Imaging optical system, projection display device, and imaging device

Abstract

A high-resolution imaging optical system having a wide angle of view and in which various aberrations are appropriately corrected, a projection display device including this imaging optical system, and an imaging device including this imaging optical system are provided. The imaging optical system is composed of a first optical system and a second optical system in this order along the optical path from the enlargement side to the reduction side. An intermediate image is formed between the first optical system and the second optical system. The imaging optical system has a maximum half angle of view ωm of 1.73 on the enlargement side.

Description

[Technical Field]

[0001] The technology of the present disclosure relates to an imaging optical system, a projection display device, and an imaging device. [Background technology]

[0002] As optical systems applicable to projection devices, optical systems described in Patent Documents 1 to 6 below have been proposed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-009221 [Patent Document 2] Japanese Patent Application Publication No. 2020-008799 [Patent Document 3] International Publication No. 2017 / 195857 [Patent Document 4] Patent Publication No. 2021-173845 [Patent Document 5] International Publication No. 2020 / 152941 [Patent Document 6] Japanese Patent Publication No. 2023-155932 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for high-resolution imaging optical systems with wide angles of view and appropriate correction of various aberrations, and these demands are becoming higher every year.

[0005] The present disclosure has been made in consideration of the above circumstances, and provides a high-resolution imaging optical system having a wide angle of view and in which various aberrations are appropriately corrected, a projection-type display device equipped with this imaging optical system, and an imaging device equipped with this imaging optical system. [Means for solving the problem]

[0006] A first aspect of the present disclosure is an imaging optical system that forms an intermediate image at a position conjugate with a reduction-side imaging surface and re-images the intermediate image on an enlargement-side imaging surface, and that comprises, in order along an optical path from the enlargement side to the reduction side, a first optical system and a second optical system, and an intermediate image is formed between the first optical system and the second optical system. When the lens arranged adjacent to the reduction side of the longest lens spacing, which is the longest spacing on the optical axis between lenses in the imaging optical system, is an LA lens, and the lens arranged adjacent to the reduction side of the LA lens is an LB lens, the following conditional expressions (1), (2), and (3) are satisfied. 1.73 <tanωm<5 (1) 0<(RAf+RAr) / (RAf-RAr)<1.5 (2) 1<(RAr+RBf) / (RAr-RBf)<10 (3) Here, ωm is the maximum half angle of view on the enlargement side. RAf is the radius of curvature of the surface of the LA lens on the enlargement side. RAr is the radius of curvature of the surface of the LA lens on the reduction side. RBf is the radius of curvature of the surface of the LB lens on the enlargement side. Note that if the imaging optical system is a variable magnification optical system, the longest lens spacing and ωm are the values ​​at the wide-angle end.

[0007] A second aspect of the present disclosure provides the following: in the imaging optical system of the first aspect, when the air-equivalent distance of the longest lens spacing is Dmax, the focal length of the imaging optical system is f, and when the imaging optical system is a variable magnification optical system, Dmax and f are values ​​at the wide-angle end: 10 <Dmax / |f|<45 (4) Conditional expression (4) expressed as follows is satisfied.

[0008] A third aspect of the present disclosure is directed to the imaging optical system of the first aspect, where DAB is the distance on the optical axis between the LA lens and the LB lens, Ymax is the maximum image height on the reduction-side image plane, and when the imaging optical system is a variable magnification optical system, DAB and Ymax are values ​​at the wide-angle end: 0.1 <DAB / Ymax<1.5 (5) Conditional expression (5) expressed as follows is satisfied.

[0009] A fourth aspect of the present disclosure is an imaging optical system according to the first aspect, in which, when the refractive index of the LA lens at the d-line is NA and the refractive index of the LB lens at the d-line is NB, 1 <NA / NB<1.3 (6) Conditional expression (6) expressed as follows is satisfied.

[0010] A fifth aspect of the present disclosure is the imaging optical system of the first aspect, wherein the LA lens and the LB lens are disposed in a second optical system.

[0011] A sixth aspect of the present disclosure is the imaging optical system of the first aspect, wherein the LB lens is cemented to a lens disposed adjacent to the reduction side of the LB lens.

[0012] In a seventh aspect of the present disclosure, in the imaging optical system of the first aspect, when the lens closest to the intermediate image on the optical axis is the LM lens, the LM lens is a positive lens.

[0013] An eighth aspect of the present disclosure is an imaging optical system according to the seventh aspect, in which an LM lens is disposed adjacent to the enlarged side of the longest lens spacing.

[0014] A ninth aspect of the present disclosure is the imaging optical system of the first aspect, wherein a first optical path deflection member that bends the optical path is disposed within the longest lens spacing.

[0015] A tenth aspect of the present disclosure is directed to an imaging optical system according to the ninth aspect, in which, when DR is the distance on the optical axis from the first optical path deflector to the lens surface of the second optical system on the most reduction side, and Ymax is the maximum image height on the reduction-side imaging surface, and when the imaging optical system is a variable magnification optical system, DR and Ymax are values ​​at the wide-angle end, 8 <DR / Ymax<26 (7) Conditional expression (7) expressed as follows is satisfied.

[0016] An eleventh aspect of the present disclosure is the imaging optical system of the ninth aspect, wherein a second optical path deflection member that bends the optical path is disposed in the first optical system.

[0017] A twelfth aspect of the present disclosure is an imaging optical system according to the eleventh aspect, in which, when the distance on the optical axis from the first optical path deflection member to the second optical path deflection member is DMr12 and the maximum image height on the reduction-side imaging surface is Ymax, and when the imaging optical system is a variable magnification optical system, DMr12 and Ymax are values ​​at the wide-angle end, 8 <DMr12 / Ymax<30 (8) Conditional expression (8) expressed as follows is satisfied.

[0018] A thirteenth aspect of the present disclosure is an imaging optical system according to the first aspect, wherein the imaging optical system is a variable magnification optical system, and when one lens group is a group whose spacing in the optical axis direction from an adjacent group changes during magnification, the second optical system includes two or more lens groups that move during magnification.

[0019] A fourteenth aspect of the present disclosure is directed to the imaging optical system of the thirteenth aspect, wherein the number of lens groups included in the second optical system that move during magnification variation is two.

[0020] A fifteenth aspect of the present disclosure is directed to an imaging optical system according to the thirteenth aspect, where fz is the focal length of the lens group that maximizes the amount of movement when changing magnification from the wide-angle end to the telephoto end, and fw is the focal length of the imaging optical system at the wide-angle end: 10 <fz / |fw|<30 (9) Condition (9) is satisfied.

[0021] In a sixteenth aspect of the present disclosure, in the imaging optical system of the first aspect, the lens surface on the enlargement side of the lens closest to the enlargement side of the first optical system is aspheric, with a concave surface facing the enlargement side in the paraxial region, and with an inflection point where the concave-convex shape changes midway as one moves from the optical axis to the periphery.

[0022] A seventeenth aspect of the present disclosure is an imaging optical system of the first aspect, in which the lens surface on the reduction side of the lens on the most enlargement side of the first optical system is aspherical, with a convex surface facing the reduction side in the paraxial region, and with an inflection point where the concave-convex shape changes midway as one moves from the optical axis to the periphery.

[0023] An eighteenth aspect of the present disclosure is the imaging optical system of the first aspect, wherein the reduction side is telecentric.

[0024] A nineteenth aspect of the present disclosure is a projection display device including the imaging optical system according to any one of the first to eighteenth aspects.

[0025] A twentieth aspect of the present disclosure is an imaging device including the imaging optical system according to any one of the first to eighteenth aspects.

[0026] In this specification, "consisting of" and "consisting of" are intended to mean that, in addition to the listed components, other optical elements than lenses, such as lenses that have substantially no refractive power (power), apertures, masks, filters, cover glasses, flat mirrors, and prisms, as well as mechanical parts such as lens flanges, lens barrels, image sensors, and image stabilization mechanisms, may also be included.

[0027] The "lens group" and "focus group" in this specification are not limited to configurations consisting of multiple lenses, and may be configurations consisting of only one lens.

[0028] A compound aspherical lens (a lens in which a lens (e.g., a spherical lens) and an aspherical film formed on that lens are integrally constructed, functioning as a single aspherical lens overall) is not considered a cemented lens, but is treated as a single lens. Unless otherwise specified, the radius of curvature, sign of refractive power, and surface shape of lenses including aspherical surfaces are those in the paraxial region. The sign of the radius of curvature of the surface with a convex shape facing the enlargement side is positive, and the sign of the radius of curvature of the surface with a convex shape facing the reduction side is negative.

[0029] Unless otherwise specified, the "distance on the optical axis" used in conditional expressions is a geometric distance. The "focal length" used in conditional expressions is a paraxial focal length. The values ​​used in conditional expressions are values ​​based on the d-line.

[0030] The terms "d-line," "C-line," "F-line," and "g-line" used in this specification are emission lines. The wavelength of the d-line is 587.56 nm (nanometers), the wavelength of the C-line is 656.27 nm (nanometers), the wavelength of the F-line is 486.13 nm (nanometers), and the wavelength of the g-line is 435.84 nm (nanometers). [Effects of the Invention]

[0031] According to the present disclosure, it is possible to provide a high-resolution imaging optical system having a wide angle of view and in which various aberrations are appropriately corrected, a projection display device including this imaging optical system, and an imaging device including this imaging optical system. [Brief explanation of the drawings]

[0032] [Figure 1] 1 is a cross-sectional view showing the configuration of an imaging optical system according to an embodiment and a light beam, which corresponds to the imaging optical system of Example 1. FIG. [Figure 2] FIG. 10 is a diagram for explaining symbols in a conditional expression. [Figure 3] 1 is a cross-sectional view of an example of an imaging optical system in which a first optical path deflection member and a second optical path deflection member are arranged. [Figure 4] FIG. 10 is a cross-sectional view of another example of an imaging optical system in which a first optical path deflecting member and a second optical path deflecting member are arranged. [Figure 5] 3A to 3C are diagrams showing spherical aberration, astigmatism, distortion, and chromatic aberration of magnification of the imaging optical system of Example 1. [Figure 6] 3A to 3C are diagrams showing lateral aberrations of the imaging optical system of Example 1. [Figure 7] FIG. 10 is a cross-sectional view showing the configuration of an imaging optical system and a light beam according to a second embodiment. [Figure 8] 10A to 10C are diagrams showing spherical aberration, astigmatism, distortion, and chromatic aberration of magnification of the imaging optical system of Example 2. [Figure 9] 10A to 10C are diagrams showing lateral aberrations of the imaging optical system of Example 2. [Figure 10] FIG. 10 is a cross-sectional view showing the configuration of an imaging optical system and a light beam according to a third embodiment. [Figure 11]10A to 10C are diagrams showing spherical aberration, astigmatism, distortion, and chromatic aberration of magnification of the imaging optical system of Example 3. [Figure 12] 10A to 10C are diagrams showing lateral aberrations of the imaging optical system of Example 3. [Figure 13] FIG. 10 is a cross-sectional view showing the configuration of an imaging optical system and a light beam according to a fourth embodiment. [Figure 14] 10A to 10C are diagrams showing spherical aberration, astigmatism, distortion, and lateral chromatic aberration of the imaging optical system of Example 4. [Figure 15] 10A to 10C are diagrams showing lateral aberrations of the imaging optical system of Example 4. [Figure 16] FIG. 10 is a cross-sectional view showing the configuration of an imaging optical system and a light beam according to a fifth embodiment. [Figure 17] 10A to 10C are diagrams showing spherical aberration, astigmatism, distortion, and lateral chromatic aberration of the imaging optical system of Example 5. [Figure 18] 10A to 10C are lateral aberration diagrams of the imaging optical system of Example 5. [Figure 19] FIG. 10 is a cross-sectional view showing the configuration of an imaging optical system and a light beam according to a sixth embodiment. [Figure 20] 10A to 10C are diagrams showing spherical aberration, astigmatism, distortion, and lateral chromatic aberration of the imaging optical system of Example 6. [Figure 21] 10A to 10C are lateral aberration diagrams of the imaging optical system of Example 6. [Figure 22] FIG. 10 is a cross-sectional view showing the configuration of an imaging optical system and a light beam according to a seventh embodiment. [Figure 23] 10A to 10C are diagrams showing spherical aberration, astigmatism, distortion, and lateral chromatic aberration of the imaging optical system of Example 7. [Figure 24] 13A to 13C are diagrams showing lateral aberrations of the imaging optical system of Example 7. [Figure 25] 1 is a schematic configuration diagram of a projection display device according to an embodiment. [Figure 26] FIG. 10 is a schematic configuration diagram of a projection display device according to another embodiment. [Figure 27] FIG. 10 is a schematic configuration diagram of a projection display device according to yet another embodiment. [Figure 28] FIG. 10 is a schematic configuration diagram of a projection display device according to yet another embodiment. [Figure 29]1 is a perspective view of the front side of an imaging device according to an embodiment. [Figure 30] FIG. 30 is a perspective view of the rear side of the imaging device shown in FIG. 29. DETAILED DESCRIPTION OF THE INVENTION

[0033] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0034] FIG. 1 shows a cross-sectional view of the configuration of an imaging optical system according to an embodiment of the present disclosure and a light beam. In FIG. 1, the light beam is an on-axis light beam and a light beam at the maximum half angle of view. In FIG. 1, the left side is the enlargement side and the right side is the reduction side. The example shown in FIG. 1 corresponds to the imaging optical system of Example 1, which will be described later.

[0035] The imaging optical system of the present disclosure can be a projection optical system that is mounted in a projection display device and forms an image to be projected onto a screen, or can be an imaging optical system that is mounted in an imaging device and forms an image of an object. The following description will be given assuming that the imaging optical system is used as a projection optical system. To avoid redundant explanation, the "imaging optical system of the present disclosure" may be referred to simply as the "imaging optical system."

[0036] FIG. 1 shows an example in which an optical element PP and a light valve display surface Sim are arranged on the reduction side of the imaging optical system, assuming that the imaging optical system is installed in a projection display device. The light valve is a display element that outputs an optical image, and this optical image is displayed as an image on the display surface Sim. The light valve can be, for example, a liquid crystal display element or an image display element such as a DMD (Digital Micromirror Device: registered trademark). The optical element PP is a component that is assumed to be a filter, cover glass, color synthesis prism, etc. The optical element PP is a component that does not have refractive power. The material, length, and number of components of the optical element PP can be changed as appropriate, and a configuration in which the optical element PP is omitted is also possible.

[0037] In a projection display device, a light beam that has been given image information on a display surface Sim is incident on an imaging optical system via an optical member PP, and is then projected onto a screen Scr by the imaging optical system. In this case, the display surface Sim corresponds to the reduction-side imaging surface, and the screen Scr corresponds to the enlargement-side imaging surface. In this specification, the "screen Scr" refers to the object onto which the projection image formed by the imaging optical system is projected. The screen Scr may be a dedicated screen, or may be a wall, floor, ceiling, or exterior wall of a building.

[0038] In this specification, the term "enlargement side" refers to the side of the screen Scr on the optical path, and the term "reduction side" refers to the side of the display surface Sim on the optical path. In this specification, the terms "enlargement side" and "reduction side" are determined along the optical path, and this also applies to an imaging optical system having a bent optical path. "From the most enlargement side" means the side that is closest to the screen Scr in terms of distance. Furthermore, "adjacent" in relation to the arrangement of components means that they are adjacent to each other in terms of order on the optical path. In the following, to avoid redundant explanation, "in order along the optical path from the enlargement side to the reduction side" may be expressed as "in order from the enlargement side to the reduction side."

[0039] The imaging optical system of the present disclosure comprises, in order along the optical path from the enlargement side to the reduction side, a first optical system G1 and a second optical system G2. The imaging optical system of the present disclosure forms an intermediate image MI at a position conjugate with the reduction-side imaging plane and re-images the intermediate image MI on the enlargement-side imaging plane. The position where the intermediate image MI is formed is between the first optical system G1 and the second optical system G2. Note that the above "position where the intermediate image MI is formed" refers to the imaging position of the intermediate image MI on the optical axis, not off the optical axis.

[0040] The imaging optical system of the present disclosure is a relay optical system with a second optical system G2 as a relay group. When the imaging optical system of the present disclosure is applied as a projection optical system, the second optical system G2 forms an intermediate image MI of the image on the display surface, and the first optical system G1 enlarges this intermediate image MI and re-images it as a projected image on the screen Scr. When shortening the focal length of the imaging optical system to achieve a wide angle, the magnification-side lens tends to become large if high optical performance is to be achieved while maintaining the back focus required of the imaging optical system. By using a relay optical system in which the intermediate image MI is formed internally, it is possible to achieve a compact configuration by suppressing the increase in the diameter of the magnification-side lens, despite the ultra-wide angle optical system. Note that the intermediate image MI is schematically shown by a dashed line in Figure 1. The shape of the intermediate image MI in Figure 1 is not necessarily accurate. This method of illustrating the intermediate image MI is similar to that in other figures.

[0041] As an example, each optical system in FIG. 1 is configured as follows: The first optical system G1 is composed of lenses L1a to L1m, in order from the enlargement side to the reduction side. The second optical system G2 is composed of, in order from the enlargement side to the reduction side, a second-order lens group G2A, a second-order lens group G2B, a second-order lens group G2C, and a second-order lens group G2D. The second-order lens group G2A is composed of lenses L2a to L2d, in order from the enlargement side to the reduction side. The second-order lens group G2B is composed of a lens L2e. The second-order lens group G2C is composed of an aperture stop St and lenses L2f to L2h, in order from the enlargement side to the reduction side. The second-order lens group G2D is composed of a lens L2i. Note that the aperture stop St shown in FIG. 1 does not indicate its size or shape, but rather its position in the optical axis direction. This method of illustrating the aperture stop St is similar in other drawings.

[0042] The imaging optical system of the present disclosure may be a fixed-focus optical system or a variable magnification optical system. As an example, the imaging optical system of FIG. 1 is a zoom lens. FIG. 1 shows the state at the wide-angle end. In the example of FIG. 1, when changing magnification from the wide-angle end to the telephoto end, the second-subgroup G2B and the second-subgroup G2C move along the optical axis Z while changing the distance between them, while all other lenses are fixed relative to the display surface Sim. The arrows below the second-subgroup G2B and the second-subgroup G2C in FIG. 1 indicate the approximate movement directions of each lens group when changing magnification from the wide-angle end to the telephoto end.

[0043] In this specification, a lens group in the second optical system G2 is defined as a group whose distance in the optical axis direction between adjacent groups changes during magnification. That is, a "lens group" is a component of the second optical system G2 that includes at least one lens and is separated by an air gap that changes during magnification. During magnification, the distance between adjacent lenses within a lens group does not change. During magnification, each lens group is moved or fixed individually. A "lens group" may include components other than a lens without power, such as an aperture stop St and / or a plane mirror.

[0044] When the imaging optical system of the present disclosure is a variable magnification optical system, the second optical system G2 preferably includes two or more lens groups that move when the magnification is changed. By providing the second optical system G2, which is a relay group, with a variable magnification function, it becomes easier to simplify the lens configuration. When the second optical system G2 includes two lens groups that move when the magnification is changed, limiting the number of moving lens groups to two makes it easier to further simplify the lens configuration.

[0045] Generally, among the lenses in a relay group, the lenses on the magnification side and the reduction side tend to have larger diameters. Therefore, as shown in the example of Figure 1, when changing magnification, the second-A lens group G2A on the magnification side and the second-D lens group G2D on the reduction side are fixed, and the second-B lens group G2B and the second-C lens group G2C are moved, thereby making it possible to downsize the mechanical mechanism for movement. Furthermore, by fixing the second-D lens group G2D when changing magnification, fluctuations in telecentricity when changing magnification can be suppressed.

[0046] In this specification, the longest distance on the optical axis between lenses in an imaging optical system is referred to as the "longest lens distance." If the imaging optical system is a variable magnification optical system, the longest lens distance is the value at the wide-angle end. In other words, if the imaging optical system is a variable magnification optical system, which distance is the longest lens distance is determined in the wide-angle end state. Furthermore, the longest lens distance is the distance between lenses, and the distance between a lens and an element other than a lens (for example, a prism, a mirror, etc.) is never the longest lens distance.

[0047] In this specification, the lens arranged adjacent to the reduction side of the longest lens spacing is referred to as the "LA lens LA." Furthermore, the lens arranged adjacent to the reduction side of the LA lens LA is referred to as the "LB lens LB." In other words, the longest lens spacing, the LA lens LA, and the LB lens LB are positioned consecutively from the enlargement side to the reduction side. In the example of FIG. 1, the distance on the optical axis between lens L1m and lens L2a corresponds to the longest lens spacing, lens L2a corresponds to the LA lens LA, and lens L2b corresponds to the LB lens LB.

[0048] It is preferable that the LA lens LA and the LB lens LB are disposed within the second optical system G2, which is advantageous for efficiently correcting coma aberration at the periphery of the image.

[0049] It is preferable that the LB lens LB be cemented with a lens disposed adjacent to the reduction side of the LB lens LB to form a cemented lens, which is advantageous for correcting coma aberration for each color.

[0050] In this specification, the lens that is closest to the intermediate image MI on the optical axis is called the “LM lens LM.” In the example of Figure 1, the lens L1m corresponds to the LM lens LM.

[0051] The LM lens LM is preferably a positive lens. By locating a positive lens on the optical axis closest to the intermediate image MI, this positive lens can effectively function as a field lens, efficiently bending light rays at the periphery of the image. This is advantageous for reducing the size of the lens on the magnification side of the LM lens LM.

[0052] The LM lens LM is preferably arranged adjacent to the enlarged side of the longest lens spacing. The diameter of the lens tends to be large on the reduction side of the LM lens LM, which acts as a field lens. By locating the longest lens spacing adjacent to the reduction side of the LM lens LM, it is possible to reduce the number of lenses with large diameters.

[0053] It is preferable that the lens surface on the magnification side of the lens closest to the magnification side of the first optical system G1 is aspherical, with a concave surface facing the magnification side in the paraxial region and an inflection point where the concave and convex shapes change midway from the optical axis toward the periphery. In this case, distortion can be suppressed while ensuring a wide angle of view. Note that in this specification, the term "lens surface" refers to the surface of a lens through which light rays used for imaging pass.

[0054] It is preferable that the reduction-side lens surface of the lens closest to the enlargement side in the first optical system G1 be aspherical, with a convex surface facing the reduction side in the paraxial region and an inflection point where the concave-convex shape changes midway from the optical axis toward the periphery, thereby ensuring a wide angle of view and suppressing distortion.

[0055] An inflection point is a point where the surface shape changes from convex to concave, or from concave to convex, i.e., where the sign of the radius of curvature changes. By having an inflection point on the lens surface, the refractive power of the peripheral part of the lens can be determined independently of the refractive power of the paraxial region.

[0056] The imaging optical system of the present disclosure is preferably telecentric on the reduction side. Projection display devices that output high-definition images employ a three-plate system, which is required to have good telecentricity. In recent years, the so-called pixel shift system, which shifts pixels to achieve a resolution two or four times the number of pixels of the display element, has become more common in order to realize small, high-definition projection display devices. In this case, a telecentric optical system is desirable in order to ensure the required resolution.

[0057] In this specification, "telecentric on the reduction side" refers to a state in which, in the cross section of a light beam converging at an arbitrary point on the display surface Sim on the reduction side, the bisector between the upper maximum ray and the lower maximum ray is parallel to the optical axis Z or nearly parallel to the optical axis Z. In other words, "telecentric on the reduction side" in this specification does not necessarily refer to a completely telecentric state, i.e., a state in which the bisector is completely parallel to the optical axis Z, but also includes a state in which there is some error. Here, a state in which there is some error refers to a state in which the inclination of the bisector with respect to the optical axis Z is within the range of -3 degrees or more and +3 degrees or less. Note that, if the imaging optical system includes an aperture stop, the chief ray, which is a ray that passes through the center of the aperture stop, may be used as a substitute for the bisector.

[0058] The imaging optical system of the present disclosure preferably has distortion within the range of -3% or more and +3% or less. Furthermore, the imaging optical system preferably has a maximum total angle of view of 120 degrees or more. If the imaging optical system is a variable magnification optical system, the maximum total angle of view at the wide-angle end is preferably 120 degrees or more.

[0059] The imaging optical system of the present disclosure preferably does not include a reflective type element having power. In the imaging optical system of the present disclosure, it is preferable that all optical elements having power are refractive type elements. In imaging optical systems including reflective type optical elements having power, light beams near the optical axis reflected by the reflective surface of the optical element are generally blocked by the projection display device and cannot be used to form a projected image. To avoid this blocking, the center position of the image on the reduction-side image plane is shifted from the optical axis Z of the imaging optical system, and this shift amount is often large. Therefore, in imaging optical systems including reflective type optical elements having power, the size of the reflective surface having power tends to be large, making miniaturization often difficult. In contrast, in imaging optical systems in which all optical elements having power are refractive type, light beams near the optical axis can also be used to form a projected image, and even if the shift amount is small, the shift amount can be small. Reducing the shift amount enables the miniaturization of each optical element, which leads to the miniaturization of the entire optical system.

[0060] The imaging optical system of the present disclosure is preferably a coaxial system, which allows for a simpler optical system configuration than a non-coaxial system.

[0061] The imaging optical system of the present disclosure may be configured to include a focus group that moves to achieve focus when the projection distance changes. As an example, in the example of FIG. 1, the focus group is made up of lenses L1d to L1e. In FIG. 1, parentheses and a double-headed arrow parallel to the optical axis Z are written below the lenses corresponding to the focus group. Note that in the drawings of the present application, multiple lenses shown enclosed in a single parentheses accompanying an arrow indicating movement indicate that they move integrally. "Moving integrally" means moving simultaneously in the same direction by the same amount.

[0062] The imaging optical system of the present disclosure may be configured to include a mount that is detachable from a mount provided in a projection display device, which makes it easy to attach and detach the imaging optical system, which is convenient for replacement or maintenance of the imaging optical system.

[0063] Next, preferred and possible configurations for the conditional expressions of the imaging optical system of the present disclosure will be described. In the following description of the conditional expressions, to avoid redundant explanation, the same symbols are used for elements with the same definitions, and duplicate explanations of the symbols will be omitted. Also, to avoid redundant explanation, the "imaging optical system of the present disclosure" will be simply referred to as the "imaging optical system" below. When the imaging optical system is a variable magnification optical system, all symbols in the following conditional expressions are values ​​at the wide-angle end.

[0064] When the maximum half angle of view on the magnification side is ωm, it is preferable that the imaging optical system satisfy the following conditional expression (1). In conditional expression (1), tan is the tangent. FIG. 2 shows the configuration and light beam of the imaging optical system of FIG. 1, and shows the above-mentioned maximum half angle of view ωm as an example. Ensuring that the corresponding value of conditional expression (1) is not equal to or smaller than the lower limit thereof is advantageous for ensuring the required angle of view. Ensuring that the corresponding value of conditional expression (1) is not equal to or larger than the upper limit thereof can prevent the optical system from becoming too large. 1.73 <tanωm<5 (1)

[0065] To obtain better characteristics, the lower limit of conditional expression (1) is more preferably set to 1.8, even more preferably to 2, and even more preferably to 2.1. To obtain better characteristics, the upper limit of conditional expression (1) is more preferably set to 4, even more preferably to 3, and even more preferably to 2.6. For example, it is more preferable that the imaging optical system satisfy at least one of the following conditional expressions (1-1), (1-2), and (1-3). 1.8 <tanωm<4 (1-1) 2 <tanωm<3 (1-2) 2.1 <tanωm<2.6 (1-3)

[0066] It is preferable that the imaging optical system satisfy the following conditional expression (2). Here, the radius of curvature of the enlargement-side surface of the LA lens LA is RAf. The radius of curvature of the reduction-side surface of the LA lens LA is RAr. By satisfying conditional expression (2), the refractive power arrangement on the enlargement-side surface and the reduction-side surface of the LA lens LA becomes suitable, which is advantageous for good correction of spherical aberration. 0<(RAf+RAr) / (RAf-RAr)<1.5 (2)

[0067] To obtain better characteristics, the lower limit of conditional expression (2) is more preferably set to 0.1, even more preferably to 0.2, and even more preferably to 0.3. To obtain better characteristics, the upper limit of conditional expression (2) is more preferably set to 1, even more preferably to 0.8, and even more preferably to 0.7. For example, it is more preferable that the imaging optical system satisfy at least one of the following conditional expressions (2-1), (2-2), and (2-3). 0.1<(RAf+RAr) / (RAf-RAr)<1 (2-1) 0.2<(RAf+RAr) / (RAf-RAr)<0.8 (2-2) 0.3<(RAf+RAr) / (RAf-RAr)<0.7 (2-3)

[0068] It is preferable that the imaging optical system satisfy the following conditional expression (3). Here, the radius of curvature of the enlargement-side surface of the LB lens LB is RBf. Conditional expression (3) defines the appropriate range of the shape factor of the air lens when the air gap between the reduction-side surface of the LA lens LA and the enlargement-side surface of the LB lens LB is considered to be an air lens. Satisfying conditional expression (3) is advantageous for appropriately correcting coma and field curvature. 1<(RAr+RBf) / (RAr-RBf)<10 (3)

[0069] In order to obtain better characteristics, the lower limit of conditional expression (3) is more preferably set to 1.5, even more preferably to 2, and even more preferably to 2.5. In order to obtain better characteristics, the upper limit of conditional expression (3) is more preferably set to 5, even more preferably to 4.5, and even more preferably to 4. For example, it is more preferable that the imaging optical system satisfy at least one of the following conditional expressions (3-1), (3-2), and (3-3). 1.5<(RAr+RBf) / (RAr-RBf)<5 (3-1) 2<(RAr+RBf) / (RAr-RBf)<4.5 (3-2) 2.5<(RAr+RBf) / (RAr-RBf)<4 (3-3)

[0070] It is more preferable that the imaging optical system simultaneously satisfy the above conditional expressions (1), (2), and (3). When the imaging optical system simultaneously satisfies the conditional expressions (1), (2), and (3), it becomes easy to realize an optical system with a wide angle of view, a reduced number of lenses, and high resolution in which various aberrations are appropriately corrected.

[0071] It is preferable that the imaging optical system satisfy the following conditional expression (4). Here, the air-equivalent distance of the longest lens spacing is defined as Dmax. The focal length of the imaging optical system is defined as f. As an example, FIG. 2 shows the air-equivalent distance Dmax of the longest lens spacing. By ensuring that the corresponding value of conditional expression (4) is not equal to or less than the lower limit, it is advantageous to correct various aberrations while limiting the number of lenses. Furthermore, satisfying conditional expressions (2) and (3) and ensuring that the corresponding value of conditional expression (4) is not equal to or less than the lower limit, it is advantageous to correct various aberrations while limiting the number of lenses. By ensuring that the corresponding value of conditional expression (4) is not equal to or greater than the upper limit, it is advantageous to shorten the overall lens length, thereby preventing the optical system from becoming too large. 10 <Dmax / |f|<45 (4)

[0072] In order to obtain better characteristics, the lower limit of conditional expression (4) should more preferably be set to 12, even more preferably to 14, and even more preferably to 15. In order to obtain better characteristics, the upper limit of conditional expression (4) should more preferably be set to 40, even more preferably to 35, and even more preferably to 32. For example, it is more preferable that the imaging optical system satisfy at least one of the following conditional expressions (4-1), (4-2), and (4-3). 12 <Dmax / |f|<40 (4-1) 14 <Dmax / |f|<35 (4-2) 15 <Dmax / |f|<32 (4-3)

[0073] It is preferable that the imaging optical system satisfy the following conditional expression (5). Here, the distance on the optical axis between the LA lens LA and the LB lens LB is defined as DAB. The maximum image height on the reduction-side imaging surface is defined as Ymax. As an example, FIG. 2 shows the above-mentioned distance DAB and maximum image height Ymax. By ensuring that the corresponding value of conditional expression (5) is not below the lower limit, the distance DAB does not become too small, which is advantageous for ensuring the degree of freedom in the curvature of the reduction-side surface of the LA lens LA and the enlargement-side surface of the LB lens LB. By ensuring that the corresponding value of conditional expression (5) is not above the upper limit, the distance DAB does not become too large, which allows the air gap between the reduction-side surface of the LA lens LA and the enlargement-side surface of the LB lens LB to be regarded as an air lens. Satisfying conditional expression (5) is advantageous for appropriately exerting the effect of conditional expression (3). 0.1 <DAB / Ymax<1.5 (5)

[0074] To obtain better characteristics, the lower limit of conditional expression (5) is more preferably set to 0.15, even more preferably to 0.2, and even more preferably to 0.22. To obtain better characteristics, the upper limit of conditional expression (5) is more preferably set to 1.2, even more preferably to 0.9, and even more preferably to 0.6. For example, it is more preferable that the imaging optical system satisfy at least one of the following conditional expressions (5-1), (5-2), and (5-3). 0.15 <DAB / Ymax<1.2 (5-1) 0.2 <DAB / Ymax<0.9 (5-2) 0.22 <DAB / Ymax<0.6 (5-3)

[0075] It is preferable that the imaging optical system satisfy the following conditional expression (6). Here, the refractive index of the LA lens LA at the d-line is defined as NA. The refractive index of the LB lens LB at the d-line is defined as NB. By ensuring that the corresponding value of conditional expression (6) is not below the lower limit, it becomes easy to maintain a favorable balance between the refractive power of the reduction-side surface of the LA lens LA and the refractive power of the enlargement-side surface of the LB lens LB, and the amount of coma aberration generated can be suppressed. By ensuring that the corresponding value of conditional expression (6) is not above the upper limit, the refractive index of the LB lens LB does not become too low, which is advantageous for maintaining good optical performance in the peripheral parts of the image and is particularly advantageous for good correction of astigmatism. 1 <NA / NB<1.3 (6)

[0076] To obtain better characteristics, the lower limit of conditional expression (6) should preferably be set to 1.05, more preferably to 1.08, and even more preferably to 1.1. To obtain better characteristics, the upper limit of conditional expression (6) should preferably be set to 1.25, more preferably to 1.2, and even more preferably to 1.15. For example, it is more preferable that the imaging optical system satisfy at least one of the following conditional expressions (6-1), (6-2), and (6-3). 1.05 <NA / NB<1.25 (6-1) 1.08 <NA / NB<1.2 (6-2) 1.1 <NA / NB<1.15 (6-3)

[0077] When the imaging optical system is a variable magnification optical system and the second optical system G2 includes two or more lens groups that move during magnification variation, it is preferable that the imaging optical system satisfy the following conditional expression (9). Here, the focal length of the lens group that moves the most when magnification is varied from the wide-angle end to the telephoto end is defined as fz. The focal length of the imaging optical system at the wide-angle end is defined as fw. By ensuring that the corresponding value of conditional expression (9) is not below the lower limit, the refractive power of the lens group that moves the most when magnification is varied from the wide-angle end to the telephoto end does not become too strong, which is advantageous for suppressing fluctuations in spherical aberration during magnification variation. By ensuring that the corresponding value of conditional expression (9) is not above the upper limit, the refractive power of the lens group that moves the most when magnification is varied from the wide-angle end to the telephoto end does not become too weak, which reduces the amount of movement during magnification variation, which is advantageous for reducing the size of the entire optical system. 10 <fz / |fw|<30 (9)

[0078] In order to obtain better characteristics, the lower limit of conditional expression (9) should preferably be set to 13, more preferably to 15, and even more preferably to 17. In order to obtain better characteristics, the upper limit of conditional expression (9) should preferably be set to 28, more preferably to 26, and even more preferably to 25. For example, it is more preferable that the imaging optical system satisfy at least one of the following conditional expressions (9-1), (9-2), and (9-3). 13 <fz / |fw|<28 (9-1) 15 <fz / |fw|<26 (9-2) 17 <fz / |fw|<25 (9-3)

[0079] It is preferable that the imaging optical system satisfy the following conditional expression (10). Here, the back focus of the imaging optical system in terms of the air equivalent distance when the reduction side is the back side is defined as Bf. By satisfying conditional expression (10), it is possible to ensure a back focus of an appropriate length. It is more preferable that the imaging optical system satisfy the following conditional expression (10-1). By ensuring that the corresponding value of conditional expression (10-1) is not equal to or greater than the upper limit value, it is possible to prevent the optical system from becoming too large. Bf / |f|>5 (10) 5 <Bf / |f|<20 (10-1)

[0080] The imaging optical system of the present disclosure may be configured so that a first optical path deflection member that bends the optical path is disposed within the longest lens spacing. Bending the optical path enables a compact configuration, which is advantageous for miniaturization.

[0081] Furthermore, the imaging optical system of the present disclosure may be configured so that a second optical path deflector that bends the optical path is disposed within the first optical system G1. Bending the optical path enables a compact configuration, which is advantageous for miniaturization.

[0082] The imaging optical system of the present disclosure may be configured such that a first optical path deflection member that bends the optical path is disposed within the longest lens spacing, and a second optical path deflection member that bends the optical path is disposed within the first optical system G1. By including two optical path deflection members, the imaging optical system can be more compact than an optical path deflection member that includes only one optical path deflection member, which is advantageous for miniaturization. Furthermore, if the bending member is configured to be rotatable, the most magnifying lens can be positioned in any direction, making it possible to project in various directions while keeping the projection display device body fixed.

[0083] The first optical path deflecting member and the second optical path deflecting member may be, for example, a prism having a reflective surface, a mirror, or the like. The angle at which the optical path of the first optical path deflecting member and the second optical path deflecting member is bent can be set arbitrarily, for example, to 90 degrees. Setting the angle at which the optical path is bent to 90 degrees enables a structure that is easy to manufacture. Note that this "90 degrees" includes an error that is practically acceptable in the technical field to which the technology of the present disclosure pertains. The error may be, for example, in the range of -5 degrees or more and +5 degrees or less. When the imaging optical system is a variable magnification optical system, it is preferable that the first optical path deflecting member and the second optical path deflecting member be fixed during magnification change in order to simplify the device.

[0084] As an example, Fig. 3 shows a configuration example in which the above-mentioned first optical path deflection member and second optical path deflection member are arranged in the imaging optical system of Fig. 1. Fig. 3 shows the configuration at the wide-angle end, and some of the lens reference numerals are omitted to avoid complicating the drawing.

[0085] The imaging optical system of Fig. 3 comprises, in order along the optical path from the magnification side to the reduction side, a first optical system G1r and a second optical system G2r. The first optical system G1r of Fig. 3 differs from the first optical system G1 of Fig. 1 in that a mirror Mr2 is disposed between lenses L1g and L1h to bend the optical path, but the other lens configurations are the same. The second optical system G2r of Fig. 3 differs from the second optical system G2 of Fig. 1 in that a mirror Mr1 is disposed on the magnification side of lens L2a to bend the optical path, but the other lens configurations are the same. The mirror Mr1 corresponds to the first optical path deflection member, and the mirror Mr2 corresponds to the second optical path deflection member.

[0086] FIG. 4 shows another example configuration in which the first optical path deflecting member and the second optical path deflecting member are arranged in the imaging optical system of FIG. 1. The imaging optical system of FIG. 4 is composed of a first optical system G1r and a second optical system G2r, arranged in this order along the optical path from the enlargement side to the reduction side. The imaging optical system of FIG. 4 has the same configuration as the imaging optical system of FIG. 3, except for the direction in which the optical path is bent. In the example of FIG. 3, the mirrors Mr1 and Mr2 are arranged so that their extensions intersect, and the optical path of the entire imaging optical system roughly resembles a "U" rotated 90 degrees counterclockwise. In contrast, in the example of FIG. 4, the mirrors Mr1 and Mr2 are arranged parallel to each other, and the optical path of the entire imaging optical system is roughly "Z" shaped. However, in the technology of the present disclosure, the way in which the optical path is bent is not limited to the examples in Figures 3 and 4, and the optical path may be bent at an angle between the examples in Figures 3 and 4, and the angle at which the optical path is bent can be set arbitrarily within the possible range.

[0087] In a configuration in which a first optical path deflection member that bends the optical path is disposed within the longest lens spacing, it is preferable that the imaging optical system satisfy the following conditional expression (7). Here, the distance on the optical axis from the first optical path deflection member to the lens surface of the second optical system G2r on the reduction side is defined as DR. As an example, FIG. 3 shows the above distance DR. By ensuring that the corresponding value of conditional expression (7) is not equal to or less than the lower limit, it is possible to ensure the length necessary to avoid interference with the optical engine. By ensuring that the corresponding value of conditional expression (7) is not equal to or greater than the upper limit, it is possible to prevent the optical system from becoming too large. 8 <DR / Ymax<26 (7)

[0088] In order to obtain better characteristics, the lower limit of conditional expression (7) should preferably be set to 11, more preferably to 12, and even more preferably to 13. In order to obtain better characteristics, the upper limit of conditional expression (7) should preferably be set to 24, more preferably to 22, and even more preferably to 20. For example, it is more preferable that the imaging optical system satisfy at least one of the following conditional expressions (7-1), (7-2), and (7-3). 11 <DR / Ymax<24 (7-1) 12 <DR / Ymax<22 (7-2) 13 <DR / Ymax<20 (7-3)

[0089] In a configuration in which a first optical path deflector that bends the optical path is disposed within the longest lens spacing and a second optical path deflector that bends the optical path is disposed within the first optical system, the imaging optical system preferably satisfies the following conditional expression (8). Here, the distance on the optical axis from the first optical path deflector to the second optical path deflector is designated DMr12. As an example, FIG. 3 shows the above-described distance DMr12. When it is desired to minimize the visibility of the projection display device body for spatial presentations, projection may be performed with the projection display device body hidden while leaving only a portion of the lens exposed. By ensuring that the value corresponding to conditional expression (8) is not less than the lower limit, projection in this state is possible, thereby contributing to improving the versatility of the projection display device. Furthermore, in the configuration example shown in FIG. 3, by ensuring that the value corresponding to conditional expression (8) is not less than the lower limit, the length necessary to avoid interference with the optical engine can be ensured. By ensuring that the value corresponding to conditional expression (8) is not less than the upper limit, the size of the optical system can be suppressed. 8 <DMr12 / Ymax<30 (8)

[0090] In order to obtain better characteristics, the lower limit of conditional expression (8) should preferably be set to 9, more preferably to 9.5, and even more preferably to 10. In order to obtain better characteristics, the upper limit of conditional expression (8) should preferably be set to 25, even more preferably to 20, and even more preferably to 18. For example, it is more preferable that the imaging optical system satisfy at least one of the following conditional expressions (8-1), (8-2), and (8-3). 9 <DMr12 / Ymax<25 (8-1) 9.5 <DMr12 / Ymax<20 (8-2) 10 <DMr12 / Ymax<18 (8-3)

[0091] The above-described preferred and possible configurations, including those related to the conditional expressions, can be combined in any combination within a range consistent with each other, and are preferably selectively adopted as appropriate according to the required specifications. Various modifications are possible within a range that does not deviate from the spirit of the technology of the present disclosure. For example, in the technology of the present disclosure, the number of lenses included in each optical system, the number of lens groups included in the second optical system, the number of lenses included in each lens group, and the number of lenses included in the focus group may be different from those in the example of FIG. 1. The lens groups that are fixed and move during magnification change, as well as the focus group, may be different from those in the example of FIG. 1.

[0092] As an example, a preferred embodiment of the imaging optical system of the present disclosure is an imaging optical system that forms an intermediate image at a position conjugate with the reduction-side imaging plane and re-images the intermediate image on the enlargement-side imaging plane, and is composed of, in order along the optical path from the enlargement side to the reduction side, a first optical system G1 and a second optical system G2, an intermediate image MI is formed between the first optical system G1 and the second optical system G2, an LA lens LA is arranged adjacent to the reduction side of the longest lens spacing, which is the longest spacing on the optical axis between lenses in the imaging optical system, and an LB lens LB is arranged adjacent to the reduction side of the LA lens LA, and satisfies the above conditional expressions (1), (2), and (3).

[0093] Next, examples of the imaging optical system of the present disclosure will be described with reference to the drawings. Note that the reference symbols assigned to each lens, each lens group, and each optical system in the cross-sectional views of each example are used independently for each example to avoid cluttering the explanation and drawings due to an increase in the number of digits in the reference symbols. Therefore, even if common reference symbols are assigned in drawings of different examples, this does not necessarily mean that the configuration is the same.

[0094] [Example 1] The configuration of the imaging optical system of Example 1 and a cross-sectional view of a light beam are shown in FIG. 1. The illustration method and configuration are as described above, so some overlapping explanations will be omitted here. The imaging optical system of Example 1 is a variable magnification optical system and comprises, in order from the magnification side to the reduction side, a first optical system G1 and a second optical system G2. An intermediate image MI is formed between the first optical system G1 and the second optical system G2. The second optical system G2 comprises, in order from the magnification side to the reduction side, a second-A lens group G2A, a second-B lens group G2B, a second-C lens group G2C, and a second-D lens group G2D. When varying magnification from the wide-angle end to the telephoto end, the second-B lens group G2B and the second-C lens group G2C move along the optical axis Z while changing the distance between them, while all other lenses are fixed relative to the display surface Sim.

[0095] For the imaging optical system of Example 1, basic lens data is shown in Tables 1A and 1B, specifications and variable surface spacing during magnification are shown in Table 2, and aspherical coefficients are shown in Table 3. Here, to avoid making one table too long, the basic lens data is shown in two tables, Table 1A and Table 1B. The table of basic lens data also includes the optical element PP. While FIG. 1 shows a diagram of a linear optical path, the table of basic lens data includes data on the first optical path deflection element and the second optical path deflection element in consideration of the case where a first optical path deflection element and a second optical path deflection element are disposed within the imaging optical system.

[0096] The basic lens data table is written as follows. The Sn column indicates the surface number, with the surface closest to the magnification side designated as surface 1 and the numbers increasing by one toward the reduction side. Note that the surface number corresponding to the first optical path deflector is marked "Mr1," and the surface number corresponding to the second optical path deflector is marked "Mr2." The surface number corresponding to the aperture stop St is marked with the surface number and "(St)." The surface closest to the reduction side in the table corresponds to the display surface Sim. The R column indicates the radius of curvature of each surface. The sign of the radius of curvature is positive for surfaces with a convex shape facing the magnification side, and negative for surfaces with a convex shape facing the reduction side. The D column indicates the surface spacing on the optical axis between each surface and the surface adjacent to it on the reduction side. The variable surface spacing during magnification is indicated by the symbol DD[ ], with the surface number on the magnification side of this spacing placed inside the brackets and entered in the D column. The Nd column shows the refractive index at the d-line of each component. The νd column shows the Abbe number of each component based on the d-line. The ED column shows the maximum effective diameter of each surface. On the left side of the "Sn" column, the rows of lenses corresponding to the LM lens LM, LA lens LA, and LB lens LB are marked with "LM," "LA," and "LB," respectively.

[0097] Table 2 shows the magnification ratio, absolute value of focal length, back focus at air-equivalent distance (shown as "back focus" in Table 2), maximum F-number, maximum full-field angle, and variable surface spacing during magnification, based on the d-line. Back focus at air-equivalent distance is the air-equivalent distance from the lens surface at the most reduction side of the imaging optical system to the display surface Sim. The [°] in the maximum full-field angle column indicates that the unit is degrees. In Table 2, the columns labeled "WIDE," "MIDDLE," and "TELE" show the values ​​for the wide-angle end, mid-focal length state, and telephoto end state, respectively.

[0098] In the basic lens data, the aspherical surface numbers are marked with an *, and the paraxial radius of curvature value is listed in the aspherical radius of curvature column. In Table 3, the Sn row shows the aspherical surface numbers, and the KA and Am (m = 3, 4, 5, 6, ..., 20) rows show the numerical values ​​of the aspherical coefficients for each aspherical surface. The numerical values ​​of the aspherical coefficients in Table 3, "E±n" (n: integer), are expressed as "×10 ±n KA and Am are aspherical coefficients in the aspherical formula given below. Zd=C×h 2 / {1+(1-KA×C 2 ×h 2 ) 1 / 2}+ΣAm×h m however, Zd: Aspheric depth (length of the perpendicular line drawn from a point on the aspheric surface at height h to a plane perpendicular to the optical axis Z where the vertex of the aspheric surface is in contact) h: Height (distance from optical axis Z to lens surface) C: Reciprocal of paraxial curvature radius KA, Am: aspherical coefficients In the aspherical formula, Σ means the summation over m.

[0099] The following tables and the aberration diagrams described later all show data normalized so that the maximum image height on the reduction-side image plane is 10. Furthermore, the values ​​in each of the tables shown below are rounded to a predetermined number of decimal places.

[0100] [Table 1A]

[0101] [Table 1B]

[0102] [Table 2]

[0103] [Table 3]

[0104] Figures 5 and 6 show aberration diagrams at a projection distance of 771.3 mm. In Figure 5, the upper row labeled "WIDE" shows aberrations at the wide-angle end, the middle row labeled "MIDDLE" shows aberrations at the intermediate focal length, and the lower row labeled "TELE" shows aberrations at the telephoto end. From left to right, Figure 5 shows spherical aberration, astigmatism, distortion, and lateral chromatic aberration. In the spherical aberration diagram, aberrations for the d-line, C-line, and F-line are shown with solid, long-dashed, and short-dashed lines, respectively. In the astigmatism diagram, aberrations for the d-line in the sagittal direction are shown with solid lines, and aberrations for the d-line in the tangential direction are shown with short-dashed lines. In the distortion diagram, aberrations for the d-line are shown with solid lines. In the lateral chromatic aberration diagram, aberrations for the C-line and F-line are shown with long-dashed and short-dashed lines, respectively. In the spherical aberration diagrams, the maximum F-number value in each state is shown after "FNo.=". In the other aberration diagrams in Figure 5, the maximum half angle of view value in each state is shown after "ω=".

[0105] In Figure 6, the left side labeled "WIDE" shows the lateral aberration at the wide-angle end, and the right side labeled "TELE" shows the lateral aberration at the telephoto end. Of the "WIDE" figures, the four figures in the left column show the tangential aberration, and the three figures in the right column show the sagittal aberration. In Figure 6, the half angle of view is shown after "ω=", indicating the lateral aberration at each angle of view. Aberrations at the d-line, C-line, F-line, and g-line are shown with a solid line, long-dashed line, short-dashed line, and dash-dot line, respectively. The same applies to the "TELE" figures.

[0106] Unless otherwise specified, the symbols, meanings, description methods, and illustration methods of each piece of data related to Example 1 above, as well as the fact that data is normalized so that the maximum image height on the reduction-side imaging plane is 10, are basically the same in the following examples, and therefore will not be described again below. The screen Scr is not shown in the cross-sectional views of the following examples.

[0107] [Example 2] FIG. 7 shows a cross-sectional view of the configuration and light beam of the imaging optical system of Example 2. The imaging optical system of Example 2 is a variable magnification optical system and is composed of, in order from the magnification side to the reduction side, a first optical system G1 and a second optical system G2. An intermediate image MI is formed between the first optical system G1 and the second optical system G2. The second optical system G2 is composed of, in order from the magnification side to the reduction side, a second-A lens group G2A, a second-B lens group G2B, a second-C lens group G2C, a second-D lens group G2D, and a second-E lens group G2E. When varying magnification from the wide-angle end to the telephoto end, the second-B lens group G2B, the second-C lens group G2C, and the second-D lens group G2D move along the optical axis Z while changing the spacing between adjacent lens groups, while all other lenses are fixed relative to the display surface Sim.

[0108] The first optical system G1 is composed of, in order from the enlargement side to the reduction side, lenses L1a to L1n. The secondA lens group G2A is composed of, in order from the enlargement side to the reduction side, lenses L2a to L2c. The secondB lens group G2B is composed of a lens L2d. The secondC lens group G2C is composed of a lens L2e. The secondD lens group G2D is composed of, in order from the enlargement side to the reduction side, an aperture stop St and lenses L2f to L2h. The secondE lens group G2E is composed of a lens L2i. The focus group is composed of lenses L1e to L1f.

[0109] The imaging optical system of Example 2 is shown in Tables 4A and 4B, the specifications and variable surface spacing during magnification are shown in Table 5, the aspherical coefficients are shown in Table 6, and the various aberration diagrams are shown in Figures 8 and 9. Each aberration diagram is for a projection distance of 753.3 mm.

[0110] [Table 4A]

[0111] [Table 4B]

[0112] [Table 5]

[0113] [Table 6]

[0114] [Example 3] FIG. 10 shows a cross-sectional view of the configuration and light beam of the imaging optical system of Example 3. The imaging optical system of Example 3 is a variable magnification optical system and comprises, in order from the magnification side to the reduction side, a first optical system G1 and a second optical system G2. An intermediate image MI is formed between the first optical system G1 and the second optical system G2. The second optical system G2 comprises, in order from the magnification side to the reduction side, a second-A lens group G2A, a second-B lens group G2B, a second-C lens group G2C, and a second-D lens group G2D. When varying magnification from the wide-angle end to the telephoto end, the second-B lens group G2B and the second-C lens group G2C move along the optical axis Z while changing the distance between them, while all other lenses are fixed relative to the display surface Sim.

[0115] The first optical system G1 is composed of, in order from the enlargement side to the reduction side, lenses L1a to L1m. The second-A lens group G2A is composed of, in order from the enlargement side to the reduction side, lenses L2a to L2d. The second-B lens group G2B is composed of a lens L2e. The second-C lens group G2C is composed of, in order from the enlargement side to the reduction side, an aperture stop St and lenses L2f to L2h. The second-D lens group G2D is composed of a lens L2i. The focus group is composed of lenses L1d to L1e.

[0116] For the imaging optical system of Example 3, basic lens data is shown in Tables 7A and 7B, specifications and variable surface spacing during magnification are shown in Table 8, aspherical coefficients are shown in Table 9, and various aberration diagrams are shown in Figures 11 and 12. Each aberration diagram is for a projection distance of 790.2.

[0117] [Table 7A]

[0118] [Table 7B]

[0119] [Table 8]

[0120] [Table 9]

[0121] [Example 4] FIG. 13 shows a cross-sectional view of the configuration and light beam of the imaging optical system of Example 4. The imaging optical system of Example 4 is a variable magnification optical system and comprises, in order from the magnification side to the reduction side, a first optical system G1 and a second optical system G2. An intermediate image MI is formed between the first optical system G1 and the second optical system G2. The second optical system G2 comprises, in order from the magnification side to the reduction side, a second-A lens group G2A, a second-B lens group G2B, a second-C lens group G2C, and a second-D lens group G2D. When varying magnification from the wide-angle end to the telephoto end, the second-B lens group G2B and the second-C lens group G2C move along the optical axis Z while changing the distance between them, and all other lenses are fixed relative to the display surface Sim.

[0122] The first optical system G1 is composed of, in order from the enlargement side to the reduction side, lenses L1a to L1l. The second-A lens group G2A is composed of, in order from the enlargement side to the reduction side, lenses L2a to L2e. The second-B lens group G2B is composed of a lens L2f. The second-C lens group G2C is composed of, in order from the enlargement side to the reduction side, an aperture stop St and lenses L2g to L2i. The second-D lens group G2D is composed of a lens L2j. The focus group is composed of lenses L1d to L1e.

[0123] For the imaging optical system of Example 4, basic lens data is shown in Tables 10A and 10B, specifications and variable surface spacing during magnification are shown in Table 11, aspherical coefficients are shown in Table 12, and aberration diagrams are shown in Figures 14 and 15. Each aberration diagram is for a projection distance of 790.2.

[0124] [Table 10A]

[0125] [Table 10B]

[0126] [Table 11]

[0127] [Table 12]

[0128] [Example 5] FIG. 16 shows a cross-sectional view of the configuration and light beam of the imaging optical system of Example 5. The imaging optical system of Example 5 is a variable magnification optical system, and is composed of, in order from the magnification side to the reduction side, a first optical system G1 and a second optical system G2. An intermediate image MI is formed between the first optical system G1 and the second optical system G2. The second optical system G2 is composed of, in order from the magnification side to the reduction side, a second-A lens group G2A, a second-B lens group G2B, a second-C lens group G2C, and a second-D lens group G2D. When varying magnification from the wide-angle end to the telephoto end, the second-B lens group G2B and the second-C lens group G2C move along the optical axis Z while changing the distance between them, and all other lenses are fixed relative to the display surface Sim.

[0129] The first optical system G1 is composed of, in order from the enlargement side to the reduction side, lenses L1a to L1m. The second-A lens group G2A is composed of, in order from the enlargement side to the reduction side, lenses L2a to L2d. The second-B lens group G2B is composed of a lens L2e. The second-C lens group G2C is composed of, in order from the enlargement side to the reduction side, an aperture stop St and lenses L2f to L2h. The second-D lens group G2D is composed of a lens L2i. The focus group is composed of lenses L1d to L1e.

[0130] For the imaging optical system of Example 5, basic lens data is shown in Tables 13A and 13B, specifications and variable surface spacing during magnification are shown in Table 14, aspherical coefficients are shown in Table 15, and various aberration diagrams are shown in Figures 17 and 18. Each aberration diagram is for a projection distance of 790.2.

[0131] [Table 13A]

[0132] [Table 13B]

[0133] [Table 14]

[0134] [Table 15]

[0135] [Example 6] FIG. 19 shows a cross-sectional view of the configuration and light beam of the imaging optical system of Example 6. The imaging optical system of Example 6 is a variable magnification optical system, and is composed of, in order from the magnification side to the reduction side, a first optical system G1 and a second optical system G2. An intermediate image MI is formed between the first optical system G1 and the second optical system G2. The second optical system G2 is composed of, in order from the magnification side to the reduction side, a second-A lens group G2A, a second-B lens group G2B, a second-C lens group G2C, and a second-D lens group G2D. When varying magnification from the wide-angle end to the telephoto end, the second-B lens group G2B and the second-C lens group G2C move along the optical axis Z while changing the distance between them, and all other lenses are fixed relative to the display surface Sim.

[0136] The first optical system G1 is composed of lenses L1a to L1m, in order from the enlargement side to the reduction side. The second-A lens group G2A is composed of lenses L2a to L2d, in order from the enlargement side to the reduction side. The second-B lens group G2B is composed of lens L2e and aperture stop St, in order from the enlargement side to the reduction side. The second-C lens group G2C is composed of lenses L2f to L2h, in order from the enlargement side to the reduction side. The second-D lens group G2D is composed of lens L2i. The imaging optical system of Example 6 has two focus groups that move with a varying distance between them during focusing. The focus group on the enlargement side is composed of lens L1d, and the focus group on the reduction side is composed of lens L1e.

[0137] For the imaging optical system of Example 6, basic lens data is shown in Tables 16A and 16B, specifications and variable surface spacing during magnification are shown in Table 17, aspherical coefficients are shown in Table 18, and each aberration diagram is shown in Figures 20 and 21. Each aberration diagram is for a projection distance of 614.1.

[0138] [Table 16A]

[0139] [Table 16B]

[0140] [Table 17]

[0141] [Table 18]

[0142] [Example 7] A cross-sectional view of the configuration of the imaging optical system of Example 7 and the light beam is shown in Figure 22. The imaging optical system of Example 7 is a fixed-focus optical system, and is composed of, in order from the enlargement side to the reduction side, a first optical system G1 and a second optical system G2. An intermediate image MI is formed between the first optical system G1 and the second optical system G2.

[0143] The first optical system G1 is composed of, in order from the enlargement side to the reduction side, lenses L1a to L1n. The second optical system G2 is composed of, in order from the enlargement side to the reduction side, lenses L2a to L2d, an aperture stop St, and lenses L2e to L2h. The focus group is composed of lenses L1e to L1f.

[0144] For the imaging optical system of Example 7, basic lens data is shown in Tables 19A and 19B, specifications are shown in Table 20, aspherical coefficients are shown in Table 21, and each aberration diagram is shown in Figures 23 and 24. Each aberration diagram is for a projection distance of 753.3 mm.

[0145] [Table 19A]

[0146] [Table 19B]

[0147] [Table 20]

[0148] [Table 21]

[0149] Table 22 shows the corresponding values ​​of conditional expressions (1) to (10) and the value of Ymax for the imaging optical systems of Examples 1 to 7. The corresponding values ​​of the Examples shown in Table 22 may be used as the upper or lower limits of the conditional expressions to set preferred ranges for the conditional expressions.

[0150] [Table 22]

[0151] The imaging optical systems of Examples 1 to 7 have a wide angle of view, with a total angle of view of 120 degrees or more at the wide-angle end. The imaging optical systems of Examples 1 to 7 realize optical systems with high resolution in which various aberrations are well corrected.

[0152] Next, a projection display device according to an embodiment of the present disclosure will be described. FIG. 25 is a schematic diagram of a projection display device according to an embodiment of the present disclosure. The projection display device 100 shown in FIG. 25 includes an imaging optical system 10 according to an embodiment of the present disclosure, a light source 15, and transmissive display elements 11a-11c as light valves that output optical images corresponding to the respective color lights. The projection display device 100 also includes dichroic mirrors 12 and 13 for color separation, a cross dichroic prism 14 for color synthesis, condenser lenses 16a-16c, and total reflection mirrors 18a-18c for deflecting the optical path. Note that FIG. 25 only shows the imaging optical system 10. An integrator is disposed between the light source 15 and the dichroic mirror 12, but is not shown in FIG. 25.

[0153] White light from light source 15 is separated into three colored light beams (green light, blue light, and red light) by dichroic mirrors 12 and 13, and then passes through condenser lenses 16a to 16c, where the colored light beams are incident on transmissive display elements 11a to 11c corresponding to the colored light beams and modulated there. After being color-synthesized by cross dichroic prism 14, the colored light beams are incident on imaging optical system 10. Imaging optical system 10 projects an optical image based on the modulated light by transmissive display elements 11a to 11c onto screen 105.

[0154] FIG. 26 is a schematic diagram of a projection display device according to another embodiment of the present disclosure. The projection display device 200 shown in FIG. 26 includes an imaging optical system 210 according to an embodiment of the present disclosure, a light source 215, and DMD (Digital Micromirror Device: registered trademark) elements 21a-21c as light valves that output optical images corresponding to the respective color lights. The projection display device 200 also includes TIR (Total Internal Reflection) prisms 24a-24c for color separation and color synthesis, and a polarization separation prism 25 that separates illumination light and projection light. Note that FIG. 26 only shows a schematic diagram of the imaging optical system 210. An integrator is disposed between the light source 215 and the polarization separation prism 25, but is not shown in FIG. 26.

[0155] White light from light source 215 is reflected by a reflective surface inside polarization splitter prism 25, and then separated into three colored light beams (green light, blue light, and red light) by TIR prisms 24a-24c. Each separated colored light beam enters and is modulated by the corresponding DMD elements 21a-21c, travels again in the opposite direction through TIR prisms 24a-24c, and is color-synthesized. Then, it passes through polarization splitter prism 25 and enters imaging optical system 210. Imaging optical system 210 projects an optical image based on the modulated light by DMD elements 21a-21c onto screen 205.

[0156] Fig. 27 is a schematic diagram of a projection display device according to yet another embodiment of the present disclosure. The projection display device 300 shown in Fig. 27 includes an imaging optical system 310 according to an embodiment of the present disclosure, a light source 315, reflective display elements 31a-31c as light valves corresponding to the respective colors of light, dichroic mirrors 32 and 33 for color separation, a cross dichroic prism 34 for color synthesis, a total reflection mirror 38 for optical path deflection, and polarization separation prisms 35a-35c. Note that Fig. 27 only shows the imaging optical system 310 in a simplified manner. An integrator is disposed between the light source 315 and the dichroic mirror 32, but is not shown in Fig. 27.

[0157] White light from light source 315 is separated into three colored light beams (green light, blue light, and red light) by dichroic mirrors 32 and 33. Each separated colored light beam passes through polarization separation prisms 35a to 35c, enters and is modulated by reflective display elements 31a to 31c corresponding to the colored light beam, and is then color-synthesized by cross dichroic prism 34 before entering imaging optical system 310. Imaging optical system 310 projects an optical image based on the modulated light by reflective display elements 31a to 31c onto screen 305.

[0158] Fig. 28 is a schematic diagram of a projection display device according to yet another embodiment of the present disclosure. The projection display device 400 shown in Fig. 28 includes an imaging optical system 46 according to an embodiment of the present disclosure, a light source 41, and a DMD element 44 as a light valve that outputs an optical image corresponding to each color light. The projection display device 400 also includes a color wheel 42, a light-guiding optical system 43, and a TIR prism 45. Note that Fig. 28 shows the imaging optical system 46 only in a simplified manner.

[0159] Color wheel 42 has three color filters (green, blue, and red) arranged on its circumference, and as color wheel 42 rotates, the filters of each color are inserted sequentially into the optical path. White light from light source 41 is time-divided into three colored light beams (green light, blue light, and red light) by entering the rotating color wheel 42. After time division, each colored light beam passes through light-guiding optical system 43 and TIR prism 45, then enters DMD element 44 and is modulated, and passes through TIR prism 45 again before entering imaging optical system 46. Imaging optical system 46 projects an optical image based on the modulated light by DMD element 44 onto screen 405.

[0160] 29 and 30 are external views of a camera 800, which is an imaging device according to an embodiment of the present disclosure. Fig. 29 shows a perspective view of the camera 800 as seen from the front side, and Fig. 30 shows a perspective view of the camera 800 as seen from the rear side. The camera 800 is a so-called mirrorless digital camera, to which an interchangeable lens 820 can be removably attached. The interchangeable lens 820 is configured to include an imaging optical system 801 according to an embodiment of the present disclosure housed in a lens barrel.

[0161] Camera 800 includes camera body 831. A shutter button 832 and a power button 833 are provided on the top surface of camera body 831. An operation unit 834, an operation unit 835, and a display unit 836 are provided on the back surface of camera body 831. Display unit 836 displays a captured image and an image within the angle of view before capture.

[0162] A photographic opening through which light from the subject to be photographed enters is provided in the center of the front of camera body 831, and a mount 837 is provided at a position corresponding to the photographic opening, and interchangeable lens 820 is attached to camera body 831 via mount 837.

[0163] An imaging element 838 is provided within the camera body 831. The imaging element 838 outputs an imaging signal corresponding to the subject image formed by the interchangeable lens 820. For example, a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) is used as the imaging element 838. A signal processing circuit (not shown), a recording medium (not shown), and the like are provided within the camera body 831. The signal processing circuit processes the imaging signal output from the imaging element 838 to generate an image. The recording medium is for recording the generated image. With the camera 800, it is possible to take a still image or a video by pressing the shutter button 832, and the image data obtained by this shooting is recorded on the recording medium.

[0164] Although the technology of the present disclosure has been described above using embodiments and examples, the technology of the present disclosure is not limited to the above embodiments and examples and various modifications are possible. The radius of curvature, surface spacing, refractive index, Abbe number, aspherical coefficient, etc. of each lens are not limited to the values ​​shown in the above examples and may take other values.

[0165] Furthermore, the projection display device according to the technology of the present disclosure is not limited to the above configuration. For example, the optical members and light valves used for light beam separation or light beam combination can be modified in various ways. The light valve is not limited to a configuration in which light from a light source is spatially modulated by an image display element and output as an optical image based on image data, but may be a configuration in which light output from a self-luminous image display element itself is output as an optical image based on image data. Examples of self-luminous image display elements include image display elements in which light-emitting elements such as LEDs (Light Emitting Diodes) or OLEDs (Organic Light Emitting Diodes) are two-dimensionally arranged.

[0166] Furthermore, the imaging device according to the technology of the present disclosure is not limited to the above configuration, but can take various forms, such as cameras other than mirrorless cameras, film cameras, video cameras, security cameras, and cinema cameras.

[0167] The following additional notes are provided regarding the above embodiments and examples. [Appendix 1] An imaging optical system that forms an intermediate image at a position conjugate with a reduction-side imaging surface and re-images the intermediate image on an enlargement-side imaging surface, The optical system comprises, in order from the magnification side to the reduction side along the optical path, a first optical system and a second optical system, the intermediate image is formed between the first optical system and the second optical system, a lens arranged adjacent to the reduction side of a longest lens interval, which is the longest interval among the intervals on the optical axis between lenses in the imaging optical system, is defined as an LA lens; The lens arranged adjacent to the reduction side of the LA lens is an LB lens, The maximum half angle of view on the magnification side is ωm, The radius of curvature of the surface on the enlargement side of the LA lens is RAf, The radius of curvature of the reduction-side surface of the LA lens is RAr, The radius of curvature of the enlargement side surface of the LB lens is RBf, When the imaging optical system is a variable magnification optical system, the longest lens spacing and ωm are values ​​at the wide-angle end, 1.73 <tanωm<5 (1) 0<(RAf+RAr) / (RAf-RAr)<1.5 (2) 1<(RAr+RBf) / (RAr-RBf)<10 (3) An imaging optical system that satisfies conditional expressions (1), (2), and (3) expressed as follows: [Appendix 2] The air equivalent distance of the longest lens spacing is defined as Dmax, The focal length of the imaging optical system is defined as f, When the imaging optical system is a variable magnification optical system, Dmax and f are values ​​at the wide-angle end, 10 <Dmax / |f|<45 (4) 10. The imaging optical system according to claim 1, which satisfies conditional expression (4) shown below. [Appendix 3] The distance on the optical axis between the LA lens and the LB lens is defined as DAB, The maximum image height on the reduction-side imaging surface is defined as Ymax, When the imaging optical system is a variable magnification optical system, DAB and Ymax are values ​​at the wide-angle end, 0.1 <DAB / Ymax<1.5 (5) 10. The imaging optical system according to claim 1, which satisfies conditional expression (5) shown below. [Appendix 4] The refractive index of the LA lens at the d line is defined as NA, When the refractive index of the LB lens at the d line is NB, 1 <NA / NB<1.3 (6) 4. The imaging optical system according to claim 1, which satisfies conditional expression (6) below. [Appendix 5] 5. The imaging optical system according to claim 1, wherein the LA lens and the LB lens are disposed within the second optical system. [Appendix 6] 6. The imaging optical system according to claim 1, wherein the LB lens is cemented to a lens disposed adjacent to the reduction side of the LB lens. [Appendix 7] If the lens closest to the intermediate image on the optical axis is the LM lens, 7. The imaging optical system according to claim 1, wherein the LM lens is a positive lens. [Appendix 8] 8. The imaging optical system according to claim 7, wherein the LM lens is disposed adjacent to the enlarged side of the longest lens spacing. [Appendix 9] 9. The imaging optical system according to claim 1, wherein a first optical path deflection member that bends the optical path is disposed within the longest lens interval. [Appendix 10] a distance on the optical axis from the first optical path deflector to the lens surface of the second optical system on the most reduction side is defined as DR; The maximum image height on the reduction-side imaging surface is defined as Ymax, When the imaging optical system is a variable magnification optical system, DR and Ymax are values ​​at the wide-angle end, 8 <DR / Ymax<26 (7) 10. The imaging optical system according to claim 9, which satisfies conditional expression (7) shown below. [Appendix 11] 11. The imaging optical system according to claim 1, wherein a second optical path deflection member that bends the optical path is disposed within the first optical system. [Appendix 12] a distance on the optical axis from the first optical path deflection member to the second optical path deflection member is defined as DMr12; The maximum image height on the reduction-side imaging surface is defined as Ymax, When the imaging optical system is a variable magnification optical system, DMr12 and Ymax are the values ​​at the wide-angle end, 8 <DMr12 / Ymax<30 (8) 12. The imaging optical system according to claim 11, which satisfies conditional expression (8) expressed as follows: [Appendix 13] the imaging optical system is a variable magnification optical system, 13. The imaging optical system according to claim 1, wherein, when a group whose distance in the optical axis direction from an adjacent group changes during magnification is defined as one lens group, the second optical system includes two or more lens groups that move during magnification. [Appendix 14] 14. The imaging optical system according to claim 13, wherein the number of lens groups included in the second optical system that move during magnification variation is two. [Appendix 15] The focal length of the lens group that moves the maximum amount when changing magnification from the wide-angle end to the telephoto end is defined as fz. When the focal length of the imaging optical system at the wide-angle end is fw, 10 <fz / |fw|<30 (9) 15. The imaging optical system according to claim 13, which satisfies conditional expression (9) shown below. [Appendix 16] 16. The imaging optical system according to claim 1, wherein the lens surface on the magnification side of the lens closest to the magnification side of the first optical system is an aspheric surface that faces a concave surface toward the magnification side in a paraxial region and has an inflection point where the concave-convex shape changes midway from on the optical axis to the periphery. [Appendix 17] 17. The imaging optical system according to claim 1, wherein the reduction-side lens surface of the most enlargement-side lens in the first optical system is an aspheric surface that faces a convex surface toward the reduction side in a paraxial region and has an inflection point where the concave-convex shape changes midway from on the optical axis to the periphery. [Appendix 18] 18. The imaging optical system according to any one of claims 1 to 17, wherein the reduction side is telecentric. [Appendix 19] A projection display device comprising the imaging optical system according to any one of Supplementary Note 1 to Supplementary Note 18. [Appendix 20] An imaging device comprising the imaging optical system according to any one of Supplementary Note 1 to Supplementary Note 18. [Explanation of symbols]

[0168] 10 Imaging optical system 11a to 11c Transmissive display element 12 Dichroic mirror 13 Dichroic mirror 14 Cross dichroic prism 15 light source 16a~16c Condenser Lens 18a~18c Total reflection mirror 21a~21c DMD elements 24a~24c TIR Prism 25 Polarization separation prism 31a to 31c reflective display elements 32 Dichroic mirror 33 Dichroic mirror 34 Cross Dichroic Prism 35a~35c Polarization separation prism 38 Total Reflection Mirror 41 Light source 42 Color Wheel 43 Light guiding optical system 44 DMD elements 45 TIR Prism 46 Imaging Optical System 100 Projection display device 105 screens 200 Projection display device 205 screens 210 Imaging Optical System 215 Light source 300 Projection display device 305 screens 310 Imaging Optical System 315 Light source 400 Projection display device 405 screens 800 cameras 801 Imaging Optical System 820 Interchangeable Lens 831 Camera Body 832 shutter button 833 Power button 834 Operation section 835 Operation section 836 Display section 837 Mount 838 Image sensor DAB distance Dmax air equivalent distance DMr12 distance DR distance G1 1st optical system G1r 1st optical system G2 2nd optical system G2A 2A lens group G2B 2B lens group G2C 2C lens group G2D 2nd lens group G2E 2E lens group G2r 2nd optical system L1a~L2j lenses LA LA Lens LB LB lens LM LM lens MI intermediate image Mr1 Mirror Mr2 Mirror PP optical components Scr Screen Sim display surface St aperture stop Ymax Maximum image height Z optical axis ωm Maximum half angle of view

Claims

1. An imaging optical system that forms an intermediate image at a position conjugate with a reduction-side imaging surface and re-images the intermediate image on an enlargement-side imaging surface, The optical system comprises, in order from the magnification side to the reduction side along the optical path, a first optical system and a second optical system, the intermediate image is formed between the first optical system and the second optical system, a lens disposed adjacent to the reduction side of a longest lens interval, which is the longest interval on the optical axis between lenses in the imaging optical system, is defined as an LA lens; a lens arranged adjacent to the reduction side of the LA lens is an LB lens; The maximum half angle of view on the enlargement side is ωm, The radius of curvature of the enlargement side surface of the LA lens is RAf, The radius of curvature of the reduction-side surface of the LA lens is RAr, The radius of curvature of the enlargement side surface of the LB lens is RBf, When the imaging optical system is a variable magnification optical system, the longest lens spacing and ωm are values ​​at the wide-angle end, 1.73<tanωm<5 (1) 0<(RAf+RAr) / (RAf-RAr)<1.5 (2) 1<(RAr+RBf) / (RAr-RBf)<10 (3) An imaging optical system that satisfies conditional expressions (1), (2), and (3) expressed by the following formulas.

2. The air equivalent distance of the longest lens spacing is Dmax, The focal length of the imaging optical system is defined as f, When the imaging optical system is a variable magnification optical system, Dmax and f are values ​​at the wide-angle end, 10<Dmax / |f|<45 (4) 2. The imaging optical system according to claim 1, which satisfies conditional expression (4) expressed as follows:

3. The distance on the optical axis between the LA lens and the LB lens is defined as DAB, The maximum image height on the reduction-side imaging surface is defined as Ymax, When the imaging optical system is a variable magnification optical system, DAB and Ymax are values ​​at the wide-angle end, 0.1<DAB / Ymax<1.5 (5) 2. The imaging optical system according to claim 1, which satisfies conditional expression (5) expressed as follows:

4. The refractive index of the LA lens at the d line is defined as NA, When the refractive index of the LB lens at the d line is NB, 1<NA / NB<1.3 (6) 2. The imaging optical system according to claim 1, which satisfies conditional expression (6) expressed as follows:

5. The imaging optical system according to claim 1 , wherein the LA lens and the LB lens are disposed within the second optical system.

6. 2. The imaging optical system according to claim 1, wherein the LB lens is cemented to a lens disposed adjacent to the reduction side of the LB lens.

7. If the lens closest to the intermediate image on the optical axis is an LM lens, 2. The imaging optical system according to claim 1, wherein the LM lens is a positive lens.

8. 8. The imaging optical system according to claim 7, wherein the LM lens is disposed adjacent to the enlarged side of the longest lens spacing.

9. 2. The imaging optical system according to claim 1, further comprising a first optical path deflecting member for bending the optical path, disposed within the longest lens interval.

10. a distance on the optical axis from the first optical path deflector to the lens surface of the second optical system on the most reduction side is defined as DR; The maximum image height on the reduction-side imaging surface is defined as Ymax, When the imaging optical system is a variable magnification optical system, DR and Ymax are values ​​at the wide-angle end, 8<DR / Ymax<26 (7) 10. The imaging optical system according to claim 9, which satisfies conditional expression (7) expressed as follows:

11. 10. The imaging optical system according to claim 9, wherein a second optical path deflecting member for bending the optical path is disposed within the first optical system.

12. a distance on the optical axis from the first optical path deflection member to the second optical path deflection member is defined as DMr12; The maximum image height on the reduction-side imaging surface is defined as Ymax, When the imaging optical system is a variable magnification optical system, DMr12 and Ymax are values ​​at the wide-angle end, 8<DMr12 / Ymax<30 (8) 12. The imaging optical system according to claim 11, which satisfies conditional expression (8) expressed as follows:

13. the imaging optical system is a variable magnification optical system, 2. The imaging optical system according to claim 1, wherein when a group whose spacing in the optical axis direction from an adjacent group changes during magnification is defined as one lens group, the second optical system includes two or more lens groups that move during magnification.

14. 14. The imaging optical system according to claim 13, wherein the number of lens groups included in the second optical system that move during magnification variation is two.

15. The focal length of the lens group at which the amount of movement during magnification change from the wide-angle end to the telephoto end is maximum is defined as fz, When the focal length of the imaging optical system at the wide-angle end is fw, 10<fz / |fw|<30 (9) 14. The imaging optical system according to claim 13, which satisfies conditional expression (9) expressed as follows:

16. 2. The imaging optical system according to claim 1, wherein the lens surface on the magnification side of the lens closest to the magnification side of the first optical system is an aspheric surface that faces a concave surface toward the magnification side in the paraxial region and has an inflection point where the concave and convex shapes change midway as one moves from the optical axis to the periphery.

17. 2. The imaging optical system according to claim 1, wherein the reduction-side lens surface of the most magnifying lens in the first optical system is an aspheric surface that faces the convex surface toward the reduction side in the paraxial region and has an inflection point where the concave-convex shape changes midway as one moves from the optical axis to the periphery.

18. 2. The imaging optical system according to claim 1, wherein the reduction side is telecentric.

19. A projection display device comprising the imaging optical system according to any one of claims 1 to 18.

20. An imaging device comprising the imaging optical system according to any one of claims 1 to 18.

Images