Stereo imaging system, stereo optical system, and imaging device

Abstract

When arranging two optical systems in parallel, miniaturization is achieved while avoiding interference between the image sensors. [Solution] The stereo imaging system 10 comprises two imaging devices 11 and 12, each having an optical system including a first lens group L1, arranged so that the first lens groups are in parallel. The optical system of each of the two imaging devices includes a first optical element 121 that branches the optical path from the first lens group into a first optical path extending in a direction different from the optical axis direction of the first lens group and a second optical path extending in a direction different from the first optical path, a second lens group L21 arranged on the first optical path and having a positive refractive power toward the first imaging plane, a second optical element 122 that bends the second optical path, and a third lens group L22 arranged on the second optical path bent by the second optical element and having a positive refractive power toward the second imaging plane. The bending direction of the second optical path by the second optical element in each of the two imaging devices is different from that of the other.

Description

[Technical Field]

[0001] This invention relates to an optical system suitable for stereo imaging. [Background technology]

[0002] As an optical system used for imaging, Patent Document 1 discloses an optical system that uses an optical path separation element to guide light from a subject to multiple image sensors. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2010-160312 [Overview of the project] [Problems that the invention aims to solve]

[0004] When arranging two such optical systems in parallel for stereo imaging, miniaturization of the optical system is required while avoiding interference between the image sensors. [Means for solving the problem]

[0005] One aspect of the present invention is a stereo imaging system in which two imaging devices, each having an optical system including a first lens group, are arranged so that the first lens groups are in parallel. The optical system of each of the two imaging devices includes a first optical element that branches the optical path from the first lens group into a first optical path extending in a direction different from the optical axis direction of the first lens group and a second optical path extending in a direction different from the first optical path, a second lens group arranged on the first optical path and having a positive refractive power toward the first imaging plane, a second optical element that bends the second optical path, and a third lens group arranged on the second optical path bent by the second optical element and having a positive refractive power toward the second imaging plane. A characteristic feature is that the bending direction of the second optical path by the second optical element in each of the two imaging devices is different from that of the other.

[0006] Another aspect of the present invention is a stereo optical system having two optical systems, each including a first lens group, and arranged so that the first lens groups are in parallel. Each of the two optical systems includes a first optical element that branches the optical path from the first lens group into a first optical path extending in a direction different from the optical axis direction of the first lens group and a second optical path extending in a direction different from the first optical path, a second lens group arranged on the first optical path and having a positive refractive power toward the first image plane, a second optical element that bends the second optical path, and a third lens group arranged on the second optical path bent by the second optical element and having a positive refractive power toward the second image plane. A characteristic feature is that the bending direction of the second optical path by the second optical element in each of the two optical systems is different from that of the other. An imaging device having the above stereo optical system also constitutes another aspect of the present invention. [Effects of the Invention]

[0007] According to the present invention, a compact stereo optical system and a stereo imaging device can be provided. [Brief explanation of the drawing]

[0008] [Figure 1] A diagram showing the configuration of a stereo imaging system as an example. [Figure 2] A diagram showing the configuration of another stereo imaging system as an example. [Figure 3] Cross-sectional view and aberration diagram of the optical system of Example 1. [Figure 4] Cross-sectional view and aberration diagram of the optical system of Example 2. [Figure 5] A diagram showing the configuration of an imaging device having the optical system of Example 3. [Figure 6] Cross-sectional view and aberration diagram of the optical system of Example 3.

[0009] The present invention provides a compact imaging device and imaging system that can easily capture wide-angle, high-resolution stereoscopic images. [Modes for carrying out the invention]

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0011] Figures 1(A) and 1(B) show the configuration of a stereo imaging system (hereinafter simply referred to as the imaging system) 10 using the optical systems of Examples 1 to 3 described later. Figure 1(A) shows the imaging system viewed from a direction perpendicular to the optical axis of the first lens group, which will be described later, and Figure 1(B) shows the imaging system viewed from the object side in the direction of the sub-axis of the first lens group. The imaging system 10 is used for stereoscopic imaging and consists of imaging devices 11 and 12 arranged so that their respective optical systems have parallax with each other. This imaging system 10 is used for various imaging applications such as general-purpose imaging, broadcast imaging, cinema imaging, surveillance imaging, and in-vehicle imaging.

[0012] Each imaging device 11 and 12 simultaneously images the same subject by directing light from the subject to multiple image sensors via an optical system. By combining the multiple images obtained by simultaneously imaging the same subject in each imaging device, high-resolution composite images and composite images with a wide dynamic range can be generated. Because the images generated by imaging devices 11 and 12 have parallax with each other, these images can be viewed in 3D.

[0013] The optical system of each imaging device has a first lens group L1 closest to the object. The first lens groups L1 of imaging devices 11 and 12 are arranged in parallel so that their optical axes are parallel to each other at a predetermined interval (baseline length).

[0014] Furthermore, the optical system of each imaging device has one or more first optical elements 121 that branch the optical path from the first lens group L1 (i.e., the optical axis of the optical system) into a first optical path extending in a direction different from the optical axis direction of the first lens group L1 and a second optical path extending in a direction different from the first optical path. The second optical path may extend in the direction of the optical axis direction of the first lens group L1, or it may extend in a direction different from the optical axis direction.

[0015] Also, the optical system of each imaging device has a second-1 lens group (second lens group) L21 disposed on the first optical path and having a positive refractive power toward the first image plane or the first imaging plane (imaging element 131). Further, the optical system has one or more second optical elements 122 that bend the second optical path, and a second-2 lens group (third lens group) L22 disposed on the second optical path bent by the second optical element 122 and having a positive refractive power toward the second image plane or the second imaging plane (imaging element 132). The one or more first optical elements include the first optical element on the object side, and the one or more second optical elements include the second optical element on the image side. FIGS. 1(A) and (B) show an optical system having one (the most object-side) first optical element 121 and one (the most image-side) second optical element 122. A lens group includes one or more lenses.

[0016] A surface that branches the optical path by transmission, reflection, etc. in the first optical element is called a branching surface, and a surface that bends the optical path by reflection, etc. in the second optical element is called a bending surface. The branching direction of the first optical path at the branching surface and the bending direction of the second optical path at the bending surface may be perpendicular to the original optical path or deviate from the perpendicular direction.

[0017] The optical systems of the imaging devices 11 and 12 have the same configuration as each other except for the branching direction of the optical path by the first optical element 121 and the bending direction of the optical path by the second optical element 122. In the optical systems of the imaging devices 11 and 12, after the first optical path is branched with respect to the second optical path by the first optical element 121, the second optical path is bent in different directions from each other by the second optical element 122. Thereby, interference between a plurality (two) of imaging elements 131 and 132 can be avoided in a small-sized imaging device.

[0018] And the bending directions of the second optical paths by the second optical elements in the imaging devices 11 and 12 are different from each other (for example, in opposite directions as shown in FIG. 1(B)). Thereby, the distances between the optical system parts on the image side of the second optical element 122 and between the imaging elements 132 in the imaging devices 11 and 12 are separated from each other, and these interferences can be avoided.

[0019] The second-first lens group L21 and the second-second lens group L22 have positive refractive power, which allows for a longer optical path length from the first optical element 122 to the image sensors 131 and 132. As a result, the distance between the image sensors 131 and 132 can be increased to avoid interference between them.

[0020] The first optical element may be a beam splitter acting as a prism, as shown in Figure 1(A), or a half-mirror. Furthermore, it may be an element that branches the optical path according to wavelength, such as a color-separating prism or a dichroic mirror. By using an element that branches the optical path according to wavelength (color) and imaging with image sensors provided for each color, as in a so-called three-chip camera, a high-resolution color composite image can be obtained compared to imaging without separating wavelengths. The second optical element may be a prism with a reflective surface, or a mirror.

[0021] The optical path of light passing through the second-first lens group L21 and forming an image on the image sensor 131 is bent once by the first optical element 121. On the other hand, the optical path of light passing through the second-second lens group L22 and forming an image on the image sensor 132 is bent once by the second optical element 122. As a result, the subject image formed on the image sensor 131 and the subject image formed on the image sensor 132 are inverted horizontally or vertically from each other. Therefore, it is preferable to perform image processing to invert one of the captured images obtained by the image sensor 131 and the captured image obtained by the image sensor 132 to align the orientation of these captured images.

[0022] Figure 2 shows an imaging device 11 using an optical system with a different configuration than that of Figure 1(A), viewed from the same direction as Figure 1(A) (a direction perpendicular to the optical axis of the first lens group L1). The optical system shown in Figure 2 has the same components as the optical systems in Figures 1(A) and (B), but the bending direction of the optical path of the second optical element 122 is different from that of Figures 1(A) and (B). As a result, the orientation of the optical axis of the second-second lens group L22 (the position of the image sensor 132) is different from that of Figures 1(A) and (B). The configuration of the imaging device 12 is basically the same as that of the imaging device 11, but the bending direction of the optical path by the second optical element 122 (the second optical path from the second optical element 122 to the image sensor 132) is in a different direction (opposite direction) than that of the imaging device 11.

[0023] Furthermore, each imaging device preferably has the following configuration. First, the first lens group L1 preferably has an aperture diaphragm S and a first sub-lens group L1A as a focusing group that moves in the optical axis direction during focusing. A sub-lens group is a collection of one or more lenses that move in a way that changes the distance between adjacent sub-lens groups during focusing. By arranging the aperture diaphragm S and the focusing group (L1A) on the object side of the first optical element 121, aperture adjustment and focusing do not need to be performed for each image sensor, and the configuration of the imaging device can be simplified.

[0024] Furthermore, it is preferable that the second-first lens group L21 includes a glass block 140 that does not have refractive power, such as a parallel plate. This is to make the optical path length from the first optical element 121 to the image sensor 131 and the optical path length from the second optical element 122 to the image sensor 132 the same, thereby making the aberrations in the image sensors 131 and 132 the same.

[0025] Furthermore, in each imaging device with the configuration shown in Figure 2, it is preferable to place an intermediate lens group between the first optical element 121 and the second optical element 122 in order to increase the distance between the image sensors 131 and 132.

[0026] Furthermore, the optical axes of the second-first lens group L21 and the second-second lens group L22 may both extend perpendicular to the optical axis of the first lens group L1, as shown in Figures 1(A), (B) and 2, or they may extend at an angle other than a right angle to the optical axis of the first lens group L1. Also, as shown in Figures 1(A) and (B), one of the optical axes of the second-first lens group L21 and the second-second lens group L22 may be located in a plane parallel to the optical axis of the first lens group L1 and the other in a plane perpendicular to that plane, or as shown in Figure 2, both may be located in a plane parallel to the optical axis of the first lens group L1. Moreover, the optical axes of the second-first lens group L21 and the second-second lens group L22 may both be located in a plane perpendicular to the plane parallel to the optical axis of the first lens group L1. In any of these cases, the bending directions of the second optical path by the second optical element in each of the imaging devices 11 and 12 should be in different directions.

[0027] Figure 3(A) shows a cross-section along the optical axis of the optical system of Example 1 when it is in focus on an object at infinity (hereinafter referred to as the infinity focus state). The optical system of Example 1 has a first lens group L1 with positive refractive power, a first optical element 121, a second optical element 122, and a second-first lens group L21 with positive refractive power on the first optical path bent by the first optical element 121, arranged in order from the object side to the image side. Light emitted from the second-first lens group L21 is imaged on the image sensor 131. Although not shown, the second-second lens group L22 with positive refractive power on the second optical path, which is bent by the second optical element 122 but not by the first optical element 121, has the same configuration as the second-first lens group L21. Light emitted from the second-second lens group L22 is imaged on the image sensor 132. The first lens group L1 includes an aperture diaphragm S and a first sub-lens group L1A.

[0028] Following the description of the optical system of Example 3, which will be discussed later, numerical examples 1 to 3 corresponding to Examples 1 to 3 are shown. Figure 3(B) shows the longitudinal aberrations (spherical aberration, astigmatism, distortion, and chromatic aberration) of the optical system of numerical example 1 in the infinity focus state. In the spherical aberration diagram, Fno indicates the F number, the solid line indicates spherical aberration at the d line (wavelength 587.6 nm), and the dashed line indicates spherical aberration at the g line (wavelength 435.8 nm). In the astigmatism diagram, the solid line S indicates astigmatism at the sagittal image plane, and the dashed line M indicates astigmatism at the meridional image plane. The distortion diagram shows distortion at the d line. The chromatic aberration diagram shows lateral chromatic aberration at the g line. ω is the half-angle of view (°).

[0029] Figure 4(A) shows a cross-section along the optical axis of the optical system of Example 2 in the infinity focus state. The optical system of Example 2 has, arranged in order from the object side to the image side, a first lens group L1 with positive refractive power, a first optical element 121, an intermediate lens group LM, a second optical element 122, and a second-first lens group L21 with positive refractive power on the first optical path bent by the first optical element 121. Light emitted from the second-first lens group L21 is imaged on the image sensor 131. Although not shown, the second-second lens group L22 with positive refractive power on the second optical path, which is bent by the second optical element 122 but not by the first optical element 121, has the same configuration as the second-first lens group L21. Light emitted from the second-second lens group L22 is imaged on the image sensor 132. The first lens group L1 includes an aperture diaphragm S and a first sub-lens group L1A. By arranging the intermediate lens group LM between the first optical element 121 and the second optical element 122, the second-first lens group L21 and the second-second lens group L22 can be miniaturized, and each imaging device can also be miniaturized.

[0030] Figure 4(B) shows the longitudinal aberrations (spherical aberration, astigmatism, distortion, and chromatic aberration) of the optical system in numerical example 3 when it is in focus at infinity.

[0031] Figure 5 shows the configuration of the imaging device 11 having the optical system of Example 3, viewed from the same direction as in Figure 2. Figure 6(A) shows a cross-section along the optical axis of the optical system of Example 3 in the infinity focus state. The optical system of Example 3 has a first lens group L1 with positive refractive power arranged in order from the object side to the image side, a first optical element 121, another first optical element 123 arranged on a second optical path branched by the first optical element 121, and a second optical element 122 arranged on a first optical path branched by the first optical element 123. It also has another second optical element 124 arranged on a second optical path branched by the first optical element 123.

[0032] Furthermore, the optical system of this embodiment has a second-first lens group L21 with positive refractive power on the first optical path, which is bent by the first optical element 121. It also has another second-first lens group L21 with positive refractive power on the first optical path, which is not bent by the first optical element 121 but is bent by the first optical element 123 and then by the second optical element 122. The light emitted from these two second-first lens groups L21 forms images on separate image sensors 131. The second-second lens group L22, which has positive refractive power on the second optical path, is not bent by the first optical element 123 but is bent by the second optical element 124, and has the same configuration as the second-first lens group L21. The light emitted from the second-second lens group L22 forms an image on the image sensor 132. The first lens group L1 has an aperture diaphragm S and a first sub-lens group L1A.

[0033] As in Example 3, in each imaging device, light incident from the first lens group L1 may be captured by three image sensors, and a composite image may be generated by combining the three captured images produced using these image sensors.

[0034] Figure 6(B) shows the longitudinal aberrations (spherical aberration, astigmatism, distortion, and chromatic aberration) of the optical system in numerical example 3 when it is in focus at infinity.

[0035] In each embodiment (each numerical example), the optical system preferably satisfies the following condition (1), where D1 is the distance along the optical axis from the lens surface closest to the object in the first lens group L1 to the lens surface closest to the image in the first lens group L1, and f is the focal length of the entire optical system.

[0036] 7.50 ≤ D1 / f ≤ 16.00 (1) If D1 / f falls below the lower limit of equation (1), it becomes difficult to arrange the aperture diaphragm S and the first sub-lens group L1A, which is the focusing group, in the first lens group L1, which is undesirable. If D1 / f exceeds the upper limit of equation (1), the diameter of the lens closest to the object becomes large, causing interference between the lenses closest to the object of adjacent imaging devices 11 and 12, which is also undesirable.

[0037] Furthermore, it is more preferable to set the lower limit of equation (1) to 7.80, 8.00, or 8.20 (6.76 3.47). Also, it is more preferable to set the upper limit of equation (1) to 15.00, 14.00, or 13.00 (19.35 21.59).

[0038] Furthermore, it is preferable that the optical system of each embodiment satisfies the following condition (2) when the focal length of the second-first lens group L21 and the second-second lens group L22 is f2.

[0039] 5.71 ≤ f² / f ≤ 7.82 (2) If f2 / f falls below the lower limit of equation (2), the refractive power of the second-first lens group L21 and the second-second lens group L22 becomes too large, making it difficult to correct the chromatic aberration and field curvature occurring in the first lens group L1, which is undesirable. If f2 / f exceeds the upper limit of equation (2), it becomes difficult to correct the various aberrations occurring in the first lens group L1, which is also undesirable.

[0040] Furthermore, it is more preferable to set the lower limit of equation (2) to 5.90, 6.10, or 6.30 (5.04 2.66). Also, it is more preferable to set the upper limit of equation (2) to 7.40, 7.00, or 6.80 (8.91 9.64).

[0041] Furthermore, in each embodiment, it is preferable that the optical system satisfies the following condition (3), where D2 is the distance along the optical axis from the bending surface of the second optical element 122 to the first and second imaging planes (image planes).

[0042] 5.00 ≤ D2 / f ≤ 7.44 (3) It is preferable that D2 / f falls below the lower limit of equation (3), as this is undesirable because the distance from the folding surface to each imaging surface (image plane) becomes too short, causing the image sensors 131 and 132 to interfere with each other. It is also undesirable that D2 / f exceeds the upper limit of equation (3), as this causes the distance from the folding surface to the imaging surface to become too long, resulting in a larger imaging device.

[0043] Furthermore, it is more preferable to set the lower limit of equation (3) to 5.20, 5.40, or 5.60 (4.37 2.19). Also, it is more preferable to set the upper limit of equation (3) to 7.30, 7.20, or 7.00 (7.89 8.19).

[0044] Furthermore, in each embodiment, it is preferable that the optical system satisfies the following condition (4), where DM is the distance along the optical axis from the branching surface of the first optical element 121 to the bending surface of the second optical element 122.

[0045] 2.47 ≤ DM / f ≤ 8.22 (4) If DM / f falls below the lower limit of equation (4), the first optical element 121 and the second optical element 122 will interfere with each other, which is undesirable. If DM / f exceeds the upper limit of equation (4), the distance from the first optical element 121 to the second optical element 122 will become too long, which is undesirable because the imaging device will become larger.

[0046] Furthermore, it is more preferable to set the lower limit of equation (4) to 2.60, 2.80, or 2.90 (2.01 0.83). Also, it is more preferable to set the upper limit of equation (4) to 7.80, 7.50, 7.00, or 6.40 (10.30 11.69).

[0047] Furthermore, it is preferable that the optical system of each embodiment satisfies the following condition (5), where DS is the distance along the optical axis from the aperture diaphragm S to the first and second imaging planes, respectively.

[0048] 11.87 ≤ DS / f ≤ 20.01 (5) If DS / f falls below the lower limit of equation (5), it becomes difficult to position the aperture diaphragm S closer to the object than the first optical element 121, which is undesirable. If DS / f exceeds the upper limit of equation (5), the distance between the aperture diaphragm S and the second-first lens group L21 and the second-second lens group L22 becomes too long, causing the diameters of the second-first lens group L21 and the second-second lens group L22 to increase. As a result, the imaging device becomes larger, which is undesirable.

[0049] Furthermore, it is more preferable to set the lower limit of equation (5) to 12.00, 12.20, or 12.40 (11.27 7.97). Also, it is more preferable to set the upper limit of equation (5) to 18.00, 17.00, or 16.00 (23.53 25.89).

[0050] The above describes a case in which an imaging system is configured using two imaging devices, each having an optical system that satisfies the above configuration and conditions. However, it is also possible to configure a stereo optical system and an integrated imaging device having the same, each containing two optical systems that satisfy the above configuration and conditions. In this case, the stereo optical system consists of two optical systems, each containing a first lens group, arranged so that the first lens groups are in parallel. Each of these two optical systems has one or more first optical elements that bend the optical path from the first lens group, and a second optical element that is positioned closer to the image than the first optical element closest to the image, and that branches the optical path into multiple optical paths. Each first lens group includes an aperture diaphragm S and a focusing group.

[0051] The following shows Numerical Examples 1 to 3. In each numerical example, the surface number i indicates the order of the surface when counted from the object side. r is the radius of curvature (mm) of the i-th surface from the object side, d is the lens thickness or air gap on the optical axis between the i-th and (i + 1)-th surfaces (mm), and nd is the refractive index of the optical material between the i-th and (i + 1)-th surfaces at the d-line. νd is the Abbe number of the optical material between the i-th and (i + 1)-th surfaces with respect to the d-line. The Abbe number νd with respect to the d-line is expressed as νd = (Nd - 1) / (NF - NC), where Nd, NF, and NC are the refractive indices of the Fraunhofer lines d (587.6 nm), F (486.1 nm), and C (656.3 nm), respectively.

[0052] d, focal length (mm), F-number, and semi-angle (°) are all values in the infinitely focused state. BF represents the back focus (mm). The back focus is the distance on the optical axis from the most image-side lens surface (the final surface) to the paraxial image plane, expressed in terms of the air-equivalent length. The overall lens length is the length obtained by adding the back focus to the distance on the optical axis from the most object-side lens surface (the front surface) to the final surface of the optical system.

[0053] The "*" attached to the surface number means that the surface has an aspherical shape. The aspherical shape is expressed by the following formula when X is the displacement amount from the surface vertex in the optical axis direction, H is the height from the optical axis in the direction orthogonal to the optical axis, the direction of light propagation is positive, R is the paraxial radius of curvature, K is the conic constant, and A4, A6, A8, A10 are the aspherical coefficients. The "e±xx" of the conic constant and aspherical coefficients means ×10 12 , 8 , 10 , 4 , 6 , 2 , 1 / 2 , ±xx , 2 is meant.

[0054] X=(H 2 / R) / [1+{1-(1+K)(H / R) 2} 1 / 2 +A4×h 4 +A6×h 6 +A8×h 8 +A10×h 10 +A12×h 12 [Numerical Example 1] Unit: mm ​ Surface data Face number rd nd νd 1 58.960 2.50 2.00100 29.1 2 19.260 12.58 3 128.130 2.00 2.00069 25.5 4 35.789 7.47 5 -35.180 1.50 2.00100 29.1 6 35.840 1.88 7 70.612 13.31 1.74000 28.3 8 -15.913 1.50 1.75500 52.3 9 -29.744 1.57 10 96.467 10.75 1.51742 52.4 11 -25.100 1.50 2.00069 25.5 12 -29.032 9.44 13* -21.280 1.05 2.00100 29.1 14 35.263 6.79 1.51742 52.4 15 -21.761 9.61 16 (aperture) ∞ 2.00 17 182.035 4.21 1.71736 29.5 18 -39.049 2.00 19 ∞ 16.04 1.51633 64.1 20 ∞ 16.04 1.51633 64.1 21 ∞ 16.04 1.51633 64.1 22 ∞ 16.04 1.51633 64.1 23 ∞ 1.00 24 25.707 14.34 1.43875 94.7 25 -56.775 0.46 26 -66.697 1.70 2.00100 29.1 27 24.577 11.14 1.43875 94.7 28 -85.408 0.20 29 65.673 7.80 1.43875 94.7 30 -231.395 0.20 31 31.585 16.16 1.43875 94.7 32 -39.217 1.70 1.87070 40.7 33 -106.953 15.07 Image plane ∞ Aspherical data Page 13 K = 0.00000e+00 A 4= 9.63772e-06 A 6= 3.80437e-08 A 8= 4.11555e-13 A10 = -3.99834e-14 Various data Focal length 10.90 F-number 2.91 Half-angle (°): 95.00 Image height 18.00 Lens length: 225.60 BF 15.07 Lens group data Group Starting plane Ending plane Focal length L1 1 18 24.64 L1A 10 12 49.16 L2-1 24 33 69.68 [Numerical Example 2] Unit: mm Surface data Face number rd nd νd 1 43.749 1.95 2.00100 29.1 2 14.861 8.41 3* -174.867 1.30 2.00100 29.1 4 24.881 6.96 5 -16.683 1.30 2.00100 29.1 6 -296.826 0.37 7 -180.603 9.76 1.75211 25.0 8 -19.291 0.19 9 58.407 1.30 1.96300 24.1 10 29.267 1.80 11 32.899 11.99 1.53172 48.8 12 -17.423 1.30 1.49700 81.5 13 -46.042 0.65 14* 69.188 4.78 1.62041 60.3 15 -36.922 0.98 1.51633 64.1 16 49.355 24.47 17 (aperture) ∞ 1.95 18 ∞ 8.83 1.51633 64.1 19 ∞ 8.83 1.51633 64.1 20 ∞ 1.30 21 35.125 0.97 1.65160 58.5 22 15.583 3.28 1.49700 81.5 23 -49.533 0.19 24 ∞ 8.83 1.51633 64.1 25 ∞ 8.83 1.51633 64.1 26 ∞ 6.48 27 26.820 5.77 1.43875 94.7 28 -22.721 0.19 29 -75.166 4.18 1.43875 94.7 30 -16.807 1.30 1.87070 40.7 31 21.259 0.48 32 22.993 6.01 1.43875 94.7 33 -42.175 0.19 34 20.791 11.66 1.43875 94.7 35 -18.205 1.10 1.95375 32.3 36 -28.909 8.77 Image plane ∞ Aspherical data 3rd page K = 0.00000e+00 A 4= 4.36079e-06 A 6=-5.43863e-08 A 8= 1.42166e-10 A10 = -1.96625e-13 Side 14 K = 0.00000e+00 A 4=-1.52652e-06 A 6= 9.29124e-09 A 8=-3.92721e-11 A10 = 8.37057e-14 Various data Focal length 7.05 F-number 2.91 Half-angle (°): 95.00 Image height 11.70 Lens length: 166.71 BF 8.77 Lens group data Group Starting plane Ending plane Focal length L1 1 17 -45.66 L1A 14 16 622.90 LM 21 23 54.14 L2-1 27 36 47.41 [Numerical Example 3] Unit: mm Surface data Face number rd nd νd 1 61.892 2.50 2.00100 29.1 2 18.845 12.30 3 96.205 2.00 2.00100 29.1 4 33.863 9.08 5 -25.497 1.50 1.80400 46.5 6 55.942 1.39 7 107.758 10.22 1.84666 23.8 8 -28.587 5.75 9 1065.446 1.50 2.00100 29.1 10 22.701 8.60 1.53172 48.8 11 -107.956 4.29 12 4355.929 9.58 1.53172 48.8 13 -14.863 1.50 1.72916 54.7 14 -20.340 3.62 15* -17.902 1.05 2.00100 29.1 16 75.458 7.44 1.51742 52.4 17 -19.147 10.00 18 192.746 2.00 2.00069 25.5 19 60.263 10.13 1.72825 28.5 20 -37.726 2.00 21 (aperture) ∞ 2.00 22 ∞ 16.74 1.51633 64.1 23 ∞ 16.74 1.51633 64.1 24 ∞ 16.74 1.51633 64.1 25 ∞ 16.74 1.51633 64.1 26 ∞ 16.74 1.51633 64.1 27 ∞ 16.74 1.51633 64.1 28 ∞ 1.00 29 25.774 11.39 1.43875 94.7 30 -83.126 0.15 31 -144.020 2.00 2.00100 29.1 32 31.298 2.07 33 44.533 13.15 1.43875 94.7 34 -24.083 2.00 1.87070 40.7 35 -119.868 0.20 36 147.604 9.71 1.43875 94.7 37 -35.095 0.20 38 38.964 17.12 1.43875 94.7 39 -28.428 1.70 1.87070 40.7 40 -57.958 15.07 Image plane ∞ Aspherical data Page 15 K = 0.00000e+00 A 4= 4.41006e-06 A 6= 3.09378e-08 A 8= 2.42081e-11 A10 = 5.76305e-13 Various data Focal length 10.90 F-number 2.91 Half-angle (°): 95.00 Image height 18.00 Lens length: 284.68 BF 15.07 Lens group data Group Starting plane Ending plane Focal length L1 1 21 17.79 L1A 12 14 43.33 L2-1 29 40 73.36 The values ​​of equations (1) to (5) for numerical examples 1 to 3 are summarized in Table 1. The optical systems in each numerical example satisfy all the conditions of equations (1) to (5).

[0055] [Table 1]

[0056] The above embodiments include the following configuration.

[0057] (Composition 1) A stereo imaging system comprising two imaging devices, each having an optical system including a first lens group, arranged such that the first lens groups are in parallel, The optical systems of each of the two imaging devices are A first optical element that branches the optical path from the first lens group into a first optical path extending in a direction different from the optical axis direction of the first lens group and a second optical path extending in a direction different from the first optical path, A second lens group arranged on the first optical path and having a positive refractive power toward the first imaging plane, A second optical element that bends the second optical path, It comprises a third lens group arranged on the second optical path bent by the second optical element and having a positive refractive power toward the second imaging plane, A stereo imaging system characterized in that the bending direction of the second optical path by the second optical element in each of the two imaging devices is different from that of the other two imaging devices. (Configuration 2) The stereo imaging system according to configuration 1, characterized in that the second optical path from the first optical element to the second optical element extends in the direction of the optical axis of the first lens group. (Composition 3) The stereo imaging system according to configuration 1 or 2, characterized in that the bending directions of the second optical path by the second optical element in each of the two imaging devices are in opposite directions. (Composition 4) When D1 is the distance along the optical axis from the lens surface closest to the object in the first lens group to the lens surface closest to the image in the first lens group, and f is the focal length of the optical system, 7.50 ≤ D1 / f ≤ 16.00 A stereo imaging system according to any one of configurations 1 to 3, characterized by satisfying the following conditions. (Composition 5) When the focal lengths of the second lens group and the third lens group are f2, and the focal length of the optical system is f, 5.71 ≤ f² / f ≤ 7.82 A stereo imaging system according to any one of configurations 1 to 4, characterized in that it satisfies the following conditions. (Composition 6) When D2 is the distance along the optical axis from the surface that bends the second optical path in the second optical element to the first and second imaging surfaces, and f is the focal length of the optical system, 5.00 ≤ D2 / f ≤ 7.44 A stereo imaging system according to any one of configurations 1 to 5, characterized in that it satisfies the following conditions. (Composition 7) When DM is the distance along the optical axis from the surface in the first optical element that branches the optical path to the surface in the second optical element that bends the optical path, and f is the focal length of the optical system, 2.47 ≤ DM / f ≤ 8.22 A stereo imaging system according to any one of configurations 1 to 6, characterized in that it satisfies the following conditions. (Composition 8) When DS is the distance along the optical axis from the aperture diaphragm to the first and second imaging planes, and f is the focal length of the optical system, 11.87 ≤ DS / f ≤ 20.01 A stereo imaging system according to any one of configurations 1 to 7, characterized in that it satisfies the following conditions. (Composition 9) A stereo imaging system comprising two imaging devices, each having an optical system including a first lens group, arranged such that the first lens groups are in parallel, The optical systems of each of the two imaging devices are A first optical element that branches the optical path from the first lens group into a first optical path extending toward a first imaging plane in a direction different from the optical axis direction of the first lens group and a second optical path extending in a direction different from the first optical path, It has a second optical element that bends the second optical path toward the second imaging plane, A stereo imaging system characterized in that the bending direction of the second optical path by the second optical element in each of the two imaging devices is different from that of the other two imaging devices. (Composition 10) A stereo optical system having two optical systems, each including a first lens group, and arranged so that the first lens groups are in parallel, The two aforementioned optical systems are, A first optical element that branches the optical path from the first lens group into a first optical path extending in a direction different from the optical axis direction of the first lens group and a second optical path extending in a direction different from the first optical path, A second lens group arranged on the first optical path and having a positive refractive power toward the first image plane, A second optical element that bends the second optical path, It comprises a third lens group arranged on the second optical path bent by the second optical element and having a positive refractive power toward the second image plane, A stereo optical system characterized in that the bending direction of the second optical path by the second optical element in each of the two imaging devices is different from that of the other two imaging devices. (Composition 11) The stereo optical system according to configuration 10, characterized in that the second optical path from the first optical element to the second optical element extends in the direction of the optical axis of the first lens group. (Composition 12) The stereo optical system according to configuration 10 or 11, characterized in that the bending directions of the second optical path by the second optical element in each of the two optical systems are in opposite directions. (Composition 13) A stereo optical system having two optical systems, each including a first lens group, and arranged so that the first lens groups are in parallel, The two aforementioned optical systems are, A first optical element that branches the optical path from the first lens group into a first optical path extending toward a first image plane in a direction different from the optical axis direction of the first lens group and a second optical path extending in a direction different from the first optical path, It has a second optical element that bends the second optical path toward the second image plane, A stereo optical system characterized in that the bending direction of the second optical path by the second optical element in each of the two imaging devices is different from that of the other two imaging devices. (Composition 14) An imaging device characterized by having a stereo optical system as described in any one of configurations 10 to 13.

[0058] The embodiments described above are merely representative examples, and various modifications and changes can be made to each embodiment when implementing the present invention. [Explanation of Symbols]

[0059] L1 First lens group L21 2-1 lens group (2nd lens group) L22 2nd-2nd lens group (3rd lens group) 121 First optical elements 122 Second Optical Related 131,132 Image sensors

Claims

1. A stereo imaging system comprising two imaging devices, each having an optical system including a first lens group, arranged such that the first lens groups are in parallel, The optical systems of each of the two imaging devices are A first optical element that branches the optical path from the first lens group into a first optical path extending in a direction different from the optical axis direction of the first lens group and a second optical path extending in a direction different from the first optical path, A second lens group arranged on the first optical path and having a positive refractive power toward the first imaging plane, A second optical element that bends the second optical path, It comprises a third lens group arranged on the second optical path bent by the second optical element and having a positive refractive power toward the second imaging plane, A stereo imaging system characterized in that the bending direction of the second optical path by the second optical element in each of the two imaging devices is different from that of the other two imaging devices.

2. The stereo imaging system according to claim 1, characterized in that the second optical path from the first optical element to the second optical element extends in the direction of the optical axis of the first lens group.

3. The stereo imaging system according to claim 1, characterized in that the bending directions of the second optical path by the second optical element in each of the two imaging devices are in opposite directions to each other.

4. When D1 is the distance along the optical axis from the lens surface closest to the object in the first lens group to the lens surface closest to the image in the first lens group, and f is the focal length of the optical system, 7.50 ≤ D1 / f ≤ 16.00 The stereo imaging system according to claim 1, characterized in that it satisfies the following conditions.

5. When the focal lengths of the second lens group and the third lens group are f2, and the focal length of the optical system is f, 5.71 ≤ f² / f ≤ 7.82 The stereo imaging system according to claim 1, characterized in that it satisfies the following conditions.

6. When D2 is the distance along the optical axis from the surface that bends the second optical path in the second optical element to the first and second imaging surfaces, and f is the focal length of the optical system, 5.00 ≤ D² / f ≤ 7.44 The stereo imaging system according to claim 1, characterized in that it satisfies the following conditions.

7. When DM is the distance along the optical axis from the surface in the first optical element that branches the optical path to the surface in the second optical element that bends the optical path, and f is the focal length of the optical system, 2.47 ≤ DM / f ≤ 8.22 The stereo imaging system according to claim 1, characterized in that it satisfies the following conditions.

8. When DS is the distance along the optical axis from the aperture diaphragm to the first and second imaging planes, and f is the focal length of the optical system, 11.87 ≤ DS / f ≤ 20.01 The stereo imaging system according to claim 1, characterized in that it satisfies the following conditions.

9. A stereo imaging system comprising two imaging devices, each having an optical system including a first lens group, arranged such that the first lens groups are in parallel, The optical systems of each of the two imaging devices are A first optical element that branches the optical path from the first lens group into a first optical path extending toward a first imaging plane in a direction different from the optical axis direction of the first lens group and a second optical path extending in a direction different from the first optical path, It has a second optical element that bends the second optical path toward the second imaging plane, A stereo imaging system characterized in that the bending direction of the second optical path by the second optical element in each of the two imaging devices is different from that of the other two imaging devices.

10. A stereo optical system having two optical systems, each including a first lens group, and arranged so that the first lens groups are in parallel, The two optical systems described above are, A first optical element that branches the optical path from the first lens group into a first optical path extending in a direction different from the optical axis direction of the first lens group and a second optical path extending in a direction different from the first optical path, A second lens group arranged on the first optical path and having a positive refractive power toward the first image plane, A second optical element that bends the second optical path, It comprises a third lens group arranged on the second optical path bent by the second optical element and having a positive refractive power toward the second image plane, A stereo optical system characterized in that the bending direction of the second optical path by the second optical element in each of the two optical systems is different from that of the other two optical systems.

11. The stereo optical system according to claim 10, characterized in that the second optical path from the first optical element to the second optical element extends in the direction of the optical axis of the first lens group.

12. The stereo optical system according to claim 10, characterized in that the bending directions of the second optical path by the second optical element in each of the two optical systems are in opposite directions to each other.

13. A stereo optical system having two optical systems, each including a first lens group, and arranged so that the first lens groups are in parallel, The two optical systems described above are, A first optical element that branches the optical path from the first lens group into a first optical path extending toward a first image plane in a direction different from the optical axis direction of the first lens group and a second optical path extending in a direction different from the first optical path, It has a second optical element that bends the second optical path toward the second image plane, A stereo optical system characterized in that the bending direction of the second optical path by the second optical element in each of the two optical systems is different from that of the other two optical systems.

14. An imaging apparatus characterized by having a stereo optical system according to any one of claims 10 to 13.

Images