Light source device and projection device

Abstract

To provide a light source device capable of reducing the difference between speckle noises per color.SOLUTION: A light source device comprises: a laser source emitting a first laser beam and a second laser beam different from the first laser beam in a color; a first lens through which the first laser beam and the second laser beam emitted from the laser source pass; and an optical member through which the first laser beam and the second laser beam emitted from the first lens pass. The optical member includes: a first surface capable of emitting the first laser beam and the second laser beam and arranged around a central axis along the travelling directions of the first laser beam and the second laser beam in the optical member; and a second surface arranged around the first surface. The first surface reflects the second laser beam while transmitting the first laser beam therethrough. The second surface reflects the first laser beam transmitting through the first surface.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a light source device and a projection device. [Background technology]

[0002] Conventionally, a light source device that emits laser light and a projection device such as a projector that includes the light source device are known. For example, Patent Document 1 discloses a configuration that includes a first collimating optical system that receives a light beam emitted from a light source, a focusing optical system provided after the first collimating optical system, and a rod provided after the focusing optical system in order to reduce speckle noise. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-41564 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the configuration described in Patent Document 1, when a plurality of light beams of different colors are incident on an optical member such as a rod, the effect of reducing speckle noise differs for each of the plurality of light beams.

[0005] An object of an embodiment of the present disclosure is to provide a light source device capable of reducing the difference in speckle noise between colors. [Means for solving the problem]

[0006] A light source device according to one embodiment of the present disclosure includes a laser light source that emits a first laser light and a second laser light having a color different from the first laser light, a first lens through which the first laser light and the second laser light emitted from the laser light source pass, and an optical member through which each of the first laser light and the second laser light emitted from the first lens passes, wherein the optical member is capable of emitting the first laser light and the second laser light, and has a first surface arranged around a central axis along a traveling direction of the first laser light and the second laser light in the optical member, and a second surface arranged around the first surface, wherein the first surface reflects the second laser light and transmits the first laser light, and the second surface reflects the first laser light that has transmitted through the first surface. Effect of the Invention

[0007] According to an embodiment of the present disclosure, a light source device capable of reducing the difference in speckle noise between colors can be provided. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic cross-sectional view showing an example of the configuration of a light source device according to a first embodiment. [Diagram 2] 1 is a schematic plan view showing an example of the configuration of a laser light source included in a light source device according to a first embodiment. [Diagram 3] 3 is a schematic cross-sectional view showing an example of the configuration of an optical member included in the light source device according to the first embodiment. FIG. [Figure 4] 4A to 4C are diagrams illustrating an example of a two-dimensional irradiance distribution of a first laser light emitted from a laser light source included in the light source device according to the first embodiment and before being incident on an optical member. [Diagram 5] 4A to 4C are diagrams illustrating an example of how a first laser light passes through an optical member included in the light source device according to the first embodiment. [Figure 6] 4A to 4C are diagrams illustrating an example of a two-dimensional irradiance distribution of a first laser light emitted from an optical member included in the light source device according to the first embodiment. [Figure 7]FIG. 7 is a diagram illustrating an example of the irradiance distribution in FIG. 6. [Figure 8] 4A to 4C are diagrams illustrating an example of a two-dimensional irradiance distribution of a second laser light emitted from a laser light source included in the light source device according to the first embodiment and before being incident on an optical member. [Figure 9] 5A to 5C are diagrams illustrating an example of a state in which a second laser light passes through an optical member included in the light source device according to the first embodiment. [Figure 10] 5A to 5C are diagrams illustrating an example of a two-dimensional irradiance distribution of a second laser light emitted from an optical member included in the light source device according to the first embodiment. [Figure 11] FIG. 11 is a diagram illustrating an example of the irradiance distribution in FIG. [Figure 12] 13 is a diagram showing a two-dimensional irradiance distribution of a second laser light emitted from an optical member included in a light source device according to a reference example. FIG. [Figure 13] FIG. 13 is a diagram showing the irradiance distribution in FIG. 12. [Figure 14] 13 is a schematic cross-sectional view showing an example of the configuration of an optical member included in a light source device according to a second embodiment. FIG. [Figure 15] 13 is a diagram showing an example of a two-dimensional irradiance distribution of a first laser light emitted from a laser light source included in a light source device according to a second embodiment and before being incident on an optical member. FIG. [Figure 16] 13 is a diagram showing an example of a state in which a first laser light passes through an optical member included in a light source device according to a second embodiment. FIG. [Figure 17] 13 is a diagram showing an example of a two-dimensional irradiance distribution of a first laser light emitted from an optical member included in the light source device according to the second embodiment. FIG. [Figure 18] FIG. 18 is a diagram illustrating an example of the irradiance distribution in FIG. 17. [Figure 19] 13 is a schematic cross-sectional view showing an example of the configuration of an optical member included in a light source device according to a third embodiment. FIG. [Figure 20] FIG. 11 is a schematic cross-sectional view showing an example of the configuration of a projection device according to a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A light source device and a projection device according to an embodiment of the present disclosure will be described in detail with reference to the drawings. However, the following embodiments are merely illustrative of light source devices and projection devices for embodying the technical ideas of the present disclosure, and are not limited to the following. Furthermore, unless otherwise specified, the dimensions, materials, shapes, and relative arrangements of the components described in the embodiments are merely illustrative examples, and are not intended to limit the scope of the present disclosure to those alone. Note that the size, positional relationship, etc. of the components shown in each drawing may be exaggerated to clarify the explanation. In addition, in the following explanation, the same names and symbols indicate the same or homogeneous components, and detailed explanations will be omitted as appropriate. An end view showing only a cut surface may be used as a cross-sectional view.

[0010] In each drawing, a Cartesian coordinate system with an X-axis, a Y-axis, and a Z-axis is used to represent directions. The X-axis, the Y-axis, and the Z-axis are mutually perpendicular. The direction in which the arrow points in the X direction along the X axis is indicated as the +X direction, and the opposite direction to the +X direction is indicated as the -X direction. The direction in which the arrow points in the Y direction along the Y axis is indicated as the +Y direction, and the opposite direction to the +Y direction is indicated as the -Y direction. The direction in which the arrow points in the Z direction along the Z axis is indicated as the +Z direction, and the opposite direction to the +Z direction is indicated as the -Z direction.

[0011] In the light source device according to the embodiment, the first laser light and the second laser light emitted from the laser light source included in the light source device travel in the +Z direction inside the optical member included in the light source device. That is, the traveling direction of the first laser light and the second laser light in the optical member is a direction along the Z direction. From another perspective, the traveling direction corresponds to the Z direction of the central axis of the light propagation direction in the optical member. For example, in FIG. 1 and FIG. 3, the Z direction is a direction along the normal to the light emission surface of the optical member. Also, a view of an object viewed from the normal direction of the object is called a plan view. However, the terms indicating these specific directions and positions are merely used to make the relative directions and positions in the referenced drawings easier to understand. These directional expressions do not limit the orientation of the light source device and the projection device according to the embodiment when used, and the orientation of the light source device and the projection device according to the embodiment when used is arbitrary.

[0012] In the following embodiments, "along the X-axis, Y-axis, and Z-axis" includes an object having a tilt within a range of ±10 degrees with respect to these axes. In the embodiments, each of the perpendicular and perpendicular directions may have an error within ±10 degrees with respect to 90 degrees.

[0013] In addition, in this specification or claims, when there are multiple elements of a certain type and each element is to be expressed with a distinction, the elements may be distinguished by adding "first," "second," etc. to the beginning of the element. In addition, the objects to be distinguished may differ between this specification and the claims. Therefore, even if the claims describe an element with the same notation as this specification, the object identified by this element may not match between this specification and the claims.

[0014] [First embodiment] <Configuration of the light source device according to the first embodiment> The configuration of the light source device according to the first embodiment will be described with reference to Figs. 1 to 3. Fig. 1 is a schematic cross-sectional view showing an example of the configuration of the light source device 100 according to the first embodiment. Fig. 1 shows a cross-section of the light source device 100 cut along a virtual plane (e.g., YZ plane) including the central axis 30 of the optical member 3 included in the light source device 100. Fig. 2 is a schematic plan view showing an example of the configuration of the laser light source 1. Fig. 3 is a schematic cross-sectional view showing an example of the configuration of the optical member 3 included in the light source device 100. Fig. 3 shows a cross-section of the optical member 3 cut along a virtual plane (e.g., XZ plane) including the central axis 30 of the optical member 3, and also shows how the first laser light L1 and the second laser light L2 pass through the inside of the optical member 3.

[0015] As shown in FIG. 1, the light source device 100 includes a laser light source 1 that emits a first laser light L1 and a second laser light L2 that is different in color from the first laser light L1. The light source device 100 also includes a first lens 2 through which the first laser light L1 and the second laser light L2 emitted from the laser light source 1 pass, and an optical member 3 through which the first laser light L1 and the second laser light L2 emitted from the first lens 2 pass. The optical member 3 can emit the first laser light L1 and the second laser light L2. As shown in FIG. 3, the optical member 3 has a first surface 31 arranged around a central axis 30 along the traveling direction of the first laser light L1 and the second laser light L2 in the optical member 3, and a second surface 32 arranged around the first surface 31. The first surface 31 reflects the second laser light L2 and transmits the first laser light L1. The second surface 32 reflects the first laser light L1 having been transmitted through the first surface 31.

[0016] For example, in a light source device that emits multiple laser beams of different colors from an optical member, the multiple laser beams have different emission positions and emission angles from the laser light source. Furthermore, the number of laser elements included in the laser light source may differ for each color. For this reason, when the multiple laser beams travel inside the optical member in the +Z direction, the irradiance distribution on the light emission surface of the optical member may not be sufficiently averaged for each laser beam of each color. In this case, color unevenness may occur in the multiple laser beams on the light emission surface of the optical member. If there is color unevenness, the speckle noise reduction effect for each of the multiple laser beams differs for each position on the irradiation surface of the laser beam, resulting in a difference in speckle noise for each color. For example, when the light source device 100 is mounted on a projector, the irradiation surface of the laser beam is a screen. In addition, in order to reduce speckle noise, when multiple laser lights emitted from a light source device are made to enter an optical system having an angle multiplexing function such as a fly-eye lens, the emission positions and emission angles from the laser light source of multiple laser lights of different colors, the number of laser elements included in the laser light source, etc. are different, as in the above case. Therefore, the incidence angles and incidence ranges of the laser lights into the optical system are different. In this case, the irradiance distribution of the laser lights after passing through the optical system is different for each color, so color unevenness may occur on the surface irradiated with the laser light even if the effect of angle multiplexing by the optical system is utilized. Therefore, the speckle noise reduction effect for each of the multiple laser lights differs for each position on the surface irradiated with the laser light, and thus differences in speckle noise for each color may occur.

[0017] In the light source device 100, the optical path through which the first laser light L1 passes in the optical member 3 is different from the optical path through which the second laser light L2 passes in the optical member 3, so that it is possible to adjust the number of times that the first laser light L1 and the second laser light L2 are reflected by the optical member 3 when propagating through the optical member 3. This makes it possible to make the degree of variation in the irradiance distribution of the first laser light L1 and the second laser light L2 on the light output surface of the optical member 3 about the same, and to reduce color unevenness of the first laser light L1 and the second laser light L2 on the light output surface of the optical member 3. In addition, even when the first laser light L1 and the second laser light L2 emitted from the light source device 100 are incident on an optical system having an angle multiplexing function such as a fly-eye lens, it is possible to reduce the difference in the incidence angle, incidence range, etc. of the first laser light L1 and the second laser light L2 into the optical system according to the respective colors. As a result, in this embodiment, it is possible to provide light source device 100 that can reduce the difference in speckle noise reduction effect for each of the first laser light L1 and the second laser light L2 and reduce the difference in speckle noise for each color.

[0018] In the example shown in FIG. 1 to FIG. 3, the first laser light L1 is a red laser light. The second laser light L2 includes a green laser light and a blue laser light. The red laser light is a laser light having a peak wavelength in the range of 605 nm to 750 nm. The green laser light is a laser light having a peak wavelength in the range of 495 nm to 570 nm. The blue laser light is a laser light having a peak wavelength in the range of 420 nm to 495 nm. The light source device 100 can reduce the difference in speckle noise between the colors in the first laser light L1 and the second laser light L2 and emit them. Note that the second laser light L2 is not limited to including both the green laser light and the blue laser light, but may include at least one of the green laser light and the blue laser light.

[0019] In the example shown in FIG. 1 to FIG. 3, the laser light source 1 includes a first laser light source 11 that emits a plurality of red first laser lights L1, and a second laser light source 12 that emits a plurality of green laser lights and a plurality of blue laser lights. The first laser light source 11 is disposed away from the second laser light source 12. The first laser light source 11 includes a first semiconductor laser element 111. The second laser light source 12 includes a second semiconductor laser element 121 and a third semiconductor laser element 122. In the example shown in FIG. 2, the first semiconductor laser element 111 is disposed on the first substrate 110, and the second semiconductor laser element 121 and the third semiconductor laser element 122 are disposed on the second substrate 120 that is disposed away from the first substrate 110. In the light source device 100, by disposing the first laser light source 11 away from the second laser light source 12, the influence of heat generation of the second laser light source 12 on the first laser light source 11 can be reduced.

[0020] In the example shown in FIG. 2, the first laser light source 11 includes five first semiconductor laser elements 111 each emitting a red laser beam. The second laser light source 12 includes three second semiconductor laser elements 121 each emitting a green laser beam and two third semiconductor laser elements 122 each emitting a blue laser beam. The number of the first semiconductor laser elements 111 is greater than the number of the second semiconductor laser elements 121 and greater than the number of the third semiconductor laser elements 122. The first semiconductor laser elements 111 are greatly affected by a decrease in optical output and a wavelength shift due to a rise in temperature. In order to reduce these effects, it is preferable to dispose the first laser light source 11 including the first semiconductor laser elements 111 and the second laser light source 12 including the second semiconductor laser elements 121 and the third semiconductor laser elements 122 apart from each other.

[0021] By making the number of the first semiconductor laser elements 111 greater than the number of the second semiconductor laser elements 121 and greater than the number of the third semiconductor laser elements 122, the white laser light emitted from the light source device 100 can be adjusted to a predetermined color temperature. Here, in this specification, the color temperature also includes the correlated color temperature. For example, the color temperature may be 5000K or more and 9000K or less, preferably 6000K or more and 7000K or less, and more preferably 6500K. From the viewpoint of adjusting the color temperature of the white laser light in the range of 6000K to 7000K, it is preferable that the number of the first semiconductor laser elements 111 is greater than the number of the second semiconductor laser elements 121, and the number of the second semiconductor laser elements 121 is greater than the number of the third semiconductor laser elements 122. Usually, when the number of semiconductor laser elements differs for each emission color, the total emission area for each color differs. In this case, due to differences in etendue, the irradiance distribution at the light exit surface 34 of the optical member 3 is not uniform for each color, and color unevenness occurs at the light exit surface 34, so that the speckle noise reduction effect differs for each color. However, in the light source device 100, by providing the configuration of the optical member 3, color unevenness at the light exit surface 34 is reduced even if there is a difference in the number of semiconductor laser elements that emit different colors, and the difference in the speckle noise reduction effect for each color is reduced. The details of the configuration of the optical member 3 will be described later. However, the number of first semiconductor laser elements 111, second semiconductor laser elements 121, and third semiconductor laser elements 122 may be any number as long as they are plural. In addition, the arrangement of first semiconductor laser elements 111, second semiconductor laser elements 121, and third semiconductor laser elements 122 is not limited to that shown in FIG. 2 and can be changed as appropriate depending on the application of light source device 100, etc.

[0022] It is preferable to use, for example, a III-V group compound semiconductor for each of the first semiconductor laser element 111, the second semiconductor laser element 121, and the third semiconductor laser element 122. Examples of III-V group compound semiconductors include at least one of GaN, InGaN, AlGaN, GaAs, AlGaInP, InGaAsP, and AlGaAs.

[0023] In the example shown in FIG. 2, the first laser light source 11 and the second laser light source 12 are arranged side by side in the Y direction. The five first semiconductor laser elements 111 are arranged side by side in the X direction. The three second semiconductor laser elements 121 and the two third semiconductor laser elements 122 are arranged side by side in the X direction. When the first semiconductor laser element 111, the second semiconductor laser element 121, and the third semiconductor laser element 122 are edge-emitting semiconductor laser elements, the first laser light source 11 and the second laser light source 12 may have the following configuration. That is, each of the five first semiconductor laser elements 111 emits the first laser light L1 in any direction in the XY plane, and raises the first laser light L1 in the +Z direction by a mirror before emitting it. Each of the three second semiconductor laser elements 121 emits the green second laser light L2 in any direction in the XY plane, and raises the green laser light L2 in the +Z direction by a mirror before emitting it. Each of the two third semiconductor laser elements 122 emits the blue second laser light L2 in any direction in the XY plane, and emits it in the +Z direction by a mirror. When the first semiconductor laser element 111, the second semiconductor laser element 121, and the third semiconductor laser element 122 are vertical cavity surface emitting laser elements, the resonance direction may be the +Z direction.

[0024] In the example shown in FIG. 1 and FIG. 3, the first laser light L1 emitted from the first laser light source 11 and the second laser light L2 emitted from the second laser light source 12 pass through the first lens 2 and then pass through the light incident surface 33 of the optical member 3 to enter the inside of the optical member 3. The first laser light L1 that has entered the inside of the optical member 3 passes through the optical member 3 while repeatedly passing through the first surface 31 and reflecting off the second surface 32. On the other hand, the second laser light L2 that has entered the inside of the optical member 3 passes through the optical member 3 while repeatedly reflecting off the first surface 31. The first laser light L1 and the second laser light L2 that have passed through the optical member 3 are emitted from the optical member 3 through the light exit surface 34 of the optical member 3. By adopting such a configuration, the number of reflections of the first laser light L1 and the second laser light L2 within the optical member 3 can be adjusted. The irradiance distribution for each color becomes substantially uniform on the light exit surface 34, reducing color unevenness on the light exit surface 34. The radiation angle distribution on the light exit surface 34 also becomes substantially uniform. Therefore, the difference in the speckle noise reduction effect for each color becomes smaller.

[0025] The first lens 2 can be made of a material including a glass material, an optical crystal, or a resin material having translucency for each of the first laser light L1 and the second laser light L2 emitted from the laser light source 1. For example, in the case of an application in which the power of the laser light is relatively low, such as a head mounted display, a resin material can also be used. The translucency of the first lens 2 is preferably such that the transmittance for each of the first laser light L1 and the second laser light L2 emitted from the laser light source 1 is 90% or more, 95% or more, or 98% or more. In addition, the first lens 2 can be made of a plano-convex single lens, a biconvex single lens, a meniscus single lens, a Fresnel lens, a diffractive lens, a lens set consisting of a plurality of single lenses, or the like. The first lens 2 may include at least one of a spherical lens and an aspherical lens. The type, arrangement, shape, etc. of the first lens 2 can be appropriately changed according to the specifications of the light source device 100, etc.

[0026] In the example shown in FIG. 3, the optical member 3 includes a first optical member 35 and a second optical member 36 provided so as to surround the first optical member 35. The shape of the optical member 3 as viewed from the +Z direction (for example, the normal direction of the light exit surface 34) is substantially rectangular. That is, the optical member 3 is a quadrangular prism member. The shape of the first optical member 35 as viewed from the +Z direction is substantially rectangular. That is, the first optical member 35 is a quadrangular prism member. The shape of the second optical member 36 as viewed from the +Z direction is substantially rectangular. That is, the second optical member 36 is a quadrangular tube member. The central axes of the optical member 3, the first optical member 35, and the second optical member 36 are substantially aligned. However, the shapes of the optical member 3, the first optical member 35, and the second optical member 36 as viewed from the +Z direction may be substantially polygonal or the like. The shape of the second optical member 36 being substantially polygonal when viewed from the +Z direction means that the outer edge of the area defined by the second surface 32 is substantially polygonal. For example, the second optical member 36, which is a quadrangular prism, may be joined to each side surface of the first optical member 35, which is a polygonal prism. The first optical member 35 may be a quadrangular prism, a hexagonal prism, an octagonal prism, or the like. The central axes of the optical member 3, the first optical member 35, and the second optical member 36 do not necessarily have to coincide with each other.

[0027] The optical member 3 may be made of a glass material, optical crystal, or resin material that is translucent to each of the first laser light L1 and the second laser light L2 emitted from the laser light source 1. A glass material or an optical crystal is preferably used for the optical member 3. The translucency of the optical member 3 is preferably such that the optical member 3 has a transmittance of 90% or more, 95% or more, or 98% or more for each of the first laser light L1 and the second laser light L2 emitted from the laser light source 1.

[0028] In the example shown in FIG. 3, the first surface 31 constitutes at least one of the outer peripheral surface of the first optical member 35 and the inner peripheral surface of the second optical member 36. The first surface 31 is, for example, a dichroic mirror surface. The dichroic mirror surface of the first surface 31 transmits the first laser light L1 and reflects the second laser light L2. In the light source device 100, the first surface 31 is a dichroic mirror surface, so that the configuration of the light source device 100 can be simplified. The first surface 31 can be configured to include a dielectric multilayer film or the like. The dielectric multilayer film of the first surface 31 can be disposed on at least one of the outer peripheral surface of the first optical member 35 and the inner peripheral surface of the second optical member 36.

[0029] In the example shown in FIG. 3, the second surface 32 constitutes the outer peripheral surface of the second optical member 36. The second surface 32 is, for example, a total reflection surface. The total reflection surface of the second surface 32 totally reflects at least the first laser light L1. However, the second surface 32 may be configured to include a metal film, a dielectric multilayer film, or the like. In this case, the metal film or dielectric multilayer film, or the like of the second surface 32 can be disposed on the outer peripheral surface of the second optical member 36. The metal film or dielectric multilayer film, or the like of the second surface 32 reflects at least the first laser light L1.

[0030] Such an optical member 3 can be formed by bonding a first optical member 35 and a second optical member 36 by a method such as optical contact or hydroxyl group bonding. At this time, a dichroic mirror made of a dielectric multilayer film is formed in advance on either the first optical member 35 or the second optical member 36.

[0031] <Example of irradiance> The irradiance of the laser light in each of the light source device according to the first embodiment and the light source device according to the reference example will be described with reference to Figs. 4 to 13. The irradiance of the laser light in Figs. 4 to 13 was obtained by simulation using Zemax OpticStudio, which is optical design and analysis software. In the simulation results, a two-dimensional irradiance distribution is shown as an image. The brighter the brightness of a pixel in the image, the higher the irradiance. These points are also true for the simulation of irradiance shown below.

[0032] Fig. 4 to Fig. 7 are diagrams showing the irradiance of the first laser light L1 in the light source device 100 according to the first embodiment. Fig. 8 to Fig. 11 are diagrams showing the irradiance of the second laser light L2 in the light source device 100 according to the first embodiment. Fig. 4 to Fig. 11 show the irradiance of the first laser light L1 and the second laser light L2 in the light source device 100 that are incident on the optical member 3, pass through the optical member 3, and then are emitted from the optical member 3.

[0033] 12 and 13 are diagrams showing the irradiance of laser light in a light source device according to a reference example. The light source device according to the reference example emits laser light that is emitted from a laser light source and passes through an optical member. The optical member included in the light source device according to the reference example differs from the optical member 3 in that it does not have a surface (for example, the first surface 31 of the optical member 3) that is disposed inside the optical member. That is, the light source device according to the reference example differs from the light source device 100 in that the first laser light corresponding to the first laser light L1 and the second laser light corresponding to the second laser light L2 pass through the inside of the optical member while being reflected by the outer peripheral surface of the optical member (the surface corresponding to the second surface 32 of the optical member 3).

[0034] Fig. 4 is a diagram showing an example of a two-dimensional irradiance distribution of the first laser light L1 emitted from the laser light source 1 and before being incident on the optical member 3. Fig. 4 shows the two-dimensional irradiance distribution of five first laser lights L1 viewed from the +Z direction.

[0035] Fig. 5 is a diagram showing an example of how the first laser light L1 passes through the inside of the optical member 3. Fig. 5 shows the first laser light L1 passing through the inside of the optical member 3 as viewed from the +Y direction. In the example shown in Fig. 5, each of the multiple lines inside the optical member 3 represents a beam of the first laser light L1 passing through the inside of the optical member 3.

[0036] Fig. 6 is a diagram showing an example of a two-dimensional irradiance distribution of the first laser light L1 emitted from the optical member 3. Fig. 6 shows a two-dimensional irradiance distribution of the first laser light L1 at the position of the light emission surface 34 as viewed from the -Z direction.

[0037] Fig. 7 is a diagram in which the irradiance distribution of the light exit surface 34 in Fig. 6 is integrated in the Y direction. The horizontal axis of Fig. 7 represents the position in the X direction, and the vertical axis represents the integrated intensity in the Y direction. As shown in Fig. 7, the first laser L1 emitted from the optical member 3 has a top-hat shaped irradiance distribution in which the irradiance distribution near the peak irradiance is almost flat.

[0038] Fig. 8 is a diagram showing an example of a two-dimensional irradiance distribution of the second laser light L2 emitted from the laser light source 1 and before being incident on the first optical member 35 of the optical member 3. Fig. 8 shows two-dimensional irradiance distributions of five second laser lights L2 viewed from the +Z direction. Of the five second laser lights L2 shown in Fig. 8, three are green laser lights L21 and two are blue laser lights L22.

[0039] 9 is a diagram showing an example of the second laser light L2 passing through the inside of the first optical member 35. FIG. 9 shows the second laser light L2 passing through the inside of the first optical member 35 as viewed from the +Y direction. Each of the multiple lines in the inside of the first optical member 35 in FIG. 9 represents a ray of the second laser light L2 passing through the inside of the first optical member 35. The ray shown by the gray solid line represents the green laser light L21, and the ray shown by the black solid line represents the blue laser light L22. FIG. 9 suggests that the green laser light L21 and the blue laser light L22 are each distributed approximately uniformly on the light emission surface 34.

[0040] Fig. 10 is a diagram showing an example of a two-dimensional irradiance distribution of the second laser light L2 emitted from the optical member 3. Fig. 10 shows a two-dimensional irradiance distribution of the second laser light L2 at the position of the light emission surface 34 as viewed from the -Z direction.

[0041] Fig. 11 is a diagram in which the irradiance distribution of the light exit surface 34 in Fig. 10 is integrated in the Y direction. The horizontal axis of Fig. 11 represents the position in the X direction, and the vertical axis represents the integrated intensity in the Y direction. As shown in Fig. 11, the second laser light L2 emitted from the optical member 3 has a top hat irradiance distribution. The integrated intensity of the irradiance distribution shown in Fig. 11 is formed because the irradiance distributions of the green laser light L21 and the blue laser light L22 are both approximately top hat shaped at the light exit surface 34.

[0042] 12 is a diagram showing a two-dimensional irradiance distribution of the second laser light L2X emitted from an optical member included in a light source device according to a reference example. FIG. 12 shows a two-dimensional irradiance distribution of the second laser light L2X at the position of the light emission surface of the optical member as viewed from the -Z direction. In the light source device according to the reference example, the second laser light L2X passes through the optical member while being reflected by the outer peripheral surface of the optical member (the surface corresponding to the second surface 32 of the optical member 3). Therefore, the magnitude of the radiant flux of the second laser light L2X at the position of the light emission surface of the optical member is approximately the same as the magnitude of the radiant flux of the first laser light L1 in FIG. 6.

[0043] FIG. 13 is a diagram in which the irradiance distribution of the light exit surface of FIG. 12 is integrated in the Y direction. The horizontal axis of FIG. 13 represents the position in the X direction, and the vertical axis represents the integrated intensity in the Y direction. As shown in FIG. 13, the second laser L2X emitted from the optical member included in the light source device according to the reference example has an irradiance distribution that is more different from the top hat shape than the irradiance distribution of the first laser light L1 shown in FIG. 7 or the irradiance distribution of the second laser light L2 shown in FIG. 11. In particular, when comparing the irradiance distribution of the second laser light L2, the result shown in FIG. 11 is closer to the top hat shape than the result shown in FIG. 13. Therefore, in the case of laser light containing green and blue, it can be seen that the irradiance distribution averaged in the light exit surface can be obtained by propagating only the first optical member 35 of the optical member 3.

[0044] Here, since there are various differences in the conditions of the laser light, such as the wavelength, the number of light sources, the entrance pupil, and the beam spread angle, the laser light cannot be used under the same conditions. On the other hand, it is known that speckle noise is related to light intensity. In the light source device 100, the irradiance distribution of the laser light emitted from the optical member 3 can be made to approximate a top hat shape for each color and averaged. The top hat shape is derived from the fact that the laser light is reflected many times within the optical member 3 and is emitted from the light emission surface 34 at various angles for each color. In the light source device 100, by obtaining an irradiance distribution in a shape close to a top hat shape, the speckle noise for each color can be reduced by the effect of angle multiplexing. For example, in the light source device 100, it is possible to reduce the occurrence of a phenomenon in which only red, only green, or only blue flickers due to speckle noise.

[0045] 4 to 11, it is desirable that the irradiance distribution has a top hat shape in terms of the integrated intensity in the Y direction. Here, the top hat shape also includes a state in which the maximum and minimum values ​​of the integrated intensity in the Y direction at the light exit surface 34 deviate from the average value of the integrated intensity by 15% or less, preferably 10% or less, or 5% or less.

[0046] [Second embodiment] Next, a light source device according to a second embodiment will be described. Note that the same names and symbols as those in the already described embodiments indicate the same or similar members or configurations, and detailed descriptions will be omitted as appropriate. This also applies to the following embodiments.

[0047] The light source device according to the second embodiment differs from the light source device 100 according to the first embodiment in that it includes an optical member 3a.

[0048] Fig. 14 is a schematic cross-sectional view showing an example of the configuration of an optical member 3a included in a light source device according to the second embodiment. Fig. 14 shows a cross section of the optical member 3a cut along a virtual plane (e.g., an XZ plane) including a central axis 30 of the optical member 3a, and shows how the first laser light L1 and the second laser light L2 pass through the inside of the optical member 3a. The optical member 3a differs from the optical member 3 in the light source device 100 in that it includes a second surface 32a having an inverse tapered shape that widens in a direction from the light incident surface 33 toward the light exit surface 34.

[0049] In the example shown in FIG. 14, the optical member 3a includes a first optical member 35 and a second optical member 36a provided so as to surround the first optical member 35. The shape of the optical member 3a as viewed from the +Z direction (for example, the normal direction of the light exit surface 34) is substantially rectangular. That is, the optical member 3a is a member having a truncated quadrangular pyramid shape. The shape of the second optical member 36a as viewed from the +Z direction is substantially rectangular. That is, the second optical member 36a is a member having a truncated quadrangular pyramid shape with a rectangular through hole inside into which the first optical member 35 can be inserted. The central axes of the optical member 3a, the first optical member 35, and the second optical member 36a are substantially aligned. However, the shapes of the optical member 3, the first optical member 35, and the second optical member 36a as viewed from the +Z direction may be substantially polygonal or the like. The central axes of the optical member 3a, the first optical member 35, and the second optical member 36a do not necessarily have to be aligned. The configuration of the optical member 3a is not limited to a configuration in which the first optical member 35 and the second optical member 36a are combined, as long as the optical member 3a has a first surface and a second surface. The optical member 3a may be a configuration in which a plurality of second optical members 36a are bonded to each side surface of the first optical member 35 by a method such as optical contact or hydroxyl group bonding. In this case, it is desirable that the second optical member 36a is bonded to the first optical member 35 so that the cross section including the central axis of the first optical member 35 has substantially the same cross section in the XZ plane and the YZ plane.

[0050] Fig. 15 is a diagram showing an example of a two-dimensional irradiance distribution of the first laser light L1 emitted from the laser light source included in the light source device according to the second embodiment and before being incident on the optical member 3a. Fig. 15 shows the two-dimensional irradiance distribution of five first laser lights L1 as viewed from the +Z direction.

[0051] Fig. 16 is a diagram showing an example of the first laser light L1 passing through the inside of the optical member 3a. Fig. 16 shows the first laser light L1 passing through the inside of the optical member 3a as viewed from the +Y direction. In the example shown in Fig. 16, each of the multiple lines inside the optical member 3a represents a ray of the first laser light L1 passing through the inside of the optical member 3a.

[0052] Fig. 17 is a diagram showing an example of the irradiance distribution of the first laser light L1 emitted from the optical member 3a. Fig. 17 shows a two-dimensional irradiance distribution of the first laser light L1 at the position of the light emission surface 34 as viewed from the -Z direction.

[0053] Fig. 18 is a diagram in which the irradiance distribution of the light exit surface in Fig. 17 is integrated in the Y direction. The horizontal axis of Fig. 18 represents the position in the X direction, and the vertical axis represents the integrated intensity in the Y direction. As shown in Fig. 18, the first laser L1 emitted from the optical member 3a has a top-hat shaped irradiance distribution in which the irradiance distribution near the peak irradiance is almost flat.

[0054] The irradiance distribution of the second laser light L2 in the second embodiment is similar to that of the second laser light L2 in the light source device 100 according to the first embodiment. Therefore, in the light source device according to the second embodiment, it is possible to obtain an irradiance distribution close to a top hat shape in each of the first laser light L1 and the second laser light L2. This makes it possible to reduce speckle noise for each color by the effect of angle multiplexing.

[0055] In addition, for example, when the number or arrangement positions of the first laser light source 11 and the second laser light source 12 constituting the laser light source 1 are different, the difference in the incidence angle between the first laser light L1 and the second laser light L2 to the optical member may become large. When the difference in the incidence angle is large, the difference in the number of reflections in the optical member becomes large, and the difference in the uniformity of the illuminance becomes large. As a result, the difference in the reduction effect of the speckle noise between the first laser light L1 and the second laser light L2 may become large. In the light source device according to the second embodiment, the second surface 32a of the optical member 3a is made to have an inverse tapered shape, so that the number of reflections in the optical member 3a between the first laser light L1 and the second laser light L2 can be made close to each other. Therefore, even when the difference in the incidence angle between the first laser light L1 and the second laser light L2 to the optical member 3a is large, the difference in the uniformity of the irradiance distribution can be reduced, and the difference in the reduction effect of the speckle noise between the first laser light L1 and the second laser light L2 can be reduced. As a result, the difference in the speckle noise for each color can be reduced.

[0056] The other effects and advantages are the same as those of the first embodiment.

[0057] [Third embodiment] Next, a description will be given of a light source device according to a third embodiment. The light source device according to the third embodiment differs from the light source device according to the second embodiment in that it includes an optical member 3b.

[0058] Fig. 19 is a schematic cross-sectional view showing an example of the configuration of an optical member 3b included in a light source device according to the third embodiment. Fig. 19 shows a cross-section of the optical member 3b cut along a virtual plane (for example, an XZ plane) including the central axis 30 of the optical member 3b, and shows how the first laser light L1 and the second laser light L2 pass through the inside of the optical member 3b. The optical member 3b differs from the optical member 3a in the second embodiment in that it has a first surface 31b. The first surface 31b includes a first region 31b1 parallel to the direction from the light incident surface 33 to the light exit surface 34, and a second region 31b2 extending in the direction from the light incident surface 33 to the light exit surface 34. The first region 31b1 is located closer to the light incident surface 33 than the second region 31b2.

[0059] In the example shown in FIG. 19, the optical member 3b includes a first optical member 35b and a second optical member 36b provided so as to surround the first optical member 35b. The shape of the optical member 3b as viewed from the +Z direction (for example, the normal direction of the light exit surface 34) is substantially rectangular. That is, the optical member 3b is a member having a quadrangular pyramid shape. The central axes of the optical member 3b, the first optical member 35b, and the second optical member 36b are substantially aligned. However, the shapes of the optical member 3b, the first optical member 35b, and the second optical member 36b as viewed from the +Z direction may be substantially polygonal or the like. The central axes of the optical member 3b, the first optical member 35b, and the second optical member 36b do not necessarily have to be aligned. The configuration of the optical member 3b is not limited to a configuration in which the first optical member 35b and the second optical member 36b are combined, as long as the optical member 3b has a first surface and a second surface.

[0060] In this embodiment, by providing the optical member 3b, the size of the radiant flux of the first laser light L1 and the size of the radiant flux of the second laser light L2 can be made close to each other at the position of the light exit surface 34. As a result, when the first laser light L1 and the second laser light L2 emitted from the optical member 3b are made incident on an optical system having an angle multiplexing function located in a subsequent stage, the difference in the reduction effect of speckle noise due to angle multiplexing between the first laser light L1 and the second laser light L2 can be reduced. As a result, the difference in speckle noise for each color can be reduced. For example, if the first surface 31b and the second surface 32a are configured so that the size of the radiant flux of the first laser light L1 and the size of the radiant flux of the second laser light L2 are almost the same at the position of the light exit surface 34, the difference in the reduction effect of speckle noise due to angle multiplexing can be minimized.

[0061] Furthermore, in this embodiment, the length N1 of the first region 31b1 can be set to 50% or more and 80% or less of the length N0 of the optical member 3b in the direction from the light incident surface 33 to the light emitting surface 34. This allows the magnitude of the radiant flux of the first laser light L1 to be close to the magnitude of the radiant flux of the second laser light L2 at the position of the light emitting surface 34.

[0062] The other effects and advantages are the same as those of the second embodiment.

[0063] [Fourth embodiment] Next, a projection device according to a fourth embodiment will be described.

[0064] Fig. 20 is a schematic cross-sectional view showing an example of the configuration of a projection device 200 according to a fourth embodiment. Fig. 20 shows a cross section of the projection device 200 taken along a virtual cross section (e.g., a YZ plane) including the central axis 30 of the optical member 3 of the light source device 100 included in the projection device 200.

[0065] The projection device 200 includes a light source device 100, a second lens 4 through which the first laser light L1 and the second laser light L2 emitted from the optical member 3 pass, and a fly-eye lens 5 through which the first laser light L1 and the second laser light L2 emitted from the second lens 4 pass. The projection device 200 also includes a spatial modulator 6 that modulates the first laser light L1 and the second laser light L2 emitted from the fly-eye lens 5, and a third lens 7 that projects the first laser light L1 and the second laser light L2 modulated by the spatial modulator 6. In the example shown in FIG. 20, the projection device 200 further includes a fourth lens 8 and a fifth lens 9.

[0066] The second lens 4, the third lens 7, the fourth lens 8, and the fifth lens 9 can each be made of a glass material, an optical crystal, or a resin material that is translucent to the first laser light L1 and the second laser light L2 emitted from the laser light source 1. The translucency of the second lens 4, the third lens 7, the fourth lens 8, and the fifth lens 9 preferably has a transmittance of 90% or more, 95% or more, or 98% or more to the first laser light L1 and the second laser light L2 emitted from the laser light source 1.

[0067] Each of the second lens 4, the third lens 7, the fourth lens 8, and the fifth lens 9 can be a plano-convex single lens, a biconvex single lens, a meniscus single lens, a Fresnel lens, a diffractive lens, a lens assembly consisting of a plurality of single lenses, or the like. Each of the second lens 4, the third lens 7, the fourth lens 8, and the fifth lens 9 can include at least one of a spherical lens and an aspherical lens. The type, arrangement, shape, and the like of each of the second lens 4, the third lens 7, the fourth lens 8, and the fifth lens 9 can be appropriately changed according to the specifications of the projection device 200, and the like.

[0068] The fly-eye lens 5 is a plate-like member including a plurality of lenses. The plurality of lenses are arranged side by side on a virtual plane (e.g., an XY plane) intersecting with the optical axis of the lens. In the example shown in Fig. 20, the fly-eye lens 5 includes a plurality of sixth lenses 51 arranged two-dimensionally on the surface on the side where the laser light source 1 is located, and a plurality of seventh lenses 52 arranged two-dimensionally on the surface opposite to the surface on which the plurality of sixth lenses are arranged.

[0069] The fly-eye lens 5, the fourth lens 8, and the fifth lens 9 constitute an integrator optical system 50 that substantially uniforms the illuminance of the first laser light L1 and the second laser light L2 incident from the second lens 4. However, the configuration of the integrator optical system 50 can be appropriately changed as long as it includes the fly-eye lens 5.

[0070] The fly-eye lens 5 may be made of a material including a glass material, an optical crystal, or a resin material having translucency to each of the first laser light L1 and the second laser light L2 emitted from the laser light source 1. The translucency of the fly-eye lens 5 preferably has a transmittance of 90% or more, 95% or more, or 98% or more to each of the first laser light L1 and the second laser light L2 emitted from the laser light source 1. The number, arrangement, shape, etc. of the sixth lens 51 and the seventh lens 52 in the fly-eye lens 5 can be appropriately changed according to the specifications of the projection device 200, etc.

[0071] The spatial modulator 6 may be a transmissive liquid crystal panel, LCOS (Liquid crystal on silicon), DMD (Digital Micromirror Device), or the like. In the example shown in Fig. 20, the spatial modulator 6 generates an image by spatially modulating incident light in response to a control signal based on image data or the like. The projection device 200 can project, by the third lens 7, an image generated by modulating the first laser light L1 and the second laser light L2 by the spatial modulator 6.

[0072] The projection device 200 can project the first laser light L1 and the second laser light L2 while reducing the difference in speckle noise between colors by including the light source device 100. The projection device 200 may include at least one of the light source device 100, the light source device 100a, and the light source device 100b.

[0073] The effects other than those mentioned above are similar to those in the first to third embodiments.

[0074] Although the preferred embodiments have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the claims.

[0075] The ordinal numbers, quantities, and other numbers used in the description of the embodiments are all provided as examples to specifically explain the technology of the present disclosure, and the present disclosure is not limited to the illustrated numbers. Furthermore, the connection relationships between the components are provided as examples to specifically explain the technology of the present disclosure, and do not limit the connection relationships that realize the functions of the present disclosure.

[0076] The light source device and projection device of the present disclosure can reduce the difference in speckle noise for each color, and therefore can be suitably used as a light source device and a projection device in various devices, devices, or systems using laser light. For example, the light source device and projection device of the present disclosure can be suitably used as a light source device in a display device such as a projector or a head-up display, or a head-mounted display device such as a head-mounted display. The light source device and projection device of the present disclosure can also be used as a light source device and a projection device in a lighting device, a lighting system such as smart lighting or energy-saving lighting, a display device such as a head-up display or a head-mounted display, a drawing device mounted on a vehicle or an aircraft, a spatial three-dimensional drawing device, an underwater drawing system, and the like.

[0077] Aspects of the present disclosure are, for example, as follows. <Item 1> A light source device including: a laser light source that emits a first laser light and a second laser light having a color different from the first laser light; a first lens through which the first laser light and the second laser light emitted from the laser light source pass; and an optical member through which each of the first laser light and the second laser light emitted from the first lens passes, wherein the optical member is capable of emitting the first laser light and the second laser light, and has a first surface that is arranged around a central axis along a traveling direction of the first laser light and the second laser light in the optical member, and a second surface that is arranged around the first surface, wherein the first surface reflects the second laser light and transmits the first laser light, and the second surface reflects the first laser light that has transmitted through the first surface. <Item 2> In the light source device according to <Item 1>, the first laser light is a red laser light, and the second laser light includes at least one of a green laser light and a blue laser light. <Item 3> The light source device described in <Item 1> or <Item 2>, wherein the optical member includes a light incident surface into which each of the first laser light and the second laser light emitted from the first lens is incident, and a light exit surface from which each of the first laser light and the second laser light is exited, and the second surface has an inverted tapered shape that widens in a direction from the light incident surface toward the light exit surface. <Item 4> The light source device described in <Item 3>, wherein the first surface includes a first region parallel to a direction from the light incident surface to the light exit surface and a second region extending in a direction from the light incident surface to the light exit surface, and the first region is located closer to the light incident surface than the second region. <Item 5> The light source device according to <Item 4>, wherein a length of the first region is 50% to 80% of a length of the optical member in a direction from the light entrance surface to the light exit surface. <Item 6> The light source device according to any one of <Item 1> to <Item 5>, wherein the first surface is a dichroic mirror surface. <Item 7> The laser light source is a light source device described in any one of <Item 1> to <Item 6>, which includes a first laser light source that emits a plurality of red laser beams, and a second laser light source that emits a plurality of green laser beams and a plurality of blue laser beams. <Item 8> The light source device described in <Item 7>, wherein the first laser light source includes a plurality of first semiconductor laser elements each emitting red laser light, the second laser light source includes a plurality of second semiconductor laser elements each emitting green laser light and a plurality of third semiconductor laser elements each emitting blue laser light, and the number of the first semiconductor laser elements is greater than the number of the second semiconductor laser elements and is also greater than the number of the third semiconductor laser elements. <Item 9> A projection device comprising: a light source device according to any one of <Item 1> to <Item 8>; a second lens through which the first laser light and the second laser light emitted from the optical member pass; a fly-eye lens through which the first laser light and the second laser light emitted from the second lens pass; a spatial modulator that modulates the first laser light and the second laser light emitted from the fly-eye lens; and a third lens that projects the first laser light and the second laser light modulated by the spatial modulator. [Explanation of symbols]

[0078] 1 Laser light source 11 First laser light source 110 First board 111 First semiconductor laser element 12 Second laser light source 120 Second board 121 Second semiconductor laser element 122 Third semiconductor laser element 2 First lens 3, 3a, 3b Optical components 30 center axis 31, 31b 1st page 31b1 1st area 31b2 2nd area 32, 32a 2nd side 33 Light incidence surface 34 Light exit surface 35, 35b First optical member 36, 36a, 36b Second optical member 4 Second lens 5 Fly-eye lens 51 6th lens 52 7th lens 6 Spatial Modulator 7 Third lens 8 Fourth lens 9 Fifth lens 50 Integrator Optical System 100 Light source device 200 Projection device L1 First laser beam L2 Second laser beam L21 Green laser light L22 Blue laser light N0, N1 length

Claims

1. a laser light source that emits a first laser light and a second laser light having a different color from the first laser light; a first lens through which the first laser light and the second laser light emitted from the laser light source pass; an optical member through which each of the first laser light and the second laser light emitted from the first lens passes, The optical member is The first laser light and the second laser light can be emitted, a first surface disposed around a central axis of the optical member along a traveling direction of the first laser light and the second laser light; a second surface disposed about the first surface, the first surface reflects the second laser light and transmits the first laser light; The second surface reflects the first laser light that has passed through the first surface.

2. the first laser light is a red laser light, The light source device according to claim 1 , wherein the second laser light includes at least one of a green laser light and a blue laser light.

3. The optical member is a light incident surface onto which each of the first laser light and the second laser light emitted from the first lens is incident; a light emission surface that emits each of the first laser light and the second laser light, The light source device according to claim 1 , wherein the second surface has an inverse tapered shape expanding in a direction from the light incident surface toward the light exit surface.

4. The first surface is A first region parallel to a direction from the light incident surface to the light exit surface; a second region extending in a direction from the light incident surface to the light exit surface, The light source device according to claim 3 , wherein the first region is located closer to the light incident surface than the second region.

5. In a direction from the light incident surface to the light exit surface, a length of the first region is 50% or more and 80% or less of a length of the optical member. The light source device according to claim 4 .

6. The light source device according to claim 1 , wherein the first surface is a dichroic mirror surface.

7. The laser light source is a first laser light source that emits a plurality of red laser beams; The light source device according to claim 1 , further comprising: a second laser light source that emits a plurality of green laser beams and a plurality of blue laser beams.

8. the first laser light source includes a plurality of first semiconductor laser elements each emitting a red laser beam; the second laser light source includes a plurality of second semiconductor laser elements each emitting a green laser beam and a plurality of third semiconductor laser elements each emitting a blue laser beam; 8. The light source device according to claim 7, wherein the number of the first semiconductor laser elements is greater than the number of the second semiconductor laser elements and is greater than the number of the third semiconductor laser elements.

9. The light source device according to claim 1 ; a second lens through which the first laser light and the second laser light emitted from the optical member pass; a fly-eye lens through which the first laser light and the second laser light emitted from the second lens pass; a spatial modulator that modulates the first laser light and the second laser light emitted from the fly-eye lens; a third lens that projects the first laser light and the second laser light modulated by the spatial modulator.

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