OPTICAL SYSTEM AND LASER DEVICE, COLLIMATOR LENS

An optical system includes: a first collimator lens disposed facing the light source array, configured to collimate each light beam in at least a vertical direction, intersecting an arrangement direction of light sources and an optical axis direction of each light beam, among the vertical direction and the arrangement direction; an optical element disposed on an emission side of each light beam in the first collimator lens; and a second collimator lens disposed on an emission side of each light beam in the optical element, configured to collimate each light beam at least in the arrangement direction. The first collimator lens includes lens portions arranged in the arrangement direction, the lens portions corresponding to the light sources in the light source array. The lens portions are configured rotationally asymmetrically to have positive power in the vertical direction and have positive power in the arrangement direction.

TECHNICAL FIELD

The present disclosure relates to an optical system used in a laser processing device or the like, a laser device, and a collimator lens.

BACKGROUND ART

US 2016/0048028 discloses a wavelength-combining laser system in which individual light beams are superposed to form a combined beam. US 2016/0048028 discloses that light beams from a plurality of diode bars are condensed on an optical fiber from a viewpoint of increasing light output. For the purpose of reducing the size of the laser system, an optical system for removing the placement of a light combining lens from the focal length in wavelength synthesis is separately included, or a beam rotor is rotated.

SUMMARY

The present disclosure provides an optical system, a laser device, and a collimator lens capable of facilitating simple configuration of an optical system for guiding a plurality of light beams from a light source array.

In an aspect of the present disclosure, an optical system is provided for guiding a plurality of light beams from a light source array in which a plurality of light sources are arranged. The optical system includes: a first collimator lens disposed facing the light source array, configured to collimate each light beam in at least a vertical direction among the vertical direction and an arrangement direction of the plurality of light sources, the vertical direction intersecting the arrangement direction and an optical axis direction of each light beam; an optical element disposed on an emission side of each light beam in the first collimator lens; and a second collimator lens disposed on an emission side of each light beam in the optical element, configured to collimate each light beam at least in the arrangement direction. The first collimator lens includes a plurality of lens portions arranged in the arrangement direction, the plurality of lens portions corresponding to the plurality of light sources in the light source array. The plurality of lens portions are configured rotationally asymmetrically to have positive power in the vertical direction and have positive power in the arrangement direction.

In an aspect of the present disclosure, a laser device includes: a light source array including a plurality of light sources arranged in the arrangement direction, configured to emit the plurality of light beams; and the optical system configured to guide the plurality of light beams from the light source array.

In an aspect of the present disclosure, a collimator lens is provided for collimating a plurality of light beams from a light source array in which a plurality of light sources are arranged. The collimator lens includes a plurality of first lens portions arranged in the arrangement direction, the plurality of lens portions corresponding to the plurality of light sources in the light source array. The plurality of first lens portions are provided rotationally asymmetrically to have positive power in a vertical direction and to have positive power in the arrangement direction, the vertical direction intersecting the arrangement direction and an optical axis direction of each of the light beams.

According to the present disclosure, it is possible to provide an optical system, a laser device, and a collimator lens capable of facilitating simple configuration of an optical system for guiding a plurality of light beams from a light source array.

DETAILED DESCRIPTION

Hereinafter, embodiments will be described in detail with reference to the drawings as needed. However, description more detailed than necessary may be omitted. For example, detailed description of already well-known matters and redundant description of substantially the same configuration may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art.

In addition, the inventor(s) provide(s) the accompanying drawings and the following description in order to enable those skilled in the art to sufficiently understand the present disclosure, which is not intended to limit the claimed subject matter.

First Embodiment

In a first embodiment, a wavelength-combining optical resonator and a laser processing device including the same will be described as an example of a laser device.

A configuration of a laser processing device and an optical resonator according to a first embodiment will be described with reference toFIG.1.FIG.1is a diagram showing a configuration of a laser processing device1according to the present embodiment.

For example, as shown inFIG.1, a laser processing device1includes an optical resonator2, a transmission optical system10, a processing head11, and a controller12. The laser processing device1is an example of a laser device that irradiates various processing objects15with laser light to perform various laser processing. Examples of the various laser processing include laser welding, laser cutting, and laser drilling.

The optical resonator2is an example of a laser device that generates laser light output from the laser processing device1, for example. In the present embodiment, the optical resonator2is a wavelength-combining external resonator that resonates and combines a plurality of light beams at respective wavelengths. The wavelength-combining optical resonator2makes it easy to obtain favorable beam quality and to narrow the beam diameter.

As shown inFIG.1, the optical resonator2according to the present embodiment includes a laser diode (LD) array3in which a plurality of laser elements31to33are arranged, an output coupler25that emits output light, and an optical system (4,20) disposed between the LD array3and the output coupler25. Hereinafter, a direction in which the laser elements31to33are arranged is referred to as an “X direction”, a direction of an optical axis of a light beam emitted from each of the laser elements31to33by the LD array3is referred to as a “Z direction”, and a direction orthogonal to the X and Z directions is referred to as a “Y direction”. The generic term of the laser elements31to33may be “laser elements30”.

The LD array3in the optical resonator2is an example of a light source array including a plurality of laser elements30.FIG.1illustrates three laser elements31to33included in the LD array3. For example, the number of laser elements30included in the LD array3is several tens to several hundreds.

The optical system (4,20) in the optical resonator2includes a diffractive element20and a collimator optical system4that collimates each light beam incident on the diffractive element20, for example. The optical resonator2of the present embodiment causes each light beam of a specific wavelength band to resonate in an optical path that reciprocates between the LD array3and the output coupler25via the optical system described above.

In the optical system for use in such an optical resonator2, the present embodiment provides an optical system that can simplify the placing configuration by reducing the number of components or by other means while ensuring the beam quality of the laser processing device1. The configuration of the optical system and the like in the optical resonator2will be described later.

In the laser processing device1, the transmission optical system10is an optical system that transmits the laser light from the optical resonator2to the processing head11, and includes e.g. an optical fiber. For example, the processing head11is a device that is disposed facing the processing object15and irradiates the processing object15with the laser light transmitted from the optical resonator2.

The controller12is a control device that controls the entire operation of the laser processing device1. For example, the controller12includes a central processing unit (CPU) or a micro-processing unit (MPU) that achieves a predetermined function in cooperation with software. The controller12may include an internal memory that stores various programs and data, and various interfaces that enables a user to input oscillation conditions and the like through user operations. The controller12may include a hardware circuit, such as an application-specific integrated circuit (ASIC) or a field-programmable gate array (FPGA), that achieves various functions. The controller12may be configured integrally with a drive circuit of a light source.

The configuration of the optical system and the like of the optical resonator2according to the present embodiment will be described with reference toFIG.2.

FIG.2illustrates a configuration of an optical resonator2in the laser processing device1of the first embodiment. In the optical resonator2of the present embodiment, the collimator optical system4includes a beam-twister unit (BTU)40and a fast-axis collimator (FAC)45as shown inFIG.2, for example (details will be described later). In the present configuration example, the optical resonator2may further include a telescope optical system26disposed between the diffractive element20and the output coupler25.

In the optical resonator2, the LD array3includes a direct diode laser, for example. A high reflectance coating with a reflectance of e.g. 99.9% or more is applied to the rear end surface (i.e., −Z side) of the LD array3. For example, an antireflection coating with a transmittance of 99.9% or more is applied to the front (i.e., +Z side) end surface of the LD array3. The plurality of laser elements30in the LD array3have a common spontaneous emission spectrum corresponding to material of an LD light emitting layer, for example. For example, the spectrum corresponds to a resonance wavelength band, and is e.g. a blue region with a wavelength of 400 nm to 450 nm.

In the present embodiment, the LD array3emits light beams having a fast axis with a relatively larger divergence angle and a slow axis with a relatively smaller divergence angle from each laser element30(cf.FIGS.6and8). The fast axis of the light beam causes the beam diameter to expand more rapidly than the slow axis, making it easier to obtain fine beam quality. Each laser element30is an example of a light source constituting an emitter of the LD array3, and emits a light beam to the +Z side.

For example, the diffractive element20is disposed at a position away from the FAC45of the collimator optical system4on the +Z side. For example, the diffractive element20is a dispersive element in which a transmissive type diffraction grating is formed. In the present embodiment, the diffraction grating of the diffractive element20satisfies a diffraction condition for emitting light beams from the plurality of laser elements31to33in the same direction and combining the light beams (details will be described later). The diffractive element20is not particularly limited to the transmissive type, and may be formed of a reflective type diffraction grating.

The telescope optical system26is formed of a plurality of cylindrical lenses having optical power in a direction corresponding to the fast axis, for example. For example, the telescope optical system26reduces the beam diameter in the fast axis of the light beam from the diffractive element20to emit the light beam to the output coupler25. The telescope optical system26can reduce the angular error sensitivity of the output coupler25with respect to the fast axis of the light beam.

The output coupler25is disposed in a direction in which the light beam diffracted by the diffractive element20is emitted. For example, the output coupler25includes a mirror element with predetermined transmittance and reflectance. Among the light beams incident on the output coupler25from the diffractive element20, a transmission component corresponding to the transmittance is emitted to the transmission optical system10as an output of the optical resonator2, for example. On the other hand, the reflection component corresponding to the reflectance is returned to the diffractive element20for optical resonance. The output coupler25may be provided with a mechanism capable of adjusting such reflectance and transmittance.

The configuration of the optical resonator2as described above is an example, and is not particularly limited to this configuration. For example, the telescope optical system26may be omitted. Alternatively or additionally, an optical system for performing various adjustments in the optical resonator2may be included. The optical resonator2may further include various optical elements such as a half-wave plate or a prism. The number of the LD arrays3in the optical resonator2is not limited to one, and may be plural.

1-2. Collimator Optical System

Details of the collimator optical system4in the present embodiment will be described with reference toFIGS.2to5.

In the collimator optical system4of the present embodiment, the BTU40is disposed on the +Z side of the LD array3, and the FAC45is disposed on the +Z side of the BTU40as shown inFIG.2, for example.FIG.3illustrates the configuration of the BTU40in the collimator optical system4.FIG.3corresponds to an XZ cross-section along the optical axis of the laser element30in the BTU40.

The BTU40in the collimator optical system4includes an FAC41disposed facing the LD array3and a BT (beam twister)42disposed on the +Z side of the FAC41as shown inFIG.3, for example. Hereinafter, the FAC41in the BTU40is referred to as a first FAC41, and the FAC45outside the BTU is referred to as a second FAC45. The first FAC41extends in the X direction, which is the arrangement direction of the plurality of laser elements30in the LD array3.

The first FAC41of the present embodiment is configured in an array shape having positive optical power (i.e., positive power) for each laser element30arranged in the X direction. By introducing such a first FAC41, the optical resonator2of the present embodiment can achieve simplification of the overall configuration of the optical system.

FIG.4is a perspective view illustrating the configuration of the first FAC41in the BTU40of the present embodiment. The first FAC41of the present embodiment is formed of a toroidal array and includes a plurality of lens portions43arranged in the X direction. The lens portion43is a portion constituting a lens corresponding to each laser element30in the first FAC41.

For example, the plurality of lens portions43in the first FAC41have the same shape or the like and are arranged at a pitch similar to the pitch between the laser elements30in the LD array3. For example, each lens portion43has an optical axis that coincides with the optical axis of the light beam from the corresponding laser element30. The first FAC41is disposed at a focal length of each lens portion43from the emission side of the LD array3, for example (cf.FIG.3).

The first FAC41of the present embodiment has a lens shape in which the positive power in the X direction is smaller than the positive power in the Y direction in each lens portion43according to the characteristics of a fast axis Af and a slow axis As of the laser element30. The lens portion43of the first FAC41is an example of the first lens portion43in the present embodiment.

In the configuration example ofFIG.4, the lens surface from which the light beam is emitted on the +Z side in the first FAC41, that is, the emission surface, is configured as a toroidal aspherical surface for each lens portion43. Such an emission surface of the first FAC41is rotationally asymmetric with respect to each optical axis for each lens portion43.

In the present configuration example, the lens surface on which the light beam is incident from the laser element30on the −Z side of the first FAC41, that is, the incident surface, is a flat surface. According to the present configuration example, it is possible to omit the processing for axial alignment between the incident surface and the emission surface, and to facilitate the manufacturing of the first FAC41. Numerical examples of such a first FAC41will be described later.

FIG.5is a perspective view showing a configuration example of the BT42. For example, the BT42is an optical element that rotates a plurality of light beams and includes a plurality of oblique lens portions44. The oblique lens portion44is a portion constituting a lens for each laser element30in the BT42and constitutes a cylindrical lens, for example. The oblique lens portion44is an example of a second lens portion in the present embodiment. Note that the BT42and the first FAC41are not particularly limited to being integrally provided as in the BTU40, and for example, the first FAC41may be provided separately from the BT42.

The BT42is formed such that a plurality of oblique lens portions44are arranged at a predetermined pitch in the X direction, for example. The oblique lens portion44is inclined by 45° with respect to both the X and Y directions, for example. The inclination of the oblique lens portion44in BT42is not necessarily 45°, and may be e.g. 40° to 50° with respect to the Y direction.

For example, the BT42may be attached to the first FAC41and the LD array3by being rotated around the optical axis of the specific laser element30, such as the center one, by a predetermined minute angle (e.g., 0.01° or less). This may provide the BT42with a light-condensing function to emit a plurality of light beams, which have passed through the BT42, at a light beam angle that brings the light beams closer to each other as they travel (e.g., see US 2016/0048028).

Returning toFIG.2, in the collimator optical system4of the present embodiment, the second FAC45is formed of a spherical lens and has positive power, for example. For example, the second FAC45is disposed rotationally symmetrically around the optical axis of the light beam emitted from a specific laser element30, such as the center one, in the LD array3. For example, the second FAC45is disposed at a position with a focal length from the emission surface of the BTU40on the +Z side where the light beam travels, for example.

The second FAC45is not particularly limited to a spherical lens, and may be e.g. a rotationally symmetric aspherical lens or a rotationally asymmetric lens such as an anamorphic aspherical lens. The second FAC45is not limited to one lens element, and may be formed of a plurality of lens elements. For example, the second FAC45may be configured by combining a positive lens and a negative lens to have a combined focal length longer than the focal length of one positive lens. The second FAC45is not particularly limited to a refraction lens, and may be a diffraction lens.

The function of the collimator optical system4of the present embodiment, which is configured as described above, to collimate each light beam from the LD array3will be described with reference toFIGS.6A to8B.

FIGS.6A and6Bare diagrams for explaining the collimating function in the fast axis Af in the collimator optical system4of the present embodiment.FIG.6Ais a side view of the collimator optical system4as viewed from the X side.FIG.6Bis a side view of the collimator optical system4as viewed from the Y side.FIGS.6A and6Billustrates each of the lens portions43,44corresponding to the light beam from one laser element30.

FIGS.6A and6Billustrate a component Bf with respect to the fast axis Af of the light beam. Before the light beam of the laser element30is incident on the collimator optical system4, the fast axis Af of the light beam faces the Y direction, and the slow axis As faces the X direction.

In the collimator optical system4of the present embodiment, as exemplified inFIG.6A, the first FAC41collimates the light beam from the laser element30in the Y direction corresponding to the fast axis Af, and emits the collimated light beam to the BT42.

The BT42rotates the light beam incident from the laser element30via the first FAC41by a rotation angle of 90 degrees on the XY plane. As a result, the fast axis Af of the light beam emitted from the BT42is directed in the X direction, and the slow axis As is directed in the Y direction.

As shown inFIG.6B, the light beam emitted from BT42basically linearly travels to the +Z side for the component Bf corresponding to the fast axis Af. However, according to the wave action of the light, as the light beam travels to the +Z side, the beam diameter corresponding to the fast axis Af may spread due to the influence of diffraction.

Therefore, the second FAC45collimates the light beam with the beam diameter thus expanded on the +Z side of the BT42, and inhibits the influence of wave diffraction on the component Bf in the fast axis Af of the light beam, for example. With such a collimating function in the fast axis Af, the collimator optical system4of the present embodiment can output a light beam with fine beam quality in the fast axis Af to the diffractive element20and the like of the optical resonator2, for example (cf.FIG.2).

The collimator optical system4of the present embodiment has the collimating function in the slow axis As in addition to the collimating function in the fast axis Af as described above. Prior to the description, a typical configuration with such a collimating function will be described.

FIGS.7A and7Bare diagrams for explaining a collimator optical system4xof the typical example described above.FIG.7Ais a side view of the collimator optical system4xfrom the X side, andFIG.7Bis a side view of the collimator optical system4xfrom the Y side.FIGS.7A and7Billustrate the component Bf in the fast axis Af and a component Bs in the slow axis As of the light beam in the collimator optical system4x.

The typical collimator optical system4xfurther includes a slow-axis collimator (SAC)46in addition to the BTU40xand the second FAC45x.The typical FACs41x,45xare respectively different from the FACs41,45in the collimator optical system4of the present embodiment in a configuration such as a lens shape.

For example, as shown inFIGS.7A and7B, the typical first FAC41xis formed of a cylindrical lens having positive power only in the Y direction corresponding to the fast axis Af. In the present example, the light beam from the laser element30is collimated only for the component Bf in the fast axis Af by the first FAC41xand is incident on the BT42. When the light beam in the typical example as described above is emitted from the BT42, as exemplified inFIG.7A, the component Bs in the slow axis As becomes divergent light.

For example, as shown inFIGS.7A and7B, the SAC46is disposed between the BTU40xand the FAC45x,and is formed of a cylindrical lens having positive power only in the Y direction corresponding to the slow axis As. In the present example, the light beam from the BT42is collimated for the component Bs in the slow axis As by the SAC46and emitted to the FAC45x.

For example, as shown inFIGS.7A and7B, the typical second FAC45xis formed of a cylindrical lens having positive power only in the X direction corresponding to the fast axis Af. As shown inFIG.7B, the second FAC45xinhibits the wave influence on light for the component Bf in the fast axis Af.

As described above, in the typical collimator optical system4x,two FACs41x,45xare used for the collimating function in the fast axis Af, and one SAC46is used for the collimating function in the slow axis As. In such a typical configuration, achieving the collimating function in each of the axes Af, As requires accurate placement of the SAC46in addition to the BTU40xand the second FAC45x,resulting in a complicated placing configuration and an enlarged device configuration.

Therefore, in the collimator optical system4of the present embodiment, the SAC46with the typical configuration as described above is omitted, and instead, a lens shape capable of achieving the collimating function in the slow axis As is adopted for the first and second FACs41,45. It is thereby possible to provide the collimator optical system4, which can simplify the placing configuration by the amount of the omitted SAC46while maintaining the collimating function in each of the axes Af, As, and can also be reduced in size.

FIGS.8A and8Bare diagrams for explaining the collimating function in the slow axis As in the collimator optical system4of the present embodiment.FIGS.8A and8Bshow side views of each of the lens portions43,44of the collimator optical system4from the X and Y sides, respectively, similarly toFIGS.6A and6B.FIGS.8A and8Billustrate the component Bs in the slow axis As of the light beam in the collimator optical system4.

In the collimator optical system4of the present embodiment, as exemplified inFIG.8B, the first FAC41in the BTU40is configured with a shape having positive power also in the X direction corresponding to the slow axis As. Such a first FAC41also has the collimating function in the slow axis As in the collimator optical system4of the present embodiment. That is, when the light beam from the laser element30is incident on the first FAC41, the light beam is collimated for the component Bs in the slow axis As, as shown inFIG.8B, in addition to the component Bf in the fast axis Af (FIG.6A).

Moreover, in the collimator optical system4of the present embodiment, as exemplified inFIG.6A, the second FAC45after emission from the BTU40is configured with a shape that also has positive power in the Y direction corresponding to the slow axis As. Such a configuration can solve a new problem that arises from the above modification to the typical collimator optical system4xwith respect to the collimating function in the slow axis As. This point will be described below.

In the collimator optical system4of the present embodiment, the light beam incident on the BT42from the first FAC41is emitted with the slow axis As in the Y direction from the BT42due to the rotation of each of the axes Af, as described the above, as exemplified inFIG.8A. The component Bs of the light beam emitted from the BT42in this manner is collimated in the slow axis As in the first FAC41before incidence on the BT42(FIG.8B), resulting in the light beam being geometrically and optically parallel to the Z direction.

However, in the case of collimation before incidence on the BT42as described above, as shown inFIG.8A, the wave diffraction of light may also affect the component Bs in the slow axis As of the light beam on the +Z side after emission of the BT42. For this reason, even though collimation in the slow axis As has been performed once, the beam diameter in the slow axis As continues to expand toward the +Z side, which may cause the new problem that it is difficult to supply a light beam with a small diameter to the diffractive element20and the like.

Therefore, as shown inFIG.8A, the collimator optical system4of the present embodiment collimates the light beam again also in the Y direction of the slow axis As by the second FAC45on the emission side of the BT42. According to this, the collimator optical system4of the present embodiment can reduce the spread of the wave light beam diameter in the slow axis As and solve the above problem.

According to the collimation of the first FAC41in the present embodiment, the wave source at which the beam diameter in the slow axis As begins to expand as described above is located in the vicinity of the emission surface of the BT42and can coincide with the position of the wave source of the fast axis Af as shown inFIG.8A(cf.FIG.6B). Therefore, the second FAC45in the present embodiment can adopt a rotationally symmetric lens shape in which the position of such a wave source is the focal position, and can be achieved with a simple configuration. Note that the second FAC45may have a rotationally asymmetric lens shape, such as an anamorphic aspherical surface.

In the collimator optical system4of the present embodiment, the second FAC45is disposed as close to the BT42as the position where the SAC46is disposed in the typical collimator optical system4xfrom the viewpoint of reducing the beam diameter in the slow axis As, for example. This enables the collimator optical system4to be configured in a smaller size, which in turn enables the optical resonator2to be reduced in size. Furthermore, it is easy to reduce the beam diameter not only in the slow axis As but also in the fast axis Af.

The operations of the laser processing device1and the optical resonator2configured as described above will be described below.

The laser processing device1(FIG.1) of the present embodiment drives the LD array3of the optical resonator2, based on an oscillation condition set in the controller12, and causes the optical resonator2to generate laser light, for example. The laser processing device1performs various kinds of laser processing by irradiating the processing object15with the laser light generated by the optical resonator2from the processing head11under the control of the controller12, for example.

For example, in the laser processing device1as described above, the collimator optical system4of the optical resonator2collimates a plurality of light beams from the LD array3by the collimating functions in the fast axis Af and the slow axis As described above, and supplies the light beams to the diffractive element20.

The diffractive element20diffracts the light so that, when light with a wavelength λ is incident at an incident angle α, the light is emitted at a diffraction angle β, according to the diffraction condition as in the following equation (1) as an example, thereby combining the plurality of light beams from each LD array3.

where d represents a pitch of the diffractive element20, and m represents a diffraction order.FIG.9is a diagram illustrating a method of combining light beams in the diffractive element20of the optical resonator2.

In the diffractive element20, as exemplified inFIG.9, the incident angles α=α1, α2, α3of the light beams from the respective laser elements31,32,33are different from each other. In the optical resonator2of the present embodiment, different resonance wavelengths λ=λ1, λ2, λ3are set for the respective laser elements31,32,33based on the exemplified equation (1) as the above, so that the diffraction angles β of the light beams are the same. As a result, the plurality of light beams from the LD array3are emitted from the diffractive element20in the same direction after diffraction in the optical path illustrated inFIG.9.

FIG.10is a graph showing a spectrum of the resonance wavelength λ in the optical resonator2. In the graph ofFIG.10, the horizontal axis represents the wavelength and the vertical axis represents the intensity of light.

FIG.10shows resonance spectra S1to S3of the plurality of laser elements31to33in the LD array3and a common spontaneous emission spectrum S0. The resonance spectra S1, S2, S3indicate distributions of the resonance wavelengths λ of the respective LDs31,32,33. The spontaneous emission spectrum S0includes a specific wavelength band, e.g. a blue region. The light beam thus combined is incident on the output coupler25via the telescope optical system26, for example.

The output coupler25reflects a part of the light beam combined by the diffractive element20to move the reflected light beam back through the telescope optical system26and the like, thus returning the light beam to each laser element30. For example, due to the backward movement along the optical path illustrated inFIG.9, the light beams with the plurality of wavelengths λ=λ1to λ3are separated and emitted at different angles α1, α2, α3for the respective wavelengths λ1, λ2, λ3in the diffractive element20, similarly to the angles a of incidence on the diffractive element20from the respective laser elements31,32,33. The separated light beams further move back through the collimator optical system4and the like, and are returned to the laser elements31,32,33of the incident sources, respectively.

Thus, in the optical resonator2, return light for laser oscillation is supplied over various resonance wavelengths λ=λ1to λ3, enabling optical resonance to occur between the rear end surface of the LD array3and the output coupler25. The light beam having passed through the output coupler25is used as an output of the laser processing device1, for example.

2-1. Numerical Simulation for Light Spot

By a numerical simulation for a light spot that is a spot of a light beam obtained by the optical resonator2in the laser processing device1as described above, the effect of the collimator optical system4of the present embodiment can be verified. Such a numerical simulation will be described with reference toFIGS.11A and11B.

FIGS.11A and11Bare diagrams for explaining a numerical simulation for a light spot in the present embodiment.FIG.11Ashows a simulation result of the collimator optical system4xof the typical example.FIG.11Bshows a simulation result of the collimator optical system4of the present embodiment.

InFIGS.11A and11B, a numerical simulation is performed for a light spot formed by a light beam from one laser element30in the LD array3. In this simulation, the numerical calculation of the light spot is performed for the collimator optical system4x(FIGS.7A and7B) of the typical example including the typical FACs41x,45xand the collimator optical system4of the present embodiment including the FACs41,45.

FIGS.11A and11Beach show a two-dimensional distribution of light intensity obtained as a simulation result of a light spot formed on the incident surface of the diffractive element20. InFIGS.11A and11B, the horizontal axis indicates the position in the X direction corresponding to the fast axis Af, and the vertical axis indicates the position in the Y direction corresponding to the slow axis As, each in mm. In the drawings, the magnitude of the light intensity is shown by shading, with a substantially white portion indicating the light spot.

As shown inFIG.11B, the collimator optical system4of the present embodiment was checked that the size of the light spot (i.e., beam diameter) can be made smaller in the X direction, i.e. in the fast axis Af, than in the case ofFIG.11A. Thus, it is possible to improve the beam quality in the wavelength-combining optical resonator2.

Also, for the Y direction, i.e. the slow axis As, a result was obtained in which the beam diameter (FIG.11B) in the present embodiment is comparable to the beam diameter (FIG.11A) in the typical example. That is, it can be verified that the collimator optical system4of the present embodiment can solve the new problem regarding the collimating function in the slow axis As described above and supply a light beam with a sufficiently small diameter to the diffractive element20.

Moreover, according to the collimator optical system4of the present embodiment, as the beam diameter can be reduced in the direction of the fast axis Af as described above, the configuration of the optical resonator2can be further simplified. For example, in the telescope optical system26on the emission side from the diffractive element20, it is not necessary to reduce the light spot particularly in the direction of the fast axis Af, and the telescope optical system26can be omitted.

A numerical example of the first FAC41in the collimator optical system4of the present embodiment as described above will be described with reference toFIG.12.

FIG.12is a table showing a numerical example in the collimator optical system4of the present embodiment. The table ofFIG.12includes lens thickness data DI and emission surface data D11for the first FAC41of the present embodiment. Note that the incident surface of the first FAC41of the present embodiment is a flat surface as described above.

The lens thickness data DI indicates the thickness of the lens portion43of the first FAC41in the Z direction. The table ofFIG.12shows various dimensions related to the length of one lens portion43in the first FAC41. For example, millimeters are used as the unit of length, such as lens thickness.

The emission surface data D11defines the shape of the emission-side lens surface of the lens portion43in the first FAC41. For example, as shown inFIG.12, the emission surface data D11of the present embodiment includes an X curvature radius, a Y curvature radius, conic constants KX, KY in the X and Y directions, rotationally symmetric deformation coefficients AR, BR, CR, DR, and non-rotationally symmetric deformation coefficients AP, BP, CP, DP. The X curvature radius is the curvature radius of the lens portion43in the X direction. The Y curvature radius is the curvature radius of the lens portion43in the Y direction. For example, each curvature radius is measured in the vicinity of a vertex in a cross-section passing through the optical axis of the lens portion43. The emission surface of the first FAC41of the present embodiment constitutes an anamorphic aspherical surface defined by the following equation (2) for each lens portion43.

In the above equation (2), x and y represent positions on the lens surface in the X and Y directions, respectively, and z represents a sag amount of the lens surface in the Z direction. CUX represents curvature in the X direction and corresponds to the X curvature radius. CUY represents curvature in the Y direction and corresponds to the Y curvature radius.

The FAC41of the present embodiment is a toroidal array that satisfies the above equation (2) for each lens portion43. The emission-side lens surface of such a lens portion43is a rotationally asymmetric convex surface, that is, convex on the +Z side in each of the X and Y directions, and the convex shapes are different from each other.

In the first FAC41of the present embodiment, as exemplified inFIG.12, the absolute value of the X curvature radius is larger than the absolute value of the Y curvature radius on the emission surface, that is, the positive power in the X direction is smaller than the positive power in the Y direction. Such a first FAC41makes it possible to facilitate collimation corresponding to the characteristics of the fast axis Af and the slow axis As of the laser element30.

As described above, the collimator optical system4in the present embodiment is an example of an optical system that guides a plurality of light beams from the LD array3, which is an example of a light source array where the laser elements30as a plurality of light sources are arranged. The collimator optical system4includes the first FAC41, which is an example of a first collimator lens, the BT42, which is an example of an optical element, and the second FAC45, which is an example of a second collimator lens. The first FAC41is disposed facing the LD array3, and collimates each light beam in at least the Y direction out of the X direction and the Y direction. The Y direction is an example of the arrangement direction of the plurality of laser elements30. The Y direction is an example of the vertical direction intersecting the X direction and the Z direction, which is an example of the optical axis direction of each light beam. The BT42is disposed on the emission side (+Z side) of each light beam in the FAC41. The second FAC45is disposed on the emission side of each light beam in the BT42, and collimates each light beam at least in the X direction. The first FAC41includes a plurality of lens portions43arranged in the X direction corresponding to the plurality of laser elements30in the LD array3. Each of the plurality of lens portions43is provided rotationally asymmetrically to have positive power in the Y direction and positive power in the X direction.

According to the collimator optical system4described above, by introducing the first FAC41that constitutes the toroidal array with the lens portions43having positive power also in the X direction, it is possible to facilitate simple configuration of the optical system that guides the plurality of light beams from the LD array3.

In the present embodiment, the light beam of the LD array3is emitted from each laser element30in a state where the divergence angle in the X direction corresponding to the fast axis Af is smaller than the divergence angle in the Y direction corresponding to the slow axis As (cf.FIGS.6A and8B). In each lens portion43of the first FAC41, the positive power in the X direction is smaller than the positive power in the Y direction.

According to the collimator optical system4described above, the first FAC41can guide the light beam with positive power smaller than that in the X direction in the Y direction corresponding to the slow axis As in accordance with the characteristic that the divergence angle of the component Bs in the slow axis As is smaller than that of the component Bf in the fast axis Af in the light beam from the laser element30. As described above, the light beams can be guided from the first FAC41in accordance with the characteristic of the divergence angle different between the two axes Af, As, and it is possible to facilitate simplification of the configuration of the optical system for the light source array such as the LD array3.

In the present embodiment, the second FAC45has positive power in the X direction and positive power in the Y direction. This also enables the second FAC45to perform the light guide, such as collimation, of the light beam not only in the fast axis Af but also in the slow axis As, and facilitates simplification of the configuration of the collimator optical system4.

In the present embodiment, the second FAC45is provided rotationally symmetrically in the Z direction, and is disposed at a focal length from the emission-side surface of the BT42. It is thereby possible to simply configure the second FAC45that collimates the light beam in the fast axis Af and the slow axis As, and simplify the configuration of the collimator optical system4.

In the present embodiment, the first FAC41is disposed to collimate each light beam from the LD array3in the Y direction and the X direction. The second FAC45is disposed to collimate each light beam from the BT42in the X direction and the Y direction. As a result, in both the fast axis Af and the slow axis As, the first FAC41collimates each light beam, and the second FAC45collimates each light beam that can spread due to the wave influence of light from the BT42, so that the beam quality of the light beam output from the collimator optical system4can be improved.

In the present embodiment, the BT42rotates each light beam incident from the first FAC41around the Z direction. This enables the collimator optical system4to output the light beam such that the wavelengths of the plurality of light beams can be combined in the fast axis Af with the fine beam quality with the fast axis Af of the light beam directed in the X direction of the arrangement direction of the light beams.

In the present embodiment, the surface of the first FAC41on the emission side of each light beam has a convex shape in the Y direction and a convex shape in the X direction, which is different from the convex shape in the Y direction, for each lens portion43. It is thereby possible to control the light guide of the light beam rotationally asymmetrically for each lens portion43on the emission surface of the first FAC41, achieving simplification of the configuration of the collimator optical system4as a whole.

In the present embodiment, the surface of the first FAC41on the incident side of each light beam is a flat surface. This makes it possible to omit the processing for, in particular, axis alignment between the incident surface and the emission surface, and the like, in the first FAC41and simplify the manufacturing of the first FAC41.

In the present embodiment, for example, a laser device such as the optical resonator2includes the LD array3including a plurality of laser elements30that are arranged in the X direction and emit a plurality of light beams, and a collimator optical system4that guides the plurality of light beams from the LD array3. According to such a laser device, the first FAC41of the collimator optical system4can facilitate simple configuration of the optical system in the laser device using the LD array3.

In the present embodiment, the optical resonator2, which is an example of a laser device, further includes the diffractive element20and the output coupler25. The diffractive element20diffracts each light beam at an angle corresponding to the wavelength of each light beam guided from the LD array3in the optical system. The output coupler25reflects a part of the light beam diffracted by the diffractive element20back to the laser element30, and outputs the rest of the light beam. In such an optical resonator2, the first FAC41of the collimator optical system4can facilitate simply configuring the optical system.

In the present embodiment, the laser processing device1, which is a further example of the laser device, further includes the processing head11that irradiates a processing object with the light beam output from the output coupler25of the optical resonator2, in addition to the configuration of the optical resonator2. In such a laser processing device1, the first FAC41of the collimator optical system4can facilitate simple configuration of the optical system.

In the present embodiment, the first FAC41is an example of a collimator lens that collimates a plurality of light beams from the LD array3in which a plurality of laser elements30is disposed. The first FAC41includes the lens portion43as an example of a plurality of first lens portions arranged in the X direction corresponding to the plurality of laser elements30in the LD array3. Each of the plurality of lens portions43is provided rotationally asymmetrically to have positive power in the Y direction and positive power in the X direction. Such a first FAC41makes it possible to facilitate simple configuration of various optical systems that guide the plurality of light beams from the light source array such as the LD array3.

In the present embodiment, the BTU40is an example of an optical system including the first FAC41and the BT42that is disposed on the emission side of each light beam in the first FAC41. The BT42includes the oblique lens portions44as an example of a plurality of second lens portions arranged to rotate the respective light beams incident from the first FAC41around the Z direction. Such a BTU40can also facilitate simple configuration of an optical system that guides a plurality of light beams from the LD array3and the like.

In the present embodiment, there may be provided a laser device equipped with the LD array3including a plurality of laser elements30that are arranged in the X direction and emit a plurality of light beams, and the first FAC41that guides the plurality of light beams from the LD array3. For example, a laser module with the BTU40assembled to the LD array3may be provided. In such a laser module, the BT42may be omitted. Even in various systems using such a laser module, the first FAC41can facilitate simple configuration of the optical system.

Second Embodiment

A second embodiment will be described below with reference toFIGS.13A to16. In the first embodiment, the example in which the incident surface of the first FAC41in the collimator optical system4is a flat surface has been described. In the second embodiment, a collimator optical system with an incident surface of a first FAC having positive power will be described.

Hereinafter, the collimator optical system and the first FAC according to the present embodiment will be described, omitting, as appropriate, description of configurations and operations similar to those of the laser processing device1and the laser device such as the optical resonator2, the optical system such as the collimator optical system4, and the first FAC4according to the first embodiment.

FIGS.13A and13Billustrate a configuration of a collimator optical system4aaccording to the second embodiment.FIGS.13A and13Bshow side views of the collimator optical system4aof the present embodiment from the X and Y sides, respectively, similarly toFIGS.6A and6Band other drawings. The collimator optical system4aof the present embodiment includes a first FAC41awith a shape of a lens portion43adifferent from that of the lens portion43of the first embodiment in a configuration similar to that of the collimator optical system4of the first embodiment.

FIG.14illustrates the configuration of the first FAC41ain the second embodiment. In the first FAC41aof the present embodiment, the incident surface on the −Z side is formed of a cylindrical surface having positive power in the X direction and not having optical power in the Y direction for each lens portion43a.The emission surface on the +Z side of the first FAC41aof the present embodiment is formed of a cylindrical surface having positive power in the Y direction and not having optical power in the X direction.

The first FAC41aconfigured as described above has the collimating function in the slow axis As on the incident surface and the collimating function in the fast axis Af on the emission surface. Such a configuration also omit the processing for axial alignment between the incident surface and the emission surface in the first FAC41a,and can facilitate the manufacturing of the first FAC41a.

Returning toFIGS.13A and13B, in the collimator optical system4aof the present embodiment, the second FAC45may have a shorter focal length than the second FAC45of the first embodiment. The second FAC45is disposed closer to the emission surface of the BT42by the reduced focal length, for example.

FIGS.15A and15Bare diagrams for explaining a numerical simulation for a light spot in the collimator optical system4aof the second embodiment.FIG.15Aillustrates a case where the focal length of the second FAC45in the collimator optical system4aof the present embodiment is similar to that of the first embodiment.FIG.15Billustrates a case where the focal length of the second FAC45is reduced by half fromFIG.15A.

As shown inFIGS.15A and15B, it can be verified that the collimator optical system4aof the present embodiment can also obtain a light beam with a sufficiently small light spot, similarly to the first embodiment. For example, as shown inFIG.15B, reducing the focal length of the second FAC45enables a sufficient reduction in the size of the light spot in the Y direction (slow axis As), similarly to the first embodiment and the like.

FIG.16is a table showing a numerical example in the collimator optical system4aof the second embodiment. The table ofFIG.16includes lens thickness data D1, incident surface data D10a,and emission surface data D11afor the first FAC41aof the present embodiment, which are similar to those of the first embodiment.

The incident surface data D10aof the present embodiment includes an X curvature radius, a conic constant k, and various aspherical coefficients A, B, C, and D, for the incident-side lens surface of the lens portion43ain the first FAC41aas shown inFIG.16, for example. The conic constant k and the various aspherical coefficients A to D represent various coefficients of the following equation (3) that defines the shape of the aspherical surface.

In the above equation (3), z is the sag amount of the lens surface, r is the distance on the lens surface with respect to a reference position, and c is curvature at the vertex of the lens surface. In the above equation (3), the aspherical coefficients A to D of the order of 4 to 10 are used, but higher-order aspherical coefficients may be used. For example, in an axisymmetric aspherical surface, the sag amount z indicates displacement parallel to the Z direction, and the distance r indicates displacement in the radial direction with a position where the optical axis passes through the XY plane as the reference position.

For example, the lens portion43aof the present embodiment satisfies equation (3) for the aspherical surface with the incident surface data D10ain each XZ cross-section. That is, the shape of the entire incident-side lens surface of the lens portion43ais obtained by setting the same shape in the XZ cross-section at each position in the Y direction. As shown inFIG.14, the incident-side lens surface of such a lens portion43ais convex on the −Z side in the X direction.

The emission surface data D11aof the present embodiment includes a Y curvature radius and various coefficients k, A to D of equation (3), for the emission surface of the first FAC41a.For example, the emission surface of the first FAC41aof the present embodiment satisfies equation (3) for the aspherical surface with the emission surface data D11ain each YZ cross-section. As shown inFIG.14, the emission surface of such a first FAC41ais convex on the +Z side in the Y direction. The first FAC41aof the present embodiment is also a toroidal array that is rotationally asymmetric for each lens portion43a.

As described above, in the collimator optical system4aof the present embodiment, in the first FAC41a,the incident-side surface of each light beam has a convex shape for each lens portion43ain the X direction. In the first FAC41a,the emission-side surface of each light beam has a convex shape in the Y direction. The incident-side surface may have a cylindrical shape extending in the Y direction for each lens portion43a.The emission-side surface may have a cylindrical shape extending in the X direction. Similarly to the first embodiment, such a first FAC41acan also facilitate simple configuration of an optical system that guides a plurality of light beams from the LD array3and the like.

Third Embodiment

Hereinafter, a third embodiment will be described with reference toFIGS.17to19. In the first and second embodiments, the first FACs41,41awith only one of the emission surface and the incident surface having positive power in the X direction have been described. In the third embodiment, a collimator optical system with both an incident surface and an emission surface of a first FAC having positive power in the X direction will be described.

Hereinafter, the collimator optical system and the first FAC according to the present embodiment will be described, omitting, as appropriate, description of configurations and operations similar to those of various laser devices, optical systems, and the like according to the first and second embodiments.

FIG.17illustrates a configuration of a first FAC41bof the third embodiment. The first FAC41bof the present embodiment includes a lens portion43bwith a convex shape in the X direction on the incident side in a configuration similar to that of the first FAC41(FIG.4) of the first embodiment, for example.

For example, the lens portion43bof the present embodiment has a toroidal aspherical configuration on the emission side, similarly to the first embodiment, and has a cylindrical surface configuration on the incident side, similarly to the second embodiment. Such a first FAC41bhas the collimating function in the slow axis As with the incident surface and the emission surface, and has the collimating function in the fast axis Af with the emission surface.

FIG.18is a diagram for explaining a numerical simulation for a light spot in the collimator optical system of the third embodiment. The collimator optical system of the present embodiment includes the first FAC41binstead of the first FAC41of the first embodiment in a configuration similar to that of the first embodiment, for example. In the simulation ofFIG.18, such a first FAC41band the second FAC45with the focal length similar to that of the first embodiment are used to perform numerical calculation of the light spot, similarly to each of the above embodiments. As shown inFIG.18, it can be verified that the collimator optical system of the present embodiment can also obtain, with the first FAC41b,a similar effect to those of the first embodiment and the like with respect to the size of the light spot.

FIG.19is a table showing a numerical example in the collimator optical system of the third embodiment. The table ofFIG.19includes lens thickness data D1, incident surface data D10b,and emission surface data D11bfor the first FAC4bof the present embodiment, which are similar to those of the first and second embodiments.

In the lens portion43bof the present embodiment, the incident surface data D10bincludes an X curvature radius and a conic constant k as shown inFIG.19, for example. The incident surface of the first FAC41bin the present embodiment satisfies equation (3) for the aspherical surface for each lens portion43b,similarly to the incident surface of the second embodiment with coefficients A to D set to 0 except for the conic constant k in equation (3), for example.

In the present embodiment, as exemplified inFIG.19, the emission surface data D11bincludes an X curvature radius, a Y curvature radius, conic constants KX, KY in the X and Y directions, rotationally symmetric deformation coefficients AR, BR, CR, DR, and non-rotationally symmetric deformation coefficients AP, BP, CP, DP. The emission surface of the first FAC41bof the present embodiment satisfies equation (2) for the anamorphic aspherical surface for each lens portion43b,similarly to the emission surface of the first embodiment. The first FAC41bof the present embodiment is also a toroidal array that is rotationally asymmetric for each lens portion43b.

As described above, in the present embodiment, the surface of the first FAC41bon the incident side of each light beam has a convex shape for each lens portion43bin the X direction. The incident-side surface may have a cylindrical shape extending in the Y direction for each lens portion43b.Similarly to the first and second embodiments, such a first FAC41bcan also facilitate simple configuration of an optical system that guides a plurality of light beams from the light source array.

Fourth Embodiment

A fourth embodiment will be described below with reference toFIGS.20to22. In the third embodiment, the first FAC41bwith the incident surface having positive power in the X direction has been described. In the fourth embodiment, a collimator optical system with the incident surface of the first FAC having positive power in the Y direction will be described.

Hereinafter, the collimator optical system and the first FAC according to the present embodiment will be described, omitting, as appropriate, description of configurations and operations similar to those of various laser devices, optical systems, and the like according to the first to third embodiments.

FIG.20illustrates a configuration of a first FAC41cof the fourth embodiment. The first FAC41cof the present embodiment includes a lens portion43bwith a convex shape in the Y direction on the incident side in a configuration similar to that of the first FAC41(FIG.4) of the first embodiment, for example.

For example, the lens portion43cof the present embodiment has a toroidal aspherical configuration on the emission side, similarly to the first embodiment, and has a cylindrical surface configuration on the incident side, similarly to the emission surface of the second embodiment. Such a first FAC41chas the collimating function in the fast axis Af with the incident surface and the emission surface, and has the collimating function in the slow axis As with the emission surface.

FIG.21is a diagram for explaining a numerical simulation for a light spot in the collimator optical system of the fourth embodiment. The collimator optical system of the present embodiment includes the first FAC41cinstead of the first FAC41of the first embodiment in a configuration similar to that of the first embodiment, for example. In the simulation ofFIG.21, such a first FAC41cand the second FAC45with the focal length similar to that of the first embodiment are used to perform numerical calculation of the light spot, similarly to each of the above embodiments. As shown inFIG.21, it can be verified that the collimator optical system of the present embodiment can also obtain, with the first FAC41c,a similar effect to those of the first embodiment and the like with respect to the size of the light spot.

FIG.22is a table showing a numerical example in the collimator optical system of the fourth embodiment. The table ofFIG.22includes lens thickness data D1, incident surface data D10c,and emission surface data D11cfor the first FAC4cof the present embodiment, which are similar to those of the first to third embodiments.

In the lens portion43cof the present embodiment, the incident surface data D10cincludes a Y curvature radius and a conic constant k as shown inFIG.22, for example. The incident surface of the first FAC41cin the present embodiment satisfies equation (3) for the aspherical surface, similarly to the emission surface of the second embodiment with coefficients A to D set to 0 except for the conic constant k in equation (3), for example.

The emission surface data D11cof the present embodiment indicates various coefficients in equation (2) for the anamorphic aspherical surface, similarly to the emission surface data D11bof the third embodiment. Similarly to each of the above embodiments, the first FAC41cof the present embodiment is also a toroidal array that is rotationally asymmetric for each lens portion43c.In the first FAC41cof the present embodiment, with the incident surface not having optical power in the X direction, the axial alignment is not necessary between the incident surface and the emission surface, and manufacturing can be facilitated.

As described above, in the present embodiment, the surface of the first FAC41con the incident side of each light beam has a convex shape in the Y direction. The incident-side surface may have a cylindrical shape extending in the X direction. Similarly to the first to third embodiments, such a first FAC41ccan also facilitate simple configuration of the optical system that guides the plurality of light beams from the light source array.

Other Embodiments

As the above, the first to fourth embodiments have been described as examples of the techniques disclosed in the present application. However, the technique in the present disclosure is not limited thereto, and can also be applied to embodiments in which change, replacement, addition, omission, and the like are made as appropriate. It is also possible to combine the constituent elements described in each of the above embodiments to provide a new embodiment. Other embodiments will be described below.

In the first embodiment described above, the collimator optical system4has been described in which the collimation in the slow axis As (X direction) is performed in the first FAC41, and the collimation in the slow axis As (Y direction) is performed again in the second FAC45. The collimator optical system4of the present embodiment does not necessarily perform collimation in the slow axis As twice, once in the first FAC41and once the second FAC45. The positive power in the X direction of the first FAC41and the positive power in the Y direction of the second FAC45may be appropriately distributed such that the collimation in the slow axis As is performed once for the first and second FACs41,45as a whole. The light beam output from the collimator optical system of the present embodiment is not necessarily completely parallel light in the slow axis As, and may have a divergence angle within an appropriately allowable range. The collimation in each of the axes As and Af may be appropriately performed within a range of tolerance.

As described above, in the present embodiment, the first FAC41may not collimate the light beam from the laser element30in the X direction. The second FAC45may not collimate the light beam from the BT42in the Y direction. Even in this case, similarly to the first embodiment and the like, it is possible to facilitate simple configuration of the optical system that guides the plurality of light beam according to various specifications of the optical system into which the first FAC41and the like are introduced.

In the above embodiments, the BT42has been exemplified as an example of the optical element in the collimator optical system4. In the present embodiment, the collimator optical system4may include an optical element different from the BT42. For example, an optical element may be used which does not rotate each of the light beams from the LD array3and has a light-condensing function, such as emission of the plurality of light beams having passed through the optical element at a light beam angle that brings the light beams closer to each other as they travel.

In the above embodiments, the example of the laser processing device1using the wavelength-combining optical resonator2has been described. In the present embodiment, the laser processing device1is not particularly limited to the wavelength-combining type, and may be a spatially combining type, for example. In such a laser processing device1as well, the use of the first FAC41can facilitate simple configuration of the optical system that spatially combines a plurality of light beams from the LD array.

In the above embodiments, the example in which the resonance wavelength band of the optical resonator2is the blue region has been described. In the present embodiment, the resonance wavelength band of the optical resonator2is not limited to the above, and may be, for example, a red region, such as a wavelength of 900 nm to 950 nm.

As described above, the embodiments have been described as examples of the technique in the present disclosure. For this purpose, the accompanying drawings and the detailed description have been provided.

Accordingly, some of the constituent elements described in the accompanying drawings and the detailed description can include not only constituent elements essential for solving the problem, but also constituent elements not being essential for solving the problem but provided for illustrating the above technique. For this reason, these nonessential constituent elements should not be recognized as essential as soon as these nonessential constituent elements are described in the accompanying drawings and the detailed description.

In addition, since the embodiments described above are intended to exemplify the technique in the present disclosure, it is possible to make various modifications, replacements, additions, omissions, and the like within the scope of claims or the equivalent thereto.

INDUSTRIAL APPLICABILITY

The present disclosure is applicable to various applications using a plurality of light beams, and is applicable to various laser processing techniques, for example.