JP2009151046A - Imaging lens and imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact and low-cost imaging lens having a long back focal length and a small F number while maintaining favorable optical performance in a wide wavelength range from a visible region to a near-infrared region. <P>SOLUTION: The imaging lens includes a negative first lens L1 disposed on a most object side, having a concave surface directed toward the object side and having a meniscus shape, a cemented lens LC disposed on a most image side and having a convex surface on its most object side and a diaphragm disposed just in front of the object side of the cemented lens. The imaging lens satisfies following conditional expressions (1): 0.05<(R2-R1)/(R1+R2)<0.25, and (2): νd1-νd2>15, wherein R1 is a radius of curvature of an object side surface of the first lens; R2 is a radius of curvature of an image side surface of the first lens; νd1 is an Abbe number of the lens, which is located on the most object side among lenses constituting the cemented lens, at a d-line; and νd2 is an Abbe number of the lens, which is located on the most image side among the lenses constituting the cemented lens, at the d-line. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an imaging lens and an imaging apparatus, and more particularly, to an in-vehicle camera, a mobile terminal camera, a surveillance camera, and the like using an imaging element such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS). The present invention relates to an imaging lens suitable for the imaging, and an imaging device including the imaging lens.

  In recent years, image sensors such as CCDs and CMOSs have been greatly reduced in size and pixels. At the same time, the image pickup device body including these image pickup devices is also downsized, and the image pickup lens mounted thereon is also required to be downsized and light.

  On the other hand, in-vehicle cameras, surveillance cameras, and the like, there is a demand for inexpensive and high-performance lenses that can be used in a wide temperature range while having high weather resistance from the outside air in a cold region to the interior of a tropical summer car.

In Patent Document 1, in order from the object side, a meniscus positive first lens having a convex surface facing the object side, a positive second lens, a negative third lens, a diaphragm, and a negative fourth lens And a medium telephoto lens in which a cemented lens of a positive fifth lens is arranged. Patent Document 2 discloses, in order from the object side, a first lens group including three meniscus positive lenses having a convex surface facing the object side, and a second lens group including meniscus negative lenses. A medium telephoto lens is described in which a diaphragm, a third lens group composed of a cemented lens of a negative lens and a positive lens, and a fourth lens group composed of one or more positive lenses are arranged.
JP-A-11-271610 JP-A-5-224119

  In-vehicle cameras and surveillance cameras are used throughout the day and night, and in particular, in-vehicle cameras shoot with visible light in the daytime and near infrared light at night, so a wide wavelength range from the visible to the near infrared range. An optical system corresponding to the area is required. In addition, a bright optical system with a large aperture ratio is required to support shooting at low illuminance. Furthermore, in view of disposing a cover glass, a filter, or the like between the lens system and the image sensor, an optical system with a long back focus is preferable.

  However, although the mid-telephoto lenses described in Patent Documents 1 and 2 consider aberration correction in the visible region, performance in the near infrared region is not guaranteed. Moreover, the thing of patent document 1 is a dark optical system whose F value is about 4, and is unsuitable for use at night. Since the number of lenses described in Patent Document 2 is as large as 7 to 8, the optical system becomes large and expensive, and since an aspheric lens is used, the required accuracy during processing and assembly is high. It becomes severe and leads to cost increase after all.

  In view of the above circumstances, the present invention provides a small and inexpensive imaging lens having a long back focus and a small F number while maintaining good optical performance in a wide wavelength range from the visible range to the near infrared range, and An object of the present invention is to provide an imaging device including an imaging lens.

The first imaging lens of the present invention has a meniscus negative first lens disposed closest to the object side and having a concave surface facing the object side, and the most object-side surface disposed closest to the image side. It has a cemented lens and a stop arranged immediately before the object side of the cemented lens, and satisfies the following conditional expression.
0.05 <(R2-R1) / (R1 + R2) <0.25 (1)
νd1-νd2> 15 (2)
However,
R1: radius of curvature of the object-side surface of the first lens R2: radius of curvature of the image-side surface of the first lens νd1: Abbe relative to the d-line of the most object-side lens among the lenses constituting the cemented lens closest to the image side Number νd2: Abbe number with respect to d-line of the most image side lens among the lenses constituting the most image side cemented lens

  Here, “immediately before” of the “aperture disposed immediately before the object side of the cemented lens” does not mean a distance, but another optical element exists between the cemented lens and the aperture. It means not entering.

  Here, when the first lens is an aspheric lens, paraxial curvature radii are used as R1 and R2 in the conditional expression (1).

  In the first imaging lens of the present invention, a negative meniscus first lens disposed closest to the object side and having a concave surface facing the object side makes it easy to obtain a bright optical system having a long back focus and a small F value. By defining the negative power of the first lens so as to satisfy the conditional expression (1), it becomes easy to achieve both long back focus and good correction of various aberrations. In the first imaging lens of the present invention, the cemented lens is disposed closest to the image side, and the dispersion characteristic of the material of the cemented lens is defined so as to satisfy the conditional expression (2). It becomes easy to achieve both suppression of point aberration and good correction of lateral chromatic aberration in a wide wavelength range. By adopting the above configuration, it is possible to obtain a compact and high-performance optical system without necessarily using an aspheric lens.

  At this time, in the first imaging lens of the present invention, it can be configured such that all lenses constituting the cemented lens closest to the image side are positive lenses.

  The second imaging lens of the present invention includes, in order from the object side, a meniscus negative first lens having a concave surface facing the object side, a positive second lens having a convex surface facing the object side, and a convex surface facing the object side. Positive meniscus third lens with a convex surface, a negative fourth meniscus lens with a convex surface facing the object side, a stop, a positive fifth lens with a convex surface facing the object side, and a positive sixth lens And a cemented lens made of a lens.

  In the second imaging lens of the present invention, the negative meniscus first lens disposed closest to the object side and having the concave surface facing the object side makes it easy to obtain a bright optical system having a long back focus and a small F value. In the second imaging lens of the present invention, the cemented lens is disposed closest to the image side, and the configuration of each lens of the first to sixth lenses, such as the configuration of the power and the like, is suitably set as described above. In addition, it is easy to achieve both suppression of coma and astigmatism and good correction of lateral chromatic aberration in a wide wavelength range, and it becomes possible to obtain a compact and high-performance optical system without necessarily using an aspheric lens. .

Here, in the first and second imaging lenses of the present invention, it is preferable that the following conditional expression is satisfied.
0.10 <(R2-R1) / (R1 + R2) <0.20 (1-1)
However,
R1: radius of curvature of object side surface of first lens R2: radius of curvature of image side surface of first lens

  In the first and second imaging lenses of the present invention, the absolute value of the radius of curvature of each surface of the cemented lens closest to the image side may be configured to increase from the object side toward the image side. Good.

  In the first and second imaging lenses of the present invention, it is preferable that the refractive index of all lenses in the entire system with respect to the d line is greater than 1.75, and further, with respect to the d lines of all lenses in the entire system. More preferably, the refractive index is greater than 1.8.

In the first and second imaging lenses of the present invention, it is preferable that the following conditional expression is satisfied.
νd1-νd2> 20 (2-1)
However,
νd1: Abbe number for the d-line of the most object side lens among the lenses constituting the most image side cemented lens νd2: Abbe number for the d line of the most image side lens among the lenses constituting the most image side cemented lens

  Each value of the conditional expression is based on the e-line (wavelength 546.07 nm) as a reference wavelength. In this specification, the e-line is a reference wavelength unless otherwise specified.

  An image pickup apparatus of the present invention includes the above-described image pickup lens of the present invention and an image pickup element that converts an optical image formed by the image pickup lens into an electric signal.

  According to the present invention, since the configuration of the shape, power, etc. of each lens is suitably set, a long back focus and a small size are maintained while maintaining good optical performance in a wide wavelength range from the visible range to the near infrared range. It is possible to provide an imaging lens having an F value, which is small and inexpensive, and an imaging apparatus including the imaging lens.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, an embodiment of the imaging lens of the present invention will be described, and then an embodiment of the imaging device will be described.

  FIG. 1 shows a lens cross-sectional view of an imaging lens 1 according to an embodiment of the present invention. FIG. 1 also shows the outermost peripheral ray 2 of the axial ray, the principal ray 3 of the off-axis ray, and the outermost peripheral ray 4 of the off-axis ray. The configuration example shown in FIG. 1 corresponds to the lens configuration of Example 1 described later shown in FIG. FIGS. 3 to 7 show lens cross-sectional views of other configuration examples of the imaging lens according to the embodiment of the present invention, and these correspond to the lens configurations of Examples 2 to 6 described later. . Since the basic lens configurations of the imaging lenses of Examples 1 to 6 are the same, the imaging lens 1 having the configuration example shown in FIG. 1 will be described below as an imaging lens according to an embodiment of the present invention.

  The imaging lens 1 has, in order from the object side, a meniscus negative first lens L1 with a concave surface facing the object side, a positive second lens L2 with a convex surface facing the object side, and a convex surface facing the object side. Meniscus positive third lens L3, meniscus negative fourth lens L4 with a convex surface facing the object side, aperture stop St, positive fifth lens L5 with a convex surface facing the object side, and positive A cemented lens LC composed of a sixth lens L6 is arranged.

  Note that the aperture stop St in FIG. 1 does not indicate the shape or size, but indicates the position on the optical axis Z. In FIG. 1, the imaging element 5 disposed on the image plane including the imaging position Pim of the imaging lens is also illustrated in consideration of the case where the imaging lens 1 is applied to the imaging device. The image pickup device 5 converts an optical image formed by the image pickup lens into an electric signal, and includes, for example, a CCD image sensor.

  Although not shown in FIG. 1, when the imaging lens 1 is applied to an imaging device, a cover glass or a low-pass is provided between the imaging lens 1 and the imaging element 5 according to the configuration of the camera side on which the lens is mounted. It is preferable to arrange various filters such as a filter, an infrared cut filter, and an ultraviolet cut filter. For example, when this imaging lens is used in an in-vehicle camera and used as a night vision camera for visual assistance at night, a filter that cuts blue light from ultraviolet light between the lens system and the imaging device Is preferably inserted. The imaging lens 1 is an optical system having a long back focus so that such a cover glass, a filter, and the like are arranged with sufficient margin and can be adjusted at the time of mounting.

  In the imaging lens 1, the first lens L1 disposed closest to the object side is a negative meniscus lens having a concave surface facing the object side, which makes it easy to ensure a long back focus, It becomes easy to obtain a bright optical system having a small F value.

The imaging lens 1 preferably satisfies the following conditional expression (1).
0.05 <(R2-R1) / (R1 + R2) <0.25 (1)
However, R1 is a curvature radius of the object side surface of the first lens L1, and R2 is a curvature radius of the image side surface of the first lens L1.

  Conditional expression (1) defines a preferable range regarding the negative power of the first lens L1 arranged closest to the object side. Exceeding the lower limit of conditional expression (1) makes it difficult to ensure a long back focus, correct longitudinal chromatic aberration, and correct curvature of field. If the upper limit of conditional expression (1) is exceeded, the field curvature and lateral chromatic aberration cannot be corrected.

It is more preferable that the imaging lens 1 further satisfies the following conditional expression (1-1).
0.10 <(R2-R1) / (R1 + R2) <0.20 (1-1)
Furthermore, satisfying conditional expression (1-1) makes it easier to ensure a long back focus, to correct longitudinal chromatic aberration, to correct field curvature, and to correct lateral chromatic aberration.

In the imaging lens 1, it is preferable that the most image side cemented lens LC satisfies the following conditional expression (2).
νd1-νd2> 15 (2)
Where νd1 is the Abbe number with respect to the d-line of the most object side lens among the lenses constituting the most image side cemented lens LC, and νd2 is the most image side of the lenses constituting the most image side cemented lens LC. This is the Abbe number for the d-line of the lens.

  Conditional expression (2) defines a preferable range of the dispersion characteristic of the material of the cemented lens arranged closest to the image side. By satisfying conditional expression (2), it becomes easy to satisfactorily correct lateral chromatic aberration while suppressing coma and astigmatism.

It is more preferable that the imaging lens 1 further satisfies the following conditional expression (2-1).
νd1-νd2> 20 (2-1)
Furthermore, satisfying conditional expression (2-1) makes it easier to satisfactorily correct lateral chromatic aberration while suppressing coma and astigmatism.

  Further, in the cemented lens LC closest to the image side, it is preferable that the absolute value of the radius of curvature of each surface increases as it goes from the object side to the image side, and the imaging lens 1 shown in FIG. It is configured. With this configuration, it is possible to ensure a long back focus and to maintain good curvature of field while balancing axial chromatic aberration and chromatic aberration of magnification.

  If the object side surface of the fifth lens L5, which is the most object side surface of the cemented lens LC, is configured to have a convex surface facing the object side, it is advantageous in terms of aberration correction.

  The cemented surface of the cemented lens LC of the imaging lens 1 shown in FIG. 1 has a center of curvature on the image side. Also in the imaging lenses of Examples 2 to 6 to be described later, this cemented surface has a center of curvature on the image side (sign of curvature radius is positive) or has a center of curvature on the object side (sign of curvature radius). Is negative) has a small curvature. According to such a configuration, the incident angle of off-axis rays with respect to the cemented surface is increased, and the lateral chromatic aberration can be effectively corrected.

  Even if the curvature of the cemented surface of the cemented lens LC is not increased, in an optical system having a small F value, such as the present imaging lens 1, the angle formed by the outer peripheral ray of the axial ray and the cemented surface increases. Upper chromatic aberration can also be corrected effectively.

  In the imaging lens 1, the cemented lens LC is obtained by cementing two positive lenses (fifth lens L5 and sixth lens L6). In this way, the imaging lens of the present invention can be configured such that all the cemented lenses arranged closest to the image side are positive lenses. Such a configuration is advantageous for correcting chromatic aberration and curvature of field while taking a long back focus.

  Such a configuration of the cemented lens LC made of a positive lens is preferable from the viewpoint of ghost prevention and ghost reduction. If the most image side lens is a negative lens, the most image side lens surface (hereinafter referred to as the final surface) of the entire system becomes a concave surface having a large curvature, and the light reflected by the imaging element 5 is again reflected on the final surface. There is a possibility that the light is reflected and condensed again on the image pickup device 5 to become a strong flare, that is, a ghost. On the other hand, in the present imaging lens 1, by making the most image side lens a positive lens, the final surface can be a convex surface or a concave surface having a small curvature, and is reflected by the imaging device 5 and reflected on the final surface. It is possible to prevent the flare light reflected again from being condensed at high density on the image sensor 5.

  The first lens L1 to the sixth lens L6 constituting the imaging lens 1 have negative, positive, positive, negative, positive, and positive power arrangement in order from the object side, and are long in the negative first lens L1. After expanding the incident light beam so as to have back focus, the light beam is gradually converged by the positive second and third lenses L2 and L3, and the positive and negative aberrations are once balanced by the negative fourth lens L4. Thereafter, the light beams are converged and imaged by the positive fifth and sixth lenses L5 and L6. In addition, the imaging lens 1 can reduce the overall aberration generation amount by using many meniscus lenses that generate less aberration than the biconvex shape or the biconcave shape, and particularly suppresses coma and astigmatism well. Thus, high optical performance can be realized while ensuring a small F value.

  Further, the third lens L3, the fourth lens L4, and the fifth lens L5 arranged adjacent to each other have a meniscus shape having a convex surface facing the object side, a meniscus shape having a convex surface facing the object side, and a convex surface facing the object side. By setting the shape to be directed, it becomes possible to arrange these lenses with a close interval between the lenses, which can contribute to downsizing.

  In the imaging lens according to the present embodiment, it is preferable that the refractive index with respect to the d-line of all the lenses constituting the entire system is greater than 1.75, and further, the refractive index with respect to the d-line of all these lenses is 1.8. Larger is preferred. In order to reduce the size, it is preferable that the power of each lens is large. However, if the radius of curvature of the surface is decreased to increase the power, it becomes difficult to correct various aberrations including chromatic aberration. In order to increase the power without reducing the radius of curvature of the surface, a material having a high refractive index may be employed as described above, and thereby miniaturization can be achieved while suppressing various aberrations.

  When this imaging lens is used in a harsh environment such as an in-vehicle camera, the lens placed closest to the object is resistant to surface deterioration due to wind and rain, temperature changes due to direct sunlight, and oils and detergents. It is preferable to use materials that are resistant to chemicals such as water resistance, weather resistance, acid resistance, and chemical resistance.

  Further, it is preferable to use a hard and hard-to-break material as the lens disposed closest to the object side. Specifically, it is preferable to use glass or transparent ceramics. Ceramics have properties of higher strength and higher heat resistance than ordinary glass.

  Further, when this imaging lens is applied to, for example, a vehicle-mounted camera, it is required that the imaging lens can be used in a wide temperature range from the outside air in a cold region to the interior of a tropical summer vehicle. When used in a wide temperature range, it is preferable to use a lens having a small linear expansion coefficient. In order to manufacture lenses at low cost, it is preferable that all the lenses are spherical lenses.

  Next, specific numerical examples of the imaging lens according to the present invention will be described. First, the first embodiment will be described as an example. FIG. 2 shows a lens configuration diagram of the imaging lens according to Example 1, and Table 1 shows lens data.

  In the lens data of Table 1, Si indicates the i-th (i = 1, 2, 3,...) Surface number that sequentially increases toward the image side with the most object-side component surface being first, and Ri is The radius of curvature of the i-th surface is indicated, Di indicates the surface interval on the optical axis Z between the i-th surface and the i + 1-th surface, and Ndj is the optical element closest to the object side as the first, and as it moves toward the image side. The refractive index with respect to the d-line of the j-th (j = 1, 2, 3,...) Optical element that increases sequentially, and νdj represents the Abbe number with respect to the d-line of the j-th optical element. In Table 1, the unit of the radius of curvature and the surface interval is mm, and the radius of curvature is positive when convex on the object side and negative when convex on the image side. The lens data in Table 1 also includes the aperture stop St.

  3 to 7 are lens configuration diagrams of imaging lenses according to Examples 2 to 6, and Tables 2 to 6 are lens data. 2 to 7 also show the imaging element 5 arranged on the image plane including the imaging position Pim, and the illustrated aperture stop St does not represent the shape or size but is on the optical axis Z. Is shown. In each embodiment, Ri and Di (i = 1, 2, 3,...) In the lens data table correspond to the symbols Ri and Di in the lens configuration diagram.

  Table 7 shows various data in the imaging lenses of Examples 1 to 6. In Table 7, the focal length is the focal length of the entire system, f5 is the focal length of the fifth lens L5, f6 is the focal length of the sixth lens L6, and (R2-R1) / (R2 + R1) is a condition. It is a value corresponding to Expression (1), νd1−νd2 is a value corresponding to Conditional Expression (2), and Ndmin is the minimum value of the refractive index of d-line in the entire lens system. In Table 7, the unit of focal length, back focus, f5 and f6 is mm, and the unit of total angle of view is degree. As can be seen from Table 7, Examples 1 to 6 satisfy all the conditional expressions (1) and (2).

  Aberration diagrams of spherical aberration, astigmatism, distortion (distortion aberration), and lateral chromatic aberration of the imaging lenses according to Examples 1 to 6 are shown in FIGS. Each aberration diagram shows an aberration with the e-line (wavelength 546.07 nm) as a reference wavelength, and the spherical aberration diagram and the lateral chromatic aberration diagram show the g-line (wavelength 435.83 nm) and C-line (wavelength 656.3 nm). ) And s-line (wavelength 852.11 nm) are also shown. The distortion diagram shows the amount of deviation from the ideal image height f × tan θ using the focal length f and half angle of view θ (variable treatment, 0 ≦ θ ≦ ω) of the entire system. FNo. Is an F value, and ω in other aberration diagrams represents a half angle of view.

  As can be seen from the above data, in Examples 1 to 6, although the F value is a small value of 1.40 to 1.46, each aberration is good over a wide wavelength band from the visible range to the near infrared range. It has been corrected. Moreover, the said Examples 1-6 have a long back focus which can insert a filter etc. easily, and are comprised small. Furthermore, since the first to sixth embodiments are all composed of spherical lenses without using any aspheric surfaces, they can be manufactured at low cost. Such an imaging lens of Examples 1-6 can be used suitably for the vehicle-mounted camera etc. for image | photographing images, such as the front of a motor vehicle, a side, and the back.

  As a usage example, FIG. 14 shows a state in which the imaging lens and the imaging apparatus of the present embodiment are mounted on the automobile 100. In FIG. 14, an automobile 100 includes an in-vehicle camera 101 for imaging a blind spot range on the side surface on the passenger seat side, an in-vehicle camera 102 for imaging a blind spot range on the rear side of the automobile 100, and a rear surface of a rearview mirror. An in-vehicle camera 103 is attached and is used for photographing the same field of view as the driver. The outside camera 101, the outside camera 102, and the inside camera 103 are imaging devices, and include an imaging lens 1 according to an embodiment of the present invention and an imaging element 5 that converts an optical image formed by the imaging lens 1 into an electrical signal. I have.

  As described above, the imaging lens 1 according to the embodiment of the present invention is configured to have a small F value and a small size while maintaining good optical performance in a wide wavelength range from the visible range to the near infrared range, Since it can be manufactured at low cost, the outside cameras 101 and 102 and the inside camera 103 can also be made small and inexpensive, and the imaging surface of the imaging device 5 is bright and good over a wide wavelength band from the visible range to the near infrared range. An image can be formed.

  The present invention has been described with reference to the embodiment and examples. However, the present invention is not limited to the above embodiment and example, and various modifications can be made. For example, the values of the radius of curvature, the surface interval, and the refractive index of each lens component are not limited to the values shown in the above numerical examples, but can take other values.

  Further, in the embodiment of the imaging apparatus, the example in which the present invention is applied to a vehicle-mounted camera has been described with reference to the drawings. However, the present invention is not limited to this application, and for example, a mobile terminal camera or a surveillance camera The present invention can also be applied.

1 is an optical path diagram of an imaging lens according to an embodiment of the present invention. Sectional drawing which shows the lens structure of the imaging lens concerning Example 1 of this invention. Sectional drawing which shows the lens structure of the imaging lens concerning Example 2 of this invention. Sectional drawing which shows the lens structure of the imaging lens concerning Example 3 of this invention. Sectional drawing which shows the lens structure of the imaging lens concerning Example 4 of this invention. Sectional drawing which shows the lens structure of the imaging lens concerning Example 5 of this invention. Sectional drawing which shows the lens structure of the imaging lens concerning Example 6 of this invention. Each aberration diagram of the imaging lens according to Example 1 of the present invention Each aberration diagram of the imaging lens according to Example 2 of the present invention Each aberration diagram of the imaging lens according to Example 3 of the present invention Each aberration diagram of the imaging lens according to Example 4 of the present invention Each aberration diagram of the imaging lens according to Example 5 of the present invention Each aberration diagram of the imaging lens according to Example 6 of the present invention The figure for demonstrating arrangement | positioning of the vehicle-mounted imaging device concerning embodiment of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Imaging lens 2 Outermost peripheral ray of on-axis ray 3 Main ray of off-axis ray 4 Outermost ray of off-axis ray 5 Imaging device 100 Automobile 101, 102 Out-of-vehicle camera 103 In-vehicle camera Di i-th surface and i + 1-th surface The surface interval on the optical axis Pim imaging position L1 1st lens L2 2nd lens L3 3rd lens L4 4th lens L5 5th lens L6 6th lens LC cemented lens Ri Radius of curvature St Aperture stop Z optical axis

Claims (9)

A meniscus negative first lens disposed closest to the object side and having a concave surface facing the object side; a cemented lens disposed closest to the image side and having a convex surface on the most object side; and the object side of the cemented lens An imaging lens comprising: a diaphragm disposed immediately before the lens, and satisfying the following conditional expression:
0.05 <(R2-R1) / (R1 + R2) <0.25 (1)
νd1-νd2> 15 (2)
However,
R1: radius of curvature of the object-side surface of the first lens R2: radius of curvature of the image-side surface of the first lens νd1: Abbe number νd2 for the d-line of the lens closest to the object among the lenses constituting the cemented lens: Abbe number for the d-line of the most image side lens among the lenses constituting the cemented lens   The imaging lens according to claim 1, wherein all lenses constituting the cemented lens are positive lenses.   In order from the object side, a negative first meniscus lens having a concave surface facing the object side, a positive second lens having a convex surface facing the object side, and a positive third meniscus shape having a convex surface facing the object side A lens, a meniscus negative fourth lens with a convex surface facing the object side, a stop, and a cemented lens made up of a positive fifth lens and a positive sixth lens with a convex surface facing the object side An imaging lens characterized by. The imaging lens according to claim 1, wherein the following conditional expression is satisfied.
0.10 <(R2-R1) / (R1 + R2) <0.20 (1-1)
However,
R1: radius of curvature of object side surface of first lens R2: radius of curvature of image side surface of first lens   5. The imaging lens according to claim 1, wherein the cemented lens is configured such that an absolute value of a radius of curvature of each surface increases from an object side toward an image side. 6. .   The imaging lens according to any one of claims 1 to 5, wherein the refractive index with respect to d-line of all the lenses is greater than 1.75.   The imaging lens according to any one of claims 1 to 5, wherein the refractive index of all lenses with respect to d-line is greater than 1.8. The imaging lens according to claim 1, wherein the following conditional expression is satisfied.
νd1-νd2> 20 (2-1)
However,
νd1: Abbe number for the d-line of the lens closest to the object among the lenses constituting the cemented lens νd2: Abbe number for the d-line of the lens closest to the image among the lenses constituting the cemented lens The imaging lens according to any one of claims 1 to 8,
An imaging device comprising: an imaging element that converts an optical image formed by the imaging lens into an electrical signal.

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