Patent Description:
<CIT> discloses a wavelength beam combining laser system in which individual light beams are superposed to form a coupling beam. <CIT> also discloses that light beams from a plurality of diode bars are condensed on an optical fiber from the viewpoint of increasing light outputs. Further, for the purpose of reducing the size of the laser system, an optical system for removing arrangement of a coupling lens in wavelength beam combining from a focal length is separately included, and a beam rotor is rotated.

<CIT> shows a wavelength combining laser apparatus including a semiconductor laser to emit a plurality of laser beams and a wavelength combining element to combine the plurality of laser beams into a single laser beam. The wavelength combining laser apparatus of <CIT> also includes a cross-coupling reduction optical system having a positive power in a laser beam combining direction perpendicular to an optical axis of the single laser beam that is output from the wavelength combining element; and a partially-reflective mirror to reflect the single laser beam that passes through the cross-coupling reduction optical system and to allow the single laser beam to transmit through and exit the partially-reflective mirror. <CIT> discloses an optical resonator including a light source and an output coupler. The light source emits light. The output coupler resonates the light emitted from the light source to emit output light. The output coupler includes a mirror, a polarization beam splitter, at least one quarter-wave plate, and an adjuster. <CIT> shows optical systems and components thereof which may be used for maintaining the brightness of laser emitter bar output beams. <CIT> discloses a laser module comprising a laser diode including a plurality of emitters arrayed along a first line, and emitting a laser beam from each one of the plurality of emitters at an emitting surface; a first collimator lens disposed facing the emitting surface of the laser diode, and having positive power along a fast axis; a beam twister disposed facing the laser beam given off from the first collimator lens, and turning the laser beam by approx. <NUM> degrees; and an optical element disposed facing the laser beam given off from the beam twister, and including a plurality of incident surfaces placed in a stepped shape.

The present disclosure provides an optical unit capable of improving a degree of freedom in design for guiding a plurality of light beams, a beam coupling device, and a laser processing machine.

The optical unit according to the present disclosure is provided as defined in claim <NUM>.

The beam coupling device according to one aspect of the present invention is defined in claim <NUM>.

The beam coupling device according to another aspect of the present invention is defined in claim <NUM>.

The laser processing machine according to the present invention is defined in claim <NUM>.

According to the optical unit, the beam coupling device, and the laser processing machine according to the present disclosure, it is possible to improve the degree of freedom in design for guiding a plurality of light beams.

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

It should be noted that the applicant provides the accompanying drawings and the following description in order for those skilled in the art to fully understand the present disclosure, and does not intend to limit the subject matter described in the claims. The invention is defined in the accompanying claims.

In the first embodiment, an example of applying an optical unit to a beam coupling device for wavelength beam combining and a laser processing machine provided with the beam coupling device will be described.

A configuration of the laser processing machine and the beam coupling device according to the first embodiment will be described with reference to <FIG> is a diagram illustrating a configuration of a laser processing machine <NUM> according to the present embodiment.

<FIG> is a diagram illustrating a configuration of a laser processing machine <NUM> according to the present embodiment. For example, the laser processing machine <NUM> includes a beam coupling device <NUM>, a transmission optical system <NUM>, a processing head <NUM>, and a controller <NUM>. The laser processing machine <NUM> is a device that irradiates various workpieces <NUM> with laser light to perform various laser processing. For example, the various laser processing include, laser welding, laser cutting, and laser perforation.

The beam coupling device <NUM> is a device that couples a plurality of light beams emitted separately, in order to supply the laser light of the laser processing machine <NUM>, for example. In the present embodiment, the beam coupling device <NUM> is configured by adopting wavelength beam combining in which a plurality of light beams are combined with resonating at different wavelengths. The beam coupling device <NUM> for wavelength beam combining can facilitate to obtain high beam quality and to narrow down the beam diameter.

In the laser processing machine <NUM>, the transmission optical system <NUM> is an optical system that transmits the laser light from the beam coupling device <NUM> to the processing head <NUM>, including an optical fiber, for example. The processing head <NUM> is a device that is arranged to face the workpiece <NUM> to irradiate the workpiece <NUM> with a laser light transmitted from the beam coupling device <NUM>, for example.

The controller <NUM> is a control device that controls the overall operation of the laser processing machine <NUM>. The controller <NUM> includes, for example, a CPU or MPU that cooperates with software to realize a predetermined function. The controller <NUM> may be provided with an internal memory for storing various programs and data, and various interfaces capable of inputting oscillation conditions and the like by the operation of the user. The controller <NUM> may include a hardware circuit such as ASIC or FPGA that realize various functions. Further, the controller <NUM> may be integrally configured with the drive circuit of the light source.

As illustrated in <FIG>, the beam coupling device <NUM> of the present embodiment includes an LD bar <NUM> which is an example of a light source, an optical unit <NUM>, a coupling lens <NUM>, a diffraction element <NUM>, and an output coupler <NUM>, for example. The beam coupling device <NUM> of the present embodiment constitutes an external resonance type optical resonator that resonates light in an optical path that reciprocates between the LD bar <NUM> and the output coupler <NUM>.

The LD bar <NUM> is formed of an array of light emitters including a plurality of LDs (laser diodes) <NUM> to <NUM> arranged one-dimensionally. Hereinafter, a direction in which the LDs <NUM> to <NUM> are arranged is referred to as "X direction", a direction of the optical axis of the light beam emitted by the LD bar <NUM> from the LDs <NUM> to <NUM> is referred to as "Z direction", and a direction orthogonal to the X and Z directions is referred to as "Y direction".

<FIG> illustrates three LD <NUM>, <NUM>, and <NUM> in the LD bar <NUM>. The number of LDs <NUM> to <NUM> included in the LD bar <NUM> is e.g. tens to hundreds. The plurality of LDs <NUM> to <NUM> have a common spontaneous emission spectrum depending on the material of the LD light emitting layer, for example (refer to <FIG>). Hereinafter, the generic term of LDs <NUM> to <NUM> may be referred to as "LD <NUM>". Each LD <NUM> is an example of a light emitter constituting the emitter of the LD bar <NUM>, to emit a light beam toward the +Z side, respectively.

The optical unit <NUM> is an optical system that adjusts and guides a plurality of light beams from each LD <NUM> of the LD bar <NUM>. The optical unit <NUM> is arranged on the +Z side of the LD bar <NUM>. According to the optical unit <NUM> of the present embodiment, the degree of freedom in design can be improved for the beam coupling device <NUM> for wavelength beam combining, which is likely to have a complicated optical design, and the size of the beam coupling device <NUM> can be redueced. The details of the optical unit <NUM> will be described later.

The coupling lens <NUM> is arranged on the +Z side of the optical unit <NUM> with a distance D1, for example. The distance D1 on the -Z side of the coupling lens <NUM> is set to the focal length of the coupling lens <NUM>, for example. The plurality of light beams from each LD <NUM> of the LD bar <NUM> enters the coupling lens <NUM> via the optical unit <NUM>, to be are condensed at a position where a distance D2 is placed on the +Z side from the coupling lens <NUM>. The coupling lens <NUM> collimates each light beam at the condensing.

The diffraction element <NUM> is arranged at a position of a distance D2 on the +Z side from the coupling lens <NUM>, for example. The diffraction element <NUM> is a dispersive element in which a transmission type diffraction grating is formed, for example. In the present embodiment, the diffraction grating of the diffraction element <NUM> satisfies the diffraction conditions for coupling the light beams emitted from a plurality of LDs <NUM> to <NUM> to guide in the same direction. The diffraction conditions of the diffraction element <NUM> is expressed by the following Equation (<NUM>), for example. <MAT> where, α is an incident angle of the light beam incident on the diffraction element <NUM>, and β is a diffraction angle of the light beam emitted after diffraction. Further, λ is a wavelength of the light to be diffracted and corresponds to the resonance wavelength. d is a pitch of the diffraction grating in the diffraction element <NUM>. m is a diffraction order, e.g. a natural number.

<FIG> is a diagram illustrating a method for coupling a light beam in the diffraction element <NUM> of the beam coupling device <NUM>. In the diffraction element <NUM>, the incident angles α = α1, α2, and α3 of the light beams from the LD <NUM>, <NUM>, and <NUM> are different from each other, as illustrated in <FIG>. In the beam coupling device <NUM> of the present embodiment, different resonance wavelengths λ are set for each LDs <NUM> to <NUM> so that the diffraction angles β of the LDs <NUM> to <NUM> are the same based on the above Equation (<NUM>). As a result, the light beams from the plurality of LDs <NUM> to <NUM> are emitted from the diffraction element <NUM> in the same direction after diffraction, to obtain the light beam as a coupling result.

<FIG> is a graph illustrating a spectrum of resonance wavelengths λ in the beam coupling device <NUM>. In the graph of <FIG>, a horizontal axis represents a wavelength [nm] and a vertical axis represents a light intensity.

<FIG> illustrates individual resonance spectra S1 to S3 in the plurality of LDs <NUM> to <NUM> in the LD bar <NUM> and the common spontaneous emission spectrum S0. Each of resonance spectra S1, S2, and S3 indicates the distribution of the resonance wavelength λ of each LD <NUM>, <NUM>, and <NUM>. The spontaneous emission spectrum S0 includes a wavelength band in the <NUM> band, e.g. <NUM> to <NUM>. According to the resonance spectra S1 to S3, the resonance wavelength λ is longer as in order from LD <NUM> to LD <NUM> based on the positions arranged in the LD bar <NUM>.

As illustrated in <FIG>, regarding the beam coupling device <NUM> of the present embodiment, various parameters of the beam coupling device <NUM> are set so that the resonance spectra S1 to S3 of all LDs <NUM> to <NUM> in the LD bar <NUM> are within the range of the spontaneous emission spectrum S0. For example, the various parameters of the beam coupling device <NUM> are the pitch of LDs <NUM> to <NUM> in the LD bar <NUM>, the focal length of the coupling lens <NUM>, the shape of the diffraction grating in the diffraction element <NUM>, and the distance between the respective portions of the beam coupling device <NUM>.

Returning to <FIG>, the output coupler <NUM> is arranged in the direction to which the light beam diffracted by the diffraction element <NUM> is emitted. The output coupler <NUM> includes a mirror element having a predetermined transmittance and reflectance, for example. Among the light beams incident on the output coupler <NUM> from the diffraction element <NUM>, the transmission component corresponding to the transmittance is emitted to the transmission optical system <NUM> as the output of the beam coupling device <NUM>, for example. On the other hand, the reflection component corresponding to the reflectance is returned to the diffraction element <NUM> due to optical resonance. The output coupler <NUM> may be provided with a mechanism capable of adjusting such reflectance and transmittance.

According to the beam coupling device <NUM> as described above, high beam quality can be obtained by performing wavelength beam coupling as an external resonance type optical resonator. On the other hand, in the external resonance type optical resonator that performs wavelength beam coupling, there is a problem in that the optical design is complicated and the device configuration is large. To address this , the present embodiment provides an optical unit <NUM> that can improve the degree of freedom in design such an optical design and can reduce the size of the beam coupling device <NUM>.

The details of the configuration of the beam coupling device <NUM> according to the present embodiment will be described with reference to <FIG> illustrates a plan view of the beam coupling device <NUM> as viewed from the Y direction. <FIG> illustrates a side view of the beam coupling device <NUM> as viewed from the X direction.

In the beam coupling device <NUM> of the present embodiment, the optical unit <NUM> includes a BTU (beam twister unit) <NUM> arranged opposite to the LD bar <NUM>, and a SAC (slow axis collimator) <NUM> arranged on the +Z side of the BTU <NUM>, for example. The coupling lens <NUM> is configured with a cylindrical lens having a positive refractive power in the X direction, for example. The BTU <NUM> and the SAC <NUM> may be provided separately. In this case, the BTU <NUM> is an example of the optical unit in the present embodiment.

In the present embodiment, the distance D1 from the BTU <NUM> of the optical unit <NUM> to the coupling lens <NUM> is set to a focal length Df of the coupling lens <NUM>, in view of collimating each light beam from the LD bar <NUM> as described above, for example. On the other hand, the distance D2 from the coupling lens <NUM> to the diffraction element <NUM> may be set in view of condensing each light beam on the diffraction element <NUM>, for example.

Here, if a plurality of light beams from the LD bar <NUM> are incident on the coupling lens <NUM> in parallel with each other, the above described light condensing causes the distance D2 to the diffraction element <NUM> to be the focal length Df, resulting in the increased size of the device configuration. Therefore, in the present embodiment, the direction of a plurality of light beams from the LD bar <NUM> is controlled by the BTU <NUM> of the optical unit <NUM>.

<FIG> each exemplify a chief ray L11 of the light beam from the outer LD <NUM> and a chief ray L13 of the light beam from the central LD <NUM> in the LD bar <NUM>. In the beam coupling device <NUM> of the present embodiment, the central LD <NUM> has the chief ray L13 that travels straight through the optical unit <NUM> and the coupling lens <NUM> and is parallel to the Z direction, for example.

According to the BTU <NUM> of the present embodiment, as illustrated in <FIG>, the chief ray L11 of the light beam from the outer LD <NUM> in the LD bar <NUM> is directed inward in the X direction. As a result, the plurality of light beams can be condensed with the chief rays L11 and L13 intersecting each other at the distance D2 shorter than the focal length Df from the coupling lens <NUM>, for example. Therefore, the distance D2 to the diffraction element <NUM> can be shortened from the focal length Df, and the size of the beam coupling device <NUM> can be reduced.

Further, the arrangement of the coupling lens <NUM> can be changed by controlling the chief ray directions of the plurality of light beams by the BTU <NUM>. For example, the focal length Df of the coupling lens <NUM> can be set to an appropriate length from the viewpoint of collimation described above, and can be set to e.g. <NUM> or more. Additionally, the degree of freedom in design is also obtained so that a light-condensing function is realized by the collaboration between the BTU <NUM> and the coupling lens <NUM>.

Further, according to the optical unit <NUM> of the present embodiment, the chief ray L11 directed inward in the X direction by the BTU <NUM> can be prevented from being directed inward or outward in the Y direction, as illustrated in <FIG>. The external resonance type optical resonator is conceivable that, if the light ray angle of the light beam deviates in the Y direction, the incident angle of the light beam with respect to the output coupler <NUM> (refer to <FIG>) changes, thereby causing a problem in optical resonance. In contrast to this, according to the optical unit <NUM> of the present embodiment, the light ray direction in the X direction can be controlled without interfering with the light ray angle in the Y direction, and the above-mentioned problems can be avoided. As described above, according to the optical unit <NUM> of the present embodiment, it is possible to improve the degree of freedom in various optical designs for the beam coupling device <NUM>.

Hereinafter, the details of the optical unit <NUM> of the beam coupling device <NUM> in the present embodiment will be described.

First, the basic configuration of the optical unit <NUM> will be described with reference to <FIG>. <FIG> illustrate the basic configuration of the optical unit <NUM>.

<FIG> illustrates a plan view of the optical unit <NUM> in the basic configuration. <FIG> illustrates a side view of the optical unit <NUM> of <FIG> illustrate an optical path of the light beam from one LD <NUM>, such as the central LD <NUM>.

The BTU <NUM> in the optical unit <NUM> includes a BT (beam twister) <NUM> and a FAC (fast axis collimator) <NUM>. In the optical unit <NUM>, the FAC <NUM>, the BT <NUM>, and the SAC <NUM> are arranged in order from the vicinity of LD <NUM> to the +Z side, for example.

In the present embodiment, the LD <NUM> emits a light beam having a fast axis Af and a slow axis As. In the fast axis Af of the light beam, the beam diameter expands more rapidly than in the slow axis As, and it is easier to obtain high beam quality. Before the light beam of LD <NUM> is incident on the optical unit <NUM>, the fast axis Af of the light beam is directed in the Y direction and the slow axis As is directed in the X direction.

The FAC <NUM> is provided for collimating a light beam on the fast axis Af, and is formed of a cylindrical lens having a positive refractive power, for example. As illustrated in <FIG>, the FAC <NUM> is arranged at a focal length position from the +Z side of the LD bar <NUM> with the longitudinal direction being the X direction, for example. In this example, the light beam from LD <NUM> is collimated by the FAC <NUM> in the Y direction (i.e., the fast axis Af), and then incident on BT <NUM>.

<FIG> illustrates a configuration example of the BT <NUM>. For example, the BT <NUM> is an optical element that rotates a plurality of light beams respectively, and the BT <NUM> includes a plurality of oblique lens portions <NUM>. The oblique lens portion <NUM> is a portion of the BT <NUM> that constitutes a lens for each LD <NUM>, and constitutes e.g. a cylindrical lens. The BT <NUM> and the FAC41 may be provided separately. In this case, the BT <NUM> is an example of the optical unit in the present embodiment.

The BT <NUM> is formed so as to arrange a plurality of oblique lens portions <NUM> at a predetermined pitch in the X direction, for example. In this configuration example, the oblique lens portion <NUM> is inclined by <NUM>° with respect to the both arrangement direction (i.e., X direction) and the thickness direction (i.e., Y direction) of the BT <NUM>. The inclination of the oblique lens portion <NUM> in the BT <NUM> does not necessarily have to be <NUM>°, and may be <NUM>° to <NUM>° with respect to the Y direction, for example.

In the example of <FIG>, the BT <NUM> rotates the light beam incident from the LD <NUM> through the FAC <NUM> by a rotation angle of <NUM>° in the XY plane. As a result, the slow axis As of the light beam emitted from the BT <NUM> is oriented in the Y direction, and the fast axis Af is oriented in the X direction. The light beam emitted from the BT <NUM> is divergent light in the Y direction and parallel light in the X direction.

The SAC <NUM> is provided for collimating a light beam on the slow axis As, and is formed of a cylindrical lens having a positive refractive power, for example. As illustrated in <FIG>, the SAC <NUM> is arranged at a focal length position from the +Z side of the BTU <NUM> with the longitudinal direction being the X direction, for example. In this example, the light beam from the BT <NUM> is collimated by the SAC <NUM> in the Y direction (i.e., the slow axis As), and then exits from the optical unit <NUM>.

According to the above optical unit <NUM>, the light beam emitted from each LD <NUM> of the LD bar <NUM> is basically collimated in the fast axis Af and the slow axis As. However, due to the wave characteristics of light, the beam diameter can widen by an influence of waves from the +Z side surface of the BT <NUM>, particularly in the fast axis Af. To address this, the beam coupling device <NUM> of the present embodiment makes possible to suppress the above-mentioned influence by collimating each light beam by the coupling lens <NUM>.

In the present embodiment, various chief rays are controlled by adjusting the arrangement of the oblique lens portion <NUM> in the BT <NUM> as well as utilizing the basic functions of each portion of the optical unit <NUM> as described above. Hereinafter, a configuration example of such an optical unit <NUM> will be described.

<FIG> illustrates a configuration example of the BT <NUM> of the optical unit <NUM> in the present embodiment. <FIG> illustrates a front view of the optical unit <NUM> as viewed from the -Z side together with a plurality of LDs <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>. For example, the light beams from LDs <NUM> to <NUM> pass through the facing lens portions <NUM> from the -Z side to the +Z side, with the Z direction being the optical axis direction. The BT <NUM> of the present embodiment is configured by shifting the pitch of the oblique lens portion <NUM> between both end faces of the ±Z sides, that is, the emission side and the incident side of the light beam from each LD <NUM>.

<FIG> illustrates a cross-sectional view of an XZ plane in the BT <NUM> of <FIG>. The BT <NUM> of this configuration example is configured so that a pitch Wo between the oblique lens portions <NUM> on the end face on the +Z side is smaller than a pitch Wi on the end face on the -Z side. The pitch Wi on the -Z side is set to be the same as the pitch between the LDs <NUM> in the LD bar <NUM>, for example. In the BT <NUM> of this configuration example, the center of the central oblique lens portion <NUM> matches on both sides of the ±Z side, for example.

For example, a difference between the pitches Wi and Wo is set to be sufficiently smaller than each of the pitches Wi and Wo, and is e.g. <NUM> times or less of each of the pitches Wi and Wo. The difference between the pitches Wi and Wo may be set in consideration of the number of the oblique lens portions <NUM> or LD <NUM>. For example, the difference between the pitches Wi and Wo is <NUM> times or more that of each of the pitches Wi and Wo.

<FIG> exemplify the optical path in the optical unit <NUM> of this configuration example. <FIG> corresponds to the A-A cross section in the optical unit <NUM> of <FIG>. The A-A cross section is an XZ plane in which each LDs <NUM> to <NUM> of the LD bar <NUM> is located. <FIG> correspond to the B-B cross-sectional view and the C-C cross-sectional view in <FIG>, respectively. The B-B cross section is the YZ plane where the central LD <NUM> is located. The C-C cross section is the YZ plane where the outer LD <NUM> is located.

According to the optical unit <NUM> of the present embodiment, as illustrated in <FIG>, the chief ray of the light beam from each LD <NUM>, entering the FAC <NUM>, goes straight along the Z direction to reach the +Z side surface of the BT <NUM>. On the +Z side surface of the BT 50A, the chief ray La can be directed more outward in the X direction and inclined in the Y direction as the LD 31a is located more outside in the X direction, according to the pitch Wo of the oblique lens portion <NUM> which is smaller than that of the -Z side surface.

Each of chief rays La and Lc exits from the BT <NUM> to reach the SAC <NUM>. Here, as the SAC <NUM> collimates the light beam in the Y direction, the inclination of the chief ray Lc in the Y direction can be corrected in the SAC <NUM> as illustrated in <FIG>.

As described above, according to the optical unit <NUM> of the present embodiment, the chief ray Lc of the outer LD 31c in the X direction can be restricted to the X direction and directed inward.

Examples relating to the configuration example of the beam coupling device <NUM> and the optical unit <NUM> of the present embodiment as described above will be described below.

As a numerical example of the beam coupling device <NUM> of the present embodiment, a numerical simulation using the optical unit <NUM> of the above configuration example were performed. In this simulation, the focal length of the SAC <NUM> was set to <NUM>, the focal length of the coupling lens <NUM> was set to <NUM>, and the pitch between LDs <NUM> of LD bar <NUM> was set to <NUM>. In such a simulation environment, as the present embodiment, the pitch Wo on the +Z side of the BT <NUM> was set to be <NUM> smaller than the pitch Wi on the -Z side. The pitch Wi on the -Z side of the BT <NUM> was set to be the same as the pitch between the LDs of the LD bar <NUM>.

<FIG> illustrates the simulation results of the beam coupling device <NUM> of the present embodiment. In this simulation, numerical calculation of the chief ray on the +X side was performed in order to check the effect of shifting the pitch Wi and Wo of the BT <NUM> in the above settings. Each row in the drawing shows the numerical calculation result for each surface number from the object side (i.e., -Z side) to the image side (i.e., +Z side) with the chief ray passing through each portion of the beam coupling device <NUM>. As a numerical calculation result, "X" represents an X coordinate, "Y" represents a Y coordinate, "TANX" represents an inclination in the XZ plane with a tangent function, and "TANY" represents an inclination in the YZ plane with the tangent function. The position of LD <NUM> corresponding to the numerically calculated chief ray was <NUM> in the X coordinate.

According to the simulation results in <FIG>, "TANX" was changed from a zero value at the emission by the LD <NUM> to a positive value "-<NUM>" after the exit of the SAC <NUM>, indicating that the chief ray on the +X side is directed inward. Furthermore, "TANY" was not changed at a zero value from the exit of the SAC <NUM> to the diffraction element <NUM>. Therefore, it was checked that the outer chief ray in the X direction can be directed inward in the X direction with suppressing the influence in the Y direction according to the deviation of Wi and Wo of the BT <NUM>.

<FIG> illustrates the simulation results of a comparative example with respect to <FIG>. In this comparative example, the same numerical calculation as in <FIG> was performed in a case where the BTU pitch is not shifted on both sides of the ±Z side but the BTU is rotated in the XY plane. A technique for making an outer chief ray by rotating an optical element such as a BTU has been known in the related art (e.g., Patent Document <NUM>). The rotation angle of BTU was set to <NUM>°.

According to the simulation result of <FIG>, the value "-<NUM>" of "TANX" after the exit of the SAC is equivalent to the example of <FIG>. On the other hand, "TANY" had a value of "<NUM>" after the exit of the SAC. This indicates that, in this comparative example, directing the outer chief ray inward in the X direction causes an influence of an inclination in the Y direction. From the above, it was checked that the optical unit <NUM> of the present embodiment can realize the inward direction of the outer chief ray in the X direction with suppressing the influence in the Y direction as compared with the technique in the related art.

As described above, the optical unit <NUM> in the present embodiment is provided for guide a plurality of light beams. The BT <NUM> of the optical unit <NUM> includes a plurality of oblique lens portions <NUM> as an example of a plurality of lens portions through which a plurality of light beams are transmitted. The plurality of oblique lens portions <NUM> are arranged in an arrangement direction (e.g., the X direction) that intersects the optical axis direction (e.g., the Z direction) along which the light beam is transmitted. Each oblique lens portion <NUM> is inclined with respect to a thickness direction (e.g., the Y direction) intersecting the optical axis direction and the arrangement direction. In the optical unit <NUM> of the present embodiment, the pitch Wo at which the oblique lens portions <NUM> are arranged in the end face on the +Z side as an example of one end face of both end faces of the BT <NUM> in the optical axis direction is smaller than the pitch Wi at which the oblique lens portion <NUM> is arranged in the end face on the -Z side as the other end face.

According to the above optical unit <NUM>, in an example when a plurality of light beams are incident from the -Z side at the same pitch as the pitch Wi of the oblique lens portion <NUM> on the -Z side of the BT <NUM>, as the pitch Wo of the oblique lens portion <NUM> is smaller on the +Z side, the outer chief ray L11 of the light beam in the X direction can be directed inward. Therefore, it is possible to control the light ray direction that guides the light beam so as to condense a plurality of light beams. In this way, the BT <NUM> of the optical unit <NUM> can improve the degree of freedom in design for guiding a plurality of light beams.

In the present embodiment, the BTU <NUM> of the optical unit <NUM> includes a FAC <NUM> as an example of the first collimator lens. The FAC <NUM> is arranged to face the end face on the -Z side, which is either end face of the both end faces on the ±Z side of the BT <NUM>, with a light beam being incident on the oblique lens portion <NUM> from the end face. According to the BTU <NUM> of the present embodiment, it is possible to control the light ray direction of a plurality of light beams incident from the FAC <NUM>.

In the present embodiment, the optical unit <NUM> further includes a SAC <NUM> as an example of the second collimator lens. The SAC <NUM> is arranged to face the end face on the +Z side, which is the opposite side of the end face facing the FAC <NUM>, among both end faces of the BT <NUM>, to collimate the light beam emitted from the end face. According to the SAC <NUM>, it is possible to correct the light ray direction of a light beam whose the light ray direction is changed in BT <NUM> incident from the FAC <NUM>, and it is possible to easily control the light ray direction of a plurality of the light beams.

The beam coupling device <NUM> in the present embodiment includes an LD bar <NUM> as an example of a light source, an optical unit <NUM>, and a diffraction element <NUM>. The LD bar <NUM> includes LDs <NUM> to <NUM> as a plurality of light emitters capable of resonating at different wavelengths from each other, to emit respectively a plurality of light beams from each of the LDs <NUM> to <NUM>. The optical unit <NUM> is arranged to guide each light beam from the LD bar <NUM>. The diffraction element <NUM> is arranged to diffract each light beam incident from the LD bar <NUM> via the optical unit <NUM>, to couple a plurality of light beams that resonate at different wavelengths. The optical unit <NUM> is arranged so that among both end faces of the BT <NUM>, the end face on the +Z side having a small pitch Wo of the oblique lens portion <NUM> faces the diffraction element <NUM>.

According to the above beam coupling device <NUM>, when a plurality of light beams resonating at different wavelengths are diffracted and coupled by the diffraction element <NUM>, the plurality of light beams can be condensed on the diffraction element <NUM> by the optical unit <NUM>. By improving the degree of freedom in design, the device configuration of the beam coupling device <NUM> can be downsized.

In the present embodiment, the wavelength of resonance via the diffraction element <NUM> for each LD <NUM> gradually changes according to the position of each LD <NUM> in the X direction, which is the arrangement direction. For example, the resonance wavelength λ becomes longer from LD <NUM> on the +X side to LD <NUM> on the -X side. As a result, the light beam from each LD <NUM> can be coupled via the diffraction element <NUM>.

In the present embodiment, the pitch between the plurality of LDs <NUM> in the arrangement direction and the pitch Wi in which the oblique lens portions <NUM> are arranged on the end face on the -Z side closer to the light source among both end faces of the BTU <NUM> in the optical unit <NUM> are matched. This makes it possible to appropriately control the light beam from each LD <NUM>.

In the present embodiment, the laser processing machine <NUM> includes the beam coupling device <NUM> and the processing head <NUM> arranged to irradiate a workpiece with a light beam coupled by the beam coupling device <NUM>. The laser processing machine <NUM> of the present embodiment can be configured by using the beam coupling device <NUM> for wavelength beam combining, with reduced size from the improvement of the degree of freedom in design for guiding a plurality of light beams by the optical unit <NUM>.

Hereinafter, the second embodiment will be described with reference to <FIG>. In the second embodiment, an example of applying an optical unit to a beam coupling device for spatial beam combining and a laser processing machine provided with the beam coupling device will be described.

Hereinafter, the laser processing machine, the beam coupling device, and the optical unit according to the present embodiment will be described by omitting the description of the same configuration and operation as the laser processing machine <NUM>, the beam coupling device <NUM>, and the optical unit <NUM> according to the first embodiment as appropriate.

<FIG> is a diagram illustrating a configuration of a laser processing machine 1A according to the second embodiment. The laser processing machine <NUM> of the present embodiment has the configuration similar to the laser processing machine <NUM> of the first embodiment, but includes a beam coupling device 2A for spatial beam combining instead of the beam coupling device <NUM> for wavelength beam combining.

In the present embodiment, the beam coupling device 2A includes a laser light source <NUM>, a plurality of optical units 4A-<NUM> to 4A-<NUM>, and a coupling optical system <NUM>. The laser light source <NUM> includes a plurality of LD bars <NUM>-<NUM> to <NUM>-<NUM> in the present embodiment. Each of the LD bars <NUM>-<NUM> to <NUM>-<NUM> is configured similarly to the LD bar <NUM> of the first embodiment, for example. Hereinafter, the generic term for LD bars <NUM>-<NUM> to <NUM>-<NUM> may be referred to as "LD bar <NUM>", and the generic term for optical units 4A-<NUM> to 4A-<NUM> may be referred to as "optical unit 4A".

In the beam coupling device 2A, the plurality of LD bars <NUM> are juxtaposed in the Y direction orthogonal to the X direction, with the arrangement direction of each LD being set to be parallel to the X direction, for example. The number of LD bars <NUM> in the beam coupling device 2A is not particularly limited to three as the shown example, and may be two or four or more.

The beam coupling device 2A of the present embodiment is configured for spatial beam combining in which a large number of light beams emitted by each LD <NUM> of a plurality of LD bars <NUM> spatially arranged in the laser light source <NUM> are coupled. In the present embodiment, the beam coupling device 2A capable of performing beam coupling at a high density with a small beam diameter is provided.

In the beam coupling device 2A of the present embodiment, a plurality of optical units 4A are provided for the number of LD bars <NUM>, for example. One optical unit 4A guides light beams from respective LDs in one LD bar <NUM> to the coupling optical system <NUM>. The coupling optical system <NUM> is an optical system that couples the light beams from each optical unit 4A in the beam coupling device 2A.

<FIG> are diagrams illustrating a configuration of a beam coupling device 2A according to the second embodiment. <FIG> illustrates a side view of the beam coupling device 2A as viewed from the X direction. <FIG> illustrates a plan view of the beam coupling device 2A as viewed from the Y direction.

In the beam coupling device 2A of the present embodiment, as illustrated in <FIG>, each LD bar <NUM> is arranged on the -Z side of a separate optical unit 4A, for example. In the optical unit 4A of the present embodiment, the configuration of the BTU 40A is different from the configuration of the optical unit <NUM> of the first embodiment. The coupling optical system <NUM> is arranged on the +Z side of the optical unit 4A and includes an axially symmetric condenser lens <NUM> and a cylindrical lens <NUM> arranged between the condenser lens <NUM> and the optical unit 4A.

<FIG> exemplifies the five LDs 31a, 31b, 31c, 31d, and 31e in the LD bar <NUM>. In the present embodiment, the resonance wavelengths of the individual LDs 31a to 31e may be the same. The plurality of LDs 31a to 31e in the LD bar <NUM> are an example of a set of light emitters in the laser light source <NUM> of the present embodiment. Hereinafter, the generic term of LDs 31a to 31e may be referred to as "LD <NUM>".

<FIG> exemplify a beam coupling position P1 resulted from coupling the light beam by the beam coupling device 2A. The beam coupling position P1 is set to a position at which a beam diameter including the light beam emitted from each of the LDs 31a to 31e of all the LD bars <NUM>-<NUM> to <NUM>-<NUM> is minimized, for example. For example, an incident end of the optical fiber of the transmission optical system <NUM> described above is arranged at the beam coupling position P1.

<FIG> exemplifies a chief ray L1 of the light beam from the outer LD bar <NUM>-<NUM> in the Y direction, and a chief ray L2 of the light beam from the central LD bar <NUM>-<NUM>. <FIG> exemplifies a chief ray La of the light beam from the outer LD 31a in the X direction, and a chief ray Lc of the light beam from the central LD 31c. In the beam coupling device 2A of the present embodiment, the LD 31c central in the X and Y directions has a chief ray Lc parallel to the Z direction similar to the first embodiment, for example.

In the present embodiment, as illustrated in <FIG>, the chief ray L1 of the light beam emitted by the outer LD bars <NUM>-<NUM> of the plurality of LD bars <NUM> arranged in the Y direction is directed inward, in view of increasing the output of the beam coupling device 2A for spatial beam combining, for example. Such light ray control can be performed by inclining the outer optical unit 4A-<NUM> or shifting the arrangement of the SAC <NUM> inward. For example, the upper (+Y side) optical unit 4A in the drawing makes the chief ray L1 of the light beam inclined from the Z direction to the lower side (-Y side). In this case, the beam coupling position P1 in the Y direction where the chief rays L1 and L2 intersect between the LD bars <NUM> is located on the -Z side from a focal position P0 of the condenser lens <NUM>.

On the other hand, as illustrated in <FIG>, in a plurality of LDs 31a to 31e arranged in the X direction for each LD bar <NUM>, the optical unit 4A of the beam coupling device 2A of the present embodiment is configured to make the chief ray La of the light beam from the outer LD 31a directed outward. As a result, the position where the plurality of light beams intersect can be brought closer to the focal point of the condenser lens <NUM>, the beam diameter itself at the coupling of each light beam can be reduced, and the density of the light beam incident on the coupling optical system <NUM> can be increased. Further, according to the cylindrical lens <NUM> of the coupling optical system <NUM>, the beam coupling position P1 can match the beam coupling position P1 in the X direction and the Y direction.

Hereinafter, the optical unit 4A of the beam coupling device 2A according to the second embodiment will be described.

<FIG> illustrates a configuration example of the BT 50A of the optical unit 4A in the second embodiment. For example, the optical unit 4A of the present embodiment includes a BT 50A of the configuration example of <FIG>, in place of the BT <NUM> having the pitch Wo on the +Z side smaller than the pitch Wi on the -Z side in the optical unit <NUM> of the first embodiment.

<FIG> illustrates a cross-sectional view of the XZ plane in the BT 50A of <FIG>. In the BT 50A of this configuration example, a pitch Wi on the -Z side is smaller than a pitch Wo on the +Z side. In other words, the BT 50A of this configuration example is configured so that the pitch Wo between the oblique lens portions <NUM> on the end face on the +Z side is larger than the pitch Wi on the end face on the -Z side. In the BT 50A of this configuration example, the curved surface shape of the oblique lens portion <NUM> on the end face on the +Z side can be set to extend the curved surface shape on the -Z side, for example.

Further, in this configuration example, the pitch Wi on the -Z side is set according to the pitch between the LDs <NUM> in the LD bar <NUM> as in the BT <NUM> of the first embodiment, for example. The magnitude of the difference between the pitches Wi and Wo may be within the same range as that of the first embodiment. The BT 50A and BTU 40A of the present embodiment are also examples of optical units as in the first embodiment.

<FIG> illustrate the optical path in the optical unit 4A of the present embodiment, in the same manner as in <FIG>. <FIG> corresponds to the A-A cross section of <FIG>. <FIG> correspond to the B-B cross-sectional view and the C-C cross-sectional view in <FIG>, respectively. The BT 50A of the present embodiment faces the SAC <NUM> on the +Z side and faces the FAC <NUM> on the -Z side, as in the first embodiment.

According to the optical unit 4A of the present embodiment, as to the chief ray of the light beam from each LD <NUM> as illustrated in <FIG>, the chief ray La is directed more outward in the X and Y directions as the LD 31a is located more outside in the X direction, according to the pitch Wo of the oblique lens portion <NUM> on the end face on the +Z side of the BT 50A wherein the pitch Wo is larger than the pitch between LDs <NUM>. As illustrated in <FIG>, the inclination of the chief ray La in the Y direction is corrected in the SAC <NUM> in the same manner as in the first embodiment.

As described above, according to the optical unit 4A of the present embodiment, the chief ray Lc of the outer LD 31c in the X direction can be restricted to the X direction and directed outward.

<FIG> illustrates the simulation results of an example of the beam coupling device 2A of the second embodiment. In this simulation, the same numerical calculation as in the first embodiment was performed in the simulation environment of the beam coupling device 2A for spatial beam combining. In this simulation, the distance between the plurality of optical units 4A was set to <NUM>, the focal length of the SAC <NUM> was set to <NUM>, and the focal length of the condenser lens <NUM> was set to <NUM>.

In this simulation, the same numerical calculation as in the first embodiment was performed by setting that the pitch Wo on the +Z side of the BT 50A is made larger by <NUM> than the pitch Wi on the -Z side. The pitch between the pitch Wi on the -Z side of the BT 50A and the LD of the LD bar <NUM> was <NUM> as in the first embodiment.

According to the simulation result of <FIG>, "TANX" has a positive value of "<NUM>" after the exit of the SAC <NUM>, and the chief ray on the +X side is directed outward. Further, the value "<NUM>" of "TANY" at this time is sufficiently smaller than the above-mentioned "TANX". Therefore, it was checked that the outer chief ray in the X direction can be directed outward in the X direction while keeping the inclination in the Y direction slightly.

As described above, in the optical unit 4A of the present embodiment, the pitch Wi in which the oblique lens portions <NUM> are arranged on the end face on the -Z side as an example of one end face of both end faces of the BT <NUM> in the optical axis direction is smaller than the pitch Wo at which the oblique lens portion <NUM> is arranged on the end face on the +Z side as an example of the other end face.

According to the above optical unit 4A, in an example when a plurality of light beams are incident from the -Z side at the same pitch as the pitch Wi of the oblique lens portion <NUM> on the -Z side of the BT 50A, as the pitch Wo of the oblique lens portion <NUM> is larger on the +Z side, the outer chief ray La of the light beam in the X direction can be directed outward. In this way, the BT 50A of the optical unit 4A can improve the degree of freedom in design for guiding a plurality of light beams.

In the present embodiment, the beam coupling device 2A includes a laser light source <NUM> as an example of the light source, a plurality of optical units 4A, and a coupling optical system <NUM>. The laser light source <NUM> includes LDs <NUM> which is an example of a plurality of light emitters arranged in the X direction and the Y direction, for example. The plurality of optical units 4A are arranged to guide each light beam for each LD bar <NUM> as a set of LD 31a to LD 31e arranged in the X direction in the laser light source <NUM>. The coupling optical system <NUM> is arranged to couple a plurality of light beams guided to each optical unit 4A. The optical unit 4A is arranged so that among both end faces of the BT <NUM>, the end face on the +Z side having a large pitch Wo of the oblique lens portion <NUM> faces the coupling optical system <NUM>.

According to the above beam coupling device 2A, when a plurality of light beams are coupled, the beam diameter itself at the beam coupling position P1 can be reduced by making the outer chief ray L11 in the X direction directed outward by the optical unit 4A. In this way, by improving the degree of freedom in design by the optical unit 4A, it is possible to improve the beam quality in the coupling device 2A for spatial beam combining.

As described above, the first and second embodiments are described as an example of the technique 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 changes, substitutions, additions, omissions, and the like are made as appropriate. In addition, it is also possible to combine each component described in each embodiment to form a new embodiment. Thus, in the following, other embodiments will be exemplified.

In the first embodiment described above, an example of the beam coupling device <NUM> for wavelength beam combining has been described, but the configuration of the beam coupling device <NUM> is not particularly limited to this example. For example, an example in which the transmission type diffraction element <NUM> is used for the beam coupling device <NUM> has been described, but the diffraction element <NUM> is not limited to the transmission side and may be a reflection type. Further, in <FIG>, the <NUM> band is illustrated as the wavelength band in which the LD <NUM> emits light; however, the wavelength band of the LD <NUM> is not particularly limited and may be the <NUM> band, for example. According to the optical unit <NUM> of the present embodiment, even in the optical design of such various beam coupling devices <NUM> for wavelength beam combining, the light ray direction of the light beam can be controlled such that the BT <NUM> has the light-condensing function, and the degree of freedom in design can be improved.

In the second embodiment described above, an example of the beam coupling device 2A for spatial beam combining has been described, but the configuration of the beam coupling device 2A is not particularly limited to this example. For example, the beam coupling device 2A for inwardly directing the outer chief ray L1 in the Y direction has been described; however, the chief ray L1 may not be inwardly directed, and may be outwardly directed, for example. Further, an example in which the cylindrical lens <NUM> is used for the coupling optical system <NUM> has been described, but the cylindrical lens <NUM> may be omitted. According to the optical unit 4A of the present embodiment, even in the optical design of such various coupling devices 2A for spatial beam combining, the degree of freedom in design can be improved.

In the above embodiments, an example of applying the optical units <NUM> and 4A to beam coupling devices <NUM> and 2A for wavelength beam combining and spatial beam combining has been described. The optical unit of the present embodiment is not limited to the e coupling device for wavelength beam combining or spatial beam combining, and may be applied to various beam coupling devices. The optical unit of the present embodiment can also be applied to a beam coupling device in which wavelength beam combining and spatial beam combining are appropriately used.

As described above, the embodiments are described as the exemplification of the technique in the present disclosure. To that end, the accompanying drawings and the detailed description are provided.

Therefore, among the components described in the accompanying drawings and the detailed description, not only the component essential for solving the problem, but also the component not essential for solving the problem may be included in order to exemplify the above technique. Therefore, it should not be certified that these non-essential components are essential immediately because these non-essential components are described in the accompanying drawings and the detailed description.

In addition, since the above embodiment is for illustrating the technique in the present disclosure, various changes, substitutions, additions, omissions, and the like can be made within the scope of the claims.

Claim 1:
An optical unit (<NUM>, <NUM>, 50A) for guiding a plurality of light beams,
comprising two opposing end faces through which the plurality of light beams are transmitted, each of the two end faces comprising a plurality of lens portions (<NUM>), wherein a pitch (Wo, Wi) is defined as a distance between an optical axis of respective adjacent lens portions (<NUM>), wherein
the plurality of lens portions (<NUM>) are arranged in an arrangement direction (X) that intersects an optical axis direction (Z) along which the light beams are transmitted, characterized in that
each of the lens portions (<NUM>) is inclined with respect to both a thickness direction (Y) intersecting the optical axis direction (Z) and the arrangement direction (X), and in that
the optical unit (<NUM>) has both end faces in the optical axis direction (Z) with the pitch (Wo, Wi) at which the lens portions (<NUM>) are arranged in one end face being smaller than the pitch (Wi, Wo) at which the lens portions are arranged in another end face.