JP2022187238A - Laser processing device and laser processing method - Google Patents

Abstract

To provide a laser processing device and a laser processing method which use a laser beam efficiently.SOLUTION: A laser processing device comprises: a laser oscillating unit that emits laser light; a laser shutter unit that switches the emitted laser light to first laser light or second laser light which is different in optical axis from the emitted laser light and then emits the laser light; an output part including a double core fiber having a center core and a ring core; and a light collection optical system that guides the first laser light to the center core and guides the second laser light to the ring core. The output part guides the first laser light through the center core and emits a center beam based on the first laser light; and guides the second laser light through the ring core and emits a ring beam based on the second laser light to a circumference of an emission area of the center beam.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a laser processing apparatus and a laser processing method, and more particularly to a laser processing apparatus and a laser processing method using a laser shutter.

2. Description of the Related Art Conventionally, a laser shutter unit that temporally turns on/off a laser beam emitted from a laser oscillator is known (for example, Patent Document 1). In processing using a laser processing apparatus having a laser shutter unit, a laser beam is pulsed by the laser shutter unit and applied to a processing object. By pulsing the laser beam, the diffusion of heat can be suppressed, and the heat-affected zone can be reduced, thereby improving the processing quality.

Some laser shutter units use an acousto-optic modulator (AOM: Acousto-Optic Module) or an electro-optic modulator (EOM: Electro-Optic Module).

In the AOM type laser shutter unit, the optical axis of the emission direction of the laser light passing through the AOM is switched according to the input pulse signal.

On the other hand, in the EOM type laser shutter unit, the polarization direction of the laser light passing through the EOM is switched according to the input pulse signal, and the optical axis of the emission direction is switched according to the switched polarization direction.

The optical paths of two laser beams with different emission directions (hereinafter referred to as "first laser beam" and "second laser beam") are spatially separated. Then, the first laser light is guided to the output section for use in processing, and is irradiated onto the processing target. The second laser beam is guided to a light receiving portion such as a damper and is not used for processing.

JP 2019-86266 A

As described above, in the laser processing apparatus having the laser shutter unit disclosed in Patent Document 1, etc., only the first laser beam guided to the output section is used for processing the workpiece, and the light is guided to the light receiving section. Energy loss occurs because the second laser beam that is emitted is not used for processing.

The present disclosure has been made in view of the above problems, and aims to provide a laser processing apparatus and a laser processing method that efficiently use laser light.

The laser processing apparatus of the present disclosure includes a laser oscillation unit that emits a laser beam, a laser shutter unit that switches the incident laser beam to a first laser beam or a second laser beam having a different optical axis and emits the laser beam, an output section including a double-core fiber having a center core and a ring core; and a condensing optical system that guides the first laser beam to the center core and guides the second laser beam to the ring core. The output unit guides the first laser beam through the center core, irradiates a center beam based on the first laser beam, and emits the second laser beam through the ring core. to irradiate a ring beam based on the second laser beam around the irradiation area of the center beam.

The laser processing method of the present disclosure emits a laser beam, switches the laser beam to a first laser beam or a second laser beam having a different optical axis, and outputs the first laser beam and the second laser beam. are respectively guided to the center core and the ring core of the double-core fiber, the first laser beam is guided through the center core, and the center beam based on the first laser beam is irradiated to irradiate the object to be processed is processed, the second laser beam is guided through the ring core, and a ring beam based on the second laser beam is irradiated around the irradiation area of the center beam to preheat or Cool slowly.

ADVANTAGE OF THE INVENTION According to this indication, the laser processing apparatus and laser processing method which use a laser beam efficiently can be provided.

FIG. 1 is a schematic diagram showing a laser processing apparatus according to the first embodiment. FIG. 2 is a schematic diagram showing a laser shutter unit included in the laser processing apparatus according to the first embodiment. 3A and 3B are enlarged views of the vicinity of the input and output ends of the double-core fiber according to the first embodiment. 4A to 4E are diagrams showing the positional relationship between the processing points on the object to be processed and the irradiation area of the laser light. FIG. 5 is a diagram showing temporal changes in irradiation energy of laser light irradiated to a processing point of an object to be processed. Schematic diagram showing the vicinity of a laser shutter unit of a laser processing apparatus according to a second embodiment

Hereinafter, each embodiment and each modification of the present disclosure will be described with reference to the drawings.

[First embodiment]
FIG. 1 is a schematic diagram showing a laser processing apparatus 100 according to the first embodiment.

The laser processing apparatus 100 includes a laser oscillation unit 1, a laser shutter unit 2, a condensing optical system 4, an output section 5, and the like. The laser processing apparatus 100 irradiates the object 7 with a laser beam, melts and evaporates the irradiated portion with thermal energy, and processes the object 7 .

The laser oscillation unit 1 oscillates and emits laser light LA. The laser light LA emitted by the laser oscillation unit 1 of this embodiment is, for example, parallel light having a single central wavelength.

Note that the laser light LA emitted by the laser oscillation unit 1 may not necessarily have a single wavelength, and may be a laser light having a spread from the central wavelength. Also, the laser light LA may not be perfectly parallel light. In other words, the laser beam LA only needs to have the property of being switched between two types of laser beams with different optical axes by the laser shutter unit 2 .

The laser oscillation unit 1 contains at least a laser oscillator. In addition, the laser oscillation unit 1 may include an optical element such as a lens that guides the laser beam LA to the laser shutter unit 2, a transmission fiber, and the like.

The laser shutter unit 2 includes an optical device called an optical shutter such as an acousto-optic modulator or an electro-optic modulator. The laser shutter unit 2 receives the laser beam LA emitted from the laser oscillation unit 1, and converts the received laser beam LA into two types of laser beams LA11 and LA21 traveling in different directions (hereinafter referred to as "shutter ON beam LA11", (referred to as "shutter OFF beam LA21") to emit. The traveling direction of the shutter-OFF beam LA21 (hereinafter referred to as "second direction") is inclined at an angle θ with respect to the traveling direction of the shutter-ON beam LA11 (hereinafter referred to as "first direction"). . In other words, the optical axis of the shutter-OFF beam LA21 is inclined at an angle θ with respect to the optical axis of the shutter-ON beam LA11.

In the first embodiment, as shown in FIG. 2, the laser shutter unit 2 includes an electro-optic modulator 21 (hereinafter referred to as "EOM 21"), a polarizer 22, and a reflecting mirror 23. .

The EOM 21 switches the laser light LA into two types of laser light with different polarization directions. Specifically, the EOM 21 is connected to the modulation signal generator 3 of FIG. . The modulation signal generator 3 is a device that generates a modulation signal S for modulating the output signal of the laser beam LA, and is, for example, a pulse generator. The polarization directions of the two types of laser beams emitted from the EOM 21 are preferably orthogonal.

The polarizer 22 is an optical element that switches the traveling directions of two types of laser beams with different polarization directions emitted from the EOM 21 according to the respective polarization directions. For example, the polarizer 22 transmits one laser beam emitted from the EOM 21 . The laser beam is emitted from the laser shutter unit 2 as a shutter ON beam LA11. Also, the polarizer 22 reflects the other laser beam emitted from the EOM 21 toward the reflecting mirror 23 .

The reflecting mirror 23 is an optical element that reflects laser light. Reflecting mirror 23 reflects the laser light reflected by polarizer 22 so as to travel in the second direction. The laser beam is emitted from the laser shutter unit 2 as a shutter-OFF beam LA21.

When the modulated signal S is input from the modulated signal generator 3, the laser shutter unit 2 switches the laser light LA to the shutter-ON beam LA11 or the shutter-OFF beam LA21 in synchronization with or inversely synchronized with the modulation signal S. In this embodiment, the pulse signal of the shutter ON beam LA11 is synchronized with the modulation signal S, and the pulse signal of the shutter OFF beam LA21 is inversely synchronized with the modulation signal S. The pulse signal of the shutter ON beam LA11 may be inversely synchronized with the modulated signal S, and the pulse signal of the shutter OFF beam LA21 may be synchronized with the modulated signal S.

The condensing optical system 4 is an optical system such as a condensing lens. The condensing optical system 4 receives the shutter ON beam LA11 and the shutter OFF beam LA21 and guides them to the output section 5 . In this embodiment, as shown in FIG. 1, the condensing optical system 4 is arranged such that its optical axis coincides with the optical axis of the shutter ON beam LA11.

The condensing optical system 4 is preferably a telecentric optical system. In this case, even if the shutter-OFF beam LA21 enters the condensing optical system 4 with its optical axis tilted, the occurrence of curvature of field is suppressed, so that the light convergence to the ring core 512 is improved.

The output unit 5 guides the shutter-on beam LA11 and the shutter-off beam LA21 received from the condensing optical system 4 and irradiates the workpiece 7 with them.

The output section 5 includes a double core fiber 51 , a collimating optical system 52 and a processing optical system 53 .

The double-core fiber 51, as shown in FIGS. 3A and 3B, is an optical fiber for laser transmission having two cores, a center core 511 located in the center and a ring core 512 located on the outer periphery of the center core 511. The diameters of the center core 511 and ring core 512 are d1 and d2, respectively. The double-core fiber 51 has a clad 513 around the outer circumference of the ring core 512 .

Further, a protective covering, a cooling mechanism, or the like may be provided on the outer circumference of the clad 513 . An end cap or the like may be fused to the end of the double core fiber 51 for protection.

The direction of the double-core fiber 51 is adjusted and arranged so that the incident end surface of the center core 511 is positioned on the optical axis of the condensing optical system 4 .

After passing through the focusing optical system 4, the shutter-on beam LA11 is focused on the center core 511 of the double-core fiber 51 on the same optical axis (see FIG. 3A), propagates, and then emerges from the output end face of the double-core fiber 51. It is emitted as a center beam LA12 (see FIG. 3B).

On the other hand, since the shutter-OFF beam LA21 is incident on the condensing optical system 4 at an angle θ, it is condensed by the condensing optical system 4 onto the ring core 512 of the double-core fiber 51 (see FIG. 3A) and propagates. After that, it is emitted as a ring beam LA22 from the emission end face of the double-core fiber 51 (see FIG. 3B).

At this time, the center beam LA12 and the ring beam LA22 are emitted on the same optical axis. Further, the pulse signal of the center beam LA12 is synchronized with the pulse signal of the shutter ON beam LA11, and the pulse signal of the ring beam LA22 is synchronized with the pulse signal of the shutter OFF beam LA21.

Conditions that the diameter d1 of the center core 511 and the diameter d2 of the ring core 512 should satisfy will be described below.

Assuming that the distance from the condensing position of the shutter-OFF beam LA21 to the optical axis of the shutter-ON beam LA11 is L (see FIG. 3A), and the focal length of the condensing optical system 4 is f, the following formula (1) holds.
L=f·tan θ (1)

Assuming that the focused spot diameter when the shutter-on beam LA11 is focused by the focusing optical system 4 is d0, the diameter d1 of the center core 511 of the double-core fiber 51 and the diameter d2 of the ring core 512 are as follows. Equations (2) and (3) hold. In this case, the shutter ON beam LA11 and the shutter OFF beam LA21 are guided to the center core 511 and the ring core 512, respectively.
d0≦d1≦2·L−d0 (2)
d2≧2·L+d0 (3)

In other words, the diameter d1 of the center core 511 and the diameter d2 of the ring core 512 are set so that the equations (2) and (3) are satisfied, so that the shutter ON beam LA11 and the shutter OFF beam LA21 are The light is guided to the center core 511 and ring core 512 .

The collimating optical system 52 collimates the center beam LA12 emitted from the center core 511 and the ring beam LA22 emitted from the ring core 512 and guides them to the processing optical system 53 . Note that the center beam LA12 and the ring beam LA22 that have passed through the collimating optical system 52 do not necessarily have to be completely parallel light.

The processing optical system 53 converges the center beam LA12 and the ring beam LA22, which are parallel lights, and irradiates the processing object 7 with them.

A ring beam LA22 is irradiated around the irradiation area of the center beam LA12. At the start of irradiation, the condensing points of the center beam LA12 and the ring beam LA22 may not necessarily match the surface of the workpiece 7, and may be defocused after irradiation, for example.

The output unit 5 also includes a scanning system 54 . The scanning system 54 is, for example, a driving device including a motorized stage on which the workpiece 7 is arranged. The scanning system 54 adjusts the relative position between the converging positions of the center beam LA12 and the ring beam LA22 and the object 7 to be processed. More specifically, the scanning system 54 moves the motorized stage along a plane perpendicular to the optical axes of the center beam LA12 and the ring beam LA22 that irradiate the workpiece 7 (hereinafter referred to as "scanning plane"). move. Thereby, the processing point on the processing object 7 is scanned on the scanning plane.

In addition, the scanning system 54 moves the electric stage along the optical axis direction of the center beam LA12 and the ring beam LA22 with which the object 7 is irradiated, so that the center beam LA12 and the ring beam LA22 are converged. The relative position with respect to the workpiece 7 may be moved in the optical axis direction so that the machining point can be scanned along the optical axis direction. As a result, even when the surface of the object 7 is uneven, the condensing positions of the center beam LA12 and the ring beam LA22 can be aligned with the surface of the object 7 . Therefore, processing treatment, preheat treatment, and slow cooling treatment, which will be described later, can be effectively performed.

Further, the scanning system 54 may include an optical device (for example, a galvanometer scanner) that changes the irradiation direction of the center beam LA12 and the ring beam LA22 to planarly scan the processing point on the processing object 7 . In this case, the scanning system 54 is arranged, for example, after the collimating optical system 52 and before the processing optical system 53 on the optical axes of the center beam LA12 and the ring beam LA22.

Processing of the object to be processed 7 by the laser processing apparatus 100 will be described below with reference to FIGS. 4A to 4E and FIG.

4A to 4E are diagrams showing the positional relationship between the processing point A of the workpiece 7 and the irradiation area of the laser beam. FIG. 5 is a diagram showing a temporal change in the irradiation energy of the laser beam with which the processing point A of the object 7 is irradiated.

As shown in FIGS. 4A to 4E, the size of the irradiation area R1 of the center beam LA12 is smaller than the size of the irradiation area R2 of the ring beam LA22. For example, the diameter of the irradiation region R1 is approximately 100 μm, and the diameter of the irradiation region R2 is approximately 400 μm. The diameter of the irradiation area R1 and the diameter of the irradiation area R2 respectively correspond to the focused spot diameter of the center beam LA12 and the focused spot diameter of the ring beam LA22.

Also, the energy amounts per unit time of the center beam LA12 and the ring beam LA22 are substantially the same. Therefore, the spatial energy density per unit time in the irradiation region R1 of the center beam LA12 is higher than the spatial energy density per unit time in the irradiation region R2 of the ring beam LA22.

4A to 4E, the scanning system 54 is driven to move the electric stage in the direction indicated by the arrow in FIG. is diametrically crossed. Further, FIG. 5 shows the case where the processing point A moves at a constant speed, and the irradiation energy in the time periods t1 to t5 in FIG. handle. Hereinafter, when the center beam LA12 and the ring beam LA22 are not distinguished from each other, they are simply referred to as "beams."

At the time shown in FIG. 4A (for example, when the laser irradiation is started), the processing point A is located outside the beam irradiation regions R1 and R2, and the center beam LA12 and the ring beam LA22 are not irradiated. As the scanning system 54 is driven, the processing point A approaches the beam irradiation regions R1 and R2.

After that, the processing point A enters the irradiation region R2 of the ring beam LA22 and moves within the irradiation region R2 as shown in FIG. 4B. 5, the processing point A passes through the irradiation region R2 of the ring beam LA22, during which the ring beam LA22 is irradiated. At this time, the spatial energy density of the ring beam LA22 per unit time is small, and the irradiation energy received by the processing point A while passing through the irradiation region R2 is the threshold of the energy required for processing the object 7 (hereinafter referred to as , referred to as the “processing threshold”). Therefore, the irradiation energy contributes only to the heating of the processing point A (no processing is performed), and the processing point A can be preheated prior to the processing time period (time period t3 in FIG. 5) described later. A time period t2 in FIG. 5 is called a preheating time period in which the processing point A is preheated.

After that, the processing point A enters the irradiation region R1 of the center beam LA12 and moves within the irradiation region R1 as shown in FIG. 4C. At time t3 in FIG. 5, the processing point A passes through the irradiation region R1 of the center beam LA12, during which the center beam LA12 is irradiated. At this time, the spatial energy density per unit time of the center beam LA12 is large, and the irradiation energy received by the processing point A while passing through the irradiation region R1 greatly exceeds the processing threshold. Therefore, machining at the machining point A is performed. A time period t3 in FIG. 5 is called a machining time period in which the machining point A is machined.

After that, the processing point A passes through the irradiation region R1 of the center beam LA12, enters the irradiation region R2 of the ring beam LA22, and moves within the irradiation region R2 again as shown in FIG. 4D. At time t4 in FIG. 5, the processing point A passes through the irradiation region R2 of the ring beam LA22, during which the ring beam LA22 is irradiated. At this time, the spatial energy density per unit time of the ring beam LA22 is small, and the irradiation energy received by the processing point A while passing through the irradiation region R2 does not exceed the processing threshold. Therefore, the irradiation energy contributes only to the heating of the processing point A (no processing is performed), and the processing point A, which is processed during the processing time period (time period t3 in FIG. 5) and has a high temperature, suddenly Cooling can be suppressed and slow cooling can be performed. A time zone t4 in FIG. 5 is called a slow cooling time zone in which the working point A is slowly cooled.

After that, the processing point A passes through the irradiation region R2 of the ring beam LA22 and is positioned outside the beam irradiation regions R1 and R2 as shown in FIG. 4E. In time period t5 in FIG. 5, the processing point A moves outside the beam irradiation regions R1 and R2. At this time, the processing point A is not irradiated with the center beam LA12 and the ring beam LA22. Thus, the machining of the machining point A is completed.

In the above description, the scanning system 54 moves the workpiece 7 one-dimensionally during machining of the workpiece 7 as an example. However, the scanning system 54 may move the workpiece 7 two-dimensionally during machining of the workpiece 7 . Further, the moving speed of the workpiece 7 by the scanning system 54 may be changed according to the time required for the processing of the processing point A, the preheat treatment and the slow cooling.

As described above, the laser processing apparatus 100 includes the laser oscillation unit 1 that emits the laser beam LA, and the incident laser beam LA as the shutter ON beam LA11 (first laser beam) or the shutter OFF beam LA21 with different optical axes. A laser shutter unit 2 that switches to (second laser light) and emits it, an output unit 5 including a double core fiber 51 having a center core 511 and a ring core 512, and a shutter ON beam LA11 Guided to the center core 511, and a condensing optical system 4 that guides the shutter-OFF beam LA21 to the ring core 512 .

The output unit 5 guides the shutter ON beam LA11 through the center core 511 to irradiate the center beam LA12 based on the shutter ON beam LA11, and guides the shutter OFF beam LA21 through the ring core 512 to produce the shutter ON beam LA11. A ring beam LA22 based on the shutter-OFF beam LA21 is irradiated around the irradiation area R1 of the center beam LA12.

By irradiating the object 7 with the ring beam LA22 whose energy density is reduced to the extent that the object 7 is not processed, the center beam LA12 is used for processing the object 7, while the ring beam LA 22 can be used for preheating and slow cooling of workpiece 7 .

By performing preheating and slow cooling on the object 7, the temperature gradient near the processing point A of the object 7 becomes gentle. As a result, there are mainly the following advantages.

(1) Since the generation of spatter is suppressed in the processing, the diffusion of the melted matter of the workpiece 7 is suppressed. For example, it is possible to reduce the possibility that a melt containing a conductive substance as a main component will adhere to the insulating portion of the workpiece 7 .
(2) Since the residual stress in the processed object 7 can be reduced, cracks are less likely to occur in the processed object 7 .
(3) Further, the occurrence of blowholes in the workpiece 7 is suppressed. Therefore, it is possible to suppress a decrease in the strength of the processed workpiece 7 .

That is, the processing quality of the laser processing apparatus 100 is improved by performing the preheating and slow cooling.

It can be said that the laser processing apparatus 100 effectively uses both the shutter ON beam LA11 and the shutter OFF beam LA21. Therefore, the laser processing apparatus 100 can reduce the energy loss of the laser beam LA emitted from the laser oscillation unit 1 and use the laser beam LA efficiently.

Moreover, since there is no need to separately prepare a heating device for performing preheating and slow cooling, a single laser processing apparatus 100 can perform high-quality laser processing.

More specifically, the output unit 5 has a processing optical system 53 that converges the center beam LA12 and the ring beam LA22 on the object 7 to be processed. It also has a scanning system 54 that adjusts the relative positions of the workpiece 7 and the condensing positions of the center beam LA12 and the ring beam LA22.

The output unit 5 further includes a collimating optical system 52 that collimates the center beam LA12 and the ring beam LA22 and guides them to the processing optical system 53 .

Also, the condensing optical system 4 is a telecentric optical system. If the condensing optical system 4 is not a telecentric optical system, the following problems may occur. As described above, the shutter-OFF beam LA21 enters the condensing optical system 4 with its optical axis inclined at an angle θ with respect to the optical axis of the condensing optical system 4 . Therefore, the condensing position of the shutter-OFF beam LA21 with respect to the double-core fiber 51 by the condensing optical system 4 may shift in the optical axis direction of the condensing optical system 4 . This deviation causes curvature of field.

Since the condensing optical system 4 of the present embodiment is a telecentric optical system, the shutter-OFF beam LA21 is condensed in a state in which the optical axis of the shutter-OFF beam LA21 is inclined at an angle θ with respect to the optical axis of the condensing optical system 4. Even if the beam enters the optical system 4, the occurrence of field curvature can be suppressed, and the shutter-OFF beam LA21 can be appropriately focused on the ring core 512. FIG.

The laser shutter unit 2 includes an EOM 21 that switches the polarization direction of the transmitted laser light LA, and a polarizer 22 (optical element) that switches the traveling direction of the laser light LA according to the polarization direction of the laser light LA transmitted through the EOM 21. have.

Therefore, by appropriately setting the polarization direction of the polarizer 22, the laser beam LA can be easily and reliably switched to the shutter ON beam LA11 or the shutter OFF beam LA21.

When the AOM is used to switch the laser beam LA to the shutter ON beam LA11 or the shutter OFF beam LA21, while one beam is being emitted from the laser shutter unit 2, the other beam is also slightly emitted. For this reason, the center beam LA12 used for processing is irradiated onto the processing object 7 at a timing when processing is not desired, which may lead to deterioration in processing quality.

However, the laser shutter unit 2 of this embodiment uses the EOM 21 to switch the laser beam LA to the shutter ON beam LA11 or the shutter OFF beam LA21. Therefore, while one of the shutter-ON beam LA11 and the shutter-OFF beam LA21 is being emitted, the other beam is not emitted. Therefore, the center beam LA12 used for processing does not irradiate the processing object 7 at a timing when the processing is not desired, and deterioration of processing quality can be suppressed.

[Second embodiment]
In the following, the second embodiment will be described mainly about the differences from the first embodiment.

FIG. 6 is a schematic diagram showing a laser processing apparatus 200 according to the second embodiment. Like the laser processing apparatus 100 according to the first embodiment, the laser processing apparatus 200 includes a laser oscillation unit 1, a laser shutter unit 2, a condensing optical system 4, an output section 5, and the like. Note that FIG. 6 shows only the double-core fiber 51 for the configuration of the output section 5 .

In the first embodiment, the EOM system is adopted as the laser shutter unit 2, whereas in the second embodiment, the AOM system is adopted. That is, the laser shutter unit 2 has an acousto-optic modulator (AOM) 24 . The AOM 24 switches the traveling direction of the incident laser light LA between the first direction and the second direction. The operating principle of the AOM will be described below.

AOM 24 has an ultrasonic generator (not shown) and an AO crystal (not shown). The ultrasonic generator is a device that applies ultrasonic waves to the AO crystal in synchronization with the modulated signal S from the modulated signal generator 3 . AO crystals are transparent acousto-optic crystals, crystals whose refractive index changes when ultrasonic waves are applied.

While the ultrasonic wave generator is not applying ultrasonic waves to the AO crystal, the laser beam LA passes through the AO crystal without changing its optical axis. As a result, the laser shutter unit 2 emits a shutter ON beam LA11 traveling in the first direction.

On the other hand, while the ultrasonic wave generator is applying ultrasonic waves to the AO crystal, the optical axis of the laser beam LA is changed by an angle θ when passing through the AO crystal. As a result, the laser shutter unit 2 emits a shutter-OFF beam LA21 traveling in the second direction.

In the second embodiment, no optical element is interposed on the light guide path from the AOM 24 to the condensing optical system 4 . That is, the shutter-on beam LA11 and the shutter-off beam LA21 emitted from the AOM 24 directly enter the condensing optical system 4 . That is, the shutter-ON beam LA11 and the shutter-OFF beam LA21 are guided to the condensing optical system 4 without changing their traveling directions when emitted from the AOM 24 .

In the second embodiment, the angle θ between the optical axis of the laser beam LA incident on the AOM 24 and the optical axes of the shutter ON beam LA11 and the shutter OFF beam LA21 is represented by the following equation (4).

In equation (4), λ is the laser center wavelength of the laser beam LA, fC is the center frequency of the ultrasonic waves generated by the ultrasonic generator of the AOM 24, and V is the travel speed of the ultrasonic waves in the AO crystal. That is, the second direction, which is the emission direction of the shutter-OFF beam LA21, is determined by the laser center wavelength λ of the laser light LA and the center frequency fC of the ultrasonic wave. In other words, the center frequency fC of the ultrasonic wave is appropriately set based on the angle θ determined so that the shutter-OFF beam LA21 is focused on the ring core 512 and the laser center wavelength λ of the laser light LA.

The condensing optical system 4 directly receives the shutter ON beam LA11 and the shutter OFF beam LA21 emitted from the AOM 24 . That is, the shutter-on beam LA11 and the shutter-off beam LA21 do not pass through or are reflected by the optical element until they enter the condensing optical system 4 .

The condensing optical system 4 guides the received shutter-on beam LA11 to the center core 511 and guides the shutter-off beam LA21 to the ring core 512 .

Also, the laser processing apparatus 200 according to the second embodiment satisfies the expressions (1) to (3) as in the first embodiment. Therefore, the shutter ON beam LA11 is incident on the center core 511 from the incident end surface of the center core 511, propagates through the center core 511, and is emitted from the output end surface of the center core 511 as the center beam LA12. Further, the shutter-OFF beam LA21 is incident on the ring core 512 from the incident end face of the ring core 512, propagates through the ring core 512, and is emitted from the outgoing end face of the ring core 512 as the ring beam LA22.

Unlike the first embodiment, the laser shutter unit 2 of the second embodiment does not have optical elements such as the polarizer 22 and the reflecting mirror 23 . Therefore, it is not necessary to secure a space for arranging an optical element for switching between the shutter-on beam LA11 traveling in the first direction and the shutter-off beam LA21 traveling in the second direction. Also, the laser beam LA can be switched to the shutter ON beam LA11 or the shutter OFF beam LA21 with fewer elements than in the first embodiment.

Therefore, it is possible to make the laser shutter unit 2 compact, and thus to make the laser processing apparatus 200 compact.

In addition, since the AOM 24 has higher durability against laser light than the EOM 21, it can use a higher output laser light LA than the laser shutter unit 2 of the first embodiment.

As with the laser processing apparatus 100 according to the first embodiment, the laser processing apparatus 200 according to the second embodiment uses the laser oscillation unit 1 that emits the laser light LA and the incident laser light LA as shutters having different optical axes. A laser shutter unit 2 that switches to an ON beam LA11 (first laser beam) or a shutter OFF beam LA21 (second laser beam) and emits it, and an output section 5 that includes a double core fiber 51 having a center core 511 and a ring core 512. , and a condensing optical system 4 that guides the shutter-on beam LA11 to the center core 511 and guides the shutter-off beam LA21 to the ring core 512 .

The output unit 5 guides the shutter ON beam LA11 through the center core 511 to irradiate the center beam LA12 based on the shutter ON beam LA11, and guides the shutter OFF beam LA21 through the ring core 512 to produce the shutter ON beam LA11. A ring beam LA22 based on the shutter-OFF beam LA21 is irradiated around the irradiation area R1 of the center beam LA12.

Therefore, the same actions and effects as those of the laser processing apparatus 100 can be obtained. Specifically, since the laser processing apparatus 200 effectively uses both the shutter ON beam LA11 and the shutter OFF beam LA21, the energy loss of the laser light LA emitted from the laser oscillation unit 1 is reduced, and the laser light LA can be used efficiently.

In addition, the laser shutter unit 2 has an AOM 24 that switches the traveling direction of the incident laser beam LA. ) directly enters the condensing optical system 4 .

Therefore, the laser beam LA can be switched to the shutter-ON beam LA11 or the shutter-OFF beam LA21 with a smaller number of elements. Furthermore, a higher output laser beam LA can be used.

[Other Modifications]
The laser shutter unit 2 of the first embodiment has been described as having the EOM 21 , the polarizer 22 , and the reflecting mirror 23 that reflects the laser beam LA reflected by the polarizer 22 . The laser shutter unit 2 may include a reflecting mirror that reflects the laser beam LA transmitted through the polarizer 22 instead of the reflecting mirror 23 . In addition to the reflecting mirror 23 , the laser shutter unit 2 may also have a reflecting mirror that reflects the laser beam that has passed through the polarizer 22 . Also, the laser shutter unit 2 may have a reflecting mirror 23 or, in place of the reflecting mirror, a prism that refracts the laser light to change the traveling direction of the laser light.

The condensing optical system 4 does not necessarily have to be a telecentric optical system.

The shutter ON beam LA11 may be focused on the ring core 512 and the shutter OFF beam LA21 may be focused on the center core 511 . In that case, the orientation of the condensing optical system 4 is adjusted so that the optical axis of the condensing optical system 4 coincides with the optical axis of the shutter-OFF beam LA21. Alternatively, the orientation of the double core fiber 51 is adjusted so that the ring core 512 can receive the shutter ON beam LA11 and the center core 511 can receive the shutter OFF beam LA21. In this case, the shutter-OFF beam LA21 is emitted from the emission end face of the center core 511 as the center beam LA12, and the shutter-ON beam LA11 is emitted from the emission end face of the ring core 512 as the ring beam LA22.

The output section 5 does not necessarily have to have the collimating optical system 52 . That is, the center beam LA12 and the ring beam LA22 emitted from the emission end faces of the center core 511 and the ring core 512 may be guided to the processing optical system 53 without being parallel.

According to the laser processing apparatus and laser processing method according to the present disclosure, laser light can be efficiently used for laser processing.

REFERENCE SIGNS LIST 100, 200 laser processing device 1 laser oscillation unit 2 laser shutter unit 3 modulation signal generation unit 4 condensing optical system 5 output unit 51 double core fiber 511 center core 512 ring core 513 clad 52 collimating optical system 53 processing optical system 54 scanning system 7 processing Object 21 electro-optic modulator (EOM)
22 polarizer 23 reflective mirror 24 acousto-optic modulator (AOM)
LA Laser beam LA11 Shutter ON beam LA21 Shutter OFF beam LA12 Center beam LA22 Ring beam S Modulation signal θ Angle

Claims (7)

a laser oscillation unit that emits laser light;
a laser shutter unit that switches the incident laser beam to a first laser beam or a second laser beam with a different optical axis and emits the laser beam;
an output section comprising a double-core fiber having a center core and a ring core;
a condensing optical system that guides the first laser beam to the center core and guides the second laser beam to the ring core;
with
The output unit guides the first laser beam through the center core, irradiates a center beam based on the first laser beam, and guides the second laser beam through the ring core. A laser processing apparatus that emits a ring beam based on the second laser light to the periphery of the irradiation area of the center beam. The output unit includes a processing optical system that converges the center beam and the ring beam on an object to be processed;
a scanning system that adjusts relative positions of the object to be processed and converging positions of the center beam and the ring beam;
The laser processing apparatus according to claim 1. The output unit further includes a collimating optical system that collimates the center beam and the ring beam and guides the light to the processing optical system.
The laser processing apparatus according to claim 2. The condensing optical system is a telecentric optical system,
The laser processing apparatus according to any one of claims 1 to 3. The laser shutter unit includes an electro-optic modulator that switches the polarization direction of the transmitted laser light, and an optical element that switches the traveling direction of the laser light according to the polarization direction of the laser light that has passed through the electro-optic modulator. has
The laser processing apparatus according to any one of claims 1 to 4. The laser shutter unit has an acousto-optic modulator that switches the traveling direction of the incident laser light,
The first laser light and the second laser light emitted from the acousto-optic modulator directly enter the condensing optical system,
The laser processing apparatus according to any one of claims 1 to 4. emit a laser beam,
switching the laser beam to a first laser beam or a second laser beam having a different optical axis;
guiding the first laser beam and the second laser beam to the center core and ring core of a double-core fiber, respectively;
guiding the first laser beam through the center core and irradiating a center beam based on the first laser beam to process the workpiece;
guiding the second laser beam through the ring core and irradiating a ring beam based on the second laser beam around the irradiation area of the center beam to preheat or slowly cool the object;
Laser processing method.

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