Optical imaging system and optical lens

Abstract

The present application relates to the field of optical imaging technology, and more particularly to an optical imaging system and an optical lens, the optical imaging system comprising in order from an object side to an image side along an optical axis a first lens having a negative focal power and being made of a first material, a second lens having a positive focal power and being made of a second material, a stop, a third lens having a positive focal power and being made of a third material, a fourth lens having a negative focal power and being made of the second material, and a fifth lens having a positive focal power and being made of the first material. Through the above configuration, the optical imaging system realizes day and night confocal, overcomes the heat-sensitive defects caused by multiple plastic lenses, and realizes the compensation of focal length drift caused by environmental temperature changes in a wide temperature range.

Description

Technical Field

[0001] This invention relates to the field of optical imaging technology, and more particularly to an optical imaging system and an optical lens. Background Technology

[0002] Most existing security surveillance lenses are constructed using all-glass or glass-plastic hybrid materials. As security surveillance evolves towards ultra-high definition, low-light full-color, and wide field of view, the market demands lenses that simultaneously possess large apertures, ultra-wide angles, and all-weather (i.e., day and night confocal) imaging capabilities. However, existing designs, while increasing the field of view, struggle to address the significant aberrations introduced by large apertures, including decreased edge resolution, vignetting in low relative illumination, and purple fringing under high contrast, among others. Specifically, under the dual extreme conditions of a large field of view and a large aperture, the refraction angle of light at the edge of the field of view is extremely large, resulting in a sharp drop in relative illumination, severe vignetting, and unsatisfactory purple fringing correction at the edges. When switching between daytime (e.g., visible light) and nighttime (e.g., near-infrared light), the dispersion characteristics of the constituent materials have not been specifically adjusted, making it easy for the imaging to produce focal plane shift, resulting in ghosting in nighttime images. When adapting to high-pixel, large-area sensors, the resolution difference between the edge and center parts is large, which cannot fully utilize the sensor's performance. Existing glass-plastic hybrid lenses are prone to severe thermal drift in extreme high / low temperature environments due to the inherently high coefficient of thermal expansion and temperature coefficient of refractive index (dn / dT) of plastic, resulting in image blurring and ultimately making the lens unable to meet the security requirements of harsh outdoor environments. Summary of the Invention

[0003] This invention provides an optical imaging system and an optical lens to solve the defect of focal length drift caused by material properties in existing optical lenses over a wide temperature range, and to achieve a day and night cofocal distance and a stable focal length without drift over a wide temperature range.

[0004] According to a first aspect of the present invention, an optical imaging system is provided, comprising, along the optical axis from the object-side side to the image-side side, the following components in sequence: The first lens has negative optical power and is made of a first material; The second lens has positive optical power and is made of a second material; Aperture; The third lens has positive optical power and is made of a third material; The fourth lens has negative optical power and is made of the second material; The fifth lens has positive optical power and is made of the first material.

[0005] In the optical imaging system provided by the present invention, the first material and the second material are different plastics from each other, and / or the third material is glass.

[0006] According to the optical imaging system provided by the present invention, the first lens is an aspherical lens, wherein its object-facing side surface is convex with a radius of curvature of 4.21 mm to 5.85 mm; its image-facing side surface is concave with a radius of curvature of 1.56 mm to 3.21 mm; and / or The first lens f1 and the effective focal length f of the optical imaging system satisfy -2.1≤f1 / f≤-1.85.

[0007] According to the optical imaging system provided by the present invention, the second lens is an aspherical lens, wherein its object-side surface is concave with a radius of curvature of -4.81 mm to -6.24 mm; its image-side surface is convex with a radius of curvature of -4.23 mm to -6.21 mm; and / or The second lens f2 and the effective focal length f of the optical imaging system satisfy 8.0≤f2 / f≤8.5.

[0008] According to the optical imaging system provided by the present invention, the third lens is a spherical lens, the side surface facing the object side is convex, and its radius of curvature is 5.45 mm to 9.12 mm; the side surface facing the image side is convex, and its radius of curvature is -9.23 mm to -6.34 mm; and / or The third lens f3 and the effective focal length f of the optical imaging system satisfy 1.9≤f3 / f≤2.1.

[0009] According to the optical imaging system provided by the present invention, the fourth lens is an aspherical lens, wherein its object-side surface is concave with a radius of curvature of -15.02 mm to -12.76 mm; its image-side surface is concave with a radius of curvature of 2.54 mm to 4.31 mm; and / or The fourth lens f4 and the effective focal length f of the optical imaging system satisfy -1.25≤f4 / f≤-1.2.

[0010] According to the optical imaging system provided by the present invention, the fifth lens is an aspherical lens, wherein its object-facing side surface is convex with a radius of curvature of 2.23 mm to 4.52 mm; its image-facing side surface is convex with a radius of curvature of -6.42 mm to -3.85 mm; and / or The fifth lens f5 and the effective focal length f of the optical imaging system satisfy 1.18≤f5 / f≤1.25.

[0011] According to the optical imaging system provided by the present invention, the aspherical surfaces of the first lens, the second lens, the fourth lens, and the fifth lens satisfy the following: Where Z is the sag of the lens along the optical axis, k is the conic coefficient of the quadratic surface, γ is the lens height, c is the lens curvature, and A, B, C, D, E, F, and G are the coefficients of the 4th, 6th, 8th, 10th, 12th, 14th, and 16th order terms of the aspherical polynomial.

[0012] According to the optical imaging system provided by the present invention, the Abbe number of the first lens and the fifth lens is greater than 55, and / or the Abbe number of the second lens and the fourth lens is less than 24.

[0013] According to a second aspect of the invention, an optical lens is also provided, comprising a lens barrel and an optical imaging system according to the first aspect of the invention, the optical imaging system being mounted inside the lens barrel.

[0014] The optical imaging system provided by this invention utilizes lenses constructed from different materials. This specific material arrangement achieves a large aperture and ultra-wide-angle imaging while effectively correcting aberrations, reducing purple fringing at the field of view, ensuring high relative illumination, and enabling day and night confocal focusing. It overcomes the heat sensitivity issues caused by multiple plastic lenses, and compensates for focal length drift caused by ambient temperature changes over a wide temperature range. Furthermore, this configuration effectively controls the defocusing of infrared light relative to the visible light focal plane, allowing for continuous high-resolution image output without refocusing when switching from full-color daytime mode to infrared nighttime mode. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the layout of the optical imaging system provided by the present invention.

[0017] Figure 2 This is a graph showing the relationship between the field of view and relative illumination of the optical imaging system provided by this invention.

[0018] Figures 3 to 12 These are curves showing the relationship between chromatic aberration and secondary spectral achromatic aberration of the optical imaging system provided by this invention at different object side angles.

[0019] Figure 13This is a graph showing the infrared defocusing amount of the optical imaging system provided by this invention.

[0020] Figures 14 to 15 These are curves showing the defocusing amount of the optical imaging system provided by this invention under different ambient temperatures.

[0021] Figure label: 1. First lens; 2. Second lens; 3. Third lens; 4. Fourth lens; 5. Fifth lens; 6. Aperture stop; 7. Protective glass; O. Object side; I. Image side. Detailed Implementation

[0022] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0023] In the description of the embodiments of the present invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0024] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to fixed connections or detachable connections, wherein a fixed connection can include an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention based on the specific circumstances.

[0025] In embodiments of the present invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0026] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0027] The following is combined with Figures 1 to 15 The optical imaging system and optical lens of the present invention are described.

[0028] Figure 1 This is a schematic diagram of the layout of the optical imaging system provided by the present invention, as shown below. Figure 1 As shown, the optical imaging system includes, along the optical axis from the object side O to the image side I, a first lens 1, a second lens 2, an aperture stop 6, a third lens 3, a fourth lens 4, and a fifth lens 5. The first lens 1 has negative optical power and is made of a first material; the second lens 2 has positive optical power and is made of a second material; the third lens 3 has positive optical power and is made of a third material; the fourth lens 4 has negative optical power and is made of a second material; and the fifth lens 5 has positive optical power and is made of the first material. Here, the first, second, and third materials are materials with different compositions. The aperture stop 6 is positioned between the second lens 2 and the third lens 3, separating them to a certain extent. Therefore, even if the second lens 2 and the third lens 3 are arranged sequentially along the optical axis, both can have positive optical power.

[0029] Aperture stop 6 is used to limit the amount of light incident or to limit the size of the field of view. In this embodiment, aperture stop 6 is an aperture stop, and the aperture value f# of aperture stop 6 can be set to ≤1.65, for example, 1.6, where the aperture value refers to the ratio of the lens focal length to the lens light-transmitting diameter. This indicates that aperture stop 6 has a relatively large aperture value. In addition, the center thickness of aperture stop 6 along the optical axis can be set to approximately 2.42 mm.

[0030] With the above configuration, the aberrations of the optical imaging system are well corrected while achieving large aperture and ultra-wide-angle imaging. This reduces the purple fringing problem at the edge of the field of view, ensures high relative illumination of the image, and achieves day and night confocal imaging. It also overcomes the thermal sensitivity defects caused by multiple plastic lenses and achieves focal length drift caused by changes in ambient temperature over a wide temperature range.

[0031] Moreover, through the above configuration, such as Figure 13 As shown, this optical imaging system not only solves or at least reduces the chromatic aberration problem to a certain extent, but also controls the amount of infrared light defocusing relative to the focal plane of visible light. This allows the optical imaging system to continuously output images with high resolution without refocusing when switching from full-color mode in the daytime to infrared mode in the nighttime.

[0032] In some embodiments, both the first material and the second material are plastic materials, but their specific compositions differ. For example, the first material may be a cyclic olefin optical plastic with the following optical properties: a transmittance of approximately 92%, a refractive index of approximately 1.53, and a low birefringence, making it suitable for applications requiring precision optics. Conversely, the second material may be an amorphous cyclic resin with the following optical properties: a transmittance of approximately 96%, making it suitable for applications requiring high transparency, such as optical lenses.

[0033] In addition, the third material is glass, specifically phosphate optical glass, which is suitable for applications with high requirements for chromatic aberration control, such as achromatic lenses.

[0034] Figures 3 to 12 These are curves showing the relationship between chromatic aberration and second-order spectral achromatic aberration of the optical imaging system provided by this invention at different object side angles, as shown below. Figures 3 to 12 As shown, by combining different components of plastic and glass, the chromatic aberration and secondary spectrum of this optical imaging system are controlled, and purple fringing is well controlled in high-contrast backlighting scenarios. The secondary spectrum refers to the residual chromatic aberration that remains at the common focal point of a third wavelength relative to the first two wavelengths after the optical system has corrected for chromatic aberration at two specific wavelengths (e.g., red and blue light). This residual chromatic aberration is unavoidable in achromatic systems (e.g., cemented doublets).

[0035] The above configuration constructs a hybrid optical imaging system architecture of glass and plastic. By combining specific materials, it achieves a wide-angle (e.g., 108°) and large aperture (i.e., f#1.6 mentioned above) while also being small in size, lightweight, high-performance, and low in cost.

[0036] Furthermore, the distribution of positive / negative optical power of each lens, combined with the mutually canceling thermal properties of the first, second, and third materials, ensures that the defocus amount of the optical imaging system is always controlled within the acceptable tolerance range of the optical imaging system in a wide temperature range of -30℃ to 80℃, effectively offsetting the focal length drift caused by changes in ambient temperature.

[0037] Figures 14 to 15These are curves showing the defocusing amount of the optical imaging system provided by this invention under different ambient temperatures, as shown below. Figures 14 to 15 As shown, this optical imaging system breaks through the operating temperature bottleneck of the traditional glass-plastic hybrid architecture. In extreme environmental tests ranging from -30℃ to 80℃, the defocusing and resolution degradation of this optical imaging system are within a strictly acceptable range, and the imaging images remain clear and sharp under all seasons and day-night temperature differences.

[0038] Figure 2 This is a graph showing the relationship between the field of view and relative illumination of the optical imaging system provided by this invention, such as... Figure 2 As shown, since the first material, the second material and the third material have their own different dispersion characteristics, and in particular, the combination of the first material, the second material and the third material effectively eliminates the second-order spectrum, focuses the light of different wavelengths on the same plane (e.g., the image side I), thereby greatly suppressing the purple fringing phenomenon and ensuring that near-infrared light and visible light are confocal.

[0039] In some embodiments, the focal length of each lens and the radius of curvature of each surface satisfy the following conditions:

[0040] In some embodiments, the radius of curvature R (in mm), center thickness d (in mm), refractive index (ND), and Abbe number (VD) of each lens satisfy the following conditions:

[0041] In some embodiments, the first lens 1 is an aspherical lens. The side surface of the first lens 1 facing the object side O is convex, while its side surface facing the image side I is concave. The advantage of this configuration is that the first lens 1 can quickly converge the light rays incident from the object side O.

[0042] Furthermore, the radius of curvature of the side surface of the first lens 1 facing the object side O is 4.21 mm to 5.85 mm, for example, 5.36 mm; therefore, the center thickness of this side surface along the optical axis is 1.35 mm. The radius of curvature of the side surface facing the image side I is 1.56 mm to 3.21 mm, for example, 2 mm; therefore, the center thickness of this side surface along the optical axis is 3.66 mm. Also, the refractive index of the first lens 1 is 1.54.

[0043] In some embodiments, the second lens 2 is an aspherical lens. The side surface of the second lens 2 facing the object side O is concave, while its side surface facing the image side I is convex. Thus, on the side of the aperture stop 6 facing the object side O, the first lens 1 and the second lens 2 are combined to form a lens combination in which both the side surfaces facing the object side O and the side surfaces facing the image side I are convex, for the purpose of initially converging light rays.

[0044] Furthermore, the radius of curvature of the side surface of the second lens 2 facing the object side O is -4.81 mm to -6.24 mm, for example -5.99 mm, therefore, the center thickness of this side surface along the optical axis is 2.36 mm; the radius of curvature of the side surface facing the image side I is -4.23 mm to -6.21 mm, for example -5.25 mm, therefore, the center thickness of this side surface along the optical axis is 0.2 mm. Also, the refractive index of the second lens 2 is 1.64.

[0045] In some embodiments, the third lens 3 is a spherical lens. The object-side surface of the third lens 3 is convex, and both the object-side surface and the image-side surface are convex. The spherical lens can uniformly converge light rays, thus possessing the ability to form an image. This means that after light passes through the aperture 6, it is converged due to the presence of the third lens 3, thereby forming a preliminary image.

[0046] Furthermore, the radius of curvature of the side surface of the third lens 3 facing the object side O is 5.45 mm to 9.12 mm, for example, 7.82 mm; therefore, the central thickness of this side surface along the optical axis is 2.64 mm. The radius of curvature of the side surface facing the image side I is -9.23 mm to -6.34 mm, for example, -7.82 mm; therefore, the central thickness of this side surface along the optical axis is 0.6 mm. Also, the refractive index of the third lens 3 is 1.59.

[0047] In some embodiments, the fourth lens 4 is an aspherical lens. The side surface of the fourth lens 4 facing the object side O is concave, and the side surface facing the image side I is concave.

[0048] Furthermore, the radius of curvature of the side surface of the fourth lens 4 facing the object side O is -15.02 mm to -12.76 mm, for example -13.31 mm; therefore, the center thickness of this side surface along the optical axis is 0.53 mm. The radius of curvature of the side surface facing the image side I is 2.54 mm to 4.31 mm, for example 3.74 mm; therefore, the center thickness of this side surface along the optical axis is 0.23 mm. Also, the refractive index of the fourth lens 4 is 1.64.

[0049] In some embodiments, the fifth lens 5 is an aspherical lens. The side surface of the fifth lens 5 facing the object-side surface O is convex, and the side surface facing the image-side surface I is also convex. As a spherical lens, the third lens 3 will cause spherical aberration, affecting the sharpness of the image. Therefore, by sequentially arranging the fourth lens 4 and the fifth lens 5 downstream of the third lens 3 along the optical axis, the aforementioned spherical aberration can be corrected.

[0050] Furthermore, the radius of curvature of the side surface of the third lens 3 facing the object side O is 2.23 mm to 4.52 mm, for example, 3.74 mm; therefore, the center thickness of this side surface along the optical axis is 2.25 mm. The radius of curvature of the side surface facing the image side I is -6.42 mm to -3.85 mm, for example, -5 mm; therefore, the center thickness of this side surface along the optical axis is 1.11 mm. The refractive index of the fifth lens is 1.54.

[0051] In some embodiments, the aspherical k-values ​​(Conic) and aspherical coefficients of each optical surface of the first lens 1, the second lens 2, the fourth lens 4, and the fifth lens 5 respectively satisfy the following conditions:

[0052] Therefore, these aspherical lenses satisfy: Where Z is the sag of the lens along the optical axis, k is the conic coefficient of the quadratic surface, γ is the lens height, c is the lens curvature, and A, B, C, D, E, F, and G are the coefficients of the 4th, 6th, 8th, 10th, 12th, 14th, and 16th order terms of the aspherical polynomial.

[0053] Furthermore, on the side of the aperture stop 6 facing the image side I, the third lens 3, the fourth lens 4, and the fifth lens 5 are combined to form a lens assembly with convex side surfaces facing both the object side O and the image side I, for imaging.

[0054] Furthermore, at the manufacturing level, the individual lenses are insensitive, and the lens surface is simple and easy to manufacture, resulting in lower processing costs. At the same time, its flexible surface also makes aberration correction easier, thus achieving high mass production cost-effectiveness.

[0055] In some embodiments, the optical imaging system further includes a filter. The filter is disposed on the image-side surface I of the fifth lens 5. The filter selectively transmits light of a specific wavelength through absorption or interference effects to improve imaging contrast and control spectral composition. In this embodiment, the filter can be an interference filter, such as a cutoff filter, a bandpass filter, etc.; or it can be an absorption filter.

[0056] In some embodiments, the optical imaging system further includes a protective glass 7 and an image acquisition element (not shown). The protective glass 7 is integrated onto the image acquisition element, making them a single unit. Incidentally, the aforementioned filter is integrated onto the protective glass 7. The image acquisition element is positioned on the side of the filter facing the image side I. The advantage of this configuration is that light passes sequentially through the combination of lenses and apertures 6, and then through the filter, before being captured by the image acquisition element to obtain the desired image. Furthermore, the protective glass 7 has a refractive index of 1.52 and an Abbe number of 64.21.

[0057] In some embodiments, the Abbe numbers of the first lens 1 and the fifth lens 5 are greater than 55, and / or the Abbe numbers of the second lens 2 and the fourth lens 4 are less than 24. The Abbe number characterizes the degree of light dispersion in a transparent medium and is a key indicator of the imaging quality of optical materials. High-refractive-index lenses are thinner and lighter, but simultaneously have lower Abbe numbers, making them more prone to dispersion; while low-refractive-index lenses have higher Abbe numbers, but are also thicker and heavier. Therefore, the second lens 2 and the fourth lens 4 are constructed to be thinner and lighter than the first lens 1 and the fifth lens 5. For example, the Abbe number of the first lens 1 is 55.711, the Abbe number of the second lens 2 is 23.53, the Abbe number of the third lens 3 is 68.34, the Abbe number of the fourth lens 4 is 23.53, and the Abbe number of the fifth lens 5 is 55.711.

[0058] According to another embodiment of the present invention, the present invention also provides an optical lens, including a lens barrel and an optical imaging system as described above, the optical imaging system being installed inside the lens barrel.

[0059] The total focal length f of the optical lens, the focal length of each lens, the holographic height IC under the condition of using a 1 / 2.7-inch chip, the total optical length TTL, the optical back focal length OBBFL, and the aperture f# respectively meet the following conditions:

[0060] With the above configuration, the field of view of the optical lens can reach 108° or more; the total focal length f can be set to 3.45mm~4.5mm, for example, about 3.64mm; the total length TTL of the entire optical lens can be set to ≤22.5mm, for example, 22.26mm, or at least limited to about 22.44mm, or the total length TTL and total focal length f of the optical lens can satisfy 4.22≤TTL / f≤6.25, for example, 6.1; its optical back focal length OBFL is about 5.5mm, or such that the optical back focal length OBFL satisfies 0.2≤OBFL / TTL≤0.26, for example, 0.25; and the holographic height IC can satisfy IC / TTL≥0.25, for example, 0.29.

[0061] Correspondingly, the focal length f1 of the first lens 1 can be set to -4.67mm to -7.23mm, the focal length f2 of the second lens 2 can be set to 27.25mm to 31.32mm, the focal length f3 of the third lens 3 can be set to 5.51mm to 7.62mm, the focal length f4 of the fourth lens 4 can be set to -6.21mm to -4.12mm, and the focal length f5 of the fifth lens 5 can be set to 3.84mm to 4.72mm. For example, the focal lengths f1 of the first lens 1, f2 of the second lens 2, f3 of the third lens 3, f4 of the fourth lens 4, and f5 of the fifth lens 5 satisfy the following conditions: -2.1≤f1 / f≤-1.85, 8.0≤f2 / f≤8.5, 1.9≤f3 / f≤2.1, -1.25≤f4 / f≤-1.2, and 1.18≤f5 / f≤1.25, respectively.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An optical imaging system, characterized in that, Along the optical axis from the object side to the image side, the following are included in sequence: The first lens has negative optical power and is made of a first material; The second lens has positive optical power and is made of a second material; Aperture; The third lens has positive optical power and is made of a third material; The fourth lens has negative optical power and is made of the second material; The fifth lens has positive optical power and is made of the first material.

2. The optical imaging system according to claim 1, characterized in that, The first material and the second material are different plastics from each other, and / or the third material is glass.

3. The optical imaging system according to claim 1 or 2, characterized in that, The first lens is an aspherical lens, with its object-facing side surface being convex and having a radius of curvature of 4.21 mm to 5.85 mm; its image-facing side surface being concave and having a radius of curvature of 1.56 mm to 3.21 mm; and / or The first lens f1 and the effective focal length f of the optical imaging system satisfy -2.1≤f1 / f≤-1.

85.

4. The optical imaging system according to claim 1 or 2, characterized in that, The second lens is an aspherical lens, with its object-facing side surface being concave and its radius of curvature being -4.81 mm to -6.24 mm; its image-facing side surface being convex and its radius of curvature being -4.23 mm to -6.21 mm; and / or The second lens f2 and the effective focal length f of the optical imaging system satisfy 8.0≤f2 / f≤8.

5.

5. The optical imaging system according to claim 1 or 2, characterized in that, The third lens is a spherical lens, with its object-facing side surface being convex and its radius of curvature being 5.45mm~9.12mm; its image-facing side surface being convex and its radius of curvature being -9.23mm~-6.34mm; and / or The third lens f3 and the effective focal length f of the optical imaging system satisfy 1.9≤f3 / f≤2.

1.

6. The optical imaging system according to claim 1 or 2, characterized in that, The fourth lens is an aspherical lens, with its object-facing side surface being concave and its radius of curvature being -15.02 mm to -12.76 mm; its image-facing side surface being concave and its radius of curvature being 2.54 mm to 4.31 mm; and / or The fourth lens f4 and the effective focal length f of the optical imaging system satisfy -1.25≤f4 / f≤-1.

2.

7. The optical imaging system according to claim 1 or 2, characterized in that, The fifth lens is an aspherical lens, with its object-facing side surface being convex and its radius of curvature being 2.23mm~4.52mm; its image-facing side surface being convex and its radius of curvature being -6.42mm~-3.85mm; and / or The fifth lens f5 and the effective focal length f of the optical imaging system satisfy 1.18≤f5 / f≤1.

25.

8. The optical imaging system according to claim 1, characterized in that, The aspherical surfaces of the first lens, the second lens, the fourth lens, and the fifth lens satisfy the following: Where Z is the sag of the lens along the optical axis, k is the conic coefficient of the quadratic surface, γ is the lens height, c is the lens curvature, and A, B, C, D, E, F, and G are the coefficients of the 4th, 6th, 8th, 10th, 12th, 14th, and 16th order terms of the aspherical polynomial.

9. The optical imaging system according to claim 1, characterized in that, The Abbe number of the first lens and the fifth lens is greater than 55, and / or the Abbe number of the second lens and the fourth lens is less than 24.

10. An optical lens, characterized in that, It includes a lens barrel and an optical imaging system according to any one of claims 1 to 9, wherein the optical imaging system is installed inside the lens barrel.

Images