Optical system and image capturing device

Abstract

To provide a compact optical system with no parallax.SOLUTION: An optical system (OS1) provided herein comprises a first light path splitting means (M1) for splitting light from a front group (FG) into a first light path (TP) and a second light path (RP), and partial optical systems (CL1, CL2) respectively disposed on the first light path and the second light path. First light passing through the first light path and second light passing through the second light path form images with different lateral magnifications.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an optical system and an imaging device. [Background technology]

[0002] In recent years, compact imaging devices equipped with compound optical systems, such as smartphones, have become widespread. The use of compound optical systems enables imaging that is difficult with a single optical system, such as obtaining multiple focal lengths simultaneously despite the device being thin, and acquiring distance information to adjust the focus position after shooting.

[0003] Patent document 1 discloses a compound eye imaging device that embeds an image obtained by an imaging element corresponding to a lens with a long focal length into a part of an image obtained by an imaging element corresponding to a lens with a short focal length. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-303694 Summary of the Invention [Problem to be solved by the invention]

[0005] In the compound eye imaging device disclosed in Patent Document 1, the optical axes of the lenses in the compound eye optical system do not coincide on the object side, so parallax occurs between the images captured at each focal length. Therefore, when a long focal length image is inserted into a short focal length image, images with different viewpoints are combined, and the central viewpoint switches in the intermediate zoom range, creating an unnatural feeling.

[0006] Furthermore, even in areas that are commonly captured in both the short-focus image and the long-focus image, there is an occlusion that is captured only in each image, causing a breakdown at the joints when the images are combined. In particular, if a compound eye optical system with a large individual image circle is placed in an imaging system with a large sensor, the parallax increases and the system becomes larger.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a small-sized optical system and imaging device that are free from parallax. [Means for solving the problem]

[0008] An optical system according to one aspect of the present invention comprises an optical path branching means that branches light from a front group into a first optical path and a second optical path, and a partial optical system that is arranged on the first optical path or the second optical path, wherein a first light that passes through the first optical path and a second light that passes through the second optical path are imaged at different lateral magnifications, and the partial optical system includes a biconcave lens.

[0009] Other objects and features of the present invention are illustrated in the following examples. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a small-sized optical system and an imaging device that are free from parallax. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a cross-sectional view of an optical system according to the first embodiment. [Figure 2] 4A and 4B are longitudinal aberration diagrams of the optical system in Example 1 when focused at infinity. [Figure 3] FIG. 10 is a cross-sectional view of an optical system according to a second embodiment. [Figure 4] FIG. 10 is a longitudinal aberration diagram of the optical system according to the second embodiment when focused at infinity. [Figure 5] FIG. 10 is a cross-sectional view of an optical system according to a third embodiment. [Figure 6] FIG. 10 is a longitudinal aberration diagram of the optical system according to Example 3 when focused at infinity. [Figure 7] FIG. 10 is a cross-sectional view of an optical system according to a fourth embodiment. [Figure 8] FIG. 10 is a longitudinal aberration diagram of the optical system of Example 4 when focused at infinity. [Figure 9] FIG. 10 is a diagram illustrating the configuration of an optical system in the fifth and sixth embodiments. [Figure 10] FIG. 4 is an explanatory diagram of the inclination angle of the reflecting surface in each example. [Figure 11] 1 is a schematic diagram of an imaging device including an optical system according to each embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0013] 1, 3, 5, and 7 are cross-sectional views of the optical systems of Examples 1 to 4 when focused at infinity. The optical systems of the examples are imaging optical systems used in imaging devices such as digital video cameras, digital still cameras, and silver halide film cameras. In each cross-sectional view, the left side is the object side (front) and the right side is the image side (rear). Note that, when photographing, the paper surface direction of each cross-sectional view does not necessarily have to be perpendicular to the screen.

[0014] 2, 4, 6, and 8 are longitudinal aberration diagrams of the optical systems of Examples 1 to 4, respectively. In each aberration diagram, (A) shows the longitudinal aberration diagram for the transmitted light path TP when focused at infinity, and (B) shows the longitudinal aberration diagram for the reflected light path RP when focused at infinity. In the spherical aberration diagram, Fno is the F-number, and in the spherical aberration diagram, the amount of spherical aberration for each of the d-line (wavelength 587.6 nm) and g-line (wavelength 435.8 nm) is shown. In the astigmatism diagram, S shows the amount of astigmatism in the sagittal image plane, and M shows the amount of astigmatism in the meridional image plane. In the distortion diagram, the amount of distortion for the d-line is shown. In the chromatic aberration diagram, the amount of chromatic aberration for the g-line is shown. ω is the half angle of view (degrees).

[0015] In the optical system of each embodiment, FP is the front group, M1 and M2 are the first optical element and the second optical element, respectively, and CL1 and CL2 are the first converter and the second converter, respectively (the second converter CL2 does not exist in FIG. 7.) In each embodiment, the front group FG is configured to be integrated with or replaceable with the optical system having the first optical element M1, the second optical element M2, the first converter CL1, and the second converter CL2.

[0016] IC1 and IC2 are the first and second image circles, respectively. When used as the imaging optical system for a video camera or digital still camera, the imaging surface of an imaging element (photoelectric conversion element) such as a CCD sensor or CMOS sensor, or the photosensitive surface of the film in a silver halide film camera, is located on each image circle.

[0017] The first optical element M1 is a half mirror (optical path branching means) that branches the light from the front group FP into a transmitted optical path (first optical path) TP and a reflected optical path (second optical path) RP. However, each embodiment is not limited to this, and the first optical element M1 may be configured using other optical path branching means, such as one that uses polarized light to branch the optical path, instead of a half mirror.

[0018] The first converter CL1 and the second converter CL2 are partial optical systems arranged on the transmitted optical path TP (on the first optical path) or the reflected optical path RP (on the second optical path). They are the first partial optical system and the second partial optical system. As shown in FIGS. 1, 3, and 5, in the optical systems of Examples 1 to 3, the partial optical system has a first converter (first partial optical system) CL1 arranged on the reflected optical path RP and a second converter (second partial optical system) CL2 arranged on the transmitted optical path TP. On the other hand, as shown in FIG. 7, in the optical system of Example 4, the partial optical system has only the first converter (first partial optical system) CL1 arranged on the reflected optical path RP. In addition, in the optical systems of each Example, light passing through the transmitted optical path TP (first light) and light passing through the reflected optical path RP (second light) are imaged in the first image circle IC1 and the second image circle IC2, respectively, with different lateral magnifications (imaging magnifications). That is, in the optical systems of the respective embodiments, the optical paths after the transmitted optical path TP have different lateral magnifications (imaging magnifications). In other words, images are formed so that the focal lengths of the light passing through the transmitted optical path TP and the light passing through the reflected optical path RP are different.

[0019] By splitting the common light incident on the first optical element M1 from the object side into reflected light and transmitted light by the optical element M1, the optical path can be branched without generating parallax. Then, by forming images of each optical path at different imaging magnifications for each image circle, multiple focal lengths can be acquired. This allows multiple focal lengths to be acquired simultaneously without parallax, making it easy to generate images in the middle range from multiple focal lengths. Furthermore, a front group FG is located closer to the object than the first optical element M1, allowing the use of common light. Therefore, compared to a typical compound eye optical system, the front group FG is integrated, enabling a smaller size. With the above configuration, each embodiment can realize a compact optical system (compound eye optical system) without parallax.

[0020] Preferably, the first converter CL1 is placed on the reflected light path RP to increase the absolute value of the lateral magnification (focal length). By placing the first converter CL1, which increases the lateral magnification, the focal length of the first converter CL1 is negative, causing the on-axis light beam to diverge and the optical path to become longer. If the first converter CL1 were placed on the transmitted light path TP, the length (depth) from the surface of the first converter CL1 closest to the object to the image plane would be longer, resulting in a larger size. Therefore, by placing the first converter CL1 on the reflected light path RP, the space perpendicular to the transmitted light path TP is utilized, shortening the depth and making the lens more compact.

[0021] Preferably, the second converter CL2 is disposed on the transmitted light path TP and reduces the absolute value of the lateral magnification (focal length). The second converter CL2, which reduces the focal length, has a positive focal length, so it converges the axial light beam and shortens the optical path. Therefore, by disposing the second converter CL2 on the transmitted light path TP, the length (depth) from the surface of the second converter CL2 closest to the object to the image plane is shortened, resulting in a compact design.

[0022] Preferably, the optical systems of each embodiment have a common front group FG having refractive power that is located closer to the object than the first optical element M1. By providing a common front group FG having refractive power, the refractive power can be shared with the optical system located closer to the image than the first optical element M1, making it easier to correct aberrations.

[0023] Preferably, the optical system of each embodiment includes a second optical element (reflecting means) M2 on the reflected optical path RP, which further reflects the light reflected by the first optical element M1. Furthermore, the optical axes of the transmitted optical path TP and the reflected optical path RP are substantially parallel, and the first image circle IC1 of the light (first light) passing through the transmitted optical path TP and the second image circle IC2 of the light (second light) passing through the reflected optical path RP are formed on substantially the same plane. By forming the first image circle IC1 and the second image circle IC2 on substantially the same plane, an image of a compound eye can be captured on a single sensor. This allows, for example, an existing single-sensor camera body to capture an image of a compound eye, making it possible to configure a simple and compact optical system.

[0024] Here, "substantially parallel" means that the angle between the optical axis of the transmitted light path TP and the optical axis of the reflected light path RP is 10 degrees or less. Furthermore, "substantially on the same plane" means that the deviation in the imaging positions between the centers of the first image circle IC1 and the second image circle IC2 is 3% or less of the radius of the image circle size. A deviation greater than this would undesirably blur one of the images. More preferably, the angle between the optical axis of the transmitted light path TP and the optical axis of the reflected light path RP is 1 degree or less, and the deviation in the imaging positions of the centers of the image circles is 1% or less of the radius of the image circle size. This allows high-quality compound-eye images to be captured on a single sensor.

[0025] Preferably, as shown in Figure 5, an element CU is provided between the transmitted light path TP and the reflected light path RP to prevent interference between the first image circle IC1 and the second image circle IC2. Enlarging the image circles for both eyes creates areas of interference, which is undesirable as it results in areas of double images. Therefore, by placing a member CU, such as an anodized resin member (resin sheet), between the first image circle IC1 and the second image circle IC2, interference can be effectively prevented.

[0026] Preferably, the optical system of each embodiment satisfies at least one of the following conditional expressions (1) to (6).

[0027] 1.10<βc1<3.00 (1) 0.30<βc2<0.85 (2) 1.20 <Dc1 / Lc1<3.50 ···(3) 0.60 <Dc2 / Lc2<2.50 ···(4) 1.50 <Z<4.00 ···(5) 0.01 <T / R<0.50 ···(6) Here, βc1 is the lateral magnification (focal length) of the first converter CL, and βc2 is the lateral magnification (focal length) of the second converter CL2. Dc1 is the distance on the optical axis from the most image-side point of the front group FG to the most object-side point of the first converter CL1. Lc1 is the distance from the most object-side point of the first converter CL1 to the most image-side point. Dc2 is the distance on the optical axis from the most image-side point of the front group FG to the most object-side point of the second converter CL2. Lc2 is the distance from the most object-side point of the second converter CL2 to the most image-side point. Z is the ratio of the lateral magnification of light passing through the reflected optical path RP to the lateral magnification of light passing through the transmitted optical path TP. T is the amount of light transmitted by the first optical element M1, and R is the amount of light reflected by the first optical element M1.

[0028] Next, the technical meaning of each conditional expression will be explained. Conditional expression (1) represents the lateral magnification (imaging magnification) of the first converter CL1. If the upper limit of conditional expression (1) is exceeded, the lateral magnification becomes too large, which makes the refractive power of the first converter CL1 too strong and makes aberration correction difficult. On the other hand, if the lower limit of conditional expression (1) is exceeded, the lateral magnification becomes too small and the zoom ratio of the compound eye (the ratio of the focal lengths of the reflected light path RP and the transmitted light path TP) becomes too small, approaching 1, which is undesirable.

[0029] Conditional expression (2) represents the lateral magnification of the second converter CL2. Exceeding the upper limit of conditional expression (2) undesirably increases the lateral magnification too much, causing the zoom ratio of the compound eye (the ratio of the focal lengths of the reflected light path RP and the transmitted light path TP) to approach 1 and become too small. On the other hand, exceeding the lower limit of conditional expression (2) causes the lateral magnification to become too small, causing the refractive power of the converter CL2 to become too strong, making aberration correction difficult.

[0030] Conditional expression (3) represents the ratio of the distance on the optical axis from the most image-side part of the front group FG to the most object-side part of the first converter CL1 to the distance from the most object-side part of the first converter CL1 to the most image-side part. Exceeding the upper limit of conditional expression (3) results in an excessively large distance on the optical axis from the most image-side part of the front group FG to the most object-side part of the first converter CL1, resulting in an increase in size. On the other hand, exceeding the lower limit of conditional expression (3) results in an excessively small distance on the optical axis from the most image-side part of the front group FG to the most object-side part of the first converter CL1, making it difficult to position the first optical element M1 there.

[0031] Conditional expression (4) represents the ratio of the distance on the optical axis from the most image-side part of the front group FG to the most object-side part of the second converter CL2 to the distance from the most object-side part of the second converter CL2 to the most image-side part. Exceeding the upper limit of conditional expression (4) results in an excessively large distance on the optical axis from the most image-side part of the front group FL to the most object-side part of the second converter CL2, resulting in an increase in size. On the other hand, exceeding the lower limit of conditional expression (4) results in an excessively small distance on the optical axis from the most image-side part of the front group FL to the most object-side part of the second converter CL2, making it difficult to position the first optical element M1 there.

[0032] Conditional formula (5) expresses the ratio of the lateral magnification (focal length) of light passing through the reflected optical path RP to the lateral magnification (focal length) of light passing through the transmitted optical path TP. If the upper limit of conditional formula (5) is exceeded, in order to increase the zoom ratio, it is necessary to increase the lateral magnification of the first converter CL1 (telephoto side) or decrease the lateral magnification of the second converter CL2 (wide-angle side). In other words, in either case, the refractive power of each converter must be increased, making aberration correction difficult. On the other hand, if the lower limit of conditional formula (5) is exceeded, the zoom ratio of the compound eye (the ratio of the focal lengths of the reflected optical path RP and the transmitted optical path TP) becomes too small, approaching 1, which is undesirable.

[0033] Conditional expression (6) represents the ratio of the amount of light transmitted through the first optical element M1 to the amount of light reflected by the first optical element M1. Here, the amount of light is the amount of light at the center of the first optical element M1. Placing a magnifying optical system on the reflected light path results in a telephoto setting, and the F-number becomes larger (darker). For this reason, allocating a larger amount of light on the reflected side makes it possible to ensure a T-number (10 × F-number / √light amount (%)) on the telephoto side. If the upper limit of conditional expression (6) is exceeded, the T-number on the telephoto side becomes too dark, which is undesirable. On the other hand, if the lower limit of conditional expression (6) is exceeded, the T-number on the wide-angle side after passing through the transmitted light path TP becomes too dark, which is undesirable.

[0034] More preferably, at least one of the numerical ranges of the conditional expressions (1) to (6) is set as in the following conditional expressions (1a) to (6a).

[0035] 1.20<βc1<2.80 (1a) 0.40<βc2<0.75 (2a) 1.40 <Dc1 / Lc1<2.90 ···(3a) 0.75 <Dc2 / Lc2<2.10 ···(4a) 1.90 <Z<3.75 ···(5a) 0.05 <T / R<0.48 ···(6a) It is more preferable that at least one of the numerical ranges of the conditional expressions (1a) to (6a) is set as in the following conditional expressions (1b) to (6b).

[0036] 1.40<βc1<2.60 (1b) 0.50<βc2<0.70 (2b) 1.60 <Dc1 / Lc1<2.50 ···(3b) 0.90 <Dc2 / Lc2<1.70 ···(4b) 2.40 <Z<3.50 ···(5b) 0.09 <T / R<0.46 ···(6b) With the above configuration, a small optical system without parallax can be realized. Next, the characteristics of the optical systems of Examples 1 to 6 will be described. [Example]

[0037] First, with reference to FIG. 1, an optical system according to a first embodiment of the present invention will be described. Light passing through a common front group FG is split into a transmitted light path TP and a reflected light path RP by a first optical element M1. A wide-angle second converter CL2 is disposed on the transmitted light path TP, and a telephoto first converter CL1 is disposed on the reflected light path RP. This allows images to be captured simultaneously at multiple focal lengths without parallax. A second optical element M2 is disposed on the reflected light path RP, so that the optical axes of the transmitted light path TP and the reflected light path RP are aligned substantially parallel, and the first image circle IC1 and the second image circle IC2 are formed on substantially the same plane. This allows, for example, images of an object to be captured at multiple focal lengths on a single sensor, thereby enabling the optical system to be made more compact.

[0038] The first converter CL1 has two cemented convex-concave lenses. The second converter CL2 has three cemented convex-concave lenses. By using multiple cemented lenses, each converter can effectively correct chromatic aberration while minimizing the number of interfaces between the air and the lens (reducing reflectivity through cemented surfaces) and reducing ghosting caused by reflections between lens surfaces or between the sensor and the lens surface. [Example]

[0039] Next, an optical system according to a second embodiment of the present invention will be described with reference to Fig. 3. Note that from this embodiment onwards, technical explanations that overlap with those of the first embodiment will be omitted. With respect to the second converter CL2, a negative lens L2 having a larger absolute value of refractive power than that of the first embodiment is disposed as the second lens counting from the object side. This reduces the absolute value of the Petzval sum, making it possible to further reduce the curvature of field. [Example]

[0040] Next, an optical system according to a third embodiment of the present invention will be described with reference to Fig. 5. In this embodiment, an element CU is disposed between the first image circle IC1 and the second image circle IC2 to prevent interference between light on the transmitted light path TP and light on the reflected light path RP. The element CU is made of, for example, an anodized resin material or flocked paper, and cuts (reduces) the light incident on each image circle. [Example]

[0041] Next, an optical system according to a fourth embodiment of the present invention will be described with reference to Fig. 7. In this embodiment, there is no lens with refractive power on the transmitted light path TP, which is closer to the image than the first optical element M1, and the focal length of the common front group FG is extended by the first converter CL1 on the reflected light path RP. This makes it possible to reduce ghost images incident on the wide-angle side. [Example]

[0042] Next, an optical system according to a fifth embodiment of the present invention will be described with reference to FIG. 9(A). FIG. 9(A) is a diagram illustrating the configuration of the optical system according to this embodiment. Light from a common main lens (front group) passes through a first optical element (optical path branching means) M1, where the light is branched into a transmitted optical path and a reflected optical path, and then split into images for the wide-angle side and the telephoto side. The optical system according to this embodiment has a configuration in which the orientation of the image plane (image circle) differs between the wide-angle side and the telephoto side. With this configuration, the second optical element M2 is not necessary. This makes it possible to reduce the space required for the optical path branching means, thereby reducing the overall volume of the optical system and enabling further miniaturization. [Example]

[0043] An optical system according to a sixth embodiment of the present invention will now be described with reference to FIG. 9B. FIG. 9B is a structural diagram of the optical system of this embodiment. Light from a common interchangeable lens (front group FG) passes through a first optical element (first optical path branching means) M1, where the light is branched into a transmitted optical path TP and a reflected optical path RP. A second optical element (second optical path branching means) M2 further branches the reflected optical path RP into a first reflected optical path RP1 and a second reflected optical path RP2, and a third optical element (reflecting means) M3 changes the optical path direction of the second reflected optical path RP2. This configuration splits the light from the interchangeable lens (front group FG) into three substantially parallel optical paths. This embodiment can achieve a triplet configuration, enabling a larger zoom ratio than the twin-lens configurations of the previous embodiments. In this embodiment, the interchangeable lens (front group FG) is interchangeable, and the focal length at which the image is captured changes depending on the interchangeable lens.

[0044] Numerical Examples 1 to 4 corresponding to Examples 1 to 4, respectively, are shown below. In the surface data of each numerical example, r represents the radius of curvature of each optical surface, and d (mm) represents the axial distance (distance on the optical axis) between the mth surface and the (m+1)th surface. Here, m is the surface number counted from the light incident side. Furthermore, nd represents the refractive index of each optical member with respect to the d-line, and vd represents the Abbe number of the optical member with the d-line as the reference. The Abbe number vd is given by the following equation, where Nd, NF, and NC are the refractive indices at the d-line (587.6 nm), F-line (486.1 nm), and C-line (656.3 nm) of the Fraunhofer lines. νd=(Nd-1) / (NF-NC) It is expressed as:

[0045] In each numerical example, d, focal length (mm), F-number, and half angle of view (degrees) are all values ​​when the optical system of each example is focused on an object at infinity (when focused at infinity). "Back focus" is the distance on the optical axis from the final lens surface (the lens surface closest to the image) to the paraxial image plane, expressed as an air-equivalent length. "Total lens length" is the distance on the optical axis from the forefront lens surface (the lens surface closest to the object) to the final lens surface plus the back focus. "Lens group" is not limited to cases where it is composed of multiple lenses, but also includes cases where it is composed of a single lens.

[0046] Furthermore, if the optical surface is aspherical, an "*" is added to the right of the surface number. The aspherical shape is expressed by the following equation, where x is the displacement from the vertex of the surface in the optical axis direction, h is the height from the optical axis in a direction perpendicular to the optical axis, R is the paraxial radius of curvature, k is the conic constant, and A4, A6, A8, and A10 are the aspherical coefficients of each order.

[0047]

number

[0048] In addition, "e±XX" in each aspherical coefficient is "×10 ±XX " means.

[0049] Here, the definition of θ in each numerical example will be described with reference to Fig. 10. Fig. 10 is an explanatory diagram of the tilt angle (tilt angle θ with respect to the reference axis) of the reflecting surface (first optical element M1). At the position where the reference axis passing through the center of the lens intersects with the reflecting surface, the angle formed by the reference axis and a line perpendicular to the reflecting surface is defined as the tilt angle θ with respect to the reference axis. With respect to the reference axis that is closer to the object than the reflecting surface (through which light passes first), a clockwise direction is defined as positive. In this case, the absolute value of the angle formed by the reference axis connecting the front group FG and the reflecting surface and the reference axis connecting the reflecting surface and the side of the rear group that is closest to the object is equivalent to twice the tilt angle θ.

[0050] (Numerical Example 1) Unit: mm Surface Data Surface number rd nd νd Effective diameter 1 47.394 3.52 1.49700 81.5 22.50 2 -512.795 22.35 22.17 3 256.616 2.03 1.43387 95.1 16.19 4 -135.769 0.20 15.85 5 20.673 3.13 1.49700 81.5 15.20 6 -206.870 0.72 14.44 7 -66.965 0.70 1.60092 48.0 14.06 8 10.677 0.51 12.81 9 10.927 4.30 1.59282 68.6 12.94 10 -196.266 0.68 12.15 11 -59.338 0.70 1.77250 49.6 11.84 12 19.908 4.48 11.36 13 (Aperture) ∞ 1.58 11.31 14 -25.018 2.88 1.84777 30.9 11.30 Below CL1 15 -16.832 15.00 11.21 16 13.954 3.67 1.78897 28.5 13.15 17 -974.918 1.20 2.05090 26.9 12.62 18 13.290 4.79 12.00 19 29.151 5.30 1.98693 32.8 14.85 20 -21.562 1.20 1.80564 23.4 14.97 21 65.901 (variable) 14.89 Image plane ∞ Various data Focal length 60.00 F-number 2.80 Half angle of view 7.59 Image height 8.00 Lens length 87.95 BF 9.00 d21 9.00 Entrance pupil position 77.66 Exit pupil position -40.65 Front principal point position 65.15 Back principal point position -51.00 Lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 60.00 78.96 65.15 -51.00 Single lens data Lens starting surface focal length 1 1 87.48 2 3 204.97 3 5 37.99 4 7 -15.27 5 9 17.60 6 11 -19.22 7 14 52.25 8 16 17.47 9 17 -12.47 10 19 13.25 11 20 -20.04 CL2 (replaces CL1 from surface 15 onwards) surface data Surface number rd nd νd Effective diameter θ 15 -16.832 8.00 11.80 16 ∞ 21.00 15.36 -45 degrees 17 ∞ 5.00 10.23 45 degrees 18 148.383 2.31 1.84016 21.4 7.56 19 -9.772 0.80 1.89335 41.3 7.56 20 17.887 2.65 7.60 21 -62.497 3.08 1.55500 42.5 8.54 22 -9.241 0.50 2.00174 31.4 9.22 23 145.860 1.18 10.14 24 20.784 6.75 1.70108 30.0 12.75 25 -9.903 1.00 1.95000 17.0 13.69 26 -17.865 (variable) 14.74 Image plane ∞ Various data Focal length 180.00 F-number 8.00 Half angle of view: 2.54 Image height 8.00 Lens length 109.05 BF 9.00 d26 9.00 Entrance pupil position 77.66 Exit pupil position -44.99 Front principal point position -342.47 Back principal point position -171.00 Lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 180.00 58.06 -342.47 -171.00 Single lens data Lens starting surface focal length 1 1 87.48 2 3 204.97 3 5 37.99 4 7 -15.27 5 9 17.60 6 11 -19.22 7 14 52.25 8 18 10.99 9 19 -6.98 10 21 19.14 11 22 -8.66 12 24 10.52 13 25 -24.91 (Numerical Example 2) Unit: mm Surface Data Surface number rd nd νd Effective diameter 1 46.836 3.53 1.49700 81.5 22.50 2 -586.965 22.36 22.17 3 481.986 1.84 1.43387 95.1 16.20 4 -180.153 0.61 15.89 5 21.428 3.02 1.49700 81.5 15.19 6 -190.744 0.71 14.51 7 -72.729 0.76 1.60830 48.3 14.12 8 10.806 0.51 12.92 9 11.075 4.07 1.59282 68.6 13.07 10 -191.928 0.60 12.42 11 -67.529 0.70 1.77250 49.6 12.16 12 19.998 6.21 11.69 13 (Aperture) ∞ 1.43 11.79 14 -22.939 2.23 1.78701 35.4 11.80 Below CL1 15 -16.486 21.10 9.23 16* 13.428 4.59 2.05090 26.9 15.27 17 -73.738 0.50 14.45 18 -97.055 1.20 2.02673 24.6 13.68 19 9.097 3.24 12.00 20* 226.553 5.12 1.82231 47.8 13.84 21 -14.286 1.20 1.96164 18.1 14.64 22 -23.978 (variable) 15.34 Image plane ∞ Aspheric data Page 16 K = 0.00000e+000 A 4=-2.25978e-005 A 6=-2.66550e-007 A 8=-1.08236e-009 Page 20 K = 0.00000e+000 A 4= 4.76588e-005 A 6= 2.28401e-007 A 8= 2.97506e-008 Various data Focal length 60.00 F-number 3.50 Half angle of view 7.59 Image height 8.00 Lens length 94.54 BF 9.00 d22 9.00 Entrance pupil position 82.11 Exit pupil position -79.96 Front principal point position 101.65 Back principal point position -51.00 Lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 60.00 85.54 101.65 -51.00 Single lens data Lens starting surface focal length 1 1 87.44 2 3 302.50 3 5 38.94 4 7 -15.41 5 9 17.80 6 11 -19.90 7 14 64.65 8 16 11.11 9 18 -8.06 10 20 16.50 11 21 -39.13 CL2 (replaces CL1 from surface 15 onwards) surface data Surface number rd nd νd Effective diameter θ 15 -16.486 10.45 12.24 16 ∞ -22.00 15.65 -45 degrees 17 ∞ 5.00 11.57 45 degrees 18 31.404 2.49 1.92732 24.0 8.77 19 -13.887 0.80 1.71663 57.4 8.61 20 27.775 2.57 8.26 21 41.062 2.67 1.55500 42.5 7.95 22 -15.518 0.50 2.03172 28.7 7.65 23 18.601 0.59 7.65 24 10.633 4.70 1.51742 52.4 8.12 25 -9.674 1.00 2.05090 26.9 8.14 26 -685.731 (variable) 8.59 Image plane ∞ Various data Focal length 180.00 F-number 8.00 Half angle of view: 2.54 Image height 8.00 Lens length 116.54 BF 15.19 d26 15.19 Entrance pupil position 82.11 Exit pupil position -13.40 Front principal point position -871.28 Back principal point position -164.81 Lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 180.00 57.35 -871.28 -164.81 Single lens data Lens starting surface focal length 1 1 87.44 2 3 302.50 3 5 38.94 4 7 -15.41 5 9 17.80 6 11 -19.90 7 14 64.65 8 18 10.67 9 19 -12.82 10 21 20.64 11 22 -8.14 12 24 10.63 13 25 -9.34 (Numerical Example 3) Unit: mm Surface Data Surface number rd nd νd Effective diameter 1 81.118 3.23 1.49700 81.5 20.00 2 -284.047 23.06 19.80 3 175.704 2.48 1.43387 95.1 16.09 4 -90.346 0.38 15.82 5 21.607 3.57 1.49700 81.5 15.23 6 -105.991 0.64 14.40 7 -62.180 0.70 1.55275 50.4 14.04 8 10.222 0.52 12.79 9 10.508 5.00 1.59282 68.6 12.94 10 -3709.273 0.82 11.87 11 -46.026 0.70 1.77250 49.6 11.57 12 19.731 4.76 11.15 13 (Aperture) ∞ 1.51 11.33 14 -28.700 2.48 1.80547 34.6 11.37 Below CL1 15 -16.160 17.50 11.11 16* 13.273 3.45 1.97893 33.5 14.13 17 41.052 0.50 13.33 18 39.782 1.20 2.05090 26.9 13.10 19 9.614 1.99 12.00 20* 20.385 3.53 1.77894 51.7 13.54 21 73.120 (variable) 13.70 Image plane ∞ Aspheric data Page 16 K = 0.00000e+000 A 4=-1.30600e-005 A 6=-4.47229e-008 A 8=-9.36982e-010 Page 20 K = 0.00000e+000 A 4= 5.77013e-005 A 6= 2.03950e-007 A 8= 1.22461e-008 Various data Focal length 53.06 F-number 2.80 Half angle of view: 8.57 Image height 8.00 Lens total length 87.00 BF 9.00 d21 9.00 Entrance pupil position 69.99 Exit pupil position -25.47 Front principal point position 41.38 Back principal point position -44.06 Lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 53.06 78.00 41.38 -44.06 Single lens data Lens starting surface focal length 1 1 127.33 2 3 137.91 3 5 36.45 4 7 -15.83 5 9 17.68 6 11 -17.80 7 14 42.19 8 16 18.88 9 18 -12.31 10 20 35.25 Unit: mm CL2 (replaces CL1 from surface 15 onwards) surface data Surface number rd nd νd Effective diameter θ 15 -16.160 8.00 11.77 16 ∞ -22.00 15.27 -45 degrees 17 ∞ 5.00 9.40 45 degrees 18 -27.980 2.30 1.97672 19.9 6.81 19 -6.564 0.80 1.91307 39.5 7.00 20 13.898 0.50 7.22 21 8.911 3.99 1.55500 42.5 7.94 22 -8.162 0.50 2.01715 30.0 8.05 23 25.045 0.64 8.62 24 15.871 5.44 1.55500 42.5 9.80 25 -9.737 1.00 2.05090 26.9 10.89 26 -16.917 (variable) 11.82 Image plane ∞ Various data Focal length 180.00 F-number 9.00 Half angle of view 2.54 Image height 8.00 Overall lens length 109.00 BF 9.00 d26 9.00 Entrance pupil position 69.99 Exit pupil position -19.97 Front principal point position -868.55 Rear principal point position -171.00 Lens group data Group Starting surface Focal length Lens configuration length Front principal point position Rear principal point position 1 1 180.00 56.00 -868.55 -171.00 Single lens data Lens Starting surface Focal length 1 1 127.33 2 3 137.91 3 5 36.45 4 7 -15.83 5 9 17.68 6 11 -17.80 7 14 42.19 8 18 8.34 9 19 -4.79 10 21 8.38 11 22 -6.01 12 24 11.76 13 25 -23.51 (Numerical Example 4) Unit: mm Surface data Surface number r d nd νd Effective diameter<00​​​ 3 124.307 2.48 1.43387 95.1 18.85 4 -96.445 0.20 18.46 5 20.523 3.01 1.49700 81.5 17.35 6 -493.132 0.69 16.76 7 -89.379 0.70 1.59574 50.4 16.39 8 10.886 0.51 14.53 9 11.059 4.09 1.59282 68.6 14.67 10 -921.777 0.80 14.06 11 -46.598 0.70 1.77250 49.6 13.81 12 18.751 5.42 13.14 13 (Aperture) ∞ 1.52 13.44 14 -27.455 2.94 1.87692 37.3 13.49 Below CL1 15 -16.550 (variable) 11.12 Image plane ∞ Various data Focal length 77.53 F-number 4.00 Half angle of view 5.89 Image height 8.00 Lens length 87.47 BF 43.12 d15 43.12 Entrance pupil position 67.17 Exit pupil position -3.59 Front principal point position 16.03 Back principal point position -34.40 Lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 77.53 44.34 16.03 -34.40 Single lens data Lens starting surface focal length 1 1 92.08 2 3 125.60 3 5 39.72 4 7 -16.25 5 9 18.46 6 11 -17.23 7 14 42.19 Unit: mm CL2 (replaces CL1 from surface 15 onwards) surface data Surface number rd nd νd Effective diameter θ 15 -16.550 8.00 14.10 16 ∞ -21.00 18.59 -45 degrees 17 ∞ 5.00 9.66 45 degrees 18* -44.338 2.46 1.84178 21.3 6.72 19 -5.912 0.80 1.95729 35.5 6.79 20 17.082 2.10 7.07 21 788.101 2.99 1.55500 42.5 8.33 22 -11.267 2.73 9.21 23 -10.297 0.80 2.03244 28.6 9.71 24 -49.896 2.96 10.79 25* 22.460 6.29 1.48749 70.2 15.73 26 -12.697 (variable) 16.72 Image plane ∞ Aspheric data Page 18 K = 0.00000e+000 A 4= 1.03330e-004 A 6= 2.96522e-007 A 8=-5.26125e-008 Page 25 K = 0.00000e+000 A 4=-7.55933e-005 A 6= 1.80595e-007 A 8=-2.06505e-009 Various data Focal length 193.29 F-number 8.00 Half angle of view: 2.37 Image height 8.00 Lens length 108.47 BF 9.00 d26 9.00 Entrance pupil position 67.17 Exit pupil position -144.32 Front principal point position 16.80 Back principal point position -184.29 Lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 193.29 57.47 16.80 -184.29 Single lens data Lens starting surface focal length 1 1 92.08 2 3 125.60 3 5 39.72 4 7 -16.25 5 9 18.46 6 11 -17.23 7 14 42.19 8 18 7.87 9 19 -4.51 10 21 20.04 11 23 -12.70 12 25 17.68 The numerical values ​​of the conditional expressions in each numerical example are summarized in Table 1 below.

[0051] [Table 1]

[0052] Next, with reference to Fig. 11, an imaging device (digital camera) 10 using the optical system of each embodiment as an imaging optical system will be described. Fig. 11 is a schematic diagram of the imaging device 10. In Fig. 11, 100 denotes a camera body, and 101 denotes an imaging optical system configured with the optical system of each embodiment. 102 denotes an imaging element (photoelectric conversion element) such as a CCD that receives a subject image (optical image) formed by the imaging optical system 101. The imaging device 10 also has a display element such as a liquid crystal panel, and the subject image formed on the imaging element 102 is displayed. In this way, by applying the optical system (imaging optical system) of each embodiment to an imaging device, a small imaging device without parallax can be realized.

[0053] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist of the present invention.

[0054] For example, the number of eyes may be more than two or three as described in each embodiment. Furthermore, when combined with an imaging device equipped with an imaging element that converts an optical image formed on a light receiving surface into an electrical signal, electrical correction may be added depending on the amount of distortion aberration and lateral chromatic aberration. Furthermore, a configuration may be adopted in which the F-number is adjusted using an aperture diaphragm. [Explanation of symbols]

[0055] CL1 First converter (partial optical system) CL2 Second converter (partial optical system) M1 First optical element (optical path branching means)

Claims

1. an optical path branching means for branching light from the front group into a first optical path and a second optical path; a partial optical system disposed on the first optical path or the second optical path, the first light passing through the first optical path and the second light passing through the second optical path are imaged at different lateral magnifications; The optical system is characterized in that the partial optical system includes a biconcave lens.

2. 2. The optical system according to claim 1, wherein a first partial optical system, which is one of the partial optical systems and is arranged on the second optical path, increases the absolute value of the lateral magnification.

3. When the lateral magnification of a first partial optical system arranged on the second optical path among the partial optical systems is βc1, 1.10<βc1<3.00 3. The optical system according to claim 1, wherein the following condition is satisfied:

4. 4. The optical system according to claim 1, wherein a second partial optical system, which is one of the partial optical systems and is arranged on the first optical path, reduces the absolute value of the lateral magnification.

5. When the lateral magnification of the second partial optical system arranged on the first optical path among the partial optical systems is βc2, 0.30<βc2<0.85 5. The optical system according to claim 1, wherein the following condition is satisfied:

6. 6. The optical system according to claim 1, further comprising the front group having refractive power, the front group being arranged closer to the object side than the optical path branching means.

7. Let Dc1 be the distance on the optical axis from the most image-side of the front group to the most object-side of a first partial optical system that is disposed on the second optical path among the partial optical systems, and let Lc1 be the distance on the optical axis from the most object-side to the most image-side of the first partial optical system. 1.20<Dc1 / Lc1<3.50 7. The optical system according to claim 6, wherein the following condition is satisfied:

8. Let Dc2 be the distance on the optical axis from the most image-side of the front group to the most object-side of a second partial optical system that is disposed on the first optical path among the partial optical systems, and let Lc2 be the distance on the optical axis from the most object-side to the most image-side of the second partial optical system. 0.60<Dc2 / Lc2<2.50 8. The optical system according to claim 1, wherein the following condition is satisfied:

9. 8. The optical system according to claim 1, further comprising an element disposed between the first optical path and the second optical path, for preventing interference between the first image circle and the second image circle.

10. When the ratio of the lateral magnification of the first light beam passing through the first optical path to the lateral magnification of the light beam passing through the second optical path is Z, 1.50<Z<4.00 10. The optical system according to claim 1, wherein the following condition is satisfied:

11. When the amount of light transmitted by the optical path branching means is T and the amount of light reflected by the optical path branching means is R, 0.01<T / R<0.50 11. The optical system according to claim 1, wherein the following condition is satisfied:

12. the first optical path is a transmission optical path of light that has passed through the optical path branching means, 12. The optical system according to claim 1, wherein the second optical path is a reflected optical path of light reflected by the optical path branching means.

13. 13. The optical system according to claim 1, wherein a second partial optical system of the partial optical systems arranged on the first optical path includes a negative lens as a second lens counting from the object side.

14. An optical system according to any one of claims 1 to 13; an imaging element that receives an optical image formed by the optical system.

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