Imaging optical system

Abstract

An imaging optical system is provided that can reduce the size of a first lens while suppressing deterioration in optical characteristics. [Solution] An imaging optical system 100 comprises, in order from the object side to the image side, a front group 110, an aperture 130, and a rear group 120. The front group 110 is made up of multiple lenses, including a first lens 10 arranged closest to the object side. The rear group 120 is made up of multiple lenses. The first lens 10 has negative power. If the total length of the entire lens system is d0, the effective radius of the object-side lens surface 11 of the first lens 10 is sd11, and the maximum image height is IH, then the following conditional expression is satisfied: 3,000 <d0 / sd11<4.500:(1) 2,500 <d0 / IH<5.000:(2) Meet the following.

Description

[Technical Field]

[0001] The present invention relates to an imaging optical system.

[0002] An imaging optical system used in vehicle-mounted cameras and surveillance cameras is described in Patent Document 1. The imaging optical system in Patent Document 1 is composed of an aperture stop, a first lens group arranged closer to the object than the aperture stop, and a second lens group arranged closer to the image than the aperture stop. The first lens group and the second lens group each consist of a plurality of lenses. The first lens group includes a first lens arranged closest to the object, and the first lens is exposed from a lens barrel or the like that covers the imaging optical system. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-112893 Summary of the Invention [Problem to be solved by the invention]

[0004] In imaging optical systems used in vehicle-mounted cameras and surveillance cameras, miniaturization of the first lens is required from the viewpoint of design and from the viewpoint of reducing the user's sense of being monitored. However, in the imaging optical system of Patent Document 1, it is difficult to miniaturize the first lens while preventing deterioration of optical characteristics.

[0005] In view of the above problems, an object of the present invention is to provide an imaging optical system that can reduce the size of the first lens while suppressing degradation of optical characteristics. [Means for solving the problem]

[0006] In order to achieve the above object, an imaging optical system of the present invention comprises, in order from the object side to the image side, a front group, a stop, and a rear group, the front group is made up of a plurality of lenses including a first lens arranged closest to the object, the rear group is made up of a plurality of lenses, the first lens has negative power; When the total length of the entire lens system is d0, the effective radius of the lens surface on the object side of the first lens is sd11, and the maximum image height is IH, the following conditional expression is satisfied: 3.000< d0 / sd11 <4.500 (1) 2.500< d0 / IH <5.000 (2) The present invention is characterized in that: [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is an explanatory diagram of an imaging optical system according to the first embodiment. [Figure 2] FIG. 2 is a diagram showing data of the imaging optical system of the first embodiment. [Figure 3] FIG. 3 is a diagram showing spherical aberration of the imaging optical system shown in FIG. [Figure 4] FIG. 4 is a diagram showing chromatic aberration of magnification of the imaging optical system shown in FIG. [Figure 5] FIG. 5 is a diagram showing astigmatism and distortion of the imaging optical system shown in FIG. [Figure 6] FIG. 6 is a diagram showing the lateral aberration of the imaging optical system shown in FIG. [Figure 7] FIG. 7 is an explanatory diagram of an imaging optical system according to the second embodiment. [Figure 8] FIG. 8 is a diagram showing data of the imaging optical system of the second embodiment. [Figure 9] FIG. 9 is a diagram showing spherical aberration of the imaging optical system shown in FIG. [Figure 10] FIG. 10 is a diagram showing chromatic aberration of magnification of the imaging optical system shown in FIG. [Figure 11] FIG. 11 is a diagram showing astigmatism and distortion of the imaging optical system shown in FIG. [Figure 12] FIG. 12 is a diagram showing the lateral aberration of the imaging optical system shown in FIG. [Figure 13] FIG. 13 is an explanatory diagram of an imaging optical system according to the third embodiment. [Figure 14] FIG. 14 is a diagram showing data of the imaging optical system of the third embodiment. [Figure 15] FIG. 15 is a diagram showing spherical aberration of the imaging optical system shown in FIG. [Figure 16] FIG. 16 is a diagram showing chromatic aberration of magnification of the imaging optical system shown in FIG. [Figure 17] FIG. 17 is a diagram showing astigmatism and distortion of the imaging optical system shown in FIG. [Figure 18] FIG. 18 is a diagram showing the lateral aberration of the imaging optical system shown in FIG. [Figure 19] FIG. 19 is an explanatory diagram of an imaging optical system according to the fourth embodiment. [Figure 20] FIG. 20 is a diagram showing data of the imaging optical system of the fourth embodiment. [Figure 21] FIG. 21 is a diagram showing spherical aberration of the imaging optical system shown in FIG. [Figure 22] FIG. 22 is a diagram showing chromatic aberration of magnification of the imaging optical system shown in FIG. [Figure 23] FIG. 23 is a diagram showing astigmatism and distortion of the imaging optical system shown in FIG. [Figure 24] FIG. 24 is a diagram showing the lateral aberration of the imaging optical system shown in FIG. [Figure 25] FIG. 25 is an explanatory diagram of an imaging optical system according to the fifth embodiment. [Figure 26] FIG. 26 is a diagram showing data of the imaging optical system of the fifth embodiment. [Figure 27] FIG. 27 is a diagram showing spherical aberration of the imaging optical system shown in FIG. [Figure 28] FIG. 28 is a diagram showing chromatic aberration of magnification of the imaging optical system shown in FIG. [Figure 29] FIG. 29 is a diagram showing astigmatism and distortion of the imaging optical system shown in FIG. [Figure 30]FIG. 30 is a diagram showing the lateral aberration of the imaging optical system shown in FIG. [Figure 31] FIG. 31 is an explanatory diagram of an imaging optical system according to the sixth embodiment. [Figure 32] FIG. 32 is a diagram showing data of the imaging optical system of the sixth embodiment. [Figure 33] FIG. 33 is a diagram showing spherical aberration of the imaging optical system shown in FIG. [Figure 34] FIG. 34 is a diagram showing chromatic aberration of magnification of the imaging optical system shown in FIG. [Figure 35] FIG. 35 is a diagram showing astigmatism and distortion of the imaging optical system shown in FIG. [Figure 36] FIG. 36 is a diagram showing the lateral aberration of the imaging optical system shown in FIG. [Figure 37] FIG. 37 is an explanatory diagram of an imaging optical system according to the seventh embodiment. [Figure 38] FIG. 38 is a diagram showing data of the imaging optical system of the seventh embodiment. [Figure 39] FIG. 39 is a diagram showing spherical aberration of the imaging optical system shown in FIG. [Figure 40] FIG. 40 is a diagram showing chromatic aberration of magnification of the imaging optical system shown in FIG. [Figure 41] FIG. 41 is a diagram showing astigmatism and distortion of the imaging optical system shown in FIG. [Figure 42] FIG. 42 is a diagram showing the lateral aberration of the imaging optical system shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] An embodiment of an imaging optical system 100 to which the present invention is applied will be described below. The imaging optical system 100 is used in an in-vehicle camera or a surveillance camera. In particular, the imaging optical system 100 is suitable for use in a surveillance camera for monitoring the interior of a vehicle.

[0009] (Embodiment 1) Fig. 1 is an explanatory diagram of an imaging optical system 100 according to embodiment 1. As shown in Fig. 1, the imaging optical system 100 of this embodiment includes, in order from the object side La to the image side Lb, a front group 110, a diaphragm 130, a rear group 120, and an infrared cut filter 80.

[0010] The front group 110 is composed of, in order from the object side La to the image side Lb, a first lens 10 and a second lens 20. The rear group 120 is composed of, in order from the object side La to the image side Lb, a third lens 30, a fourth lens 40, a fifth lens 50, a sixth lens 60, and a seventh lens 70. On the image side Lb of the seventh lens 70, in order from the object side La to the image side Lb, are arranged a flat infrared cut filter 80, a light-transmitting cover 90, and an image sensor 140. The image sensor 140 is arranged on the image plane of the image side Lb of the imaging optical system 100.

[0011] The first lens 10 is made of resin. The first lens 10 has negative power. The first lens 10 has a convex lens surface 11 on the object side La and a concave lens surface 12 on the image side Lb. The first lens 10 has an aspheric lens surface 12.

[0012] The second lens 20 is made of resin. The second lens 20 has negative power. The second lens 20 has a concave lens surface 21 on the object side La and a convex lens surface 22 on the image side Lb. The second lens 20 has aspherical surfaces on both sides.

[0013] The third lens 30 is made of glass and has positive power. The third lens 30 has a convex lens surface 31 on the object side La and a convex lens surface 32 on the image side Lb.

[0014] The fourth lens 40 is made of resin. The fourth lens 40 has negative power. The fourth lens 40 has a concave lens surface 41 on the object side La and a concave lens surface 42 on the image side Lb. The fourth lens 40 has aspherical surfaces on both sides.

[0015] The fifth lens 50 is made of resin. The fifth lens 50 has positive power. The fifth lens 50 has a convex lens surface 51 on the object side La and a convex lens surface 52 on the image side Lb. The fifth lens 50 has aspherical surfaces on both sides.

[0016] The sixth lens 60 is made of resin. The sixth lens 60 has negative power. The sixth lens 60 has a lens surface 61 on the object side La that is concave, and a lens surface 62 on the image side Lb that is concave. The sixth lens 60 has aspherical surfaces on both sides.

[0017] The seventh lens 70 is made of resin. The seventh lens 70 has positive power. The seventh lens 70 has a convex lens surface 71 on the object side La and a concave lens surface 72 on the image side Lb. The seventh lens 70 has aspherical surfaces on both sides.

[0018] Fig. 2 is a diagram showing data of the imaging optical system 100 of Embodiment 1. Note that the values ​​shown in Fig. 2 have been rounded off to the nearest whole number.

[0019] 2 shows the following various data. Here, in the various data, the total length of the entire lens system is the distance on the optical axis L from the lens surface 11 on the object side La of the first lens 10 to the imaging surface of the image sensor 140. The total length between the first lens and the seventh lens is the distance on the optical axis L from the lens surface 11 on the object side La of the first lens 10 to the lens surface 72 on the image side Lb of the seventh lens.

[0020] Focal length of the entire lens system f0 (Effective Focal Length) Total length of the entire lens system d0 (Total Track) F-number (Fno) of the entire lens system Max. Field Angle Pupil Diameter Total length between 1st lens and 7th lens (L1R1-L7R2 Track)

[0021] Figure 2 also shows the lens data for each of the following lenses. In the lens data, surfaces with an * next to the surface number are aspherical. R is the radius of curvature. d is the surface spacing. N is the refractive index. v is the Abbe number. f is the focal length. sd is the effective radius. The units for the radius of curvature, surface spacing, and focal length are mm. Figure 2 also shows the aspherical coefficients that indicate the shape of the aspherical surface for each surface number.

[0022] The imaging optical system 100 satisfies the following conditional expression, where d0 is the total length of the entire lens system, sd11 is the effective radius of the lens surface 11 on the object side of the first lens 10, and IH is the maximum image height. 3.000< d0 / sd11 <4.500 (1) 2.500< d0 / IH <5.000 (2) Meet the following.

[0023] In this embodiment, d0=13.920 sd11=4.036 IH=3.650 Therefore, d0 / sd11=3.449, which satisfies conditional expression (1). d0 / IH=3.814, which satisfies conditional expression (2).

[0024] In the imaging optical system 100, when the effective radius of the lens surface 11 on the object side of the first lens 10 is sd11 and the maximum image height is IH, the following conditional expression is satisfied: 0.650< sd11 / IH <1.300 (3) Meet the following.

[0025] In this embodiment, sd11=4.036 IH=3.650 Therefore, sd11 / IH=1.106, which satisfies conditional expression (3).

[0026] In the imaging optical system 100, when the radius of curvature of the lens surface 11 on the object side of the first lens 10 is R11 and the radius of curvature of the lens surface 12 on the image side of the first lens 10 is R12, the following conditional expression is satisfied: 1.100< (R11+R12) / (R11-R12) <2.000 (4) Meet the following.

[0027] In this embodiment, R11=11.747 R12=1.962 Therefore, (R11+R12) / (R11-R12)=1.401, which satisfies the conditional expression (4).

[0028] In the imaging optical system 100, when the focal length of the entire lens system is f0 and the radius of curvature of the lens surface 11 on the object side of the first lens 10 is R11, the following conditional expression is satisfied: 2.000< R11 / f0 <9.000 (5) Meet the following.

[0029] In this embodiment, f0=2.856 R11=11.747 Therefore, R11 / f0=4.113, which satisfies the conditional expression (5).

[0030] In the imaging optical system 100, when the focal length of the entire lens system is f0 and the radius of curvature of the image-side lens surface 12 of the first lens 10 is R12, the following conditional expression is satisfied: 0.500< R12 / f0 <3.000 (6) Meet the following.

[0031] In this embodiment, f0=2.856 R12=1.962 Therefore, R12 / f0=0.687, which satisfies conditional expression (6).

[0032] In the imaging optical system 100, when the focal length of the entire lens system is f0, the radius of curvature of the lens surface 21 on the object side of the second lens 20 is R21, and the radius of curvature of the lens surface 22 on the image side of the second lens 20 is R22, the following conditional expression is satisfied: -6.000< R21 / f0 <-1.500 (7) -6.000< R22 / f0 <-1.500 (8) Meet the following.

[0033] In this embodiment, f0=2.856 R21=-3.691 R22=-3.733 Therefore, R21 / f0=-1.292, which satisfies conditional expression (7). R22 / f0=-1.307, which satisfies conditional expression (8).

[0034] In the imaging optical system 100, when the Abbe number of the fifth lens 50 is ν5 and the Abbe number of the sixth lens 60 is ν6, the following conditional expression is satisfied: 50.000< ν5 (9) ν6 <30,000 (10) Meet the following.

[0035] In this embodiment, ν5=56.61 ν6=21.39 Therefore, the conditional expressions (9) and (10) are satisfied.

[0036] In the imaging optical system 100, when the total length of the entire lens system is d0 and the focal length of the entire lens system is f0, the following conditional expression is satisfied: 3.500< d0 / f0 <7.500 (11) Meet the following.

[0037] In this embodiment, d0=13.920 f0=2.856 Therefore, d0 / f0=4.874, which satisfies conditional expression (11).

[0038] When the maximum angle of view of the imaging optical system 100 is ω, the following conditional expression is satisfied: 120< ω <180 (12) Meet the following.

[0039] In this embodiment, ω=160 Therefore, conditional expression (12) is satisfied.

[0040] (Action and effect) In this configuration, the imaging optical system 100 satisfies condition (1), so the overall length of the first lens 10 and the entire lens system is reduced. If the value of condition (1) falls below the lower limit, the first lens 10 becomes larger relative to the overall length of the lens system, resulting in a larger imaging optical system 100. If the value of condition (1) exceeds the upper limit, the first lens 10 becomes too small relative to the overall length of the lens system, so peripheral light cannot be secured, and the imaging optical system 100 becomes dark.

[0041] The imaging optical system 100 in this configuration satisfies condition (2), so various aberrations can be corrected well, and the overall length of the lens system can be reduced. If the value of condition (2) falls below the lower limit, the angle of the light rays incident on the image sensor 140 becomes large, and various aberrations cannot be corrected well. If the value of condition (2) exceeds the upper limit, various aberrations can be corrected well, but the overall length of the lens becomes larger.

[0042] In this embodiment, the imaging optical system 100 satisfies condition (3), so the brightness of the imaging optical system 100 is maintained while the first lens 10 is miniaturized. If the value of condition (3) falls below the lower limit, the first lens 10 is miniaturized, but it becomes too small, so peripheral light cannot be secured, and the imaging optical system 100 becomes dark. If the value of condition (3) exceeds the upper limit, the imaging optical system 100 becomes brighter because the first lens 10 becomes larger, but the first lens 10 becomes larger.

[0043] The imaging optical system 100 of this embodiment satisfies conditional expression (4), making it easy to form the first lens 10 while ensuring the negative power of the first lens 10. If the value of conditional expression (4) is below the lower limit, the radius of curvature of the image-side lens surface 12 of the first lens 10 becomes too small relative to the radius of curvature of the object-side lens surface 11 of the first lens 10, making it difficult to form the first lens 10. If the value of conditional expression (4) exceeds the upper limit, it is easy to form the first lens 10, but it is difficult to ensure sufficient negative power of the first lens 10.

[0044] The imaging optical system 100 of this embodiment satisfies conditional expression (5), thereby ensuring the negative power of the first lens 10 and properly correcting various aberrations. If the value of conditional expression (5) is below the lower limit, the negative power of the first lens 10 can be ensured, but the radius of curvature of the object-side lens surface 11 of the first lens 10 becomes too small relative to the negative power of the first lens 10, making it difficult to properly correct various aberrations. Furthermore, the radius of curvature of the object-side lens surface 11 of the first lens 10 becomes too small, making it difficult to form the first lens 10. If the value of conditional expression (5) exceeds the upper limit, the radius of curvature of the object-side lens surface 11 of the first lens 10 becomes too large relative to the negative power of the first lens 10, making it possible to properly correct various aberrations, but making it difficult to sufficiently ensure the negative power of the first lens 10. As a result, the overall length of the entire lens system tends to increase.

[0045] The imaging optical system 100 of this embodiment satisfies conditional expression (6), and therefore can ensure the negative power of the first lens 10 while properly correcting various aberrations. If the value of conditional expression (6) is below the lower limit, the negative power of the first lens 10 can be ensured, but the radius of curvature of the image-side lens surface 12 of the first lens 10 becomes too small relative to the negative power of the first lens 10, making it impossible to properly correct various aberrations. In addition, the radius of curvature of the image-side lens surface 12 of the first lens 10 becomes too small, making it difficult to form the first lens 10. When the value of condition (6) exceeds the upper limit, the radius of curvature of the image-side lens surface 12 of the first lens 10 increases relative to the negative power of the first lens 10. This allows for proper correction of various aberrations, but makes it difficult to secure sufficient negative power for the first lens 10. As a result, the overall length of the lens system tends to increase.

[0046] The imaging optical system 100 in this embodiment satisfies conditions (7) and (8), so that the negative power of the second lens 20 can be secured while properly correcting aberrations. If the value of condition (7) falls below the lower limit, the negative power of the second lens 20 can be secured, but the radius of curvature of the object-side lens surface 21 of the second lens 20 becomes too small relative to the negative power of the second lens 20, making it impossible to properly correct aberrations. If the value of condition (8) falls below the lower limit, the negative power of the second lens 20 can be secured, but the radius of curvature of the image-side lens surface 22 of the second lens 20 becomes too small relative to the negative power of the second lens 20, making it impossible to properly correct aberrations. Furthermore, since the radii of curvature on both sides of the second lens 20 become too small, it becomes difficult to form the second lens 20. If the value of condition (7) exceeds the upper limit, the radius of curvature of the object-side lens surface 21 of the second lens 20 increases relative to the negative power of the second lens 20. This allows for proper correction of various aberrations, but makes it difficult to ensure sufficient negative power for the second lens 20. As a result, the overall length of the lens system tends to increase. If the value of condition (8) exceeds the upper limit, the radius of curvature of the image-side lens surface 22 of the second lens 20 increases relative to the negative power of the second lens 20. This allows for proper correction of various aberrations, but makes it difficult to ensure sufficient negative power for the second lens 20. As a result, the overall length of the lens system tends to increase.

[0047] Since the imaging optical system 100 in this configuration satisfies the conditions (9) and (10), chromatic aberration can be properly corrected.

[0048] The imaging optical system 100 of this embodiment satisfies conditional expression (11), and therefore can prevent the overall length of the lens system from increasing and can also prevent the occurrence of various aberrations. If the value of conditional expression (11) is below the lower limit, it is difficult to prevent the occurrence of various aberrations. If the value of conditional expression (11) is above the upper limit, each lens system is likely to become large, and the overall length of the lens system is likely to increase.

[0049] The imaging optical system 100 of this embodiment satisfies conditional expression (12), and therefore, a wide range can be imaged with a camera using the imaging optical system 100, and a large decrease in peripheral light intensity relative to the central light intensity can be suppressed.

[0050] In the imaging optical system 100 of this embodiment, the third lens 30 is made of glass, and the fifth lens 50 is made of resin, which results in the imaging optical system 100 having good temperature characteristics.

[0051] Fig. 3 is a diagram showing spherical aberration of the imaging optical system 100 shown in Fig. 1. Fig. 4 is a diagram showing lateral chromatic aberration of the imaging optical system 100 shown in Fig. 1, showing lateral chromatic aberration at the maximum half angle of view (80,000 deg). Fig. 5 is a diagram showing astigmatism and distortion of the imaging optical system 100 shown in Fig. 1. Fig. 6 is a diagram showing lateral aberration of the imaging optical system 100 shown in Fig. 1, showing lateral aberration in the tangential direction (Y direction) and sagittal direction (X direction).

[0052] 3 to 6, the aberrations at wavelengths of 486 nm, 588 nm, and 656 nm are indicated by B, G, and R. Regarding the astigmatism shown in Fig. 5, the characteristics in the sagittal direction are indicated by S, and the characteristics in the tangential direction are indicated by T.

[0053] As shown in FIGS. 3 to 6, in the imaging optical system 100 of this embodiment, spherical aberration, chromatic aberration of magnification, astigmatism (distortion), and lateral aberration are corrected to appropriate levels.

[0054] (Embodiment 2) Fig. 7 is an explanatory diagram of an imaging optical system 100 according to embodiment 2. As shown in Fig. 7, the imaging optical system 100 of this embodiment includes, in order from the object side La to the image side Lb, a front group 110, a diaphragm 130, a rear group 120, and an infrared cut filter 80.

[0055] The front group 110 consists of a first lens 10 and a second lens 20, arranged in order from the object side La to the image side Lb. The rear group 120 consists of a third lens 30, a fourth lens 40, a fifth lens 50, a sixth lens 60, and a seventh lens 70, arranged in order from the object side La to the image side Lb. On the image side Lb of the seventh lens 70, a flat infrared cut filter 80, a light-transmitting cover 90, and an image sensor 140 are arranged in order from the object side La to the image side Lb. The image sensor 140 is positioned on the imaging plane of the image side Lb of the imaging optical system 100.

[0056] The first lens 10 is made of resin. The first lens 10 has negative power. The first lens 10 has a convex lens surface 11 on the object side La and a concave lens surface 12 on the image side Lb. The first lens 10 has an aspheric lens surface 12.

[0057] The second lens 20 is made of resin. The second lens 20 has negative power. The second lens 20 has a concave lens surface 21 on the object side La and a convex lens surface 22 on the image side Lb. The second lens 20 has aspherical surfaces on both sides.

[0058] The third lens 30 is made of glass and has positive power. The third lens 30 has a convex lens surface 31 on the object side La and a convex lens surface 32 on the image side Lb.

[0059] The fourth lens 40 is made of resin. The fourth lens 40 has negative power. The fourth lens 40 has a concave lens surface 41 on the object side La and a concave lens surface 42 on the image side Lb. The fourth lens 40 has aspherical surfaces on both sides.

[0060] The fifth lens 50 is made of resin. The fifth lens 50 has positive power. The fifth lens 50 has a convex lens surface 51 on the object side La and a convex lens surface 52 on the image side Lb. The fifth lens 50 has aspherical surfaces on both sides.

[0061] The sixth lens 60 is made of resin. The sixth lens 60 has negative power. The sixth lens 60 has a lens surface 61 on the object side La that is concave, and a lens surface 62 on the image side Lb that is concave. The sixth lens 60 has aspherical surfaces on both sides.

[0062] The seventh lens 70 is made of resin. The seventh lens 70 has positive power. The seventh lens 70 has a convex lens surface 71 on the object side La and a concave lens surface 72 on the image side Lb. The seventh lens 70 has aspherical surfaces on both sides.

[0063] (Lens configuration) 8 is a diagram showing data of the imaging optical system 100 according to the second embodiment. The imaging optical system 100 according to this embodiment satisfies the conditional expressions (1) to (12) described in the first embodiment.

[0064] In this embodiment, d0=13.944 sd11=4.041 IH=3.653 Therefore, d0 / sd11=3.451, which satisfies conditional expression (1). d0 / IH=3.817, which satisfies conditional expression (2).

[0065] In this embodiment, sd11=4.041 IH=3.653 Therefore, sd11 / IH=1.106, which satisfies conditional expression (3).

[0066] In this embodiment, R11=11.808 R12=1.968 Therefore, (R11+R12) / (R11-R12)=1.400, which satisfies conditional expression (4).

[0067] In this embodiment, f0=2.847 R11=11.808 Therefore, R11 / f0=4.148, which satisfies the conditional expression (5).

[0068] In this embodiment, f0=2.847 R12=1.968 Therefore, R12 / f0=0.691, which satisfies conditional expression (6).

[0069] In this embodiment, f0=2.847 R21=-3.687 R22=-3.726 Therefore, R21 / f0=-1.295, which satisfies conditional expression (7). R22 / f0=-1.309, which satisfies conditional expression (8).

[0070] In this embodiment, ν5=56.61 ν6=21.39 Therefore, the conditional expressions (9) and (10) are satisfied.

[0071] In this embodiment, d0=13.944 f0=2.847 Therefore, d0 / f0=4.898, which satisfies conditional expression (11).

[0072] In this embodiment, ω=160 Therefore, conditional expression (12) is satisfied.

[0073] (Action and effect) The imaging optical system 100 of the second embodiment satisfies the conditional expressions (1) to (12) in the same manner as the first embodiment, and therefore can achieve the same effects as the first embodiment. In the imaging optical system 100 of this embodiment, the third lens 30 is made of glass, and the fifth lens 50 is made of resin. This allows Therefore, the temperature characteristics of the imaging optical system 100 become good.

[0074] Fig. 9 is a diagram showing spherical aberration of the imaging optical system 100 shown in Fig. 7. Fig. 10 is a diagram showing chromatic aberration of magnification of the imaging optical system 100 shown in Fig. 7. Fig. 11 is a diagram showing astigmatism and distortion of the imaging optical system 100 shown in Fig. 7. Fig. 12 is a diagram showing lateral aberration of the imaging optical system 100 shown in Fig. 7.

[0075] As shown in FIGS. 9 to 12, in the imaging optical system 100 of this embodiment, spherical aberration, chromatic aberration of magnification, astigmatism (distortion), lateral aberration, and resolution are corrected to appropriate levels.

[0076] (Embodiment 3) Fig. 13 is an explanatory diagram of an imaging optical system 100 according to embodiment 3. As shown in Fig. 13, the imaging optical system 100 of this embodiment includes, in order from the object side La to the image side Lb, a front group 110, a diaphragm 130, a rear group 120, and an infrared cut filter 80.

[0077] The front group 110 consists of a first lens 10 and a second lens 20, arranged in order from the object side La to the image side Lb. The rear group 120 consists of a third lens 30, a fourth lens 40, a fifth lens 50, a sixth lens 60, and a seventh lens 70, arranged in order from the object side La to the image side Lb. On the image side Lb of the seventh lens 70, a flat infrared cut filter 80, a light-transmitting cover 90, and an image sensor 140 are arranged in order from the object side La to the image side Lb. The image sensor 140 is positioned on the imaging plane of the image side Lb of the imaging optical system 100.

[0078] The first lens 10 is made of resin. The first lens 10 has negative power. The first lens 10 has a convex lens surface 11 on the object side La and a concave lens surface 12 on the image side Lb. The first lens 10 has an aspheric lens surface 12.

[0079] The second lens 20 is made of resin. The second lens 20 has positive power. The second lens 20 has a concave lens surface 21 on the object side La and a convex lens surface 22 on the image side Lb. The second lens 20 has aspherical surfaces on both sides.

[0080] The third lens 30 is made of glass and has positive power. The third lens 30 has a convex lens surface 31 on the object side La and a convex lens surface 32 on the image side Lb.

[0081] The fourth lens 40 is made of resin. The fourth lens 40 has negative power. The fourth lens 40 has a concave lens surface 41 on the object side La and a concave lens surface 42 on the image side Lb. The fourth lens 40 has aspherical surfaces on both sides.

[0082] The fifth lens 50 is made of resin. The fifth lens 50 has positive power. The fifth lens 50 has a convex lens surface 51 on the object side La and a convex lens surface 52 on the image side Lb. The fifth lens 50 has aspherical surfaces on both sides.

[0083] The sixth lens 60 is made of resin. The sixth lens 60 has negative power. The sixth lens 60 has a lens surface 61 on the object side La that is concave, and a lens surface 62 on the image side Lb that is concave. The sixth lens 60 has aspherical surfaces on both sides.

[0084] The seventh lens 70 is made of resin. The seventh lens 70 has positive power. The seventh lens 70 has a convex lens surface 71 on the object side La and a concave lens surface 72 on the image side Lb. The seventh lens 70 has aspherical surfaces on both sides.

[0085] (Lens configuration) 14 is a diagram showing data of the imaging optical system 100 according to the third embodiment. The imaging optical system 100 according to this embodiment satisfies the conditional expressions (1) to (12) described in the first embodiment.

[0086] In this embodiment, d0=14.178 sd11=3.933 IH=3.672 Therefore, d0 / sd11=3.605, which satisfies conditional expression (1). d0 / IH=3.861, which satisfies conditional expression (2).

[0087] In this embodiment, sd11=3.933 IH=3.672 Therefore, sd11 / IH=1.071, which satisfies conditional expression (3).

[0088] In this embodiment, R11=10.848 R12=1.930 Therefore, (R11+R12) / (R11-R12)=1.433, which satisfies the conditional expression (4).

[0089] In this embodiment, f0=2.883 R11=10.848 Therefore, R11 / f0=3.763, which satisfies the conditional expression (5).

[0090] In this embodiment, f0=2.883 R12=1.930 Therefore, R12 / f0=0.669, which satisfies conditional expression (6).

[0091] In this embodiment, f0=2.883 R21=-4.231 R22=-3.909 Therefore, R21 / f0=-1.467, which satisfies conditional expression (7). R22 / f0=-1.356, which satisfies conditional expression (8).

[0092] In this embodiment, ν5=55.71 ν6=21.23 Therefore, the conditional expressions (9) and (10) are satisfied.

[0093] In this embodiment, d0=14.178 f0=2.883 Therefore, d0 / f0=4.918, which satisfies conditional expression (11).

[0094] In this embodiment, ω=160 Therefore, conditional expression (12) is satisfied.

[0095] (Action and effect) The imaging optical system 100 of the third embodiment satisfies conditional expressions (1) to (12) like the first embodiment, and can therefore achieve the same effects as the first embodiment. In the imaging optical system 100 of this embodiment, the third lens 30 is made of glass, and the fifth lens 50 is made of resin. This improves the temperature characteristics of the imaging optical system 100.

[0096] Fig. 15 is a diagram showing spherical aberration of the imaging optical system 100 shown in Fig. 13. Fig. 16 is a diagram showing chromatic aberration of magnification of the imaging optical system 100 shown in Fig. 13. Fig. 17 is a diagram showing astigmatism and distortion of the imaging optical system 100 shown in Fig. 13. Fig. 18 is a diagram showing lateral aberration of the imaging optical system 100 shown in Fig. 13.

[0097] As shown in FIGS. 15 to 18, in the imaging optical system 100 of this embodiment, spherical aberration, chromatic aberration of magnification, astigmatism (distortion), lateral aberration, and resolution are corrected to appropriate levels.

[0098] (Embodiment 4) Fig. 19 is an explanatory diagram of an imaging optical system 100 according to embodiment 4. As shown in Fig. 19, the imaging optical system 100 of this embodiment includes, in order from the object side La to the image side Lb, a front group 110, a diaphragm 130, a rear group 120, and an infrared cut filter 80.

[0099] The front group 110 consists of a first lens 10 and a second lens 20, arranged in order from the object side La to the image side Lb. The rear group 120 consists of a third lens 30, a fourth lens 40, a fifth lens 50, a sixth lens 60, and a seventh lens 70, arranged in order from the object side La to the image side Lb. On the image side Lb of the seventh lens 70, a flat infrared cut filter 80, a light-transmitting cover 90, and an image sensor 140 are arranged in order from the object side La to the image side Lb. The image sensor 140 is positioned on the imaging plane of the image side Lb of the imaging optical system 100.

[0100] The first lens 10 is made of resin. The first lens 10 has negative power. The first lens 10 has a convex lens surface 11 on the object side La and a concave lens surface 12 on the image side Lb. The first lens 10 has an aspheric lens surface 12.

[0101] The second lens 20 is made of resin. The second lens 20 has negative power. The second lens 20 has a concave lens surface 21 on the object side La and a convex lens surface 22 on the image side Lb. The second lens 20 has aspherical surfaces on both sides.

[0102] The third lens 30 is made of glass and has positive power. The third lens 30 has a convex lens surface 31 on the object side La and a convex lens surface 32 on the image side Lb.

[0103] The fourth lens 40 is made of resin. The fourth lens 40 has negative power. The fourth lens 40 has a concave lens surface 41 on the object side La and a concave lens surface 42 on the image side Lb. The fourth lens 40 has aspherical surfaces on both sides.

[0104] The fifth lens 50 is made of resin. The fifth lens 50 has positive power. The fifth lens 50 has a convex lens surface 51 on the object side La and a convex lens surface 52 on the image side Lb. The fifth lens 50 has aspherical surfaces on both sides.

[0105] The sixth lens 60 is made of resin. The sixth lens 60 has negative power. The sixth lens 60 has a lens surface 61 on the object side La that is concave, and a lens surface 62 on the image side Lb that is concave. The sixth lens 60 has aspherical surfaces on both sides.

[0106] The seventh lens 70 is made of resin. The seventh lens 70 has positive power. The seventh lens 70 has a convex lens surface 71 on the object side La and a concave lens surface 72 on the image side Lb. The seventh lens 70 has aspherical surfaces on both sides.

[0107] (Lens configuration) 20 is a diagram showing data of the imaging optical system 100 of the fourth embodiment. The imaging optical system 100 of this embodiment satisfies the conditional expressions (1) to (12) described in the first embodiment.

[0108] In this embodiment, d0=14.013 sd11=4.056 IH=3.654 Therefore, d0 / sd11=3.455, which satisfies conditional expression (1). d0 / IH=3.835, which satisfies conditional expression (2).

[0109] In this embodiment, sd11=4.056 IH=3.654 Therefore, sd11 / IH=1.110, which satisfies conditional expression (3).

[0110] In this embodiment, R11=11.980 R12=1.944 Therefore, (R11+R12) / (R11-R12)=1.387, which satisfies condition (4).

[0111] In this embodiment, f0 = 2.835 R11=11.980 Therefore, R11 / f0 = 4.225, which satisfies condition (5).

[0112] In this embodiment, f0 = 2.835 R12=1.944 Therefore, R12 / f0 = 0.686, which satisfies condition (6).

[0113] In this embodiment, f0 = 2.835 R21 = -3.691 R22 = -3.730 Therefore, R21 / f0 = -1.302, satisfying condition (7). R22 / f0 = -1.315, satisfying condition (8).

[0114] In this embodiment, ν5=56.61 ν6=21.39 Therefore, the conditional expressions (9) and (10) are satisfied.

[0115] In this embodiment, d0=14.013 f0 = 2.835 Therefore, d0 / f0 = 4.942, which satisfies condition (11).

[0116] In this embodiment, ω=160 Therefore, conditional expression (12) is satisfied.

[0117] (Action and effect) The imaging optical system 100 of Embodiment 4 satisfies the same conditions (1) to (12) as Embodiment 1, and therefore can achieve the same effects as Embodiment 1. In the imaging optical system 100 of this embodiment, the third lens 30 is made of glass, and the fifth lens 50 is made of resin. This results in good temperature characteristics for the imaging optical system 100.

[0118] Figure 21 shows the spherical aberration of the imaging optical system 100 shown in Figure 19. Figure 22 shows the lateral chromatic aberration of the imaging optical system 100 shown in Figure 19. Figure 23 shows the astigmatism and distortion of the imaging optical system 100 shown in Figure 19. Figure 24 shows the lateral aberration of the imaging optical system 100 shown in Figure 19.

[0119] As shown in Figures 21 to 24, in the imaging optical system 100 of this embodiment, spherical aberration, chromatic aberration, astigmatism (distortion), transverse aberration, and resolution are corrected to an appropriate level.

[0120] (Embodiment 5) Figure 25 is an explanatory diagram of the imaging optical system 100 according to Embodiment 5. As shown in Figure 25, the imaging optical system 100 of this embodiment comprises, in order from the object side La to the image side Lb, a front group 110, an aperture 130, a rear group 120, and an infrared cut filter 80.

[0121] The front group 110 consists of a first lens 10 and a second lens 20, arranged in order from the object side La to the image side Lb. The rear group 120 consists of a third lens 30, a fourth lens 40, a fifth lens 50, a sixth lens 60, and a seventh lens 70, arranged in order from the object side La to the image side Lb. On the image side Lb of the seventh lens 70, a flat infrared cut filter 80, a light-transmitting cover 90, and an image sensor 140 are arranged in order from the object side La to the image side Lb. The image sensor 140 is positioned on the imaging plane of the image side Lb of the imaging optical system 100.

[0122] The first lens 10 is made of resin. The first lens 10 has negative power. The first lens 10 has a convex lens surface 11 on the object side La and a concave lens surface 12 on the image side Lb. The first lens 10 has an aspheric lens surface 12.

[0123] The second lens 20 is made of resin. The second lens 20 has positive power. The second lens 20 has a concave lens surface 21 on the object side La and a convex lens surface 22 on the image side Lb. The second lens 20 has aspherical surfaces on both sides.

[0124] The third lens 30 is made of resin. The third lens 30 has positive power. The third lens 30 has a convex lens surface 31 on the object side La and a convex lens surface 32 on the image side Lb. The third lens 30 has aspheric surfaces on both sides.

[0125] The fourth lens 40 is made of resin. The fourth lens 40 has negative power. The fourth lens 40 has a concave lens surface 41 on the object side La and a concave lens surface 42 on the image side Lb. The fourth lens 40 has aspherical surfaces on both sides.

[0126] The fifth lens 50 is made of glass and has positive power. The fifth lens 50 has a convex lens surface 51 on the object side La and a convex lens surface 52 on the image side Lb.

[0127] The sixth lens 60 is made of resin. The sixth lens 60 has negative power. The sixth lens 60 has a lens surface 61 on the object side La that is concave, and a lens surface 62 on the image side Lb that is concave. The sixth lens 60 has aspherical surfaces on both sides.

[0128] The seventh lens 70 is made of resin. The seventh lens 70 has positive power. The seventh lens 70 has a convex lens surface 71 on the object side La and a concave lens surface 72 on the image side Lb. The seventh lens 70 has aspherical surfaces on both sides.

[0129] (Lens configuration) 26 is a diagram showing data of the imaging optical system 100 according to the fifth embodiment. The imaging optical system 100 according to this embodiment satisfies the conditional expressions (1) to (12) described in the first embodiment.

[0130] In this embodiment, d0 = 14.294 sd11 = 4.167 IH = 3.682 Therefore, d0 / sd11=3.430, which satisfies conditional expression (1). d0 / IH=3.882, which satisfies conditional expression (2).

[0131] In this embodiment, sd11 = 4.167 IH = 3.682 Therefore, sd11 / IH=1.132, which satisfies conditional expression (3).

[0132] In this embodiment, R11 = 12.028 R12 = 2.034 Therefore, (R11+R12) / (R11-R12)=1.407, which satisfies the conditional expression (4).

[0133] In this embodiment, f0 = 2.794 R11 = 12.028 Therefore, R11 / f0=4.305, which satisfies conditional expression (5).

[0134] In this embodiment, f0 = 2.794 R12 = 2.034 Therefore, R12 / f0=0.728, which satisfies conditional expression (6).

[0135] In this embodiment, f0 = 2.794 R21 = -3.763 R22 = -3.657 Therefore, R21 / f0=-1.347, which satisfies conditional expression (7). R22 / f0=-1.309, which satisfies conditional expression (8).

[0136] In this embodiment, ν5=55.46 ν6=21.39 Therefore, the conditional expressions (9) and (10) are satisfied.

[0137] In this embodiment, d0 = 14.294 f0 = 2.794 Therefore, d0 / f0=5.116, which satisfies conditional expression (11).

[0138] In this embodiment, ω=160 Therefore, conditional expression (12) is satisfied.

[0139] (Action and effect) The imaging optical system 100 of embodiment 5 satisfies conditional expressions (1) to (12) like embodiment 1, and can therefore achieve the same effects as embodiment 1. In the imaging optical system 100 of this embodiment, the third lens 30 is made of resin, and the fifth lens 50 is made of glass. This improves the temperature characteristics of the imaging optical system 100.

[0140] Fig. 27 is a diagram showing spherical aberration of the imaging optical system 100 shown in Fig. 25. Fig. 28 is a diagram showing chromatic aberration of magnification of the imaging optical system 100 shown in Fig. 25. Fig. 29 is a diagram showing astigmatism and distortion of the imaging optical system 100 shown in Fig. 25. Fig. 30 is a diagram showing lateral aberration of the imaging optical system 100 shown in Fig. 25.

[0141] As shown in FIGS. 27 to 30, in the imaging optical system 100 of this embodiment, spherical aberration, chromatic aberration of magnification, astigmatism (distortion), lateral aberration, and resolution are corrected to appropriate levels.

[0142] (Embodiment 6) Fig. 31 is an explanatory diagram of an imaging optical system 100 according to embodiment 6. As shown in Fig. 31, the imaging optical system 100 of this embodiment includes, in order from the object side La to the image side Lb, a front group 110, a diaphragm 130, a rear group 120, and an infrared cut filter 80.

[0143] The front group 110 consists of a first lens 10 and a second lens 20, arranged in order from the object side La to the image side Lb. The rear group 120 consists of a third lens 30, a fourth lens 40, a fifth lens 50, a sixth lens 60, and a seventh lens 70, arranged in order from the object side La to the image side Lb. On the image side Lb of the seventh lens 70, a flat infrared cut filter 80, a light-transmitting cover 90, and an image sensor 140 are arranged in order from the object side La to the image side Lb. The image sensor 140 is positioned on the imaging plane of the image side Lb of the imaging optical system 100.

[0144] The first lens 10 is made of resin. The first lens 10 has negative power. The first lens 10 has a convex lens surface 11 on the object side La and a concave lens surface 12 on the image side Lb. The first lens 10 has an aspheric lens surface 12.

[0145] The second lens 20 is made of resin. The second lens 20 has positive power. The second lens 20 has a concave lens surface 21 on the object side La and a convex lens surface 22 on the image side Lb. The second lens 20 has aspherical surfaces on both sides.

[0146] The third lens 30 is made of resin. The third lens 30 has positive power. The third lens 30 has a convex lens surface 31 on the object side La and a convex lens surface 32 on the image side Lb. The third lens 30 has aspheric surfaces on both sides.

[0147] The fourth lens 40 is made of resin. The fourth lens 40 has negative power. The fourth lens 40 has a concave lens surface 41 on the object side La and a concave lens surface 42 on the image side Lb. The fourth lens 40 has aspherical surfaces on both sides.

[0148] The fifth lens 50 is made of glass and has positive power. The fifth lens 50 has a convex lens surface 51 on the object side La and a convex lens surface 52 on the image side Lb.

[0149] The sixth lens 60 is made of resin. The sixth lens 60 has negative power. The sixth lens 60 has a lens surface 61 on the object side La that is concave, and a lens surface 62 on the image side Lb that is concave. The sixth lens 60 has aspherical surfaces on both sides.

[0150] The seventh lens 70 is made of resin. The seventh lens 70 has negative power. The seventh lens 70 has a convex shape on the lens surface 71 on the object side La and a concave shape on the lens surface 72 on the image side Lb. The seventh lens 70 has aspherical shapes on both sides.

[0151] (Lens configuration) Figure 32 shows the data from the imaging optical system 100 of Embodiment 6. The imaging optical system 100 of this embodiment satisfies the conditions (1) to (12) described in Embodiment 1.

[0152] In this embodiment, d0=14.221 sd11=4.338 IH=3.677 Therefore, d0 / sd11 = 3.278, satisfying condition (1). d0 / IH = 3.868, satisfying condition (2).

[0153] In this embodiment, sd11=4.338 IH=3.677 Therefore, sd11 / IH = 1.180, which satisfies condition (3).

[0154] In this embodiment, R11=12.568 R12=2.140 Therefore, (R11+R12) / (R11-R12)=1.411, which satisfies condition (4).

[0155] In this embodiment, f0 = 2.807 R11=12.568 Therefore, R11 / f0 = 4.476, which satisfies condition (5).

[0156] In this embodiment, f0 = 2.807 R12=2.140 Therefore, R12 / f0 = 0.762, which satisfies condition (6).

[0157] In this embodiment, f0 = 2.807 R21 = -3.780 R22 = -3.733 Therefore, R21 / f0 = -1.347, satisfying condition (7). R22 / f0 = -1.330, satisfying condition (8).

[0158] In this embodiment, ν5=55.46 ν6=21.39 Therefore, the conditional expressions (9) and (10) are satisfied.

[0159] In this embodiment, d0=14.221 f0 = 2.807 Therefore, d0 / f0 = 5.066, which satisfies condition (11).

[0160] In this embodiment, ω=160 Therefore, conditional expression (12) is satisfied.

[0161] (Action and effect) The imaging optical system 100 of the sixth embodiment satisfies conditional expressions (1) to (12) like the first embodiment, and can therefore achieve the same effects as the first embodiment. In the imaging optical system 100 of this embodiment, the third lens 30 is made of resin, and the fifth lens 50 is made of glass. This improves the temperature characteristics of the imaging optical system 100.

[0162] Fig. 33 is a diagram showing spherical aberration of the imaging optical system 100 shown in Fig. 31. Fig. 34 is a diagram showing chromatic aberration of magnification of the imaging optical system 100 shown in Fig. 31. Fig. 35 is a diagram showing astigmatism and distortion of the imaging optical system 100 shown in Fig. 31. Fig. 36 is a diagram showing lateral aberration of the imaging optical system 100 shown in Fig. 31.

[0163] As shown in FIGS. 33 to 36, in the imaging optical system 100 of this embodiment, spherical aberration, chromatic aberration of magnification, astigmatism (distortion), lateral aberration, and resolution are corrected to appropriate levels.

[0164] (Embodiment 7) Fig. 37 is an explanatory diagram of an imaging optical system 100 according to embodiment 7. As shown in Fig. 37, the imaging optical system 100 of this embodiment includes, in order from the object side La to the image side Lb, a front group 110, a diaphragm 130, a rear group 120, and an infrared cut filter 80.

[0165] The front group 110 is made up of, in order from the object side La to the image side Lb, a first lens 10 and a second lens 20. The rear group 120 is made up of, in order from the object side La to the image side Lb, a third lens The imaging optical system 100 is made up of a first lens 30, a fourth lens 40, a fifth lens 50, a sixth lens 60, and a seventh lens 70. On the image side Lb of the seventh lens 70, in this order from the object side La to the image side Lb, there are arranged a flat infrared cut filter 80, a light-transmitting cover 90, and an image sensor 140. The image sensor 140 is arranged on the image plane on the image side Lb of the imaging optical system 100.

[0166] The first lens 10 is made of resin. The first lens 10 has negative power. The first lens 10 has a convex lens surface 11 on the object side La and a concave lens surface 12 on the image side Lb. The first lens 10 has an aspheric lens surface 12.

[0167] The second lens 20 is made of resin. The second lens 20 has positive power. The second lens 20 has a concave lens surface 21 on the object side La and a convex lens surface 22 on the image side Lb. The second lens 20 has aspherical surfaces on both sides.

[0168] The third lens 30 is made of resin. The third lens 30 has positive power. The third lens 30 has a convex lens surface 31 on the object side La and a convex lens surface 32 on the image side Lb. The third lens 30 has aspheric surfaces on both sides.

[0169] The fourth lens 40 is made of resin. The fourth lens 40 has negative power. The fourth lens 40 has a concave lens surface 41 on the object side La and a concave lens surface 42 on the image side Lb. The fourth lens 40 has aspherical surfaces on both sides.

[0170] The fifth lens 50 is made of glass and has positive power. The fifth lens 50 has a convex lens surface 51 on the object side La and a convex lens surface 52 on the image side Lb.

[0171] The sixth lens 60 is made of resin. The sixth lens 60 has negative power. The sixth lens 60 has a lens surface 61 on the object side La that is concave, and a lens surface 62 on the image side Lb that is concave. The sixth lens 60 has aspherical surfaces on both sides.

[0172] The seventh lens 70 is made of resin. The seventh lens 70 has negative power. The seventh lens 70 has a convex shape on the lens surface 71 on the object side La and a concave shape on the lens surface 72 on the image side Lb. The seventh lens 70 has aspherical shapes on both sides.

[0173] (Lens configuration) 38 is a diagram showing data of the imaging optical system 100 of the seventh embodiment. The imaging optical system 100 of this embodiment satisfies the conditional expressions (1) to (12) described in the first embodiment.

[0174] In this embodiment, d0=13.221 sd11=3.984 IH=3.658 Therefore, d0 / sd11=3.318, which satisfies conditional expression (1). d0 / IH=3.614, which satisfies conditional expression (2).

[0175] In this embodiment, sd11=3.984 IH=3.658 Therefore, sd11 / IH=1.089, which satisfies conditional expression (3).

[0176] In this embodiment, R11=10.274 R12=2.198 Therefore, (R11+R12) / (R11-R12)=1.544, which satisfies the conditional expression (4).

[0177] In this embodiment, f0=2.881 R11=10.274 Therefore, R11 / f0=3.567, which satisfies conditional expression (5).

[0178] In this embodiment, f0=2.881 R12=2.198 Therefore, R12 / f0=0.763, which satisfies conditional expression (6).

[0179] In this embodiment, f0=2.881 R21=-3.844 R22=-3.763 Therefore, R21 / f0=-1.334, which satisfies conditional expression (7). R22 / f0=-1.306, which satisfies conditional expression (8).

[0180] In this embodiment, ν5=55.46 ν6=21.39 Therefore, the conditional expressions (9) and (10) are satisfied.

[0181] In this embodiment, d0=13.221 f0=2.881 Therefore, d0 / f0=4.590, which satisfies conditional expression (11).

[0182] In this embodiment, ω=160 Therefore, conditional expression (12) is satisfied.

[0183] (Action and effect) The imaging optical system 100 of Embodiment 7 satisfies the same conditions (1) to (12) as in Embodiment 1, and therefore can achieve the same effects as Embodiment 1. In the imaging optical system 100 of this embodiment, the third lens 30 is made of resin, and the fifth lens 50 is made of glass. This results in good temperature characteristics for the imaging optical system 100.

[0184] Figure 39 shows the spherical aberration of the imaging optical system 100 shown in Figure 37. Figure 40 shows the lateral chromatic aberration of the imaging optical system 100 shown in Figure 37. Figure 41 shows the astigmatism and distortion of the imaging optical system 100 shown in Figure 37. Figure 42 shows the lateral aberration of the imaging optical system 100 shown in Figure 37.

[0185] As shown in Figures 39 to 42, in the imaging optical system 100 of this embodiment, spherical aberration, chromatic aberration, astigmatism (distortion), transverse aberration, and resolution are corrected to an appropriate level.

[0186] The present technology can be configured as follows.

[0187] (1) The lens group, arranged in order from the object side to the image side, consists of a front group, an aperture, and a rear group. The aforementioned front group consists of a plurality of lenses, including a first lens positioned closest to the object. The aforementioned rear group consists of multiple lenses, The first lens has negative power, If the total length of the lens system is d0, the effective radius of the object-side lens surface of the first lens is sd11, and the maximum image height is IH, then the following conditional equation 3.000< d0 / sd11 <4.500 (1) 2.500< d0 / IH <5.000 (2) An imaging optical system characterized by satisfying the following conditions.

[0188] (2) If the effective radius of the object-side lens surface of the first lens is sd11 and the maximum image height is IH, then the following conditional equation 0.650< sd11 / IH <1.300 (3) The imaging optical system according to (1), characterized in that it satisfies the following conditions.

[0189] (3) If the radius of curvature of the object-side lens surface of the first lens is R11, and the radius of curvature of the image-side lens surface of the first lens is R12, then the following conditional equation 1.100< (R11+R12) / (R11-R12) <2.000 (4) The imaging optical system according to (1) or (2), characterized in that it satisfies the following conditions.

[0190] (4) If the focal length of the entire lens system is f0, and the radius of curvature of the object-side lens surface of the first lens is R11, then the following conditional equation 2.000< R11 / f0 <9.000 (5) An imaging optical system according to any one of (1) to (3), characterized in that it satisfies the following conditions.

[0191] (5) When the focal length of the entire lens system is f0 and the radius of curvature of the image-side lens surface of the first lens is R12, the following conditional expression is satisfied: 0.500< R12 / f0 <3.000 (6) The imaging optical system according to any one of (1) to (4), wherein the following is satisfied:

[0192] (6) the front group comprises, in order from the object side to the image side, the first lens and a second lens, When the focal length of the entire lens system is f0, the radius of curvature of the lens surface on the object side of the second lens is R21, and the radius of curvature of the lens surface on the image side of the second lens is R22, the following conditional expression is satisfied: -6.000< R21 / f0 <-1.500 (7) -6.000< R22 / f0 <-1.500 (8) The imaging optical system according to any one of (1) to (5), wherein the following is satisfied:

[0193] (7) The front group includes, in order from the object side to the image side, the first lens, the second lens, And the rear group comprises, in order from the object side to the image side, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens, the third lens has a positive power, the fourth lens has a negative power, the fifth lens has a positive power, The imaging optical system according to any one of (1) to (6), wherein the sixth lens has a negative power.

[0194] (8) When the Abbe number of the fifth lens is ν5 and the Abbe number of the sixth lens is ν6, the following conditional expression is satisfied: 50.000< ν5 (9) ν6 <30,000 (10) The imaging optical system according to (7) satisfies the following:

[0195] (9) the third lens is made of resin, The imaging optical system according to (7) or (8), wherein the fifth lens is made of glass.

[0196] (10) the third lens is made of glass; The imaging optical system according to (7) or (8), wherein the fifth lens is made of resin. [Explanation of symbols]

[0197] 100...Imaging optical system, 110...Front group, 120...Rear group, 10...First lens, 20...Second lens, 30...Third lens, 40...Fourth lens, 50...Fifth lens, 60...Sixth lens, 70...Seventh lens, 80...Infrared cut filter, 90...Cover, 130...Aperture, 140...Image sensor.

Claims

1. It comprises, in order from the object side to the image side, a front group, a stop, and a rear group, the front group is made up of a plurality of lenses including a first lens arranged closest to the object, the rear group is made up of a plurality of lenses, the first lens has a negative power; When the total length of the entire lens system is d0, the effective radius of the lens surface on the object side of the first lens is sd11, and the maximum image height is IH, the following conditional expression is satisfied: 3.000<d0 / sd11<4.500 (1) 2.500<d0 / IH<5.000 (2) An imaging optical system characterized by satisfying the following:

2. When the effective radius of the lens surface on the object side of the first lens is sd11 and the maximum image height is IH, the following conditional expression is satisfied: 0.650< sd11 / IH <1.300 (3) 2. The imaging optical system according to claim 1, wherein the following is satisfied:

3. When the radius of curvature of the lens surface of the first lens on the object side is R11 and the radius of curvature of the lens surface of the first lens on the image side is R12, the following conditional expression is satisfied: 1.100<(R11+R12) / (R11-R12)<2.000 (4) 3. The imaging optical system according to claim 1, wherein the following is satisfied:

4. When the focal length of the entire lens system is f0 and the radius of curvature of the lens surface of the first lens on the object side is R11, the following conditional expression is satisfied: 2.000< R11 / f0 <9.000 (5) 2. The imaging optical system according to claim 1, wherein the following is satisfied:

5. When the focal length of the entire lens system is f0 and the radius of curvature of the image-side lens surface of the first lens is R12, the following conditional expression is satisfied: 0.500< R12 / f0 <3.000 (6) 2. The imaging optical system according to claim 1, wherein the following is satisfied:

6. the front group comprises, in order from the object side to the image side, the first lens and a second lens, When the focal length of the entire lens system is f0, the radius of curvature of the lens surface of the second lens on the object side is R21, and the radius of curvature of the lens surface of the second lens on the image side is R22, the following conditional expression is satisfied: -6.000< R21 / f0 <-1.500 (7) -6.000< R22 / f0 <-1.500 (8) 2. The imaging optical system according to claim 1, wherein the following is satisfied:

7. the front group comprises, in order from the object side to the image side, the first lens and a second lens, the rear group comprises, in order from the object side to the image side, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens, the third lens has a positive power, the fourth lens has a negative power, the fifth lens has a positive power, The imaging optical system according to claim 1 , wherein the sixth lens has a negative power.

8. When the Abbe number of the fifth lens is ν5 and the Abbe number of the sixth lens is ν6, the following conditional expression is satisfied: 50.000< ν5 (9) ν6 <30.000 (10) 8. The imaging optical system according to claim 7, wherein the following is satisfied:

9. the third lens is made of resin, 9. The imaging optical system according to claim 7, wherein the fifth lens is made of glass.

10. the third lens is made of glass, 9. The imaging optical system according to claim 7, wherein the fifth lens is made of resin.

Images