An optical imaging lens

Abstract

The present invention relates to an optical imaging lens, which includes a first lens to an eighth lens in sequence from an object side to an image side along an optical axis. The first lens to the eighth lens each include an object-side surface facing the object side and allowing imaging light to pass through, and an image-side surface facing the image side and allowing imaging light to pass through. The optical imaging lens has only the above-mentioned eight lenses with refractive power, and can maintain system performance while effectively shortening the lens length.

Description

Technical Field

[0001] The present invention relates to the field of optical imaging technology, and in particular to an optical imaging lens. Background Art

[0002] With the continuous advancement of technology, optical imaging lenses have also developed rapidly in recent years and are widely used in various fields such as smart phones, tablets, video conferencing, security monitoring, etc. Therefore, the requirements for optical imaging lenses are also getting higher and higher.

[0003] However, the optical imaging lenses currently used in security monitoring, intelligent transportation, smart home, video conferencing and other fields still have at least the following defects:

[0004] 1. The total length of the optical system of the lens is too long and there are too many lenses, which makes the overall cost of the lens too high, and the large size limits its installation and use.

[0005] 2. The imaging resolution of the lens is low.

[0006] 3. The optical distortion of zoom lenses with a focal length of about 3.5mm-9mm is large, which will cause image distortion. Summary of the invention

[0007] The present invention aims to provide an optical imaging lens to solve at least one of the above problems.

[0008] The specific plan is as follows:

[0009] An optical imaging lens, which includes a first lens to an eighth lens in order from the object side to the image side along an optical axis, wherein each of the first lens to the eighth lens includes an object-side surface facing the object side and allowing imaging light to pass through, and an image-side surface facing the image side and allowing imaging light to pass through; wherein the first lens has a negative refractive power, and its object-side surface is a convex surface, and its image-side surface is a concave surface; the second lens has a negative refractive power, and its object-side surface is a concave surface, and its image-side surface is a concave surface, and its object-side surface and image-side surface are both aspherical surfaces; the third lens has a positive refractive power, and its object-side surface is a convex surface, and its image-side surface is a concave surface, and Its object side surface and image side surface are both aspherical surfaces; the fourth lens has a positive refractive power, its object side surface is convex, and its image side surface is convex; the fifth lens has a positive refractive power, its object side surface is convex, and its image side surface is convex; the sixth lens has a negative refractive power, its object side surface is concave, and its image side surface is concave; the seventh lens has a positive refractive power, its object side surface is convex, and its image side surface is convex; the eighth lens has a positive refractive power, its object side surface is convex, its image side surface is convex, and its object side surface and image side surface are both aspherical surfaces; the optical imaging lens has only the above eight lenses with refractive power.

[0010] In some embodiments, the optical imaging lens includes a compensating group with negative optical power and a varifocal group with positive optical power from left to right. The compensating group consists of a first lens, a second lens, and a third lens, and the varifocal group consists of a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens. The aperture stop is located between the third lens and the fourth lens, and the position of the aperture stop changes with the position of the varifocal group.

[0011] In some embodiments, the fifth lens and the sixth lens form a cemented lens.

[0012] In some embodiments, the Abbe number of the fifth lens is greater than that of the sixth lens, and vd5 - vd6 > 40 is satisfied, where vd5 and vd6 are the Abbe numbers of the fifth and sixth lenses respectively.

[0013] In some embodiments, during the zooming process of the optical imaging lens, the travel of the compensating group is 15 - 17 mm; the travel of the varifocal group is 4.5 - 5.5 mm.

[0014] In some embodiments, the following condition is also satisfied: 0.9 < |fA / fB| < 1.2, where fA is the focal length of the compensating group and fB is the focal length of the varifocal group.

[0015] In some embodiments, the following conditions are also satisfied: 1.6 < nd1 < 1.7, 1.5 < nd2 < 1.6, 1.6 < nd3 < 1.7, 1.65 < nd4 < 1.75, 1.55 < nd5 < 1.65, 1.7 < nd6 < 1.8, 1.6 < nd7 < 1.7, 1.5 < nd8 < 1.6, where nd1, nd2, nd3, nd4, nd5, nd6, nd7, and nd8 are the refractive indices of the first to eighth lenses respectively.

[0016] In some embodiments, the following conditions are also satisfied: 50 < vd1 < 60, 50 < vd2 < 60, 15 < vd3 < 25, 50 < vd4 < 60, 65 < vd5 < 75, 20 < vd6 < 30, 55 < vd7 < 65, 55 < vd8 < 65, where vd1, vd2, vd3, vd4, vd5, vd6, vd7, and nd8 are the Abbe numbers of the first to eighth lenses respectively.

[0017] 10. In some embodiments, the following condition is also satisfied: the object side and the image side of the second, third, and eighth lenses are designed as 16th - order even aspheres.

[0018] The optical imaging lens provided by the present invention has the following advantages compared with the prior art:

[0019] 1. Adopting a design of 8 lenses, it has a simple structure, the total optical system length TTL is less than 46.5 mm, the overall volume of the lens is small, and it is convenient for installation and use;

[0020] 2. High resolution, 120lp / mm full field of view MTF is greater than 0.45, 0.9 field of view MTF is greater than 0.5;

[0021] 3. In the focal length range of 3.5mm-9mm, the optical distortion is <-7.5% for short focus, <-0.5% for medium focus, and <0.5% for long focus. The image can clearly restore the shape of the object without distortion. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The optical path diagram of the optical imaging lens in the first embodiment at short focal length is shown.

[0023] Figure 2 The optical path diagram of the optical imaging lens in the first embodiment when at mid-focus is shown.

[0024] Figure 3 The optical path diagram of the optical imaging lens in the first embodiment is shown in FIG.

[0025] Figure 4 A detailed optical data table of the optical imaging lens in Example 1 is shown.

[0026] Figure 5a The MTF curve of the optical imaging lens in the first embodiment at short focal length is shown.

[0027] Figure 5b The MTF curve diagram of the optical imaging lens in the first embodiment when the lens is at mid-focus is shown.

[0028] Figure 5c The MTF curve of the optical imaging lens in the first embodiment at a telephoto focus is shown.

[0029] Figure 6a The focal shift curve diagram of the optical imaging lens in the first embodiment at short focal length is shown.

[0030] Figure 6b The focal shift curve diagram of the optical imaging lens in the first embodiment is shown.

[0031] Figure 6c The focal shift curve diagram of the optical imaging lens in the first embodiment at a telephoto focus is shown.

[0032] Figure 7a A diagram showing lateral chromatic aberration of the optical imaging lens in the first embodiment at short focal length is shown.

[0033] Figure 7b A diagram showing lateral chromatic aberration of the optical imaging lens in Embodiment 1 when the lens is at mid-focus.

[0034] Figure 7cA diagram showing lateral chromatic aberration of the optical imaging lens in the first embodiment at a telephoto focus is shown.

[0035] Figure 8a The field curvature and distortion diagram of the optical imaging lens in the first embodiment at short focal length are shown.

[0036] Figure 8b The field curvature and distortion diagram of the optical imaging lens in the first embodiment when the lens is at mid-focus are shown.

[0037] Figure 8c The field curvature and distortion diagram of the optical imaging lens in the first embodiment at a telephoto focus are shown.

[0038] Figure 9a The longitudinal aberration diagram of the optical imaging lens in the first embodiment at short focal length is shown.

[0039] Figure 9b The longitudinal aberration diagram of the optical imaging lens in the first embodiment when the lens is at mid-focus is shown.

[0040] Fig.9c The longitudinal aberration diagram of the optical imaging lens in the first embodiment at a telephoto focus is shown.

[0041] Fig.10 The optical path diagram of the optical imaging lens in the second embodiment at short focal length is shown.

[0042] Fig.11 The optical path diagram of the optical imaging lens in the second embodiment when at mid-focus is shown.

[0043] Fig.12 The optical path diagram of the optical imaging lens in the second embodiment is shown in FIG.

[0044] Fig.13 A table diagram showing detailed optical data of the optical imaging lens in Example 2 is shown.

[0045] Fig.14a The MTF curve of the optical imaging lens in the second embodiment at short focal length is shown.

[0046] Fig.14b The MTF curve diagram of the optical imaging lens in the second embodiment when the lens is at mid-focus is shown.

[0047] Fig.14c The MTF curve diagram of the optical imaging lens in the second embodiment at a telephoto focus is shown.

[0048] Fig.15a The focal shift curve diagram of the optical imaging lens in the second embodiment at short focal length is shown.

[0049] Fig.15b A focal shift curve diagram of the optical imaging lens in the second embodiment is shown.

[0050] Fig.15c The focal shift curve diagram of the optical imaging lens in the second embodiment at a telephoto focus is shown.

[0051] Fig.16a A diagram showing lateral chromatic aberration of the optical imaging lens in the second embodiment at short focal length is shown.

[0052] Fig.16b A diagram showing lateral chromatic aberration of the optical imaging lens in Embodiment 2 when the lens is at mid-focus.

[0053] Fig.16c A diagram showing lateral chromatic aberration of the optical imaging lens in Embodiment 2 at telephoto focus is shown.

[0054] Fig.17a The field curvature and distortion diagram of the optical imaging lens in the second embodiment at short focal length are shown.

[0055] Fig.17b The field curvature and distortion diagram of the optical imaging lens in the second embodiment when the lens is at mid-focus are shown.

[0056] Fig.17c The field curvature and distortion diagram of the optical imaging lens in the second embodiment at a telephoto focus are shown.

[0057] Fig.18a The longitudinal aberration diagram of the optical imaging lens in the second embodiment at short focal length is shown.

[0058] Fig.18b The longitudinal aberration diagram of the optical imaging lens in the second embodiment when the lens is at mid-focus is shown.

[0059] Fig.18c The longitudinal aberration diagram of the optical imaging lens in the second embodiment at a telephoto focus is shown.

[0060] Fig.19 The light path diagram of the optical imaging lens in the third embodiment at short focal length is shown.

[0061] Fig. 20 The light path diagram of the optical imaging lens in the third embodiment when at mid-focus is shown.

[0062] Fig.21 The light path diagram of the optical imaging lens in the third embodiment is shown in FIG.

[0063] Fig. 22 A detailed optical data table of the optical imaging lens in Example 3 is shown.

[0064] Fig.23a The MTF curve of the optical imaging lens in the third embodiment at short focal length is shown.

[0065] Figure 23bThe MTF curve diagram of the optical imaging lens in the third embodiment when the lens is at mid-focus is shown.

[0066] Fig.23c The MTF curve of the optical imaging lens in the third embodiment at a telephoto focus is shown.

[0067] Fig.24a The focal shift curve diagram of the optical imaging lens in the third embodiment at short focal length is shown.

[0068] Figure 24b A focal shift curve diagram of the optical imaging lens in the third embodiment is shown.

[0069] Fig.24c The focal shift curve of the optical imaging lens in the third embodiment is shown in FIG.

[0070] Fig.25a A diagram showing lateral chromatic aberration of the optical imaging lens in Example 3 at short focal length is shown.

[0071] Fig.25b A diagram showing lateral chromatic aberration of the optical imaging lens in Embodiment 3 when the lens is at mid-focus.

[0072] Fig.25c A diagram showing lateral chromatic aberration of the optical imaging lens in Example 3 at telephoto focus is shown.

[0073] Fig.26a The field curvature and distortion diagram of the optical imaging lens in the third embodiment at short focal length are shown.

[0074] Figure 26b The field curvature and distortion diagram of the optical imaging lens in Example 3 when the lens is at mid-focus are shown.

[0075] Fig.26c The field curvature and distortion diagram of the optical imaging lens in the third embodiment at a telephoto focus are shown.

[0076] Fig.27a The longitudinal aberration diagram of the optical imaging lens in the third embodiment at short focal length is shown.

[0077] Figure 27b A longitudinal aberration diagram of the optical imaging lens in Example 3 when the lens is at mid-focus is shown.

[0078] Fig.27c The longitudinal aberration diagram of the optical imaging lens in the third embodiment at a telephoto focus is shown.

[0079] Fig.28 The surface data table of the aspherical surfaces of the object side and image side of the second, third and eighth lenses of the optical imaging lens in the first, second and third embodiments is shown. DETAILED DESCRIPTION

[0080] To further illustrate the various embodiments, the present invention provides drawings. These drawings are part of the disclosure of the present invention, which are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these contents, a person of ordinary skill in the art should be able to understand other possible implementations and advantages of the present invention. The components in the figures are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0081] The present invention will now be further described with reference to the accompanying drawings and specific implementation methods.

[0082] In this specification, "a lens having a positive refractive power (or a negative refractive power)" means that the paraxial refractive power of the lens calculated by Gaussian optical theory is positive (or negative). The "object side (or image side) of the lens" is defined as a specific range of the lens surface through which the imaging light passes. The concave and convex shape of the lens can be judged according to the judgment method of ordinary knowledge in this field, that is, the concave and convex shape of the lens surface can be judged by the positive and negative signs of the radius of curvature (abbreviated as R value). R value can be commonly used in optical design software, such as Zemax or CodeV. R value is also commonly found in the lens data sheet (lensdatasheet) of optical design software. For the object side, when the R value is positive, the object side is judged to be convex; when the R value is negative, the object side is judged to be concave. Conversely, for the image side, when the R value is positive, the image side is judged to be concave; when the R value is negative, the image side is judged to be convex.

[0083] The present invention provides an optical imaging lens, which includes a first lens to an eighth lens in sequence along an optical axis from the object side to the image side, wherein each of the first lens to the eighth lens includes an object-side surface facing the object side and allowing imaging light to pass through, and an image-side surface facing the image side and allowing imaging light to pass through; wherein:

[0084] The first lens has a negative refractive power, with a convex object side surface and a concave image side surface;

[0085] The second lens has a negative refractive power, its object side surface is concave, its image side surface is concave, and its object side surface and image side surface are both aspherical;

[0086] The third lens has a positive refractive power, its object side surface is convex, its image side surface is concave, and both its object side surface and image side surface are aspherical;

[0087] The fourth lens element has a positive refractive power, and its object side surface is convex and its image side surface is convex;

[0088] The fifth lens element has a positive refractive power, and its object side surface is convex and its image side surface is convex;

[0089] The sixth lens element has a negative refractive power, and its object side surface is concave and its image side surface is concave;

[0090] The seventh lens has a positive refractive power, with its object side being convex and its image side being convex.

[0091] The eighth lens has a positive refractive power, with its object side being convex, its image side being convex, and both its object-side surface and image-side surface being aspherical.

[0092] The object sides and image sides of the first, fourth, fifth, sixth, and seventh lenses described above are all spherical, and their combination with the aspherical object sides and image sides of the second, third, and seventh lenses can maintain system performance while effectively shortening the lens length.

[0093] In some embodiments, the optical imaging lens sequentially includes a compensation group with negative optical power and a varifocal group with positive optical power from left to right. The compensation group consists of the first lens, the second lens, and the third lens, and the varifocal group consists of the fourth lens, the fifth lens, the sixth lens, the seventh lens, and the eighth lens. The fifth lens and the sixth lens form a cemented lens. The aperture stop is located between the third lens and the fourth lens, and the position of the aperture stop changes following the position of the varifocal group. During the zooming process of the lens, the travel of the compensation group is 15 - 17 mm; the travel of the varifocal group is 4.5 - 5.5 mm.

[0094] In some embodiments, the optical imaging lens of the present invention further satisfies the following condition: 0.9 < |fA / fB| < 1.2, where fA is the focal length of the compensation group and fB is the focal length of the varifocal group.

[0095] In some embodiments, the optical imaging lens of the present invention further satisfies the following conditions: 1.6 < nd1 < 1.7, 50 < vd1 < 60, 1.5 < nd2 < 1.6, 50 < vd2 < 60, 1.6 < nd3 < 1.7, 15 < vd3 < 25, 1.65 < nd4 < 1.75, 50 < vd4 < 60, 1.55 < nd5 < 1.65, 65 < vd5 < 75, 1.7 < nd6 < 1.8, 30 < vd6 < 30, 1.6 < nd7 < 1.7, 55 < vd7 < 65, 1.5 < nd8 < 1.6, 55 < vd8 < 65; where nd1, nd2, nd3, nd4, nd5, nd6, nd7, nd8 are the refractive indices of the first to eighth lenses respectively, and vd1, vd2, vd3, vd4, vd5, vd6, vd7, nd8 are the Abbe numbers of the first to eighth lenses respectively.

[0096] In some embodiments, the object sides and image sides of the second, third, and eighth lenses are all designed with 16th-order even aspheres, which is beneficial for correcting secondary spectrum and higher-order aberrations.

[0097] In some embodiments, the fifth lens and the sixth lens use a cemented lens with high and low dispersion materials, which is beneficial for correcting chromatic aberration, facilitating the lens structure design, and reducing the lens cost.

[0098] Embodiment 1

[0099] This specific embodiment provides an optical imaging lens, such as Figure 1 As shown, it includes the first lens to the eighth lens in sequence along an optical axis I from the object side A1 to the image side A2, and each of the first lens to the eighth lens includes an object-side surface facing the object side and allowing imaging light to pass through, and an image-side surface facing the image side and allowing imaging light to pass through; wherein:

[0100] The first lens 1 has a negative refractive power, and its object side surface is convex and its image side surface is concave;

[0101] The second lens 2 has a negative refractive power, its object side surface is concave, its image side surface is concave, and its object side surface and image side surface are both aspherical surfaces;

[0102] The third lens 3 has a positive refractive power, its object side surface is convex, its image side surface is concave, and its object side surface and image side surface are both aspherical;

[0103] The fourth lens element 4 has a positive refractive power, and its object-side surface is convex and its image-side surface is convex;

[0104] The fifth lens element 5 has a positive refractive power, and its object-side surface is convex and its image-side surface is convex;

[0105] The sixth lens element 6 has a negative refractive power, and its object-side surface is concave and its image-side surface is concave;

[0106] The seventh lens element 7 has a positive refractive power, and its object-side surface is convex and its image-side surface is convex;

[0107] The eighth lens element 8 has a positive refractive power, has a convex object-side surface, a convex image-side surface, and both the object-side surface and the image-side surface are aspherical surfaces.

[0108] The optical imaging lens has only the above-mentioned eight lenses with refractive power, and the fifth lens and the sixth lens form a cemented lens, the first lens, the second lens and the third lens of the eight lenses form a compensation group, the fourth lens, the fifth lens, the sixth lens, the seventh lens and the eighth lens form a zoom group, and the diaphragm (not shown in the figure) is located between the third lens and the fourth lens, and the position of the diaphragm changes with the position of the zoom group.

[0109] The optical path diagram of the optical imaging lens in this embodiment at short focal length is as follows: Figure 1 As shown, the optical path diagram at mid-focus is as follows Figure 2 As shown, the optical path diagram at telephoto is as follows Figure 3As shown, during the zooming process of the lens, when the lens changes from short focus to long focus, the magnification group moves away from the image plane, and the compensation group moves close to the image plane, that is, the magnification group and the compensation group are close to each other; during the zooming process of the lens, the interval between the magnification group and the compensation group at the short focus position is the largest, and at this time the distance between the magnification group and the target surface (that is, the back working distance of the lens) is the smallest; the interval between the magnification group and the compensation group at the long focus position is the smallest, but a certain minimum center interval is still guaranteed, and at this time the distance between the magnification group and the target surface (that is, the back working distance of the lens) is the largest.

[0110] The detailed optical data of this specific embodiment are as follows Figure 4 As shown in the figure, the surface data of the aspheric surfaces of the object side and image side of the second, third and eighth lenses are as follows Fig.28 As shown in the part of embodiment 1.

[0111] Please refer to the MTF curve of visible light (435nm~650nm) Figure 5a-5c ,in Figure 5a This is the MTF curve at short focal length. Figure 5b This is the MTF curve at mid-focus. Figure 5c This is the MTF curve at telephoto.

[0112] For the focal shift curve of visible light (435nm~650nm), please refer to Figure 6a-6c ,in Figure 6a This is the focal shift curve at short focal length. Figure 6b This is the focal shift curve at mid-focus. Figure 6c This is the focal shift curve for telephoto.

[0113] For the lateral chromatic aberration diagram of visible light (435nm~650nm), please refer to Figure 7a-7c ,in Figure 7a This is the lateral chromatic aberration diagram at short focal length. Figure 7b This is the lateral chromatic aberration diagram at mid-focus. Figure 7c This is a diagram of lateral chromatic aberration at telephoto.

[0114] For the field curvature and distortion diagram of visible light (435nm~650nm), please refer to Figure 8a-8c A and B, where Figure 8a This is the field curvature and distortion diagram at short focal length. Figure 8b This is the field curvature and distortion diagram at mid-focus. Figure 8c This is the field curvature and distortion diagram at telephoto.

[0115] For the longitudinal aberration diagram of visible light (435nm~650nm), please refer to Figure 9a-9c ,in Figure 9a is the longitudinal aberration diagram at short focal length, Figure 9b This is the longitudinal aberration diagram at mid-focus. Fig.9c This is the longitudinal aberration diagram at telephoto.

[0116] In this embodiment, the front group uses two meniscus lenses with negative focal length in succession, which can better control the light path; the rear group uses five lenses, which can better correct the system aberrations; so that the imaging quality of the lens is good, the MTF of the full field of view of 120lp / mm is greater than 0.45, and the MTF within the field of view of 0.9 is greater than 0.5; the maximum optical distortion is at the short focus position, the maximum distortion is about -7.5%, and the optical distortion at the mid-focus and long focus positions is less than |0.5%|.

[0117] The optical imaging lens has a combined focal length of 3.53 to 9 mm, a zoom ratio of up to 2.55, a field of view of 90 to 40°, a total system length of less than 46.5 mm TTL, a relative aperture of 1 / 2.5 to 1 / 3.5, an imaging range greater than or equal to φ6.6 mm, and is suitable for 1 / 2.7″ CCD or CMOS chips. The maximum light-transmitting diameter of the lens is less than φ18 mm. The overall structure is compact, the volume is small, the practicability is strong, and the installation and use are extremely convenient.

[0118] Embodiment 2

[0119] This specific embodiment provides an optical imaging lens, such as Fig.10 As shown, it includes the first lens to the eighth lens in sequence along an optical axis I from the object side A1 to the image side A2, and each of the first lens to the eighth lens includes an object-side surface facing the object side and allowing imaging light to pass through, and an image-side surface facing the image side and allowing imaging light to pass through; wherein:

[0120] The first lens 1 has a negative refractive power, and its object side surface is convex and its image side surface is concave;

[0121] The second lens 2 has a negative refractive power, its object side surface is concave, its image side surface is concave, and its object side surface and image side surface are both aspherical surfaces;

[0122] The third lens 3 has a positive refractive power, its object side surface is convex, its image side surface is concave, and its object side surface and image side surface are both aspherical;

[0123] The fourth lens element 4 has a positive refractive power, and its object-side surface is convex and its image-side surface is convex;

[0124] The fifth lens element 5 has a positive refractive power, and its object-side surface is convex and its image-side surface is convex;

[0125] The sixth lens element 6 has a negative refractive power, and its object-side surface is concave and its image-side surface is concave;

[0126] The seventh lens element 7 has a positive refractive power, and its object-side surface is convex and its image-side surface is convex;

[0127] The eighth lens element 8 has a positive refractive power, has a convex object-side surface, a convex image-side surface, and both the object-side surface and the image-side surface are aspherical surfaces.

[0128] The optical imaging lens has only the above-mentioned eight lenses with refractive power, and the fifth lens and the sixth lens form a cemented lens, the first lens, the second lens and the third lens of the eight lenses form a compensation group, the fourth lens, the fifth lens, the sixth lens, the seventh lens and the eighth lens form a zoom group, and the diaphragm (not shown in the figure) is located between the third lens and the fourth lens, and the position of the diaphragm changes with the position of the zoom group.

[0129] The optical path diagram of the optical imaging lens in this embodiment at short focal length is as follows: Fig.10 As shown, the optical path diagram at mid-focus is as follows Fig.11 As shown, the optical path diagram at telephoto is as follows Fig.12 As shown, during the zooming process of the lens, when the lens changes from short focus to long focus, the magnification group moves away from the image plane, and the compensation group moves close to the image plane, that is, the magnification group and the compensation group are close to each other; during the zooming process of the lens, the interval between the magnification group and the compensation group at the short focus position is the largest, and at this time the distance between the magnification group and the target surface (that is, the back working distance of the lens) is the smallest; the interval between the magnification group and the compensation group at the long focus position is the smallest, but a certain minimum center interval is still guaranteed, and at this time the distance between the magnification group and the target surface (that is, the back working distance of the lens) is the largest.

[0130] The detailed optical data of this specific embodiment are as follows Fig.13 As shown in the figure, the surface data of the aspheric surfaces of the object side and image side of the second, third and eighth lenses are as follows Fig.28 As shown in the part of Example 2.

[0131] Please refer to the MTF curve of visible light (435nm~650nm) Figure 14a-Figure 14c ,in Fig.14a This is the MTF curve at short focal length. Fig.14b This is the MTF curve at mid-focus. Fig.14c This is the MTF curve at telephoto.

[0132] For the focal shift curve of visible light (435nm~650nm), please refer to Figure 15a-Figure 15c ,in Fig.15a This is the focal shift curve at short focal length. Fig.15b This is the focal shift curve at mid-focus. Fig.15c This is the focal shift curve for telephoto.

[0133] For the lateral chromatic aberration diagram of visible light (435nm~650nm), please refer to Figure 16a-Figure 16c ,in Fig.16a This is the lateral chromatic aberration diagram at short focal length. Fig.16b This is the lateral chromatic aberration diagram at mid-focus. Fig.16c This is a diagram of lateral chromatic aberration at telephoto.

[0134] For the field curvature and distortion diagram of visible light (435nm~650nm), please refer to Figure 17a-Figure 17c A and B, where Fig.17a This is the field curvature and distortion diagram at short focal length. Fig.17b This is the field curvature and distortion diagram at mid-focus. Fig.17c This is the field curvature and distortion diagram at telephoto.

[0135] For the longitudinal aberration diagram of visible light (435nm~650nm), please refer to Figure 18a-Figure 18c ,in Fig.18a is the longitudinal aberration diagram at short focal length, Fig.18b This is the longitudinal aberration diagram at mid-focus. Fig.18c This is the longitudinal aberration diagram at telephoto.

[0136] In this embodiment, the front group uses two meniscus lenses with negative focal length in succession, which can better control the light path; the rear group uses five lenses, which can better correct the system aberrations; so that the imaging quality of the lens is good, the MTF of the full field of view of 120lp / mm is greater than 0.45, and the MTF within the field of view of 0.9 is greater than 0.5; the maximum optical distortion is at the short focus position, the maximum distortion is about -7.5%, and the optical distortion at the mid-focus and long focus positions is less than |0.5%|.

[0137] The optical imaging lens has a combined focal length of 3.53 to 9 mm, a zoom ratio of up to 2.55, a field of view of 90 to 40°, a total system length of less than 46.5 mm TTL, a relative aperture of 1 / 2.5 to 1 / 3.5, an imaging range greater than or equal to φ6.6 mm, and is suitable for 1 / 2.7″ CCD or CMOS chips. The maximum light-transmitting diameter of the lens is less than φ18 mm. The overall structure is compact, the volume is small, the practicability is strong, and the installation and use are extremely convenient.

[0138] Embodiment 3

[0139] This specific embodiment provides an optical imaging lens, such as Fig.19 As shown, it includes the first lens to the eighth lens in sequence along an optical axis I from the object side A1 to the image side A2, and each of the first lens to the eighth lens includes an object-side surface facing the object side and allowing imaging light to pass through, and an image-side surface facing the image side and allowing imaging light to pass through; wherein:

[0140] The first lens 1 has a negative refractive power, and its object side surface is convex and its image side surface is concave;

[0141] The second lens 2 has a negative refractive power, its object side surface is concave, its image side surface is concave, and its object side surface and image side surface are both aspherical surfaces;

[0142] The third lens 3 has a positive refractive power, its object side surface is convex, its image side surface is concave, and its object side surface and image side surface are both aspherical;

[0143] The fourth lens element 4 has a positive refractive power, and its object-side surface is convex and its image-side surface is convex;

[0144] The fifth lens element 5 has a positive refractive power, and its object-side surface is convex and its image-side surface is convex;

[0145] The sixth lens element 6 has a negative refractive power, and its object-side surface is concave and its image-side surface is concave;

[0146] The seventh lens element 7 has a positive refractive power, and its object-side surface is convex and its image-side surface is convex;

[0147] The eighth lens element 8 has a positive refractive power, has a convex object-side surface, a convex image-side surface, and both the object-side surface and the image-side surface are aspherical surfaces.

[0148] The optical imaging lens has only the above-mentioned eight lenses with refractive power, and the fifth lens and the sixth lens form a cemented lens, the first lens, the second lens and the third lens of the eight lenses form a compensation group, the fourth lens, the fifth lens, the sixth lens, the seventh lens and the eighth lens form a zoom group, and the diaphragm (not shown in the figure) is located between the third lens and the fourth lens, and the position of the diaphragm changes with the position of the zoom group.

[0149] The optical path diagram of the optical imaging lens in this embodiment at short focal length is as follows: Fig.19 As shown, the optical path diagram at mid-focus is as follows Fig. 20 As shown, the optical path diagram at telephoto is as follows Fig.21 As shown, during the zooming process of the lens, when the lens changes from short focus to long focus, the magnification group moves away from the image plane, and the compensation group moves close to the image plane, that is, the magnification group and the compensation group are close to each other; during the zooming process of the lens, the interval between the magnification group and the compensation group at the short focus position is the largest, and at this time the distance between the magnification group and the target surface (that is, the back working distance of the lens) is the smallest; the interval between the magnification group and the compensation group at the long focus position is the smallest, but a certain minimum center interval is still guaranteed, and at this time the distance between the magnification group and the target surface (that is, the back working distance of the lens) is the largest.

[0150] The detailed optical data of this specific embodiment are as follows Fig. 22 As shown in the figure, the surface data of the aspheric surfaces of the object side and image side of the second, third and eighth lenses are as follows Fig.28 As shown in the part of Example 3.

[0151] Please refer to the MTF curve of visible light (435nm~650nm) Figure 23a-23c ,in Fig.23a This is the MTF curve at short focal length. Figure 23b This is the MTF curve at mid-focus. Fig.23c This is the MTF curve at telephoto.

[0152] For the focal shift curve of visible light (435nm~650nm), please refer to Figure 24a-Figure 24c ,in Fig.24a This is the focal shift curve at short focal length. Figure 24b This is the focal shift curve at mid-focus. Fig.24c This is the focal shift curve for telephoto.

[0153] For the lateral chromatic aberration diagram of visible light (435nm~650nm), please refer to Figure 25a-Figure 25c ,in Fig.25a This is the lateral chromatic aberration diagram at short focal length. Fig.25b This is the lateral chromatic aberration diagram at mid-focus. Fig.25c This is a diagram of lateral chromatic aberration at telephoto.

[0154] For the field curvature and distortion diagram of visible light (435nm~650nm), please refer to Figure 26a-26c A and B, where Fig.26a This is the field curvature and distortion diagram at short focal length. Figure 26b This is the field curvature and distortion diagram at mid-focus. Fig.26c This is the field curvature and distortion diagram at telephoto.

[0155] For the longitudinal aberration diagram of visible light (435nm~650nm), please refer to Figure 27a-Figure 27c ,in Fig.27a is the longitudinal aberration diagram at short focal length, Figure 27b This is the longitudinal aberration diagram at mid-focus. Fig.27c This is the longitudinal aberration diagram at telephoto.

[0156] In this embodiment, the front group uses two meniscus lenses with negative focal length in succession, which can better control the light path; the rear group uses five lenses, which can better correct the system aberrations; so that the imaging quality of the lens is good, the MTF of the full field of view of 120lp / mm is greater than 0.45, and the MTF within the field of view of 0.9 is greater than 0.5; the maximum optical distortion is at the short focus position, the maximum distortion is about -7.5%, and the optical distortion at the mid-focus and long focus positions is less than |0.5%|.

[0157] The optical imaging lens has a combined focal length of 3.53 to 9 mm, a zoom ratio of up to 2.55, a field of view of 90 to 40°, a total system length of less than 46.5 mm TTL, a relative aperture of 1 / 2.5 to 1 / 3.5, an imaging range greater than or equal to φ6.6 mm, and is suitable for 1 / 2.7″ CCD or CMOS chips. The maximum light-transmitting diameter of the lens is less than φ18 mm. The overall structure is compact, the volume is small, the practicability is strong, and the installation and use are extremely convenient.

[0158] Although the present invention has been specifically shown and described in conjunction with the preferred embodiments, it should be understood by those skilled in the art that various changes may be made to the present invention in form and details without departing from the spirit and scope of the present invention as defined by the appended claims, all of which are within the scope of protection of the present invention.

Claims

1. An optical imaging lens, characterized in that: It sequentially includes a first lens to an eighth lens along an optical axis from the object side to the image side. Each of the first lens to the eighth lens includes an object side surface facing the object side and allowing imaging light rays to pass through, and an image side surface facing the image side and allowing imaging light rays to pass through; wherein: The first lens has a negative refractive power. Its object side surface is convex and its image side surface is concave. The second lens has a negative refractive power. Its object side surface is concave and its image side surface is concave, and both its object side surface and image side surface are aspherical surfaces. The third lens has a positive refractive power. Its object side surface is convex and its image side surface is concave, and both its object side surface and image side surface are aspherical surfaces. The fourth lens has a positive refractive power. Its object side surface is convex and its image side surface is convex. The fifth lens has a positive refractive power. Its object side surface is convex and its image side surface is convex. The sixth lens has a negative refractive power. Its object side surface is concave and its image side surface is concave. The seventh lens has a positive refractive power. Its object side surface is convex and its image side surface is convex. The eighth lens has a positive refractive power. Its object side surface is convex, its image side surface is convex, and both its object side surface and image side surface are aspherical surfaces. There are only the above eight lenses with refractive power in this optical imaging lens. The optical imaging lens is sequentially a compensation group with negative optical power and a varifocal group with positive optical power from left to right. The compensation group is composed of the first lens, the second lens, and the third lens, and the varifocal group is composed of the fourth lens, the fifth lens, the sixth lens, the seventh lens, and the eighth lens. The aperture stop is located between the third lens and the fourth lens, and the position of the aperture stop changes following the position of the varifocal group. Wherein, during the zooming process of the optical imaging lens, the stroke of the compensation group is 15 - 17 mm; the stroke of the varifocal group is 4.5 - 5.5 mm.

2. The optical imaging lens according to claim 1, wherein: The fifth lens and the sixth lens form a cemented lens.

3. The optical imaging lens according to claim 2, wherein: The Abbe number of the fifth lens is greater than the Abbe number of the sixth lens, and satisfies vd5 - vd6 > 40, where vd5 and vd6 are the Abbe numbers of the fifth and sixth lenses respectively.

4. The optical imaging lens according to claim 1, wherein: It also satisfies the following condition: 0.9 < |fA / fB| < 1.2, where fA is the focal length of the compensation group and fB is the focal length of the varifocal group.

5. The optical imaging lens according to claim 1, wherein: It also satisfies the following condition: 0.9 < |fA / fB| < 1.2, where fA is the focal length of the compensation group and fB is the focal length of the varifocal group. 1.5 < nd2 < 1.6, 1.6 < nd3 < 1.7, 1.65 < nd4 < 1.75, 1.55 < nd5 < 1.65, 1.7 < nd6 < 1.8, 1.6 ≤ nd7 < 1.7, 1.5 < nd8 < 1.6, where nd1, nd2, nd3, nd4, nd5, nd6, nd7, nd8 are the refractive indices of the first to the eighth lenses respectively.

6. The optical imaging lens according to claim 1, wherein: It also satisfies the following conditions: 50 < vd1 < 60, 50 < vd2 < 60, 15 < vd3 < 25, 50 < vd4 < 60, 65 < vd5 < 75, 20 < vd6 < 30, 55 < vd7 < 65, 55 < vd8 < 65, where vd1, vd2, vd3, vd4, vd5, vd6, vd7, nd8 are the Abbe numbers of the first to the eighth lenses respectively.

7. The optical imaging lens according to claim 1, wherein: It also satisfies the following condition: The object side surfaces and image side surfaces of the second, third, and eighth lenses are all designed as 16th - order even - numbered aspherical surfaces.

Images