JP7748207B2 - Light-emitting device - Google Patents

Description

This disclosure relates to a light-emitting device.

Light-emitting devices equipped with multiple semiconductor laser packages are known (see, for example, Patent Document 1). The light-emitting device described in Patent Document 1 includes multiple CAN packages mounted on a mounting substrate, and attempts to focus the laser light from the multiple CAN packages using a lens array.

Japanese Patent Application Laid-Open No. 2012-215633

Each of the multiple CAN packages contains a semiconductor laser chip. Light-emitting devices are required to achieve higher output, and the current supplied to each semiconductor laser chip tends to increase. This increases the amount of heat generated by each semiconductor laser chip, making it necessary to ensure a heat dissipation path from each semiconductor laser chip. However, in the light-emitting device described in Patent Document 1, multiple holes must be formed in the mounting substrate to mount the multiple CAN packages. This reduces the heat dissipation path in the mounting substrate compared to when no holes are formed in the mounting substrate, thereby reducing the heat dissipation characteristics from each semiconductor laser chip via the mounting substrate. This can limit the amount of current that can be supplied to the semiconductor laser chip.

The present disclosure aims to solve these problems by providing a light-emitting device that can improve the heat dissipation characteristics of a semiconductor laser chip.

In order to solve the above problems, one aspect of the light-emitting device disclosed herein comprises a base having a principal surface, a plurality of semiconductor laser chips mounted on the principal surface and having optical axes parallel to the principal surface, a plurality of mirrors each having a reflective surface that reflects light emitted from the emission points of each of the plurality of semiconductor laser chips, and an optical element having a plurality of lens portions that receive the light reflected from the reflective surfaces of each of the plurality of mirrors, wherein, in a planar view of the principal surface, the distance between the center position of the emitted light on the reflective surface and the center position of a lens portion of the plurality of lens portions that corresponds to the reflective surface increases as the distance between the center position of the emitted light and the center position of a lens region in which the plurality of lens portions are arranged increases, and output light from each of the plurality of lens portions is irradiated within a predetermined surface region having an area smaller than that of the lens region.

This disclosure provides a light-emitting device that can improve the heat dissipation characteristics of a semiconductor laser chip.

FIG. 1 is a plan view of a light emitting device according to a first embodiment. FIG. 2 is a cross-sectional view of the light emitting device according to the first embodiment. FIG. 3 is a plan view showing the light emitting device according to the first embodiment with the optical members removed. FIG. 4 is a cross-sectional view showing the configuration of the semiconductor laser chip, the submount, and the mirror according to the first embodiment. FIG. 5 is a cross-sectional view illustrating the optical path in the light emitting device according to the first embodiment. FIG. 6 is a diagram showing the positional relationship between a plurality of mirrors and a plurality of lens portions in the light emitting device according to the first embodiment. FIG. 7 is a plan view showing a state in which the optical members of the light emitting device according to the second embodiment have been removed. FIG. 8 is a cross-sectional view of a light emitting device according to the second embodiment. FIG. 9 is a plan view showing a state in which the optical members of the light emitting device according to the third embodiment have been removed. FIG. 10 is a cross-sectional view of a light emitting device according to the third embodiment. FIG. 11 is a plan view showing a state in which the optical members of the light emitting device according to the fourth embodiment have been removed. FIG. 12 is a cross-sectional view of a light emitting device according to the fourth embodiment. FIG. 13 is a plan view showing a state in which the optical members of the light emitting device according to the fifth embodiment have been removed. FIG. 14 is a cross-sectional view of a light emitting device according to the fifth embodiment. FIG. 15 is a plan view showing a state in which the optical members of the light emitting device according to the sixth embodiment have been removed. FIG. 16 is a plan view showing a state in which the optical members of the light emitting device according to the seventh embodiment are removed. FIG. 17 is a plan view showing a state in which the optical members of the light emitting device according to the eighth embodiment are removed. FIG. 18 is a schematic cross-sectional view of a light emitting device according to the eighth embodiment. FIG. 19 is a diagram showing a far-field pattern obtained by superimposing all output light profiles in a predetermined surface area of the light emitting device according to the eighth embodiment.

Embodiments of the present disclosure will be described below with reference to the drawings. Note that each embodiment described below represents a specific example of the present disclosure. Therefore, the numerical values, shapes, materials, components, and the arrangement and connection of the components shown in the following embodiments are merely examples and are not intended to limit the present disclosure.

Furthermore, each figure is a schematic diagram and is not necessarily an exact illustration. Therefore, the scale and other details do not necessarily match between the figures. Furthermore, in each figure, the same reference numerals are used to designate substantially identical components, and redundant explanations will be omitted or simplified.

In addition, in this specification, the terms "above" and "below" do not refer to the upward direction (vertically upward) and downward direction (vertically downward) in an absolute spatial sense, but are used as terms defined by a relative positional relationship based on the stacking order in the stacked configuration. Furthermore, the terms "above" and "below" apply not only to cases where two components are arranged with a gap between them and another component exists between them, but also to cases where two components are arranged in contact with each other.

(Embodiment 1)
A light emitting device according to a first embodiment will be described.

[1-1. Overall configuration]
First, the overall configuration of the light emitting device according to the present embodiment will be described with reference to Figures 1 to 3. Figures 1 and 2 are a plan view and a cross-sectional view, respectively, of a light emitting device 10 according to the present embodiment. Figure 2 shows a cross section taken along line II-II in Figure 1. Figure 3 is a plan view showing the light emitting device 10 according to the present embodiment with the optical member 40 removed. Each figure also shows an X-axis, a Y-axis, and a Z-axis, which are orthogonal to one another.

As shown in FIG. 2, the light-emitting device 10 according to this embodiment is a device that irradiates light onto a predetermined surface area (not shown) located away from the light-emitting device 10 in the Z direction, and includes a base 20, multiple semiconductor laser chips 60, multiple mirrors 70, and an optical member 40. In this embodiment, the light-emitting device 10 further includes a frame member 30 and multiple submounts 50.

The base 20 shown in Figures 1 to 3 is a member having a main surface 21 on which multiple semiconductor laser chips 60 are mounted. In this embodiment, the base 20 is a substrate having a substantially rectangular plate shape. The base 20 is made of a material with high thermal conductivity, and also functions as a heat dissipation member that dissipates heat generated by the multiple semiconductor laser chips 60.

The base 20 may be made of, for example, a metal, ceramic, glass, or resin material. To efficiently dissipate the heat generated by the semiconductor laser chip 60 through the base 20, the base 20 should be made of a material with high thermal conductivity, such as a metal. Metal materials with high thermal conductivity that are practical for the base 20 include, for example, Cu or Al. In this embodiment, the base 20 is a Cu substrate made of Cu.

In addition, a structure for fixing the base 20 may be formed on the outer portion of the frame member 30 of the base 20. For example, the base 20 may have a through hole or the like formed therein.

The frame member 30 shown in Figures 2 and 3 is an annular member that surrounds multiple semiconductor laser chips 60 and multiple mirrors 70. The frame member 30 is erected on the main surface 21 of the base 20 and functions as part of a container that houses multiple semiconductor laser chips 60 and other components. The frame member 30 also functions to support the optical member 40. The frame member 30 is sandwiched between the base 20 and the optical member 40. Multiple semiconductor laser chips 60 and multiple mirrors 70 are housed in the space surrounded by the frame member 30, the base 20, and the optical member 40. Although not shown, the frame member 30 may have current terminals for supplying current to the multiple semiconductor laser chips 60. The frame member 30 is formed, for example, from a metal such as Fe or an alloy. If the frame member 30 has a current terminal, an insulating member is arranged around the current terminal.

Each of the multiple semiconductor laser chips 60 shown in Figures 2 and 3 is mounted on the main surface 21 of the base 20 and is a semiconductor light-emitting element having an optical axis parallel to the main surface 21. In this embodiment, each of the 20 semiconductor laser chips 60 is mounted on the main surface 21 via a submount 50. As shown in Figure 3, the multiple semiconductor laser chips 60 are arranged in a matrix in the X-axis and Y-axis directions. Each of the multiple semiconductor laser chips 60 is positioned corresponding to each of the multiple lens portions 43 of the optical member 40.

All of the multiple semiconductor laser chips 60 have the same configuration. The configuration of the semiconductor laser chip 60 will now be described with reference to Figure 4. Figure 4 is a cross-sectional view showing the configuration of the semiconductor laser chip 60, submount 50, and mirror 70 according to this embodiment. Figure 4 is an enlarged view of a portion of Figure 2. As shown in Figure 4, each of the multiple semiconductor laser chips 60 has an emission point E1 from which emitted laser light L1 is emitted. The optical axis of the emitted light L1 is parallel to the main surface 21 of the base 20. Here, the emitted light L1 is indicated by an arrow, but this arrow indicates the optical axis of the emitted light L1; in reality, the emitted light L1 is a diverging light with a width.

The semiconductor laser chip 60 is elongated, with its longitudinal direction aligned with the optical axis direction of the emitted light L1 (i.e., the resonance direction). As an example, the length of the semiconductor laser chip 60 in the optical axis direction is 1200 μm, but is not limited to this.

The semiconductor laser chip 60 is mounted on the upper surface of the submount 50. Specifically, the semiconductor laser chip 60 is mounted on wiring electrodes (not shown) on the submount 50. In this embodiment, the semiconductor laser chip 60 is mounted on the submount 50 using junction-down mounting. However, the mounting configuration of the semiconductor laser chip 60 is not limited to this, and it may also be mounted on the submount 50 using junction-up mounting.

The semiconductor laser chip 60 is mounted so that the end face where the emission point E1 is located protrudes from the end face on the light emission side of the submount 50. In other words, the semiconductor laser chip 60 protrudes from the end face of the submount 50, and the emission point E1 of the semiconductor laser chip 60 is located on the light emission side of the semiconductor laser chip 60 relative to the end face on the light emission side of the submount 50. The amount of protrusion of the semiconductor laser chip 60 (i.e., the distance from the end face on the light emission side of the submount 50 to the emission point E1 of the semiconductor laser chip 60) is, for example, 5 μm or more and 20 μm or less, but is not limited to this. In this embodiment, the amount of protrusion of the semiconductor laser chip 60 is 10 μm.

Each of the multiple submounts 50 shown in Figures 2 to 4 is mounted on the main surface 21 of the base 20 and is a member that supports the semiconductor laser chip 60. In this embodiment, the multiple submounts 50 all have the same configuration. As shown in Figure 4, the submount 50 has a mounting surface 51 that faces the main surface 21 of the base 20, and an attachment surface 52 located on the back side of the mounting surface 51 and on which the semiconductor laser chip 60 is attached. In other words, the submount 50 is located between the base 20 and the semiconductor laser chip 60.

The light-emitting device 10 has the same number of submounts 50 as the semiconductor laser chips 60. In this embodiment, the 20 submounts 50 correspond one-to-one to the 20 semiconductor laser chips 60.

The submount 50 also functions as a heat sink to dissipate heat generated by the semiconductor laser chip 60. Therefore, the submount 50 may be made of either a conductive or insulating material, but is preferably made of a material with high thermal conductivity. The thermal conductivity of the submount 50 is preferably 150 W/(m·K) or higher. For example, the submount 50 may be made of ceramics such as aluminum nitride (AlN) or polycrystalline silicon carbide (SiC), metal materials such as Cu, or diamond, such as single crystal diamond or polycrystalline diamond. In this embodiment, the submount 50 is made of AlN. The shape of the submount 50 is, for example, a rectangular plate-like cuboid, but is not limited to this.

The submount 50 is bonded to the main surface 21 of the base 20 using, for example, a metal bonding material. In other words, the submount 50 is mounted without forming fixing holes or the like in the base 20. This allows the submount 50 to be mounted on the base 20 without reducing the heat dissipation characteristics of the base 20.

As shown in FIG. 4, each of the multiple mirrors 70 is an element having a reflective surface 71 that reflects the emitted light L1 from the emission point E1 of each of the multiple semiconductor laser chips 60. All of the multiple mirrors 70 have the same configuration. As shown in FIG. 3, the multiple mirrors 70 are arranged in a matrix in the X-axis direction and the Y-axis direction. Each of the multiple mirrors 70 is arranged at a position corresponding to each of the multiple lens portions 43 of the optical element 40. As shown in FIG. 4, the reflective surface 71 is a flat mirror arranged opposite the emission point E1 of the semiconductor laser chip 60. In this embodiment, the reflective surface 71 is inclined at 45° with respect to the direction of the emitted light L1. In other words, the direction perpendicular to the reflective surface 71 is inclined at 45° with respect to the direction of the emitted light L1. The emitted light L1 is reflected at the reflective surface 71 and propagates as reflected light L2 from the mirror 70 toward the optical element 40. In this embodiment, the emitted light L1 is incident on the center position 71C of the reflecting surface 71 shown in Figure 2. Here, the center position 71C of the reflecting surface 71 is defined as the center of gravity of the reflecting surface 71. Furthermore, although the reflected light L2 is indicated by an arrow, this arrow indicates the optical axis of the reflected light L2; in reality, the reflected light L2 is divergent light with a width.

The mirrors 70 are mounted on the main surface 21 of the base 20. As shown in FIG. 3, the light-emitting device 10 includes the same number of mirrors 70 as the semiconductor laser chips 60. In this embodiment, the 20 mirrors 70 correspond one-to-one with the 20 semiconductor laser chips 60. Here, the positional relationship between the mirrors 70 and the semiconductor laser chips 60 is the same for all sets. In other words, the distance from the emission point E1 of the semiconductor laser chip 60 to the center position C1 of the emitted light L1 on the reflecting surface 71 is the same for all sets, and the height of the optical axis of the emitted light L1 from the semiconductor laser chip 60 from the main surface 21 and the height of the reflecting surface 71 from the main surface 21 are all the same.

The optical element 40 shown in Figures 1, 2, and 4 is a translucent plate-like element having multiple lens portions 43. The optical element 40 is supported by the frame element 30 and also functions as a lid for the area surrounded by the frame element 30. As shown in Figure 4, each of the multiple lens portions 43 receives reflected light L2 from the reflecting surface 71 of each of the multiple mirrors 70. In this embodiment, all of the multiple lens portions 43 have the same focal length. The lens portions 43 are, for example, spherical lenses. The surface of the lens portion 43 facing the reflecting surface 71 is flat, and the surface behind (i.e., the outside) of the flat surface has a spherical convex shape. In other words, the lens portions 43 are convex lenses. The optical element 40 has the same number of lens portions 43 as the semiconductor laser chips 60 and mirrors 70. The multiple lens portions 43 are arranged in a matrix in the X-axis and Y-axis directions, as shown in Figure 3. Each of the multiple lens portions 43 is positioned corresponding to each of the multiple mirrors 70. In this embodiment, the 20 lens units 43 correspond one-to-one to the 20 mirrors 70. The optical member 40 is made of a translucent material such as glass.

As shown in FIG. 1, the optical element 40 has a lens region 44 in which multiple lens portions 43 are arranged. The lens region 44 is, for example, the region surrounded by an envelope 44E of the multiple lens portions 43. The center position 44C of the lens region 44 is the center of gravity of the lens region 44.

[1-2. Optical path]
Next, the optical path in the light emitting device 10 according to this embodiment will be described mainly with reference to Figs. 5 and 6. Fig. 5 is a cross-sectional view illustrating the optical path in the light emitting device 10 according to this embodiment. Fig. 5 shows a partially enlarged view of the same cross section as Fig. 2, and the optical path. Fig. 6 is a diagram showing the positional relationship between the plurality of mirrors 70 and the plurality of lens units 43 in the light emitting device 10 according to this embodiment. Fig. 6 shows a plan view of the main surface 21 of the base 20 in a plan view. In Fig. 6, the outlines of the plurality of lens units 43 are also shown by dashed lines.

As shown in FIG. 5, emitted light L1, which has an optical axis parallel to the principal surface 21 and is emitted from the semiconductor laser chip 60, is reflected by the reflecting surface 71 of the mirror 70 and propagates toward the lens unit 43 as reflected light L2. Here, the direction of the optical axis of the reflected light L2 is parallel to the direction perpendicular to the principal surface 21 of the base 20. The reflected light L2 is incident on the lens unit 43. The direction of the optical axis of the lens unit 43 is parallel to the direction perpendicular to the principal surface 21 of the base 20. The lens unit 43 converts the reflected light L2, which is divergent light, into a parallel or convergent state and outputs it from the light-emitting device 10 as output light L3. Here, the optical axis of the reflected light L2 does not pass through the center of the lens unit 43 and is parallel to the optical axis of the lens unit 43, so the output light L3 from the lens unit 43 is refracted in the direction of the optical axis of the lens unit 43. Note that output light L3 is indicated by an arrow, but this arrow indicates the optical axis of output light L3; in reality, output light L3 is light with a width.

5 and 6, in a plan view of the principal surface 21, the distance (Dc) in the X-axis direction between the center position C1 of the emitted light L1 on the reflecting surface 71 and the center position 43C of the lens portion 43 corresponding to the reflecting surface 71 increases as the distance (De) in the X-axis direction between the center position C1 of the emitted light L1 and the center position 44C of the lens region 44 in which the multiple lens portions 43 are arranged increases. Here, the center position C1 of the emitted light L1 on the reflecting surface 71 is defined as the center of gravity of the beam profile of the emitted light L1 or the position where the intensity of the emitted light L1 is maximized. Furthermore, the center position 43C of the lens portion 43 is defined as the position through which the optical axis of the lens portion 43 (the dashed line shown in FIG. 5) passes in a plan view of the principal surface 21. Although no auxiliary lines are shown in the figures, the center position C1 of the emitted light L1 on the reflecting surface 71 also changes in the Y-axis direction.

In addition, in this embodiment, the distance in the X-axis direction between the center position 71C of the reflecting surface 71 in a plan view of the main surface 21 and the center position 43C of the lens portion 43 among the multiple lens portions 43 that corresponds to the reflecting surface 71 increases as the distance in the X-axis direction between the center position 71C of the reflecting surface 71 and the center position 44C of the lens region 44 increases. In this embodiment, the center position C1 of the emitted light L1 on the reflecting surface 71 coincides with the center position 71C of the reflecting surface 71. Note that the center position C1 of the emitted light L1 on the reflecting surface 71 does not have to coincide with the center position 71C of the reflecting surface 71.

With the above configuration, as shown in Figure 5, as the distance between the center position C1 of the emitted light L1 and the center position 44C of the lens region 44 increases, the refraction angle of the optical axis of the reflected light L2 at the lens section 43 increases.

Therefore, output light L3 from each of the multiple lens portions 43 is irradiated onto the interior of the predetermined surface area A1, which has an area smaller than that of the lens area 44. In this way, with the light-emitting device 10 according to this embodiment, multiple output light beams L3 can be focused onto the predetermined surface area A1, which has an area smaller than that of the lens area 44, without placing a focusing lens between the optical member 40 and the predetermined surface area A1.

Here, by making Dc proportional to De, the optical axes of all output light beams L3 can be converged to one location. The center position 71C of the reflecting surface 71 also changes in the Y-axis direction. As shown in Figure 6, the center position 43C of the lens portion 43 is located on the line segment connecting the center position C1 of the output light beam L1 and the center position 44C of the lens region 44, but it does not necessarily have to be exactly on that line segment. Furthermore, while the optical axis of each output light beam L3 generally points toward the center position of the lens region 44 in a planar view, it does not necessarily have to point exactly toward the center position. Furthermore, by making the distance from the emission point E1 of the semiconductor laser chip 60 to the center position C1 of the output light beam L1 on the reflecting surface 71 the same for all beams, the distance from the emission point E1 of the semiconductor laser chip 60 to the lens portion 43 is also the same for all beams, minimizing the impact of changes in the positions of the semiconductor laser chip 60 and mirror 70 on the convergence of the output light beam L3. Furthermore, since the center position C1 of the emitted light L1 on the reflecting surface 71 coincides with the center position 71C of the reflecting surface 71, the emitted light L1 can be efficiently reflected by the mirror 70.

Furthermore, in this embodiment, by making the output light L3 a focused beam focused by the lens unit 43, the output light L3 can be focused on a predetermined surface area A1 that is smaller than when the output light L3 is not a focused beam. In other words, the area of the far-field pattern formed by multiple output light beams L3 can be reduced. Therefore, the light density in the predetermined surface area A1 can be further increased.

[1-3. Effects]
Next, the effects of the light emitting device 10 according to this embodiment will be described. As shown in FIG. 2 , the light emitting device 10 according to this embodiment includes a plurality of semiconductor laser chips 60. Each of the plurality of semiconductor laser chips 60 is mounted on the main surface 21 of the base 20 and has an optical axis parallel to the main surface 21. The semiconductor laser chip 60 is mounted on the main surface 21 via a submount 50. Here, the submount 50 can be mounted on the base 20 without forming a fixing hole or the like in the base 20, so the submount 50 can be mounted on the base 20 without degrading the heat dissipation characteristics of the base 20. Furthermore, the semiconductor laser chip 60 can be mounted on the base 20 only via the submount 50. In other words, the semiconductor laser chip 60 can be mounted in close proximity to the main surface 21 of the base 20. Therefore, by using a submount 50 with high thermal conductivity, the heat dissipation characteristics from the semiconductor laser chip 60 to the base 20 can be improved compared to when a CAN package or the like including the semiconductor laser chip 60 is mounted on the base 20. As described above, according to this embodiment, it is possible to realize a light emitting device 10 that can improve the heat dissipation characteristics of the plurality of semiconductor laser chips 60 .

[1-4. Manufacturing method]
Next, a method for manufacturing the light emitting device 10 according to the present embodiment will be described.

First, a semiconductor laser chip 60 is mounted on each of the multiple submounts 50. Specifically, the semiconductor laser chip 60 is bonded to the mounting surface 52 of the submount 50 using a metallic bonding material. A Zener diode for maintaining a constant voltage supplied to the semiconductor laser chip 60 may also be bonded to the mounting surface 52 of the submount 50. Examples of metallic bonding materials that can be used include solder materials such as AuSn and AuGeNi, and bonding materials containing fine particles of Cu, Al, Au, Ag, and alloys thereof.

Next, the submount 50 with the semiconductor laser chip 60 mounted thereon is mounted on the main surface 21 of the base 20. Specifically, the submount 50 is bonded to the main surface 21 of the base 20 using a metallic bonding material. Examples of metallic bonding materials that can be used include solder materials such as AuSn and AuGeNi, and bonding materials containing fine particles of Cu, Al, Au, Ag, and alloys thereof. When bonding the submount 50 to the main surface 21, the base 20, submount 50, and metallic bonding material are heated, for example, to 200°C for approximately 30 minutes. The metallic bonding material is then cooled to harden it. This allows the submount 50 to be mounted on the base 20. The frame member 30 is mounted on the base 20 in advance. Alternatively, the frame member 30 may be formed integrally with the base 20.

Next, wires for supplying current to the semiconductor laser chip 60 are connected to the semiconductor laser chip 60. Specifically, for example, a terminal provided on the frame member 30 is connected to the semiconductor laser chip 60 by a wire, and two adjacent semiconductor laser chips 60 are connected in series by a wire. This makes it possible to supply current from outside the light-emitting device 10. There are no particular restrictions on the material of the wire as long as it is conductive, but examples include Au, Ag, and Cu.

Next, the mirror 70 is mounted on the main surface 21 of the base 20. Specifically, the mirror 70 is bonded to the main surface 21 of the base 20 using a metallic bonding material. Before the metallic bonding material is cured, active alignment of the mirror 70 is performed. That is, a current is supplied to the semiconductor laser chip 60 to emit the emitted light L1, and the position of the emitted light L1 on the reflecting surface 71 of the mirror 70 and the position of the reflected light L2 from the mirror 70 are checked while adjusting the position of the mirror 70 on the main surface 21. After alignment of the mirror 70 is complete, the metallic bonding material is cured in the same manner as when mounting the submount 50. This allows the mirror 70 to be mounted on the base 20.

Next, the optical element 40 is mounted on the base 20. In this embodiment, the optical element 40 is mounted on the base 20 via the frame element 30. Specifically, the optical element 40 is bonded to the frame element 30 using an adhesive or the like. A UV-curable adhesive, for example, can be used as the adhesive. First, the UV-curable adhesive is applied to at least one of the frame element 30 and the optical element 40 to temporarily fix the optical element 40. Next, active alignment of the position of the optical element 40 in the X, Y, and Z axis directions is performed. After alignment of the optical element 40 is complete, the UV-curable adhesive is irradiated with UV light to cure the UV-curable adhesive. This allows the optical element 40 to be mounted on the base 20.

As described above, the light emitting device 10 according to this embodiment can be manufactured. Note that a light-transmitting member such as a cover glass may be attached between the optical member 40 and the frame member 30. Furthermore, the multiple lens portions 43 of the optical member 40 may be configured to be separable from the optical member 40. In this case, the multiple lens portions 43 may be individually active aligned.

(Embodiment 2)
A light emitting device according to embodiment 2 will be described. In the light emitting device 10 according to embodiment 1, the positions of the mirror 70 and the semiconductor laser chip 60 relative to the lens portion 43 are changed in plan view while maintaining their positional relationship relative to the lens portion 43, depending on the distance from the center position 44C of the lens region 44 to the center position 71C of the reflecting surface 71 of the mirror 70. The light emitting device according to this embodiment differs from the light emitting device 10 according to embodiment 1 in that the positions of the mirror 70 and the semiconductor laser chip 60 relative to the lens portion 43 are not changed, but the height of the optical axis of the emitted light L1 from the main surface 21 of the base 20 is changed. The light emitting device according to this embodiment will be described below with reference to FIGS. 7 and 8, focusing on the differences from the light emitting device 10 according to embodiment 1.

Figure 7 is a plan view showing the light-emitting device 110 according to this embodiment with the optical member 40 removed. Figure 7 shows a plan view of the main surface 21 of the base 20. Figure 7 also shows the outlines of multiple lens portions 43 with dashed lines. Figure 8 is a cross-sectional view of the light-emitting device 110 according to this embodiment. Figure 8 shows a cross-section taken along line VIII-VIII in the X-axis direction of Figure 7. Note that Figure 8 also shows a cross-section of the optical member 40.

The light-emitting device 110 according to this embodiment includes a base 20, a frame member 30, an optical member 40, multiple semiconductor laser chips 60, multiple submounts 53a-53d, 54a-54d, 55a-55d, 56a-56d, and 57a-57d, and multiple mirrors 70.

In this embodiment, as shown in FIG. 7 , in a plan view of the main surface 21 of the base 20, the relative position between each of the multiple mirrors 70 and each of the multiple lens portions 43 is the same for all mirrors 70. In the example of the light-emitting device 110 according to this embodiment, in a plan view of the main surface 21, the center position 43C of each of the multiple lens portions 43 coincides with the center position 71C of the reflecting surface 71 corresponding to each of the multiple lens portions 43. Furthermore, the distance from the emission point E1 of the semiconductor laser chip 60 to the center position 71C of the reflecting surface 71 is the same for all. In other words, the positional relationship between the semiconductor laser chip 60 and the mirror 70 is the same for all.

As shown in FIG. 8, the multiple submounts 53a-53d, 54a-54d, 55a-55d, 56a-56d, and 57a-57d differ from the submount 50 of embodiment 1 in that they have different heights. The direction of the optical axis of reflected light L2 is parallel to the direction perpendicular to the main surface 21, since the angle of the reflecting surface with respect to the main surface is 45°. The absolute value of the difference between the height from the main surface 21 to the emission point E1 of each of the multiple semiconductor laser chips 60 and the average height from the main surface 21 to the emission point E1 of each of the multiple semiconductor laser chips 60 increases as the distance from the center position 44C of the lens region 44 to the center position 43C of the lens portion 43 corresponding to each of the multiple submounts increases. Therefore, the distance from the main surface 21 of the optical axis of the semiconductor laser chip 60, i.e., the position of the emitted light L1 in the X-axis direction on the reflecting surface 71, varies depending on the height of the submount.

As a result, similar to the light-emitting device 10 according to embodiment 1, in the light-emitting device 110 according to this embodiment, in a plan view of the main surface 21, the distance in the X-axis direction between the center position C1 of the emitted light L1 on the reflecting surface 71 and the center position 43C of the lens portion 43 among the plurality of lens portions 43 that corresponds to the reflecting surface 71 increases as the distance in the X-axis direction between the center position C1 of the emitted light L1 and the center position 44C of the lens region 44 in which the plurality of lens portions 43 are arranged increases. Therefore, the position of the reflected light L2 incident on each of the plurality of lens portions 43 according to this embodiment in the X-axis direction is the same as in embodiment 1, and the output light L3 is refracted toward the center of the lens region 44 in the X-axis direction. On the other hand, it is not refracted in the Y-axis direction. Here, as shown in FIG. 7 , the optical axis of each output light L3 is generally oriented toward the center of the lens region 44 in the X-axis direction in a plan view, but this need not be strictly oriented.

Therefore, even in the light-emitting device 110 according to this embodiment, multiple output light beams L3 can be focused onto a predetermined surface area A1 that is smaller in area than the lens area 44 without the need for a focusing lens.

Here, because the absolute value of the difference from the average height is proportional to De, the optical axes of all output light beams L3 can be converged to approximately one location. Furthermore, in the Y-axis direction, as in embodiment 1, the distance in the Y-axis direction between the center position of output light beam L1 on reflecting surface 71 and center position 43C of the lens portion 43 corresponding to reflecting surface 71 is increased as the distance in the Y-axis direction between center position C1 of output light beam L1 and center position 44C of lens region 44 in which the multiple lens portions 43 are arranged increases (not shown). This makes it possible to converge multiple output light beams L3 to a predetermined surface region A1 smaller in area than lens region 44 without using a converging lens. Furthermore, if the distance from the position of the emission point E1 of the semiconductor laser chip 60 in a plan view to the center position 71C of the reflecting surface 71 is the same for all positions, the angle between the main surface 21 of the base 20, which is parallel to the emitted light L1, and the reflecting surface 71 is 45°. Therefore, even if the height from the main surface 21 to the position of the emission point E1 of the semiconductor laser chip 60 changes, the sum of the distance from the emission point E1 of the semiconductor laser chip 60 to the center position of the emitted light L1 on the reflecting surface 71 and the distance from the center position of the emitted light L1 on the reflecting surface 71 to the lens portion 43 remains constant, and the effect of the height from the main surface 21 to the position of the emission point E1 of the semiconductor laser chip 60 on the focusing state of the output light L3 can be minimized.

Furthermore, in the light-emitting device 110 according to this embodiment and in all of the other embodiments 210 to 710 described below, each of the multiple semiconductor laser chips 60 is mounted on the main surface 21 and has an optical axis parallel to the main surface 21, thereby achieving the same improved heat dissipation effect as the light-emitting device 10 according to embodiment 1.

(Embodiment 3)
A light emitting device according to embodiment 3 will be described. The light emitting device according to this embodiment differs from light emitting device 110 according to embodiment 2 in that the height of the optical axis of emitted light L1 from main surface 21 is the same for all semiconductor laser chips 60, but the height of reflecting surface 71 from main surface 21 is changed, and the distance between emission point E1 and center position 71C of reflecting surface 71 in plan view is changed. The light emitting device according to this embodiment will be described below with reference to FIGS. 9 and 10, focusing on the differences from light emitting device 110 according to embodiment 2.

Figure 9 is a plan view showing the light-emitting device 210 according to this embodiment with the optical member 40 removed. Figure 9 shows a plan view of the main surface 21 of the base 20. Figure 9 also shows the outlines of multiple lens portions 43 with dashed lines. Figure 10 is a cross-sectional view of the light-emitting device 210 according to this embodiment. Figure 10 shows a cross-section taken along line X-X in Figure 9. Note that Figure 10 also shows a cross-section of the optical member 40.

The light-emitting device 210 according to this embodiment includes a base 20, a frame member 30, an optical member 40, multiple semiconductor laser chips 60, multiple submounts 50, and multiple mirrors 73a-73d, 74a-74d, 75a-75d, 76a-76d, and 77a-77d.

The multiple submounts 50 according to this embodiment have the same configuration as the multiple submounts 50 according to embodiment 1. Therefore, the distances from the main surface 21 to the optical axes of the semiconductor laser chips 60 mounted on the multiple submounts 50 are all the same.

Each of the multiple mirrors 73a-73d, 74a-74d, 75a-75d, 76a-76d, and 77a-77d has a reflective surface 71, similar to mirror 70 according to embodiment 2. As shown in FIG. 9, in a plan view of the main surface 21 of the base 20, the relative position between each of the multiple mirrors and each of the multiple lens portions 43 is the same for all mirrors. In the example of light-emitting device 210 according to this embodiment, in a plan view of the main surface 21, the center position 43C of each of the multiple lens portions 43 coincides with the center position 71C of the reflective surface 71 corresponding to each of the multiple lens portions 43.

As shown in FIG. 10 , the multiple mirrors according to this embodiment differ from the multiple mirrors 70 according to embodiment 1 in that the heights of the center positions 71C of the reflecting surfaces 71 from the principal surface 21 are not the same. The direction of the optical axis of the reflected light L2 is parallel to the direction perpendicular to the principal surface 21, since the angle of the reflecting surface 71 with respect to the principal surface 21 is 45°. The absolute value of the difference between the height from the principal surface 21 to the center position 71C of the reflecting surface 71 and the average height from the principal surface 21 to the center position 71C of the reflecting surface 71 for the multiple mirrors increases as the distance from the center position 44C of the lens region 44 to the center position 43C of the lens portion 43 corresponding to each of the multiple mirrors increases. Therefore, the position of the emitted light L1 in the X-axis direction on the reflecting surface 71 varies depending on the height from the principal surface 21 of the center position 71C of the reflecting surface 71. As a result, similarly to the light-emitting device 10 according to the first embodiment, in the light-emitting device 210 according to the present embodiment, in a plan view of the main surface 21, the distance between the center position C1 of the emitted light L1 on the reflecting surface 71 and the center position 43C of the lens portion 43 among the plurality of lens portions 43 corresponding to the reflecting surface 71 increases as the distance between the center position C1 of the emitted light L1 and the center position 44C of the lens region 44 in which the plurality of lens portions 43 are arranged increases. Therefore, the position of the reflected light L2 incident on each of the plurality of lens portions 43 according to the present embodiment is the same as in the first embodiment in the X-axis direction, and the output light L3 is refracted toward the center of the lens region 44 in the X-axis direction. On the other hand, it is not refracted in the Y-axis direction. Here, as shown in FIG. 9 , the optical axis direction of each output light L3 is generally oriented toward the center position of the lens region 44 in the X-axis direction in a plan view, but this does not necessarily have to be strictly oriented. Therefore, in the light-emitting device 210 according to this embodiment, multiple output light beams L3 can be focused onto a predetermined surface area A1 that is smaller in area than the lens area 44, without the need for a focusing lens.

In this third embodiment, the absolute value of the difference between the average height of the center position 71C of the reflecting surface 71 and the center position 71C is proportional to De, allowing the optical axes of all output light L3 to be converged to approximately one location. Furthermore, because the angle between the output light L1 and the reflecting surface 71 is 45°, the distance from the center position of the output light L1 on the reflecting surface 71 to the lens portion 43 is shortened by the same amount as the change in height from the main surface 21 to the center position 71C of the reflecting surface 71. Therefore, as shown in FIG. 10, by increasing the distance from the output point E1 of the semiconductor laser chip 60 to the center position 71C of the reflecting surface 71 by the same amount, the sum of the distance from the output point E1 of the semiconductor laser chip 60 to the center position 71C of the reflecting surface 71 and the distance from the main surface 21 to the center position 71C of the reflecting surface 71 can be made constant. This minimizes the effect of the change in height from the main surface 21 to the center position 71C of the reflecting surface 71 on the convergence of the output light L3. Furthermore, in the Y-axis direction, as in the first embodiment, the distance in the Y-axis direction between the center position of the output light L1 on the reflecting surface 71 and the center position 43C of the lens portion 43 that corresponds to the reflecting surface 71 is increased as the distance in the Y-axis direction between the center position C1 of the output light L1 and the center position 44C of the lens region 44 in which the multiple lens portions 43 are arranged increases (not shown), making it possible to focus the multiple output light beams L3 on a predetermined surface region A1 that is smaller in area than the lens region 44 without placing a focusing lens.

(Fourth embodiment)
A light emitting device according to embodiment 4 will be described. The light emitting device according to this embodiment differs from the light emitting device 10 according to embodiment 1 mainly in that the direction of the optical axis of at least a portion of the reflected light L2 differs from the direction of the optical axis of the lens portion 43. The light emitting device according to this embodiment will be described below with reference to FIGS. 11 and 12, focusing on the differences from the light emitting device 10 according to embodiment 1.

Figure 11 is a plan view showing a light-emitting device 310 according to this embodiment with the optical member 40 removed. Figure 11 shows a plan view of the main surface 21 of the base 20. Figure 11 also shows the outlines of multiple lens portions 43 with dashed lines. Figure 12 is a cross-sectional view of the light-emitting device 310 according to this embodiment. Figure 12 shows a cross-section taken along line XII-XII in Figure 11. Note that Figure 12 also shows a cross-section of the optical member 40.

The light-emitting device 310 according to this embodiment includes a base 20, a frame member 30, an optical member 40, a plurality of semiconductor laser chips 60, a plurality of submounts 50, and a plurality of mirrors 373a-373d, 374a-374d, 375a-375d, 376a-376d, and 377a-377d. As shown in FIG. 11, in a plan view of the main surface 21, each mirror is positioned so that the direction perpendicular to the reflective surface 71 of each mirror projected onto the main surface 21 (e.g., the direction of the dashed arrow 71D shown on mirror 374b in FIG. 11) is parallel to the line connecting the center position 71C of the reflective surface 71 and the center position 44C of the lens region 44 (e.g., the dashed-dotted line connecting the center position 44C of the lens region 44 and the center position 71C of the reflective surface 71 of mirror 374b in FIG. 11). Furthermore, each semiconductor laser chip 60 and submount 50 are positioned so that the direction of the optical axis of the emitted light L1 from each semiconductor laser chip 60 coincides with the direction perpendicular to the reflecting surface 71 on which the emitted light L1 is incident, projected onto the main surface 21.

Each of the multiple mirrors according to this embodiment has a reflective surface 71, similar to the mirror 70 according to embodiment 1. As shown in FIG. 12, the multiple mirrors according to this embodiment are the same as those according to embodiment 1 in that the optical axis of reflected light L2 passes through the optical center of the lens portion 43, but differ from the mirror 70 according to embodiment 1 in the inclination of the reflective surface 71. In this embodiment, the absolute value of the difference between the angle Dm perpendicular to the main surface 21 and the direction D71 perpendicular to the reflective surface 71 (see angle θr for mirror 375a in FIG. 12) and the average value of this angle for the multiple mirrors increases as the distance from the center position 44C of the lens region 44 to the center position 43C of the lens portion 43 corresponding to the reflective surface 71 increases. As a result, the angle (see angle θ2 in FIG. 12 ) between the direction of the optical axis of reflected light L2 and the direction perpendicular to main surface 21 (or the direction of the optical axis of lens portion 43) increases as the distance from center position 44C of lens region 44 to center position 43C of the lens portion 43 that receives reflected light L2 increases. Note that in this embodiment, as shown in FIG. 12 , the optical axis of reflected light L2 passes through the center position (optical center) of lens portion 43, so even if the optical axis of lens portion 43 and the optical axis of reflected light L2 are misaligned, reflected light L2 and output light L3 propagate in the same direction.

Therefore, the optical axis of the reflected light L2 is not refracted by the lens unit 43, and the optical axis of the output light L3 can be tilted with respect to the optical axis of the lens unit 43, so that the output light L3 can be focused on the predetermined surface area A1. In this way, in this embodiment, since there is no need to refract the optical axis of the reflected light L2 by the lens unit 43, it is possible for the reflected light L2 to be incident near the optical axis of the lens unit 43. Therefore, the coma aberration of the output light L3 can be reduced, and distortion of the profile of the output light L3 in the predetermined surface area A1 can be suppressed. In other words, the output light L3 can be reliably focused on the predetermined surface area A1.

Here, the absolute value of the difference from the average value of this angle is proportional to the distance from the center position 44C of the lens region 44 to the center position 43C of the lens section 43, so that the optical axes of all output light L3 can be converged to approximately one location. Also, as shown in Figure 11, the optical axes of the reflected light L2 and the output light L3 are generally oriented toward the center position of the lens region 44 in a planar view, but they do not necessarily have to be oriented exactly toward the center position.

Also, as shown in Figure 11, the angle between the direction perpendicular to the reflecting surface 71 projected onto the main surface 21 and the direction of incidence of the emitted light L1 on the reflecting surface 71 is the same for all mirrors. In this embodiment, this angle is 0°. Making the angle the same allows for a unified standard for position inspection after mounting, simplifying the inspection.

Here, by positioning the semiconductor laser chip 60 so that the sum of the distance from the emission point E1 of the semiconductor laser chip 60 to the center position of the emitted light L1 on the reflecting surface 71 and the distance from the center position of the emitted light L1 on the reflecting surface 71 to the lens section 43 is constant, the effect that changes in the angle of the reflecting surface 71 have on the focusing state of each output light L3 can be greatly reduced.

Fifth Embodiment
A light emitting device according to embodiment 5 will be described. The light emitting device according to this embodiment differs from light emitting device 310 according to embodiment 4 in the configuration of the multiple mirrors. The light emitting device according to this embodiment will be described below with reference to FIGS. 13 and 14, focusing on the differences from light emitting device 310 according to embodiment 4.

Figure 13 is a plan view showing a light-emitting device 410 according to this embodiment with the optical member 40 removed. Figure 13 shows a plan view of the main surface 21 of the base 20. Figure 13 also shows the outlines of multiple lens portions 43 with dashed lines. Figure 14 is a cross-sectional view of the light-emitting device 410 according to this embodiment. Figure 14 shows a cross-section taken along line XIV-XIV in Figure 13. Note that Figure 14 also shows a cross-section of the optical member 40.

The light-emitting device 410 according to this embodiment includes a base 20, a frame member 30, an optical member 40, a plurality of semiconductor laser chips 60, a plurality of submounts 50, and a plurality of mirrors 470. In this embodiment, the light-emitting device 410 further includes a plurality of support portions 83a-83d, 84a-84d, 85a-85d, 86a-86d, and 87a-87d, as shown in FIG. 13. Here, the support portions may be formed integrally with the base, or may be composed of separate members.

As shown in FIG. 14, each of the multiple mirrors 470 is a plate-shaped element having a reflective surface 71. In this embodiment, each of the multiple mirrors 470 has a plate-like shape with a rectangular reflective surface 71 as one of its main surfaces. In other words, each of the multiple mirrors 470 has a rectangular parallelepiped shape. The multiple mirrors 470 are respectively supported against multiple supports 83a-83d, 84a-84d, 85a-85d, 86a-86d, and 87a-87d. Note that each of the multiple mirrors 470 may be bonded to the main surface 21 of the base 20 and the corresponding support using a bonding material or the like.

Each of the multiple support portions 83a-83d, 84a-84d, 85a-85d, 86a-86d, and 87a-87d shown in FIG. 13 is disposed on the main surface 21 of the base 20 and supports the mirror 470. In this embodiment, the multiple support portions form a step between themselves and the main surface 21. The multiple support portions also differ in size from one another. Specifically, as shown in FIG. 14, the absolute value of the difference (|Hs-Hsm|) between the height of the support portion from the main surface 21 (see the height Hs of support portion 85d shown in FIG. 14) and the average value of that height for the multiple support portions (see the average height Hsm of the support portions shown in FIG. 14) increases as the distance from the center position 44C of the lens region 44 to the center position 43C of the lens portion 43 that corresponds to the reflective surface 71 of the mirror 470 supported by the support portion increases. As a result, similar to the fourth embodiment, the absolute value of the difference between the angle (θr) between the direction perpendicular to the main surface 21 and the direction perpendicular to the reflecting surface 71 and the average value of the angle formed by the multiple mirrors increases as the distance from the center position 44C of the lens region 44 to the center position 43C of the lens portion 43 corresponding to the reflecting surface 71 increases. Therefore, in the light-emitting device 410 according to this embodiment, the positional relationship between the emitted light L1 from the semiconductor laser chip 60, the reflected light L2 from the reflecting surface 71, and the output light L3 from the lens portion 43 is the same as in the fourth embodiment, and therefore the same effect as in the fourth embodiment is achieved. Here, the absolute value of the difference from the average value of the angle formed is proportional to the distance from the center position 44C of the lens region 44 to the center position 43C of the lens portion 43, so that the optical axes of all the output light L3 can be converged to approximately one location. Furthermore, in this embodiment, the inclination angle of each of the multiple mirrors 470 relative to the main surface 21 of the base 20 can be adjusted, enabling fine optical axis adjustment. Furthermore, since the structure of multiple mirrors 470 can be made common, manufacturing of multiple mirrors 470 can be simplified and the cost required for multiple mirrors 470 can be reduced.

(Embodiment 6)
A light emitting device according to embodiment 6 will be described. The light emitting device according to this embodiment differs from light emitting device 310 according to embodiment 4 mainly in the configuration of the plurality of semiconductor laser chips 60 and the plurality of mirrors 70. The light emitting device according to this embodiment will be described below with reference to FIG. 15 , focusing on the differences from light emitting device 310 according to embodiment 4.

Figure 15 is a plan view showing the light-emitting device 510 according to this embodiment with the optical member 40 removed. Figure 15 shows a plan view of the main surface 21 of the base 20. Figure 15 also shows the outlines of the multiple lens portions 43 with dashed lines, as well as the optical axis of the reflected light L2 from the mirror 70 and the optical axis of the output light L3.

The light-emitting device 510 according to this embodiment comprises a base 20, a frame member 30, an optical member 40, a plurality of semiconductor laser chips 60, a plurality of submounts 50, and a plurality of mirrors 70. Except for their arrangement, the plurality of semiconductor laser chips 60, the plurality of submounts 50, and the plurality of mirrors 70 each have the same configuration as the plurality of semiconductor laser chips 60, the plurality of submounts 50, and the plurality of mirrors 70 according to embodiment 1.

In this embodiment, the angle between the reflecting surface 71 of the mirror 70 and the main surface 21 of the base 20 is 45°. When direction A (the direction of the dashed line in Figure 15, i.e., the X-axis direction) obtained by projecting a direction perpendicular to the reflecting surface 71 onto the main surface 21 coincides with the optical axis of the emitted light L1, the reflected light L2 travels in direction B (Z-axis direction) perpendicular to the main surface 21 of the base 20. When they do not coincide, if the vector of the emitted light L1 is decomposed into direction A and direction C (Y-direction) orthogonal to direction A in a plane parallel to the main surface 21, the vector of the reflected light L2 will have components in directions B and C. That is, in a planar view, the reflected light L2 will point in direction C (Y-axis direction).

In this embodiment, in a plan view of the main surface 21 of the base 20, the direction of the reflected light L2 is tilted with respect to the direction perpendicular to the main surface 21 by adjusting the angle between the direction perpendicular to the reflecting surface 71 of the mirror 70 projected onto the main surface 21 of the base 20 and the direction of the optical axis of the emitted light L1 from the semiconductor laser chip 60. Specifically, the angle between the direction perpendicular to the reflecting surface 71 projected onto the main surface 21 (the direction of the dashed line shown in FIG. 15) and the direction of the emitted light L1 (the direction of the dot-dash line shown in FIG. 15) increases as the distance from the center position 44C of the lens region 44 to the center position 43C of the lens portion 43 corresponding to the reflecting surface 71 increases. As a result, the angle between the direction of the optical axis of the reflected light L2 and the direction perpendicular to the main surface 21 increases as the distance from the center position 44C of the lens region 44 to the center position 43C of the lens portion 43 that receives the reflected light L2 increases. Therefore, in the light-emitting device 510 according to the present embodiment, as in the light-emitting device 310 according to the fourth embodiment, the angle between the direction of the optical axis of the reflected light L2 and the direction perpendicular to the main surface 21 increases as the distance from the center position 44C of the lens region 44 to the center position 43C of the lens portion 43 that receives the reflected light L2 increases, thereby achieving a similar light-condensing effect. In particular, as described in the first embodiment, when the optical axis of the reflected light L2 passes through a location that is shifted from the center position 43C of the lens portion, the output light L3 changes direction and travels toward the center position 43C of the lens portion. Therefore, by appropriately positioning the light-emitting device 510 according to the first embodiment, the output light L3 can be directed toward the center position 44C of the lens region 44 (see the arrow indicating the output light L3 in FIG. 15 ). In other words, multiple output light beams L3 can be focused onto the specified surface area A1.

Here, this angle is approximately proportional to the distance from the center position 44C of the lens region 44 to the center position 43C of the lens section 43, so that the optical axes of all output light L3 can be converged to approximately one point.

Furthermore, in this embodiment, it is possible to use the same mirror for all of the multiple mirrors 70. This simplifies the configuration of the light-emitting device 510.

Furthermore, in this embodiment, the direction perpendicular to the reflecting surface 71 of the mirror 70 projected onto the main surface is the direction of the dashed line shown on each mirror 70 in Figure 15, and is the same direction for all multiple mirrors (i.e., the X-axis direction in Figure 15). In this way, the orientation of multiple mirrors 70 can be unified, allowing the multiple mirrors 70 to be aligned. This makes it easier to implement multiple mirrors 70.

In addition, in this embodiment, the angle (45°) between the reflective surface 71 and the main surface 21 in the direction perpendicular to the reflective surface 71 is the same for all of the multiple mirrors 70. In this way, the same mirrors can be used for all of the multiple mirrors 70, simplifying the configuration of the light-emitting device 510. Furthermore, because the reflective surfaces 71 of multiple mirrors lined up in a row can be set to the same plane, multiple mirrors can be replaced with a single mirror connected in the row direction, further simplifying the configuration.

Incidentally, for the four semiconductor laser chips 60 whose positions in the Y-axis direction shown in Figure 15 are the same as the center position 44C of the lens region 44 (the four semiconductor laser chips 60 arranged in the third row from the top in Figure 15), the angles between the direction perpendicular to the reflecting surface 71 projected onto the main surface 21 and the direction of the emitted light L1 are all 0°, and do not increase as the distance from the center position 44C of the lens region 44 increases. Such a combination of emitted light L1 and mirror 70 may be included in the light-emitting device 510.

Seventh Embodiment
A light emitting device according to embodiment 7 will be described. The light emitting device according to this embodiment differs from the light emitting device 510 according to embodiment 6 mainly in the configuration of the plurality of semiconductor laser chips 60 and the plurality of mirrors 70. The light emitting device according to this embodiment will be described below with reference to FIG. 16 , focusing on the differences from the light emitting device 510 according to embodiment 6.

Figure 16 is a plan view showing a light-emitting device 610 according to this embodiment with the optical member 40 removed. Figure 16 shows a plan view of the main surface 21 of the base 20. Figure 16 also shows the outlines of multiple lens portions 43 with dashed lines, as well as the optical axis of the reflected light L2 from the mirror 70 and the optical axis of the output light L3.

The light-emitting device 610 according to this embodiment comprises a base 20, a frame member 30, an optical member 40, a plurality of semiconductor laser chips 60, a plurality of submounts 50, and a plurality of mirrors 70. Except for their arrangement, the plurality of semiconductor laser chips 60, the plurality of submounts 50, and the plurality of mirrors 70 each have the same configuration as the plurality of semiconductor laser chips 60, the plurality of submounts 50, and the plurality of mirrors 70 according to embodiment 1.

In this embodiment, as in the sixth embodiment, the direction of the reflected light L2 is tilted relative to the direction perpendicular to the principal surface 21 by adjusting the angle between the direction perpendicular to the reflecting surface 71 of the mirror 70 projected onto the principal surface 21 of the base 20 (the direction of the dashed line shown in FIG. 16 ) in a plan view of the principal surface 21 of the base 20 and the direction of the optical axis of the emitted light L1 from the semiconductor laser chip 60 (the direction of the dot-dash line shown in FIG. 16 ). In this embodiment, the direction perpendicular to the reflecting surfaces 71 of the multiple mirrors 70 is changed depending on the distance from the center position 44C of the lens region 44. Specifically, in a plan view of the principal surface 21, the angle between the direction perpendicular to the reflecting surface 71 projected onto the principal surface 21 and the line connecting the center position 71C of the reflecting surface 71 and the center position 44C of the lens region 44 increases as the distance from the center position 44C of the lens region 44 to the center position 71C of the reflecting surface 71 increases. As a result, the angle between the direction of the optical axis of reflected light L2 and the direction perpendicular to main surface 21 increases as the distance from center position 44C of lens region 44 to center position 43C of the lens portion 43 that receives reflected light L2 increases. Therefore, light-emitting device 610 according to this embodiment is similar to light-emitting device 510 according to embodiment 6, and therefore achieves the same effects.

Here, because this angle is approximately proportional to the distance from the center position 44C of the lens region 44 to the center position 71C of the reflecting surface 71, the optical axes of all output light L3 can be converged to approximately one point. Furthermore, within the main surface 21, the direction orthogonal to the direction perpendicular to the reflecting surface 71 projected onto the main surface 21 points toward the center position 44C of the lens region 44, and, as in embodiment 1, the center position 43C of the lens section 43 may be on the line segment connecting the center position of the output light L1 on the reflecting surface 71 and the center position 44C of the lens region 44. This makes it possible to converge all output light L3 to one point.

Furthermore, in this embodiment, it is possible to use the same mirror for all of the multiple mirrors 70. This simplifies the configuration of the light-emitting device 610.

Furthermore, in this embodiment, the direction of the emitted light L1 is the same for all of the multiple semiconductor laser chips 60 (i.e., a direction parallel to the X-axis direction in Figure 15). This allows the orientation of the multiple semiconductor laser chips 60 to be unified, making it possible to align the multiple semiconductor laser chips 60. This therefore makes it easier to mount the multiple semiconductor laser chips 60.

Furthermore, in this embodiment, the angle (45°) between the reflective surface 71 and the main surface 21 in the direction perpendicular to the reflective surface 71 is the same for all of the multiple mirrors 70. In this way, the same mirrors can be used for all of the multiple mirrors 70, simplifying the configuration of the light-emitting device 610.

In addition, for the four mirrors 70 whose positions in the Y-axis direction shown in Figure 16 are the same as the center position 44C of the lens region 44 (the four mirrors 70 arranged in the third row from the top in Figure 16), the angles formed between the direction perpendicular to the reflective surface 71 projected onto the main surface 21 and the line connecting the center position 71C of the reflective surface 71 and the center position 44C of the lens region 44 are all 0°, and do not increase as the distance from the center position 44C of the lens region 44 to the center position 71C of the reflective surface 71 increases. Such a combination of emitted light L1 and mirrors 70 may be included in the light-emitting device 610.

Eighth Embodiment
A light emitting device according to embodiment 8 will be described. The light emitting device according to this embodiment differs from the light emitting device 510 according to embodiment 6 mainly in the configuration of the optical members and the configurations of the plurality of semiconductor laser chips 60 and the plurality of mirrors 70. The light emitting device according to this embodiment will be described below with reference to FIGS. 17 and 18, focusing on the differences from the light emitting device 510 according to embodiment 6.

Figure 17 is a plan view showing a light-emitting device 710 according to this embodiment with the optical member 40 removed. Figure 17 shows a plan view of the main surface 21 of the base 20. Figure 17 also shows the outlines of multiple lens portions 743 with dashed lines, as well as the optical axis of reflected light L2 from the mirror and the optical axis of output light L3. Figure 18 is a schematic cross-sectional view of the light-emitting device 710 according to this embodiment. Figure 18 shows a cross-section taken along line XVIII-XVIII in Figure 17. Note that Figure 18 also shows a cross-section of the optical member 740. Figure 18 also schematically shows the semiconductor laser chip 60, which is not present in the cross-section.

The light-emitting device 710 according to this embodiment includes a base 20, a frame member 30, an optical member 740, a plurality of semiconductor laser chips 60, a plurality of submounts 50, and a plurality of mirrors 70. Except for their arrangement, the plurality of semiconductor laser chips 60, the plurality of submounts 50, and the plurality of mirrors 70 each have the same configuration as the plurality of semiconductor laser chips 60, the plurality of submounts 50, and the plurality of mirrors 70 according to embodiment 1.

The optical element 740 has a plurality of lens portions 743. As shown in FIG. 17 , the optical element 740 has a lens region 744 in which the plurality of lens portions 743 are arranged. The lens region 744 is, for example, the region surrounded by an envelope 744E of the plurality of lens portions 743. The center position 744C of the lens region 744 is the center of gravity of the lens region 744.

The lens portion 743 is an aspherical lens, such as a parabolic lens. In this embodiment, as shown by the dashed-dotted line in FIG. 18 , the optical axis of the lens portion 743 is inclined with respect to the direction perpendicular to the principal surface 21. The magnitude of this inclination angle increases as the distance from the center position 744C of the lens region 744 to the lens portion 743 increases. In other words, the angle between the direction of the optical axis of each of the multiple lens portions 743 and the direction perpendicular to the principal surface 21 increases as the distance from the center position 744C of the lens region 744 to the center position 743C of each of the multiple lens portions 743 increases. This allows the direction and position of the optical axis of the reflected light L2 incident on the lens portion 743 to approximately coincide with the direction and position of the optical axis of the lens portion 743, respectively, thereby focusing the output light L3 on the predetermined surface area A1. Furthermore, by bringing the position of the optical axis of the reflected light L2 closer to the position of the optical axis of the lens portion 743, coma aberration in the lens portion 743 can be reduced, thereby suppressing distortion of the profile of the output light L3 in the specified surface area A1. In other words, the output light L3 can be reliably focused on the specified surface area A1.

Furthermore, the optical axis of each of the multiple lens units 743 may intersect with the predetermined surface area A1. This allows the direction and position of the optical axis of the reflected light L2 incident on the lens unit 743 to approximately coincide with the direction and position of the optical axis of the lens unit 743, respectively, thereby allowing the output light L3 to be focused on the predetermined surface area A1.

Furthermore, as shown in FIG. 17 , in a plan view of the main surface 21, a point 743A, through which the optical axis of each of the plurality of lens portions 743 passes, may be located on the surface of each of the plurality of lens portions 743, on a line segment connecting the center position 744C of the lens region 744 and the center position C1 of the emitted light L1 on the reflecting surface 71 corresponding to each of the plurality of lens portions 743. This makes it possible to align the reflected light L2 from the reflecting surface 71 with the optical axis of the lens portion 743, thereby reducing the component of the reflected light L2 that deviates from the optical axis of the lens portion 743 and is lost.

Furthermore, the angle (angle θe shown in FIG. 18) between the direction of the optical axis of each of the multiple lens portions 743 and the direction of the optical axis of the reflected light L2 incident on each of the multiple lens portions 743 may increase as the distance from the center position 744C of the lens region 744 to the center position 743C of each of the multiple lens portions 743 increases. This configuration has the same positional relationship as the reflected light L2 and lens portions 43 in embodiment 4, and therefore has the same focusing effect. Note that in this embodiment, the reflected light L2 and output light L3 propagate in the same direction, as shown in FIG. 18.

The profile of output light L3 in a predetermined surface area A1 of light-emitting device 710 according to embodiments 4, 5, 6, and 8 will be described using Figure 19. Figure 19 is a diagram showing a far-field pattern obtained by superimposing the profiles of all output light L3 in a predetermined surface area A1 of light-emitting device 710 according to the present embodiment. In Figure 19, the profile of each output light L3 is indicated by a dashed line.

As shown in Figure 19, the far-field pattern obtained by superimposing the profiles of all output light L3 in a predetermined surface area A1 of the light-emitting device 710 according to this embodiment is circular. Note that the term "circular" here does not necessarily mean a perfect circle, but also includes something that is substantially circular. For example, even if the deviation of the outline of the far-field pattern from a circle is 10% or less, the shape of the far-field pattern is also considered circular.

Furthermore, as shown in Figure 19, the cross-sectional shape of the output light L3 has a major axis direction in the specified surface area A1. In Figure 19, part of the major axis direction is indicated by a thick solid line. The major axis direction is evenly distributed in all of the output light L3. In other words, the major axis direction is not biased in a particular direction in all of the output light L3. This makes it easier to homogenize the light intensity distribution in the specified surface area A1. Therefore, it is possible to generate irradiation light with little unevenness in the intensity distribution.

(Variations, etc.)
Although the light emitting device according to the present disclosure has been described above based on the embodiments, the present disclosure is not limited to the above-described embodiments.

For example, in each of the above embodiments, each light-emitting device includes a frame member 30, but the frame member 30 is not an essential component of each light-emitting element. For example, each optical member of each light-emitting device may have a portion equivalent to a frame member. Furthermore, each optical member may be supported on the base 20 by a member other than the frame member 30.

Furthermore, the submount 50 of each light-emitting device other than that of embodiment 2 is not an essential component. The semiconductor laser chip 60 may be mounted directly on the base 20. In this way, the semiconductor laser chip 60 may be mounted directly on the main surface 21 of the base 20 or via the submount 50.

Furthermore, in each of the above embodiments, the multiple semiconductor laser chips 60 all have the same configuration, but they may also have different configurations.

In addition, in the light-emitting device 310 according to embodiment 4, the direction perpendicular to the reflecting surface 71 projected onto the main surface 21 was not the same for all of the multiple mirrors, but it may be the same. In this case, as with the light-emitting device 510 according to embodiment 6, by varying the direction of the emitted light L1 for each semiconductor laser chip 60, it is possible to adjust the direction of the optical axis of the reflected light L2 to be the same as the optical axis of the reflected light L2 according to embodiment 4. In this case, the direction perpendicular to the reflecting surface 71 of the multiple mirrors may also be adjusted as appropriate.

Furthermore, in each of the light-emitting devices according to embodiments 1, 2, 3, and 7, by uniformly reducing the major axis direction of each output light by using a cylindrical lens or the like, it is possible to obtain a circular far-field pattern, similar to the light-emitting device 710 according to embodiment 8.

This disclosure also includes forms obtained by applying various modifications to the above embodiments that would occur to those skilled in the art, as well as forms realized by arbitrarily combining the components and functions of the above embodiments within the scope of the spirit of this disclosure.

The light-emitting device disclosed herein can be used, for example, as a high-output, high-light-density light source for projectors.

10, 110, 210, 310, 410, 510, 610, 710 Light emitting device 20 Base 21 Main surface 30 Frame member 40, 740 Optical member 43, 743 Lens portion 43C, 44C, 71C, 743C, 744C, C1 Center position 44, 744 Lens area 44E, 744E Envelope 50, 53a, 53b, 53c, 53d, 54a, 54b, 54c, 54d, 55a, 55b, 55c, 55d, 56a, 56b, 56c, 56d, 57a, 57b, 57c, 57d Submount 51 Mounting surface 52 Mounting surface 60 Semiconductor laser chip 70, 73a, 73b, 73c, 73d, 74a, 74b, 74c, 74d, 75a, 75b, 75c, 75d, 76a, 76b, 76c, 76d, 77a, 77b, 77c, 77d, 373a, 373b, 373c, 373d, 374a, 374b, 374c, 374d, 375a, 375b, 375c, 375d, 376a, 376b, 376c, 376d, 377a, 377b, 377c, 377d, 470 mirror 71 reflective surface 83a, 83b, 83c, 83d, 84a, 84b, 84c, 84d, 85a, 85b, 85c, 85d, 86a, 86b, 86c, 86d, 87a, 87b, 87c, 87d Support part A1 Predetermined surface area E1 Emission point L1 Output light L2 Reflected light L3 Output light

Claims (28)

a base having a main surface;
a plurality of semiconductor laser chips mounted on the main surface and having optical axes parallel to the main surface;
a plurality of mirrors, each having a reflecting surface that reflects light emitted from each of the emission points of the plurality of semiconductor laser chips;
an optical member having a plurality of lens portions each receiving reflected light from the reflective surfaces of the plurality of mirrors;
When a distance from a center position of the emitted light on the reflecting surface to a center position of a lens portion of the plurality of lens portions corresponding to the reflecting surface is defined as a first distance in a plan view of the main surface,
the first distance to a lens portion of the plurality of lens portions that is closest to a center position of the lens region in which the plurality of lens portions are arranged is greater than the first distance to a lens portion of the plurality of lens portions that is located at the outermost position of the lens region in which the plurality of lens portions are arranged;
The output light from each of the plurality of lens portions is irradiated onto the inside of a predetermined surface area having an area smaller than that of the lens area,
When an angle formed between the direction of the optical axis of the reflected light and a direction perpendicular to the main surface is defined as a first angle,
The first angle with respect to the reflected light corresponding to a lens portion of the plurality of lens portions that is closest to a center position of the lens region is larger than the first angle with respect to the reflected light corresponding to a lens portion of the plurality of lens portions that is located at the outermost position of the lens region.
Light-emitting device. The light emitting device according to claim 1 , wherein the first angle increases as the distance from the center of the lens region to the center of one of the plurality of lens portions that receives the reflected light increases. When the absolute value of the difference between the angle formed by the direction perpendicular to the main surface and the direction perpendicular to the reflecting surface and the average value of the formed angle for the plurality of mirrors is defined as a third difference,
The third difference with respect to the reflecting surface corresponding to the lens portion of the plurality of lens portions that is closest to the center position of the lens region is greater than the third difference with respect to the reflecting surface corresponding to the lens portion of the plurality of lens portions that is located at the outermost position of the lens region.
The light-emitting device according to claim 1 or 2 . The third difference increases as the distance from the center position of the lens region to the center position of the lens portion corresponding to the reflecting surface among the plurality of lens portions increases.
The light emitting device according to claim 3 . The light emitting device according to claim 3 , wherein a direction perpendicular to the reflecting surface projected onto the main surface is the same for all of the plurality of mirrors. The light emitting device according to claim 3 , wherein an angle formed between a direction perpendicular to the reflecting surface projected onto the main surface and an incident direction of the emitted light onto the reflecting surface is the same for all of the plurality of mirrors. further comprising a plurality of support portions disposed on the main surface;
The light emitting device according to claim 3 , wherein the plurality of mirrors are respectively supported on a plurality of supports. a base having a main surface;
a plurality of semiconductor laser chips mounted on the main surface and having optical axes parallel to the main surface;
a plurality of mirrors, each having a reflecting surface that reflects light emitted from each of the emission points of the plurality of semiconductor laser chips;
an optical member having a plurality of lens portions each receiving reflected light from the reflective surfaces of the plurality of mirrors;
When a distance from a center position of the emitted light on the reflecting surface to a center position of a lens portion of the plurality of lens portions corresponding to the reflecting surface is defined as a first distance in a plan view of the main surface,
the first distance to a lens portion of the plurality of lens portions that is closest to a center position of the lens region in which the plurality of lens portions are arranged is greater than the first distance to a lens portion of the plurality of lens portions that is located at the outermost position of the lens region in which the plurality of lens portions are arranged;
The output light from each of the plurality of lens portions is irradiated onto the inside of a predetermined surface area having an area smaller than that of the lens area,
When the angle between the direction perpendicular to the reflecting surface and the direction of the emitted light projected onto the main surface is defined as a second angle,
The second angle with respect to the reflecting surface corresponding to a lens portion of the plurality of lens portions that is closest to a center position of the lens region is larger than the second angle with respect to the reflecting surface corresponding to a lens portion of the plurality of lens portions that is located at the outermost position of the lens region.
Light-emitting device. The second angle increases as the distance from the center position of the lens region to the center position of the lens portion corresponding to the reflecting surface among the plurality of lens portions increases.
The light emitting device according to claim 8 . The light emitting device according to claim 8 , wherein a direction perpendicular to the reflecting surface projected onto the main surface is the same for all of the plurality of mirrors. The light emitting device according to claim 8 , wherein the angle of the direction perpendicular to the reflecting surface with respect to the main surface is the same for all of the plurality of mirrors. a base having a main surface;
a plurality of semiconductor laser chips mounted on the main surface and having optical axes parallel to the main surface;
a plurality of mirrors, each having a reflecting surface that reflects light emitted from each of the emission points of the plurality of semiconductor laser chips;
an optical member having a plurality of lens portions each receiving reflected light from the reflective surfaces of the plurality of mirrors;
When a distance from a center position of the emitted light on the reflecting surface to a center position of a lens portion of the plurality of lens portions corresponding to the reflecting surface is defined as a first distance in a plan view of the main surface,
the first distance to a lens portion of the plurality of lens portions that is closest to a center position of the lens region in which the plurality of lens portions are arranged is greater than the first distance to a lens portion of the plurality of lens portions that is located at the outermost position of the lens region in which the plurality of lens portions are arranged;
The output light from each of the plurality of lens portions is irradiated onto the inside of a predetermined surface area having an area smaller than that of the lens area,
When the angle formed between the direction of the optical axis of each of the plurality of lens portions and the direction perpendicular to the main surface is defined as a third angle,
The third angle of the lens portion located at the outermost position of the lens region among the plurality of lens portions is larger than the third angle of the lens portion located closest to the center position of the lens region among the plurality of lens portions.
Light-emitting device. The light emitting device according to claim 12 , wherein the third angle increases as the distance from the center of the lens region to the center of each of the plurality of lens portions increases. When an angle formed between the direction of the optical axis of each of the plurality of lens portions and the direction of the optical axis of the reflected light incident on each of the plurality of lens portions is defined as a fourth angle,
The fourth angle of the lens portion of the plurality of lens portions that is located at the outermost position of the lens region is larger than the fourth angle of the lens portion of the plurality of lens portions that is closest to the center position of the lens region.
14. The light emitting device according to claim 12 or 13. The light emitting device according to claim 14 , wherein the fourth angle increases as the distance from the center of the lens region to the center of each of the plurality of lens portions increases. The light emitting device according to claim 12 or 13 , wherein the optical axis of each of the plurality of lens portions intersects with the predetermined surface area. 14. The light emitting device according to claim 12, wherein, in a planar view of the main surface, a point on the surface of each of the plurality of lens portions through which the optical axis of each of the plurality of lens portions passes is located on a line segment connecting a center position of the lens region and a center position of the emitted light on the reflecting surface corresponding to each of the plurality of lens portions. a base having a main surface;
a plurality of semiconductor laser chips mounted on the main surface and having optical axes parallel to the main surface;
a plurality of mirrors, each having a reflecting surface that reflects light emitted from each of the emission points of the plurality of semiconductor laser chips;
an optical member having a plurality of lens portions each receiving reflected light from the reflective surfaces of the plurality of mirrors;
When a distance from a center position of the emitted light on the reflecting surface to a center position of a lens portion of the plurality of lens portions corresponding to the reflecting surface is defined as a first distance in a plan view of the main surface,
the first distance to a lens portion of the plurality of lens portions that is closest to a center position of the lens region in which the plurality of lens portions are arranged is greater than the first distance to a lens portion of the plurality of lens portions that is located at the outermost position of the lens region in which the plurality of lens portions are arranged;
The output light from each of the plurality of lens portions is irradiated onto the inside of a predetermined surface area smaller than the area of the lens area.
when an absolute value of a difference between a height from the principal surface to the emission point of each of the plurality of semiconductor laser chips and an average value of a height from the principal surface to the emission point of each of the plurality of semiconductor laser chips is defined as a first difference,
The first difference with respect to the emission point corresponding to a lens portion of the plurality of lens portions that is closest to a center position of the lens region is greater than the first difference with respect to the emission point corresponding to a lens portion of the plurality of lens portions that is located at the outermost position of the lens region.
Light-emitting device. The first difference increases as the distance from the center position of the lens region to the center position of the lens portion corresponding to the emission point among the plurality of lens portions increases.
19. The light emitting device according to claim 18. a base having a main surface;
a plurality of semiconductor laser chips mounted on the main surface and having optical axes parallel to the main surface;
a plurality of mirrors, each having a reflecting surface that reflects light emitted from each of the emission points of the plurality of semiconductor laser chips;
an optical member having a plurality of lens portions each receiving reflected light from the reflective surfaces of the plurality of mirrors;
When a distance from a center position of the emitted light on the reflecting surface to a center position of a lens portion of the plurality of lens portions corresponding to the reflecting surface is defined as a first distance in a plan view of the main surface,
the first distance to a lens portion of the plurality of lens portions that is closest to a center position of the lens region in which the plurality of lens portions are arranged is greater than the first distance to a lens portion of the plurality of lens portions that is located at the outermost position of the lens region in which the plurality of lens portions are arranged;
The output light from each of the plurality of lens portions is irradiated onto the inside of a predetermined surface area having an area smaller than that of the lens area,
When an absolute value of a difference between a height from the main surface to a center position of the reflecting surface and an average value of heights from the main surface to the center positions of the reflecting surfaces for the plurality of mirrors is defined as a second difference,
The second difference with respect to the reflecting surface corresponding to the lens portion of the plurality of lens portions that is closest to the center position of the lens region is larger than the second difference with respect to the reflecting surface corresponding to the lens portion of the plurality of lens portions that is located at the outermost position of the lens region.
Light-emitting device. The second difference increases as the distance from the center position of the lens region to the center position of a lens portion among the plurality of lens portions corresponding to each of the plurality of mirrors increases.
21. The light emitting device according to claim 20. The light emitting device according to any one of claims 18 to 21, wherein , in a planar view of the main surface, a center position of each of the plurality of lens portions coincides with a center position of the reflecting surface corresponding to each of the plurality of lens portions. the first distance increases as the distance from the center position of the emitted light to the center position of the lens region increases;
The light emitting device according to any one of claims 1 to 22. The light emitting device according to any one of claims 1 to 23 , wherein the output light is a condensed beam. When a distance from a center position of the reflecting surface to a center position of a lens portion of the plurality of lens portions corresponding to the reflecting surface is defined as a second distance in a plan view of the main surface,
The second distance to a lens portion of the plurality of lens portions that is closest to a center position of the lens region is greater than the second distance to a lens portion of the plurality of lens portions that is located at the outermost position of the lens region.
The light emitting device according to any one of claims 1 to 24. The second distance increases as the distance from the center of the reflecting surface to the center of the lens area increases.
26. The light emitting device of claim 25. The light emitting device according to any one of claims 1 to 26 , wherein a far-field pattern obtained by superimposing all of the output light in the predetermined surface area is circular. The cross-sectional shape of the output light has a major axis in the predetermined surface area, and the major axis is
28. The light emitting device of claim 27 , wherein all of the output light is uniformly dispersed.