Laser devices and laser processing equipment

Abstract

The laser device (100) includes: a seed light source that outputs pulsed laser light and can control the repetition frequency of the pulsed laser light; an amplifier that amplifies and outputs the pulsed laser light; a shield (50) that shapes at least one of the beam diameter and beam shape of the pulsed laser light emitted from the amplifier; an optical switch element (30) disposed in the optical path between the amplifier and the shield (50) that modulates the transmittance so that at least one of the output and energy of the pulsed laser light emitted from the amplifier varies over time with the change of the repetition frequency of the pulsed laser light within a predetermined range; and a beam conduction adjustment unit (40) disposed in the optical path between the amplifier and the shield (50) that adjusts the beam conduction of the pulsed laser light emitted from the amplifier.

Description

[Technical Field]

[0001] This disclosure relates to a laser apparatus for emitting laser light for laser processing, and a laser processing apparatus. [Previous Technology]

[0002] In recent years, laser processing equipment using short-pulse lasers as light sources has been widely used in various applications such as opening holes in printed circuit boards, glass cutting, and precision metal processing in microfabrication. In laser equipment installed in such processing units, a master oscillator power amplifier (MOPA) method is often used, where the short-pulse laser light output from the seed light source is amplified by a solid-state amplifier. Advantages of the MOPA method include easily controllable pulse characteristics and the ability to increase the output of the pulsed laser light by increasing the number of stages in the solid-state amplifier, catering to different processing applications. Furthermore, in laser equipment installed in laser processing units, sometimes the short-pulse laser light output from the MOPA light source is used as the fundamental wave, and harmonics are generated using a nonlinear optical crystal to output a short-wavelength short-pulse laser light with a shortened wavelength.

[0003] When performing micro-machining using a laser processing apparatus that employs short-pulse laser light as a light source, productivity can sometimes be improved by changing the laser's repetition frequency according to the processing shape. However, in a typical short-pulse laser, the output characteristics or beam conduction characteristics of the output pulsed laser light change with the repetition frequency. Since these changes are accompanied by thermal changes within the short-pulse laser, they do not end instantaneously but occur over time. Therefore, there is a problem that the output characteristics or beam conduction characteristics at the processing point change over time after the repetition frequency is changed. When the output characteristics or beam conduction characteristics of the short-pulse laser light change, the intensity distribution at the processing point changes, making it difficult to maintain stable processing quality after the repetition frequency is changed.

[0004] Patent Document 1 describes a laser processing apparatus that uses a laser whose output parameters need to be changed in accordance with laser output changes. The laser light emitted from the laser is incident on an acousto-optic element that modulates the transmittance of the laser light. By changing the transmittance of the laser light through the acousto-optic element, the output of the laser light emitted from the acousto-optic element is kept constant. [Prior Art Documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2005-161329. [Summary of the Invention]

[0006] [Problem to be Solved by the Invention] However, the laser processing apparatus described in Patent Document 1 does not take into account the change in the beam conduction characteristics of the pulsed laser light over time when the repetition frequency of the laser is changed. That is, in the laser processing apparatus described in Patent Document 1, because the beam conduction characteristics of the pulsed laser light change over time when the repetition frequency of the pulsed laser light is changed, the beam diameter or beam shape at the processing point changes over time, which leads to the problem that it is difficult to immediately perform stable processing after the repetition frequency is changed.

[0007] This disclosure arises in view of the above-mentioned problems, and its purpose is to provide a laser device that can suppress changes in the output characteristics and beam conduction characteristics of the amplified pulsed laser light over time due to variations in the repetition frequency of the seed light source. [Means for solving the problem]

[0008] To solve the above problems and achieve the objective, the laser device disclosed herein includes: a seed light source that outputs pulsed laser light and can control the repetition frequency of the pulsed laser light; an amplifier that amplifies and outputs the pulsed laser light; a shield that shapes at least one of the beam diameter and beam shape of the pulsed laser light emitted from the amplifier; an optical switching element disposed in the optical path between the amplifier and the shield that modulates the transmittance so that at least one of the output and energy of the pulsed laser light emitted from the amplifier varies over time with the change in the repetition frequency of the pulsed laser light within a predetermined range; and a beam conduction adjustment unit disposed in the optical path between the amplifier and the shield that adjusts the beam conduction of the pulsed laser light emitted from the amplifier. [Effects of the Invention]

[0009] According to this disclosure, it is possible to achieve the effect of obtaining a laser device that can suppress the changes in the output characteristics and beam conduction characteristics of the amplified pulsed laser light over time due to changes in the repetition frequency of the seed light source.

Implementation Method

[0011] Hereinafter, a laser apparatus and a laser processing apparatus according to embodiments of the present disclosure will be described in detail based on the drawings. Furthermore, the embodiments described below are merely illustrative, and the scope of the present disclosure is not limited to the embodiments described below.

[0012] Example 1. Figure 1 is a block diagram schematically showing an example of the configuration of a laser processing apparatus including a laser device according to Example 1. The laser processing apparatus 1 is an apparatus that processes a workpiece W by irradiating it with pulsed laser light output from the laser device 100. The workpiece W is, for example, a printed circuit board, a glass substrate, or a metal plate. Processing includes, for example, cutting, soldering, and drilling. The laser processing apparatus 1 can perform processes such as drilling holes in printed circuit boards, cutting glass, and precision machining of metals.

[0013] The laser processing apparatus 1 includes a laser device 100 that outputs pulsed laser light, a scanning unit 60, a mask transcribing optical system 70, and a processing table 80.

[0014] The laser device 100 includes a laser oscillator 10, a control unit 20, an optical switch element 30, a beam conduction adjustment unit 40, a drive device 41, and a shield 50.

[0015] The laser oscillator 10 outputs pulsed laser light. The pulse width of the pulsed laser light output from the laser oscillator 10 varies from femtoseconds to microseconds, depending on the type of object W being processed and the content of the laser processing. When fine and precise laser processing is required, short-pulse laser light with a pulse width of tens of picoseconds or less is used as the pulsed laser light output from the laser oscillator 10. In particular, ablation processing using short-pulse laser light can reduce the heat effect generated during processing, making it suitable for micro-processing. In Example 1, the pulsed laser light output from the laser oscillator 10 is assumed to be a short-pulse laser light with a pulse width of tens of picoseconds or less suitable for micro-processing. Hereinafter, the "short-pulse laser light" output from the laser oscillator 10 will sometimes be simply referred to as "pulse light".

[0016] Figure 2 is a block diagram schematically showing one example of the configuration of a laser oscillator including a laser device according to Embodiment 1. The laser oscillator 10 includes a seed light source 11, an fiber amplifier 12, a solid-state amplifier 13, and a nonlinear optical crystal 14. The laser oscillator 10 is a wavelength conversion MOPA type laser that amplifies and outputs pulsed light L from the seed light source 11 through the fiber amplifier 12 and the solid-state amplifier 13. The laser oscillator 10 emits short-pulse laser light.

[0017] The seed light source 11 outputs a pulsed light L as laser light with a pulse width of less than tens of picoseconds. The pulsed light L output from the seed light source 11 is laser light amplified in the fiber amplifier 12 and the solid-state amplifier 13. As an example, the seed light source 11 uses a gain-switched semiconductor laser, a mode-locked fiber laser oscillator, or a solid-state laser oscillator.

[0018] The fiber optic amplifier 12 amplifies the pulsed light L output from the seed light source 11. Since the output of the pulsed light L from the seed light source 11 is relatively low, an amplifier is needed to amplify the pulsed light L output from the seed light source 11 in the downstream section of the seed light source 11 in order to use the seed light source 11 as a processing light source. The fiber optic amplifier 12 can amplify the low-output pulsed light with high efficiency. As an example, the fiber optic amplifier 12 uses fiber with added ytterbium (Yb). The output characteristics of the pulsed light output from the fiber optic amplifier 12, as an example, have an average output of several milliwatts (mW) to several hundred mW, and a peak output of several kilowatts (kW).

[0019] In addition, the "output characteristics of pulsed laser light" in Example 1 refers to the average output of pulsed laser light, the pulse energy of pulsed laser light, the peak output of pulsed laser light, and other characteristics.

[0020] The solid-state amplifier 13 amplifies and outputs the pulsed amplified light output from the fiber optic amplifier 12 to a high output range suitable for processing the workpiece W. The solid-state amplifier 13 includes a solid-state active medium and an excitation light source. The solid-state active medium is excited by the excitation light source. The pulsed light incident on the solid-state active medium is amplified and emitted as pulsed amplified light. For example, the output characteristics of the pulsed amplified light output from the solid-state amplifier 13 include an average output of several watts (W) to tens of W, and a peak output of several megawatts (MW) to tens of MW.

[0021] As an example, the solid-state active medium of the solid-state amplifier 13 uses neodymium-doped yttrium vanadate (Nd:YVO₄), neodymium-doped yttrium aluminum garnet (Nd:YAG), ytterbium-doped yttrium aluminum garnet (Yb:YAG), and ytterbium-doped potassium tungstate (Yb:KGW). The excitation light source is a light source that outputs laser light to excite the solid-state active medium. For the excitation light source, a semiconductor laser is preferably used. The wavelength of the laser light output from the excitation light source corresponds to the absorption spectrum of the solid-state active medium. An example of the wavelength of the laser light output from the excitation light source is 808 nm, 878.6 nm, 880 nm, 885 nm, 940 nm, and 980 nm.

[0022] In addition, although one solid-state amplifier 13 is used in Embodiment 1, the solid-state amplifier 13 may also be composed of multiple stages.

[0023] The nonlinear optical crystal 14 operates as a wavelength conversion crystal that converts the wavelength of the pulse amplified light amplified in the solid-state amplifier 13. The nonlinear optical crystal 14 converts the wavelength of the pulse amplified light amplified in the solid-state amplifier 13 to 1 / 2, 1 / 3, or 1 / 4 times its normal wavelength through high-order harmonic generation, which is a second nonlinear optical effect. That is, the nonlinear optical crystal 14 converts the wavelength of the pulse amplified light amplified in the solid-state amplifier 13 to a second, third, or fourth harmonic through high-order harmonic generation. For example, lithium triborate (LiB₃O₅, LBO), cesium lithium borate (CsLiB₆O₁₀, CLBO), and barium β-borate (β-BaB₂O₄, BBO) crystals are used. When the wavelength of the pulse amplified light amplified in the solid-state amplifier 13 is made to be 1 / 3 or 1 / 4 times its normal wavelength, two or more nonlinear optical crystals 14 are used. As an example, the nonlinear optical crystal 14 at this time uses a combination of LBO and LBO, or LBO and CLBO.

[0024] In order to control the characteristics of the pulsed light output from the laser oscillator 10, there are also cases where an optical switching element is incorporated into the laser oscillator 10. The optical switching element incorporated into the laser oscillator 10 is configured between the fiber amplifier 12 and the solid-state amplifier 13, between the solid-state amplifier 13 and the nonlinear optical crystal 14, or at the rear end of the nonlinear optical crystal 14.

[0025] Through the above configuration, the laser oscillator 10 emits pulsed amplified light with a wavelength determined by the nonlinear optical crystal 14.

[0026] Hereinafter, the pulsed light that amplifies the pulsed light L output from the seed light source 11 will be called the pulse amplification light L1. That is, the pulse amplification light L1 is the pulsed laser amplification light that amplifies the pulsed laser light output from the seed light source 11.

[0027] Returning to Figure 1, the control unit 20 controls various parameters of the pulse amplification light L1, which is the pulse light output from the laser oscillator 10, including wavelength, repetition frequency, pulse width, average output, and pulse energy. The repetition frequency is the number of pulses generated per second in a pulse generated at a certain period. In addition, the control unit 20 controls the optical switch element 30, the drive device 41, the scanning unit 60, the mask transcribing optical system 70, and the processing stage 80.

[0028] The optical switching element 30 modulates the transmittance of the pulsed amplified light L1 output from the laser oscillator 10. The pulsed amplified light L1 output from the laser oscillator 10 is incident on the optical switching element 30, and after passing through the optical switching element 30 at a set transmittance, it is incident on the beam guiding adjustment unit 40 along the optical axis La of the pulsed amplified light L1. The transmittance of the optical switching element 30 is modulated according to the signal transmitted from the control unit 20.

[0029] The transmittance of the optical switching element 30 is defined as the optical switching condition where the output of the pulsed amplified light L1 traveling from the optical switching element 30 towards the shield 50 reaches its maximum, and is defined as 100% transmittance. In the laser processing apparatus 1, for example, an acousto-optic modulator (AOM) is used for the optical switching element 30, and the first diffracted light of the pulsed amplified light L1 output from the AOM can be used for laser processing. At this time, the diffraction efficiency of the first diffracted light of the pulsed amplified light L1 output from the AOM is at most about 85%. That is, in the general method of considering transmittance, the transmittance of the AOM is 85%.

[0030] In the laser processing apparatus 1, when the output of the pulsed amplified light L1 traveling in the direction of the transmission light switching element 30 toward the shield 50 reaches its maximum, the output of the first diffracted light in the maximum diffraction efficiency is redefined as 100% transmittance. That is, for example, when the maximum diffraction efficiency of the first diffracted light of the pulsed amplified light L1 emitted from the AOM is 85%, the optical switching condition at this time is defined as 100% transmittance. In addition, similar to the general method of considering transmittance, when the amount of light of the pulsed amplified light L1 traveling in the direction of the shield 50 through the AOM is 0, the transmittance is 0%.

[0031] In addition, "modulation of transmittance" refers to making the transmittance change over time. By setting the transmittance of the pulsed light in the optical switching element 30 to 0% or 100%, the output of the pulsed amplified light L1 from the optical switching element 30 can be switched on and off.

[0032] For the optical switch element 30, an acousto-optic (AO) element and an electro-optic (EO) element are used as examples. When an acousto-optic element is used in the optical switch element 30, the zero-order diffraction light or the first-order diffraction light of the acousto-optic element is used for processing.

[0033] The optical switching element 30 is disposed on the optical axis La of the pulse amplification light L1 between the laser oscillator 10 and the beam conduction adjustment section 40. When the transmittance of the pulse amplification light L1 is modulated by the optical switching element 30 for each pulse, the modulation frequency of the transmittance in the optical switching element 30 is set to the repetition frequency of the pulse amplification light L1, that is, the repetition frequency of the pulse light L output from the seed light source 11. The optical switching element 30 selects the wavelength of the pulse amplification light L1 applied to the processing of the workpiece W. In addition, in the optical switching element 30, a non-reflective film for the wavelength of the pulse amplification light L1 is provided at the pulse light incident surface where the pulse amplification light L1 is incident and the pulse light emitting surface where the pulse light is emitted.

[0034] The beam conduction adjustment unit 40 adjusts the beam conduction of the pulse amplification light L1 output from the optical switching element 30. "Beam conduction" refers to the change in the beam diameter of the pulse amplification light L1 as it travels. When discussing beam conduction in a cross-section perpendicular to the direction of travel of the pulse amplification light L1, the beam conduction in the pulse amplification light L1 at that position is determined by the beam diameter, the radius of curvature of the wavefront, the beam quality M2, and the wavelength.

[0035] The beam transmission adjustment unit 40 has at least one optical element, either a spherical lens or a curved mirror, as a constituent element. The beam transmission adjustment unit 40 is, for example, composed of a plano-convex lens, a plano-concave lens, and a convex mirror. The pulsed amplified light L1 transmitted through the beam transmission adjustment unit 40 illuminates the shield 50.

[0036] A driving device 41 is provided on the beam conduction adjustment section 40. The driving device 41 includes the function of moving an optical element, which is a constituent element of the beam conduction adjustment section 40, along the optical axis of the pulse amplified light L1 output from the optical switching element 30. By moving the optical element of the beam conduction adjustment section 40 along the optical axis of the pulse amplified light L1 output from the optical switching element 30, the driving device 41 can adjust at least one of the beam diameter and the radius of curvature of the wavefront of the pulse amplified light L1 illuminating the shield 50. That is, the driving device 41 can adjust at least one of the beam diameter and the radius of curvature of the wavefront of the pulse amplified light L1 on the shield 50. In addition, the positional relationship between the optical switching element 30 and the beam conduction adjustment section 40 on the optical axis La of the pulse amplified light L1 between the laser oscillator 10 and the shield 50 can also be reversed.

[0037] The laser processing apparatus 1 can stabilize the processing quality by moving the optical element constituting the beam conduction adjustment section 40 and by operating at least one of the beam diameter and the radius of curvature of the pulse amplification light L1 on the mask 50.

[0038] The mask 50 includes an opening 50a, which allows a portion of the pulsed amplified light L1 from the transmission beam guidance adjustment section 40 to be transmitted, restricting the transmission area of ​​the pulsed amplified light L1 and shaping the beam profile of the pulsed amplified light L1. By restricting the transmission area of ​​the pulsed amplified light L1 from the transmission beam guidance adjustment section 40, the mask 50 shapes at least one of the beam diameter and beam shape of the pulsed amplified light L1, thus shaping the beam profile of the pulsed amplified light L1. The control section 20 controls the position of the beam guidance adjustment section 40 so that the beam diameter on the mask 50 of the pulsed amplified light L1 is larger than the opening diameter of the opening 50a.

[0039] For example, a metal plate forming an opening 50a is used in the mask 50. The shape of the transmission area of ​​the mask 50, that is, the shape of the opening 50a in the in-plane direction of the mask 50, is, in one example, circular or rectangular. Alternatively, the shape of the transmission area of ​​the mask 50 can be a shape surrounded by a pattern composed of a plurality of lines or circles. When the shape of the transmission area of ​​the mask 50 is a shape surrounded by a pattern composed of a plurality of lines or circles, the substrate of the mask 50 uses a transparent material that allows the pulse amplification light L1 to be transmitted, and a metal film is provided in the patterned portion of the substrate to obstruct the transmission of the pulse amplification light L1.

[0040] While fixing the workpiece W, the processing table 80 moves in the vertical two-axis direction, causing the workpiece W to move in the vertical two-axis direction. In Embodiment 1, the vertical two-axis direction, which is the direction of movement of the processing table 80, is defined as the X direction and the Y direction.

[0041] The scanning unit 60 guides the pulsed amplified light L1 from the opening 50a of the transmission shield 50 to the workpiece W to form an optical path, and transmits the pulsed amplified light L1 from the opening 50a of the transmission shield 50 to a desired position on the workpiece W and focuses the light. The scanning unit 60 scans the pulsed amplified light L1 from the opening 50a of the transmission shield 50, so that the pulsed amplified light L1 illuminates the desired position on the surface of the workpiece W to be processed. The scanning unit 60 is composed of one or more mirrors. In one example, the scanning unit 60 is composed of a galvano mirror. The galvano mirror may also be composed of two mirrors that scan the X and Y directions at the processing point respectively.

[0042] The mask transcription optical system 70 transcribes the pattern of the pulsed amplified light L1 transmitted through the mask 50 onto the workpiece W. That is, the pulsed amplified light L1, which is transmitted through the opening 50a of the mask 50 and scanned by the scanning unit 60, is incident on the mask transcription optical system 70, and the image of the opening 50a is transcribed onto the surface of the workpiece W to be processed. In other words, when the mask transcription optical system 70 is used, the processing shape of the workpiece W is determined by the transmission shape of the mask 50, that is, by the shape of the opening 50a of the mask 50.

[0043] The mask transcribing optical system 70 consists of a set of condenser lenses. Alternatively, the mask transcribing optical system 70 may consist of a collimator lens and a set of condenser lenses, the collimator lens being collimated to diffract the pulsed amplified light L1 transmitted through the mask 50. For example, an fθ lens may be used as the condenser lens. The position of the fθ lens is adjusted so that the image of the opening 50a of the mask 50 on the workpiece W is properly transcribed at the desired position. When the position adjustment of the fθ lens is performed via an automatic stage, the position of the fθ lens is adjusted by controlling the position of the automatic stage via the control unit 20.

[0044] In the laser processing apparatus 1, a processing optical system 65 is constituted by a scanning unit 60 and a mask transcribing optical system 70. The processing optical system 65 forms an optical path that guides the pulse amplification light L1 emitted from the laser apparatus 100 to the workpiece W, focuses the pulse amplification light L1 to a desired position on the workpiece W, and irradiates the workpiece W with the pulse amplification light L1.

[0045] Next, the response of the laser oscillator 10 shown in Figure 2 when the repetition frequency of the pulsed light L output from the seed light source 11 is changed will be explained. Here, it is assumed that a semiconductor laser is used as the seed light source 11 of the laser oscillator 10. Furthermore, it is assumed that the repetition frequency of the pulsed light used for laser aperture processing is typically from 100 kHz to several MHz.

[0046] First, the repetition frequency of the pulsed light is determined by the repetition frequency of the current pulse injected into the semiconductor laser to oscillate the laser. Therefore, the change in the repetition frequency of the pulsed light output from the semiconductor laser is achieved by changing the repetition frequency of the current pulse injected into the semiconductor laser. Hereinafter, the "repetition frequency of the pulsed light output from the semiconductor laser" will sometimes be simply referred to as the "repetition frequency of the pulsed light".

[0047] Pulsed light output from a semiconductor laser is incident on an optical fiber amplifier 12 and amplified within the optical fiber amplifier 12. When the excitation output of the optical fiber amplifier 12 remains constant regardless of the repetition frequency of the pulsed light, the output characteristics of the pulse amplification light L1 amplified within the optical fiber amplifier 12—that is, the average output and pulse energy of the pulse amplification light L1—change with the repetition frequency of the pulsed light incident on the optical fiber amplifier 12.

[0048] On the other hand, the beam propagation of the pulsed amplified light L1 output from the fiber amplifier 12, which is amplified in the fiber amplifier 12, is determined by the propagation mode of the optical fiber constituting the fiber amplifier 12. For the amplification of pulsed light used in microfabrication, single-mode optical fiber is used in the fiber amplifier 12. Therefore, the optical fiber constituting the fiber amplifier 12 has only one propagation mode. Therefore, the beam propagation of the pulsed amplified light L1 output from the fiber amplifier 12 does not remain constant regardless of the repetition frequency of the pulsed light incident on the fiber amplifier 12.

[0049] Next, the response of pulse amplified light L1, which has different characteristics such as average output and pulse energy, from the fiber amplifier 12, when incident on a solid-state amplifier 13 whose excitation output is fixed to a certain value will be explained.

[0050] First, consider the case where the average output of the pulse amplification light L1 emitted from the fiber amplifier 12 changes due to the change in the repetition frequency of the pulse light output from the semiconductor laser. When the high repetition pulse light with a repetition frequency of 100kHz or higher is amplified by the solid-state amplifier 13, the average output of the pulse amplification light L1 amplified in the solid-state amplifier 13 depends on the average output of the pulse light incident on the solid-state amplifier 13.

[0051] Therefore, due to the change in the repetition frequency of the pulse light output from the semiconductor laser, when the average output of the incident pulse amplification light incident from the fiber amplifier 12 to the solid-state amplifier 13 changes, the average output of the amplified pulse amplification light L1 in the solid-state amplifier 13 changes with the change in the repetition frequency of the pulse light output from the semiconductor laser.

[0052] That is, when the repetition frequency of the pulsed light incident on the optical fiber amplifier 12 from the semiconductor laser is changed, the average output of the pulse amplification light L1, which is amplified in the optical fiber amplifier 12, will change. Next, when the average output of the pulse amplification light L1 incident on the solid-state amplifier 13 from the optical fiber amplifier 12 changes, the average output of the pulse amplification light L1 amplified in the solid-state amplifier 13 will change.

[0053] Furthermore, the extracted output during the amplification of the incident pulse amplified light in the solid-state amplifier 13 varies depending on the repetition frequency of the incident pulse amplified light. The extracted output is the difference between the output of the pulse amplified light L1 after the incident pulse amplified light in the solid-state amplifier 13 is amplified and the output of the incident pulse amplified light before amplification in the solid-state amplifier 13. When the extracted output changes, the thermal lensing effect occurring in the solid-state amplifier 13 will also change.

[0054] The change in the thermal lensing effect of the solid-state amplifier 13 will cause a change in the beam propagation of the emitted pulse amplification light, which is the emitted pulse amplification light L1 amplified by the solid-state amplifier 13. Therefore, the beam propagation of the emitted pulse amplification light after being amplified by the solid-state amplifier 13 changes due to the change in the repetition frequency of the pulse light output from the semiconductor laser.

[0055] The change in the thermal lensing effect that occurs in the solid-state amplifier 13 due to the change in the repetition frequency of the pulsed light output from the semiconductor laser does not end instantaneously; it takes several seconds to several minutes for the change to end. Therefore, when the repetition frequency of the pulsed light is changed, the change in the beam propagation of the emitted pulse amplification light emitted from the solid-state amplifier 13 takes several seconds to several minutes for the change to end.

[0056] Next, consider the case where the pulse energy of the pulse amplification light L1 emitted from the fiber amplifier 12 changes due to the change in the repetition frequency of the pulse light output from the semiconductor laser.

[0057] In the solid-state amplifier 13, when pulsed light with a pulse width of less than tens of picoseconds is amplified to tens of W levels that can be used for processing, the nonlinear effects occurring in the solid-state amplifier 13 become unavoidable. The nonlinear effects that are particularly worrying are stimulated Raman scattering (SRS) and the optical Kerr effect.

[0058] Stimulated Raman scattering is a phenomenon in which the wavelength of the amplified light is shifted to a different wavelength due to scattering. In the solid-state amplifier 13, when stimulated Raman scattering occurs, the output of the amplified pulsed amplified light L1 decreases, and the output of the emitted pulsed amplified light from the solid-state amplifier 13 also decreases.

[0059] The optical Kerr effect is a phenomenon where the refractive index of a medium is modulated by the intensity distribution of the pulsed light. When the intensity distribution of the pulsed light incident on the solid-state amplifier 13 is Gaussian, the solid active medium in the solid-state amplifier 13 forms a Gaussian refractive index distribution, which changes the beam propagation of the amplified pulsed light L1. These nonlinear effects occurring in the solid-state amplifier 13 are dependent on the peak intensity of the pulsed light. That is, when amplifying pulsed light with a pulse width of several picoseconds or less in the solid-state amplifier 13 to the tens of W level that can be used for processing, the stimulated Raman scattering and optical Kerr effect that occur are dependent on the peak intensity of the pulsed light.

[0060] In a pulsed light with a certain pulse width, the peak intensity is dependent on the pulse energy. Therefore, the so-called change in the pulse energy of the pulse amplified light L1 emitted from the fiber amplifier 12 due to the change in the repetition frequency of the pulsed light means that the output of the pulse amplified light L1 emitted from the solid-state amplifier 13 and the characteristics of beam propagation change due to the change in the repetition frequency of the pulsed light.

[0061] The change in the pulse light's characteristics due to the nonlinear effect occurring in the solid-state amplifier 13, caused by the change in the pulse light's repetition frequency, is considered to end instantaneously. However, due to the change in the pulse light's characteristics caused by the nonlinear effect, and the change induced by the thermal lensing effect of the solid-state amplifier 13, it takes several seconds to several minutes for the beam propagation characteristics of the pulse amplification light L1 emitted from the solid-state amplifier 13 to stabilize.

[0062] Furthermore, in the above explanation, it is assumed that the excitation output of the solid-state amplifier 13 does not remain constant due to changes in the repetition frequency of the pulsed light. If a change in the repetition frequency of the corresponding pulsed light causes a change in the excitation output of the solid-state amplifier 13, due to the thermal state change occurring within the solid-state amplifier 13, it will undoubtedly take approximately several seconds to several minutes for the output characteristics and beam conduction characteristics of the pulsed amplified light L1 emitted from the solid-state amplifier 13 to stabilize, just as described above.

[0063] Therefore, in both cases, the output characteristics of the pulse amplification light L1 emitted from the solid-state amplifier 13 and the beam conduction characteristics will take several seconds to several minutes to stabilize. Whether the excitation output of the solid-state amplifier 13 remains constant due to the change in the repetition frequency of the pulse light, or changes in the repetition frequency of the pulse light, the output characteristics of the pulse amplification light L1 emitted from the solid-state amplifier 13 and the beam conduction characteristics will stabilize.

[0064] Figure 3 is a characteristic graph showing the experimental results of measuring the output characteristics of the pulsed amplified light emitted from the laser oscillator when the repetition frequency of the pulsed light is switched in the laser oscillator according to Embodiment 1. Figure 3 shows the average output and time variation of the pulsed amplified light L1 emitted from the laser oscillator 10 when the repetition frequency of the pulsed light is switched in the laser oscillator 10. The output characteristics of the pulsed amplified light L1 emitted from the laser oscillator 10 can be described in other words as the output characteristics of the pulsed amplified light L1 emitted from the solid-state amplifier 13.

[0065] The horizontal axis of Figure 3 displays time. In the horizontal axis of Figure 3, the moment when the repetition frequency is changed is set to 0 minutes. The left axis of Figure 3 displays the variation (%) of the average output of the pulse amplification light L1, which is the output characteristic of the pulse amplification light L1 emitted from the solid-state amplifier 13. The right axis of Figure 3 displays the variation (%) of the beam diameter of the pulse amplification light L1, which is the output characteristic of the pulse amplification light L1. In the variation (%) of the average output and the variation (%) of the beam diameter, the value of the moment when the repetition frequency is changed is set to 100%.

[0066] According to the results of this experiment, it takes two seconds for the average output of the pulsed amplified light L1 emitted from the solid-state amplifier 13 to stabilize. In addition, it takes 180 seconds for the beam diameter of the pulsed amplified light L1 emitted from the solid-state amplifier 13 to stabilize.

[0067] Furthermore, the output characteristics of the pulsed amplified light L1 emitted from the solid-state amplifier 13 in this experiment will be evaluated using the average output power. The average output of the pulsed amplified light L1 is the pulse energy of the pulsed amplified light L1 multiplied by the repetition frequency. Therefore, regarding the pulse energy, if the moving average of the complex pulses is evaluated in the same way as described above, the same trend will be observed.

[0068] Figure 4 is a characteristic graph showing the average output, pulse energy, and beam diameter of the pulse amplified light emitted from the laser oscillator when the repetition frequency of the pulse light is switched in the laser oscillator according to Embodiment 1. In Figure 4, the time variation of the average output, pulse energy, and beam diameter of the pulse amplified light L1 emitted from the laser oscillator 10 is shown when the repetition frequency of the pulse light in the laser oscillator 10 is switched. The pulse energy of the pulse amplified light L1 here is calculated by dividing the measured result of the average output of the pulse amplified light L1 by the repetition frequency. The horizontal axis of Figure 4 shows time. In the horizontal axis of Figure 4, the time of changing the repetition frequency is set to 0 minutes. The left axis of Figure 4 shows the variation (%) of the average output of the pulse amplified light L1 as an output characteristic of the pulse amplified light L1 emitted from the solid-state amplifier 13, and the variation (%) of the pulse energy of the pulse amplified light L1. The right axis of Figure 4 shows the variation (%) of the beam diameter of the pulse amplified light L1 as an output characteristic of the pulse amplified light L1. In the average output variation (%), pulse energy variation (%), and beam diameter variation (%) of the pulse amplification light L1, the value of the time when the repetition frequency changes is 100%.

[0069] As explained above, when the repetition frequency of the pulsed light L output from the seed light source 11 is changed, the output characteristics and beam conduction characteristics of the pulsed amplified light L1 emitted from the solid-state amplifier 13 change over time. Therefore, when the repetition frequency of the pulsed amplified light L1 output from the laser oscillator 10 is changed, the output characteristics and beam conduction characteristics of the pulsed amplified light L1 output from the laser oscillator 10 change over time.

[0070] Next, the impact on processing caused by the change in the characteristics of the pulse amplification light L1 output from the laser oscillator 10 over time as the repetition frequency of the pulse light changes will be explained. Because the repetition frequency of the pulse light changes, the characteristics of the pulse amplification light L1 output from the laser oscillator 10 change over time. At the processing point after the change in the repetition frequency, the intensity distribution of the pulse amplification light L1 varies with time, making the processing quality unstable and difficult to maintain a certain processing quality after the change in the repetition frequency. At this time, in order to stabilize the processing quality, processing needs to be interrupted after the change in the repetition frequency of the pulse light until the characteristics of the pulse amplification light L1 stabilize, resulting in reduced productivity.

[0071] In the configuration of the laser processing apparatus 1 according to Embodiment 1, the intensity distribution of the pulse amplification light L1 at the processing point is determined by the mask 50. Therefore, in order to stabilize the processing quality, it is effective to stabilize the intensity distribution of the pulse amplification light L1 on the mask 50 in the laser processing apparatus 1.

[0072] The intensity distribution of the pulse amplification light L1 on the mask 50 is determined by factors such as the pulse width, pulse energy, beam diameter, and beam shape of the pulse amplification light L1 on the mask 50. Among these factors, the pulse energy, beam diameter, and beam shape of the pulse amplification light L1 on the mask 50 are factors whose repetition frequency of the pulse light changes over time. Furthermore, among these, the pulse energy of the pulse amplification light L1 has a particularly significant impact on the processing in the mask transcribing process of the laser processing apparatus 1. That is, the pulse energy of the pulse amplification light L1 on the mask 50 has a particularly significant impact on the intensity distribution of the pulse amplification light L1 on the mask 50 due to the change in the repetition frequency of the pulse light over time.

[0073] Here, regarding the aforementioned issue, in the laser processing apparatus 1, the transmittance of the optical switching element 30, which is arranged in the optical path of the pulse amplification light L1 between the laser oscillator 10 and the shield 50, is modulated so that the pulse energy of the pulse amplification light L1 on the shield 50 after the change of the pulse repetition frequency remains constant before and after the change of the pulse repetition frequency. Here, "constant" means that the change in the pulse energy of the pulse amplification light L1 before and after the change of the pulse repetition frequency is within a predetermined range.

[0074] Therefore, in the laser processing apparatus 1, when the repetition frequency of the pulse light is changed, the pulse energy of the pulse amplification light L1 irradiating the mask 50 can be suppressed from changing over time. That is, in the laser processing apparatus 1, the pulse energy of the pulse amplification light L1 irradiating the mask 50 can be suppressed from changing over time before and after the repetition frequency of the pulse light is changed. Therefore, even if the repetition frequency of the pulse light is changed, the laser processing apparatus 1 can stabilize the intensity distribution of the pulse amplification light L1 at the processing point, and can maintain a certain processing quality and stabilize the processing quality.

[0075] Next, the method for modulating the transmittance of the pulse amplification light L1 in the optical switching element 30 of the laser processing apparatus 1 will be explained. Hereinafter, we will focus on explaining how to suppress the variation in pulse energy of the pulse amplification light L1 on the mask 50 when the repetition frequency of the pulse light is changed. As described above, the change in pulse energy of the pulse amplification light L1 emitted from the fiber amplifier 12 due to the change in the repetition frequency of the pulse light refers to the change in the output characteristics and beam conduction characteristics of the pulse amplification light L1 emitted from the solid-state amplifier 13 due to the change in the repetition frequency of the pulse light.

[0076] As the repetition frequency of the pulse light changes, the pulse energy of the pulse amplification light L1 emitted from the laser oscillator 10 changes, as shown in Figure 4. It can be divided into a component with a short time constant and a component with a long time constant. The component with a short time constant changes instantaneously with the change of the repetition frequency of the pulse light, while the component with a long time constant changes over time with the change of the repetition frequency of the pulse light.

[0077] At this time, the component with a short time constant that accompanies the change in the repetition frequency of the pulse light is the component whose pulse energy variation amplitude within a predetermined time range is above a predetermined threshold. The component with a long time constant that accompanies the change in the repetition frequency of the pulse light is the component whose pulse energy variation amplitude within a predetermined time range does not reach the predetermined threshold.

[0078] In the average output pulse energy graph of Figure 4, the component that rises almost vertically after time 0 minutes is the component with a short time constant that changes instantaneously. Additionally, in the average output pulse energy graph of Figure 4, the component that changes from time 0 minutes up to time 10 minutes is the component with a long time constant that changes over time.

[0079] Regarding the component with a short time constant, before and after the change in the repetition frequency of the pulsed light, the transmittance of the light-switching element 30 is modulated so that the transmittance of the pulsed amplified light L1 illuminating the mask 50 is constant. Here, "constant" means that the change in the transmittance of the pulsed amplified light L1 in the mask 50 before and after the change in the repetition frequency of the pulsed light is within a predetermined range.

[0080] The pulsed amplified light L1 of the transmissive light switching element 30 is incident on the beam guiding adjustment unit 40 along the optical axis La of the pulsed amplified light L1, and then illuminates the shield 50. The transmittance of the light switching element 30 is modulated according to the signal transmitted from the control unit 20.

[0081] In addition, the transmittance of the mask 50 is obtained by the following mathematical formula (1) before and after the change of the repetition frequency of the pulse light.

[0082] (Pulse energy of pulse amplification light L1 after transmission masking) / (Pulse energy of pulse amplification light L1 before transmission masking) …(1).

[0083] When the intensity distribution of the pulse amplified light L1 before the transmission shield 50 is Gaussian, the transmittance of the shield 50 affects not only the pulse energy of the pulse amplified light L1 after the transmission shield 50, but also the beam shape of the pulse amplified light L1 after the transmission shield 50. The higher the transmittance of the shield 50, the closer the beam shape of the pulse amplified light L1 after the transmission shield 50 is to the original Gaussian distribution, that is, the Gaussian distribution of the pulse amplified light L1 before the transmission shield 50. In addition, the lower the transmittance of the shield 50, the closer the beam shape of the pulse amplified light L1 after the transmission shield 50 is to a top-hat distribution.

[0084] Therefore, in order to stabilize the processing quality of the laser processing apparatus 1, it is necessary to make the transmittance of the mask 50 almost the same before and after the change of the repetition frequency of the pulse light.

[0085] Regarding the components with short time constants, the modulation of the transmittance of the optical switching element 30 is performed individually based on a predetermined transmittance modulation method, before and after the change of the pulse light repetition frequency, corresponding to the repetition frequency pairing. The transmittance modulation method is the method by which the control unit 20 modulates the transmittance of the optical switching element 30.

[0086] Regarding the transmittance modulation method for components with short time constants, the pairing of different repetition frequencies is determined before and after the change of the pulse light's repetition frequency, so that the transmittance in the mask 50 irradiating the pulse amplified light L1 is constant. The transmittance modulation method is stored in the control unit 20. Hereinafter, the pairing of repetition frequencies before and after the change of the pulse light's repetition frequency will sometimes be simply referred to as "repetition frequency pairing".

[0087] Based on the transmittance modulation method corresponding to the repetition frequency, the control unit 20 controls the transmittance of the optical switching element 30 to keep the transmittance in the mask 50 of the pulse amplification light L1 constant before and after the change of the repetition frequency of the pulse light.

[0088] When determining the transmittance modulation method, transmittance data in the mask 50 of the pulse amplification light L1 is obtained for various repetition frequency pairs before and after the change of the pulse light repetition frequency. Next, for each of the various repetition frequency pairs, a transmittance modulation method is determined based on the obtained data, making the transmittance in the mask 50 of the pulse amplification light L1 illuminating the mask 50 a certain.

[0089] However, when the beam diameter of the pulse amplification light L1 on the mask 50 increases due to the change in the repetition frequency of the pulse light, the modulation of the transmittance of the optical switching element 30 alone may not be able to maintain a constant transmittance in the mask 50 of the pulse amplification light L1 before and after the change in the repetition frequency of the pulse light.

[0090] At this time, in addition to modulating the transmittance of the optical switching element 30, compensation is also performed for the beam diameter of the pulsed amplified light L1 after the transmission of the optical switching element 30. The compensation for the beam diameter of the pulsed amplified light L1 after the transmission of the optical switching element 30 is performed by moving the optical element, which is a component of the beam conduction adjustment unit 40, in the direction of the optical axis La of the pulsed amplified light L1 output from the optical switching element 30 via the drive device 41 included in the beam conduction adjustment unit 40.

[0091] That is, the laser processing apparatus 1 modulates the transmittance of the optical switching element 30 and compensates for the beam diameter of the pulsed amplified light L1 emitted from the optical switching element 30 and irradiating the mask 50, so that the transmittance in the mask 50 of the pulsed amplified light L1 remains constant before and after the repetition frequency is changed. The method of moving the optical element of the beam conduction adjustment unit 40 by the drive device 41 will be described later.

[0092] Regarding the component with a long time constant, the transmittance of the optical switching element 30 is modulated over time, so that the pulse energy of the pulse amplification light L1 after the repetition frequency of the pulse light is changed remains constant. Here, "constant" means that the variation in the pulse energy of the pulse amplification light L1 after the repetition frequency of the pulse light is changed is within a predetermined range. In this case, the method for modulating the transmittance of the optical switching element 30 is as follows:

[0093] The first transmittance modulation method is to apply a predetermined transmittance modulation mode to the optical switching element 30 individually, corresponding to the pairing of repetition frequencies, before and after the change of the repetition frequency of the pulsed light. At this time, for the pairing of various repetition frequencies, time series data of the pulse energy variation of the pulse amplification light L1 emitted from the laser oscillator 10 is obtained, and the modulation mode is determined based on the time series data.

[0094] Furthermore, machine learning can also be applied when determining the modulation mode. By applying machine learning to the determination of the modulation mode, the accuracy of the modulation of the transmittance of the optical switching element 30 to maintain a certain time constant component of the pulse energy of the pulse amplification light L1 can be improved after the repetition frequency of the pulse light is changed. In addition, by applying machine learning when determining the modulation mode, even for repetition frequency pairings for which experimental data is not available, the modulation mode of the optical switching element 30 to maintain a certain time constant component of the pulse energy of the pulse amplification light L1 after the repetition frequency of the pulse light is changed can be predicted.

[0095] The second transmittance modulation method involves placing a photosensor 90 at the rear end of the mask 50 to measure the pulse energy of the pulse amplified light L1, and dynamically modulating the transmittance of the optical switching element 30 based on the pulse energy data of the pulse amplified light L1 measured through the photosensor 90. Figure 5 is a block diagram schematically showing an example of the configuration of a photosensor installed on a laser processing apparatus including a laser device according to Embodiment 1.

[0096] The photosensor 90 receives the pulsed amplified light L1 from the transmission shield 50 and measures the pulse energy of the pulsed amplified light L1. The photosensor 90 transmits the pulse energy data of the pulsed amplified light L1, as a measurement result, to the control unit 20. The photosensor 90 includes components such as a photodiode that operates as a light-receiving unit.

[0097] At this time, the control unit 20 dynamically feeds back and controls the transmittance of the optical switching element 30 based on the measurement results of the photosensitive sensor 90.

[0098] In Figure 5, reflectors 91a and 91b, and a light sensor 90 are disposed between the mask 50 and the scanning unit 60. The light sensor 90 is disposed on the back of the reflector 91a, that is, on the light transmission side of the reflector 91a.

[0099] A portion of the pulsed amplified light L1 of the transmission shield 50 is incident on the transmission mirror 91a and the light sensor 90. The light sensor 90 receives the pulsed amplified light L1 from the transmission mirror 91a and measures the pulse energy of the pulsed amplified light L1.

[0100] The remaining portion of the pulse amplification light L1 of the transmission shield 50 is reflected by the reflector 91a and incident on the reflector 91b, and is reflected by the reflector 91b and incident on the scanning unit 60.

[0101] Furthermore, the position of the light sensor 90 can be in the rear section of the mask 50, and is not limited to the position between the mask 50 and the scanning unit 60. For example, the light sensor 90 can be disposed in the rear section of the mask 50 at the back of the transmission mirror that transmits the pulse amplified light L1, and can measure the position of the transmitted light of the pulse amplified light L1 that passes through the transmission mirror. In addition, the light sensor 90 can be in the rear section of the mask 50, for example, to measure the position of the scattered reflected light of the pulse amplified light L1 reflected from the front of the transmission mirror that transmits the pulse amplified light L1, or in the rear section of the mask 50, to measure the position of the scattered reflected light reflected from the surface of the lens that transmits the pulse amplified light L1.

[0102] In either of the first or second transmittance modulation methods described above, if the change in pulse amplification light L1 after the pulse repetition frequency change becomes negligible in terms of processing quality over time, the transmittance modulation of the optical switching element 30 can be terminated. That is, the control unit 20 terminates the transmittance modulation of the optical switching element 30 when the change in pulse amplification light L1 after the pulse repetition frequency change is considered negligible in terms of processing quality and is within a predetermined range.

[0103] The laser processing apparatus 1 modulates the transmittance of the optical switching element 30 as described above, and controls it so that the transmittance in the mask 50 of the pulse amplification light L1 remains constant before and after the repetition frequency change, thereby stabilizing the intensity distribution of the pulse amplification light L1 on the mask 50 before and after the repetition frequency change.

[0104] Furthermore, in the above, the focus is on explaining how to suppress the variation of pulse energy of the pulse amplification light L1 on the mask 50 when the repetition frequency of the pulse light is changed. As the repetition frequency of the pulse light changes, the variation of the average output of the pulse amplification light L1 emitted from the laser oscillator 10 can also be divided into a component with a short time constant and a component with a long time constant, as shown in Figure 3. The component with a short time constant changes instantaneously with the change of the repetition frequency of the pulse light, while the component with a long time constant changes over time with the change of the repetition frequency of the pulse light.

[0105] Therefore, the change in the average output of the pulse amplification light L1 on the mask 50 when the repetition frequency of the pulse light is changed can be suppressed in the same way as the change in the pulse energy of the pulse amplification light L1 on the mask 50 when the repetition frequency of the pulse light is changed by modulating the transmittance of the optical switching element 30. Therefore, even if the repetition frequency of the pulse light is changed, the laser processing apparatus 1 can stabilize the intensity distribution of the pulse amplification light L1 at the processing point, thereby maintaining a certain processing quality and stabilizing the processing quality.

[0106] Next, the method of moving the optical element of the beam conduction adjustment unit 40 via the drive device 41 will be explained. According to Figure 4, similar to the change in pulse energy, as the repetition frequency of the pulse light changes, the change in the beam diameter of the pulse amplification light L1 emitted from the laser oscillator 10 can be divided into a component with a short time constant and a component with a long time constant. The component with a short time constant changes instantaneously with the change in the repetition frequency of the pulse light, while the component with a long time constant changes over time with the change in the repetition frequency of the pulse light.

[0107] At this time, the component with a short time constant that changes instantaneously with the change in the repetition frequency of the pulsed light is the component whose beam diameter variation within a predetermined time range is above a predetermined threshold. The component with a long time constant that changes over time with the change in the repetition frequency of the pulsed light is the component whose beam diameter variation within a predetermined time range does not reach the predetermined threshold.

[0108] In the beam diameter diagram of Figure 4, the component that moves almost vertically upwards after time 0 minutes is a component with a short time constant that changes instantaneously. In addition, in the beam diameter diagram of Figure 4, the component that changes from time 0 minutes upwards until time 10 minutes is a component with a long time constant that changes with time.

[0109] Regarding the component with a short time constant, before and after the change in the repetition frequency of the pulsed light, the change in the beam diameter of the pulsed amplification light L1 emitted from the optical switching element 30 is compensated to keep the beam diameter of the pulsed amplification light L1 constant. Here, "constant" means that the change in the beam diameter of the pulsed amplification light L1 before and after the change in the repetition frequency of the pulsed light is within a predetermined range.

[0110] Compensation for beam diameter variations in components with short time constants is performed based on a predetermined driving mode of the driving device 41. Before and after the change of the pulse light repetition frequency, the driving mode of the driving device 41 for the components with short time constants is determined for each pairing of different repetition frequencies, so that the beam diameter of the pulse amplification light L1 after the change of the pulse light repetition frequency remains constant, and the driving mode of the driving device 41 is stored in the control unit 20.

[0111] Based on the driving method of the drive device 41 paired with the repetition frequency, the control unit 20 compensates for the short time constant component of the beam diameter of the pulse amplified light L1 illuminating the mask 50 by moving the optical element of the beam conduction adjustment unit 40 through the drive device 41. In this way, the control unit 20 controls the beam diameter of the pulse amplified light L1 on the mask 50 to remain constant before and after the repetition frequency change, and maintains the transmittance of the pulse amplified light L1 in the mask 50 to remain constant before and after the repetition frequency change.

[0112] When determining the driving mode of the driving device 41, before and after the change of the repetition frequency of the pulsed light, data on the change in beam diameter of the pulsed amplified light L1 emitted from the optical switching element 30 is obtained for each pair of repetition frequencies. Next, for each pair of repetition frequencies, the driving mode of the driving device 41 that compensates for the change in beam diameter of the pulsed amplified light L1 emitted from the optical switching element 30 is determined based on the obtained data.

[0113] Furthermore, machine learning can also be applied when determining the driving mode of the drive device 41. That is, machine learning can be performed by using data on the beam diameter variation of the paired pulse amplification light L1 for various repetition frequencies as learning data to generate a trained model for inferring the driving mode of the drive device 41, and the driving mode of the drive device 41 can be inferred using the trained model. The inferred driving mode of the drive device 41 is stored in the control unit 20. The above-mentioned machine learning and inference of the driving mode of the drive device 41 can be performed in the control unit 20 or in other machines.

[0114] By applying machine learning in determining the driving mode of the driving device 41, it becomes possible to improve the accuracy of the driving mode of the driving device 41, which is to keep the variation amplitude of the beam diameter of the pulse amplification light L1 after the repetition frequency of the pulse light is changed constant. In addition, by applying machine learning in determining the driving mode of the driving device 41, it is also possible to predict the driving mode of the driving device 41 by matching the repetition frequency for which experimental data has not been obtained.

[0115] Regarding the component with a long time constant, in order to keep the beam diameter of the pulse amplification light L1 constant after the change of the repetition frequency of the pulse light, the change in the beam diameter of the pulse amplification light L1 emitted from the optical switching element 30 is compensated. Here, "constant" means that the change in the beam diameter of the pulse amplification light L1 before and after the change of the repetition frequency of the pulse light is within a predetermined range.

[0116] Compensation for beam diameter variation in components with long time constants is performed based on a pre-determined driving mode of the driving device 41. The driving mode of the driving device 41 for components with long time constants is determined using the same method as for components with short time constants. The driving mode of the driving device 41 is stored in the control unit 20.

[0117] The control unit 20, based on the driving mode of the driving device 41 paired with the repetition frequency, moves the optical element of the beam conduction adjustment unit 40 by the driving device 41 to compensate for the long component of the time constant of the beam diameter of the pulse amplified light L1 irradiating the mask 50, so that the transmittance of the pulse amplified light L1 in the mask 50 is maintained at a constant.

[0118] Based on the driving method of the drive device 41 paired with the repetition frequency, the control unit 20 compensates for the short time constant component of the beam diameter of the pulse amplified light L1 illuminating the mask 50 by moving the optical element of the beam conduction adjustment unit 40 through the drive device 41. In this way, the control unit 20 controls the beam diameter of the pulse amplified light L1 on the mask 50 to remain constant before and after the repetition frequency change, and maintains the transmittance of the pulse amplified light L1 in the mask 50 to remain constant before and after the repetition frequency change.

[0119] Alternatively, a beam diameter monitor 92 for measuring the beam diameter of the pulse amplified light L1 can be disposed at the rear end of the beam conduction adjustment section 40, and the drive device 41 controls the movement of the optical elements of the beam conduction adjustment section 40 so that the beam diameter of the pulse amplified light L1 measured by the beam diameter monitor 92 is kept constant.

[0120] The beam diameter monitor 92 receives the pulsed amplified light L1 through the beam conduction adjustment unit 40 and measures the beam diameter of the pulsed amplified light L1. The beam diameter monitor 92 transmits the beam diameter data of the pulsed amplified light L1, as a measurement result, to the control unit 20. The beam diameter monitor 92 may include, for example, a camera using an image sensor such as a charge-coupled device (CCD) sensor and a complementary metal-oxide-semiconductor (CMOS) sensor.

[0121] At this time, the control unit 20 dynamically controls the movement of the optical element of the beam conduction adjustment unit 40 based on the measurement results in the beam diameter monitor 92.

[0122] Figure 6 is a block diagram schematically showing one example of the configuration of a laser processing apparatus including a laser device according to Embodiment 1, in which a beam diameter monitor is installed. In Figure 6, reflectors 93a and 93b and a beam diameter monitor 92 are disposed between the beam conduction adjustment section 40 and the shield 50. The beam diameter monitor 92 is disposed on the back of the reflector 93a, that is, on the light transmission side of the reflector 93a.

[0123] One part of the pulse amplified light L1 of the transmitted beam conduction adjustment unit 40, and the incident beam diameter monitor 92 of the transmission mirror 93a. The beam diameter monitor 92 receives the pulse amplified light L1 from the transmission mirror 93a and measures the beam diameter of the pulse amplified light L1.

[0124] The remaining portion of the pulse amplification light L1 of the transmitted beam conduction adjustment section 40 is reflected by the reflector 93a and incident on the reflector 93b, and is reflected by the reflector 93b and incident on the shield 50.

[0125] As described above, the control unit 20 compensates for the short time constant component of the pulse amplification light L1 emitted from the optical switching element 30 based on the driving mode of the driving device 41 paired with the corresponding repetition frequency, so that the beam diameter of the pulse amplification light L1 remains constant before and after the change of the pulse light repetition frequency. Furthermore, the control unit 20 compensates for the long time constant component of the pulse amplification light L1 emitted from the optical switching element 30 based on the driving mode of the driving device 41 paired with the corresponding repetition frequency, so that the beam diameter of the pulse amplification light L1 remains constant after the change of the pulse light repetition frequency.

[0126] Therefore, the laser processing apparatus 1 can be controlled to keep the beam diameter of the pulse amplification light L1 on the mask 50 constant before and after the repetition frequency change, thereby stabilizing the intensity distribution of the pulse amplification light L1 on the mask 50.

[0127] The laser processing apparatus 1 can control the movement of the optical element of the beam conduction adjustment unit 40 as described above, so that the beam diameter of the pulse amplification light L1 on the mask 50 is kept constant before and after the repetition frequency change, and the intensity distribution of the pulse amplification light L1 on the mask 50 is stabilized before and after the repetition frequency change.

[0128] Furthermore, in stabilizing the processing quality, the drive device 41 ensures that the wavefront state of the pulse amplification light L1 on the mask 50 remains unchanged before and after the repetition frequency change. In other words, even if the divergence or convergence state of the wavefront of the pulse amplification light L1 remains unchanged, the moving beam transmission adjustment unit 40 is effective. When the thickness of the object W being processed is greater than a specific thickness, the taper angle of the groove or hole formed by the processing will change because the wavefront state of the pulse amplification light L1 at the processing point is either divergent or convergent. Since the taper angle is an important evaluation item that determines the processing quality, it is preferable that it remains constant regardless of the change in the repetition frequency of the pulse light.

[0129] Therefore, by controlling the position of the beam conduction adjustment unit 40, the laser processing apparatus 1 ensures that the wavefront state of the pulse amplification light L1 at the processing point does not change before and after the repetition frequency change, and that the wavefront state of the pulse amplification light L1 on the mask 50 does not change before and after the repetition frequency change.

[0130] Figure 7 shows the characteristic graph of the result of calculating the set transmittance modulation mode when the average output after changing the repetition frequency of the pulsed light changes over time in the experiment shown in Figure 3, through transmittance modulation compensation of the optical switch element 30. The horizontal axis of Figure 7 displays time. In the horizontal axis of Figure 7, the time of changing the repetition frequency is set to 0 minutes. The left axis of Figure 7 displays the transmittance (%) of the optical switch element in the transmittance modulation mode. The right axis of Figure 7 displays the average output (%) of the pulsed amplified light L1 transmitted by the optical switch element. In the transmittance (%) of the optical switch element in the transmittance modulation mode and the average output (%) of the pulsed amplified light L1 transmitted by the optical switch element, the value of the time of changing the repetition frequency is set to 100%.

[0131] As shown in Figure 7, by modulating the transmittance of the optical switch element 30 using a transmittance modulation method, the variation in the average output (%) of the pulse amplified light L1 after transmission from the optical switch element is less compared to the case in Figure 3. In other words, it can be said that when the average output or pulse energy of the pulse amplified light L1 emitted from the laser oscillator 10 changes over time due to the change in repetition frequency, the average output can be kept approximately constant by modulating the transmittance of the optical switch element 30. Furthermore, regarding the change in the beam diameter of the pulse amplified light L1 over time after the repetition frequency change, it is assumed that this is compensated by the beam conduction adjustment unit 40.

[0132] According to the laser device 100 of Embodiment 1 described above, a laser device including a seed light source, an amplifier, a shield, an optical switch element, and a beam conduction adjustment unit is implemented. The seed light source outputs pulsed laser light and the repetition frequency of the pulsed laser light can be controlled. The amplifier amplifies and outputs pulsed laser light. The shield shapes at least one of the beam diameter and beam shape of the pulsed laser light output from the amplifier. The optical switch element is disposed in the optical path between the amplifier and the shield to modulate the transmittance so that at least one of the output and energy of the pulsed laser light output from the amplifier, which occurs with the change of the repetition frequency of the pulsed laser light, changes over time within a predetermined range. The beam conduction adjustment unit is disposed in the optical path between the amplifier and the shield to adjust the beam conduction of the pulsed laser light output from the amplifier.

[0133] As described above, in the laser processing apparatus 1 according to Embodiment 1, the optical switching element 30 modulates the transmittance so that, as the repetition frequency of the pulsed light changes, at least one of the output and energy of the pulsed amplified light L1 amplified by the fiber amplifier 12 and the solid-state amplifier 13 varies over time within a predetermined range. Therefore, even if the repetition frequency of the pulsed light changes, the laser processing apparatus 1 can stabilize the intensity distribution of the pulsed amplified light L1 at the processing point, thus maintaining a constant processing quality and stabilizing the processing quality.

[0134] Furthermore, the laser processing apparatus 1 is disposed in the optical path between the solid-state amplifier 13 and the shield 50, and includes a beam conduction adjustment unit 40 for adjusting the beam conduction of the pulse amplification light L1 emitted from the solid-state amplifier 13. By moving the optical elements constituting the beam conduction adjustment unit 40, the laser processing apparatus 1 can stabilize the processing quality by manipulating at least one of the beam diameter and wavefront of the pulse amplification light L1 on the shield 50.

[0135] Therefore, according to the laser apparatus 100 and laser processing apparatus 1 of Embodiment 1, the output characteristics and beam conduction characteristics of the amplified pulsed laser light L1, which are generated by the change in the repetition frequency of the seed light source 11, can be suppressed over time. Furthermore, the laser processing apparatus 1 can suppress the changes in the average output, pulse energy, beam diameter, and beam shape of the processing point over time after the change in the repetition frequency of the pulsed light. Finally, the laser processing apparatus 1 can immediately stabilize the processing quality after the change in the repetition frequency of the pulsed light output from the seed light source 11, thereby improving processing productivity.

[0136] Example 2. In the wiring substrate of electronic components or integrated circuits (ICs), it is sometimes necessary to process holes of different multiple apertures within a wiring substrate. When processing different multiple apertures with the same laser processing equipment, when processing holes with relatively small apertures, the beam diameter of the pulsed laser light at the processing point is relatively small, and when processing holes with relatively large apertures, the beam diameter of the pulsed laser light at the processing point is relatively large.

[0137] In the material of the object to be processed, there is an inherent processing threshold for the irradiated laser light. In order to perform stable laser processing, it is necessary to irradiate laser light with characteristics such as energy exceeding the processing threshold. The processing threshold is the minimum characteristic value of the laser light at the beginning of the decomposition of the object to be processed when the laser light irradiates it. When the processing threshold is set to Fth and the aperture is r, the minimum energy Eth of the laser light required for processing is expressed by the following mathematical formula (2).

[0138] Eth = πr2Fth…(2).

[0139] The processing threshold Fth is a fixed value determined by the material. Therefore, the minimum laser energy Eth required for processing the object increases as the aperture r increases. That is, the larger the processing aperture, the greater the laser energy required for processing.

[0140] Generally, pulsed laser light emitted from a pulsed laser oscillator has the property that the lower the repetition frequency, the greater the pulse energy. Based on this characteristic, when performing hole-making through pulsed laser light, the smaller hole diameter portion can be processed at a high repetition frequency with a relatively high repetition frequency, and the larger hole diameter portion can be processed at a low repetition frequency with a relatively low repetition frequency, which can be done efficiently.

[0141] Next, in a mask transcribing optical system where the beam diameter of the laser light at the processing point is determined by the opening diameter of the mask, processing can be performed efficiently by using a mask with a relatively small opening diameter when processing a relatively small aperture and a mask with a relatively large opening diameter when processing a relatively large aperture.

[0142] Figure 8 is a block diagram schematically showing an example of the configuration of a laser processing apparatus including a laser device according to Embodiment 2. The laser processing apparatus 2 according to Embodiment 2 differs from the laser processing apparatus 1 according to Embodiment 1 in that it includes a laser device 110 instead of a laser device 100. The laser device 110 also differs from the laser processing apparatus 1 according to Embodiment 1 in that it includes a mask 51 instead of a mask 50, a control unit 21 instead of a control unit 20, and a mask changer 52.

[0143] Figure 9 is a plan view showing an example of a mask including a laser processing apparatus according to Embodiment 2. The mask 51 forms a plurality of openings of different apertures as opening regions on a substrate. The mask 51 shown in Figure 9 is a circular metal plate forming a plurality of circular openings 51a. The mask 50 according to Embodiment 1 forms one opening 50a. In contrast, the mask 51 according to Embodiment 2 forms a plurality of circular openings 51a.

[0144] In the in-plane direction of the mask 51, a plurality of circular openings 51a are formed on concentric circles with the center C of the circle of the mask 51 as the center. That is, the mask 51 forms a plurality of circular openings 51a including the center on an imaginary circle V that is concentric with the circle of the mask 51.

[0145] Alternatively, the mask 51 may be constructed by embedding and fixing an opening part 51b made of a transparent material that transmits pulse amplification light L1 into the opening 51a.

[0146] The mask changer 52 rotates the mask 51 by rotating an axis perpendicular to the in-plane direction of the mask 51 and passing through the center C of the circle, thereby changing the opening 51a of the transmitted pulse amplification light L1. The mask changer 52 changes the position of the opening 51a and the opening 51a of the transmitted pulse amplification light L1, so that the optical axis La of the pulse amplification light L1 passes through the opening 51a. The drive of the mask changer 52 is controlled by the control unit 21.

[0147] In the masked transcription optical system 70, the processing point beam diameter is determined based on the opening diameter of the opening 51a of the mask 51 and the transcription magnification. The laser device 110 can change the processing point beam diameter corresponding to the aperture to be processed by changing the opening 51a through which the pulse amplification light L1 is transmitted via the mask changer 52. In addition, the laser device 110 utilizes the correlation between the pulse energy of the pulse amplification light L1 output from the laser oscillator 10 and the repetition frequency of the pulse light L output from the seed light source 11 to determine the repetition frequency of the pulse light L output from the seed light source 11 corresponding to the aperture for processing.

[0148] Accordingly, when the laser device 110 performs hole-making through pulse amplification light L1, it can use a high repetition frequency, which is a relatively high repetition frequency, to process small-diameter portions that can be processed with relatively low pulse energy at high speed. Conversely, when the laser device 110 performs hole-making through pulse amplification light L1, it can use a low repetition frequency, which is a relatively low repetition frequency, to process large-diameter portions that require relatively high energy at low speed. Therefore, the laser device 110 can efficiently process multiple types of holes with different diameters.

[0149] In addition to the functions of the control unit 20 according to Embodiment 1, the control unit 21 also includes the function of controlling the mask changer 52.

[0150] Figure 10 is a flowchart showing the sequence of hole-opening processes with different apertures in the laser processing apparatus according to Embodiment 2. Here, it is explained that in the laser processing apparatus 2, the repetition frequency of the pulse light is used as repetition frequency A to perform hole-opening processing with aperture a, and then the repetition frequency of the pulse light is changed to repetition frequency B to perform hole-opening processing with aperture b, which is a different aperture from aperture a.

[0151] First, in step S110, in the laser processing apparatus 2, the repetition frequency of the pulsed light is used as the repetition frequency A to perform hole opening processing for aperture a. After the hole opening processing for aperture a is completed, the irradiation of the pulsed amplified light L1 from the laser apparatus 110 to the workpiece W is temporarily stopped. In addition, when the laser oscillator 10 is stopped and then restarted, it takes time until a stable pulsed amplified light L1 is obtained. Therefore, even when the irradiation of the pulsed amplified light L1 from the laser apparatus 110 to the workpiece W is temporarily stopped, the pulsed amplified light L1 can continue to be generated inside the laser apparatus 110.

[0152] Examples of methods for stopping the irradiation of pulsed amplified light L1 onto the workpiece W include, for example, using the beam switching function included in the laser device 110 itself, or stopping the output of pulsed amplified light L1 from the laser device 110 by setting the transmittance of the light switching element 30 to 0%. The beam switching function is the function of switching the output of pulsed amplified light L1 from the laser device 110. Then, proceed to step S120.

[0153] In step S120, in order to perform the hole opening process of aperture b, the repetition frequency of the pulse light is changed from repetition frequency A to repetition frequency B. Then, proceed to step S130.

[0154] In step S130, the control unit 21 determines whether the change in the repetition frequency of the pulse light requires a change in the opening 51a of the mask 51. When the control unit 21 performs aperture b opening processing through the pulse amplification light L1 with repetition frequency B, it re-stores information on whether the opening 51a of the mask 51 needs to be changed. Based on this information, the control unit 21 determines whether the opening 51a of the mask 51 needs to be changed along with the change in the repetition frequency of the pulse light.

[0155] If it is determined that the opening 51a of the mask 51 needs to be changed due to the change in the repetition frequency of the pulse light, then if step S130 is yes, proceed to step S140. If the opening 51a of the mask 51 does not need to be changed due to the change in the repetition frequency of the pulse light, then if step S130 is no, proceed to step S150.

[0156] In step S140, the opening 51a of the mask 51 is changed. Specifically, the mask changer 52 changes the opening 51a through which the pulse amplification light L1 is transmitted, according to the control of the control unit 21. Information about the opening 51a of the mask 51 used by the control unit 21 when performing aperture b opening processing with the pulse amplification light L1 at a repetition frequency B is stored in advance. Based on this information, the control unit 21 instructs the mask changer 52 to use the opening 51a. Then, the process proceeds to step S150.

[0157] In step S150, the control unit 21 determines whether at least one of the wavefront and beam diameter of the pulse amplification light L1 on the mask 51 needs to be changed due to the change in the repetition frequency of the accompanying pulse light. When the control unit 21 performs aperture b opening processing using the pulse amplification light L1 with repetition frequency B, it pre-stores information on whether at least one of the wavefront and beam diameter of the pulse amplification light L1 on the mask 51 needs to be changed. Based on this information, the control unit 21 determines whether at least one of the wavefront and beam diameter of the pulse amplification light L1 on the mask 51 needs to be changed.

[0158] If it is determined that the change in the repetition frequency of the accompanying pulse light requires a change in at least one of the wavefront and beam diameter of the pulse amplification light L1 on the mask 51, then step S150 is yes, and the process proceeds to step S160. If it is determined that the change in the repetition frequency of the accompanying pulse light does not require a change in at least one of the wavefront and beam diameter of the pulse amplification light L1 on the mask 51, then step S150 is no, and the process proceeds to step S170.

[0159] In step S160, at least one of the wavefront and beam diameter of the pulsed amplified light L1 on the mask 51 is changed. Specifically, the driving device 41, under the control of the control unit 21, changes at least one of the wavefront and beam diameter of the pulsed amplified light L1 on the mask 51 by moving the optical element of the beam conduction adjustment unit 40. The control unit 21 stores in advance the position information of the optical element of the beam conduction adjustment unit 40 used when performing aperture b opening processing with pulsed amplified light L1 of repetition frequency B. Based on this information, the control unit 21 instructs the driving device 41 on the position of the optical element of the beam conduction adjustment unit 40. Then, proceed to step S170.

[0160] In step S170, the control unit 21 begins to modulate the transmittance of the optical switching element 30. Then, it proceeds to step S180.

[0161] In step S180, pulse amplification light L1 is output from laser device 110, and hole opening processing of aperture b is performed through pulse amplification light L1 with repetition frequency B.

[0162] As described above, the laser device 110 performs hole opening processing of aperture a through pulse amplification light L1 with repetition frequency A, and then performs hole opening processing of aperture b through pulse amplification light L1 with repetition frequency B, so that hole opening processing of aperture a and aperture b can be performed efficiently.

[0163] Furthermore, although the above description illustrates the case where the laser processing apparatus 2 continuously performs hole-opening processing of aperture a and aperture b, when performing hole-opening processing of three or more different apertures, the processing conditions can be changed to continuously perform hole-opening processing of different apertures in the same manner as described above. For example, after performing hole-opening processing of aperture b as described above, the repetition frequency of the pulse light is changed to repetition frequency C, and hole-opening processing of aperture c, which is different from aperture a and aperture b, can be performed. At this time, after performing hole-opening processing of aperture b in step S180, the process returns to step S120. In the second step from S120 to S170, the processing conditions are changed in the same manner as described above to correspond to hole-opening processing of aperture c, and hole-opening processing of aperture c is performed in the second step S180.

[0164] The laser processing apparatus 2 according to Embodiment 2 described above includes a mask 51 having a plurality of openings 51a of different shapes or sizes through which pulse amplification light L1 can be transmitted. Next, by changing the openings 51a through which the pulse amplification light L1 is transmitted via the mask changer 52, the laser processing apparatus 2 can change the diameter of the processing point beam corresponding to the desired aperture. Therefore, when the laser apparatus 110 performs aperture opening processing through the pulse amplification light L1, it can process small aperture portions with relatively small apertures at a relatively high repetition frequency and large aperture portions with relatively large apertures at a relatively low repetition frequency, thus efficiently performing the processing. Therefore, when the laser processing apparatus 2 performs aperture opening processing through the pulse amplification light L1, it can efficiently process a plurality of different types of apertures.

[0165] Next, the hardware configuration of the control unit 200 according to Embodiments 1 and 2 will be described respectively. The control units 200 according to Embodiments 1 and 2 correspond to the control unit 20 of the laser device 100 and the control unit 21 of the laser device 110, respectively. The functions of the control units 200 according to Embodiments 1 and 2 are implemented by processing circuits. The processing circuit can be dedicated hardware or a processing device that executes a program stored in a memory device.

[0166] When the processing circuit is dedicated hardware, the processing circuit may be, for example, a single circuit, a composite circuit, a programmable processor, a flat-array programmable processor, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or a combination of the above. Figure 11 is a diagram showing the configuration of the various functions of the control unit according to Embodiments 1 and 2 implemented in hardware. In the processing circuit 201, a processing circuit 201a that implements the functions of the control unit 200 is embedded.

[0167] When the processing circuit 201 is a processing device, the function of the control unit 200 is realized through software, firmware, or a combination of software and firmware.

[0168] Figure 12 is a diagram showing the configuration of the control unit according to Embodiments 1 and 2, which implements various functions in software. The processing circuit 201 includes a processor 202 that executes program 201b, a random access memory 203 used by the processor 202 in its working area, and a memory device 204 that stores program 201b. The processor 202 opens program 201b stored in memory device 204 in random access memory 203 and implements the functions of control unit 200 by execution. The software or firmware is written in a programming language and stored in memory device 204. The processor 202 may be a central processing unit, but is not limited thereto. The memory device 204 can be a semiconductor memory such as random access memory (RAM), read-only memory (ROM), flash memory, erasable programmable read-only memory (EPROM), or electrically erasable programmable read-only memory (EEPROM). The memory device 204 can be non-volatile or volatile memory. In addition to semiconductor memory, the memory device 204 can also use magnetic disks, floppy disks, optical disks, compact discs, mini-disks, or digital versatile discs (DVDs). Furthermore, the processor 202 can output calculation results and other data to the memory device 204 for storage, or it can store this data in an auxiliary memory device (not shown) via random access memory 203. By integrating the processor 202, random access memory 203, and memory device 204 onto a single chip, the functions of the control unit 200 can be realized through a microcomputer.

[0169] The processing circuit 201 implements the functions of the control unit 200 by reading and executing the program 201b stored in the memory device 204. In other words, the program 201b is the sequence and method of executing the control unit 200 in the computer.

[0170] In addition, the processing circuit 201 can implement part of the function of the control unit 200 by dedicated hardware, or it can implement part of the function of the control unit 200 by software or firmware.

[0171] Therefore, the processing circuit 201 can implement the above functions through hardware, software, firmware, or a combination thereof.

[0172] The configuration shown in the above embodiments is only one example and can be combined with other known technologies. The embodiments can also be combined with each other. Without departing from the spirit of the matter, a part of the configuration can be omitted or changed. [Simplified Explanation of the Diagram]

[0010] Figure 1 is a block diagram schematically showing an example of the configuration of a laser processing apparatus including a laser device according to Embodiment 1. Figure 2 is a block diagram schematically showing an example of the configuration of a laser oscillator including a laser device according to Embodiment 1. Figure 3 is a characteristic diagram showing experimental results of measuring the output characteristics of pulse amplified light emitted from the laser oscillator when switching the repetition frequency of the pulse light in the laser oscillator according to Embodiment 1. Figure 4 is a characteristic diagram showing experimental results of measuring the pulse energy and beam diameter of pulse amplified light emitted from the laser oscillator when switching the repetition frequency of the pulse light in the laser oscillator according to Embodiment 1. Figure 5 is a block diagram schematically showing an example of the configuration of a laser processing apparatus including a laser device with a photosensitive sensor installed on it according to Embodiment 1. Figure 6 is a block diagram schematically showing an example of the configuration of a laser processing apparatus including a laser device with a beam diameter monitor installed on it according to Embodiment 1. Figure 7 is a characteristic diagram showing the change in average output over time after changing the repetition frequency of the pulsed light in the experiment shown in Figure 3, calculated as a result of the set transmittance modulation mode when the transmittance of the optical switching element is compensated. Figure 8 is a block diagram schematically showing an example of the configuration of a laser processing apparatus including a laser device according to Embodiment 2. Figure 9 is a plan view showing an example of a mask including a laser processing apparatus according to Embodiment 2. Figure 10 is a flowchart showing the sequence of opening holes of different diameters in the laser processing apparatus according to Embodiment 2. Figure 11 is a diagram showing the configuration of the various functions of the control unit according to Embodiments 1 and 2 implemented in hardware. Figure 12 is a diagram showing the configuration of the various functions of the control unit according to Embodiments 1 and 2 implemented in software.

Claims

1. A laser device, comprising: The seed light source outputs pulsed laser light, and the repetition frequency of the aforementioned pulsed laser light can be controlled; Amplifier, amplifies and outputs the aforementioned pulsed laser light; A mask that shapes at least one of the beam diameter and beam shape of the pulsed laser light emitted from the aforementioned amplifier; an optical switch element disposed in the optical path between the aforementioned amplifier and the aforementioned mask that modulates the transmittance so that at least one of the output and energy of the aforementioned pulsed laser light emitted from the aforementioned amplifier varies over time with the change in the repetition frequency of the aforementioned pulsed laser light within a predetermined range; and a beam conduction adjustment unit disposed in the optical path between the aforementioned amplifier and the aforementioned mask that adjusts the beam conduction of the aforementioned pulsed laser light emitted from the aforementioned amplifier.

2. The laser device of claim 1 further includes a driving device that moves the optical element constituting the aforementioned beam conduction adjustment section in the direction of the optical axis of the aforementioned pulsed laser light emitted from the aforementioned optical switching element.

3. The laser device as described in claim 2, wherein, The aforementioned driving device moves the aforementioned optical element after the repetition frequency of the aforementioned pulsed laser light changes, thereby adjusting the beam diameter of the aforementioned pulsed laser light emitted from the aforementioned amplifier that illuminates the aforementioned shield.

4. The laser device as described in claim 2, wherein, The aforementioned driving device moves the aforementioned optical element after the repetition frequency of the aforementioned pulsed laser light changes, so that the divergence state or the convergence state of the aforementioned pulsed laser light emitted from the aforementioned amplifier that illuminates the aforementioned shield does not change before and after the repetition frequency of the aforementioned pulsed laser light changes.

5. The laser device as described in claim 1 further includes: A sensor measures the pulse energy of the pulsed laser light emitted from the amplifier and transmitted through the aforementioned shield; wherein the aforementioned optical switching element modulates the transmittance based on the measurement result of the aforementioned sensor.

6. The laser device as described in any of claims 1 to 5, wherein, The aforementioned shield includes multiple transmission regions of different shapes or sizes through which the aforementioned pulsed laser light can be transmitted, and the aforementioned transmission regions can be changed to allow the aforementioned pulsed laser light emitted from the aforementioned amplifier to be transmitted.

7. A laser processing apparatus, comprising: Such as the laser device requested in any of items 1 to 6; And a processing optical system, which causes the pulsed laser light emitted from the aforementioned laser device to irradiate the object being processed.

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