Unmanned aerial vehicle aerial optical imaging system

Abstract

This invention provides an optical imaging system for unmanned aerial vehicle (UAV) aerial photography. The system comprises, from the object side to the image side along the optical axis, a first lens with positive optical power, a second lens with negative optical power, a third lens with positive optical power, a fourth lens with negative optical power, a fifth lens with positive optical power, a sixth lens with positive optical power, and a seventh lens with negative optical power. This design employs a single glass aspherical lens and six plastic aspherical lenses. Therefore, it provides a miniaturized, lightweight, large image area, high image quality, and heat-free optical imaging system.

Description

Technical Field

[0001] This utility model relates to the field of optical imaging, and in particular to an optical imaging system for drone aerial photography. Background Technology

[0002] In recent years, with the development of technology, portable electronic products have become increasingly widely used. This has driven the development of camera products for portable electronic devices, leading to a growing demand for miniaturized, high-quality, wide-angle, and calorimetric optical imaging systems.

[0003] For example, existing drone shooting devices and compact cameras such as action cameras generally require high-quality, heat-free lenses, while the market demand for camera products with large-size image sensors is also increasing. This places higher demands on the design of optical imaging systems, resulting in requirements for miniaturization, overall lightweighting, large image size, high image quality, and good thermal defocusing performance. Utility Model Content

[0004] Technical issues

[0005] In view of this, the present invention proposes an optical imaging system that is miniaturized, lightweight, has a large image area, and has high imaging quality.

[0006] Solution

[0007] To solve the above-mentioned technical problems, according to an embodiment of the present invention, an optical imaging system is provided. The lens of the optical imaging system is composed of a first lens with positive optical power, a second lens with negative optical power, a third lens with positive optical power, a fourth lens with negative optical power, a fifth lens with positive optical power, a sixth lens with positive optical power, and a seventh lens with negative optical power, arranged sequentially from the object side to the image side along the optical axis. The object side of the first lens is convex, and the image side is concave; the object side of the second lens is convex, and the image side is concave; the object side of the third lens is convex, and the image side is convex; the object side of the fourth lens is convex, and the image side is concave; the object side of the fifth lens is concave, and the image side is convex; the object side of the sixth lens is convex, and the image side is concave; and the object side of the seventh lens is concave, and the image side is concave.

[0008] In one possible implementation of the above embodiments, the optical imaging system satisfies the following condition:

[0009] 1.3 <f1 / f<1.9

[0010] -2.6 <f2 / f<-2.0

[0011] 0.9 <f3 / f<1.1

[0012] -3.6 <f4 / f<-3.0

[0013] 1.8 <f5 / f<2.4

[0014] 5.7 <f6 / f<6.3

[0015] -1.1 <f7 / f<-0.5

[0016] Wherein, f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, f5 is the focal length of the fifth lens, f6 is the focal length of the sixth lens, f7 is the focal length of the seventh lens, and f is the focal length of the optical imaging system.

[0017] In one possible implementation of the above embodiments, the following condition is satisfied:

[0018] 1.50≤Nd1≤1.70

[0019] 50≤Vd1≤70

[0020] 1.55≤Nd2≤1.70

[0021] 20≤Vd2≤40

[0022] 1.70≤Nd3≤1.90

[0023] 50≤Vd3≤70

[0024] 1.55≤Nd4≤1.70

[0025] 20≤Vd4≤40

[0026] 1.50≤Nd5≤1.70

[0027] 50≤Vd5≤70

[0028] 1.50≤Nd6≤1.70

[0029] 50≤Vd6≤70

[0030] 1.50≤Nd7≤1.70

[0031] 50≤Vd7≤70

[0032] Wherein, Nd1 is the refractive index of the first lens, Vd1 is the dispersion coefficient of the first lens, Nd2 is the refractive index of the second lens, Vd2 is the dispersion coefficient of the second lens, Nd3 is the refractive index of the third lens, Vd3 is the dispersion coefficient of the third lens, Nd4 is the refractive index of the fourth lens, Vd4 is the dispersion coefficient of the fourth lens, Nd5 is the refractive index of the fifth lens, Vd5 is the dispersion coefficient of the fifth lens, Nd6 is the refractive index of the sixth lens, Vd6 is the dispersion coefficient of the sixth lens, Nd7 is the refractive index of the seventh lens, and Vd7 is the dispersion coefficient of the seventh lens.

[0033] In one possible implementation of the above embodiments, the first lens, the second lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens are plastic lenses, and the third lens is a glass lens.

[0034] In one possible implementation of the above embodiments, the object-side surface and the image-side surface of both the sixth and seventh lenses are inverted.

[0035] In one possible implementation of the above embodiments, the following condition is satisfied:

[0036] 0.6 <f / TTL<1.0,

[0037] Where f is the focal length of the optical imaging system, and TTL is the on-axis distance from the object side of the first lens to the imaging surface of the optical imaging system.

[0038] In one possible implementation of the above embodiments, the optical imaging system satisfies the following condition:

[0039] 1.0≤CT6 / ET6≤1.5

[0040] 0.6 ≤ ET7 / CT7 ≤ 1.0

[0041] Wherein, CT6 is the center thickness of the sixth lens, ET6 is the edge thickness of the sixth lens, CT7 is the center thickness of the seventh lens, and ET7 is the edge thickness of the seventh lens.

[0042] In one possible implementation of the above embodiments, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens are aspherical lenses.

[0043] In one possible implementation of the above embodiments, an aperture stop is disposed between the second lens and the third lens.

[0044] Beneficial effects

[0045] According to the optical imaging system of this utility model, by adopting the structural design of the first to seventh lenses described above, the horizontal viewing angle can reach more than 70 degrees, thus providing a wide viewing angle. In addition, the total optical length can be less than or equal to 10mm, reducing the system size and achieving miniaturization, while also achieving a light overall weight. Furthermore, it has a large image plane, making it suitable for large-size image sensors, and provides better imaging quality.

[0046] Other features and aspects of the present invention will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0047] The accompanying drawings, which are included in and form part of this specification, illustrate exemplary embodiments, features, and aspects of the present invention together with the specification and serve to explain the principles of the present invention.

[0048] Figure 1 This is a lens structure diagram of the optical imaging system involved in this embodiment.

[0049] Figure 2 This is a schematic diagram illustrating the MTF (modulation transfer function) of the optical imaging system involved in this embodiment.

[0050] Figure 3 This is a defocus curve diagram showing the optical imaging system involved in this embodiment at a normal temperature of 20°C.

[0051] Figure 4 This is a defocus curve diagram showing the optical imaging system involved in this embodiment at a high temperature of 70°C.

[0052] Figure 5 This is a defocus curve diagram showing the optical imaging system involved in this embodiment at a low temperature of -20°C.

[0053] List of reference numerals

[0054] 1: Optical imaging system; L1: First lens; L2: Second lens; L3: Third lens; L4: Fourth lens; L5: Fifth lens; L6: Sixth lens; L7: Seventh lens; STO: Aperture stop; IR: Infrared filter; IMA: Imaging surface. Detailed Implementation

[0055] Various exemplary embodiments, features, and aspects of the present invention will now be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings denote elements that have the same or similar functions. Although various aspects of the embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.

[0056] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[0057] Furthermore, to better illustrate this utility model, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that this utility model can be implemented even without certain specific details. In some instances, methods, means, components, and circuits well-known to those skilled in the art have not been described in detail, in order to highlight the main points of this utility model.

[0058] The optical imaging system described in this embodiment can be applied to devices such as drones, action cameras, and facial recognition devices. The optical imaging system of this embodiment consists of seven lenses, has a simple structure, and exhibits excellent optical performance through the combination of lenses with different structures.

[0059] The basic structure of the optical imaging system involved in this embodiment will be described.

[0060] In its basic structure, the optical imaging system consists of a first lens with positive optical power, a second lens with negative optical power, a third lens with positive optical power, a fourth lens with negative optical power, a fifth lens with positive optical power, a sixth lens with positive optical power, and a seventh lens with negative optical power, arranged sequentially along the optical axis from the object side to the image side. Specifically, the object side of the first lens is convex, and the image side is concave. The object side of the second lens is convex, and the image side is concave. The object side of the third lens is convex, and the image side is convex. The object side of the fourth lens is convex, and the image side is concave. The object side of the fifth lens is concave, and the image side is convex. The object side of the sixth lens is convex, and the image side is concave. The object side of the seventh lens is concave, and the image side is concave.

[0061] By employing the structural design of the first to seventh lenses described above, the optical imaging system of this embodiment achieves a horizontal viewing angle of over 70 degrees, thus providing a wide viewing angle. Furthermore, the total optical length of the optical imaging system of this embodiment is less than or equal to 10 mm, reducing the overall volume and achieving miniaturization. It is also lightweight, and the imaging surface size reaches 1 / 1.3 inch, making it suitable for larger image sensors. In addition, by combining lenses with different structures and rationally allocating the optical power of each lens, high-definition resolution and excellent optical performance can be obtained.

[0062] Furthermore, the optical imaging system described in this embodiment can also satisfy the following conditional expression.

[0063] 1.3 <f1 / f<1.9

[0064] -2.6 <f2 / f<-2.0

[0065] 0.9 <f3 / f<1.1

[0066] -3.6 <f4 / f<-3.0

[0067] 1.8 <f5 / f<2.4

[0068] 5.7 <f6 / f<6.3

[0069] -1.1 <f7 / f<-0.5

[0070] Where f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, f5 is the focal length of the fifth lens, f6 is the focal length of the sixth lens, f7 is the focal length of the seventh lens, and f is the focal length of the optical imaging system.

[0071] In the optical imaging system described in this embodiment, each lens satisfies the above-described conditional formula, resulting in a reasonable distribution ratio of optical power among the lenses. Furthermore, the object-side surface of the first lens is convex, which reduces the angle of incidence of peripheral light rays onto the first lens, helps reduce surface reflection, makes the optical imaging system more suitable for wide-angle designs, and facilitates an increased field of view.

[0072] Furthermore, the optical imaging system described in this embodiment can also satisfy the following conditional expression.

[0073] 1.50≤Nd1≤1.70

[0074] 50≤Vd1≤70

[0075] 1.55≤Nd2≤1.70

[0076] 20≤Vd2≤40

[0077] 1.70≤Nd3≤1.90

[0078] 50≤Vd3≤70

[0079] 1.55≤Nd4≤1.70

[0080] 20≤Vd4≤40

[0081] 1.50≤Nd5≤1.70

[0082] 50≤Vd5≤70

[0083] 1.50≤Nd6≤1.70

[0084] 50≤Vd6≤70

[0085] 1.50≤Nd7≤1.70

[0086] 50≤Vd7≤70

[0087] Wherein, Nd1 is the refractive index of the first lens, Vd1 is the dispersion coefficient of the first lens, Nd2 is the refractive index of the second lens, Vd2 is the dispersion coefficient of the second lens, Nd3 is the refractive index of the third lens, Vd3 is the dispersion coefficient of the third lens, Nd4 is the refractive index of the fourth lens, Vd4 is the dispersion coefficient of the fourth lens, Nd5 is the refractive index of the fifth lens, Vd5 is the dispersion coefficient of the fifth lens, Nd6 is the refractive index of the sixth lens, Vd6 is the dispersion coefficient of the sixth lens, Nd7 is the refractive index of the seventh lens, and Vd7 is the dispersion coefficient of the seventh lens.

[0088] In this embodiment, by ensuring that the refractive indices of each lens satisfy the aforementioned conditional expression, it is beneficial to achieve a reasonable distribution of optical power, and to better correct aberrations such as spherical aberration and field curvature, thereby improving the resolution of the optical imaging system. Furthermore, to meet the miniaturization requirements of the optical imaging system, i.e., to minimize the overall length, the third lens is made of a high-refractive-index material that satisfies the aforementioned refractive index relationship. This effectively improves off-axis aberrations, facilitates rapid changes in light direction, and allows for correction of the exit angle of the optical imaging system, thus enabling better matching of the photosensitive element. Additionally, by ensuring that the dispersion coefficients of each lens satisfy the aforementioned conditional expression, it is beneficial to correct chromatic aberration problems caused by wide-angle lenses.

[0089] In this embodiment, the first, second, fourth, fifth, sixth, and seventh lenses can all be made of plastic, while the third lens is made of glass. By employing a hybrid design of glass and plastic lenses, compared to a design using all-plastic lenses, the impact of temperature drift on the optical imaging system can be reduced, which helps to suppress temperature drift problems and lowers the risk of defocusing when shooting in harsh environments. Furthermore, it also helps to further reduce the weight of the optical imaging system, thereby enabling further miniaturization.

[0090] In this embodiment, since the optical imaging system satisfies the above conditional expression "0.9 < f3 / f < 1.1", the third lens bears the vast majority of the system's optical power. The system is relatively sensitive to the refractive index change of the third lens. Once the refractive index of the third lens changes with temperature, it will have a greater impact on the entire optical imaging system. Therefore, in this embodiment, the third lens is set as a glass lens. By utilizing the characteristic that the optical power of a glass lens is insensitive to temperature change, the change in optical power caused by temperature change is minimized through the third lens, the temperature drift phenomenon is improved, and the risk of defocus during shooting in a harsh environment is reduced. Thus, the optical imaging system can well control the temperature drift problem of the optical imaging system and can meet the usage requirements in more different environments.

[0091] In this embodiment, it is also possible that the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens are aspherical lenses. Due to the large degree of freedom of the aspherical surface type, the ability of an aspherical lens to deflect light rays and correct aberrations is significantly stronger than that of a spherical lens. Therefore, by setting the first lens to the seventh lens as aspherical lenses, it is beneficial to improve the resolution of the optical imaging system and correct the distortion of the optical imaging system. In addition, it is also beneficial to correct the angle of the outgoing light rays of the optical imaging system, so as to better match the photosensitive element.

[0092] In this embodiment, it is also possible that both the object side and the image side of the sixth lens and the seventh lens have reverse curvature. By setting it to this structure, the distortion of the optical imaging system and the ray aberrations at different apertures can be effectively corrected, and it is beneficial to control the angle at which off-axis field light rays enter the photosensitive element.

[0093] In addition, the optical imaging system involved in this embodiment can also satisfy the following conditional expressions.

[0094] 0.6 < f / TTL < 1.0

[0095] Where f is the focal length of the optical imaging system, and TTL is the axial distance from the object side of the first lens to the imaging surface of the optical imaging system.

[0096] By making the focal length of the optical imaging system and the above axial distance satisfy the above conditional expressions, it is possible to effectively shorten the length of the optical imaging system while maintaining a high imaging quality.

[0097] In addition, the optical imaging system involved in this embodiment can also satisfy the following conditional expressions.

[0098] 1.0 ≤ CT6 / ET6 ≤ 1.5

[0099] 0.6 ≤ ET7 / CT7 ≤ 1.0

[0100] Wherein, CT6 is the center thickness of the sixth lens, ET6 is the edge thickness of the sixth lens, CT7 is the center thickness of the seventh lens, and ET7 is the edge thickness of the seventh lens.

[0101] By designating the sixth and seventh lenses to satisfy the above relationship, it is beneficial to the molding process of the sixth and seventh lenses, especially when the sixth and seventh lenses are plastic lenses. It is beneficial to the moldability and uniformity of the plastic lenses, making the sixth and seventh lenses easier to process and manufacture.

[0102] In this embodiment, an aperture stop can also be disposed between the second and third lenses. This arrangement helps to increase the field of view of the optical imaging system, better balance the exit angle of the optical imaging system, and thus facilitate matching with the corresponding image sensor. Furthermore, this simple structure allows for adjustment of the beam intensity. The aperture can reach F2.8, providing high resolution, enabling the optical imaging system to meet high-definition quality requirements and possess a wide viewing angle.

[0103] The optical imaging system will now be described in detail with reference to the accompanying drawings, using specific examples.

[0104] Example

[0105] Figure 1 This is a lens structure diagram of the optical imaging system 1 involved in this embodiment. Figure 1 As shown, the optical imaging system 1, from the object side to the image side along the optical axis, includes a first lens L1, a second lens L2, an aperture stop STO, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an infrared filter IR, and an imaging plane IMA. The aperture stop STO is not a necessary component and may be omitted. Similarly, the infrared filter IR is not a necessary component and may be omitted.

[0106] The first lens L1 has a positive optical power, a convex object-side surface, and a concave image-side surface. The second lens L2 has a negative optical power, a convex object-side surface, and a concave image-side surface. The third lens L3 has a positive optical power, a convex object-side surface, and a convex image-side surface. The fourth lens L4 has a negative optical power, a convex object-side surface, and a concave image-side surface. The fifth lens L5 has a positive optical power, a concave object-side surface, and a convex image-side surface. The sixth lens L6 has a positive optical power, a convex object-side surface with inversion, and a concave image-side surface with inversion. The seventh lens L7 has a negative optical power, a concave object-side surface with inversion, and a concave image-side surface with inversion.

[0107] In this embodiment, preferably, the first lens L1, the second lens L2, the fourth lens L4, the fifth lens L5, the sixth lens L6, and the seventh lens L7 are all made of plastic material, and the third lens L3 is made of glass material. By adopting a hybrid design scheme of glass lenses and plastic lenses, it is beneficial to suppress the temperature drift problem and reduce the risk of defocus during shooting in harsh environments. In addition, it can effectively improve the miniaturization degree of the optical imaging system 1 and reduce the weight.

[0108] In this embodiment, preferably, the first lens L1 to the sixth lens L7 are all aspherical lenses. The reason is that: the aspherical surface has the characteristic of large degrees of freedom. Therefore, the aspherical lens has stronger ability to deflect light and correct aberration than the spherical lens, can further improve the resolution of the optical imaging system 1 and further correct the distortion of the optical imaging system 1, and is also beneficial to correcting the exit light angle of the optical imaging system 1 so as to better match the photosensitive element.

[0109] In this embodiment, by setting the object side and the image side of the sixth lens L6 and the seventh lens L7 to have reverse curvature like this, it is possible to effectively correct the distortion of the optical imaging system 1 and the light aberration at different apertures, and is beneficial to controlling the angle of light incident on the photosensitive element in the off-axis field of view.

[0110] Preferably, when the focal lengths of the first lens L1 to the seventh lens L7 are set as f1 to f7 respectively, and the focal length of the optical imaging system 1 is set as f, the focal lengths of the first lens L1 to the seventh lens L7 satisfy the following conditional expressions: 1.3 < f1 / f < 1.9, -2.6 < f2 / f < -2.0, 0.9 < f3 / f < 1.1, -3.6 < f4 / f < -3.0, 1.8 < f5 / f < 2.4, 5.7 < f6 / f < 6.3, -1.1 < f7 / f < -0.5. By making the focal lengths of the first lens L1 to the seventh lens L7 satisfy the above conditional expressions, it is possible to ensure the good optical performance of the lenses of the optical imaging system 1 and achieve wide-angle imaging.

[0111] Preferably, when the refractive indices of the first lens L1 to the seventh lens L7 are set as Nd1 to Nd7 respectively, and the Abbe numbers of the first lens L1 to the seventh lens L7 are set as Vd1 to Vd7 respectively, the refractive indices and Abbe numbers of the first lens L1 to the seventh lens L7 satisfy the following conditional expressions: 1.50 ≤ Nd1 ≤ 1.70, 50 ≤ Vd1 ≤ 70, 1.55 ≤ Nd2 ≤ 1.70, 20 ≤ Vd2 ≤ 40, 1.70 ≤ Nd3 ≤ 1.90, 50 ≤ Vd3 ≤ 70, 1.55 ≤ Nd4 ≤ 1.70, 20 ≤ Vd4 ≤ 40, 1.50 ≤ Nd5 ≤ 1.70, 50 ≤ Vd5 ≤ 70, 1.50 ≤ Nd6 ≤ 1.70, 50 ≤ Vd6 ≤ 70, 1.50 ≤ Nd7 ≤ 1.70, 50 ≤ Vd7 ≤ 70. By making the refractive indices of the first lens L1 to the seventh lens L7 satisfy the above conditional expressions, it is beneficial to achieve a reasonable distribution of the optical power, and can preferably correct aberrations such as spherical aberration and field curvature, thereby improving the resolution of the optical imaging system 1. In addition, by setting the third lens L3 to have a high refractive index, the off-axis aberration can be effectively improved, which is beneficial to the rapid change of the light direction and the correction of the exit angle of the optical imaging system 1, is beneficial to shortening the overall length, realizing miniaturization of the optical imaging system 1 and can better match the photosensitive element. In addition, by making the Abbe numbers of the first lens L1 to the seventh lens L7 satisfy the above conditional expressions, it is beneficial to correct the chromatic aberration problem caused by the large wide angle.

[0112] Preferably, when the focal length of the optical imaging system 1 is set as f, and the on-axis distance from the object side surface of the first lens L1 to the imaging surface IMA is set as TTL, the optical imaging system 1 satisfies the following conditional expression: 0.6 < f / TTL < 1.0. By setting it like this, the optical imaging system 1 can effectively shorten the system length while maintaining a high imaging quality.

[0113] Preferably, when the central thickness of the sixth lens L6 is set as CT6, the edge thickness of the sixth lens L6 is set as ET6, the central thickness of the seventh lens L7 is set as CT7, and the edge thickness of the seventh lens L7 is set as ET7, the sixth lens L6 and the seventh lens L7 satisfy the following conditional expressions: 1.0 ≤ CT6 / ET6 ≤ 1.5, 0.6 ≤ ET7 / CT7 ≤ 1.0. By making the structures of the sixth lens L6 and the seventh lens L7 satisfy the above conditional expressions, it is beneficial to the molding processes of the sixth lens L6 and the seventh lens L7. Especially when the sixth lens L6 and the seventh lens L7 are plastic lenses, it is beneficial to the molding property and uniformity of the plastic lenses, making the sixth lens L6 and the seventh lens L7 easy to process and manufacture.

[0114] In this embodiment, by configuring an aperture stop STO between the second lens L2 and the third lens L3, the beam intensity can be adjusted with a simple structure. Furthermore, this increases the field of view of the optical imaging system 1, better balances the emission angle of the optical imaging system 1, and thus facilitates matching with the corresponding image sensor.

[0115] The design parameters of the optical imaging system 1 involved in this embodiment can be shown in the table below.

[0116]

[0117] In the table above, the units for surface radius and thickness are millimeters. Surfaces marked with "*" indicate aspherical surfaces. Furthermore, the surface profile of aspherical lenses satisfies the following relationship:

[0118]

[0119] In the above formula, parameter c is the curvature corresponding to the lens radius, y is the radial coordinate, and the unit of the radial coordinate is the same as the unit of the lens length. k is the conic section coefficient. When k is less than -1, the surface profile of the lens is a hyperbola; when k equals -1, the surface profile of the lens is a parabola; when k is between -1 and 0, the surface profile of the lens is an ellipse; when k equals 0, the surface profile of the lens is a circle; and when k is greater than 0, the surface profile of the lens is an elongated ellipse. a4, a6, a8, a 10 a 12 a 14 These are the surface coefficients corresponding to the radial coordinates of the fourth, sixth, eighth, tenth, twelfth, and fourteenth orders, respectively. The values ​​of the conic coefficient k are shown in the table below, and the other detailed aspherical parameters are shown in the table below.

[0120]

[0121] Figure 2 This is a schematic diagram showing the MTF (modulation transfer function) of the optical imaging system 1 involved in this embodiment. Figure 3 This is a defocus curve diagram showing the optical imaging system 1 involved in this embodiment at a normal temperature of 20°C. Figure 4 This is a defocus curve diagram showing the optical imaging system 1 involved in this embodiment at a high temperature of 70°C. Figure 5 This is a defocus curve diagram showing the optical imaging system 1 involved in this embodiment at a low temperature of -20°C.

[0122] Depend on Figure 2As can be seen, the optical imaging system 1 involved in this embodiment, by adopting the structural design of the first to seventh lenses described above, achieves a horizontal viewing angle of over 70 degrees and an aperture of F2.8. Therefore, the optical imaging system 1 has high resolution, meets the requirements of high-definition quality, and possesses a wide viewing angle. Furthermore, the total optical length of the optical imaging system 1 is less than 10mm, exhibiting a short total optical length, reducing the overall volume and thus achieving a high degree of miniaturization. It is also lightweight. In addition, the imaging surface size reaches 1 / 1.3 inches, making it suitable for larger image sensors.

[0123] Furthermore, the hybrid design using both glass and plastic lenses helps suppress temperature drift and reduces the risk of focus loss when shooting in harsh environments. According to Figures 3-5 The defocus MTF curves of the optical imaging system 1 shown are displayed under ambient temperature of 20℃, high temperature of 70℃, and low temperature of -20℃. It can be seen that the optical imaging system 1 involved in this embodiment has a small temperature drift and performs well in harsh environments of high and low temperatures, which is beneficial to meeting the shooting requirements in special environments.

[0124] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the protection scope of the claims.

Claims

1. An optical imaging system, characterized in that, The optical imaging system consists of a first lens with positive optical power, a second lens with negative optical power, a third lens with positive optical power, a fourth lens with negative optical power, a fifth lens with positive optical power, a sixth lens with positive optical power, and a seventh lens with negative optical power, arranged sequentially along the optical axis from the object side to the image side. In this configuration, 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 also convex. The object-side surface of the fourth lens is convex, and the image-side surface is concave. The object-side surface of the fifth lens is concave, and the image-side surface is convex. The object-side surface of the sixth lens is convex, and the image-side surface is concave. The object-side surface of the seventh lens is concave, and the image-side surface is also concave.

2. The optical imaging system of claim 1, wherein, The following conditions must be met. 1.3 <f1 / f<1.9, -2.6 <f2 / f<-2.0, 0.9 <f3 / f<1.1, -3.6 <f4 / f<-3.0, 1.8 <f5 / f<2.4, 5.7 <f6 / f<6.3, -1.1 <f7 / f<-0.5, Where f1 is the focal length of the first lens. f2 is the focal length of the second lens. f3 is the focal length of the third lens. f4 is the focal length of the fourth lens. f5 is the focal length of the fifth lens. f6 is the focal length of the sixth lens. f7 is the focal length of the seventh lens. f is the focal length of the optical imaging system.

3. The optical imaging system of claim 1, wherein, The following conditions must be met. 1.50≤Nd1≤1.70, 50≤Vd1≤70, 1.55≤Nd2≤1.70, 20≤Vd2≤40, 1.70≤Nd3≤1.90, 50≤Vd3≤70, 1.55≤Nd4≤1.70, 20≤Vd4≤40, 1.50≤Nd5≤1.70, 50≤Vd5≤70, 1.50≤Nd6≤1.70, 50≤Vd6≤70, 1.50≤Nd7≤1.70, 50≤Vd7≤70, Wherein, Nd1 is the refractive index of the first lens. Vd1 is the dispersion coefficient of the first lens. Nd2 is the refractive index of the second lens. Vd2 is the dispersion coefficient of the second lens. Nd3 is the refractive index of the third lens. Vd3 is the dispersion coefficient of the third lens. Nd4 is the refractive index of the fourth lens. Vd4 is the dispersion coefficient of the fourth lens. Nd5 is the refractive index of the fifth lens. Vd5 is the dispersion coefficient of the fifth lens. Nd6 is the refractive index of the sixth lens. Vd6 is the dispersion coefficient of the sixth lens. Nd6 is the refractive index of the sixth lens. Vd6 is the dispersion coefficient of the sixth lens. Nd7 is the refractive index of the seventh lens. Vd7 is the dispersion coefficient of the seventh lens.

4. The optical imaging system according to claim 2, characterized in that, The first lens, the second lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens are plastic lenses, and the third lens is a glass lens.

5. The optical imaging system according to claim 1, characterized in that, The object-side and image-side surfaces of the sixth and seventh lenses are both inverted.

6. The optical imaging system of claim 1, wherein, The following condition must be met: 0.6 <f / TTL<1.0, Where f is the focal length of the optical imaging system. TTL is the on-axis distance from the object surface of the first lens to the imaging surface of the optical imaging system.

7. The optical imaging system of claim 1, wherein, The following condition must be met: 1.0 ≤ CT6 / ET6 ≤ 1.

5. 0.6≤ET7 / CT7≤1.0 Wherein, CT6 is the center thickness of the sixth lens. ET6 is the edge thickness of the sixth lens. CT7 is the center thickness of the seventh lens. ET7 is the edge thickness of the seventh lens.

8. The optical imaging system according to any one of claims 1 to 7, characterized in that, The first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens are aspherical lenses.

9. The optical imaging system according to claim 1, characterized in that, An aperture stop is disposed between the second lens and the third lens.

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