阅读说明：本技术 透镜系统、摄像机系统以及摄像系统 (Lens system, camera system, and imaging system ) 是由 松村善夫 于 2018-02-13 设计创作，主要内容包括：本公开的透镜系统是在配置于光轴的矩形的摄像元件成像的透镜系统,具备相对于光轴非对称的第2自由曲面透镜,从光轴离开相对于最短像高的给定的比率的长度的圆上的第2自由曲面透镜的凹陷量在与穿过光轴并与摄像元件的长边平行的第1面以及穿过光轴并与摄像元件的短边平行的第2面的交点以外具有极值。(The lens system of the present disclosure forms an image on a rectangular image pickup device disposed on an optical axis, and includes a 2 nd free-form surface lens asymmetric with respect to the optical axis, and a depression amount of the 2 nd free-form surface lens on a circle separated from the optical axis by a length of a given ratio with respect to a shortest image height has an extreme value other than an intersection point with a 1 st surface passing through the optical axis and parallel to a long side of the image pickup device and a 2 nd surface passing through the optical axis and parallel to a short side of the image pickup device.)

1. A lens system for forming an image on a rectangular image pickup element disposed on an optical axis,

the lens system includes: a 2 nd free-form lens asymmetrical with respect to the optical axis,

the amount of depression of the 2 nd free-form surface lens on a circle that is separated from the optical axis by a length of a given ratio with respect to a shortest image height has an extreme value other than an intersection of a 1 st surface that passes through the optical axis and is parallel to a long side of the image pickup element and the circle and an intersection of a 2 nd surface that passes through the optical axis and is parallel to a short side of the image pickup element and the circle.

2. The lens system of claim 1,

the given ratio is 40% to 80%.

3. The lens system of claim 1 or 2,

an aperture stop is provided between the object side and the image plane side,

the optical pickup device includes a 1 st free-form surface lens on an object side of the aperture stop and a 2 nd free-form surface lens on an image side of the aperture stop.

4. The lens system of claim 3,

the 2 nd free-form surface lens is disposed on the most image surface side, and both the object side and the image surface side are free-form surfaces.

5. The lens system according to any one of claims 1 to 4,

the object side sequentially has: a 1 st lens element which is a meniscus lens having a negative refractive power and is convex toward the object side; and a 2 nd lens element having a negative power.

6. The lens system of claim 5,

the 1 st free-form surface lens is disposed on the image plane side of the 2 nd lens element, and at least the object side is a free-form surface.

7. The lens system of any of claims 1 to 6,

there are at least 3 or more lens elements that are rotationally symmetric with respect to the optical axis.

8. The lens system according to any one of claims 1 to 7,

the extreme value is within a range of ± 25 ° from an intersection point of a light-sensing surface of the image-pickup element and the optical axis to a direction of a corner of the light-sensing surface.

9. The lens system according to any one of claims 1 to 7,

when the ratio of the long side to the short side of the light-sensing surface of the image-sensing element is a to b, tan is formed on the 1 st surface^-1(b/a) ± 25 ° having said extremum.

10. The lens system according to any one of claims 1 to 7,

when the ratio of the long side to the short side of the image pickup element is 16 to 9, the extremum is present in a range of 29 ± 25 ° with respect to the 1 st plane.

11. The lens system according to any one of claims 1 to 7,

having said extreme value in the range of 33 ± 21 ° with respect to said 1 st face.

12. The lens system of claim 1,

the lens system satisfies the following condition (1):

ω_LONG＞60° …(1)

in this case, the amount of the solvent to be used,

ω_LONG: the maximum half angle of view in the longitudinal direction of the image pickup element.

13. The lens system of claim 1,

the lens system satisfies the following condition (2):

1＜D_LSHORT/D_SSHORT…(2)

in this case, the amount of the solvent to be used,

D_LSHORT: a maximum distance in the longitudinal direction between an image point of incident light in the longitudinal direction of the image pickup element at an angle of view equal to a maximum half angle of view in the short-side direction of the image pickup element and an image point of incident light perpendicular to the image pickup element,

D_SSHORT: the maximum distance in the short side direction between the image point of the incident light with the maximum half angle of view in the short side direction of the imaging element and the image point of the incident light perpendicular to the imaging element.

14. The lens system of claim 1,

the lens system satisfies the following condition (3):

0.5＜D_SSHORT×ω_LONG/(D_LLONG×ω_SHORT)＜1 …(3)

in this case, the amount of the solvent to be used,

ω_LONG: the maximum half angle of view in the longitudinal direction of the image pickup element,

ω_SHORT: the maximum half angle of view in the short side direction of the image pickup element,

D_LLONG: the maximum distance in the longitudinal direction between the image point of the incident light with the maximum half angle of view in the longitudinal direction of the image pickup element and the image point of the incident light perpendicular to the image pickup element,

D_SSHORT: an image point of incident light with a maximum half angle of view in a short side direction of the image pickup device and an image point of incident light with a maximum half angle of view perpendicular to the image pickup deviceThe maximum distance in the short side direction of the image point of the incident light.

15. The lens system of claim 1,

the lens system satisfies the following condition (4):

ω_LONG-ω_SHORT＞0 …(4)

in this case, the amount of the solvent to be used,

ω_LONG: the maximum half angle of view in the longitudinal direction of the image pickup element,

ω_SHORT: the maximum half angle of view in the short side direction of the image pickup element.

16. The lens system of claim 1,

the lens system satisfies the following condition (5):

L×Fno./D_LLONG＜40 …(5)

in this case, the amount of the solvent to be used,

l: the total optical length of the lens system is,

fno.: the F-number of the lens system is,

D_LLONG: the maximum distance in the longitudinal direction between an image point of incident light at a maximum half angle of view in the longitudinal direction of the image pickup device and an image point of incident light perpendicular to the image pickup device.

17. The lens system of claim 1,

the lens system satisfies the following condition (6):

n_FREE＜1.7 …(6)

in this case, the amount of the solvent to be used,

n_FREE: refractive index of the 1 st or 2 nd free-form surface lens with respect to d-line.

18. The lens system of claim 1,

the lens system further includes a lens element and an aperture stop, and satisfies the following condition (7):

-3≤N_o-N_i≤3 …(7)

in this case, the amount of the solvent to be used,

N_o: the number of lens elements on the object side of the aperture stop,

N_i: the number of lens elements on the image plane side of the aperture stop, wherein the lens elements include a 2 nd free-form surface lens.

19. The lens system of claim 1,

the image pickup element does not include an image circle of the lens system.

20. A camera system is provided with:

the lens system of claim 1; and

and the rectangular image pickup element is arranged at a position where the optical axis forms an image by the lens system.

21. An imaging system includes:

the lens system of claim 1;

the rectangular image pickup element disposed at a position where the lens system forms an image on the optical axis; and

and an image processing unit that processes the image generated by the image pickup device.

Technical Field

The present disclosure relates to a lens system, a camera system, and an image pickup system.

Background

When an image formed by a lens of a non-center projection system deviates from a rectangular shape, the area of the photosensitive surface that is not used is increased because the optical image and the image sensor do not overlap each other when a rectangular image sensor is used.

Patent document 1 discloses a method of capturing a panoramic image with a rectangular image sensor. Patent document 1 discloses an image pickup device in which a circular image is formed into a rectangular image by using a circular ring lens in a fish-eye objective lens, and the rectangular image is formed on the image pickup device.

Disclosure of Invention

Provided are a lens system capable of effectively utilizing the region of a light-receiving surface of a rectangular image pickup element, a camera system including the lens, and an image pickup system.

The lens system of the present disclosure is a lens system for forming an image on an imaging element arranged in a rectangular shape on an optical axis, and includes a 2 nd free-form surface lens asymmetric with respect to the optical axis, and a depression amount of the 2 nd free-form surface lens on a circle separated from the optical axis by a length of a given ratio with respect to a shortest image height has an extreme value except for an intersection point of a 1 st surface passing through the optical axis and being parallel to a long side of the imaging element and the circle and an intersection point of a 2 nd surface passing through the optical axis and being parallel to a short side of the imaging element and the circle.

The camera system of the present disclosure includes: the above lens system of the present disclosure; and a rectangular image pickup element disposed at a position where the lens system forms an image on an optical axis.

The imaging system of the present disclosure includes: the above lens system of the present disclosure; a rectangular image pickup element disposed at a position where the optical axis of the image pickup element forms an image on the lens system; and an image processing unit that processes the image generated by the image pickup element.

In the present invention, a lens system that forms a substantially rectangular image, a camera system including the lens system, and an imaging system can be realized.

Drawings

Fig. 1 is a lens arrangement diagram showing an infinite focus state of a lens system according to embodiment 1.

Fig. 2 is a lens arrangement diagram showing an infinite focus state of the lens system according to embodiment 2.

Fig. 3 is a lens arrangement diagram showing an infinite focus state of the lens system according to embodiment 3.

Fig. 4 is a schematic view of the light-sensing surfaces of the imaging devices according to embodiments 1 to 3.

Fig. 5 is a diagram showing a relationship between a depression amount and an angle (phase) around an optical axis of a free-form surface lens of the lens system according to embodiment 1.

Fig. 6 is a diagram showing a relationship between a depression amount and an angle (phase) around an optical axis of a free-form surface lens of the lens system according to embodiment 2.

Fig. 7 is a diagram showing a relationship between a depression amount and an angle (phase) around an optical axis of a free-form surface lens of the lens system according to embodiment 3.

Fig. 8 is a schematic configuration diagram of a camera system according to embodiment 4.

Fig. 9 is a schematic configuration diagram of an imaging system according to embodiment 5.

Fig. 10 is an aberration diagram showing spherical aberration and field curvature in an infinite focus state of the lens system according to numerical example 1.

Fig. 11 is a diagram showing a relationship between an angle of view and an image point in an infinite focus state of the lens system according to numerical example 1.

Fig. 12 is an aberration diagram showing spherical aberration and field curvature in an infinite focus state of the lens system according to numerical example 2.

Fig. 13 is a diagram showing a relationship between an angle of view and an image point in an infinite focus state of the lens system according to numerical example 2.

Fig. 14 is an aberration diagram showing spherical aberration and field curvature in an infinite focus state of the lens system according to numerical example 3.

Fig. 15 is a diagram showing a relationship between an angle of view and an image point in an infinite focus state of the lens system according to numerical example 3.

Detailed Description

The embodiments are described in detail below with reference to the accompanying drawings as appropriate. However, the above detailed description may be omitted. For example, detailed descriptions of already widely known matters and repetitive descriptions of substantially the same configuration may be omitted. This is to avoid unnecessary redundancy of the following description, which will make understanding easy for those skilled in the art.

The drawings and the following description are provided for those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

(embodiment mode 1)

Fig. 1 is a configuration diagram of a lens system according to embodiment 1, showing an infinity focus state.

Fig. 1 (a) is a YZ cross section, and fig. 1 (b) is an XZ cross section, which represents a lens system 111 having 8 lens elements and a rectangular image pickup element 102 having a short side and a long side. The X direction is a direction parallel to the long side of the image pickup device 102, the Y direction is a direction parallel to the short side of the image pickup device 102, and the Z direction is a direction parallel to the optical axis. In addition, the YZ cross section is a plane including the optical axis and parallel to the Y direction and the Z direction. The XZ section is a plane containing the optical axis and parallel to the X direction and the Z direction.

As shown in fig. 1, the lens system 111 according to embodiment 1 includes 5 lens elements L1 to L5, an aperture stop a, and 3 lens elements L6 to L8 in this order from the object side to the image surface side. The position of the lens system 111 where an image is formed is an image plane of the image pickup device 102. Reference numerals are omitted in fig. 1 (b).

The lens system 111 is further described in detail. The lens system 111 is composed of the following elements from the object side to the image surface side: a negative meniscus lens element L1 with the convex surface facing the object side; two concave-shaped lens elements L2; two concave-shaped lens elements L3; a lenticular element L4 of biconvex shape; a positive meniscus lens element L5 whose both surfaces are formed aspherical and whose convex surface faces the object side; an aperture diaphragm A; a lenticular element L6 of biconvex shape; a negative meniscus lens element L7 having a convex surface facing the image plane side; and a positive meniscus-shaped lens element L8 with the convex surface directed to the object side. Lens element L6 and lens element L7 were joined. Here, lens element L1 is an example of the 1 st lens element, and lens element L2 is an example of the 2 nd lens element.

In the lens system 111, both the object side and the image plane side of the lens element L3 and the lens element L8 are free-form surfaces of XY polynomial. In fig. 1, a seal is attached to the free-form surface. Here, the lens element L3 is an example of a 1 st free-form surface lens, and the lens element L8 is an example of a 2 nd free-form surface lens.

The amount of recess of each circle having a length of 40% or more of the shortest image height, which is separated from the optical axis, of the free-form surface on the image plane side of the lens element L8 has an extreme value other than the intersection point of the XZ plane (1 st plane) passing through the optical axis and parallel to the long side of the image pickup device 102 and the YZ plane (2 nd plane) passing through the optical axis and parallel to the short side of the image pickup device 102. Here, the depression amount is a distance in a direction parallel to the optical axis from the reference plane to a certain point on the surface of the lens element when a plane orthogonal to the optical axis including an intersection with the surface of the lens element is taken as the reference plane. The numerical expression indicating the amount of recess and the surface data of each lens element will be described later. The surface shapes of the free-form surface lens and the aspherical surface lens are expressed in the vicinity of the optical axis (vertex) in the Y direction.

(embodiment mode 2)

Fig. 2 is a layout diagram of a lens system according to embodiment 2. Fig. 2 (a) is a YZ cross section, and fig. 2 (b) is an XZ cross section, which represents a lens system 121 composed of 8 lens elements and a rectangular image pickup element 102 having a short side and a long side. Reference numerals are omitted in fig. 2 (b). In the lens system 121 according to embodiment 2, the number of lens elements, the type of lens elements, and the order of arrangement are the same as those of the lens system 111 according to embodiment 1, and the surface data of the lens system elements L1 to L8 are different from each other. The difference points of the plane data will be described later. In the lens system 121, the lens element L1 is an example of a 1 st lens element, the lens element L2 is an example of a 2 nd lens element, the lens element L3 is an example of a 1 st free-form surface lens, and the lens element L8 is an example of a 2 nd free-form surface lens.

In the lens system 121 according to embodiment 2, the amount of recess of the free-form surface of the lens element L8 on the image plane side on each circle having a length of 20% or more of the shortest image height from the optical axis has an extreme value other than the intersection point of the XZ plane (1 st plane) passing through the optical axis and parallel to the long side of the image pickup element 102 and the YZ plane (2 nd plane) passing through the optical axis and parallel to the short side of the image pickup element 102.

(embodiment mode 3)

Fig. 3 is a layout diagram of a lens system according to embodiment 3. Fig. 3 (a) is a YZ cross section, and fig. 3 (b) is an XZ cross section, representing a lens system 131 having 7 lens elements and a rectangular image pickup element 102 having a short side and a long side. Reference numerals are omitted in fig. 3 (b). The lens system 131 of embodiment 3 differs from the lens system 111 of embodiment 1 in the number of lens elements (7 lens elements) and surface data of each of the lens system elements L1 to L7.

As shown in fig. 3, the lens system 131 according to embodiment 3 includes 4 lens elements L1 to L4, an aperture stop a, and 3 lens elements L5 to L7 in this order from the object side to the image surface side. The position of the image formed by the lens system 131 is the image plane of the image sensor 102. The difference points of the plane data will be described later.

The lens system 131 is further described in detail. The lens system 131 includes the following elements in order from the object side to the image side: a negative meniscus lens element L1 with the convex surface facing the object side; a lens element L2 whose both surfaces are formed with aspherical surfaces and which is shaped in two concave shapes; two concave-shaped lens elements L3; a lens element L4 whose object-side surface is formed to be aspherical and has a biconvex shape; an aperture diaphragm A; a lens element L5 whose object-side surface is formed to be aspherical and has a biconvex shape; a negative meniscus lens element L6 having an aspherical surface on the image plane side and a convex surface facing the image plane side; and a lenticular element L7 of a lenticular shape. Lens element L5 and lens element L6 were joined. Here, lens element L1 is an example of the 1 st lens element, and lens element L2 is an example of the 2 nd lens element.

In the lens system 131, the object-side surface of the lens element L3 is a free-form surface of XY polynomial, and the image-side surface is an aspherical surface. Both the object side and the image surface side of the lens element L7 are free-form surfaces of XY polynomial. In fig. 3, a seal is attached to the free-form surface. Here, the lens element L3 is an example of a 1 st free-form surface lens, and the lens element L7 is an example of a 2 nd free-form surface lens.

The amount of recess of the object-side free-form surface of the lens element L7 on a circle having a length of 30% or more of the shortest image height from the optical axis has an extreme value other than the intersection point with the XZ plane (1 st plane) passing through the optical axis and parallel to the long side and short side of the image pickup device 102 and the YZ plane (2 nd plane) passing through the optical axis and parallel to the short side of the image pickup device 102.

(common configuration of embodiments 1 to 3)