Optical system, display device, projection device, and lighting device

Abstract

To provide an optical system with a high light usage efficiency.SOLUTION: The optical system includes: a coherent light source; and a fixation diffusion plate and a relative moving diffusion plate which intersect with the direction in which light emitted from the coherent light source travels. The fixation diffusion plate emits incident light in a rectangle pattern. In the relative moving diffusion plate, a light diffusion surface relatively moves with respect to the incident light. When the diffusion angle of the fixation diffusion plate is denoted by θa and the diffusion angle of the relative moving diffusion plate is denoted by θb, the relations of θb / θa≤0.76 and θa≤16 are satisfied.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an optical system, a display device, a projection device, and an illumination device.

Background Art

[0002] A diffusion plate diffuses incident light in various directions. The diffusion plate is used in various applications such as displays, projectors, and lighting.

[0003] For example, Patent Document 1 describes a projector using laser light emitted from a laser light source. The projector described in Patent Document 1 displays a rectangular image by passing the laser light through a diffusion plate and a light pipe. Further, Patent Document 2 describes a light source device provided with a plurality of diffusion regions adjacent to each other and having different diffusion characteristics, and each of the plurality of diffusion regions is rotatable around a rotation axis.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the projector described in Patent Document 1, circularly diffused light by a diffusion plate is incident on a rectangular light pipe. As a result, there is an optical input loss in the projector described in Patent Document 1. Further, in the light source device of Patent Document 2, the shape of the diffused light becomes circular as the light diffusion element having a plurality of diffusion regions rotates. As a result, there is an optical input loss in the light diffusion element described in Patent Document 2.

[0006] The present invention has been made in view of the above problems, and an object thereof is to provide an optical system, a display device, a projection device, and a lighting device with high light utilization efficiency.

Means for Solving the Problems

[0007] In order to solve the above problems, the present invention provides the following means.

[0008] The optical system according to the first aspect includes a coherent light source, a fixed diffusion plate and a relative movement diffusion plate that intersect the traveling direction of the light emitted from the coherent light source. The fixed diffusion plate emits incident light in a rectangular shape, and the relative movement diffusion plate has a diffusion surface of light that moves relative to the incident light.

[0009] In the optical system according to the above aspect, the fixed diffusion plate and the relative movement diffusion plate may be arranged in the order of the fixed diffusion plate and the relative movement diffusion plate with respect to the traveling direction of the light.

[0010] In the optical system according to the above aspect, the fixed diffusion plate and the relative movement diffusion plate may be arranged in the order of the relative movement diffusion plate and the fixed diffusion plate with respect to the traveling direction of the light.

[0011] In the optical system according to the above aspect, the relative movement diffusion plate may be a rotatable rotation diffusion plate whose rotation surface intersects the traveling direction of the light.

[0012] In the optical system according to the above aspect, the relative movement diffusion plate may have convex lenses or concave lenses with random radii of curvature randomly arranged on the diffusion surface.

[0013] In the optical system according to the above aspect, when the diffusion angle of the fixed diffusion plate is θa and the diffusion angle of the relative movement diffusion plate is θb, θb / θa≤0.76 may be satisfied.

[0014] In the optical system according to the above aspect, the fixed diffusion plate may be a microlens array in which a plurality of microlenses are arranged in a matrix in a plan view.

[0015] The optical system according to the above aspect further includes an integrator lens, and the integrator lens may be behind the fixed diffusion plate and the relative movement diffusion plate with respect to the traveling direction of the light.

[0016] The optical system according to the above aspect further includes an integrator lens, the integrator lens is behind the fixed diffusion plate and the relative movement diffusion plate with respect to the traveling direction of the light, and the microlens array has a plurality of row virtual lines extending in the row direction through the average position in the column direction of the centers of the microlenses arranged in the row direction among the plurality of microlenses, and a plurality of column virtual lines extending in the column direction through the average position in the row direction of the centers of the microlenses arranged in the column direction among the plurality of microlenses, and has a basic cell region surrounded by the plurality of row virtual lines and the plurality of column virtual lines, and the ratio of the long side to the short side of the integrator lens may be substantially the same as the ratio of the long side to the short side of the basic cell region.

[0017] The display device according to the second aspect includes the optical system according to the above aspect.

[0018] The projection device according to the third aspect includes the optical system according to the above aspect.

[0019] The lighting device according to the fourth aspect includes the optical system according to the above aspect.

Advantages of the Invention

[0020] According to the optical system according to the above aspect, the utilization efficiency of light can be increased.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

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Figure 11

Embodiments for Carrying Out the Invention

[0022] Hereinafter, this embodiment will be described in detail with appropriate reference to the drawings. The drawings used in the following description may show, for the sake of clarity, parts that are characteristic by being enlarged for convenience, and the dimensional ratios of each component may be different from the actual ones. The materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not limited thereto, and it can be appropriately modified and implemented within the scope where the effects of the present invention are achieved.

[0023] FIG. 1 is a schematic diagram of an optical system 100 according to a first embodiment. The optical system 100 includes coherent light sources 10B, 10G, 10R, a fixed diffusion plate 20, a rotating diffusion plate 30, and an integrator lens 40. The optical system 100 shown in FIG. 1 further includes a dichroic mirror DM.

[0024] First, directions will be defined. The plane on which the fixed diffusion plate 20 extends is defined as the xy plane, any direction in the xy plane is defined as the x direction, and the direction orthogonal to the x direction is defined as the y direction. The x direction is an example of a row direction. The y direction is an example of a column direction. Further, the direction orthogonal to the fixed diffusion plate 20 is defined as the z direction.

[0025] Coherent light sources 10B, 10G, and 10R emit coherent light. The coherent light sources 10B, 10G, and 10R are, for example, lasers. The coherent light source 10B shown in FIG. 1 is a blue laser, the coherent light source 10G is a green laser, and the coherent light source 10R is a red laser. The coherent light sources may prepare each color, or may generate yellow, green, and red by irradiating a phosphor with a blue laser. In FIG. 1, each color emitted from the respective coherent light sources 10B, 10G, and 10R is converged using a dichroic mirror DM to realize white light.

[0026] Coherent light produces speckle noise. Speckle noise is a random fine interference pattern generated as noise by the diffusion action in the irradiated object (e.g., a screen) and the interference with coherent laser light. Speckle noise, for example, causes a significant reduction in the image quality of an image. When speckle noise occurs, each color flickers and does not become white.

[0027] Light from the coherent light sources 10B, 10G, and 10R is incident on the fixed diffuser plate 20 and the rotating diffuser plate 30. By spreading the coherent light with the fixed diffuser plate 20 and the rotating diffuser plate 30, the speckle noise is reduced. The optical system 100 shown in FIG. 1 is arranged in the order of the fixed diffuser plate 20 and the rotating diffuser plate 30 with respect to the traveling direction of light.

[0028] The fixed diffuser plate 20 is a rectangular diffuser plate that diffuses incident light into a rectangle. Diffusing incident light into a rectangle means that the ratio of the 10% angular width in the x direction to the 10% angular width in the xy direction of the diffused light is less than 1. The 10% angular width of the diffused light is the range of angles at which the intensity becomes 10% or more of the maximum intensity in the intensity distribution fitted with a Gaussian function.

[0029] The fixed diffuser plate 20 is, for example, a microlens array. FIG. 2 is a plan view of the fixed diffuser plate 20 according to the first embodiment. FIG. 3 is a cross-sectional view of the fixed diffuser plate 20 according to the first embodiment. FIG. 3 is a cross-section obtained by cutting the fixed diffuser plate 20 along the virtual line Vc in FIG. 2.

[0030] In the fixed diffuser plate 20, for example, in a plan view from the z direction, a plurality of microlenses 21 are arranged in a matrix. Each of the microlenses 21 is, for example, substantially rectangular. Each of the plurality of microlenses 21 is arranged based on a basic pattern.

[0031] The basic pattern is a pattern in which basic cell regions surrounded by the virtual row line Vc and the virtual column line Vr are aligned in the x direction and the y direction. The virtual row line Vc is a plurality of virtual lines extending in the x direction and passing through the average position in the column direction (y direction) of the centers of the microlenses 21 arranged in the row direction (x direction). The virtual column line Vr is a plurality of virtual lines extending in the y direction and passing through the average position in the row direction (x direction) of the centers of the microlenses 21 arranged in the column direction (y direction).

[0032] The minimum unit surrounded by two virtual row lines Vc and two virtual column lines Vr is the basic cell region. When the ratio of the length Gx in the x direction to the length Gy in the y direction of the basic cell region substantially matches the ratio of the length in the x direction to the length in the y direction of the integrator lens 40 described later, the light utilization efficiency of the optical system 100 is particularly enhanced. Substantially matching means being within a numerical range of 10% based on any value.

[0033] In the fixed diffuser plate 20, the microlenses 21 are densely present. That is, there is no non-lens region between the microlenses 21. Therefore, ridges are formed between the microlenses 21. When the height and direction of the ridges are irregular, diffraction by the fixed diffuser plate 20 is suppressed. It is preferable that adjacent ridges are not parallel to each other.

[0034] The microlens 21 is, for example, a concave lens that is recessed with respect to the reference plane Rp of the fixed diffuser plate 20. The microlens 21 may be, for example, a convex lens that protrudes with respect to the reference plane Rp. The reference plane Rp is a plane parallel to the xy plane and is a plane that contacts the most protruding portion of the first surface 20a. The reference plane Rp is, for example, the surface of the substrate before processing the concave portion that will become the microlens 21 of the fixed diffuser plate 20. In FIG. 3, an example where the microlens 21 is only on the first surface 20a of the fixed diffuser plate 20 is shown, but the microlens 21 may be on both the first surface 20a and the second surface 20b. The respective radii of curvature of the microlens 21 may be random.

[0035] The fixed diffuser plate 20 is made of, for example, a material that can transmit light in the incident wavelength band. The fixed diffuser plate 20 is, for example, optical glass, crystal, sapphire, a resin plate, or a resin film. The optical glass is, for example, quartz glass, borosilicate glass, white plate glass, etc. The resin is, for example, polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polycarbonate (PC), cyclic olefin copolymer (COC), etc. The inorganic materials of optical glass, crystal, and sapphire are excellent in light resistance. Also, crystal and sapphire are excellent in heat dissipation.

[0036] The fixed diffuser plate 20 is manufactured by a resist coating process, an exposure and development process, and an etching process. FIGS. 4 and 5 are schematic diagrams for explaining an example of the manufacturing method of the fixed diffuser plate 20.

[0037] First, in the resist coating process, a resist R1 is coated on a substrate S. The substrate S is made of the same material as the fixed diffuser plate 20 described above because it will become the fixed diffuser plate 20 through processing. In the etching process described later, fluorine-based etching gases (such as CF4, SF6, CHF3, etc.) may be used as the etching gas. Al2O3 and alkali metals, etc., may react with the fluorine-based etching gas to become non-volatile substances. For example, when etching a glass substrate (such as Eagle XG manufactured by Corning) that does not contain alkali metals but contains 27% Al2O3 with a fluorine-based etching gas, it is difficult to etch the remaining Al2O3, micro-protrusions are generated on the surface, and the transmittance of the glass substrate decreases. The substrate S preferably has an alkali component content of 20 mass% or less, and more preferably 10 mass% or less. The substrate S is preferably, for example, quartz glass or temperax glass. A known resist R1 can be applied.

[0038] Next, in the exposure process, the resist R1 is irradiated with light L1 through a gray scale mask Gm to expose the resist R1. The exposure is performed, for example, by repeating the exposure while moving the gray scale mask and performing step-and-repeat exposure. Depending on the positioning accuracy of the stepping, joints with a width of up to about several μm may occur between the basic cells formed by a single exposure. To avoid such problems, it is preferable to perform the exposure so that the basic cells overlap each other. When the basic cells are overlapped significantly, it may be adjusted so that the desired exposure amount is obtained by multiple exposures.

[0039] The gray scale mask Gm is designed based on the basic pattern. The basic pattern is equivalent to the pattern formed by the above-described row virtual line Vc and column virtual line Vr. The gray scale mask Gm is produced by shifting the intervals G x , G y , the positions of the vertices c of the respective microlenses, and the parameters of the curvature radii of the respective microlenses, respectively. By varying these parameters, the output of the diffraction pattern from the fixed diffuser plate 20 is suppressed.

[0040] Next, in the development process, the exposed resist pattern is developed. By development, a part of the resist R1 is removed, and the resist R2 having a resist pattern on the surface is obtained. On the surface of the resist R2, a resist pattern similar to the desired microlens array is formed.

[0041] Next, in the etching process, the substrate S is dry-etched through the resist R2. The dry etching is performed using, for example, a reactive gas G. The gas G is, for example, the fluorine-based etching gas described above. By the dry etching, the pattern of the microlens array formed on the surface of the resist R2 is transferred to the substrate S. The substrate S becomes the fixed diffusion plate 20 having the microlens array formed on the first surface.

[0042] The rotating diffusion plate 30 has a rotating surface that intersects the traveling direction of light and is rotatable. By rotating the rotating diffusion plate 30, the diffusion surface of light moves relative to the incident light. The rotating diffusion plate 30 is an example of a relative movement diffusion plate. The rotating diffusion plate 30 may be any plate as long as the diffusion surface of light moves relative to the incident light. For example, instead of the rotating diffusion plate 30, a vibrating diffusion plate that vibrates may be used.

[0043] The rotating diffusion plate 30 is, for example, a frosted diffusion plate or a microlens diffusion plate. The rotating diffusion plate 30 may be a rectangular diffusion plate that diffuses incident light into a rectangle or a circular diffusion plate that diffuses incident light into a circle even when it is not rotating. When the rotating diffusion plate 30 is used alone, regardless of whether a rectangular diffusion plate or a circular diffusion plate is used, the diffused light becomes circular because the diffusion surface moves relative to the incident light.

[0044] The rotating diffusion plate 30 has, for example, convex lenses or concave lenses with random radii of curvature randomly arranged on the diffusion surface. Because the radius of curvature and the arrangement are random, coherent light is efficiently spread, and the generation of speckle noise is likely to be reduced.

[0045] The fixed diffuser plate 20 and the rotating diffuser plate 30 may have an antireflection film on at least one surface. The antireflection film is, for example, a laminated film in which a low refractive index layer and a high refractive index layer are laminated. The low refractive index layer is, for example, SiO2, MgF2, or CaF2. The high refractive index layer is, for example, Nb2O5, TiO2, Ta2O5, Al2O3, HfO2, or ZrO2. SiO2, Nb2O5, and Ta2O5 have excellent light resistance and are less likely to deteriorate even when irradiated with light of high optical density emitted by a high-power laser or the like. The antireflection film may also have a moth-eye structure in which fine irregularities with a pitch of several hundred nm are arranged.

[0046] It is preferable that the diffusion angle θa of the fixed diffuser plate 20 and the diffusion angle θb of the rotating diffuser plate 30 satisfy θb / θa ≤ 0.76.

[0047] FIG. 6 is a schematic diagram for explaining the definition of the diffusion angles of the fixed diffuser plate 20 and the rotating diffuser plate 30. The diffusion angle θ of the diffuser plate is obtained based on the following relationship from the average radius of curvature R of the lens, the refractive index n of the diffuser plate, and the average interval p between adjacent lenses. θ = 2sin -1 {(p(n - 1) / 2R) The diffusion angle θ of the diffuser plate can also be defined as the divergence angle of the light emitted from the diffuser plate when parallel light is incident.

[0048] When the diffusion angle θa and the diffusion angle θb satisfy the above relationship, the light after passing through the two diffuser plates becomes rectangular. As described above, when the rotating diffuser plate 30 is used alone, the passed light spreads in a circular shape in principle. In contrast, when two diffuser plates are used and these two diffuser plates satisfy the above relationship, the passed light becomes rectangular. The light after passing through the diffuser plate is irradiated onto an integrator lens or an image display device. These members are quadrilateral, and when the diffused light is rectangular, the light utilization efficiency is increased.

[0049] The integrator lens 40 is a lens that enhances the uniformity of illuminance on the irradiation surface. By allowing light to pass through the integrator lens 40, the accuracy of the projected image is increased. The integrator lens 40 is located behind the fixed diffuser plate 20 and the rotating diffuser plate 30 with respect to the traveling direction of light.

[0050] When the ratio of the length in the x - direction to the length in the y - direction of the integrator lens 40 substantially coincides with the ratio of the length Gx in the x - direction to the length Gy in the y - direction of the basic cell region, the light utilization efficiency of the optical system 100 is particularly enhanced.

[0051] When using the optical system according to this embodiment, the light utilization efficiency is higher than when using a circular diffusion plate in which the diffused light on the fixed diffusion plate 20 is circular. Further, by satisfying a predetermined relationship between the diffusion angle θa of the fixed diffusion plate 20 and the diffusion angle θb of the rotating diffusion plate 30, the light passing through the two diffusion plates can be made closer to a rectangle, and the light utilization efficiency can be further enhanced.

[0052] Although the first embodiment has been described in detail above, it is not limited to this example, and various modifications and changes are possible within the scope of the gist of the present invention described within the claims.

[0053] FIG. 7 is a schematic diagram of an optical system 101 according to the first modification. In the optical system 101 according to the first modification, the arrangement order of the fixed diffusion plate 20 and the rotating diffusion plate 30 is different from that of the above - described optical system 100. For the components having the same configuration as those in the optical system 100 in the optical system 101 according to the first modification, the same reference numerals are given and the description is omitted.

[0054] In the optical system 101 shown in FIG. 7, in the light traveling direction, the rotating diffusion plate 30, the fixed diffusion plate 20, and the integrator lens 40 are arranged in this order. Even if the arrangement order of the rotating diffusion plate 30 and the fixed diffusion plate 20 is reversed, the light after passing through the two diffusion plates is the same. Therefore, the optical system 101 according to the first modification can also obtain the same effects as those of the above - described optical system 100.

[0055] The above - described optical systems 100 and 101 can be used in display devices, projection devices, lighting devices, etc.

[0056] FIG. 8 is a schematic diagram of a display device DP according to a first application example. The display device DP is, for example, a laser television or a DLP projector. The display device DP includes a coherent light source 10B, a fixed diffuser 20, a plurality of mirrors M, a phosphor wheel PW, a rotating diffuser 30, an integrator lens 40, a plurality of lenses L, a digital microdevice DLD, and a prism TIR.

[0057] Blue light is emitted from the coherent light source 10B. After passing through the fixed diffuser 20 and the phosphor wheel PW, the light is incident on the rotating diffuser 30. The phosphor wheel PW generates yellow (green, red) when irradiated with a blue laser, and these lights reach the rotating diffuser 30. The light after passing through the rotating diffuser 30 is condensed by the integrator lens 40 and the plurality of lenses L. The condensed light reaches the digital microdevice DLD via the prism TIR. The digital microdevice DLD controls the ON and OFF of the light and outputs the light to the outside via the prism TIR.

Example

[0058] In the following Examples 1 to 15 and Comparative Examples 1 to 20, the optical system shown in FIG. 9 was designed, and the diffused light was evaluated by simulation. The optical system includes a coherent light source 10, a fixed diffuser 20, a rotating diffuser 30, and a screen Sc. The coherent light source 10 outputs light with an intensity of 1 W and a spot diameter of 0.6 mm. The distance between the coherent light source 10 and the fixed diffuser 20 was set to 5 mm. The distance between the fixed diffuser 20 and the rotating diffuser 30 was set to 0.5 mm. The distance between the rotating diffuser 30 and the screen Sc was set to 200 mm. The simulation was performed using OpticStudio from Zemax.

[0059] The entire area of the screen was set to 40 mm × 40 mm, and the evaluation area was set to an area of 18.5 mm × 18.5 mm in the center of the entire area. Then, the light utilization efficiency of the evaluation area with respect to the entire area, and the diffusion characteristics in the x direction and the xy direction were determined. The xy direction is a direction inclined by 45° with respect to each of the x direction and the y direction. FIG. 10 is a schematic diagram for explaining the diffused light in the examples and comparative examples. The diffusion characteristics in the x direction and the xy direction were evaluated by the 10% angular width of the diffused light in the x direction and the xy direction. As described above, the 10% angular width of the diffused light is the range of angles at which the intensity becomes 10% or more of the maximum intensity in the intensity distribution fitted with a Gaussian function.

[0060] "Examples 1 to 4, Comparative Examples 1 to 6" In Examples 1 to 4, the fixed diffusion plate 20 was a rectangular diffusion plate that diffused incident light into a rectangle, and the rotating diffusion plate 30 was a circular diffusion plate that diffused incident light into a circle. In Comparative Examples 1 to 6, the fixed diffusion plate 20 was a circular diffusion plate, and the rotating diffusion plate 30 was a circular diffusion plate. In Examples 1 to 4 and Comparative Examples 1 to 6, the detection intensity of the entire area was set to about 1425 mW. In Examples 1 to 4, the diffusion angle θa of the fixed diffusion plate 20 was set to 5°, and in Comparative Examples 1 to 6, the diffusion angle θa of the fixed diffusion plate 20 was set to 7°. Then, the diffusion angle θb of the rotating diffusion plate 30 was changed, and evaluations were performed for each case. The results are summarized in Table 1 below.

[0061]

Table 1

[0062] Examples 1 to 4 had higher light utilization efficiency compared to Comparative Examples 1 to 6. Also, when the diffusion angle θb / diffusion angle θa was less than 0.8, the shape of the diffused light approached a rectangle.

[0063] "Examples 5 to 8, Comparative Examples 7 to 13" In Examples 5 to 8, the fixed diffusion plate 20 was a rectangular diffusion plate, and the rotating diffusion plate 30 was a circular diffusion plate. In Comparative Examples 7 to 13, the fixed diffusion plate 20 was a circular diffusion plate, and the rotating diffusion plate 30 was a circular diffusion plate. In Examples 5 to 8 and Comparative Examples 7 to 13, the detection intensity of the entire area was set to about 300 mW. In Examples 5 to 8, the diffusion angle θa of the fixed diffusion plate 20 was set to 10°, and in Comparative Examples 7 to 13, the diffusion angle θa of the fixed diffusion plate 20 was set to 14°. Then, the diffusion angle θb of the rotating diffusion plate 30 was changed, and the evaluation was performed for each case. The results are summarized in Table 2 below.

[0064]

Table 2

[0065] Examples 5 to 8 had a higher light utilization efficiency compared to Comparative Examples 7 to 13. Also, when the diffusion angle θb / diffusion angle θa was less than 0.8, the shape of the diffused light approached a rectangle.

[0066] "Examples 9 to 15, Comparative Examples 14 to 20" In Examples 9 to 15, the fixed diffusion plate 20 was a rectangular diffusion plate, and the rotating diffusion plate 30 was a circular diffusion plate. In Comparative Examples 14 to 20, the fixed diffusion plate 20 was a circular diffusion plate, and the rotating diffusion plate 30 was a circular diffusion plate. In Examples 9 to 15 and Comparative Examples 14 to 20, the detection intensity of the entire area was set to about 100 mW. In Examples 9 to 15, the diffusion angle θa of the fixed diffusion plate 20 was set to 16°, and in Comparative Examples 14 to 20, the diffusion angle θa of the fixed diffusion plate 20 was set to 22°. Then, the diffusion angle θb of the rotating diffusion plate 30 was changed, and the evaluation was performed for each case. The results are summarized in Table 3 below.

[0067]

Table 3

[0068] Examples 9 to 15 had a higher light utilization efficiency compared to Comparative Examples 14 to 20. Also, when the diffusion angle θb / diffusion angle θa was less than 0.8, the shape of the diffused light approached a rectangle.

[0069] Also, the results of these Examples and Comparative Examples are summarized in FIG. 11. As shown in FIG. 11, if the diffusion angle θb / diffusion angle θa is 0.76 or less, the light utilization efficiency can be increased from the maximum value of the light utilization efficiency in the Comparative Examples.

Explanation of Signs

[0070] 10, 10B, 10G, 10R coherent light sources 20 fixed diffuser 21 microlens 30 rotating diffuser 40 integrator lens 100, 101 optical systems DP display device Vc row virtual line Vr column virtual line θ, θa, θb diffusion angles

Claims

1. A coherent light source, A fixed diffuser plate and a relative movement diffuser plate that intersect the traveling direction of the light emitted from the coherent light source, The fixed diffuser plate emits incident light in a rectangle, In the relative movement diffuser plate, the diffusion surface of the light moves relative to the incident light, When the diffusion angle of the fixed diffuser plate is θa and the diffusion angle of the relative movement diffuser plate is θb, θb / θa ≤ 0.76, θa ≤ 16 is satisfied, The fixed diffuser plate is a microlens array in which a plurality of microlenses are arranged in a matrix in a plan view, Further comprising an integrator lens, The integrator lens is behind the fixed diffuser plate and the relative movement diffuser plate with respect to the traveling direction of the light, The microlens array, A plurality of row virtual lines extending in the row direction passing through the average position in the column direction of the centers of the microlenses arranged in the row direction among the plurality of microlenses, A plurality of column virtual lines extending in the column direction passing through the average position in the row direction of the centers of the microlenses arranged in the column direction among the plurality of microlenses, Has a basic cell region surrounded by, An optical system in which the ratio of the long side to the short side of the integrator lens is substantially the same as the ratio of the long side to the short side of the basic cell region.

2. The optical system according to claim 1, wherein the fixed diffuser plate and the relative movement diffuser plate are arranged in the order of the fixed diffuser plate and the relative movement diffuser plate with respect to the traveling direction of the light.

3. The optical system according to claim 1, wherein the fixed diffuser plate and the relative movement diffuser plate are arranged in the order of the relative movement diffuser plate and the fixed diffuser plate with respect to the traveling direction of the light.

4. The optical system according to any one of claims 1 to 3, wherein the relative movement diffuser plate is a rotatable rotation diffuser plate whose rotation surface intersects the traveling direction of the light.

5. The optical system according to any one of claims 1 to 4, wherein the relative movement diffuser plate has convex lenses or concave lenses with random radii of curvature randomly arranged on the diffusion surface.

6. A display device including the optical system according to any one of claims 1 to 5.

7. A projection device including the optical system according to any one of claims 1 to 5.

8. A lighting device including the optical system according to any one of claims 1 to 5.

Images