Wide-angle photographic lens

Abstract

The embodiment of the invention discloses a wide-angle photographic lens. The wide-angle photographic lens comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens which are sequentially arranged from an object plane to an image plane along an optical axis; the first lens has positive focal power, the second lens has positive focal power, the third lens has negative focal power, the fourth lens has negative focal power, the fifth lens has positive focal power, and the sixth lens has positive focal power. According to the embodiment of the invention, a traditional double-Gaussian symmetric optical system is constructed or approximately constructed, so that the light trend and the refraction angle of the object side space and the image side space are symmetric, and through the matching of the focal power of the lenses which are symmetric front and back, the reasonable air interval adjustment of different lenses and the optimization of the aperture of the lenses, the resolution of the lenses is improved. On one hand, aberration can be effectively corrected, small distortion, small chromatic aberration and low field curvature can be achieved, and on the other hand, the front-back length of the whole lens can be compressed, and the size of the whole lens can be reduced.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of optical lenses, and in particular to a wide-angle photography lens. Background Art

[0002] With the rapid development of photography technology, photographic lenses play an important role in landscape photography, portrait photography, and image art. Due to the influence of their applicable scenarios and artistic nature, these lenses are required to have a wide field of view, low distortion, minimal field curvature, minimal chromatic aberration, a compact size, and low cost.

[0003] Currently, lenses on the market often struggle to strike a balance between these performance indicators. For example, higher-definition lenses often exhibit greater distortion, distorting portraits or scenery. Alternatively, even when designed to meet aberration standards, the lenses can be bulky and expensive. Furthermore, even when distortion is met, high curvature of field can make focusing at the edges and center of the image difficult. Therefore, developing a high-definition photography lens that meets all the required design specifications is crucial. Summary of the Invention

[0004] The present invention provides a wide-angle photographic lens, which aims to realize a lens solution with half-frame target surface, wide angle, small distortion, short volume and low-cost manufacturing, and achieves technical indicators of -0.5% ≤ optical distortion ≤ 2.5%; 50° ≤ diagonal field of view ≤ 60°.

[0005] An embodiment of the present invention provides a wide-angle photography lens, comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens arranged in sequence along an optical axis from an object plane to an image plane;

[0006] The first lens has positive optical power, the second lens has positive optical power, the third lens has negative optical power, the fourth lens has negative optical power, the fifth lens has positive optical power, and the sixth lens has positive optical power.

[0007] Optionally, the first lens to the sixth lens meet the following conditions:

[0008] 0.668<Φ1 / Φ<0.935;

[0009] 1.009<Φ2 / Φ<1.410;

[0010] -1.875<Φ3 / Φ<-1.492;

[0011] -1.664<Φ4 / Φ<-1.434;

[0012] 1.172<Φ5 / Φ<1.703;

[0013] 0.413<Φ6 / Φ<0.958;

[0014] Among them, Φ1 is the optical focal length of the first lens, Φ2 is the optical focal length of the second lens, Φ3 is the optical focal length of the third lens, Φ4 is the optical focal length of the fourth lens, Φ5 is the optical focal length of the fifth lens, Φ6 is the optical focal length of the sixth lens, and Φ is the optical focal length of the wide-angle photography lens.

[0015] Optionally, the first lens satisfies the following condition: -1.2456≤(C1-C2) / (C1+C2)≤-0.2976;

[0016] Wherein, C1 is the curvature of the object-side surface of the first lens, and C2 is the curvature of the image-side surface of the first lens.

[0017] Optionally, the first lens to the sixth lens meet the following conditions:

[0018] 0.5649<Φ1_3 / Φ<0.6487;

[0019] 0.7450<Φ4_6 / Φ<1.0982;

[0020] Wherein, Φ1_3 is the optical focal length of the lens group consisting of the first lens, the second lens and the third lens; Φ4_6 is the optical focal length of the lens group consisting of the fourth lens, the fifth lens and the sixth lens.

[0021] Optionally, the object-side surface of the first lens is convex, and the image-side surface is concave;

[0022] The object side surface of the second lens is convex, and the image side surface is concave;

[0023] The object side surface of the third lens is convex, and the image side surface is concave;

[0024] The object-side surface of the sixth lens is concave, and the image-side surface is concave.

[0025] Optionally, the first lens is an aspherical glass lens, and the second lens to the sixth lens are all spherical glass lenses.

[0026] Optionally, the first lens meets the following conditions:

[0027] -1.204 <K1<-0.174;

[0028] -3.982 <K2<-0.354;

[0029] Wherein, K1 is the cone coefficient of the object-side surface of the first lens, and K2 is the cone coefficient of the image-side surface of the first lens.

[0030] Optionally, the fourth lens and the fifth lens meet the following conditions:

[0031] -1.1840≤1000*(Φ4 / VD4+Φ5 / VD5)≤0.421;

[0032] Wherein, Φ4 is the optical power of the fourth lens, Φ5 is the optical power of the fifth lens; VD4 is the Abbe number of the fourth lens, and VD5 is the Abbe number of the fifth lens.

[0033] Optionally, the fourth lens and the fifth lens meet the following conditions:

[0034] 26.4781 <VD4<40.8475;

[0035] 33.3090 <VD5<40.8475。

[0036] Optionally, the wide-angle camera lens meets the following conditions: 1.1785 <TTL / f<1.2890;

[0037] Wherein, TTL is the total optical length of the wide-angle photography lens, and f is the focal length of the wide-angle photography lens.

[0038] The technical solution of the embodiment of the present invention is to provide a wide-angle photography lens including a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens arranged in sequence along the optical axis from the object plane to the image plane; the first lens has a positive optical power, the second lens has a positive optical power, the third lens has a negative optical power, the fourth lens has a negative optical power, the fifth lens has a positive optical power, and the sixth lens has a positive optical power. The purpose is to set the optical powers of the first three lenses and the rear three lenses of the lens to be symmetrical or approximately symmetrical, thereby constructing or approximately constructing a traditional double-Gauss symmetrical optical system. This can make the light paths and refraction angles on the object side and image side space symmetrical. The coordination of the optical powers of the front-to-back symmetrical lenses, combined with the reasonable adjustment of the air spacing between different lens components and the optimization of the lens aperture, not only helps to effectively correct aberrations and achieve low distortion, low chromatic aberration, and low field curvature, but also helps to compress the front-to-back length of the entire lens and reduce the overall lens volume. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 1 is a schematic structural diagram of a wide-angle photographic lens provided in Embodiment 1 of the present invention;

[0040] Figure 2 yes Figure 1 The resolution MTF curve of the wide-angle photographic lens shown in the figure;

[0041] Figure 3 yes Figure 1Spherical aberration curve of the wide-angle photography lens shown;

[0042] Figure 4 yes Figure 1 Chromatic aberration diagram of the wide-angle photography lens shown;

[0043] Figure 5 yes Figure 1 The field curvature distortion diagram of the wide-angle photography lens shown;

[0044] Figure 6 1 is a schematic structural diagram of a wide-angle photographic lens provided by Embodiment 2 of the present invention;

[0045] Figure 7 yes Figure 5 The resolution MTF curve of the wide-angle photographic lens shown in the figure;

[0046] Figure 8 yes Figure 5 Spherical aberration curve of the wide-angle photography lens shown;

[0047] Figure 9 yes Figure 5 Chromatic aberration diagram of the wide-angle photography lens shown;

[0048] Figure 10 yes Figure 5 The field curvature distortion diagram of the wide-angle photography lens shown;

[0049] Figure 11 1 is a schematic structural diagram of a wide-angle photographic lens provided by Embodiment 3 of the present invention;

[0050] Figure 12 yes Figure 11 The resolution MTF curve of the wide-angle photographic lens shown in the figure;

[0051] Figure 13 yes Figure 11 Spherical aberration curve of the wide-angle photography lens shown;

[0052] Figure 14 yes Figure 11 Chromatic aberration diagram of the wide-angle photography lens shown;

[0053] Figure 15 yes Figure 11 The field curvature distortion diagram of the wide-angle photography lens shown. DETAILED DESCRIPTION

[0054] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It will be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all structures.

[0055] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. It should be noted that the directional words such as "upper", "lower", "left", and "right" described in the embodiments of the present invention are described based on the angles shown in the accompanying drawings and should not be understood as limiting the embodiments of the present invention. In addition, in the context, it is also necessary to understand that when it is mentioned that an element is formed "on" or "under" another element, it can not only be formed directly "on" or "under" another element, but can also be formed indirectly "on" or "under" another element through an intermediate element. The terms "first", "second", etc. are only used for descriptive purposes and do not indicate any order, quantity or importance, but are only used to distinguish different components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0056] The term "including" and its variations used in the present invention are open inclusions, that is, "including but not limited to." The term "based on" means "based at least in part on." The term "one embodiment" means "at least one embodiment."

[0057] It should be noted that the concepts such as "first" and "second" mentioned in the present invention are only used to distinguish the corresponding contents, and are not used to limit the order or mutual dependence.

[0058] It should be noted that the modifications of "one" and "multiple" mentioned in the present invention are illustrative rather than restrictive. Those skilled in the art should understand that unless otherwise clearly indicated in the context, it should be understood as "one or more".

[0059] Figure 1 This is a schematic diagram of the structure of a wide-angle photographic lens provided by the first embodiment of the present invention, with reference to Figure 1 The wide-angle camera lens includes a first lens 10, a second lens 20, a third lens 30, a fourth lens 40, a fifth lens 50, and a sixth lens 60, which are arranged in sequence along the optical axis from the object plane to the image plane. The first lens 10 has positive optical power, the second lens 20 has positive optical power, the third lens 30 has negative optical power, the fourth lens 40 has negative optical power, the fifth lens 50 has positive optical power, and the sixth lens 60 has positive optical power.

[0060] First of all, for optical lenses, the focal length is equal to the difference between the convergence of the image-side beam and the convergence of the object-side beam, which characterizes the ability of the optical system to deflect light. The larger the absolute value of the focal length, the stronger the ability to bend light, and the smaller the absolute value of the focal length, the weaker the ability to bend light. When the focal length is a positive number, the refraction of light is convergent; when the focal length is a negative number, the refraction of light is divergent. The focal length can be used to characterize a certain refractive surface of a lens (i.e., a surface of a lens), can be used to characterize a certain lens, and can also be used to characterize a system formed by multiple lenses (i.e., a lens group).

[0061] In the photographic lens provided in this embodiment, each lens can be fixed to a lens barrel ( Figure 1 (not shown) in the Figure 1 As shown, the lens also includes an aperture 70, which can be positioned between the third lens element 30 and the fourth lens element 40. In this embodiment, the aperture 70 can be specifically positioned on the object-side surface of the fourth lens element 40. In this embodiment of the present invention, the focal powers of the six lenses are sequentially set to positive, positive, negative, negative, positive, and positive, and the aperture 70 is positioned between the third and fourth lenses. This aims to establish a symmetrical or nearly symmetrical relationship between the focal powers of the first three lenses and the last three lenses of the lens, thereby forming or approximately forming a traditional double-Gaussian symmetrical optical system. Those skilled in the art will appreciate that a traditional double-Gaussian symmetrical optical system, due to its symmetrical relationship, can achieve symmetrical light paths and refraction angles on the object and image sides. This allows for effective aberration correction, achieving minimal distortion, chromatic aberration, and field curvature, by combining the focal powers of the front-to-back symmetrical lenses, along with appropriate air spacing adjustment between the different lens elements and optimized lens apertures. Furthermore, it helps to reduce the overall length and overall size of the lens.

[0062] In a specific embodiment, optionally, the first lens 10 to the sixth lens 60 satisfy the following conditions: 0.668<Φ1 / Φ<0.935; 1.009<Φ2 / Φ<1.410; -1.875<Φ3 / Φ<-1.492; -1.664<Φ4 / Φ<-1.434; 1.172<Φ5 / Φ<1.703; 0.413<Φ6 / Φ<0.958; wherein Φ1 is the optical power of the first lens 10, Φ2 is the optical power of the second lens 20, Φ3 is the optical power of the third lens 30, Φ4 is the optical power of the fourth lens 40, Φ5 is the optical power of the fifth lens 50, Φ6 is the optical power of the sixth lens 60, and Φ is the optical power of the wide-angle photography lens.

[0063] In this embodiment, by limiting the optical power ratio of each lens to the entire lens and adjusting the optical power range of each lens, it is possible to further ensure that the entire lens is closer to a traditional double-Gaussian symmetrical optical system, thereby optimizing the aberration correction effect and enabling the wide-angle camera lens to achieve the characteristics of small distortion, small chromatic aberration and low field curvature.

[0064] Further optionally, the first lens element 10 satisfies the following condition: -1.2456≤(C1-C2) / (C1+C2)≤-0.2976; wherein C1 is the curvature of the object-side surface of the first lens element 10, and C2 is the curvature of the image-side surface of the first lens element 10.

[0065] In this embodiment, the curvatures of the object-side and image-side surfaces of the first lens 10 are restricted to satisfy the above relationship. In essence, the surface shape of the first lens 10 is further restricted while the first lens 10 satisfies the positive optical power condition, so that the first lens 10 can receive more incident light, increase the field of view, and realize the wide-angle characteristic of the lens.

[0066] Further optionally, the first lens 10 to the sixth lens 60 satisfy the following conditions: 0.5649<Φ1_3 / Φ<0.6487; 0.7450<Φ4_6 / Φ<1.0982; wherein Φ1_3 is the optical focal length of the lens group consisting of the first lens 10, the second lens 20, and the third lens 30; and Φ4_6 is the optical focal length of the lens group consisting of the fourth lens 40, the fifth lens 50, and the sixth lens 60.

[0067] In this embodiment, the optical power ratio of the lens group before and after the aperture 70 to the entire lens is limited, and the optical power range of the lens group is adjusted to further ensure that the entire lens is closer to a traditional double-Gaussian symmetrical optical system, so that the optical distortion and other field aberrations of the lens can be effectively suppressed, which is beneficial to reducing the incident angle of light, reducing the sensitivity of the lens, reducing distortion and field area, etc., optimizing the aberration correction effect, and enabling the wide-angle camera lens to achieve the characteristics of small distortion, small chromatic aberration and low field curvature.

[0068] In a specific embodiment, the object-side surface of the first lens 10 is optionally convex, and the image-side surface is concave; the object-side surface of the second lens 20 is optionally convex, and the image-side surface is concave; the object-side surface of the third lens 30 is optionally convex, and the image-side surface is concave; and the object-side surface of the sixth lens 60 is optionally concave, and the image-side surface is concave. More specifically, in an embodiment of the present invention, the opposing surfaces of the fourth lens 40 and the fifth lens 50 may be cemented together to form a cemented lens group.

[0069] In this embodiment, by designing the surface profiles of the above-mentioned lenses, in essence, the three lenses before and after the diaphragm 70, especially the first lens 10 and the sixth lens 60, are set to be symmetric or approximately symmetric shapes. Thereby, the light path and refraction angle in the object space and the image space can be controlled to have a symmetric or approximately symmetric effect, ensuring that this lens can achieve a traditional double-Gauss symmetric optical system. Specifically, by restricting the first lens 10, the second lens 20, and the third lens 30 to satisfy the above-mentioned surface profiles, when the bending direction of the lens is beneficial for the lens with a smaller aperture, it can collect light with a larger field angle, reflecting the function of reducing the volume of the lens. At the same time, it reduces the height of light propagation inside the lens, reduces aberration, and realizes the characteristics of small volume, wide angle, and small aberration. The sixth lens 60 is the last lens of the lens. This lens is a positive lens, mainly used to converge light, control the back focal distance, and play a role in reducing the total length of the lens. Meeting the above requirements is also beneficial for the flat filter to have sufficient installation space. In addition, the fourth lens 40 and the fifth lens 50 are combined into a cemented lens group, which can not only reduce the distance between the lenses, be beneficial for reducing the overall volume of the lens, but also appropriately correct chromatic aberration, improve field curvature and coma, thereby further optimizing and correcting the imaging quality.

[0070] Furthermore, in the embodiment of the present invention, the first lens 10 is an aspherical glass lens, and the second lens 20 to the sixth lens 60 are all spherical glass lenses.

[0071] Among them, by restricting all six lenses to be glass lenses, the characteristics of the glass material can be utilized to reduce the sensitivity of imaging to temperature, reduce the deformation degree of the lens at different temperatures, and ensure clear imaging in high and low temperature environments. And by designing the remaining five lenses except the first lens 10 to be spherical glass lenses, on the basis that the lens only has six lenses in total and has a low material cost, the processing difficulty of the glass lens can be reduced, and the processing cost can be reduced, which is beneficial for reducing the manufacturing cost and realizing mass production.

[0072] Still further, the first lens 10 satisfies the following conditions: -1.204 < K1 < -0.174; -3.982 < K2 < -0.354; where K1 is the conic coefficient of the object side surface of the first lens 10, and K2 is the conic coefficient of the image side surface of the first lens 10.

[0073] As described above, in the embodiments of the present invention, the first lens 10 can be designed as an aspherical lens. On this basis, K1 and K2 are the conic coefficients of the aspherical object-side surface and the image-side surface respectively. The conic coefficient affects the resolution of the optical system. The adjustment of this coefficient is the key to optimizing the imaging quality. By restricting the object side and the image side of the first lens 10 to satisfy the above relationship ranges respectively, the layout of the optical system can be optimized. Inserting an aspherical lens at the position of the first lens can utilize the characteristic that different apertures of the aspherical surface have different curvature values, and when the light rays in different fields of view are relatively separated, the effects of correcting field aberrations such as distortion and field curvature can be achieved.

[0074] In a specific embodiment, optionally, the fourth lens 40 and the fifth lens 50 satisfy the following conditions: -1.1840 ≤ 1000*(Φ4 / VD4 + Φ5 / VD5) ≤ 0.421; where, Φ4 is the optical power of the fourth lens 40, Φ5 is the optical power of the fifth lens 50; VD4 is the Abbe number of the fourth lens 40, and VD5 is the Abbe number of the fifth lens 50. More specifically, the fourth lens 40 and the fifth lens 50 can be set to satisfy the following conditions: 26.4781 < VD4 < 40.8475; 33.3090 < VD5 < 40.8475.

[0075] Among them, the Abbe constant represents the index of the dispersion ability of the medium. The larger the Abbe constant, the lighter the dispersion. In this embodiment, according to the achromatic formula of the positive and negative optical power doublet lens, restricting the fourth lens 40 and the fifth lens 50 to satisfy the above optical power and Abbe number ranges is beneficial to the correction of axial chromatic aberration and lateral chromatic aberration, and higher resolution and better imaging performance can be obtained.

[0076] In a specific embodiment, optionally, the wide-angle photographic lens satisfies the following conditions: 1.1785 < TTL / f < 1.2890; where, TTL is the total optical length of the wide-angle photographic lens, and f is the focal length of the wide-angle photographic lens.

[0077] For the wide-angle lens in the embodiments of the present invention, the value of TTL / f is the retrofocus ratio. This value is usually greater than 1, indicating that the principal plane of the lens is inside the lens, and the focal plane of the lens is usually close to the image plane. When the lens satisfies the above proportional numerical requirements, the principal plane of the lens can be moved closer to the front end of the lens, which is beneficial to the compression of the total length of the lens and balances the contradiction between various aberrations of the lens and the volume and length of the lens.

[0078] Based on the same above concept, the present invention provides three different specific embodiments. The optical power relationship and the design ranges of related physical optical parameters are shown in Table 1:

[0079] Table 1 Related physical optical parameters in each embodiment

[0080]

[0081]

[0082] In the first embodiment of the present invention, referring to Figure 1 It can be seen that the structural composition of each component of the system and the shape and position of each component are crucial to the system. As can be seen from the figure, the optical system is composed of 6 optical lenses. Among them, the aperture 70 is located on the object side of the fourth lens 40. In addition, a flat glass 70 is provided along the object surface to the image surface; the flat glass 70 is located on the image side of the sixth lens 60. The flat glass 70 can protect the photosensitive chip in the imaging sensor, wherein the imaging chip is used to convert the light signal collected by the telephoto lens into an electrical signal, thereby ensuring the imaging effect of the telephoto lens. Specifically, in Example 1, the wide-angle photography lens can achieve the following technical parameters: image plane size Φ28.4mm, field of view angle 52.6°, total lens length 35mm, and distortion 2.59%.

[0083] like Figure 1 The parameter design values of each lens in the wide-angle photography lens of the first embodiment are shown in Table 2:

[0084] Table 2: Design values of each lens in the wide-angle photography lens of Example 1

[0085]

[0086]

[0087] The surface numbers in Table 1 are numbered according to the order of the lens surfaces. STO represents the aperture of the wide-angle lens. The radius of curvature represents the degree of curvature of the lens surface, with a positive value indicating that the surface is curved toward the image plane and a negative value indicating that the surface is curved toward the object plane. The thickness represents the axial distance from the current surface to the center of the next surface. The refractive index represents the ability of the material between the current and next surfaces to deflect light. A blank space represents the current position as air, with a refractive index of 1. The Abbe number represents the dispersion characteristics of the material between the current and next surfaces. The semi-aperture represents half the aperture of the current surface, and the same applies to the following surfaces.

[0088] The aspherical lenses in Table 2 satisfy the following formula:

[0089]

[0090] Among them, Z is the sag of the aspheric surface, c is the basic curvature at the vertex, k is the cone coefficient, r is the radial coordinate perpendicular to the optical axis, a i is the coefficient of the higher-order term, a i r 2i is the high-order term of the aspheric surface.

[0091] The coefficient values of the aspheric surface in the above embodiment 1 are shown in Table 3:

[0092] Table 3 Aspheric coefficients of the first lens in Example 1

[0093] Surface number <![CDATA[a2]]> <![CDATA[a3]]> <![CDATA[a4]]> <![CDATA[a5]]> <![CDATA[a6]]> <![CDATA[a7]]> <![CDATA[a8]]> 1 3.3023E-06 3.4914E-07 -1.4201E-08 2.1383E-10 -6.0495E-12 0.0000E+00 0 2 1.9424E-05 1.2528E-07 8.4070E-10 -5.8181E-10 2.0005E-12 0.0000E+00 0

[0094] Among them, 3.3023E-06 means that the coefficient a2 is 3.3023*10 -6 , and so on.

[0095] Figure 2 yes Figure 1 The MTF curve of the wide-angle photography lens shown is one of the most commonly used lens resolution evaluation methods in modern optical design. The horizontal axis is spatial frequency, and the vertical axis is contrast. The most ideal curve is the highest diffraction limit, which shows the physical limit of the lens under this parameter. The vertical axis of the curve corresponds to the contrast between the black and white line boundaries. The horizontal axis corresponds to the number of black and white lines within 1mm. S and T correspond to the sagittal and meridian of each field of view. Figure 2 It can be seen that the system is close to the diffraction limit at all wavelengths in all fields of view, indicating that the aberrations of the system at all wavelengths are well corrected. At the same time, there is no obvious dispersion in the sagittal and meridional of each field of view, indicating that the system astigmatism is also well corrected, thereby ensuring that the optical system can achieve high-resolution imaging requirements.

[0096] Figure 3 yes Figure 1 The spherical aberration curve for a wide-angle photography lens is shown. The vertical axis is a dimensionless quantity representing the normalized entrance pupil radius, and the horizontal axis represents the distance from the image sensor surface to the focal point on each wavelength axis. The horizontal axis values for all wavelengths are within ±0.1mm, indicating that the optical system has well-corrected axial chromatic aberration.

[0097] Figure 4 yes Figure 1 The chromatic aberration diagram of the wide-angle photography lens shown in the figure. In the coordinate system, the horizontal coordinate represents the distance from the reference wavelength of the light, and the unit is μm; the vertical coordinate represents the normalized image height, and has no unit. The solid lines on both sides of the zero point are the radius of the Airy disk. Figure 4 It can be seen that the chromatic aberration is effectively controlled in this embodiment, that is, during imaging, the distance difference between the reference wavelength and the peripheral wavelengths is small.

[0098] Figure 5 yes Figure 1 The field curvature distortion diagram of the wide-angle photography lens is shown in the figure. In the coordinate system on the left side of the figure, the horizontal coordinate represents the magnitude of the field curvature, and the unit is mm; the vertical coordinate represents the normalized image height, and there is no unit; T represents the meridian, and S represents the arc loss; Figure 5It can be seen that the field curvature of the present embodiment is effectively controlled, that is, when imaging, the difference between the image quality at the center and the image quality at the periphery is small; in the coordinate system on the right, the horizontal coordinate represents the magnitude of the distortion, in %, and the vertical coordinate represents the normalized image height, without a unit; Figure 5 It can be seen that the distortion of the lens provided in this embodiment is 0%≤≤2.5%.

[0099] Figure 6 is a schematic structural diagram of a wide-angle photographic lens provided by the second embodiment of the present invention. In the second embodiment of the present invention, reference is made to Figure 6 As can be seen, this optical system also consists of six optical lenses, with an aperture 70 located between the third lens 30 and the fourth lens 40. Similarly, a flat glass 70 is provided along the object plane to the image plane; it is located on the image-side surface of the sixth lens 60 and protects the photosensitive chip in the imaging sensor. Specifically, in Example 2, this wide-angle photography lens achieves the following technical parameters: image plane size Φ28.4mm, field of view 53.586°, total lens length 33mm, and distortion 0.52%.

[0100] like Figure 6 The parameter design values of each lens in the wide-angle photography lens of the second embodiment are shown in Table 4:

[0101] Table 4: Design values of each lens in the wide-angle photography lens of Example 2

[0102]

[0103]

[0104] The surface numbers in Table 4 are numbered according to the order of the lens surfaces. STO represents the aperture of the wide-angle lens. The radius of curvature represents the degree of curvature of the lens surface, with a positive value indicating that the surface is curved toward the image plane, and a negative value indicating that the surface is curved toward the object plane. The thickness represents the axial distance from the current surface to the center of the next surface. The refractive index represents the light-bending ability of the material between the current and next surfaces. A blank space represents the current position as air, with a refractive index of 1. The Abbe number represents the light-dispersion properties of the material between the current and next surfaces. The semi-aperture represents half the aperture of the current surface, and the same applies to the following surfaces.

[0105] The aspherical lenses in Table 4 satisfy the following formula:

[0106]

[0107] Among them, Z is the sag of the aspheric surface, c is the basic curvature at the vertex, k is the cone coefficient, r is the radial coordinate perpendicular to the optical axis, a i is the coefficient of the higher-order term, a i r2i is the high-order term of the aspheric surface.

[0108] The coefficient values of the aspheric surface in the above-mentioned embodiment 2 are shown in Table 5:

[0109] Table 5 Aspheric coefficients of the first lens in Example 2

[0110] Surface number <![CDATA[a2]]> <![CDATA[a3]]> <![CDATA[a4]]> <![CDATA[a5]]> <![CDATA[a6]]> <![CDATA[a7]]> <![CDATA[a8]]> 1 1.5855E-05 1.3808E-06 -8.8520E-08 1.7460E-09 -2.8242E-11 1.5855E-05 1.3808E-06 2 6.0752E-05 1.0088E-06 -1.0430E-07 1.9624E-09 -2.8996E-11 6.0752E-05 1.0088E-06

[0111] Among them, 1.5855E-05 means that the coefficient a2 is 1.5855*10 -5 , and so on.

[0112] Figure 7 yes Figure 5 The MTF curve of the wide-angle photography lens shown is one of the most commonly used lens resolution evaluation methods in modern optical design. The horizontal axis is spatial frequency, and the vertical axis is contrast. The most ideal curve is the highest diffraction limit, which shows the physical limit of the lens under this parameter. The vertical axis of the curve corresponds to the contrast between the black and white line boundaries. The horizontal axis corresponds to the number of black and white lines within 1mm. S and T correspond to the sagittal and meridian of each field of view. Figure 7 It can be seen that the system is close to the diffraction limit at all wavelengths in all fields of view, indicating that the aberrations of the system at all wavelengths are well corrected. At the same time, there is no obvious dispersion in the sagittal and meridional of each field of view, indicating that the system astigmatism is also well corrected, thereby ensuring that the optical system can achieve high-resolution imaging requirements.

[0113] Figure 8 yes Figure 5 The spherical aberration curve for a wide-angle photography lens is shown. The vertical axis is a dimensionless quantity representing the normalized entrance pupil radius, and the horizontal axis represents the distance from the image sensor surface to the focal point on each wavelength axis. The horizontal axis values for all wavelengths are within ±0.1mm, indicating that the optical system has well-corrected axial chromatic aberration.

[0114] Figure 9 yes Figure 5 The chromatic aberration diagram of the wide-angle photography lens shown in the figure. In the coordinate system, the horizontal coordinate represents the distance from the reference wavelength of the light, and the unit is μm; the vertical coordinate represents the normalized image height, and has no unit. The solid lines on both sides of the zero point are the radius of the Airy disk. Figure 9 It can be seen that the chromatic aberration is effectively controlled in this embodiment, that is, during imaging, the distance difference between the reference wavelength and the peripheral wavelengths is small.

[0115] Figure 10 yes Figure 5The field curvature distortion diagram of the wide-angle photography lens is shown in the figure. In the coordinate system on the left side of the figure, the horizontal coordinate represents the magnitude of the field curvature, and the unit is mm; the vertical coordinate represents the normalized image height, and there is no unit; T represents the meridian, and S represents the arc loss; Figure 10 It can be seen that the field curvature of the present embodiment is effectively controlled, that is, when imaging, the difference between the image quality at the center and the image quality at the periphery is small; in the coordinate system on the right, the horizontal coordinate represents the magnitude of the distortion, in %, and the vertical coordinate represents the normalized image height, without a unit; Figure 10 It can be seen that the distortion of the lens provided in this embodiment is -0.5% ≤ ≤ 0%.

[0116] Figure 11 is a schematic structural diagram of a wide-angle photographic lens provided by the third embodiment of the present invention. In the third embodiment of the present invention, reference is made to Figure 11 As can be seen, this optical system also consists of six optical lenses. Similarly, an aperture 70 is located between the third lens 30 and the fourth lens 40. A flat glass 70 is also provided along the object plane to the image plane. Flat glass 70 is located on the image-side surface of the sixth lens 60 and protects the photosensitive chip in the imaging sensor. Specifically, in Example 3, this wide-angle photography lens achieves the following technical parameters: image plane size Φ28.4mm, field of view 52.8°, total lens length 33mm, and distortion 2.1%.

[0117] like Figure 11 The parameter design values of each lens in the wide-angle photography lens of the third embodiment are shown in Table 6:

[0118] Table 6: Design values of each lens in the wide-angle photography lens of Example 3

[0119]

[0120]

[0121] The surface numbers in Table 6 are numbered according to the order of the lens surfaces. STO represents the aperture of the wide-angle lens. The radius of curvature represents the degree of curvature of the lens surface. A positive value indicates that the surface is curved toward the image plane, while a negative value indicates that the surface is curved toward the object plane. The thickness represents the axial distance from the current surface to the center of the next surface. The refractive index represents the light-bending ability of the material between the current and next surfaces. A blank space represents the current position as air, with a refractive index of 1. The Abbe number represents the light-dispersion properties of the material between the current and next surfaces. The semi-aperture represents half the aperture of the current surface, and the same applies to the following surfaces.

[0122] The aspherical lenses in Table 6 satisfy the following formula:

[0123]

[0124] Among them, Z is the sag of the aspheric surface, c is the basic curvature at the vertex, k is the cone coefficient, r is the radial coordinate perpendicular to the optical axis, a i is the coefficient of the higher-order term, a i r 2i is the high-order term of the aspheric surface.

[0125] The coefficient values of the aspheric surface in the above embodiment 3 are shown in Table 7:

[0126] Table 7 Aspheric coefficients of the first lens in Example 3

[0127] Surface number <![CDATA[a2]]> <![CDATA[a3]]> <![CDATA[a4]]> <![CDATA[a5]]> <![CDATA[a b ]]> <![CDATA[a7]]> <![CDATA[a8]]> 1 -1.7909E-05 -4.7928E-08 -2.0308E-08 2.7465E-10 -6.4774E-12 0 0 2 -1.1367E-06 -4.0122E-07 -5.3933E-09 -3.0123E-10 1.0372E-13 0 0

[0128] Among them, -1.7909E-05 means that the coefficient a2 is -1.7909*10 -5 , and so on.

[0129] Figure 12 yes Figure 11 The MTF curve of the wide-angle photography lens shown is one of the most commonly used lens resolution evaluation methods in modern optical design. The horizontal axis is spatial frequency, and the vertical axis is contrast. The most ideal curve is the highest diffraction limit, which shows the physical limit of the lens under this parameter. The vertical axis of the curve corresponds to the contrast between the black and white line boundaries. The horizontal axis corresponds to the number of black and white lines within 1mm. S and T correspond to the sagittal and meridian of each field of view. Figure 12 It can be seen that the system is close to the diffraction limit at all wavelengths in all fields of view, indicating that the aberrations of the system at all wavelengths are well corrected. At the same time, there is no obvious dispersion in the sagittal and meridional of each field of view, indicating that the system astigmatism is also well corrected, thereby ensuring that the optical system can achieve high-resolution imaging requirements.

[0130] Figure 13 yes Figure 11 The spherical aberration curve for a wide-angle photography lens is shown. The vertical axis is a dimensionless quantity representing the normalized entrance pupil radius, and the horizontal axis represents the distance from the image sensor surface to the focal point on each wavelength axis. The horizontal axis values for all wavelengths are within ±0.1mm, indicating that the optical system has well-corrected axial chromatic aberration.

[0131] Figure 14 yes Figure 11 The chromatic aberration diagram of the wide-angle photography lens shown in the figure. In the coordinate system, the horizontal coordinate represents the distance from the reference wavelength of the light, and the unit is μm; the vertical coordinate represents the normalized image height, and has no unit. The solid lines on both sides of the zero point are the radius of the Airy disk. Figure 14 It can be seen that the chromatic aberration is effectively controlled in this embodiment, that is, during imaging, the distance difference between the reference wavelength and the peripheral wavelengths is small.

[0132] Figure 15 yes Figure 11 The field curvature distortion diagram of the wide-angle photography lens is shown in the figure. In the coordinate system on the left side of the figure, the horizontal coordinate represents the magnitude of the field curvature, and the unit is mm; the vertical coordinate represents the normalized image height, and there is no unit; T represents the meridian, and S represents the arc loss; Figure 15 It can be seen that the field curvature of the present embodiment is effectively controlled, that is, when imaging, the difference between the image quality at the center and the image quality at the periphery is small; in the coordinate system on the right, the horizontal coordinate represents the magnitude of the distortion, in %, and the vertical coordinate represents the normalized image height, without a unit; Figure 15 It can be seen that the distortion of the lens provided in this embodiment is 0%≤≤2.1%.

[0133] Note that the above are only preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will appreciate that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, combinations, and substitutions are possible for those skilled in the art without departing from the scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments and may include many other equivalent embodiments without departing from the scope of the present invention. The scope of the present invention is determined by the scope of the appended claims.

Claims

1. A wide-angle photographic lens, characterized in that: comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens arranged in sequence along the optical axis from the object plane to the image plane; The first lens has positive optical power, the second lens has positive optical power, the third lens has negative optical power, the fourth lens has negative optical power, the fifth lens has positive optical power, and the sixth lens has positive optical power.

2. The wide-angle photography lens according to claim 1, wherein: The first lens to the sixth lens meet the following conditions: 0.668<Φ1 / Φ<0.935; 1.009<Φ2 / Φ<1.410; -1.875<Φ3 / Φ<-1.492; -1.664<Φ4 / Φ<-1.434; 1.172<Φ5 / Φ<1.703; 0.413<Φ6 / Φ<0.958; Among them, Φ1 is the optical focal length of the first lens, Φ2 is the optical focal length of the second lens, Φ3 is the optical focal length of the third lens, Φ4 is the optical focal length of the fourth lens, Φ5 is the optical focal length of the fifth lens, Φ6 is the optical focal length of the sixth lens, and Φ is the optical focal length of the wide-angle photography lens.

3. The wide-angle photography lens according to claim 2, wherein: The first lens satisfies the following conditions: -1.2456≤(C1-C2) / (C1+C2)≤-0.2976; Wherein, C1 is the curvature of the object-side surface of the first lens, and C2 is the curvature of the image-side surface of the first lens.

4. The wide-angle photography lens according to claim 2, wherein: The first lens to the sixth lens meet the following conditions: 0.5649<Φ1_3 / Φ<0.6487; 0.7450<Φ4_6 / Φ<1.0982; Wherein, Φ1_3 is the optical focal length of the lens group consisting of the first lens, the second lens and the third lens; Φ4_6 is the optical focal length of the lens group consisting of the fourth lens, the fifth lens and the sixth lens.

5. The wide-angle photography lens according to claim 1, wherein: The object side surface of the first lens is convex, and the image side surface is concave; The object side surface of the second lens is convex, and the image side surface is concave; The object side surface of the third lens is convex, and the image side surface is concave; The object-side surface of the sixth lens is concave, and the image-side surface is concave.

6. The wide-angle photography lens according to claim 5, wherein: The first lens is an aspherical glass lens, and the second lens to the sixth lens are all spherical glass lenses.

7. The wide-angle photography lens according to claim 6, wherein: The first lens meets the following conditions: -1.204<K1<-0.174； -3.982<K2<-0.354； Wherein, K1 is the cone coefficient of the object-side surface of the first lens, and K2 is the cone coefficient of the image-side surface of the first lens.

8. The wide-angle photography lens according to claim 1, wherein: The fourth lens and the fifth lens meet the following conditions: -1.1840≤1000*(Φ4 / VD4+Φ5 / VD5)≤0.421; Wherein, Φ4 is the optical power of the fourth lens, Φ5 is the optical power of the fifth lens; VD4 is the Abbe number of the fourth lens, and VD5 is the Abbe number of the fifth lens.

9. The wide-angle photography lens according to claim 8, wherein: The fourth lens and the fifth lens meet the following conditions: 26.4781 <VD4<40.8475; 33.3090 <VD5<40.8475。 10. The wide-angle photography lens according to claim 1, wherein: The wide-angle camera lens meets the following conditions: 1.1785 <TTL / f<1.2890; Wherein, TTL is the total optical length of the wide-angle photography lens, and f is the focal length of the wide-angle photography lens.

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