Optical device and display device

Abstract

An optical device capable of improving the performance of reducing speckle noise is provided. The optical device includes: a laser light source; a first integrator optical system that transmits the laser light emitted from the laser light source; a second integrator optical system that transmits the laser light emitted from the first integrator optical system; and a phase difference plate that is arranged between the laser light source and the second integrator optical system and rotates the polarization of the transmitted laser light by 90 degrees by transmitting a part of the laser light.

Description

Technical Field

[0001] The present disclosure relates to an optical device and a display device. Background Art

[0002] Conventionally, there has been known an optical device for emitting laser light and which is mounted on a display device or the like that displays an image using laser light.

[0003] For example, Patent Document 1 discloses a light source device that uses a half-wavelength plate to rotate the polarization of laser light output from a laser light source by 90 degrees in order to reduce speckle noise caused by laser scattering.

[0004] <Prior Art Literature>

[0005] <Patent Documents>

[0006] Patent Document 1: (Japanese) Patent Publication No. 2011-242537 Summary of the invention

[0007] <Problems to be Solved by the Invention>

[0008] However, in the device described in Patent Document 1, only polarized light of laser light from a laser light source is used, and therefore there is still room for improvement in speckle noise reduction performance.

[0009] An object of an embodiment of the present disclosure is to provide an optical device capable of improving the performance of reducing speckle noise.

[0010] <Methods used to solve the problem>

[0011] The optical device of the embodiment of the present disclosure includes: a laser light source; a first integrator optical system, which transmits the laser light emitted from the laser light source; a second integrator optical system, which transmits the laser light emitted from the first integrator optical system; and a phase difference plate, which is arranged between the laser light source and the second integrator optical system, and rotates the polarization light of the transmitted laser light by 90 degrees by transmitting a part of the laser light.

[0012] <Effects of the Invention>

[0013] An object of an embodiment of the present disclosure is to provide an optical device capable of improving the performance of reducing speckle noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic cross-sectional view of the optical device according to embodiment 1.

[0015] Figure 2 This is a schematic plan view showing a first example of the positional relationship between the laser light source and the phase difference plate in the optical device according to the first embodiment.

[0016] Figure 3 This is a schematic perspective view of a first fly-eye lens included in the first integrator optical system of the optical device according to the first embodiment.

[0017] Figure 4 This is a schematic perspective view of a third fly-eye lens included in the second integrator optical system of the optical device according to the first embodiment.

[0018] Figure 5 This is a schematic cross-sectional view showing a second illumination optical system in which two orthogonal polarized lights are incident on an illumination surface in the optical device according to the first embodiment.

[0019] Figure 6 This is a schematic plan view showing a second example of the positional relationship between the laser light source and the phase difference plate in the optical device according to the first embodiment.

[0020] Figure 7 This is a schematic cross-sectional view of an optical device according to embodiment 2.

[0021] Figure 8 This is a schematic cross-sectional view showing a second illumination optical system in which two orthogonal polarized lights are incident on an irradiation surface in the optical device according to the second embodiment.

[0022] Fig. 9 This is a schematic cross-sectional view showing a first example of the structure around a laser light source in an optical device according to the third embodiment.

[0023] Fig.10 This is a schematic cross-sectional view showing a second example of the structure around the laser light source in the optical device of embodiment 3.

[0024] Fig.11 This is a schematic plan view showing a first example of the positional relationship between the synthetic light and the phase difference plate in the optical device according to the third embodiment.

[0025] Fig.12 This is a schematic plan view showing a second example of the positional relationship between the synthetic light and the phase difference plate in the optical device according to the third embodiment.

[0026] Fig.13 This is a schematic cross-sectional view of an optical device according to embodiment 4.

[0027] Fig.14 This is a schematic cross-sectional view of a display device according to Embodiment 5. DETAILED DESCRIPTION

[0028] The optical device and display device of the embodiment of the present disclosure will be described in detail with reference to the accompanying drawings. However, the method shown below is an example of the structure of the optical device and display device used to concretize the technical idea of ​​the present disclosure, and is not limited to the following. In addition, the size, material, shape, relative configuration, etc. of the structural parts described in the embodiment, unless otherwise specified, do not mean that the scope of the present disclosure is limited to this, but are only illustrative examples. In addition, in order to clarify the description, the size, positional relationship, etc. of the components shown in each figure are sometimes expanded. In addition, in the following description, the same name and symbol represent the same or homogeneous components, and the detailed description is appropriately omitted. As a cross-sectional view, an end view that only shows the cut surface is sometimes used.

[0029] In each figure, as a direction expression, an orthogonal coordinate including an X-axis, a Y-axis, and a Z-axis is used. The X-axis, the Y-axis, and the Z-axis are orthogonal to each other. The side indicated by the arrow in the X direction along the X-axis is marked as the +X side, and the side opposite to the +X side is marked as the -X side. The side indicated by the arrow in the Y direction along the Y-axis is marked as the +Y side, and the side opposite to the +Y side is marked as the -Y side. The side indicated by the arrow in the Z direction along the Z-axis is marked as the +Z side, and the side opposite to the +Z side is marked as the -Z side.

[0030] The Z axis is the axis along the normal of the phase difference plate of the optical device of the embodiment. In addition, the optical device of the embodiment emits the laser to the +Z side. The plane view in the terminology of the embodiment refers to observing the object from the +Z side or the -Z side. The plane view of the object represents a diagram of the object under the plane view. However, these do not limit the direction of the optical device and the display device according to the embodiment when in use, and the direction of the optical device and the display device according to the embodiment is arbitrary.

[0031] In the embodiments shown below, along the X, Y, and Z axes, the object is included to have a tilt within a range of ±10 degrees relative to these axes. In the embodiments, orthogonal and vertical can each include an error within ±10 degrees relative to 90 degrees. In addition, a rotation of 90 degrees can include an error within ±10 degrees. In addition, half of the object can include an error within ±10% of the object.

[0032] In addition, in the specification or claims, when there are multiple structural elements and they need to be described separately, sometimes "first", "second", etc. are added to the beginning of the structural element to distinguish them. In addition, the objects to be distinguished in the specification and the claims may be different. Therefore, even if the claims record a structural element with the same symbol as in the present specification, the object determined by the structural element may not be consistent between the specification and the claims.

[0033] [Implementation Method 1]

[0034] Reference Figure 1 to Figure 5, describing the optical device of embodiment 1. Figure 1 This is a schematic cross-sectional view showing an example of the optical device 100 according to the first embodiment. Figure 1 The cross section of the optical device 100 is shown when it is cut on a virtual plane (eg, YZ plane) including the optical axis A of the optical device 100 . The optical axis A of the optical device 100 is an axis passing through the center of the first integrator optical system 2 included in the optical device 100 . Figure 2 1 is a schematic plan view showing a first example of the positional relationship between the laser light source 1 and the phase difference plate 4 in the optical device 100 . Figure 3 It is a schematic perspective view of the first fly-eye lens 21 included in the first integrator optical system 2 of the optical device 100 . Figure 4 It is a schematic perspective view of the third fly-eye lens 31 included in the second integrator optical system 3 of the optical device 100 . Figure 5 1 is a schematic cross-sectional view of the second illumination optical system 30 showing a state in which two orthogonal polarized lights are incident on the irradiation surface S in the optical device 100 . Figure 5 1 shows a cross section of the optical device 100 cut on a virtual plane (for example, a YZ plane) including the optical axis A of the optical device 100 .

[0035] The optical device 100 includes a laser light source 1, a first integrator optical system 2 that transmits the laser light L emitted from the laser light source 1, and a second integrator optical system 3 that transmits the laser light L emitted from the first integrator optical system 2. In addition, the optical device 100 also includes a phase difference plate 4 disposed between the laser light source 1 and the second integrator optical system 3, which transmits a portion of the laser light L to rotate the polarization of the transmitted laser light L by 90 degrees. Figure 1 In the example shown, the optical device 100 includes a first lens 5, a second lens 6, a third lens 7, and a fourth lens 8. The first integrator optical system 2, the first lens 5, and the second lens 6 constitute a first illumination optical system 20. The second integrator optical system 3, the third lens 7, and the fourth lens 8 constitute a second illumination optical system 30. The second integrator optical system 3 may include a third fly-eye lens 31.

[0036] exist Figure 1 In the example shown, the laser light source 1 includes a semiconductor laser element 11, a substrate 13 having a recessed portion on the surface on the +Z side, a cover member 12, and an optical component 16. The semiconductor laser element 11 is arranged in the recessed portion of the substrate 13. The recessed portion of the substrate 13 is sealed by the cover member 12, and the optical component 16 is arranged on the surface on the +Z side of the cover member 12. The semiconductor laser element 11 can emit laser light L according to the current supplied through the substrate 13, etc.

[0037] like Figure 2As shown, the laser light source 1 includes four first semiconductor laser elements 11R emitting red laser light, two second semiconductor laser elements 11G emitting green laser light, and two third semiconductor laser elements 11B emitting blue laser light. Figure 1 The semiconductor laser elements 11 in the embodiment include four first semiconductor laser elements 11R, two second semiconductor laser elements 11G, and two third semiconductor laser elements 11B. Figure 1 The laser light L includes laser lights emitted from the four first semiconductor laser elements 11R, the two second semiconductor laser elements 11G, and the two third semiconductor laser elements 11B.

[0038] exist Figure 1 and Figure 2 In the example shown, the laser light source 1 emits linearly polarized laser light L from a semiconductor laser element 11. The laser light L is, for example, P polarized light. The phase difference plate 4 transmits a portion of the laser light L emitted from the semiconductor laser element 11, and emits S polarized light whose polarization direction is rotated 90 degrees relative to the P polarized light of the transmitted laser light L. The P polarized light of the laser light L that does not pass through the phase difference plate 4 and the S polarized light that passes through the phase difference plate 4 are incident on the first integrator optical system 2.

[0039] The phase difference plate 4 is, for example, a 1 / 2 wavelength plate. Figure 2 In the example shown, the shape of the phase difference plate 4 in a plane view is roughly rectangular, with the horizontal direction (for example, the X direction) orthogonal to the vertical direction as the long side. However, the shape of the phase difference plate 4 in a plane view can be roughly circular, roughly elliptical, roughly polygonal, etc. The normal of the phase difference plate 4 is roughly consistent with the optical axis A, for example. The 1 / 2 wavelength plate can be composed of crystals with birefringence, or it can be composed of a resin with birefringence. The phase difference plate 4 is configured so that the optical axis of the 1 / 2 wavelength plate is inclined 45 degrees relative to the polarization direction of the laser L as linear polarized light. Therefore, the phase difference plate 4 can rotate the polarization of the laser light in the laser L that transmits the phase difference plate 4 by 90 degrees.

[0040] exist Figure 1 In the example shown, the first integrator optical system 2 and the second integrator optical system 3 each generate a light beam with uniform illumination using the laser light L emitted from the laser light source 1. The laser light L from the laser light source 1 passes through the first integrator optical system 2, and then passes through the first lens 5 and the second lens 6 to enter the second integrator optical system 3. The laser light L that passes through the second integrator optical system 3 passes through the third lens 7 and the fourth lens 8, and then is emitted from the optical device 100. The laser light L emitted from the optical device 100 is irradiated onto an irradiation surface S. The irradiation surface S is, for example, a screen.

[0041] Here, laser light, which is coherent light, is more likely to interfere than incoherent light. Therefore, when the laser light irradiates the irradiation surface S, speckle noise may be generated due to the interference of light scattered on the surface of the irradiation surface S. Due to the generation of speckle noise, when an image is displayed using the laser light emitted from the optical device, uneven brightness or color may occur, resulting in a decrease in image quality.

[0042] The optical device 100 can emit two orthogonal polarized lights by rotating a portion of the polarized light of the laser light source L emitted from the laser light source 1 by 90 degrees using the phase difference plate 4. Since the two orthogonal polarized lights do not interfere with each other, the optical device 100 can reduce speckle noise by emitting the two orthogonal polarized lights. In this specification, the above is referred to as "speckle noise reduction effect by polarization multiplexing".

[0043] In addition, the optical device 100 is provided with two integrator optical systems including a first integrator optical system 2 and a second integrator optical system 3, and is able to increase the angle difference of the laser light source L emitted from the optical device 100 and incident on the irradiation surface S. The angle difference of light incident on the irradiation surface S means the angle difference between the incident angle of one light incident on the irradiation surface S and the incident angle of other light. In addition, the angle difference of light incident on the irradiation surface S, in other words, is the range of angles at which light is incident on the irradiation surface S. The greater the angle difference of the incident angles of light, the smaller the interference between the incident lights. The optical device 100 is provided with two integrator optical systems including a first integrator optical system 2 and a second integrator optical system 3, and is able to reduce speckle noise by increasing the angle difference of the incident angles of light. In this specification, the above is referred to as the "speckle noise reduction effect through angle multiplexing". In addition, regarding the effect of this angle multiplexing, refer to the description of the angle multiplexing method. Figure 5 Provide explanation.

[0044] In this embodiment, by using both polarization multiplexing and angle multiplexing, it is possible to provide an optical device 100 that can improve speckle noise reduction performance. For example, by using both polarization multiplexing and angle multiplexing, the optical device 100 can improve speckle noise reduction performance compared to the case of using only polarization multiplexing.

[0045] In the optical device 100, the phase difference plate 4 can transmit half of the laser light L emitted from the laser light source 1. Figure 2 As shown in FIG. 1 , the phase difference plate 4 may be arranged so that half of the laser light L emitted from one of the semiconductor laser elements 11 passes through the phase difference plate 4 . Figure 2In the example shown, the phase difference plate 4 is arranged so as to transmit half of each of the four laser lights L emitted from the four first semiconductor laser elements 11R, transmit half of each of the two laser lights L emitted from the two second semiconductor laser elements 11G, and transmit half of each of the two laser lights L emitted from the two third semiconductor laser elements 11B. With this arrangement, the laser lights L emitted from the four first semiconductor laser elements 11R, the two second semiconductor laser elements 11G, and the two third semiconductor laser elements 11B can be split into two orthogonal polarized lights. By splitting into two orthogonal polarized lights, the speckle noise reduction effect of polarization multiplexing can be almost maximized, and the speckle noise can be further reduced compared to the case where polarization multiplexing is not used.

[0046] The laser light source 1 is a light emitting device having a plurality of semiconductor laser elements 11. Each semiconductor laser element 11 emits laser light L. Therefore, the optical device 100 can emit brighter light than when light other than laser light is emitted or when one semiconductor laser element emits laser light.

[0047] In addition, the laser light source 1 can emit a plurality of laser beams L having different colors. Therefore, the optical device 100 can emit mixed light of the colors of the plurality of laser beams L.

[0048] The first integrator optical system 2 includes a first fly-eye lens 21 and a second fly-eye lens 22. The first fly-eye lens 21 and the second fly-eye lens 22 are plate-shaped components having a first surface 21a and a second surface 21b located on the opposite side of the first surface 21a, respectively. The first surface 21a and the second surface 21b are planes (e.g., XY planes) orthogonal to the optical axis A. The first surface 21a includes a plurality of first convex surfaces 210 arranged along a plane orthogonal to the optical axis A. The first fly-eye lens 21 and the second fly-eye lens 22 are configured in a manner such that the second surfaces 21b of each other are opposite. From a productivity point of view, the first fly-eye lens 21 and the second fly-eye lens 22 preferably have the same shape, but may also have different shapes. In addition, the first fly-eye lens 21 and the second fly-eye lens 22 may also be made as an integral component rather than an independent component.

[0049] exist Figure 3In the example shown, each of the plurality of first convex surfaces 210 included in the first fly-eye lens 21 has a substantially hexagonal shape when viewed from above. The plurality of first convex surfaces 210 are arranged to be almost seamless when viewed from above. In addition, the shape of the first convex surface 210 when viewed from above is not limited to being substantially hexagonal, but may also be substantially circular, substantially elliptical, substantially rectangular, substantially polygonal other than hexagonal, and the like. The four first lasers LR emitted from the four first semiconductor laser elements 11R, the two second lasers LG emitted from the two second semiconductor laser elements 11G, and the two third lasers LB emitted from the two third semiconductor laser elements 11B transmit Figure 1 The optical component 16 shown in the figure is incident on the first fly-eye lens 21 as substantially parallel light.

[0050] The second integrator optical system 3 is arranged at a position substantially conjugate with the first integrator optical system 2 through the first lens 5 and the second lens 6. Furthermore, the first illumination optical system 20 is configured so that the enlarged conjugate images of the plurality of first convex surfaces 210 in the first integrator optical system 2 substantially overlap near the arrangement position of the second integrator optical system 3. Thus, near the arrangement position of the second integrator optical system 3, as shown in FIG. Figure 4 As shown, by the mixed color light Lm of the red laser, the green laser and the blue laser that pass through the plurality of first convex surfaces 210, an enlarged conjugate image in which the enlarged conjugate images of the plurality of first convex surfaces 210 are substantially overlapped can be obtained.

[0051] exist Figure 4 In the example shown, the third fly-eye lens 31 is a plate-shaped member having a plurality of third convex surfaces 301 arranged along a plane perpendicular to the optical axis A. The plurality of third convex surfaces 301 are connected and formed as an integral member.

[0052] The first integrator optical system 2, the second integrator optical system 3, the first lens 5, the second lens 6, the third lens 7, and the fourth lens 8 are each composed of a resin or glass having light transmittance to the laser light L emitted from the laser light source 1. In addition, the light transmittance here preferably has a light transmittance of 60% or more to the laser light L.

[0053] exist Figure 5 In the example shown, P-polarized light Lp and S-polarized light Ls, which are two orthogonal polarized lights, are irradiated onto the irradiation surface S through the second illumination optical system 30. The P-polarized light Lp is the laser light that is not transmitted by the phase difference plate 4 among the laser light L emitted by the laser light source 1. The S-polarized light Ls is the laser light that is transmitted by the phase difference plate 4 among the laser light L emitted by the laser light source 1.

[0054] like Figure 1As shown, in the optical device 100, the phase difference plate 4 can be arranged between the laser light source 1 and the first integrator optical system 2. By this arrangement, Figure 5 As shown, the P-polarized light Lp and the S-polarized light Ls are incident on the irradiation surface S in directions that are substantially symmetrical about the optical axis A. As a result, the angle difference of the incident angle of the P-polarized light Lp with respect to the irradiation surface S and the angle difference of the incident angle of the S-polarized light Ls with respect to the irradiation surface S are increased compared to the case where the P-polarized light Lp and the S-polarized light Ls are not incident on the irradiation surface S in directions that are not symmetrical about the optical axis A. Thus, in the optical device 100, the speckle noise reduction effect due to angle multiplexing can be improved compared to the case where the P-polarized light Lp and the S-polarized light Ls are not incident on the irradiation surface S in directions that are not symmetrical about the optical axis A.

[0055] In the optical device 100, the number and arrangement of the semiconductor laser elements 11 included in the laser light source 1 can be appropriately changed. The respective structures of the first illumination optical system 20 and the second illumination optical system 30 and the arrangement of each structural part can also be appropriately changed. In addition, the laser light source 1 is not limited to a structure that emits a plurality of lasers L of different colors, but can also be a structure that emits a monochromatic laser L. In this case, the optical device 100 can also reduce speckle noise.

[0056] <Other Examples of Positional Relationship between Laser Light Source 1 and Phase Difference Plate 4>

[0057] The positional relationship between the laser light source 1 and the phase difference plate 4 is Figure 2 In addition to the first example shown, various modifications can be made. Here, another example of the positional relationship between the laser light source 1 and the phase difference plate 4 will be described. In addition, the same names and symbols as those in the examples or embodiments already described represent the same or homogeneous components or structures, and detailed descriptions are appropriately omitted. This is also the same in the embodiments shown later.

[0058] (Example 2)

[0059] Figure 6 1 is a schematic plan view showing a second example of the positional relationship between the laser light source 1 and the phase difference plate 4 in the optical device 100. Figure 6 In the illustrated example, the phase difference plate 4 includes a first phase difference plate 41 and a second phase difference plate 42 .

[0060] The first phase difference plate 41 and the second phase difference plate 42 are, for example, half-wave plates. The first phase difference plate 41 and the second phase difference plate 42 are respectively configured so that the optical axis of the half-wave plate is inclined 45 degrees relative to the polarization direction of the incident linear polarized light. Thus, the phase difference plate 4 can rotate the polarization of the laser light that passes through the first phase difference plate 41 and the second phase difference plate 42, respectively, among the incident linear polarized light, by 90 degrees.

[0061] The first phase difference plate 41 is configured to transmit half of the four lasers emitted by the four first semiconductor laser elements 11R. On the other hand, the second phase difference plate 42 is configured to transmit half of the two lasers emitted by the two second semiconductor laser elements 11G, and transmit half of the two lasers emitted by the two third semiconductor laser elements 11B. Thus, the phase difference plate 4 can divide the lasers emitted by the four first semiconductor laser elements 11R, the two second semiconductor laser elements 11G, and the two third semiconductor laser elements 11B into two orthogonal polarized lights. By dividing into two orthogonal polarized lights, the speckle noise reduction effect promoted by polarization multiplexing can be almost maximized, and the speckle noise can be reduced compared to the case where polarization multiplexing is not used.

[0062] [Implementation Method 2]

[0063] Reference Figure 7 as well as Figure 8 , describing the optical device of embodiment 2. Figure 7 This is a schematic cross-sectional view showing an optical device 100a according to Embodiment 2. Figure 7 The cross section of the optical device 100 a cut on a virtual plane (eg, YZ plane) including the optical axis A is shown. Figure 8 1 is a schematic cross-sectional view showing the second illumination optical system 30 in which two orthogonal polarized lights are incident on the irradiation surface S in the optical device 100 a . Figure 8 The cross section of the second illumination optical system 30 cut on a virtual plane (for example, a YZ plane) including the optical axis A is shown.

[0064] The present embodiment is different from the first embodiment in that the phase difference plate 4 is disposed between the first integrator optical system 2 and the second integrator optical system 3. Figure 7 as well as Figure 8 In the example shown, the phase difference plate 4 is arranged near the arrangement position of the second integrator optical system 3 so as to transmit half of the mixed color light Lm obtained by the first illumination optical system 20 .

[0065] exist Figure 8 In the example shown, P polarized light Lp and S polarized light Ls, which are two orthogonal polarized lights, pass through the second illumination optical system 30 and are irradiated onto the irradiation surface S. P polarized light Lp is the mixed light that has not passed through the phase difference plate 4 in the mixed light Lm. S polarized light Ls is the mixed light that has passed through the phase difference plate 4 in the mixed light Lm.

[0066] In the optical device 100a, by disposing the phase difference plate 4 between the first integrator optical system 2 and the second integrator optical system 3, as shown in FIG. Figure 8As shown in FIG. 1 , the P polarized light Lp and the S polarized light Ls are incident on the irradiation surface S in directions that are approximately symmetrical with respect to the optical axis A. That is, Figure 8 In the example shown, most of the P-polarized light Lp passes through the space on the +Y side of the optical axis A and is irradiated to the irradiation surface S, and most of the S-polarized light Ls passes through the space on the -Y side of the optical axis A and is irradiated to the irradiation surface S. As a result, the angle difference between the incident angle of the P-polarized light Lp entering the irradiation surface S and the angle difference between the incident angle of the S-polarized light Ls entering the irradiation surface S increases. Thus, in the optical device 100a, the speckle noise reduction effect due to angle multiplexing can be increased.

[0067] In addition, compared with the case where the P polarized light Lp and the S polarized light Ls are incident on the irradiation surface S in directions substantially symmetrical with respect to the optical axis A in the first embodiment (see Figure 5 ), the angle difference of the incident angle of the P polarized light Lp entering the irradiation plane S and the angle difference of the incident angle of the S polarized light Ls entering the irradiation plane S in the optical device 100a are each halved. Therefore, in the optical device 100a, the speckle noise reduction effect caused by angle multiplexing is reduced compared with the first embodiment.

[0068] [Implementation method 3]

[0069] Reference Figures 9 to 12 , describing the optical device of embodiment 3. Fig. 9 This is a schematic cross-sectional view showing a first example of the structure of the periphery of the laser light source 1 in the optical device 100 b according to the third embodiment. Fig.10 It is a schematic cross-sectional view showing a second example of the structure around the laser light source 1 in the optical device 100 b . Fig. 9 as well as Fig.10 Each shows a cross section of the periphery of the laser light source 1 of the optical device 100b cut on a virtual plane (eg, YZ plane) including the optical axis A. The structure of the optical device 100b other than the periphery of the laser light source 1 may be the same as that of the optical device 100 of the first embodiment. Fig.11 1 is a schematic plan view showing a first example of the positional relationship between the synthesized light Lu and the phase difference plate 4 in the optical device 100 b . Fig.12 It is a schematic plan view showing a second example of the positional relationship between the synthetic light Lu and the phase difference plate 4 in the optical device b.

[0070] In this embodiment, a synthesis optical system 14 is further included, which is arranged between the laser light source 1 and the first integrator optical system 2 and is used to synthesize multiple lasers L. The phase difference plate 4 transmits a part of the synthesized light Lu synthesized by the synthesis optical system 14 into multiple lasers L, and rotates the polarization of the transmitted synthesized light Lu by 90 degrees. This is different from the first embodiment.

[0071] When the phase difference plate 4 is configured to transmit a portion of each of the multiple lasers, the positioning adjustment is time-consuming because the multiple lasers need to be positioned at the phase difference plate 4 with high precision. In addition, when the positioning adjustment accuracy is low, the speckle noise reduction effect is sometimes reduced. In this embodiment, by configuring the phase difference plate 4 to transmit a portion of the synthetic light Lu, compared to the case where the phase difference plate 4 is configured to transmit a portion of each of the multiple lasers, the phase difference plate 4 can be easily and accurately configured to reduce the speckle noise.

[0072] exist Fig. 9 The first example of the optical device 100b shown in FIG. Fig.10 In the second example of the optical device 100b shown, the laser light source 1 emits a plurality of laser lights L of different colors. The synthesis optical system 14 includes a lens group 15 for synthesizing the plurality of laser lights L of different colors. In addition, the synthesis optical system 14 also includes a beam expander 17 that expands the maximum width of the laser lights L in a direction orthogonal to the optical axis A of the optical device 100b. Fig. 9 The first example shown and Fig.10 In the second example shown, the mirror group 15 is arranged between the laser light source 1 and the first integrator optical system 2. In addition, the beam expander 17 is arranged between the mirror group 15 and the first integrator optical system 2.

[0073] exist Fig. 9 The first example shown and Fig.10 In the second example shown, the mirror group 15 includes a mirror 151, a first dichroic mirror 152, and a second dichroic mirror 153. The mirror 151 reflects the first laser light LR emitted by the first semiconductor laser element 11R toward the beam expander 17. The first dichroic mirror 152 reflects the second laser light LG emitted by the second semiconductor laser element 11G toward the beam expander 17, and transmits the first laser light LR reflected by the mirror 151. The second dichroic mirror 153 reflects the third laser light LB emitted by the third semiconductor laser element 11B toward the beam expander 17, and transmits the first laser light LR reflected by the mirror 151 and the second laser light LG reflected by the first dichroic mirror 152. In addition, the mirror 151 may also be a dichroic mirror.

[0074] The first laser LR, the second laser LG, and the third laser LB are synthesized by the mirror group 15 to form a synthesized light Lu. The synthesized light Lu is a mixture of red, green, and blue light that is substantially parallel to the optical axis A. The synthesized light Lu is incident on the beam expander 17. In addition, the mirror group 15 is not limited to a structure including the mirror 151, the first dichroic mirror 152, and the second dichroic mirror 153 as long as it can synthesize a plurality of lasers L of different colors. For example, the number or arrangement of the reflective mirrors or dichroic mirrors can be appropriately changed according to the number or arrangement of the semiconductor laser elements 11 included in the laser light source 1.

[0075] The beam expander 17 includes a concave lens 171 and a convex lens 172. The beam expander 17 expands the maximum width of the synthesized light Lu from the lens group 15 in a direction perpendicular to the optical axis A. The synthesized light Lu after the maximum width is expanded by the beam expander 17 is light substantially parallel to the optical axis A. Fig. 9 The first example shown and Fig.10 The width W in each of the second examples shown represents the maximum width of the synthesized light Lu after expansion by the beam expander 17. In addition, the beam expander 17 is not limited to a structure including a concave lens 171 and a convex lens 172 as long as it can expand the maximum width of the incident light in a direction orthogonal to the optical axis A. For example, it may also be a structure including two or more convex lenses.

[0076] The synthesis optical system 14 includes the lens group 15, and can synthesize a plurality of laser lights L of different colors emitted from the laser light source 1. Therefore, even when a plurality of laser lights L of different colors are used, the phase difference plate 4 for reducing speckle noise can be easily and accurately arranged. In addition, the synthesis optical system 14 includes the beam expander 17, and can obtain a synthesis light Lu whose maximum width in a direction orthogonal to the optical axis A is enlarged, and the phase difference plate 4 for reducing speckle noise can be more easily and accurately arranged compared to a case where the beam expander 17 is not included. The synthesis optical system 14 does not necessarily include both the lens group 15 and the beam expander 17, and may include at least one of the lens group 15 and the beam expander 17.

[0077] exist Fig. 9 In the first example shown, the phase difference plate 4 is arranged between the synthesis optical system 14 and the first integrator optical system 2. The synthesis light Lu of the synthesis optical system 14 is vertically incident on the incident surface 40 of the phase difference plate 4. The phase difference plate 4, as shown in FIG. Fig.11 As shown in FIG. 12, a portion of the synthetic light Lu of the synthetic optical system 14 can be transmitted. Fig.11 In the example shown, the shape of the phase difference plate 4 in a plan view is a substantially rectangular shape with the vertical direction (e.g., Y direction) as the long side, and can transmit half of the synthetic light Lu of the synthetic optical system 14 in the horizontal direction (e.g., X direction). Fig.12 In the example shown, the shape of the phase difference plate 4 in a plan view is a substantially rectangular shape with the long side in the horizontal direction, and can transmit half of the combined light Lu of the combining optical system 14 in the vertical direction.

[0078] exist Fig. 9In the first example shown, the phase plate 4 can accurately impart a phase difference of 1 / 2 wavelength to the synthesized light Lu by making the synthesized light Lu of the synthesizing optical system 14 vertically incident on the incident surface 40 of the phase plate 4. As a result, the phase plate 4 can accurately rotate the polarization direction of the transmitted synthesized light Lu by 90 degrees, so that the optical device 100b can improve the effect of reducing speckle noise.

[0079] On the other hand, Fig.10 In the second example shown, the phase difference plate 4 is arranged on the opposite side (e.g., +Z side) of the first integrator optical system 2 on the side (e.g., -Z side) where the synthesis optical system 14 is provided. For example, when the phase difference plate 4 is arranged between the synthesis optical system 14 and the first integrator optical system 2, the synthesis light L as substantially parallel light is incident on the phase difference plate 4, and therefore, at the end of the phase difference plate 4, for example, the end on the -Y side, the scattered light of the synthesis light Lu may increase. When the scattered light is superimposed on the laser light L emitted from the optical device 100b, the quality of the laser light L emitted from the optical device 100b is reduced.

[0080] exist Fig.10 In the second example shown, by arranging the phase difference plate 4 on the side opposite to the side of the first integrator optical system 2 on which the synthesis optical system 14 is provided, the scattering of the synthesis light Lu at the end of the phase difference plate 4 can be reduced compared to the case where the phase difference plate 4 is arranged between the synthesis optical system 14 and the first integrator optical system 2. As a result, the scattered light superimposed on the laser light L emitted by the optical device 100b is reduced, and the quality of the laser light L emitted by the optical device 100b can be improved. The effects of the optical device 100b of the second example other than the above are the same as those of the optical device 100b of the first example.

[0081] [Implementation Method 4]

[0082] Fig.13 This is a schematic cross-sectional view of an optical device 100c according to a fourth embodiment. Fig.13 The cross section of the optical device 100 c cut on a virtual plane (eg, YZ plane) including the optical axis A is shown.

[0083] The present embodiment is different from the first embodiment in that the optical device 100c includes a second integrator optical system 3c including a light pipe.

[0084] exist Fig.13 In the example shown, the optical device 100c includes a second integrator optical system 3c including a light pipe and a fifth lens 9. The light pipe is, for example, a rod lens or a hollow light pipe. The second integrator optical system 3c and the fifth lens 9 constitute a second illumination optical system 30c. The laser light L emitted by the laser light source 1 and passing through the first illumination optical system 20 passes through the second illumination optical system 30c and is irradiated onto the irradiation surface S.

[0085] In the optical device 100c, the phase plate 4 disposed between the laser light source 1 and the second integrator optical system 3c transmits part of the laser light and rotates the polarization of the transmitted laser light L by 90 degrees, thereby achieving a speckle noise reduction effect through polarization multiplexing.

[0086] [Implementation method 5]

[0087] Fig.14 This is a schematic cross-sectional view of a display device 200 according to Embodiment 5. Fig.14 1 shows a cross section of the display device 200 cut along a virtual plane (eg, YZ plane) including the optical axis A of the optical device 100 .

[0088] This embodiment is different from Embodiment 1 in that the display device 200 includes the optical device 100, a spatial modulator 201 that generates an image by modulating the spatial intensity distribution of the laser light L from the optical device 100, and a lens 202 that projects the image generated by the spatial modulator 201.

[0089] The spatial modulator 201 includes an LCD (Liquid Crystal Display) or a DMD (Digital Micromirror Device). The display device 200 is, for example, a projector. The display device 200 projects the image generated by the spatial modulator 201 onto a projection surface such as a screen through a lens 202, thereby being able to display the image on the projection surface.

[0090] By polarization multiplexing and angle multiplexing, the laser light L emitted from the optical device 100 to the spatial modulator 201 is less likely to generate speckle noise. As a result, the display device 200 can project an image with reduced speckle noise onto a projection surface, and display a high-quality image with reduced brightness and color unevenness caused by speckle noise on the projection surface.

[0091] The optical device included in the display device 200 is not limited to the optical device 100, and may be any one of the optical device 100a, the optical device 100b, or the optical device 100c.

[0092] As mentioned above, although the preferred embodiment was described in detail, the present invention is not limited to the above-described embodiment, and various modifications and substitutions can be made to the above-described embodiment without departing from the scope described in the claims.

[0093] The numbers such as ordinal numbers and quantities used in the description of the embodiments are all exemplified for the purpose of specifically describing the technology of the present disclosure, and the present disclosure is not limited to the exemplified numbers. In addition, the connection relationship between the structural elements is exemplified for the purpose of specifically describing the technology of the present disclosure, and the connection relationship for realizing the functions of the present disclosure is not limited to this.

[0094] The optical device of the present disclosure can improve the speckle noise reduction performance, and thus can be appropriately used as a light source device in various devices, devices, or systems using lasers. For example, the optical device of the present disclosure can be appropriately 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. In addition, the optical device of the present disclosure can also be used as a light source device in lighting equipment, lighting systems such as smart lighting and energy-saving lighting, mapping devices installed on vehicles or aircraft, space three-dimensional mapping devices, underwater mapping systems, and the like.

[0095] The embodiment of the present invention can also be described as follows, for example.

[0096] <Item 1> An optical device, comprising: a laser light source; a first integrator optical system, which transmits the laser light emitted from the laser light source; a second integrator optical system, which transmits the laser light emitted from the first integrator optical system; a phase difference plate, which is arranged between the laser light source and the second integrator optical system, and which rotates the polarization light of the transmitted laser light by 90 degrees by transmitting a part of the laser light.

[0097] <Item 2> The optical device according to <Item 1>, wherein the phase difference plate transmits half of the laser light.

[0098] <Item 3> The optical device according to <Item 1> or <Item 2>, wherein the laser light source is a light emitting device having a plurality of semiconductor laser elements, each of which emits the laser light.

[0099] <Item 4> The optical device according to <Item 3>, wherein the phase difference plate is configured so that half of the laser light emitted from one of the semiconductor laser elements is transmitted through the phase difference plate.

[0100] <Item 5> The optical device according to any one of <Item 1> to <Item 4>, wherein the laser light source emits a plurality of laser beams having different colors from each other.

[0101] <Item 6> The optical device according to any one of <Item 1> to <Item 5>, wherein the phase difference plate is arranged between the laser light source and the first integrator optical system.

[0102] <Item 7> The optical device according to any one of <Item 1> to <Item 6>, wherein the phase difference plate is arranged between the first integrator optical system and the second integrator optical system.

[0103] <Item 8> An optical device as described in any one of <Item 1> to <Item 7>, wherein the optical device also includes a synthetic optical system, which is arranged between the laser light source and the first integrator optical system, and synthesizes a plurality of the lasers, and the phase difference plate rotates the polarization of the transmitted synthetic light by 90 degrees by transmitting a portion of the synthetic light of the plurality of lasers from the synthetic optical system.

[0104] <Item 9> An optical device as described in <Item 8>, wherein the laser light source emits a plurality of lasers of different colors, and the synthetic optical system includes a mirror group that synthesizes the plurality of lasers of different colors.

[0105] <Item 10> An optical device as described in <Item 8> or <Item 9>, wherein the synthetic optical system includes a beam expander that expands the maximum width of the laser in a direction orthogonal to the optical axis of the optical device.

[0106] <Item 11> An optical device as described in any one of <Item 8> to <Item 10>, wherein the phase difference plate is arranged between the synthetic optical system and the first integrator optical system, and the synthetic light from the synthetic optical system is vertically incident on the incident surface of the phase difference plate.

[0107] <Item 12> An optical device as described in any one of <Item 8> to <Item 11>, wherein the phase difference plate is arranged on the side of the first integrator optical system opposite to the side where the synthetic optical system is located.

[0108] <Item 13> A display device, comprising: an optical device as described in any one of <Item 1> to <Item 12>; a spatial modulator that generates an image by modulating the spatial intensity distribution of the laser from the optical device; and a lens that transmits the image generated by the spatial modulator.

[0109] Explanation of symbols

[0110] 1Laser light source

[0111] 11Semiconductor laser element

[0112] 11R No.1 semiconductor laser element

[0113] 11G No. 2 semiconductor laser element

[0114] 11B No. 3 semiconductor laser element

[0115] 12 Cover parts

[0116] 13 substrates

[0117] 14 Synthetic Optical System

[0118] 15 lens groups

[0119] 16 Optical components

[0120] 151 Mirror

[0121] 152 1st dichroic mirror

[0122] 153 Second dichroic mirror

[0123] 17 Beam Expander

[0124] 171 Concave lens

[0125] 172 Convex lens

[0126] 21st integrator optical system

[0127] 21 No.1 Fly Eye Lens

[0128] 21a Page 1

[0129] 21b Page 2

[0130] 210 1st convex surface

[0131] 22. Fly Eye Lens

[0132] 3.3c Second integrator optical system

[0133] 31.3 Fly Eye Lens

[0134] 4 phase difference plate

[0135] 40 Incident surface

[0136] 411st phase difference plate

[0137] 42 2nd phase difference plate

[0138] 51st lens

[0139] 6The second lens

[0140] 7Third lens

[0141] 8Fourth lens

[0142] 95th lens

[0143] 201st Illumination Optical System

[0144] 30, 30c Second illumination optical system

[0145] 100, 100a, 100b, 100c optical device

[0146] 200 display devices

[0147] 201 Spatial Modulator

[0148] 202 lens

[0149] A-axis

[0150] L Laser

[0151] Lm mixed color light

[0152] LR 1st Laser

[0153] LG 2nd Laser

[0154] LB 3rd Laser

[0155] Lp P polarized light

[0156] Ls S polarized light

[0157] Lu Synthetic Light

[0158] S irradiation surface

[0159] WWidth

Claims

1. An optical device, comprising: Laser light source; a first integrator optical system that transmits the laser light emitted from the laser light source; a second integrator optical system that transmits the laser light emitted from the first integrator optical system; and The phase difference plate is arranged between the laser light source and the second integrator optical system, and rotates the polarization of the transmitted laser light by 90 degrees by transmitting a part of the laser light.

2. The optical device according to claim 1, wherein: The phase difference plate transmits half of the laser light.

3. The optical device according to claim 1 or 2, wherein: The laser light source is a light emitting device having a plurality of semiconductor laser elements. The semiconductor laser elements respectively emit the laser light.

4. The optical device according to claim 3, wherein: The phase difference plate is arranged so that half of the laser light emitted from one of the semiconductor laser elements is transmitted through the phase difference plate.

5. The optical device according to any one of claims 1 to 4, wherein: The laser light source emits a plurality of laser beams having different colors.

6. The optical device according to any one of claims 1 to 5, wherein: The phase difference plate is arranged between the laser light source and the first integrator optical system.

7. The optical device according to any one of claims 1 to 6, wherein: The phase difference plate is arranged between the first integrator optical system and the second integrator optical system.

8. The optical device according to any one of claims 1 to 7, wherein: The optical device further includes a synthesis optical system disposed between the laser light source and the first integrator optical system and used for synthesizing the plurality of laser beams. The phase difference plate transmits a part of the synthesized light of the plurality of laser beams from the synthesizing optical system, and rotates the polarization of the transmitted synthesized light by 90 degrees.

9. The optical device according to claim 8, wherein: The laser light source emits a plurality of lasers of different colors. The synthesis optical system includes a mirror group for synthesizing the plurality of laser lights having different colors.

10. The optical device according to claim 8 or 9, wherein: The synthetic optical system includes a beam expander for expanding a maximum width of the laser light in a direction orthogonal to an optical axis of the optical device.

11. An optical device according to any one of claims 8 to 10, wherein: The phase difference plate is arranged between the synthesis optical system and the first integrator optical system, and the synthesized light from the synthesis optical system is vertically incident on the incident surface of the phase difference plate.

12. An optical device according to any one of claims 8 to 11, wherein: The phase difference plate is arranged on the side of the first integrator optical system opposite to the side where the combining optical system is located.

13. A display device comprising: An optical device according to any one of claims 1 to 12; a spatial modulator for generating an image by modulating the spatial intensity distribution of the laser light from the optical device; and A lens transmits the image generated by the spatial modulator.

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