Optical lens

Abstract

The application discloses an optical lens. The optical lens comprises, in sequence from an object side to an image side along an optical axis, a first lens with negative refractive power, a second lens with positive refractive power, a third lens with positive refractive power, a fourth lens with negative refractive power, a fifth lens with negative refractive power, a sixth lens with positive refractive power, a seventh lens with positive refractive power, an eighth lens with positive refractive power, and a ninth lens with negative refractive power.

Description

Technical Field

[0001] This application relates to the field of optical components, and more specifically, to an optical lens. Background Technology

[0002] With the rapid development of society and the economy, the demand for optical lenses is increasing across all industries in order to improve the safety of production and daily life. Furthermore, the increasing integration of electronic devices and the ever-higher quality requirements for optical lenses necessitate miniaturization while maintaining high resolution and low distortion to achieve clear resolution and reduce image distortion.

[0003] Nowadays, security lenses play an important role in shopping malls, residences, roads and other places. However, most of the security fixed-focus lenses on the market still have a number of problems, such as low resolution, which cannot simultaneously guarantee image quality and low distortion requirements, or small target surface, which cannot meet the requirements of higher image quality. Summary of the Invention

[0004] This application provides an optical lens that, along the optical axis from the object side to the image side, sequentially comprises: a first lens having negative optical power; a second lens having positive optical power; a third lens having positive optical power; a fourth lens having negative optical power; a fifth lens having negative optical power; a sixth lens having positive optical power; a seventh lens having positive optical power; an eighth lens having positive optical power; and a ninth lens having negative optical power.

[0005] In one embodiment, the object-side surface of the first lens is convex, and the image-side surface is concave.

[0006] In one embodiment, the object-side surface of the second lens is convex.

[0007] In one embodiment, the object-side surface of the third lens is convex, and the image-side surface is also convex.

[0008] In one embodiment, the object-side surface of the fourth lens is concave, and the image-side surface is also concave.

[0009] In one embodiment, the object-side surface of the fifth lens is concave, and the image-side surface is also concave.

[0010] In one embodiment, the object-side surface of the sixth lens is convex, and the image-side surface is also convex.

[0011] In one embodiment, the object-side surface of the seventh lens is convex, and the image-side surface is also convex.

[0012] In one embodiment, the object-side surface of the eighth lens is convex, and the image-side surface is also convex.

[0013] In one embodiment, the object-side surface of the ninth lens is concave, and the image-side surface is also concave.

[0014] In one embodiment, the effective focal length F of the optical lens and the distance TTL from the object side of the first lens to the imaging surface of the optical lens on the optical axis satisfy: 0.3≤F / TTL≤0.8.

[0015] In one embodiment, the back focal length BFL of the optical lens and the distance TTL from the object side of the first lens to the imaging plane of the optical lens on the optical axis satisfy: 0.24≤BFL / TTL≤0.32.

[0016] In one embodiment, the effective focal length F1 of the first lens and the effective focal length F of the optical lens satisfy: -6.5≤F1 / F≤-0.83.

[0017] In one embodiment, the effective focal length F2 of the second lens and the effective focal length F of the optical lens satisfy: 0.89≤F2 / F≤1.9.

[0018] In one embodiment, the effective focal length F3 of the third lens and the effective focal length F of the optical lens satisfy: 0.6≤F3 / F≤1.2.

[0019] In one embodiment, the effective focal length F4 of the fourth lens and the effective focal length F of the optical lens satisfy: -0.9≤F4 / F≤-0.3.

[0020] In one embodiment, the effective focal length F5 of the fifth lens and the effective focal length F of the optical lens satisfy: -0.65≤F5 / F≤-0.25.

[0021] In one embodiment, the effective focal length F6 of the sixth lens and the effective focal length F of the optical lens satisfy the following condition: 0.55≤F6 / F≤0.8.

[0022] In one embodiment, the effective focal length F7 of the seventh lens and the effective focal length F of the optical lens satisfy: 0.5≤F7 / F≤1.27.

[0023] In one embodiment, the effective focal length F8 of the eighth lens and the effective focal length F of the optical lens satisfy: 0.45≤F8 / F≤1.03.

[0024] In one embodiment, the effective focal length F9 of the ninth lens and the effective focal length F of the optical lens satisfy: -0.84≤F9 / F≤-0.25.

[0025] In one embodiment, the combined focal length F34 of the third and fourth lenses satisfies the following condition with respect to the effective focal length F of the optical lens: -16.10 ≤ F34 / F ≤ -0.45.

[0026] In one embodiment, the combined focal length F56 of the fifth and sixth lenses satisfies the following condition with respect to the effective focal length F of the optical lens: -3.95≤F56 / F≤4.66.

[0027] In one embodiment, the combined focal length F89 of the eighth and ninth lenses satisfies the following condition with respect to the effective focal length F of the optical lens: -8.15 ≤ F89 / F ≤ -0.32.

[0028] In one embodiment, the sum of the center thicknesses of the third and fourth lenses on the optical axis, D34, and the sum of the center thicknesses of the fifth and sixth lenses on the optical axis, D56, satisfy the condition: 0.65 ≤ D34 / D56 ≤ 1.73.

[0029] In one embodiment, the refractive index ND7 of the seventh lens, the refractive index ND8 of the eighth lens, and the refractive index ND9 of the ninth lens satisfy: 1.9≤(ND7+ND8) / ND9≤2.0.

[0030] In one embodiment, the Abbe number VD3 of the third lens and the Abbe number VD8 of the eighth lens satisfy: 70≤(VD3+VD8) / 2≤90.

[0031] In one embodiment, the maximum optical aperture DM7 of the seventh lens and the distance TTL from the object side of the first lens to the imaging surface of the optical lens on the optical axis satisfy: 0.26≤DM7 / TTL≤0.33.

[0032] In one embodiment, the air gap d12 between the first lens and the second lens on the optical axis satisfies the following condition with respect to the effective focal length F of the optical lens: 0.04≤d12 / F≤0.3.

[0033] In another aspect, this application provides an electronic device. This electronic device includes an optical lens according to this application and an imaging element for converting an optical image formed by the optical lens into an electrical signal.

[0034] The optical lens provided in this application is a fixed-focus lens. By reasonably setting the number of lenses and optimizing the optical power of each lens, the optical lens provided in this application has at least one beneficial effect such as low distortion, high image quality, large target surface, miniaturization, and infrared confocal focus. Attached Figure Description

[0035] Other features, objects, and advantages of this utility application will become more apparent from the following detailed description of the embodiments, taken in conjunction with the accompanying drawings. In the drawings:

[0036] Figure 1 This is a schematic diagram of the structure of an optical lens according to Embodiment 1 of this application;

[0037] Figure 2The distortion diagram is shown for the optical lens according to Embodiment 1 of this application;

[0038] Figure 3 This is a schematic diagram of the structure of an optical lens according to Embodiment 2 of this application;

[0039] Figure 4 The distortion diagram is shown for the optical lens according to Embodiment 2 of this application;

[0040] Figure 5 This is a schematic diagram of the structure of the optical lens according to Embodiment 3 of this application;

[0041] Figure 6 The distortion diagram is shown for the optical lens according to Embodiment 3 of this application;

[0042] Figure 7 This is a schematic diagram of the structure of the optical lens according to Embodiment 4 of this application;

[0043] Figure 8 The distortion diagram is shown for the optical lens according to Embodiment 4 of this application;

[0044] Figure 9 This is a schematic diagram of the structure of an optical lens according to Embodiment 5 of this application; and

[0045] Figure 10 This is a distortion diagram of the optical lens according to Embodiment 5 of this application. Detailed Implementation

[0046] To facilitate understanding of this application, a more complete description of the application will be provided below with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely illustrative of exemplary embodiments of the application and are not intended to limit the scope of the application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0047] It should be noted that in this specification, the terms "first," "second," "third," etc., are used only to distinguish one feature from another and do not imply any limitation on the features. Therefore, without departing from the teachings of this application, the first lens discussed below may also be referred to as the second lens or the third lens.

[0048] In the accompanying drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are illustrated by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustrative purposes only and are not strictly to scale.

[0049] In this article, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the location of the convexity is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the location of the concaveness is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the subject is called the object-side surface of the lens, and the surface of each lens closest to the imaging side is called the image-side surface of the lens.

[0050] It should also be understood that the terms "comprising," "including," "having," "containing," and / or "comprising," when used in this specification, indicate the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. Furthermore, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire list of features, not individual elements in the list. Additionally, when describing embodiments of this application, the word "may" is used to mean "one or more embodiments of this application." And the term "exemplary" is intended to refer to an example or illustration.

[0051] Unless otherwise specified, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms (e.g., those defined in common dictionaries) shall be interpreted as having a meaning consistent with their meaning in the context of the relevant art and shall not be interpreted in an idealized or overly formalized sense, unless expressly so specified herein.

[0052] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0053] The features, principles and other aspects of this application are described in detail below.

[0054] In an exemplary embodiment, the optical lens includes, for example, nine lenses with optical power, namely a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a ninth lens.

[0055] In an exemplary embodiment, the optical lens may further include a photosensitive element disposed on the image side of the ninth lens. Optionally, the photosensitive element disposed on the image side of the ninth lens may be a photosensitive coupling element (CCD) or a complementary metal oxide semiconductor element (CMOS).

[0056] In an exemplary embodiment, the optical lens may further include an aperture stop for limiting the light beam, thereby further improving the imaging quality of the optical lens. Exemplarily, the aperture stop may be positioned between the first lens and the second lens. The aperture stop helps to concentrate the light entering the optical lens, shorten the overall length of the optical system, reduce the maximum aperture of the optical lens, and facilitates miniaturization and reduces the system's assembly sensitivity. However, it should be noted that the positions of the aperture stop disclosed herein are merely examples and not limitations; in alternative embodiments, the aperture stop may be positioned in other locations as needed.

[0057] In an exemplary embodiment, the first lens has negative optical power, with its object-side surface being convex and its image-side surface being concave. The first lens, having both negative optical power and a convex-concave shape, can diffuse a large field of light entering the optical lens to the rear optical system, effectively controlling distortion and achieving a low-distortion effect. This can effectively increase light transmission and improve lens resolution.

[0058] In an exemplary embodiment, the second lens has positive optical power and its object-side surface is convex. The positive optical power of the second lens can smooth the angle of light passing through it, ensuring aberration correction and improving lens resolution while minimizing distortion.

[0059] In an exemplary embodiment, the third lens has positive optical power, and its object-side surface is convex, as is its image-side surface. The positive optical power of the third lens can correct system aberrations and balance high and low temperature performance.

[0060] In an exemplary embodiment, the fourth lens has negative optical power, and both its object-side and image-side surfaces are concave. The negative optical power of the fourth lens, when used in conjunction with the third lens, can balance the spherical aberration introduced by the third lens, thus helping to ensure high image quality.

[0061] In an exemplary embodiment, the fifth lens has negative optical power, and both its object-side and image-side surfaces are concave. The negative optical power of the fifth lens helps to balance spherical aberration and also balances the field curvature of the system, thus contributing to high image quality.

[0062] In an exemplary embodiment, the sixth lens has positive optical power, and both its object-side and image-side surfaces are convex. The sixth lens, with its positive optical power, works in conjunction with the fifth lens to balance system spherical aberration, improve resolution, and achieve high resolution.

[0063] In an exemplary embodiment, the seventh lens has positive optical power, and both its object-side and image-side surfaces are convex. The positive optical power of the seventh lens ensures the height of light rays before and after it, which is beneficial for achieving a large target surface.

[0064] In an exemplary embodiment, the eighth lens has positive optical power, and both its object-side and image-side surfaces are convex. The positive optical power of the eighth lens helps balance astigmatism generated by light passing through the system, thus improving lens image quality while maintaining a large target surface.

[0065] In an exemplary embodiment, the ninth lens has negative optical power, and both its object-side and image-side surfaces are concave. The negative optical power of the ninth lens, when used in conjunction with the eighth lens, balances system aberrations, reduces system tolerance sensitivity, and helps ensure production yield.

[0066] In an exemplary embodiment, the optical lens according to this application satisfies: 0.3 ≤ F / TTL ≤ 0.8, where TTL is the distance on the optical axis from the object-side surface of the first lens to the imaging surface of the optical lens, and F is the effective focal length of the optical lens. More specifically, F and TTL can further satisfy: 0.37 ≤ F / TTL ≤ 0.65. Satisfying 0.3 ≤ F / TTL ≤ 0.8, under a certain system focal length value, by controlling the overall optical length of the system, the overall optical length of the system is made smaller, which is beneficial for miniaturization.

[0067] In an exemplary embodiment, the optical lens according to this application satisfies: 0.24 ≤ BFL / TTL ≤ 0.32, where BFL is the back focal length of the optical lens, and TTL is the distance on the optical axis from the object-side surface of the first lens to the imaging surface of the optical lens. Satisfying 0.24 ≤ BFL / TTL ≤ 0.32 is beneficial for achieving miniaturization while ensuring the lens's assemblability by controlling the system's optical back focal length, allowing for the insertion of filters without interference at the rear end.

[0068] In an exemplary embodiment, the optical lens according to this application satisfies: -6.5 ≤ F1 / F ≤ -0.83, where F1 is the effective focal length of the first lens and F is the effective focal length of the optical lens. More specifically, F1 and F may further satisfy: -5.81 ≤ F1 / F ≤ -1.10. Satisfying -6.5 ≤ F1 / F ≤ -0.83, by converging the incident light rays, diverges the large field-of-view light rays entering the optical system to the rear optical system, which is beneficial for achieving low distortion.

[0069] In an exemplary embodiment, the optical lens according to this application satisfies: 0.89 ≤ F2 / F ≤ 1.9, where F2 is the effective focal length of the second lens and F is the effective focal length of the optical lens. Satisfying 0.89 ≤ F2 / F ≤ 1.9, by reasonably controlling the focal length value of the second lens, helps to smooth the light transition, correct aberrations, improve lens resolution, and reduce distortion, thus ensuring low lens distortion.

[0070] In an exemplary embodiment, the optical lens according to this application satisfies: 0.6 ≤ F3 / F ≤ 1.2, where F3 is the effective focal length of the third lens and F is the effective focal length of the optical lens. More specifically, F3 and F further satisfy: 0.73 ≤ F3 / F ≤ 1.17. By satisfying 0.6 ≤ F3 / F ≤ 1.2 and controlling the focal length value of the third lens, system aberrations can be corrected and high and low temperature performance can be balanced.

[0071] In an exemplary embodiment, the optical lens according to this application satisfies: -0.9 ≤ F4 / F ≤ -0.3, where F4 is the effective focal length of the fourth lens and F is the effective focal length of the optical lens. More specifically, F4 and F further satisfy: -0.79 ≤ F4 / F ≤ -0.49. Satisfying -0.9 ≤ F4 / F ≤ -0.3, the fourth lens has negative optical power. By controlling the focal length value of the fourth lens, the spherical aberration introduced by the third lens can be balanced, which is beneficial for ensuring high image quality.

[0072] In an exemplary embodiment, the optical lens according to this application satisfies: -0.65 ≤ F5 / F ≤ -0.25, where F5 is the effective focal length of the fifth lens and F is the effective focal length of the optical lens. More specifically, F5 and F can further satisfy: -0.65 ≤ F5 / F ≤ -0.34. Satisfying -0.65 ≤ F5 / F ≤ -0.25, by controlling the focal length value of the fifth lens and the total focal length value of the optical lens within a certain range, can balance the field curvature of the system, which is beneficial to clear imaging.

[0073] In an exemplary embodiment, the optical lens according to this application satisfies: 0.55≤F6 / F≤0.8, where F6 is the effective focal length of the sixth lens and F is the effective focal length of the optical lens. Satisfying 0.55≤F6 / F≤0.8 ensures that the sixth lens has positive optical power, which can balance the spherical aberration introduced by the fifth lens and helps guarantee high image quality.

[0074] In an exemplary embodiment, the optical lens according to this application satisfies: 0.5 ≤ F7 / F ≤ 1.27, where F7 is the effective focal length of the seventh lens and F is the effective focal length of the optical lens. More specifically, F7 and F can further satisfy: 0.52 ≤ F7 / F ≤ 0.85. Satisfying 0.5 ≤ F7 / F ≤ 1.27, by controlling the focal length value of the seventh lens and the total focal length value of the optical lens within a certain range, can ensure the light height before and after the seventh lens, which is beneficial for achieving a large target surface.

[0075] In an exemplary embodiment, the optical lens according to this application satisfies: 0.45 ≤ F8 / F ≤ 1.03, where F8 is the effective focal length of the eighth lens and F is the effective focal length of the optical lens. More specifically, F8 and F can further satisfy: 0.5 ≤ F8 / F ≤ 0.75. Satisfying 0.45 ≤ F8 / F ≤ 1.03, the eighth lens has positive optical power. By controlling the focal length value of the eighth lens and the total focal length value of the optical lens within a certain range, astigmatism generated by light passing through the system can be balanced, which is beneficial for ensuring image quality under large target surfaces.

[0076] In an exemplary embodiment, the optical lens according to this application satisfies: -0.84 ≤ F9 / F ≤ -0.25, where F9 is the effective focal length of the ninth lens and F is the effective focal length of the optical lens. More specifically, F9 and F further satisfy: -0.55 ≤ F9 / F ≤ -0.28. Satisfying -0.84 ≤ F9 / F ≤ -0.25, the ninth lens has negative optical power, is located at the end of the system, and can balance off-axis aberrations, which is beneficial for ensuring image quality under large target surfaces.

[0077] In an exemplary embodiment, the optical lens according to this application satisfies: -16.10 ≤ F34 / F ≤ -0.45, where F34 is the combined focal length of the third and fourth lenses, and F is the effective focal length of the optical lens. More specifically, F34 and F can further satisfy: -15 ≤ F34 / F ≤ -2. Satisfying -16.10 ≤ F34 / F ≤ -0.45, by reasonably controlling the combined focal length of the third and fourth lenses, results in a smaller spherical aberration, ensuring high image quality.

[0078] In an exemplary embodiment, the optical lens according to this application satisfies: -3.95 ≤ F56 / F ≤ 4.66, where F56 is the combined focal length of the fifth and sixth lenses, and F is the effective focal length of the optical lens. More specifically, F56 and F further satisfy: -3 ≤ F56 / F ≤ -1.3. By satisfying -3.95 ≤ F56 / F ≤ 4.66 and reasonably controlling the combined focal length of the fifth and sixth lenses, chromatic aberration of the system can be balanced, resolution improved, and high resolution achieved.

[0079] In an exemplary embodiment, the optical lens according to this application satisfies: -8.15 ≤ F89 / F ≤ -0.32, where D2 is the center thickness of the second lens on the optical axis, and D3 is the center thickness of the third lens on the optical axis. More specifically, F89 and F can further satisfy: -2.2 ≤ F89 / F ≤ -1.2. Satisfying -8.15 ≤ F89 / F ≤ -0.32, and reasonably controlling the combined focal length of the eighth and ninth lenses, can balance system aberrations, improve lens resolution, and reduce system tolerance sensitivity, which is beneficial to ensuring production yield.

[0080] In an exemplary embodiment, the optical lens according to this application satisfies the following: 0.65 ≤ D34 / D56 ≤ 1.73, where D34 is the sum of the center thicknesses of the third and fourth lenses along the optical axis, and D56 is the sum of the center thicknesses of the fifth and sixth lenses along the optical axis. More specifically, D34 and D56 can further satisfy: 0.7 ≤ D34 / D56 ≤ 1.7. Satisfying 0.65 ≤ D34 / D56 ≤ 1.73, and reasonably controlling the thickness ratios of the third and fourth lenses, and the fifth and sixth lenses, is beneficial for balancing system chromatic aberration and for achieving high image quality.

[0081] In an exemplary embodiment, the optical lens according to this application satisfies: 1.9 ≤ (ND7 + ND8) / ND9 ≤ 2.0, where ND7 is the refractive index of the seventh lens, ND8 is the refractive index of the eighth lens, and ND9 is the refractive index of the ninth lens. By satisfying 1.9 ≤ (ND7 + ND8) / ND9 ≤ 2.0 and reasonably controlling the refractive index ratio of the last three lenses within a certain range, optical aberrations converged onto the photosensitive receiving chip can be reduced, which is beneficial for clear imaging.

[0082] In an exemplary embodiment, the optical lens according to this application satisfies: 70≤(VD3+VD8) / 2≤90, where VD3 is the Abbe number of the third lens and VD8 is the Abbe number of the eighth lens. Satisfying 70≤(VD3+VD8) / 2≤90, by reasonably controlling the Abbe numbers of the third and eighth lenses, is beneficial for balancing infrared band performance and achieving day and night confocal focusing.

[0083] In an exemplary embodiment, the optical lens according to this application satisfies the following condition: 0.26 ≤ DM7 / TTL ≤ 0.33, where DM7 is the maximum optical aperture of the seventh lens, and TTL is the distance on the optical axis from the object-side surface of the first lens to the imaging surface of the optical lens. By satisfying 0.26 ≤ DM7 / TTL ≤ 0.33 and controlling the ratio of the maximum optical aperture of the seventh lens to the total optical length, the system size can be reduced, which is beneficial for miniaturized integration.

[0084] In an exemplary embodiment, the optical lens according to this application satisfies: 0.04 ≤ d12 / F ≤ 0.3, where d12 is the air gap between the first lens and the second lens on the optical axis, and F is the effective focal length of the optical lens. More specifically, d12 and F can further satisfy: 0.05 ≤ d12 / F ≤ 0.29. Satisfying 0.04 ≤ d12 / F ≤ 0.3, by controlling the air gap between the first lens and the second lens and the total focal length of the lens within a certain range, is beneficial for maintaining a suitable air gap between the first lens and the second lens, reducing various aberrations generated at the front end of the lens, and improving image quality.

[0085] In an exemplary embodiment, the optical lens of this application may be made of glass. For example, the first lens to the ninth lens may all be made of glass. Using glass makes the lens more stable and achieves high imaging quality in the range of -30℃ to +70℃.

[0086] In exemplary embodiments, the third and fourth lenses may form a cemented lens, or the fifth and sixth lenses may form a cemented lens, or the eighth and ninth lenses may form a cemented lens. Cemented lenses are beneficial for balancing various aberrations, improving resolution, achieving high resolution, and also for reducing tolerance sensitivity between lenses, ensuring production yield. This application does not specifically limit the specific number of cemented lenses. Optionally, the optical lens of this application may include three cemented lenses, such as the third and fourth lenses forming a cemented lens, the fifth and sixth lenses forming a cemented lens, and the eighth and ninth lenses forming a cemented lens. Optionally, the optical lens of this application may also include two cemented lenses, such as the fifth and sixth lenses forming a cemented lens, and the eighth and ninth lenses forming a cemented lens. Those skilled in the art should understand that the above are merely examples and not limitations. Without departing from the technical solution claimed in this application, at least one of the following can be selected: the third and fourth lenses forming a cemented lens, the fifth and sixth lenses forming a cemented lens, and the eighth and ninth lenses forming a cemented lens.

[0087] Optionally, in an exemplary embodiment, the optical lens of this application may further include a filter and / or protective glass disposed between the ninth lens and the imaging surface, as needed, to filter light of different wavelengths and prevent damage to the image-side elements (e.g., chips) of the optical lens.

[0088] In an exemplary embodiment, the object-side surface and image-side surface of each of the first to ninth lenses of this application are spherical mirror surfaces.

[0089] In other exemplary embodiments, the first to ninth lenses may be spherical lenses or aspherical lenses, depending on the requirements. This application does not specifically limit the number of spherical and aspherical lenses; when image quality is a primary concern, the number of aspherical lenses can be increased, and even all lenses may be aspherical. Aspherical lenses are characterized by a continuously changing curvature from the lens center to the periphery. Unlike spherical lenses, which have a constant curvature from the lens center to the periphery, aspherical lenses have better radius of curvature characteristics, offering advantages in improving distortion and astigmatism. Using aspherical lenses can minimize aberrations that occur during image formation, thereby improving the lens's image quality.

[0090] The optical lens according to the above embodiments of this application can employ multiple lenses, such as the nine lenses mentioned above. By rationally allocating optical parameters such as the optical power, surface shape, center thickness of each lens, and on-axis spacing between each lens, at least one of the following characteristics can be achieved: low distortion, large target area, high image quality, small size, and infrared confocal lens. The optical lens provided by this application has good infrared confocal performance, provides excellent infrared imaging at night, and is an imaging lens suitable for both day and night use. Furthermore, it provides clear imaging at temperatures ranging from -30℃ to +70℃.

[0091] In an exemplary embodiment, the maximum optical distortion (DIS) of the optical lens according to this application can satisfy: |DIS|≤2.9%, so that the optical lens exhibits low distortion and achieves high-quality imaging requirements.

[0092] In an exemplary embodiment, the diagonal length (holographic height) Img of the effective pixel area on the imaging surface of the optical lens according to this application satisfies: Img ≥ 8.4mm, and Img can further satisfy: 8.4mm ≤ Img ≤ 8.9mm.

[0093] In an exemplary embodiment, the aperture number Fno of the optical lens according to this application can satisfy: Fno≥1.60; Fno can further satisfy: 1.60≤Fno≤1.90, thereby reducing the F number of the optical lens, increasing the aperture, increasing the amount of light entering, enhancing the imaging effect in dark environments, and at the same time, reducing the aberrations at the edge of the field of view.

[0094] The optical lens according to the above embodiments of this application may employ multiple lenses, such as the nine lenses described above. However, those skilled in the art should understand that the number of lenses constituting the lens can be changed without departing from the technical solutions claimed in this application to obtain the various results and advantages described in this specification. For example, although nine lenses have been described as an example in the embodiments, the optical lens is not limited to including nine lenses. If necessary, the optical lens may also include other numbers of lenses. Specific embodiments of the optical lens applicable to the above embodiments are further described below with reference to the accompanying drawings.

[0095] Example 1

[0096] The following is for reference Figure 1 An optical lens according to Embodiment 1 of this application is described. Figure 1 A schematic diagram of the structure of an optical lens according to Embodiment 1 of this application is shown.

[0097] like Figure 1As shown, the optical lens includes, in sequence from the object side to the image side, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, and a ninth lens L9.

[0098] The first lens L1 has negative optical power, with its object side S1 being convex and its image side S2 being concave.

[0099] The second lens L2 has positive optical power, and its object side S4 is convex, and its image side S5 is convex.

[0100] The third lens L3 has positive optical power, and its object side S6 is convex, while its image side S7 is convex.

[0101] The fourth lens L4 has negative optical power, and its object side S7 is concave, as is its image side S8.

[0102] The fifth lens L5 has negative optical power, and its object side S9 is concave, and its image side S10 is concave.

[0103] The sixth lens L6 has positive optical power, and its object side S10 is convex, and its image side S11 is convex.

[0104] The seventh lens L7 has positive optical power, and its object side S12 is convex, and its image side S13 is convex.

[0105] The eighth lens L8 has positive optical power, and its object side S14 is convex, and its image side S15 is convex.

[0106] The ninth lens L9 has negative optical power, and its object side S15 is concave, and its image side S16 is concave.

[0107] The third lens L3 and the fourth lens L4 form a cemented lens, the fifth lens L5 and the sixth lens L6 form a cemented lens, and the eighth lens L8 and the ninth lens L9 form a cemented lens.

[0108] The optical lens may also include an aperture stop STO, which may be positioned between the first lens L1 and the second lens L2 to improve image quality.

[0109] Optionally, the optical lens may also include a filter CG having an object-side surface S17 and an image-side surface S18 and / or a protective glass (not shown) having an object-side surface and an image-side surface. The filter CG and / or the protective glass can be used to correct color aberrations, and can also be used to protect the image sensor chip located at the imaging surface IMA (S19). Light from the object passes sequentially through each surface S1 to S18 and is finally imaged onto the imaging surface IMA (S19).

[0110] Table 1 shows the radius of curvature, thickness / distance, refractive index, and Abbe number of each lens in the optical lens of Example 1, wherein the units of radius of curvature and thickness / distance are millimeters (mm).

[0111]

[0112]

[0113] Table 1

[0114] In this embodiment, the aperture number Fno of the optical lens is 1.80, the diagonal length (holographic height) Img of the effective pixel area on the imaging plane is 8.70mm, and the absolute value of the maximum optical distortion DIS, |DIS|, is 1.10%.

[0115] Figure 2 A distortion diagram of the optical lens of Embodiment 1 is shown, representing the distortion magnitude values ​​corresponding to different fields of view. According to... Figure 2 It can be seen that the optical lens given in Example 1 has the characteristics of low distortion and can achieve good imaging quality.

[0116] Example 2

[0117] The following is for reference Figure 3 An optical lens according to Embodiment 2 of this application is described. In this embodiment and the following embodiments, for the sake of brevity, descriptions similar to those in Embodiment 1 will be omitted. Figure 3 A schematic diagram of the structure of an optical lens according to Embodiment 2 of this application is shown.

[0118] like Figure 3 As shown, the optical lens includes, in sequence from the object side to the image side, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, and a ninth lens L9.

[0119] The first lens L1 has negative optical power, with its object side S1 being convex and its image side S2 being concave.

[0120] The second lens L2 has positive optical power, its object side S4 is convex, and its image side S5 is flat.

[0121] The third lens L3 has positive optical power, and its object side S6 is convex, while its image side S7 is convex.

[0122] The fourth lens L4 has negative optical power, and its object side S7 is concave, as is its image side S8.

[0123] The fifth lens L5 has negative optical power, and its object side S9 is concave, and its image side S10 is concave.

[0124] The sixth lens L6 has positive optical power, and its object side S10 is convex, and its image side S11 is convex.

[0125] The seventh lens L7 has positive optical power, and its object side S12 is convex, and its image side S13 is convex.

[0126] The eighth lens L8 has positive optical power, and its object side S14 is convex, and its image side S15 is convex.

[0127] The ninth lens L9 has negative optical power, and its object side S15 is concave, and its image side S16 is concave.

[0128] The third lens L3 and the fourth lens L4 form a cemented lens, the fifth lens L5 and the sixth lens L6 form a cemented lens, and the eighth lens L8 and the ninth lens L9 form a cemented lens.

[0129] The optical lens may also include an aperture stop STO, which may be positioned between the first lens L1 and the second lens L2 to improve image quality.

[0130] Optionally, the optical lens may also include a filter CG having an object-side surface S17 and an image-side surface S18 and / or a protective glass (not shown) having an object-side surface and an image-side surface. The filter CG and / or the protective glass can be used to correct color aberrations, and can also be used to protect the image sensor chip located at the imaging surface IMA (S19). Light from the object passes sequentially through each surface S1 to S18 and is finally imaged onto the imaging surface IMA (S19).

[0131] Table 2 shows the radius of curvature, thickness / distance, refractive index, and Abbe number of each lens in the optical lens of Example 2, wherein the units of radius of curvature and thickness / distance are millimeters (mm).

[0132]

[0133] Table 2

[0134] In this embodiment, the aperture number Fno of the optical lens is 1.75, the diagonal length (holographic height) Img of the effective pixel area on the imaging plane is 8.70mm, and the absolute value of the maximum optical distortion DIS, |DIS|, is 1.01%.

[0135] Figure 4 A distortion diagram of the optical lens of Embodiment 2 is shown, representing the distortion magnitude values ​​corresponding to different fields of view. According to... Figure 4 It can be seen that the optical lens given in Example 2 has the characteristics of low distortion and can achieve good imaging quality.

[0136] Example 3

[0137] The following is for reference Figure 5 An optical lens according to Embodiment 3 of this application is described. Figure 5 A schematic diagram of the structure of an optical lens according to Embodiment 3 of this application is shown.

[0138] like Figure 5 As shown, the optical lens includes, in sequence from the object side to the image side, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, and a ninth lens L9.

[0139] The first lens L1 has negative optical power, with its object side S1 being convex and its image side S2 being concave.

[0140] The second lens L2 has positive optical power, and its object side S4 is convex, and its image side S5 is convex.

[0141] The third lens L3 has positive optical power, and its object side S6 is convex, while its image side S7 is convex.

[0142] The fourth lens L4 has negative optical power, and its object side S8 is concave, as is its image side S9.

[0143] The fifth lens L5 has negative optical power, and its object side S10 is concave, and its image side S11 is concave.

[0144] The sixth lens L6 has positive optical power, and its object side S11 is convex, and its image side S12 is convex.

[0145] The seventh lens L7 has positive optical power, and its object side S13 is convex, and its image side S14 is convex.

[0146] The eighth lens L8 has positive optical power, and its object side S15 is convex, and its image side S16 is convex.

[0147] The ninth lens L9 has negative optical power, and its object side S16 is concave, and its image side S17 is concave.

[0148] The fifth lens L5 and the sixth lens L6 form a cemented lens, and the eighth lens L8 and the ninth lens L9 form a cemented lens.

[0149] The optical lens may also include an aperture stop STO, which may be positioned between the first lens L1 and the second lens L2 to improve image quality.

[0150] Optionally, the optical lens may also include a filter CG having an object-side surface S18 and an image-side surface S19 and / or a protective glass (not shown) having an object-side surface and an image-side surface. The filter CG and / or the protective glass can be used to correct color aberrations, and can also be used to protect the image sensor chip located at the imaging surface IMA (S20). Light from the object passes sequentially through each surface S1 to S19 and is finally imaged onto the imaging surface IMA (S20).

[0151] Table 3 shows the radius of curvature, thickness / distance, refractive index, and Abbe number of each lens in the optical lens of Example 3, wherein the units of radius of curvature and thickness / distance are millimeters (mm).

[0152]

[0153]

[0154] Table 3

[0155] In this embodiment, the aperture number Fno of the optical lens is 1.60, the diagonal length (holographic height) Img of the effective pixel area on the imaging plane is 8.49mm, and the absolute value of the maximum optical distortion DIS, |DIS|, is 1.20%.

[0156] Figure 6 A distortion diagram of the optical lens of Embodiment 3 is shown, representing the distortion magnitude values ​​corresponding to different fields of view. According to... Figure 6 It can be seen that the optical lens given in Example 3 has the characteristics of low distortion and can achieve good imaging quality.

[0157] Example 4

[0158] The following is for reference Figure 7 An optical lens according to Embodiment 4 of this application is described. Figure 7 A schematic diagram of the structure of an optical lens according to Embodiment 4 of this application is shown.

[0159] like Figure 8 As shown, the optical lens includes, in sequence from the object side to the image side, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, and a ninth lens L9.

[0160] The first lens L1 has negative optical power, with its object side S1 being convex and its image side S2 being concave.

[0161] The second lens L2 has positive optical power, and its object side S4 is convex, and its image side S5 is convex.

[0162] The third lens L3 has positive optical power, and its object side S6 is convex, while its image side S7 is convex.

[0163] The fourth lens L4 has negative optical power, and its object side S8 is concave, as is its image side S9.

[0164] The fifth lens L5 has negative optical power, and its object side S10 is concave, and its image side S11 is concave.

[0165] The sixth lens L6 has positive optical power, and its object side S11 is convex, and its image side S12 is convex.

[0166] The seventh lens L7 has positive optical power, and its object side S13 is convex, and its image side S14 is convex.

[0167] The eighth lens L8 has positive optical power, and its object side S15 is convex, and its image side S16 is convex.

[0168] The ninth lens L9 has negative optical power, and its object side S16 is concave, and its image side S17 is concave.

[0169] The fifth lens L5 and the sixth lens L6 form a cemented lens, and the eighth lens L8 and the ninth lens L9 form a cemented lens.

[0170] The optical lens may also include an aperture stop STO, which may be positioned between the first lens L1 and the second lens L2 to improve image quality.

[0171] Optionally, the optical lens may also include a filter CG having an object-side surface S18 and an image-side surface S19 and / or a protective glass (not shown) having an object-side surface and an image-side surface. The filter CG and / or the protective glass can be used to correct color aberrations, and can also be used to protect the image sensor chip located at the imaging surface IMA (S20). Light from the object passes sequentially through each surface S1 to S19 and is finally imaged onto the imaging surface IMA (S20).

[0172] Table 4 shows the radius of curvature, thickness / distance, refractive index, and Abbe number of each lens in the optical lens of Example 4, where the units for radius of curvature and thickness / distance are millimeters (mm).

[0173]

[0174] Table 4

[0175] In this embodiment, the aperture number Fno of the optical lens is 1.75, the diagonal length (holographic height) Img of the effective pixel area on the imaging plane is 8.71mm, and the absolute value of the maximum optical distortion DIS, |DIS|, is 0.61%.

[0176] Figure 8 A distortion diagram of the optical lens of Embodiment 4 is shown, representing the distortion magnitude values ​​corresponding to different fields of view. According to... Figure 8 As can be seen, the optical lens given in Example 4 has the characteristics of low distortion and can achieve good imaging quality.

[0177] Example 5

[0178] The following is for reference Figure 9 An optical lens according to Embodiment 5 of this application is described. Figure 9 A schematic diagram of the structure of an optical lens according to Embodiment 5 of this application is shown.

[0179] like Figure 9 As shown, the optical lens includes, in sequence from the object side to the image side, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, and a ninth lens L9.

[0180] The first lens L1 has negative optical power, with its object side S1 being convex and its image side S2 being concave.

[0181] The second lens L2 has positive optical power, and its object side S4 is convex, and its image side S5 is convex.

[0182] The third lens L3 has positive optical power, and its object side S6 is convex, while its image side S7 is convex.

[0183] The fourth lens L4 has negative optical power, and its object side S7 is concave, as is its image side S8.

[0184] The fifth lens L5 has negative optical power, and its object side S9 is concave, and its image side S10 is concave.

[0185] The sixth lens L6 has positive optical power, and its object side S10 is convex, and its image side S11 is convex.

[0186] The seventh lens L7 has positive optical power, and its object side S12 is convex, and its image side S13 is convex.

[0187] The eighth lens L8 has positive optical power, and its object side S14 is convex, and its image side S15 is convex.

[0188] The ninth lens L9 has negative optical power, and its object side S15 is concave, and its image side S16 is concave.

[0189] The third lens L3 and the fourth lens L4 form a cemented lens, the fifth lens L5 and the sixth lens L6 form a cemented lens, and the eighth lens L8 and the ninth lens L9 form a cemented lens.

[0190] The optical lens may also include an aperture stop STO, which may be positioned between the first lens L1 and the second lens L2 to improve image quality.

[0191] Optionally, the optical lens may also include a filter CG having an object-side surface S17 and an image-side surface S18 and / or a protective glass (not shown) having an object-side surface and an image-side surface. The filter CG and / or the protective glass can be used to correct color aberrations, and can also be used to protect the image sensor chip located at the imaging surface IMA (S19). Light from the object passes sequentially through each surface S1 to S18 and is finally imaged onto the imaging surface IMA (S19).

[0192] Table 5 shows the radius of curvature, thickness / distance, refractive index, and Abbe number of each lens in the optical lens of Example 5, wherein the units of radius of curvature and thickness / distance are millimeters (mm).

[0193]

[0194] Table 5

[0195] In this embodiment, the aperture number Fno of the optical lens is 1.75, the diagonal length (holographic height) Img of the effective pixel area on the imaging plane is 8.76mm, and the absolute value of the maximum optical distortion DIS, |DIS|, is 2.89%.

[0196] Figure 10 A distortion diagram of the optical lens of Embodiment 5 is shown, representing the distortion magnitude values ​​corresponding to different fields of view. According to... Figure 10 It can be seen that the optical lens given in Example 5 has the characteristics of low distortion and can achieve good imaging quality.

[0197] In summary, Examples 1 to 5 satisfy the relationships shown in Table 6 below.

[0198] Conditional Implementation Examples Example 1 Example 2 Example 3 Example 4 Example 5 0.3 ≤ F / TTL ≤ 0.8 0.576 0.609 0.523 0.411 0.413 0.24≤BFL / TTL≤0.32 0.300 0.304 0.299 0.290 0.257 -6.5≤F1 / F≤-0.83 -3.241 -5.186 -1.549 -1.455 -1.561 0.89≤F² / F≤1.9 1.191 1.287 1.184 1.301 1.001 0.6 ≤ F3 / F ≤ 1.2 0.787 0.835 0.810 0.993 1.108 -0.9≤F4 / F≤-0.3 -0.557 -0.531 -0.566 -0.747 -0.577 -0.65≤F5 / F≤-0.25 -0.380 -0.399 -0.503 -0.484 -0.611 0.55≤F6 / F≤0.8 0.631 0.648 0.723 0.731 0.617 0.5≤F7 / F≤1.27 0.622 0.619 0.640 0.754 1.176 0.45≤F8 / F≤1.03 0.637 0.597 0.565 0.682 0.959 -0.84≤F9 / F≤-0.25 -0.378 -0.377 -0.356 -0.450 -0.769 -16.1≤F34 / F≤-0.45 -4.709 -2.817 -7.143 -14.030 -1.616 -3.95≤F56 / F≤4.66 -1.575 -1.621 -2.870 -2.448 3.581 -8.15≤F89 / F≤-0.32 -1.305 -1.552 -1.438 -2.022 -7.170 0.65≤D34 / D56≤1.73 0.879 1.169 1.588 1.285 0.786 1.9≤(ND7+ND8) / ND9≤2.0 1.924 1.979 1.962 1.962 1.973 70≤(VD3+VD8) / 2≤90 78.555 85.300 76.795 79.250 85.900 0.26≤DM7 / TTL≤0.33 0.314 0.304 0.311 0.292 0.281 0.04≤d12 / F≤0.3 0.076 0.089 0.087 0.261 0.116

[0199] Table 6

[0200] This application also provides an electronic device that may include an optical lens according to the above embodiments of this application and an imaging element for converting an optical image formed by the optical lens into an electrical signal.

[0201] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. An optical lens, characterized in that, The optical lens comprises, along the optical axis from the object side to the image side, the following in sequence: A first lens with negative optical power; A second lens with positive optical power; A third lens with positive optical power; A fourth lens with negative optical power; A fifth lens with negative optical power; A sixth lens with positive optical power; A seventh lens with positive optical power; An eighth lens with positive optical power; and A ninth lens with negative optical power; The optical lens has nine lenses with optical power. The combined focal length F34 of the third lens and the fourth lens satisfies the following condition with respect to the effective focal length F of the optical lens: -14.030≤F34 / F≤-1.

616.

2. The optical lens according to claim 1, wherein, The object side of the first lens is convex, and the image side is concave.

3. The optical lens according to claim 1, wherein, The object-side surface of the second lens is convex.

4. The optical lens according to claim 1, wherein, The object-side surface of the third lens is convex, and the image-side surface is also convex.

5. The optical lens according to claim 1, wherein, The object-side surface of the fourth lens is concave, and the image-side surface is also concave.

6. The optical lens according to claim 1, wherein, The object-side surface of the fifth lens is concave, and the image-side surface is also concave.

7. The optical lens according to claim 1, wherein, The object-side surface of the sixth lens is convex, and the image-side surface is also convex.

8. The optical lens according to claim 1, wherein, The object-side surface of the seventh lens is convex, and the image-side surface is also convex.

9. The optical lens according to claim 1, wherein, The object-side surface of the eighth lens is convex, and the image-side surface is also convex.

10. The optical lens according to claim 1, wherein, The object-side surface of the ninth lens is concave, and the image-side surface is also concave.

11. The optical lens according to any one of claims 1-10, wherein, The effective focal length F of the optical lens and the distance TTL from the object side of the first lens to the imaging surface of the optical lens on the optical axis satisfy the following condition: 0.37≤F / TTL≤0.

65.

12. The optical lens according to any one of claims 1-10, wherein, The back focal length BFL of the optical lens and the distance TTL from the object side of the first lens to the imaging surface of the optical lens on the optical axis satisfy the following condition: 0.24≤BFL / TTL≤0.

32.

13. The optical lens according to any one of claims 1-10, wherein, The effective focal length F1 of the first lens and the effective focal length F of the optical lens satisfy: -5.186≤F1 / F≤-1.

455.

14. The optical lens according to any one of claims 1-10, wherein, The effective focal length F2 of the second lens and the effective focal length F of the optical lens satisfy: 1.001≤F2 / F≤1.

301.

15. The optical lens according to any one of claims 1-10, wherein, The effective focal length F3 of the third lens and the effective focal length F of the optical lens satisfy the following condition: 0.787≤F3 / F≤1.

108.

16. The optical lens according to any one of claims 1-10, wherein, The effective focal length F4 of the fourth lens and the effective focal length F of the optical lens satisfy the following condition: -0.79≤F4 / F≤-0.

49.

17. The optical lens according to any one of claims 1-10, wherein, The effective focal length F5 of the fifth lens and the effective focal length F of the optical lens satisfy the following condition: -0.65≤F5 / F≤-0.

34.

18. The optical lens according to any one of claims 1-10, wherein, The effective focal length F6 of the sixth lens and the effective focal length F of the optical lens satisfy the following condition: 0.617≤F6 / F≤0.

731.

19. The optical lens according to any one of claims 1-10, wherein, The effective focal length F7 of the seventh lens and the effective focal length F of the optical lens satisfy the following condition: 0.619≤F7 / F≤1.

176.

20. The optical lens according to any one of claims 1-10, wherein, The effective focal length F8 of the eighth lens and the effective focal length F of the optical lens satisfy the following condition: 0.565≤F8 / F≤0.

959.

21. The optical lens according to any one of claims 1-10, wherein, The effective focal length F9 of the ninth lens and the effective focal length F of the optical lens satisfy the following condition: -0.769≤F9 / F≤-0.

356.

22. The optical lens according to any one of claims 1-10, wherein, The combined focal length F56 of the fifth lens and the sixth lens satisfies the following condition with respect to the effective focal length F of the optical lens: -2.870≤F56 / F≤3.

581.

23. The optical lens according to any one of claims 1-10, wherein, The combined focal length F89 of the eighth lens and the ninth lens satisfies the following condition with respect to the effective focal length F of the optical lens: -7.170≤F89 / F≤-1.

305.

24. The optical lens according to any one of claims 1-10, wherein, The sum of the center thicknesses of the third and fourth lenses on the optical axis, D34, and the sum of the center thicknesses of the fifth and sixth lenses on the optical axis, D56, satisfy the condition: 0.786 ≤ D34 / D56 ≤ 1.

588.

25. The optical lens according to any one of claims 1-10, wherein, The refractive index ND7 of the seventh lens, the refractive index ND8 of the eighth lens, and the refractive index ND9 of the ninth lens satisfy the following condition: 1.9≤(ND7+ND8) / ND9≤2.

0.

26. The optical lens according to any one of claims 1-10, wherein, The Abbe number VD3 of the third lens and the Abbe number VD8 of the eighth lens satisfy the following condition: 76.795 ≤ (VD3 + VD8) / 2 ≤ 85.

900.

27. The optical lens according to any one of claims 1-10, wherein, The maximum optical aperture DM7 of the seventh lens and the distance TTL from the object side of the first lens to the imaging surface of the optical lens on the optical axis satisfy the following condition: 0.26≤DM7 / TTL≤0.

33.

28. The optical lens according to any one of claims 1-10, wherein, The air gap d12 between the first lens and the second lens on the optical axis and the effective focal length F of the optical lens satisfy the following condition: 0.04≤d12 / F≤0.3.

Images