Wide-angle lens

Abstract

The present invention discloses a wide-angle lens, which is composed of a first lens group G1 composed of lenses with an overall negative focal length, a second lens group G2 including an optical element p, a third lens group G3 composed of lenses with a positive focal length within 2 pieces, and a fourth lens group G4 composed of 1 negative focal length lens, in sequence according to the optical path from the object side. The first lens group G1 includes a negative meniscus lens with a convex surface facing the object side. The optical element p is, in sequence according to the optical path, a first optical surface convex to the object side, a second optical surface that bends the optical path of the first optical surface, and a third optical surface concave to the object side. The first optical surface, the second optical surface, and the third optical surface are integrally formed and have more than six aspherical surfaces. The wide-angle lens provided by the present invention has high imaging performance, not only the length of the optical path on the object side is short enough, but also the length of the optical path on the image side is short enough.

Description

Technical Field

[0001] The present invention relates to a small optical system, and more particularly to a wide-angle lens. Background Art

[0002] Small optical systems are shown in Japanese Patent Documents 1 (Japanese Unexamined Patent Application Publication No. 2005-81635) and 2 (Japanese Unexamined Patent Application Publication No. 2005-215165). In such an optical system, the optical path is bent by an optical element disposed in the optical path. As a result, the formed optical path is more likely to form an optical path on the object side (hereinafter referred to as the "object-side optical path") than the optical element, and is more likely to form an optical path on the image side (hereinafter referred to as the "image-side optical path") than the optical element.

[0003] In the above optical system, the length of the object-side optical path is very short, but it cannot be said that the length of the image-side optical path is also very short.

[0004] The present invention has been made in view of such circumstances. That is, an object of the present invention is to provide a wide-angle lens in which not only the object-side optical path is sufficiently short but also the image-side optical path is sufficiently short while having high imaging performance. Summary of the Invention

[0005] In order to solve the above problems and achieve the object, the state of the wide-angle lens of the present invention, in the order of the object-side optical path, is a first lens group having a negative overall focal length, a second lens group including an optical element, a third lens group having a positive overall focal length with 2 or less lens elements, a fourth lens group having 1 negative lens, the first lens group including a meniscus negative lens with the convex surface facing the object side, and the optical element is, in the order of the optical path, a first optical surface convex toward the object side, a second optical surface that bends the optical path of the first optical surface, and a third optical surface concave toward the object side;

[0006] The first optical surface, the second optical surface, and the third optical surface are integrally formed and have six or more aspherical surfaces.

[0007] In order to achieve the above object, in the form of the wide-angle lens of the present invention, the first lens group is composed only of a meniscus negative lens with the convex surface facing the object side.

[0008] In order to achieve the above object, in the form of the wide-angle lens of the present invention, the entire lens is composed of 4 or more aspherical surfaces, and the aspherical surface is a rotationally symmetric aspherical surface.

[0009] In order to achieve the above object, in the form of the wide-angle lens of the present invention, all lenses and optical elements constituting each lens group are plastic products.

[0010] In order to achieve the above object, the form of the wide-angle lens of the present invention satisfies the following condition (1)

[0011] 0.35 < f / (FNo × d2) < 1.0 (1)

[0012] Here, f is the focal length of the entire wide-angle lens, FNo is the F-number of the wide-angle lens, and d2 is the thickness on the optical axis of the entire second lens group.

[0013] To achieve the above object, the wide-angle lens form of the present invention satisfies the following conditions (2) and (3).

[0014] 0.9 < R1 / f < 2.1 (2)

[0015] -1.9 < R2 / f < -0.9 (3)

[0016] Here, R1 is the radius of curvature of the object-side surface of the second lens group, R2 is the radius of curvature of the image-side surface of the second lens group, and f is the focal length of the entire wide-angle lens.

[0017] To achieve the above object, the wide-angle lens form of the present invention satisfies the following condition (4).

[0018] -0.55 < f / fL1 < -0.15 (4)

[0019] Here, f is the focal length of the entire wide-angle lens, and fL1 is the focal length of the first lens group.

[0020] To achieve the above object, the wide-angle lens form of the present invention satisfies the following condition (5).

[0021] -0.80 < f / fL4 < -0.15 (5)

[0022] Here, f is the focal length of the entire wide-angle lens, and fL4 is the focal length of the fourth lens group.

[0023] The present invention has the following beneficial effects compared with the prior art: The wide-angle lens of the present invention has high imaging performance, and not only is the object-side optical path length short enough, but the image-side optical path length can also be made short enough. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a cross-sectional view of the wide-angle lens according to the embodiment of the present invention;

[0025] Figure 2 It is a cross-sectional view of the wide-angle lens according to the first embodiment of the present invention;

[0026] Figure 3 It is a aberration diagram of the wide-angle lens according to the first embodiment of the present invention;

[0027] Figure 4 It is a cross-sectional view of the wide-angle lens according to the second embodiment of the present invention;

[0028] Figure 5 Spherical aberration diagram of the wide-angle lens according to the second embodiment of the present invention;

[0029] Figure 6 Cross-sectional view of the wide-angle lens according to the third embodiment of the present invention;

[0030] Figure 7 Spherical aberration diagram of the wide-angle lens according to the third embodiment of the present invention. Detailed implementation manners

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0032] For the wide-angle lens of this embodiment, in the optical path order on the object side

[0033] The first lens group with a negative total focal length, the second lens group containing optical elements, the third lens group with a positive total focal length and less than 2 lenses, the fourth lens group composed of 1 negative lens. The first lens group includes a meniscus negative lens with a convex surface facing the object side. The optical elements are, in the optical path order, the first optical surface convex towards the object side, the second optical surface that bends the optical path of the first optical surface, and the third optical surface concave towards the object side;

[0034] The first optical surface, the second optical surface and the third optical surface are integrally formed and have more than six aspherical surfaces.

[0035] [[ID=2S]] Figure 1 Cross-sectional view of the wide-angle lens of this embodiment. The wide-angle lens is composed of the first lens group G1, the second lens group G2, the third lens group G3 and the fourth lens group G4. The wide-angle lens of this embodiment forms an optical image of the object at the image I based on the 4 lens groups.

[0036] The first lens group G1 is all composed of lenses with a negative total focal length and includes a meniscus lens with a negative focal length. In the wide-angle lens of this embodiment, the first lens group G1 includes a meniscus lens L1 with a negative focal length and a convex surface facing the object side. Therefore, the first lens group G1 can have a negative focal length.

[0037] The second lens group G2 contains the optical element P. The wide-angle lens of this embodiment is composed of the second lens group G2 with the optical element P.

[0038] The optical element P is composed of the first optical surface r1, the second optical surface r2, and the third optical surface r3 in the optical path order. The first optical surface r1 and the third optical surface r3 play a role in refracting light, and the second optical surface r2 plays a role in reflecting light.

[0039] The second optical surface r2 is a plane with a reflecting surface function. Therefore, the second optical surface r2 can bend the optical path from the first optical surface r1, forming an object-side optical path and an image-side optical path. Since there is only the first lens group G1 on the object side of the optical element p, the length of the object-side optical path can be shortened. At the same time, along the object-side optical path, the thickness of the second lens group G2 can be thinned, enabling the optical system to be made smaller.

[0040] The first optical surface r1 is convex towards the object side, and the third optical surface r3 is concave towards the object side. Therefore, the optical element p can have a positive focal length, and as a result, the second lens group G2 can have a positive focal length.

[0041] Based on the above, the first lens group G1 can have a negative focal length. The second lens group G2 can have a positive focal length, and the order of the focal lengths from the object side is negative focal length and then positive focal length. At this time, an inverse telephoto optical system is formed by the first lens group G1 and the second lens group G2.

[0042] The inverse telephoto optical system has the performance of a wide field of view angle and a long back working distance. The wide-angle lens of this embodiment can easily achieve the performance of a wide field of view angle and a sufficiently long back working distance.

[0043] If the back working distance can be fully ensured, a long space will be formed on the image side of the second lens group G2. Therefore, the third lens group G3 and the fourth lens group G4 can be arranged in this space.

[0044] The third lens group G3 is composed of lenses with a total positive focal length within 2 pieces, and the fourth lens group G4 is composed of 1 negative focal length lens. In this case, since the total number of lenses for the third lens group G3 and the lenses for the fourth lens group G4 is within 3 pieces, the thickness of the third lens group G3 and the thickness of the fourth lens group G4 can be reduced. Since the thickness of the third lens group G3 and the fourth lens group G4 are arranged on the image side of the optical element P, the length of the image-side optical path can be shortened.

[0045] In the wide-angle lens of this embodiment, the third lens group G3 is composed of a biconvex lens L2, and the fourth lens group G4 is composed of a negative meniscus lens L3 with the convex surface facing the image side. Since the total number of lenses for the third lens group G3 and the lenses for the fourth lens group G4 is 2 pieces, the optical path on the image side becomes very short.

[0046] Since a positive focal length lens and a negative focal length lens are arranged on the image side of the second lens group, chromatic aberration can be corrected well. In the wide-angle lens of this embodiment, the biconvex lens L2 and the negative meniscus lens L3 with a negative focal length can correct chromatic aberration well.

[0047] The optical element P can be formed of a colorless transparent material. Glass or resin can be used as the colorless transparent material.

[0048] As described above, in the optical element P, the second optical surface r2 serves as a reflection surface. In the case of using total reflection, the surface of the material can directly serve as the second optical surface r2. In the case where total reflection is not utilized, a reflection film can be formed on the surface of the material, and the reflection film surface can be used as the second optical surface r2.

[0049] The optical element P can be a single unit. In this case, the first optical surface r1, the second optical surface r2, and the third optical surface r3 are integrally formed. Since the three optical surfaces are integrally formed, the eccentricity generated between the first optical surface r1 and the second optical surface r2, the eccentricity generated between the first optical surface r1 and the third optical surface r3, and the eccentricity generated between the second optical surface r2 and the third optical surface r3 can all be suppressed. As a result, a decrease in imaging performance caused by eccentricity can be prevented.

[0050] The wide-angle lens of this embodiment has aspherical surfaces with a total of six or more surfaces. By using six or more aspherical surfaces, high imaging performance can be ensured.

[0051] The aspherical surface can be a rotationally symmetric surface with the optical axis as the rotation axis. By adopting a rotationally symmetric surface, the lens surface can be formed with high precision. As a result, high imaging performance can be ensured. In addition, the manufacturing cost of the optical system can be reduced.

[0052] The aperture stop can be placed between the first lens group G1 and the second lens group G2, or between the second lens group G2 and the third lens group G3.

[0053] In the wide-angle lens of this embodiment, the first lens group is composed only of a meniscus lens with a negative focal length and a convex surface facing the object side.

[0054] Since the first lens group is composed of a meniscus lens, even if the first lens group has a large light refraction, the light refraction can be shared. Therefore, the occurrence of aberration can be suppressed. In addition, in the case of only one meniscus lens, the thickness of the first lens group can be reduced. Therefore, the present invention can manufacture a smaller optical system.

[0055] The wide-angle lens of this embodiment is an aspherical surface that is rotationally symmetric with four or more surfaces.

[0056] By using a rotationally symmetric aspherical surface, high imaging performance can be ensured. The rotationally symmetric aspherical surface can be a surface without an inflection point. In this way, a lens surface with high precision can be obtained. Therefore, the manufacturing cost of the optical system can be reduced.

[0057] In the wide-angle lens of this embodiment, an aspherical surface and a spherical surface can be combined. Two spherical surfaces can be used. From the perspective of manufacturing cost, the aspherical surface is preferably a surface without an inflection point. However, from the perspective of ensuring higher imaging performance, the use of an aspherical surface with an inflection point can be allowed.

[0058] In the wide-angle lens of this embodiment, all lenses and optical elements constituting each lens group are made of plastic.

[0059] Since the lens and optical elements are made of plastic, the weight of the optical system can be reduced, and the manufacturing cost of the optical system can be lowered.

[0060] The wide-angle lens of this embodiment satisfies the following condition (1)

[0061] 0.35 < f / (FNo × d2) < 1.0 (1)

[0062] Here, f is the focal length of the entire wide-angle lens, FNo is the F-number of the wide-angle lens, and d2 is the thickness on the optical axis of the entire second lens group.

[0063] If it is smaller than the lower limit value of condition (1), the size of the entire optical system will become larger. If it is larger than the upper limit value of condition (1), the refraction of the optical path will become difficult.

[0064] The wide-angle lens of this embodiment satisfies the following conditions (2) and (3)

[0065] 0.9 < R1 / f < 2.1 (2)

[0066] -1.9 < R2 / f < -0.9 (3)

[0067] Here, R1 is the radius of curvature of the object side of the second lens group, R2 is the radius of curvature of the image side of the second lens group, and f is the focal length of the entire wide-angle lens.

[0068] If it is smaller than the lower limit value of condition (2), it will be difficult to correct due to large negative spherical aberration. If it is larger than the upper limit value of condition (2), the positive spherical aberration generated by the first lens group cannot be eliminated, so the spherical aberration will deteriorate.

[0069] If it is smaller than the lower limit value of condition (3), it will be difficult to correct due to large spherical aberration. If it is larger than the upper limit value of condition (3), the positive spherical aberration generated by the fourth lens group cannot be eliminated, so the spherical aberration will deteriorate.

[0070] The wide-angle lens of this embodiment satisfies the following condition (4)

[0071] -0.55 < f / fL1 < -0.15 (4)

[0072] Here, f is the focal length of the entire wide-angle lens, and fL1 is the focal length of the first lens group.

[0073] If it is smaller than the lower limit value of condition (4), the spherical aberration deteriorates and the overall length of the optical system becomes longer. This makes correction difficult. If it is larger than the upper limit value of condition (4), the reverse telephoto effect weakens, resulting in deterioration of the image height aberration in a large field of view.

[0074] The wide-angle lens of this embodiment satisfies the following condition (5)

[0075] -0.80 < f / fL4 < -0.15 (5)

[0076] Here, f is the focal length of the entire wide-angle lens, and fL4 is the focal length of the fourth lens group.

[0077] When it is smaller than the lower limit value of condition (5), the balance with the coma generated by the first lens group is broken, resulting in deterioration of the coma. When it is larger than the upper limit value of condition (5), the balance with the coma generated by the first lens group is broken, resulting in deterioration of the coma.

[0078] The embodiments of the wide-angle lens will be described based on the drawings. However, the invention is not limited to these embodiments.

[0079] The aberration diagrams of each embodiment will be described. Figure 3 (a), Figure 5 (a), Figure 7 (a) is a diagram showing spherical aberration. In the spherical aberration diagram, the vertical axis represents the relative incident height, and the horizontal axis represents the aberration amount. In the figure, F represents the F line (wavelength 486 nm), d represents the d line (wavelength 588 nm), and C represents the C line (wavelength 656 nm).

[0080] Figure 3 (b), Figure 5 (b), Figure 7 (b) represents astigmatism. On the astigmatism diagram, the vertical axis represents the principal ray incident angle on the object side (half frame), the horizontal axis represents the aberration amount, the solid line represents the aberration in the meridional plane M, and the dashed line represents the aberration in the sagittal plane S.

[0081] Figure 3 (c), Figure 3 (d), Figure 5 (c), Figure 5 (d), Figure 7 (c), Figure 7 (d) represents the coma at an incident angle of 0°. Figure 3 (c), Figure 5 (c), Figure 7 (c) represents the coma in the meridional plane direction. Figure 3 (d), Figure 5 (d), Figure 7 (d) represents the coma in the sagittal plane direction.

[0082] Figure 3(e), Figure 3 (f), Figure 5 (e), Figure 5 (f), Figure 7 (e), Figure 7 (f) represents the coma when the incident angle is 38°. Figure 3 (e), Figure 5 (e), Figure 7 (e) represents the coma in the meridional plane direction. Figure 3 (f), Figure 5 (f), Figure 7 (f) represents the coma in the sagittal plane direction.

[0083] The vertical axis of the coma diagram represents the aberration amount, and the horizontal axis represents the distance.

[0084] The First Embodiment

[0085] The wide-angle lens of the first embodiment is used Figure 2 and Figure 3 for illustration. Figure 2 is a diagram of the wide-angle lens of the first embodiment made according to the present invention. Figure 3 is an aberration diagram of the wide-angle lens of the first embodiment made according to the present invention.

[0086] The wide-angle lens of the first embodiment is composed of a first lens group G1 with a negative focal length, a second lens group G2 with a positive focal length, a third lens group G3 with a positive focal length, and a fourth lens group G4 with a negative focal length in the optical path order on the object side.

[0087] The first lens group G1 is composed of a meniscus lens L1 with a convex surface facing the object side and a negative focal length, the second lens group G2 is composed of an optical element P, the third lens group G3 is composed of a biconvex lens L2, and the fourth lens group G4 is composed of a meniscus lens L3 with a convex surface facing the image side and a negative focal length.

[0088] The optical element P is made of a resin material. The optical element P has a first optical surface, a second optical surface, and a third optical surface. The first optical surface is represented by r3, the second optical surface is represented by r4, and the third optical surface is represented by r5.

[0089] The second optical surface is a convex surface relative to the object side. The second optical surface is a plane. The third optical surface is a concave surface relative to the object side, and the second optical surface functions as a reflector.

[0090] Aspherical designs are on both sides of the meniscus lens L1, both sides of the biconvex lens L2, and both sides of the meniscus lens L3. All the aspherical surfaces are rotationally symmetric aspherical surfaces.

[0091] The Second Embodiment

[0092] The wide-angle lens of the second embodiment is used Figure 4 andFigure 5 For illustration. Figure 4 It is a wide-angle lens diagram of the second embodiment made according to the present invention. Figure 5 It is an aberration diagram of the wide-angle lens of the second embodiment made according to the present invention.

[0093] The wide-angle lens of the second embodiment is composed of a first lens group G1 with a negative focal length, a second lens group G2 with a positive focal length, a third lens group G3 with a positive focal length, and a fourth lens group G4 with a negative focal length in the optical path order on the object side.

[0094] The first lens group G1 is composed of a meniscus lens L1 with a convex surface facing the object side and a negative focal length. The second lens group G2 is composed of an optical element P. The third lens group G3 is composed of a biconvex lens L2. The fourth lens group G4 is composed of a meniscus lens L3 with a convex surface facing the image side and a negative focal length.

[0095] The optical element P is made of a resin material. The optical element P has a first optical surface, a second optical surface, and a third optical surface. The first optical surface is represented by r3, the second optical surface is represented by r4, and the third optical surface is represented by r5.

[0096] The second optical surface is a convex surface relative to the object side. The second optical surface is a flat surface. The third optical surface is a concave surface relative to the object side, and the second optical surface functions as a reflector.

[0097] Aspherical designs are on both surfaces of the meniscus lens L1, both surfaces of the biconvex lens L2, and both surfaces of the meniscus lens L3. All the aspherical surfaces are rotationally symmetric aspherical surfaces.

[0098] The third embodiment

[0099] The wide-angle lens of the third embodiment is used Figure 6 and Figure 7 For illustration. Figure 6 It is a wide-angle lens diagram of the third embodiment made according to the present invention. Figure 7 It is an aberration diagram of the wide-angle lens of the third embodiment made according to the present invention.

[0100] The wide-angle lens of the third embodiment is composed of a first lens group G1 with a negative focal length, a second lens group G2 with a positive focal length, a third lens group G3 with a positive focal length, and a fourth lens group G4 with a negative focal length in the optical path order on the object side.

[0101] The first lens group G1 is composed of a meniscus lens L1 with a convex surface facing the object side and a negative focal length. The second lens group G2 is composed of an optical element P. The third lens group G3 is composed of a biconvex lens L2 and a biconvex lens L3. The fourth lens group G4 is composed of a meniscus lens L4 with a convex surface facing the image side and a negative focal length.

[0102] The optical element P is made of resin material. The optical element P has a first optical surface, a second optical surface, and a third optical surface. The first optical surface is represented by r3, the second optical surface is represented by r4, and the third optical surface is represented by r5.

[0103] The second optical surface is a convex surface with respect to the object side. The second optical surface is a plane. The third optical surface is a concave surface with respect to the object side, and the second optical surface functions as a reflector.

[0104] The aspherical design is applied to both surfaces of the meniscus lens L1, both surfaces of the biconvex lens L2, both surfaces of the biconvex lens L3, and both surfaces of the meniscus lens L4. All the aspherical surfaces are rotationally symmetric aspherical surfaces.

[0105] The following shows the data of the first embodiment. In the table, the surface number, the radius of curvature (r), the surface interval (d), the refractive index (nd) at a wavelength of 588 nm, and the Abbe number (vd) are represented in order from the left. An asterisk indicates an aspherical surface.

[0106] The radius of curvature r, the surface interval d, and other length units are in mm. However, since the optical system can obtain the same optical performance regardless of scale expansion or scale reduction, the unit is not limited to mm.

[0107] For the shape of the aspherical surface, the height in the direction perpendicular to the optical axis is r, the displacement amount of the height r in the optical axis direction is z(r), the curvature is C, the conic coefficient is k, and the aspherical coefficients are A0, A2, A4, A6, A8, A 10 , …, it is expressed by the following formula:

[0108] z(r) = (cr 2 ) / {1 + [1 - (1 + k)c 2 r 2 1 / 2}

[0109] + A0 + A2r 2 + A4r 4 + A6r 6 + A8r 8 + A 10 r 10 + …

[0110] The coordinate value y in the Y direction, the coordinate value x in the X direction, and r are expressed by the following formula r = (x 2 + y 2} 1 / 2

[0111] The Y direction is the direction orthogonal to the optical axis, and the X direction is the direction orthogonal to both the optical axis direction and the Y direction.

[0112] In addition, among the aspherical coefficients, “E -n ​”(n is an integer) represents "10 -n ”

[0113] Numerical Example 1 Unit: mm

[0114] Surface data

[0115]

[0116]

[0117] Aspherical surface data for the first surface k = 0.000

[0118] A2 = 0.000, A4 = -1.142E -03 , A6 = -1.449E -04 , A8 = -3.122E -05 , A 10 = -7.554E -06

[0119] For the second surface k = 0.000

[0120] A2 = 0.000, A4 = 9.505E -04 , A6 = -1.613E -04 , A8 = 2.222E -04 , A 10 = -7.094E -05

[0121] For the third surface k = -0.015

[0122] A2 = 0.000, A4 = -9.163E -04 , A6 = 3.036E -05 , A8 = 1.092E - 05 , A 10 = -7.252E -06

[0123] For the fifth surface k = -0.013

[0124] A2 = 0.000, A4 = -9.151E -04 , A6 = -6.432E -05 , A8 = -2.004E -07 , A 10 = 1.451E -06

[0125] For the sixth surface k = 0.000

[0126] A2 = 0.000, A4 = -3.856E -04 , A6 = 2.223E -06,A8 = -2.815E -06 ,A 10 = -1.213E -06

[0127] The 7th surface k = 0.000

[0128] A2 = 0.000, A4 = 1.273E -03 A6 = -4.842E -05 ,A8 = -6.390E -06 ,A 10 = 5.598E -07

[0129] The 8th surface k = -0.305

[0130] A2 = 0.000, A4 = -9.492E -04 ,A6 = 1.588E -04 ,A8 = 2.572E -05 ,A 10 = 3.154E -06

[0131] The 9th surface k = 0.000

[0132] A2 = 0.000, A4 = 1.459E -05 ,A6 = 1.345E -07 ,A8 = -2.896E -08 ,A 10 = -5.196E -09

[0133] Various data

[0134] f 3.63mm

[0135] Fno 1.17

[0136] Half field of view 38°

[0137] Numerical example 2 Unit: mm

[0138] Surface data

[0139] Surface number r d nd νd 1* 12.217 0.230 1.53 56.3 2* 3.999 3.239 3* 4.885 2.500 1.53 57.1 4 ∞ 2.551 1.53 57.1 5* -4.934 0.050 6* 5.952 1.984 1.53 57.1 7* -16.639 2.126 8* -3.123 0.200 1.53 30.0 9* -30.474 0.337 Image plane ∞

[0140] Aspherical surface data The 1st surface k = 0.000

[0141] A2 = 0.000, A4 = 2.619E -04 ,A6 = 1.540E -05 ,A8 = 8.507E -06 ,A 10 = 5.916E -08,A 12 =-2.389E -08

[0142] The second surface k = 0.061

[0143] A2 = 0.000, A4 = -2.581E -04 , A6 = -4.353E -05 , A8 = 5.451E -06 , A 10 = 3.076E -06 , A 12 = 5.267E -08

[0144] The third surface k = -3.981E-03

[0145] A2 = 0.000, A4 = -3.463E -03 , A6 = -2.546E -04 , A8 = -1.673E -05 , A 10 = -2.546E -07 , A 12 = 2.474E -07

[0146] The fifth surface k = 0.000

[0147] A2 = 0.000, A4 = 4.113E -04 , A6 = -1.708E -04 , A8 = -2.565E -05 , A 10 = 8.466E -08 , A 12 = 1.321E -06

[0148] The sixth surface k = 0.000

[0149] A2 = 0.000, A4 = -1.013E -03 , A6 = 7.391E -04 , A8 = -1.597E -04 , A 10 = -3.815E -05 , A 12 = 1.202E -05

[0150] The seventh surface k = 0.000

[0151] A2 = 0.000, A4 = 3.056E -03 , A6 = -2.937E-04 , A8 = -7.596E -05 , A 10 = -3.376E -06 , A 12 = 4.252E -06

[0152] The 8th surface k = 0.842

[0153] A2 = 0.000, A4 = -8.148E -03 , A6 = -2.056E -04 , A8 = 5.995E -05 , A 10 = 2.333E -05 , A 12 = 6.343E -06

[0154] The 9th surface k = 0.000

[0155] A2 = 0.000, A4 = 7.904E -03 , A6 = -1.777E -03 , A8 = 4.417E -05 , A 10 = 2.590E -05 , A 12 = -2.600E -06

[0156] Various data

[0157] f 3.63mm

[0158] Fno 1.17

[0159] Half field of view angle 38°

[0160] Numerical example 3 Unit mm

[0161] Surface data

[0162] Surface number r d nd νd 1* 11.488 0.220 1.59 29.9 2* 4.433 1.527 3* 5.010 2.090 1.53 56.3 4 ∞ 2.100 1.53 56.3 5* -3.760 0.042 6* 6.892 1.000 1.53 57.1 7* -15.705 0.024 8* 8.549 1.047 1.53 57.1 9* -7.953 1.241 10* -3.915 0.160 1.59 29.9 11* -80.000 0.339 Image plane ∞

[0163] Aspherical data The 1st surface k = 0.000

[0164] A2 = -6.800E -03 , A4 = 2.866E -03 , A6 = 7.730E -05 , A8 = 7.123E -06 , A 10 = 6.031E -07 , A 12 = 2.634E -08

[0165] The second side, k = 0.000

[0166] A2 = 1.055E -03 , A4 = -1.805E -03 , A6 = -2.578E -05 , A8 = 2.924E -05 , A 10 = 1.280E -06 , A 12 = -5.736E -07

[0167] The third side

[0168] k = -12.648

[0169] A2 = -3.775E -03 , A4 = -5.179E -03 , A6 = -1.526E -03 , A8 = -3.977E -04 , A 10 = -3.727E -05 , A 12 = 2.297E -05

[0170] The fifth side, k = -1.584

[0171] A2 = -2.705E -03 , A4 = -1.024E -03 , A6 = -1.380E -04 , A8 = 4.881E -06 , A 10 = 1.706E -05 , A 12 = 1.073E -05

[0172] The sixth side, k = 0.000

[0173] A2 = 6.710E -06 , A4 = -5.063E -05 , A6 = 8.607E -06 , A8 = 1.040E -05 , A 10 = 2.369E -06 , A 12 = -1.259E -06

[0174] The seventh side, k = 0.000

[0175] A2 = -7.865E -03 , A4 = -4.201E -03 , A6 = -5.913E -04 , A8 = -6.098E -05 , A 10 = -7.227E -06 , A 12 = -2.020E -06

[0176] The 8th surface k = 0.000

[0177] A2 = 1.689E -05 , A4 = -1.348E -04 , A6 = 1.128E -04 , A8 = 1.191E -06 , A 10 = -1.150E -05 , A 12 = 2.256E -06

[0178] The 9th surface k = 0.000

[0179] A2 = -2.033E -05 , A4 = 3.278E -04 , A6 = -7.891E -05 , A8 = -2.396E -05 , A 10 = -4.442E -07 , A 12 = 1.758E -06

[0180] The 10th surface k = 0.661

[0181] A2 = -0.160, A4 = -0.037, A6 = 7.012E -03 , A8 = 4.418E -05 , A 10 = -1.821E -04 , A 12 = 3.993E -06

[0182] The 11th surface k = 0.0001

[0183] A2 = 9.563E -05 , A4 = 5.880E -05 , A6 = 5.524E -05 , A8 = 4.167E -06 , A 10 = -4.528E-09 , A 12 = -1.678E -07

[0184] Various data f 2.88mm

[0185] Fno 1.11

[0186] Half field of view angle 45°

[0187] The values of each parameter are described as follows:

[0188] First embodiment Second embodiment Third embodiment f 3.63 3.63 2.88 FNo 1.17 1.17 1.11 d2 4.890 5.051 4.190 R1 3.799 4.885 5.010 R2 -4.818 -4.934 -3.760 fL1 -11.40 -11.30 -11.17 fL4 -4.421 -6.528 -3.032

[0189] The values of each parameter are described as follows

[0190] First embodiment Second embodiment Third embodiment (1) 0.6346 0.6143 0.6193 (2) 1.0466 1.3457 1.7396 (3) -1.3272 -1.3592 -1.3056 (4) -0.3185 -0.3212 -0.2578 (5) -0.8211 -0.5561 -0.9499

[0191] The above is the description of the embodiments of the present invention. However, the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of this theme.

[0192]

Industrial Applicability

[0193] The present invention is applicable to a wide-angle lens that has high imaging performance and in which not only the length of the object-side optical path but also the length of the image-side optical path is sufficiently short.

[0194]

Explanation of Symbols

[0195] G1 The first lens group

[0196] G2 The second lens group

[0197] G3 The third lens group

[0198] G4 The fourth lens group

[0199] L1, L2, L3, L4 Lenses

[0200] P Optical element

[0201] r1 The first optical surface

[0202] r2 The second optical surface

[0203] r3 The third optical surface

[0204] I Image plane

[0205] Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications and improvements without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be defined by the claims.

Claims

1. A wide-angle lens, characterized in that, It is configured in the following order of optical path from the object side: A first lens group composed of lenses with a negative overall focal length; A second lens group containing optical elements; A third lens group composed of no more than 2 lenses with a positive overall focal length, and A fourth lens group composed of 1 lens with a negative focal length; The first lens group includes a meniscus negative lens with its convex surface facing the object side, and the optical elements are, in the order of optical path, a first optical surface with its convex surface facing the object side, a second optical surface that bends the optical path of the first optical surface, and a third optical surface with its concave surface facing the object side; The first optical surface, the second optical surface, and the third optical surface are integrally formed and have more than six aspherical surfaces; Satisfy the following conditional formula (1); 0.35 < f / (FNo×d2) < 1.0(1) Here, f is the focal length of the entire wide-angle lens, FNo is the F-number of the wide-angle lens, and d2 is the thickness on the entire optical axis of the second lens group.

2. The wide-angle lens according to claim 1, characterized in that, The first lens group is composed only of a meniscus negative lens with its convex surface facing the object side.

3. The wide-angle lens according to claim 2, wherein, The entire lens is composed of more than 4 aspherical surfaces, and the aspherical surfaces are rotationally symmetric aspherical surfaces.

4. The wide-angle lens according to claim 1, wherein, All lenses and optical elements of each lens group are plastic products.

5. The wide-angle lens according to any one of claims 1-4, characterized in that , satisfy the following conditional formulas (2) and (3); 0.9 < R1 / f < 2.1(2) -1.9 < R2 / f < -0.9(3) Here, R1 is the radius of curvature of the surface on the object side of the second lens group, R2 is the radius of curvature of the surface on the image side of the second lens group, and f is the focal length of the entire wide-angle lens.

6. The wide-angle lens according to any one of claims 1-4, characterized in that, Satisfy the following condition (4); -0.55 < f / fL1 < -0.15(4) Here, f is the overall focal length of the wide-angle lens, and fL1 is the focal length of the first lens group.

7. The wide-angle lens according to any one of claims 1 to 4, characterized in that, Satisfy the following condition (5); -0.80 < f / fL4 < -0.15(5) Here, f is the overall focal length of the wide-angle lens, and fL4 is the focal length of the fourth lens group.

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