Optical system

Abstract

The application discloses an optical system which comprises, in order from the object side to the image side along the optical axis, a first lens with positive refractive power, the object side surface of which is a convex surface and the image side surface of which is a concave surface; a second lens with positive refractive power, the object side surface of which is a convex surface and the image side surface of which is a concave surface; a third lens with negative refractive power, the object side surface of which is a convex surface and the image side surface of which is a concave surface; a fourth lens with positive refractive power, the object side surface of which is a convex surface; a fifth lens with negative refractive power, the image side surface of which is a concave surface; a sixth lens with positive refractive power, the object side surface of which is a convex surface and the image side surface of which is a concave surface; a seventh lens with positive refractive power, the object side surface of which is a convex surface and the image side surface of which is a convex surface; an eighth lens with negative refractive power, the object side surface of which is a concave surface and the image side surface of which is a concave surface; and a ninth lens with negative refractive power, the object side surface of which is a concave surface and the image side surface of which is a convex surface; wherein the optical system has nine lenses with refractive power.

Description

Technical Field

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

[0002] In recent years, with the continuous advancement of technology, sighting lenses have been widely used in fields such as hunting, sports shooting, and distance measurement, which has also placed higher demands on the imaging quality of sighting lenses.

[0003] However, existing observation and aiming lenses often have some problems. For example, they are too heavy and bulky, making them less portable; or, while achieving miniaturization, they struggle to achieve features such as telephoto lenses and high image quality, thus failing to meet the need for discerning minute details; or, their image quality is poor at night, making them unsuitable for nighttime observation. Summary of the Invention

[0004] This application provides an optical system that can at least solve or partially solve at least one problem or other problems existing in the prior art.

[0005] This application provides an optical system comprising, along the optical axis from the object side to the image side, the following in sequence: a first lens with positive optical power, having a convex object side and a concave image side; a second lens with positive optical power, having a convex object side and a concave image side; a third lens with negative optical power, having a convex object side and a concave image side; a fourth lens with positive optical power, having a convex object side; a fifth lens with negative optical power, having a concave image side; a sixth lens with positive optical power, having a convex object side and a concave image side; a seventh lens with positive optical power, having a convex object side and a convex image side; an eighth lens with negative optical power, having a concave object side and a concave image side; and a ninth lens with negative optical power, having a concave object side and a convex image side. The optical system comprises nine lenses with optical power.

[0006] According to an exemplary embodiment of this application, the total effective focal length F of the optical system and the total optical length TTL of the optical system satisfy: 0.8≤TTL / F≤1.0.

[0007] According to an exemplary embodiment of this application, the maximum aperture Dmax of the optical system and the total optical length TTL of the optical system satisfy: 0.2≤Dmax / TTL≤0.4.

[0008] According to an exemplary embodiment of this application, the back focal length BFL of the optical system and the total effective focal length F of the optical system satisfy: 0.1≤BFL / F≤0.3.

[0009] According to an exemplary embodiment of this application, a second lens, a third lens, a fourth lens, and a fifth lens are cemented together to form a cemented lens. The combined focal length F2345 of the second, third, fourth, and fifth lenses satisfies the condition that -0.7 ≤ F2345 / F ≤ -0.5 with respect to the total effective focal length F of the optical system.

[0010] According to an exemplary embodiment of this application, the effective focal length F1 of the first lens and the total effective focal length F of the optical system satisfy: 0.7≤F1 / F≤1.0.

[0011] According to an exemplary embodiment of this application, the effective focal length F2 of the second lens and the total effective focal length F of the optical system satisfy: 0.7≤F2 / F≤1.0.

[0012] According to an exemplary embodiment of this application, the effective focal length F3 of the third lens and the total effective focal length F of the optical system satisfy: -0.5≤F3 / F≤-0.2.

[0013] According to an exemplary embodiment of this application, the effective focal length F4 of the fourth lens and the total effective focal length F of the optical system satisfy: 0.3≤F4 / F≤0.5.

[0014] According to an exemplary embodiment of this application, the effective focal length F5 of the fifth lens and the total effective focal length F of the optical system satisfy: -0.4≤F5 / F≤-0.2.

[0015] According to an exemplary embodiment of this application, the effective focal length F6 of the sixth lens and the total effective focal length F of the optical system satisfy: 0.6≤F6 / F≤0.9.

[0016] According to an exemplary embodiment of this application, the effective focal length F7 of the seventh lens and the total effective focal length F of the optical system satisfy: 0.1≤F7 / F≤0.3.

[0017] According to an exemplary embodiment of this application, the effective focal length F8 of the eighth lens and the total effective focal length F of the optical system satisfy: -0.3≤F8 / F≤-0.1.

[0018] According to an exemplary embodiment of this application, the effective focal length F9 of the ninth lens and the total effective focal length F of the optical system satisfy: -1.0≤F9 / F≤-0.5.

[0019] According to an exemplary embodiment of this application, a seventh lens and an eighth lens are cemented together to form a cemented lens. The combined focal length F78 of the seventh and eighth lenses satisfies the condition that 0.6 ≤ F78 / F ≤ 1.1 with respect to the total effective focal length F of the optical system.

[0020] According to an exemplary embodiment of this application, the combined focal length FG1 of the first to sixth lenses and the total effective focal length F of the optical system satisfy: 0.9≤FG1 / F≤1.1.

[0021] According to an exemplary embodiment of this application, the seventh lens and the eighth lens are cemented together to form a cemented lens. The combined focal length FG2 of the seventh to ninth lenses satisfies the condition that -8.0 ≤ FG2 / F ≤ -2.5 with respect to the total effective focal length F of the optical system.

[0022] According to an exemplary embodiment of this application, the optical system satisfies at least one of the following conditions: 65≤VD2≤75, 65≤VD4≤75, 90≤VD6≤100, where VD2 is the Abbe number of the second lens, VD4 is the Abbe number of the fourth lens, and VD6 is the Abbe number of the sixth lens. Attached Figure Description

[0023] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings. In the drawings:

[0024] Figure 1 A schematic diagram of the structure of the optical system according to Embodiment 1 of this application is shown;

[0025] Figure 2 A schematic diagram of the structure of the optical system according to Embodiment 2 of this application is shown;

[0026] Figure 3 A schematic diagram of the structure of the optical system according to Embodiment 3 of this application is shown;

[0027] Figure 4 A schematic diagram of the structure of the optical system according to Embodiment 4 of this application is shown; and

[0028] Figure 5 A schematic diagram of the structure of an optical system according to Embodiment 5 of this application is shown. Detailed Implementation

[0029] To better understand this application, various aspects of this application will be described in detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely descriptions of exemplary embodiments of this application and are not intended to limit the scope of this application in any way.

[0030] 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 drawn strictly to scale.

[0031] 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 plane is called the image-side surface of the lens.

[0032] It should also be understood that the terms "comprising," "including," "having," "containing," and / or "comprises" as 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. It should be noted that in this specification, the expressions "first," "second," "third," etc., are used only to distinguish one feature from another and do not imply any limitation on the features.

[0033] Unless otherwise specified, all terms used herein shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. Terms shall be interpreted as having the meaning consistent with their meaning in the context of the relevant art and shall not be interpreted in an idealized or overly formal sense unless expressly stated herein.

[0034] 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.

[0035] An optical system according to an exemplary embodiment of this application may include 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, and these nine lenses are arranged sequentially along the optical axis from the object side to the image side.

[0036] In an exemplary embodiment, the first lens may have positive optical power. The first lens collects light, and by setting the first lens as a positive lens, the light rays emitted from the first lens can be made to be as close as possible to the direction of the optical axis, effectively reducing the aperture of the rear lens, thereby achieving miniaturization of the optical system.

[0037] As an example, the object-side surface of the first lens can be convex, and the image-side surface can be concave. By setting the image-side surface of the first lens to be concave, the incident angle of on-axis rays on the image-side surface of the first lens can be effectively reduced, thereby reducing the spherical aberration generated by the image-side surface of the first lens, which is beneficial to achieving high image quality of the optical system.

[0038] In an exemplary embodiment, the second lens may have positive optical power. The object-side surface of the second lens may be convex, and the image-side surface may be concave. By setting the second lens as a positive lens and the image-side surface of the second lens as concave, the incident angle of on-axis rays on the image-side surface of the second lens can be effectively reduced, thereby reducing the spherical aberration generated by the image-side surface of the second lens, which is beneficial to achieving high image quality of the optical system.

[0039] In an exemplary embodiment, the third lens may have negative optical power. The object-side surface of the third lens may be convex, and the image-side surface may be concave. By setting the third lens as a negative lens and the object-side surface of the third lens to be convex, the incident angle of on-axis rays on the object-side surface of the third lens can be effectively reduced, thereby reducing the spherical aberration generated by the object-side surface of the third lens, which is beneficial to achieving high image quality of the optical system.

[0040] In an exemplary embodiment, the fourth lens may have positive optical power. The object-side surface of the fourth lens may be convex, and the image-side surface may be convex or concave. By setting the fourth lens as a positive lens and having a convex object-side surface, aberrations can be effectively reduced, which is beneficial for achieving high image quality in the optical system.

[0041] In an exemplary embodiment, the fifth lens may have negative optical power. The object-side surface of the fifth lens may be convex or concave, and the image-side surface may be concave. By setting the fifth lens as a negative lens and its image-side surface as concave, aberrations can be effectively reduced, which is beneficial for achieving high image quality in the optical system.

[0042] In an exemplary embodiment, the sixth lens may have positive optical power. The object-side surface of the sixth lens may be convex, and the image-side surface may be concave. By configuring the sixth lens with the above-described structure and using a low-dispersion material, it is beneficial to apochromatic the optical system and achieve infrared confocality of the optical system.

[0043] In an exemplary embodiment, the seventh lens may have positive optical power. The object-side surface of the seventh lens may be convex, and the image-side surface may also be convex. By setting the seventh lens as a biconvex positive lens, the object-side and image-side surfaces of the seventh lens can share the optical power of the seventh lens, reducing the surface curvature of the object-side and image-side surfaces of the seventh lens, reducing the generation of aberrations, and thus facilitating the achievement of high image quality in the optical system.

[0044] As an example, the seventh and eighth lenses are cemented together to form a cemented lens, such as a cemented doublet. By cementing the seventh and eighth lenses together to form a cemented lens, it is beneficial to correct residual chromatic aberration in the optical system and achieve high image quality.

[0045] As an example, the seventh lens has positive optical power in a cemented lens and is combined with a low dispersion material, which is beneficial for apochromatic optical systems and enables infrared confocal optical systems.

[0046] In an exemplary embodiment, the eighth lens may have negative optical power. The object-side surface of the eighth lens may be concave, and the image-side surface may also be concave. By configuring the eighth lens as a biconcave negative lens, the object-side and image-side surfaces of the eighth lens can share the optical power, reducing the surface curvature of the object-side and image-side surfaces, thus reducing aberrations and contributing to high image quality in the optical system. Furthermore, the eighth lens's negative optical power in a cemented lens, when used in conjunction with the seventh lens, can apochromatic the optical system, achieving high image quality.

[0047] In an exemplary embodiment, the ninth lens may have negative optical power. The object-side surface of the ninth lens may be concave, and the image-side surface may be convex. By setting the ninth lens as a negative lens and having a concave object-side surface, it is beneficial to reduce the overall optical length of the optical system and achieve miniaturization of the optical system.

[0048] As an example, the ninth lens uses a high refractive index material, which can enhance the ability of the ninth lens to bend light, reduce the surface curvature of the object side and image side of the ninth lens, reduce the generation of aberrations, and help to achieve high image quality of the optical system.

[0049] In an exemplary embodiment, the second lens, the third lens, the fourth lens, and the fifth lens are cemented together to form a cemented lens, such as a four-cemented lens.

[0050] In an exemplary embodiment, the optical system may further include an aperture stop. The aperture stop may be disposed between the first lens and the second lens.

[0051] In an exemplary embodiment, the total effective focal length F of the optical system and the total optical length TTL of the optical system can satisfy: 0.8 ≤ TTL / F ≤ 1.0. By reasonably configuring the ratio of the total optical length to the total effective focal length of the optical system, the total optical length of the optical system can be effectively reduced while keeping the total effective focal length constant, thereby achieving miniaturization of the optical system.

[0052] In an exemplary embodiment, the maximum aperture Dmax of the optical system and the total optical length TTL of the optical system can satisfy: 0.2 ≤ Dmax / TTL ≤ 0.4. By rationally configuring the ratio of the maximum aperture Dmax to the total optical length of the optical system, given a fixed total optical length, the maximum aperture Dmax of the optical system can be made smaller, which is beneficial for miniaturizing the optical system.

[0053] In an exemplary embodiment, the back focal length BFL of the optical system and the total effective focal length F of the optical system can satisfy: 0.1 ≤ BFL / F ≤ 0.3. By rationally configuring the ratio of the back focal length to the total effective focal length of the optical system, miniaturization of the optical system can be achieved while constraining the back focal length within a certain range, which is beneficial for the assembly of the optical system.

[0054] In an exemplary embodiment, the combined focal length F2345 of the second, third, fourth, and fifth lenses and the total effective focal length F of the optical system can satisfy: -0.7 ≤ F2345 / F ≤ -0.5. By rationally configuring the ratio of the combined focal length of the second, third, fourth, and fifth lenses to the total effective focal length of the optical system, the four-cemented lens formed by the second, third, fourth, and fifth lenses can compensate for the on-axis chromatic aberration generated by the first lens, which is beneficial for achieving infrared confocality in the optical system. Simultaneously, it also enables the four-cemented lens to have negative optical power, and the positive spherical aberration generated by the four-cemented lens can effectively compensate for the negative spherical aberration generated by the first lens, thereby achieving high image quality in the optical system.

[0055] In an exemplary embodiment, the effective focal length F1 of the first lens and the total effective focal length F of the optical system can satisfy: 0.7 ≤ F1 / F ≤ 1.0. By rationally configuring the ratio of the effective focal length of the first lens to the total effective focal length of the optical system, the light rays emitted from the first lens can be directed closer to the optical axis, which is beneficial for reducing the aperture of the rear lens and thus achieving miniaturization of the optical system.

[0056] In an exemplary embodiment, the effective focal length F2 of the second lens and the total effective focal length F of the optical system can satisfy: 0.7 ≤ F2 / F ≤ 1.0. The second lens uses a low-dispersion material, and by using a reasonable ratio of the effective focal length of the second lens to the total effective focal length of the optical system, chromatic aberration can be effectively reduced, the difficulty of correcting chromatic aberration in the optical system can be lowered, and high image quality of the optical system can be achieved.

[0057] In an exemplary embodiment, the effective focal length F3 of the third lens and the total effective focal length F of the optical system can satisfy: -0.5 ≤ F3 / F ≤ -0.2. By rationally configuring the ratio of the effective focal length of the third lens to the total effective focal length of the optical system, the third lens can achieve negative optical power in the four-crystal lens configuration. Combined with the fourth lens, it can achieve apochromatic aberration and realize high image quality in the optical system.

[0058] In an exemplary embodiment, the effective focal length F4 of the fourth lens and the total effective focal length F of the optical system can satisfy: 0.3 ≤ F4 / F ≤ 0.5. The fourth lens uses a low-dispersion material, and with a reasonable ratio of its effective focal length to the total effective focal length of the optical system, the fourth lens can achieve positive optical power in the four-cement lens configuration. This facilitates apochromatic aberration in the optical system and enables infrared confocal focusing of the optical system.

[0059] In an exemplary embodiment, the effective focal length F5 of the fifth lens and the total effective focal length F of the optical system can satisfy: -0.4 ≤ F5 / F ≤ -0.2. By rationally configuring the ratio of the effective focal length of the fifth lens to the total effective focal length of the optical system, the fifth lens can achieve negative optical power in a four-crystal lens configuration. Combined with the fourth lens, it can achieve apochromatic aberration, resulting in high image quality for the optical system.

[0060] In an exemplary embodiment, the effective focal length F6 of the sixth lens and the total effective focal length F of the optical system can satisfy: 0.6 ≤ F6 / F ≤ 0.9. By rationally configuring the ratio of the effective focal length of the sixth lens to the total effective focal length of the optical system, aberrations generated by the front-end lens can be effectively corrected, achieving high image quality in the optical system.

[0061] In an exemplary embodiment, the effective focal length F7 of the seventh lens and the total effective focal length F of the optical system can satisfy: 0.1 ≤ F7 / F ≤ 0.3. The seventh lens uses a low-dispersion material, and with a reasonable ratio of its effective focal length to the total effective focal length of the optical system, the seventh lens can achieve positive optical power in a cemented doublet, which is beneficial for apochromatic aberration in the optical system and for realizing infrared confocality of the optical system.

[0062] In an exemplary embodiment, the effective focal length F8 of the eighth lens and the total effective focal length F of the optical system can satisfy: -0.3 ≤ F8 / F ≤ -0.1. By rationally configuring the ratio of the effective focal length of the eighth lens to the total effective focal length of the optical system, the eighth lens can achieve negative optical power in a cemented doublet, and when paired with the seventh lens, it can achieve apochromatic aberration, thus realizing high image quality in the optical system.

[0063] In an exemplary embodiment, the effective focal length F9 of the ninth lens and the total effective focal length F of the optical system can satisfy: -1.0 ≤ F9 / F ≤ -0.5. By rationally configuring the ratio of the effective focal length of the ninth lens to the total effective focal length of the optical system, the ninth lens can have negative optical power, effectively reducing the total optical length of the optical system, thereby achieving miniaturization of the optical system.

[0064] In an exemplary embodiment, the combined focal length F78 of the seventh and eighth lenses and the total effective focal length F of the optical system can satisfy: 0.6 ≤ F78 / F ≤ 1.1. By rationally configuring the ratio of the combined focal length of the seventh and eighth lenses to the total effective focal length of the optical system, the focal lengths of the seventh and eighth lenses can be reasonably allocated, effectively correcting residual chromatic aberration in the optical system and achieving high image quality.

[0065] In an exemplary embodiment, the combined focal length FG1 of the first to sixth lenses and the total effective focal length F of the optical system can satisfy: 0.9 ≤ FG1 / F ≤ 1.1. By rationally configuring the ratio of the combined focal length of the first to sixth lenses to the total effective focal length of the optical system, the focal length of the lens group formed by the first to sixth lenses can be made positive, effectively reducing the total optical length of the optical system and thus achieving miniaturization of the optical system.

[0066] In an exemplary embodiment, the combined focal length FG2 of the seventh to ninth lenses and the total effective focal length F of the optical system can satisfy: -8.0 ≤ FG2 / F ≤ -2.5. By rationally configuring the ratio of the combined focal length of the seventh to ninth lenses to the total effective focal length of the optical system, the focal length of the lens group formed by the seventh to ninth lenses can be made negative, effectively correcting the residual chromatic aberration of the optical system and achieving high image quality.

[0067] In an exemplary embodiment, the Abbe number VD2 of the second lens can satisfy: 65 ≤ VD2 ≤ 75. Properly configuring the Abbe number of the second lens can reduce chromatic aberration, lower the difficulty of chromatic aberration correction in the optical system, and facilitate the realization of infrared confocal optical systems.

[0068] In an exemplary embodiment, the Abbe number VD4 of the fourth lens can satisfy: 65 ≤ VD4 ≤ 75. Properly configuring the Abbe number of the fourth lens can reduce chromatic aberration, lower the difficulty of chromatic aberration correction in the optical system, and facilitate the realization of infrared confocal optical systems.

[0069] In an exemplary embodiment, the Abbe number VD6 of the sixth lens can satisfy: 90 ≤ VD6 ≤ 100. Properly configuring the Abbe number of the sixth lens can reduce chromatic aberration, lower the difficulty of chromatic aberration correction in the optical system, and facilitate the realization of infrared confocal optical systems.

[0070] The optical system 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 can be achieved: miniaturization, long focal length, high image quality, and infrared confocal focus. The optical system provided by this application has good infrared confocal performance, provides good imaging quality at night, meets the requirements for nighttime observation, and can, for example, be 4K high image quality.

[0071] Those skilled in the art should understand that the total optical length (TTL) of the optical system used above refers to the axial distance from the object side of the first lens to the imaging plane; and the back focal length (BFL) of the optical system refers to the axial distance from the image side of the ninth lens to the imaging plane.

[0072] However, those skilled in the art should understand that, without departing from the technical solutions claimed in this application, the number of lenses constituting the optical system can be changed to obtain the various results and advantages described in this specification.

[0073] Specific embodiments of the optical system applicable to the above-described embodiments are further described below with reference to the accompanying drawings.

[0074] Example 1

[0075] The following is for reference Figure 1 An optical system according to Embodiment 1 of this application is described. Figure 1 This is a schematic diagram of the optical system according to Embodiment 1 of this application.

[0076] like Figure 1 As shown, the optical system, along the optical axis from the object side to the image side, sequentially includes 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. An aperture stop STO is positioned between the first lens L1 and the second lens L2. The second lens L2, the third lens L3, the fourth lens L4, and the fifth lens L5 are cemented together to form a cemented lens, such as a four-cemented lens. The seventh lens L7 and the eighth lens L8 are cemented together to form a cemented lens, such as a two-cemented lens.

[0077] The first lens L1 has positive optical power, with its object side S1 being convex and its image side S2 being concave.

[0078] The second lens L2 has positive optical power, and its object side S4 is convex while its image side is concave.

[0079] The third lens L3 has negative optical power, and its object side S5 is convex while its image side is concave.

[0080] The fourth lens L4 has positive optical power, and its object-side surface S6 is convex, as is its image-side surface.

[0081] The fifth lens L5 has negative optical power, and its object side S7 is concave, as is its image side S8.

[0082] The sixth lens L6 has positive optical power, with its object side S9 being convex and its image side S10 being concave.

[0083] The seventh lens L7 has positive optical power, and its object side S11 is convex, as is its image side.

[0084] The eighth lens L8 has negative optical power, and its object side S12 is concave, and its image side S13 is concave.

[0085] The ninth lens L9 has negative optical power, with its object side S14 being concave and its image side S15 being convex.

[0086] A filter CG can also be placed between the ninth lens L9 and the imaging plane IMA. The filter CG has an object-side surface S16 and an image-side surface S17. Light from the object passes sequentially through surfaces S1-S2 and S4-S17 and is finally imaged onto the imaging plane IMA. It should be noted that surfaces S1-S2 and S4-S17 are... Figure 1 Not shown in the image.

[0087] Table 1 shows the basic parameters of the optical system of Example 1, where the units for radius of curvature, thickness / distance, and focal length are millimeters (mm).

[0088]

[0089]

[0090] Table 1

[0091] In this embodiment, the total optical length (TTL) of the optical system is 54.53 mm, the aperture value (FNO) of the optical system is 2.2, and the total effective focal length (F) of the optical system is 60 mm.

[0092] Example 2

[0093] The following is for reference Figure 2 An optical system according to Embodiment 2 of this application is described. Figure 2 This is a schematic diagram of the optical system according to Embodiment 2 of this application.

[0094] like Figure 2As shown, the optical system, along the optical axis from the object side to the image side, sequentially includes 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. An aperture stop STO is positioned between the first lens L1 and the second lens L2. The second lens L2, the third lens L3, the fourth lens L4, and the fifth lens L5 are cemented together to form a cemented lens, such as a four-cemented lens. The seventh lens L7 and the eighth lens L8 are cemented together to form a cemented lens, such as a two-cemented lens.

[0095] The first lens L1 has positive optical power, with its object side S1 being convex and its image side S2 being concave.

[0096] The second lens L2 has positive optical power, and its object side S4 is convex while its image side is concave.

[0097] The third lens L3 has negative optical power, and its object side S5 is convex while its image side is concave.

[0098] The fourth lens L4 has positive optical power, and its object-side surface S6 is convex, as is its image-side surface.

[0099] The fifth lens L5 has negative optical power, and its object side S7 is concave, as is its image side S8.

[0100] The sixth lens L6 has positive optical power, with its object side S9 being convex and its image side S10 being concave.

[0101] The seventh lens L7 has positive optical power, and its object side S11 is convex, as is its image side.

[0102] The eighth lens L8 has negative optical power, and its object side S12 is concave, and its image side S13 is concave.

[0103] The ninth lens L9 has negative optical power, with its object side S14 being concave and its image side S15 being convex.

[0104] A filter CG can also be placed between the ninth lens L9 and the imaging plane IMA. The filter CG has an object-side surface S16 and an image-side surface S17. Light from the object passes sequentially through surfaces S1-S2 and S4-S17 and is finally imaged onto the imaging plane IMA. It should be noted that surfaces S1-S2 and S4-S17 are... Figure 2 Not shown in the image.

[0105] Table 2 shows the basic parameters of the optical system of Example 2, where the units for radius of curvature, thickness / distance, and focal length are millimeters (mm).

[0106]

[0107] Table 2

[0108] In this embodiment, the total optical length (TTL) of the optical system is 55 mm, the aperture value (FNO) of the optical system is 2.2, and the total effective focal length (F) of the optical system is 60 mm.

[0109] Example 3

[0110] The following is for reference Figure 3 An optical system according to Embodiment 3 of this application is described. Figure 3 This is a schematic diagram of the optical system according to Embodiment 3 of this application.

[0111] like Figure 3 As shown, the optical system includes, sequentially 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 along the optical axis. An aperture stop STO is positioned between the first lens L1 and the second lens L2. The second lens L2, the third lens L3, the fourth lens L4, and the fifth lens L5 are cemented together to form a cemented lens, such as a four-cemented lens. The seventh lens L7 and the eighth lens L8 are cemented together to form a cemented lens, such as a two-cemented lens.

[0112] The first lens L1 has positive optical power, with its object side S1 being convex and its image side S2 being concave.

[0113] The second lens L2 has positive optical power, and its object side S4 is convex while its image side is concave.

[0114] The third lens L3 has negative optical power, and its object side S5 is convex while its image side is concave.

[0115] The fourth lens L4 has positive optical power, with its object-side surface S6 being convex and its image-side surface being concave.

[0116] The fifth lens L5 has negative optical power, with its object side S7 being convex and its image side S8 being concave.

[0117] The sixth lens L6 has positive optical power, with its object side S9 being convex and its image side S10 being concave.

[0118] The seventh lens L7 has positive optical power, and its object side S11 is convex, as is its image side.

[0119] The eighth lens L8 has negative optical power, and its object side S12 is concave, and its image side S13 is concave.

[0120] The ninth lens L9 has negative optical power, with its object side S14 being concave and its image side S15 being convex.

[0121] A filter CG can also be placed between the ninth lens L9 and the imaging plane IMA. The filter CG has an object-side surface S16 and an image-side surface S17. Light from the object passes sequentially through surfaces S1-S2 and S4-S17 and is finally imaged onto the imaging plane IMA. It should be noted that surfaces S1-S2 and S4-S17 are... Figure 3 Not shown in the image.

[0122] Table 3 shows the basic parameters of the optical system of Example 3, where the units for radius of curvature, thickness / distance, and focal length are millimeters (mm).

[0123]

[0124] Table 3

[0125] In this embodiment, the total optical length (TTL) of the optical system is 55 mm, the aperture value (FNO) of the optical system is 2.2, and the total effective focal length (F) of the optical system is 60 mm.

[0126] Example 4

[0127] The following is for reference Figure 4 An optical system according to Embodiment 4 of this application is described. Figure 4 This is a schematic diagram of the optical system according to Embodiment 4 of this application.

[0128] like Figure 4 As shown, the optical system includes, sequentially 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 along the optical axis. An aperture stop STO is positioned between the first lens L1 and the second lens L2. The second lens L2, the third lens L3, the fourth lens L4, and the fifth lens L5 are cemented together to form a cemented lens, such as a four-cemented lens. The seventh lens L7 and the eighth lens L8 are cemented together to form a cemented lens, such as a two-cemented lens.

[0129] The first lens L1 has positive optical power, with its object side S1 being convex and its image side S2 being concave.

[0130] The second lens L2 has positive optical power, and its object side S4 is convex while its image side is concave.

[0131] The third lens L3 has negative optical power, and its object side S5 is convex while its image side is concave.

[0132] The fourth lens L4 has positive optical power, with its object-side surface S6 being convex and its image-side surface being concave.

[0133] The fifth lens L5 has negative optical power, with its object side S7 being convex and its image side S8 being concave.

[0134] The sixth lens L6 has positive optical power, with its object side S9 being convex and its image side S10 being concave.

[0135] The seventh lens L7 has positive optical power, and its object side S11 is convex, as is its image side.

[0136] The eighth lens L8 has negative optical power, and its object side S12 is concave, and its image side S13 is concave.

[0137] The ninth lens L9 has negative optical power, with its object side S14 being concave and its image side S15 being convex.

[0138] A filter CG can also be placed between the ninth lens L9 and the imaging plane IMA. The filter CG has an object-side surface S16 and an image-side surface S17. Light from the object passes sequentially through surfaces S1-S2 and S4-S17 and is finally imaged onto the imaging plane IMA. It should be noted that surfaces S1-S2 and S4-S17 are... Figure 4 Not shown in the image.

[0139] Table 4 shows the basic parameters of the optical system of Example 4, where the units for radius of curvature, thickness / distance, and focal length are millimeters (mm).

[0140]

[0141] Table 4

[0142] In this embodiment, the total optical length (TTL) of the optical system is 55 mm, the aperture value (FNO) of the optical system is 2.2, and the total effective focal length (F) of the optical system is 60 mm.

[0143] Example 5

[0144] The following is for reference Figure 5 An optical system according to Embodiment 5 of this application is described. Figure 5 This is a schematic diagram of the optical system according to Embodiment 5 of this application.

[0145] like Figure 5As shown, the optical system includes, sequentially 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 along the optical axis. An aperture stop STO is positioned between the first lens L1 and the second lens L2. The second lens L2, the third lens L3, the fourth lens L4, and the fifth lens L5 are cemented together to form a cemented lens, such as a four-cemented lens. The seventh lens L7 and the eighth lens L8 are cemented together to form a cemented lens, such as a two-cemented lens.

[0146] The first lens L1 has positive optical power, with its object side S1 being convex and its image side S2 being concave.

[0147] The second lens L2 has positive optical power, and its object side S4 is convex while its image side is concave.

[0148] The third lens L3 has negative optical power, and its object side S5 is convex while its image side is concave.

[0149] The fourth lens L4 has positive optical power, with its object-side surface S6 being convex and its image-side surface being concave.

[0150] The fifth lens L5 has negative optical power, with its object side S7 being convex and its image side S8 being concave.

[0151] The sixth lens L6 has positive optical power, with its object side S9 being convex and its image side S10 being concave.

[0152] The seventh lens L7 has positive optical power, and its object side S11 is convex, as is its image side.

[0153] The eighth lens L8 has negative optical power, and its object side S12 is concave, and its image side S13 is concave.

[0154] The ninth lens L9 has negative optical power, with its object side S14 being concave and its image side S15 being convex.

[0155] A filter CG can also be placed between the ninth lens L9 and the imaging plane IMA. The filter CG has an object-side surface S16 and an image-side surface S17. Light from the object passes sequentially through surfaces S1-S2 and S4-S17 and is finally imaged onto the imaging plane IMA. It should be noted that surfaces S1-S2 and S4-S17 are... Figure 5 Not shown in the image.

[0156] Table 5 shows the basic parameters of the optical system of Example 5, where the units for radius of curvature, thickness / distance, and focal length are millimeters (mm).

[0157]

[0158] Table 5

[0159] In this embodiment, the total optical length (TTL) of the optical system is 55 mm, the aperture value (FNO) of the optical system is 2.2, and the total effective focal length (F) of the optical system is 60 mm.

[0160] In summary, the conditional expressions in Examples 1 to 5 satisfy the relationships shown in Table 6.

[0161] Conditional / Example 1 2 3 4 5 TTL / F 0.908 0.917 0.917 0.917 0.917 Dmax / TTL 0.253 0.251 0.251 0.251 0.251 BFL / F 0.190 0.206 0.200 0.190 0.197 F2345 / F -0.557 -0.608 -0.570 -0.618 -0.608 F1 / F 0.802 0.812 0.909 0.907 0.915 F2 / F 0.859 0.837 0.783 0.806 0.799 F3 / F -0.333 -0.320 -0.370 -0.377 -0.337 F4 / F 0.305 0.303 0.340 0.347 0.323 F5 / F -0.254 -0.276 -0.235 -0.241 -0.261 F6 / F 0.764 0.819 0.661 0.663 0.717 F7 / F 0.158 0.163 0.173 0.174 0.177 F8 / F -0.200 -0.205 -0.209 -0.210 -0.212 F9 / F -0.530 -0.525 -0.872 -0.811 -0.807 F78 / F 0.674 0.690 0.927 0.980 0.970 FG1 / F 0.993 0.973 0.993 0.976 0.980 FG2 / F -3.308 -2.778 -7.769 -5.144 -6.225 VD2 68.3 68.3 68.3 68.3 68.3 VD4 68.3 68.3 68.3 68.3 68.3 VD6 94.5 94.5 94.5 94.5 94.5

[0162] Table 6

[0163] This application also provides an imaging device, wherein the electronic photosensitive element may be a photocoupled device (CCD) or a complementary metal oxide semiconductor device (CMOS), and the imaging device is equipped with the optical system described above.

[0164] 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 system, characterized in that, Along the optical axis from the object side to the image side, in sequence: The first lens with positive optical power has a convex object side and a concave image side. A second lens with positive optical power has a convex object-side surface and a concave image-side surface; A third lens with negative optical power has a convex object side and a concave image side. The fourth lens has positive optical power and its object side is convex. The fifth lens has negative optical power and its image-side surface is concave. The sixth lens with positive optical power has a convex object side and a concave image side. The seventh lens with positive optical power has a convex object-side surface and a convex image-side surface. An eighth lens with negative optical power, its object-side surface is concave, and its image-side surface is concave; and The ninth lens with negative optical power has a concave object side and a convex image side. The optical system has nine lenses with optical power. The optical system satisfies: 0.3≤F4 / F≤0.5, where F4 is the effective focal length of the fourth lens and F is the total effective focal length of the optical system.

2. The optical system according to claim 1, wherein, The optical system satisfies the following condition: 0.8 ≤ TTL / F ≤ 1.0, where TTL is the total optical length of the optical system.

3. The optical system according to claim 1, wherein, The optical system satisfies: 0.2≤Dmax / TTL≤0.4, where Dmax is the maximum aperture of the optical system and TTL is the total optical length of the optical system.

4. The optical system according to claim 1, wherein, The optical system satisfies: 0.1≤BFL / F≤0.3, where BFL is the back focal length of the optical system.

5. The optical system according to claim 1, wherein, The second lens, the third lens, the fourth lens, and the fifth lens are cemented together to form a cemented lens; The optical system satisfies: -0.7≤F2345 / F≤-0.5, where F2345 is the combined focal length of the second lens, the third lens, the fourth lens, and the fifth lens.

6. The optical system according to claim 1, wherein, The optical system satisfies: 0.7≤F1 / F≤1.0, where F1 is the effective focal length of the first lens.

7. The optical system according to claim 1, wherein, The optical system satisfies: 0.7≤F2 / F≤1.0, where F2 is the effective focal length of the second lens.

8. The optical system according to claim 1, wherein, The optical system satisfies: -0.5≤F3 / F≤-0.2, where F3 is the effective focal length of the third lens.

9. The optical system according to claim 1, wherein, The optical system satisfies: -0.4≤F5 / F≤-0.2, where F5 is the effective focal length of the fifth lens.

10. The optical system according to claim 1, wherein, The optical system satisfies: 0.6≤F6 / F≤0.9, where F6 is the effective focal length of the sixth lens.

11. The optical system according to claim 1, wherein, The optical system satisfies: 0.1≤F7 / F≤0.3, where F7 is the effective focal length of the seventh lens.

12. The optical system according to claim 1, wherein, The optical system satisfies: -0.3≤F8 / F≤-0.1, where F8 is the effective focal length of the eighth lens.

13. The optical system according to claim 1, wherein, The optical system satisfies: -1.0≤F9 / F≤-0.5, where F9 is the effective focal length of the ninth lens.

14. The optical system according to claim 1, wherein, The seventh lens and the eighth lens are cemented together to form a cemented lens; The optical system satisfies: 0.6≤F78 / F≤1.1, where F78 is the combined focal length of the seventh lens and the eighth lens.

15. The optical system according to claim 1, wherein, The optical system satisfies: 0.9≤FG1 / F≤1.1, where FG1 is the combined focal length of the first lens to the sixth lens.

16. The optical system according to claim 1, wherein, The optical system satisfies: -8.0≤FG2 / F≤-2.5, where FG2 is the combined focal length of the seventh lens to the ninth lens.

17. The optical system according to claim 1, wherein, The optical system satisfies at least one of the following conditions: 65≤VD2≤75, 65≤VD4≤75, 90≤VD6≤100, Wherein, VD2 is the Abbe number of the second lens, VD4 is the Abbe number of the fourth lens, and VD6 is the Abbe number of the sixth lens.

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