Laser device

Abstract

To provide a laser device that can suppress deterioration of a laser source caused by a return beam and can make manufacturing easier.SOLUTION: A laser device 1 comprises: a laser module which emits a plurality of laser beams La, Lb, Lc, Ld; a condenser lens 3 which condenses the plurality of laser beams La, Lb, Lc, Ld; and an optical fiber which propagates the plurality of laser beams La, Lb, Lc, Ld. In the caser where the laser device is seen from an X-axis direction, out of the plurality of laser beams La, Lb, Lc, Ld arrayed in a Z-axis direction, the positions of the laser beams La, Lb positioned on one side in the Z-axis direction for a second reference line 3c and the positions of the laser beams Lc, Ld positioned on the other side in Z-axis direction for the second reference line 3c are asymmetrical with regard to the second reference line 3c. The focal length of a fast axis collimator lens is larger than the minimum value of gaps G1, G2, G3 between the plurality of laser beams La, Lb, Lc, Ld.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] The present invention relates to a laser device. [Background technology]

[0002] A laser device including a laser light source that emits a plurality of laser beams and an optical fiber is known (see, for example, Patent Document 1). In such a laser device, the plurality of laser beams emitted from the laser light source are focused by a focusing lens and then enter the optical fiber. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-114657 Summary of the Invention [Problem to be solved by the invention]

[0004] In the laser device described above, so-called feedback light may occur, and if this feedback light enters the laser light source, the laser light source may be deteriorated. Furthermore, since such laser devices require precision, they may be difficult to manufacture.

[0005] An object of the present invention is to provide a laser device that can suppress deterioration of a laser light source due to returned light and can be easily manufactured. [Means for solving the problem]

[0006] The laser device of the present invention includes: [1] "a laser module that emits a plurality of laser beams aligned along a first direction toward one side of a second direction intersecting the first direction; a focusing lens that has an optical axis parallel to the second direction and focuses the plurality of laser beams; an optical fiber that has an entrance end face perpendicular to the optical axis of the focusing lens and propagates the plurality of laser beams focused by the focusing lens; and a housing that accommodates the laser module and the focusing lens, wherein the laser module has a plurality of laser units, each of the plurality of laser units including: a laser light source that emits at least one laser beam among the plurality of laser beams; a fast-axis collimating lens that is disposed in an optical path of the laser beams and that collimates the laser beam emitted from the laser light source in a fast-axis direction along the first direction; and a fast-axis collimating lens that is disposed downstream of the optical path with respect to the fast-axis collimating lens and that collimates the laser beam emitted from the laser light source in a fast-axis direction along the first direction. a slow axis collimating lens that collimates the laser beam emitted from the lens in a slow axis direction, wherein when viewed from the second direction, a plurality of intervals between the plurality of laser beams emitted from the laser module while being lined up along the first direction are non-uniform, when viewed from the second direction, a position of at least one laser beam, among the plurality of laser beams emitted from the laser module while being lined up along the first direction, extending along a third direction intersecting both the first direction and the second direction and located on one side in the first direction with respect to a reference line passing through the optical axis of the focusing lens, and positions of all laser beams located on the other side in the first direction with respect to the reference line are asymmetric with respect to the reference line, and a focal length of the fast axis collimating lens of each of the plurality of laser units is greater than the smallest value of the plurality of intervals.

[0007] In the laser device described in [1] above, when viewed from the second direction, among the multiple laser beams emitted from the laser module while aligned along the first direction, the position of at least one laser beam located on one side of the reference line in the first direction and the positions of all laser beams located on the other side of the reference line in the first direction are asymmetric with respect to the reference line. As a result, even if at least one laser beam located on one side of the reference line in the first direction is reflected by the incident end face of the optical fiber and then enters the laser light source as returned light, the position of the returned light does not coincide with the position of the light-emitting region of the laser light source, thereby suppressing deterioration of the laser light source. Furthermore, the focal length of the fast-axis collimating lens of each of the multiple laser units is greater than the smallest value among the multiple spacings between the multiple laser beams emitted from the laser module while aligned along the first direction. This allows for a larger distance between the laser light source and the incident surface of the fast-axis collimating lens, facilitating attachment of the fast-axis collimating lens to the laser light source. This facilitates manufacturing of the laser device. Therefore, this laser device suppresses deterioration of the laser light source due to returned light and facilitates manufacturing.

[0008] The laser device of the present invention may be [2] "the laser device according to the above [1], wherein, when viewed from the second direction, of the plurality of laser beams emitted from the laser module while being aligned along the first direction, the positions of all laser beams located on one side of the reference line in the first direction and the positions of all laser beams located on the other side of the reference line in the first direction are asymmetric with respect to the reference line." This reliably suppresses deterioration of the laser light source due to returned light.

[0009] The laser device of the present invention may be the laser device according to [1] or [2] above, wherein [3] "the laser module further includes a support including a plurality of mounting surfaces arranged in a stepped manner such that the positions in the first direction increase with increasing distance from the focusing lens in the second direction, the laser light source of each of the plurality of laser units is disposed on each of the plurality of mounting surfaces and emits the laser light toward one side in the third direction, each of the plurality of laser units further includes a reflection mirror disposed downstream of the optical path with respect to the slow axis collimating lens and reflecting the laser light emitted from the slow axis collimating lens along the second direction toward the focusing lens, the reflection mirrors of each of the plurality of laser units being aligned along the second direction when viewed from the first direction and including a reflection surface overlapping with the laser light source when viewed from the third direction." In this way, by adjusting the position of each mounting surface in the first direction, it is possible to adjust the asymmetry between the position of at least one laser light located on one side of a reference line in the first direction and the positions of all laser light located on the other side of the reference line in the first direction.

[0010] The laser device of the present invention may be [4] "the laser device according to any one of the above [1] to [3], further comprising a wavelength filter disposed between the plurality of laser units and the optical fiber, the wavelength filter transmitting the plurality of laser beams emitted from the plurality of laser units and reflecting the light emitted from the optical fiber." This prevents light entering the interior of the housing from the outside via the optical fiber from entering each laser unit.

[0011] The laser device of the present invention may be [5] "the laser device according to any one of the above [1] to [4], wherein the focal length of the fast axis collimating lens is 100 μm to 400 μm." This makes it easy to attach the fast axis collimating lens to the laser light source, as described above, and therefore makes it easy to manufacture the laser device.

[0012] The laser device of the present invention may be [6] "the laser device according to any one of the above [1] to [5], wherein each of the plurality of intervals is 100 μm to 500 μm." This makes it easy to attach the fast axis collimating lens to the laser light source, as described above, and therefore makes it easy to manufacture the laser device.

[0013] The laser device of the present invention may be [7] "the laser device according to any one of the above [1] to [5], wherein the difference between each of the plurality of intervals is 700 μm or less." This makes it possible to realize the asymmetric state described above.

[0014] The laser device of the present invention may be [8] "the laser device according to any one of [1] to [7] above, wherein, when viewed from the second direction, a difference between a distance from an n-th laser beam (n is a natural number) of the plurality of laser beams that is located on one side of the reference line in the first direction and counting from the reference line to the reference line and a distance from an n-th laser beam of the plurality of laser beams that is located on the other side of the reference line in the first direction and counting from the reference line to the reference line is 10 μm to 500 μm." This prevents the n-th laser beam that is located on one side of the reference line in the first direction from being reflected by an incident end surface of an optical fiber and then being incident as a return beam into an emission region of a laser light source that emits the n-th laser beam that is located on the other side of the reference line in the first direction. Similarly, the n-th laser beam that is located on the other side of the reference line in the first direction from being reflected by an incident end surface of an optical fiber and then being incident as a return beam into an emission region of a laser light source that emits the n-th laser beam that is located on one side of the reference line in the first direction. Therefore, deterioration of the laser light source due to the returned light is suppressed.

[0015] The laser device of the present invention may be [9] "the laser device according to any one of the above [1] to [8], wherein the laser light source of each of the plurality of laser units has one laser diode bar, and the one laser diode bar includes multiple light-emitting regions." This makes it possible to suppress deterioration of the laser light source while maintaining the optical output of the laser light source.

[0016] The laser device of the present invention may be

[10] "the laser device according to any one of the above [1] to [8], wherein the laser light source of each of the plurality of laser units has a plurality of semiconductor laser elements, and each of the plurality of semiconductor laser elements includes one light-emitting region." This makes it possible to suppress deterioration of the laser light source while maintaining the optical output of the laser light source. [Effects of the Invention]

[0017] According to the present invention, it is possible to provide a laser device that can suppress deterioration of a laser light source due to returned light and can be easily manufactured. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a plan view of a laser device according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 2 is a plan view of the support shown in FIG. 1. [Figure 4] FIG. 2 is a front view of the support shown in FIG. 1. [Figure 5] FIG. 2 is a partially enlarged view of FIG. [Figure 6] FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5. [Figure 7] FIG. 6 is a front view of the laser light source shown in FIG. 5. [Figure 8] FIG. 6 is a side view of the laser light source and fast-axis collimating lens shown in FIG. 5. [Figure 9]FIG. 6 is a plan view of the slow-axis collimating lens and reflecting mirror shown in FIG. 5. [Figure 10] FIG. 2 is a front view of the laser module shown in FIG. [Figure 11] FIG. 2 is a side view of the laser module shown in FIG. [Figure 12] FIG. 3 is a front view of the condenser lens as seen from the imaginary plane shown in FIG. 2. [Figure 13] FIG. 3 is a front view of the condenser lens as seen from the imaginary plane shown in FIG. 2. [Figure 14] FIG. 2 is a schematic diagram showing a plurality of laser beams and a plurality of return beams. [Figure 15] FIG. 2 is a schematic diagram showing the positional relationship between a plurality of light-emitting regions and a plurality of return lights. [Figure 16] FIG. 10 is a front view of a laser light source according to a second embodiment. [Figure 17] FIG. 10 is a plan view of a laser unit according to a second embodiment. [Figure 18] 10A and 10B are schematic diagrams illustrating adjustment of the arrangement direction of a plurality of laser beams according to the second embodiment. [Figure 19] FIG. 10 is a front view of a laser light source according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals, and duplicated explanations will be omitted.

[0020] [First embodiment] [Laser device configuration] 1, the laser device 1 of the first embodiment includes a laser module 2, a condenser lens 3, a fiber member 4, a wavelength filter 5, a housing 6, and an electrode 7. The laser device 1 is used, for example, to excite a fiber laser. The laser module 2, the condenser lens 3, and the wavelength filter 5 are housed in the housing 6.

[0021] The laser module 2 emits a plurality of laser beams. The condenser lens 3 is disposed downstream of the optical paths of the plurality of laser beams relative to the laser module 2. The condenser lens 3 is spaced apart from the laser module 2. The condenser lens 3 has an optical axis 3a parallel to the X-axis direction. The condenser lens 3 condenses the plurality of laser beams emitted from the laser module 2. The diameter of the condenser lens 3 is, for example, approximately 5 mm. That is, the width of the condenser lens 3 in the Z-axis direction is, for example, approximately 5 mm. The condenser lens 3 is made of, for example, glass. The refractive index of the condenser lens 3 is, for example, 1.6 to 2.0. In this embodiment, the refractive index of the condenser lens 3 is, for example, approximately 1.8. The condenser lens 3 is, for example, a plano-convex lens (product number: N-LASF44) manufactured by Edmund Optics, Inc.

[0022] The fiber member 4 is disposed downstream of the optical paths of the plurality of laser beams with respect to the condenser lens 3. The fiber member 4 has an optical fiber 46. The optical fiber 46 propagates the plurality of laser beams condensed by the condenser lens 3.

[0023] The wavelength filter 5 is disposed in the optical path between the laser module 2 and the optical fiber 46. In this embodiment, the wavelength filter 5 is disposed in the optical path between the laser module 2 and the condenser lens 3. That is, the wavelength filter 5 is separated from both the laser module 2 and the condenser lens 3. The wavelength filter 5 transmits (passes) a plurality of laser beams (excitation beams) emitted from the laser module 2. The wavelength filter 5 reflects oscillation beams having wavelengths different from the excitation beams. The wavelength filter 5 reflects light that enters the inside of the housing 6 from the outside via the optical fiber 46 into the inside of the housing 6 (light emitted from the optical fiber 46 and having a wavelength different from the laser beams emitted from the laser module 2). The wavelength filter 5 is, for example, a dichroic mirror.

[0024] The electrodes 7 are fixed to the housing 6. The laser module 2 is driven by a voltage supplied via the electrodes 7.

[0025] 1 and 2, the housing 6 has a bottom wall 61, side walls 62, a connecting member 63, and a support member 64. The bottom wall 61 is, for example, plate-shaped. The side walls 62 are fixed to the main surface of the bottom wall 61. The laser module 2, the condenser lens 3, and the wavelength filter 5 are each fixed to the main surface of the bottom wall 61 while being disposed inside the side walls 62. The condenser lens 3 and the wavelength filter 5 are each fixed to the bottom wall 61 by, for example, an adhesive resin.

[0026] The side wall 62 includes an inner wall surface 62a, an outer wall surface 62b, and a through hole 62c. The through hole 62c penetrates the side wall 62. The through hole 62c has an axis that is parallel to, for example, the X-axis direction. The connecting member 63 has, for example, a cylindrical shape. A tip 63a of the connecting member 63 is fixed to the outer wall surface 62b of the side wall 62 with the axis of the connecting member 63 coinciding with the axis of the through hole 62c.

[0027] The support member 64 has, for example, a plate shape. The support member 64 is fixed to an inner wall surface 62a of the side wall 62. When viewed from the X-axis direction, the support member 64 partially overlaps with the through-hole 62c of the side wall 62. The support member 64 includes a support surface 64a. The support surface 64a is, for example, a flat surface that intersects with the Z-axis direction. The position of the support surface 64a in the Z-axis direction substantially coincides with the position of the axis of the connection member 63 in the Z-axis direction. The material of the housing 6 is, for example, copper or copper tungsten.

[0028] The fiber member 4 is connected to the housing 6. Specifically, the fiber member 4 has a ferrule 45 that holds an optical fiber 46. The ferrule 45 has, for example, a cylindrical shape. The ferrule 45 is inserted into the connecting member 63 from the rear end 63b of the connecting member 63. The optical fiber 46 is inserted into an insertion hole of the ferrule 45. The tip of the optical fiber 46 is placed on a support surface 64a of a support member 64 inside the side wall 62. The tip of the optical fiber 46 is fixed to the support surface 64a with, for example, a UV-curable resin. The optical fiber 46 has an incident end surface 46a that is perpendicular to the optical axis 3a of the focusing lens 3. The multiple laser beams focused by the focusing lens 3 are incident on the incident end surface 46a.

[0029] [Laser module configuration] As shown in FIG. 1, the laser module 2 includes a support 30 and multiple laser units 40A, 40B, 40C, and 40D. As shown in FIGS. 3 and 4, the support 30 has, for example, a rectangular shape when viewed from the Z-axis direction (thickness direction of the support 30). The support 30 includes a bottom surface 31 and a main surface 32. The bottom surface 31 is a flat surface parallel to the XY plane. The main surface 32 faces the opposite side to the bottom surface 31. The main surface 32 has a stepped shape. Specifically, the main surface 32 includes a first region 33 and a second region 34. The first region 33 and the second region 34 are aligned along the Y-axis direction when viewed from the Z-axis direction. Each of the first region 33 and the second region 34 has, for example, a rectangular shape.

[0030] The first region 33 includes a base surface 33e, a first mounting surface 33a, a second mounting surface 33b, a third mounting surface 33c, and a fourth mounting surface 33d. The base surface 33e is a flat surface parallel to the XY plane. The base surface 33e has, for example, a rectangular shape. The first mounting surface 33a, the second mounting surface 33b, the third mounting surface 33c, and the fourth mounting surface 33d are located on the opposite side of the base surface 33e from the second region 34 when viewed from the Z-axis direction. Each of the first mounting surface 33a, the second mounting surface 33b, the third mounting surface 33c, and the fourth mounting surface 33d is a flat surface parallel to the XY plane. Each of the first mounting surface 33a, the second mounting surface 33b, the third mounting surface 33c, and the fourth mounting surface 33d has, for example, a rectangular shape.

[0031] The first mounting surface 33a, the second mounting surface 33b, the third mounting surface 33c, and the fourth mounting surface 33d are aligned along the X-axis direction when viewed from the Z-axis direction. The positions of the first mounting surface 33a, the second mounting surface 33b, the third mounting surface 33c, and the fourth mounting surface 33d in the Z-axis direction are different from one another. The first mounting surface 33a, the second mounting surface 33b, the third mounting surface 33c, and the fourth mounting surface 33d are aligned in a stepped manner from one side of the support 30 to the other in the X-axis direction. The first mounting surface 33a, the second mounting surface 33b, the third mounting surface 33c, and the fourth mounting surface 33d are aligned in a stepped manner so that their positions in the Z-axis direction increase as they move away from the focusing lens 3 (see FIG. 1 ) in the X-axis direction (toward the opposite side of the fiber member 4 from the focusing lens 3). Specifically, the position of the first mounting surface 33a in the Z-axis direction coincides with the position of the base surface 33e in the Z-axis direction. In other words, the first mounting surface 33a is located on the same plane as the base surface 33e. The second mounting surface 33b is located on the opposite side of the bottom surface 31 from the first mounting surface 33a. The third mounting surface 33c is located on the opposite side of the bottom surface 31 from the second mounting surface 33b. The fourth mounting surface 33d is located on the opposite side of the bottom surface 31 from the third mounting surface 33c.

[0032] The height difference H2 between the second mounting surface 33b and the third mounting surface 33c in the Z-axis direction is different from the height difference H1 between the first mounting surface 33a and the second mounting surface 33b in the Z-axis direction and the height difference H3 between the third mounting surface 33c and the fourth mounting surface 33d in the Z-axis direction. In this embodiment, the height difference H2 is smaller than both the height difference H1 and the height difference H3. In this embodiment, the height difference H1 and the height difference H3 are the same.

[0033] The second region 34 is a flat surface parallel to the XY plane. The second region 34 is recessed more than the first region 33. That is, the second region 34 is located closer to the bottom surface 31 than the first region 33. The second region 34 is located between the base surface 33e and the bottom surface 31 in the Z-axis direction. The distance between the bottom surface 31 and the base surface 33e is greater than the distance between the bottom surface 31 and the second region 34. That is, the thickness of the portion of the support body 30 including the first region 33 is greater than the thickness of the portion of the support body 30 including the second region 34.

[0034] A fixing hole 33f is formed in the base surface 33e. The fixing hole 33f penetrates, for example, the support body 30. When viewed from the Z-axis direction, the fixing hole 33f has, for example, a circular shape. A jig (for example, a spacer) or the like used to position the laser light sources 41A, 41B, 41C, and 41D (see FIG. 10) on the support body 30 is attached to the fixing hole 33f. The material of the support body 30 is, for example, copper (Cu) or copper tungsten (CuW). The support body 30 is fixed to the bottom wall 61 of the housing 6 by, for example, a solder material or the like.

[0035] The support body 30 supports a plurality of laser units 40A, 40B, 40C, and 40D. The plurality of laser units 40A, 40B, 40C, and 40D are fixed to the support body 30. Specifically, as shown in FIGS. 5 and 6, the laser unit 40A is disposed on the main surface 32 of the support body 30. The laser unit 40A has a laser light source 41A, a fast-axis collimating lens 42A, a slow-axis collimating lens 44A, and a reflecting mirror 50A. When viewed from the Z-axis direction, the laser light source 41A, the fast-axis collimating lens 42A, the slow-axis collimating lens 44A, and the reflecting mirror 50A are aligned in order along the Y-axis direction.

[0036] The laser light source 41A is disposed on the first mounting surface 33a of the support 30. The laser light source 41A is fixed to the support 30. Specifically, the laser light source 41A has one submount 411 and one semiconductor laser element 412. The submount 411 is disposed on the first mounting surface 33a. The submount 411 has a substrate made of, for example, aluminum nitride (AIN) and a metal film (e.g., Cu or Ni / Au) metallized on the surface of the substrate. The metal film functions, for example, for soldering or conduction. The submount 411 is fixed to the first mounting surface 33a with, for example, a solder material. The semiconductor laser element 412 is disposed on the opposite side of the submount 411 from the first mounting surface 33a. The semiconductor laser element 412 is fixed to the submount 411 with, for example, a solder material. In this embodiment, the semiconductor laser element 412 emits one laser beam La.

[0037] The fast-axis collimating lens 42A is disposed in the optical path of the laser beam La. The fast-axis collimating lens 42A is disposed on the base surface 33e of the support 30. In this embodiment, the fast-axis collimating lens 42A is fixed to the submount 411 by fixing members 49A. The fixing members 49A are provided between the fast-axis collimating lens 42A and the submount 411, at both ends of the fast-axis collimating lens 42A in the X-axis direction. When viewed from the Z-axis direction, the fixing members 49A are located on both sides of the semiconductor laser element 412 in the X-axis direction. There is an air gap between the fast-axis collimating lens 42A and the laser light source 41A. The fixing members 49A are, for example, UV-curable resin. The fast-axis collimating lens 42A collimates the laser beam La emitted from the laser light source 41A in the fast-axis direction along the Z-axis direction (first direction).

[0038] The slow-axis collimating lens 44A is disposed downstream of the optical path of the laser light La with respect to the fast-axis collimating lens 42A. The slow-axis collimating lens 44A is disposed on the second region 34 of the support body 30. The slow-axis collimating lens 44A is fixed to the support body 30. The slow-axis collimating lens 44A is fixed to the second region 34 by, for example, an adhesive resin 440. The adhesive resin 440 is located closer to the bottom surface 31 than the first region 33. The slow-axis collimating lens 44A collimates the laser light La emitted from the fast-axis collimating lens 42A in the slow-axis direction along the X-axis direction (a second direction intersecting the first direction).

[0039] The reflecting mirror 50A is disposed downstream of the optical path of the laser beam La relative to the slow axis collimating lens 44A. The reflecting mirror 50A is disposed in the optical path between the slow axis collimating lens 44A and the condenser lens 3 (see FIG. 1). The reflecting mirror 50A is disposed on the second region 34. The reflecting mirror 50A is fixed to the support body 30. The reflecting mirror 50A is fixed to the second region 34 by, for example, an adhesive resin 500. The adhesive resin 500 is located closer to the bottom surface 31 than the first region 33.

[0040] As shown in FIGS. 7 and 8, the semiconductor laser element 412 includes a light emitting surface 41b. The light emitting surface 41b is, for example, a flat surface parallel to the XZ plane. The light emitting surface 41b is, for example, located on the same plane as the tip surface 41c of the submount 411. The light emitting surface 41b includes one light emitting region 41a. The laser light La is emitted from the light emitting region 41a. The semiconductor laser element 412 emits the laser light La to one side (the fast-axis collimating lens 42A side) in the Y-axis direction (a third direction intersecting both the first and second directions). The laser light La is, for example, diverging light. The laser light La travels along the Y-axis while diverging conically as it moves away from the laser light source 41A. The Z-axis direction of the laser light La is the fast-axis direction, and the X-axis direction is the slow-axis direction.

[0041] The fast-axis collimating lens 42A is configured, for example, by a single cylindrical lens whose collimation direction is the Z-axis direction. The fast-axis collimating lens 42A extends along the X-axis direction. The fast-axis collimating lens 42A is formed, for example, from high-refractive-index glass. The refractive index of the fast-axis collimating lens 42A is, for example, 1.6 to 2.0. In this embodiment, for example, an FAC lens (J10919 series) manufactured by Hamamatsu Photonics K.K. is used as the fast-axis collimating lens 42A.

[0042] The fast-axis collimating lens 42A includes an incident surface 421 facing the light-emitting region 41a of the laser light source 41A and an exit surface 422 facing the opposite side to the incident surface 421. The incident surface 421 is, for example, a flat surface parallel to the XZ plane. The exit surface 422 is a convex surface protruding on the side opposite to the incident surface 421. The exit surface 422 is a part of a cylindrical surface having an axis parallel to the X-axis direction. The laser light La that enters the incident surface 421 while diffusing in a conical shape is collimated (parallelized) in the Z-axis direction by the fast-axis collimating lens 42A and then exits from the exit surface 422 as light parallel to, for example, the XY plane. The focal point of the fast-axis collimating lens 42A is located on the light exit surface 41b of the semiconductor laser element 412. The focal length Fd of the fast-axis collimating lens 42A is, for example, 100 μm to 400 μm.

[0043] 9, the slow axis collimating lens 44A is configured, for example, by a single cylindrical lens whose collimation direction is the X-axis direction. The slow axis collimating lens 44A extends along the Z-axis direction. The slow axis collimating lens 44A is formed, for example, from high refractive index glass. The refractive index of the slow axis collimating lens 44A is, for example, 1.6 to 2.0. In this embodiment, for example, FISBA's SAC5600 (product number: K-PBK40) is used as the slow axis collimating lens 44A.

[0044] Slow-axis collimating lens 44A includes incident surface 441 facing laser light source 41A and exit surface 442 facing the opposite side to incident surface 441. Incident surface 441 is, for example, a flat surface parallel to the XZ plane. Exit surface 442 is a convex surface protruding on the side opposite to incident surface 441. Exit surface 442 is part of a cylindrical surface having an axis parallel to the Z-axis direction. Laser light La incident on incident surface 441 is collimated (parallelized) in the X-axis direction by slow-axis collimating lens 44A, and then emitted from exit surface 442 as parallel light (collimated light) parallel to, for example, the Y-axis direction. The focal length of slow-axis collimating lens 44A is, for example, approximately 5.6 mm.

[0045] The reflecting mirror 50A reflects the laser light La emitted from the slow-axis collimating lens 44A toward the collecting lens 3 (see FIG. 1) along the X-axis direction. The reflecting mirror 50A includes a reflecting surface 51 that faces the slow-axis collimating lens 44A at an angle. The reflecting surface 51 is parallel to the Z-axis direction and obliquely intersects with both the X-axis and Y-axis directions. When viewed from the Z-axis direction, the reflecting surface 51 is inclined along the Y-axis direction so that the further away from the slow-axis collimating lens 44A it is, the closer it is to the collecting lens 3. When viewed from the Y-axis direction, the reflecting surface 51 overlaps with the laser light source 41A.

[0046] In this embodiment, "along the direction" includes a state in which the laser beam La is parallel to the direction and a state in which the laser beam La intersects with the direction at a predetermined angle. The predetermined angle is, for example, 0 to 30 degrees. In this embodiment, the reflecting mirror 50A may reflect the laser beam La emitted from the slow axis collimating lens 44A so that the laser beam La travels along an optical path parallel to the X-axis direction, or may reflect the laser beam La so that the laser beam La emitted from the slow axis collimating lens 44A travels along an optical path that intersects with the X-axis direction at the above-mentioned predetermined angle.

[0047] As shown in FIG. 10 , multiple laser units 40A, 40B, 40C, and 40D are aligned along the X-axis direction. Like the laser unit 40A, the laser unit 40B includes a laser light source 41B, a fast-axis collimating lens 42B, a slow-axis collimating lens 44B, and a reflecting mirror 50B. The laser unit 40B differs from the laser unit 40A in that the laser light source 41B is disposed on the second mounting surface 33b. Like the laser unit 40A, the laser unit 40C includes a laser light source 41C, a fast-axis collimating lens 42C, a slow-axis collimating lens 44C, and a reflecting mirror 50C. The laser unit 40C differs from the laser unit 40A in that the laser light source 41C is disposed on the third mounting surface 33c. Similar to the laser unit 40A, the laser unit 40D includes a laser light source 41D, a fast axis collimating lens 42D, a slow axis collimating lens 44D, and a reflecting mirror 50D. The laser unit 40D differs from the laser unit 40A in that the laser light source 41D is disposed on the fourth mounting surface 33d.

[0048] The configuration of each of the laser light sources 41B, 41C, and 41D is the same as the configuration of the laser light source 41A. The configuration of each of the fast-axis collimating lenses 42B, 42C, and 42D is the same as the configuration of the fast-axis collimating lens 42A. The configuration of each of the slow-axis collimating lenses 44B, 44C, and 44D is the same as the configuration of the slow-axis collimating lens 44A.

[0049] The multiple reflecting mirrors 50A, 50B, 50C, and 50D are aligned along the X-axis direction when viewed from the Z-axis direction. This configuration prevents the laser device 1 from becoming larger. The height (length in the Z-axis direction) of the reflecting mirror 50B is greater than the height of the reflecting mirror 50A. An end 50b of the reflecting mirror 50B opposite the support 30 is located on the opposite side from the support 30 of an end 50a of the reflecting mirror 50A opposite the support 30. The difference in height between the reflecting mirror 50B and the reflecting mirror 50A is approximately the same as the difference in height between the second mounting surface 33b and the first mounting surface 33a. The height of the reflecting mirror 50C is greater than the height of the reflecting mirror 50B. An end 50c of the reflecting mirror 50C opposite the support 30 is located on the opposite side from the support 30 of an end 50b of the reflecting mirror 50B opposite the support 30. The difference in height between the reflecting mirror 50C and the reflecting mirror 50B is approximately the same as the difference in height between the third mounting surface 33c and the second mounting surface 33b. The height of the reflecting mirror 50D is greater than the height of the reflecting mirror 50C. One end 50d of the reflecting mirror 50D opposite the support 30 is located on the opposite side from the support 30 than one end 50c of the reflecting mirror 50C opposite the support 30. The difference in height between the reflecting mirror 50D and the reflecting mirror 50C is approximately the same as the difference in height between the fourth mounting surface 33d and the third mounting surface 33c. The configuration of each of the reflecting mirrors 50B, 50C, and 50D is the same as the configuration of the reflecting mirror 50A except for the height.

[0050] As shown in FIG. 11, laser light La is emitted from slow axis collimating lens 44A and then reflected by reflecting mirror 50A. Like laser light La, laser light Lb is emitted from slow axis collimating lens 44B and then reflected by reflecting mirror 50B. Laser light Lb is reflected at a position on the opposite side of reflecting mirror 50A from support 30. In other words, laser light Lb does not pass through reflecting mirror 50A. Like laser light La, laser light Lc is emitted from slow axis collimating lens 44C and then reflected by reflecting mirror 50C. Laser light Lc is reflected at a position on the opposite side of reflecting mirror 50B from support 30. In other words, laser light Lc does not pass through reflecting mirror 50B and reflecting mirror 50A. Like laser light La, laser light Ld is emitted from slow axis collimating lens 44D and then reflected by reflecting mirror 50D. The laser light Ld is reflected at a position on the opposite side of the support 30 with respect to the reflecting mirror 50C. In other words, the laser light Ld does not pass through the reflecting mirror 50C, the reflecting mirror 50B, and the reflecting mirror 50A. As described above, the laser module 2 emits a plurality of laser beams La, Lb, Lc, and Ld aligned along the Z-axis direction (first direction) to one side (the collecting lens 3 side) in the X-axis direction (second direction). The laser beams La, Lb, Lc, and Ld are incident on the collecting lens 3 (see FIG. 1) aligned along the Z-axis direction.

[0051] The condenser lens 3 condenses the laser light La, the laser light Lb, the laser light Lc, and the laser light Ld, and then couples the condensed laser light to the optical fiber 46 of the fiber member 4 (see FIG. 1).

[0052] [Laser beam position] Fig. 12 is a front view of the collecting lens 3 as viewed from the imaginary plane S shown in Fig. 2. The imaginary plane S is a plane perpendicular to the optical axis 3a of the collecting lens 3. As shown in Fig. 12, the collecting lens 3 has a first reference line 3b that extends along the Z-axis direction and passes through the optical axis 3a, and a second reference line 3c that extends along the Y-axis direction and passes through the optical axis 3a. In this embodiment, the first reference line 3b is parallel to the Z-axis direction, and the second reference line 3c is parallel to the Y-axis direction.

[0053] The center Lac of laser beam La, the center Lbc of laser beam Lb, the center Lcc of laser beam Lc, and the center Ldc of laser beam Ld are each located on the first reference line 3b. Laser beam La, laser beam Lb, laser beam Lc, and laser beam Ld are lined up in order from one side in the Z-axis direction (the lower side in FIG. 12) to the other side in the Z-axis direction (the upper side in FIG. 12). Laser beam La and laser beam Lb are located on one side of the second reference line 3c, and laser beam Lc and laser beam Ld are located on the other side of the second reference line 3c. The distance between adjacent centers Lac, Lbc, Lcc, and Ldc is, for example, approximately 0.4 mm.

[0054] The cross-sectional shape of the laser beam La in the YZ plane (plane perpendicular to the optical axis 3a) will be described. The outer edge of the laser beam La has, for example, an elliptical shape. The outer edge of the laser beam La has a minor axis parallel to the first reference line 3b and a major axis parallel to the second reference line 3c. The intensity distribution of the laser beam La follows, for example, a normal distribution (Gaussian distribution). Specifically, the intensity of the laser beam La gradually decreases in a normal distribution manner as it moves away from the center Lac. The intensity at the outer edge of the laser beam La is 1 / e of the intensity at the center Lac of the laser beam La. 2 In other words, in this embodiment, the intensity at the outer edge of the laser beam La is 1 / e times the intensity at the center Lac. 2 The laser beam La is formed by an ellipse that is twice as wide as the laser beam La. The width of the laser beam La in the Z-axis direction is, for example, about 0.3 mm. The width of the laser beam La in the Z-axis direction is, for example, the length of a line segment connecting two intersections between the first reference line 3b and the outer edge of the laser beam La. The cross-sectional shapes of the laser beams Lb, Lc, and Ld in the YZ plane are the same as the cross-sectional shape of the laser beam La.

[0055] When viewed from the X-axis direction, among the multiple laser beams La, Lb, Lc, and Ld that are aligned along the Z-axis direction and emitted from the laser module 2, the position of at least one laser beam that is located on one side of the second reference line 3c in the Z-axis direction and the positions of all laser beams that are located on the other side of the second reference line 3c in the Z-axis direction are asymmetric with respect to the second reference line 3c. In this embodiment, when viewed from the X-axis direction, among the multiple laser beams La, Lb, Lc, and Ld that are aligned along the Z-axis direction and emitted from the laser module 2, the positions of all laser beams that are located on one side of the second reference line 3c in the Z-axis direction and the positions of all laser beams that are located on the other side of the second reference line 3c in the Z-axis direction are asymmetric with respect to the second reference line 3c.

[0056] When viewed from the X-axis direction, the distance from the nth (n is a natural number) laser light among the multiple laser lights La, Lb, Lc, and Ld that is located on one side of the second reference line 3c in the Z-axis direction and counting from the second reference line 3c to the second reference line 3c is different from the distance from the nth laser light among the multiple laser lights La, Lb, Lc, and Ld that is located on the other side of the second reference line 3c in the Z-axis direction and counting from the second reference line 3c to the second reference line 3c.

[0057] In this embodiment, the positions of the laser beams La and Ld are asymmetric with respect to the second reference line 3c. A first distance R1 from the center Lac of the laser beam La (the second laser beam counting from the second reference line 3c) to the second reference line 3c is different from a fourth distance R4 from the center Ldc of the laser beam Ld (the second laser beam counting from the second reference line 3c). The first distance R1 is, for example, shorter than the fourth distance R4. The difference between the first distance R1 and the fourth distance R4 is, for example, 10 μm to 500 μm.

[0058] In this embodiment, the positions of the laser beams Lb and Lc are asymmetric with respect to the second reference line 3c. A second distance R2 from the center Lbc of the laser beam Lb (the first laser beam counting from the second reference line 3c) to the second reference line 3c is different from a third distance R3 from the center Lcc of the laser beam Lc (the first laser beam counting from the second reference line 3c) to the second reference line 3c. The second distance R2 is, for example, shorter than the third distance R3. The difference between the second distance R2 and the third distance R3 is, for example, 10 μm to 500 μm.

[0059] In this embodiment, the positions of the laser beams La and Lc are asymmetric with respect to the second reference line 3c. The first distance R1 and the third distance R3 are different from each other. The first distance R1 is, for example, greater than the third distance R3.

[0060] In this embodiment, the positions of the laser beams Lb and Ld are asymmetric with respect to the second reference line 3c. The second distance R2 and the fourth distance R4 are different from each other. The second distance R2 is, for example, shorter than the fourth distance R4.

[0061] When viewed from the X-axis direction, the laser light La, the laser light Lb, the laser light Lc, and the laser light Ld are arranged at unequal intervals along the Z-axis direction. When viewed from the X-axis direction, the multiple intervals between the multiple laser lights La, Lb, Lc, and Ld are non-uniform. The "interval" between the laser lights refers to the shortest distance between adjacent laser lights. The "interval" between the laser lights is, for example, the length of the area between the outer edge of one laser light and the outer edge of the other laser light among the line segments connecting the centers of adjacent laser lights.

[0062] The phrase "non-uniform" for multiple intervals means that at least two of the multiple intervals are different from each other. The first interval G1 between laser light La and laser light Lb in the Z-axis direction, the second interval G2 between laser light Lb and laser light Lc in the Z-axis direction, and the third interval G3 between laser light Lc and laser light Ld in the Z-axis direction are non-uniform. In this embodiment, the first interval G1 is larger than the second interval G2. In this embodiment, the second interval G2 is smaller than the third interval G3. In this embodiment, the first interval G1 and the third interval G3 are the same.

[0063] The focal length Fd of the fast-axis collimating lens 42A is greater than the smallest value among the first interval G1, the second interval G2, and the third interval G3. The focal length Fd of the fast-axis collimating lens 42A is greater than the second interval G2. In this embodiment, the focal length Fd of the fast-axis collimating lens 42A is greater than each of the first interval G1, the second interval G2, and the third interval G3. Each of the first interval G1, the second interval G2, and the third interval G3 is, for example, 100 μm to 500 μm. Each difference between the first interval G1, the second interval G2, and the third interval G3 is, for example, 700 μm or less. Specifically, each of the difference between the first interval G1 and the second interval G2 and the difference between the third interval G3 and the second interval G2 is, for example, 700 μm or less.

[0064] The phrase "the positions of two laser beams are asymmetric with respect to each other" refers to a case where, in a cross section perpendicular to the optical axis of the focusing lens, when one laser beam is rotated 180 degrees around the optical axis of the focusing lens, there is a region of one laser beam that does not overlap with the other laser beam. As a first example, in this embodiment, as shown in FIG. 13, the virtual laser beam Lbs formed by rotating the laser beam Lb 180 degrees around the optical axis 3a is separated from the laser beam Lc, so that there is a region of the virtual laser beam Lbs that does not overlap with the laser beam Lc. In such a case, the positions of the laser beam Lb and the laser beam Lc can be said to be asymmetric with respect to the second reference line 3c. As a second example, for example, in FIG. 13, even when a portion of the virtual laser beam Lbs overlaps with the laser beam Lc, there is also a region of the virtual laser beam Lbs that does not overlap with the laser beam Lc. In such a case, the positions of the laser beam Lb and the laser beam Lc can be said to be asymmetric with respect to the second reference line 3c.

[0065] "The positions of two laser beams are asymmetric with respect to each other" refers to a case where, in a cross section perpendicular to the optical axis of the focusing lens, the distance from the center of one laser beam to the reference line is different from the distance from the center of the other laser beam to the reference line. As a third example, in this embodiment, as shown in Fig. 12, the second distance R2 from the center Lbc of laser beam Lb to the second reference line 3c and the third distance R3 from the center Lcc of laser beam Lc to the second reference line 3c are different from each other, so that it can be said that the positions of laser beam Lb and laser beam Lc are asymmetric with respect to the second reference line 3c.

[0066] As shown in Figure 14, each laser light La, Lb, Lc, Ld may be reflected by the incident end face 46a of the optical fiber 46 and then enter each laser light source 41A, 41B, 41C, 41D of the laser module 2 as returned light via the focusing lens 3.

[0067] After being reflected by the incident end face 46a, the laser beam La enters the laser module 2 as return beam Lar via the condenser lens 3. Since the position of the laser beam La is asymmetric with respect to the second reference line 3c as described above, the return beam Lar travels an optical path different from the optical paths of the laser beams Lc and Ld. The optical path of the return beam Lar is located between the optical path of the laser beam Lc and the optical path of the laser beam Lc.

[0068] After being reflected by the incident end face 46a, the laser beam Lb enters the laser module 2 as return beam Lbr via the condenser lens 3. Since the position of the laser beam Lb is asymmetric with respect to the second reference line 3c as described above, the return beam Lbr travels along an optical path different from the optical paths of the laser beams Lc and Ld. The optical path of the return beam Lbr is located between the optical path of the laser beam Lc and the optical axis 3a of the condenser lens 3.

[0069] After being reflected by the incident end face 46a, the laser light Lc enters the laser module 2 as return light Lcr via the condenser lens 3. Because the position of the laser light Lc is asymmetric with respect to the second reference line 3c as described above, the return light Lcr travels an optical path different from the optical paths of the laser light La and Lb. The optical path of the return light Lcr is located between the optical paths of the laser light La and the laser light Lb.

[0070] After being reflected by the incident end face 46a, the laser light Ld enters the laser module 2 as return light Ldr via the condenser lens 3. Because the position of the laser light Ld is asymmetric with respect to the second reference line 3c as described above, the return light Ldr travels an optical path different from the optical paths of the laser lights La and Lb. The optical path of the return light Ldr is located on the opposite side of the optical axis 3a of the condenser lens 3 from the optical path of the laser light La.

[0071] As shown in (a) of FIG. 15, in this embodiment, the return light Lar is incident on a region of the laser light source 41D that does not overlap with the light-emitting region 41a. As shown in (b) of FIG. 15, in this embodiment, the return light Lbr is incident on a region of the laser light source 41C that does not overlap with the light-emitting region 41a. As shown in (c) of FIG. 15, in this embodiment, the return light Lcr is incident on a region of the laser light source 41B that does not overlap with the light-emitting region 41a. As shown in (d) of FIG. 15, in this embodiment, the return light Ldr is incident on a region of the laser light source 41A that does not overlap with the light-emitting region 41a.

[0072] As described above, in the laser device 1, when viewed from the X-axis direction, among the laser beams La, Lb, Lc, and Ld emitted from the laser module 2 while aligned along the Z-axis direction, the position of at least one laser beam (e.g., laser beam La) located on one side of the second reference line 3c in the Z-axis direction and the positions of all the laser beams Lc and Ld located on the other side of the second reference line 3c in the Z-axis direction are asymmetric with respect to the second reference line 3c. As a result, even if the laser beam La is reflected by the incident end face 46a of the optical fiber 46 and then enters the laser light source 41D as returned light Lar, the position of the returned light Lar does not coincide with the position of the light-emitting region 41a of the laser light source 41D, thereby suppressing deterioration of the laser light source 41D. In addition, the focal length Fd of the fast-axis collimating lens 42A is greater than the minimum value of the intervals G1, G2, and G3 between the laser beams La, Lb, Lc, and Ld emitted from the laser module 2 while aligned along the Z-axis direction. This allows the distance between the laser light source 41A and the incident surface 421 of the fast-axis collimating lens 42A to be increased, making it easier to attach the fast-axis collimating lens 42A to the laser light source 41A. This also facilitates the manufacture of the laser device 1. Therefore, the laser device 1 suppresses deterioration of the laser light source due to returned light, and also facilitates the manufacture of the laser device 1.

[0073] Reducing the focal length Fd of the fast-axis collimating lens 42A and reducing the spot diameter of the laser beam La makes it easier to change the position of the laser beam La incident on a limited area (e.g., the focusing lens 3). However, the smaller the focal length Fd of the fast-axis collimating lens 42A, the more likely it is that high-precision assembly of the fast-axis collimating lens 42A relative to the laser light source 41A is required. In this embodiment, the focal length Fd of the fast-axis collimating lens 42A is set to be greater than the minimum value of the intervals G1, G2, and G3, making it easier to assemble the fast-axis collimating lens 42A relative to the laser light source 41A. Furthermore, by arranging the laser beams La, Lb, Lc, and Ld so that the intervals G1, G2, and G3 are non-uniform, deterioration of the laser light source due to returned light is suppressed.

[0074] When viewed from the X-axis direction, of the laser beams La, Lb, Lc, and Ld emitted from the laser module 2 while aligned along the Z-axis direction, the positions of all the laser beams La and Lb located on one side of the second reference line 3c in the Z-axis direction and the positions of all the laser beams Lc and Ld located on the other side of the second reference line 3c in the Z-axis direction are asymmetric with respect to the second reference line 3c. This reliably suppresses deterioration of the laser light source due to returned light.

[0075] The laser module 2 has a support 30 including mounting surfaces 33a, 33b, 33c, and 33d arranged in a stepped manner so that the position in the Z axis direction increases with increasing distance from the focusing lens 3 in the X axis direction. Laser light sources 41A, 41B, 41C, and 41D are disposed on the mounting surfaces 33a, 33b, 33c, and 33d and emit laser beams La, Lb, Lc, and Ld to one side in the Y axis direction. The laser units 40A, 40B, 40C, and 40D include reflection mirrors 50A, 50B, 50C, and 50D that are disposed downstream of the slow axis collimating lenses 44A, 44B, 44C, and 44D in the optical path and reflect the laser beams La, Lb, Lc, and Ld emitted from the slow axis collimating lenses 44A, 44B, 44C, and 44D toward the focusing lens 3 along the X axis direction. The reflecting mirrors 50A, 50B, 50C, and 50D are aligned along the X-axis when viewed from the Z-axis direction. The reflecting mirrors 50A, 50B, 50C, and 50D include reflecting surfaces 51 that overlap with the laser light sources 41A, 41B, 41C, and 41D when viewed from the Y-axis direction. This makes it possible to adjust the asymmetry between the position of at least one laser beam (e.g., laser beam La) located on one side of the second reference line 3c in the Z-axis direction and the positions of all laser beams Lc and Ld located on the other side of the second reference line 3c in the Z-axis direction by adjusting the positions of the mounting surfaces 33a, 33b, 33c, and 33d in the Z-axis direction.

[0076] The laser device 1 includes a wavelength filter 5. The wavelength filter 5 is disposed between the laser module 2 (plurality of laser units 40A, 40B, 40C, and 40D) and the optical fiber 46. The wavelength filter 5 transmits the laser beams La, Lb, Lc, and Ld emitted from the laser module 2 and reflects the light emitted from the optical fiber 46. This prevents the light that has entered the housing 6 from the outside via the optical fiber 46 from entering the laser units 40A, 40B, 40C, and 40D.

[0077] The focal length Fd of the fast axis collimating lens 42A is 100 μm to 400 μm. As described above, this makes it easy to attach the fast axis collimating lens 42A to the laser light source 41A, facilitating the manufacture of the laser device 1. Furthermore, it is possible to easily align the fast axis collimating lens 42A with the laser light source 41A while reducing the width of the laser light La.

[0078] The intervals G1, G2, and G3 are 100 μm to 500 μm. As described above, this makes it easy to attach the fast axis collimating lens 42A to the laser light source 41A, facilitating the manufacture of the laser device 1. Furthermore, the laser beams La, Lb, Lc, and Ld can be made incident within the numerical aperture (NA) of the optical fiber 46 while suppressing vignetting of the laser beams La, Lb, Lc, and Ld by the reflecting mirrors 50A, 50B, 50C, and 50D.

[0079] The difference between the intervals G1, G2, and G3 is 700 μm or less. This allows the asymmetric state described above to be realized. Also, the laser beams La, Lb, Lc, and Ld can be suitably incident within the numerical aperture of the optical fiber 46.

[0080] When viewed from the X-axis direction, the difference between the distance (first distance R1) from the n-th laser beam (e.g., laser beam La) among the laser beams La, Lb, Lc, and Ld that is located on one side of the second reference line 3c in the Z-axis direction and counting from the second reference line 3c to the second reference line 3c and the distance (fourth distance R4) from the n-th laser beam (e.g., laser beam Ld) among the laser beams La, Lb, Lc, and Ld that is located on the other side of the second reference line 3c in the Z-axis direction and counting from the second reference line 3c to the second reference line 3c is 10 μm to 500 μm. This prevents the laser beam La from being reflected by the incident end surface 46a of the optical fiber 46 and entering the light-emitting region 41a of the laser light source 41D that emits the laser beam Ld as returned light Lar. Similarly, after the laser light Ld is reflected by the incident end surface 46a of the optical fiber 46, it is prevented from being incident as return light Ldr into the light emitting region 41a of the laser light source 41A that emits the laser light La. Therefore, deterioration of the laser light source due to return light is suppressed. Furthermore, the laser lights La, Lb, Lc, and Ld can be preferably incident within the numerical aperture of the optical fiber 46.

[0081] The functions and effects of the laser unit 40A are similarly exhibited by the laser units 40B, 40C, and 40D.

[0082] [Second embodiment] The laser device of the second embodiment differs from the laser device of the first embodiment mainly in that one laser light source emits multiple laser beams. As shown in FIG. 16, each of laser light sources 41A, 41B, 41C, and 41D may have, for example, one laser diode bar 413 instead of a semiconductor laser element 412. The laser diode bar 413 includes multiple light-emitting regions 41a. The laser diode bar 413 includes, for example, two light-emitting regions 41a. The multiple light-emitting regions 41a are arranged along the X-axis direction. The distance (center-to-center distance) between adjacent light-emitting regions 41a is, for example, 150 μm to 300 μm. Each light-emitting region 41a emits laser beam La. The Z-axis direction of each laser beam La is the fast axis direction, and the X-axis direction is the slow axis direction.

[0083] 17, when the laser diode bar 413 emits a plurality of laser beams La, the laser unit 40A further includes a prism unit 43A. The prism unit 43A is disposed in the optical path between the fast-axis collimating lens 42A and the slow-axis collimating lens 44A. The prism unit 43A is disposed on the base surface 33e of the support 30. The prism unit 43A is fixed to the base surface 33e with, for example, a UV-curable resin. The prism unit 43A may also be fixed to the fast-axis collimating lens 42A with, for example, a UV-curable resin.

[0084] Prism unit 43A adjusts the arrangement direction of the multiple laser beams La so that the multiple laser beams La emitted from fast-axis collimating lens 42A while being arranged along the X-axis direction are incident on slow-axis collimating lens 44A while being arranged along the Z-axis direction. Prism unit 43A is composed of multiple prisms.

[0085] As shown in FIG. 18 , the multiple laser beams La emitted from the laser light source 41A are arranged along the X-axis direction, and then exit the slow-axis collimating lens 44A in an array along the Z-axis direction, where they are reflected by the reflecting mirror 50A. Similar to the laser light source 41A, the laser light source 41B emits multiple laser beams Lb arranged along the X-axis direction. Similar to the multiple laser beams La, the multiple laser beams Lb exit the slow-axis collimating lens 44B in an array along the Z-axis direction, where they are reflected by the reflecting mirror 50B. Similar to the laser light source 41A, the laser light source 41C emits multiple laser beams Lc arranged along the X-axis direction. Similar to the multiple laser beams La, the multiple laser beams Lc exit the slow-axis collimating lens 44C in an array along the Z-axis direction, where they are reflected by the reflecting mirror 50C. Similar to the laser light source 41A, the laser light source 41D emits multiple laser beams Ld arranged along the X-axis direction. Similar to the multiple laser beams La, the multiple laser beams Ld are emitted from slow-axis collimator lens 44D while being arranged along the Z-axis direction, and are then reflected by reflecting mirror 50D. The multiple laser beams La, the multiple laser beams Lb, the multiple laser beams Lc, and the multiple laser beams Ld are incident on condenser lens 3 while being arranged along the Z-axis direction, and are condensed by condenser lens 3 as a single laser beam L. With this configuration, it is possible to suppress deterioration of laser light sources 41A, 41B, 41C, and 41D as described above, while maintaining the optical outputs of laser light sources 41A, 41B, 41C, and 41D.

[0086] [Variations] The present invention is not limited to the above-described embodiments.

[0087] 19, each of the laser light sources 41A, 41B, 41C, and 41D may have a plurality of semiconductor laser elements 414 instead of one semiconductor laser element 412. Each semiconductor laser element 414 may include one light-emitting region 41a. In this case, as in the second embodiment, each of the laser units 40A, 40B, 40C, and 40D may further include a prism unit. With this configuration, it is possible to suppress deterioration of the laser light sources 41A, 41B, 41C, and 41D as described above while maintaining the optical output of the laser light sources 41A, 41B, 41C, and 41D.

[0088] In the embodiment, when viewed from the X-axis direction, the positions of all the laser beams La, Lb located on one side of the second reference line 3c in the Z-axis direction and the positions of all the laser beams Lc, Ld located on the other side of the second reference line 3c in the Z-axis direction are asymmetric with respect to the second reference line 3c, but, for example, the position of the laser beam La and the position of the laser beam Lc or the laser beam Ld may be symmetric with each other. It is only necessary that the position of at least one laser beam located on one side of the second reference line 3c in the Z-axis direction and the positions of all the laser beams located on the other side of the second reference line 3c in the Z-axis direction are asymmetric with respect to the second reference line 3c.

[0089] In the embodiment, the laser light source 41A has the submount 411, but the laser light source 41A does not have to have the submount 411. In this case, the semiconductor laser element 412 of the laser light source 41A may be fixed to the support body 30 by, for example, a solder material or the like.

[0090] In the embodiment, the reflecting mirrors 50A, 50B, 50C, and 50D are fixed to the support body 30, but the reflecting mirrors 50A, 50B, 50C, and 50D may be fixed to the housing 6, for example.

[0091] In the embodiment, the laser device 1 is used to excite a fiber laser, but the laser device 1 may also be used for laser processing, for example.

[0092] In the embodiment, when viewed from the X-axis direction, the position of at least one laser beam located on one side of the second reference line 3c in the Z-axis direction and the positions of all laser beams located on the other side of the second reference line 3c in the Z-axis direction are asymmetric with respect to the second reference line 3c. However, the laser beams La, Lb, Lc, and Ld emitted from the laser module 2 while aligned along the Z-axis direction may be symmetric with respect to the second reference line 3c when viewed from the X-axis direction. It is sufficient that the focal length Fd of the fast-axis collimating lens 42A is greater than the minimum value of the intervals G1, G2, and G3 between the laser beams La, Lb, Lc, and Ld emitted from the laser module 2 while aligned along the Z-axis direction. In this case, the incident end surface 46a of the optical fiber 46 does not have to be perpendicular to the optical axis 3a of the focusing lens 3. Even in this case, as described above, the fast-axis collimating lens 42A can be easily attached to the laser light source 41A. This facilitates the manufacture of the laser device 1.

[0093] In the embodiment, the condensing lens 3 is separated from the laser module 2, but the condensing lens 3 may be fixed to the support 30 while being disposed on the main surface 32 of the support 30 of the laser module 2. In the embodiment, the wavelength filter 5 is separated from the laser module 2, but the wavelength filter 5 may be fixed to the support 30 while being disposed on the main surface 32 of the support 30 of the laser module 2. [Explanation of symbols]

[0094] REFERENCE SIGNS LIST 1...laser device, 2...laser module, 3...condensing lens, 3a...optical axis, 3c...second reference line, 5...wavelength filter, 6...casing, 30...support, 33a...first mounting surface, 33b...second mounting surface, 33c...third mounting surface, 33d...fourth mounting surface, 40A, 40B, 40C, 40D...laser unit, 41A, 41B, 41C, 41D...laser light source, 41a...light emitting area region, 42A, 42B, 42C, 42D...fast axis collimating lenses, 44A, 44B, 44C, 44D...slow axis collimating lenses, 46...optical fiber, 46a...incident end face, 50A, 50B, 50C, 50D...reflecting mirror, 51...reflecting surface, Fd...focal length, G1...first interval, G2...second interval, G3...third interval, La, Lb, Lc, Ld...laser light.

Claims

1. a laser module that emits a plurality of laser beams aligned along a first direction toward one side of a second direction that intersects with the first direction; a focusing lens having an optical axis parallel to the second direction and configured to focus the plurality of laser beams; an optical fiber having an incident end face perpendicular to the optical axis of the focusing lens, and through which the plurality of laser beams focused by the focusing lens propagate; a housing that houses the laser module and the condenser lens, The laser module includes a plurality of laser units, Each of the plurality of laser units a laser light source that emits at least one laser beam among the plurality of laser beams; a fast-axis collimating lens disposed in an optical path of the laser light and configured to collimate the laser light emitted from the laser light source in a fast-axis direction along the first direction; a slow axis collimating lens that is disposed downstream of the fast axis collimating lens in the optical path and that collimates the laser light emitted from the fast axis collimating lens in a slow axis direction, When viewed from the second direction, a plurality of intervals between the plurality of laser beams emitted from the laser module in a state of being aligned along the first direction are non-uniform, when viewed from the second direction, among the plurality of laser beams emitted from the laser module while being aligned along the first direction, a position of at least one laser beam that extends along a third direction that intersects both the first direction and the second direction and is located on one side in the first direction with respect to a reference line that passes through the optical axis of the condenser lens, and positions of all laser beams that are located on the other side in the first direction with respect to the reference line are asymmetric with respect to the reference line; A laser device, wherein the focal length of the fast axis collimating lens of each of the plurality of laser units is greater than the smallest value of the plurality of intervals.

2. 2. The laser device according to claim 1, wherein, when viewed from the second direction, of the plurality of laser beams emitted from the laser module while being aligned along the first direction, positions of all laser beams located on one side of the reference line in the first direction and positions of all laser beams located on the other side of the reference line in the first direction are asymmetric with respect to the reference line.

3. the laser module further includes a support including a plurality of mounting surfaces arranged in a stepped manner such that the positions in the first direction increase with increasing distance from the condenser lens in the second direction, and the laser light sources of the plurality of laser units are disposed on the plurality of mounting surfaces, respectively, and emit the laser light to one side in the third direction; each of the plurality of laser units further includes a reflection mirror that is disposed downstream of the slow axis collimating lens in the optical path and that reflects the laser light emitted from the slow axis collimating lens toward the condenser lens along the second direction; 2. The laser device according to claim 1, wherein the reflecting mirrors of each of the plurality of laser units are aligned along the second direction when viewed from the first direction and include a reflecting surface that overlaps with the laser light source when viewed from the third direction.

4. 2. The laser device according to claim 1, further comprising a wavelength filter disposed between the plurality of laser units and the optical fiber, the wavelength filter transmitting the plurality of laser beams emitted from the plurality of laser units and reflecting the light emitted from the optical fiber.

5. 2. The laser device of claim 1, wherein the focal length of the fast axis collimating lens is between 100 μm and 400 μm.

6. 2. The laser device according to claim 1, wherein each of the plurality of intervals is 100 μm to 500 μm.

7. The laser device according to claim 1 , wherein the difference between each of the plurality of intervals is 700 μm or less.

8. 2. The laser device according to claim 1, wherein, when viewed from the second direction, a difference between a distance from an n-th laser beam (n is a natural number) among the plurality of laser beams that is located on one side of the reference line in the first direction and counting from the reference line to the reference line, and a distance from an n-th laser beam among the plurality of laser beams that is located on the other side of the reference line in the first direction and counting from the reference line to the reference line, is 10 μm to 500 μm.

9. the laser light source of each of the plurality of laser units includes one laser diode bar; 10. The laser device of claim 1, wherein the single laser diode bar includes a plurality of light-emitting regions.

10. the laser light source of each of the plurality of laser units includes a plurality of semiconductor laser elements, 2. The laser device according to claim 1, wherein each of said plurality of semiconductor laser elements includes one light-emitting region.

Images