Optical system and projector

Abstract

Provided are an optical system and a projector that can bring a first reflection surface and a second reflection surface close to each other. The optical system includes a first optical element and a second optical element disposed on a reduction side of the first optical element. The first optical element has a concave first reflection surface, and the second optical element has a first transmission surface, a second reflection surface disposed on a reduction side of the first transmission surface, and a second transmission surface disposed on a reduction side of the second reflection surface. A first optical axis of the first reflection surface is parallel to a second optical axis of the first transmission surface. At least one of the first transmission surface, the second reflection surface, and the second transmission surface has a refractive power.

Description

Technical Field

[0001] This invention relates to optical systems and projectors. Background Technology

[0002] Patent Document 1 describes a projection optical system comprising a projection lens, a first reflector, and a second reflector arranged sequentially from the reduction side to the magnification side. The first reflector is planar, and the second reflector is concave. When the projection optical system is used in a projector, an image display element is disposed on the image plane of the reduction side of the projection optical system. A screen is disposed on the image plane of the magnification side of the projection optical system. In this document, the projected light incident on the first reflector from the image display element side through the projection lens is a diffuse beam. After being reflected by the first reflector and then by the second reflector, the projected light is temporarily focused before reaching the screen disposed on the image plane of the magnification side.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2013-064816

[0004] In the projection optical system of Patent Document 1, in order to prevent the first reflecting mirror located on the magnification side of the projection lens from physically interfering with both the projection lens and the second reflecting mirror, it is necessary to ensure a relatively wide air gap between the first and second reflecting mirrors. Therefore, it is difficult to bring the first and second reflecting mirrors close together, thus increasing the size of the projection optical system. Summary of the Invention

[0005] To address the aforementioned issues, the optical system of the present invention comprises: a first optical element; and a second optical element disposed on the reduced side of the first optical element, the first optical element having a concave first reflecting surface, and the second optical element comprising: a first transmitting surface; a second reflecting surface disposed on the reduced side of the first transmitting surface; and a second transmitting surface disposed on the reduced side of the second reflecting surface, wherein a first optical axis of the first reflecting surface is parallel to a second optical axis of the first transmitting surface, and at least one of the first transmitting surface, the second reflecting surface, and the second transmitting surface has refractive power.

[0006] Next, the projector of the present invention includes: a light modulation element disposed on a conjugate surface on the reduction side to modulate light emitted from a light source; and the aforementioned optical system that projects light modulated by the light modulation element. Attached Figure Description

[0007] Figure 1 This is a diagram showing a schematic structure of a projector having the optical system of the present invention.

[0008] Figure 2 This is a schematic diagram showing the overall light pattern of the optical system of Embodiment 1.

[0009] Figure 3 This is a ray diagram of the optical system in Example 1.

[0010] Figure 4 This is a diagram showing the MTF on the magnification side of the optical system of Embodiment 1.

[0011] Figure 5 This is a spot diagram of the optical system in Example 1.

[0012] Figure 6 This is a schematic diagram showing the overall light pattern of the optical system of Embodiment 2.

[0013] Figure 7 This is a ray diagram of the optical system in Example 2.

[0014] Figure 8 This is a diagram showing the MTF on the magnified side of the optical system of Embodiment 2.

[0015] Figure 9 This is a dot diagram of the optical system in Example 2.

[0016] Figure 10 This is a schematic diagram showing the overall light pattern of the optical system of Embodiment 3.

[0017] Figure 11 This is a ray diagram of the optical system in Example 3.

[0018] Figure 12 This is a light diagram of the first optical system in Example 3.

[0019] Figure 13 This is a diagram showing the MTF on the magnification side of the optical system of Embodiment 3.

[0020] Figure 14 This is a dot diagram of the optical system in Example 3.

[0021] Figure 15 This is a schematic diagram showing the overall light pattern of the optical system of Embodiment 4.

[0022] Figure 16 This is a ray diagram of the optical system in Example 4.

[0023] Figure 17 This is a light diagram of the first optical system in Example 4.

[0024] Figure 18 This is a diagram showing the MTF on the magnified side of the optical system of Embodiment 4.

[0025] Figure 19 This is a dot diagram of the optical system in Example 4.

[0026] Label Explanation

[0027] 1: Projector; 2: Image forming unit; 3, 3A, 3B, 3C, 3D: Optical system; 4: Control unit; 6: Image processing unit; 7: Display driving unit; 10: Light source; 11: Integrator lens; 12: Integrator lens; 13: Polarization conversion element; 14: Overlapping lens; 15: Dichroic mirror; 16: Reflector; 17R: Field lens; 17G: Field lens; 17B: Field lens; 18 (18B, 18R, 18G): Liquid crystal panel; 19: Cross-shaped dichroic prism; 21: Dichroic mirror; 22: Relay lens; 23: Reflector; 24: Relay lens; 25: Reflector; 3 0: Intermediate image; 31: First optical system; 32: Second optical system; 33: First optical element; 34: Second optical element; 35: Correction lens; 36: Correction optical element; 37: Second relay element; 38: First relay element; 40: First reflecting surface; 41: Third transmitting surface; 42: First reflecting surface; 43: Fourth transmitting surface; 51: First transmitting surface; 52: Second reflecting surface; 53: Second transmitting surface; 61: First lens surface; 62: Second lens surface; L1~L15: Lens; N: Optical axis; M: Optical axis; P: Maximum effective point; Q: Imaginary line; S: Screen. Detailed Implementation

[0028] Hereinafter, the optical system and projector of embodiments of the present invention will be described with reference to the accompanying drawings.

[0029] (Projector)

[0030] Figure 1 This is a diagram showing a schematic structure of a projector having the optical system 3 of the present invention. (See diagram for example.) Figure 1 As shown, the projector 1 includes: an image forming unit 2 that generates a projected image that is projected onto a screen S; an optical system 3 that magnifies the projected image and projects a magnified image onto the screen S; and a control unit 4 that controls the operation of the image forming unit 2.

[0031] (Image forming unit and control unit)

[0032] The image forming unit 2 includes a light source 10, a first integrator lens 11, a second integrator lens 12, a polarization conversion element 13, and an overlapping lens 14. The light source 10 is, for example, an ultra-high pressure mercury lamp or a solid-state light source. The first integrator lens 11 and the second integrator lens 12 each have multiple lens elements arranged in an array. The first integrator lens 11 splits the light beam from the light source 10 into multiple segments. Each lens element of the first integrator lens 11 converges the light beam from the light source 10 to the vicinity of each lens element of the second integrator lens 12.

[0033] The polarization conversion element 13 converts the light from the second integrator lens 12 into linearly polarized light. The overlapping lens 14 causes the images of each lens element of the first integrator lens 11 to be superimposed on the display areas of the liquid crystal panels 18R, 18G, and 18B, as described later, via the second integrator lens 12.

[0034] Additionally, the image forming unit 2 includes a first dichroic mirror 15, a reflector 16, a field lens 17R, and a liquid crystal panel 18R. The first dichroic mirror 15 reflects the red light, which is part of the light incident from the overlapping lens 14, while allowing the G light and B light, which are also part of the light incident from the overlapping lens 14, to pass through. The red light reflected by the first dichroic mirror 15 passes through the reflector 16 and the field lens 17R and is incident on the liquid crystal panel 18R. The liquid crystal panel 18R is a light modulation element. The liquid crystal panel 18R modulates the red light according to the image signal, thereby forming a red projected image.

[0035] Furthermore, the image forming unit 2 includes a second dichroic mirror 21, a field lens 17G, and a liquid crystal panel 18G. The second dichroic mirror 21 reflects the G light, which is part of the light from the first dichroic mirror 15, and allows the B light, which is part of the light from the first dichroic mirror 15, to pass through. The G light reflected by the second dichroic mirror 21 is incident on the liquid crystal panel 18G via the field lens 17G. The liquid crystal panel 18G is a light modulation element. The liquid crystal panel 18G modulates the G light according to the image signal, thereby forming a green projected image.

[0036] Additionally, the image forming unit 2 includes a relay lens 22, a reflector 23, a relay lens 24, a reflector 25, a field lens 17B, a liquid crystal panel 18B, and a cross-shaped dichroic prism 19. B-light passing through the second dichroic mirror 21 passes through the relay lens 22, reflector 23, relay lens 24, reflector 25, and field lens 17B, and then enters the liquid crystal panel 18B. The liquid crystal panel 18B is a light modulation element. The liquid crystal panel 18B modulates the B-light according to the image signal, thereby forming a blue projected image.

[0037] Liquid crystal panels 18R, 18G, and 18B surround the cross-shaped dichroic prism 19 from three directions. The cross-shaped dichroic prism 19 is a prism used for light synthesis, generating a projected image by synthesizing the light modulated by each of the liquid crystal panels 18R, 18G, and 18B.

[0038] The optical system 3 magnifies and projects the image synthesized by the cross dichroic prism 19 onto the screen S.

[0039] The control unit 4 includes: an image processing unit 6, which receives external image signals such as video signals; and a display driving unit 7, which drives the liquid crystal panel 18R, liquid crystal panel 18G, and liquid crystal panel 18B according to the image signals output from the image processing unit 6.

[0040] The image processing unit 6 converts the image signal input from the external device into an image signal containing grayscale values ​​of various colors. The display driving unit 7 operates the liquid crystal panels 18R, 18G, and 18B according to the projected image signals of various colors output from the image processing unit 6. As a result, the image processing unit 6 displays the projected image corresponding to the image signal on the liquid crystal panels 18R, 18G, and 18B.

[0041] (Example 1)

[0042] Figure 2 This is a schematic diagram showing the overall light pattern of the optical system of Embodiment 1. Figure 3 This is a ray diagram of the optical system 3A in Example 1. (As shown) Figure 2 , Figure 3 As shown, a liquid crystal panel 18 is disposed on the conjugate surface of the reduced side of the optical system 3A.

[0043] In the following explanation, for convenience, the three mutually orthogonal axes are designated as the X-axis, Y-axis, and Z-axis. Furthermore, the width direction of screen S, which serves as the conjugate surface for magnification, is designated as the X-axis, the vertical direction of screen S as the Y-axis, and the direction perpendicular to screen S as the Z-axis. Along the Y-axis, the top of screen S is designated as the Y1 direction, and the bottom of screen S as the Y2 direction. Along the Z-axis, the side of screen S located on is designated as the Z1 direction, and the opposite side as the Z2 direction.

[0044] like Figure 2 As shown, the optical system 3A in this example has a first optical system 31 and a second optical system 32 arranged sequentially from the magnification side to the reduction side. The first optical system 31 is a reflective optical system. The first optical system 31 has a first optical element 33 and a second optical element 34. The first optical element 33 and the second optical element 34 are arranged sequentially from the magnification side to the reduction side. The optical axis M of the first optical element 33 extends along the Z-axis direction. That is, the optical axis M of the first optical element 33 is perpendicular to the screen S. The second optical system 32 is a refractive optical system. The optical axis N (the sixth optical axis) of the second optical system 32 extends along the Y-axis direction. The screen S is located in the Z1 direction of the optical axis N.

[0045] like Figure 3 As shown, the first optical element 33 has a first reflecting surface 40 facing the Z1 direction. The first reflecting surface 40 has a concave shape that is recessed in the Z2 direction. The first optical axis of the first reflecting surface 40 is the optical axis M of the first optical element 33. The first reflecting surface 40 has a rotationally symmetric shape centered on the first optical axis. The first reflecting surface 40 has an aspherical shape. Here, the first optical element 33 is designed with the optical axis M as the design axis. That is, the first optical axis is the optical axis in the design of the first reflecting surface 40.

[0046] The second optical element 34 is composed of a single optical element. The second optical element 34 is located in the Z1 direction of the first optical element 33. The second optical element 34 has a first transmission surface 51, a second reflection surface 52 located on the narrowing side of the first transmission surface 51, and a second transmission surface 53 located on the narrowing side of the second reflection surface 52.

[0047] The first transmitting surface 51 and the first reflecting surface 40 are opposite each other in the Z-axis direction. The first transmitting surface 51 has a convex shape facing the Z2 direction. The second optical axis of the first transmitting surface 51 is approximately parallel to the first optical axis of the first reflecting surface 40. In this example, the second optical axis of the first transmitting surface 51 coincides with the first optical axis of the first reflecting surface 40. In other words, the second optical axis of the first transmitting surface 51 coincides with the optical axis M of the first optical element 33. The first transmitting surface 51 has a rotationally symmetric shape about the second optical axis. The first transmitting surface 51 has positive refractive power. The first transmitting surface 51 has an aspherical shape.

[0048] The second reflecting surface 52 is a plane mirror without refractive power. The second reflecting surface 52 is tilted at 45° with respect to the Y-axis and Z-axis. The second reflecting surface 52 bends the light path by 90° between the first transmitting surface 51 and the second transmitting surface 53. The second reflecting surface 52 is formed by providing a reflective coating on the outer surface of the second optical element 34 in the Z1 direction.

[0049] The second transmission surface 53 faces the Y2 direction and is opposite to lens L15. The angle between the optical axis of the second transmission surface 53 and the second optical axis of the first transmission surface 51 is 90°. That is, the angle between the optical axis of the second transmission surface 53 and the optical axis M of the first optical element 33 is 90°. In addition, the optical axis of the second transmission surface 53 is aligned with the optical axis N of the second optical system 32. The second transmission surface 53 has a rotationally symmetric shape centered on the optical axis of the second transmission surface 53. The second transmission surface 53 has positive refractive power. The second transmission surface 53 has an aspherical shape.

[0050] like Figure 3 As shown, the second optical system 32 includes 15 lenses L1 to L15. Lenses L1 to L15 are arranged sequentially from the reduction side to the magnification side. In this example, lens L2 and lens L3 are combined to form the first combined lens L21. Lens L4 and lens L5 are combined to form the second combined lens L22. Lens L11 and lens L12 are combined to form the third combined lens L23. Lens L13 and lens L14 are combined to form the fourth combined lens L24. An aperture O is arranged between lens L9 and lens L10. Lenses L6, L9, and L15 are aspherical lenses with aspherical shapes on both sides. In the second optical system 32, each lens has a plane of rotational symmetry centered on the optical axis N.

[0051] Here, as Figure 3 As shown, the liquid crystal panel 18, disposed on the reduced-side conjugate surface of the optical system 3A, forms a projected image on the Z2 direction side of the optical axis N. Furthermore, the angle θ1 formed by the optical axis M of the first optical element 33 and the optical axis N of the second optical system 32 is 90° or less. In this example, the angle θ1 is 90°. Therefore, light from the liquid crystal panel 18 side, after passing through the second optical system 32, is bent by 90° by the second reflecting surface 52 of the second optical element 34 and directed towards the Z2 direction. The light directed towards the Z2 direction is reflected back towards the Z1 and Y1 directions by the first reflecting surface 40 of the first optical element 33 and reaches the screen S.

[0052] In addition, such as Figure 3 As shown, the optical system 3A forms an intermediate image 30 that is conjugate to both the reduction-side conjugate surface and the magnification-side conjugate surface between the reduction-side conjugate surface and the magnification-side conjugate surface. In this example, the intermediate image 30 is formed between the first reflecting surface 40 of the first optical element 33 and the second transmitting surface 53 of the second optical element 34.

[0053] The lens data for optical system 3A is as follows. The surface numbers are sequentially labeled from the reduction side to the magnification side. The labels are for the LCD panel, dichroic prism, lens, and screen. Data with surface numbers that do not correspond to those for the LCD panel, dichroic prism, lens, and screen is virtual data. Surfaces marked with an asterisk (*) are aspherical surfaces. R is the radius of curvature. D is the on-axis spacing. nd is the refractive index. νd is the Abbe number. Y is the aperture radius. The units for R, D, and Y are mm. Furthermore, the lens data in this example was designed using Synopsys CODE V.

[0054]

[0055] The aspherical coefficients are as follows.

[0056]

[0057]

[0058] The coordinates of the light rays on the object's surface are as follows.

[0059]

[0060] Additionally, in this example, face number 33 is an eccentric face. The parameters of the eccentric face are as follows.

[0061]

[0062] (Effects)

[0063] In the optical system 3A of this example, the first optical element 33, located on the magnification side, has a concave first reflecting surface 40. The second optical element 34, located on the reduction side of the first optical element 33, has a first transmitting surface 51, a second reflecting surface 52 located on the reduction side of the first transmitting surface 51, and a second transmitting surface 53 located on the reduction side of the second reflecting surface 52. The first optical axis of the first reflecting surface 40 is aligned with the second optical axis of the first transmitting surface 51. The first transmitting surface 51 and the second transmitting surface 53 have positive refractive power.

[0064] According to this example, the second optical element 34, which has a first transmission surface 51 that projects projected light toward the first optical element 33, possesses refractive power. Therefore, the diffusion and direction of light from the first transmission surface 51 toward the first reflection surface 40 can be controlled, thus shortening the air gap between the first optical element 33 and the second optical element 34. Consequently, the projected light is easily controlled in the first reflection surface 40 of the first optical element 33. Therefore, a magnified image with well-corrected aberrations can be projected onto the screen S. Furthermore, since the air gap between the first optical element 33 and the second optical element 34 can be shortened, the optical system can be reduced in size.

[0065] Furthermore, in this example, the angle θ1 formed by the optical axis M of the first optical element 33 and the optical axis N of the second optical system 32 is 90° or less. Therefore, optical elements positioned closer to the magnification side than the second optical element 34 can be arranged in a direction parallel to or away from the magnification side imaging plane. Thus, interference between optical elements positioned closer to the magnification side than the second optical element 34 and the magnification side imaging plane can be prevented. Therefore, the optical system can be positioned close to the screen S.

[0066] Furthermore, in this example, an intermediate image 30, conjugate with both the reduction-side and magnification-side conjugate surfaces, is formed between the first reflecting surface 40 of the first optical element 33 and the second transmitting surface 53 of the second optical element 34. Thus, the second optical element 34, possessing refractive power, is located near the intermediate image 30. Therefore, chromatic aberration and other aberrations in the intermediate image can be suppressed.

[0067] In this example, the second optical system 32, located on the reduced side of the second optical element 34, is a refractive optical system. The refractive optical system includes multiple lenses, each possessing a plane of rotational symmetry centered on the optical axis N. This simplifies the manufacture of the second optical system 32.

[0068] Figure 4 This is a diagram showing the MTF on the magnification side of optical system 3A. Figure 4 The horizontal axis represents spatial frequency, and the vertical axis represents contrast ratio. For example... Figure 4 As shown, the optical system 3A in this example has high resolution.

[0069] Figure 5 This is a dot plot of optical system 3A. (Example) Figure 5 As shown, in this example, the deviation of the point was suppressed.

[0070] (Example 2)

[0071] Figure 6 This is a schematic diagram showing the overall light pattern of the optical system of Embodiment 2. Figure 7 This is a ray diagram of the optical system 3B in Example 2. (As shown) Figure 6 , Figure 7 As shown, a liquid crystal panel 18 is disposed on the conjugate surface of the reduced side of the optical system 3B.

[0072] In the following explanation, for convenience, the three mutually orthogonal axes are designated as the X-axis, Y-axis, and Z-axis. Furthermore, the width direction of screen S, which serves as the conjugate surface for magnification, is designated as the X-axis, the vertical direction of screen S as the Y-axis, and the direction perpendicular to screen S as the Z-axis. Along the Y-axis, the top of screen S is designated as the Y1 direction, and the bottom of screen S as the Y2 direction. Along the Z-axis, the side of screen S located on is designated as the Z1 direction, and the opposite side as the Z2 direction.

[0073] like Figure 6 As shown, the optical system 3B in this example has a first optical system 31 and a second optical system 32 arranged sequentially from the magnification side to the reduction side. The first optical system 31 is a reflective optical system. The first optical system 31 has a first optical element 33 and a second optical element 34. The first optical element 33 and the second optical element 34 are arranged sequentially from the magnification side to the reduction side. The optical axis M of the first optical element 33 extends along the Z-axis direction. That is, the optical axis M of the first optical element 33 is perpendicular to the screen S. The second optical system 32 is a refractive optical system. The optical axis N (the sixth optical axis) of the second optical system 32 extends along the Y-axis direction. The screen S is located in the Z1 direction of the optical axis N.

[0074] like Figure 7 As shown, the first optical element 33 has a first reflecting surface 40 facing the Z1 direction. The first reflecting surface 40 has a concave shape that is recessed in the Z2 direction. The first optical axis of the first reflecting surface 40 is the optical axis M of the first optical element 33. The first reflecting surface 40 has a rotationally symmetric shape about the first optical axis. The first reflecting surface 40 has an aspherical shape. Here, the first optical element 33 is designed with the optical axis M as the design axis. That is, the first optical axis is the optical axis in the design of the first reflecting surface 40.

[0075] The second optical element 34 is composed of a single optical element. The second optical element 34 is located in the Z1 direction of the first optical element 33. The second optical element 34 has a first transmission surface 51, a second reflection surface 52 located on the narrowing side of the first transmission surface 51, and a second transmission surface 53 located on the narrowing side of the second reflection surface 52.

[0076] The first transmitting surface 51 and the first reflecting surface 40 are opposite each other in the Z-axis direction. The first transmitting surface 51 has a convex shape facing the Z2 direction. The second optical axis of the first transmitting surface 51 is approximately parallel to the first optical axis of the first reflecting surface 40. In this example, the second optical axis of the first transmitting surface 51 coincides with the first optical axis of the first reflecting surface 40. In other words, the second optical axis of the first transmitting surface 51 coincides with the optical axis M of the first optical element 33. The first transmitting surface 51 has a rotationally symmetric shape about the second optical axis. The first transmitting surface 51 has positive refractive power. The first transmitting surface 51 has an aspherical shape.

[0077] The second reflecting surface 52 is a mirror with a non-planar shape. Here, the non-planar shape includes aspherical shapes and freeform surfaces. In this example, the second reflecting surface 52 has an aspherical shape. The second reflecting surface 52 is inclined at 45° with respect to the Y-axis and Z-axis. The second reflecting surface 52 bends the light path by 90° between the first transmitting surface 51 and the second transmitting surface 53. The second reflecting surface 52 is formed by providing a reflective coating on the outer surface of the second optical element 34 in the Z1 direction.

[0078] The second transmission surface 53 faces the Y2 direction and is opposite to lens L15. The angle between the optical axis of the second transmission surface 53 and the second optical axis of the first transmission surface 51 is 90°. That is, the angle between the optical axis of the second transmission surface 53 and the optical axis M of the first optical element 33 is 90°. In addition, the optical axis of the second transmission surface 53 is aligned with the optical axis N of the second optical system 32. The second transmission surface 53 has a rotationally symmetric shape centered on the optical axis of the second transmission surface 53. The second transmission surface 53 has positive refractive power. The second transmission surface 53 has an aspherical shape.

[0079] like Figure 7As shown, the second optical system 32 includes 15 lenses L1 to L15. Lenses L1 to L15 are arranged in this order from the reduction side to the magnification side. In this example, lens L2 and lens L3 are a first joint lens L21. Lens L4 and lens L5 are a second joint lens L22. Lens L11 and lens L12 are a third joint lens L23. Lens L13 and lens L14 are a fourth joint lens L24. An aperture O is arranged between lens L9 and lens L10. Lenses L6, L9, and L15 are aspherical lenses with aspherical shapes on both sides. In the second optical system 32, each lens has a plane of rotational symmetry centered on the optical axis N.

[0080] Here, as Figure 7 As shown, the liquid crystal panel 18, disposed on the reduced-side conjugate surface of the optical system 3B, forms a projected image on the Z2 direction side of the optical axis N. Furthermore, the angle θ1 formed by the optical axis M of the first optical element 33 and the optical axis N of the second optical system 32 is 90° or less. In this example, the angle θ1 is 90°. Therefore, light from the liquid crystal panel 18 side, after passing through the second optical system 32, is bent by 90° by the second reflecting surface 52 of the second optical element 34 and directed towards the Z2 direction. The light directed towards the Z2 direction is reflected back towards the Z1 and Y1 directions by the first reflecting surface 40 of the first optical element 33 and reaches the screen S.

[0081] In addition, such as Figure 7 As shown, the optical system 3B forms an intermediate image 30 that is conjugate to both the reduction-side conjugate surface and the magnification-side conjugate surface between the reduction-side conjugate surface and the magnification-side conjugate surface. In this example, the intermediate image 30 is formed between the first reflecting surface 40 of the first optical element 33 and the second transmitting surface 53 of the second optical element 34.

[0082] The lens data for optical system 3B is as follows. Surface numbers are sequentially labeled from the reduction side to the magnification side. These labels correspond to the LCD panel, dichroic prism, lens, and screen. Surface numbers that do not correspond to the LCD panel, dichroic prism, lens, or screen are virtual data. Surfaces marked with an asterisk (*) are aspherical. R is the radius of curvature. D is the on-axis spacing. nd is the refractive index. νd is the Abbe number. Y is the aperture radius. The units for R, D, and Y are mm. Furthermore, the lens data in this example was designed using Synopsys CODE V.

[0083]

[0084] The aspherical coefficients are as follows.

[0085]

[0086]

[0087] The coordinates of the light rays on the object's surface are as follows.

[0088]

[0089] Additionally, in this example, face number 33 is an eccentric face. The parameters of the eccentric face are as follows.

[0090]

[0091] (Effects)

[0092] The optical system 3B in this example achieves the same effect as the optical system 3A in Embodiment 1. Furthermore, in this example, the second reflecting surface 52 has a non-planar shape. That is, the second reflecting surface 52 is an aspherical or freeform surface. Specifically, the second reflecting surface 52 has an aspherical shape. Therefore, it is easier to correct various aberrations in the intermediate image 30.

[0093] Figure 8 This is a diagram showing the MTF of the magnified side of optical system 3B. Figure 8 The horizontal axis represents spatial frequency, and the vertical axis represents contrast ratio. For example... Figure 8 As shown, the optical system 3B in this example has high resolution.

[0094] Figure 9 This is a dot diagram of optical system 3B. (Example) Figure 9 As shown, in this example, the deviation of the point was suppressed.

[0095] (Example 3)

[0096] Figure 10 This is a schematic diagram showing the overall light pattern of the optical system of Embodiment 3. Figure 11 This is a ray diagram of the optical system 3C in Example 3. Figure 12 This is a ray diagram of the first optical system in Example 3. (As shown) Figure 10 , Figure 11 As shown, a liquid crystal panel 18 is disposed on the conjugate surface of the reduced side of the optical system 3C.

[0097] In the following explanation, for convenience, the three mutually orthogonal axes are designated as the X-axis, Y-axis, and Z-axis. Furthermore, the width direction of screen S, which serves as the conjugate surface for magnification, is designated as the X-axis, the vertical direction of screen S as the Y-axis, and the direction perpendicular to screen S as the Z-axis. Along the Y-axis, the top of screen S is designated as the Y1 direction, and the bottom of screen S as the Y2 direction. Along the Z-axis, the side of screen S located on is designated as the Z1 direction, and the opposite side as the Z2 direction.

[0098] like Figure 10As shown, the optical system 3C in this example has a first optical system 31 and a second optical system 32 arranged sequentially from the magnification side to the reduction side. The first optical system 31 is a reflective optical system. The first optical system 31 has a first optical element 33 and a second optical element 34. The first optical element 33 and the second optical element 34 are arranged in this order from the magnification side to the reduction side. The optical axis M of the first optical element 33 extends along the Z-axis direction. That is, the optical axis M of the first optical element 33 is perpendicular to the screen S. The second optical system 32 is a refractive optical system. The optical axis N (the sixth optical axis) of the second optical system 32 extends along the Y-axis direction. The screen S is located in the Z1 direction of the optical axis N.

[0099] like Figure 11 As shown, the first optical element 33 is composed of a single optical element. The first optical element 33 is located in the Z2 direction of the second optical element 34. The first optical element 33 has a third transmission surface 41, a first reflection surface 42 located on the narrowing side of the third transmission surface 41, and a fourth transmission surface 43 located on the narrowing side of the first reflection surface 42.

[0100] The third transmission surface 41 has a convex shape facing the Y1 direction. The third optical axis of the third transmission surface 41 is aligned with the optical axis M of the first optical system 31. The third transmission surface 41 has a rotationally symmetric shape centered on the third optical axis of the third transmission surface 41. The third transmission surface 41 has positive refractive power.

[0101] The first reflecting surface 42 is located in the Y2 direction of the third transmitting surface 41. The first reflecting surface 42 has a concave shape that is recessed in the Z2 direction. The first optical axis of the first reflecting surface 42 is aligned with the optical axis M of the first optical system 31. The first reflecting surface 42 has a rotationally symmetric shape centered on the first optical axis of the first reflecting surface 42. The first reflecting surface 42 has positive refractive power. The first reflecting surface 42 has an aspherical shape. The first reflecting surface 42 is formed by providing a reflective coating on the outer surface of the first optical element 33 in the Z2 direction.

[0102] The fourth optical axis of the fourth transmission surface 43 coincides with the optical axis M of the first optical system 31. The fourth transmission surface 43 has a rotationally symmetric shape centered on the fourth optical axis of the fourth transmission surface 43. The fourth transmission surface 43 has positive refractive power. The fourth transmission surface 43 has an aspherical shape.

[0103] Here, the first optical element 33 is designed with the optical axis M as the design axis. That is, the third optical axis is the optical axis in the design of the third transmission surface 41. The first optical axis is the optical axis in the design of the first reflection surface 42. The fourth optical axis is the optical axis in the design of the fourth transmission surface 43.

[0104] The second optical element 34 is composed of a single optical element. The second optical element 34 is located in the Z1 direction of the first optical element 33. The second optical element 34 has a first transmission surface 51, a second reflection surface 52 located on the narrowing side of the first transmission surface 51, and a second transmission surface 53 located on the narrowing side of the second reflection surface 52.

[0105] The first transmission surface 51 and the fourth transmission surface 43 are opposite each other in the Z-axis direction. The first transmission surface 51 has a convex shape facing the Z2 direction. The second optical axis of the first transmission surface 51 is approximately parallel to the first optical axis of the first reflecting surface 42. In this example, the second optical axis of the first transmission surface 51 coincides with the first optical axis of the first reflecting surface 42. In other words, the second optical axis of the first transmission surface 51 coincides with the optical axis M of the first optical element 33. The first transmission surface 51 has a rotationally symmetric shape centered on the second optical axis. The first transmission surface 51 has positive refractive power. The first transmission surface 51 has an aspherical shape.

[0106] The second reflecting surface 52 is a plane mirror without refractive power. The second reflecting surface 52 is tilted at 45° with respect to the Y-axis and Z-axis. The second reflecting surface 52 bends the light path by 90° between the first transmitting surface 51 and the second transmitting surface 53. The second reflecting surface 52 is formed by providing a reflective coating on the outer surface of the second optical element 34 in the Z1 direction.

[0107] The second transmission surface 53 faces the Y2 direction and is opposite to lens L15. The angle between the optical axis of the second transmission surface 53 and the second optical axis of the first transmission surface 51 is 90°. That is, the angle between the optical axis of the second transmission surface 53 and the optical axis M of the first optical element 33 is 90°. In addition, the optical axis of the second transmission surface 53 is aligned with the optical axis N of the second optical system 32. The second transmission surface 53 has a rotationally symmetric shape centered on the optical axis of the second transmission surface 53. The second transmission surface 53 has positive refractive power. The second transmission surface 53 has an aspherical shape.

[0108] like Figure 11 As shown, the second optical system 32 includes 12 lenses L1 to L12. Lenses L1 to L12 are arranged in this order from the reducing side to the magnifying side. Lenses L2, L7, and L12 are aspherical lenses with aspherical shapes on both sides. In the first optical system 31, each lens has a plane of rotational symmetry centered on the optical axis N.

[0109] Here, as Figure 11As shown, the liquid crystal panel 18, disposed on the reduced-side conjugate surface of the optical system 3C, forms a projected image on the Z2 direction side of the optical axis N. Furthermore, the angle θ1 formed by the optical axis M of the first optical element 33 and the optical axis N of the second optical system 32 is 90° or less. In this example, the angle θ1 is 90°. Therefore, light from the liquid crystal panel 18 side, after passing through the second optical system 32, is bent by 90° by the second reflecting surface 52 of the second optical element 34 and directed towards the Z2 direction. The light directed towards the Z2 direction is reflected back towards the Z1 and Y1 directions by the first reflecting surface 42 of the first optical element 33 and reaches the screen S.

[0110] In addition, such as Figure 11 As shown, the optical system 3C forms an intermediate image 30 that is conjugate to both the reduction-side conjugate surface and the magnification-side conjugate surface between the reduction-side conjugate surface and the magnification-side conjugate surface. In this example, the intermediate image 30 is formed between the first reflecting surface 42 of the first optical element 33 and the second transmitting surface 53 of the second optical element 34.

[0111] Here, as Figure 12 As shown, the light traveling between the third transmission surface 41 and the first reflection surface 42 has a peripheral light L that tilts away from the screen S, which is the conjugate surface of the magnification side, as it approaches the third transmission surface 41. The peripheral light L tilts towards the screen S as it moves away from the third transmission surface 41 between the third transmission surface 41 and the screen S. In addition, the imaginary line Q connecting the maximum effective point P of the peripheral light L on the third transmission surface 41 to the center of curvature of the third transmission surface 41 intersects the optical axis M (the third optical axis) at an angle θ2 of 90° or more.

[0112] The lens data for the 3C optical system is as follows. Surface numbers are sequentially labeled from the reduction side to the magnification side. These labels correspond to the LCD panel, dichroic prism, lens, and screen. Surface numbers that do not correspond to those of the LCD panel, dichroic prism, lens, or screen are virtual data. Surfaces marked with an asterisk (*) are aspherical surfaces. R is the radius of curvature. D is the on-axis spacing. nd is the refractive index. νd is the Abbe number. Y is the aperture radius. The units for R, D, and Y are mm. Furthermore, the lens data in this example was designed using Synopsys CODE V.

[0113]

[0114] The aspherical coefficients are as follows.

[0115]

[0116]

[0117] The coordinates of the light rays on the object's surface are as follows.

[0118]

[0119] Additionally, in this example, faces numbered 29, 33, and 34 are eccentric faces. The parameters of the eccentric faces are as follows.

[0120]

[0121]

[0122] (Effects)

[0123] The optical system 3C in this example achieves the same effect as the optical system 3A in Embodiment 1. Furthermore, in this example, the first optical element 33 has a third transmission surface 41 located on the magnification side of the first reflecting surface 42 and a fourth transmission surface 43 located on the reduction side of the first reflecting surface 42. Therefore, light emitted from the first transmission surface 51 of the second optical element 34 passes sequentially through the fourth transmission surface 43, the first reflecting surface 42, and the third transmission surface 41 of the first optical element 33 before reaching the screen S. Thus, the projected light can be controlled before it enters the first reflecting surface 42, thereby suppressing the image plane curvature aberration of the intermediate image 30 formed on the reduction side of the first reflecting surface 42. Furthermore, since the image plane curvature aberration can be corrected in the intermediate image 30, the burden on the optical system for eliminating its curvature on the reduction side can be reduced. This allows for the overall miniaturization of the optical system.

[0124] In this example, the third transmission surface 41 has a rotationally symmetrical convex shape centered on its third optical axis. Furthermore, in the optical system 3C of this example, the light passing between the third transmission surface 41 and the first reflecting surface 42 has a peripheral light L that tilts away from the screen S, which serves as the conjugate surface for magnification, as it approaches the third transmission surface 41. Moreover, when an imaginary line Q is defined connecting the maximum effective point P of the peripheral light L on the third transmission surface 41 to the center of curvature of the third transmission surface 41, the imaginary line Q intersects the third optical axis at an angle θ2 of 90° or more. Therefore, when light incident on the first optical element 33 from the fourth transmission surface 43 on the reduction side is reflected back at the first reflecting surface 42 and directed towards the third transmission surface 41, the peripheral light L of the light is directed away from the screen S and reaches a region in the third transmission surface 41 that is not directly opposite the screen S. If this peripheral light L does not reach the screen S, a problem of peripheral darkening occurs in the magnified image projected onto the screen S. In contrast, in this example, the third transmission surface 41 has refractive power. Therefore, the peripheral light L is tilted towards the screen S as it moves away from the third transmission surface 41. That is, after being reflected back by the first reflective surface 42, the peripheral light L, moving away from the screen S within the first optical element 33, is directed towards the screen S via the third transmission surface 41. Thus, the amount of light around the periphery of the magnified image projected onto the screen S can be ensured.

[0125] In this example, the third optical axis of the third transmission surface 41 and the fourth optical axis of the fourth transmission surface are aligned with the first optical axis. This makes the manufacture of the first optical element 33 easier.

[0126] In this example, the first reflecting surface 42 and the fourth transmitting surface 43 have aspherical shapes. Therefore, it is easier to correct various aberrations.

[0127] Figure 13 This is a graph representing the MTF on the magnified side of the optical system 3C. Figure 13 The horizontal axis represents spatial frequency, and the vertical axis represents contrast ratio. For example... Figure 13 As shown, the optical system 3C in this example has high resolution.

[0128] Figure 14 This is a dot diagram of an optical system (3C). For example... Figure 14 As shown, in this example, the deviation of the point was suppressed.

[0129] (Example 4)

[0130] Figure 15 This is a schematic diagram showing the overall light pattern of the optical system of Embodiment 4. Figure 16 This is a 3D light diagram of the optical system in Example 4. Figure 17 This is a ray diagram of the first optical system in Example 4. (As shown) Figure 15 , Figure 16 As shown, a liquid crystal panel 18 is disposed on the conjugate surface of the reduced side of the optical system 3D.

[0131] In the following explanation, for convenience, the three mutually orthogonal axes are designated as the X-axis, Y-axis, and Z-axis. Furthermore, the width direction of screen S, which serves as the conjugate surface for magnification, is designated as the X-axis, the vertical direction of screen S as the Y-axis, and the direction perpendicular to screen S as the Z-axis. Along the Y-axis, the top of screen S is designated as the Y1 direction, and the bottom of screen S as the Y2 direction. Along the Z-axis, the side of screen S located on is designated as the Z1 direction, and the opposite side as the Z2 direction.

[0132] like Figure 15As shown, the optical system 3D in this example has a first optical system 31 and a second optical system 32 arranged sequentially from the magnification side to the reduction side. The first optical system 31 is a reflective optical system. The first optical system 31 includes a correction lens 35, a first optical element 33, and a second optical element 34. The correction lens 35, the first optical element 33, and the second optical element 34 are arranged in this order from the magnification side to the reduction side. The optical axis M of the first optical element 33 extends along the Z-axis direction. That is, the optical axis M of the first optical element 33 is perpendicular to the screen S. The second optical system 32 is a refractive optical system. The optical axis N (the sixth optical axis) of the second optical system 32 extends along the Y-axis direction. The screen S is located in the Z1 direction of the optical axis N.

[0133] The corrective lens 35 is located in the Y1 direction of the first optical element 33. The fifth optical axis of the corrective lens 35 is aligned with the optical axis M of the first optical system 31. The corrective lens 35 has positive refractive power. The corrective lens 35 has a first lens surface 61 facing the magnifying side and a second lens surface 62 facing the reducing side. The first lens surface 61 has a convex shape. The first lens surface 61 has an aspherical shape. The second lens surface 62 has a concave shape. The second lens surface 62 has an aspherical shape. Both the first lens surface 61 and the second lens surface 62 have a rotationally symmetric shape about the fifth optical axis of the corrective lens 35.

[0134] like Figure 16 As shown, the first optical element 33 is composed of a single optical element. The first optical element 33 is located in the Z2 direction of the second optical element 34. The first optical element 33 has a third transmission surface 41, a first reflection surface 42 located on the narrowing side of the third transmission surface 41, and a fourth transmission surface 43 located on the narrowing side of the first reflection surface 42.

[0135] The third transmission surface 41 has a convex shape facing the Y1 direction. The third optical axis of the third transmission surface 41 is aligned with the optical axis M of the first optical system 31. The third transmission surface 41 has a rotationally symmetric shape centered on the third optical axis of the third transmission surface 41. The third transmission surface 41 has positive refractive power.

[0136] The first reflecting surface 42 is located in the Y2 direction of the third transmitting surface 41. The first reflecting surface 42 has a concave shape that is recessed in the Z2 direction. The first optical axis of the first reflecting surface 42 is aligned with the optical axis M of the first optical system 31. The first reflecting surface 42 has a rotationally symmetric shape centered on the first optical axis of the first reflecting surface 42. The first reflecting surface 42 has positive refractive power. The first reflecting surface 42 has an aspherical shape. The first reflecting surface 42 is formed by providing a reflective coating on the outer surface of the first optical element 33 in the Z2 direction.

[0137] The fourth optical axis of the fourth transmission surface 43 coincides with the optical axis M of the first optical system 31. The fourth transmission surface 43 has a rotationally symmetric shape centered on the fourth optical axis of the fourth transmission surface 43. The fourth transmission surface 43 has positive refractive power. The fourth transmission surface 43 has an aspherical shape.

[0138] Here, the first optical element 33 is designed with the optical axis M as the design axis. That is, the third optical axis is the optical axis in the design of the third transmission surface 41. The first optical axis is the optical axis in the design of the first reflection surface 42. The fourth optical axis is the optical axis in the design of the fourth transmission surface 43.

[0139] The second optical element 34 is composed of a single optical element. The second optical element 34 is located in the Z1 direction of the first optical element 33. The second optical element 34 has a first transmission surface 51, a second reflection surface 52 located on the narrowing side of the first transmission surface 51, and a second transmission surface 53 located on the narrowing side of the second reflection surface 52.

[0140] The first transmission surface 51 and the fourth transmission surface 43 are opposite each other in the Z-axis direction. The first transmission surface 51 has a convex shape facing the Z2 direction. The second optical axis of the first transmission surface 51 is approximately parallel to the first optical axis of the first reflecting surface 42. In this example, the second optical axis of the first transmission surface 51 coincides with the first optical axis of the first reflecting surface 42. In other words, the second optical axis of the first transmission surface 51 coincides with the optical axis M of the first optical element 33. The first transmission surface 51 has a rotationally symmetric shape about the second optical axis. The first transmission surface 51 has positive refractive power. The first transmission surface 51 has an aspherical shape.

[0141] The second reflecting surface 52 is a plane mirror without refractive power. The second reflecting surface 52 is tilted at 45° with respect to the Y-axis and Z-axis. The second reflecting surface 52 bends the light path by 90° between the first transmitting surface 51 and the second transmitting surface 53. The second reflecting surface 52 is formed by providing a reflective coating on the outer surface of the second optical element 34 in the Z1 direction.

[0142] The second transmission surface 53 faces the Y2 direction and is opposite to the lens L12. The angle between the optical axis of the second transmission surface 53 and the second optical axis of the first transmission surface 51 is 90°. That is, the angle between the optical axis of the second transmission surface 53 and the optical axis M of the first optical element 33 is 90°. In addition, the optical axis of the second transmission surface 53 is aligned with the optical axis N of the second optical system 32. The second transmission surface 53 has a rotationally symmetric shape about its optical axis. The second transmission surface 53 has positive refractive power. The second transmission surface 53 has an aspherical shape.

[0143] like Figure 16As shown, the second optical system 32 includes 12 lenses L1 to L12. Lenses L1 to L12 are arranged in this order from the reducing side to the magnifying side. Lenses L2, L7, and L12 are aspherical lenses with aspherical shapes on both sides. In the first optical system 31, each lens has a plane of rotational symmetry centered on the optical axis N.

[0144] Here, as Figure 16 As shown, the liquid crystal panel 18, disposed on the reduced-side conjugate surface of the optical system 3D, forms a projected image on the Z2 direction side of the optical axis N. Furthermore, the angle θ1 formed by the optical axis M of the first optical element 33 and the optical axis N of the second optical system 32 is 90° or less. In this example, the angle θ1 is 90°. Therefore, light from the liquid crystal panel 18 side, after passing through the second optical system 32, is bent by 90° by the second reflecting surface 52 of the second optical element 34 and directed towards the Z2 direction. The light directed towards the Z2 direction is reflected back towards the Z1 and Y1 directions by the first reflecting surface 42 of the first optical element 33 and reaches the screen S.

[0145] In addition, such as Figure 16 As shown, the optical system 3D forms an intermediate image 30 conjugate to both the reduction-side and magnification-side conjugate surfaces between the reduction-side and magnification-side conjugate surfaces. In this example, the intermediate image 30 is formed between the first reflecting surface 42 of the first optical element 33 and the second transmitting surface 53 of the second optical element 34.

[0146] Here, as Figure 17 As shown, the light traveling between the third transmission surface 41 and the first reflection surface 42 has a peripheral light L that tilts away from the screen S, which serves as the conjugate surface for magnification, as it approaches the third transmission surface 41. The peripheral light L tilts away from the screen S as it moves away from the third transmission surface 41 between the third transmission surface 41 and the correction lens 35. Conversely, the peripheral light L tilts towards the screen S as it moves away from the correction lens 35 between the correction lens 35 and the screen S. Furthermore, an imaginary line Q connecting the maximum effective point P of the peripheral light L on the third transmission surface 41 to the center of curvature of the third transmission surface 41 intersects the optical axis M (the third optical axis) at an angle θ2 of 90° or more.

[0147] The lens data for the 3D optical system is as follows. Surface numbers are sequentially labeled from the reduced side to the magnified side. These labels correspond to the LCD panel, dichroic prism, lens, and screen. Surface numbers that do not correspond to those of the LCD panel, dichroic prism, lens, or screen are virtual data. Surfaces marked with an asterisk (*) are aspherical. R is the radius of curvature. D is the on-axis spacing. nd is the refractive index. νd is the Abbe number. Y is the aperture radius. The units for R, D, and Y are mm. Furthermore, the lens data in this example was designed using Synopsys CODE V.

[0148]

[0149] The aspherical coefficients are as follows.

[0150]

[0151] The coordinates of the light rays on the object's surface are as follows.

[0152]

[0153] Additionally, in this example, faces numbered 29, 33, 34, and 36 are eccentric faces. The parameters of the eccentric faces are as follows.

[0154]

[0155]

[0156] (Effects)

[0157] The optical system 3D in this example achieves the same effect as the optical system 3C in Embodiment 3. Furthermore, the optical system 3D in this example includes a correction lens 35 disposed on the magnification side of the first optical element 33, thus enabling control of the projected light at a position close to the screen S. Therefore, through the third transmission surface 41 and the correction lens 35, the peripheral light L can be tilted towards the screen S as it moves away from the correction lens 35. That is, the refractive power of the lens, which refracts the peripheral light L towards the screen S, can be generated in both the third transmission surface 41 and the correction lens 35. Therefore, compared to Embodiment 3, the refractive power of the lens in the third transmission surface 41 can be reduced, making it easier to manufacture the first optical element 33. In addition, since the refractive power of the lens in the third transmission surface 41 can be reduced, it is easier to correct various aberrations in the magnified image.

[0158] Furthermore, in this example, the fifth optical axis of the corrective lens 35 coincides with the first optical axis of the first reflecting surface 42. That is, the fifth optical axis of the corrective lens 35 coincides with the optical axis M of the first optical element 33. Therefore, the first optical element 33 and the corrective lens 35 can be configured with high precision.

[0159] Figure 18 This is a graph representing the MTF of the magnified side of the 3D optical system. Figure 18 The horizontal axis represents spatial frequency, and the vertical axis represents contrast ratio. For example... Figure 18 As shown, the optical system in this example has high resolution in 3D.

[0160] Figure 19 This is a 3D point map of the optical system. For example... Figure 19 As shown, in this example, the deviation of the point was suppressed.

[0161] (Other implementation methods)

[0162] Furthermore, the optical system 3 in this example can be used as a camera lens. In this case, the camera element is positioned on the reduced-size imaging surface of the optical system 3.

Claims

1. An optical system, characterized in that, The optical system has: The first optical element; and The second optical element is disposed on the reduced side of the first optical element. The first optical element has a concave first reflecting surface. The second optical element has: a first transmissive surface; a second reflective surface disposed on the reduced-size side of the first transmissive surface; and a second transmissive surface disposed on the reduced-size side of the second reflective surface. The first optical axis of the first reflecting surface is parallel to the second optical axis of the first transmitting surface. At least one of the first transmissive surface, the second reflective surface, and the second transmissive surface has refractive power. The first optical element has: a third transmission surface disposed on the magnification side of the first reflection surface; and a fourth transmission surface disposed on the reduction side of the first reflection surface. The fourth transmission surface is opposite to the first transmission surface. The third optical axis of the third transmission surface and the fourth optical axis of the fourth transmission surface are aligned with the first optical axis. The third transmission surface has a convex shape that is rotationally symmetric about the third optical axis. The light passing between the third transmitting surface and the first reflecting surface has peripheral light that tilts away from the magnifying conjugate surface as it approaches the third transmitting surface. An imaginary line connecting the maximum effective point of the peripheral light in the third transmission surface and the center of curvature of the third transmission surface intersects the third optical axis at an angle of more than 90°.

2. The optical system according to claim 1, characterized in that, An intermediate image conjugate to the shrinking side conjugate surface and the magnifying side conjugate surface is formed between the first reflecting surface and the second transmitting surface.

3. The optical system according to claim 1, characterized in that, The optical system also includes a correction lens, which is disposed on the magnification side of the first optical element.

4. The optical system according to claim 3, characterized in that, The fifth optical axis of the correction lens is aligned with the first optical axis.

5. The optical system according to any one of claims 1 to 4, characterized in that, The second reflective surface has a non-planar shape.

6. The optical system according to any one of claims 1 to 4, characterized in that, The optical system also includes a refractive optical system disposed on the reduced side of the second optical element.

7. The optical system according to claim 6, characterized in that, The refractive optical system has multiple lenses. The plurality of lenses have a rotationally symmetric shape centered on the sixth optical axis of the refractive optical system.

8. The optical system according to claim 7, characterized in that, The angle between the first optical axis and the sixth optical axis is less than 90°.

9. A projector, characterized in that, The projector has: An optical modulation element, which is disposed on the conjugate surface of the reduced side, modulates the light emitted from the light source; as well as The optical system according to any one of claims 1 to 8 projects light modulated by the light modulation element.

Images