Optical system and imaging device

Abstract

The optical system includes a first optical element group including a lens group including at least one lens and having a positive refractive power, and a reflecting optical element having a reflecting surface capable of bending an optical axis, which are arranged in order from the object side to the image side, a second optical element group including at least three lenses and having a negative refractive power, and a third optical element group including at least one lens and having a positive refractive power, and the focal length of the third optical element group is f G3 When the focal length of the entire optical system when focused at infinity is f, 3>f G3 / f>0.5.

Description

[Technical field]

[0001] The present invention relates to an optical system including a plurality of optical elements, and an imaging device including the optical system. [Background technology]

[0002] 2. Description of the Related Art Various optical systems equipped with reflecting optical elements have been conventionally known.

[0003] For example, the optical system described in CN216956501U includes, arranged in order from the object side to the image side, a first lens group having a first lens with positive refractive power and a prism capable of bending the optical axis, a second lens group including two lenses, and a third lens group including one lens, and focuses by moving the third lens group in the optical axis direction.

[0004] Also, the optical system described in US9557627B2 includes a first lens group having a first lens with positive refractive power and a prism capable of bending an optical axis, and a second lens group including four lenses, which are arranged in order from the object side to the image side, and focusing is performed by moving the second lens group in the optical axis direction. The total optical length TTL of this optical system is 16 mm or less, and the focal length is in the range of 8 to 14 mm.

[0005] The optical system described in US20210048628A1 includes a first lens group having a first lens with positive refractive power and a prism capable of bending an optical axis, which are arranged in order from the object side to the image side, and a second lens group including four lenses, and focuses by moving the second lens group in the optical axis direction. In this optical system, the back focal length (BFL) is large. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] CN216956501U [Patent Document 2] US9557627B2 [Patent Document 3] US20210048628A1 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide an optical system that can be arranged in a thin imaging device, has a large aperture, and is capable of telephoto shooting, and an imaging device equipped with the optical system. [Means for solving the problem]

[0008] The optical system according to the present invention comprises: Arranged in order from the object side to the image side, a first optical element group including a lens group including at least one lens and having a positive refractive power, and a reflecting optical element having a reflecting surface capable of bending an optical axis; a second optical element group including at least three lenses and having negative refractive power; a third optical element group including at least one lens and having a positive refractive power; The focal length of the third optical element group is f G3 and the focal length of the entire optical system when focused at infinity is f, 3>f G3 / f>0.5 Meet the following.

[0009] In addition, in the optical system, Focusing may be performed by moving the third optical element group along the optical axis.

[0010] In addition, in the optical system, The number of lenses included in the third optical element group may be smaller than the number of lenses included in the second optical element group.

[0011] In addition, in the optical system, The lens group may be configured such that an entrance pupil is located within the reflective optical element.

[0012] In addition, in the optical system, the reflecting optical element is a prism, When the optical axis before being bent by the reflecting surface is a first optical axis, and the angle of the first optical axis with respect to the reflecting surface is α, 30°≦α≦60° may be satisfied.

[0013] In addition, in the optical system, The optical axis after being bent by the reflecting surface is a second optical axis, the maximum effective diameter of the first optical axis when focusing at infinity is D1, and the maximum effective diameter of the second optical axis is D2. 1 <D1 / D2<2 may be satisfied.

[0014] In addition, in the optical system, The at least one lens included in the lens group may have an Abbe number of 40 or greater.

[0015] In addition, in the optical system, When the focal length of the lens group is f1, 1.2>f1 / f>0.4 may be satisfied.

[0016] In addition, in the optical system, The second optical element group may include, arranged from the object side to the image side, a first lens having negative refractive power, a second lens having positive refractive power, and a third lens having negative refractive power.

[0017] In addition, in the optical system, any one of the lenses included in the second optical element group has a negative refractive power, The refractive index N of the lens is Refractive index N>1.5 may be satisfied.

[0018] In addition, in the optical system, Let S1 be the distance along the optical axis from the reflective optical element side surface of the lens closest to the reflective optical element in the lens group to the reflective optical element side surface of the lens closest to the reflective optical element in the second group, and let TTL be the distance along the optical axis from the object side surface of the lens closest to the object in the optical system to the image plane, 0.5 <S1 / TTL<0.1 may be satisfied.

[0019] In addition, in the optical system, The F value, which is the ratio of the focal length f to the entrance pupil diameter, is F NO When the lens is set as above, the range of the F-number when focusing at infinity is as follows: 1.6≦F NO <=8 may be also possible.

[0020] In addition, in the optical system, When the distance along the optical axis from the object side surface of the lens closest to the object side of the optical system to the image forming surface is TTL and the effective focal length of the optical system is EFL, 1 <TTL / EFL<1.5 may be satisfied.

[0021] In addition, in the optical system, When focusing at infinity, the distance along the optical axis from the image side surface of the lens closest to the image side of the optical system to the image forming surface is defined as BFL, and the distance along the optical axis from the object side surface of the lens closest to the object side of the optical system to the image forming surface is defined as TTL. BFL / TTL≦0.25 may be satisfied.

[0022] In addition, in the optical system, The optical system may have a real focal length of 12 mm or greater.

[0023] In addition, in the optical system, When the dimension of the optical system in the direction in which the first optical axis, which is the optical axis before being bent by the reflecting surface, extends is MH, 5mm≦MH≦13mm may be satisfied.

[0024] Moreover, the imaging device according to the present invention comprises: Any one of the optical systems described above; and an image sensor disposed at an image forming position of the optical system. [Brief description of the drawings]

[0025] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of an imaging device according to this embodiment. [Diagram 2] FIG. 2 is a schematic diagram showing the configuration of an optical system included in the imaging device. [Diagram 3] FIG. 3 is a lens configuration diagram of the optical system of the first embodiment. [Figure 4] FIG. 4 is a longitudinal aberration diagram of the optical system of the first embodiment when focused on an object at infinity. [Diagram 5] FIG. 5 is a longitudinal aberration diagram of the optical system of Example 1 when focused at 1000 mm. [Figure 6] FIG. 6 is a lateral aberration diagram of the optical system of Example 1 when focused on an object at infinity. [Figure 7] FIG. 7 is a lateral aberration diagram of the optical system of Example 1 when focused at 1000 mm. [Figure 8] FIG. 8 is a lens configuration diagram of the optical system according to the second embodiment. [Figure 9] FIG. 9 is a longitudinal aberration diagram of the optical system of the second embodiment when focused on an object at infinity. [Figure 10] FIG. 10 is a longitudinal aberration diagram of the optical system of Example 2 when focused at 1000 mm. [Figure 11] FIG. 11 is a lateral aberration diagram of the optical system of Example 2 when focused on an object at infinity. [Figure 12] FIG. 12 is a lateral aberration diagram of the optical system of Example 2 when focused at 1000 mm. [Figure 13] FIG. 13 is a lens configuration diagram of the optical system of the third embodiment. [Figure 14]FIG. 14 is a longitudinal aberration diagram of the optical system of Example 3 when focused on an object at infinity. [Figure 15] FIG. 15 is a longitudinal aberration diagram of the optical system of Example 3 when focused at 1000 mm. [Figure 16] FIG. 16 is a lateral aberration diagram of the optical system of Example 3 when focused on an object at infinity. [Figure 17] FIG. 17 is a lateral aberration diagram of the optical system of Example 3 when focused at 1000 mm. [Figure 18] FIG. 18 is a lens configuration diagram of the optical system of the fourth embodiment. [Figure 19] FIG. 19 is a longitudinal aberration diagram of the optical system of Example 4 when focused on an object at infinity. [Figure 20] FIG. 20 is a longitudinal aberration diagram of the optical system of Example 4 when focused at 1000 mm. [Figure 21] FIG. 21 is a lateral aberration diagram of the optical system of Example 4 when focused on an object at infinity. [Figure 22] FIG. 22 is a lateral aberration diagram of the optical system of Example 4 when focused at 1000 mm. [Figure 23] FIG. 23 is a lens configuration diagram of the optical system of the fifth embodiment. [Figure 24] FIG. 24 is a longitudinal aberration diagram of the optical system of Example 5 when focused on an object at infinity. [Diagram 25] FIG. 25 is a longitudinal aberration diagram of the optical system of Example 5 when focused at 1000 mm. [Figure 26] FIG. 26 is a lateral aberration diagram of the optical system of Example 5 when focused on an object at infinity. [Figure 27] FIG. 27 is a lateral aberration diagram of the optical system of Example 5 when focused at 1000 mm. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0027] The imaging device according to this embodiment is capable of capturing an image of an object, such as a digital camera, a smartphone, or a tablet device, and the imaging device described below is, for example, a smartphone.

[0028] 1, the imaging device 100 includes an optical system 1 arranged so that at least a portion of it is built into a smartphone body (imaging device body) 101, and an image sensor 5 arranged at an image forming position of the optical system 1. Specifically, the imaging device 100 includes the smartphone body 101, the optical system 1, the image sensor 5, and a display unit 102 such as a liquid crystal screen that displays imaging (image) data output from the image sensor 5.

[0029] The image sensor 5 disposed at the imaging position of the optical system 1 is an element that converts the optical image formed by the optical system 1 into an electrical signal (imaging data), and the image sensor 5 of this embodiment is a CMOS image sensor. The effective image height IH of the image sensor 5 is half the diagonal length of the image sensor 5, and the frame of the image sensor 5 is 3:4, 9:16, 3:2, etc.

[0030] The optical system 1 includes at least a first optical element group G1, a second optical element group G2, and a third optical element group G3, which are arranged in order from the object side to the image side along the optical axis C. Each of these optical element groups G1, G2, and G3 includes at least one optical element such as a lens. The optical system 1 of this embodiment includes, in order from the object side to the image side along the optical axis C, the first optical element group G1, the second optical element group G2, the third optical element group G3, and an optical filter (IR filter in this embodiment) 6. The optical system 1 also includes an aperture (aperture device) 7 arranged at a predetermined position on the optical axis C, and a protective glass 8 arranged on the object side of the first optical element group G1.

[0031] In this optical system 1, during focusing, the distances of the first optical element group G1 and the second optical element group G2 from the image sensor 5 (the imaging surface of the optical system 1) on the optical axis C are fixed, while the third lens group G3 moves along the optical axis C. That is, in the optical system 1 of this embodiment, of the optical element groups G1, G2, and G3, the third optical element group G3 constitutes a focus lens group.

[0032] The third optical element group G3 is moved during focusing by various mechanisms that have been known in the art. Vibration prevention (shake correction) in the optical system 1 may be performed by either a sensor shift method or a lens shift method (shifting the entire optical element group, or shifting the third optical element group).

[0033] In the following, the optical element groups G1 to G3 in the optical system 1 will be described in detail.

[0034] The first optical element group G1 includes a lens group 10 including at least one lens and having a positive refractive power, and a reflective optical element 15 having a reflecting surface 15a capable of bending the optical axis C. In the first optical element group G1 of this embodiment, the lens group 10 includes one lens 11, and the reflective optical element 15 is a prism made of glass. The second optical element group G2 includes at least three lenses and has a negative refractive power. The second optical element group G2 of this embodiment includes three lenses (a first lens 21, a second lens 22, and a third lens 23). In these three lenses 21, 22, and 23, the first lens 21 has a negative refractive power, the second lens 22 has a positive refractive power, and the third lens 23 has a negative refractive power. The third optical element group G3 includes at least one lens and has a positive refractive power. The third optical element group G3 of this embodiment includes one lens 31.

[0035] The optical system 1 of this embodiment includes a bending portion 10A that receives light rays (light from an object) and bends the optical axis C of the incident light rays, and a main body portion 10B that is built into a smartphone main body 101. The bending portion 10A is a portion where a first optical element group G1 is arranged, and the main body portion 10B is a portion where a second optical element group G2 and a third optical element group G3 are arranged. In this optical system 1, the optical axis in the bending portion 10A (i.e., the optical axis before being bent by the reflecting surface 15a) is also referred to as a first optical axis C1, and the optical axis in the main body portion 10B (i.e., the optical axis after being bent by the reflecting surface 15a) is also referred to as a second optical axis C2.

[0036] In the optical system 1 of this embodiment, the lens group 10 and the third optical element group G3 are names for convenience, and include those composed of only one optical element (lens, etc.). That is, each of the lens group 10 and the third optical element group G3 includes at least one optical element such as a lens. In addition, the optical system 1 is divided into optical elements (lenses, etc.) whose positions on the optical axis C are fixed during focusing and optical elements that move, and the fixed at least one optical element in the divided area is one lens group, and the moving at least one optical element in the divided area is another lens group.

[0037] Here, the focal length of the third optical element group G3 is f G3 and the focal length of the entire optical system 1 when focused at infinity is f, the optical system 1 may satisfy the following formula (1). 3>f G3 / f>0.5 ···(1)

[0038] In this way, by satisfying the above formula (1) in the optical system 1, an optical system that has a large aperture and is capable of telephoto shooting (a so-called large aperture telephoto lens) and has rear focusing is obtained. Telephoto shooting is possible with the optical system 1. In optical system 1, this ratio (f G3When the ratio (f / f) is 3 or more, the power of the third optical element group G3 becomes weak, and the focusing stroke becomes large. G3 When / f) is 0.5 or less, the power of the third optical element group G3 becomes too strong, the power balance of the entire optical system 1 (plurality of optical element groups G1, G2, G3) is not achieved, and the performance at wide angles of view is degraded.

[0039] From the viewpoint of the focusing stroke and the power configuration of each of the optical element groups G1, G2, and G3, it is more preferable that the optical system 1 satisfies the following formula (2). 2.5>f G3 / f>0.8 ···(2)

[0040] In addition, in this optical system 1, focusing may be performed by moving the third optical element group G3 along the optical axis C. In this manner, by configuring to move some (third optical element group) G3 of the multiple optical elements 21, 22, 23, 31 arranged in the main body portion (a portion closer to the image side than the prism 15) 1B of the optical system 1 in the second optical axis C2 direction (the optical axis direction after bending by the reflecting surface 15a) to perform focusing, the load on the mechanism that moves the optical element (lens in this embodiment) 31 in the second optical axis C2 direction (the up-down direction in FIG. 2) and vibration during driving can be suppressed, and the mechanism can be simplified and made smaller to suitably suppress the dimension of the main body portion 10B in the first optical axis C1 direction (the left-right direction in FIG. 2).

[0041] Furthermore, in this optical system 1, the number of lenses 31 included in the third optical element group g1 may be smaller than the number of lenses 21, 22, and 23 included in the second optical element group G2. This makes it possible to further reduce the load on the mechanism that drives the third optical element group G3 in the direction of the second optical axis C2 and vibrations during driving, and also to further simplify and miniaturize the mechanism, thereby making it possible to further reduce the dimension of the main body 10B in the direction of the first optical axis C1.

[0042] In addition, in this optical system 1, the lens group 10 of the first optical element group G1 may be configured so that the entrance pupil is located inside the prism 15. This allows the overall optical length of the optical system 1 to be further reduced.

[0043] In addition, in this optical system 1, the reflective optical element of the first optical element group G1 is a prism 15, and when the optical axis before being bent by the reflective surface 15a of the prism 15 is defined as a first optical axis C1 and the angle of the first optical axis C1 with respect to the reflective surface 15a is defined as α, the optical system 1 may satisfy the following formula (3). 30°≦α≦60° (3)

[0044] In this way, by satisfying the above formula (3) in the optical system 1, it is possible to reduce the dimension in the direction of the first optical axis C1 of the optical system 1. The angle α in the optical system 1 of this embodiment is 45°.

[0045] In addition, in this optical system 1, When the optical axis C after being bent by the reflecting surface 15a is defined as the second optical axis C2, the maximum effective diameter on the first optical axis C1 when focusing at infinity is defined as D1, and the maximum effective diameter on the second optical axis C2 is defined as D2, the optical system 1 may satisfy the following formula (4). 1 <D1 / D2<2 ···(4)

[0046] In this way, since the optical system 1 satisfies the above formula (4), the dimension of the main body 10B of the optical system 1 in the direction of the first optical axis C1 can be made sufficiently small, which makes it possible to place the optical system 1 (i.e., a large-aperture telephoto lens) in a thin imaging device 100 such as a smartphone with the main body 10B built-in.

[0047] More specifically, the maximum effective diameter D1 on the first optical axis C1 is the maximum effective diameter of a light ray passing through the lens 11, and the maximum effective diameter D2 on the second optical axis C2 is the maximum effective diameter of a light ray passing through the lens 21 closest to the object in the second optical element group G2. In the optical system 2 of this embodiment, the optimal value of D1 / D2 is around 1.6.

[0048] In the optical system 1, at least one lens 11 included in the lens group 10 of the first optical element group G1 may have an Abbe number of 40 or more.

[0049] In this way, in the lens group 10 (the optical element group on the object side of the prism 15) which has the power to most converge the light beam and which has a dominant effect on the spherical aberration and axial chromatic aberration in the optical system 1, at least one lens 11 is made of a low-dispersion material with an Abbe number of 40 or more, thereby making it possible to reduce chromatic aberration in the entire optical system 1.

[0050] In addition, in this optical system 1, when the focal length of the lens group 10 is f1, the optical system 1 may satisfy the following formula (5). 1.2>f1 / f>0.4 (5)

[0051] In the optical system 1, when the ratio (f1 / f) is 1.2 or more, the power of the lens group 10 becomes weak, and the total optical length of the optical system 1 becomes large. On the other hand, when the ratio (f1 / f) is 0.4 or less, the power of the lens group 10 becomes strong, and the total optical length of the optical system 1 becomes short, and it becomes impossible to secure a space for disposing the prism 15 between the lens group 10 and the second optical element group G2. In addition, spherical aberration also becomes large. In other words, according to the above configuration, it is possible to suppress the total optical length while securing the space for disposing the prism 15, and also suppress the spherical aberration.

[0052] It is more preferable that the ratio between the focal length f1 of the lens group 10 and the focal length f of the entire optical system 1 when focused at infinity satisfies the following formula (6). 1.1>f1 / f>0.5 (6)

[0053] In addition, in this optical system 1, the second optical element group G2 may include a first lens 21 having negative refractive power, a second lens 22 having positive refractive power, and a third lens 23 having negative refractive power, which are arranged from the object side to the image side. This allows the second optical element group G2 to correct various aberrations in the optical system 1, and as a result, it is possible to suitably reduce spherical aberration and off-axis aberration in the optical system 1. Note that, with the lenses 21, 22, and 23 arranged in order from the object side to the image side, another lens may be disposed between any of the lenses.

[0054] In the optical system 1, any one of the lenses 21 and 23 included in the second optical element group G2 may have negative refractive power, and the refractive index N of the lenses 21 and 23 may satisfy the following formula (7). Refractive index N>1.5 (7)

[0055] In the optical system 1, the Petzval sum can be reduced by satisfying the formula (7). The Petzval sum is expressed by the following formula (8). P = Σ(1 / Nf) (8)

[0056] In addition, in this optical system 1, When the distance along the optical axis from the reflecting optical element side surface of the lens closest to the reflecting optical element in the lens group to the reflecting optical element side surface of the lens closest to the reflecting optical element in the second group is S1, and the distance along the optical axis from the object side surface of the lens closest to the object in the optical system to the image forming surface is TTL, the optical system 1 may satisfy the following formula (9). Note that the above "TTL" is the total distance of TL1 and TL2 shown in FIG. 2, and the above "S1" is the total distance of tp1 and tp2 shown in FIG. 2. 0.5 <S1 / TTL<0.1 ···(9)

[0057] In this way, by satisfying the above formula (9) in the optical system 1, it is possible to secure a placement space for the reflective optical element 15 in the optical path of the optical system 1, and thereby, it becomes possible to configure the optical system 1 so that the optical axis C can be bent at a desired angle and the effective light rays are not cut off.

[0058] Also, in this optical system 1, When the F value, which is the ratio of the focal length f to the entrance pupil diameter, is denoted as F NO the range of the F value at infinity focus may satisfy the following formula (10). 1.6 ≦ F NO ≦ 8 ···(10) and it may be so.

[0059] In this way, by satisfying the above formula (10) in the optical system 1, it is possible to realize the maximum lens entrance pupil diameter within the constraints due to the outer dimensions of the optical system 1, and thereby, the image quality of the imaging device 100 equipped with the optical system 1 is improved.

[0060] Also, in this optical system 1, when the distance along the optical axis C from the object side surface of the lens 11 on the most object side of the optical system 1 to the imaging surface is denoted as TTL and the effective focal length of the optical system 1 is denoted as EFL, the optical system 1 may satisfy the following formula (11). 1 < TTL / EFL < 1.5 ··· Formula (11) and it may satisfy.

[0061] In this way, by satisfying the above formula (11) in the optical system 1, a balance is achieved between the optical performance and the outer dimensions of the optical system 1. That is, in the optical system 1, when this ratio (TTL / EFL) becomes 1.5 or more, the length of the optical system 1 (the length along the optical axis C) becomes too large, and when it becomes 1 or less, the performance of the optical system 1 deteriorates.

[0062] In addition, in this optical system 1, when the distance along the optical axis C from the image-side surface of the lens 11 closest to the image of the optical system 1 to the image plane when focusing at infinity is defined as BFL (see Figure 2), and the distance along the optical axis C from the object-side surface of the lens 11 closest to the object of the optical system 1 to the image plane is defined as TTL, the optical system 1 may satisfy the following equation (12). BFL / TTL≦0.25 (12) may be satisfied.

[0063] In this way, by satisfying the above formula (12) in optical system 1, the lens closest to the image side can be positioned closer to the image plane, thereby ensuring space to move the lens closest to the image side in the direction of the optical axis (second optical axis C2) as a focusing group.

[0064] Moreover, the optical system 1 is characterized in that the actual focal length of the optical system 1 is 12 mm or more.

[0065] In addition, in the optical system, when the dimension of the optical system 1 in the direction in which the first optical axis C1, which is the optical axis C before being bent by the reflecting surface 15a of the prism 15, extends is defined as MH (see Figure 2), the optical system 1 may satisfy the following formula (13). 5mm≦MH≦13mm (13)

[0066] In this way, by satisfying the above formula (13) in the optical system 1, it is possible to obtain an optical system 1 having a sufficiently small dimension in the direction of the first optical axis C1. This also makes it possible to reduce the thickness (size in the direction of the first optical axis C1) of the smartphone (imaging device) 100 including the optical system 1.

[0067] According to the optical system 1 described above, the dimension in the first optical axis C1 direction can be suppressed by bending the optical axis C by the prism 15. Moreover, according to this optical system 1, a large-diameter (i.e., small F-number) and telephoto lens can be obtained. The optical system 1 of this embodiment has an aperture (F-number of about 2) larger than the thickness (dimension in the first optical axis C1 direction) of the smartphone body 101, and is capable of telephoto shooting equivalent to 125 mm, for example. Furthermore, by providing the optical system 1 with a large aperture (i.e., small F-number), the dynamic range of the smartphone (imaging device) 100 is improved. Moreover, by configuring the optical system 2 to move a part (third optical element group) G3 of the multiple optical element groups G1, G2, and G3 provided therein along the optical axis for focusing, aberration fluctuation can be suppressed.

[0068] Furthermore, by arranging the optical system 1 so that the main body 10B is built in, the smartphone (imaging device) 100 can be made thinner (the dimension in the direction of the first optical axis C1 can be reduced).

[0069] The optical system 1 and the imaging device 100 including the optical system 1 of the present invention are not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, the configuration of one embodiment can be added to the configuration of another embodiment, and part of the configuration of one embodiment can be replaced with the configuration of another embodiment. Furthermore, part of the configuration of one embodiment can be deleted.

[0070] In the optical system 1 of this embodiment, the lens group 10 of the first optical element group G1 includes one lens 11, but is not limited to this configuration. The lens group 10 may include two or more lenses. This configuration makes it easier to suppress various aberrations. In addition, the bent portion 10A where the first optical element group G1 is arranged is a portion that protrudes from the smartphone body 101, and the dimension of the main body portion 10B built into the smartphone body 101 in the first optical axis C1 direction does not change, so there is no need to increase the thickness dimension (dimension in the first optical axis C1 direction) of the smartphone body 101.

[0071] Next, Examples 1 to 5 of the imaging device of the present invention will be described. In each of the following Examples, the same reference numerals are used for configurations corresponding to those of the optical system of the above embodiment. In the tables of each of the following Examples, r is the radius of curvature, d is the lens thickness or lens spacing, nd is the refractive index of the d-line, and vd is the Abbe number based on the d-line. In addition, the aspheric surface is defined, for example, by the following number 1.

number

[0072] Moreover, each longitudinal aberration diagram shows, from the left, spherical aberration (mm), astigmatism (mm), and distortion (DIS (%)). In the spherical aberration diagrams, the solid line represents the d-line characteristics, the short dashed line represents the F-line characteristics, and the long dashed line represents the C-line characteristics. In the astigmatism diagrams, the vertical axis represents the maximum image height, the solid line represents the sagittal plane characteristics (indicated by X in the diagrams), and the dashed line represents the meridional plane characteristics (indicated by Y in the diagrams). In the distortion diagrams, the vertical axis represents the maximum image height.

[0073] Next, Examples 1 to 5 of the present invention will be described. First, various data for each Example will be shown in Table 1, and then each Example will be specifically described. [Table 1]

[0074] [Example 1] Fig. 3 is a lens configuration diagram of the optical system 1A of this Example 1, Fig. 4 is a longitudinal aberration diagram when focused at infinity, Fig. 5 is a longitudinal aberration diagram when focused at 1000 mm, Fig. 6 is a lateral aberration diagram when focused at infinity, and Fig. 7 is a lateral aberration diagram when focused at 1000 mm. In addition, the following Table 2 shows the surface data of each lens, Table 3 shows the aspheric surface data, Table 4 shows the decentering data of the reflecting surface, and Table 5 shows the position data when focused.

[0075] The optical system 1A of the first embodiment includes, in order from the object side to the image side, a lens 11A having a positive refractive power, a prism 15, an aperture 7, a lens 21A having a negative refractive power, a lens 22A having a positive refractive power, a lens 23A having a positive refractive power, a lens 24A having a negative refractive power, and a lens 31A having a positive refractive power. In this optical system 1A, the second optical element group G2 has a negative refractive power and includes lenses 21A, 22A, 23A, and 24A. The refractive powers of the lenses 21A, 22A, 23A, and 24A in the second optical element group G2 are arranged as negative, positive, positive, and negative. The third optical element group G3 includes a lens 31A and focuses by moving along the second optical axis C2.

[0076] [Table 2] [Table 3] [Table 4] [Table 5] [Table 6]

[0077] [Example 2] Fig. 8 is a lens configuration diagram of optical system 1B of this Example 2, Fig. 9 is a longitudinal aberration diagram when focused at infinity, Fig. 10 is a longitudinal aberration diagram when focused at 1000 mm, Fig. 11 is a lateral aberration diagram when focused at infinity, and Fig. 12 is a lateral aberration diagram when focused at 1000 mm. In addition, Table 7 below shows various data, Table 8 shows surface data of each lens, Table 9 shows aspheric data, Table 10 shows decentering data of reflecting surfaces, and Table 11 shows position data when focused.

[0078] The optical system 1B of the second embodiment includes, in order from the object side to the image side, a lens 11B having a positive refractive power, a prism 15, an aperture 7, a lens 21B having a negative refractive power, a lens 22B having a positive refractive power, a lens 23B having a negative refractive power, a lens 24B having a negative refractive power, and a lens 31B having a positive refractive power. In this optical system 1B, the second optical element group G2 has a negative refractive power and includes lenses 21B, 22B, 23B, and 24B. The refractive powers of the lenses 21B, 22B, 23B, and 24B in the second optical element group G2 are arranged as negative, positive, negative, and negative. The third optical element group G3 includes a lens 31B and focuses by moving along the second optical axis C2.

[0079] [Table 7] [Table 8] [Table 9] [Table 10] [Table 11]

[0080] [Example 3] Fig. 13 is a lens configuration diagram of optical system 1C of this Example 3, Fig. 14 is a longitudinal aberration diagram when focused at infinity, Fig. 15 is a longitudinal aberration diagram when focused at 1000 mm, Fig. 16 is a lateral aberration diagram when focused at infinity, and Fig. 17 is a lateral aberration diagram when focused at 1000 mm. In addition, Table 12 below shows various data, Table 13 shows surface data of each lens, Table 14 shows aspheric data, Table 15 shows decentering data of reflecting surfaces, and Table 16 shows position data when focused.

[0081] The optical system 1C of the third embodiment includes a prism 15A (an optical element in which a lens 11C having a positive refractive power and a prism 15 are integrated) having a convex surface on the object side, a lens 21C having a negative refractive power, an aperture 7, a lens 22C having a positive refractive power, a lens 23C having a negative refractive power, a lens 24C having a positive refractive power, and a lens 31C having a positive refractive power, which are arranged in order from the object side to the image side. In this optical system 1C, the second optical element group G2 has a negative refractive power and includes lenses 21C, 22C, 23C, and 24C. The refractive powers of the lenses 21C, 22C, 23C, and 24C in the second optical element group G2 are arranged as negative, positive, negative, and positive. The third optical element group G3 includes a lens 31C and focuses by moving along the second optical axis C2.

[0082] [Table 12] [Table 13] [Table 14] [Table 15] [Table 16]

[0083] [Example 4] Fig. 18 is a lens configuration diagram of optical system 1D of this Example 4, Fig. 19 is a longitudinal aberration diagram when focused at infinity, Fig. 20 is a longitudinal aberration diagram when focused at 1000 mm, Fig. 21 is a lateral aberration diagram when focused at infinity, and Fig. 22 is a lateral aberration diagram when focused at 1000 mm. In addition, Table 17 below shows various data, Table 18 shows surface data of each lens, Table 19 shows aspheric data, Table 20 shows decentering data of reflecting surfaces, and Table 21 shows position data when focused.

[0084] The optical system 1D of the fourth embodiment includes, in order from the object side to the image side, a lens 11D having a positive refractive power, a prism 15, an aperture 7, a lens 21D having a negative refractive power, a lens 22D having a positive refractive power, a lens 23D having a negative refractive power, a lens 24D having a positive refractive power, and a lens 31D having a positive refractive power. In this optical system 1D, the second optical element group G2 has a negative refractive power and includes lenses 21D, 22D, 23D, and 24D. The refractive powers of the lenses 21D, 22D, 23D, and 24D in the second optical element group G2 are arranged as negative, positive, negative, and positive. The third optical element group G3 includes a lens 31D and focuses by moving along the second optical axis C2.

[0085] [Table 17] [Table 18] [Table 19] [Table 20] [Table 21]

[0086] [Example 5] Fig. 23 is a lens configuration diagram of optical system 1E of this Example 5, Fig. 24 is a longitudinal aberration diagram when focused at infinity, Fig. 25 is a longitudinal aberration diagram when focused at 1000 mm, Fig. 26 is a lateral aberration diagram when focused at infinity, and Fig. 27 is a lateral aberration diagram when focused at 1000 mm. In addition, Table 22 below shows various data, Table 23 shows surface data of each lens, Table 24 shows aspheric data, Table 25 shows decentering data of reflecting surfaces, and Table 26 shows position data when focused.

[0087] The optical system 1E of the fifth embodiment includes, in order from the object side to the image side, a lens 11E having a positive refractive power, a prism 15, an aperture 7, a lens 21E having a negative refractive power, a lens 22E having a positive refractive power, a lens 23E having a negative refractive power, a lens 24E having a negative refractive power, and a lens 31E having a positive refractive power. In this optical system 1E, the second optical element group G2 has a negative refractive power and includes lenses 21E, 22E, 23E, and 24E. The refractive powers of the lenses 21E, 22E, 23E, and 24E in the second optical element group G2 are arranged as negative, positive, negative, and negative. The third optical element group G3 includes a lens 31E and focuses by moving along the second optical axis C2.

[0088] [Table 22] [Table 23] [Table 24] [Table 25] [Table 26]

[0089] In order to express the present invention, the present invention has been described adequately and sufficiently through the embodiments with reference to the drawings in the above description, but it should be recognized that those skilled in the art can easily change and / or improve the above-mentioned embodiments. Therefore, unless the changes or improvements made by those skilled in the art are at a level that departs from the scope of the claims described in the claims, the changes or improvements are interpreted as being included in the scope of the claims. [Explanation of symbols]

[0090] 1, 1A, 1B, 1C, 1D, 1E...optical system, 10A...bending portion, 10B...main body, 5...image sensor, 6...optical filter, 7...aperture stop, 8...protective glass, 10...lens group, 11, 11A, 11B, 11C, 11D, 11E...lens, 15...prism (reflective optical element), 15a...reflective surface, 21, 21A, 21B, 21C, 21D, 21E...first lens (optical element), 22, 22A, 22B, 2 2C, 22D, 22E...second lens (optical element), 23, 23A, 23B, 23C, 23D, 23E...third lens (optical element), 24A, 24D, 24E...fourth lens (optical element), 31...lens (optical element), 100...imaging device, 101...smartphone body, 102...display unit, C...optical axis, C1...first optical axis, C2...second optical axis, G1...first optical element group, G2...second optical element group, G3...third optical element group

Claims

1. Arranged in order from the object side to the image side, a first optical element group having a positive refractive power and capable of bending an optical axis; a second optical element group including at least three lenses and having negative refractive power; a third optical element group including at least one lens and having a positive refractive power; The focal length of the third optical element group is f Ｇ３ and the focal length of the entire optical system when focused at infinity is f, 3>f Ｇ３ / f>0.5 Meet the optical system.

2. The optical system according to claim 1 , wherein the third optical element group performs focusing by moving along the optical axis.

3. The optical system according to claim 2 , wherein the number of lenses included in the third optical group is smaller than the number of lenses included in the second optical group.

4. The optical system according to any one of claims 1 to 3, wherein the lens group is configured such that an entrance pupil is located within the reflecting optical element.

5. the reflecting optical element is a prism, When the optical axis before being bent by the reflecting surface is a first optical axis, and the angle of the first optical axis with respect to the reflecting surface is α, ３０°≦α≦６０° The optical system according to any one of claims 1 to 4, which satisfies the following:

6. When the optical axis after being bent by the reflecting surface is a second optical axis, the maximum effective diameter of the first optical axis when focusing on infinity is D1, and the maximum effective diameter of the second optical axis is D2, 1<D1 / D2<2 The optical system according to any one of claims 1 to 5, which satisfies the following:

7. 7. The optical system according to claim 1, wherein the at least one lens included in the lens group has an Abbe number of 40 or more.

8. When the focal length of the lens group is f1, 1.2>f1 / f>0.4 The optical system according to any one of claims 1 to 7, which satisfies the following:

9. 9. The optical system according to claim 1, wherein the second optical element group includes, arranged from the object side to the image side, a first lens having negative refractive power, a second lens having positive refractive power, and a third lens having negative refractive power.

10. any one of the lenses included in the second optical element group has a negative refractive power, The refractive index N of the lens is Refractive index N>1.5 The optical system according to any one of claims 1 to 9, which satisfies the following:

11. S1 is a distance along the optical axis from a surface of the lens closest to the reflecting optical element in the lens group closest to the reflecting optical element to a surface of the lens closest to the reflecting optical element in the second group closest to the reflecting optical element, and TTL is a distance along the optical axis from the object-side surface of the lens closest to the object in the optical system to an image plane, 0.5<S1 / TTL<0.1 The optical system according to any one of claims 1 to 10, which satisfies the following:

12. The F value, which is the ratio of the focal length f to the entrance pupil diameter, is F ＮＯ When the lens is focused at infinity, the range of the F-number is as follows: 1.6≦F ＮＯ ≦8 The optical system according to any one of claims 1 to 11, wherein

13. When the distance along the optical axis from the object side surface of the lens closest to the object side of the optical system to the image forming surface is TTL and the effective focal length of the optical system is EFL, 1<TTL / EFL<1.5 The optical system according to any one of claims 1 to 12, which satisfies the following:

14. When focusing at infinity, the distance along the optical axis from the image side surface of the lens closest to the image side of the optical system to the image forming surface is defined as BFL, and the distance along the optical axis from the object side surface of the lens closest to the object side of the optical system to the image forming surface is defined as TTL. BFL / TTL≦0.25 The optical system according to any one of claims 1 to 13, wherein

15. The optical system according to any one of claims 1 to 14, wherein the real focal length of the optical system is 12 mm or more.

16. When the dimension of the optical system in the direction in which the first optical axis, which is the optical axis before being bent by the reflecting surface, extends is defined as M, 5mm≦MH≦13mm The optical system according to any one of claims 1 to 15,

17. The first optical element group includes a lens group including at least one lens and having a positive refractive power, and a reflective optical element having a reflective surface that can bend an optical axis, or The optical system according to any one of claims 1 to 16, wherein the first optical element group includes an integrated optical element made up of a lens portion having a positive refractive power and a prism portion capable of bending an optical axis.

18. An optical system according to any one of claims 1 to 17; an image sensor disposed at an image forming position of the optical system.

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