WO2022044674A1

WO2022044674A1 - Reflection optical system and projection display device

Info

Publication number: WO2022044674A1
Application number: PCT/JP2021/027944
Authority: WO
Inventors: 賢天野
Original assignee: 富士フイルム株式会社
Priority date: 2020-08-28
Filing date: 2021-07-28
Publication date: 2022-03-03

Abstract

This reflection optical system is capable of enlarging an image on an image display surface so as to form an enlarged image on a projection surface. The reflection optical system comprises, in series along an optical path and in this order from the expansion side, a first reflection surface having a curvature and a second reflection surface having a curvature, wherein an intermediate image is formed at a position that is between the first reflection surface and the second reflection surface and that is conjugate to the image display surface. An intermediate image of a first main light beam which is incident on the projection surface at a minimum angle of incidence is located on the first reflection surface side of a boundary. Located on the second reflection surface of the boundary is an intermediate image of a second main light beam that passes through a point which, with respect to the intersection between a central main light beam and the projection surface, is symmetrical to the intersection between the first main light beam and the projection surface.

Description

Reflective optical system and projection type display device

The technology of the present disclosure relates to a catadioptric system and a projection type display device.

Conventionally, as a projection optical system that can be used in a projection type display device or the like and has a mirror or a reflective surface, those described in JP-A-2008-250296 and JP-A-2004-061961 are known. ..

In recent years, there has been a demand for a catadioptric system that is compact, secures a wide angle of view, and has good optical performance.

The present disclosure has been made in view of the above circumstances, and an object of the present invention is to provide a catadioptric system having a small size, a wide angle, and good optical performance, and a projection type display device provided with the catadioptric system. do.

The reflective optical system according to one aspect of the technique of the present disclosure is a reflective optical system capable of enlarging an image displayed on an image display surface and forming an enlarged image on the projected surface, and the reflective optical system is on the enlarged side. A first reflecting surface having a curvature and a second reflecting surface having a curvature are included in order from to the reduction side along the optical path, and the reflection optical system is between the first reflection surface and the second reflection surface. An intermediate image is formed at a position conjugate with the image display surface, and of the optical path of the central main light beam, which is the main light beam that passes through the center of the image and is incident on the projected surface, goes from the second reflecting surface to the first reflecting surface. The optical path and the optical path from the image display surface to the second reflection surface have two intersections, and of the two intersections, the intersection on the reduced side is reduced on the optical path from the image display surface to the second reflection surface. The side intersection is defined as one line-shaped optical path including the reduced side intersection among the optical paths from the image display surface to the second reflection surface, and the projection is performed at the minimum incident angle of the main light rays used to form the enlarged image. The main light incident on the surface is the first main light, the intersection of the first main light and the projected surface is the first intersection, and the point symmetric with the first intersection with respect to the intersection of the central main light and the projected surface. When the main ray passing through is the second main ray, the intermediate image of the first main ray is located on the first reflecting surface side with respect to the boundary, and the intermediate image of the second main ray is the second reflecting surface with respect to the boundary. Located on the side.

It is preferable that the first main ray and the second main ray intersect between the first reflecting surface and the projected surface.

It is preferable that the first reflecting surface has a concave shape.

The catadioptric system is composed of a first reflecting surface, a second reflecting surface, a third reflecting surface having a curvature, and a fourth reflecting surface having a curvature in order from the enlargement side to the reduction side along the optical path. It may be configured. In that case, it is preferable that the second reflecting surface has a concave shape, the third reflecting surface has a convex shape, and the fourth reflecting surface has a concave shape.

All the reflective surfaces included in the reflective optical system may be configured to have a free curved surface shape.

It is preferable that the optical axes of all the optical elements included in the reflective optical system are in the same plane.

The projected surface may be configured to be tilted 90 degrees with respect to the image display surface.

The projection type display device according to another aspect of the technique of the present disclosure includes an image display element for outputting an image and a reflection optical system according to the above aspect.

In addition to the above-mentioned components, "consisting of" and "consisting of" in the present specification may include members such as an image pickup element, a focusing mechanism, and a mechanical part such as an image stabilization mechanism. Is intended.

According to the technique of the present disclosure, it is possible to provide a catadioptric system having a small size, a wide angle, and good optical performance, and a projection type display device provided with the catadioptric system.

It is sectional drawing which shows the structure and the light flux of the main part of the projection type display device which concerns on one Embodiment. It is sectional drawing which shows the structure and the luminous flux of the reflection optical system which concerns on one Embodiment. It is a figure which shows the structure of the reflected optical system and the central main ray which concerns on one Embodiment. It is sectional drawing which shows an example of the state which the reflective optical system is housed in a housing. It is a figure for demonstrating the shape of each reflective surface. It is an enlarged view for demonstrating the shape of the 2nd reflective surface. It is an enlarged view for demonstrating the shape of the 3rd reflection surface. It is a figure which shows the position of the spot image on the image display surface. It is a figure which shows the spot diagram of one Example. It is a figure which shows the distortion grid of one Example. It is a schematic block diagram of the projection type display device which concerns on one Embodiment. It is a schematic block diagram of the projection type display device which concerns on another embodiment. It is a schematic block diagram of the projection type display device which concerns on still another Embodiment.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

The reflected optical system according to the technique of the present disclosure can be used as a projection optical system mounted on a projection type display device. FIG. 1 is a cross-sectional view showing a configuration of a main part of a projection type display device according to an embodiment of the technique of the present disclosure. The projection type display device of FIG. 1 includes a reflection optical system 1 according to an embodiment of the technique of the present disclosure. FIG. 2 is a cross-sectional view showing the configuration of the reflected optical system 1. Luminous flux is also shown in FIGS. 1 and 2.

In the projection type display device, the luminous flux including the image information output from the light bulb is incident on the reflected optical system 1 via the optical member PP. The light bulb is, for example, an image display element such as a DMD (Digital Micromirror Device: registered trademark) element or a liquid crystal display element. The light bulb has an image display surface Sim on which an image is displayed, and outputs an image to the image display surface Sim based on the image data. The optical member PP is a member assuming a filter, a prism, or the like used for color synthesis or separation of illumination light. The catadioptric system 1 magnifies and projects an image displayed on the image display surface Sim, and forms it as an enlarged image on the screen Scr. The screen Scr is an example of the "projected surface" of the technique of the present disclosure. The screen Scr means an object to be projected, and the screen Scr may be a wall surface, a floor surface, a ceiling, or the like, in addition to a dedicated screen.

In the following description, the "enlarged side" means the screen side on the optical path, and the "reduced side" means the image display surface side on the optical path.

The reflective optical system 1 according to the technique of the present disclosure includes a first reflecting surface R1 having a curvature and a second reflecting surface R2 having a curvature continuously in order from an enlargement side to a reduction side along an optical path. Will be done. As an example, the reflective optical system 1 shown in FIG. 2 has a first reflecting surface R1 having a curvature, a second reflecting surface R2 having a curvature, and a curvature continuously in order from the enlargement side to the reduction side along an optical path. It is composed of a third reflecting surface R3 and a fourth reflecting surface R4 having a curvature. According to this configuration, it is possible to achieve both miniaturization and wide-angle, even though the number of reflective surfaces is as small as four. Each reflective surface can be, for example, a mirror surface.

In the examples of FIGS. 1 and 2, the reflected optical system 1 functions as an imaging optical system for projection. By forming the entire imaging optical system for projection with the catadioptric system 1 that does not include the dioptric optical element, it is possible to make an optical system that does not generate chromatic aberration.

In FIGS. 1 and 2, the central luminous flux LF0, the first luminous flux LF1, and the second luminous flux LF2 are shown as the three luminous fluxes from the image display surface Sim toward the screen Scr. Further, the central main ray C0 which is the main ray of the central luminous flux LF0, the first main ray C1 which is the main ray of the first luminous flux LF1, and the second main ray C2 which is the main ray of the second luminous flux LF2 are also shown. The central luminous flux LF0 is a luminous flux passing through the center of the image on the image display surface Sim. The first main ray C1 is a main ray that is incident on the screen Scr at the minimum incident angle among the main rays used for forming the magnified image.

FIG. 1 also shows the intersection P0 between the central main ray C0 and the screen Scr, the intersection P1 between the first main ray C1 and the screen Scr, and the intersection P2 between the second main ray C2 and the screen Scr. The intersection point P2 is a point at a position symmetrical to the intersection point P1 with respect to the intersection point P0. The second main ray C2 is defined as the main ray passing through the intersection P2. In this specification, in the cross section connecting the intersection P2, the intersection P0, and the intersection P1, the bisector of the upper maximum ray and the lower maximum ray of each luminous flux is defined as the main ray.

The catadioptric system 1 forms an intermediate image between the first reflecting surface R1 and the second reflecting surface R2 and at a position conjugate with the image display surface Sim, and magnifies this intermediate image as an enlarged image on the screen Scr. Reimage. By forming an intermediate image between the first reflecting surface R1 and the second reflecting surface R2, it is possible to give a strong power to the first reflecting surface R1, and various aberrations that are problematic in wide-angle lensing can be caused. It is advantageous for correction. By giving the first reflecting surface R1 a strong power, it is advantageous for the first reflecting surface R1 to be miniaturized, and it is also possible to contribute to suppressing the increase in the size of the second reflecting surface R2.

In FIG. 2, the intermediate images formed by the central main ray C0, the first luminous flux LF1, and the second luminous flux LF2 are shown as the intermediate image MI0, the intermediate image MI1, and the intermediate image MI2. Hereinafter, the positional relationship between the intermediate image MI1 and the intermediate image MI2 will be described step by step.

As shown in FIGS. 2 and 3, in the reflection optical system 1, among the optical paths of the central main ray C0, the optical path from the second reflection surface R2 to the first reflection surface R1 and the second reflection surface from the image display surface Sim. The optical path toward R2 is configured to have two intersections. FIG. 3 shows a cross-sectional view showing the configuration of each optical element, and shows only the central main ray C0 as a light ray. The optical path from the image display surface Sim to the second reflection surface R2 is bent because the fourth reflection surface R4 and the third reflection surface R3 are on the way. In FIGS. 2 and 3, of the two intersections, the intersection located on the reduced side on the optical path from the image display surface Sim to the second reflecting surface R2 is the reduced side intersection Pr, and the intersection located on the larger side is the enlarged side. Shown as the intersection Pm. By configuring the two optical paths of the central main ray C0 to intersect twice in the reflected optical system 1, it is possible to form a bent optical path and lengthen the optical path, so that the power of each reflecting surface can be increased. The entire reflective optical system can be configured without making it excessively strong. As a result, it becomes easy to satisfactorily correct various aberrations such as distortion while reducing the size of the entire reflected optical system.

In the above configuration, one line segment-shaped optical path including the reduction side intersection Pr among the optical paths from the image display surface Sim to the second reflection surface R2 is defined as the boundary B. The one line segment-shaped optical path is an optical path that is not bent, and in this example, the boundary B is an optical path from the image display surface Sim to the fourth reflection surface R4.

The reflection optical system 1 is configured such that the intermediate image MI1 is located on the first reflecting surface R1 side with respect to the boundary B, and the intermediate image MI2 is located on the second reflecting surface R2 side with respect to the boundary B. That is, the intermediate image MI1 of the first main ray C1 is located on the first reflecting surface R1 side with respect to the boundary B, and the intermediate image MI2 of the second main ray C2 is located on the second reflecting surface R2 side with respect to the boundary B. It is configured to do. In this way, the fact that the positions of the intermediate images of the two main rays symmetrical with respect to the center of the image are on opposite sides of the boundary B causes a large curvature of field at the intermediate image positions. Become. By setting the first reflecting surface R1 so as to cancel this curvature of field, the curvature of field can be satisfactorily corrected on the magnified side of the intermediate image, so that the enlarged image with the curvature of field satisfactorily corrected. Can be projected on the screen. In other words, the catadioptric system 1 adopts a configuration in which a large curvature of field is generated at the intermediate image position in order to obtain a magnified image in which the curvature of field is well corrected on the screen. This configuration is advantageous in terms of both miniaturization of the optical system and good aberration correction, as compared with a configuration in which the curvature of field is satisfactorily corrected for both the intermediate image and the magnified image.

As shown in FIG. 2, it is preferable that the first main ray C1 and the second main ray C2 intersect between the first reflecting surface R1 and the screen Scr and have an intersection point P12. According to this configuration, as shown as an example in FIG. 4, when the reflective optical system 1 is housed in the housing 5, the size of the optical window 6 for emitting each light ray to the outside of the housing 5 can be reduced. .. Further, since the stray light incident on the inside of the housing 5 from the outside can be reduced, the display quality of the image projected on the screen can be improved.

It is preferable that the first reflecting surface R1 has a concave shape. By making the first reflecting surface R1 on the most enlarged side a concave surface having a converging action, it becomes easy to miniaturize the first reflecting surface R1. Further, by making the first reflecting surface R1 a concave surface, the size of the optical window 6 for emitting each light ray to the outside of the housing 5 can be reduced when the reflecting optical system 1 is housed in the housing 5. Further, since the stray light incident on the inside of the housing 5 from the outside can be reduced, the display quality of the image projected on the screen can be improved.

When the reflective optical system 1 is composed of the above four reflective surfaces having curvatures, the second reflective surface R2 has a concave shape, the third reflective surface R3 has a convex shape, and the fourth reflective surface R4 has a concave shape. It is preferable to have. In this case, the fourth reflecting surface R4 converges the light spreading from the image display element, and the third reflecting surface R3 and the second reflecting surface R2 properly maintain the power of the entire reflected optical system while maintaining a wide angle. It is advantageous to achieve both miniaturization and miniaturization.

FIG. 5 is a diagram for explaining the shape of each reflective surface. In the present specification, the concave and convex surfaces of each reflective surface are defined as follows. That is, a surface perpendicular to the normal of the reflecting surface at the intersection of the central main ray C0 and the reflecting surface (dotted line in FIG. 5) and in contact with the intersection of the central main ray C0 and the reflecting surface (two points in FIG. 5). When the chain line) is used as the reference plane, the surface shape facing the reflection optical system side from the reference plane is defined as a concave surface, and the surface shape facing the opposite side of the reference plane toward the reflection optical system side is defined as a convex surface. An enlarged view of the portion related to the second reflecting surface R2 of FIG. 5 is shown in FIG. 6, and an enlarged view of the portion related to the third reflecting surface R3 of FIG. 5 is shown in FIG. In this example, the second reflecting surface R2 has a concave shape, and the third reflecting surface R3 has a convex shape.

Note that all the reflective surfaces included in the reflective optical system 1 may be configured to have a free curved surface shape. Normally, in order to avoid interference between reflective surfaces, it is necessary to take a large eccentricity of components in the optical system, which causes eccentric aberration. However, the configuration having a free curved surface shape makes it easy to appropriately correct the eccentric aberration that occurs.

Further, it is preferable that the optical axes of all the optical elements included in the reflective optical system 1 are in the same plane. For example, in the reflective optical system 1 of this example, the optical axes of the four reflective surfaces, which are optical elements, are in the same plane. According to this configuration, the shape of the reflecting surface can be configured to have symmetry in a predetermined plane, which is advantageous in terms of cost and manufacturability.

The screen Scr may be configured to be tilted 90 degrees with respect to the image display surface Sim. According to such a configuration, it is advantageous to reduce the size of the entire device including the reflective optical system 1. The above 90 degrees is not limited to the complete 90 degrees, and may be an angle including an error generally allowed in the technical field to which the technique of the present disclosure belongs.

In the above description, the reflective optical system 1 composed of four reflective surfaces has been described as an example, but the reflective optical system according to the technique of the present disclosure includes the first reflective surface R1 and the second reflective surface R2. If so, the number of reflective surfaces may be three or five or more.

The above-mentioned preferable configuration and possible configuration can be any combination, and it is preferable that they are appropriately and selectively adopted according to the required specifications.

Next, the data of the examples will be described. As the numerical data of the reflected optical system 1 shown in FIG. 2, the surface data is shown in Table 1, the data related to eccentricity is shown in Table 2, and the free-form surface coefficients are shown in Tables 3A and 3B. The free-form surface coefficients are shown separately in two tables to avoid lengthening one table.

Table 1 shows surface data for the reflected optical system 1, the optical member PP, and the image display surface Sim. In Table 1, in the column of Sn, the surface number of the optical element on the most enlarged side (first reflective surface) is set as the first surface, and the surface numbers are shown when the numbers are increased one by one toward the reduced side. The surface numbers of free-form surfaces are marked with *. The radius of curvature of each surface is shown in the column of R, and the radius of curvature of the near axis is shown in the column of R of the free curved surface. The column D indicates the distance between each surface and the surface adjacent to the reduced side. "Reflective surface" is written in the Nd column corresponding to each reflective surface. The columns of Nd and νd corresponding to the enlarged side surface of the optical member PP indicate the refractive index of the optical member PP with respect to the d-line and the Abbe number of the d-line reference, respectively. The seventh surface of Table 1 corresponds to the image display surface Sim.

The values of the projection distance and the total angle of view are shown in the margin of Table 1. The projection distance is the distance from the first reflecting surface R1 to the screen Scr.

Table 2 shows the shift and tilt values of each surface. In the data in Table 2, in the right-handed XYZ Cartesian coordinate system, the reduction side direction is the + Z axis direction, the shift is the translation in the Y axis direction, and the tilt is the rotation around the X axis. The shift sign is positive in the + Y-axis direction and negative in the −Y-axis direction. The sign of the tilt is positive for counterclockwise rotation and negative for clockwise rotation when the X-axis is viewed in the direction from −X to + X. Table 2 shows the data when the first and subsequent surfaces are tilt-eccentric by -90 degrees.

Tables 3A and 3B show surface numbers and free-form surface coefficients for each free-form surface. The numerical value "E ± n" (n: integer) of the free-form surface coefficient in Table 3 means "× 10 ± n". The free-form surface coefficients shown in Tables 3A and 3B are the values of the rotationally asymmetric free-form surface coefficients C (i, j) in the free-form surface equation represented by the following equation.
Z = ΣΣC (i, j) ・ X ⁱ・ Y ^j
here,
X, Y, and Z are coordinates with the surface vertex as the origin.
Further, in the above equation, the value of X is an absolute value.
Further, in the above equation, the first Σ is the sum of i and the second Σ is the sum of j.

In the data in each table, degrees are used as the unit of angle and mm (millimeter) is used as the unit of length. Units can also be used. In addition, in each table shown below, numerical values rounded to a predetermined digit are listed.

FIG. 9 shows a spot diagram when light rays are traced from the enlargement side to the reduction side in the above embodiment. FIG. 8 shows an image display surface Sim which is an image formation position of a spot image when light rays are traced from the enlarged side. Each spot diagram in FIG. 9 is a spot diagram at each of the 15 grid points indicated by the black circles in FIG.

FIG. 10 shows the distortion grid of the above embodiment. The distorted grid shows the distorted shape of the grid pattern formed on the screen when an image composed of the grid pattern is projected by using the reflection optical system 1 of the above embodiment.

As can be seen from the above data, the reflected optical system 1 of the above embodiment is configured to be compact, but each aberration is satisfactorily corrected to realize high optical performance. Further, the total angle of view is 135 degrees, which is 120 degrees or more, which is a guideline for a wide angle, and a sufficiently wide angle of view is secured.

Next, the projection type display device according to the embodiment of the present disclosure will be described. FIG. 11 is a schematic configuration diagram of a projection type display device according to an embodiment of the present disclosure. The projection type display device 100 shown in FIG. 11 includes a reflection optical system 10 according to an embodiment of the present disclosure, a light source 15, transmission type display elements 11a to 11c as light valves corresponding to each color light, and for color separation. The dichroic mirrors 12 to 13, the cross dichroic prism 14 for color synthesis, the condenser lenses 16a to 16c, and the total reflection mirrors 18a to 18c for deflecting the optical path are provided. In FIG. 11, the reflective optical system 10 is schematically shown. Further, although an integrator is arranged between the light source 15 and the dichroic mirror 12, the illustration is omitted in FIG.

The white light from the light source 15 is decomposed into three color light beams (Green light, Blue light, Red light) by the dichroic mirrors 12 to 13, and then transmitted through the condenser lenses 16a to 16c, respectively, corresponding to each color light light beam. It is incident on the mold display elements 11a to 11c, modulated, color-synthesized by the cross dichroic prism 14, and then incident on the reflection optical system 10. The catadioptric system 10 projects an optical image of the modulated light modulated by the transmissive display elements 11a to 11c on the screen 105.

FIG. 12 is a schematic configuration diagram of a projection type display device according to another embodiment of the present disclosure. The projection type display device 200 shown in FIG. 12 includes a reflection optical system 210 according to the embodiment of the present disclosure, a light source 215, DMD elements 21a to 21c as light valves corresponding to each color light, and color separation and color synthesis. It has a TIR (Total Internal Reflection) prisms 24a to 24c for the purpose, and a polarization separation prism 25 for separating illumination light and projected light. Note that FIG. 12 schematically shows the reflected optical system 210. Further, although an integrator is arranged between the light source 215 and the polarization separation prism 25, the illustration thereof is omitted in FIG.

The white light from the light source 215 is reflected by the reflecting surface inside the polarization separation prism 25, and then decomposed into three color light beams (Green light, Blue light, Red light) by the TIR prisms 24a to 24c. Each color light flux after decomposition is incident on the corresponding DMD elements 21a to 21c and modulated, and the TIR prisms 24a to 24c proceed in the opposite directions to perform color synthesis, and then pass through the polarization separation prism 25. It is incident on the reflection optical system 210. The catadioptric system 210 projects an optical image of the modulated light modulated by the DMD elements 21a to 21c on the screen 205.

FIG. 13 is a schematic configuration diagram of a projection type display device according to still another embodiment of the present disclosure. The projection type display device 300 shown in FIG. 13 includes a reflection optical system 310 according to the embodiment of the present disclosure, a light source 315, reflection type display elements 31a to 31c as light valves corresponding to each color light, and for color separation. Dichroic mirrors 32 and 33, a cross dichroic prism 34 for color synthesis, a total reflection mirror 38 for optical path deflection, and polarization separation prisms 35a to 35c. In addition, in FIG. 13, the reflection optical system 310 is schematically shown. Further, although an integrator is arranged between the light source 315 and the dichroic mirror 32, the illustration thereof is omitted in FIG.

The white light from the light source 315 is decomposed into three color light fluxes (Green light, Blue light, Red light) by the dichroic mirrors 32 and 33. Each color light beam after decomposition passes through the polarization separation prisms 35a to 35c, is incident on the reflective display elements 31a to 31c corresponding to each color light beam, is modulated, is color-synthesized by the cross dichroic prism 34, and then is reflected. It is incident on the optical system 310. The catadioptric system 310 projects an optical image of the modulated light modulated by the reflective display elements 31a to 31c on the screen 305.

Although the techniques of the present disclosure have been described above with reference to embodiments and examples, the techniques of the present disclosure are not limited to the above embodiments and examples, and various modifications are possible. For example, the radius of curvature, the surface spacing, the free curved surface coefficient, and the like of each reflecting surface are not limited to the values shown in the above embodiment, and may take other values.

Further, the projection type display device according to the technique of the present disclosure is not limited to the above-mentioned configuration, and for example, the optical member and the light bulb used for luminous flux separation or luminous flux synthesis can be changed in various modes. .. The light valve is not limited to the mode in which the light from the light source is spatially modulated by the image display element and output as an optical image based on the image data, and the light itself output from the self-luminous image display element is the image data. It may be an aspect of outputting as an optical image based on. Examples of the self-luminous image display element include an image display element in which light emitting elements such as an LED (Light Emitting Diode) or an OLED (Organic Light Emitting Diode) are two-dimensionally arranged.

All documents, patent applications, and technical standards described herein are to the same extent as if the individual documents, patent applications, and technical standards were specifically and individually stated to be incorporated by reference. Incorporated by reference herein.

Claims

It is a catadioptric system that can magnify the image displayed on the image display surface and form it as an enlarged image on the projected surface.
The catadioptric system includes a first reflecting surface having a curvature and a second reflecting surface having a curvature continuously along an optical path from an enlargement side to a reduction side.
The catadioptric system forms an intermediate image between the first reflecting surface and the second reflecting surface and at a position conjugate with the image display surface.
Of the optical paths of the central main ray, which is the main ray that passes through the center of the image and is incident on the projected surface, the optical path from the second reflecting surface to the first reflecting surface and the second reflection from the image display surface. The optical path toward the surface has two intersections and has two points of intersection.
Of the two intersections, the intersection on the reduction side on the optical path from the image display surface to the second reflection surface is defined as the reduction side intersection.
Of the optical paths from the image display surface to the second reflection surface, one line segment-shaped optical path including the reduction side intersection is defined as a boundary.
Of the main rays used to form the magnified image, the main ray incident on the projected surface at the minimum incident angle is defined as the first main ray.
The intersection of the first main ray and the projected surface is set as the first intersection.
When the main ray passing through a point symmetrical to the first intersection with respect to the intersection of the central main ray and the projected surface is the second main ray.
The intermediate image of the first main ray is located on the first reflecting surface side with respect to the boundary, and the intermediate image of the second main ray is located on the second reflecting surface side with respect to the boundary. Optical system.
The reflected optical system according to claim 1, wherein the first main ray and the second main ray intersect between the first reflecting surface and the projected surface.
The reflective optical system according to claim 1 or 2, wherein the first reflective surface has a concave shape.
The reflective optical system is composed of the first reflecting surface, the second reflecting surface, the third reflecting surface having a curvature, and the fourth reflecting surface having a curvature, in order from the enlargement side to the reduction side along the optical path. The reflective optical system according to any one of claims 1 to 3.
The reflective optical system according to claim 4, wherein the second reflecting surface has a concave shape, the third reflecting surface has a convex shape, and the fourth reflecting surface has a concave shape.
The reflective optical system according to any one of claims 1 to 5, wherein all the reflective surfaces included in the reflected optical system have a free curved surface shape.
The reflective optical system according to any one of claims 1 to 6, wherein the optical axes of all the optical elements included in the reflected optical system are in the same plane.
The reflective optical system according to any one of claims 1 to 7, wherein the projected surface is tilted 90 degrees with respect to the image display surface.
An image display element that outputs the image and
A projection type display device including the catadioptric system according to any one of claims 1 to 8.