Laser device and laser determination method

Abstract

To provide a laser device and a laser determination method which are capable of determining a generation position of a return beam by a simple configuration.SOLUTION: A laser device 1 comprises: a laser module 2 which emits a plurality of laser beams; and a photodetector 8 which detects each of the plurality of laser beams. The laser module 2 has laser units 40A, 40B, 40C, 40D which emits laser beams. The laser units 40A, 40B, 40C, 40D includes: a laser source which emits laser beams; and reflection mirrors 50A, 50B, 50C, 50D which reflect the laser beams to a condenser lens 3 side along an X-axis direction. The photodetector 8 is arranged so as to oppose the laser source via the reflection mirrors 50A, 50B, 50C, 50D. The photodetector 8 detects laser beams having passed through the reflection mirrors 50A, 50B, 50C, 50D.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] A laser device is known that includes a laser light source that emits multiple laser beams and an optical fiber (see, for example, Patent Document 1). In such a laser device, multiple 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 return light may occur, and if the return light is incident on the laser light source, the laser light source may be deteriorated. In order to suppress deterioration of the laser light source due to the return light, it is important to determine the position where the return light is generated. Furthermore, there are cases where a simplified configuration is required for such a laser device.

[0005] An object of the present invention is to provide a laser device and a laser determination method that can determine the position where return light is generated with a simple configuration. [Means for solving the problem]

[0006] a housing accommodating the laser module, the collecting lens, and the photodetector; a laser module that emits a plurality of laser beams arranged along a first direction toward one side of a second direction intersecting the first direction; a collecting lens having an optical axis parallel to the second direction and collecting the plurality of laser beams; an optical fiber that has an incident end face perpendicular to the optical axis of the collecting lens and through which the plurality of laser beams collected by the collecting lens propagate; a photodetector that detects each of the plurality of laser beams; and a housing accommodating the laser module, the collecting lens, and the photodetector; wherein the laser module has a plurality of laser units that emit the plurality of laser beams; and a support body; wherein each of the plurality of laser units includes: a laser light source that emits at least one laser beam among the plurality of laser beams toward one side of a third direction intersecting both the first direction and the second direction; 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 a slow-axis collimating lens that collimates the laser light emitted from the fast-axis collimating lens in a slow-axis direction, and a reflecting mirror that is arranged downstream of the slow-axis collimating lens in the optical path and reflects the laser light emitted from the slow-axis collimating lens toward the collecting lens along the second direction, the support body includes a plurality of mounting surfaces arranged in a stepped manner such that the position in the first direction increases as the distance from the collecting lens in the second direction increases, the laser light source of each of the plurality of laser units is arranged on each of the plurality of mounting surfaces, and the reflecting mirrors of each of the plurality of laser units are arranged along the second direction when viewed from the first direction, the photodetector is arranged to face the laser light source of each of the plurality of laser units via the reflecting mirror of each of the plurality of laser units in the third direction, and detects each of the plurality of laser light beams that have passed through the reflecting mirror of each of the plurality of laser units.

[0007] The laser device described in [1] above includes a photodetector that detects each of the multiple laser beams emitted from the multiple laser units. This allows the location of return light entering the laser module to be determined based on multiple detection results corresponding to the multiple laser beams detected by the photodetector. Furthermore, the photodetector is positioned facing the laser light source via a reflecting mirror that reflects the laser light emitted from the laser light source toward the focusing lens, and detects the laser light that has passed through the reflecting mirror. This allows for the omission of components, etc., for guiding the laser light emitted from the laser light source to the photodetector. This simplifies the configuration. Therefore, this laser device allows the location of return light to be determined with a simple configuration.

[0008] The laser device of the present invention may be [2] "the laser device according to the above [1], further comprising a signal processing unit that determines the generation position of return light incident on the laser module based on a plurality of detection results corresponding to the plurality of laser beams detected by the photodetector." This allows the signal processing unit to determine the generation position of return light incident on the laser module.

[0009] The laser device of the present invention may be [3] "the laser device according to the above [2], wherein the signal processing unit determines that the return light has occurred when at least one of the plurality of detection results substantially fluctuates." This makes it possible to suitably determine the occurrence of the return light.

[0010] The laser device of the present invention may be [4] the laser device described in [3] above, wherein "when all of the plurality of detection results substantially fluctuate and the fluctuation range of each of the plurality of detection results tends to increase as the incidence position of each of the plurality of laser beams on the condenser lens approaches the optical axis, the signal processing unit determines that the returned light has occurred on the opposite side of the incidence end face of the optical fiber to the condenser lens." This makes it possible to specifically determine the generation position of the returned light.

[0011] The laser device of the present invention may be [5] the laser device described in [3] above, wherein "the signal processing unit determines that the returned light is generated at the incident end face of the optical fiber when the plurality of detection results include both detection results that substantially fluctuate and detection results that substantially do not fluctuate, or when all of the plurality of detection results substantially fluctuate and when the range of fluctuation of each of the plurality of detection results does not tend to increase as the incidence position of each of the plurality of laser beams on the focusing lens gets closer to the optical axis." This makes it possible to specifically determine the generation position of the returned light.

[0012] The laser device of the present invention may be [6] "the laser device according to any one of [2] to [5] above, wherein the plurality of laser beams are three or more laser beams, and the signal processing unit calculates an intensity distribution of the plurality of laser beams transmitted through the reflecting mirror of each of the plurality of laser units based on the plurality of detection results." This makes it possible to determine the position where the returning light is generated based on the intensity distribution of the laser beam transmitted through the reflecting mirror.

[0013] The laser device of the present invention may be [7] "the laser device according to any one of the above [1] to [6], wherein the photodetector has a plurality of photodetecting elements aligned along the second direction, and each of the plurality of photodetecting elements faces the respective laser light source of the plurality of laser units via the respective reflecting mirror of the plurality of laser units." This improves the degree of freedom in arranging each photodetecting element, and therefore improves the degree of freedom in arranging each laser light source.

[0014] The laser device of the present invention may be [8] "the laser device according to any one of the above [1] to [7], 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.

[0015] The laser device of the present invention may be [9] "the laser device according to any one of [1] to [8] above, wherein the photodetector includes a photodetection surface inclined with respect to the third direction." This prevents reflected light from the photodetector's photodetection surface from entering 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 [9], wherein the photodetector is attached to the housing at a distance from the support." This prevents heat from the laser light source from being transferred to the photodetector via the support, thereby preventing a decrease in the detection accuracy of the photodetector.

[0017] The laser device of the present invention may be

[11] "the laser device according to any one of the above [1] to

[10] , 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.

[0018] The laser device of the present invention may be

[12] "the laser device according to any one of the above [1] to

[10] , 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.

[0019] The laser determination method of the present invention is

[13] "a laser determination method comprising: a first step of preparing the laser device described in [1] above; a second step of emitting the plurality of laser beams by the laser module; a third step of detecting the plurality of laser beams by the photodetector; and a fourth step of determining the position of occurrence of return light incident on the laser module based on a plurality of detection results corresponding to the plurality of laser beams detected by the photodetector."

[0020] In the fourth step of the laser determination method described in

[13] above, the position where return light entering the laser module is generated is determined based on multiple detection results corresponding to multiple laser beams detected by the photodetector. Furthermore, in the first step, a laser device is prepared that is arranged opposite the laser light source via a reflecting mirror that reflects the laser light emitted from the laser light source toward the focusing lens, and that includes a photodetector that detects the laser light that has passed through the reflecting mirror. This makes it possible to omit components for guiding the laser light emitted from the laser light source to the photodetector. This simplifies the configuration. Therefore, this laser determination method allows the position where return light is generated to be determined with a simple configuration.

[0021] The laser determination method of the present invention may be

[14] "the laser determination method according to the above

[13] , wherein in the fourth step, if at least one of the plurality of detection results substantially fluctuates, it is determined that the return light has occurred." This makes it possible to suitably determine the occurrence of the return light.

[0022] The laser determination method of the present invention may be

[15] the laser determination method according to the above

[14] , wherein "in the fourth step, if all of the plurality of detection results substantially fluctuate and the fluctuation range of each of the plurality of detection results tends to increase as the incidence position of each of the plurality of laser beams on the condenser lens approaches the optical axis, it is determined that the returned light is generated on the opposite side of the condenser lens with respect to the incidence end face of the optical fiber." This makes it possible to specifically determine the generation position of the returned light.

[0023] The laser determination method of the present invention may also be

[16] the laser determination method according to the above

[14] , wherein "in the fourth step, if the plurality of detection results include both detection results that substantially fluctuate and detection results that substantially do not fluctuate, or if all of the plurality of detection results substantially fluctuate and if the fluctuation range of each of the plurality of detection results does not tend to increase as the incidence position of each of the plurality of laser beams on the focusing lens gets closer to the optical axis, it is determined that the returned light is generated at the incidence end face of the optical fiber." This makes it possible to specifically determine the generation position of the returned light. [Effects of the Invention]

[0024] According to the present invention, it is possible to provide a laser device and a laser determination method that can determine the position where return light is generated with a simple configuration. [Brief explanation of the drawings]

[0025] [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. 2 is a partially enlarged view of FIG. [Figure 13] FIG. 13 is a front view of the photodetector shown in FIG. 12. [Figure 14] FIG. 14 is a cross-sectional view taken along line XIV-XIV in FIG. [Figure 15] FIG. 10 is a schematic diagram showing fluctuations in light intensity. [Figure 16] FIG. 2 is a schematic diagram showing the position where return light is generated. [Figure 17] FIG. 2 is a schematic diagram showing the position where return light is generated. [Figure 18] 5A and 5B are schematic diagrams showing the intensity distribution of return light generated at each position. [Figure 19] 2 is a flowchart showing steps of a laser light determination method using the laser device shown in FIG. [Figure 20] 20 is a flowchart showing details of a fourth step shown in FIG. 19. [Figure 21] FIG. 10 is a front view of a laser light source according to a second embodiment. [Figure 22] FIG. 10 is a plan view of a laser unit according to a second embodiment. [Figure 23] 10A and 10B are schematic diagrams illustrating adjustment of the arrangement direction of a plurality of laser beams according to the second embodiment. [Figure 24] FIG. 10 is a front view of a laser light source according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0026] 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 redundant explanations will be omitted.

[0027] [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, an electrode 7, a photodetector 8, and a signal processing unit 9. The laser device 1 is used, for example, to excite a fiber laser. The laser module 2, the condenser lens 3, the wavelength filter 5, and the photodetector 8 are housed in the housing 6.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] The electrode 7 is fixed to the housing 6. The laser module 2 is driven by a voltage supplied via the electrode 7. The photodetector 8 detects each laser light emitted from the laser module 2. The signal processing unit 9 is disposed outside the housing 6. The signal processing unit 9 is electrically connected to the photodetector 8. The signal processing unit 9 is configured by a computer device such as an operator's PC (Personal Computer) or tablet terminal. The signal processing unit 9 processes the signal output from the photodetector 8.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] [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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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).

[0044] 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).

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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. Like the laser light source 41A, the laser light source 41B emits laser light Lb (see FIG. 11). Like the laser light source 41A, the laser light source 41C emits laser light Lc (see FIG. 11). Like the laser light source 41A, the laser light source 41D emits laser light Ld (see FIG. 11). The outputs of the laser light La emitted from the laser light source 41A, the laser light Lb emitted from the laser light source 41B, the laser light Lc emitted from the laser light source 41C, and the laser light Ld emitted from the laser light source 41D are substantially the same as one another. 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.

[0055] 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.

[0056] 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 multiple (three or more) laser lights La, Lb, Lc, and Ld aligned along the Z-axis direction (first direction) to one side (the side of the condenser lens 3) in the X-axis direction (second direction). The laser light La, the laser light Lb, the laser light Lc, and the laser light Ld are incident on the condenser lens 3 (see FIG. 1) aligned along the Z-axis direction.

[0057] 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).

[0058] As shown in FIG. 12, the photodetector 8 is disposed so as to face the laser light sources 41A, 41B, 41C, and 41D (see FIG. 10) via the reflecting mirrors 50A, 50B, 50C, and 50D in the Y-axis direction. In other words, the photodetector 8 is disposed on the opposite side of the reflecting mirrors 50A, 50B, 50C, and 50D from the laser light sources 41A, 41B, 41C, and 41D. A portion of the laser light La passes through the reflecting mirror 50A as transmitted light Lat, a portion of the laser light Lb passes through the reflecting mirror 50B as transmitted light Lbt, a portion of the laser light Lc passes through the reflecting mirror 50C as transmitted light Lct, and a portion of the laser light Ld passes through the reflecting mirror 50D as transmitted light Ldt. The photodetector 8 detects the transmitted light Lat, Lbt, Lct, and Ldt.

[0059] 13 and 14, the photodetector 8 has a support substrate 81, a circuit board 82, and a plurality of photodetector elements 83A, 83B, 83C, and 83D. The photodetector 8 is spaced apart from the laser module 2. The photodetector 8 is attached to the housing 6 at a distance from the support 30.

[0060] The support substrate 81 is fixed to the side wall 62 (see FIG. 1) of the housing 6, for example, by a resin adhesive or bolts. The support substrate 81 includes a support surface 811 that faces the laser module 2 in the Y-axis direction. The support surface 811 is a flat surface parallel to the X-axis direction. The support surface 811 is inclined with respect to the Y-axis direction. When viewed from the X-axis direction, the support surface 811 is inclined so as to move away from the laser module 2 in the Y-axis direction, for example, as it moves toward the opposite side of the reflecting mirror 50A with respect to the support body 30 in the Z-axis direction.

[0061] The circuit board 82 is fixed to the support surface 811 of the support board 81 by, for example, a resin adhesive or bolts. The circuit board 82 includes a support surface 821 that faces the laser module 2 in the Y-axis direction. The support surface 821 is a flat surface that is parallel to the X-axis direction. Like the support surface 811, the support surface 821 is inclined with respect to the Y-axis direction.

[0062] The photodetection elements 83A, 83B, 83C, and 83D are provided on the support surface 821. The photodetection elements 83A, 83B, 83C, and 83D are aligned along the X-axis direction. The photodetection element 83A faces the laser light source 41A (see FIG. 10) via the reflecting mirror 50A. In other words, the photodetection element 83A is disposed on the opposite side of the reflecting mirror 50A from the laser light source 41A. The photodetection element 83A detects the intensity of the transmitted light Lat that has passed through the reflecting mirror 50A. The photodetection element 83A includes a photodetection surface 831 that faces the reflecting mirror 50A in the Y-axis direction. The photodetection surface 831 is a flat surface that is parallel to the X-axis direction. The photodetection surface 831 is inclined with respect to the Y-axis direction, similar to the support surface 811.

[0063] The photodetector element 83B faces the laser light source 41B (see FIG. 10) via the reflecting mirror 50B. In other words, the photodetector element 83B is disposed on the opposite side of the reflecting mirror 50B from the laser light source 41B. The photodetector element 83B detects the intensity of the transmitted light Lbt that has passed through the reflecting mirror 50B. Like the photodetector surface 831 of the photodetector element 81A, the photodetector element 83B includes a photodetection surface that faces the reflecting mirror 50B in the Y-axis direction and is inclined with respect to the Y-axis direction.

[0064] The photodetector 83C faces the laser light source 41C (see FIG. 10) via the reflecting mirror 50C. In other words, the photodetector 83C is disposed on the opposite side of the reflecting mirror 50C from the laser light source 41C. The photodetector 83C detects the intensity of the transmitted light Lct that has passed through the reflecting mirror 50C. Like the photodetection surface 831 of the photodetector 81C, the photodetector 83C includes a photodetection surface that faces the reflecting mirror 50C in the Y-axis direction and is inclined with respect to the Y-axis direction.

[0065] The photodetector 83D faces the laser light source 41D (see FIG. 10) via the reflecting mirror 50D. In other words, the photodetector 83D is disposed on the opposite side of the reflecting mirror 50D from the laser light source 41D. The photodetector 83D detects the intensity of the transmitted light Ldt that has passed through the reflecting mirror 50D. Similar to the photodetection surface 831 of the photodetector 81D, the photodetector 83D includes a photodetection surface that faces the reflecting mirror 50D in the Y-axis direction and is inclined with respect to the Y-axis direction.

[0066] In the laser device 1, returning light may be generated at some position and may enter the light-emitting region 41a of the laser module 2. When returning light enters the light-emitting region 41a of the laser light source 41A, the transmitted light Lat fluctuates, when returning light enters the light-emitting region 41a of the laser light source 41B, the transmitted light Lbt fluctuates, when returning light enters the light-emitting region 41a of the laser light source 41C, the transmitted light Lct fluctuates, and when returning light enters the light-emitting region 41a of the laser light source 41D, the transmitted light Ldt fluctuates.

[0067] FIG. 15 is a schematic diagram showing the detection result of, for example, the photodetector element 83A of the photodetector 8. As shown in FIG. 15, when no returning light is incident on the light-emitting region 41a of the laser light source 41A, the intensity of the transmitted light Lat (detection result R) does not substantially fluctuate over time. When returning light is incident on the light-emitting region 41a, the intensity of the transmitted light Lat (detection result D) substantially fluctuates over time. "Substantially fluctuates" means that the fluctuation range of the detection result (the difference between the maximum and minimum values) is greater than a predetermined value. The predetermined value is determined based on the output of the laser beams La, Lb, Lc, and Ld output from the laser light sources 41A, 41B, 41C, and 41D, for example.

[0068] When at least one of the detection results of the photodetection elements 83A, 83B, 83C, and 83D of the photodetector 8 substantially varies, the signal processing unit 9 determines that returned light has occurred at some position and that the returned light has entered the light-emitting region 41a of the laser module 2. When the detection result of the photodetection element 83A substantially varies, the signal processing unit 9 determines that the returned light has entered the light-emitting region 41a of the laser light source 41A; when the detection result of the photodetection element 83B substantially varies, the signal processing unit 9 determines that the returned light has entered the light-emitting region 41a of the laser light source 41B; when the detection result of the photodetection element 83C substantially varies, the signal processing unit 9 determines that the returned light has entered the light-emitting region 41a of the laser light source 41C; and when the detection result of the photodetection element 83D substantially varies, the signal processing unit 9 determines that the returned light has entered the light-emitting region 41a of the laser light source 41D.

[0069] 16 is a schematic diagram illustrating a case where return light is generated at a position (first position) on the opposite side of the condenser lens 3 with respect to the incident end face 46a of the optical fiber 46. As shown in FIG. 16, for example, reflected light Lr may be generated by a reflecting member 47 located away from the exit end face 46b of the optical fiber 46. The reflected light Lr is incident on the exit end face 46b of the optical fiber 46 and then exits from the incident end face 46a of the optical fiber 46. The reflected light Lr is emitted from the incident end face 46a while diffusing, and enters (returns to) the laser module 2 via the condenser lens 3 as, for example, return light Lar, Lbr, Lcr, and Ldr. The return light Lar is incident on the light-emitting region 41a of the laser light source 41A, the return light Lbr is incident on the light-emitting region 41a of the laser light source 41B, the return light Lcr is incident on the light-emitting region 41a of the laser light source 41C, and the return light Ldr is incident on the light-emitting region 41a of the laser light source 41D. The intensity of the return light Lar, Lbr, Lcr, and Ldr tends to increase as the emission angle (the angle formed with respect to the axis of the optical fiber 46) when emitted from the incident end face 46a decreases (as the incident position on the condenser lens 3 approaches the optical axis 3a). For example, in Fig. 16, the intensity of the return light Lbr and Lcr having a relatively small emission angle is greater than the intensity of the return light Lar and Ldr having a relatively large emission angle.

[0070] FIG. 17 is a schematic diagram illustrating a case where return light is generated at the incident end surface 46a (second position) of the optical fiber 46. As shown in FIG. 17, the laser light Ld incident on the incident end surface 46a of the optical fiber 46 may be reflected by the incident end surface 46a. The reflected light of the laser light Ld is incident on the laser module 2 via the condenser lens 3 as return light Lar. The return light Lar is incident on the light-emitting region 41a of the laser light source 41A. Similarly, the laser light La may be reflected on the incident end surface 46a and then incident on the light-emitting region 41a of the laser light source 41D via the condenser lens 3. The laser light Lb may be reflected on the incident end surface 46a and then incident on the light-emitting region 41a of the laser light source 41C via the condenser lens 3. The laser light Ld may be reflected on the incident end surface 46a and then incident on the light-emitting region 41a of the laser light source 41A via the condenser lens 3. In these cases, the intensity of each return light is substantially the same.

[0071] The greater the intensity of the return light incident on the light-emitting region 41a of the laser light sources 41A, 41B, 41C, and 41D, the greater the intensity of the laser light La, Lb, Lc, and Ld emitted from the light-emitting region 41a, and the greater the intensity of the transmitted light Lat, Lbt, Lct, and Ldt that passes through the reflecting mirrors 50A, 50B, 50C, and 50D.

[0072] The signal processing unit 9 determines the generation position of the return light incident on each light-emitting region 41a of the laser module 2 based on multiple detection results corresponding to the multiple transmitted light beams Lat, Lbt, Lct, and Ldt detected by the photodetector 8. The signal processing unit 9 calculates the intensity distribution of the transmitted light beams Lat, Lbt, Lct, and Ldt based on the detection results of the photodetector elements 83A, 83B, 83C, and 83D of the photodetector 8. Fig. 18 is a graph in which the horizontal axis represents the positions of the photodetector elements 83A, 83B, 83C, and 83D and the vertical axis represents the intensities of the transmitted light beams Lat, Lbt, Lct, and Ldt detected by the photodetector elements 83A, 83B, 83C, and 83D.

[0073] Intensity distribution D1 shown in Fig. 18 is the intensity distribution of transmitted light Lat, Lbt, Lct, and Ldt when returned light occurs at the first position. As shown in Fig. 18, when returned light occurs at the first position, the intensities of returned light Lar, Lbr, Lcr, and Ldr tend to increase as the emission angle when emitted from incident end face 46a decreases (as the incident position on condenser lens 3 decreases), and therefore the intensities of transmitted light Lat, Lbt, Lct, and Ldt tend to increase from both ends of photodetector 8 in the X-axis direction toward the center. In Fig. 18, the intensity of transmitted light Lbt detected by photodetector element 83B and the intensity of transmitted light Lct detected by photodetector element 83C are greater than the intensity of transmitted light Lat detected by photodetector element 83A and the intensity of transmitted light Ldt detected by photodetector element 83D.

[0074] Intensity distribution D2 shown in Fig. 18 is the intensity distribution of transmitted light Lat, Lbt, Lct, and Ldt when returned light occurs at the second position. As shown in Fig. 18, when returned light occurs at the second position, only the intensity of transmitted light Lat detected by, for example, photodetector element 83A fluctuates. When returned light occurs at the second position, the intensity of any of transmitted light Lbt, Lct, and Ldt detected by photodetector elements 83B, 83C, and 83D may fluctuate. In this case, the intensity distribution of transmitted light Lbt, Lct, and Ldt is substantially the same as intensity distribution D2.

[0075] When the condition that all of the detection results of the photodetecting elements 83A, 83B, 83C, and 83D of the photodetector 8 substantially fluctuate and the fluctuation range of the detection results tends to increase as the incident positions of the laser beams La, Lb, Lc, and Ld on the collecting lens 3 are closer to the optical axis 3a is satisfied, the signal processing unit 9 determines that the returned light has occurred on the opposite side (first position) from the collecting lens 3 with respect to the incident end face 46a of the optical fiber 46. As shown in Fig. 16, when the returned light has occurred at the first position, the intensity of the returned light tends to increase as the incident position on the collecting lens 3 is closer to the optical axis 3a. 16, the intensity of the return light Lbr, Lcr corresponding to the laser light Lb, Lc whose incident position is closer to the optical axis 3a (incident on the laser light sources 41B, 41C that emit the laser light Lb, Lc) is greater than the intensity of the return light Lar, Ldr corresponding to the laser light La, Ld whose incident position is farther from the optical axis 3a (incident on the laser light sources 41A, 41D that emit the laser light La, Ld). In this case, the fluctuation range of the detection results of the photodetector elements 83B, 83C is greater than the fluctuation range of the detection results of the photodetector elements 83A, 83D. If the fluctuation range of the detection results of the photodetector elements 83B, 83C is greater than the fluctuation range of the detection results of the photodetector elements 83A, 83D, the signal processing unit 9 determines that the return light has occurred at the first position.

[0076] If the above condition is not satisfied, the signal processing unit 9 determines that the returned light has occurred at the incident end surface 46a (second position) of the optical fiber 46. If the detection results of the photodetecting elements 83A, 83B, 83C, and 83D of the photodetector 8 include both detection results that substantially fluctuate and detection results that substantially do not fluctuate, or if all of the detection results of the photodetecting elements 83A, 83B, 83C, and 83D of the photodetector 8 substantially fluctuate and there is no tendency for the range of fluctuation in the detection results to increase as the incident positions of the laser beams La, Lb, Lc, and Ld on the focusing lens 3 become closer to the optical axis 3a, the signal processing unit 9 determines that the returned light has occurred at the second position.

[0077] The signal processing unit 9 determines that the returned light has occurred at the second position when at least one of the detection results of the photodetecting elements 83A, 83B, 83C, and 83D of the photodetector 8 does not substantially fluctuate. The signal processing unit 9 determines that the returned light has occurred at the incident end surface 46a (second position) of the optical fiber 46 when only one of the detection results of the photodetecting elements 83A, 83B, 83C, and 83D of the photodetector 8 substantially fluctuates, when at least two of the detection results of the photodetecting elements 83A, 83B, 83C, and 83D substantially fluctuate and the at least two detection results are substantially the same, or when at least two of the detection results of the photodetecting elements 83A, 83B, 83C, and 83D substantially fluctuate and the fluctuation range of the detection results tends to be smaller as the incident positions of the laser beams La, Lb, Lc, and Ld on the focusing lens 3 are closer to the optical axis 3a. The phrase "substantially the same" means that the difference in the fluctuation range between the two detection results is smaller than a predetermined value. The predetermined value is determined, for example, based on the output of the laser beams La, Lb, Lc, and Ld output from the laser light sources 41A, 41B, 41C, and 41D. The signal processing unit 9 determines that the returned light occurred at the second position when only one of the photodetecting elements 83A, 83B, 83C, and 84D detects a detection result that fluctuates, for example, as shown in FIG. 15 as the detection result D. The signal processing unit 9 determines that the returned light occurred at the second position when one or more intensity distributions, for example, as shown in FIG. 18 as the intensity distribution D2, are calculated. The signal processing unit 9 determines that the returned light occurred at the second position when the fluctuation range of the detection results of the photodetecting elements 83B and 83C is smaller than the fluctuation range of the detection results of the photodetecting elements 83A and 83D.

[0078] As described above, the laser device 1 includes the photodetector 8 that detects the laser beams La, Lb, Lc, and Ld emitted from the laser units 40A, 40B, 40C, and 40D. This makes it possible to determine the position of occurrence of the return beam incident on the laser module 2 based on the detection results corresponding to the laser beams La, Lb, Lc, and Ld detected by the photodetector 8. Furthermore, the photodetector 8 is disposed so as to face the laser beams La, Lb, Lc, and Ld emitted from the laser beam sources 41A, 41B, 41C, and 41D via the reflecting mirrors 50A, 50B, 50C, and 50D that reflect the laser beams La, Lb, Lc, and Ld emitted from the laser beam sources 41A, 41B, 41C, and 41D toward the condenser lens 3, and detects the transmitted beams Lat, Lbt, Lct, and Ldt that have passed through the reflecting mirrors 50A, 50B, 50C, and 50D. This makes it possible to omit components for guiding the laser beams La, Lb, Lc, and Ld emitted from the laser light sources 41A, 41B, 41C, and 41D to the photodetector 8. This allows for a simplified configuration. Therefore, the laser device 1 can determine the position where the returning beam is generated with a simple configuration. Furthermore, it becomes possible to implement a device that notifies the operator of the position where the returning beam is generated.

[0079] The laser device 1 includes a signal processing unit 9 that determines the generation position of the return light incident on the laser module 2 based on the detection results corresponding to the laser beams La, Lb, Lc, and Ld detected by the photodetector 8. This allows the signal processing unit 9 to determine the generation position of the return light incident on the laser module 2.

[0080] The signal processing unit 9 determines that return light has occurred when at least one of the detection results of the photodetecting elements 83A, 83B, 83C, and 83D of the photodetector 8 substantially fluctuates. This allows the occurrence of return light to be appropriately determined. When the occurrence of return light is determined, the operation of the laser device 1 is stopped, thereby suppressing deterioration of the laser light sources 41A, 41B, 41C, and 41D.

[0081] When all of the detection results of the photodetecting elements 83A, 83B, 83C, and 83D of the photodetector 8 substantially fluctuate and the fluctuation range of the detection results tends to increase as the incidence positions of the laser beams La, Lb, Lc, and Ld on the condenser lens 3 are closer to the optical axis 3a, the signal processing unit 9 determines that the returned light has occurred on the opposite side of the incident end face 46a of the optical fiber 46 from the condenser lens 3. This makes it possible to specifically determine the generation position of the returned light. Furthermore, by clarifying the generation position of the returned light, it is possible to consider measures to prevent deterioration of the laser light sources 41A, 41B, 41C, and 41D.

[0082] The signal processing unit 9 determines that the returning light is generated at the incident end surface 46a of the optical fiber 46 when the detection results of the photodetecting elements 83A, 83B, 83C, and 83D of the photodetector 8 include both detection results that substantially fluctuate and detection results that do not substantially fluctuate, or when all of the detection results of the photodetecting elements 83A, 83B, 83C, and 83D of the photodetector 8 substantially fluctuate and the range of fluctuation in the detection results does not tend to increase as the incidence positions of the laser beams La, Lb, Lc, and Ld on the focusing lens 3 are closer to the optical axis 3a. This makes it possible to specifically determine the generation position of the returning light. Furthermore, by clarifying the generation position of the returning light, it is possible to consider measures to prevent deterioration of the laser light sources 41A, 41B, 41C, and 41D.

[0083] The signal processing unit 9 calculates the intensity distribution of the transmitted light Lat, Lbt, Lct, and Ldt that has passed through the reflecting mirrors 50A, 50B, 50C, and 50D of the laser units 40A, 40B, 40C, and 40D based on the detection results of the photodetecting elements 83A, 83B, 83C, and 83D of the photodetector 8. The position where the returned light is generated can be determined based on the intensity distribution of the transmitted light Lat, Lbt, Lct, and Ldt that has passed through the reflecting mirrors 50A, 50B, 50C, and 50D.

[0084] The photodetector 8 has photodetection elements 83A, 83B, 83C, and 83D lined up along the X-axis direction. The photodetection elements 83A, 83B, 83C, and 83D face the laser light sources 41A, 41B, 41C, and 41D via the reflecting mirrors 50A, 50B, 50C, and 50D. This improves the degree of freedom in the arrangement of the photodetection elements 83A, 83B, 83C, and 83D, and therefore the degree of freedom in the arrangement of the laser light sources 41A, 41B, 41C, and 41D.

[0085] 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.

[0086] The photodetecting elements 83A, 83B, 83C, and 83D of the photodetector 8 include a photodetection surface 831 that is inclined with respect to the Y-axis direction. This prevents reflected light from the photodetection surface 831 of the photodetector 8 from being incident on the laser light sources 41A, 41B, 41C, and 41D.

[0087] The photodetector 8 is attached to the housing 6 at a distance from the support 30. Since the heat of the laser light sources 41A, 41B, 41C, and 41D is prevented from being transmitted to the photodetector 8 via the support 30, a decrease in the detection accuracy of the photodetector 8 is prevented.

[0088] [Laser detection method] Next, a laser determination method using the laser device 1 will be described. As shown in FIG. 19, in the laser determination method, first, the laser device 1 is prepared (first step S1). Next, the laser module 2 emits laser beams La, Lb, Lc, and Ld (second step S2). Next, the photodetector 8 detects the laser beams La, Lb, Lc, and Ld (third step S3). In the third step S3, transmitted beams Lat, Lbt, Lct, and Ldt that have passed through the reflecting mirrors 50A, 50B, 50C, and 50D are detected. Next, based on a plurality of detection results corresponding to the laser beams La, Lb, Lc, and Ld detected by the photodetector 8, the generation position of the return beam entering the laser module 2 is determined (fourth step S4).

[0089] 20, in the fourth step S4, it is determined whether at least one of the plurality of detection results has substantially fluctuated (step S41). If it is determined that at least one of the plurality of detection results has substantially fluctuated (step S41: YES), it is determined that returned light has occurred (step S42). If it is not determined that at least one of the plurality of detection results has substantially fluctuated (step S41: NO), it is determined that returned light has not occurred (step S43).

[0090] Next, it is determined whether or not a condition is satisfied that all of the plurality of detection results substantially fluctuate and that the fluctuation range of the detection results tends to increase as the incident positions of the laser beams La, Lb, Lc, and Ld on the condenser lens 3 are closer to the optical axis 3a (step S44). If it is determined that all of the plurality of detection results substantially fluctuate and that the fluctuation range of the detection results tends to increase as the incident positions of the laser beams La, Lb, Lc, and Ld on the condenser lens 3 are closer to the optical axis 3a (step S44: YES), that is, if the above condition is satisfied, it is determined that the returned light has occurred on the opposite side of the incident end face 46a of the optical fiber 46 from the condenser lens 3 (first position) (step S45). If the above condition is not satisfied (step S44: NO), it is determined that the returned light has occurred at the incident end face 46a of the optical fiber 46 (second position) (step S46). That is, when all of the plurality of detection results substantially fluctuate and it is not determined that the fluctuation range of the detection results tends to increase as the incident position of the laser beams La, Lb, Lc, and Ld on the condenser lens 3 approaches the optical axis 3a (step S44: NO), it is determined that the returned light has occurred at the second position. Specifically, when the plurality of detection results include both detection results that substantially fluctuate and detection results that do not substantially fluctuate, or when all of the plurality of detection results substantially fluctuate and there is no tendency that the fluctuation range of the detection results tends to increase as the incident position of the laser beams La, Lb, Lc, and Ld on the condenser lens 3 approaches the optical axis 3a, it is determined that the returned light has occurred at the second position.

[0091] As described above, in the fourth step S4 of the laser determination method of this embodiment, the generation position of the return light incident on the laser module 2 is determined based on a plurality of detection results corresponding to the laser beams La, Lb, Lc, and Ld detected by the photodetector 8. Moreover, in the first step S1, the laser device 1 is prepared. The photodetector 8 is disposed to face the laser beams La, Lb, Lc, and Ld emitted from the laser beam sources 41A, 41B, 41C, and 41D via the reflecting mirrors 50A, 50B, 50C, and 50D, which reflect the laser beams La, Lb, Lc, and Ld emitted from the laser beam sources 41A, 41B, 41C, and 41D toward the focusing lens 3, and detects the transmitted beams Lat, Lbt, Lct, and Ldt transmitted through the reflecting mirrors 50A, 50B, 50C, and 50D. This eliminates the need for components for guiding the laser beams La, Lb, Lc, and Ld emitted from the laser beam sources 41A, 41B, 41C, and 41D to the photodetector 8. This simplifies the configuration. Therefore, according to this laser determination method, it is possible to determine the position where the returning light is generated with a simple configuration.

[0092] In the fourth step S4, if at least one of the plurality of detection results substantially varies, it is determined that return light has occurred, thereby making it possible to suitably determine the occurrence of return light.

[0093] In the fourth step S4, if all of the multiple detection results substantially fluctuate and the closer the incident positions of the laser beams La, Lb, Lc, and Ld onto the condenser lens 3 are to the optical axis 3a, the greater the fluctuation range of the detection results tends to be, it is determined that the returned light has occurred on the opposite side of the incident end face 46a of the optical fiber 46 to the condenser lens 3. This makes it possible to specifically determine the position where the returned light has occurred.

[0094] In the fourth step S4, if the plurality of detection results includes both detection results that substantially fluctuate and detection results that substantially do not fluctuate, or if all of the plurality of detection results substantially fluctuate and the fluctuation range of the detection results does not tend to increase as the incidence positions of the laser beams La, Lb, Lc, and Ld on the focusing lens 3 are closer to the optical axis 3a, it is determined that the returning light has occurred at the incident end surface 46a of the optical fiber 46. This makes it possible to specifically determine the generation position of the returning light.

[0095] [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. 21 , 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.

[0096] As shown in FIG. 22, 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.

[0097] 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.

[0098] As shown in FIG. 23 , the multiple laser beams La emitted from the laser light source 41A are arranged along the X-axis direction, then exit the slow-axis collimating lens 44A and 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 and 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 and 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 while maintaining the optical outputs of laser light sources 41A, 41B, 41C, and 41D.

[0099] [Variations] The present invention is not limited to the above-described embodiments.

[0100] 24, 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 while maintaining the optical output of the laser light sources 41A, 41B, 41C, and 41D.

[0101] In the embodiment, the signal processing unit 9 is arranged outside the housing 6, but the signal processing unit 9 may be arranged inside the housing 6. The laser device 1 does not necessarily have to include the signal processing unit 9.

[0102] In the embodiment, the photodetector 8 has the photodetecting elements 83A, 83B, 83C, and 83D, but the photodetector 8 may have a single photodetecting element facing the laser light sources 41A, 41B, 41C, and 41D via the reflecting mirrors 50A, 50B, 50C, and 50D. The photodetector 8 only needs to detect the transmitted light Lat, Lbt, Lct, and Ldt that have passed through the reflecting mirrors 50A, 50B, 50C, and 50D.

[0103] In the embodiment, the laser module 2 emits three or more laser beams, but it is sufficient that the laser module 2 emits at least two laser beams.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] 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]

[0108] 1...laser device, 2...laser module, 3...condensing lens, 3a...optical axis, 5...wavelength filter, 6...housing, 8...photodetector, 9...signal processing unit, 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 region, 42A, 4 2B, 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, 83A, 83B, 83C, 83D...photodetecting element, 831...photodetecting surface, La, Lb, Lc, Ld...laser light, Lat, Lbt, Lct, Ldt...transmitted 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 photodetector for detecting each of the plurality of laser beams; a housing that houses the laser module, the condenser lens, and the photodetector, the laser module includes a plurality of laser units that emit the plurality of laser beams and a support; Each of the plurality of laser units a laser light source that emits at least one laser beam among the plurality of laser beams toward one side of a third direction that intersects both the first direction and the second direction; 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; 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 condensing lens along the second direction, the support body includes 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, the laser light sources of the plurality of laser units are disposed on the plurality of mounting surfaces, respectively; the reflecting mirrors of the plurality of laser units are aligned along the second direction when viewed from the first direction, The photodetector is arranged to face the laser light sources of each of the plurality of laser units via the reflection mirrors of each of the plurality of laser units in the third direction, and detects each of the plurality of laser beams that have passed through the reflection mirrors of each of the plurality of laser units.

2. 2. The laser device according to claim 1, further comprising a signal processing unit that determines a generation position of return light incident on the laser module based on a plurality of detection results corresponding to the plurality of laser beams detected by the photodetector.

3. The laser device according to claim 2 , wherein the signal processing unit determines that the returned light has occurred when at least one of the plurality of detection results substantially fluctuates.

4. 4. The laser device according to claim 3, wherein the signal processing unit determines that the returned light is generated on the opposite side of the focusing lens from the incident end face of the optical fiber when all of the plurality of detection results substantially fluctuate and the fluctuation range of each of the plurality of detection results tends to be larger as the incident positions of each of the plurality of laser beams onto the focusing lens are closer to the optical axis.

5. 4. The laser device according to claim 3, wherein the signal processing unit determines that the returned light is generated at the incident end face of the optical fiber when the plurality of detection results include both detection results that substantially fluctuate and detection results that substantially do not fluctuate, or when all of the plurality of detection results substantially fluctuate and the fluctuation range of each of the plurality of detection results does not tend to increase as the incident position of each of the plurality of laser beams on the focusing lens gets closer to the optical axis.

6. the plurality of laser beams are three or more laser beams, The laser device according to claim 2 , wherein the signal processing unit calculates an intensity distribution of the plurality of laser beams transmitted through the reflecting mirrors of the plurality of laser units based on the plurality of detection results.

7. the photodetector has a plurality of photodetection elements aligned along the second direction, The laser device according to claim 1 , wherein each of the plurality of photodetector elements faces the laser light source of each of the plurality of laser units via the reflecting mirror of each of the plurality of laser units.

8. 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.

9. The laser device of claim 1 , wherein the photodetector includes a photodetection surface that is inclined with respect to the third direction.

10. The laser device of claim 1 , wherein the photodetector is attached to the housing at a distance from the support.

11. 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.

12. 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.

13. A first step of preparing the laser device according to claim 1; a second step of emitting the plurality of laser beams by the laser module; a third step of detecting the plurality of laser beams by the photodetector; and a fourth step of determining the position of occurrence of return light incident on the laser module based on a plurality of detection results corresponding to the plurality of laser light beams detected by the photodetector.

14. 14. The laser determination method according to claim 13, wherein in the fourth step, it is determined that the returned light has occurred if at least one of the plurality of detection results substantially fluctuates.

15. 15. The laser determination method of claim 14, wherein in the fourth step, if all of the plurality of detection results substantially fluctuate and the fluctuation range of each of the plurality of detection results tends to be larger the closer the incident position of each of the plurality of laser beams onto the focusing lens is to the optical axis, it is determined that the returned light is generated on the opposite side of the focusing lens from the incident end face of the optical fiber.

16. 15. The laser determination method according to claim 14, wherein in the fourth step, if the plurality of detection results include both detection results that substantially fluctuate and detection results that substantially do not fluctuate, or if all of the plurality of detection results substantially fluctuate and the fluctuation range of each of the plurality of detection results does not tend to increase as the incident position of each of the plurality of laser beams onto the focusing lens gets closer to the optical axis, it is determined that the returned light is generated at the incident end face of the optical fiber.

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