light ro and the focal point P of the second-order light rq, and the zeroth-order light ro, the first-order light rp, and the second-order light rq must be separated from each other by several mm in order to prevent the zeroth-order light ro and the second-order light rq from passing through the opening 15a.
  • another technique is to separate the acousto-optical element from the galvanometer so that the zeroth-order and second-order light emitted from the acousto-optical element misses the galvanometer mirror of the galvanometer, thereby reflecting only the first-order light towards the focusing lens.
  • the angular difference between the zeroth-order and first-order light emitted from the acousto-optical element and the angular difference between the first-order and second-order light are usually about 0.1 degrees to a few degrees, and in order to use this method to cause the zeroth-order and second-order light emitted from the acousto-optical element to miss the galvanometer mirror of the galvanometer, it is necessary to separate the acousto-optical element from the galvanometer by about 1 m. This poses the problem of increasing the size of the laser processing device and the length of the optical path.
  • the laser processing device 1 is provided with an angle filter 6 that separates the zeroth light ro and the second light rq from the first light rp of the laser beam r emitted from the acousto-optical element 4.
  • the angle filter 6 is a transmission type diffraction grating that diffracts the first light rp so that the angle difference between the zeroth light ro and the first light rp when the zeroth light ro and the first light rp emitted from the acousto-optical element 4 pass through the angle filter 6 is large, and the angle difference between the first light rp and the second light rq when the first light rp and the second light rq emitted from the acousto-optical element 4 pass through the angle filter 6 is large.
  • the first light rp is separated from the zeroth light ro and the second light rq, and only the first light rp required for processing the workpiece 11 is guided toward the workpiece 11, and the zeroth light ro and the second light rq unnecessary for processing the workpiece 11 can be cut. Therefore, the processing defects of the workpiece 11 caused by the zeroth light ro and the second light rq emitted from the acousto-optical element 4 are suppressed, and a high-quality workpiece 11 is obtained.
  • the angle filter 6 when the zeroth light ro, the first light rp, and the second light rq emitted from the acousto-optical element 4 pass through the angle filter 6, the angle difference between the zeroth light ro and the first light rp, and the angle difference between the first light rp and the second light rq are widened, so that the first light rp can be separated from the zeroth light ro and the second light rq at a shorter distance than the above-mentioned technology.
  • This makes it possible to suppress the increase in size of the laser processing device 1 and the lengthening of the optical path, so that the accuracy of the processing position against environmental changes such as temperature is stabilized. Therefore, in this embodiment, high-speed processing by the beam scanning mechanism composed of the acousto-optical element 4, the galvanometer 8, and the table 10 can be realized with high quality and high precision.
  • the laser processing device 1 is provided with a damper 7 that absorbs the zeroth-order light ro and the second-order light rq of the laser beam r emitted from the acousto-optical element 4.
  • a damper 7 that absorbs the zeroth-order light ro and the second-order light rq of the laser beam r emitted from the acousto-optical element 4.
  • the damper 7a is disposed near the angle filter 6a, so that the zeroth-order light ro and the second-order light rq emitted from the acousto-optical element 4a are absorbed by the damper 7a.
  • the damper 7b is disposed near the angle filter 6b, so that the zeroth-order light ro and the second-order light rq emitted from the acousto-optical element 4b are absorbed by the damper 7b.
  • the damper 7 may be disposed, for example, at a distance of several tens of mm from the angle filter 6.
  • the damper 7 By disposing the damper 7 in this manner, the zeroth-order light ro and the second-order light rq that have passed through the angle filter 6 are absorbed by the damper 7, so that the increase in size of the laser processing apparatus 1 and the lengthening of the optical path caused by disposing the damper 7 can be suppressed.
  • the diffraction direction of the laser beam r by the acousto-optical elements 4 can be set in two directions, the X-axis direction and the Y-axis direction, and the irradiation position of the laser beam r on the workpiece 11 can be changed in the X-axis direction and the Y-axis direction.
  • the laser processing device 1 is equipped with a half-wave plate 5b arranged between multiple angle filters 6a, 6b.
  • the polarization direction of the primary light rp emitted from the angle filter 6a can be rotated 90 degrees around the optical axis of the laser beam r.
  • the diffraction efficiency of the TE wave i.e., S-polarized light, is higher.
  • the diffraction efficiency of the primary light rp in the angle filter 6b can be increased, and primary light rp with higher energy can be guided toward the workpiece 11.
  • the laser processing device 1 includes a half-wave plate 5a disposed between multiple acousto-optical elements 4a and 4b.
  • the polarization direction of the primary light rp emitted from the acousto-optical element 4a can be rotated by 90 degrees around the optical axis of the laser beam r.
  • the diffraction efficiency of the TE wave i.e., S-polarized light, is higher.
  • the diffraction efficiency of the primary light rp in the acousto-optical element 4b can be increased, and primary light rp with higher energy can be guided toward the workpiece 11.
  • the angular filter 6 only needs to be able to separate at least one of the zeroth-order light ro and the second-order light rq from the first-order light rp of the laser beam r emitted from the acousto-optical element 4.
  • the angular filter 6 only needs to be a transmission type diffraction grating that diffracts the first-order light rp so that the angle difference between the zeroth-order light ro and the second-order light rq and the first-order light rp becomes large when the first-order light rp and at least one of the zeroth-order light ro and the second-order light rq emitted from the acousto-optical element 4 pass through the angular filter 6.
  • the front surface 6c and the back surface 6d of the angle filter 6 shown in FIG. 3 are symmetrical with respect to the center line C, but they may be non-symmetrical with respect to the center line C as long as the periods T of the front surface 6c and the back surface 6d are the same.
  • the lattice pattern 6e on the front surface 6c and the lattice pattern 6e on the back surface 6d may be shifted from each other in the vertical direction of the paper in FIG. 3.
  • angles of incidence of the zeroth-order light ro, the first-order light rp, and the second-order light rq such that only the first-order light rp is diffracted by the angle filter 6, and the zeroth-order light ro and the second-order light rq are not diffracted by the angle filter 6 and are emitted from the back surface 6d at the same angle at which they were incident on the front surface 6c.
  • the angle filter 6 may be adjusted appropriately to obtain such angles of incidence.
  • the depth of the blaze surface 6h on the front surface 6c and the back surface 6d i.e., the length of the blaze surface 6h in the plate thickness direction, may be different from each other. Even in this case, as long as the lattice pattern 6e is provided on each of the front surface 6c and the back surface 6d, the same effect as in this embodiment can be achieved.
  • the number of acousto-optical elements 4, half-wave plates 5, angular filters 6, dampers 7, and galvanometers 8 is two, but it may be one or three or more. Also, the half-wave plate 5 may be omitted. Also, the arrangement of the angular filters 6a, 6b and dampers 7a, 7b is not limited to the example shown in the figure. For example, the angular filter 6a and damper 7a may be arranged after the acousto-optical element 4a, and the angular filter 6b and damper 7b may be arranged after the acousto-optical element 4b.
  • the angle filter 6 is a diagram for explaining the action of the angle filter 6 of the modified example of the first embodiment.
  • the angle filter 6 may be a volume phase holographic (VPH) type diffraction grating shown in FIG. 6.
  • the angle filter 6 is a diffraction grating having stripes with high refractive index and stripes with low refractive index in the vertical direction along the surface 6c.
  • d denotes the thickness of the portion of the angular filter 6 that is a stripe having a refractive index
  • n denotes the average value of the refractive index of the stripes with a high refractive index and the stripes with a low refractive index
  • T denotes the period that is the vertical distance between the stripes with a high refractive index and the stripes with a low refractive index
  • ⁇ denotes the angular difference between the zeroth-order light ro and the first-order light rp emitted from the acousto-optical element 4, and the angular difference between the first-order light rp and the second-order light rq emitted from the acousto-optical element 4.
  • Embodiment 2 Next, a laser processing apparatus 1A according to a second embodiment will be described with reference to Fig. 7 to Fig. 9.
  • the configuration of the angle filter 6 is different from that of the first embodiment.
  • the same reference numerals are used for the parts that overlap with those of the first embodiment, and the description thereof will be omitted.
  • FIG. 7 is a perspective view showing a laser processing device 1A according to the second embodiment.
  • the angle filter 6 is a plate-shaped element formed of a material that cannot transmit the laser beam r.
  • the angle filter 6 has a thickness along the optical axis direction of the laser beam r.
  • the outer shape of the angle filter 6 is not particularly limited, but is circular in this embodiment.
  • the material of the plate-shaped element is not particularly limited as long as it cannot transmit the wavelength of the laser beam r.
  • the material of the plate-shaped element may be, for example, metal, resin, glass, or semiconductor.
  • the angle filter 6 has a plurality of openings 6n formed therethrough in the plate thickness direction.
  • the half-wave plate 5 may be disposed between the plurality of acousto-optical elements 4a and 4b.
  • FIG. 8 is a perspective view showing the angle filter 6 according to the second embodiment.
  • the shape of the opening 6n when viewed along the penetration direction is circular.
  • the plurality of openings 6n are arranged side by side in a direction intersecting the optical axis direction of the laser beam r.
  • the plurality of openings 6n are arranged adjacent to each other.
  • FIG. 9 is a cross-sectional view of the angle filter 6, which is a diagram for explaining the operation of the angle filter 6 of the second embodiment.
  • the zeroth-order light ro, the first-order light rp, and the second-order light rq are incident on the same opening 6n on the surface 6c of the angle filter 6.
  • the zeroth-order light ro, the first-order light rp, and the second-order light rq are each drawn with a single line.
  • the zeroth-order light ro, the first-order light rp, and the second-order light rq are laser beams that are wider than the size D of one opening 6n, so the zeroth-order light ro, the first-order light rp, and the second-order light rq are incident on multiple openings 6n.
  • the angle filter 6 is configured so that the transmittance of the first-order light rp passing through the angle filter 6 is higher than at least one of the transmittance of the zeroth-order light ro passing through the angle filter 6 and the transmittance of the second-order light rq passing through the angle filter 6.
  • the angle filter 6 is an element arranged so that the transmission direction in which the laser beam r can pass through the angle filter 6 is parallel to the traveling direction of the first-order light rp, and so that the transmission direction intersects with the traveling direction of the zeroth-order light ro and the traveling direction of the second-order light rq.
  • the transmission direction is the penetration direction of the opening 6n.
  • the traveling direction of the first-order light rp and the penetration direction of the opening 6n are consistent.
  • the penetration direction of the opening 6n intersects with the traveling direction of the zeroth-order light ro and the traveling direction of the second-order light rq.
  • the penetration direction of the opening 6n is parallel to the traveling direction of the first-order light rp and the penetration direction of the opening 6n is intersected with the traveling direction of the zeroth-order light ro and the traveling direction of the second-order light rq, only the first-order light rp passes through the opening 6n, while the zeroth-order light ro and the second-order light rq are blocked by the inner wall surface of the opening 6n, and the zeroth-order light ro and the second-order light rq can be absorbed or scattered by the inner wall surface of the opening 6n.
  • the thickness of the angular filter 6 is d
  • the size of the opening 6n is D
  • the angular difference between the zeroth-order light ro and the first-order light rp emitted from the acousto-optical element 4 are ⁇ . d ⁇ D/ ⁇ ...(5)
  • the angle filter 6 is a plate-shaped element made of a material that cannot transmit the laser beam r, and the angle filter 6 has a plurality of openings 6n formed therein that penetrate in the plate thickness direction.
  • the shape of the opening 6n when viewed along the penetration direction is circular, so the angular filter 6 does not have directionality in the X-axis and Y-axis directions. Therefore, the angular filter 6 can cut the zeroth-order light ro and second-order light rq in the X-axis direction emitted from the acousto-optical element 4a, and can also cut the zeroth-order light ro and second-order light rq in the Y-axis direction emitted from the acousto-optical element 4b. Therefore, in this embodiment, at least one angular filter 6 after the acousto-optical element 4 is sufficient.
  • the damper 7 can be omitted because the zeroth-order light ro and second-order light rq are absorbed or scattered by the inner wall surface of the opening 6n.
  • FIG. 10 is a perspective view of the angle filter 6 according to the first modified example of the second embodiment.
  • FIG. 11 is a perspective view of the angle filter 6 according to the second modified example of the second embodiment.
  • the shape of the opening 6n when viewed along the penetration direction is circular in this embodiment, but may be other than circular.
  • the shape of the opening 6n when viewed along the penetration direction may be a triangle, a square as shown in FIG. 10, or a hexagon as shown in FIG. 11.
  • the shape of the opening 6n when viewed along the penetration direction may be an ellipse or a rectangle, but is preferably a circle or a regular polygon. In this way, the angle filter 6 can be made to have no directionality in the X-axis direction and the Y-axis direction.
  • the shape of the angle filter 6 becomes symmetrical in the X-axis direction and the Y-axis direction.
  • the size D of the opening 6n if the shape of the opening 6n when viewed along the penetration direction is circular, the diameter of the circle is taken as the size D of the opening 6n. If the shape of the opening 6n when viewed along the penetration direction is elliptical, the major axis of the ellipse is taken as the size D of the opening 6n. If the shape of the opening 6n when viewed along the penetration direction is polygonal, the diameter of the circumscribing circle of the polygon is taken as the size D of the opening 6n.
  • the angle filter 6 can be manufactured by, for example, machining, etching, or die-sinking electrical discharge machining. Alternatively, multiple thin plates with openings 6n formed by etching or other methods can be stacked together until the thickness reaches a predetermined thickness d, and the outer periphery of each plate can be clamped with screws or the plates can be joined by diffusion bonding, ultrasonic bonding, or the like.
  • the angular filter 6, which is a plate-shaped element, may be an element consisting of multiple circular tubes bundled together.
  • the axial direction of the circular tubes is parallel to the traveling direction of the primary light rp, and the axial direction of the circular tubes is intersected with the traveling direction of the zeroth-order light ro and the traveling direction of the secondary light rq.
  • the axial direction of the circular tubes is the transmission direction in which the laser beam r can pass through the angular filter 6.
  • the angular filter 6, which is a plate-shaped element, may be an element formed by bundling multiple fibers made of a material through which the laser beam r passes.
  • multiple glass fibers are bundled and sealed with resin or the like, and the sealed multiple glass fibers are cut in a direction perpendicular to the length of the glass fibers, and the cut surfaces are polished and then coated with an anti-reflection film to form an element that can be used as the angular filter 6.
  • the length direction of the fibers is parallel to the traveling direction of the primary light rp, and the length direction of the fibers is crossed with the traveling direction of the zeroth-order light ro and the traveling direction of the secondary light rq.
  • the length direction of the fibers is the transmission direction in which the laser beam r can pass through the angular filter 6.
  • the angle filter 6 only needs to be able to separate at least one of the zeroth-order light ro and the second-order light rq from the first-order light rp of the laser beam r emitted from the acousto-optical element 4. That is, the angle filter 6 is a plate-shaped element, and is arranged so that the transmission direction in which the laser beam r can pass through the angle filter 6 is parallel to the traveling direction of the first-order light rp, and the transmission direction intersects with at least one of the traveling directions of the zeroth-order light ro and the second-order light rq.
  • the angle filter 6 is configured so that the transmittance of the first-order light rp passing through the angle filter 6 is higher than at least one of the transmittance of the zeroth-order light ro passing through the angle filter 6 and the transmittance of the second-order light rq passing through the angle filter 6.
  • the number of acousto-optical elements 4, angular filters 6, and galvanometers 8 is not limited to the example shown in the figure and may be changed as appropriate.
  • Embodiment 3 Next, a laser processing apparatus 1C according to a third embodiment will be described with reference to Fig. 12 to Fig. 17.
  • the configuration of the angle filter 6 is different from that of the second embodiment.
  • the same reference numerals are used for the parts that overlap with those of the second embodiment, and the description thereof will be omitted.
  • FIG. 12 is a perspective view showing a laser processing apparatus 1C according to the third embodiment.
  • the angle filter 6 shown in FIG. 12 is an etalon.
  • the etalon is a wavelength filter that utilizes multiple interference of two opposing partial reflecting mirrors 6q.
  • the etalon has a periodic transmission spectrum and a sharp transmission peak with a narrow half-width.
  • the material of the etalon is not particularly limited as long as it can transmit the wavelength of the laser beam r.
  • the material of the etalon may be, for example, glass, quartz, or a semiconductor.
  • the etalon used as the angle filter 6 may be a solid etalon, but in this embodiment, it is an air gap etalon that has better angular characteristics than a solid etalon.
  • a solid etalon can be made of a metamaterial with a refractive index of 0.3 or less for the wavelength of the laser beam r, it is preferable to use a solid etalon as the angle filter 6 because more suitable angular characteristics can be obtained than with an air gap etalon.
  • the half-wave plate 5 may be disposed between the multiple acousto-optical elements 4a and 4b.
  • FIG. 13 is a cross-sectional view of the angle filter 6 of the third embodiment.
  • the angle filter 6 is configured so that the transmittance of the first-order light rp passing through the angle filter 6 is higher than the transmittance of the zeroth-order light ro passing through the angle filter 6 and the transmittance of the second-order light rq passing through the angle filter 6.
  • the angle filter 6 has two transparent members 6o, 6p facing each other across a gap G.
  • Each of the transparent members 6o, 6p has a flat plate shape.
  • the two transparent members 6o, 6p are arranged parallel to each other.
  • the surface of each of the transparent members 6o, 6p facing the gap G is a partial reflecting mirror 6q.
  • the laser beam r incident on the transparent member 6o of the angle filter 6 at an incident angle ⁇ passes through the transparent member 6o and enters the gap G, then undergoes multiple reflections between the two partial reflecting mirrors 6q, and is emitted from the transparent member 6p.
  • the angular filter 6 exhibits high transmittance.
  • the gap between the transparent members 6o and 6p is G
  • the incident angle of the laser beam r is ⁇
  • the wavelength of the laser beam r is ⁇
  • m is an integer (natural number) equal to or greater than 1.
  • the zeroth-order light ro, the first-order light rp, and the second-order light rq emitted from the acousto-optical element 4 have different exit angles and different incident angles ⁇ to the angle filter 6, so in this embodiment, only the incident angle ⁇ of the first-order light rp is adjusted to the transmission peak of the angle filter 6.
  • the design parameters of the etalon are the gap G and the reflectance of the partial reflector 6q. It is preferable that the reflectance of the partial reflector 6q is 50% or more.
  • FIG. 14 is an angle characteristic diagram showing the relationship between the incident angle ⁇ and the transmittance of the angle filter 6 of embodiment 3 at the wavelength ⁇ of the laser beam r when the gap G is appropriately set.
  • a wide range of angles of the incident angle ⁇ is shown.
  • the center of the paper in the horizontal direction of FIG. 14 represents the incident angle ⁇ being 0 degrees, that is, the laser beam r being perpendicularly incident on the angle filter 6.
  • the transmission peaks are discrete, and the period of the transmission peaks becomes narrower as the incident angle ⁇ increases.
  • Figure 15 is an enlarged view of the area surrounded by the thick dashed line in Figure 14.
  • Figure 15 also shows the incidence angle ⁇ of the zeroth-order light ro, the first-order light rp, and the second-order light rq emitted from the acousto-optical element 4.
  • Figure 15 shows the incidence angle ⁇ at which only the first-order light rp has a high transmittance. Since the acousto-optical element 4 is a diffraction grating in which the diffraction direction of the laser beam r is variable, the incidence angle ⁇ of the first-order light rp and the incidence angle ⁇ of the second-order light rq have an angular range.
  • the angle filter 6 shown in Figures 12 and 13 at an appropriate angle in the optical path of the laser processing device 1C, the first-order light rp emitted from the acousto-optical element 4 is transmitted, and the zeroth-order light ro and the second-order light rq are reflected, so that the first-order light rp can be separated from the zeroth-order light ro and the second-order light rq.
  • FIG. 16 is a transmission spectrum diagram showing the relationship between the wavelength ⁇ and the transmittance of the angular filter 6 of embodiment 3 at the incident angle ⁇ of the transmission peak of the primary light rp shown in FIG. 15.
  • a wide wavelength range of the wavelength ⁇ is shown.
  • FIG. 17 is an enlarged view of the area surrounded by the thick dashed line in FIG. 16. As is clear from FIG. 16, the transmission peaks are discrete and periodic. Note that FIG. 17 also shows a very narrow oscillation wavelength range in which the width of the laser beam r emitted from the laser oscillator 2 is less than 0.5 nm.
  • the dot-hatched area in FIG. 17 is the oscillation wavelength range.
  • the angle difference from the transmission peak at an incident angle ⁇ of 0 degrees to the adjacent bottom with low transmittance is wider than the angle difference between the zeroth-order light ro and the first-order light rp, or the angle difference between the first-order light rp and the second-order light rq, and the transmittance of the zeroth-order light ro and the second-order light rq cannot be kept sufficiently low.
  • the period of the transmission peak in FIG. 14 can be narrowed, and the incident angle ⁇ of the adjacent bottom with low transmittance can be matched to the incident angle ⁇ of the zeroth-order light ro and the second-order light rq.
  • the period of the transmission peaks shown in FIG. 16 also becomes narrower, and depending on the width of the oscillation wavelength range of the laser beam r, the oscillation wavelength range of the laser beam r shown in FIG. 17 may include several transmission peaks. As a result, the transmittance of the primary light rp decreases.
  • a solid etalon can be made from a metamaterial with a refractive index of 0.3 or less for the wavelength of the laser beam r, and when this solid etalon is used as the angle filter 6, both the angle characteristics and the transmission spectrum described above can be satisfied.
  • the oscillation wavelength range of the laser beam r can be contained within one transmission peak in the transmission spectrum while the first-order light rp is perpendicularly incident on the angle filter 6.
  • the angle filter 6 is an etalon configured so that the transmittance of the first-order light rp passing through the angle filter 6 is higher than the transmittance of the zeroth-order light ro passing through the angle filter 6 and the transmittance of the second-order light rq passing through the angle filter 6.
  • the first-order light rp shown in FIG. 13 is incident on the etalon, which is the angle filter 6, at an angle other than perpendicular, so that it is possible to increase the transmittance of the first-order light rp while keeping the transmittance of the zeroth-order light ro and the second-order light rq low.
  • the transmittance of the angle filter 6 changes depending on the incident angle ⁇ , so the angle filter 6 does not have directionality in the X-axis and Y-axis directions. Therefore, the zero-order light ro and second-order light rq in the X-axis direction outputted from the acousto-optical element 4a can be cut by the angle filter 6, and the zero-order light ro and second-order light rq in the Y-axis direction outputted from the acousto-optical element 4b can also be cut by the angle filter 6. Therefore, in this embodiment, at least one angle filter 6 after the acousto-optical element 4 is sufficient.
  • the angle filter 6 only needs to be able to separate at least one of the zeroth-order light ro and the second-order light rq from the first-order light rp of the laser beam r emitted from the acousto-optical element 4.
  • the angle filter 6 only needs to be configured so that the transmittance of the first-order light rp passing through the angle filter 6 is higher than at least one of the transmittance of the zeroth-order light ro passing through the angle filter 6 and the transmittance of the second-order light rq passing through the angle filter 6.
  • the number of acousto-optical elements 4, angular filters 6, and galvanometers 8 is not limited to the example shown in the figure and may be changed as appropriate.
  • Embodiment 4 a laser processing apparatus 1D according to a fourth embodiment will be described with reference to Fig. 18 to Fig. 23.
  • This embodiment differs from the second embodiment in that the configuration of the angle filter 6 and the damper 7 are provided.
  • the same reference numerals are used for the parts that overlap with the second embodiment, and the description thereof will be omitted.
  • FIG. 18 is a perspective view showing a laser processing apparatus 1D according to the fourth embodiment.
  • FIG. 19 is a diagram for explaining the function of the angle filter 6 according to the fourth embodiment.
  • the double-headed arrows Y0, Y1, and Y2 shown in FIG. 19 represent the polarization directions of the zeroth-order light ro, the first-order light rp, and the second-order light rq, respectively.
  • the double-headed arrow Y3 shown in FIG. 19 represents the polarization direction of the laser beam r when it is incident on the acousto-optical element 4.
  • the angle filter 6 shown in FIG. 18 is an attenuator equipped with a wave plate 6r and a polarizing beam splitter 6s. As shown in FIG.
  • the wave plate 6r causes the polarization direction Y1 of the first-order light rp to differ by 90 degrees from the polarization direction Y0 of the zeroth-order light ro and the polarization direction Y2 of the second-order light rq.
  • the polarizing beam splitter 6s is disposed after the wave plate 6r on the optical path of the laser beam r, and transmits only the first-order light rp and reflects the zeroth-order light ro and the second-order light rq, or reflects only the first-order light rp and transmits the zeroth-order light ro and the second-order light rq.
  • the attenuator can adjust the intensity ratio of the light transmitted through the polarizing beam splitter 6s and the light reflected by the polarizing beam splitter 6s.
  • the angle filter 6 is configured so that the transmission rate of the first-order light rp passing through the angle filter 6 is higher than the transmission rate of the zeroth-order light ro passing through the angle filter 6 and the transmission rate of the second-order light rq passing through the angle filter 6.
  • the transmission here means that when the first-order light rp passes through the polarizing beam splitter 6s, the zeroth-order light ro and the second-order light rq are also transmitted, and when the first-order light rp is reflected by the polarizing beam splitter 6s, the zeroth-order light ro and the second-order light rq are also reflected.
  • the transmission rate refers to the transmittance when the primary light rp passes through the polarizing beam splitter 6s, and refers to the reflectance when the primary light rp is reflected by the polarizing beam splitter 6s.
  • the material of the wave plate 6r is not particularly limited as long as it is a birefringent material that can transmit the wavelength of the laser beam r.
  • the birefringent material may be a uniaxial crystal or a biaxial crystal.
  • the material of the wave plate 6r is, for example, quartz.
  • the wave plate 6r used as the angle filter 6 is a multi-order wave
  • the number of angle filters 6 is two in this embodiment.
  • angle filters 6a and 6b when the two angle filters 6 are to be distinguished from one another, they are referred to as angle filters 6a and 6b.
  • wave plates 6r of the two angle filters 6 when the wave plates 6r of the two angle filters 6 are to be distinguished from one another, they are referred to as wave plates 6r1 and 6r2.
  • polarizing beam splitters 6s of the two angle filters 6 are to be distinguished from one another, they are referred to as polarizing beam splitters 6s1 and 6s2.
  • the wave plate 6r2 and the polarizing beam splitter 6s2 are arranged after the acousto-optic element 4b on the optical path of the laser beam r, and the wave plate 6r1 and the polarizing beam splitter 6s1 are arranged after the acousto-optic element 4a on the optical path of the laser beam r.
  • the half-wave plate 5 may be arranged between the polarizing beam splitter 6s2 and the acousto-optic element 4a.
  • the damper 7 serves to absorb the zeroth-order light ro and the second-order light rq of the laser beam r emitted from the angle filter 6.
  • damper 7a and damper 7b are disposed near the angle filter 6a and absorbs the zeroth-order light ro and the second-order light rq of the laser beam r emitted from the angle filter 6a.
  • the damper 7b is disposed near the angle filter 6b and absorbs the zeroth-order light ro and the second-order light rq of the laser beam r emitted from the angle filter 6b.
  • the operation of the angle filter 6 of the fourth embodiment will be described. Since the angle filters 6a and 6b have the same operation, only the operation of the angle filter 6b arranged after the acousto-optical element 4b on the optical path of the laser beam r will be described here, and the operation of the angle filter 6a will be omitted.
  • the zeroth-order light ro, the first-order light rp, and the second-order light rq emitted from the acousto-optical element 4b are incident on the wave plate 6r2 at different angles.
  • the zeroth-order light ro, the first-order light rp, and the second-order light rq are each linearly polarized light.
  • the arrow with the symbol V on the surface of the wave plate 6r2 indicates the direction of the optical axis of the wave plate 6r2.
  • the polarization directions Y0, Y1, and Y2 of the zeroth-order light ro, the first-order light rp, and the second-order light rq emitted from the wave plate 6r2 rotate or do not rotate depending on the optical path length in the wave plate 6r2.
  • the design parameter of the wave plate 6r is the thickness (optical path length).
  • the angle between the direction V of the optical axis of the wave plate 6r2 and the polarization directions Y0, Y1, Y2 of the zeroth-order light ro, the first-order light rp, and the second-order light rq incident on the wave plate 6r2 is 45 degrees. Also, in this embodiment, only the polarization direction Y1 of the first-order light rp output from the wave plate 6r2 rotates by 90 degrees, and the polarization directions Y0, Y2 of the zeroth-order light ro and the second-order light rq do not rotate and are the same as the polarization directions Y0, Y2 when they are incident on the wave plate 6r2.
  • the first-order light rp passes through the polarizing beam splitter 6s2, and the zeroth-order light ro and the second-order light rq are reflected by the polarizing beam splitter 6s2.
  • the thickness of the wave plate 6r2 or adjusting the angles of incidence of the zeroth light ro, the first-order light rp, and the second-order light rq on the wave plate 6r2
  • the polarization direction Y1 of the first-order light rp and the polarization direction Y0 of the zeroth-order light ro and the polarization direction Y2 of the second-order light rq different by 90 degrees using the wave plate 6r2
  • the damper 7 may be arranged ahead of the zero-order light ro and the second-order light rq in the traveling direction that transmits through the polarizing beam splitter 6s2 or is reflected by the polarizing beam splitter 6s2.
  • Figure 20 is an angle characteristic diagram showing the relationship between the incident angle and transmittance on the wave plate 6r of the angle filter 6 of embodiment 4 at the wavelength ⁇ of the laser beam r when the thickness of the wave plate 6r is appropriately set.
  • a wide range of incident angles is shown.
  • the center of the paper in the horizontal direction of Figure 20 represents an incident angle of 0 degrees, that is, the laser beam r is perpendicularly incident on the angle filter 6.
  • the transmission peaks are periodic, and the period of the transmission peaks becomes narrower as the incident angle increases.
  • Figure 21 is an enlarged view of the area surrounded by the thick dashed line in Figure 20.
  • Figure 21 also shows the angles of incidence of the zeroth-order light ro, first-order light rp, and second-order light rq emitted from the acousto-optical element 4.
  • Figure 21 shows the angles of incidence at which only the first-order light rp has a high transmittance. Since the acousto-optical element 4 is a diffraction grating in which the diffraction direction of the laser beam r is variable, the angles of incidence of the first-order light rp and the second-order light rq have an angular range.
  • the transmittance of the first-order light rp is higher than that of the zeroth-order light ro and the second-order light rq.
  • the transmittance of the zeroth-order light ro and the second-order light rq are kept low compared to that of the first-order light rp. That is, by placing the wave plate 6r of the angle filter 6 shown in FIG. 18 at an appropriate angle in the optical path of the laser processing device 1D, the polarizing beam splitter 6s2 shown in FIG.
  • Figure 22 is a transmission spectrum diagram showing the relationship between the wavelength ⁇ and the transmittance of the angular filter 6 of embodiment 4 at the incident angle of the transmission peak of the primary light rp shown in Figure 21.
  • a wide range of wavelengths ⁇ is shown.
  • Figure 23 is an enlarged view of the area surrounded by the thick dashed line in Figure 22. As is clear from Figure 22, the transmission peaks are periodic. Note that Figure 23 also shows a very narrow oscillation wavelength range in which the width of the laser beam r emitted from the laser oscillator 2 is less than 0.5 nm. The dot-hatched area in Figure 23 is the oscillation wavelength range.
  • the angle difference from the transmission peak at an incident angle of 0 degrees to the adjacent bottom with low transmittance is wider than the angle difference between the zeroth-order light ro and the first-order light rp or the angle difference between the first-order light rp and the second-order light rq, and the transmittance of the zeroth-order light ro and the second-order light rq cannot be kept sufficiently low.
  • the period of the transmission peak in FIG. 20 can be narrowed, and the angle of incidence of the adjacent bottom with low transmittance can be adjusted to the angle of incidence of the zeroth-order light ro and the second-order light rq.
  • the period of the transmission peaks shown in FIG. 22 will also become narrower, and depending on the width of the oscillation wavelength range of the laser beam r, the oscillation wavelength range of the laser beam r shown in FIG. 23 will include several transmission peaks. As a result, the transmittance of the primary light rp will decrease.
  • the secondary light rq emitted from the acousto-optic element 4 has a wide angular range when the diffraction direction is changed, so it is preferable to make the secondary light rq perpendicularly incident on the wave plate 6r and to have the primary light rp reflected by the angle filter 6 in order to reduce the transmission rate of the secondary light rq. It is also possible to change the thickness of the wave plate 6r and invert the angle characteristic diagram in Figure 20 upside down. In other words, it is also possible to make it so that the secondary light rq perpendicularly incident on the wave plate 6r is reflected by the polarizing beam splitter 6s and the primary light rp is transmitted through the polarizing beam splitter 6s.
  • the angle filter 6 is an attenuator configured so that the transmission rate of the first-order light rp passing through the angle filter 6 is higher than the transmission rate of the zeroth-order light ro passing through the angle filter 6 and the transmission rate of the second-order light rq passing through the angle filter 6.
  • the angle filter 6 includes a wave plate 6r that makes the polarization direction Y1 of the first-order light rp different from the polarization direction Y0 of the zeroth-order light ro and the polarization direction Y2 of the second-order light rq by 90 degrees, and a polarizing beam splitter 6s that is disposed after the wave plate 6r on the optical path of the laser beam r and transmits only the first-order light rp and reflects the zeroth-order light ro and the second-order light rq, or reflects only the first-order light rp and transmits the zeroth-order light ro and the second-order light rq.
  • the first-order light rp shown in FIG. 19 is incident on the wave plate 6r of the angle filter 6 at an angle other than perpendicular, so that it is possible to increase the transmittance of the first-order light rp while keeping the transmittance of the zeroth-order light ro and the second-order light rq low.
  • the laser processing device 1D is equipped with a damper 7 that absorbs the zero-order light ro and the second-order light rq that are transmitted through the polarizing beam splitter 6s or reflected by the polarizing beam splitter 6s.
  • This configuration makes it possible to prevent the zero-order light ro and the second-order light rq that are unnecessary for processing the workpiece 11 from being irradiated to unintended locations.
  • the angle filter 6 only needs to be able to separate at least one of the zeroth-order light ro and the second-order light rq from the first-order light rp of the laser beam r emitted from the acousto-optical element 4.
  • the angle filter 6 only needs to be arranged so that when at least one of the zeroth-order light ro and the second-order light rq emitted from the acousto-optical element 4 and the first-order light rp pass through the angle filter 6, the angle difference between at least one of the zeroth-order light ro and the second-order light rq and the first-order light rp becomes large.
  • the angle filter 6 only needs to be configured so that the transmission rate of the first-order light rp passing through the angle filter 6 is higher than at least one of the transmission rate of the zeroth-order light ro passing through the angle filter 6 and the transmission rate of the second-order light rq passing through the angle filter 6.
  • the number of acousto-optical elements 4, angular filters 6, and galvanometers 8 may be changed as appropriate without being limited to the example shown in the figure.
  • the angular filter 6 arranged after the acousto-optical element 4b shown in FIG. 18 may be omitted.
  • Appendix 1 a laser oscillator that emits a laser beam; an acousto-optic element that diffracts the laser beam emitted from the laser oscillator; an angle filter that separates at least one of a zero-order light and a second-order light from a first-order light of the laser beam outputted from the acousto-optic element;
  • the angle filter is configured so that the transmittance of the first-order light passing through the angle filter is higher than at least one of the transmittance of the zeroth-order light passing through the angle filter and the transmittance of the second-order light passing through the angle filter.
  • the angle filter is A wave plate that makes the polarization direction of the first-order light different from the polarization direction of the zeroth-order light and the polarization direction of the second-order light by 90 degrees; a polarizing beam splitter that is disposed after the wave plate on the optical path of the laser beam and transmits only the first-order light and reflects the zeroth-order light and the second-order light, or reflects only the first-order light and transmits the zeroth-order light and the second-order light; 2.
  • the laser processing apparatus according to claim 1, comprising: (Appendix 3) 3.
  • the angular filter is an etalon.
  • Appendix 5 The laser processing apparatus according to claim 4, wherein the primary light is incident on the etalon at an angle other than perpendicular.
  • the angular filter is a plate-like element formed of a material that is not transparent to the laser beam, 2.
  • the laser processing apparatus according to claim 1, wherein the plate-like element has a plurality of openings formed therethrough in the thickness direction.
  • Appendix 7) The laser processing apparatus according to claim 6, wherein the shape of the opening when viewed along the penetration direction is a circle or a regular polygon.
  • Appendix 9 a laser oscillator that emits a laser beam; an acousto-optic element that diffracts the laser beam emitted from the laser oscillator; an angle filter that separates at least one of a zero-order light and a second-order light from a first-order light of the laser beam outputted from the acousto-optic element;
  • the laser processing apparatus is characterized in that the angular filter is a transmission type diffraction grating that diffracts the first-order light so that the angular difference between the first-order light and at least one of the zero-order light and the second-order light emitted from the acousto-optical element and the zero-order light is large when the first-order light and at least one of the zero-order light and the second-order light pass through
  • the transmission type diffraction grating is a volume phase holographic type diffraction grating.
  • the transmission type diffraction grating includes a front surface onto which the laser beam is incident and a back surface from which the laser beam is emitted, 10.
  • the front surface and the back surface are provided with a grating pattern.
  • Appendix 12 12.
  • the laser processing apparatus according to any one of claims 1 to 12, further comprising at least one damper that absorbs at least one of the zeroth order light and the second order light of the laser beam emitted from the acousto-optical element.
  • Appendix 14 13
  • Appendix 15 15.
  • 1, 1A, 1B, 1C, 1D laser processing device 2 laser oscillator, 3 mirror, 4, 4a, 4b acousto-optical element, 5, 5a, 5b 1/2 wavelength plate, 6, 6a, 6b angle filter, 6c front surface, 6d back surface, 6e grating pattern, 6f groove, 6g step surface, 6h, 6i, 6j, 6k, 6m blazed surface, 6n, 15a aperture, 6o, 6p transparent member, 6q partial reflector, 6r, 6r1, 6r2 wavelength plate, 6s, 6s1 , 6s2 polarizing beam splitter, 7, 7a, 7b, 15 damper, 8, 8a, 8b galvanometer, 8c galvanometer mirror, 8d galvanometer motor, 9 focusing lens, 10 table, 11 workpiece, 12 afocal lens, 13, 14 convex lens, C center line, G gap, r laser beam, ro 0th order light, rp 1st order light, rq 2nd order light

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  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Nonlinear Science (AREA)
  • Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Mechanical Engineering (AREA)
  • Laser Beam Processing (AREA)

Abstract

Cet appareil de traitement laser (1D) comprend un oscillateur laser (2) qui émet un faisceau laser (r), un élément optique acoustique (4) qui réfracte le faisceau laser (r), et un filtre d'angle (6) qui sépare la lumière de premier ordre d'une lumière d'ordre zéro et/ou d'une lumière de second ordre à l'intérieur du faisceau laser (r) émis par l'élément optique acoustique (4). Le filtre d'angle (6) est configuré de sorte que le débit de transmission de la lumière de premier ordre transmise à travers le filtre d'angle (6) est supérieur à audit au moins un débit de transmission de la lumière d'ordre zéro transmise à travers le filtre d'angle (6) et le débit de transmission de la lumière de second ordre étant transmis à travers le filtre d'angle (6).
PCT/JP2024/003732 2023-02-20 2024-02-05 Appareil de traitement laser Ceased WO2024176797A1 (fr)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070075063A1 (en) * 2005-10-03 2007-04-05 Aradigm Corporation Method and system for LASER machining
KR102018613B1 (ko) * 2018-04-04 2019-09-06 주식회사 이오테크닉스 음향 광학 편향 시스템, 이를 포함하는 레이저 가공 장치 및 빔 차단 방법
JP2020062658A (ja) * 2018-10-16 2020-04-23 イビデン株式会社 レーザ加工装置およびレーザ加工方法

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050213192A1 (en) * 2002-11-28 2005-09-29 Murtagh Martin E Apparatus for modulating a light beam
CN217965346U (zh) * 2022-06-08 2022-12-06 伊欧激光科技（苏州）有限公司 一种利用声响光学调制的激光加工装置

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070075063A1 (en) * 2005-10-03 2007-04-05 Aradigm Corporation Method and system for LASER machining
KR102018613B1 (ko) * 2018-04-04 2019-09-06 주식회사 이오테크닉스 음향 광학 편향 시스템, 이를 포함하는 레이저 가공 장치 및 빔 차단 방법
JP2020062658A (ja) * 2018-10-16 2020-04-23 イビデン株式会社 レーザ加工装置およびレーザ加工方法

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