Imaging optical system and imaging device

Abstract

To provide an imaging optical system capable of effectively correcting chromatic aberration, and an imaging apparatus equipped with such an imaging optical system. [Solution] The 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 comprises, in order from the object side to the image side, a first group 111 having negative power and a second group 112 having positive power. The second group 112 comprises a third lens 30 and a fourth lens 40 adjacent to the third lens 30 on the image side and positioned closest to the image. If the Abbe number of the third lens 30 is ν21, the Abbe number of the fourth lens 40 is ν22, the focal length of the third lens 30 is f3, and the focal length of the fourth lens 40 is f4, then the following conditional expression ν21<30.000 44.000<ν22 0.000 < |f3 / f4| < 0.500 It satisfies the condition.

Description

Technical Field

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

[0002] An imaging optical system used in an in-vehicle camera or a surveillance camera is described in Patent Document 1. The imaging optical system of Patent Document 1 includes an aperture stop, a first lens group disposed on the object side of the aperture stop, and a second lens group disposed on the image side of the aperture stop. The first lens group includes, in order from the object side, a first lens, a second lens, a third lens, and a fourth lens. The second lens group includes, in order from the object side, a fifth lens, a sixth lens, and a seventh lens. The sixth lens and the seventh lens constitute a cemented lens. This cemented lens is disposed on the most image side and corrects chromatic aberration.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In an imaging optical system used in an in-vehicle camera or a surveillance camera, in order to obtain a sharp image, it is required to further correct chromatic aberration well.

[0005] In view of the above problems, an object of the present invention is to provide an imaging optical system capable of correcting chromatic aberration well and an imaging device including the imaging optical system.

Means for Solving the Problems

[0006] To solve the above problems, one aspect of the imaging optical system of the present invention includes a front group, an aperture stop, and a rear group in order from the object side to the image side. The aforementioned group comprises, in order from the object side to the image side, a first group having negative power and a second group having positive power. The second group comprises a first lens of the second group and a second lens of the second group that is adjacent to the first lens of the second group on the image side and positioned closest to the image side. If the Abbe number of the first lens in the second group is ν21, the Abbe number of the second lens in the second group is ν22, the focal length of the first lens in the second group is f3, and the focal length of the second lens in the second group is f4, then the following conditional expression ν21 <30.000 44.000 < ν22 0.000 <|f3 / f4|< 0.500 It is characterized by satisfying the following conditions.

[0007] One embodiment of the imaging apparatus of the present invention is characterized by comprising an imaging optical system and an image sensor disposed on the image side of the imaging optical system. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is an explanatory diagram of an imaging device according to Embodiment 1. [Figure 2] Figure 2 shows the data of the imaging optical system of Embodiment 1. [Figure 3] Figure 3 shows the spherical aberration of the imaging optical system shown in Figure 1. [Figure 4] Figure 4 shows the chromatic aberration of the imaging optical system shown in Figure 1. [Figure 5] Figure 5 shows the astigmatism and distortion of the imaging optical system shown in Figure 1. [Figure 6] Figure 6 shows the lateral aberration of the imaging optical system shown in Figure 1. [Figure 7] Figure 7 is an explanatory diagram of the imaging device according to Embodiment 2. [Figure 8] Figure 8 shows the data from the imaging optical system of Embodiment 2. [Figure 9] Figure 9 shows the spherical aberration of the imaging optical system shown in Figure 7. [Figure 10] FIG. 10 is a diagram showing the longitudinal chromatic aberration of the imaging optical system shown in FIG. 7. [Figure 11] FIG. 11 is a diagram showing the spherical aberration and distortion of the imaging optical system shown in FIG. 7. [Figure 12] FIG. 12 is a diagram showing the lateral aberration of the imaging optical system shown in FIG. 7. [Figure 13] FIG. 13 is an explanatory diagram of the imaging device according to Embodiment 3. [Figure 14] FIG. 14 is a diagram showing data of the imaging optical system of Embodiment 3. [Figure 15] FIG. 15 is a diagram showing the spherical aberration of the imaging optical system shown in FIG. 13. [Figure 16] FIG. 16 is a diagram showing the longitudinal chromatic aberration of the imaging optical system shown in FIG. 13. [Figure 17] FIG. 17 is a diagram showing the spherical aberration and distortion of the imaging optical system shown in FIG. 13. [Figure 18] FIG. 18 is a diagram showing the lateral aberration of the imaging optical system shown in FIG. 13. [Figure 19] FIG. 19 is an explanatory diagram of the imaging device according to Embodiment 4. [Figure 20] FIG. 20 is a diagram showing data of the imaging optical system of Embodiment 4. [Figure 21] FIG. 21 is a diagram showing the spherical aberration of the imaging optical system shown in FIG. 19. [Figure 22] FIG. 22 is a diagram showing the longitudinal chromatic aberration of the imaging optical system shown in FIG. 19. [Figure 23] FIG. 23 is a diagram showing the spherical aberration and distortion of the imaging optical system shown in FIG. 19. [Figure 24] FIG. 24 is a diagram showing the lateral aberration of the imaging optical system shown in FIG. 19. [Figure 25] FIG. 25 is an explanatory diagram of the imaging device according to Embodiment 5. [Figure 26] FIG. 26 is a diagram showing data of the imaging optical system of Embodiment 5. [Figure 27] FIG. 27 is a diagram showing the spherical aberration of the imaging optical system shown in FIG. 25. [Figure 28] Figure 28 shows the chromatic aberration of the imaging optical system shown in Figure 25. [Figure 29] Figure 29 shows the astigmatism and distortion of the imaging optical system shown in Figure 25. [Figure 30] Figure 30 shows the lateral aberration of the imaging optical system shown in Figure 25. [Figure 31] Figure 31 is an explanatory diagram of the imaging device according to Embodiment 6. [Figure 32] Figure 32 shows the data of the imaging optical system of Embodiment 6. [Figure 33] Figure 33 shows the spherical aberration of the imaging optical system shown in Figure 31. [Figure 34] Figure 34 shows the chromatic aberration of the imaging optical system shown in Figure 31. [Figure 35] Figure 35 shows the astigmatism and distortion of the imaging optical system shown in Figure 31. [Figure 36] Figure 36 shows the lateral aberration of the imaging optical system shown in Figure 31. [Figure 37] Figure 37 is an explanatory diagram of the imaging device according to Embodiment 7. [Figure 38] Figure 38 shows the data of the imaging optical system of Embodiment 7. [Figure 39] Figure 39 shows the spherical aberration of the imaging optical system shown in Figure 37. [Figure 40] Figure 40 shows the chromatic aberration of the imaging optical system shown in Figure 37. [Figure 41] Figure 41 shows the astigmatism and distortion of the imaging optical system shown in Figure 37. [Figure 42] Figure 42 shows the lateral aberration of the imaging optical system shown in Figure 37. [Modes for carrying out the invention]

[0009] The following describes an embodiment of an imaging device 200 equipped with an imaging optical system 100 to which the present invention is applied. The imaging device 200 is used in in-vehicle cameras and surveillance cameras. In particular, the imaging optical system 100 is suitable for use in surveillance cameras for monitoring inside vehicles.

[0010] (Embodiment 1) Figure 1 is an explanatory diagram of an imaging device 200 according to Embodiment 1. As shown in Figure 1, the imaging device 200 of this embodiment comprises an imaging optical system 100 and an image sensor 140. The imaging optical system 100 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. On the image side Lb of the infrared cut filter 80, in order from the object side La to the image side Lb, a translucent cover 90 and the image sensor 140 are arranged. The image sensor 140 is positioned on the imaging plane of the image side Lb of the imaging optical system 100.

[0011] The front group 110 comprises a first group 111 having negative power and a second group 112 having positive power, arranged in order from the object side La to the image side Lb. The first group 111 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 first lens 10 is made of glass. The first lens 10 has negative power. The first lens 10 has a convex shape on the lens surface 11 on the object side La and a concave shape on the lens surface 12 on the image side Lb. The second lens 20 is made of resin. The second lens 20 has negative power. The second lens 20 has a convex shape on the lens surface 21 on the object side La and a concave shape on the lens surface 22 on the image side Lb. The second lens 20 has aspherical shapes on both sides.

[0012] The second group 112 consists of a third lens 30 (second group first lens) and a fourth lens 40 (second group second lens), arranged in order from the object side La to the image side Lb. The third lens 30 is made of resin. The third lens 30 has positive power. The third lens 30 has a convex shape near the optical axis L and a concave shape at the periphery on the lens surface 31 on the object side La, and a convex shape on the lens surface 32 on the image side Lb. The third lens 30 has aspherical shapes on both sides. The fourth lens 40 is made of resin. The fourth lens 40 has negative power. The fourth lens 40 has a concave shape on the lens surface 41 on the object side La and a convex shape on the lens surface 42 on the image side Lb. The fourth lens 40 has aspherical shapes on both sides.

[0013] The rear group 120 consists of a fifth lens 50 and a cemented lens 75, arranged in order from the object side La to the image side Lb. The cemented lens 75 consists of a sixth lens 60 (object side lens) and a seventh lens 70 (image side lens), arranged in order from the object side La to the image side Lb. The sixth lens 60 and the seventh lens 70 are bonded together by adhesive.

[0014] The fifth lens 50 is made of glass. The fifth lens 50 has positive power. The fifth lens 50 has a convex shape on the lens surface 51 on the object side La and a convex shape on the lens surface 52 on the image side Lb. The sixth lens 60 is made of resin. The sixth lens 60 has negative power. The sixth lens 60 has a concave shape on the lens surface 61 on the object side La and a concave shape on the lens surface 62 on the image side Lb. The sixth lens 60 has aspherical shapes on both sides. The seventh lens 70 is made of resin. The seventh lens 70 has positive power. The seventh lens 70 has a convex shape on the lens surface 71 on the object side La and a convex shape on the lens surface 72 on the image side Lb. The seventh lens 70 has aspherical shapes on both sides.

[0015] Figure 2 shows the data from the imaging optical system 100 of Embodiment 1. Note that the values ​​shown in Figure 2 have been rounded.

[0016] Figure 2 shows the following various data. Here, in the various data, the total length of the entire lens system is the distance along the optical axis L from the object-side lens surface 11 of the first lens 10 (La) to the imaging surface of the image sensor 140. The total length between the first lens and the seventh lens is the distance along the optical axis L from the object-side lens surface 11 of the first lens 10 (La) to the image-side lens surface 72 of the seventh lens (Lb).

[0017] The effective focal length (f0) of the entire lens system. Total length of the entire lens system (Total Track: d0) The F-number (Fno) of the entire lens system Maximum half-angle (ω) Pupil Diameter Total length between the 1st lens and the 7th lens (L1R1-L7R2 Track)

[0018] Figure 2 also shows the lens data for each lens listed below. In the lens data, surfaces marked with an asterisk (*) are aspherical. R is the radius of curvature. d is the interplanar spacing. N is the refractive index. v is the Abbe number. f is the focal length. sd is the effective radius. Sag is the sag amount. The units for radius of curvature, interplanar spacing, focal length, effective radius, and sag amount are mm. Figure 2 also shows the aspheric coefficient, which indicates the shape of the aspherical surface for each surface number.

[0019] If the Abbe number of the third lens 30 (second group, first lens) is ν21, the Abbe number of the fourth lens 40 (second group, second lens) is ν22, the focal length of the third lens 30 (second group, first lens) is f3, and the focal length of the fourth lens 40 (second group, second lens) is f4, then the following conditional equation ν21 <30.000 (1) 44.000 < ν22 (2) 0.000 <|f3 / f4|< 0.500 (3) It satisfies the condition. More preferably, condition (1) is the following condition 21.000 < ν21 < 30.000 (1A) It satisfies the condition. More preferably, condition (2) is the following condition 50.000 < ν22 (2A)

[0020] In this form, ν²¹ = 21.621 ν²² = 56.131 f3 = 4.689 f4 = -76.624 Therefore, ν21 = 21.621, satisfying condition (1)(1A). ν22 = 56.131, satisfying condition (2)(2A). |f3 / f4| = 0.061, satisfying condition (3).

[0021] If the imaging optical system 100 has an Abbe number of ν21 for the third lens 30 (second group, first lens), an Abbe number of ν22 for the fourth lens 40 (second group, second lens), a sag amount of the object-side lens surface 71 of the seventh lens 70 (image-side lens) is Sag71, and the effective radius of the object-side lens surface 71 of the seventh lens 70 (image-side lens) is sd71, then the following conditional equation ν21 <30.000 (1) 44.000 < ν22 (2) 0.200 <|Sag71 / sd71|< 0.750 (4) It satisfies the condition. More preferably, condition (1) is the following condition 21.000 < ν21 < 30.000 (1A) It satisfies the condition. More preferably, condition (2) is the following condition 50.000 < ν22 (2A) It satisfies the condition. More preferably, condition (4) is the following condition 0.300 <|Sag71 / sd71|< 0.600 (4A) It satisfies the condition.

[0022] In this form, ν²¹ = 21.621 ν²² = 56.131 Sag71 = 1.081 sd71 = 1.968 Therefore, ν21 = 21.621, satisfying condition (1)(1A). ν22 = 56.131, satisfying condition (2)(2A). |Sag71 / sd71| = 0.550, satisfying condition (4)(4A).

[0023] If the imaging optical system 100 has a sag amount of the object-side lens surface 31 of the third lens 30 (second group first lens) as Sag31, and the effective radius of the object-side lens surface 31 of the third lens 30 (second group first lens) as sd31, then the following conditional equation 0.000 <|Sag31 / sd31|< 0.250 (5) It satisfies the condition.

[0024] In this form, Sag31 = -0.010 sd31 = 1.781 Therefore, |Sag31 / sd31|=0.005, and condition (5) is satisfied.

[0025] If the focal length of the entire lens system of the imaging optical system 100 is f0 and the focal length of the second group 112 is f34, then the following conditional equation 2.000 <f34 / f0< 6.000 (6) It satisfies the condition.

[0026] In this form, f0 = 1.334 f34 = 5.828 Therefore, f34 / f0 = 4.369, which satisfies condition (6).

[0027] If the imaging optical system 100 has a total focal length of f0, the radius of curvature of the object-side lens surface 61 of the sixth lens 60 (object-side lens) is R61, and the radius of curvature of the object-side lens surface 71 of the seventh lens 70 (image-side lens) is R71, then the following conditional equation -10.000 < R61 / f0 < -2.000 (7) 1.000 < R71 / f0 < 2.000 (8) It satisfies the condition.

[0028] In this form, f0 = 1.334 R61 = -6.507 R71 = 1.750 Therefore, R61 / f0 = -4.878, satisfying condition (7). R71 / f0 = 1.312, satisfying condition (8).

[0029] If the imaging optical system 100 has a radius of curvature of the object-side lens surface 61 of the sixth lens 60 (object-side lens) as R61, and a radius of curvature of the image-side lens surface 62 of the sixth lens 60 (object-side lens) as R62, then the following conditional equation 0.000< (R61+R62) / (R61-R62) <1.000 (9) It satisfies the condition.

[0030] In this form, R61 = -6.507 R62 = 1.750 Therefore, (R61+R62) / (R61-R62)=0.576, which satisfies condition (9).

[0031] If the focal length of the entire lens system is f0 and the total length of the entire lens system is d0, then the following conditional equation applies to the imaging optical system 100. 10.000 < d0 / f0 < 15.000 (10) It satisfies the condition.

[0032] In this form, f0 = 1.334 d0 = 16.770 Therefore, d0 / f0 = 12.572, which satisfies condition (10).

[0033] If the radius of curvature of the object-side lens surface 51 of the fifth lens 50 is R51 and the radius of curvature of the image-side lens surface 52 of the fifth lens 50 is R52, then the following conditional equation |R52| < |R51| (11) It satisfies the condition.

[0034] In this form, R51 = 4.990 R52 = -3.750 Therefore, condition (11) is satisfied.

[0035] If the Abbe number of the sixth lens 60 is ν6 and the Abbe number of the seventh lens 70 is ν7, then the following conditional equation applies to the imaging optical system 100. ν6 <30.000 (12) 50.000 < ν7 (13) It satisfies the condition.

[0036] In this form, ν6 = 21.621 ν7 = 56.131 Therefore, ν6 = 21.621, satisfying condition (12). ν7 = 56.131, satisfying condition (13).

[0037] The imaging optical system 100, with respect to the maximum field of view ω, is governed by the following condition: 90 < ω < 120 (14) It satisfies the condition.

[0038] In this form, ω=106 Therefore, condition (14) is satisfied.

[0039] The imaging optical system 100, with T1 being the thickness of the first lens 10 and f0 being the focal length of the entire lens system, is given by the following conditional equation 0.700 < T1 / f0 < 0.900 (15) It satisfies the condition.

[0040] In this form, T1 = 1.000 f0 = 1.334 Therefore, T1 / f0 = 0.750, which satisfies condition (15).

[0041] If the focal length of the entire lens system of the imaging optical system 100 is f0, and the radius of curvature of the object-side lens surface 31 of the third lens 30 (second group first lens) is R31, then the following conditional equation 8.000 <|R31 / f0| (16) It satisfies the condition.

[0042] In this form, f0 = 1.334 R31 = 15.080 Therefore, |R31 / f0|=11.305, which satisfies condition (16).

[0043] The imaging optical system 100, with the entire lens system's focal length being f0 and the cemented lens 75's focal length being f67, is given by the following conditional equation 2.000 < f67 / f0 < 7.000 (17) It satisfies the condition.

[0044] In this form, f0 = 1.334 f67 = 6.701 Therefore, f67 / f0 = 5.024, which satisfies condition (17).

[0045] (Effects and Benefits) The imaging optical system 100 in this configuration satisfies the conditions (1), (1A), (2), (2A), and (3), so chromatic aberration can be well corrected in the third lens 30 and the fourth lens 40. When the conditions (1), (1A), (2), and (2A) are satisfied, if the value of condition (3) exceeds the upper limit, the lens power of the fourth lens 40 becomes too large, making it difficult to well correct chromatic aberration. Here, if the value of condition (1A) falls below the lower limit, chromatic aberration can be well corrected, but the cost of the glass material for the third lens 30 increases.

[0046] The imaging optical system 100 in this embodiment satisfies the conditions (1), (1A), (2), (2A), and (4), so chromatic aberration can be well corrected in the cemented lens 75. When the conditions (1), (1A), (2), and (2A) are satisfied, if the value of condition (4) falls below the lower limit, the lens surfaces 62 and 71, which are the bonding surfaces of the cemented lens 75, approach a planar shape, making it difficult to well correct chromatic aberration in the cemented lens 75. If the value of condition (4) exceeds the upper limit, chromatic aberration can be well corrected in the cemented lens 75, but the sag amount of the lens surfaces 62 and 71 becomes too large relative to the effective radius, so the productivity of the sixth lens 60 and the seventh lens 70 decreases and costs increase. In particular, the seventh lens If the lens surface 71 on the object side La of lens 70 is convex, and the sag amount becomes too large relative to the effective radius, the lens surface 71 will protrude significantly. As a result, when molding the seventh lens with a mold, the time it takes for the resin flowing in from the gate set on the side of the flange portion of the seventh lens 70 to fill up to the top of the lens surface 71 becomes longer. This tends to significantly reduce the productivity of the seventh lens 70.

[0047] The imaging optical system 100 in this embodiment satisfies condition (5), so it can effectively correct various aberrations while suppressing the occurrence of ghosting on the object-side lens surface 31 of the third lens 30. If the value of condition (5) falls below the lower limit, the lens surface 31 becomes flat, making it difficult to effectively correct various aberrations. If the value of condition (5) exceeds the upper limit, ghosting is more likely to occur on the lens surface 31.

[0048] Since the imaging optical system 100 in this embodiment satisfies condition (6), various aberrations can be corrected well.

[0049] The imaging optical system 100 in this embodiment satisfies conditions (7) and (8), so various aberrations can be corrected well. If the value of condition (7) falls below the lower limit, the radius of curvature of the object-side lens surface 61 of the sixth lens 60 becomes too small, making it difficult to correct various aberrations well. If the value of condition (7) exceeds the upper limit, the radius of curvature of the object-side lens surface 61 of the sixth lens 60 becomes too large, reducing the productivity of the sixth lens 60 and increasing costs. If the value of condition (8) falls below the lower limit, the radius of curvature of the object-side lens surface 71 of the seventh lens 70 becomes too large, reducing the productivity of the seventh lens 70 and increasing costs. If the value of condition (8) exceeds the upper limit, the radius of curvature of the object-side lens surface 71 of the seventh lens 70 becomes too small, making it difficult to correct various aberrations well.

[0050] Since the imaging optical system 100 in this embodiment satisfies condition (9), various numerical differences can be corrected effectively.

[0051] The imaging optical system 100 in this configuration satisfies condition (10), thus suppressing an increase in the overall length of the lens system and enabling good correction of various aberrations. If the value of condition (10) falls below the lower limit, it becomes difficult to correct various aberrations well. If the value of condition (10) exceeds the upper limit, each lens element tends to become larger, and the overall length of the lens system also tends to increase.

[0052] The fifth lens 50 is made of glass. Since the imaging optical system 100 of this embodiment satisfies condition (11), even if the adjacent fifth lens 50 at the image side Lb of the aperture 130 is subjected to temperature changes, the deterioration of the optical characteristics of the fifth lens 50 can be suppressed.

[0053] Since the imaging optical system 100 in this configuration satisfies conditions (12) and (13), the cemented lens 75 can effectively correct chromatic aberration.

[0054] Since the imaging optical system 100 of this embodiment satisfies condition (14), the imaging device 200 using the imaging optical system 100 can image a wide area, and the significant decrease in peripheral light intensity relative to central light intensity can be suppressed.

[0055] The imaging optical system 100 in this embodiment satisfies condition (15), so it is possible to ensure the strength of the first lens 10 while suppressing an increase in the overall length of the lens system. If the value of condition (15) falls below the lower limit, the thickness of the first lens 10 becomes too thin, and the strength of the first lens 10 decreases. If the value of condition (15) exceeds the upper limit, the strength of the first lens 10 can be ensured, but the overall length of the lens system tends to increase.

[0056] The imaging optical system 100 in this embodiment satisfies condition (16), thus reducing the production cost of the third lens 30. If the value of condition (16) falls below the lower limit, the radius of curvature of the object-side lens surface 31 of the third lens 30 becomes too large, which reduces the productivity of the third lens 30 and increases its cost.

[0057] The imaging optical system 100 in this configuration satisfies condition (17), thus suppressing an increase in the overall length of the lens system and enabling good correction of various aberrations. If the value of condition (17) falls below the lower limit, it becomes difficult to adequately correct chromatic aberration and distortion in the cemented lens 75. If the value of condition (17) exceeds the upper limit, the overall length of the lens system tends to increase.

[0058] The third lens 30 has positive power. The lens surface 31 on the object side La of the third lens 30 is convex near the optical axis L and concave at the periphery. The lens surface 32 on the image side Lb of the third lens 30 is convex. This allows for good correction of astigmatism and distortion.

[0059] Figure 3 shows the spherical aberration of the imaging optical system 100 shown in Figure 1. Figure 4 shows the lateral chromatic aberration of the imaging optical system 100 shown in Figure 1, showing the lateral chromatic aberration at the maximum half-angle of view. Figure 5 shows the astigmatism and distortion of the imaging optical system 100 shown in Figure 1. Figure 6 shows the lateral aberration of the imaging optical system 100 shown in Figure 1, showing the lateral aberration in the tangential direction (Y direction) and the sagittal direction (X direction).

[0060] Figures 3 to 6 show the aberrations at wavelengths of 486 nm, 546 nm, and 656 nm, denoted by B, G, and R, respectively. For the astigmatism shown in Figure 5, the sagittal characteristic is denoted by S, and the tangential characteristic is denoted by T.

[0061] As shown in Figures 3 to 6, in the imaging optical system 100 of this embodiment, spherical aberration, lateral chromatic aberration, astigmatism (distortion), and lateral aberration are corrected to an appropriate level.

[0062] (Embodiment 2) Figure 7 is an explanatory diagram of the imaging device 200 according to Embodiment 2. As shown in Figure 7, the imaging device 200 of this embodiment includes an imaging optical system 100 and an image sensor 140, similar to Embodiment 1. The front group 110 consists of a first lens 10 and a second lens 20, 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, and a sixth lens 60, in order from the object side La to the image side Lb. The fourth lens 40 and the fifth lens 50 are bonded lenses 75 joined by adhesive. On the image side Lb of the sixth lens 60, 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.

[0063] The front group 110 comprises a first group 111 having negative power and a second group 112 having positive power, arranged in order from the object side La to the image side Lb. The first group 111 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 first lens 10 is made of glass. The first lens 10 has negative power. The first lens 10 has a convex shape on the lens surface 11 on the object side La and a concave shape on the lens surface 12 on the image side Lb. The second lens 20 is made of resin. The second lens 20 has negative power. The second lens 20 has a convex shape on the lens surface 21 on the object side La and a concave shape on the lens surface 22 on the image side Lb. The second lens 20 has aspherical shapes on both sides.

[0064] The second group 112 consists of a third lens 30 (second group first lens) and a fourth lens 40 (second group second lens), arranged in order from the object side La to the image side Lb. The third lens 30 is made of resin. The third lens 30 has positive power. The third lens 30 has a convex shape near the optical axis L and a concave shape at the periphery on the lens surface 31 on the object side La, and a convex shape on the lens surface 32 on the image side Lb. The third lens 30 has aspherical shapes on both sides. The fourth lens 40 is made of resin. The fourth lens 40 has negative power. The fourth lens 40 has a concave shape on the lens surface 41 on the object side La and a convex shape on the lens surface 42 on the image side Lb. The fourth lens 40 has aspherical shapes on both sides.

[0065] The rear group 120 consists of a fifth lens 50 and a cemented lens 75, arranged in order from the object side La to the image side Lb. The cemented lens 75 consists of a sixth lens 60 (object side lens) and a seventh lens 70 (image side lens), arranged in order from the object side La to the image side Lb. The sixth lens 60 and the seventh lens 70 are bonded together by adhesive.

[0066] The fifth lens 50 is made of glass. The fifth lens 50 has positive power. The fifth lens 50 has a convex shape on the lens surface 51 on the object side La and a convex shape on the lens surface 52 on the image side Lb. The sixth lens 60 is made of resin. The sixth lens 60 has negative power. The sixth lens 60 has a concave shape on the lens surface 61 on the object side La and a concave shape on the lens surface 62 on the image side Lb. The sixth lens 60 has aspherical shapes on both sides. The seventh lens 70 is made of resin. The seventh lens 70 has positive power. The seventh lens 70 has a convex shape on the lens surface 71 on the object side La and a convex shape on the lens surface 72 on the image side Lb. The seventh lens 70 has aspherical shapes on both sides.

[0067] (Lens configuration) Figure 8 shows the data from the imaging optical system 100 of Embodiment 2. The imaging optical system 100 of this embodiment satisfies the conditions (1) to (17) described in Embodiment 1. In this form, ν²¹ = 21.621 ν²² = 56.131 f3 = 4.847 f4 = -48.763 Therefore, ν21 = 21.621, satisfying condition (1)(1A). ν22 = 56.131, satisfying condition (2)(2A). |f3 / f4| = 0.099, satisfying condition (3).

[0068] In this form, ν²¹ = 21.621 ν²² = 56.131 Sag71 = 1.063 sd71 = 1.963 Therefore, ν21 = 21.621, satisfying condition (1)(1A). ν22 = 56.131, satisfying condition (2)(2A). |Sag71 / sd71| = 0.542, satisfying condition (4)(4A).

[0069] In this form, Sag31 = -0.012 sd31 = 1.772 Therefore, |Sag31 / sd31|=0.007, and condition (5) is satisfied.

[0070] In this form, f0 = 1.332 f34 = 6.268 Therefore, f34 / f0 = 4.707, which satisfies condition (6).

[0071] In this form, f0 = 1.332 R61 = -6.281 R71 = 1.915 Therefore, R61 / f0 = -4.717, satisfying condition (7). R71 / f0 = 1.438, satisfying condition (8).

[0072] In this form, R61 = -6.281 R62 = 1.915 Therefore, (R61+R62) / (R61-R62)=0.533, which satisfies condition (9).

[0073] In this form, f0 = 1.332 d0 = 16.725 Therefore, d0 / f0 = 12.559, which satisfies condition (10).

[0074] In this form, R51 = 4.380 R52 = -3.640 Therefore, condition (11) is satisfied.

[0075] In this form, ν6 = 21.621 ν7 = 56.131 Therefore, ν6 = 21.621, satisfying condition (12). ν7 = 56.131, satisfying condition (13).

[0076] In this form, ω=106 Therefore, condition (14) is satisfied.

[0077] In this form, T1 = 1.000 f0 = 1.332 Therefore, T1 / f0 = 0.751, which satisfies condition (15).

[0078] In this form, f0 = 1.332 R31 = 15.460 Therefore, |R31 / f0|=11.610, which satisfies condition (16).

[0079] In this form, f0 = 1.332 f67 = 6.607 Therefore, f67 / f0 = 4.961, which satisfies condition (17).

[0080] (Effects and Benefits) The imaging optical system 100 of Embodiment 2 satisfies the same conditions (1) to (17) as in Embodiment 1, and therefore can achieve the same effects as Embodiment 1.

[0081] Figure 9 shows the spherical aberration of the imaging optical system 100 shown in Figure 7. Figure 10 shows the lateral chromatic aberration of the imaging optical system 100 shown in Figure 7. Figure 11 shows the astigmatism and distortion of the imaging optical system 100 shown in Figure 7. Figure 12 shows the lateral aberration of the imaging optical system 100 shown in Figure 7.

[0082] As shown in Figures 9 to 12, 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.

[0083] (Embodiment 3) Figure 13 is an explanatory diagram of an imaging device 200 according to Embodiment 3. As shown in Figure 13, the imaging device 200 of this embodiment includes an imaging optical system 100 and an image sensor 140, similar to Embodiment 1. The front group 110 consists of a first lens 10 and a second lens 20, 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, and a sixth lens 60, in order from the object side La to the image side Lb. The fourth lens 40 and the fifth lens 50 are bonded lenses 75 joined by adhesive. On the image side Lb of the sixth lens 60, 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.

[0084] The front group 110 comprises a first group 111 having negative power and a second group 112 having positive power, arranged in order from the object side La to the image side Lb. The first group 111 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 first lens 10 is made of glass. The first lens 10 has negative power. The first lens 10 has a convex shape on the lens surface 11 on the object side La and a concave shape on the lens surface 12 on the image side Lb. The second lens 20 is made of resin. The second lens 20 has negative power. The second lens 20 has a convex shape on the lens surface 21 on the object side La and a concave shape on the lens surface 22 on the image side Lb. The second lens 20 has aspherical shapes on both sides.

[0085] The second group 112 consists of a third lens 30 (second group first lens) and a fourth lens 40 (second group second lens), arranged in order from the object side La to the image side Lb. The third lens 30 is made of resin. The third lens 30 has positive power. The third lens 30 has a convex shape near the optical axis L and a concave shape at the periphery on the lens surface 31 on the object side La, and a convex shape on the lens surface 32 on the image side Lb. The third lens 30 has aspherical shapes on both sides. The fourth lens 40 is made of resin. The fourth lens 40 has negative power. The fourth lens 40 has a concave shape on the lens surface 41 on the object side La and a convex shape on the lens surface 42 on the image side Lb. The fourth lens 40 has aspherical shapes on both sides.

[0086] The rear group 120 consists of a fifth lens 50 and a cemented lens 75, arranged in order from the object side La to the image side Lb. The cemented lens 75 consists of a sixth lens 60 (object side lens) and a seventh lens 70 (image side lens), arranged in order from the object side La to the image side Lb. The sixth lens 60 and the seventh lens 70 are bonded together by adhesive.

[0087] The fifth lens 50 is made of glass. The fifth lens 50 has positive power. The fifth lens 50 has a convex shape on the lens surface 51 on the object side La and a convex shape on the lens surface 52 on the image side Lb. The sixth lens 60 is made of resin. The sixth lens 60 has negative power. The sixth lens 60 has a concave shape on the lens surface 61 on the object side La and a concave shape on the lens surface 62 on the image side Lb. The sixth lens 60 has aspherical shapes on both sides. The seventh lens 70 is made of resin. The seventh lens 70 has positive power. The seventh lens 70 has a convex shape on the lens surface 71 on the object side La and a convex shape on the lens surface 72 on the image side Lb. The seventh lens 70 has aspherical shapes on both sides.

[0088] (Lens configuration) Figure 14 shows the data from the imaging optical system 100 of Embodiment 3. The imaging optical system 100 of this embodiment satisfies the conditions (1) to (17) described in Embodiment 1. In this form, ν²¹ = 21.621 ν²² = 56.131 f3 = 5.438 f4 = -52.794 Therefore, ν21 = 21.621, satisfying condition (1)(1A). ν22 = 56.131, satisfying condition (2)(2A). |f3 / f4| = 0.103, satisfying condition (3).

[0089] In this form, ν²¹ = 21.621 ν²² = 56.131 Sag71 = 1.065 sd71 = 1.989 Therefore, ν21 = 21.621, satisfying condition (1)(1A). ν22 = 56.131, satisfying condition (2)(2A). |Sag71 / sd71| = 0.536, satisfying condition (4)(4A).

[0090] In this form, Sag31 = -0.081 sd31 = 1.736 Therefore, |Sag31 / sd31|=0.047, and condition (5) is satisfied.

[0091] In this form, f0 = 1.333 f34 = 7.105 Therefore, f34 / f0 = 5.332, which satisfies condition (6).

[0092] In this form, f0 = 1.333 R61 = -6.320 R71 = 1.963 Therefore, R61 / f0 = -4.743, satisfying condition (7). R71 / f0 = 1.473, satisfying condition (8).

[0093] In this form, R61 = -6.320 R62 = 1.963 Therefore, (R61+R62) / (R61-R62)=0.526, which satisfies condition (9).

[0094] In this form, f0 = 1.333 d0 = 16.660 Therefore, d0 / f0 = 12.502, which satisfies condition (10).

[0095] In this form, R51 = 4.313 R52 = -3.691 Therefore, condition (11) is satisfied.

[0096] In this form, ν6 = 21.621 ν7 = 56.131 Therefore, ν6 = 21.621, satisfying condition (12). ν7 = 56.131, satisfying condition (13).

[0097] In this form, ω=106 Therefore, condition (14) is satisfied.

[0098] In this form, T1 = 1.000 f0 = 1.333 Therefore, T1 / f0 = 0.750, which satisfies condition (15).

[0099] In this form, f0 = 1.333 R31 = 72.116 Therefore, |R31 / f0|=54.116, which satisfies condition (16).

[0100] In this form, f0 = 1.333 f67 = 6.430 Therefore, f67 / f0 = 4.825, which satisfies condition (17).

[0101] (Effects and Benefits) The imaging optical system 100 of Embodiment 3 satisfies the same conditions (1) to (17) as in Embodiment 1, and therefore can achieve the same effects as Embodiment 1.

[0102] Figure 15 shows the spherical aberration of the imaging optical system 100 shown in Figure 13. Figure 16 shows the lateral chromatic aberration of the imaging optical system 100 shown in Figure 13. Figure 17 shows the astigmatism and distortion of the imaging optical system 100 shown in Figure 13. Figure 18 shows the lateral aberration of the imaging optical system 100 shown in Figure 13.

[0103] As shown in Figures 15 to 18, 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. It is being done.

[0104] (Embodiment 4) Figure 19 is an explanatory diagram of an imaging device 200 according to Embodiment 4. As shown in Figure 19, the imaging device 200 of this embodiment includes an imaging optical system 100 and an image sensor 140, similar to Embodiment 1. The front group 110 consists of a first lens 10 and a second lens 20, 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, and a sixth lens 60, in order from the object side La to the image side Lb. The fourth lens 40 and the fifth lens 50 are bonded lenses 75 joined by adhesive. On the image side Lb of the sixth lens 60, 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.

[0105] The front group 110 comprises a first group 111 having negative power and a second group 112 having positive power, arranged in order from the object side La to the image side Lb. The first group 111 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 first lens 10 is made of glass. The first lens 10 has negative power. The first lens 10 has a convex shape on the lens surface 11 on the object side La and a concave shape on the lens surface 12 on the image side Lb. The second lens 20 is made of resin. The second lens 20 has negative power. The second lens 20 has a convex shape on the lens surface 21 on the object side La and a concave shape on the lens surface 22 on the image side Lb. The second lens 20 has aspherical shapes on both sides.

[0106] The second group 112 consists of a third lens 30 (second group first lens) and a fourth lens 40 (second group second lens), arranged in order from the object side La to the image side Lb. The third lens 30 is made of resin. The third lens 30 has positive power. The third lens 30 has a convex shape near the optical axis L and a concave shape at the periphery on the lens surface 31 on the object side La, and a convex shape on the lens surface 32 on the image side Lb. The third lens 30 has aspherical shapes on both sides. The fourth lens 40 is made of resin. The fourth lens 40 has negative power. The fourth lens 40 has a concave shape on the lens surface 41 on the object side La and a convex shape on the lens surface 42 on the image side Lb. The fourth lens 40 has aspherical shapes on both sides.

[0107] The rear group 120 consists of a fifth lens 50 and a cemented lens 75, arranged in order from the object side La to the image side Lb. The cemented lens 75 consists of a sixth lens 60 (object side lens) and a seventh lens 70 (image side lens), arranged in order from the object side La to the image side Lb. The sixth lens 60 and the seventh lens 70 are bonded together by adhesive.

[0108] The fifth lens 50 is made of glass. The fifth lens 50 has positive power. The fifth lens 50 has a convex shape on the lens surface 51 on the object side La and a convex shape on the lens surface 52 on the image side Lb. The sixth lens 60 is made of resin. The sixth lens 60 has negative power. The sixth lens 60 has a concave shape on the lens surface 61 on the object side La and a concave shape on the lens surface 62 on the image side Lb. The sixth lens 60 has aspherical shapes on both sides. The seventh lens 70 is made of resin. The seventh lens 70 has positive power. The seventh lens 70 has a convex shape on the lens surface 71 on the object side La and a convex shape on the lens surface 72 on the image side Lb. The seventh lens 70 has aspherical shapes on both sides.

[0109] (Lens configuration) Figure 20 shows the data from the imaging optical system 100 of Embodiment 4. The imaging optical system 100 of this embodiment satisfies the conditions (1) to (17) described in Embodiment 1. In this form, ν²¹ = 21.621 ν²² = 56.131 f3 = 5.632 f4 = -71.657 Therefore, ν21 = 21.621, satisfying condition (1)(1A). ν22 = 56.131, satisfying condition (2)(2A). |f3 / f4| = 0.079, satisfying condition (3).

[0110] In this form, ν²¹ = 21.621 ν²² = 56.131 Sag71 = 1.090 sd71 = 2.023 Therefore, ν21 = 21.621, satisfying condition (1)(1A). ν22 = 56.131, satisfying condition (2)(2A). |Sag71 / sd71| = 0.539, satisfying condition (4)(4A).

[0111] In this form, Sag31 = 0.011 sd31 = 1.729 Therefore, |Sag31 / sd31|=0.006, and condition (5) is satisfied.

[0112] In this form, f0 = 1.314 f34 = 7.237 Therefore, f34 / f0 = 5.507, which satisfies condition (6).

[0113] In this form, f0 = 1.314 R61 = -7.335 R71 = 1.851 Therefore, R61 / f0 = -5.582, satisfying condition (7). R71 / f0 = 1.408, satisfying condition (8).

[0114] In this form, R61 = -7.335 R62 = 1.851 Therefore, (R61+R62) / (R61-R62)=0.597, which satisfies condition (9).

[0115] In this form, f0 = 1.314 d0 = 16.786 Therefore, d0 / f0 = 12.773, which satisfies condition (10).

[0116] In this form, R51 = 4.505 R52 = -3.634 Therefore, condition (11) is satisfied.

[0117] In this form, ν6 = 21.621 ν7 = 56.131 Therefore, ν6 = 21.621, satisfying condition (12). ν7 = 56.131, satisfying condition (13).

[0118] In this form, ω=106 Therefore, condition (14) is satisfied.

[0119] In this form, T1 = 1.000 f0 = 1.314 Therefore, T1 / f0 = 0.761, which satisfies condition (15).

[0120] In this form, f0 = 1.314 R31 = 15.447 Therefore, |R31 / f0|=11.755, which satisfies condition (16).

[0121] In this form, f0 = 1.314 f67 = 5.267 Therefore, f67 / f0 = 4.008, which satisfies condition (17).

[0122] (Effects and Benefits) The imaging optical system 100 of Embodiment 4 satisfies the same conditions (1) to (17) as in Embodiment 1, and therefore can achieve the same effects as Embodiment 1.

[0123] 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.

[0124] 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.

[0125] (Embodiment 5) Figure 25 is an explanatory diagram of an imaging device 200 according to Embodiment 5. As shown in Figure 25, the imaging device 200 of this embodiment includes an imaging optical system 100 and an image sensor 140, similar to Embodiment 1. The front group 110 consists of a first lens 10 and a second lens 20, 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, and a sixth lens 60, in order from the object side La to the image side Lb. The fourth lens 40 and the fifth lens 50 are bonded lenses 75 joined by adhesive. On the image side Lb of the sixth lens 60, 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.

[0126] The first group 110 consists of negative powers, arranged sequentially from the object side La to the image side Lb. The first lens group 111 comprises a first lens 10 and a second lens group 112 having positive power. The first lens group 111 consists of a first lens 10 and a second lens 20, in order from the object side La to the image side Lb. The first lens 10 is made of glass. The first lens 10 has negative power. The first lens 10 has a convex shape on the lens surface 11 on the object side La and a concave shape on the lens surface 12 on the image side Lb. The second lens 20 is made of resin. The second lens 20 has negative power. The second lens 20 has a convex shape on the lens surface 21 on the object side La and a concave shape on the lens surface 22 on the image side Lb. The second lens 20 has aspherical shapes on both sides.

[0127] The second group 112 consists of a third lens 30 (second group first lens) and a fourth lens 40 (second group second lens), arranged in order from the object side La to the image side Lb. The third lens 30 is made of resin. The third lens 30 has positive power. The third lens 30 has a concave shape on the lens surface 31 on the object side La and a convex shape on the lens surface 32 on the image side Lb. The third lens 30 has aspherical shapes on both sides. The fourth lens 40 is made of resin. The fourth lens 40 has negative power. The fourth lens 40 has a concave shape on the lens surface 41 on the object side La and a convex shape on the lens surface 42 on the image side Lb. The fourth lens 40 has aspherical shapes on both sides.

[0128] The rear group 120 consists of a fifth lens 50 and a cemented lens 75, arranged in order from the object side La to the image side Lb. The cemented lens 75 consists of a sixth lens 60 (object side lens) and a seventh lens 70 (image side lens), arranged in order from the object side La to the image side Lb. The sixth lens 60 and the seventh lens 70 are bonded together by adhesive.

[0129] The fifth lens 50 is made of glass. The fifth lens 50 has positive power. The fifth lens 50 has a convex shape on the lens surface 51 on the object side La and a convex shape on the lens surface 52 on the image side Lb. The sixth lens 60 is made of resin. The sixth lens 60 has negative power. The sixth lens 60 has a concave shape on the lens surface 61 on the object side La and a concave shape on the lens surface 62 on the image side Lb. The sixth lens 60 has aspherical shapes on both sides. The seventh lens 70 is made of resin. The seventh lens 70 has positive power. The seventh lens 70 has a convex shape on the lens surface 71 on the object side La and a convex shape on the lens surface 72 on the image side Lb. The seventh lens 70 has aspherical shapes on both sides.

[0130] (Lens configuration) Figure 26 shows the data from the imaging optical system 100 of Embodiment 5. The imaging optical system 100 of this embodiment satisfies the conditions (1) to (16) described in Embodiment 1. In this form, ν²¹ = 21.621 ν²² = 56.131 f3 = 5.509 f4 = 61.760 Therefore, ν21 = 21.621, satisfying condition (1)(1A). ν22 = 56.131, satisfying condition (2)(2A). |f3 / f4| = 0.089, satisfying condition (3).

[0131] In this form, ν²¹ = 21.621 ν²² = 56.131 Sag71 = 1.020 sd71 = 1.992 Therefore, ν21 = 21.621, satisfying condition (1)(1A). ν22 = 56.131, satisfying condition (2)(2A). |Sag71 / sd71| = 0 The result is .512, which satisfies condition (4)(4A).

[0132] In this form, Sag31 = -0.186 sd31 = 1.796 Therefore, |Sag31 / sd31|=0.104, which satisfies condition (5).

[0133] In this form, f0 = 1.417 f34 = 6.261 Therefore, f34 / f0 = 4.419, which satisfies condition (6).

[0134] In this form, f0 = 1.417 R61 = -6.743 R71 = 2.023 Therefore, R61 / f0 = -4.759, satisfying condition (7). R71 / f0 = 1.428, satisfying condition (8).

[0135] In this form, R61 = -6.743 R62 = 2.023 Therefore, (R61+R62) / (R61-R62)=0.538, which satisfies condition (9).

[0136] In this form, f0 = 1.1417 d0 = 16.939 Therefore, d0 / f0 = 11.957, which satisfies condition (10).

[0137] In this form, R51 = 4.343 R52 = -3.884 Therefore, condition (11) is satisfied.

[0138] In this form, ν6 = 21.621 ν7 = 56.219 Therefore, ν6 = 21.621, satisfying condition (12). ν7 = 56.219, satisfying condition (13).

[0139] In this form, ω=108 Therefore, condition (14) is satisfied.

[0140] In this form, T1 = 1.000 f0 = 1.417 Therefore, T1 / f0 = 0.706, which satisfies condition (15).

[0141] In this form, f0 = 1.417 R31 = -46.001 Therefore, |R31 / f0|=32.470, which satisfies condition (16).

[0142] (Effects and Benefits) The imaging optical system 100 of Embodiment 5 satisfies the same conditions (1) to (16) as in Embodiment 1, and therefore can achieve the same effects as Embodiment 1.

[0143] Figure 27 shows the spherical aberration of the imaging optical system 100 shown in Figure 25. Figure 28 shows the lateral chromatic aberration of the imaging optical system 100 shown in Figure 25. Figure 29 shows the astigmatism and distortion of the imaging optical system 100 shown in Figure 25. Figure 30 shows the lateral aberration of the imaging optical system 100 shown in Figure 25.

[0144] As shown in Figures 27 to 30, 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.

[0145] (Embodiment 6) Figure 31 is an explanatory diagram of an imaging device 200 according to Embodiment 6. As shown in Figure 31, the imaging device 200 of this embodiment includes an imaging optical system 100 and an image sensor 140, similar to Embodiment 1. The front group 110 consists of a first lens 10 and a second lens 20, 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, and a sixth lens 60, in order from the object side La to the image side Lb. The fourth lens 40 and the fifth lens 50 are bonded lenses 75 joined by adhesive. On the image side Lb of the sixth lens 60, 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.

[0146] The front group 110 comprises a first group 111 having negative power and a second group 112 having positive power, arranged in order from the object side La to the image side Lb. The first group 111 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 first lens 10 is made of glass. The first lens 10 has negative power. The first lens 10 has a convex shape on the lens surface 11 on the object side La and a concave shape on the lens surface 12 on the image side Lb. The second lens 20 is made of resin. The second lens 20 has negative power. The second lens 20 has a convex shape on the lens surface 21 on the object side La and a concave shape on the lens surface 22 on the image side Lb. The second lens 20 has aspherical shapes on both sides.

[0147] The second group 112 consists of a third lens 30 (second group first lens) and a fourth lens 40 (second group second lens), arranged in order from the object side La to the image side Lb. The third lens 30 is made of resin. The third lens 30 has positive power. The third lens 30 has a concave shape on the lens surface 31 on the object side La and a convex shape on the lens surface 32 on the image side Lb. The third lens 30 has aspherical shapes on both sides. The fourth lens 40 is made of resin. The fourth lens 40 has negative power. The fourth lens 40 has a concave shape on the lens surface 41 on the object side La and a convex shape on the lens surface 42 on the image side Lb. The fourth lens 40 has aspherical shapes on both sides.

[0148] The rear group 120 consists of a fifth lens 50 and a cemented lens 75, arranged in order from the object side La to the image side Lb. The cemented lens 75 consists of a sixth lens, arranged in order from the object side La to the image side Lb. It consists of lens 60 (object-side lens) and lens 70 (image-side lens). Lens 60 and lens 70 are joined together by adhesive.

[0149] The fifth lens 50 is made of glass. The fifth lens 50 has positive power. The fifth lens 50 has a convex shape on the lens surface 51 on the object side La and a convex shape on the lens surface 52 on the image side Lb. The sixth lens 60 is made of resin. The sixth lens 60 has negative power. The sixth lens 60 has a concave shape on the lens surface 61 on the object side La and a concave shape on the lens surface 62 on the image side Lb. The sixth lens 60 has aspherical shapes on both sides. The seventh lens 70 is made of resin. The seventh lens 70 has positive power. The seventh lens 70 has a convex shape on the lens surface 71 on the object side La and a convex shape on the lens surface 72 on the image side Lb. The seventh lens 70 has aspherical shapes on both sides.

[0150] (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 (16) described in Embodiment 1. In this form, ν²¹ = 21.621 ν²² = 56.131 f3 = 5.502 f4 = 63.653 Therefore, ν21 = 21.621, satisfying condition (1)(1A). ν22 = 56.131, satisfying condition (2)(2A). |f3 / f4| = 0.086, satisfying condition (3).

[0151] In this form, ν²¹ = 21.621 ν²² = 56.131 Sag71 = 1.002 sd71 = 1.979 Therefore, ν21 = 21.621, satisfying condition (1)(1A). ν22 = 56.131, satisfying condition (2)(2A). |Sag71 / sd71| = 0.506, satisfying condition (4)(4A).

[0152] In this form, Sag31 = -0.181 sd31 = 1.790 Therefore, |Sag31 / sd31| = 0.101, satisfying the conditional expression (5).

[0153] In this form, f0 = 1.412 f34 = 6.258 Therefore, f34 / f0 = 4.432, satisfying the conditional expression (6).

[0154] In this form, f0 = 1.412 R61 = -6.753 R71 = 2.030 Therefore, R61 / f0 = -4.782, satisfying the conditional expression (7). R71 / f0 = 1.437, satisfying the conditional expression (8).

[0155] In this form, R61 = -6.753 R62 = 2.030 Therefore, (R61 + R62) / (R61 - R62) = 0.538, satisfying the conditional expression (9).

[0156] In this form, f0 = 1.1412 d0 = 16.903 Therefore, d0 / f0 = 11.970, satisfying the conditional expression (10).

[0157] In this form, R51 = 4.342 R52 = -3.882 Therefore, the conditional expression (11) is satisfied.

[0158] In this form, ν6 = 21.621 ν7 = 56.219 Therefore, ν6 = 21.621, satisfying the conditional expression (12). ν7 = 56.219, satisfying the conditional expression (13).

[0159] In this form, ω = 108 That is. Therefore, the conditional expression (14) is satisfied.

[0160] In this embodiment, T1 = 1.000 f0 = 1.412 That is. Therefore, T1 / f0 = 0.708, and the conditional expression (15) is satisfied.

[0161] In this embodiment, f0 = 1.412 R31 = -47.186 That is. Therefore, |R31 / f0| = 33.415, and the conditional expression (16) is satisfied.

[0162] (Function and effect) Similar to Embodiment 1, the imaging optical system 100 of Embodiment 6 satisfies the conditional expressions (1) to (16), and thus can achieve the same effects as those of Embodiment 1.

[0163] FIG. 33 is a diagram showing the spherical aberration of the imaging optical system 100 shown in FIG. 31. FIG. 34 is a diagram showing the longitudinal chromatic aberration of the imaging optical system 100 shown in FIG. 31. FIG. 35 is a diagram showing the astigmatism and distortion of the imaging optical system 100 shown in FIG. 31. FIG. 36 is a diagram showing the lateral aberration of the imaging optical system 100 shown in FIG. 31.

[0164] As shown in FIGS. 33 to 36, in the imaging optical system 100 of this embodiment, the spherical aberration, longitudinal chromatic aberration, astigmatism (distortion), lateral aberration, and resolution are corrected to appropriate levels.

[0165] (Embodiment 7) Figure 37 is an explanatory diagram of the imaging device 200 according to Embodiment 7. As shown in Figure 37, the imaging device 200 of this embodiment includes an imaging optical system 100 and an image sensor 140, similar to Embodiment 1. The front group 110 consists of a first lens 10 and a second lens 20, 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, and a sixth lens 60, in order from the object side La to the image side Lb. The fourth lens 40 and the fifth lens 50 are bonded lenses 75 joined by adhesive. On the image side Lb of the sixth lens 60, 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.

[0166] The front group 110 comprises a first group 111 having negative power and a second group 112 having positive power, arranged in order from the object side La to the image side Lb. The first group 111 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 first lens 10 is made of glass. The first lens 10 has negative power. The first lens 10 has a convex shape on the lens surface 11 on the object side La and a concave shape on the lens surface 12 on the image side Lb. The second lens 20 is made of resin. The second lens 20 has negative power. The second lens 20 has a convex shape on the lens surface 21 on the object side La and a concave shape on the lens surface 22 on the image side Lb. The second lens 20 has aspherical shapes on both sides.

[0167] The second group 112 consists of a third lens 30 (second group first lens) and a fourth lens 40 (second group second lens), arranged in order from the object side La to the image side Lb. The third lens 30 is made of resin. The third lens 30 has positive power. The third lens 30 has a concave shape on the lens surface 31 on the object side La and a convex shape on the lens surface 32 on the image side Lb. The third lens 30 has aspherical shapes on both sides. The fourth lens 40 is made of resin. The fourth lens 40 has negative power. The fourth lens 40 has a concave shape on the lens surface 41 on the object side La and a convex shape on the lens surface 42 on the image side Lb. The fourth lens 40 has aspherical shapes on both sides.

[0168] The rear group 120 consists of a fifth lens 50 and a cemented lens 75, arranged in order from the object side La to the image side Lb. The cemented lens 75 consists of a sixth lens 60 (object side lens) and a seventh lens 70 (image side lens), arranged in order from the object side La to the image side Lb. The sixth lens 60 and the seventh lens 70 are bonded together by adhesive.

[0169] The fifth lens 50 is made of glass. The fifth lens 50 has positive power. The fifth lens 50 has a convex shape on the lens surface 51 on the object side La and a convex shape on the lens surface 52 on the image side Lb. The sixth lens 60 is made of resin. The sixth lens 60 has negative power. The sixth lens 60 has a concave shape on the lens surface 61 on the object side La and a concave shape on the lens surface 62 on the image side Lb. The sixth lens 60 has aspherical shapes on both sides. The seventh lens 70 is made of resin. The seventh lens 70 has positive power. The seventh lens 70 has a convex shape on the lens surface 71 on the object side La and a convex shape on the lens surface 72 on the image side Lb. The seventh lens 70 has aspherical shapes on both sides.

[0170] (Lens configuration) Figure 38 shows the data from the imaging optical system 100 of Embodiment 7. The imaging optical system 100 of this embodiment satisfies the conditions (1) to (15) described in Embodiment 1. In this form, ν²¹ = 23.261 ν²² = 56.219 f3 = 6.807 f4 = 45.666 Therefore, ν21 = 23.261, satisfying the conditional expressions (1) and (1A). ν22 = 56.219, satisfying the conditional expressions (2) and (2A). |f3 / f4| = 0.149, satisfying the conditional expression (3).

[0171] In this embodiment, ν21 = 23.261 ν22 = 56.219 Sag71 = 1.571 sd71 = 2.166 Therefore, ν21 = 23.261, satisfying the conditional expressions (1) and (1A). ν22 = 56.219, satisfying the conditional expressions (2) and (2A). |Sag71 / sd71| = 0.726, satisfying the conditional expression (4).

[0172] In this embodiment, Sag31 = -0.439 sd31 = 1.904 Therefore, |Sag31 / sd31| = 0.231, satisfying the conditional expression (5).

[0173] In this embodiment, f0 = 1.518 f34 = 6.958 Therefore, f34 / f0 = 4.583, satisfying the conditional expression (6).

[0174] In this embodiment, f0 = 1.518 R61 = -12.209 R71 = 1.601 Therefore, R61 / f0 = -8.042, satisfying the conditional expression (7). R71 / f0 = 1.054, satisfying the conditional expression (8). [[ID=5३]]

[0175] In this embodiment, R61 = -12.209 R62 = 1.601 Therefore, (R61+R62) / (R61-R62)=0.768, which satisfies condition (9).

[0176] In this form, f0 = 1.518 d0 = 18.000 Therefore, d0 / f0 = 11.856, which satisfies condition (10).

[0177] In this form, R51 = 5.956 R52 = -4.656 Therefore, condition (11) is satisfied.

[0178] In this form, ν6 = 23.261 ν7 = 56.219 Therefore, ν6 = 23.261, satisfying condition (12). ν7 = 56.219, satisfying condition (13).

[0179] In this form, ω=106 Therefore, condition (14) is satisfied.

[0180] In this form, T1 = 1.000 f0 = 1.518 Therefore, T1 / f0 = 0.659, which satisfies condition (15).

[0181] (Effects and Benefits) The imaging optical system 100 of Embodiment 7 satisfies the same conditions (1) to (15) as in Embodiment 1, and therefore can achieve the same effects as Embodiment 1.

[0182] 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.

[0183] 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.

[0184] Furthermore, this technology can be configured as follows:

[0185] (Note 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 group comprises, in order from the object side to the image side, a first group having negative power and a second group having positive power. The second group comprises a first lens of the second group and a second lens of the second group that is adjacent to the first lens of the second group on the image side and positioned closest to the image side. If the Abbe number of the first lens in the second group is ν21, the Abbe number of the second lens in the second group is ν22, the focal length of the first lens in the second group is f3, and the focal length of the second lens in the second group is f4, then the following conditional expression ν21 <30.000 44.000 < ν22 0.000 <|f3 / f4|< 0.500 An imaging optical system characterized by satisfying the following conditions.

[0186] (Note 2) If we denote the sag amount of the object-side lens surface of the second group's first lens as Sag31, and the effective radius of the object-side lens surface of the second group's first lens as sd31, then the following conditional equation 0.000 <|Sag31 / sd31|< 0.250 The imaging optical system described in Appendix 1, characterized in that it satisfies the requirements.

[0187] (Note 3) If we set the focal length of the entire lens system to f0 and the focal length of the second group to f34, then the following Conditional expression 2.000 <f34 / f0< 6.000 An imaging optical system according to Appendix 1 or 2, characterized in that it satisfies the requirements.

[0188] (Note 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 second group's first lens is R31, then the following conditional equation 8.000 <|R31 / f0| An imaging optical system as described in any one of the appendices 1 to 3, characterized in that it satisfies the following conditions.

[0189] (Note 5) The first lens of the second group has positive power, The object-side lens surface of the second group first lens has a convex shape near the optical axis and a concave shape at the periphery. The imaging optical system according to any one of the appendices 1 to 4, characterized in that the image-side lens surface of the first lens of the second group has a convex shape.

[0190] (Note 6) The imaging optical system according to any one of the appendices 1 to 5, characterized in that the first lens of the second group and the second lens of the second group are made of resin.

[0191] (Note 7) If the focal length of the entire lens system is f0 and the total length of the entire lens system is d0, then the following conditional equation 10.000 < d0 / f0 < 15.000 An imaging optical system as described in any one of the appendices 1 to 6, characterized in that it satisfies the following conditions.

[0192] (Note 8) The first group consists of a first lens and a second lens, arranged in order from the object side towards the image side. The second group consists of, in order from the object side toward the image side, the third lens which is the first lens of the second group, and the fourth lens which is the second lens of the second group. The imaging optical system according to any one of the appendices 1 to 7, characterized in that the rear group consists of a fifth lens, a sixth lens, and a seventh lens in order from the object side to the image side.

[0193] (Note 9) The aforementioned fifth lens is made of glass, If the radius of curvature of the object-side lens surface of the fifth lens is R51, and the radius of curvature of the image-side lens surface of the fifth lens is R52, then the following conditional equation |R52| < |R51| The imaging optical system described in Appendix 8, characterized in that it satisfies the requirements.

[0194] (Note 10) If the Abbe number of the sixth lens is ν6 and the Abbe number of the seventh lens is ν7, then the following conditional expression ν6 <30.000 50.000 < ν7 The imaging optical system according to appendix 8 or 9, characterized in that it satisfies the requirements.

[0195] (Note 11) The imaging optical system described in any one of the appendices 1 to 10, The imaging sensor is positioned on the image side of the aforementioned imaging optical system, An imaging device characterized by comprising: [Explanation of Symbols]

[0196] 10...First lens, 20...Second lens, 30...Third lens, 40...Fourth lens, 50...Fifth lens, 60...Sixth lens, 70...Seventh lens, 75...Cemented lens, 80...Infrared cut filter, 90...Cover, 100...Imaging optical system, 110...Front group, 111...First group, 112...Second group, 120...Rear group, 140...Image sensor, 200...Imaging device, L...Optical axis, La...Object side, Lb...Image side.

Claims

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 group comprises, in order from the object side to the image side, a first group having negative power and a second group having positive power. The second group comprises a first lens of the second group and a second lens of the second group that is adjacent to the first lens of the second group on the image side and is positioned closest to the image side. If the Abbe number of the first lens in the second group is ν21, the Abbe number of the second lens in the second group is ν22, the focal length of the first lens in the second group is f3, and the focal length of the second lens in the second group is f4, then the following conditional equation ν21 <30.000 44.000< ν22 0.000 <|f3 / f4|< 0.500 An imaging optical system characterized by satisfying the following conditions.

2. If we let Sag31 be the sag amount of the object-side lens surface of the second group first lens, and sd31 be the effective radius of the object-side lens surface of the second group first lens, then the following conditional equation 0.000 <|Sag31 / sd31|< 0.250 The imaging optical system according to claim 1, characterized in that it satisfies the requirements.

3. If the focal length of the entire lens system is f0 and the focal length of the second group is f34, then the following conditional equation 2.000 <f34 / f0< 6.000 The imaging optical system according to claim 1 or 2, characterized in that it satisfies the following conditions.

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 second group's first lens is R31, then the following conditional equation 8.000 <|R31 / f0| The imaging optical system according to claim 1, characterized in that it satisfies the requirements.

5. The first lens in the second group has positive power, The object-side lens surface of the second group first lens has a convex shape near the optical axis and a concave shape at the periphery. The imaging optical system according to claim 1, characterized in that the image-side lens surface of the second group first lens is provided with a convex shape.

6. The imaging optical system according to claim 1, characterized in that the first lens of the second group and the second lens of the second group are made of resin.

7. If the focal length of the entire lens system is f0 and the total length of the entire lens system is d0, then the following conditional equation 10.000<d0 / f0<15.000 The imaging optical system according to claim 1, characterized in that it satisfies the requirements.

8. The first group consists of a first lens and a second lens, arranged in order from the object side towards the image side. The second group consists of, in order from the object side toward the image side, the third lens which is the first lens of the second group, and the fourth lens which is the second lens of the second group. The imaging optical system according to claim 1, characterized in that the rear group consists of a fifth lens, a sixth lens, and a seventh lens in order from the object side to the image side.

9. The aforementioned fifth lens is made of glass, If the radius of curvature of the object-side lens surface of the fifth lens is R51, and the radius of curvature of the image-side lens surface of the fifth lens is R52, then the following conditional equation |R52| < |R51| The imaging optical system according to claim 8, which satisfies the requirements.

10. If the Abbe number of the sixth lens is ν6 and the Abbe number of the seventh lens is ν7, then the following conditional expression ν6 < 30.000 50.000 < ν7 The imaging optical system according to claim 8 or 9, characterized in that it satisfies the following conditions.

11. The imaging optical system according to claim 1, The imaging sensor is positioned on the image side of the aforementioned imaging optical system, An imaging device characterized by comprising:

Images