Optical device, spherical camera, and method for manufacturing the spherical camera

Abstract

To acquire a small and high-quality image by a wide-vision optical device formed by combining a plurality of lens systems (an omnidirectional camera, an optical device for a stereoscopic vision, or a panoramic imaging optical device, for example).SOLUTION: In an optical device having a sensor and a plurality of lens systems, an image circle generated by the lens systems is partially located outside the sensor. The optical device has a plurality of lens systems and the optical axes of the lens systems and straight lines as extended lines of the optical axes do not intersect with one another. Alternatively, the optical device has at least four lens systems and the optical paths intersect with one another.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an optical device suitable for photography with a digital camera, a film camera, a video camera, or the like, an omnidirectional camera, and a method for manufacturing an omnidirectional camera. [Background technology]

[0002] Conventionally, as wide-field optical devices in various fields, omnidirectional cameras (cameras capable of capturing omnidirectional images), stereoscopic optical devices, panoramic imaging optical devices, etc., have been used. In these optical devices, in order to provide high performance with a wide imaging field of view, i.e., a wide angle of view, a high-performance lens system is used or a plurality of lens systems are combined to obtain a plurality of formed images. When a high-performance lens system is used, the overall size of the lens system increases due to an increase in the number of lenses and an increase in the lens diameter due to a wider angle of view. Also, there is a demand for an increase in the number of pixels to obtain high resolution in accordance with the high-performance lens system. When multiple lens systems are combined, the overall size of the optical device tends to increase due to the need to place all of the lens systems in place, and there is a demand for a large number of pixels to be used in order to stitch together the multiple images obtained from the lens systems. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Publication No. 2018 / 0332206 Summary of the Invention

[0004] The omnidirectional camera according to the first embodiment has a plurality of lens systems, and the optical axis of each lens system and a straight line extending from the optical axis do not intersect with each other.

[0005] In addition, the omnidirectional camera according to the second embodiment has four or more lens systems, and optical paths intersect. A space in which no member is disposed is provided at the intersection of the optical paths, and the distance on the optical axis from the surface closest to the object of the lens system to the image forming surface is TL, and the distance on the optical axis from the intersection of the optical paths to the image forming surface is K. The following conditional expression is satisfied: . 0.1 < K / TL < 0.9

[0006] Also, in an optical device according to a third aspect, in an optical device including a sensor and a lens system, a part of the image circle generated by the lens system is outside the sensor.

[0007] Moreover, a celestial sphere camera or optical device according to a fourth aspect receives images formed by a plurality of lens systems with a sensor arranged on the same plane.

[0008] In addition, a manufacturing method for an omnidirectional camera according to a fifth aspect includes the steps of: having a plurality of lens systems and arranging them so that the optical axes of the respective lens systems and the straight lines extending from the optical axes do not intersect; having four or more lens systems and arranging them so that the optical paths intersect; or arranging at least four optical devices each including a sensor and a lens system such that a part of the image circle generated by the lens system is outside the sensor. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic diagram of a celestial sphere camera (regular tetrahedron) according to a first embodiment. [Diagram 2] 1 is an embodiment of a celestial sphere camera (regular tetrahedron) according to a first embodiment. [Diagram 3] 1 is an embodiment of a celestial sphere camera (regular hexahedron) according to a first embodiment. [Figure 4] 1 is an embodiment of a celestial sphere camera (regular dodecahedron) according to the first embodiment. [Diagram 5] FIG. 1 is an explanatory diagram of a celestial sphere camera (regular tetrahedron) according to a first embodiment. [Figure 6] FIG. 1 is an explanatory diagram of a celestial sphere camera (regular hexahedron) according to a first embodiment. [Figure 7] FIG. 1 is an explanatory diagram of a celestial sphere camera (regular hexahedron) according to a first embodiment. [Figure 8] FIG. 1 is an explanatory diagram of a celestial sphere camera (regular hexahedron) according to a first embodiment. [Figure 9]FIG. 1 is an explanatory diagram of a celestial sphere camera (regular hexahedron) according to a first embodiment. [Figure 10] FIG. 1 is an explanatory diagram of a celestial sphere camera (regular hexahedron) according to a first embodiment. [Figure 11] FIG. 1 is an explanatory diagram of a celestial sphere camera (regular hexahedron) according to a first embodiment. [Figure 12] FIG. 11 is an explanatory diagram of a celestial sphere camera (regular tetrahedron) according to a second embodiment. [Figure 13] FIG. 11 is an explanatory diagram of a celestial sphere camera (regular tetrahedron) according to a second embodiment. [Figure 14] FIG. 11 is an explanatory diagram of a celestial sphere camera (regular tetrahedron) according to a second embodiment. [Figure 15] FIG. 11 is an explanatory diagram of a celestial sphere camera (regular tetrahedron) according to a second embodiment. [Figure 16] 13 is an explanatory diagram of the area ratio of a polygonal shape in an image sensor according to the third embodiment. FIG. [Figure 17] 13 is an explanatory diagram of the area ratio of a regular triangular shape (regular tetrahedron or the like) in an image sensor according to the third embodiment. FIG. [Figure 18] FIG. 11 is an explanatory diagram of the area ratio of a square shape (regular hexahedron) in an image sensor according to the third embodiment. [Figure 19] FIG. 13 is an explanatory diagram of a regular pentagonal shape (regular dodecahedron) in an image sensor according to the third embodiment. [Figure 20] FIG. 13 is an explanatory diagram of an optical device according to a fourth embodiment. [Figure 21] FIG. 13 is an explanatory diagram of an optical device according to a fourth embodiment. [Figure 22] FIG. 13 is an explanatory diagram of an optical device according to a fourth embodiment. [Figure 23] FIG. 11 is a flow diagram showing a manufacturing method 1 of the omnidirectional camera according to the fifth embodiment. [Figure 24] FIG. 13 is a flow diagram showing a second manufacturing method for the omnidirectional camera according to the fifth embodiment. [Diagram 25] FIG. 13 is a flow diagram showing a manufacturing method 3 of the omnidirectional camera according to the fifth embodiment. [Figure 26] FIG. 1 is a cross-sectional view of a lens system according to a first embodiment. [Figure 27]3A to 3C are diagrams showing various aberrations of the lens system according to the first example. [Figure 28] FIG. 11 is a cross-sectional view of a lens system according to a second embodiment. [Figure 29] 7A to 7C are diagrams showing various aberrations of the lens system according to the second example. [Diagram 30] FIG. 11 is a cross-sectional view of a lens system according to a third embodiment. [Diagram 31] 13A to 13C are diagrams showing various aberrations of the lens system according to the third example. [Diagram 32] FIG. 13 is a cross-sectional view of a lens system according to a fourth embodiment. [Diagram 33] 13A to 13C are diagrams showing various aberrations of the lens system according to the fourth example. [Diagram 34] FIG. 13 is a cross-sectional view of a lens system according to a fifth embodiment. [Diagram 35] 13A to 13C are diagrams showing various aberrations of the lens system according to the fifth example. [Diagram 36] FIG. 13 is a cross-sectional view of a lens system according to a sixth example. [Figure 37] 13A to 13C are diagrams illustrating various aberrations in the lens system according to Example 6. [Figure 38] FIG. 13 is a cross-sectional view of a lens system according to a seventh example. [Figure 39] 13A to 13C are diagrams showing various aberrations of the lens system according to the seventh example. [Diagram 40] FIG. 13 is a cross-sectional view of a lens system according to an eighth embodiment. [Diagram 41] 13A to 13C are diagrams illustrating various aberrations of the lens system according to the eighth example. [Diagram 42] FIG. 13 is a cross-sectional view of a lens system according to a ninth example. [Diagram 43] 13A to 13C are diagrams illustrating various aberrations in the lens system according to the ninth example. [Diagram 44] FIG. 19 is a cross-sectional view of a lens system according to a tenth example. [Diagram 45] 15A to 15C are diagrams illustrating various aberrations in the lens system according to the tenth example. [Figure 46] FIG. 19 is a cross-sectional view of a lens system according to an eleventh embodiment. [Figure 47] 15A to 15C are diagrams illustrating various aberrations in the lens system according to the eleventh example. [Figure 48]FIG. 23 is a cross-sectional view of a lens system according to a twelfth embodiment. [Figure 49] 12A to 12C are diagrams showing various aberrations of the lens system according to the twelfth example. [Figure 50] FIG. 23 is a cross-sectional view of a lens system according to a thirteenth embodiment. [Figure 51] 23A to 23C are diagrams showing various aberrations of the lens system according to the thirteenth example. [Figure 52] FIG. 23 is a cross-sectional view of a lens system according to a fourteenth embodiment. [Figure 53] 23A to 23C are diagrams showing various aberrations of the lens system according to the fourteenth example. [Figure 54] FIG. 23 is a cross-sectional view of a lens system according to a fifteenth embodiment. [Figure 55] 23A to 23C are diagrams illustrating various aberrations in the lens system according to the fifteenth example. [Figure 56] FIG. 23 is a cross-sectional view of a lens system according to a sixteenth embodiment. [Figure 57] 23A to 23C are diagrams illustrating various aberrations in the lens system according to the sixteenth example. [Figure 58] Schematic diagrams of common spherical cameras (tetrahedron, cubic prism, and dodecahedron). [Figure 59] FIG. 1 is an explanatory diagram of the maximum angle required to capture a subject from one face of a regular tetrahedron. [Figure 60] FIG. 1 is an explanatory diagram of a pentahedron and a heptahedron. [Figure 61] FIG. 1 is an explanatory diagram of a celestial sphere camera and an optical device. [Figure 62] 1 is a diagram showing the properties of regular polyhedrons. [Figure 63] FIG. 1 is a diagram illustrating a typical tetrahedral sensor arrangement. [Figure 64] This is a diagram showing the layout of a typical lens system arranged on four regular surfaces. (2) shows the lens system in (1) with all lenses except for the lens closest to the object not shown. [Figure 65] FIG. 1 is an explanatory diagram of an optical device that captures images of two lens systems with two sensors. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an optical device, a spherical camera, and a manufacturing method of a spherical camera according to the present embodiment will be described. However, the present invention is not limited to the following embodiments, and any combination may be used. In addition, the reference symbols for the figures according to the embodiments may be used independently for each drawing to avoid complication of the description due to an increase in the number of reference symbols. Therefore, even if a reference symbol common to other drawings is used, it does not necessarily mean that the configuration is common to the other drawings.

[0011] In addition, in the following description of the omnidirectional camera, this specification uses the terms sphere, polyhedron (regular polyhedron, regular tetrahedron, regular hexahedron, regular octahedron, regular dodecahedron, regular icosahedron, triangular prism, etc.), and polygon (regular polygon, equilateral triangle, square, regular pentagon, triangle, quadrangle, rectangle, etc.). However, these terms are used to express imaginary shapes that have no substance, and may not be included as components of the physical objects of each embodiment.

[0012] For example, when shooting a full celestial sphere using two lens systems, each lens system covers a hemisphere, and the shooting area requires at least an angle of view 2ω = 180° (degrees). Hereinafter, the shooting area covered by one lens system is represented as 2ωA, where ω is the half angle of view. In reality, it is necessary to consider the angle of view taking into account parallax, stitching (image joining), manufacturing errors, etc. For example, if the corresponding angle of view is 40°, then the required angle of view is 180°+40°=220°. Hereinafter, this will be represented as 2ωB.

[0013] Generally, when comparing lens systems with the same number of lenses and overall length, the optical performance decreases as the angle of view moves away from that of a standard lens, or as the angle of view of a wide-angle lens becomes wider. At the same time, there is a demand for shooting at higher resolution than ever before, and so high optical performance is required. Therefore, it has been considered to increase the number of lens systems to more than two, thereby narrowing the burden of the angle of view borne by each lens system, that is, narrowing the angle of view.

[0014] First, imagine a sphere and think about dividing it into four or more parts. In this case, it is desirable to divide the sphere so that each part is equal, because by dividing it evenly, the lens system can be shared and the resolution of the resulting image can be made the same.

[0015] For example, as a method for dividing a sphere evenly, consider a virtual regular polyhedron inside the sphere. There are five regular polyhedrons: a regular tetrahedron, a regular cube, a regular octahedron, a regular dodecahedron, and a regular icosahedron. One lens system can be assigned to each surface, and Figure 58 shows examples of lens systems arranged on such regular polyhedrons: a regular tetrahedron (see Figure 58(1)), a regular cube (see Figure 58(2)), and a regular dodecahedron (see Figure 58(3)). Let us now consider the regular tetrahedron shown in Fig. 59. Fig. 59 shows a regular tetrahedron inscribed in a sphere (not shown), and the maximum angle (ω = angle HOB in Fig. 59) seen from the center O of the sphere to the face CBD of the regular tetrahedron is 2ωA = 141.06°. This angle is also common to all faces of a regular tetrahedron.

[0016] Next, instead of dividing the sphere evenly, it is also possible to divide the sphere so that the angle of view of each lens system is common. A triangular prism is an example of a non-regular polyhedron. Of the five faces of a triangular prism, two are triangular and the third is a quadrangle. The quadrangle should be a rectangle with the ratio of the short side to the long side set to 1:√3. The triangle should be an equilateral triangle with a common side as the long side of the quadrangle, so the ratio of the side lengths is √3. In this case, 2ωA=126.87° (see Figure 60(1)). Similarly, in the case of a pentagonal prism, two faces are pentagons and the fifth face is a quadrangle. The quadrangle is a rectangle, and the ratio of the short side to the long side is (1+√5):(10-2√5). In this case, 2ωA=102.1° (see Figure 60(2)).

[0017] In this way, by imagining a polyhedron inside a sphere and assigning a lens system to each face of the polyhedron, it is possible to divide the sphere into four or more parts. Specifically, a sphere is first imagined, and a virtual polyhedron is placed inside the imagined sphere, and one lens system is assigned to each of all the faces of the polyhedron. Furthermore, in order to capture all the light beams incident on the surface assigned to each lens system, it is possible to assign multiple lens systems to create a spherical camera by arranging the lens systems so that, for example, the axis perpendicular to the surface is the optical axis, the outside of the sphere is the object side, and the inside of the sphere is the image side. In this case, for example, the lens systems can be arranged so that the optical axes of all the lens systems and straight lines extending from these optical axes intersect at the center of gravity (geometric center) of the polyhedron, or the lens systems can be arranged so that the optical axes of all the lens systems and straight lines extending from these optical axes pass through the center of gravity of each face of the polyhedron.

[0018] Next, the omnidirectional camera will be described with reference to FIG. In this specification, an entity equipped with a lens system and a sensor is referred to as an optical device, and an omnidirectional camera is composed of one optical device or multiple optical devices. However, even if it is an optical device, it may be referred to as a lens system when explaining its characteristics as a lens system (e.g., optical axis, etc.). FIG. 61 is a diagram showing an example of the configuration of a celestial sphere camera CAM equipped with an optical device OL.

[0019] As shown in FIG. 61, the omnidirectional camera CAM is equipped with an optical device OL having a lens system 2 and a sensor 3, and three optical devices in common with the optical device OL, for a total of four optical devices. The photographing principle of the optical device OL will be explained below, but the explanation of the other three optical devices that share the same photographing principle will be omitted.

[0020] In the omnidirectional camera CAM, light from an object (subject) (not shown) is collected by a lens system 2 and forms a subject image on an imaging surface of a sensor 3 via an OLPF (Optical low pass filter) (not shown). Then, a photoelectric conversion element provided in the sensor 3 photoelectrically converts the subject image to generate an image of the subject. This image is joined with images from the other three optical devices by an image processing device (not shown) provided in the omnidirectional camera CAM to generate a omnidirectional image. The omnidirectional image is sent to a display device (not shown) via an electric communication line. The photographer can observe the subject via a display device or the like. In addition, when the photographer presses a release button (not shown), the image of the subject generated by the sensor 3 is joined with images from the other three optical devices to generate a omnidirectional image, which is stored in a memory (not shown). In this way, the photographer can photograph the subject using the omnidirectional camera CAM.

[0021] Although an example of a celestial sphere camera corresponding to a regular tetrahedron has been described as the celestial sphere camera CAM, the configuration, functions, etc. of the optical device of a celestial sphere camera corresponding to another polyhedron are similar, so description thereof will be omitted. Also, the optical device and the celestial sphere camera are not limited to those having the above configuration.

[0022] Here, consider the polygons that make up the polyhedron. As shown in Figure 62, each face of a regular tetrahedron, regular octahedron, and regular icosahedron is made up of a regular triangle, each face of a regular cubic hexahedron is made up of a regular quadrilateral, and each face of a regular dodecahedron is made up of a regular pentagon. This also applies to the shape of the image required by the lens system assigned to each face of the polyhedron. In other words, the images of a regular tetrahedron, regular octahedron, and regular icosahedron are equilateral triangles, the images of a regular hexahedron are equilateral quadrilaterals, and the images of a regular dodecahedron are equilateral pentagons. As for the lens system, the maximum angle at which each face of a polyhedron is viewed is 141.1 degrees for a regular tetrahedron, 109.5 degrees for a regular cubic hedron, 109.5 degrees for a regular octahedron, 74.8 degrees for a regular dodecahedron, and 74.8 degrees for a regular icosahedron, as shown in Figure 62.

[0023] (First and second forms) Several known techniques have been disclosed so far regarding the arrangement of lens systems in a polyhedral configuration, but no arrangement suitable for miniaturization has been disclosed. First, the arrangement of the lens system in the regular tetrahedral configuration will be described.

[0024] In the case of a regular tetrahedron, when the optical axes of the four lens systems assigned to each face or the straight lines extending from those optical axes intersect at the center O of the regular tetrahedron as shown in Figure 63(1), it is necessary to provide a space in the center to prevent the sensors from touching each other. To explain this, first consider the equilateral triangular faces that make up a regular tetrahedron as shown in Figure 63(2).

[0025] In Figure 63(2), where the image circle IC is positioned in the usual way relative to the position of the sensor IS, the short side of the sensor IS is inscribed in the image circle IC, and an equilateral triangle A is positioned outside the image circle IC. In this case, the centers C of the image circle IC, sensor IS, and equilateral triangle A all coincide. By considering a regular tetrahedron whose all faces are equilateral triangles A like this, the sensors are positioned inside the equilateral triangles, preventing contact between the sensors. However, it is not possible to place a sensor inside a regular tetrahedron constructed in this way. In other words, the lens system would be far from the center of the regular tetrahedron, and the entire spherical camera would become large (see Fig. 58(1), Fig. 63(1), Fig. 64).

[0026] In addition, in the case of an optical device arrangement in a regular hexahedron, when six optical axes or lines extending from the optical axes intersect at the center as shown in Fig. 58(2), it is necessary to provide a space in the center so that the sensors do not come into contact with each other, and it is not possible to place optical devices or sensors inside the hexahedron, as in the case of a regular tetrahedron. In other words, the optical device will be far from the center of the regular hexahedron, and will become larger. Furthermore, in the case of an optical device arrangement in a regular dodecahedron, when 12 optical axes or lines extending from the optical axes intersect at the center as shown in Figure 58(3), it is necessary to provide a space in the center so that the sensors do not come into contact with each other, and it is not possible to place optical devices or sensors inside the regular dodecahedron, as is the case with regular tetrahedrons and regular hexahedrons. In other words, the optical device will be far from the center of the regular dodecahedron, and will become larger. Similarly, regular octahedrons and regular icosahedrons are also becoming larger. Therefore, the omnidirectional camera of the first embodiment is configured as follows.

[0027] <Embodiment 1> The omnidirectional camera according to the first embodiment has a plurality of lens systems, and the optical axis of each lens system and the straight lines extending from the optical axes do not intersect with each other. With this configuration, image quality can be improved and the entire omnidirectional camera can be made smaller despite having multiple lens systems. Fig. 1 is a schematic diagram showing that the optical axes of the four lens systems and the straight lines extending from the optical axes (hereinafter referred to as "optical axes") do not intersect. Fig. 2 shows two embodiments of Fig. 1. In this way, in the case of a regular tetrahedron, the four optical axes do not intersect at the center O, so there is no need to provide space in the center to prevent the sensors from touching each other, and the entire spherical camera can be made smaller.

[0028] Similarly, in the case of a regular hexahedron, as shown in Figures 3(1), 3(2), and 3(3), the six optical axes do not intersect at the center, so there is no need to provide space in the center to prevent the sensors from touching each other, making it possible to miniaturize the entire spherical camera. Furthermore, in the case of a regular dodecahedron, as shown in Fig. 4, the 12 optical axes do not intersect at the center O, so there is no need to provide space in the center to prevent the sensors from touching each other, and the entire spherical camera can be made smaller. By adopting the above configuration for other polyhedrons as well, it becomes possible to reduce the size of the entire omnidirectional camera.

[0029] In the omnidirectional camera according to the first embodiment, it is desirable that the number of the lens systems be four or more. With this configuration, it is possible to obtain high quality images using four or more lens systems while still achieving compactness.

[0030] In the omnidirectional camera according to the first embodiment, the number of lens systems is preferably 4, 6, 8, 12, or 20. With this configuration, it is possible to realize a celestial sphere camera having an appropriate number of lens systems corresponding to regular polyhedrons, that is, a regular tetrahedron, a regular hexahedron, a regular octahedron, a regular dodecahedron, and a regular icosahedron.

[0031] In the omnidirectional camera according to the first embodiment, it is desirable that all of the lens systems are the same lens system. This configuration allows the same materials and processing mechanisms to be used for all lens systems, making assembly and adjustment work simple and efficient production. In addition, because the lens system specifications and aberrations are all the same, control and stitching are easier, and processing speed is improved. Furthermore, the simple configuration contributes to compact size and high image quality.

[0032] It is desirable for the omnidirectional camera according to the first embodiment to include four of the lens systems having a maximum angle of view of 140 degrees or more, eight of the lens systems having a maximum angle of view of 109 degrees or more, twelve of the lens systems having a maximum angle of view of 74 degrees or more, or twenty of the lens systems having a maximum angle of view of 74 degrees or more.

[0033] With this configuration, it is possible to realize a celestial sphere camera having an appropriate lens system corresponding to each of a regular tetrahedron, a regular octahedron, a regular dodecahedron, and a regular icosahedron. A specific description will be given below for a regular tetrahedron, a regular octahedron, a regular dodecahedron, and a regular icosahedron.

[0034] (regular tetrahedron) In the case of a regular tetrahedron, it is desirable to have four of the above lens systems, each with a maximum angle of view of 140 degrees or more. With this configuration, it is possible to obtain high-quality images using an appropriate lens system that corresponds to the regular tetrahedron, and also to reduce the size of the entire omnidirectional camera. If the maximum angle of view is less than 140 degrees, it will not be possible to capture an image with a field of view necessary to compose an appropriate image as a spherical camera. A maximum angle of view of 150 degrees or more is preferable since it has a favorable effect on parallax and manufacturing errors. If the maximum angle of view is 160 degrees or more, the stitching effect can be further improved, which is preferable.

[0035] For example, consider a regular hexahedron ABDCHEGF that shares vertices (A, D, E, F) with the regular tetrahedron when the four optical axes (GA, FB, HD, EC) of the four lens systems (not shown) assigned to each surface of the regular tetrahedron ADEF intersect at the center O of the regular tetrahedron as shown in Figure 5 (1). Suppose that only the vertices (A, B, D, C) of the four optical axes located in the square on the top surface of the regular hexahedron are moved clockwise to the midpoints (a, b, d, c) of the sides of the square as viewed from directly above (see Figure 5 (2)). In this case, the angle of view required for each of the four lens systems is at least 2ωA = 157.8°. This results in an arrangement in which the four optical axes do not intersect at the center, making it possible to miniaturize the entire omnidirectional camera, for example, as shown in Figure 1. Figure 2 (1) shows this embodiment. In order to prevent the optical axis of the lens system and the straight line extending from the optical axis from intersecting, the vertices (A, B, D, C) of the optical axis located on the square on the top surface of the regular hexahedron are not limited to being moved to the midpoints (a, b, d, c) of the sides of the square, but may be moved to a location other than the midpoints by making the movement amount on each side common, or may not be common to each side. Figure 2 (2) shows this embodiment.

[0036] (Eight sides) In the case of a regular octahedron, it is desirable to have eight of the above lens systems, each having a maximum angle of view of 109 degrees or more. With this configuration, it is possible to obtain high-quality images using an appropriate lens system that corresponds to the regular octahedron, and also to reduce the size of the entire omnidirectional camera. If the maximum angle of view is less than 109 degrees, it will not be possible to capture the field of view image required to compose an appropriate image as an omnidirectional camera. A maximum angle of view of 120 degrees or more is preferable since it has a favorable effect on parallax and manufacturing errors. If the maximum angle of view is 140 degrees or more, the stitching effect can be further improved, which is preferable.

[0037] (Twelve faces) In the case of a regular dodecahedron, it is desirable to have twelve of the above lens systems, each with a maximum angle of view of 109 degrees or more. With this configuration, a high-quality image can be obtained using an appropriate lens system that corresponds to a regular dodecahedron, and the entire omnidirectional camera can be made compact. If the maximum angle of view is less than 109 degrees, it will not be possible to capture the field of view image required to compose an appropriate image as an omnidirectional camera. A maximum angle of view of 120 degrees or more is preferable since it has a favorable effect on parallax and manufacturing errors. If the maximum angle of view is 140 degrees or more, the stitching effect can be further improved, which is preferable.

[0038] (20 faces) In the case of a regular icosahedron, it is desirable to have 20 of the above lens systems, each with a maximum angle of view of 74 degrees or more. With this configuration, a high-quality image can be obtained using an appropriate lens system that corresponds to the regular icosahedron, and the entire omnidirectional camera can be made compact. If the maximum angle of view is less than 74 degrees, it will not be possible to capture the field of view image required to compose an appropriate image as an omnidirectional camera. A maximum angle of view of 90 degrees or more is preferable since it has a favorable effect on parallax and manufacturing errors. If the maximum angle of view is 100 degrees or more, the stitching effect can be further improved, which is preferable.

[0039] (Six sides) The omnidirectional camera according to the first embodiment preferably includes six of the lens systems, each having a maximum angle of view of 109 degrees or more. With this configuration, a high-quality image can be obtained using an appropriate lens system that corresponds to a regular hexahedron, and the entire omnidirectional camera can be made compact. If the maximum angle of view is less than 109 degrees, it will not be possible to capture the field of view image required to compose an appropriate image as an omnidirectional camera. A maximum angle of view of 120 degrees or more is preferable since it has a favorable effect on parallax and manufacturing errors. If the maximum angle of view is 140 degrees or more, the stitching effect can be further improved, which is preferable.

[0040] In the case of a regular hexahedron, for example, consider translating each optical device along the optical axis passing through the center of gravity of the regular hexahedron and the line extending from the optical axis (hereinafter referred to as the "optical axis"). Figure 3(1) shows the optical device of Figure 58(2) where the optical axes intersect, translated in a direction perpendicular to the optical axis. If left in this state, it does not yet contribute to miniaturization, but by translating the optical axis as shown in Figures 3(2) and 3(3) and then moving the optical devices closer to each other in the optical axis direction, miniaturization can be achieved.

[0041] This will be described in detail with reference to FIGS. Usually, a lens system suitable for an omnidirectional camera has a wide angle of view, and the object side of the lens closest to the object has the largest maximum effective diameter in the entire lens system. If this maximum effective diameter is φ1, then as shown in Figure 6(1), for example, a virtual cylinder (hereinafter referred to as "cylinder") can be imagined with φ1 as the diameter of the bottom and the length SL in the optical axis direction as the height, and the lens system and optical device (or part thereof) can be placed inside it. FIG. 6(2) and FIG. 7(1) are oblique views of such a cylinder with a lens system disposed inside. Next, if we assume that all the lens systems constituting the regular hexahedron are similar cylinders, in order to realize a spherical camera, it is possible to move them as shown in (1) to (3) of Figures 3, as described above.

[0042] Specifically, as shown in Fig. 7(2), for example, the optical axis x passing through the center of gravity of a regular hexahedron is translated in the vertical direction by a distance k to become the optical axis x', which is an axis of a cylinder (lens system), and such translation is performed for all cylinders, and further, the entire cylinder (lens system) is moved in the optical axis direction so that the positions of the centers of gravity of all cylinders, or positions on the optical axis that are separated by TL / 2 from the lens surface closest to the object, approach each other within a range where the cylinders do not interfere with each other, when the distance on the optical axis from the lens surface closest to the object to the image plane is TL. Note that the above-mentioned "approaching each other" is preferably within 1.5 times the shortest distance between the cylinders or lens systems at which the cylinders do not interfere with each other at the above-mentioned positions, taking into consideration constraints due to various members constituting the omnidirectional camera.

[0043] In addition, in the arrangement of Figure 7 (2), the lengths of φ1 and k are equal, and the length of SL is three times the length of φ1, so in this case there is no interference between the cylinders. In addition, it is no longer necessary to place the sensor in the center of the regular hexahedron, making it possible to reduce the size. When a regular hexahedron is superimposed on Fig. 7(2), it becomes Fig. 7(3), and compared to Fig. 7(4) in which the cylinder has been removed for ease of explanation, for example, the cylinder (a, b, c, d, e, f) in Fig. 7(2) and the components 1, 2, 3, which are divided into three equal parts in order from the object side of the lens system as shown in Fig. 7(1), are arranged as shown in Fig. 8. In the arrangement in Fig. 7(2), SL is three times the length of φ1, but the first embodiment is not limited to this arrangement. Here, the "top" in FIG. 8 refers to the arrangement of the top row when FIG. 7(4) is viewed from above. Also, the "middle" in Figure 8 indicates the layout of the middle row when Figure 7(4) is viewed from above. Furthermore, the "bottom" in Figure 8 refers to the arrangement of the bottom row when Figure 7(4) is viewed from above. For example, it can be understood that "a1" in "top" of Figure 8 is the cylinder "a" in Figure 7(2) which is divided into "1" in Figure 7(1). Also, for example, it can be understood that "e2" in "middle" in Figure 8 is the cylinder of "e" in Figure 7(2) divided into "2" in Figure 7(1). When considering the cylinder (a), the optical system is arranged so that a1 is on the object side and a3 is on the image side. Similarly for the cylinder (b,c,d,e,f), by arranging (b,c,d,e,f)1 on the object side and (b,c,d,e,f)3 on the image side, the six optical systems can obtain images from all the faces of a regular hexahedron. It is also possible to arrange (a,b,c,d,e,f)1 on the image side and (a,b,c,d,e,f)3 on the object side. By arranging the lenses in this way on a regular hexahedron, it is possible to obtain high-quality images using the six lens systems, while also making effective use of the space and appropriately miniaturizing the entire spherical camera.

[0044] The omnidirectional camera according to the first embodiment satisfies the following conditional expression, where TL is the distance on the optical axis from the surface closest to the object of the lens system to the image plane and φ1 is the maximum effective diameter of the object side surface of the lens system closest to the object. 1.0 < TL / φ1 < 5.0 (1)

[0045] Conditional formula (1) is a conditional formula for a lens system for miniaturizing an omnidirectional camera compatible with a regular hexahedron. First, the relationship between the length of TL and the length of SL will be described with reference to FIG. 6 and FIG. For example, in the lens system shown in FIG. 6(1), the length TL is slightly shorter than the length SL of the cylinder, but the difference is not so great that they are almost the same length. If we look at this cylinder from an angle, it looks like Figure 6(2). Assuming that similar cylinders are used for all lens systems constituting a regular hexahedron as described above, an arrangement such as that shown in FIG. 9 can be considered to realize an omnidirectional camera. As shown in FIG. 9, the length SL of the cylinder d is three times as long as φ1, and as described above, the length TL of the lens system shown in FIG. 6(1) is also approximately the same. That is, the value of conditional formula (1) is approximately 3 (TL / φ1≒3). The same is true for the other cylinders, although they are not shown. In this case, all the cylinders fit within the cube (see FIG. 7(4)), so this lens system can be said to be suitable for miniaturizing an omnidirectional camera compatible with a regular hexahedron. Furthermore, if TL is the same length as φ1 as shown in Fig. 9, and TL is t1 and TL is 5 times as long as φ1, then if TL is within the range from t1 to t3, a lens system suitable for miniaturizing an omnidirectional camera compatible with a regular hexahedron can be achieved, and this is shown by conditional formula (1).

[0046] On the other hand, if the upper limit of conditional expression (1) is exceeded, TL of the lens system exceeds t3 described above, and TL becomes longer than necessary with respect to φ1. As a result, the entire omnidirectional camera becomes large. In order to ensure the effect of conditional expression (1), it is preferable to set the upper limit of conditional expression (1) to 4.5, and more preferably to 4.0, and even more preferably to 3.5. In addition, when the lower limit value of conditional formula (1) is exceeded, TL of the lens system becomes less than t1 described above, and the length of the lens system in the optical axis direction becomes shorter than necessary, whereas the amount of parallel movement of the optical axis proportional to φ1 becomes relatively large. As a result, the entire omnidirectional camera becomes large. In order to ensure the effect of conditional expression (1), it is preferable to set the lower limit of conditional expression (1) to 1.5, and it is even more preferable to set the lower limit to 2.0, and 2.5 is even more preferable.

[0047] In the above-described omnidirectional camera configuration, the lengths of φ1 and k are equal, but this is not limiting. As long as 1≦k / φ1 is satisfied, it is included in the first embodiment. In addition, it is desirable for miniaturization that 1≦k / φ1≦7 is satisfied.

[0048] Next, as an appropriate lens system to be used in the entire omnidirectional camera, if the maximum effective diameter of the object side surface of the second lens from the object side is φ2, for example, as shown in Fig. 10(1), a virtual cylinder (hereinafter referred to as "cylinder") can be assumed with φ2 as the diameter of the bottom surface and the length SL in the optical axis direction as the height, and inside it, all or some of the other lenses of the corresponding lens system can be placed, except for the first lens that has the longest maximum effective diameter. In this way, the cylinder can be made thinner than the case where the bottom surface is φ1 as shown in the above-mentioned Fig. 6(1). Furthermore, by arranging the sensor in the same manner as the relationship between k and φ1 in Figure 7(2) described above, making the lengths of φ2 and k equal, and making the length of SL three times the length of φ2, there is no interference between the cylinders and it is no longer necessary to place the sensor in the center of the regular hexahedron, making it possible to further miniaturize the sensor. FIG. 10(2) shows an oblique view of a cylinder with part of a lens system disposed inside it. Here, as shown in 10(2), consider dividing a ray of light into three equal parts 1, 2, 3, in the order of the direction in which it enters the lens system. In this case, the lens system is arranged as shown in FIG. 8, similarly to the lens system shown in FIG. By arranging the lenses in this way on a regular hexahedron, it is possible to obtain high-quality images using the six lens systems, while also making effective use of the space and appropriately miniaturizing the entire spherical camera.

[0049] The omnidirectional camera according to the first embodiment satisfies the following conditional expression, where TL is the distance on the optical axis from the surface nearest to the object side of the lens system to the image plane, and φ2 is the maximum effective diameter of the object side surface of the second lens from the object side of the lens system. 1.0 < TL / φ2 < 10.0 (2)

[0050] Conditional formula (2) is a conditional formula for a lens system to make a spherical camera compatible with a regular hexahedron more compact. First, the relationship between the length of TL and the length of SL will be described with reference to FIG. 10 and FIG. For example, in the lens system shown in FIG. 10(1), TL is longer than the cylinder SL on both the object side and the image side, with SL being three times φ2 and TL being about four times φ2. If we look at this cylinder from an angle, it looks like Figure 10(2). Assuming that the same cylinders are used for all the lens systems that form the regular hexahedron as described above, an arrangement such as that shown in FIG. 11 can be considered to realize an omnidirectional camera. In this case, as shown in FIG. 11, the length t0 of the cylinder d in the object side direction (downward of the paper) is the distance on the optical axis from the object side of the lens closest to the object side to the object side of the lens system. The lens L11d closest to the object side is placed in the region of t0, but this region does not interfere with the adjacent cylinders in the radial direction of the lens, so it can be made larger than φ2. The length SL of the cylinder d is three times as long as φ2, while the length TL is about four times as long as φ2. Although not shown, the other cylinders are similar to the cylinder d. In this case, the value of conditional expression (2) is approximately 4 (TL / φ2 ≈ 4), and as shown in FIG. 11, the object-side lens L11d and the elephant-side portion of the lens system corresponding to cylinder d protrude into the outer region of the cube (see FIG. 7(4)). However, the elephant-side portion of the lens system corresponding to cylinder a, which is arranged point-symmetrically with respect to the center of gravity of the hexahedron, and the object-side lens L11a of the lens system similarly protrude, thereby preventing a portion of the lens system from protruding outside the cube. The relationship between cylinder d and cylinder a is the same as the relationship between cylinder b and cylinder e, and the relationship between cylinder f and cylinder c. In this way, it is possible to prevent any parts from protruding from the cube, and each face of the regular hexahedron is formed in a well-balanced manner, so it can be said that this lens system is suitable for miniaturizing a spherical camera that is compatible with a regular hexahedron. Therefore, if the conditional expression (2) is satisfied, a lens system that is more suitable for miniaturizing an omnidirectional camera that supports a regular hexahedron can be realized.

[0051] On the other hand, if the upper limit value of conditional expression (2) is exceeded, TL becomes longer than necessary with respect to φ2, and as a result, the entire spherical camera becomes large. In order to ensure the effect of conditional expression (2), it is preferable to set the upper limit of conditional expression (2) to 9.0, and more preferably to 8.0, 7.0, or even 6.0. In addition, when the lower limit value of conditional expression (2) is exceeded, TL of the lens system becomes less than φ2, and the length of the lens system in the optical axis direction becomes shorter than necessary, whereas the amount of parallel movement of the optical axis proportional to φ2 becomes relatively large. As a result, the entire omnidirectional camera becomes large. In order to ensure the effect of conditional expression (2), it is preferable to set the lower limit of conditional expression (2) to 2.0, and more preferably 3.0, 4.0, or even 5.0.

[0052] In the above-described omnidirectional camera configuration, the lengths of φ2 and k are equal, but this is not limiting. As long as 1≦k / φ2 is satisfied, it is included in the first embodiment. Furthermore, it is more preferable if 1≦k / φ2≦7 is satisfied.

[0053] In the case of the regular hexahedron described above, a virtual cylinder is assumed with φ1 or φ2 as the diameter of the bottom surface and a height SL that is three times that diameter in the optical axis direction, but the cylinder is not limited to this. If some of the components constituting the lens system or optical device can be accommodated within an imaginary cylinder with the optical axis as its axis and a height (length) three times the diameter of the bottom surface, then for example, the arrangement shown in Fig. 7(2) can be realized, which can be regarded as embodiment 1. In that case, the value of k should be equal to or greater than the diameter of the bottom surface of the cylinder.

[0054] It is desirable for the omnidirectional camera according to the first embodiment to satisfy the following conditional expression, where fa is the focal length from the surface closest to the object of the lens system to the aperture and fb is the focal length from the aperture to the surface closest to the image. -20.0 < fa / fb < 20.0 (3)

[0055] Conditional formula (3) specifies the appropriate power balance between the focal length from the lens system's most object-side surface to the aperture (hereinafter referred to as the "front group") and the focal length from the aperture to the most image-side surface (hereinafter referred to as the "rear group"). If the conditional formula (3) is satisfied, the lens system will be of an appropriate size suitable for an omnidirectional camera with little curvature of field and little distortion, and the entire omnidirectional camera can be made compact by combining this lens system. If the upper limit of conditional formula (3) is exceeded, the refractive power of the rear group will be large relative to the refractive power of the front group, and the lens system will become longer in the optical axis direction, making the entire omnidirectional camera larger. In order to ensure the effect of conditional expression (3), it is preferable to set the upper limit of conditional expression (3) to 15.0, and more preferably to 10.0, 7.0, or even more preferably to 5.0. If the lower limit of condition (3) is exceeded, the refractive power of the rear group becomes small relative to the refractive power of the front group, and as a result, the relative power of the front group becomes too strong, making it difficult to correct aberrations. In particular, the effect on curvature of field becomes significant. In order to ensure the effect of conditional expression (3), it is preferable to set the lower limit of conditional expression (3) to -15.0, and it is even more preferable to set it to -10.0, -7.0, or -5.0.

[0056] It is desirable for the omnidirectional camera according to the first embodiment to satisfy the following conditional expression, where TL is the distance on the optical axis from the surface closest to the object of the lens system to the image plane, and S is the distance on the optical axis from the aperture to the image plane. 0.20 < S / TL < 0.80 (4)

[0057] Condition (4) specifies the position of the aperture in the lens system. If condition (4) is satisfied, it is possible to achieve a lens system in which astigmatism and coma aberration suitable for a spherical camera are well corrected (suppressed). If the lower limit of this condition is not met, coma and astigmatism will increase, which is not preferable. In order to ensure the effect of conditional expression (4), it is preferable to set the lower limit of conditional expression (4) to 0.25, and it is even more preferable to set it to 0.30, 0.35, or even 0.40. If the upper limit of condition (4) is exceeded, coma and astigmatism will also worsen, which is undesirable. In order to ensure the effect of conditional expression (4), it is preferable to set the upper limit of conditional expression (4) to 0.75, and it is even more preferable to set it to 0.70, 0.65, or 0.60.

[0058] The omnidirectional camera of the second embodiment is configured as follows.

[0059] <Embodiment 2> The omnidirectional camera according to the second embodiment has four or more lens systems, and optical paths intersect.

[0060] Regarding the intersection of optical paths, first consider the case where there are three lens systems on a plane. This is shown in a schematic diagram of the optical paths in Figure 12. Figure 12 shows only a simplified optical path through a lens system assigned to three surfaces. In contrast to Fig. 12(1) in which the optical paths of the three lens systems do not intersect and the optical axes intersect at center O, in Fig. 12(2) in which the optical paths of the three lens systems intersect at center O, the size of the optical path of each lens system remains the same but the area occupied by the entire optical path is smaller, so it can be seen that the spherical camera can be made smaller. Specifically, by changing the size of the sphere from CAM1 in Fig. 12(1) to CAM2 in Fig. 12(2), the length ratio is reduced to about 50%, so the area ratio can be reduced to about 25% and the volume ratio to about 12.5%.

[0061] Next, consider a three-dimensional object having four lens systems. With this configuration, for example, as shown in Figures 58, 64, and 13(1), the optical axes of the four lens systems assigned to each surface and the straight lines extending those optical axes (hereinafter referred to as the "optical axes") intersected at the center of the regular tetrahedron, but instead, as the optical paths of the four lens systems intersect as shown in Figures 13(2) and 13(3), after the optical paths intersect, as the optical paths move apart, the distance between the sensors also increases, preventing contact between the sensors and eliminating the need to provide a space in the center of the regular tetrahedron. Here, the optical path intersects in this embodiment 2 means that, of the light incident from the object side, a portion of a light ray passing through a lens system intersects with a portion of a light ray passing through another lens system before reaching the sensor. Note that Figure 13(1) shows the case where the optical paths of the four lens systems do not intersect, Figure 13(2) shows the case where the optical paths of the four lens systems intersect, and Figure 13(3) shows the lenses (one on the object side and one on the image side) and optical axes closest to the intersection of the optical paths in Figure 13(2).

[0062] Furthermore, with this configuration, no components are placed at the points where the optical paths intersect, or components common to each lens system are placed, so that a space (or component) shared by each lens system can be provided, and the space (component) can be used effectively. Also, since the space shared by one lens system is also shared by the other three lens systems, a common space for at least three lens systems is not required. Furthermore, after the optical paths intersect, the distance between the optical axes increases until an image is formed, so that sensors and the like can be placed at locations farther apart from each other, enabling the overall size to be reduced.

[0063] Note that the above explanation is for a regular tetrahedral configuration consisting of four lens systems, but the same can be said for configurations corresponding to polyhedrons other than a regular tetrahedron, and for cases in which there are four or more lens systems corresponding to such polyhedrons.

[0064] The omnidirectional camera according to the second embodiment has four or more lens systems. With this configuration, it is possible to obtain high-quality images using four or more lens systems while still achieving compactness.

[0065] The omnidirectional camera according to the second embodiment has four lens systems arranged in a regular tetrahedron. With this configuration, it is possible to receive all of the light beams incident on the four faces of the regular tetrahedron without any loss, thereby obtaining a high-quality image. Note that adopting a regular tetrahedral arrangement means that an imaginary regular tetrahedron is present inside an imagined sphere, one lens system is assigned to each face of the regular tetrahedron, and the lens system is arranged so that the optical axis is an axis perpendicular to the assigned face, and the outside of the sphere is the object side and the inside of the sphere is the image side.

[0066] In the omnidirectional camera according to the second embodiment, the lens systems are all the same. This configuration allows the same materials and processing mechanisms to be used for all lens systems, and because the configuration of the common parts is the same, it makes the assembly and adjustment work simpler and more efficient, allowing for efficient production. In addition, because the lens system specifications and aberrations are all the same, control and stitching are easier, and processing speed is improved. Furthermore, the simple configuration contributes to compact size and high image quality.

[0067] Furthermore, the omnidirectional camera according to the second embodiment satisfies the following conditional expression, where TL is the distance on the optical axis from the surface closest to the object of the lens system to the image plane, and K is the distance on the optical axis from the point where the optical paths intersect to the image plane. 0.1 < K / TL < 0.9 (5)

[0068] Condition (5) defines an appropriate distance from the point where the optical paths intersect to the image-forming plane. If the condition (5) is satisfied, the omnidirectional camera represented by a polyhedron can be made compact. This will be explained below with reference to FIG. 14 and FIG. Figure 14(1) is a regular octahedron. When viewed from the front as in Figure 14(2), it forms a regular hexagon together with the opposing faces (the shape formed by connecting the vertices ABCDEF is a regular hexagon). If we imagine a cylindrical optical path (G in Fig. 14(2) and Fig. 14(3)) in the direction perpendicular to the paper inside the regular hexagon shown in Fig. 14(2), the optical path intersects with two opposing faces of the regular octahedron, but does not intersect with the other six faces. If this cylinder is placed so that it passes through the vertices of the regular tetrahedron and the center of the face opposite that vertex, it will be shown as in Fig. 15(1). Fig. 15(2) is Fig. 15(1) without the cylinder. It is composed of a regular octahedron with a side length of 1 and four regular tetrahedrons with a side length of 1, and one face of the regular octahedron overlaps with one face of the regular tetrahedron. Overall, it is a regular tetrahedron with a side length of 2. A total of four cylinders are considered that pass through the vertices of such regular tetrahedrons and the center of the face opposite that vertex, and the optical paths do not interfere with each other outside the area of ​​the regular octahedron. In addition, since the cylinder can be considered as part of the optical path of the lens system, the regular octahedral area, which is the common area where the optical paths of such lens systems intersect, can be made of the same medium, such as air or glass, and the optical paths of four lens systems corresponding to a regular tetrahedron can be intersected, making it possible to miniaturize the entire spherical camera. Specifically, for example, the lens system can be configured by arranging a lens that constitutes the lens and another lens adjacent to that lens so that the surface spacing between them corresponds to the distance between two opposing surfaces of a regular octahedron, and by configuring the lens system to intersect with the optical path (optical axis, etc.) of the other lens system at the midpoint of this surface spacing. Conditional expression (5) defines an appropriate distance from the point where the optical paths intersect in a lens system suitable for making such an omnidirectional camera compact to the image plane.

[0069] If the conditional expression (5) is satisfied, the sensor can be disposed away from the center of the regular tetrahedron, and contact between the sensors can be avoided, thereby enabling the omnidirectional camera to be made smaller. If the upper limit of the conditional expression (5) is exceeded, the distance between the lenses disposed on the object side becomes closer, making contact between the lenses on the object side more likely to occur. It is preferable to set the upper limit of the conditional expression (5) to 0.85, and more preferably to 0.8, 0.75, 0.7, 0.65, 0.6, or even 0.55. Furthermore, if the lower limit of conditional formula (5) is not reached, contact between the sensors will easily occur due to the sensors being disposed close to the center of the regular tetrahedron. The lower limit of conditional formula (5) is preferably set to 0.15, and more preferably set to 0.2, 0.25, 0.3, 0.35, 0.4, or even 0.45.

[0070] Moreover, it is desirable for the omnidirectional camera according to the second embodiment to have a maximum angle of view of 140 degrees or more. With this configuration, it is possible to obtain high-quality images using an appropriate lens system that corresponds to the regular tetrahedron, and also to reduce the size of the entire omnidirectional camera. If the maximum angle of view is less than 140 degrees, it will not be possible to capture an image with a field of view necessary to compose an appropriate image as a spherical camera. A maximum angle of view of 150 degrees or more is preferable since it has a favorable effect on parallax and manufacturing errors. If the maximum angle of view is 160 degrees or more, the stitching effect can be further improved, which is preferable.

[0071] Furthermore, in the omnidirectional camera according to the second embodiment, it is desirable to satisfy the following conditional expression, where fa is the focal length from the surface nearest to the object side of the lens system to the diaphragm, and fb is the focal length from the diaphragm to the surface nearest to the image side. -20.0 < fa / fb < 20.0 (6)

[0072] Conditional formula (6) specifies the appropriate power balance between the focal length from the lens system's most object-side surface to the aperture (hereinafter referred to as the "front group") and the focal length from the aperture to the most image-side surface (hereinafter referred to as the "rear group"). If the conditional formula (6) is satisfied, the lens system will be of an appropriate size suitable for a spherical camera with little curvature of field and little distortion, which is preferable. If the upper limit of conditional formula (6) is exceeded, the refractive power of the rear group will be large relative to the refractive power of the front group, and the lens system will become longer in the optical axis direction, making the entire spherical camera larger. In order to ensure the effect of condition (6), it is preferable to set the upper limit of condition (6) to 15.0, and more preferably to 10.0, 7.0, or even 5.0. If the lower limit of condition (6) is exceeded, the refractive power of the rear group becomes small relative to the refractive power of the front group, and as a result, the relative power of the front group becomes too strong, making it difficult to correct aberrations. In particular, the effect on curvature of field becomes significant. In order to ensure the effect of conditional expression (6), it is preferable to set the lower limit of conditional expression (6) to -15.0, and it is even more preferable to set it to -10.0, -7.0, or -5.0.

[0073] Furthermore, in the omnidirectional camera according to the second embodiment, it is desirable to satisfy the following conditional expression, where the maximum diameter of the optical elements adjacent to the part where the optical paths of the lens system intersect is φ3 and the length in the optical axis direction of the part where the optical paths intersect is D. 0.1 < D / φ3 < 10.0 (7)

[0074] Condition (7) defines an appropriate range for the intersection of optical paths in the lens system. If the condition (7) is satisfied, the omnidirectional camera represented by a polyhedron can be made compact. This will be explained below with reference to FIG. 14 and FIG.

[0075] Figure 14(1) is a regular octahedron. When viewed from the front as in Figure 14(2), it forms a regular hexagon together with the opposing faces (the shape formed by connecting the vertices ABCDEF is a regular hexagon). If we assume a cylindrical optical path (G in Fig. 14(2) and Fig. 14(3)) in the direction perpendicular to the paper inside the regular hexagon shown in Fig. 14(2), the optical path intersects two faces of the regular octahedron but does not intersect the other six faces. If this cylinder is placed so that it passes through the vertices of the regular tetrahedron and the center of the face opposite to the vertices, it will be shown as in Fig. 15(1). Fig. 15(2) is Fig. 15(1) without the cylinder. There are a total of four cylinders that pass through the vertices of such a regular tetrahedron and the center of the face opposite to the vertices, and the optical paths of these do not interfere with each other outside the area of ​​the regular octahedron. In addition, since the cylinder is considered to be part of the optical path of the lens system, the area of ​​the regular octahedron, which is the common area where the optical paths of such lens systems intersect, can be made of the same medium, such as air or glass, and the optical paths of the four lens systems corresponding to the regular tetrahedron can be intersected, making it possible to miniaturize the entire omnidirectional camera. Specifically, for example, the lens system can be arranged so that the surface spacing between a lens that constitutes the lens system and another lens adjacent to that lens corresponds to the distance between two opposing surfaces of a regular octahedron, and the surface spacing and the range of the optical path (cylindrical range) can be configured to intersect with the optical path of the other lens systems. Conditional expression (7) defines the relationship with a portion (cylinder) where appropriate optical paths intersect in a lens system suitable for making such an omnidirectional camera compact. In addition, the portion where the optical path intersects can be a portion where the optical path of this embodiment 2 intersects with a part of the optical path of another lens system.

[0076] If the upper limit of condition (7) is exceeded, the length in the optical axis direction of the intersection of the optical paths becomes long while the width of the light beam becomes narrow, making it difficult to reduce the size or causing the image to become dark, resulting in a deterioration in optical performance. The upper limit of condition (7) should preferably be 9.0, and more preferably 8.0, 7.0, or even more preferably 6.0. If the lower limit of condition (7) is exceeded, the length in the optical axis direction of the intersecting optical paths becomes short while the width of the light beam becomes wide, so that the optical paths of the lens system cannot intersect appropriately. The lower limit of condition (7) should preferably be 0.2, and more preferably 0.3, 0.4, or even 0.5.

[0077] Furthermore, in the omnidirectional camera according to the second embodiment, it is desirable to satisfy the following conditional expression, where TL is the distance on the optical axis from the surface closest to the object to the image plane of the lens system, and S is the distance on the optical axis from the aperture to the image plane. 0.20 < S / TL < 0.80 (8)

[0078] Conditional expression (8) specifies the position of the aperture in the lens system. If conditional expression (8) is satisfied, it is possible to achieve a lens system in which astigmatism and coma aberration suitable for a spherical camera are well corrected (suppressed). If the lower limit of this condition is not met, coma and astigmatism will increase, which is not preferable. In order to ensure the effect of condition (8), it is preferable to set the lower limit of condition (8) to 0.25, and it is even more preferable to set it to 0.30, 0.35, or even 0.40. If the upper limit of condition (8) is exceeded, coma and astigmatism will also worsen, which is undesirable. In order to ensure the effect of condition (8), it is preferable to set the upper limit of condition (8) to 0.75, and it is even more preferable to set it to 0.70, 0.65, or 0.60.

[0079] In addition, in the omnidirectional camera according to the second embodiment, it is possible that light may travel along an optical path other than the original optical path at a portion where the optical paths of the lens systems intersect, causing flare or ghosting. Therefore, it is more preferable to provide a wall or a flare cutter around the optical path to block light.

[0080] (Third Form) In general photography, the image circle of a lens system is configured so that its entire area is inside the sensor. Furthermore, the imaging area required by multiple lens systems used in an omnidirectional camera or the like is often polygonal, and such a polygonal imaging area is arranged so as to be inside the image circle of the lens systems. For example, as mentioned above, a regular tetrahedron, regular octahedron, and regular icosahedron are composed of equilateral triangular faces, so the image area required by the lens system corresponding to each face is also an equilateral triangle. However, these equilateral triangles are usually positioned so that they are located inside the image circle IC, which is located inside the sensor IS, as shown in Figure 17(1). 17, 18 and 19, IC is the image circle all of which is inside the sensor, IC' is the image circle of the lens system according to embodiment 3, IS is the sensor, K and K' are the required image formation areas, b is the length of the short side of the image sensor, P is the center of the sensor, O is the center of the image circle all of which is inside the sensor, and O' is the center of the image circle of the lens system according to embodiment 3.

[0081] Similarly, since a regular hexahedron is composed of regular square faces, the image area required by the lens system corresponding to each face is also a regular square. However, these regular squares are usually arranged so that all of their areas are located inside the image circle IC, which is located inside the sensor, as shown in Figure 18(1).

[0082] Similarly, since a regular dodecahedron is composed of regular pentagonal faces, the image formation area required by the lens system corresponding to each face will be a regular pentagon. However, these regular pentagons are usually positioned so that all of their areas are located inside the image circle IC, which is located inside the image sensor, as shown in Figure 19(1).

[0083] Although such a configuration is advantageous in terms of parallax, stitching, manufacturing errors, etc., the number of pixels in the image obtained after stitching is reduced. Up until now, the arrangement of optical devices corresponding to regular tetrahedrons and regular hexahedrons has been proposed, but only spatial arrangements have been proposed, and no specific optical devices themselves or sensor arrangements have been proposed. Moreover, this situation is not limited to omnidirectional cameras, but is similar to that of, for example, optical devices for stereoscopic vision, etc. Therefore, the optical device of the third embodiment is configured as follows.

[0084] <Embodiment 3> The optical device according to the third embodiment is an optical device including a sensor and a lens system, in which a part of the image circle generated by the lens system is outside the sensor. With this configuration, the diameter of the image circle can be made larger than the short side b of the image sensor, so that the number of pixels of the image sensor used for imaging can be increased. Specifically, the equilateral triangular image area K shown in FIG. 17(1) can be configured to be inscribed within the sensor IS as in K' in FIG. 17(2), thereby enabling the number of pixels when capturing images on the sensor to be increased. In addition, the square-shaped imaging area K shown in FIG. 18(1) can be configured to be inscribed in the sensor as in K' in FIG. 18(2), thereby increasing the number of pixels when capturing images on the sensor. Furthermore, the regular pentagonal imaging area K shown in FIG. 19(1) can be configured to be inscribed in the sensor as in K' in FIG. 19(2), thereby increasing the number of pixels when capturing images on the sensor.

[0085] Also, Fig. 16 shows cases where the required image shape within the image circle generated by the lens system is an equilateral triangle, regular tetrahedron, regular pentagon, regular hexagon, regular octagon, and regular decagon, regardless of the shape of the regular polygon corresponding to the regular polyhedron. Normally, the lens system is configured so that these polygons are further inscribed inside the area within the image circle inscribed in the sensor, as shown in the relationship diagram between the image circle and the sensor on the left side of Fig. 16. In this embodiment 3, by configuring a portion of the image circle generated by the lens system to be outside the sensor, as shown in the relationship diagram between the image circle and the sensor on the right side of Figure 16, it is possible to configure these polygons to be inscribed in the sensor, making it possible to expand the imaging area of ​​the image sensor and increase the number of pixels when capturing an image.

[0086] The optical device according to the third embodiment satisfies the following conditional expression, where the area of ​​the image circle is S2 and the area of ​​the image circle inscribed in the sensor is S1. S2 / S1 > 1.10 (9)

[0087] Condition (9) defines an appropriate area ratio (S2 / S1) between the area of ​​the image circle inscribed in the sensor and the area of ​​the image circle generated by the lens system. With this configuration, the area of ​​the image circle generated by the lens system can be made larger than the area of ​​the image circle inscribed in the sensor, and the number of pixels can be increased accordingly. As shown in FIG. 16, the area ratios are 1.78, 2.00, 1.22, 1.33, 1.17, and 1.11, respectively, when the required image shape in the image circle generated by the lens system is, for example, an equilateral triangle, a regular tetrahedron, a regular pentagon, a regular hexagon, a regular octagon, or a regular decagon. That is, the image formation area required by a plurality of lens systems used in, for example, a spherical camera is often polygonal, and the number of pixels of these polygons can be increased by expanding the image formation area in the sensor according to the ratio of the area ratio. Therefore, within the range of this conditional formula (9), the number of sensor pixels required for all the polygons shown above can be increased. If the lower limit of condition (9) is exceeded, the sensor pixels cannot be used effectively. In order to ensure the effect of condition (9), it is preferable to set the lower limit of condition (9) to 1.15, and it is even more preferable to set it to 1.20, 1.25, or 1.30.

[0088] In the optical device according to the third embodiment, the center position of the sensor and the center position of the image circle are different. With this configuration, the diameter of the image circle can be made larger than the short side of the image sensor, allowing the number of pixels to be increased accordingly. This is specifically shown in Figures 17 and 19. Figure 17 is an explanatory diagram for the case where the required image shape corresponding to the equilateral triangles constituting the faces of a regular tetrahedron, regular octahedron, and regular dodecahedron is an equilateral triangle, and Figure 19 is an explanatory diagram for the case where the required image shape corresponding to the regular pentagon constituting the face of a regular dodecahedron is a regular pentagon. Typically, as shown in FIG. 17(1) or FIG. 19(1), an equilateral triangle or a regular pentagon is inscribed inside the area of ​​an image circle inscribed in the sensor. In this embodiment 3, as shown in Figure 17 (2) or Figure 19 (2), by configuring the center position P of the sensor and the center position O' of the image circle generated by the lens system to be different, it is possible to configure the sensor so that an equilateral triangle or a regular pentagon is inscribed in the sensor, which makes it possible to expand the imaging area of ​​the image sensor and increase the number of pixels when capturing an image.

[0089] It is desirable for the optical device according to the third embodiment to satisfy the following conditional expression. 0.00 ≦ d / b ≦ 0.17 (10) however, d: The distance between the center of the sensor and the center of the image circle in the short side direction of the sensor, b: The length of the short side of the sensor.

[0090] Conditional formula (10) specifies the appropriate distance in the short side direction of the sensor between the center of the sensor and the center of the image circle generated by the lens system. This distance d is the difference between the center P of the sensor and the center O' of the image circle generated by the lens system, as shown in Figures 17(2) and 19(2). If the condition (10) is within the range, it is possible to increase the number of sensor pixels required for the polygons that make up a polyhedron, particularly in the case of an equilateral triangle or a regular pentagon. If the upper limit of condition (10) is exceeded, the polygon will not fit on the sensor and part of the image will be lost.

[0091] The omnidirectional camera according to the third embodiment includes the optical device and desirably has at least four lens systems. With this configuration, it is possible to obtain high-quality images using the four lens systems while still achieving compactness.

[0092] In the omnidirectional camera according to the third embodiment, it is desirable that all of the lens systems are the same lens system. This configuration allows the same materials and processing mechanisms to be used for all lens systems, making assembly and adjustment work simple and efficient production. In addition, because the lens system specifications and aberrations are all the same, control and stitching become easier, and processing speed improves. Furthermore, the simple configuration contributes to compact size and high image quality.

[0093] It is desirable for the omnidirectional camera according to the third embodiment to satisfy the following conditional expression. 0.10 ≦ d / b ≦ 0.17 (10-1)

[0094] Conditional formula (10-1) further prescribes an appropriate distance between the center position of the sensor and the center position of the image circle in the short side direction of the sensor by considering the shape of a polyhedron corresponding to the omnidirectional camera in relation to conditional formula (10). This distance d is, for example, the difference between the distance between the center position P of the sensor and the center position O' of the image circle as shown in FIG. 17(2). If the conditional formula (10-1) is satisfied, for example, in a celestial sphere camera in which the shape of a required image is an equilateral triangle, that is, a regular tetrahedron, a regular octahedron, or a regular icosahedron, the pixel area of ​​the sensor can be widely used and an image with a large number of pixels and high resolution can be acquired (see FIG. 17(2)). If the upper limit of conditional expression (10-1) is exceeded, the polygon will not fit on the sensor, resulting in missing images or making it impossible to stitch properly. In order to ensure the effect of condition (10-1), it is preferable for the upper limit value of condition (10-1) to be set to 0.16, and it is even more preferable for it to be set to 0.15, 0.14, or even more preferably 0.13. Furthermore, if the lower limit of conditional formula (10-1) is exceeded, the sensor pixels cannot be used effectively. In order to ensure the effect of condition (10-1), it is preferable for the lower limit value of condition (10-1) to be 0.09, and it is even more preferable for it to be 0.08, 0.07, or even more preferably 0.06.

[0095] It is desirable that the omnidirectional camera according to the third embodiment has at least seven lens systems and satisfies the following conditional expression: 0.01 ≦ d / b ≦ 0.06 (10-2)

[0096] Like conditional formula (10-1), conditional formula (10-2) further prescribes an appropriate distance between the center position of the sensor and the center position of the image circle in the sensor short side direction by considering the shape of a polyhedron corresponding to the omnidirectional camera for conditional formula (10). This distance d is, for example, the difference between the distance between the center position P of the sensor and the center position O' of the image circle as shown in FIG. 19(2). If the conditional formula (10-2) is satisfied, the pixel area of ​​the sensor can be widely used in a spherical camera in which the shape of a required image is, for example, a regular pentagon, i.e., a regular dodecahedron, and an image with a large number of pixels and high resolution can be acquired (see FIG. 19(2)). If the upper limit of conditional expression (10-2) is exceeded, the polygon will not fit on the sensor, resulting in missing images or making it impossible to stitch properly. In order to ensure the effect of condition (10-2), it is preferable to set the upper limit of condition (10-2) to 0.05, and more preferably to 0.04, and even more preferably to 0.03. Furthermore, if the lower limit of conditional formula (10-2) is exceeded, the sensor pixels cannot be used effectively. In order to ensure the effect of conditional formula (10-2), it is preferable for the lower limit value of conditional formula (10-2) to be set to 0.015, and more preferably to 0.02, and even more preferably to 0.025.

[0097] It is desirable for the omnidirectional camera according to the third embodiment to include four of the lens systems having a maximum angle of view of 140 degrees or more, or six of the lens systems having a maximum angle of view of 109 degrees or more, or eight of the lens systems having a maximum angle of view of 109 degrees or more, or twelve of the lens systems having a maximum angle of view of 74 degrees or more, or twenty of the lens systems having a maximum angle of view of 74 degrees or more.

[0098] With this configuration, it is possible to realize a celestial sphere camera having an appropriate lens system corresponding to each of a regular tetrahedron, a regular hexahedron, a regular octahedron, a regular dodecahedron, and a regular icosahedron. Hereinafter, a specific description will be given of a regular tetrahedron, a regular hexahedron, a regular octahedron, a regular dodecahedron, and a regular icosahedron.

[0099] (regular tetrahedron) In the case of a regular tetrahedron, it is desirable to have four of the above lens systems, each with a maximum angle of view of 140 degrees or more. With this configuration, it is possible to obtain high-quality images using an appropriate lens system that corresponds to the regular tetrahedron, and also to reduce the size of the entire omnidirectional camera. If the maximum angle of view is less than 140 degrees, it will not be possible to capture an image with a field of view necessary to compose an appropriate image as a spherical camera. A maximum angle of view of 150 degrees or more is preferable since it has a favorable effect on parallax and manufacturing errors. If the maximum angle of view is 160 degrees or more, the stitching effect can be further improved, which is preferable.

[0100] (Six sides) In the case of a regular hexahedron, it is desirable to have six of the above lens systems, each with a maximum angle of view of 109 degrees or more. With this configuration, a high-quality image can be obtained using an appropriate lens system that corresponds to a regular hexahedron, and the entire omnidirectional camera can be made compact. If the maximum angle of view is less than 109 degrees, it will not be possible to capture the field of view image required to compose an appropriate image as an omnidirectional camera. A maximum angle of view of 120 degrees or more is preferable since it has a favorable effect on parallax and manufacturing errors. If the maximum angle of view is 140 degrees or more, the stitching effect can be further improved, which is preferable.

[0101] (Eight sides) In the case of a regular octahedron, it is desirable to have eight of the above lens systems, each having a maximum angle of view of 109 degrees or more. With this configuration, it is possible to obtain high-quality images using an appropriate lens system that corresponds to the regular octahedron, and also to reduce the size of the entire omnidirectional camera. If the maximum angle of view is less than 109 degrees, it will not be possible to capture the field of view image required to compose an appropriate image as an omnidirectional camera. A maximum angle of view of 120 degrees or more is preferable since it has a favorable effect on parallax and manufacturing errors. If the maximum angle of view is 140 degrees or more, the stitching effect can be further improved, which is preferable.

[0102] (Twelve faces) In the case of a regular dodecahedron, it is desirable to have twelve of the above lens systems, each with a maximum angle of view of 109 degrees or more. With this configuration, a high-quality image can be obtained using an appropriate lens system that corresponds to a regular dodecahedron, and the entire omnidirectional camera can be made compact. If the maximum angle of view is less than 109 degrees, it will not be possible to capture the field of view image required to compose an appropriate image as an omnidirectional camera. A maximum angle of view of 120 degrees or more is preferable since it has a favorable effect on parallax and manufacturing errors. If the maximum angle of view is 140 degrees or more, the stitching effect can be further improved, which is preferable.

[0103] (20 faces) In the case of a regular icosahedron, it is desirable to have 20 of the above lens systems, each with a maximum angle of view of 74 degrees or more. With this configuration, a high-quality image can be obtained using an appropriate lens system that corresponds to the regular icosahedron, and the entire omnidirectional camera can be made compact. If the maximum angle of view is less than 74 degrees, it will not be possible to capture the field of view image required to compose an appropriate image as an omnidirectional camera. A maximum angle of view of 90 degrees or more is preferable since it has a favorable effect on parallax and manufacturing errors. If the maximum angle of view is 100 degrees or more, the stitching effect can be further improved, which is preferable.

[0104] The omnidirectional camera according to the third embodiment satisfies the following conditional expression, where fa is the focal length from the surface nearest to the object of the lens system to the aperture, and fb is the focal length from the aperture to the surface nearest to the image. -20.0 < fa / fb < 20.0 (11)

[0105] Conditional expression (11) specifies the appropriate power balance between the focal length from the lens system's most object-side surface to the aperture (hereinafter referred to as the "front group") and the focal length from the aperture to the most image-side surface (hereinafter referred to as the "rear group"). If the condition is within the range of conditional expression (11), the lens system will be of an appropriate size suitable for a spherical camera with little curvature of field and little distortion, which is preferable. If the upper limit of conditional expression (11) is exceeded, the refractive power of the rear group will be large relative to the refractive power of the front group, and the lens system will become longer in the optical axis direction, making the entire spherical camera larger.

[0106] In order to ensure the effect of condition (11), it is preferable to set the upper limit of condition (11) to 15.0, and more preferably to 10.0, 7.0, or even more preferably to 5.0. If the lower limit of condition (11) is exceeded, the refractive power of the rear group becomes small relative to the refractive power of the front group, and as a result, the relative power of the front group becomes too strong, making it difficult to correct aberrations. In particular, the effect on the curvature of field becomes significant. In order to ensure the effect of condition (11), it is preferable to set the lower limit of condition (11) to -15.0, and more preferably to -10.0, -7.0, or even -5.0.

[0107] The omnidirectional camera according to the third embodiment satisfies the following conditional expression, where TL is the distance on the optical axis from the surface closest to the object in the lens system to the image plane, and S is the distance on the optical axis from the aperture to the image plane. 0.20 < S / TL < 0.80 (12)

[0108] Conditional expression (12) specifies the position of the aperture in the lens system. If conditional expression (12) is satisfied, it is possible to achieve a lens system in which astigmatism and coma aberration suitable for a spherical camera are well corrected (suppressed). If the lower limit of this condition is not met, coma and astigmatism will increase, which is not preferable. In order to ensure the effect of condition (12), it is preferable to set the lower limit of condition (12) to 0.25, and more preferably to 0.30, 0.35, or even 0.40. If the upper limit of condition (12) is exceeded, coma and astigmatism will also worsen, which is undesirable. In order to ensure the effect of condition (12), it is preferable to set the upper limit of condition (12) to 0.75, and more preferably to 0.70, 0.65, or even more preferably to 0.60.

[0109] (Fourth Form) In normal photography, one image is received by one sensor, as shown in Figure 65(1), so for two images, two images are received by two sensors, as in, for example, JP 2013-45089 A (see Figures 65(2) and (3)). As shown in Figures 65(1), (2), and (3), sensors are generally square and the image is circular, so only a portion of the sensor area overlaps with the image circle, resulting in fewer sensor pixels contributing to imaging. This is particularly noticeable in the case of a spherical camera that uses multiple lens systems, and the same situation exists in optical devices for stereoscopic vision. Therefore, the optical device of the fourth embodiment is configured as follows.

[0110] <Embodiment 4> The optical device according to the fourth embodiment receives images formed by a plurality of lens systems with sensors arranged on the same plane.

[0111] This configuration allows more pixels in the sensor to contribute to imaging. It also simplifies the sensor placement and adjustment work, and reduces costs with a simple configuration. It also contributes to the miniaturization of the sensor area. Specifically, for example, as shown in Figures 20(1), (2), and (3), two images are received by an imaging sensor arranged on the same plane. In this way, even if the diameter of the image circle is the same as or smaller than the short side of the image sensor, the work required for sensor arrangement can be simplified by receiving multiple images with the image sensor arranged on the same plane, and the adjustment work can be performed efficiently by performing the same adjustment on two images formed on the same plane. Also, the area occupied by the sensor can be reduced from the entire optical device. In the fourth embodiment, the sensors arranged on the same plane include a plurality of sensors arranged on the same plane. In the fourth embodiment, the "lens system" may not include optical elements (including optical fibers) or sensors.

[0112] In the optical device according to the fourth embodiment, the sensor arranged on the same plane is one sensor.

[0113] This configuration makes it possible to reduce the number of sensors used and the number of unused pixels, and also enables similar image processing to be performed on multiple lens systems. Specifically, for example, two images are received by one imaging sensor as shown in FIGS. 20(2) and 20(3). In this way, even if the diameter of the image circle is the same as or smaller than the short side of the image sensor, by receiving multiple images with one sensor, it is possible to increase the number of sensor pixels that contribute to image capture. In addition, since there is only one sensor corresponding to multiple lens systems, it is necessary to control only that one sensor, which simplifies adjustment work and configuration, and there is no individual difference, making it easy to take measures against noise, brightness, etc. In addition, by using multiple lens systems corresponding to one sensor, the number of pixels that contribute to imaging increases, resulting in higher optical performance.

[0114] In the fourth embodiment, one sensor refers to a sensor that shares a common control circuit provided inside the sensor, or a sensor whose imaging surface is integrally configured.

[0115] The optical device according to the fourth embodiment includes an optical element that bends the optical path. This configuration increases the degree of freedom in arranging the lens system, making it easier to reduce the size of the entire optical device. Specifically, for example, in Figure 20(2), lens systems are placed on the left and right sides of the paper relative to a prism (an optical element that bends the optical path), and the light rays entering the prism from both lens systems are reflected (bent) downward by the prism and can be received by a sensor placed on the same plane. Without such an optical element that bends the optical path, it is difficult to receive light on a sensor arranged on the same plane, and it is difficult to reduce the area occupied by the sensor from the entire optical device. In the fourth embodiment, the optical element that bends the optical path refers to a prism, a reflecting mirror, an optical fiber, or the like.

[0116] The optical device according to the fourth embodiment has a plurality of lens systems and a plurality of formed images. This configuration allows images formed by multiple lens systems to be received by a single sensor, making effective use of the sensor's pixels and enabling the acquisition of high-quality images. It also allows the number of sensors to be reduced, contributing to miniaturization.

[0117] The optical device according to the fourth embodiment satisfies the following conditional expression, where P is the aspect ratio of the sensor. 1.0 ≦ P < 3.0 (13)

[0118] According to conditional formula (13), which specifies the optimal aspect ratio (width / height) of the sensor, the image formed by the two lens systems can be properly received and a high-quality image can be obtained and processed. If the upper limit of conditional formula (13) is exceeded, the image formed in the height direction of the sensor cannot be accommodated on the sensor, resulting in partial loss of the image. If the lower limit of conditional formula (13) is exceeded, the image formed in the width direction of the sensor cannot be accommodated on the sensor, resulting in partial loss of the image. In order to ensure the effect of condition (13), it is preferable that the upper limit value of condition (13) be 2.9, and more preferably 2.8, 2.7, 2.6, 2.5, 2.4, 2.3, 2.2, 2.1, 2.0, 1.9, 1.8, 1.7, and further preferably 1.6. In order to ensure the effect of condition (13), it is preferable to set the lower limit of condition (13) to 1.1, and more preferably 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, or 1.9.

[0119] The omnidirectional camera according to the fourth embodiment includes the optical device and has at least four lens systems. With this configuration, in a spherical camera represented by a polyhedron with tetrahedral or more faces, it is possible to obtain high-quality images using at least four lenses, while reducing the number of sensors and making the camera more compact.

[0120] The omnidirectional camera according to the fourth embodiment has a virtual polyhedron inside an imaginary sphere, and one lens system is assigned to one surface of the polyhedron. With this configuration, it is possible to receive the light beam incident from all the faces of the polyhedron without any waste, and to obtain a high quality image.

[0121] The omnidirectional camera according to the fourth embodiment receives, with the one sensor, an image formed by light incident on two adjacent faces of the polyhedron. With this configuration, the optical path of each light beam entering from two adjacent faces of the polyhedron can be bent using a single optical element, reducing the number of optical elements. In addition, two lens systems that form an image on a single sensor can be positioned closely together, making it possible to further miniaturize the omnidirectional camera. Specifically, in Figure 21(1), consider a triangle PYQ formed by connecting vertices P and Q of a regular tetrahedron PQRS with the midpoint Y of the side RS of the regular tetrahedron. Then, let the side incident from face PRS of the regular tetrahedron be side A, and the side incident from face QSR be side B, and let the angle PYQ be θ, and the length of one side of a regular hexahedron inscribed in the regular tetrahedron be 1, then the above triangle will have the values ​​shown in Figure 21(2). Now consider a ray of light D incident from side A of the above triangle as shown in FIG. 21(3). For example, as shown in Figure 20(2), the light path of light ray D is bent by optical element C (C is an optical element that bends the light path, such as a reflecting mirror) so that it is incident on a sensor directly below, and the reflected light ray is called light ray E. Furthermore, if the angle of incidence of light ray D entering the above triangle is α, and if the optical element that bends the optical path is a reflecting mirror, the angle of the reflecting mirror with respect to a line perpendicular to the sensor placed directly below is β, and the angle between the reflective surface of the reflecting mirror and side YP of the above triangle on the RSP surface of the regular tetrahedron is γ, then α, β, and γ will have the values ​​shown in Figure 21(4). With this configuration, it is possible to bend the optical path of the light incident from side A and guide it appropriately to the sensor. Note that the same configuration is used for side B, so a description thereof will be omitted. In addition, by bending the optical paths of sides A and B with a single optical element (e.g., a prism), the omnidirectional camera can be further miniaturized.

[0122] By configuring the optical element that bends the light path in this way, the image formed by the light incident on two adjacent faces of the regular tetrahedron can be properly received by a single sensor, making it possible to miniaturize the omnidirectional camera. This is the case for a regular tetrahedron, but the same can be said for polyhedra. In addition, taking into account design errors, stitching, etc., it is sufficient that these values ​​are met within a range of plus or minus 5% from the indicated values. By using such a bending angle, it is possible to bend the optical path of each of the light rays incident on two adjacent faces of the polyhedron using a single optical element, which allows for fewer optical elements and makes the entire omnidirectional camera more compact.

[0123] The omnidirectional camera according to the fourth embodiment includes at least two of the above sensors. With this configuration, for example, in a spherical camera corresponding to a regular tetrahedron, images formed by four lens systems can be received by two sensors. For example, in FIG. 22 showing this, a light ray a2 incident from surface ABC and a light ray a1 incident from surface DCB are received by one image sensor IS1, and a light ray b1 incident from surface ADC and a light ray b2 incident from surface ADB are received by another image sensor IS2. In this way, by providing two sensors corresponding to two lens systems, it is possible to reduce the number of sensors by two compared to the normal case, and the spherical camera can be made more compact. The same is true for spherical cameras that are compatible with other polyhedrons.

[0124] In the omnidirectional camera according to the fourth embodiment, it is desirable that all of the lens systems are the same. This configuration allows the same materials and processing mechanisms to be used for all lens systems, making assembly and adjustment work simple and efficient, and also facilitating efficient production. In addition, because the lens system specifications and aberrations are all the same, control and stitching become easier, improving processing speed. Furthermore, the simple configuration also contributes to compact size and high image quality.

[0125] With this configuration, it is possible to realize an omnidirectional camera having an appropriate lens system. The regular tetrahedron will be specifically described below.

[0126] In the case of a regular tetrahedron, it is desirable to have four of the above lens systems, each with a maximum angle of view of 140 degrees or more. With this configuration, it is possible to obtain high-quality images using an appropriate lens system that corresponds to the regular tetrahedron, and also to reduce the size of the entire omnidirectional camera. If the maximum angle of view is less than 140 degrees, it will not be possible to capture an image with a field of view necessary to compose an appropriate image as a spherical camera. A maximum angle of view of 150 degrees or more is preferable since it has a favorable effect on parallax and manufacturing errors. If the maximum angle of view is 160 degrees or more, the stitching effect can be further improved, which is preferable.

[0127] The omnidirectional camera according to the fourth embodiment satisfies the following conditional expression, where fa is the focal length from the surface nearest to the object side of the lens system to the aperture, and fb is the focal length from the aperture to the surface nearest to the image side. -20.0 < fa / fb < 20.0 (14)

[0128] Conditional expression (14) specifies the appropriate power balance between the focal length from the lens system's most object-side surface to the aperture (hereinafter referred to as the "front group") and the focal length from the aperture to the most image-side surface (hereinafter referred to as the "rear group"). If the conditional expression (14) is satisfied, the lens system will be of an appropriate size suitable for an omnidirectional camera with little curvature of field and little distortion, and the entire omnidirectional camera can be made compact by combining this lens system. If the upper limit of conditional expression (14) is exceeded, the refractive power of the rear group will be large relative to the refractive power of the front group, and the lens system will become longer in the optical axis direction, making the entire omnidirectional camera larger. In order to ensure the effect of condition (14), it is preferable to set the upper limit of condition (14) to 15.0, and more preferably to 10.0, 7.0, or even more preferably to 5.0. If the lower limit of condition (14) is exceeded, the refractive power of the rear group becomes small relative to the refractive power of the front group, and as a result, the relative power of the front group becomes too strong, making it difficult to correct aberrations. In particular, the effect on the curvature of field becomes significant. In order to ensure the effect of condition (14), it is preferable to set the lower limit of condition (14) to -15.0, and more preferably to -10.0, -7.0, or even -5.0.

[0129] The omnidirectional camera according to the fourth embodiment satisfies the following conditional expression, where TL is the distance on the optical axis from the surface closest to the object in the lens system to the image plane, and S is the distance on the optical axis from the aperture to the image plane. 0.20 < S / TL < 0.80 (15)

[0130] Condition (15) specifies the position of the aperture in the lens system. If condition (15) is satisfied, it is possible to achieve a lens system in which astigmatism and coma are well corrected (suppressed) and suitable for a spherical camera. If the lower limit of this condition is not met, coma and astigmatism will increase, which is not preferable. In order to ensure the effect of condition (15), it is preferable to set the lower limit of condition (15) to 0.25, and more preferably to 0.30, 0.35, or even 0.40. If the upper limit of condition (15) is exceeded, coma and astigmatism will also worsen, which is undesirable. In order to ensure the effect of condition (15), it is preferable to set the upper limit of condition (15) to 0.75, and more preferably to 0.70, 0.65, or even more preferably to 0.60.

[0131] (Fifth Form) <Embodiment 5> Hereinafter, the manufacturing method of the omnidirectional camera according to the fifth embodiment will be explained by dividing it into manufacturing method 1, manufacturing method 2, and manufacturing method 3.

[0132] First, in the manufacturing method 1 for an omnidirectional camera according to the fifth embodiment, a plurality of lens systems are provided and arranged so that the optical axes of the respective lens systems and the straight lines extending from the optical axes do not intersect with each other. Hereinafter, an outline of a manufacturing method 1 for the omnidirectional camera OL according to the fifth embodiment will be described with reference to Fig. 23. First, a plurality of lens systems are arranged (S1). Next, the lens systems are arranged such that their optical axes and lines extending from the optical axes do not intersect (S2). According to the above-mentioned manufacturing method 1 of the omnidirectional camera, a compact omnidirectional camera can be manufactured.

[0133] Next, a manufacturing method 2 for an omnidirectional camera according to the fifth embodiment has four or more lens systems and is arranged so that the optical paths intersect. Hereinafter, an outline of a manufacturing method 2 for the omnidirectional camera OL according to the fifth embodiment will be described with reference to Fig. 24. First, four or more lens systems are arranged (S1). Next, these are arranged so that their optical paths intersect (S2). According to the above-mentioned manufacturing method 2 of the omnidirectional camera, a compact omnidirectional camera can be manufactured.

[0134] Furthermore, in the manufacturing method 3 of the omnidirectional camera according to the fifth embodiment, at least four optical devices each having a sensor and a lens system are arranged, in which a part of the image circle generated by the lens system is outside the sensor. Hereinafter, an outline of manufacturing method 3 of the omnidirectional camera OL according to the fifth embodiment will be described with reference to Fig. 25. First, an optical device including a sensor and a lens system is arranged (S1). Next, the lens system is arranged so that a part of the image circle generated by the lens system is outside the sensor (S2). Then, at least four of the optical devices are arranged (S3). According to the above-mentioned manufacturing method 3 of the omnidirectional camera, it is possible to manufacture an omnidirectional camera with a large number of pixels.

[0135] It should be noted that the conditions and configurations described above each provide the effects described above, and are not limited to those that satisfy all of the conditions and configurations. The effects described above can be obtained by satisfying any one of the conditions or configurations, or any combination of the conditions or configurations.

[0136] Moreover, the contents described below can be appropriately adopted within the scope that does not impair the optical performance.

[0137] The lens can also be used for autofocusing, and is suitable for driving a motor (such as an ultrasonic motor) for autofocusing. In addition, the lens can be configured even more simply for pan-focusing.

[0138] In addition, a lens, lens group, or partial lens group may be moved so as to have a displacement component perpendicular to the optical axis, or rotated (rocked) in a plane including the optical axis to serve as an anti-vibration lens group that corrects image blur caused by camera shake.

[0139] The lens surface may be spherical or flat, or aspheric. A spherical or flat lens surface is preferable because it facilitates lens processing and assembly adjustment, and prevents deterioration of optical performance due to processing and assembly adjustment errors. It is also preferable because there is little deterioration in depiction performance even if the image plane is shifted. When the lens surface is aspheric, the aspheric surface may be any of aspheric surfaces such as an aspheric surface formed by grinding, a glass molded aspheric surface formed by molding glass into an aspheric shape, and a composite aspheric surface formed by forming a resin into an aspheric shape on the surface of glass. The lens surface may be a diffractive surface, and the lens may be a gradient index lens (GRIN lens) or a plastic lens.

[0140] It is preferable that the aperture stop S is disposed inside or outside the lens group, but it is also possible to use the frame of the lens instead of providing a member serving as the aperture stop.

[0141] Furthermore, each lens surface may be coated with an anti-reflection coating having high transmittance over a wide wavelength range in order to reduce flare and ghosting and achieve high contrast and high optical performance.

[0142] With the above-described configuration, it is possible to provide a bright lens system having good optical performance, an optical device OL, and an omnidirectional camera having this optical device OL.

[0143] Each example according to each embodiment will be described below with reference to the drawings. Tables 1 to 16 are tables showing the specifications of each lens system in Examples 1 to 16.

[0144] The optical system cross-sectional view shown in FIG. 26 is a cross-sectional view of the optical system of the first embodiment. The lenses in FIG. 26 are designated L11, L12, L13, . . . from the object side (the left side of the page). 27 is an aberration diagram of Example 1. Here, FNO is the F-number, Y is the image height, and d, g, C, and F indicate the aberration curves for the d-line, g-line, C-line, and F-line, respectively. In the astigmatism, the solid line indicates the sagittal image surface, and the dotted line indicates the meridional image surface. The above points regarding the optical system cross-sectional views and aberration diagrams are also applicable to the drawings according to other embodiments.

[0145] In addition, the reference numerals for the drawings of each embodiment are used independently for each embodiment in order to avoid complication of explanation due to an increase in the number of digits of the reference numerals. Therefore, even if the reference numerals are used in common with drawings of other embodiments, they do not necessarily have the same configuration as the other embodiments.

[0146] In each embodiment, the C-line (wavelength 656.3 nm), d-line (wavelength 587.6 nm), F-line (wavelength 486.1 nm), and g-line (wavelength 435.8 nm) are selected as the targets for calculating the aberration characteristics.

[0147] In the table (basic specifications), f is the focal length of the lens system, FNO is the F-number, Y is the image height, TL is the total lens length (the distance from the frontmost lens surface to the final lens surface on the optical axis), and BF is the back focus (the distance from the final lens surface to the paraxial image plane on the optical axis).

[0148] In the (surface data) in the table, the surface number indicates the order of the optical surface from the object side along the traveling direction of the light ray, r indicates the radius of curvature of each optical surface, d indicates the surface spacing which is the distance on the optical axis from each optical surface to the next optical surface (or image surface), nd indicates the refractive index for the d-line of the material of the optical component, and νd indicates the Abbe number based on the d-line of the material of the optical component. In addition, (object surface) indicates the object surface, the "∞" in the radius of curvature indicates a plane or an aperture, (aperture) indicates the aperture stop S, the image surface indicates the image surface I, and BF indicates the back focus (the distance from the final lens surface on the optical axis to the paraxial image surface). Even if BF is not indicated as (variable), it may be variable. The refractive index of air "1.000000" is omitted.

[0149] In the table (Appropriate aspect of omnidirectional camera), the polyhedron indicates an appropriate polyhedron corresponding to the optical device OL composed of a lens system and a sensor. The surface shape indicates the shape of the surfaces that constitute the polyhedron. The angle of view 2ωA indicates the minimum angle of view that the omnidirectional camera can achieve with the optical device OL, and the angle of view 2ωB indicates the maximum angle of view that the optical device OL can apply. It should be noted that the lens systems of the embodiments are often applicable to other polyhedrons having a greater number of surfaces than the polyhedrons shown here.

[0150] In the table (for the appropriate sensor configuration), b is the length of the short side of the sensor, a is the length of the long side of the sensor, and 2Y-b is twice the image height minus the length of the short side of the sensor. If this value is positive, it means that part of the image circle generated by the lens system is outside the sensor.

[0151] In the table, (Suitable embodiment) shows an embodiment suitable for application of the lens system of each example among the above-mentioned embodiments. However, embodiments other than the embodiments shown here may also be applicable.

[0152] In the following, for all specifications, the focal length f, radius of curvature r, surface spacing d, and other lengths are generally in "mm" unless otherwise specified, but this is not limited to this because the optical device can obtain the same optical performance even if it is proportionally enlarged or reduced. Also, the unit is not limited to "mm" and other appropriate units can be used.

[0153] The above explanation of the tables is common to all the embodiments, and will not be repeated below.

[0154] (First Example) The first example will be described with reference to Fig. 26, Fig. 27 and Table 1. The lens system according to the first example is composed of, arranged in order from the object side along the optical axis, a front group GF having negative refractive power, an aperture stop S, and a rear group GR having positive refractive power, as shown in Fig. 26.

[0155] The front group GF consists of, arranged in order from the object side along the optical axis, a negative meniscus lens L11 with its convex surface facing the object side, a negative meniscus lens L12 with its convex surface facing the object side, a negative biconcave lens L13, and a positive biconvex lens L14.

[0156] The rear group GR is composed of, arranged in order from the object side along the optical axis, a cemented lens composed of a negative meniscus lens L21 with its convex surface facing the object side and a positive biconvex lens L22, and a positive biconvex lens L23.

[0157] An image is formed on the sensor by this lens system and photographed. Figure 26 shows the image plane I of this lens system. Table 1 below shows the values ​​of each parameter in the first embodiment.

[0158] (Table 1) First Example (Basic specifications) f 1.2 FNO 2.4 Y 1.9 TL 25.3 BF 4.2 (surface data) Surface number rd nd νd 0 (physical surface) ∞ (variable) 1 11.6728 1.0000 1.816000 46.59 2 4.2875 2.8000 3 392.8840 1.0000 1.651600 58.57 4 2.7357 2.2000 5 -48.1033 1.0000 1.618000 63.34 6 5.7672 1.0000 7 11.4369 2.3000 1.784700 26.27 8 -6.3985 1.7000 9(Aperture)∞ 1.5000 10 15.8418 1.0000 1.846660 23.80 11 2.7021 3.4000 1.640000 60.20 12 -6.7021 0.2000 13 6.8935 2.0000 1.487490 70.31 14 -7.3412 4.1507 Image plane ∞ (Appropriate aspects of the spherical camera) Polyhedron: Tetrahedron Surface shape: equilateral triangle Angle of view 2ωA=141.06° Angle of view 2ωB=189.54° (Suitable Sensor Aspects) b 3.6 a 4.8 2Y-b 0.2 (Suitable embodiment) Embodiments 1, 3, 4, 5

[0159] FIG. 27 is a diagram showing various aberrations of the optical system according to the first example of the present application. It can be seen from FIG. 27 that the optical system according to this embodiment has excellent imaging performance with various aberrations being well corrected. It can also be seen that chromatic aberration is well corrected.

[0160] (Second Example) The second embodiment will be described with reference to Fig. 28, Fig. 29 and Table 2. As shown in Fig. 28, the lens system according to the second embodiment is composed of, arranged in order from the object side along the optical axis, a front group GF having negative refractive power, an aperture stop S, and a rear group GR having positive refractive power.

[0161] The front group GF consists of, arranged in order from the object side along the optical axis, a negative meniscus lens L11 with its convex surface facing the object side, a negative meniscus lens L12 with its convex surface facing the object side, a negative meniscus lens L13 with its convex surface facing the object side, and a positive biconvex lens L14.

[0162] The rear group GR is composed of, arranged in order from the object side along the optical axis, a cemented lens composed of a negative meniscus lens L21 with its convex surface facing the object side and a positive biconvex lens L22, and a positive biconvex lens L23.

[0163] An image is formed on the sensor by this lens system and photography is performed. Figure 28 shows the image plane I of this lens system. Table 2 below shows the values ​​of each parameter in the second embodiment.

[0164] (Table 2) Second Example (Basic specifications) f 5.0 FNO 2.4 Y 6.3 TL 101.1 BF 16.7 (surface data) Surface number rd nd νd 0 (physical surface) ∞ (variable) 1 74.2196 4.0000 1.816000 46.59 2 17.9744 11.2000 3 71.2348 4.0000 1.651600 58.57 4 12.7880 8.8000 5 224.3105 4.0000 1.618000 63.34 6 15.9543 4.0000 7 57.4800 9.2000 1.784700 26.27 8 -21.2053 6.8000 9(Aperture)∞ 6.0000 10 1614.8232 4.0000 1.846660 23.80 11 11.6377 13.6000 1.640000 60.20 12 -19.7584 0.8000 13 24.6901 8.0000 1.487490 70.31 14 -42.0412 16.6522 Image plane ∞ (Appropriate aspects of the spherical camera) Polyhedron: regular hexahedron Surface shape: square Angle of view 2ωA=109.47° Angle of view 2ωB=150.50° (Suitable Sensor Aspects) b 8.8 a 13.2 2Y-b 3.8 (Suitable embodiment) Embodiments 1, 3, 4, 5

[0165] FIG. 29 is a diagram showing various aberrations of the optical system according to the second embodiment of the present application. It can be seen from FIG. 29 that the optical system according to this embodiment has excellent imaging performance with various aberrations being well corrected. It can also be seen that chromatic aberration is well corrected.

[0166] (Third Example) The third embodiment will be described with reference to Fig. 30, Fig. 31 and Table 3. As shown in Fig. 30, the lens system according to the third embodiment is composed of, arranged in order from the object side along the optical axis, a front group GF having negative refractive power, an aperture stop S, and a rear group GR having positive refractive power.

[0167] The front group GF consists of, arranged in order from the object side along the optical axis, a meniscus negative lens L11 with its convex surface facing the object side, a meniscus negative lens L12 with its convex surface facing the object side, a biconvex positive lens L13, a cemented lens consisting of a biconcave negative lens L14 and a biconvex positive lens L15, and a cemented lens consisting of a meniscus positive lens L16 with its concave surface facing the object side and a meniscus negative lens L17 with its concave surface facing the object side.

[0168] The rear group GR is made up of, in order from the object side along the optical axis, a cemented lens made up of a biconcave negative lens L21 and a biconvex positive lens L22, and a biconvex positive lens L23.

[0169] An image is formed on the sensor by this lens system and photographed. Figure 30 shows the image plane I of this lens system. Table 3 below shows the values ​​of each parameter in the third embodiment.

[0170] (Table 3) Third Example (Basic specifications) f 10.6 FNO 2.9 Y 10.1 TL 105.0 BF 41.2 (surface data) Surface number rd nd νd 0 (physical surface) ∞ (variable) 1 59.1940 2.1000 1.772500 49.62 2 15.2430 9.7000 3 78.1034 1.7000 1.834810 42.73 4 20.9438 5.7000 5 56.8025 4.0000 1.581440 40.98 6 -22.4154 0.3000 7 -19.9258 2.8000 1.772500 49.62 8 11.9633 5.0000 1.728250 28.38 9 -62.7285 9.5000 10 -54.3964 2.6000 1.517420 52.20 11 -12.9020 1.4000 1.902650 35.73 12 -20.9423 1.8000 13(Aperture)∞ 8.3000 14 -1129.0079 1.5000 1.846660 23.80 15 33.7105 4.0000 1.497820 82.57 16 -27.3470 0.2000 17 44.4578 3.2000 1.651600 58.57 18 -50.4316 41.2208 Image plane ∞ (Appropriate aspects of the spherical camera) Polyhedron: regular dodecahedron Surface shape: regular pentagon Angle of view 2ωA=74.75° Angle of view 2ωB=115.64° (Suitable Sensor Aspects) b 13.8 a 20.7 2Y-b 6.4 (Suitable embodiment) Embodiments 1, 3, 4, 5

[0171] FIG. 31 is a diagram showing various aberrations of the optical system according to the third example of the present application. It can be seen from FIG. 31 that the optical system according to this embodiment has excellent imaging performance with various aberrations being well corrected. It can also be seen that chromatic aberration is well corrected.

[0172] (Fourth Example) The fourth embodiment will be described with reference to Fig. 32, Fig. 33 and Table 4. As shown in Fig. 32, the lens system according to the fourth embodiment is composed of, arranged in order from the object side along the optical axis, a front group GF having negative refractive power, an aperture stop S, and a rear group GR having positive refractive power.

[0173] The front group GF consists of, arranged in order from the object side along the optical axis, a meniscus negative lens L11 with its convex surface facing the object side, a meniscus negative lens L12 with its convex surface facing the object side, a biconvex positive lens L13, a cemented lens consisting of a biconcave negative lens L14 and a biconvex positive lens L15, and a cemented lens consisting of a meniscus positive lens L16 with its concave surface facing the object side and a meniscus negative lens L17 with its concave surface facing the object side.

[0174] The rear group GR is made up of, in order from the object side along the optical axis, a cemented lens made up of a biconcave negative lens L21 and a biconvex positive lens L22, and a biconvex positive lens L23.

[0175] An image is formed on the sensor by this lens system and photography is performed. Figure 32 shows the image plane I of this lens system. Table 4 below shows the values ​​of each parameter in the fourth embodiment.

[0176] (Table 4) Fourth Example (Basic specifications) f 10.6 FNO 2.9 Y 11.8 TL 105.0 BF 41.2 (surface data) Surface number rd nd νd 1 60.1136 2.1000 1.772500 49.62 2 15.3022 9.7000 3 79.6717 1.7000 1.834810 42.73 4 20.9269 5.7000 5 56.4966 4.0000 1.581440 40.98 6 -22.9875 0.3000 7 -20.3569 2.8000 1.772500 49.62 8 11.9459 5.0000 1.728250 28.38 9 -62.1390 ​​9.5000 10 -55.8816 2.6000 1.517420 52.20 11 -12.9209 1.4000 1.902650 35.73 12 -21.1407 1.8000 13(Aperture)∞ 8.3000 14 -1343.4000 1.5000 1.846660 23.80 15 33.6080 4.0000 1.497820 82.57 16 -27.3417 0.2000 17 45.0478 3.2000 1.651600 58.57 18 -49.8177 41.2223 Image plane ∞ (Appropriate aspects of the spherical camera) Polyhedron: hexagonal prism Surface shape: square, regular hexagon Angle of view 2ωA=98.21° Angle of view 2ωB=139.22° (Suitable Sensor Aspects) b 15.6 a 23.6 2Y-b 8.0 (Suitable embodiment) Embodiments 1, 3, 4, 5

[0177] FIG. 33 is a diagram showing various aberrations of the optical system according to the fourth example of the present application. It can be seen from FIG. 33 that the optical system according to this embodiment has excellent imaging performance with various aberrations being well corrected. It can also be seen that chromatic aberration is well corrected.

[0178] (Fifth Example) The fifth embodiment will be described with reference to Fig. 34, Fig. 35 and Table 5. As shown in Fig. 34, the lens system according to the fifth embodiment is composed of, arranged in order from the object side along the optical axis, a front group GF having negative refractive power, an aperture stop S, and a rear group GR having positive refractive power.

[0179] The front group GF consists of, arranged in order from the object side along the optical axis, a meniscus negative lens L11 with its convex surface facing the object side, a meniscus negative lens L12 with its convex surface facing the object side, a biconvex positive lens L13, a cemented lens consisting of a biconcave negative lens L14 and a biconvex positive lens L15, and a cemented lens consisting of a meniscus positive lens L16 with its concave surface facing the object side and a meniscus negative lens L17 with its concave surface facing the object side.

[0180] The rear group GR is made up of, in order from the object side along the optical axis, a cemented lens made up of a biconcave negative lens L21 and a biconvex positive lens L22, and a biconvex positive lens L23.

[0181] The image is formed on the sensor by this lens system and photographed. Figure 34 shows the image plane I of this lens system. Table 5 below shows the values ​​of each parameter in the fifth embodiment.

[0182] (Table 5) Fifth Example (Basic specifications) f 10.6 FNO 2.9 Y 11.5 TL 105.0 BF 41.2 (surface data) Surface number rd nd νd 1 59.5096 2.1000 1.772500 49.62 2 15.2641 9.7000 3 78.3754 1.7000 1.834810 42.73 4 20.9309 5.7000 5 56.7899 4.0000 1.581440 40.98 6 -22.6020 0.3000 7 -20.0667 2.8000 1.772500 49.62 8 11.9574 5.0000 1.728250 28.38 9 -62.4989 9.5000 10 -54.7635 2.6000 1.517420 52.20 11 -12.9062 1.4000 1.902650 35.73 12 -21.0011 1.8000 13(Aperture)∞ 8.3000 14 -1197.8838 1.5000 1.846660 23.80 15 33.6728 4.0000 1.497820 82.57 16 -27.3468 0.2000 17 44.6445 3.2000 1.651600 58.57 18 -50.2228 41.2213 Image plane ∞ (Appropriate aspects of the spherical camera) Polyhedron: truncated hexahedron Surface shape: regular triangle, regular octagon Angle of view 2ωA=94.53° Angle of view 2ωB=134.82° (Suitable Sensor Aspects) b 15.6 a 23.6 2Y-b 7.4 (Suitable embodiment) Embodiments 1, 3, 4, 5

[0183] FIG. 35 is a diagram showing various aberrations of the optical system according to the fifth example of the present application. It can be seen from FIG. 35 that the optical system according to this embodiment has excellent imaging performance with various aberrations being well corrected. It can also be seen that chromatic aberration is well corrected.

[0184] (Sixth Example) The sixth embodiment will be described with reference to Fig. 36, Fig. 37 and Table 6. As shown in Fig. 36, the lens system according to the sixth embodiment is composed of, arranged in order from the object side along the optical axis, a front group GF having negative refractive power, an aperture stop S, and a rear group GR having positive refractive power.

[0185] The front group GF consists of, arranged in order from the object side along the optical axis, a negative meniscus lens L11 with its convex surface facing the object side, a negative meniscus lens L12 with its convex surface facing the object side, a biconvex positive lens L13, and a cemented lens consisting of a biconcave negative lens L14 and a biconvex positive lens L15.

[0186] The rear group GR is composed of, arranged in order from the object side along the optical axis, a cemented lens composed of a negative meniscus lens L21 with its convex surface facing the object side and a positive biconvex lens L22, and a positive biconvex lens L23.

[0187] An image is formed on the sensor by this lens system and photography is performed. Figure 36 shows the image plane I of this lens system. Table 6 below shows the values ​​of each parameter in the sixth embodiment.

[0188] (Table 6) Sixth Example (Basic specifications) f 10.6 FNO 2.9 Y 9.3 TL 105.0 BF 41.2 (surface data) Surface number rd nd νd 1 71.9072 2.1000 1.772500 49.62 2 17.1053 9.7000 3 40.1145 1.7000 1.834810 42.73 4 16.8705 5.7000 5 64.2046 4.0000 1.581440 40.98 6 -20.2776 0.3000 7 -18.2901 2.8000 1.772500 49.62 8 13.8623 5.0000 1.728250 28.38 9 -60.1567 15.3000 10(Aperture)∞ 8.3000 11 162.6653 1.5000 1.846660 23.80 12 25.7615 4.0000 1.497820 82.57 13 -30.6071 0.2000 14 36.1144 3.2000 1.651600 58.57 15 -50.6940 41.2163 Image plane ∞ (Appropriate aspects of the spherical camera) Polyhedron: truncated dodecahedron Surface shape: regular triangle, regular decagon Angle of view 2ωA=66.03° Angle of view 2ωB=106.42° (Suitable Sensor Aspects) b 13.8 a 20.7 2Y-b 4.8 (Suitable embodiment) Embodiments 1, 3, 4, 5

[0189] FIG. 37 is a diagram showing various aberrations of the optical system according to the sixth example of the present application. It can be seen from FIG. 37 that the optical system according to this embodiment has excellent imaging performance with various aberrations being well corrected. It can also be seen that chromatic aberration is well corrected.

[0190] (Seventh Example) The seventh embodiment will be described with reference to Fig. 38, Fig. 39 and Table 7. As shown in Fig. 38, the lens system according to the seventh embodiment is composed of, arranged in order from the object side along the optical axis, a front group GF having negative refractive power, an aperture stop S, and a rear group GR having positive refractive power.

[0191] The front group GF consists of, arranged in order from the object side along the optical axis, a meniscus negative lens L11 with its convex surface facing the object side, a biconcave negative lens L12, a biconvex positive lens L13, a cemented lens consisting of a biconcave negative lens L14 and a biconvex positive lens L15, and a cemented lens consisting of a biconvex positive lens L16 and a meniscus negative lens L17 with its concave surface facing the object side.

[0192] The rear group GR is made up of, in order from the object side along the optical axis, a cemented lens made up of a biconcave negative lens L21 and a biconvex positive lens L22, and a biconvex positive lens L23.

[0193] The image is formed on the sensor by this lens system and photographed. Figure 38 shows the image plane I of this lens system. Table 7 below shows the values ​​of each parameter in the seventh embodiment.

[0194] (Table 7) Seventh Example (Basic specifications) f 5.3 FNO 2.9 Y 7.1 TL 52.3 BF 20.6 (surface data) Surface number rd nd νd 0 (physical surface) ∞ (variable) 1 19.0510 1.0500 1.772500 49.62 2 7.7351 4.1500 3 -53.2941 0.8500 1.834810 42.73 4 10.8083 5.1500 5 18.1526 2.0000 1.581440 40.98 6 -12.9851 0.1500 7 -11.2798 1.4000 1.772500 49.62 8 5.9220 2.5000 1.728250 28.38 9 -33.5208 2.9500 10 114.5371 1.3000 1.517420 52.20 11 -7.7586 0.7000 1.902650 35.73 12 -17.8547 0.9000 13(Aperture)∞ 4.1500 14 -287.5466 0.7500 1.846660 23.80 15 15.1655 2.0000 1.497820 82.57 16 -12.2550 0.1000 17 22.1529 1.6000 1.651600 58.57 18 -24.4248 20.6125 Image plane ∞ (Appropriate aspects of the spherical camera) Polyhedron: Tetrahedron Surface shape: triangle Angle of view 2ωA=150.00° Angle of view 2ωB=191.64° (Suitable Sensor Aspects) b 13.0 a 17.3 2Y-b 1.1 (Suitable embodiment) Embodiments 1, 2, 3, 4, 5

[0195] FIG. 39 is a diagram showing various aberrations of the optical system according to the seventh example of the present application. It can be seen from FIG. 39 that the optical system according to this embodiment has excellent imaging performance with various aberrations being well corrected. It can also be seen that chromatic aberration is well corrected.

[0196] (Eighth Example) The eighth embodiment will be described with reference to Fig. 40, Fig. 41 and Table 8. The lens system according to the eighth embodiment, as shown in Fig. 40, is composed of, arranged in order from the object side along the optical axis, a front group GF having negative refractive power, an aperture stop S, and a rear group GR having positive refractive power.

[0197] The front group GF consists of, arranged in order from the object side along the optical axis, a negative meniscus lens L11 with its convex surface facing the object side, a negative meniscus lens L12 with its convex surface facing the object side, a negative biconcave lens L13, and a positive biconvex lens L14.

[0198] The rear group GR is composed of, arranged in order from the object side along the optical axis, a cemented lens composed of a negative meniscus lens L21 with its convex surface facing the object side and a positive biconvex lens L22, and a positive biconvex lens L23.

[0199] An image is formed on the sensor by this lens system and photography is performed. Figure 40 shows the image plane I of this lens system. Table 8 below shows the values ​​of each parameter in the eighth embodiment.

[0200] (Table 8) Eighth Example (Basic specifications) f 1.2 FNO 2.4 Y 2.0 TL 25.3 BF 4.2 (surface data) Surface number rd nd νd 0 (physical surface) ∞ (variable) 1 11.2896 1.0000 1.816000 46.59 2 4.4729 2.8000 3 34.6641 1.0000 1.651600 58.57 4 2.6641 2.2000 5 -26.3544 1.0000 1.618000 63.34 6 5.1320 1.0000 7 8.6583 2.3000 1.784700 26.27 8 -7.1171 1.7000 9(Aperture)∞ 1.5000 10 23.3054 1.0000 1.846660 23.80 11 2.7304 3.4000 1.640000 60.20 12 -6.3833 0.2000 13 5.2791 2.0000 1.487490 70.31 14 -9.0012 4.1543 Image plane ∞ (Appropriate aspects of the spherical camera) Polyhedron: Tetrahedron Surface shape: triangle Angle of view 2ωA=168.99° Angle of view 2ωB=210.46° (Suitable Sensor Aspects) b 3.6 a 4.8 2Y-b 0.4 (Suitable embodiment) Embodiments 1, 3, 4, 5

[0201] FIG. 41 is a diagram showing various aberrations of the optical system according to the eighth example of the present application. It can be seen from FIG. 41 that the optical system according to this embodiment has excellent imaging performance with various aberrations being well corrected. It can also be seen that chromatic aberration is well corrected.

[0202] (Ninth Example) The ninth embodiment will be described with reference to Fig. 42, Fig. 43 and Table 9. The lens system according to the ninth embodiment, as shown in Fig. 42, is composed of, arranged in order from the object side along the optical axis, a front group GF having negative refractive power, an aperture stop S, and a rear group GR having positive refractive power.

[0203] The front group GF consists of, arranged in order from the object side along the optical axis, a positive meniscus lens L11 with its convex surface facing the object side, a negative meniscus lens L12 with its convex surface facing the object side, a negative meniscus lens L13 with its convex surface facing the object side, a negative meniscus lens L14 with its convex surface facing the object side, and a positive biconvex lens L15.

[0204] The rear group GR consists of, arranged in order from the object side along the optical axis, a meniscus positive lens L21 with its concave surface facing the object side, a biconcave negative lens L22, a meniscus positive lens L23 with its concave surface facing the object side, and a biconvex positive lens L24.

[0205] An image is formed on the sensor by this lens system and photography is performed. Figure 42 shows the image plane I of this lens system. Table 9 below shows the values ​​of each parameter in the ninth embodiment.

[0206] (Table 9) 9th Example (Basic specifications) f 24.7 FNO 2.9 Y 21.6 TL 100.5 BF 38.7 (surface data) Surface number rd nd νd 0 (physical surface) ∞ (variable) 1 78.0268 3.2000 1.607380 56.74 2 253.6694 0.1000 3 32.8224 2.0000 1.620410 60.25 4 16.9540 5.4000 5 31.2315 1.7000 1.620410 60.25 6 15.2730 11.9000 7 81.5836 10.3000 1.620040 36.40 8 49.8037 0.9000 9 28.3581 7.0000 1.672700 32.19 10 -85.8793 0.5000 11(Aperture)∞ 2.0000 12 -443.5370 3.3000 1.620410 60.25 13 -24.8916 1.7000 14 -19.1429 3.8000 1.755200 27.57 15 51.7457 1.4000 16 -54.7480 2.7000 1.620410 60.25 17 -19.6274 0.1000 18 62.5972 3.8000 1.603110 60.69 19 -37.5242 38.7419 Image plane ∞ (Appropriate aspects of the spherical camera) Polyhedron: Dodecahedron Surface shape: pentagon Angle of view 2ωA=41.56° Angle of view 2ωB=83.68° (Suitable Sensor Aspects) b 32.8 a 43.8 2Y-b 10.4 (Suitable embodiment) Embodiments 1, 3, 4, 5

[0207] FIG. 43 is a diagram showing various aberrations of the optical system according to the ninth example of the present application. It can be seen from FIG. 43 that the optical system according to this embodiment has excellent imaging performance with various aberrations being well corrected. It can also be seen that chromatic aberration is well corrected.

[0208] (Tenth Example) The tenth embodiment will be described with reference to Fig. 44, Fig. 45 and Table 10. The lens system according to the tenth embodiment, as shown in Fig. 44, is composed of, arranged in order from the object side along the optical axis, a front group GF having negative refractive power, an aperture stop S, and a rear group GR having positive refractive power.

[0209] The front group GF is composed of, arranged in order from the object side along the optical axis, a negative meniscus lens L11 with its convex surface facing the object side, and a positive biconvex lens L12.

[0210] The rear group GR is composed of, arranged in order from the object side along the optical axis, a biconcave negative lens L21, a meniscus positive lens L22 with its concave surface facing the object side, and a biconvex positive lens L23.

[0211] The image is formed on the sensor by this lens system and photographed. Figure 44 shows the image plane I of this lens system. Table 10 below shows the values ​​of each parameter in the tenth embodiment.

[0212] (Table 10) 10th Example (Basic specifications) f 28.8 FNO 2.9 Y 21.6 TL 85.1 BF 38.2 (surface data) Surface number rd nd νd 0 (physical surface) ∞ (variable) 1 35.2519 1.8000 1.744000 44.81 2 15.6000 22.0000 3 27.5072 3.7000 1.667550 41.87 4 -44.7541 3.4000 5(Aperture)∞ 6.1000 6 -16.2873 2.5000 1.755200 27.57 7 55.0934 0.7000 8 -92.3218 3.2000 1.620410 60.25 9 -17.2910 0.1000 10 1171.3554 3.4000 1.620410 60.25 11 -25.8389 38.2029 Image plane ∞ (Appropriate aspects of the spherical camera) Polyhedron: Dodecahedron Surface shape: pentagon Angle of view 2ωA=38.21° Angle of view 2ωB=75.76° (Suitable Sensor Aspects) b 32.8 a 43.8 2Y-b 10.4 (Suitable embodiment) Embodiments 1, 3, 4, 5

[0213] FIG. 45 is a diagram showing various aberrations of the optical system according to the tenth example of the present application. It can be seen from FIG. 45 that the optical system according to this embodiment has excellent imaging performance with various aberrations being well corrected. It can also be seen that chromatic aberration is well corrected.

[0214] (Eleventh Example) Example 11 will be described with reference to Fig. 46, Fig. 47 and Table 11. The lens system according to Example 11, as shown in Fig. 46, is composed of, arranged in order from the object side along the optical axis, a front group GF having negative refractive power, an aperture stop S, and a rear group GR having positive refractive power.

[0215] The front group GF consists of, arranged in order from the object side along the optical axis, a negative meniscus lens L11 with its convex surface facing the object side, a negative meniscus lens L12 with its convex surface facing the object side, a negative biconcave lens L13, and a positive biconvex lens L14.

[0216] The rear group GR is composed of, arranged in order from the object side along the optical axis, a cemented lens composed of a negative meniscus lens L21 with its convex surface facing the object side and a positive biconvex lens L22, and a positive biconvex lens L23.

[0217] An image is formed on the sensor by this lens system and photography is performed. Figure 46 shows the image plane I of this lens system. Table 11 below shows the values ​​of each parameter in the eleventh embodiment.

[0218] (Table 11) 11th Example (Basic specifications) f 1.3 FNO 2.4 Y 1.8 TL 29.4 BF 4.1 (surface data) Surface number rd nd νd 0 (physical surface) ∞ (variable) 1 13.9231 1.0000 1.816000 46.59 2 5.7304 2.8000 3 11.5364 1.0000 1.640000 60.20 4 3.5677 2.2000 5 -7.0323 1.0000 1.618000 63.34 6 6.0645 1.0000 7 48.5130 2.3000 1.784720 25.64 8 -7.1368 6.4000 9(Aperture)∞ 1.0000 10 8.6863 1.0000 1.860740 23.08 11 3.4253 3.4000 1.640000 60.20 12 -7.7283 0.2000 13 5.0069 2.0000 1.497820 82.57 14 -111.8112 4.1435 Image plane ∞ (Appropriate aspects of the spherical camera) Polyhedron: Tetrahedron Surface shape: triangle Angle of view 2ωA=141.06° Angle of view 2ωB=176.95° (Suitable Sensor Aspects) b 3.6 a 4.8 2Y-b 0.0 (Suitable embodiment) Embodiments 2, 4, and 5

[0219] FIG. 47 is a diagram showing various aberrations of the optical system according to the eleventh example of the present application. It can be seen from FIG. 47 that the optical system according to this embodiment has excellent imaging performance with various aberrations being well corrected. It can also be seen that chromatic aberration is well corrected.

[0220] (Twelfth Example) The twelfth embodiment will be described with reference to Fig. 48, Fig. 49 and Table 12. As shown in Fig. 48, the lens system according to the twelfth embodiment is composed of, arranged in order from the object side along the optical axis, a front group GF having negative refractive power, an aperture stop S, and a rear group GR having positive refractive power.

[0221] The front group GF consists of, arranged in order from the object side along the optical axis, a negative meniscus lens L11 with its convex surface facing the object side, a negative meniscus lens L12 with its convex surface facing the object side, a negative meniscus lens L13 with its convex surface facing the object side, and a positive meniscus lens L14 with its concave surface facing the object side.

[0222] The rear group GR is composed of, arranged in order from the object side along the optical axis, a cemented lens composed of a negative meniscus lens L21 with its convex surface facing the object side and a positive biconvex lens L22, and a positive biconvex lens L23.

[0223] The image is formed on the sensor by this lens system and photographed. Figure 48 shows the image plane I of this lens system. Table 12 below shows the values ​​of each parameter in the twelfth embodiment.

[0224] (Table 12) 12th Example (Basic specifications) f 1.6 FNO 2.4 Y 2.4 TL 26.8 BF 5.5 (surface data) Surface number rd nd νd 0 (physical surface) ∞ (variable) 1 19.5882 1.0000 1.785900 44.17 2 5.1167 2.8000 3 34.8507 1.0000 1.651600 58.57 4 3.0717 2.1000 5 23.1776 1.0000 1.620410 60.25 6 6.3466 1.0000 7 -93.1757 2.0000 1.805180 25.45 8 -5.4075 3.7000 9(Aperture)∞ 1.0000 10 18.0176 1.0000 1.755200 27.57 11 3.3693 2.6000 1.456000 91.36 12 -5.1070 0.2000 13 8.2839 1.9000 1.487490 70.31 14 -6.5914 5.4920 Image plane ∞ (Appropriate aspects of the spherical camera) Polyhedron: Tetrahedron Surface shape: triangle Angle of view 2ωA=147.68° Angle of view 2ωB=187.68° (Suitable Sensor Aspects) b 3.6 a 4.8 2Y-b 1.12 (Suitable embodiment) Embodiments 2, 3, 4, and 5

[0225] FIG. 49 is a diagram showing various aberrations of the optical system according to the twelfth example of the present application. It can be seen from FIG. 49 that the optical system according to this embodiment has excellent imaging performance with various aberrations being well corrected. It can also be seen that chromatic aberration is well corrected.

[0226] (Thirteenth Example) The thirteenth embodiment will be described with reference to Fig. 50, Fig. 51 and Table 13. The lens system according to the thirteenth embodiment, as shown in Fig. 50, is composed of, arranged in order from the object side along the optical axis, a front group GF having negative refractive power, an aperture stop S, and a rear group GR having positive refractive power.

[0227] The front group GF consists of, arranged in order from the object side along the optical axis, a meniscus negative lens L11 with its convex surface facing the object side, a meniscus negative lens L12 with its convex surface facing the object side, a biconvex positive lens L13, a cemented lens consisting of a biconcave negative lens L14 and a biconvex positive lens L15, and a cemented lens consisting of a meniscus positive lens L16 with its concave surface facing the object side and a meniscus negative lens L17 with its concave surface facing the object side.

[0228] The rear group GR is made up of, in order from the object side along the optical axis, a cemented lens made up of a biconcave negative lens L21 and a biconvex positive lens L22, and a biconvex positive lens L23.

[0229] The image is formed on the sensor by this lens system and photographed. Figure 50 shows the image plane I of this lens system. Table 13 below shows the values ​​of each parameter in the thirteenth embodiment.

[0230] (Table 13) Thirteenth Example (Basic specifications) f 5.3 FNO 2.9 Y 6.3 TL 52.5 BF 20.6 (surface data) Surface number rd nd νd 0 (physical surface) ∞ (variable) 1 30.0568 1.0500 1.772500 49.62 2 7.6511 4.8500 3 39.8358 0.8500 1.834810 42.73 4 10.4634 2.8500 5 28.2483 2.0000 1.581440 40.98 6 -11.4938 0.1500 7 -10.1784 1.4000 1.772500 49.62 8 5.9730 2.5000 1.728250 28.38 9 -31.0695 4.7500 10 -27.9408 1.3000 1.517420 52.20 11 -6.4605 0.7000 1.902650 35.73 12 -10.5703 0.9000 13(Aperture)∞ 4.1500 14 -671.7000 0.7500 1.846660 23.80 15 16.8040 2.0000 1.497820 82.57 16 -13.6708 0.1000 17 22.5239 1.6000 1.651600 58.57 18 -24.9089 20.6111 Image plane ∞ (Appropriate aspects of the spherical camera) Polyhedron: Regular octahedron Surface shape: equilateral triangle Angle of view 2ωA=109.47° Angle of view 2ωB=150.02° (Suitable Sensor Aspects) b 8.8 a 13.2 2Y-b 3.7 (Suitable embodiment) Embodiments 3, 4, and 5

[0231] FIG. 51 is a diagram showing various aberrations of the optical system according to the thirteenth embodiment of the present application. It can be seen from FIG. 51 that the optical system according to this embodiment has excellent imaging performance with various aberrations being well corrected. It can also be seen that chromatic aberration is well corrected.

[0232] (14th Example) The fourteenth embodiment will be described with reference to Fig. 52, Fig. 53 and Table 14. As shown in Fig. 52, the lens system according to the fourteenth embodiment is composed of, arranged in order from the object side along the optical axis, a front group GF having negative refractive power, an aperture stop S, and a rear group GR having positive refractive power.

[0233] The front group GF consists of, arranged in order from the object side along the optical axis, a meniscus negative lens L11 with its convex surface facing the object side, a meniscus negative lens L12 with its convex surface facing the object side, a biconvex positive lens L13, a cemented lens consisting of a biconcave negative lens L14 and a biconvex positive lens L15, and a cemented lens consisting of a meniscus positive lens L16 with its concave surface facing the object side and a meniscus negative lens L17 with its concave surface facing the object side.

[0234] The rear group GR is made up of, in order from the object side along the optical axis, a cemented lens made up of a biconcave negative lens L21 and a biconvex positive lens L22, and a biconvex positive lens L23.

[0235] The image is formed on the sensor by this lens system and photographed. Figure 52 shows the image plane I of this lens system. Table 14 below shows the values ​​of each parameter in the fourteenth embodiment.

[0236] (Table 14) 14th Example (Basic specifications) f 10.6 FNO 2.9 Y 10.2 TL 105.0 BF 41.2 (surface data) Surface number rd nd νd 0 (physical surface) ∞ (variable) 1 58.7110 2.1000 1.772500 49.62 2 15.3501 9.7000 3 96.6445 1.7000 1.834810 42.73 4 21.1455 5.7000 5 52.2647 4.0000 1.581440 40.98 6 -23.5276 0.3000 7 -20.7612 2.8000 1.772500 49.62 8 11.8123 5.0000 1.728250 28.38 9 -64.2676 9.5000 10 -63.6732 2.6000 1.517420 52.20 11 -12.9573 1.4000 1.902650 35.73 12 -21.5909 1.8000 13(Aperture)∞ 8.3000 14 -1118.3104 1.5000 1.846660 23.80 15 33.9487 4.0000 1.497820 82.57 16 -26.9411 0.2000 17 45.9639 3.2000 1.651600 58.57 18 -49.7473 41.2241 Image plane ∞ (Appropriate aspects of the spherical camera) Polyhedron: Icosahedron Surface shape: equilateral triangle Angle of view 2ωA=74.75° Angle of view 2ωB=115.40° (Suitable Sensor Aspects) b 13.8 a 20.7 2Y-b 6.4 (Suitable embodiment) Embodiments 3, 4, and 5

[0237] FIG. 53 is a diagram showing various aberrations of the optical system according to the fourteenth example of the present application. It can be seen from FIG. 53 that the optical system according to this embodiment has excellent imaging performance with various aberrations being well corrected. It can also be seen that chromatic aberration is well corrected.

[0238] (Fifteenth Example) The fifteenth embodiment will be described with reference to Fig. 54, Fig. 55 and Table 15. The lens system according to the fifteenth embodiment, as shown in Fig. 54, is composed of, arranged in order from the object side along the optical axis, a front group GF having negative refractive power, an aperture stop S, and a rear group GR having positive refractive power.

[0239] The front group GF consists of, arranged in order from the object side along the optical axis, a meniscus negative lens L11 with its convex surface facing the object side, a meniscus negative lens L12 with its convex surface facing the object side, a biconvex positive lens L13, a cemented lens consisting of a biconcave negative lens L14 and a biconvex positive lens L15, and a cemented lens consisting of a meniscus positive lens L16 with its concave surface facing the object side and a meniscus negative lens L17 with its concave surface facing the object side.

[0240] The rear group GR is made up of, in order from the object side along the optical axis, a cemented lens made up of a biconcave negative lens L21 and a biconvex positive lens L22, and a biconvex positive lens L23.

[0241] The image is formed on the sensor by this lens system and photographed. Figure 54 shows the image plane I of this lens system. Table 15 below shows the values ​​of each parameter in the fifteenth embodiment.

[0242] Table 15: 15th Example (Basic specifications) f 10.6 FNO 2.9 Y 6.3 TL 105.0 BF 41.2 (surface data) Surface number rd nd νd 0 (physical surface) ∞ (variable) 1 60.1136 2.1000 1.772500 49.62 2 15.3022 9.7000 3 79.6717 1.7000 1.834810 42.73 4 20.9269 5.7000 5 56.4966 4.0000 1.581440 40.98 6 -22.9875 0.3000 7 -20.3569 2.8000 1.772500 49.62 8 11.9459 5.0000 1.728250 28.38 9 -62.1390 ​​9.5000 10 -55.8816 2.6000 1.517420 52.20 11 -12.9209 1.4000 1.902650 35.73 12 -21.1407 1.8000 13(Aperture)∞ 8.3000 14 -1343.4000 1.5000 1.846660 23.80 15 33.6080 4.0000 1.497820 82.57 16 -27.3417 0.2000 17 45.0478 3.2000 1.651600 58.57 18 -49.8177 41.2223 Image plane ∞ (Appropriate aspects of the spherical camera) Polyhedron: Regular octahedron Surface shape: equilateral triangle Angle of view 2ωA=109.47° Angle of view 2ωB=150.02° (Suitable Sensor Aspects) b 8.8 a 13.2 2Y-b 3.7 (Suitable embodiment) Embodiments 3, 4, and 5

[0243] FIG. 55 is a diagram showing various aberrations of the optical system according to the fifteenth example of the present application. It can be seen from FIG. 55 that the optical system according to this embodiment has excellent imaging performance with various aberrations being well corrected. It can also be seen that chromatic aberration is well corrected.

[0244] (16th Example) The 16th embodiment will be described with reference to Fig. 56, Fig. 57 and Table 16. As shown in Fig. 56, the lens system according to the 16th embodiment is composed of, arranged in order from the object side along the optical axis, a front group GF having negative refractive power, an aperture stop S, and a rear group GR having positive refractive power.

[0245] The front group GF consists of, arranged in order from the object side along the optical axis, a negative meniscus lens L11 with its convex surface facing the object side, a negative meniscus lens L12 with its convex surface facing the object side, a negative meniscus lens L13 with its convex surface facing the object side, and a positive biconvex lens L14.

[0246] The rear group GR is composed of, arranged in order from the object side along the optical axis, a cemented lens composed of a negative meniscus lens L21 with its convex surface facing the object side and a positive biconvex lens L22, and a positive biconvex lens L23.

[0247] The image is formed on the sensor by this lens system and photographed. Figure 56 shows the image plane I of this lens system. Table 16 below shows the values ​​of each parameter in the 16th embodiment.

[0248] (Table 16) 16th Example (Basic specifications) f 1.3 FNO 2.4 Y 2.0 TL 25.3 BF 4.2 (surface data) Surface number rd nd νd 0 (physical surface) ∞ (variable) 1 18.0049 1.0000 1.785900 44.17 2 4.0576 2.8000 3 24.2007 1.0000 1.651600 58.57 4 2.8982 2.2000 5 40.6251 1.0000 1.620410 60.25 6 4.0195 1.0000 7 27.1564 2.3000 1.805180 25.45 8 -4.8159 1.7000 9(Aperture)∞ 1.5000 10 19.1090 1.0000 1.784720 25.64 11 2.6361 3.4000 1.603110 60.69 12 -4.5563 0.2000 13 11.3779 2.0000 1.487490 70.31 14 -12.5346 4.1837 Image plane ∞ (Appropriate aspects of the spherical camera) Polyhedron: Hemisphere (2 eyes) Angle of view 2ωA=180.00° Angle of view 2ωB=221.88° (Suitable Sensor Aspects) b 3.6 a 4.8 2Y-b 0.5 (Suitable embodiment) Embodiments 3, 4, and 5

[0249] FIG. 57 is a diagram showing various aberrations of the optical system according to the sixteenth example of the present application. It can be seen from FIG. 57 that the optical system according to this embodiment has excellent imaging performance with various aberrations being well corrected. It can also be seen that chromatic aberration is well corrected.

[0250] Table 17 below shows the values ​​of each conditional expression for each embodiment. [Table 17]

[0251] According to each of the above-mentioned embodiments, it is possible to obtain a high-quality image while using a wide-field optical device that combines a plurality of lens systems and is small in size.

[0252] In order to make the present invention easier to understand, the present invention has been described above with reference to the configurational features of the embodiment, but it goes without saying that the present invention is not limited to this. [Explanation of symbols]

[0253] OL optical equipment GF 1st lens group GR 2nd lens group S aperture stop I image plane IS Sensor a The length of the long side of the sensor b The length of the short side of the sensor IC Image Circle CAM Spherical camera (optical device)

Claims

1. In a spherical camera having four or more lens systems and in which optical paths intersect, A space in which no member is disposed is provided at a location where the optical paths intersect, A celestial sphere camera that satisfies the following conditional expression, where TL is the distance on the optical axis from the surface closest to the object of the lens system to the image plane, and K is the distance on the optical axis from the point where the optical paths intersect to the image plane. 0.1 < K / TL < 0.9

2. The omnidirectional camera according to claim 1 , comprising four lens systems.

3. 3. The omnidirectional camera according to claim 1, wherein the four lens systems are arranged in a regular tetrahedron.

4. The omnidirectional camera according to claim 1 , wherein all of the lens systems are the same lens system.

5. 5. The omnidirectional camera according to claim 1, further comprising the lens system having a maximum angle of view of 140 degrees or more.

6. 6. The omnidirectional camera according to claim 1, wherein the following conditional expression is satisfied: fa is a focal length from the surface of the lens system closest to the object side to the aperture, and fb is a focal length from the aperture to the surface of the lens system closest to the image side. -20.0 < fa / fb < 20.0

7. The omnidirectional camera according to any one of claims 1 to 6, wherein the following conditional formula is satisfied: a maximum diameter of φ3 among optical elements adjacent to a portion where the optical paths of the lens system intersect, and a length in the optical axis direction of the portion where the optical paths intersect is D: 0.1 < D / φ3 < 10.0

8. 8. The omnidirectional camera according to claim 1, wherein the following conditional expression is satisfied: TL is a distance on the optical axis from the surface closest to the object of the lens system to an image forming surface, and S is a distance on the optical axis from a stop to the image forming surface. 0.20 < S / TL < 0.80

Images