JP7488445B2 - Light source unit - Google Patents

Description

This disclosure relates to a light source unit.

High-power, high-brightness laser beams are used to process a wide variety of materials, such as cutting, drilling, and marking, and to weld metal materials. Some of the carbon dioxide gas laser devices and YAG solid-state laser devices that have traditionally been used for such laser processing are being replaced by fiber laser devices with high energy conversion efficiency. Semiconductor laser diodes (hereinafter simply referred to as LDs) are used as the excitation light source for fiber laser devices. In recent years, as LDs have become more powerful, technology is being developed that uses LDs not as excitation light sources, but as light sources of laser beams that directly irradiate materials for processing. This technology is called direct diode laser (DDL) technology.

Patent document 1 discloses an example of a laser light source that combines multiple laser beams emitted from multiple LDs to increase the optical output. The combination of multiple laser beams is called "spatial beam combining" and can be used to increase the optical output of, for example, the pumping light source of a fiber laser device and a DDL device.

U.S. Pat. No. 7,733,932

There is a demand for more reliable laser light sources suitable for spatial beam combining, and laser processing devices equipped with such laser light sources.

In a non-limiting exemplary embodiment, the light source unit of the present disclosure comprises a sealed semiconductor laser package including a laser diode having an emitter region that emits laser light and a window member that transmits the laser light, a first lens system that receives the laser light that has passed through the window member and forms an image of the emitter region on an image plane, and a second lens system that converts the laser light that has passed through the image plane into a collimated beam or a convergent beam and emits the beam.

Embodiments of the present disclosure can provide a novel light source unit suitable for spatial beam combining.

FIG. 1A is a top view showing a schematic configuration example of a conventional light source unit 100P that collimates and outputs laser light emitted from an LD in a chip state. FIG. 1B is a side view of an example of the configuration of the light source unit 100P shown in FIG. 1A. FIG. 2 is a perspective view showing an example of the basic configuration of the LD 12. As shown in FIG. FIG. 3A is a schematic cross-sectional view parallel to the XZ plane showing a configuration example of a light source unit 100Q that collimates and outputs laser light emitted from the LD 12 housed in the package 10. FIG. 3B is a schematic cross-sectional view parallel to the YZ plane of the light source unit 100Q shown in FIG. 3A. FIG. 4 is a diagram showing an example of a basic configuration of the light source unit 100 in this embodiment. FIG. 5 is an enlarged view of the main part of the light source unit 100. As shown in FIG. FIG. 6 is a diagram showing a configuration in which the first lens system 20 includes an objective lens system 24 and an imaging lens system 26 . FIG. 7A is a schematic top view of the laser light source module 200 in this embodiment as viewed in the normal direction to the XZ plane. FIG. 7B is a schematic side view of the laser light source module 200 in this embodiment as viewed in the normal direction to the YZ plane. FIG. 7C is a schematic front view of the laser light source module 200 in this embodiment as viewed in the normal direction to the XY plane. FIG. 8 is a perspective view showing a schematic diagram of another configuration example including nine light source units 100. In FIG. FIG. 9A is a diagram showing an example of the configuration of the optical system 160. FIG. 9B is a diagram showing another example of the configuration of the optical system 160. In FIG. FIG. 10A is a diagram showing a schematic cross-sectional shape of the beam when five collimated beams B are incident on the fast axis convergent lens FAF. FIG. 10B is a diagram showing a schematic cross-sectional shape of the nine collimated beams B when they are incident on the fast axis focusing lens FAF. FIG. 10C is a diagram showing a schematic cross-sectional shape of a beam when 9×2 rows of collimated beams B are incident on a fast axis convergent lens FAF. FIG. 11 is a perspective view showing another configuration example of the laser light source module 200. As shown in FIG. FIG. 12 is a diagram showing another example of the configuration of the laser light source module 200. In FIG. FIG. 13 is a diagram showing an example of the configuration of an embodiment of a direct diode laser (DDL) device according to the present disclosure. FIG. 14 is a diagram illustrating a configuration example of an embodiment of a fiber laser device according to the present disclosure. FIG. 15 is a diagram showing a modified example of the light source unit in the embodiment of the present disclosure. FIG. 16 is a perspective view that illustrates an example in which the propagation direction of the collimated beam B is inclined with respect to the Z axis. FIG. 17A is a perspective view illustrating the wedge prism 34. FIG. FIG. 17B is a cross-sectional view illustrating the wedge prism 34. FIG. 17C is a diagram showing a schematic diagram of a state in which the collimated beam B emitted from the wedge prism 34 is steered so as to describe a conical surface. FIG. 18 is a diagram showing a wedge prism 34 having a cross section with a symmetrical prism shape. FIG. 19 is a diagram showing a state in which the wedge prism 34 is rotated by an angle θ0 around the X-axis. FIG. 20 is a diagram showing a front view and a cross section of the optical path correction element 32. As shown in FIG. FIG. 21 is a perspective view showing an example of the configuration of the optical path correction element 32. As shown in FIG. FIG. 22 is a perspective view showing a schematic diagram of another configuration example including a plurality of light source units 100 each having an optical path correction element 32. In FIG.

Before describing the embodiments of the present disclosure, we will explain the findings of the inventors and their technical background.

Figure 1A is a top view showing a schematic configuration example of a conventional light source unit 100P that collimates and outputs laser light emitted from an LD in a chip state, and Figure 1B is a side view of the same. For reference, the attached drawing shows a schematic XYZ coordinate system based on mutually orthogonal X-axis, Y-axis, and Z-axis.

The illustrated light source unit 100P includes an LD 12 that emits laser light L and an optical system 30P that collimates the laser light L. In the illustrated example, the optical system 30P includes a fast axis collimator lens FAC and a slow axis collimator lens SAC that are arranged on the optical axis in order from the position closest to the LD 12. Both the fast axis collimator lens FAC and the slow axis collimator lens SAC are cylindrical lenses (e.g., cylindrical plano-convex lenses). The cylindrical lens has a curved surface that converges a parallel light beam onto a straight line (focal point). The curved surface has a shape that corresponds to a part of the outer peripheral surface of a cylinder, and the curvature in the axial direction of the cylinder is zero. Spatial beam combining can be performed using multiple light source units 100P each having the illustrated configuration. Details of spatial beam combining will be described later.

2 is a perspective view showing an example of the basic configuration of the LD 12. The configuration shown is simplified for the purpose of explanation. In the example of FIG. 2, the LD 12 has a striped p-side electrode 12P formed on the upper surface, an n-side electrode 12N formed on the lower surface, and an emitter region E located on the end surface 12F. Laser light L is emitted from the emitter region E. The LD 12 has a semiconductor substrate and a plurality of semiconductor layers (semiconductor laminate structure) grown on the semiconductor substrate. The semiconductor laminate structure includes a light-emitting layer that emits light by performing laser oscillation, and may have various known configurations. The LD 12 in this example is a broad area type, and the emitter region E has a shape in which the size in the X-axis direction (e.g., 50 μm or more) is significantly larger than the size in the Y-axis direction (e.g., about 2 μm). The Y-axis size of the emitter region E is determined by the semiconductor laminate structure of the LD 12 (specifically, the thickness of the waveguide and cladding layer, the refractive index ratio, etc.). The X-axis size of the emitter region E is determined by the X-axis size of the region through which current flows across the light-emitting layer, specifically the width of the ridge structure (not shown) (gain waveguide width).

As shown in FIG. 2, the beam shape of the laser light L emitted from the emitter region E is asymmetric in the X-axis direction and the Y-axis direction. In FIG. 2, the far-field pattern of the laser light L is shown typically. The laser light L has a beam shape that is approximated to a single-mode Gaussian beam in the Y-axis direction, but has a multi-mode beam shape with a small overall divergence angle in the X-axis direction. The divergence half angle θ _y0 in the Y-axis direction is larger than the divergence half angle θ _x0 in the X-axis direction. Since the laser light L in the Y-axis direction can be approximated to a Gaussian beam, if the beam radius at the beam waist position in the Y-axis direction is ω _o and the wavelength of the laser light L is λ, then θ _y0 = tan ^-1 (λ/πω _o ) ≒ λ/(πω _o ) radians is established. In the case of a broad-area laser diode in which λ is in the visible light range, θ _y0 is, for example, 20 degrees and θ _x0 is, for example, 5 degrees. As a result, the Y-axis size of the laser light L diverges and expands relatively "fast" when propagating along the Z-axis direction. For this reason, the Y-axis is called the "fast axis" and the X-axis is called the "slow axis." The beam quality in the slow axis direction is relatively degraded compared to the beam quality in the fast axis direction because of the multimode. As a result, the beam parameter product BPP (Beam Parameter Product) that defines the beam quality is relatively larger in the slow axis direction compared to the value in the fast axis direction. Note that BPP is the product of the beam waist radius and the divergence half angle in the far field.

In the example shown in the figure, the Z axis is parallel to the propagation direction (beam central axis) of the laser light L emitted from the LD 12. When describing the operation of a single LD, it is convenient to make the origin of the XYZ coordinate system coincide with the center of the emitter region E. However, when describing spatial beam combining for multiple LDs, the origin of the XYZ coordinate system does not need to be determined in relation to any of the LDs. In addition, the orientations of multiple LDs used in spatial beam combining do not need to be parallel to each other, and individual laser beams may be reflected by different mirrors to change their propagation direction. For this reason, the terms "fast axis direction" and "slow axis direction" in this disclosure are not necessarily parallel to the "Y axis direction" and "X axis direction" in the global XYZ coordinate system, respectively, and are determined depending on the asymmetry of the beam quality of each laser beam. That is, in a cross section perpendicular to the propagation direction of the laser beam, the direction with the lowest BPP is the "fast axis", and the direction perpendicular to the fast axis is the "slow axis".

Again, reference is made to Figures 1A and 1B. In these figures, for simplicity, the laser light L and the collimated beam B are represented in a simplified manner by three representative rays. Of the three rays, the central ray is on the optical axis of the lens, and the other two rays show the positions that define the beam diameter. The beam diameter may be defined by the size of a region having a light intensity of, for example, 1/e2 or ^more with respect to the light intensity at the center of the beam, where e is Napier's number (approximately 2.71). The beam diameter or beam radius may be defined by other criteria.

As shown in FIG. 1B, the fast axis collimator lens FAC collimates the laser light L in a plane (YZ plane) that includes the propagation direction (Z axis) and fast axis direction (Y axis) of the laser light L. As shown in FIG. 1A, the slow axis collimator lens SAC collimates the laser light L in a plane (XZ plane) that includes the propagation direction (Z axis) and slow axis direction (X axis). To perform this collimation, the fast axis collimator lens FAC and the slow axis collimator lens SAC are positioned so that the center of the emitter region E is located at their respective front foci.

The cross section of the laser light L, which is shown in FIG. 2, has a shape that is shorter in the fast axis direction than in the slow axis direction in the near field, reflecting the shape of the emitter region E. However, since the divergence half angle in the fast axis direction is large, the size in the fast axis direction rapidly expands as it moves away from the emitter region E. Therefore, the shape and size of the cross section of the collimated beam B after passing through the optical system 30P depend on the positions of the fast axis collimator lens FAC and the slow axis collimator lens SAC on the optical path of the laser light L. More precisely, the fast axis size of the collimated beam B is determined by the divergence half angle θ _y0 in the fast axis direction (or the numerical aperture of the fast axis collimator lens FAC) and the focal length of the fast axis collimator lens FAC. Similarly, the slow axis size of the collimated beam B is determined by the divergence half angle θ _x0 in the slow axis direction (or the numerical aperture of the slow axis collimator lens SAC) and the focal length of the slow axis collimator lens SAC.

In general, the closer the fast axis collimator lens FAC is to the end face 12F of the LD 12, more specifically, to the emitter region E, the smaller the fast axis size of the collimated beam B can be. In other words, the farther the fast axis collimator lens FAC is from the end face 12F (emitter region E) of the LD 12, the larger the fast axis size of the collimated beam B. Similarly, the farther the slow axis collimator lens SAC is from the end face 12F (emitter region E) of the LD 12, the larger the slow axis size of the collimated beam B. Note that when changing the positions of the fast axis collimator lens FAC and the slow axis collimator lens SAC on the optical path of the laser light L, it is necessary to appropriately change the aperture and focal length of the collimator lenses FAC and SAC. The center of the emitter region E is always located at the front focal point of each of the collimator lenses FAC and SAC.

When spatial beam combining is performed using a plurality of light source units 100P having the above configuration, if an LD 12 with an oscillation wavelength shorter than the near-infrared region is adopted and its optical output is increased, there is a problem that dust in the atmosphere may adhere to the emitter region E during operation due to the optical dust collection effect, and the optical output may decrease. The material that adheres to the emitter region is not limited to dust, and there is also the possibility of deposits generated by chemical reaction of volatilized organic matter with the laser light L. The shorter the wavelength of the laser light L becomes and the higher the optical output becomes, the more significant the deterioration caused by the adhered material becomes. In order to avoid such a problem, when a plurality of LDs 12 are housed in a housing, it is possible to assemble the housing while taking care not to let dust get into the housing and seal the housing itself. However, it has been found that dust may adhere to parts such as the lens system and mirrors required for spatial beam combining, and it is difficult to increase the airtightness of the entire housing, making it difficult to maintain high optical output for a long period of time.

Another possible solution to this problem is to house each LD 12 in a sealed semiconductor laser package. LD packaging technology is highly advanced, and highly reliable operation over long periods of time has been achieved. However, when the LD 12 is housed inside a semiconductor laser package, even if an attempt is made to bring the fast axis collimator lens FAC close to the emitter region of the LD 12, the semiconductor laser package physically interferes, making it impossible to bring the lens close enough, and only fast axis collimator lenses FAC with a relatively long focal length can be used. This point is explained below.

Figure 3A is a schematic cross-sectional view parallel to the XZ plane showing an example of the configuration of a light source unit 100Q that collimates and outputs the laser light emitted from the LD 12 housed in the semiconductor laser package 10, and Figure 3B is a schematic cross-sectional view parallel to the YZ plane. Hereinafter, the semiconductor laser package may be simply referred to as a package.

As can be seen from the figure, the window member 14 of the package 10 is located between the emitter region E of the LD 12 and the fast axis collimator lens FAC, and the fast axis collimator lens FAC cannot be brought closer to the emitter region E of the LD 12 than the state shown in the figure. In the case of the light source unit 100P described above, the distance from the emitter region E of the LD 12 to the fast axis collimator lens FAC can be set to, for example, 0.3 millimeters (mm). In contrast, the distance from the emitter region E of the LD 12 housed inside the package 10 to the fast axis collimator lens FAC (meaning the "optical distance" described later) increases to, for example, about 1.5 mm. Since the center of the emitter region E needs to be located at the front focus of the fast axis collimator lens FAC, the focal length of the fast axis collimator lens FAC needs to be long, which inevitably increases the fast axis (Y axis) size of the collimated beam B by several times. If the fast axis size of the collimated beam B increases, inconveniences such as the size of the convergent optical system used to perform spatial beam combination will occur. This inconvenience will be explained in more detail below.

According to an embodiment of the present disclosure, it is possible to solve such problems. Below, an example of the basic configuration of the light source unit 100 in an embodiment of the present disclosure is described.

<Embodiment>
Light source unit
Fig. 4 is a diagram showing an example of a basic configuration of the light source unit 100 in this embodiment. Fig. 5 is a schematic diagram of a main part of the light source unit 100. In the example shown in the figure, the light source unit 100 includes a sealed package 10, a first lens system 20, and a second lens system 30.

The package 10 includes an LD 12 having an emitter region E on an end surface 12F that emits laser light L, and a window member 14 that transmits the laser light L. The configuration of the package 10 is not particularly limited, and may be, for example, a TO-CAN type package such as Φ5.6 mm or Φ9 mm. The package 10 includes a stem having a lead terminal and a metal cap that covers the LD fixed to the stem, and a window member 14 having light transmission is attached to the metal cap. A typical example of the window member 14 is a thin plate made of optical glass (refractive index: 1.4 or more). The inside of the package 10 can be filled with a highly clean inert gas such as nitrogen gas or a rare gas, and hermetically sealed. The LD 12 may be, for example, a semiconductor laser element made of a nitride semiconductor material that outputs near-ultraviolet, blue-violet, blue, or green laser light. Specifically, the oscillation wavelength (center wavelength) of the LD 12 is, for example, in the range of 350 nm to 550 nm. The LD 12 can be fixed to the stem via a submount with high thermal conductivity. The orientation of the LD 12 is not limited to the example shown in the figure, and it may be arranged so that the laser light is reflected in the Z-axis direction by a mirror in the package.

The first lens system 20 receives the laser light L transmitted through the window member 14 and forms an image E' of the emitter region E on the image plane 22. In the example shown in FIG. 5, a second window member 15 having the same configuration and size as the window member 14 is arranged on the optical path of the first lens system 20. The second window member 15 is placed in a position symmetrical to the position of the window member 14 with respect to the first lens system 20. The image plane 22 is a surface on which light rays emitted from each point of the emitter region E are converged to one point by the refraction action of the first lens system 20 to form an image. The emitter region E and the image E' on the image plane 22 are at or near a conjugate position. In the embodiment of the present disclosure, the optical axis of the laser light L passing through the center of the emitter region E coincides with the optical axis of the first lens system 20. In this disclosure, the plane perpendicular to the optical axis of the first lens system 20, which passes through the center of the point where the light emitted from the center of the emitter region E is converged by the first lens system 20, is defined as the "image plane". When a screen is placed on the image plane 22, an image E' of the emitter region E is formed on the screen. However, since no screen is actually placed on the image plane 22, the image E' functions as a virtual light source located in free space. Such a virtual light source may be called an intermediate image, redevelopment, or transfer image of the emitter region E. The second window member 15 compensates for the effect of the window member 14 on the laser light L, and contributes to the shape of the image E' formed on the image plane 22 accurately reproducing the shape of the emitter region E. Although the second window member 15 is not essential, it is preferable that the first lens system 20 has the second window member 15 or an optical member that can perform the function of the second window member 15.

The second lens system 30 converts the laser light L that has passed through the image plane 22 into a collimated beam B or a convergent beam and emits it. The second lens system 30 takes in light from the image (virtual light source) E' of the emitter region E located on the image plane 22, so the focal length of the second lens system 30 can be shortened without being subject to physical constraints (interference) due to the structure of the package 10.

5 shows the distance L0 from the end face 12F of the LD 12 to the outer surface 14S of the window member 14, and the distance L2 from the image plane 22 to the second lens system 30. In the example shown in FIG. 5, the fast axis collimator lens FAC of the second lens system 30 is arranged so that L0>L2. In this way, the focal length of the second lens system 30 (specifically the fast axis collimator lens FAC) can be shortened and the diameter of the collimated beam B can be made smaller than when it is subject to physical constraints due to the structure of the package 10. Here, "distance" means "optical distance". The optical distance is the integral of n·ds, which is the product of the line element ds and the refractive index n along the path of the light ray, and is also called the "optical distance" or "optical path length". The distance L0 may vary depending on the refractive index of the window member 14 even if the thickness of the window member 14 is the same. Since the refractive index of the window member 14 is higher than the refractive index of air (approximately 1.0), the presence of the window member 14 substantially increases the optical distance. The thickness of the window member 14 is typically about 0.25 mm. If the window member 14 is made of glass with a refractive index of 1.52, for example, the optical distance of the window member 14 alone can reach 0.38 (=0.25×1.52) mm. Furthermore, since there is a certain gap between the LD 12 and the window member 14, the distance L0 may be 1.0 mm or more. The distance from the image plane 22 to the second lens system 30 means the optical distance between the image plane 22 and the surface located closest to the image plane 22 among the surfaces of one or more optical elements such as lenses included in the second lens system 30. In this embodiment, the distance L2 from the image plane 22 to the second lens system 30 corresponds to the "front focal length", "working distance", and "BFL: Back Focal Length" of the fast axis collimator lens FAC.

According to this embodiment, the distance L2, i.e., the "front focal length" of the fast axis collimator lens FAC, can be set to 1.0 mm or less, typically 0.8 mm or less, and can also be set to a value of 0.5 mm or less (e.g., about 0.3 mm). In this way, the fast axis (Y-axis) direction size of the collimated beam B can be kept small while the LD 12 is housed inside the sealed package 10. As a result, it is possible to improve long-term reliability without enlarging the size of the optical system for convergence when performing spatial beam combining.

The first lens system 20 does not have to be composed of a single lens, and may be composed of a compound lens. As shown in FIG. 6, the first lens system 20 may be a relay lens including an objective lens system 24 and an imaging lens system 26. By using the objective lens system 24 and the imaging lens system 26, an infinity corrected optical system can be formed. The objective lens system 24 and the imaging lens system 26 may also each be a compound lens. By employing a compound lens, aberration can be reduced and deterioration of beam quality can be suppressed.

In the example of FIG. 6, the emitter region E of the LD 12 is located at the front focus of the objective lens system 24. The image plane 22 is located at the rear focus of the imaging lens system 26. In the embodiment of the present disclosure, the effective focal length F2 of the imaging lens system 26 is equal to or greater than the effective focal length F1 of the objective lens system 24. The effective focal length means the distance from the principal point of the lens to the focal point. Since the lateral magnification of the image formed on the image plane 22 is F2/F1, the size of the image E' of the emitter region E on the image plane 22 is F2/F1 times the size of the emitter region E. When F2 is larger than F1, the enlarged image E' of the emitter region E functions as a virtual light source. Here, the size of the virtual light source in the fast axis direction, that is, the fast axis beam diameter on the image plane 22 is 2×ω _y1 . In addition, the fast axis divergence half angle (divergence half angle in the far field) of the beam emitted from the virtual light source is θ _y1 . On the other hand, the fast axis size of the actual emitter region E, that is, the fast axis direction beam diameter in the emitter region E, is 2×ω _y0 . In addition, the fast axis direction divergence half angle of the beam emitted from the emitter region E (divergence half angle in the far field) is θ _y0 . Under the condition that the beam quality does not deteriorate, the relationship ω _y0 ×θ _y0 =ω _y1 ×θ _y1 is established. Therefore, when F2/F1 is larger than 1, ω _y1 is larger than ω _y0 , and θ _y1 is smaller than θ _y0 . As a result, it is possible to reduce the numerical aperture of the second lens system 30 (the fast axis collimator lens FAC and the slow axis collimator lens SAC) and increase the effective focal length. The technical significance of this will be described later.

The second lens system 30 is not limited to an optical system that emits a collimated beam, but may be an optical system that emits a convergent beam.

In this embodiment, the distance L2 from the image plane 22 to the second lens system 30 is determined by the distance from the image plane 22 to the fast axis collimator lens FAC. Here, the distance from the image plane 22 to the fast axis collimator lens FAC means the optical distance between the image plane 22 and the surface of the fast axis collimator lens FAC that is closest to the image plane 22. By using the fast axis collimator lens FAC and the slow axis collimator lens SAC without using an aspheric lens, appropriate collimation can be achieved individually for each of the fast axis and the slow axis. According to an embodiment of the present disclosure, by arranging the fast axis collimator lens FAC in a position close to the image plane 22, the effective focal length of the fast axis collimator lens FAC can be shortened and the fast axis size of the collimated beam B can be reduced.

In an embodiment of the present disclosure, when the second lens system 30 includes a fast axis collimator lens FAC and a slow axis collimator lens SAC arranged in this order from the image plane 22 side, the effective focal length EFL of the fast axis collimator lens FAC can be set to 1.0 mm or less, thereby making it possible to make the fast axis size of the collimated beam B, for example, 1.0 mm or less (for example, about 0.8 mm). If the fast axis size of the collimated beam B is small, the optical system and device (beam combiner) for spatially combining multiple collimated beams B can be made smaller.

An aperture stop may be placed at the position of the image plane 22. The aperture stop can block unnecessary light at the periphery of the emitter image E', which functions as a virtual light source. When the collimated beam B enters the optical fiber, the interference light (the interference light formed outside the airy disk) that is unnecessary for fiber coupling is removed by the action of the aperture stop.

Laser Light Source Module Next, an embodiment of the laser light source module according to the present disclosure will be described with reference to Fig. 7A, Fig. 7B, and Fig. 7C. Fig. 7A is a schematic top view of the laser light source module 200 in this embodiment as viewed from the normal direction of the XZ plane, Fig. 7B is a schematic side view as viewed from the normal direction of the YZ plane, and Fig. 7C is a schematic front view as viewed from the normal direction of the XY plane. The illustrated configuration is accommodated in a housing (not shown).

The illustrated laser light source module 200 includes a plurality of laser light sources 100A, 100B, and 100C, and a beam combiner 120. Each of the plurality of laser light sources 100A, 100B, and 100C is the light source unit 100 described above. Hereinafter, for simplicity, the laser light sources 100A, 100B, and 100C may be collectively referred to as the "light source unit 100". The number of light source units 100 included in one laser light source module 200 is arbitrary. In this example, the number of light source units 100 is three, but typically four or more. FIG. 8 is a perspective view showing a schematic diagram of another configuration example including nine light source units 100. It is possible to increase the optical output and optical intensity of the combined beam in proportion to the number of light source units 100. In order to increase the filling rate by filling a limited space with a large number of collimated beams, it is preferable to reduce the fast axis size of the collimated beam and shorten the center-to-center pitch S of the collimated beam B in the Y-axis (fast axis) direction.

Although the collimated beam B is simply depicted as a completely parallel light in the drawing, the actual collimated beam B diverges at a predetermined divergence angle after reaching the minimum beam radius at the beam waist. For this reason, in the example shown in FIG. 8, if the number of light source units 100 becomes too large, the optical path of the collimated beam B from the light source unit 100 located away from the convergence optical system 160 may become long and the beam diameter may diverge greatly. As an example, when the effective focal length of the fast axis collimator lens FAC is 0.3 mm, the distance from the fast axis collimator lens FAC to the beam waist of the collimated beam B is, for example, about 50 mm. In such an example, if the number of light source units 100 exceeds 10, the maximum optical path length greatly exceeds 50 mm. As a result, the divergence of some of the collimated beams B cannot be ignored, and it may be difficult to properly focus the light on an optical fiber with a small core size. For this reason, the number of collimated beams B to be combined by spatial beam combining is not simply better if it is more, but should be set within an appropriate range depending on the conditions.

The beam combiner 120 spatially combines multiple collimated beams B emitted from multiple light source units 100. In this embodiment, the collimated beams B emitted from each light source unit 100 have approximately the same wavelength (e.g., approximately 465 nm ± 10 nm), but their phases are not synchronized with each other. Therefore, the multiple collimated beams B are incoherently combined.

In this embodiment, the laser light source module 200 includes a support base (support) 140 that supports a plurality of light source units 100 such that the distances (heights) H from the reference plane Ref to the centers of the plurality of collimated beams B are different from one another. The support 140 has a mounting surface 140T having a plurality of steps, as shown in FIG. 7B. The center-to-center pitch S of the collimated beams B in the Y-axis (fast axis) direction corresponds to the size of the steps on the mounting surface 140T of the support 140. The center-to-center pitch S can be set within a range of, for example, 200 μm to 350 μm, but for ease of understanding, the steps are exaggerated and depicted large in FIGS. 7B, 7C, and 8. The light source units 100 are arranged at a center-to-center pitch P along the Z-axis direction, as shown in FIG. 7A.

The beam combiner 120 in this embodiment includes a mirror array having a plurality of mirrors M that respectively reflect a plurality of collimated beams B. Specifically, the mounting surface 140T of the support 140 supports a number of mirrors M corresponding to the number of light source units 100 at different heights (level positions). The position and orientation of each mirror M is aligned so as to reflect the corresponding collimated beam B and direct it toward the convergence optical system 160. In a typical example, the mirror M rotates the collimated beam B by 90 degrees around an axis parallel to the Y axis. Thus, the array of mirrors M in this embodiment propagates the reflected collimated beams B along a plane (YZ plane) perpendicular to the reference plane Ref. The mirror M may be fixed to a housing wall (not shown), or may be fixed via a component that can adjust the position and orientation of each mirror M. It is preferable that the reflecting surface of the mirror M is formed from a multilayer film that has a selectively high reflectance at the wavelength of the incident collimated beam B.

The center-to-center pitch S of the collimated beams B in the Y-axis direction is larger than the size of each mirror M in the Y-axis direction. In a typical example, the size of each mirror M in the Y-axis direction is set to be more than twice the Y-axis radius ω _y2 of each collimated beam B. Here, strictly speaking, ω _y2 is a value at the beam waist of the collimated beam B, but since the divergence half angle is sufficiently small, the Y-axis radius of the collimated beam B on the optical path in this example may be approximated to be approximately equal to ω _y2 . In this embodiment, S>2×ω _y2 holds. When _{ω y2} is, for example, 100 μm, S can be set to, for example, 300 μm (=2.5×ω _y2 ). The smaller the Y-axis radius ω _y2 of each collimated beam B, the smaller the center-to-center pitch S can be. Here, when a light source unit 100Q as shown in FIG. 3B is adopted instead of the light source unit 100 in this embodiment, the Y-axis radius ω _y2 of each collimated beam B reaches about 1 mm. Therefore, the size S of the step needs to be about 1 mm or more, and the beam diameter after spatial beam combination becomes too large. Moreover, such a problem becomes more prominent as the number of light source units 100 increases, for example, as shown in Fig. 8. However, this problem can be solved by using the light source unit 100 in this embodiment.

When determining the center-to-center pitch S of the collimated beams B in the Y-axis direction, there is no need to be concerned about physical interference between the light source units 100. In contrast, the center-to-center pitch P in the Z-axis direction is determined so that two adjacent light source units 100 do not physically interfere with each other.

The beam combiner 120 includes an optical system 160 that converges multiple collimated beams B that are respectively reflected by multiple mirrors M. In this embodiment, the optical system 160 optically couples the multiple collimated beams B to an optical fiber (not shown). Note that the reflecting surface of the mirror M does not need to be flat. The mirror M may perform at least a part of the convergence function of the optical system 160. The beam combiner 120 may also have optical components other than the mirror M, such as a filter having wavelength selectivity.

The configurations shown in Figures 7A, 7B, 7C, and 8 can be housed in a housing (not shown). The housing itself may be called a package, but compared to the semiconductor laser package described above, it has a large number of internal parts, and it is difficult to achieve a level of cleanliness sufficient to suppress the light dust collection effect and maintain airtightness.

Below, with reference to Figures 9A and 9B, an example configuration of an optical system 160 that combines multiple collimated beams B will be described. Figures 9A and 9B each show an example configuration of an optical system 160 that converges n collimated beams B arranged at a center-to-center pitch S along the fast axis (Y-axis) direction. The difference between the example in Figure 9A and the example in Figure 9B is the difference in the fast axis collimator lens FAC.

In the illustrated example, n is an odd number equal to or greater than 3, but n may be an even number. For simplicity, completely parallel light rays are illustrated as the collimated beam B in the drawings. However, as described above, the actual collimated beam B diverges at a predetermined divergence angle after reaching the minimum beam radius at the beam waist. If the total size of the n collimated beams B incident on the optical system 160 in the Y-axis direction is 2×R _TY , then the relationship 2×R _TY =S×(n−1)+2×ω _y2 holds. This relationship can be rewritten as R _TY =S×(n−1)/2+ω _y2 . Note that since the n collimated beams B are arranged in a straight line along the fast axis (Y-axis) direction, the total size of the n collimated beams B in the X-axis direction is equal to the size of each collimated beam B in the X-axis direction, 2×ω _x2 .

The optical system 160 in Figures 9A and 9B includes a slow axis convergent lens SAF and a fast axis convergent lens FAF, in that order from the side closest to the convergence point position (rear focal point) Q. These lenses are cylindrical lenses. Here, the Z axis (dash-dotted line) is assumed to coincide with the optical axis of the optical system 160. The fast axis convergent lens FAF converges all collimated beams B within a plane (YZ plane) including the Z axis and the fast axis direction (Y axis). The slow axis convergent lens SAF converges each collimated beam B within a plane (XZ plane perpendicular to the paper) including the Z axis and the slow axis direction (X axis).

The fast axis convergent lens FAF and the slow axis convergent lens SAF are arranged so that their rear focal points coincide with each other. The Y-axis radius _ωy3 of the combined laser beam at the convergence position Q has a value obtained by multiplying the Y-axis radius _ωy1 of the virtual light source by a magnification (EFL _FAF /EFL _FAC ). Here, EFL _FAC is the effective focal length of the fast axis collimator lens FAC, and EFL _FAF is the effective focal length of the fast axis convergent lens FAF.

As described above, in the embodiment of the present disclosure, when the effective focal length F2 of the imaging lens system 26 is made longer than the effective focal length F1 of the objective lens system 24, the lateral magnification of the image formed on the image plane 22 is F2/F1, so that the size of the image E' of the emitter region E on the image plane 22 is enlarged to F2/F1 times the size of the actual emitter region E. In addition, the faster axis direction divergence half angle (divergence half angle in the far field) θ _y1 of the beam emitted from the virtual light source becomes smaller as F2/F1 increases. When the fast axis direction divergence half angle (divergence half angle in the far field) θ _y1 of the beam emitted from the virtual light source becomes smaller, it is possible to reduce the numerical aperture of the fast axis collimator lens FAC and increase the effective focal length. In the configuration example of FIG. 9B, θ _y1 is relatively smaller than that in the configuration example of FIG. 9A. When a fast axis collimator lens FAC having a longer effective focal length EFL _FAC is adopted, the lateral magnification (EFL _FAF /EFL _FAC ) at the convergence position Q by the fast axis collimator lens FAC and the fast axis convergence lens FAF becomes smaller. In this way, when the lateral magnification at the convergence position Q becomes smaller, the tolerance of the positional deviation of the convergent beam spot with respect to the core of the optical fiber can be increased.

As an example, when ω _y1 =2.0 μm, EFL _FAC =0.3 mm, and EFL _FAF =10.0 mm, ω _y3 =66.7 μm. When ω _y1 =4.0 μm, EFL _FAC =0.6 mm, and EFL _FAF =10.0 mm, ω _y3 =66.7 μm. When the effective focal length of the slow axis collimator lens SAC is EFL _SAC and the effective focal length of the slow axis convergent lens SAF is EFL _SAF , the X-axis radius ω _x3 of the combined laser beam at the convergence position Q has a value obtained by multiplying the X-axis radius ω _x1 of the virtual light source by a magnification (EFL _SAF /EFL _SAC ). For example, when ω _x1 =80 μm, EFL _SAC =5.0 mm, and EFL _SAF =4.0 mm, ω _x3 =64 μm.

According to this embodiment, for example, the laser beam can be focused on a multimode optical fiber having a numerical aperture of about 0.2 and a core diameter of 100 μm. Since n laser beams are incoherently combined, the light intensity increases by n times. In the configuration of FIG. 3B, S and _RTY increase, so the converging optical system 160 needs to be enlarged.

Figures 10A, 10B, and 10C show schematic cross-sectional shapes of beams when 5, 9, and 9 x 2 rows of collimated beams B are incident on the fast axis focusing lens FAF. The shape of Figure 10C is obtained by arranging multiple light source units 100 in two rows as shown in Figure 11.

The arrangement of the light source units 100 is not limited to the above-mentioned example. FIG. 12 is a schematic top view showing yet another example. The beams output from the multiple light source units 100 may be arranged in three rows. Furthermore, the multiple light source units 100 and/or mirrors M do not need to be parallel to each other and may be tilted.

According to an embodiment of the present disclosure, since the LD 12 is housed in a package, the decrease in optical output of the LD 12 caused by the optical dust collection effect that may be caused by a high-power short-wavelength laser beam is suppressed, improving reliability. In addition, since it is possible to combine multiple collimated beams B with high spatial density, the optical output can be effectively increased. Furthermore, since the increase in the fast axis size of the collimated beam B is suppressed, the degree of freedom of the spatial arrangement of the light source unit 100 is increased, and it becomes possible to densely arrange a large number of collimated beams B. As a result, it becomes possible to combine a high-power laser beam with an optical fiber with high efficiency.

In the above embodiment, each package 10 contains one LD 12, but each package 10 may contain multiple LDs 12. In addition, in each embodiment, each LD 12 has one emitter region E, but one LD 12 may have multiple emitter regions E. In this way, even if multiple emitter regions E (emitter arrays) are located inside one package 10, the effects of the embodiments of the present disclosure can be obtained. That is, if a virtual light source is formed in free space by transferring the image of the emitter array located inside each package 10 to the image plane 22 of the first lens system 20, it becomes possible to design the second lens system 30 without being restricted by the package structure.

Direct Diode Laser Apparatus Next, an embodiment of a direct diode laser (DDL) apparatus according to the present disclosure will be described with reference to Fig. 13. Fig. 13 is a diagram showing a configuration example of a DDL apparatus 1000 in this embodiment.

The illustrated DDL device 1000 includes four laser light source modules 200, a processing head 400, and an optical transmission fiber 300 that connects the laser light source modules 200 to the processing head 400. The number of laser light source modules 200 may be one or more, and is not limited to four.

Each laser light source module 200 has a configuration similar to that described above. The number of LDs mounted on each laser light source module 200 is not particularly limited, and is determined according to the required optical output or irradiance. The wavelength of the laser light emitted from each LD can also be selected according to the material to be processed. For example, when processing copper, brass, aluminum, etc., an LD with a central wavelength in the range of 350 nm to 550 nm can be preferably used. The wavelength of the laser light emitted from each LD does not need to be the same, and laser lights with different central wavelengths may be superimposed. In addition, the effect of the present invention can be obtained even when using laser light with a central wavelength outside the range of 350 nm to 550 nm.

In the illustrated example, the optical fibers 220 extending from each of the multiple laser light source modules 200 are coupled to the optical transmission fiber 300 by the optical fiber coupler 230. The processing head 400 focuses and irradiates the laser beam emitted from the tip of the optical transmission fiber 300 on the object 500 by an optical system (not shown). When one DDL device 1000 has M laser light source modules 200 and each laser light source module 200 is equipped with N LDs, if the optical output of one LD is P watts, a laser beam with an optical output of P x N x M watts at most can be focused on the object 500. Here, N is an integer of 2 or more, and M is a positive integer. For example, if P = 10 watts, N = 9, and M = 12, an optical output of more than 1 kilowatt can be realized.

According to this embodiment, the LD in the laser light source module is housed in a semiconductor laser package, which suppresses the decrease in optical output caused by the optical dust collection effect and improves reliability. In addition, since a large number of collimated beams with small beam diameters can be packed into a limited space, a high optical output can be achieved with a small device and it is easy to couple to optical fibers.

Fiber Laser Device Next, an embodiment of a fiber laser device according to the present disclosure will be described with reference to Fig. 14. Fig. 14 is a diagram showing an example of the configuration of a fiber laser device 2000 in this embodiment.

The illustrated fiber laser device 2000 includes a laser light source module 200 that functions as an excitation light source, and a rare-earth doped optical fiber 600 that is excited by excitation light emitted from the laser light source module 200. In the illustrated example, the optical fiber 220 extending from each of the multiple laser light source modules 200 is coupled to the rare-earth doped optical fiber 600 by an optical fiber coupler 230. The rare-earth doped optical fiber 600 is sandwiched between a pair of fiber Bragg gratings that define a resonator. When the rare-earth doped optical fiber 600 is doped with Yb ions, a laser light source module 200 that generates excitation light with a wavelength of, for example, 915 nm is used. In the laser light source module 200 according to the embodiment of the present disclosure, since the LD is housed in a semiconductor laser package, as described above, it can exhibit excellent effects, especially when an LD that emits blue or green laser light is adopted. In addition, when using a rare-earth doped optical fiber 600 formed of fluoride glass doped with praseodymium (Pr), for example, it is possible to realize visible light laser oscillation by blue excitation light. The laser light source module 200 according to an embodiment of the present disclosure is useful as such an excitation light source.

The processing head 400 focuses the laser beam emitted from the tip of the rare earth-doped optical fiber 600 onto the target object 500 using an optical system (not shown).

Thus, in a non-limiting exemplary embodiment, the laser light source module of the present disclosure includes a plurality of laser light sources, each of which is a light source unit, and a beam combiner that spatially combines a plurality of collimated beams emitted from each of the plurality of laser light sources.

In one embodiment, a support is provided to support the multiple laser light sources so that the heights from a reference plane to the centers of the multiple collimated beams are different. The beam combiner includes a mirror array having multiple mirrors that reflect the multiple collimated beams, respectively, and propagates the reflected multiple collimated beams along a plane perpendicular to the reference plane, and an optical system that converges the multiple collimated beams reflected by the multiple mirrors.

In addition, in a non-limiting exemplary embodiment, the direct diode laser device of the present disclosure includes at least one of the laser light source modules, an optical fiber that propagates the laser beam emitted from the laser light source module and emits the laser beam, and a processing head coupled to the optical fiber that irradiates an object with the laser beam emitted from the optical fiber.

Furthermore, in a non-limiting exemplary embodiment, the fiber laser device of the present disclosure includes at least one of the laser light source modules and a rare-earth doped optical fiber excited by a laser beam emitted from the laser light source module.

Modified Example of Light Source Unit FIG. 15 is a diagram showing a modified example of the light source unit in the embodiment of the present disclosure. In the illustrated example, the light source unit 100X includes a sealed package 10, a first lens system 20, a second lens system 30, and an optical path correction element 32. The configurations of the package 10, the first lens system 20, and the second lens system 30 are similar to those of the configuration example in the above-mentioned embodiment. The light source unit 100X in this modified example differs from the light source unit 100 described above in that it includes an optical path correction element 32. The optical path correction element 32 is an element that changes the propagation direction of the collimated beam B emitted from the second lens system 30.

Figure 16 is a perspective view showing a schematic example in which the propagation direction of the collimated beam B is inclined with respect to the Z axis in the absence of the optical path correction element 32. The collimated beam B rotates from the positive direction of the Z axis to the positive direction of the X axis by an azimuth angle Φ in the XZ plane, and rotates from the XZ plane to the positive direction of the Y axis by an elevation angle Ω. The azimuth angle Φ and the elevation angle Ω can be generated mainly due to misalignment of the fast axis collimator lens FAC and the slow axis collimator lens SAC, respectively. For example, if the position of the fast axis collimator lens FAC in the Y axis direction is shifted by only 1 μm from the specified position, an elevation angle Ω of 0.1 degrees can be generated. Even if Ω = 0.1 degrees, if the optical path becomes long, the positional deviation of the collimated beam B becomes excessive. For example, in the laser light source module 200 described with reference to Figure 8, an angle deviation of about 0.1 to 1.0 degrees generated in the collimated beam B can adversely affect the focusing by the convergence optical system 160. Even if the position of the fast axis collimator lens FAC in the Y axis direction is at a predetermined position, if the position of the slow axis collimator lens SAC in the X axis direction deviates from the predetermined position, an azimuth angle Φ other than 0 degrees may occur.

The optical path correction element 32 in FIG. 15 makes it possible to correct the direction of the collimated beam B and bring the elevation angle Ω and azimuth angle Φ closer to 0 degrees. The optical path correction element 32 includes an optical element that refracts the collimated beam B, and a typical example of such an optical element is a wedge prism. Below, as an example, the configuration and operation of an optical path correction element 32 having a circular wedge prism will be described.

Figures 17A and 17B are respectively a perspective view and a cross-sectional view showing a wedge prism 34. Figure 17C shows a schematic diagram of how collimated beam B emitted from wedge prism 34 is steered to describe a conical surface by rotating wedge prism 34 in the direction of the arrow.

The wedge prism 34 is a prism in which an angle α other than 0 degrees is formed between the light entrance surface 34A and the light exit surface 34B. The angle α is, for example, in the range of 0.1 degrees to 1.0 degrees. The wedge prism 34 can be formed, for example, from optical glass with a refractive index of about 1.5. The collimated beam B incident on the light entrance surface 34A of the wedge prism 34 is refracted at the interface between air (refractive index is about 1.0) and the light entrance surface 34A, and at the interface between the light exit surface 34B and air. These two refractions make it possible to change the propagation direction (beam axis direction) of the collimated beam B by a predetermined angle. Therefore, if the propagation direction of the collimated beam B is changed by an appropriate angle in an appropriate direction using the wedge prism 34, the elevation angle Ω and azimuth angle Φ described above can be brought close to zero degrees.

Next, referring to FIG. 18, the refraction of light rays by the wedge prism 34 will be described. FIG. 18 shows a wedge prism 34 having a prism shape with a symmetrical cross section. The wedge prism 34 in FIG. 18 is placed on a horizontal plane 35. An incident light ray Bin is incident on the light entrance surface 34A at an angle θ0 with respect to the axis Ax of the wedge prism 34. The angle of incidence of the incident light ray Bin is determined by the angle θ1 with respect to the normal N1 of the light entrance surface 34A. Due to the symmetry of the wedge prism 34, an exit light ray Bout is exited from the light exit surface 34B at an angle θ0 with respect to the axis Ax of the wedge prism 34. The exit angle of the exit light ray Bout is determined by the angle θ1 with respect to the normal N2 of the light exit surface 34B.

Figure 19 shows the state in which such a wedge prism 34 and the rays Bin and Bout are rotated by an angle θ0 around the X-axis. With this rotation, the outgoing ray Bout becomes parallel to the Z-axis. Also, the angle that the incoming ray Bin forms with the horizontal plane 35 is equal to 2 × θ0.

As is clear from the above, when the incident light ray Bin propagates in a direction inclined by an angle of 2 × θ0 with respect to the Z axis, i.e., when the elevation angle Ω = 2 × θ0, it is possible to make the outgoing light ray Bout parallel to the Z axis by using a wedge prism 34 rotated by an angle of θ0 around the X axis.

As described above, the angle at which the incident light ray Bin is inclined with respect to the Z axis (elevation angle Ω) may vary depending on the misalignment of the fast axis collimator lens FAC. Therefore, the inclination angle θ0 of the wedge prism 34 required to correct the optical path may vary depending on the individual light source unit 100X.

As mentioned above, it may be necessary to correct the azimuth angle Φ. In such cases, as shown in FIG. 17C, by rotating the wedge prism 34 around the Z axis, it is possible to make both the elevation angle Ω and the azimuth angle Φ sufficiently small. Normally, the elevation angle Ω and the azimuth angle Φ are both small, less than 1.0 degree, so there is no need to rotate the wedge prism 34 by a large angle, as shown in FIG. 17C. Also, since the azimuth angle Φ is usually smaller than the elevation angle Ω, it is possible to correct the azimuth angle Φ by simply rotating the wedge prism 34 slightly after correcting the elevation angle Ω to zero.

In the embodiment of the present disclosure, after the alignment of the fast axis collimator lens FAC and the slow axis collimator lens SAC is completed, when adjusting the propagation direction of the collimated beam B, a wedge prism 34 is placed on the optical path and its tilt angle θ0 is adjusted. Specifically, a plurality of wedge prisms 34 tilted at different angles θ0 can be prepared in advance, and the wedge prism 34 that minimizes the elevation angle Ω can be selected from among them. Then, the wedge prism 34 selected in this manner can be rotated around the Z axis to minimize the azimuth angle Φ as well. Then, the position and orientation of the wedge prism 34 can be fixed using an adhesive or a hardening resin. The number of wedge prisms 34 that can be prepared in advance can be, for example, seven, and the tilt angle θ0 can be, for example, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, or 1.0 degrees.

Figure 20 is a diagram showing an example of the configuration of an optical path correction element 32 suitable for the above correction work. Figure 20 shows the front of the optical path correction element 32 on the left side, and a cross-section of the optical path correction element 32 on the right side. The optical path correction element 32 in Figure 20 has a cylinder (cylindrical holder) 36 and a circular wedge prism 34 fixed inside the cylinder 36 at an inclination angle θ0. Such an optical path correction element 32 can be fixed to a support base 38 as shown in Figure 21. This support base 38 has a recess that receives a part of the wedge prism 34 surrounded by the cylinder 36. In the example of Figure 21, this recess has a cross-sectional shape that is roughly a V-shaped groove. Such a V-shaped groove makes it easy to rotate the above-mentioned wedge prism 34 around the Z axis.

Figure 22 is a perspective view showing an example of the configuration of a laser light source module 200 including multiple light source units 100X. This laser light source module 200 differs from the laser light source module 200 in Figure 8 in that the light source unit 100X has an optical path correction element 32, but in other respects has a common configuration.

In the example shown in FIG. 22, each light source unit 100X has an optical path correction element 32, but the embodiment of the present disclosure is not limited to such an example. A light source unit 100X that does not require optical path correction does not need to have an optical path correction element 32. When multiple light source units 100X each have an optical path correction element 32, the magnitude of the inclination angle θ0 of each optical path correction element 32 can differ from one another depending on the amount of correction required for each.

For simplicity, detailed description is omitted in FIG. 22, but the mounting surface 140T of the support 140 has a recess for receiving a part of the wedge prism 34 in the optical path correction element 32. The outer periphery of the wedge prism 34 may be surrounded by a member such as a cylinder, if necessary. In the example of FIG. 22, each optical path correction element 32 is fixed to the support 140.

With the laser light source module 200 in FIG. 22, the collimated beam B is properly incident on the converging optical system 160, making it possible to achieve more efficient optical coupling to an optical fiber (not shown).

Note that, although the laser diode of the light source unit in each of the above embodiments is an edge-emitting laser diode, the embodiment of the present disclosure is not limited to this example. The laser diode of the light source unit is not limited to an edge-emitting laser diode, and may be a surface-emitting laser diode such as a VCSEL (Vertical-Cavity Surface-Emitting Laser). When a surface-emitting laser diode is used, the emitter region is perpendicular to the main surface of the semiconductor substrate of the laser diode, and the optical axis of the laser beam emitted from the emitter region is perpendicular to the main surface of the semiconductor substrate. When a surface-emitting laser diode is used, the laser light emitted from the emitter region may have a beam shape that is symmetrical around the optical axis. In that case, the second lens system 30 that converts the laser light that has passed through the image plane from the first lens system 20 into a collimated beam or a convergent beam and emits it does not need to have a fast axis collimator lens and a slow axis collimator lens, and may be realized by a single collimator lens.

The light source unit of the present disclosure can be used in various applications where it is required to reduce the fast axis size of a collimated or convergent beam. In particular, it can be used to combine multiple laser beams to realize a high-power laser beam. In addition, the laser light source module and direct diode laser device of the present disclosure can be used in industrial fields where a high-power laser light source is required, such as cutting various materials, drilling holes, local heat treatment, surface treatment, metal welding, 3D printing, etc. Furthermore, the laser light source module of the present disclosure can be used for applications other than DDL devices, such as an excitation light source for a fiber laser device.

10: Semiconductor laser package, 12: LD, 14: Window member, 20: First lens system, 22: Image surface, 24: Objective lens system, 26: Imaging lens system, 30: Second lens system, 100: Light source unit, 120: Beam combiner, 140: Support, 160: Converging optical system, 300: Optical transmission fiber, 400: Processing head, 1000: Direct diode laser (DDL) device, B: Beam, M: Mirror, FAC: Fast axis collimator lens, SAC: Slow axis collimator lens, FAF: Fast axis convergent lens, SAF: Slow axis convergent lens

Claims (10)

A plurality of light source units;
a converging optical system into which collimated beams or converging beams emitted from the plurality of light source units are incident;
A light source module comprising:
Each of the plurality of light source units is
a sealed semiconductor laser package including a laser diode having an emitter region for emitting laser light and a window member for transmitting the laser light;
a first lens system that transmits the laser light that has passed through the window member;
a second lens system that converts the laser light that has passed through the first lens system into the collimated beam or the convergent beam and emits the beam;
a wedge prism that changes both the elevation angle and the azimuth angle of the propagation direction of the collimated or convergent beam emitted from the second lens system;
Equipped with
A light source module, wherein the inclination angle of at least one of the plurality of wedge prisms is different from the inclination angles of the other wedge prisms. A plurality of light source units;
a converging optical system into which collimated beams or converging beams emitted from the plurality of light source units are incident;
A light source module comprising:
Each of the plurality of light source units is
a sealed semiconductor laser package including a laser diode having an emitter region for emitting laser light and a window member for transmitting the laser light;
a first lens system that transmits the laser light that has passed through the window member;
a second lens system that converts the laser light that has passed through the first lens system into the collimated beam or the convergent beam and emits the beam;
Equipped with
A light source module, wherein at least one of the plurality of light source units is provided with a wedge prism that changes both the elevation angle and the azimuth angle of the propagation direction of the collimated beam or convergent beam emitted from the second lens system, and light source units other than the at least one light source unit are not provided with the wedge prism. the first lens system receives the laser light that has passed through the window member and forms an image of the emitter region on an image plane located between the first lens system and the second lens system;
3. The light source module according to claim 1 , wherein a distance from the image plane to the second lens system is shorter than a distance from the emitter region of the laser diode to an outer surface of the window member. The light source module according to claim 1 , wherein the first lens system includes an objective lens system and an imaging lens system. the first lens system includes an objective lens system and an imaging lens system;
the emitter region of the laser diode is located at a front focal point of the objective lens system;
the image plane is located at the rear focal point of the imaging lens system;
The light source module according to claim 3 , wherein an effective focal length of the imaging lens system is equal to or greater than an effective focal length of the objective lens system. The light source module according to claim 4 , wherein the objective lens system and the imaging lens system are each a lens combination. the second lens system includes a fast axis collimator lens and a slow axis collimator lens arranged in this order from the image plane side,
6. The light source module according to claim 3 , wherein the distance from the image plane to the second lens system is defined by the distance from the image plane to the fast axis collimator lens. 8. The light source module of claim 3, 5, or 7 , wherein the distance from the image plane to the second lens system is 1.0 millimeter or less. the second lens system includes a fast axis collimator lens and a slow axis collimator lens arranged in this order from the image plane side,
the effective focal length of the fast axis collimator lens is 1.0 millimeters or less;
9. The light source module of claim 3, 5, 7, or 8 , wherein the fast axis size of the collimated beam is 1.0 millimeter or less. The light source module according to claim 1 , further comprising a base for supporting the wedge prism, the base having a recess for receiving a portion of the wedge prism.

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