Imaging lens

Abstract

This application discloses an imaging lens, comprising a first lens group, a prism, and a second lens group; wherein the first lens group has positive optical power and includes a first lens with positive optical power, a second lens with positive optical power, and a third lens with negative optical power arranged sequentially from the object side to the image side; the second lens group has positive optical power and includes a fourth lens with negative optical power, a fifth lens with positive optical power, a sixth lens with positive optical power, a seventh lens with positive optical power, and an eighth lens with negative optical power arranged sequentially from the object side to the image side; the prism is disposed between the first lens group and the second lens group; when the object distance changes, the imaging lens is focused by adjusting the position of the first lens group relative to the prism; the imaging lens has eight lenses with optical power.

Description

Technical Field

[0001] This application relates to the field of optical devices, specifically to an imaging lens. Background Technology

[0002] Surveillance lenses are a key component of machine vision systems. Due to their high precision and reliability, they are widely used in fields such as industrial automation. With the upgrading of the manufacturing industry and the development of intelligent manufacturing, the market demand for surveillance lenses is showing a steady growth trend, and higher requirements are being placed on them. For example, surveillance lenses need to have a wide range of operating distances, high illumination, and high resolution.

[0003] However, surveillance cameras often have some problems, such as low resolution, poor image clarity, and poor image quality; or, narrow object distance, which cannot meet the needs of multiple scenarios; or, low illumination, resulting in low color saturation; or, significant distortion, leading to large image deformation. Summary of the Invention

[0004] This application provides an imaging lens comprising a first lens group, a prism, and a second lens group; wherein the first lens group has positive optical power and includes a first lens with positive optical power, a second lens with positive optical power, and a third lens with negative optical power arranged sequentially from the object side to the image side; the second lens group has positive optical power and includes a fourth lens with negative optical power, a fifth lens with positive optical power, a sixth lens with positive optical power, a seventh lens with positive optical power, and an eighth lens with negative optical power arranged sequentially from the object side to the image side; the prism is disposed between the first lens group and the second lens group; when the object distance changes, the imaging lens is focused by adjusting the position of the first lens group relative to the prism; the imaging lens has eight lenses with optical power.

[0005] According to an exemplary embodiment of this application, the object-side surface of the first lens is convex. The object-side surface of the second lens is convex, and the image-side surface is also convex. The object-side surface of the third lens is concave. The object-side surface of the fourth lens is concave, and the image-side surface is also concave. The object-side surface of the fifth lens is convex, and the image-side surface is also convex. The object-side surface of the sixth lens is convex, and the image-side surface is also convex. The object-side surface of the seventh lens is convex, and the image-side surface is also convex. The object-side surface of the eighth lens is concave, and the image-side surface is also concave.

[0006] According to an exemplary embodiment of this application, the effective focal length FG1 of the first lens group and the total effective focal length F of the imaging lens satisfy: 1.75≤FG1 / F≤2.5.

[0007] According to an exemplary embodiment of this application, the effective focal length FG2 of the second lens group and the total effective focal length F of the imaging lens satisfy: 0.45≤FG2 / F≤0.85.

[0008] According to an exemplary embodiment of this application, the effective focal length FG1 of the first lens group and the effective focal length FG2 of the second lens group satisfy: 2.85≤FG1 / FG2≤3.1.

[0009] According to an exemplary embodiment of this application, the effective focal length F1 of the first lens and the effective focal length FG1 of the first lens group satisfy: 0.95≤F1 / FG1≤3.29.

[0010] According to an exemplary embodiment of this application, the effective focal length F2 of the second lens and the effective focal length FG1 of the first lens group satisfy: 0.59≤F2 / FG1≤1.31.

[0011] According to an exemplary embodiment of this application, the effective focal length F3 of the third lens and the effective focal length FG1 of the first lens group satisfy: -1.77≤F3 / FG1≤-0.95.

[0012] According to an exemplary embodiment of this application, a second lens and a third lens are cemented together to form a first cemented lens, wherein the effective focal length FB1 of the first cemented lens and the effective focal length FG1 of the first lens group satisfy: 0.86≤FB1 / FG1≤5.78.

[0013] According to an exemplary embodiment of this application, the effective focal length F4 of the fourth lens and the effective focal length FG2 of the second lens group satisfy: -0.42≤F4 / FG2≤-0.1.

[0014] According to an exemplary embodiment of this application, the effective focal length F5 of the fifth lens and the effective focal length FG2 of the second lens group satisfy: 0.6≤F5 / FG2≤0.8.

[0015] According to an exemplary embodiment of this application, the fourth lens and the fifth lens are cemented together to form a second cemented lens, and the effective focal length FB2 of the second cemented lens and the effective focal length FG2 of the second lens group satisfy: -1.62≤FB2 / FG2≤-1.2.

[0016] According to an exemplary embodiment of this application, the effective focal length F6 of the sixth lens and the effective focal length FG2 of the second lens group satisfy: 0.75≤F6 / FG2≤0.96.

[0017] According to an exemplary embodiment of this application, the effective focal length F7 of the seventh lens and the effective focal length FG2 of the second lens group satisfy: 0.66≤F7 / FG2≤0.95.

[0018] According to an exemplary embodiment of this application, the effective focal length F8 of the eighth lens and the effective focal length FG2 of the second lens group satisfy: -0.51≤F8 / FG2≤-0.33.

[0019] According to an exemplary embodiment of this application, the seventh lens and the eighth lens are cemented together to form a third cemented lens, and the effective focal length FB3 of the third cemented lens and the effective focal length FG2 of the second lens group satisfy: -2.2≤FB3 / FG2≤-1.8.

[0020] According to an exemplary embodiment of this application, the effective focal length FG1 of the first lens group and the total optical length TTL of the imaging lens satisfy: 0.1≤FG1 / TTL≤0.94.

[0021] According to an exemplary embodiment of this application, the on-axis distance T34 between the image side of the third lens and the object side of the fourth lens satisfies the following condition with respect to the total effective focal length F of the imaging lens: 1.09 ≤ T34 / F ≤ 1.55.

[0022] According to an exemplary embodiment of this application, a fourth lens and a fifth lens are cemented together to form a second cemented lens, wherein the Abbe number V(B2) of at least one lens in the second cemented lens satisfies: 55≤V(B2)≤70.

[0023] According to an exemplary embodiment of this application, the imaging lens satisfies at least one of the following conditions:

[0024] 1.78≤FG1 / F≤2.39; 0.54≤FG2 / F≤0.84; 2.94≤FG1 / FG2≤3.12; 1.17≤F1 / FG1≤3.06; 0.61≤F2 / FG1≤1.29;-1.76≤F3 / FG1≤-1.16;1.41≤FB1 / FG1≤5.23;-0.43≤F4 / FG2≤-0.29;0.62≤F5 / F G2≤0.79; -1.64≤FB2 / FG2≤-1.42; 0.73≤F6 / FG2≤0.89; 0.65≤F7 / FG2≤0.85; -0.52≤F8 / FG2 ≤-0.36; -2.19≤FB3 / FG2≤-1.89; 0.70≤FG1 / TTL≤0.96; 1.07≤T34 / F≤1.23; 61≤V(B2)≤68.7;

[0025] Wherein, FG1 is the effective focal length of the first lens group, F is the total effective focal length of the imaging lens, FG2 is the effective focal length of the second lens group, F1 is the effective focal length of the first lens, F2 is the effective focal length of the second lens, F3 is the effective focal length of the third lens, FB1 is the effective focal length of the first cemented lens formed by cementing the second and third lenses, F4 is the effective focal length of the fourth lens, F5 is the effective focal length of the fifth lens, FB2 is the effective focal length of the second cemented lens formed by cementing the fourth and fifth lenses, F6 is the effective focal length of the sixth lens, F7 is the effective focal length of the seventh lens, F8 is the effective focal length of the eighth lens, FB3 is the effective focal length of the third cemented lens formed by cementing the seventh and eighth lenses, TTL is the total optical length of the imaging lens, T34 is the axial distance from the image side of the third lens to the object side of the fourth lens, and V(B2) is the Abbe number of at least one lens in the second cemented lens formed by cementing the fourth and fifth lenses.

[0026] According to an exemplary embodiment of this application, the imaging lens further includes a first lens group replacement group; by switching the first lens group and the first lens group replacement group, focusing is achieved in the range of object distance from 300mm to infinity, wherein the first lens group achieves focusing in the range of object distance from 500mm to infinity; and the first lens group replacement group achieves focusing in the range of object distance from 300mm to 600mm.

[0027] According to an exemplary embodiment of this application, the imaging lens includes a first imaging surface and a second imaging surface; a prism splits the light emitted from the first lens group into a first beam and a second beam; the first beam is projected onto the first imaging surface via the second lens group; the imaging lens also includes a parallel second imaging lens group, and the second beam is projected onto the second imaging surface via the parallel second lens group.

[0028] According to an exemplary embodiment of this application, the imaging lens includes a first imaging surface and a second imaging surface; a prism splits the light emitted from the first lens group into a first beam and a second beam; the first beam is projected onto the first imaging surface via the second lens group; and the second beam is projected onto the second imaging surface. Attached Figure Description

[0029] 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:

[0030] Figure 1 A schematic diagram of the imaging principle of the imaging lens 100 according to this application is shown;

[0031] Figure 2 A schematic diagram of the imaging principle of the imaging lens 200 according to this application is shown;

[0032] Figure 3 A schematic diagram of the imaging lens according to Embodiment 1 of this application is shown;

[0033] Figure 4 The distortion curve of the imaging lens according to Embodiment 1 of this application in the third state is shown;

[0034] Figure 5 The relative illumination curve of the imaging lens according to Embodiment 1 of this application in the third state is shown;

[0035] Figure 6 A schematic diagram of the imaging lens according to Embodiment 2 of this application is shown;

[0036] Figure 7 The distortion curve of the imaging lens according to Embodiment 2 of this application in the third state is shown;

[0037] Figure 8 The relative illumination curve of the imaging lens in the third state according to Embodiment 2 of this application is shown;

[0038] Figure 9 A schematic diagram of the imaging lens according to Embodiment 3 of this application is shown;

[0039] Figure 10 The distortion curve of the imaging lens according to Embodiment 3 of this application in the third state is shown;

[0040] Figure 11 The relative illumination curve of the imaging lens in the third state according to Embodiment 3 of this application is shown;

[0041] Figure 12 A schematic diagram of the imaging lens according to Embodiment 4 of this application is shown;

[0042] Figure 13 The distortion curve of the imaging lens according to Embodiment 4 of this application in the third state is shown;

[0043] Figure 14 The relative illumination curve of the imaging lens in the third state according to Embodiment 4 of this application is shown. Detailed Implementation

[0044] 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.

[0045] 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.

[0046] 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.

[0047] It should also be understood that the terms "comprising," "including," "having," "containing," and / or "comprises," 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. 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. It should be noted that the longitudinal direction stated herein is perpendicular to the optical axis.

[0048] 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.

[0049] 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.

[0050] An imaging lens according to an exemplary embodiment of this application may include a first lens group, a prism, and a second lens group, with the prism disposed between the first and second lens groups. The positions of the prism and the second lens group relative to the image plane on the optical axis are fixed. When the object distance changes, the imaging lens is focused by adjusting the position of the first lens group relative to the prism.

[0051] For example, as the subject moves closer to the imaging lens, adjusting the position of the first lens group relative to the prism allows the imaging lens to switch between different states, enabling its focusing function and achieving clear focusing within a range of 300mm to infinity. For instance, when the subject is a first preset distance from the imaging lens, the imaging lens is in a first state (e.g., far-distance state); when the subject is a second preset distance, the imaging lens is in a second state (e.g., intermediate-distance state); and when the subject is a third preset distance, the imaging lens is in a third state (e.g., near-distance state).

[0052] In an exemplary embodiment, the first lens group has positive optical power and includes a first lens with positive optical power, a second lens with positive optical power, and a third lens with negative optical power arranged sequentially from the object side to the image side.

[0053] It should be understood that the number of lenses included in the first lens group being three is merely exemplary, and this application does not impose any specific limitation on the number of lenses included in the first lens group.

[0054] In an exemplary embodiment, the second lens and the third lens are cemented together to form a first cemented lens. By providing the first cemented lens, various aberrations of the imaging lens can be corrected, especially chromatic aberration, astigmatism, and field curvature, thereby improving the resolving power of the imaging lens. At the same time, it also helps to reduce the tolerance sensitivity of the imaging lens and achieve low distortion of the imaging lens.

[0055] In an exemplary embodiment, the second lens group has positive optical power and includes a fourth lens with negative optical power, a fifth lens with positive optical power, a sixth lens with positive optical power, a seventh lens with positive optical power, and an eighth lens with negative optical power, arranged sequentially from the object side to the image side. By setting the second lens group to have positive optical power, high resolution performance of the imaging lens can be achieved, distortion of the imaging lens can be reduced, and the field of view of the imaging lens can be increased.

[0056] It should be understood that the number of lenses included in the second lens group is merely exemplary, and this application does not impose any specific limitation on the number of lenses included in the second lens group.

[0057] In an exemplary embodiment, the fourth and fifth lenses are cemented together to form a second cemented lens. The seventh and eighth lenses are cemented together to form a third cemented lens. By providing the second and third cemented lenses, various aberrations of the imaging lens, especially chromatic aberration, astigmatism, and field curvature, can be corrected, improving the resolving power of the imaging lens. Simultaneously, it also helps to reduce the tolerance sensitivity of the imaging lens, achieving low distortion.

[0058] In an exemplary embodiment, the imaging lens may further include an aperture stop. The aperture stop may be located between the prism and the second lens group.

[0059] In an exemplary implementation, such as Figure 1 As shown, the imaging lens 100 according to this application may include a first imaging surface S301 and a second imaging surface S302. Light rays from the object surface OBJ pass through the first lens group S101 to the prism P. The prism P can split the light rays emitted from the first lens group S101 into a first beam LA and a second beam LB. The first beam LA is projected onto the first imaging surface S301 through the second lens group S201, and the second beam LB is projected onto the second imaging surface S302.

[0060] In an exemplary implementation, such as Figure 1 As shown, as needed, the imaging lens 100 may further include a parallel second lens group S202. Light rays from the object plane OBJ pass through the first lens group S101 to the prism P. The prism P can split the light rays emitted from the first lens group S101 into a first beam LA and a second beam LB. The first beam LA is projected onto the first imaging surface S301 through the second lens group S201, and the second beam LB is projected onto the second imaging surface S302 through the parallel second lens group S202.

[0061] In an exemplary implementation, such as Figure 2 As shown, the imaging lens 200 according to this application may further include a first lens group replacement group S102. When the object distance changes, by switching the first lens group S101 and the first lens group replacement group S102, the imaging lens 200 can achieve focusing in the range of object distance from 300mm to infinity. Specifically, the first lens group S101 focuses in the range of object distance from 500mm to infinity, and the first lens group replacement group S102 focuses in the range of object distance from 300mm to 600mm.

[0062] In an exemplary implementation, such as Figure 2 As shown, the imaging lens 200 may or may not have a parallel second lens group S202 as needed. Light rays from the object plane OBJ pass through the first lens group S101 or a replacement first lens group S102 to the prism P. The prism P can split the light rays emitted from the first lens group S101 or the replacement first lens group S102 into a first beam LA and a second beam LB. The first beam LA is projected onto the first imaging surface S301 via the second lens group S201. The second beam LB is projected onto the second imaging surface S302 via the parallel second lens group S202 or directly.

[0063] Those skilled in the art should understand that, although Figure 1 and Figure 2In this paper, the example of a prism splitting the light emitted from the first lens group S101 into two beams is used for illustration. However, this should not limit the scope of this application. In other embodiments of this application, the prism can also split the light emitted from the first lens group S101 into more beams. Fixed groups or parallel fixed groups can be set on different optical paths behind the prism as needed.

[0064] This application utilizes a prism to split the light rays emitted from the first lens group, enabling multi-beam imaging by the imaging lens. Furthermore, the prism can increase the beam length, facilitating the arrangement of components such as the second lens group and aperture.

[0065] In an exemplary embodiment, the effective focal length FG1 of the first lens group and the total effective focal length F of the imaging lens can satisfy: 1.75 ≤ FG1 / F ≤ 2.5. In one example, 1.78 ≤ FG1 / F ≤ 2.39. By reasonably configuring the ratio of the effective focal length of the first lens group to the total effective focal length of the imaging lens, the focusing function of the imaging lens can be achieved by moving the first lens group when the object distance changes, and the imaging lens can be clearly focused within the range of 300mm to infinity, allowing different beams of light from the imaging lens to be clearly focused simultaneously.

[0066] In an exemplary embodiment, the effective focal length FG2 of the second lens group and the total effective focal length F of the imaging lens can satisfy: 0.45 ≤ FG2 / F ≤ 0.85. In one example, 0.54 ≤ FG2 / F ≤ 0.84. Properly configuring the ratio of the effective focal length of the second lens group to the total effective focal length of the imaging lens is beneficial for expanding the field of view of the imaging lens, and also for achieving high resolution and low distortion. For example, the absolute value of the optical distortion DIS of the imaging lens satisfies |DIS| ≤ 2.5%.

[0067] In an exemplary embodiment, the effective focal length FG1 of the first lens group and the effective focal length FG2 of the second lens group can satisfy: 2.85 ≤ FG1 / FG2 ≤ 3.1. In one example, 2.94 ≤ FG1 / FG2 ≤ 3.12. Properly configuring the ratio of the effective focal length of the first lens group to the effective focal length of the second lens group is beneficial for the imaging lens to achieve clear focusing within the range of 300mm to infinity.

[0068] In an exemplary embodiment, the effective focal length F1 of the first lens and the effective focal length FG1 of the first lens group can satisfy: 0.95 ≤ F1 / FG1 ≤ 3.29. In one example, 1.17 ≤ F1 / FG1 ≤ 3.06. Properly configuring the ratio of the effective focal length of the first lens to the effective focal length of the first lens group can appropriately converge light rays from the object side, allowing the first lens to bear the main optical power of the first lens group, which is beneficial for correcting aberrations and achieving high resolution performance of the imaging lens.

[0069] In an exemplary embodiment, the effective focal length F2 of the second lens and the effective focal length FG1 of the first lens group can satisfy: 0.59 ≤ F2 / FG1 ≤ 1.31. In one example, 0.61 ≤ F2 / FG1 ≤ 1.29. Properly configuring the ratio of the effective focal length of the second lens to the effective focal length of the first lens group enables the second lens to have positive optical power, which is beneficial for correcting chromatic aberration and improving the image quality of the imaging lens.

[0070] In an exemplary embodiment, the effective focal length F3 of the third lens and the effective focal length FG1 of the first lens group can satisfy: -1.77 ≤ F3 / FG1 ≤ -0.95. In one example, -1.76 ≤ F3 / FG1 ≤ -1.16. Properly configuring the ratio of the effective focal length of the third lens to that of the first lens group enables the third lens to have negative optical power, which is beneficial for correcting chromatic aberration and improving the image quality of the imaging lens.

[0071] In an exemplary embodiment, the effective focal length FB1 of the first cemented lens formed by the second and third lenses and the effective focal length FG1 of the first lens group can satisfy: 0.86 ≤ FB1 / FG1 ≤ 5.78. In one example, 1.41 ≤ FB1 / FG1 ≤ 5.23. Properly configuring the ratio of the effective focal length of the first cemented lens to the effective focal length of the first lens group can correct chromatic aberration in the imaging lens and improve its resolving power.

[0072] In an exemplary embodiment, the effective focal length F4 of the fourth lens and the effective focal length FG2 of the second lens group can satisfy: -0.42 ≤ F4 / FG2 ≤ -0.1. In one example, -0.43 ≤ F4 / FG2 ≤ -0.29. Properly configuring the ratio of the effective focal length of the fourth lens to the effective focal length of the second lens group is beneficial for correcting field curvature and astigmatism of the imaging lens, improving the resolving performance of the imaging lens, and simultaneously achieving low distortion in the imaging lens.

[0073] In an exemplary embodiment, the effective focal length F5 of the fifth lens and the effective focal length FG2 of the second lens group can satisfy: 0.6 ≤ F5 / FG2 ≤ 0.8. In one example, 0.62 ≤ F5 / FG2 ≤ 0.79. Reasonably configuring the ratio of the effective focal length F5 of the fifth lens to the effective focal length of the second lens group, and using the fifth lens in conjunction with a fourth lens having negative optical power, is beneficial for correcting chromatic aberration in the imaging lens, improving the resolving performance of the imaging lens, and simultaneously achieving low distortion in the imaging lens.

[0074] In an exemplary embodiment, the effective focal length FB2 of the second cemented lens formed by the fourth and fifth lenses and the effective focal length FG2 of the second lens group can satisfy: -1.62 ≤ FB2 / FG2 ≤ -1.2. In one example, -1.64 ≤ FB2 / FG2 ≤ -1.42. Properly configuring the ratio of the effective focal length of the second cemented lens to the effective focal length of the second lens group is beneficial for correcting chromatic aberration in the imaging lens and improving its resolving performance.

[0075] In an exemplary embodiment, the effective focal length F6 of the sixth lens and the effective focal length FG2 of the second lens group can satisfy: 0.75 ≤ F6 / FG2 ≤ 0.96. In one example, 0.73 ≤ F6 / FG2 ≤ 0.89. By appropriately configuring the ratio of the effective focal length of the sixth lens to that of the second lens group, the light path can be effectively controlled, allowing the light to smoothly transition to the rear system, avoiding excessive aberration, and enabling the imaging lens to possess high image quality and high relative illumination.

[0076] In an exemplary embodiment, the effective focal length F7 of the seventh lens and the effective focal length FG2 of the second lens group can satisfy: 0.66 ≤ F7 / FG2 ≤ 0.95. In one example, 0.65 ≤ F7 / FG2 ≤ 0.85. Properly configuring the ratio of the effective focal length F7 of the seventh lens to the effective focal length of the second lens group allows the seventh lens to bear a larger optical power within the second lens group and appropriately converges the light rays emitted through the sixth lens, which is beneficial for correcting aberrations, especially astigmatism and field curvature, and improving the resolving performance of the imaging lens.

[0077] In an exemplary embodiment, the effective focal length F8 of the eighth lens and the effective focal length FG2 of the second lens group can satisfy: -0.51 ≤ F8 / FG2 ≤ -0.33. In one example, -0.52 ≤ F8 / FG2 ≤ -0.36. By reasonably configuring the ratio of the effective focal length of the eighth lens to the effective focal length of the second lens group, and by using the eighth lens in conjunction with the seventh lens having positive optical power, chromatic aberration of the imaging lens can be effectively corrected, thereby improving the resolving performance of the imaging lens.

[0078] In an exemplary embodiment, the effective focal length FB3 of the third cemented lens formed by the seventh and eighth lenses and the effective focal length FG2 of the second lens group can satisfy: -2.2 ≤ FB3 / FG2 ≤ -1.8. In one example, -2.19 ≤ FB3 / FG2 ≤ -1.89. Properly configuring the ratio of the effective focal length of the third cemented lens to the effective focal length of the second lens group is beneficial for reducing chromatic aberration in the imaging lens and improving the relative illumination of the imaging lens. For example, the relative illumination RI should satisfy RI ≥ 70%.

[0079] In an exemplary embodiment, the effective focal length FG1 of the first lens group and the total optical length TTL of the imaging lens can satisfy: 0.1 ≤ FG1 / TTL ≤ 0.94. In one example, 0.70 ≤ FG1 / TTL ≤ 0.96. Reasonably configuring the ratio of the effective focal length of the first lens group to the total optical length of the imaging lens is beneficial for controlling the total optical length of the first lens group and achieving miniaturization of the imaging lens.

[0080] In an exemplary embodiment, the axial distance T34 between the image-side surface of the third lens and the object-side surface of the fourth lens, and the total effective focal length F of the imaging lens, can satisfy: 1.09 ≤ T34 / F ≤ 1.55. In one example, 1.07 ≤ T34 / F ≤ 1.23. Properly configuring the ratio of the axial distance between the image-side surface of the third lens and the object-side surface of the fourth lens to the total effective focal length of the imaging lens helps to reserve sufficient installation space for the prism and achieve miniaturization of the imaging lens.

[0081] In an exemplary embodiment, the Abbe number V(B2) of at least one lens in the second cemented lens formed by the fourth and fifth lenses can satisfy: 55 ≤ V(B2) ≤ 70. In one example, 61 ≤ V(B2) ≤ 68.7. Properly configuring the Abbe number of at least one lens in the second cemented lens is beneficial for correcting various aberrations of the imaging lens, especially spherical aberration and chromatic aberration, thereby achieving high resolution of the imaging lens.

[0082] In an exemplary embodiment, the imaging lens may also include a filter for correcting color deviation.

[0083] In an exemplary embodiment, any one of the first to eighth lenses is a glass lens. Glass lenses can effectively suppress the shift in the back focal length of the imaging lens caused by temperature changes, improving the stability of the imaging lens. Simultaneously, glass lenses can effectively avoid image blurring caused by high or low temperature environments, ensuring that the imaging lens has high light transmittance, which is beneficial for better correction of system chromatic aberration and improving the resolving power of the imaging lens; while also achieving lower manufacturing costs.

[0084] 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 imaging lens can be changed to obtain the various results and advantages described in this specification.

[0085] The following describes in further detail, with reference to the accompanying drawings, specific embodiments of the imaging lens applicable to the above-described embodiments.

[0086] Example 1

[0087] The following is for reference Figure 3 The imaging lens according to Embodiment 1 of this application is described. Figure 3This is a schematic diagram of the imaging lens according to Embodiment 1 of this application.

[0088] like Figure 3 As shown, the imaging lens includes a first lens group, a prism P, and a second lens group. The first lens group includes a first lens L1, a second lens L2, and a third lens L3. The second lens group includes a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, and an eighth lens L8. An aperture stop STO is disposed between the prism P and the second lens group. The second lens L2 and the third lens L3 are cemented together to form a first cemented lens. The fourth lens L4 and the fifth lens L5 are cemented together to form a second cemented lens. The seventh lens L7 and the eighth lens L8 are cemented together to form a third cemented lens.

[0089] The first lens L1 has positive optical power, with its object side S1 being convex and its image side S2 being concave.

[0090] The second lens L2 has positive optical power, and its object side S3 is convex, and its image side S4 is convex.

[0091] The third lens L3 has negative optical power, and its object side is concave, while its image side S5 is also concave.

[0092] The object-side surface S6 and the image-side surface S7 of prism P are planes.

[0093] The fourth lens L4 has negative optical power, and its object side S9 is concave, and its image side S10 is concave.

[0094] The fifth lens L5 has positive optical power, and its object side is convex, while its image side S11 is convex.

[0095] The sixth lens L6 has positive optical power, and its object side S12 is convex, and its image side S13 is convex.

[0096] The seventh lens L7 has positive optical power, and its object side S14 is convex, and its image side S15 is convex.

[0097] The eighth lens L8 has negative optical power, and its object side is concave, while its image side S16 is also concave.

[0098] A filter CG can also be placed between the eighth lens L8 and the imaging plane IMA. The filter CG has an object-side surface S17 and an image-side surface S18. Light from the object passes sequentially through surfaces S1-S7 and S9-S18 and is finally imaged onto the imaging plane IMA. It should be noted that surfaces S1-S7 and S9-S18 are... Figure 3 Not shown in the image.

[0099] Table 1 shows the basic parameters of the imaging lens of Example 1, where the units for radius of curvature and thickness / distance are millimeters (mm).

[0100]

[0101]

[0102] Table 1

[0103] In this embodiment, the imaging lens has a first state, a second state, and a third state. The distance between the object surface and the imaging lens (i.e., the object distance) is D1, and the interval distance between the first lens group and the prism is D2. D1 and D2 are variables that can change with the state of the imaging lens.

[0104] Table 2 shows the values ​​of D1, D2, and the total effective focal length F of the imaging lens in different states of the imaging lens in Example 1. The units for D1, D2, and F are all millimeters (mm).

[0105] Interval distance First state Second state Third state D1 600.000 400.000 300.000 D2 5.280 6.822 8.511 F 18.904 20.031 21.430

[0106] Table 2

[0107] Figure 4 The distortion curve of the imaging lens of Example 1 in the third state is shown. Figure 5 The relative illumination curve of the imaging lens of Example 1 in its third state is shown. From... Figure 4 and Figure 5 It can be seen that the imaging lens can achieve good image quality when it is in the third state.

[0108] Example 2

[0109] The following is for reference Figure 6 The imaging lens according to Embodiment 2 of this application is described. Figure 6 This is a schematic diagram of the imaging lens according to Embodiment 2 of this application.

[0110] like Figure 6 As shown, the imaging lens includes a first lens group, a prism P, and a second lens group. The first lens group includes a first lens L1, a second lens L2, and a third lens L3. The second lens group includes a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, and an eighth lens L8. An aperture stop STO is disposed between the prism P and the second lens group. The second lens L2 and the third lens L3 are cemented together to form a first cemented lens. The fourth lens L4 and the fifth lens L5 are cemented together to form a second cemented lens. The seventh lens L7 and the eighth lens L8 are cemented together to form a third cemented lens.

[0111] The first lens L1 has positive optical power, with its object side S1 being convex and its image side S2 being concave.

[0112] The second lens L2 has positive optical power, and its object side S3 is convex, and its image side S4 is convex.

[0113] The third lens L3 has negative optical power, and its object side is concave, while its image side S5 is also concave.

[0114] The object-side surface S6 and the image-side surface S7 of prism P are planes.

[0115] The fourth lens L4 has negative optical power, and its object side S9 is concave, and its image side S10 is concave.

[0116] The fifth lens L5 has positive optical power, and its object side is convex, while its image side S11 is convex.

[0117] The sixth lens L6 has positive optical power, and its object side S12 is convex, and its image side S13 is convex.

[0118] The seventh lens L7 has positive optical power, and its object side S14 is convex, and its image side S15 is convex.

[0119] The eighth lens L8 has negative optical power, and its object side is concave, while its image side S16 is also concave.

[0120] A filter CG can also be placed between the eighth lens L8 and the imaging plane IMA. The filter CG has an object-side surface S17 and an image-side surface S18. Light from the object passes sequentially through surfaces S1-S7 and S9-S18 and is finally imaged onto the imaging plane IMA. It should be noted that surfaces S1-S7 and S9-S18 are... Figure 6 Not shown in the image.

[0121] Table 3 shows the basic parameters of the imaging lens in Example 2, where the units for radius of curvature and thickness / distance are millimeters (mm).

[0122]

[0123] Table 3

[0124] In this embodiment, the imaging lens has a first state, a second state, and a third state. The distance between the object surface and the imaging lens (i.e., the object distance) is D1, and the interval distance between the first lens group and the prism is D2. D1 and D2 are variables that can change with the state of the imaging lens.

[0125] Table 4 shows the values ​​of D1, D2, and the total effective focal length F of the imaging lens in different states of the imaging lens in Example 2. The units for D1, D2, and F are all millimeters (mm).

[0126]

[0127]

[0128] Table 4

[0129] Figure 7 The distortion curve of the imaging lens in Example 2 when it is in the third state is shown. Figure 8 The relative illumination curve of the imaging lens in Example 2 in its third state is shown. From Figure 7 and Figure 8 It can be seen that the imaging lens can achieve good image quality when it is in the third state.

[0130] Example 3

[0131] The following is for reference Figure 9 The imaging lens according to Embodiment 3 of this application is described. Figure 9 This is a schematic diagram of the imaging lens according to Embodiment 3 of this application.

[0132] like Figure 9 As shown, the imaging lens includes a first lens group, a prism P, and a second lens group. The first lens group includes a first lens L1, a second lens L2, and a third lens L3. The second lens group includes a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, and an eighth lens L8. An aperture stop STO is disposed between the prism P and the second lens group. The second lens L2 and the third lens L3 are cemented together to form a first cemented lens. The fourth lens L4 and the fifth lens L5 are cemented together to form a second cemented lens. The seventh lens L7 and the eighth lens L8 are cemented together to form a third cemented lens.

[0133] The first lens L1 has positive optical power, its object side S1 is convex, and its image side S2 is flat.

[0134] The second lens L2 has positive optical power, and its object side S3 is convex, while its image side S4 is convex.

[0135] The third lens L3 has negative optical power, its object side is concave, and its image side S5 is flat.

[0136] The object-side surface S6 and the image-side surface S7 of prism P are planes.

[0137] The fourth lens L4 has negative optical power, and its object side S9 is concave, and its image side S10 is concave.

[0138] The fifth lens L5 has positive optical power, and its object side is convex, while its image side S11 is convex.

[0139] The sixth lens L6 has positive optical power, and its object side S12 is convex, and its image side S13 is convex.

[0140] The seventh lens L7 has positive optical power, and its object side S14 is convex, and its image side S15 is convex.

[0141] The eighth lens L8 has negative optical power, and its object side is concave, while its image side S16 is also concave.

[0142] A filter CG can also be placed between the eighth lens L8 and the imaging plane IMA. The filter CG has an object-side surface S17 and an image-side surface S18. Light from the object passes sequentially through surfaces S1-S7 and S9-S18 and is finally imaged onto the imaging plane IMA. It should be noted that surfaces S1-S7 and S9-S18 are... Figure 9 Not shown in the image.

[0143] Table 5 shows the basic parameters of the imaging lens in Example 3, where the units for radius of curvature and thickness / distance are millimeters (mm).

[0144]

[0145]

[0146] Table 5

[0147] In this embodiment, the imaging lens has a first state, a second state, and a third state. The distance between the object surface and the imaging lens (i.e., the object distance) is D1, and the interval distance between the first lens group and the prism is D2. D1 and D2 are variables that can change with the state of the imaging lens.

[0148] Table 6 shows the values ​​of D1, D2, and the total effective focal length F of the imaging lens in different states of the imaging lens in Example 3. The units for D1, D2, and F are all millimeters (mm).

[0149] Interval distance First state Second state Third state D1 600.000 400.000 300.000 D2 5.266 6.816 8.478 F 18.896 20.012 21.365

[0150] Table 6

[0151] Figure 10 The distortion curve of the imaging lens in Example 3 when it is in the third state is shown. Figure 11 The relative illumination curve of the imaging lens in Example 3 when it is in the third state is shown. From... Figure 10 and Figure 11 It can be seen that the imaging lens can achieve good image quality when it is in the third state.

[0152] Example 4

[0153] The following is for reference Figure 12 The imaging lens according to Embodiment 4 of this application is described. Figure 12 This is a schematic diagram of the imaging lens according to Embodiment 4 of this application.

[0154] like Figure 12 As shown, the imaging lens includes a first lens group, a prism P, and a second lens group. The first lens group includes a first lens L1, a second lens L2, and a third lens L3. The second lens group includes a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, and an eighth lens L8. An aperture stop STO is disposed between the prism and the fourth lens L4. The second lens L2 and the third lens L3 are cemented together to form a cemented lens. The fourth lens L4 and the fifth lens L5 are cemented together to form a cemented lens. The seventh lens L7 and the eighth lens L8 are cemented together to form a cemented lens.

[0155] The first lens L1 has positive optical power, its object side S1 is convex, and its image side S2 is flat.

[0156] The second lens L2 has positive optical power, and its object side S3 is convex, and its image side S4 is convex.

[0157] The third lens L3 has negative optical power, its object side is concave, and its image side S5 is flat.

[0158] The object-side surface S6 and the image-side surface S7 of prism P are planes.

[0159] The fourth lens L4 has negative optical power, and its object side S9 is concave, and its image side S10 is concave.

[0160] The fifth lens L5 has positive optical power, and its object side is convex, while its image side S11 is convex.

[0161] The sixth lens L6 has positive optical power, and its object side S12 is convex, and its image side S13 is convex.

[0162] The seventh lens L7 has positive optical power, and its object side S14 is convex, and its image side S15 is convex.

[0163] The eighth lens L8 has negative optical power, and its object side is concave, while its image side S16 is also concave.

[0164] A filter CG can also be placed between the eighth lens L8 and the imaging plane IMA. The filter CG has an object-side surface S17 and an image-side surface S18. Light from the object passes sequentially through surfaces S1-S7 and S9-S18 and is finally imaged onto the imaging plane IMA. It should be noted that surfaces S1-S7 and S9-S18 are... Figure 12 Not shown in the image.

[0165] Table 7 shows the basic parameters of the imaging lens in Example 4, where the units for radius of curvature and thickness / distance are millimeters (mm).

[0166]

[0167] Table 7

[0168] In this embodiment, the imaging lens has a first state, a second state, and a third state. The distance between the object surface and the imaging lens (i.e., the object distance) is D1, and the interval distance between the first lens group and the prism is D2. D1 and D2 are variables that can change with the state of the imaging lens.

[0169] Table 8 shows the values ​​of D1, D2, and the total effective focal length F of the imaging lens in different states of the imaging lens in Example 4. The units for D1, D2, and F are all millimeters (mm).

[0170] Interval distance First state Second state Third state D1 Infinity 3000.000 500.000 D2 3.962 4.493 7.361 F 17.155 17.457 19.299

[0171] Table 8

[0172] Figure 13 The distortion curve of the imaging lens in Example 4 when it is in the third state is shown. Figure 14 The relative illumination curve of the imaging lens in Example 4 when it is in the third state is shown. From... Figure 13 and Figure 14 It can be seen that the imaging lens can achieve good image quality when it is in the third state.

[0173] In summary, the conditional expressions in Examples 1 to 4 satisfy the relationships shown in Table 9. Here, F in FG1 / F, FG2 / F, and T34 / F in Table 9 can, for example, represent the total effective focal length of the imaging lens when it is in the third state.

[0174] Conditional / Example 1 2 3 4 FG1 / F 1.857 2.319 1.857 2.310 FG2 / F 0.610 0.762 0.616 0.767 FG1 / FG2 3.045 3.043 3.015 3.013 F1 / FG1 1.396 2.976 1.307 2.992 F2 / FG1 0.989 0.687 1.222 0.789 F3 / FG1 -1.339 -1.236 -1.692 -1.631 FB1 / FG1 3.532 1.486 4.213 1.485 F4 / FG2 -0.361 -0.361 -0.365 -0.365 F5 / FG2 0.689 0.689 0.716 0.716 FB2 / FG2 -1.520 -1.520 -1.488 -1.488 F6 / FG2 0.803 0.803 0.824 0.824 F7 / FG2 0.748 0.748 0.718 0.718 F8 / FG2 -0.451 -0.451 -0.428 -0.428 FB3 / FG2 -1.997 -1.997 -2.116 -2.116 FG1 / TTL 0.776 0.885 0.766 0.867 T34 / F 1.146 1.165 1.142 1.160 V(B2) 61.250 61.250 68.630 68.630

[0175] Table 9

[0176] 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 imaging lens described above.

[0177] 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 imaging lens, characterized in that, It includes a first lens group, a prism, and a second lens group; wherein, The first lens group has positive optical power and includes a first lens with positive optical power, a second lens with positive optical power, and a third lens with negative optical power arranged sequentially from the object side to the image side. The second lens group has positive optical power and includes a fourth lens with negative optical power, a fifth lens with positive optical power, a sixth lens with positive optical power, a seventh lens with positive optical power, and an eighth lens with negative optical power arranged sequentially from the object side to the image side. The prism is disposed between the first lens group and the second lens group; When the object distance changes, the imaging lens is focused by adjusting the position of the first lens group relative to the prism; The imaging lens has eight lenses with optical power. The second lens and the third lens are cemented together to form a first cemented lens, and the effective focal length FB1 of the first cemented lens and the effective focal length FG1 of the first lens group satisfy: 0.86≤FB1 / FG1≤5.

78.

2. The imaging lens according to claim 1, characterized in that, The object-side surface of the first lens is convex. The object-side surface of the second lens is convex, and the image-side surface is also convex. The object-side surface of the third lens is concave. The object side of the fourth lens is concave, and the image side is also concave. The object-side surface of the fifth lens is convex, and the image-side surface is also convex. The object-side surface of the sixth lens is convex, and the image-side surface is also convex. The object-side surface of the seventh lens is convex, and the image-side surface is also convex. The object-side surface of the eighth lens is concave, and the image-side surface is also concave.

3. The imaging lens according to claim 1 or 2, characterized in that, The effective focal length FG1 of the first lens group and the total effective focal length F of the imaging lens satisfy: 1.75≤FG1 / F≤2.

5.

4. The imaging lens according to claim 1 or 2, characterized in that, The effective focal length FG2 of the second lens group and the total effective focal length F of the imaging lens satisfy: 0.45≤FG2 / F≤0.

85.

5. The imaging lens according to claim 1 or 2, characterized in that, The effective focal length FG1 of the first lens group and the effective focal length FG2 of the second lens group satisfy: 2.85≤FG1 / FG2≤3.

1.

6. The imaging lens according to claim 1 or 2, characterized in that, The effective focal length F1 of the first lens and the effective focal length FG1 of the first lens group satisfy: 0.95≤F1 / FG1≤3.

29.

7. The imaging lens according to claim 1 or 2, characterized in that, The effective focal length F2 of the second lens and the effective focal length FG1 of the first lens group satisfy: 0.59≤F2 / FG1≤1.

31.

8. The imaging lens according to claim 1 or 2, characterized in that, The effective focal length F3 of the third lens and the effective focal length FG1 of the first lens group satisfy the following condition: -1.77≤F3 / FG1≤-0.

95.

9. The imaging lens according to claim 1 or 2, characterized in that, The effective focal length F4 of the fourth lens and the effective focal length FG2 of the second lens group satisfy the following condition: -0.42≤F4 / FG2≤-0.

1.

10. The imaging lens according to claim 1 or 2, characterized in that, The imaging lens satisfies any one of the following conditions: 0.6≤F5 / FG2≤0.8; -1.62≤FB2 / FG2≤-1.2; 0.75≤F6 / FG2≤0.96; 0.66≤F7 / FG2≤0.95; -0.51≤F 8 / FG2≤-0.33; -2.2≤FB3 / FG2≤-1.8; 0.1≤FG1 / TTL≤0.94; 1.09≤T34 / F≤1.55; 55≤V(B2)≤70; Wherein, F5 is the effective focal length of the fifth lens, FG2 is the effective focal length of the second lens group, FB2 is the effective focal length of the second cemented lens formed by cementing the fourth and fifth lenses, F6 is the effective focal length of the sixth lens, F7 is the effective focal length of the seventh lens, F8 is the effective focal length of the eighth lens, FB3 is the effective focal length of the third cemented lens formed by cementing the seventh and eighth lenses, FG1 is the effective focal length of the first lens group, TTL is the total optical length of the imaging lens, T34 is the axial distance from the image side of the third lens to the object side of the fourth lens, F is the total effective focal length of the imaging lens, and V(B2) is the Abbe number of at least one lens in the second cemented lens formed by cementing the fourth and fifth lenses.

11. The imaging lens according to claim 1 or 2, characterized in that, The imaging lens satisfies any one of the following conditions: 1.78≤FG1 / F≤2.39; 0.54≤FG2 / F≤0.84; 2.94≤FG1 / FG2≤3.12; 1.17≤F1 / FG1≤3.06; 0.61≤F2 / FG1≤1.29;-1.76≤F3 / FG1≤-1.16;1.41≤FB1 / FG1≤5.23;-0.43≤F4 / FG2≤-0.29;0.62≤F5 / F G2≤0.79; -1.64≤FB2 / FG2≤-1.42; 0.73≤F6 / FG2≤0.89; 0.65≤F7 / FG2≤0.85; -0.52≤F8 / FG2 ≤-0.36; -2.19≤FB3 / FG2≤-1.89; 0.70≤FG1 / TTL≤0.96; 1.07≤T34 / F≤1.23; 61≤V(B2)≤68.7; Wherein, FG1 is the effective focal length of the first lens group, F is the total effective focal length of the imaging lens, FG2 is the effective focal length of the second lens group, F1 is the effective focal length of the first lens, F2 is the effective focal length of the second lens, F3 is the effective focal length of the third lens, FB1 is the effective focal length of the first cemented lens, F4 is the effective focal length of the fourth lens, F5 is the effective focal length of the fifth lens, FB2 is the effective focal length of the second cemented lens formed by cementing the fourth and fifth lenses, F6 is the effective focal length of the sixth lens, F7 is the effective focal length of the seventh lens, F8 is the effective focal length of the eighth lens, FB3 is the effective focal length of the third cemented lens formed by cementing the seventh and eighth lenses, TTL is the total optical length of the imaging lens, T34 is the axial distance from the image side of the third lens to the object side of the fourth lens, and V(B2) is the Abbe number of at least one lens in the second cemented lens formed by cementing the fourth and fifth lenses.

12. The imaging lens according to claim 1 or 2, characterized in that, The imaging lens also includes a first lens group replacement group; By switching between the first lens group and the first lens group replacement group, focusing is achieved in the range of object distance from 300mm to infinity, wherein the first lens group achieves focusing in the range of object distance from 500mm to infinity; and the first lens group replacement group achieves focusing in the range of object distance from 300mm to 600mm.

13. The imaging lens according to claim 1 or 2, characterized in that, The imaging lens includes a first imaging surface and a second imaging surface; The prism splits the light emitted from the first lens group into a first beam and a second beam. The first beam is projected onto the first imaging surface via the second lens group; The imaging lens also includes a second lens group in parallel, through which the second beam is projected onto the second imaging surface.

14. The imaging lens according to claim 1 or 2, characterized in that, The imaging lens includes a first imaging surface and a second imaging surface; The prism splits the light emitted from the first lens group into a first beam and a second beam. The first beam is projected onto the first imaging surface via the second lens group; The second beam is projected onto the second imaging surface.

Images