Stereo optical system and imaging apparatus

Abstract

To provide a stereo optical system that allows satisfactory stereoscopic views and can obtain photographic images with high image quality.SOLUTION: A stereo optical system has two optical systems 11, 12 arranged in parallel. When the distance on an optical axis from a surface on the most object side having a refractive power to an image surface in each of the two optical systems is defined as L, the inter-optical axis distance between lenses on the most object side in the two optical systems as Din, and the F number of the two optical systems as F, the condition of 0<(Din / L)×F≤1.35 is satisfied.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a stereo optical system for stereoscopic photography. [Background technology]

[0002] There is a demand for a stereoscopic optical system for acquiring stereoscopically viewable images for virtual reality and other applications. Patent Document 1 discloses a stereoscopic optical system in which two optical systems, each including a reflecting surface that bends the optical path midway, are arranged in parallel, and the optical axis distance on the image side is reduced while ensuring the optical axis distance (baseline length) on the object side, enabling stereoscopic imaging with one imaging element. Patent Document 2 discloses a compact stereoscopic optical system in which two optical systems, whose optical axes extend straight from the object side to the image side, are arranged in parallel. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-008629 A [Patent Document 2] JP 2012-003022 A Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for a stereo optical system that allows better stereoscopic viewing and captures higher quality images than the lens devices disclosed in Patent Documents 1 and 2. The present invention provides such a stereo optical system. [Means for solving the problem]

[0005] A stereo optical system according to one aspect of the present invention has two optical systems arranged in parallel. Let L be the distance on the optical axis from the surface having refractive power closest to the object in each of the two optical systems to the image plane, Din be the optical axis distance between the lenses closest to the object in the two optical systems, and F be the F-number of the two optical systems. 0<(Din / L)×F≦1.35 The present invention is characterized in that it satisfies the following conditions.

[0006] A stereo optical system according to another aspect of the present invention has two optical systems arranged in parallel. Each of the two optical systems includes an aperture stop. When the distance on the optical axis from the aperture stop to the image plane in each of the two optical systems is Lb, the distance between the optical axes of the lenses closest to the object in each of the two optical systems is Din, and the F-number of each of the two optical systems is F, 0.4≦(Lb / Din) / F≦1.5 The present invention is characterized in that it satisfies the following conditions. Effect of the Invention

[0007] According to the present invention, it is possible to provide a stereo optical system that enables favorable stereoscopic viewing and captures high-quality images, and a lens device having the same. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a cross-sectional view of the lens device and the stereo optical system according to the first embodiment. [Diagram 2] 4A to 4C are aberration diagrams of the stereo optical system of the first embodiment. [Diagram 3] FIG. 11 is a cross-sectional view of a lens device and a stereo optical system according to a second embodiment. [Figure 4] 11A to 11C are aberration diagrams of the stereo optical system of the second embodiment. [Diagram 5] FIG. 11 is a cross-sectional view of a lens device and a stereo optical system according to a third embodiment. [Figure 6] 11A to 11C are aberration diagrams of the stereo optical system of the third embodiment. [Figure 7] FIG. 13 is a cross-sectional view of a lens device and a stereo optical system according to a fourth embodiment. [Figure 8] 13A to 13C are aberration diagrams of the stereo optical system of the fourth embodiment. [Figure 9] FIG. 13 is a cross-sectional view of a lens device and a stereo optical system according to a fifth embodiment. [Figure 10] 13A to 13C are aberration diagrams of the stereo optical system of the fifth embodiment. [Figure 11]4A to 4C are diagrams showing optical images formed on an image sensor in each embodiment. [Figure 12] FIG. 2 is a diagram showing an imaging device including a stereo optical system according to each embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0010] FIG. 1(A), FIG. 3(A), FIG. 5(A), FIG. 7(A), and FIG. 9(A) respectively show a cross section of a lens device 100 having a stereo optical system of Examples 1 to 5 as seen from above. Each figure also shows a cross section of an imaging device 110 to which the lens device 100 as an interchangeable lens is detachably attached. The imaging device 110 includes a digital video camera, a digital still camera, a broadcast camera, a surveillance camera, and a silver halide film camera. The imaging device 110 may also be a camera for a mobile terminal such as a smartphone or a tablet. FIG. 1(B), FIG. 3(B), FIG. 5(B), FIG. 7(B), and FIG. 9(B) respectively show a cross section of one optical system of the stereo optical systems of Examples 1 to 5.

[0011] In each figure, the left side is the object side and the right side is the image side. Also, in Figures 1(A), 3(A), 5(A), 7(A) and 9(A), the upper side is the right side in the horizontal direction and the lower side is the left side.

[0012] In the first to fifth embodiments, the lens device 100 holds two optical systems 11 and 12 arranged in parallel on the left and right sides within a housing. The optical systems 11 and 12 have the same configuration, and each of the optical systems 11 and 12 forms an optical image (a right subject image and a left subject image) on an imaging surface (the same surface) of one (single) imaging element 101. However, the optical systems 11 and 12 may each form an optical image on the imaging surface of a different imaging element.

[0013] SP denotes an aperture stop. Each optical system has an object-side lens group OL arranged on the object side of the aperture stop SP, and an image-side lens group IL arranged on the image side of the aperture stop SP.

[0014] By simultaneously moving the entire optical systems 11 and 12 in the optical axis direction using an actuator (not shown), it is possible to form an optical image that is always in focus on the same surface. Also, CG in Figures 1(A), 3(A), 5(A), 7(A), and 9(A) is a cover glass made of a parallel plate (i.e., having no refractive power) arranged to cover the surface of each optical system that has refractive power and is closest to the object.

[0015] In addition, the base length, which is the distance between the optical axes of the lenses having refractive power and closest to the object in each of the optical systems 11 and 12, is Din. Each of the optical systems in Examples 1 to 4 is a coaxial optical system whose optical axis extends straight from the object side to the image side. Therefore, the center-to-center distance between the right and left subject images formed on the image sensor 101 is also Din.

[0016] On the other hand, each optical system of the fifth embodiment has an optical axis that is bent by two reflecting surfaces RF1 and RF2 in the image-side lens group IL. Therefore, the distance between the optical axes of the lenses closest to the image side, that is, the distance between the centers of the right and left subject images formed on the image sensor 101, is short Dout with respect to the base line length Din on the object side.

[0017] In each embodiment, one diaphragm mechanism 13 is provided for each of the optical systems 11 and 12, and simultaneously changes the aperture diameter (diaphragm aperture diameter) of the aperture diaphragms SP of both optical systems 11 and 12. This makes it possible to reduce the size of the lens device.

[0018] FIG. 11 shows right and left subject images (image circles) 111, 112 formed on the imaging surface of the imaging element 101 by the stereo optical system of each embodiment. The right subject image 111 is formed in a half area on the right side (shown on the left side in the figure) in the longitudinal direction of the imaging surface, and the left subject image 112 is formed in a half area on the left side (shown on the right side in the figure). By photoelectrically converting (capturing) these two subject images by the imaging element 101, two captured images (image for the right eye and image for the left eye) that have parallax and can be viewed stereoscopically are obtained. These right eye image and left eye image are displayed on a display element such as a liquid crystal panel or an organic EL panel in a stereoscopic display device such as VR goggles, and the observer can recognize an image with a sense of stereoscopic feeling by viewing the right eye image with the right eye and the left eye image with the left eye, respectively.

[0019] The stereo optical system of each embodiment having the above configuration satisfies the condition of the following formula (1), where L is the total optical length of each optical system (the distance on the optical axis from the surface having refractive power closest to the object to the image plane), Din is the base length, and F is the F-number of each optical system.

[0020] 0<(Din / L)×F≦1.35 (1) The condition of formula (1) indicates the appropriate range of the total optical length, the baseline length, and the F-number to obtain a compact stereo optical system and good optical performance for stereoscopic photography. If the F-number becomes large (darker) so that (Din / L)×F exceeds the upper limit of formula (1), each optical system will become pan-focused, and the optical performance for stereoscopic photography will decrease, which is not preferable. If the baseline length becomes large so that (Din / L)×F exceeds the upper limit of formula (1), the stereo optical system will become large, which is not preferable.

[0021] It is more preferable that the numerical range of formula (1) is as follows:

[0022] 0<(Din / L)×F≦1.33 (1a) Moreover, it is more preferable that the numerical range of the formula (1) is as follows:

[0023] 0<(Din / L)×F≦1.30 (1b) Moreover, it is even more preferable to set the numerical range of the formula (1) as follows:

[0024] 0<(Din / L)×F≦1.0 (1c) It is preferable that the stereo optical system of each embodiment satisfies at least one of the conditions of the following expressions (2) to (5).

[0025] 0.4≦(Lb / Din) / F≦1.5 (2) 0.2≦Φ / Din≦0.8 (3) 0.2≦(f / F) / hgt≦4.0 (4) 4.0≦(f×f1+f×f2-f1×f2) / f 2 <= 10.0 (5) In formulas (2) to (5), Lb is the distance on the optical axis from the aperture stop SP to the image plane, and Φ is the aperture diameter of the aperture stop SP in the fully open state (open aperture diameter). Furthermore, f is the focal length of the entire system of each optical system (11, 12), and hgt is the radius of the optical image (111, 112) formed on the image plane by each optical system, that is, the image circle radius. Furthermore, f1 is the focal length of the portion of each optical system that is closer to the object than the aperture stop SP (object-side lens group OL), and f2 is the focal length of the portion of each optical system that is closer to the image than the aperture stop SP (image-side lens group IL).

[0026] The condition of formula (2) indicates the appropriate range of the distance on the optical axis from the aperture stop SP to the image plane, the base line length, and the F-number to obtain a compact stereo optical system and good optical performance for stereoscopic photography. If the F-number becomes large (darker) so that (Lb / Din) / F falls below the lower limit of formula (2), each optical system will become pan-focused, and the optical performance for stereoscopic photography will decrease, which is not preferable. Also, if the base line length becomes large so that (Lb / Din) / F falls below the lower limit of formula (2), the stereo optical system will become large, which is not preferable.

[0027] The condition of formula (3) indicates the appropriate range of the open aperture diameter and the base length for miniaturizing the lens device and obtaining good optical performance for stereoscopic photography of the stereo optical system. If Din becomes large so that Φ / Din falls below the lower limit of formula (3), the stereo optical system becomes large, which is not preferable. Also, if the aperture diameter becomes small (darker) so that Φ / Din falls below the lower limit of formula (3), each optical system becomes pan-focused, which is not preferable because the optical performance for stereoscopic photography decreases. Furthermore, the distance between the aperture diaphragms SP of both optical systems becomes too far, making it difficult to use a single diaphragm mechanism 13, which is not preferable because the lens device becomes large.

[0028] The condition of formula (4) shows the appropriate range of the focal length, F-number, and image circle radius of each optical system for miniaturizing the lens device and obtaining good optical performance for stereoscopic photography of the stereo optical system. If the F-number becomes large (darker) so that (f / F) / hgt falls below the lower limit of formula (4), each optical system will become pan-focused and the optical performance for stereoscopic photography will decrease, which is not preferable. Furthermore, the distance between the aperture stops SP of both optical systems will be too far, making it difficult to use a single diaphragm mechanism 13, which will result in a large lens device, which is not preferable.

[0029] If the focal length of the entire system becomes so long that (f / F) / hgt exceeds the upper limit value of equation (4), the distance between the aperture stops SP of both optical systems becomes too large, making it difficult to use a single aperture mechanism 13. As a result, the lens apparatus becomes larger, which is not preferable.

[0030] The condition of formula (5) indicates the appropriate range of the focal length of the entire system and the focal lengths of the object side and image side parts in order to reduce the size of the stereo optical system and color shading. By satisfying this condition, that is, by having a long distance before and after the aperture stop SP and a long exit pupil distance, the lens diameter of each optical system can be made small. (f×f1+f×f2-f1×f2) / f 2If φ falls below the lower limit of formula (5), the exit pupil distance becomes short, which causes color shading, which is not preferable. Also, the lens diameter of each optical system becomes large, which causes the stereo optical system to become large, which is not preferable.

[0031] It is more preferable that the numerical ranges of the formulas (2) to (5) are as follows:

[0032] 0.42≦(Lb / Din) / F≦1.00 (2a) 0.22≦Φ / Din≦0.60 (3a) 0.22≦(f / F) / hgt≦3.00 (4a) 4.4≦(f×f1+f×f2-f1×f2) / f 2 <=9.0 (5a) Moreover, it is more preferable that the numerical ranges of the formulas (2) to (5) are as follows:

[0033] 0.45≦Lb / Din / F≦0.80 (2b) 0.24≦Φ / Din≦0.50 (3b) 0.26≦(f / F) / hgt≦1.00 (4b) 4.6≦(f×f1+f×f2-f1×f2) / f 2 <=8.0 (5b) Moreover, it is even more preferable that the numerical ranges of the formulas (2) to (5) are as follows:

[0034] 0.5≦(Lb / Din) / F≦0.6 (2c) 0.3≦Φ / Din≦0.4 (3c) 0.28≦(f / F) / hgt≦0.50 (4c) 5.0≦(f×f1+f×f2-f1×f2) / f 2 <=7.6 (5c) Numerical Examples 1 to 3 corresponding to Examples 1 to 3 are shown below. In each numerical example, surface number m indicates the order of the surface when counted from the object side. r (mm) indicates the radius of curvature of the mth surface, and d (mm) indicates the distance (air gap) on the optical axis between the mth surface and the (m+1)th surface. In addition, nd indicates the refractive index at the d-line of the optical material between the mth surface and the (m+1)th surface, and νd indicates the Abbe number of the optical member based on the d-line. The Abbe number νd based on the d-line is given by Nd, NF, NC, and Ng, respectively, as the refractive indexes at the d-line (587.6 nm), F-line (486.1 nm), C-line (656.3 nm), and g-line (wavelength 435.8 nm) of the Fraunhofer lines. νd=(Nd-1) / (NF-NC) It is expressed as:

[0035] In each numerical example, d, focal length (mm), F-number, and half angle of view (°) are all values ​​when the optical system is focused on an object at infinity. Back focus BF is the distance on the optical axis from the lens surface (last surface) closest to the image side of the optical system to the image surface. The total lens length is the value obtained by adding the back focus to the distance from the lens surface (first surface) closest to the object side of the optical system to the last surface.

[0036] Table 1 shows values ​​related to the conditions of the above-mentioned expressions (1) to (5) in Numerical Examples 1 to 5. The stereo optical system of each of the Numerical Examples satisfies all of the conditions of the expressions (1) to (5).

[0037] 2, 4, 6, 8, and 10 respectively show longitudinal aberrations (spherical aberration, astigmatism, distortion, and chromatic aberration) of the optical systems of Examples 1 to 5 in a state where the optical system is focused on an object at infinity. In the spherical aberration diagrams, Fno indicates the F-number, the solid line indicates the spherical aberration for the d-line (wavelength 587.6 nm), and the dashed line indicates the spherical aberration for the g-line (wavelength 435.8 nm). In the astigmatism diagrams, the solid line S indicates the astigmatism on the sagittal image plane, and the dashed line M indicates the astigmatism on the meridional image plane. The distortion diagrams show the distortion aberration at the d-line. The chromatic aberration diagrams show the chromatic aberration of magnification at the g-line. ω is the half angle of view (°). [Numerical example 1] Unit: mm Surface Data Surface number rd nd νd 1 ∞ 2.00 1.51633 64.1 2∞3.1 3 17.741 0.60 2.00069 25.5 4 5.568 2.06 5 -15.843 0.65 1.49700 81.7 6 7.816 3.41 1.91082 35.2 7 -20.000 1.50 8 52.224 0.65 1.90043 37.4 9 7.530 2.03 10 800.000 1.90 1.51742 52.4 11 -7.167 4.09 12 (Aperture) ∞ 5.30 13∞3.67 14 800.000 2.86 1.48749 70.2 15 -8.741 1.85 16 22.795 4.18 1.49700 81.7 17 -7.288 0.65 2.00100 29.1 18 -19.868 14.00 Image plane ∞ Various data Zoom ratio 1.00 Focal length 7.85 F-number 4.00 Half angle of view (°) 23.39 Image height 3.40 Lens length 54.50 BF 14.00 Lens Group Data Group starting plane focal length 1 1 ∞ 2 3 -38.94 3 12 15.99 [Numerical example 2] Unit: mm Surface Data Surface number rd nd νd 1 ∞ 2.00 1.51633 64.1 2∞4.28 3 18.462 0.60 2.00069 25.5 4 5.606 1.97 5 -18.975 0.65 1.49700 81.7 6 7.390 3.55 1.91082 35.2 7 -20.000 1.50 8 48.467 0.65 1.90043 37.4 9 6.960 1.69 10 795.039 2.89 1.53172 48.8 11 -7.309 3.38 12 (Aperture) ∞ 5.40 13∞3.00 14 795.039 3.31 1.48749 70.2 15 -8.616 1.85 16 29.070 4.13 1.49700 81.7 17 -6.974 0.65 2.00100 29.1 18 -17.099 14.00 Image plane ∞ Various data Zoom ratio 1.00 Focal length 7.85 F-number 3.90 Half angle of view(°) 23.39 Image height 3.40 Lens length 55.50 BF 14.00 Lens Group Data Group starting plane focal length 1 1 ∞ 2 3 -63.86 3 8 -118.98 4 12∞ 5 14 17.51 6 16 199.86 [Numerical example 3] Unit: mm Surface Data Surface number rd nd νd 1 ∞ 2.00 1.51633 64.1 2∞4.29 3∞0.00 4 17.949 0.60 1.59522 67.7 5 4.961 0.80 6 80.199 0.60 1.74320 49.3 7 4.452 4.00 1.59551 39.2 8 30.092 1.50 9 15.763 0.65 1.78800 47.4 10 9.807 1.50 11 649.000 1.73 1.49700 81.5 12 -6.114 3.81 13(Aperture) ∞ 7.74 14∞1.00 15 728.740 5.00 1.49700 81.5 16 -8.958 1.85 17 46.785 3.03 1.49700 81.5 18 -6.743 0.65 1.78800 47.4 19 -56.371 22.01 Image plane ∞ Various data Zoom ratio 1.00 Focal length 12.00 12.00 F-number 8.00 8.00 Half angle of view (° 22.01 22.01 Image height 4.85 4.85 Lens length 62.76 62.76 BF 22.01 22.01 d 2 4.29 4.29 d12 3.81 3.81 d14 1.00 1.00 d19 22.01 22.01 [Numerical example 4] Unit: mm Surface Data Surface number rd nd νd 1 ∞ 1.65 1.51633 64.1 2∞3.29 3∞0.00 4 10.579 1.00 1.78636 47.1 5 6.853 2.01 6 21.216 0.80 1.91701 36.2 7 7.234 4.00 1.84684 32.7 8 -525.533 1.96 9 8.910 3.20 1.59522 67.7 10 -15.871 1.00 11 -139.810 1.00 1.75521 25.4 12 5.739 2.50 13(Aperture) ∞ 1.00 14∞1.00 15 -22.569 1.00 2.00330 28.3 16 -12.905 0.50 17 9.123 2.00 1.88300 40.8 18 -18.973 0.65 1.63294 34.6 19 6.887 11.01 Image plane ∞ Various data Zoom ratio 1.00 Focal length 19.10 F-number 4.50 Half angle of view (°) 14.24 Image height 4.85 Lens length 39.55 BF 11.01 [Numerical example 5] Unit: mm Surface Data Surface number rd nd νd 1 ∞ 2.00 1.51633 64.1 2∞17.26 3∞0.00 4 471.725 0.60 1.94594 18.0 5 -60.033 1.38 6 -21.701 0.85 1.61293 37.0 7 24.545 2.79 1.88300 40.8 8 -28.231 1.73 9 -35.328 0.65 1.71736 29.5 10 14.607 1.00 11 17.760 1.82 1.67000 57.3 12 188.195 0.50 13 (Aperture) ∞ 24.00 1.51633 64.1 14∞0.50 15 23.747 2.47 1.49700 81.5 16 -36.775 18.17 17 -11.886 1.00 1.85896 22.7 18 -169.717 1.28 1.94594 18.0 19 -20.007 13.33 Image plane ∞ Various data Zoom ratio 1.00 Focal length 42.51 F-number 3.50 Half angle of view (°) 6.51 Image height 4.85 Lens length 91.32 BF 13.33

[0038] [Table 1]

[0039] [Imaging device] 12 shows a digital still camera as an imaging device using the stereo optical system of each of the above-mentioned embodiments as an imaging optical system. Reference numeral 20 denotes a camera body, and reference numeral 21 denotes an imaging optical system constituted by the stereo optical system of any of the embodiments 1 to 5, which is provided integrally with the camera body 20. Reference numeral 22 denotes a single imaging element such as a CCD sensor or CMOS sensor that is built into the camera body 20 and captures an optical image (subject image) formed by the imaging optical system 21. Reference numeral 23 denotes a recording unit that records image data generated by processing an imaging signal from the imaging element 22, and reference numeral 24 denotes a rear display that displays the image data.

[0040] By using the stereo optical system of each embodiment, a small-sized camera capable of providing good stereoscopic vision and having high optical performance can be obtained.

[0041] The above embodiment includes the following configurations.

[0042] (Configuration 1) A stereo optical system having two optical systems arranged in parallel, Let L be the distance on the optical axis from the surface having refractive power closest to the object in each of the two optical systems to the image plane, Din be the optical axis distance between the lenses closest to the object in the two optical systems, and F be the F-number of the two optical systems. 0<(Din / L)×F≦1.35 A stereo optical system characterized by satisfying the following conditions. (Configuration 2) A stereo optical system having two optical systems arranged in parallel, each of the two optical systems includes an aperture stop; Let Lb be the distance on the optical axis from the aperture stop to the image plane, Din be the optical axis distance between the lenses in the two optical systems closest to the object, and F be the F-number of the two optical systems. 0.4≦(Lb / Din) / F≦1.5 A stereo optical system characterized by satisfying the following conditions. (Configuration 3) each of the two optical systems includes an aperture stop; When the aperture diameter of the aperture stop in the fully open state is Φ, 0.2≦Φ / Din≦0.8 3. The stereo optical system according to configuration 1 or 2, which satisfies the following conditions: (Configuration 4) When the focal length of each of the two optical systems is f and the radius of the optical image formed on the image plane by each of the two optical systems is hgt, 0.2≦(f / F) / hgt≦4.0 4. The stereo optical system according to any one of configurations 1 to 3, which satisfies the following condition: (Configuration 5) each of the two optical systems includes an aperture stop; Let f be the focal length of each of the two optical systems, f1 be the focal length of a portion of each of the two optical systems that is closer to the object side than the aperture stop, and f2 be the focal length of a portion of each of the two optical systems that is closer to the image side than the aperture stop. 4.0≦(f×f1+f×f2-f1×f2) / f 2 <= 10.0 5. The stereo optical system according to any one of configurations 1 to 4, which satisfies the following condition: (Configuration 6) The stereo optical system according to any one of configurations 1 to 5, wherein each of the two optical systems is a coaxial optical system. (Configuration 7) Each of the two optical systems has two reflecting surfaces that fold the optical path; 6. The stereo optical system according to any one of configurations 1 to 5, wherein the optical axis distance between the lenses closest to the image side in the two optical systems is shorter than the optical axis distance between the lenses closest to the object side. (Configuration 8) 8. The stereo optical system according to any one of configurations 1 to 7, wherein the two optical systems form an optical image on an imaging surface of a single imaging element. (Configuration 9) A stereo optical system according to any one of configurations 1 to 8; and a single image sensor that captures an image of a subject using the stereo optical system.

[0043] The embodiments described above are merely representative examples, and various modifications and alterations are possible for each embodiment when implementing the present invention. [Explanation of symbols]

[0044] 11,12 Optical system 100 Lens device 101 Image sensor

Claims

1. A stereo optical system having two optical systems arranged in parallel, Let L be the distance on the optical axis from the surface having refractive power closest to the object in each of the two optical systems to the image plane, Din be the optical axis distance between the lenses closest to the object in the two optical systems, and F be the F-number of the two optical systems. 0<(Din / L)×F≦1.35 A stereo optical system characterized by satisfying the following conditions.

2. A stereo optical system having two optical systems arranged in parallel, Each of the two optical systems includes an aperture stop; Let Lb be the distance on the optical axis from the aperture stop to the image plane in the two optical systems, Din be the distance between the optical axes of the lenses closest to the object in the two optical systems, and F be the F-number of the two optical systems. 0.4≦(Lb / Din) / F≦1.5 A stereo optical system characterized by satisfying the following conditions.

3. Each of the two optical systems includes an aperture stop; When the aperture diameter of the aperture stop in the fully open state is Φ, 0.2≦Φ / Din≦0.8 3. The stereo optical system according to claim 1, wherein the following condition is satisfied:

4. When the focal length of each of the two optical systems is f and the radius of the optical image formed on the image plane by each of the two optical systems is hgt, 0.2≦(f / F) / hgt≦4.0 3. The stereo optical system according to claim 1, wherein the following condition is satisfied:

5. Each of the two optical systems includes an aperture stop; Let f be the focal length of each of the two optical systems, f1 be the focal length of a portion of each of the two optical systems that is closer to the object side than the aperture stop, and f2 be the focal length of a portion of each of the two optical systems that is closer to the image side than the aperture stop. 4.0≦(f×f1+f×f2-f1×f2) / f ２ ≦10.0 3. The stereo optical system according to claim 1, wherein the following condition is satisfied:

6. 3. The stereo optical system according to claim 1, wherein each of the two optical systems is a coaxial optical system.

7. Each of the two optical systems has two reflecting surfaces that bend an optical path; 3. The stereo optical system according to claim 1, wherein the distance between the optical axes of the lenses closest to the image side in the two optical systems is shorter than the distance between the optical axes of the lenses closest to the object side.

8. 3. The stereo optical system according to claim 1, wherein the two optical systems form an optical image on an imaging surface of a single imaging element.

9. The stereo optical system according to claim 1 or 2, and a single image sensor that captures an image of a subject using the stereo optical system.

Images