Optical devices, projectors, and imaging devices

Abstract

To make optical devices more compact. [Solution] The optical device 50 comprises a first reflective surface 4a having power, a second reflective surface 4b having power and positioned on the enlarged side of the first reflective surface 4a, a first optical element 42a positioned on the enlarged side of the second reflective surface 4b and arranged sequentially from the shrinking side toward the enlargement side, having a first transmissive surface 5a, a third reflective surface 4c having a concave shape in the direction of the incident light ray, and a second transmissive surface 5b different from the first transmissive surface 5a, a third optical element 42c having a fourth reflective surface 4d positioned on the enlarged side of the second reflective surface 4b, and a fifth reflective surface 4e positioned between the fourth reflective surface 4d and the first transmissive surface 5a, wherein the third reflective surface 4c has positive power, and the fourth reflective surface 4d is positioned on the shrinking side conjugate surface RC side than the first reflective surface 4a and the third reflective surface 4c.

Description

[Technical Field]

[0001] The present invention relates to an optical device, and to a projector and imaging device equipped with an optical device. [Background technology]

[0002] An imaging optical system having one prism before and one after the aperture is known (Patent Document 1). In the imaging optical system of Patent Document 1, at least one reflective surface of the prism has power, and at least one optical working surface of the prism has both transmission and reflection properties. This imaging optical system is miniaturized by utilizing refraction and internal reflection in the prism. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-271618 [Overview of the project] [Problems that the invention aims to solve]

[0004] The above-described imaging optical system has transmission and reflection functions at the same interface of the prism, which results in strict angular constraints to ensure total internal reflection, making it difficult to achieve high optical performance such as resolution, and also making it difficult to shorten the focal length. [Means for solving the problem]

[0005] An optical device in one aspect of the present invention comprises a first reflective surface having power, a second reflective surface having power positioned on the enlarged side of the first reflective surface, a first optical element positioned on the enlarged side of the second reflective surface and arranged sequentially from the reduction side toward the enlargement side, having a first transmissive surface, a third reflective surface having a concave shape in the direction of the incident light ray, and a second transmissive surface different from the first transmissive surface, a third optical element having a fourth reflective surface positioned on the enlarged side of the second reflective surface, and a fifth reflective surface positioned between the fourth reflective surface and the first transmissive surface, wherein the third reflective surface has positive power, and the fourth reflective surface is positioned on the reduction side conjugate surface side of the first and third reflective surfaces.

[0006] In one aspect of the present invention, the projector comprises the optical device described above and an image forming unit that forms an image on the reduced-side conjugate surface of the optical device.

[0007] An imaging device in one aspect of the present invention comprises the optical device described above and an image sensor disposed on the conjugate surface of the optical device on the reduction side. [Brief explanation of the drawing]

[0008] [Figure 1] This diagram illustrates the structure of a projector incorporating the optical device of the first embodiment. [Figure 2] This diagram shows the projection state of the optical device onto the screen. [Figure 3] This is a cross-sectional view illustrating the optical device or projection optical system of Example 1. [Figure 4] The lateral aberration characteristics of the projection optical system of Example 1 are shown. [Figure 5] The lateral aberration characteristics of the projection optical system of Example 1 are shown. [Figure 6] This diagram illustrates the relationship between the display surface and the projection surface in Example 1. [Figure 7] This is a cross-sectional view illustrating an optical device or projection optical system of a second embodiment. [Figure 8] The lateral aberration characteristics of the projection optical system of Example 2 are shown. [Figure 9] The lateral aberration characteristics of the projection optical system of Example 2 are shown. [Figure 10] It is a diagram for explaining the relationship between the display surface and the projection surface in Example 2. [Figure 11] It is a cross-sectional view for explaining the optical device or the projection optical system in Example 3. [Figure 12] It is a diagram for explaining the structure of an imaging device incorporating the optical device of the third embodiment.

Embodiments for Carrying Out the Invention

[0009] 〔First Embodiment〕 Hereinafter, with reference to the drawings, an optical device according to the first embodiment of the present invention and a projector incorporating the same will be described.

[0010] FIG. 1 is a diagram for explaining the structure of a projector 2 incorporating an optical device 50 according to the first embodiment. As shown in FIG. 1, the projector 2 includes an optical system portion 60 that projects image light or video light, and a circuit device 80 that controls the operation of the optical system portion 60. The optical system portion 60 has an image display device 20 that displays image light, and a projection optical system 40 that projects the image light onto a screen SC (see FIG. 2).

[0011] The image display device 20 has a light source device 10, a separation optical system 20a, an image forming section 20b, and a prism PR. In the present embodiment, the optical device 50 is a projection optical device 51, which is a combination of the prism PR and the projection optical system 40.

[0012] The light source device 10 emits light including R light, G light, and B light in a homogenized state. The light source device 10 includes, for example, a light source lamp such as an ultra-high pressure mercury lamp, a two-stage integrator lens having a plurality of lens elements arranged in an array, a polarization conversion element that converts the light passing through the two-stage integrator lens into a predetermined linear polarization, and a superimposing lens that superimposes the illumination light emitted from the rear-stage integrator lens on the display regions of liquid crystal panels 29R, 29G, and 29B.

[0013] The separation optical system 20a separates the light emitted from the light source device 10 into three colors of R, G, and B. The separation optical system 20a includes a first dichroic mirror 21, a second dichroic mirror 22, relay lenses 23 and 24, reflection mirrors 25, 26, and 27, and field lenses 28R, 28G, and 28B. The image forming unit 20b includes liquid crystal panels 29R, 29G, and 29B which are light modulation elements OM.

[0014] The first dichroic mirror 21 reflects the R light incident from the light source device 10 and transmits the G light and the B light. The R light reflected by the first dichroic mirror 21 is incident on the liquid crystal panel 29R through the reflection mirror 25 and the field lens 28R. The liquid crystal panel 29R forms an R-color image by modulating the R light according to the image signal.

[0015] The second dichroic mirror 22 reflects the G light from the first dichroic mirror 21 and transmits the B light. The G light reflected by the second dichroic mirror 22 is incident on the liquid crystal panel 29G through the field lens 28G. The liquid crystal panel 29G forms a G-color image by modulating the G light according to the image signal. The B light transmitted through the second dichroic mirror 22 is incident on the liquid crystal panel 29B through the relay lenses 23 and 24, the reflection mirrors 26 and 27, and the field lens 28B. The liquid crystal panel 29B forms a B-color image by modulating the B light according to the image signal.

[0016] The liquid crystal panels 29R, 29G, and 29B which are the image forming unit 20b form an image on their surfaces, that is, on the reduced-side conjugate plane RC (see FIG. 3) of the projection optical system 40.

[0017] The prism PR is, for example, a cross-dichroic prism 31. The cross-dichroic prism 31 is a prism for light synthesis, which synthesizes the light modulated by each of the liquid crystal panels 29R, 29G, and 29B into image light and causes it to proceed to the projection optical system 40.

[0018] The projection optical system 40 is a projection lens that projects the image light, which is modulated by each liquid crystal panel 29R, 29G, and 29B and combined by the cross dichroic prism 31, onto the screen SC (see Figure 2).

[0019] The circuit device 80 includes an image processing unit 81 to which an external image signal IS such as a video signal is input, a display drive unit 82 that drives liquid crystal panels 29R, 29G, and 29B provided in the optical system section 60 based on the output of the image processing unit 81, a lens drive unit 83 that adjusts the state of the projection optical system 40 by operating a moving mechanism AN provided in the projection optical system 40, and a main control unit 88 that comprehensively controls the operation of these circuit sections 81, 82, 83, etc.

[0020] The image processing unit 81 converts the input external image signal IS into an image signal that includes the gradation of each color. The image processing unit 81 can also perform various image processing operations on the external image signal IS, such as distortion correction and color correction.

[0021] The display drive unit 82 can operate the liquid crystal panels 29R, 29G, and 29B based on the image signal output from the image processing unit 81, and can form an image on the liquid crystal panels 29R, 29G, and 29B that corresponds to the image signal or an image that has been processed therefrom.

[0022] The lens drive unit 83 operates under the control of the main control unit 88 and adjusts the focus of the projection optical system 40 by appropriately moving the lens 41 constituting the projection optical system 40 or optical device 50 along the optical axis OA of the device using the moving mechanism AN. Here, the optical axis OA of the device is the axis passing through the center of the lens 41 in the optical device 50, or the central axis OX passing through the center of the conjugate plane RC on the reduction side (see Figure 3). The moving mechanism AN includes, for example, an actuator.

[0023] The lens drive unit 83 can be omitted. In this case, the lens 41 may be manually moved using a mechanical mechanism including a cam mechanism as the moving mechanism AN, and the focus of the projection optical system 40 may be adjusted.

[0024] The optical device 50 will be described in detail below with reference to Figures 2 and 3. Figure 2 shows the projection state of the optical device 50 onto the screen SC. Figure 3 is a diagram illustrating the configuration and ray diagram of the optical device 50. Note that the optical device 50 exemplified in Figure 3 has the same configuration as the optical device 50 of Embodiment 1 described later.

[0025] As shown in Figure 2, the optical device 50 comprises a prism PR and a projection optical system 40. The optical device 50 projects the image formed on the display surface 2a or projection surface of the image forming unit 20b onto the projection surface 2b of the screen SC. In other words, the image light ML emitted from the display surface 2a of the image forming unit 20b enters the projection surface 2b of the screen SC via the prism PR and the projection optical system 40. Here, a prism PR corresponding to the cross dichroic prism 31 in Figure 1 is positioned between the projection optical system 40 and the image forming unit 20b.

[0026] As shown in Figure 3, the projection optical system 40 of the optical device 50 comprises a lens 41, an internal reflecting element 42, and a mirror element 43. The projection optical system 40 is an eccentric or off-axis optical system, and the optical axis OA of the device, which extends along the optical path through the center of the image forming unit 20b, is arranged along a plane of symmetry parallel to the YZ plane. In other words, the projection optical system 40 is asymmetric with respect to the vertical Y direction and symmetric with respect to the YZ plane. The projection optical system 40 of the optical device 50 comprises, as a general set of components, a first reflecting surface 4a having power, a second reflecting surface 4b having power and positioned on the enlargement side of the first reflecting surface 4a, and a first optical element 42a positioned on the enlargement side of the second reflecting surface 4b and arranged sequentially from the reduction side to the enlargement side, having a first transmitting surface 5a, a third reflecting surface 4c having a concave shape in the direction of the incident light ray, and a second transmitting surface 5b different from the first transmitting surface 5a. Furthermore, the projection optical system 40 includes a third optical element 42c having a fourth reflective surface 4d positioned on the expanding side of the second reflective surface 4b in the optical path between the second reflective surface 4b and the first optical element 42a, and a fifth reflective surface 4e positioned between the fourth reflective surface 4d and the first transmissive surface 5a. Here, the third reflective surface 4c has positive power, and the fourth reflective surface 4d is spatially positioned on the contracting side conjugate surface RC side of the first reflective surface 4a and the third reflective surface 4c. As will be described in detail later, the first optical element 42a and the third optical element 42c are included in the internal reflective element 42.

[0027] Lens 41 is a positive lens positioned between the retraction-side conjugate surface RC and the first reflective surface 4a of the optical device 50 or projection optical system 40. This allows the retraction side of the optical device 50 to be made telecentric. It also suppresses the spread of the light beam, allowing the entire optical system of the optical device 50 to be miniaturized. Note that telecentricity includes the case where the principal ray is approximately parallel to the optical axis OA of the device. Lens 41 can be moved along the lens optical axis OA2 or the central axis OX of the retraction-side conjugate surface RC by the movement mechanism AN. This enables a focusing function in the optical device 50.

[0028] The internal reflective element 42 has a first optical element 42a, a second optical element 42b, and a third optical element 42c. The first optical element 42a, the second optical element 42b, and the third optical element 42c are an integrated internal reflective element 42. The internal reflective element 42 is an internal reflective type refractive optical element that has both internal reflection and refraction functions in a single element. Since the first to third optical elements 42a to 42c are an integrated component, that is, composed of the same element, cost reduction and improved assembly accuracy can be achieved. As will be described in detail later, the internal reflective element 42 has one or more reflective surfaces that are internal reflective surfaces W1. The internal reflective element 42 is formed from a light-transmitting material. Examples of light-transmitting materials include resin and glass. The light-transmitting material is formed, for example, by molding.

[0029] The first optical element 42a is positioned on the magnifying or upper side of the internal reflective element 42. The first optical element 42a has a first transmissive surface 5a, a third reflective surface 4c having a concave shape in the direction of the incident light ray, and a second transmissive surface 5b different from the first transmissive surface 5a, arranged sequentially from the reduction side to the magnification side. In other words, in the first optical element 42a, and by extension the internal reflective element 42, the final reflective surface on the magnification side has a concave shape. The third reflective surface 4c is an internal reflective surface W1 that reflects or reflects light from the back surface inside the first optical element 42a. Because the first optical element 42a has a first transmissive surface 5a and a second transmissive surface 5b, the transmissive surface through which the incident light passes (incident surface) and the transmissive surface through which the emitted light passes (exit surface) are located in different regions of the first optical element 42a. This makes it possible to improve optical performance by giving separate functions to the first transmission surface 5a, which is the incident surface of the first optical element 42a, and the second transmission surface 5b, which is the exit surface.

[0030] A boundary, not shown, is provided between the first transmissive surface 5a and the second transmissive surface 5b, specifically a linear or strip-shaped boundary in which the curvature, etc., changes discontinuously. This boundary may be provided with a light-absorbing member to suppress the leakage of incident or reflected light to the first optical element 42a into an optical path outside the specified path and back into the specified optical path from another location.

[0031] At least one of the first transmitting surface 5a, the third reflecting surface 4c, and the second transmitting surface 5b has power. In this embodiment, the first transmitting surface 5a, the third reflecting surface 4c, and the second transmitting surface 5b have positive power. This makes it possible to utilize the refractive power of the first transmitting surface 5a and the second transmitting surface 5b that are close to the third reflecting surface 4c, which facilitates ray control and is advantageous for miniaturizing and improving the performance of the optical device 50. The positive or negative sign of the power of the first transmitting surface 5a, the third reflecting surface 4c, and the second transmitting surface 5b can be changed as appropriate, but it is preferable that the third reflecting surface 4c and the second transmitting surface 5b have positive power.

[0032] In the optical device 50, an intermediate image is formed between the first transmission surface 5a and the third reflection surface 4c. In other words, the intermediate image is formed within the first optical element 42a. As a result, the intermediate image is formed in the optical path on the reduced side of the third reflection surface 4c, and by re-imaging the intermediate image with the concave third reflection surface 4c, it becomes possible to shorten the focal length.

[0033] The second optical element 42b is positioned on the reduced side or below the internal reflective element 42. The second optical element 42b has a first reflective surface 4a and a third transmissive surface 5c. The third transmissive surface 5c transmits both incident light incident on the first reflective surface 4a and reflected light reflected by the first reflective surface 4a. By having the incident and exit rays to the second optical element 42b pass through the third transmissive surface 5c, which is the same refractive surface W3, ray control that is not possible with surface reflection becomes possible, and optical performance can be improved in a space-saving manner.

[0034] A first aperture diaphragm ST1 is positioned on the first reflective surface 4a. The first aperture diaphragm ST1 is attached to the first reflective surface 4a and is formed outside the effective light-passing region of the first reflective surface 4a so as to surround the effective light-passing region of the first reflective surface 4a. The first aperture diaphragm ST1 absorbs light that passes outside the effective light-passing region of the first reflective surface 4a. In particular, when the optical device 50 is used as a projection optical device 51, the light emitted from the liquid crystal panel 29G or the like, which is a display device, is restricted by the first aperture diaphragm ST1 in the initial stages of the optical system, thereby preventing unnecessary diffuse reflection from occurring within the optical system of the optical device 50.

[0035] A second aperture diaphragm ST2 is positioned on the third transmissive surface 5c. The second aperture diaphragm ST2 is attached to the third transmissive surface 5c and is formed outside the effective light-passage region of the third transmissive surface 5c so as to surround the effective light-passage region of the third transmissive surface 5c. The second aperture diaphragm ST2 absorbs light that passes outside the effective light-passage region of the third transmissive surface 5c. By providing the second aperture diaphragm ST2, that is, by providing an aperture function on the incident side of the internally reflective second optical element 42b having the first reflective surface 4a, light ray control at this aperture position, i.e., a position close to the light source, becomes easier, which is advantageous for improving optical performance.

[0036] The third optical element 42c is positioned in the internal reflective element 42 between the first optical element 42a and the second optical element 42b. The third optical element 42c has a fourth reflective surface 4d positioned on the enlarged side of the second reflective surface 4b of the mirror element 43, which will be described later.

[0037] In the third optical element 42c, a second light-absorbing member AB2 is positioned on the back surface 6a, which is the surface opposite to the fourth reflective surface 4d, between the first reflective surface 4a and the third reflective surface 4c in the vertical direction (Y direction). This allows for the shielding of unwanted light that causes stray light, such as light reflected near the back surface 6a of the first reflective surface 4a and the third reflective surface 4c, or light incident on the back surface 6a near the first reflective surface 4a and the third reflective surface 4c and transmitted or reflected there. Examples of materials for the second light-absorbing member AB2 include light-absorbing paints or other substances, and light-shielding films. Note that the fourth reflective surface 4d, which is the surface reflective surface W2, also shields from unwanted light reflected by the back surface 6a, so the second light-absorbing member AB2 can be omitted.

[0038] Furthermore, in the third optical element 42c, a third light-absorbing member AB3 for preventing stray light may be provided around the fourth reflective surface 4d.

[0039] The mirror element 43 is spatially positioned in the -Z direction relative to the internal reflective element 42, that is, on the contraction-side conjugate plane RC side. The mirror element 43 has a second reflective surface 4b and a fifth reflective surface 4e. The second and fifth reflective surfaces 4b and 4e are surface reflective surfaces W4 that reflect incident light off the surface of the mirror element 43. The second and fifth reflective surfaces 4b and 4e face the internal reflective element 42 at a position closer to the center, avoiding the upper and lower ends of the internal reflective element 42. In other words, the second and fifth reflective surfaces 4b and 4e are spatially positioned on the contraction-side conjugate plane RC side relative to the third reflective surface 4c. The second reflective surface 4b is spatially positioned on the lower side of the optical device 50, that is, on the contraction side. Furthermore, the second reflective surface 4b is positioned between the third transmission surface 5c and the fourth reflective surface 4d in the optical path. The fifth reflective surface 4e is spatially positioned on the upper side of the optical device 50, that is, on the expansion side. Furthermore, the fifth reflective surface 4e is positioned between the fourth reflective surface 4d and the first transmissive surface 5a in the optical path. The mirror element 43 is integrally formed such that the fifth and second reflective surfaces 4e and 4b are arranged vertically. This makes it possible to miniaturize and reduce the cost of the optical system of the optical device 50. The substrate of the mirror element 43 is made of, for example, resin, metal, etc.

[0040] A stepped boundary is provided between the second reflective surface 4b and the fifth reflective surface 4e.

[0041] Focusing on the optical surfaces of the internal reflective element 42 and the mirror element 43, the optical device 50 has, in the optical path, a third transmitting surface 5c, a first reflecting surface 4a, a third transmitting surface 5c, a second reflecting surface 4b, a fourth reflecting surface 4d, a fifth reflecting surface 4e, a first transmitting surface 5a, a third reflecting surface 4c, and a second transmitting surface 5b, in the order from the reduction side to the expansion side. In the optical device 50, the image light ML is reflected five times. By providing the optical device 50 with a plurality of reflecting surfaces 4a to 4e in a direction that projects magnified with respect to the central axis OX of the reduction-side conjugate surface RC, which is the reduction-side imaging surface, the reflection angle can be minimized and a decrease in optical performance can be suppressed.

[0042] Furthermore, when focusing on the optical surfaces of the internal reflective element 42 in a cross-sectional view, the third transmissive surface 5c, the fourth reflective surface 4d, the first transmissive surface 5a, and the second transmissive surface 5b are arranged on the side of the second reflective surface 4b. Also, the second light absorbing member AB2 and the third reflective surface 4c are arranged on the side of the first reflective surface 4a. In this way, in the projection optical system 40 of the embodiment, the internal reflective surface W1, the surface reflective surface W2, and the refractive surface W3 can be arranged three-dimensionally on the internal reflective element 42 while maintaining their functions. Specifically, they can be arranged side by side in the vertical Y direction and placed close together, while being appropriately spaced apart in the front-to-back Z direction, which is advantageous for miniaturization. Specifically, the internal reflective surface W1 corresponds to the first and third reflective surfaces 4a and 4c. The surface reflective surface W2 corresponds to the fourth reflective surface 4d. The refractive surface W3 corresponds to the first to third transmissive surfaces 5a to 5c.

[0043] In the internal reflective element 42, the internal reflective surface W1 and the surface reflective surface W2 may have a thin metal film such as aluminum or silver formed on their surface, or a dielectric multilayer film formed on their surface. The refractive surface W3 has an anti-reflective film formed on its surface. On the contraction side conjugate surface RC of the internal reflective element 42, the surface reflective surface W2 and the refractive surface W3 are provided on a continuous surface, and the reflective film constituting the surface reflective surface W2 and the anti-reflective film constituting the refractive surface W3 are formed in corresponding regions.

[0044] In the mirror element 43, the surface reflective surface W4 may be a reflective surface with a thin metal film such as aluminum or silver formed on its surface, or a reflective surface with a dielectric multilayer film formed on its surface.

[0045] The optical path of the optical device 50 will be described below. Image light from the image forming unit 20b passes through the prism PR and lens 41 and enters the third transmission surface 5c of the internal reflection element 42. The light that has passed through the third transmission surface 5c is refracted as appropriate and internally reflected by the first reflection surface 4a. The light reflected by the first reflection surface 4a passes through the third transmission surface 5c again. The light emitted from the third transmission surface 5c and refracted as appropriate is reflected by the second reflection surface 4b of the mirror element 43. The light reflected by the second reflection surface 4b is surface-reflected by the fourth reflection surface 4d of the internal reflection element 42 and reflected by the fifth reflection surface 4e of the mirror element 43. The light reflected by the fifth reflection surface 4e enters the first transmission surface 5a of the internal reflection element 42. The light that has passed through the first transmission surface 5a is refracted as appropriate and internally reflected by the third reflection surface 4c. Light reflected by the third reflective surface 4c passes through the second transmissive surface 5b, which is different from the first transmissive surface 5a. The light emitted from the second transmissive surface 5b and refracted as appropriate is projected onto the screen SC (see Figure 2).

[0046] The optical device 50 described above comprises a first reflective surface 4a having power, a second reflective surface 4b having power and positioned on the enlarged side of the first reflective surface 4a, a first optical element 42a positioned on the enlarged side of the second reflective surface 4b and arranged sequentially from the reduction side toward the enlargement side, having a first transmissive surface 5a, a third reflective surface 4c having a concave shape in the direction of the incident light ray, and a second transmissive surface 5b different from the first transmissive surface 5a, a third optical element 42c having a fourth reflective surface 4d positioned on the enlarged side of the second reflective surface 4b, and a fifth reflective surface 4e positioned between the fourth reflective surface 4d and the first transmissive surface 5a, wherein the third reflective surface 4c has positive power, and the fourth reflective surface 4d is positioned on the reduction side conjugate surface RC side than the first reflective surface 4a and the third reflective surface 4c.

[0047] In the optical device 50 described above, by utilizing the refractive power of the first and second transmission surfaces 5a and 5b, which are close to the third reflection surface 4c, which is the inner reflection surface W1 of the first optical element 42a, ray control becomes easier, which is advantageous for miniaturization and high performance. Furthermore, the first and second transmission surfaces 5a and 5b can be given different functions to the incident and exit surfaces of the first optical element 42a, thereby improving optical performance. In addition, by making the third reflection surface 4c an inner reflection surface W1, the third reflection surface 4c can be made smaller, and the entire optical system can be miniaturized. Furthermore, by providing multiple reflection surfaces in a direction that magnifies and projects with respect to the central axis OX of the conjugate surface RC on the reduction side, the reflection angle can be minimized, and a decrease in optical performance can be suppressed. As a result of the above, the optical device 50 can be made shorter in focal length and miniaturized.

[0048] In optical systems that utilize multiple reflective surfaces, the effective size of the reflective surfaces can be reduced by creating a difference in the front-to-back position of adjacent reflective surfaces relative to the incident and reflected directions of light rays, thereby reducing the overall size of the optical system. Furthermore, the extensive use of reflective surfaces allows for greater flexibility in the layout of the optical system, enabling the realization of optical systems that cannot be constructed using only refractive optical systems.

[0049] Conventionally, when a projection optical system is composed solely of refractive elements, the number of lenses increases to correct for the spherical shape of the lenses and chromatic aberration, resulting in a linear projection lens with a long overall length. In contrast, the optical device 50 of the present invention can realize a three-dimensional optical system by utilizing multiple reflective surfaces and multiple refractive surfaces. Furthermore, since the internal reflective element 42 utilizes a molded reflective surface, it is not limited to a spherical shape, and by effectively utilizing the correction function of aspherical or free-form shapes on each surface, a projection system can be realized with a small number of surfaces and parts. As a result, the overall length of the optical system (i.e., the dimension in the Z direction) can be shortened, and a configuration in which the image is folded back towards the image forming unit 20b can be realized. In particular, when the focal length is shortened, the main body of the device can be placed near the screen SC, realizing a user-friendly projection configuration.

[0050] Furthermore, if the projection optical system is constructed using only surface reflective elements, as in conventional methods, the projection optical system becomes a large optical system with a large number of reflective surfaces. In contrast, the optical device 50 of the present invention uses an internal reflective element 42, which is an internal reflective type refractive optical element, and by utilizing the refractive effect at the transmission interface, the number of reflective surfaces can be reduced, thereby realizing a compact optical system.

[0051] Specifically, by making the final reflective surface on the magnification side, specifically the third reflective surface 4c, a concave shape, the intermediate image formed in front of the third reflective surface 4c can be magnified and projected, thereby achieving wide-angle projection. Furthermore, by providing the first aperture diaphragm ST1 on the first reflective surface, specifically the first reflective surface 4a, from the image forming unit 20b, unwanted light can be blocked at an early stage, enabling the realization of a compact optical system. By providing the first reflective surface 4a with the first aperture diaphragm ST1 on the internal reflective element 42, it becomes possible to control the light rays near the diaphragm position corresponding to the aperture position of the target optical element, thereby realizing a relatively bright optical system.

[0052] Furthermore, the optical device 50 can be made into a single component by arranging the optical elements or optical surfaces together in the vertical direction and connecting each element. Since the shapes of multiple surfaces can be manufactured at once by integral molding of the optical elements, it is possible to realize an optical system that reduces the number of parts while ensuring assembly accuracy.

[0053] As described above, the optical device 50 is a compact device that is bright, produces high image quality, and has a wide angle of view.

[0054] The projector 2 described above comprises the optical device 50 and an image forming unit 20b that forms an image on the reduction-side conjugate surface RC of the optical device 50. This makes it possible to miniaturize the projector 2 equipped with the optical device 50.

[0055] [Examples] The following describes an embodiment of the optical device 50.

[0056] In the following examples, such as Example 1, a common feature is that the displacement z of the surface on an aspherical surface is determined by the following polynomial (aspherical equation). TIFF2026109168000002.tif16166 However, c: Curvature (1 / R) h: Height from the optical axis k: Conic coefficient Ai: i-th order aspherical coefficients

[0057] The displacement z of a surface in an XY polynomial surface is determined by the following polynomial. TIFF2026109168000003.tif16166 However, c: Curvature (1 / R) k: Conic coefficient C mn :monomial x m y n coefficient r: Radial distance (r = √(x 2 +y 2 ))

[0058] (Example 1) Table 1 shows the optical surface data for Example 1. The terms used in Table 1 and the following tables are defined below. Surface number 1 refers to the reducing conjugate surface RC, and the last surface number refers to the expanding conjugate surface MC. "TC" means to refer to the eccentricity setting table. Data for surface numbers that do not correspond to the optical elements shown in Figure 3 are dummy data. SuNo: Face Number SuTy: Surface type Mt:Material SuFu: Surface function (refractory or reflective) SP: Spherical NP: Aspherical XY-FS:XY polynomial surface INF:Infinity OM1:SBSL7_OHARA OM2: Refractive index; 1.516745, Abbe number; 67.43 OM3:Z-330R DK: Refractive surface RH: Reflective surface R: paraxial curvature radius (unit: mm) D: Spacing on the shaft (unit: mm) Ar: Opening radius (unit: mm)

[0059] [Table 1] SuNo SuTy RD Mt SuFu Ar 1 SP INF 9.5000 DK 7.5472 2 SP INF 25.9100 OM1 DK 9.2096 3 SP INF 0.1000 DK 12.3490 4 NP 28.8770 6.9428 OM2 DK 12.8011 5 NP 47.6057 1.4383 DK 13.0167 6 SP INF TC DK 13.4207 7 NP -94.0326 TC OM3 DK 56.3488 8 NP -118.4506 TC OM3 RH 24.6180 9 NP -94.0326 TC DK 61.1608 10 XY-FS-96.6316 TC RH 34.1892 11 XY-FS 116.8783 TC RH 70.2483 12 XY-FS 291.7526 TC RH 58.1977 13 NP 41.5495 TC OM3 DK 40.5669 14 NP -63.1738 TC OM3 RH 25.6137 15 NP 24.5897 TC DK 24.1499 16 SP INF 0.0000 DK 112.8491 17 SP INF -608.6860 DK 112.8491 18 SP INF 0.0000 DK 998.8233

[0060] Table 2 shows the eccentricity settings for Example 1. The terms used in Table 2 and the following tables are defined below. The X-axis is the axis perpendicular to the plane of the paper, with the depth direction being positive. α rotation is the clockwise rotation around the X-axis when observed in the +X direction. The unit of distance is mm, and the unit of angle is °. Ec: Eccentricity XEc:X eccentricity YEc: Y-eccentricity ZEc:Z eccentricity αRo: α rotation Nr: Normal N / A: None DC & RE: Decenter and Return

[0061] [Table 2] CoNo Ec XEc YEc ZEc αRo 1 nr - - - - 2 N / A - - - - 3 N / A - - - - 4 N / A - - - - 5 N / A - - - - 6 dc & re - - 3.0000 - 7 dc & re - -37.3662 30.9474 -40.3930 8 dc & re - -4.1776 80.0000 -11.8012 9 dc & re - -37.3662 30.9474 -40.3930 10 dc & re - 46.7505 0.0000 15.4661 11 dc & re - -2.8256 62.0106 20.7235 12 dc & re - 81.6189 0.0000 -5.6859 13 dc & re - 100.5863 34.3353 1.4988 14 dc & re - 100.5863 80.0000 1.4988 15 dc & re - 100.5863 34.3353 1.4988 16 nr - - 80.0000 -

[0062] Table 3 shows the aspherical data for Example 1. The terms used in Table 3 and the following tables are defined below. Each item in the table is written in two rows. In Table 3 and the following tables, powers of 10 (e.g., 1.00 × 10) +18 This is expressed using E (for example, 1.00E+18). A: Fourth-order aspherical coefficients B: Sixth-order aspherical coefficients C: 8th-order aspherical coefficient [Table 3] SuNo 4 5 7 8 9 13 14 15 R 28.8770 47.6057 -94.0326 -118.4506 -94.0326 41.5495 -63.1738 24.5897 k 0 0 -4.56456798 -0.806373821 -4.56456798 -1.130497264 -1.223810266 0.0163858628 A -2.33958E-05 -8.62465E-06 -6.59366E-07 -6.44513E-08 -6.59366E-07 1.92800E-06 1.79185E-06 1.62137E-06 B -1.74199E-08 -2.81549E-08 5.14391E-11 -2.99274E-12 5.14391E-11 -6.00051E-10 -2.33459E-10 1.06802E-09 C -2.50049E-11 7.67102E-12 -6.52695E-15 1.45230E-15 -6.52695E-15 -3.50419E-15 -2.98931E-13 1.23508E-11

[0063] Table 4 shows the XY polynomial surface data for Example 1. In Table 4 and the following tables, C-xmyn is x m yn The coefficient C of the term (where m and n are integers greater than or equal to 0) mn is meant. When m and n are 0, or for x m or y n it is 1 and not shown.

[0064] [Table 4] SuNo 10 11 12 R -96.6316 116.8783 291.7526 k -0.0772 0.7438 16.6250 C-x4 -2.90007E-07 1.06165E-06 1.05110E+01 C-x2y2 -5.09409E-08 -2.36731E-06 1.84650E+01 C-y4 -1.67407E-07 -2.56278E-07 7.90174E+00 C-x6 9.59623E-10 -4.03104E-10 -1.02890E+01 C-x4y2 3.17737E-10 1.51031E-10 -2.47269E+01 C-x2y4 2.14788E-10 5.34443E-10 -2.43574E+01 C-y6 1.04278E-10 -9.22891E-11 -6.86895E+00 C-x8 2.58292E-13 -7.24293E-13 6.67097E+00 C-x6y2 -1.46208E-12 1.64145E-13 2.55089E+01 C-x4y4 -2.13827E-13 -9.37039E-14 3.24116E+01 C-x2y6 -2.19981E-13 -4.83831E-14 2.12806E+01 C-y8 -5.24404E-14 1.92004E-14 3.70168E+00 C-x10 0 1.86064E-15 7.98339E-01 C-x8y2 0 -1.3112E-16 -1.53734E+01 C-x6y4 0 2.60133E-17 -2.31288E+01 C-x4y6 0 7.50031E-18 -2.05257E+01 C-x2y8 0 3.65135E-19 -1.08005E+01 C-y10 0 -1.46754E-18 -1.36452E+00

[0065] Figure 3 is a cross-sectional view of the optical device 50 of Example 1.

[0066] The optical device 50 includes a prism PR, a lens 41, an internal reflective element 42, and a mirror element 43. The internal reflective element 42 is an integrated unit comprising a first optical element 42a, a second optical element 42b, and a third optical element 42c. The third optical element 42c is positioned between the first optical element 42a and the second optical element 42b. The mirror element 43 is positioned opposite the internal reflective element 42.

[0067] The first optical element 42a has a first transmission surface 5a, a third reflection surface 4c, and a second transmission surface 5b. The third reflection surface 4c is a concave inner reflection surface W1. In the first optical element 42a, the refractive surfaces W3 through which incident and reflected light pass are different optical surfaces for the first transmission surface 5a and the second transmission surface 5b. The first transmission surface 5a, the third reflection surface 4c, and the second transmission surface 5b have positive power.

[0068] The second optical element 42b has a first reflective surface 4a and a third transmissive surface 5c. The first reflective surface 4a is a concave inner surface reflective surface W1. In the second optical element 42b, the refractive surface W3 through which incident light and reflected light pass is a single third transmissive surface 5c, which is a common optical surface. A first aperture diaphragm ST1 is positioned on the first reflective surface 4a. A second aperture diaphragm ST2 is positioned on the third transmissive surface 5c.

[0069] The third optical element 42c has a fourth reflective surface 4d, which is the surface reflective surface W2. The back surface 6a, which is the surface opposite to the fourth reflective surface 4d, is a substantially smooth surface overall but is not an optical surface. A second light absorbing member AB2 is arranged on the back surface 6a.

[0070] The mirror element 43 has a second reflective surface 4b, which is the surface reflective surface W4, and a fifth reflective surface 4e, which is also the surface reflective surface W4. The second and fifth reflective surfaces 4b and 4e are integrated.

[0071] The optical device 50 has, in the optical path, a third transmitting surface 5c, a first reflecting surface 4a, a third transmitting surface 5c, a second reflecting surface 4b, a fourth reflecting surface 4d, a fifth reflecting surface 4e, a first transmitting surface 5a, a third reflecting surface 4c, and a second transmitting surface 5b, in the order from the reduction side to the expansion side. The third transmitting surface 5c, the fourth reflecting surface 4d, the first transmitting surface 5a, and the second transmitting surface 5b are arranged on the side of the second reflecting surface 4b. In addition, the second light absorbing member AB2 and the third reflecting surface 4c are arranged on the side of the first reflecting surface 4a.

[0072] Figures 4 and 5 show the lateral aberration characteristics of the optical device 50 or projection optical system 40 of Example 1. Figure 6 is a diagram illustrating the relationship between the display surface 2a of the liquid crystal panel 29G and the projection surface 2b of the screen SC of Example 1. In the upper part of Figure 6, the ● marks indicate the position of light rays on the display surface 2a, and in the lower part of Figure 6, the ● marks indicate the position of light rays on the projection surface 2b. The coordinates shown in Figure 6 are based on the center of the display surface 2a or the center of the projection surface 2b. Since the light ray positions are symmetrical, the lateral aberration diagram shows the characteristics of nine points on one side corresponding to the coordinates on the display surface 2a.

[0073] [Second Embodiment] The optical apparatus of the second embodiment will now be described. Note that the optical apparatus of the second embodiment is a modified version of the optical apparatus of the first embodiment, and the parts common to both embodiments will not be described.

[0074] Figure 7 shows the configuration and ray diagram of the optical device 50. Note that the optical device 50 illustrated in Figure 7 has the same configuration as the optical device 50 of Embodiment 2 described later. In Figure 7, some rays emitted from the first optical element 42a to the screen SC (see Figure 2) are outside the second transmission surface 5b, but in reality, such rays are prevented from being emitted by adjusting the display surface 2a.

[0075] The internal reflective element 42 includes a first optical element 42a, a second optical element 42b, and a third optical element 42c. In this embodiment, the second optical element 42b has a first reflective surface 4a which is a surface reflective surface W2. A first aperture diaphragm ST1 is arranged on the first reflective surface 4a.

[0076] In the example shown in Figure 7, the mirror element 43 is a single component in which the second reflective surface 4b and the fifth reflective surface 4e are integrated, but they may be separate components. Specifically, the mirror element 43 may be formed as a first mirror member 43a having the second reflective surface 4b and a second mirror member 43b having the fifth reflective surface 4e, which are formed separately. In this case, the positions of the second reflective surface 4b and the fifth reflective surface 4e can be adjusted individually.

[0077] The optical device 50 has a first light-absorbing member AB1 in the third optical element 42c, which is positioned between the first reflective surface 4a and the fourth reflective surface 4d, and specifically positioned to lie along the step. The first light-absorbing member AB1 prevents light reflected by the first reflective surface 4a and the second reflective surface 4b from leaking into an unspecified optical path and returning to the specified optical path from another location. In other words, the first light-absorbing member AB1 prevents the reflected light from leaking into an unspecified optical path and propagating through the inner surface of the inner reflective element 42, etc. This makes it possible to block unwanted light that is reflected by the nearby first reflective surface 4a and the second reflective surface 4b or their surroundings and causes stray light. Examples of materials for the first light-absorbing member AB1 include light-absorbing paints or other substances, light-shielding films, etc.

[0078] In addition, the second light-absorbing member AB2 may be placed on the back surface 6a of the third optical element 42c, which is the surface opposite to the fourth reflective surface 4d.

[0079] (Example 2) Table 5 shows the optical surface data for Example 2. The terms used in Table 5 are defined below. OM1=SBSL7_OHARA OM5 = refractive index; 1.743972, Abbe number; 44.85 [Table 5] SuNo SuTy RD Mt SuFu Ar 1 SP INF 9.5000 DK 7.5472 2 SP INF 25.9100 OM1 DK 9.2843 3 SP INF 1.7004 DK 12.5340 4 NP -60.4134 20.7975 OM1 DK 12.5345 5 NP -60.4209 0.1000 DK 17.3818 6 SP INF TC DK 20.0210 7 SP INF TC DK 24.0000 8 NP -194.9391 TC RH 42.6353 9 NP -75.0088 TC RH 23.7386 10 NP -245.4417 TC RH 148.1425 11 NP 912.8235 TC RH 57.3752 12 NP 69.9845 TC OM5 DK 35.8677 13 NP -41.5077 TC OM5 RH 22.3285 14 NP 69.9845 TC DK 44.7275 15 SP INF TC DK 140.6851 16 SP INF -608.6860 DK 140.6851 17 SP INF 0.0000 DK 1022.9551

[0080] Table 6 shows the eccentricity settings for Example 2. [Table 6] CoNo Ec XEc YEc ZEc αRo 1 nr - - - - 2 N / A - - - - 3 N / A - - - - 4 N / A - - - - 5 N / A - - - - 6 nr - -5.6670 - - 7 dc & re - - 3.0000 - 8 dc & re - 0.8199 150.0000 -7.8344 9 dc & re - 45.1103 10.0000 13.4408 10 dc & re - -42.4005 60.0000 -27.9448 11 dc & re - 155.8381 10.0000 -18.4113 12 dc & re - 135.3735 85.2273 -2.4034 13 dc & re - 135.3735 150.0000 -2.4034 14 dc & re - 135.3735 85.2273 -2.4034 15 nr - - 150.0000 -

[0081] Table 7 shows the aspherical data for Example 2. The terms used in Table 7 are defined below. A: Fourth-order aspherical coefficients B: Sixth-order aspherical coefficients C: 8th-order aspherical coefficient D: 10th-order aspherical coefficient [Table 7] SuNo 4 5 8 9 10 11 12 13 14 R -60.4134 -60.4209 -194.9391 -75.0088 -245.4417 912.8235 69.9845 -41.5077 69.9845 k 0 0 -1.773158752 2.230853425 0.247867 -23.0802348 0.93538444 -4.1657609481 0.9353844400 A -1.28321E-05 -4.32006E-06 -2.75594E-08 8.35291E-07 1.00706E-08 -1.12793E-08 8.92292E-07 -1.03795E-07 8.92292E-07 B -9.92816E-09 -1.39706E-09 4.99858E-14 1.95952E-10 1.29983E-13 6.80352E-12 -4.55805E-10 2.76972E-09 -4.55805E-10 C -4.57905E-11 -2.12420E-12 -1.07624E-17 1.70839E-13 -1.63649E-18 -2.20067E-15 1.74061E-13 -1.16309E-12 1.74061E-13 D 0 0 0 0 1.07479E-22 2.71454E-19 0 0 0

[0082] Figure 7 is a cross-sectional view of the optical device 50 of Example 2.

[0083] The optical device 50 includes a prism PR, a lens 41, an internal reflective element 42, and a mirror element 43. The internal reflective element 42 is an integrated unit comprising a first optical element 42a, a second optical element 42b, and a third optical element 42c. The third optical element 42c is positioned between the first optical element 42a and the second optical element 42b. The mirror element 43 is positioned opposite the internal reflective element 42.

[0084] The first optical element 42a has a first transmission surface 5a, a third reflection surface 4c, and a second transmission surface 5b. The third reflection surface 4c is a concave inner reflection surface W1. In the first optical element 42a, the refractive surfaces W3 through which incident light and reflected light pass are different for the first transmission surface 5a and the second transmission surface 5b. The first transmission surface 5a, the third reflection surface 4c, and the second transmission surface 5b have positive power.

[0085] The second optical element 42b has a first reflective surface 4a. The first reflective surface 4a is a concave surface reflective surface W2. A first aperture diaphragm ST1 is positioned on the first reflective surface 4a.

[0086] The third optical element 42c has a fourth reflective surface 4d, which is a surface reflective surface W2. A first light absorbing member AB1 is positioned between the first reflective surface 4a and the fourth reflective surface 4d, so as to lie along the step.

[0087] The mirror element 43 has a second reflective surface 4b which is the surface reflective surface W4 and a fifth reflective surface 4e which is the surface reflective surface W4.

[0088] The optical device 50 has a first reflective surface 4a, a second reflective surface 4b, a fourth reflective surface 4d, a fifth reflective surface 4e, a first transmissive surface 5a, a third reflective surface 4c, and a second transmissive surface 5b in the optical path, in order from the reduction side to the expansion side. The fourth reflective surface 4d, the first transmissive surface 5a, and the second transmissive surface 5b are arranged on the side of the first reflective surface 4a. The third reflective surface 4c is arranged on the opposite side from the first reflective surface 4a.

[0089] Figures 8 and 9 show the lateral aberration characteristics of the optical device 50 or projection optical system 40 of Example 2. Figure 10 is a diagram illustrating the relationship between the display surface 2a of the liquid crystal panel 29G and the projection surface 2b of the screen SC of Example 2.

[0090] (Example 3) Figure 11 is a cross-sectional view of the optical device 50 of Example 3. In Example 3, the second optical element 42b is separated from the internal reflective element 42. In other words, the second optical element 42b is an optical element having a surface reflective surface W2 that is separate from the internal reflective element 42.

[0091] The optical device 50 includes a prism PR, a lens 41, an internal reflective element 42, and a mirror element 43. The internal reflective element 42 is an integrated unit of a first optical element 42a and a third optical element 42c. The third optical element 42c is positioned between the first optical element 42a and the second optical element 42b. The mirror element 43 is positioned opposite the internal reflective element 42.

[0092] The first optical element 42a has a first transmission surface 5a, a third reflection surface 4c, and a second transmission surface 5b. The third reflection surface 4c is a concave inner reflection surface W1. In the first optical element 42a, the refractive surfaces W3 through which incident light and reflected light pass are different for the first transmission surface 5a and the second transmission surface 5b. The first transmission surface 5a, the third reflection surface 4c, and the second transmission surface 5b have positive power.

[0093] The second optical element 42b has a first reflective surface 4a. The first reflective surface 4a is a concave surface reflective surface W2. A first aperture diaphragm ST1 is positioned on the first reflective surface 4a. In the example shown in Figure 11, the second optical element 42b has the first reflective surface 4a formed as a surface reflective surface W2 on a light-transmitting member, but the first reflective surface 4a may be formed on a mirror element or the like. Alternatively, the first reflective surface 4a of the second optical element 42b may be an internal surface reflective surface W1.

[0094] The third optical element 42c has a fourth reflective surface 4d, which is a surface reflective surface W2. A first light absorbing member AB1 is positioned between the first reflective surface 4a and the fourth reflective surface 4d, so as to lie along the step. In Embodiment 3, the first light absorbing member AB1 may be omitted. Alternatively, a light absorbing member may be provided on the back surface 6a of the third optical element 42c.

[0095] The mirror element 43 has a second reflective surface 4b which is the surface reflective surface W4 and a fifth reflective surface 4e which is the surface reflective surface W4.

[0096] The optical device 50 has a first reflective surface 4a, a second reflective surface 4b, a fourth reflective surface 4d, a fifth reflective surface 4e, a first transmissive surface 5a, a third reflective surface 4c, and a second transmissive surface 5b in the optical path, in order from the reduction side to the expansion side. The fourth reflective surface 4d, the first transmissive surface 5a, and the second transmissive surface 5b are arranged on the side of the first reflective surface 4a. The third reflective surface 4c is arranged on the opposite side of the first reflective surface 4a.

[0097] [Third Embodiment] The optical apparatus of the third embodiment will be described below. Note that the optical apparatus of the third embodiment is a partial modification of the optical apparatus of the first embodiment, and the parts common to the optical apparatus of the first embodiment will not be described.

[0098] Figure 12 is a diagram illustrating a camera 102 incorporating an optical device 150 according to the third embodiment. As shown in Figure 12, the camera 102 includes an optical system portion 60 that images the subject OB, and a circuit device 80 that controls the operation of the optical system portion 60. The optical system portion 60 includes an imaging optical system 140 that forms an image of the subject OB, and an image detection device 120 that detects the image.

[0099] The image detection device 120 has an image sensor 129. The image sensor 129 is positioned on the reduction-side conjugate surface RC of the optical device 150. In this embodiment, the optical device 150 is an imaging optical device 151. The optical device 150 illustrated in Figure 12 has the same configuration as the optical device 50 of Example 1 (see Figure 3). Alternatively, the optical device 150 may be the optical device 50 of Examples 2 and 3 (see Figures 7 and 11). The imaging optical device 151 is obtained by omitting the prism PR that constitutes the optical device 50 of Examples 1 to 3 or by replacing it with a cover glass that is not shown.

[0100] The optical device 150 forms an image of the subject OB using the imaging optical system 140 and acquires the image detected by the imaging surface 2c of the image sensor 129.

[0101] [Other matters] The structure described above is an example, and can be modified in various ways as long as similar functionality can be achieved.

[0102] For example, in each embodiment, the optical device 50 may have one or more substantially powerless lenses added to it.

[0103] Furthermore, the optical device 50 can project images not only formed by the liquid crystal panels 29R, 29G, and 29B, but also images formed by optical modulation elements such as digital micromirror devices.

[0104] Furthermore, the second light-absorbing member AB2, the second aperture diaphragm ST2, etc., may be omitted.

[0105] Furthermore, the optical device 50 can be applied to head-up displays, in-vehicle projection systems, and the like.

[0106] [Summary of this disclosure] A summary of this disclosure is provided below.

[0107] (Note 1) A first reflective surface that possesses power, A second reflective surface having power is positioned on the enlarged side of the first reflective surface, A first optical element having a first transmissive surface, a third transmissive surface having a concave shape in the direction of incident light rays, and a second transmissive surface different from the first transmissive surface, arranged sequentially from the contraction side toward the enlargement side of the second reflective surface, A third optical element having a fourth reflective surface arranged on the enlarged side of the second reflective surface, A fifth reflective surface is positioned between the fourth reflective surface and the first transmissive surface, Equipped with, The third reflecting surface has positive power, The fourth reflective surface is positioned on the reduced conjugate surface side of the first and third reflective surfaces. optical equipment. By utilizing the refractive power of the first and second transmission surfaces, which are close to the third reflection surface (an internal reflection surface of the first optical element), ray control becomes easier, which is advantageous for miniaturization and performance improvement. Furthermore, the first and second transmission surfaces allow the incident and exit surfaces of the first optical element to have different functions, thereby improving optical performance. In addition, by making the third reflection surface an internal reflection surface, the size of the third reflection surface can be reduced, allowing for miniaturization of the entire optical system. Moreover, by providing multiple reflection surfaces in a direction that magnifies and projects with respect to the central axis of the reducing conjugate surface, the reflection angle can be minimized, suppressing a decrease in optical performance. As a result, it is possible to achieve a shorter focal length for the optical device and to miniaturize the optical device.

[0108] (Note 2) The optical apparatus as described in Appendix 1, wherein the second reflective surface and the fifth reflective surface are arranged on the side of the reduced conjugate surface that is closer to the third reflective surface.

[0109] (Note 3) The optical device according to either Appendix 1 or 2, wherein the second reflective surface and the fifth reflective surface are formed integrally. This makes it possible to miniaturize and reduce the cost of the optical system.

[0110] (Note 4) The optical apparatus according to any one of the appendices 1 to 3, further comprising a second optical element having a first reflective surface and a third transmissive surface through which both incident light incident on the first reflective surface and reflected light reflected by the first reflective surface are transmitted. By having the incident and exiting light rays pass through the third transmission surface, which is the same refractive surface, it becomes possible to control the light rays in a way that is not possible with surface reflection, thereby improving optical performance in a space-saving manner.

[0111] (Note 5) The optical device described in Appendix 4, wherein the first optical element, the second optical element, and the third optical element are an integrated internal reflective element. Furthermore, since the first to third optical elements are composed of the same element, cost reduction and improved assembly accuracy can be achieved.

[0112] (Note 6) The third reflective surface is positioned on the side of the first reflective surface. The third transmissive surface, the fourth reflective surface, the first transmissive surface, and the second transmissive surface are arranged on the side of the second reflective surface. Optical device as described in Appendix 5. This allows for the placement of an internal reflective surface, a surface reflective surface, and a refractive surface within the internal reflective element, which is advantageous for miniaturization.

[0113] (Note 7) The optical apparatus according to either of appendices 5 and 6, further comprising a second light-absorbing member disposed on the surface opposite to the fourth reflective surface. This makes it possible to block unwanted light that causes stray light reflected by the first and third reflective surfaces.

[0114] (Note 8) The second optical element further comprises the first reflective surface, The optical device described in any one of the appendices 1 to 3, wherein the first optical element, the second optical element, and the third optical element are an integrated internal reflective element.

[0115] (Note 9) The fourth reflective surface, the first transmissive surface, and the second transmissive surface are arranged on the side of the first reflective surface. The optical apparatus as described in Appendix 8, wherein the third reflective surface is located on the opposite side from the first reflective surface.

[0116] (Note 10) The optical apparatus according to any one of the appendices 1 to 9, further comprising a first light absorbing member disposed between the first reflective surface and the fourth reflective surface, which prevents light reflected from the first reflective surface and light reflected from the second reflective surface from leaking into an unspecified optical path and returning to the specified optical path from another location. This makes it possible to block unwanted light that would otherwise be reflected by the nearby first and second reflective surfaces or their surroundings, causing stray light.

[0117] (Note 11) An optical apparatus according to any one of the appendices 1 to 10, wherein an intermediate image is formed between the first transmission surface and the third reflection surface. This creates an intermediate image in the optical path on the reduced side of the concave third reflective surface, and by re-imaging the intermediate image with the third reflective surface, it becomes possible to shorten the focal length.

[0118] (Note 12) The first and second transmission surfaces are optical devices having power, as described in any one of the appendices 1 to 11.

[0119] (Note 13) The optical device according to any one of appendices 1 to 12, further comprising a first aperture diaphragm disposed on the first reflective surface. In particular, when using an optical device as a projection optical system, regulating the light emitted from the display device in the initial stages of the optical system can prevent unnecessary diffuse reflection within the optical system.

[0120] (Note 14) The optical apparatus according to any one of appendices 1 to 13, further comprising a positive lens disposed between the reducing conjugate surface and the first reflecting surface. This allows for telecentricity on the reduction side. Furthermore, it suppresses the spread of the light beam, enabling miniaturization of the entire optical system.

[0121] (Note 15) An optical device described in any one of the appendices 1 to 14, The optical device comprises an image forming unit that forms an image on the reduced conjugate surface, Equipped with, projector. This makes it possible to miniaturize projectors equipped with optical devices.

[0122] (Note 16) An optical device described in any one of the appendices 1 to 15, The image sensor arranged on the reduction-side conjugate surface of the optical device, Equipped with, Imaging device. This makes it possible to miniaturize imaging devices equipped with optical devices. [Explanation of Symbols]

[0123] 2...Projector, 2a...Display surface, 2b...Projection surface, 2c...Imaging surface, 4a~4e...Reflective surface, 5a~5c...Transmitting surface, 10...Light source device, 20...Image display device, 20a...Separation optical system, 20b...Image forming unit, 29R,29G,29B...Liquid crystal panel, 31...Cross dichroic prism, 40...Projection optical system, 41...Lens, 42...Internal reflection element, 42a,42b,42c...Optical element, 43...Mirror element, 50...Optical device, 51...Projection optical device, 60...Optical system section, 80...Circuit Device, 102...Camera, 120...Image detection device, 129...Image sensor, 140...Imaging optical system, 150...Optical device, 151...Imaging optical device, AB1~AB3...Light absorbing element, AN...Movement mechanism, MC...Magnification side conjugate plane, ML...Image light, OA...Device optical axis, OA2...Lens optical axis, OB...Subject, OM...Light modulation element, OX...Central axis, PR...Prism, RC...Reduction side conjugate plane, SC...Screen, ST1,ST2...Aperture diaphragm, W1...Internal reflection surface, W2,W4...Surface reflection surface, W3...Refractive surface

Claims

1. A first reflective surface that possesses power, A second reflective surface having power is positioned on the enlarged side of the first reflective surface, A first optical element having a first transmissive surface, a third transmissive surface having a concave shape in the direction of the incident light ray, and a second transmissive surface different from the first transmissive surface, arranged in order from the contraction side toward the enlargement side of the second reflective surface, A third optical element having a fourth reflective surface arranged on the enlarged side of the second reflective surface, A fifth reflective surface is disposed between the fourth reflective surface and the first transmissive surface, Equipped with, The third reflective surface has positive power, The fourth reflective surface is positioned on the reduced conjugate surface side of the first and third reflective surfaces. optical equipment.

2. In the optical apparatus described in claim 1, The second reflective surface and the fifth reflective surface are positioned on the reduced conjugate surface side of the third reflective surface. optical equipment.

3. In the optical apparatus described in claim 1, The second reflective surface and the fifth reflective surface are formed as a single unit. optical equipment.

4. In the optical apparatus described in claim 1, The second optical element further comprises a first reflective surface and a third transmissive surface through which both incident light incident on the first reflective surface and reflected light reflected by the first reflective surface are transmitted. optical equipment.

5. In the optical apparatus according to claim 4, The first optical element, the second optical element, and the third optical element are an integrated internal reflective element. optical equipment.

6. In the optical apparatus described in claim 5, The third reflective surface is positioned on the side of the first reflective surface. The third transmissive surface, the fourth reflective surface, the first transmissive surface, and the second transmissive surface are arranged on the side of the second reflective surface. optical equipment.

7. In the optical apparatus described in claim 5, The system further comprises a second light-absorbing member disposed on the surface opposite to the fourth reflective surface. optical equipment.

8. In the optical apparatus described in claim 1, The second optical element further comprises the first reflective surface, The first optical element, the second optical element, and the third optical element are an integrated internal reflective element. optical equipment.

9. In the optical apparatus according to claim 8, The fourth reflective surface, the first transmissive surface, and the second transmissive surface are arranged on the side of the first reflective surface. The third reflective surface is located on the opposite side from the first reflective surface. optical equipment.

10. In the optical apparatus described in claim 1, The system further comprises a first light-absorbing member positioned between the first reflective surface and the fourth reflective surface, which prevents light reflected from the first reflective surface and light reflected from the second reflective surface from leaking out into an unspecified optical path and returning to the specified optical path from another point. optical equipment.

11. In the optical apparatus according to any one of claims 1 to 10, An intermediate image is formed between the first transmission surface and the third reflection surface. optical equipment.

12. In the optical apparatus according to any one of claims 1 to 10, The first and second transparent surfaces have power. optical equipment.

13. In the optical apparatus according to any one of claims 1 to 10, The first reflective surface further comprises a first aperture diaphragm, optical equipment.

14. In the optical apparatus according to any one of claims 1 to 10, The system further comprises a positive lens positioned between the conjugate surface on the reduction side and the first reflective surface. optical equipment.

15. An optical apparatus according to any one of claims 1 to 10, The optical device comprises an image forming unit that forms an image on the reduced-side conjugate surface, Equipped with, projector.

16. An optical apparatus according to any one of claims 1 to 10, An image sensor arranged on the reduced conjugate surface of the optical device, Equipped with, Imaging device.

Images