Endoscope adapter lens

Abstract

This application discloses an endoscope adapter lens, which includes, in sequence along the optical axis from the object side to the image side: a first lens group with positive optical power, which is a fixed group; a second lens group with negative optical power, which is a zoom group; and a third lens group with positive optical power, which is a focusing group; wherein, the second lens group moves along the optical axis between the object side and the image side to achieve continuous zoom between the wide-angle end and the telephoto end; and the third lens group moves along the optical axis between the object side and the image side to compensate for changes in the image plane position during zooming.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical elements, in particular, to an endoscope adapter lens. BACKGROUND

[0002] An endoscope adapter lens, also known as a bayonet lens, is divided into fixed focal length and variable focal length. A zoom endoscope bayonet lens mainly comprises an optical imaging lens group and a mechanical zoom module. Its main function is to connect an endoscope main lens with a rear-end display system, transmit the light beam collected by the main lens to a rear-end photosensitive chip, and display the light beam through a display so as to facilitate observation by medical personnel.

[0003] With the rapid development of endoscopes, the industry has increasingly high requirements for the performance of endoscopes. In order to maximize the acquisition of clear images of lesion areas and improve the accuracy of diagnosis, the industry has proposed the demand for 4K (ultra-high definition) zoom endoscopes with good imaging quality.

[0004] However, there are still the following problems in the current zoom endoscope adapter lens: 1) the imaging quality of the zoom endoscope adapter lens is poor, the resolution of the collected image is low, and the 4K requirement cannot be met; 2) the size of the zoom endoscope adapter lens is large, so that the entire camera cannot be designed to be miniaturized; 3) the entrance pupil position changes during the zooming process of the zoom endoscope adapter lens, and the imaging is unstable. SUMMARY

[0005] The present application provides an endoscope adapter lens, which comprises, in order from the object side to the image side along the optical axis: a first lens group with positive refractive power, the first lens group being a fixed group; a second lens group with negative refractive power, the second lens group being a zoom group; a third lens group with positive refractive power, the third lens group being a focusing group; wherein the second lens group moves between the object side and the image side along the optical axis to realize continuous zooming between the wide-angle end and the long-focus end; and the third lens group moves between the object side and the image side along the optical axis to realize compensation for the change in image plane position during zooming.

[0006] In one embodiment, the first lens group comprises, in order from the object side to the image side along the optical axis: a first lens with positive refractive power; and a second lens with negative refractive power.

[0007] In one embodiment, the object side surface and the image side surface of the first lens are both convex surfaces; and the object side surface of the second lens is a concave surface and the image side surface is a convex surface.

[0008] In one embodiment, the second lens group comprises, in order from the object side to the image side along the optical axis: a third lens with negative refractive power; a fourth lens with negative refractive power; a fifth lens with positive refractive power; and a sixth lens with negative refractive power.

[0009] In one embodiment, the object side surface and the image side surface of the third lens are both concave; the object side surface and the image side surface of the fourth lens are both concave; the object side surface and the image side surface of the fifth lens are both convex; and the object side surface of the sixth lens is concave and the image side surface is convex.

[0010] In one embodiment, the third lens group comprises, along the optical axis and in order from the object side to the image side: a seventh lens having positive refractive power; an eighth lens having positive refractive power; a ninth lens having negative refractive power; a tenth lens having refractive power; an eleventh lens having negative refractive power; a twelfth lens having positive refractive power; a thirteenth lens having negative refractive power; a fourteenth lens having negative refractive power; and a fifteenth lens having positive refractive power.

[0011] In one embodiment, the object side surface and the image side surface of the seventh lens are both convex; the object side surface and the image side surface of the eighth lens are both convex; the object side surface of the ninth lens is concave and the image side surface is convex; the object side surface of the eleventh lens is convex and the image side surface is concave; the object side surface and the image side surface of the twelfth lens are both convex; the object side surface of the thirteenth lens is concave and the image side surface is convex; the object side surface of the fourteenth lens is concave; and the image side surface of the fifteenth lens is convex.

[0012] In one embodiment, the endoscope adapter lens satisfies: 0.9≤FG1 / FW≤1.3, where FG1 is the effective focal length of the first lens group and FW is the total effective focal length of the endoscope adapter lens at the wide-angle end.

[0013] In one embodiment, the endoscope adapter lens satisfies: 0.3≤FG1 / FT≤0.6, where FG1 is the effective focal length of the first lens group and FT is the total effective focal length of the endoscope adapter lens at the telephoto end.

[0014] In one embodiment, the endoscope adapter lens satisfies: -0.5≤FG2 / FW≤-0.2, where FG2 is the effective focal length of the second lens group and FW is the total effective focal length of the endoscope adapter lens at the wide-angle end.

[0015] In one embodiment, the endoscope adapter lens satisfies: -0.3≤FG2 / FT≤0, where FG2 is the effective focal length of the second lens group and FT is the total effective focal length of the endoscope adapter lens at the telephoto end.

[0016] In one embodiment, the endoscope adapter lens satisfies: 0.8≤FG3 / FW≤1.2, where FG3 is the effective focal length of the third lens group and FW is the total effective focal length of the endoscope adapter lens at the wide-angle end.

[0017] In one embodiment, the endoscope adapter lens satisfies: 0.2 ≤ FG3 / FT ≤ 0.6, where FG3 is the effective focal length of the third lens group, and FT is the total effective focal length of the endoscope adapter lens when at the telephoto end.

[0018] In one embodiment, the endoscope adapter lens satisfies: 0.5 < ENP / FW < 0.8, where ENP is the distance from the entrance pupil position of the endoscope adapter lens to the 2mm position on the object side of the front protective glass of the endoscope adapter lens, and FW is the total effective focal length of the endoscope adapter lens when at the wide angle end.

[0019] In one embodiment, the endoscope adapter lens satisfies: 0.2 < ENP / FT < 0.5, where ENP is the distance from the entrance pupil position of the endoscope adapter lens to the 2mm position on the object side of the front protective glass of the endoscope adapter lens, and FT is the total effective focal length of the endoscope adapter lens when at the telephoto end.

[0020] In one embodiment, the endoscope adapter lens satisfies: 0.3 ≤ BFL / TTL ≤ 0.5, where BFL is the distance from the image side surface of the fifteenth lens to the imaging surface of the endoscope adapter lens, and TTL is the on-axis distance from the object side surface of the first lens to the imaging surface of the endoscope adapter lens.

[0021] In one embodiment, the endoscope adapter lens satisfies: -1.6 ≤ FG2 / Z2 ≤ -1.0, where FG2 is the effective focal length of the second lens group, and Z2 is the distance that the second lens group moves on the optical axis.

[0022] In one embodiment, the endoscope adapter lens satisfies: 5.6 ≤ FG3 / Z3 ≤ 6.0, where FG3 is the effective focal length of the third lens group, and Z3 is the distance that the third lens group moves on the optical axis.

[0023] In one embodiment, the refractive index nd1 of the first lens satisfies: 1.4 ≤ nd1 ≤ 1.6; the Abbe number vd1 of the first lens satisfies: 60 ≤ vd1 ≤ 85; the refractive index nd2 of the second lens satisfies: 1.75 ≤ nd2 ≤ 1.95; and the Abbe number vd2 of the second lens satisfies: 25 ≤ vd2 ≤ 45.

[0024] In one embodiment, the refractive index nd8 of the eighth lens satisfies: 1.3 ≤ nd8 ≤ 1.6; the Abbe number vd8 of the eighth lens satisfies: 85 ≤ vd8 ≤ 95; the refractive index nd9 of the ninth lens satisfies: 1.6 ≤ nd9 ≤ 1.8; and the Abbe number vd9 of the ninth lens satisfies: 25 ≤ vd9 ≤ 40.

[0025] The endoscope adapter lens provided by the embodiment of the present application comprises three lens groups, the first lens group is a fixed group, the second lens group is a zoom group, and the third lens group is a compensation group. By reasonably setting the focal power and action mode of the first lens group to the third lens group, the endoscope adapter lens provided by the present application has at least one of the beneficial effects of high resolution, small size, infrared confocal, wide working distance range, and constant entrance pupil position during zooming. BRIEF DESCRIPTION OF DRAWINGS

[0026] Other features, objects, and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments made with reference to the accompanying drawings:

[0027] Figure 1A and Figure 1B are respectively structural schematic diagrams of an endoscope adapter lens according to Embodiment 1 of the present application at wide-angle and long-focus ends;

[0028] Figure 2A and Figure 2B are respectively structural schematic diagrams of an endoscope adapter lens according to Embodiment 2 of the present application at wide-angle and long-focus ends;

[0029] Figure 3A and Figure 3B are respectively structural schematic diagrams of an endoscope adapter lens according to Embodiment 3 of the present application at wide-angle and long-focus ends;

[0030] Figure 4A and Figure 4B are respectively structural schematic diagrams of an endoscope adapter lens according to Embodiment 4 of the present application at wide-angle and long-focus ends; DETAILED DESCRIPTION

[0031] For a better understanding of the present application, various aspects of the present application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely descriptive of exemplary embodiments of the present application, and do not limit the scope of the present application in any way. Throughout the specification, like reference numerals refer to like elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0032] It should be noted that in the present specification, the expressions first, second, third, etc. are merely used to distinguish one feature from another, and do not represent any limitation on the features. Therefore, the first lens discussed below can also be referred to as the second lens or the third lens without departing from the teachings of the present application.

[0033] In the accompanying drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are illustrated by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustrative purposes only and are not strictly to scale.

[0034] 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.

[0035] It should also be understood that the terms "comprising," "including," "having," "containing," and / or "comprising," when used in this specification, indicate the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. Furthermore, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire list of features, not individual elements in the list. Additionally, when describing embodiments of this application, the word "may" is used to mean "one or more embodiments of this application." And the term "exemplary" is intended to refer to an example or illustration.

[0036] Unless otherwise specified, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms (e.g., those defined in common dictionaries) shall be interpreted as having the meaning consistent with their meaning in the context of the relevant art and shall not be interpreted in an idealized or overly formalized sense, unless expressly so specified herein.

[0037] 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.

[0038] The features, principles and other aspects of this application are described in detail below.

[0039] An endoscope adapter lens according to an exemplary embodiment of this application may include three lens groups with optical power: a first lens group with positive optical power, a second lens group with negative optical power, and a third lens group with positive optical power. These three lens groups are arranged sequentially along the optical axis from the object side to the image side. The first lens group is a fixed group, with a fixed distance relative to the imaging plane. When the object distance changes, the second and third lens groups move along the optical axis. The second lens group is a zoom group, which can move along the optical axis between the object side and the image side to enable continuous zooming between the wide-angle and telephoto ends of the endoscope adapter lens. The third lens group is a compensation group, which compensates for defocusing caused by the movement of the zoom group during zooming, ensuring real-time image clarity. That is, the third lens group moves along the optical axis in accordance with the movement of the second lens group to compensate for changes in the image plane position during zooming, ensuring that the endoscope adapter lens has a better imaging position and stable image quality during continuous zooming.

[0040] In an exemplary embodiment of this application, the number of lenses with optical power in the first lens group is two, and the first lens group includes, in sequence from the object side to the image side along the optical axis: a first lens with positive optical power and a second lens with negative optical power.

[0041] In an exemplary embodiment of this application, the object-side surface and the image-side surface of the first lens are both convex, while the object-side surface of the second lens is concave and the image-side surface is convex.

[0042] In an exemplary embodiment of this application, the first lens group includes a positive lens and a negative lens. The first lens is a positive convex-convex lens, and the second lens is a negative concave-convex lens. Furthermore, the first and second lenses can form a cemented doublet with positive optical power. By appropriately combining the materials of the first and second lenses, the purpose of correcting axial chromatic aberration can be achieved.

[0043] In an exemplary embodiment of this application, the second lens group comprises four lenses with optical power. Along the optical axis from the object side to the image side, the second lens group sequentially includes: a third lens with negative optical power, a fourth lens with negative optical power, a fifth lens with positive optical power, and a sixth lens with negative optical power. The second lens group contains three negative lenses and one positive lens, wherein the fifth and sixth lenses are cemented doublets. The inclusion of three negative lenses in the second lens group helps to increase the light divergence speed and improve zoom efficiency. The inclusion of a cemented doublet helps to balance the positional chromatic aberration of the second lens group and improve overall resolution.

[0044] In an exemplary embodiment of this application, the object-side surface and the image-side surface of the third lens are both concave; the object-side surface and the image-side surface of the fourth lens are both concave; the object-side surface and the image-side surface of the fifth lens are both convex; and the object-side surface of the sixth lens is concave and the image-side surface is convex.

[0045] In an exemplary embodiment of this application, the fifth lens and the sixth lens can form a cemented doublet lens, which is beneficial for field curvature correction and for reducing the defocus of the infrared spectrum relative to the visible spectrum, thereby realizing the infrared confocal function of the lens.

[0046] In an exemplary embodiment of this application, the number of lenses with optical power in the third lens group is nine. The third lens group includes, in sequence along the optical axis from the object side to the image side: a seventh lens with positive optical power; an eighth lens with positive optical power; a ninth lens with negative optical power; a tenth lens with optical power; an eleventh lens with negative optical power; a twelfth lens with positive optical power; a thirteenth lens with negative optical power; a fourteenth lens with negative optical power; and a fifteenth lens with positive optical power.

[0047] In an exemplary embodiment of this application, the object-side surface and the image-side surface of the seventh lens are both convex; the object-side surface and the image-side surface of the eighth lens are both convex; the object-side surface of the ninth lens is concave and the image-side surface is convex; the object-side surface of the eleventh lens is convex and the image-side surface is concave; the object-side surface and the image-side surface of the twelfth lens are both convex; the object-side surface of the thirteenth lens is concave and the image-side surface is convex; the object-side surface of the fourteenth lens is concave; and the image-side surface of the fifteenth lens is convex.

[0048] In an exemplary embodiment of this application, the eighth lens and the ninth lens can form a cemented doublet lens, which is beneficial to reduce the system tolerance sensitivity.

[0049] In an exemplary embodiment of this application, the eleventh lens and the twelfth lens can form a cemented doublet; or the eleventh lens, the twelfth lens and the thirteenth lens can form a cemented triplicate lens, which is beneficial for correcting chromatic aberration and reducing the system tolerance sensitivity.

[0050] In an exemplary embodiment of this application, the fourteenth lens and the fifteenth lens can form a cemented doublet lens, which is beneficial to reduce the system tolerance sensitivity.

[0051] The endoscope adapter lens according to this application includes at least three cemented lenses, which helps to correct chromatic aberration of the lens from the visible light band to the infrared band, achieve the requirement of confocal focus of visible light and infrared light, and ensure that the resolution requirements of visible light and infrared light can be met at the same time; it also helps to reduce tolerance sensitivity and improve production yield.

[0052] In an exemplary embodiment, the endoscope adapter lens according to this application further includes an aperture stop disposed between the first lens group and the second lens group. The aperture stop helps to concentrate the light entering the lens, reduce the rear aperture of the lens, and decrease the assembly sensitivity of the system. In embodiments of this application, the aperture stop may be disposed between the second lens and the third lens. However, it should be noted that the location of the aperture stop disclosed herein is merely an example and not a limitation; in alternative embodiments, the aperture stop may be disposed at other locations as needed.

[0053] In an exemplary embodiment, the endoscope adapter lens according to this application further includes a front protective glass disposed on the object side of the first lens and a rear protective glass disposed on the image side of the fifteenth lens, the protective glass providing waterproof, dustproof and scratch-proof protection.

[0054] In an exemplary embodiment, the endoscope adapter lens according to this application satisfies the following condition: 0.9 ≤ FG1 / FW ≤ 1.3, where FG1 is the effective focal length of the first lens group, and FW is the total effective focal length of the endoscope adapter lens when it is at the wide-angle end. Satisfying 0.9 ≤ FG1 / FW ≤ 1.3, and reasonably controlling the ratio of the focal length of the first lens group to the total effective focal length of the endoscope adapter lens when it is at the wide-angle end, facilitates the smooth convergence of light into the optical system, thereby improving resolution.

[0055] In an exemplary embodiment, the endoscope adapter lens according to this application satisfies the following condition: 0.3 ≤ FG1 / FT ≤ 0.6, where FG1 is the effective focal length of the first lens group, and FT is the total effective focal length of the endoscope adapter lens when it is at the telephoto end. Satisfying 0.3 ≤ FG1 / FT ≤ 0.6, and reasonably controlling the ratio of the focal length of the first lens group to the total effective focal length of the endoscope adapter lens when it is at the telephoto end, facilitates the smooth convergence of light into the optical system, thereby improving resolution.

[0056] In an exemplary embodiment, the endoscope adapter lens according to this application satisfies: -0.5 ≤ FG2 / FW ≤ -0.2, where FG2 is the effective focal length of the second lens group, and FW is the total effective focal length of the endoscope adapter lens at the wide-angle end. By satisfying -0.5 ≤ FG2 / FW ≤ -0.2 and reasonably controlling the focal length value of the second lens group, imaging performance is achieved while ensuring the required zoom ratio during zooming.

[0057] In an exemplary embodiment, the endoscope adapter lens according to this application satisfies: -0.3≤FG2 / FT≤0, where FG2 is the effective focal length of the second lens group, and FT is the total effective focal length of the endoscope adapter lens when it is at the telephoto end. By satisfying -0.3≤FG2 / FT≤0, the focal length value of the second lens group is reasonably controlled, achieving imaging performance while ensuring the required zoom ratio during zooming.

[0058] In an exemplary embodiment, the endoscopic adapter lens according to the present application may satisfy: 0.8 ≤ FG3 / FW ≤ 1.2, where FG3 is the effective focal length of the third lens group, and FW is the total effective focal length of the endoscopic adapter lens at the wide-angle end. Satisfying 0.8 ≤ FG3 / FW ≤ 1.2 and reasonably distributing the focal length value of the third lens group is beneficial for the third lens group to collect the outgoing light of the second lens group, enabling the light to transition smoothly, effectively reducing the generation of aberration, improving the optical imaging quality, achieving high resolution, and at the same time being beneficial for the third lens group to play the role of focusing the image plane during the lens zooming process.

[0059] In an exemplary embodiment, the endoscopic adapter lens according to the present application may satisfy 0.2 ≤ FG3 / FT ≤ 0.6, where FG3 is the effective focal length of the third lens group, and FT is the total effective focal length of the endoscopic adapter lens at the telephoto end. Satisfying 0.2 ≤ FG3 / FT ≤ 0.6 and reasonably distributing the focal length value of the third lens group is beneficial for the third lens group to collect the outgoing light of the second lens group, enabling the light to transition smoothly, effectively reducing the generation of aberration, improving the optical imaging quality, achieving high resolution, and at the same time being beneficial for the third lens group to play the role of focusing the image plane during the lens zooming process.

[0060] In an exemplary embodiment, the endoscopic adapter lens according to the present application may satisfy: 0.5 < ENP / FW < 0.8, where ENP is the distance from the entrance pupil position of the endoscopic adapter lens to the object side 2 mm position of the front protective glass of the endoscopic adapter lens, and FW is the total effective focal length of the endoscopic adapter lens at the wide-angle end. Satisfying 0.5 < ENP / FW < 0.8, by reasonably controlling the position of the entrance pupil, the light from the endoscopic objective lens can be stably received, and the changes in spherical aberration and distortion during the entire zooming process can also be reduced to obtain high imaging performance. The invariant position of the entrance pupil during the zooming process is beneficial for maintaining the stability of the image plane.

[0061] In an exemplary embodiment, the endoscopic adapter lens according to the present application may satisfy: 0.2 < ENP / FT < 0.5, where ENP is the distance from the entrance pupil position of the endoscopic adapter lens to the object side 2 mm position of the front protective glass of the endoscopic adapter lens, and FT is the total effective focal length of the endoscopic adapter lens at the telephoto end. Satisfying 0.2 < ENP / FT < 0.5, by reasonably controlling the position of the entrance pupil, the light from the endoscopic objective lens can be stably received, and the changes in spherical aberration and distortion during the entire zooming process can also be reduced to obtain high imaging performance. The invariant position of the entrance pupil during the zooming process is beneficial for maintaining the stability of the image plane.

[0062] In an exemplary embodiment, the endoscope adapter lens according to this application satisfies: 0.3≤BFL / TTL≤0.5, where BFL is the distance from the image side of the fifteenth lens to the imaging surface of the endoscope adapter lens, and TTL is the on-axis distance from the object side of the first lens to the imaging surface of the endoscope adapter lens; satisfying 0.3≤BFL / TTL≤0.5 allows the back focus of the lens to accommodate the filter and protective glass; it satisfies the requirements of both the C-interface and the CS-interface via an adapter ring; it also shortens the overall length of the lens, making the lens compact, lightweight, and convenient for handheld use.

[0063] In an exemplary embodiment, the endoscope adapter lens according to this application satisfies: -1.6≤FG2 / Z2≤-1.0, where FG2 is the effective focal length of the second lens group, and Z2 is the distance the second lens group moves along the optical axis. Satisfying -1.6≤FG2 / Z2≤-1.0 indicates that the second lens group is a zoom group, enabling it to achieve the lens's preset zoom range within a shorter axial movement distance, making the lens compact, lightweight, and convenient for handheld use.

[0064] In an exemplary embodiment, the endoscope adapter lens according to this application satisfies: 5.6 ≤ FG3 / Z3 ≤ 6.0, where FG3 is the effective focal length of the third lens group, and Z3 is the distance the third lens group moves along the optical axis. Satisfying 5.6 ≤ FG3 / Z3 ≤ 6.0, the third lens group is a compensation group corresponding to the second lens group, which can satisfy the zoom range compensation function within a shorter axial movement distance, ensuring clear imaging while making the lens compact, lightweight, and convenient for handheld use.

[0065] The endoscope adapter lens provided in this application, by controlling the refractive index and Abbe number of the first and second lenses, helps to correct the spherical aberration and axial chromatic aberration at the long focal end of the first lens group, thereby improving the imaging quality of the optical system.

[0066] In an exemplary embodiment, the refractive index nd1 of the first lens of the endoscope adapter lens according to this application satisfies: 1.4≤nd1≤1.6.

[0067] In an exemplary embodiment, the Abbe number vd1 of the first lens of the endoscope adapter lens according to this application satisfies: 60≤vd1≤85.

[0068] In an exemplary embodiment, the refractive index nd2 of the second lens of the endoscope adapter lens according to this application satisfies: 1.75≤nd2≤1.95.

[0069] In an exemplary embodiment, the Abbe number vd2 of the second lens of the endoscope adapter lens according to this application satisfies: 25≤vd2≤45.

[0070] The endoscope adapter lens provided in this application, by reasonably controlling the refractive index and Abbe number of the eighth and ninth lenses, facilitates the smooth passage of light through the optical system, reduces system tolerance sensitivity, and also helps to reduce the defocus of the infrared spectrum relative to the visible spectrum, thereby realizing the infrared confocal function of the lens.

[0071] In an exemplary embodiment, the refractive index nd8 of the eighth lens of the endoscope adapter lens according to this application satisfies: 1.3≤nd8≤1.6.

[0072] In an exemplary embodiment, the Abbe number vd8 of the eighth lens of the endoscope adapter lens according to this application satisfies: 85≤vd8≤95.

[0073] In an exemplary embodiment, the refractive index nd9 of the ninth lens of the endoscope adapter lens according to this application satisfies: 1.6≤nd9≤1.8.

[0074] In an exemplary embodiment, the Abbe number vd8 of the eighth lens of the endoscope adapter lens according to this application satisfies: 85≤vd8≤95.

[0075] In an exemplary embodiment, the first to fifteenth lenses can be spherical lenses or aspherical lenses. This application does not specifically limit the number of spherical and aspherical lenses; when image quality is paramount, the number of aspherical lenses can be increased, and even all lenses can be aspherical. Aspherical lenses are characterized by a continuously changing curvature from the lens center to the periphery. Unlike spherical lenses, which have a constant curvature from the lens center to the periphery, aspherical lenses have better radius of curvature characteristics, offering advantages in improving distortion and astigmatism. Using aspherical lenses can minimize aberrations that occur during imaging, thereby improving the lens's image quality. Optionally, the object-side and image-side surfaces of the first to fifteenth lenses are spherical mirror surfaces.

[0076] The endoscope adapter lens of this application has excellent resolution, with a resolution of 4K or higher.

[0077] The endoscope adapter lens of this application is characterized by its small size and short overall length. The distance TTL between the object side and the imaging surface of the first lens on the optical axis satisfies: TTL≤57mm, which makes the endoscope adapter lens have a small overall length, meets the miniaturization feature, and maximizes performance in the smallest possible volume.

[0078] The endoscope adapter lens of this application has a wide focusing distance range, and can ensure clear focus from 0.3m to infinity throughout the zoom range, resulting in good imaging effect.

[0079] The endoscope adapter lens of this application can achieve infrared confocal focusing, and its design ensures imaging performance in the infrared band. Combined with the use of infrared supplementary lighting, the lens can be used in nighttime scenes and the field of endoscopy.

[0080] The endoscope adapter lens of this application can adopt a glass-plastic hybrid structure, which reduces the design cost while ensuring a large magnification.

[0081] The endoscope adapter lens of this application has good individual component and assembly tolerances and good manufacturability.

[0082] This application, by reasonably setting the optical power of each lens group and the optical power and surface shape of each lens, is beneficial to the endoscope adapter lens to have a better ability to correct optical aberrations and chromatic aberrations when switching between wide-angle and telephoto ends. At the same time, it helps to reduce the tolerance sensitivity of the system and improve the uniformity of the image.

[0083] Alternatively, in other alternative exemplary embodiments, the endoscope adapter lens described above may also include a filter for correcting color deviation and / or a protective glass for protecting the photosensitive element located on the imaging surface.

[0084] The endoscope adapter lens according to the above embodiments of this application can use multiple lenses, such as the fifteen lenses mentioned above. By reasonably allocating the optical parameters such as the optical power, surface shape, center thickness of each lens, and on-axis spacing between each lens, the endoscope adapter lens provided by this application has at least one of the following beneficial effects: high resolution (4K), small size (TTL≤57mm), infrared confocal, wide range of object distances (object distance from 0.3m to infinity), and unchanged entrance pupil position during zooming. It can be adapted to endoscope adapter lenses.

[0085] However, those skilled in the art will understand that the number of lenses constituting the endoscope adapter lens can be varied to obtain the various results and advantages described herein without departing from the technical solutions claimed in this application. For example, although fifteen lenses are described as an example in the embodiment, the endoscope adapter lens is not limited to including fifteen lenses. If desired, the endoscope adapter lens may also include other numbers of lenses.

[0086] The following describes in further detail, with reference to the accompanying drawings, specific embodiments of the endoscope adapter lens applicable to the above-described embodiments.

[0087] Example 1

[0088] The following is for reference Figure 1A and Figure 1B The endoscope adapter lens 100 according to Embodiment 1 of this application is described. Figure 1AThis is a schematic diagram of the endoscope adapter lens 100 in the wide-angle end according to Embodiment 1 of this application. Figure 1B This is a schematic diagram of the endoscope adapter lens 100 in embodiment 1 of this application when it is at the telephoto end.

[0089] like Figure 1A and Figure 1B As shown, the endoscope adapter lens 100 includes, from the object side to the image side, the following components in sequence: positioning surface D, front protective glass CG1, first lens group G1 with positive optical power, aperture sTO, second lens group G2 with negative optical power, third lens group G3 with positive optical power, filter CG2, rear protective glass CG3, and imaging surface IMA.

[0090] In this embodiment and the following embodiments, the positioning surface D is located 2 mm from the object side of the front protective glass CG1 of the endoscope adapter lens.

[0091] The front protective glass CG1 has an object side S2 and an image side S3, the rear filter CG2 has an object side S31 and an image side S32, and the rear protective glass CG3 has an object side S33 and an image side S34.

[0092] The first lens group G1 includes a first lens L1 and a second lens L2. The first lens L1 may have positive optical power, with its object-side surface S4 being convex and its image-side surface S5 being convex. The second lens L2 may have negative optical power, with its object-side surface S5 being concave and its image-side surface S6 being convex. The first lens L1 and the second lens L2 are cemented together to form a cemented doublet lens.

[0093] The second lens group G2 includes a third lens L3, a fourth lens L4, a fifth lens L5, and a sixth lens L6. The third lens L3 can have negative optical power, with its object-side surface S8 being concave and its image-side surface S9 being concave. The fourth lens L4 can have negative optical power, with its object-side surface S10 being concave and its image-side surface S11 being concave. The fifth lens L5 can have positive optical power, with its object-side surface S12 being convex and its image-side surface S13 being convex. The sixth lens L6 can have negative optical power, with its object-side surface S13 being concave and its image-side surface S14 being convex. The fifth lens L5 and the sixth lens L6 are cemented together to form a cemented doublet lens.

[0094] The third lens group G3 includes the seventh lens L7, the eighth lens L8, the ninth lens L9, the tenth lens L10, the eleventh lens L11, the twelfth lens L12, the thirteenth lens L13, the fourteenth lens L14, and the fifteenth lens L15. The seventh lens L7 can have positive optical power, with its object-side surface S15 being convex and its image-side surface S16 being convex. The eighth lens L8 can have positive optical power, with its object-side surface S17 being convex and its image-side surface S18 being convex. The ninth lens L9 can have negative optical power, with its object-side surface S18 being concave and its image-side surface S19 being convex. The tenth lens L10 can have positive optical power, with its object-side surface S20 being concave and its image-side surface S21 being convex. The eleventh lens L11 can have negative optical power, with its object-side surface S22 being convex and its image-side surface S23 being concave. Lens L12, the twelfth lens, has positive optical power; its object-side surface S23 is convex, and its image-side surface S24 is convex. Lens L13, the thirteenth lens, has negative optical power; its object-side surface S25 is concave, and its image-side surface S26 is convex. Lens L14, the fourteenth lens, has negative optical power; its object-side surface S27 is concave, and its image-side surface S28 is concave. Lens L15, the fifteenth lens, has positive optical power; its object-side surface S29 is convex, and its image-side surface S30 is convex. Lens L8, the eighth lens, and lens L9, the ninth lens, are cemented together to form a cemented doublet. Lens L11, the eleventh lens, and lens L12, the twelfth lens, are cemented together to form a cemented doublet.

[0095] The aperture stop STO can be set between the first lens group G1 and the second lens group G2. More specifically, the aperture stop STO can be set between the second lens L2 and the third lens L3.

[0096] Light from the object passes through each surface in sequence (i.e., through the front protective glass CG1, the first lens L1 to the fifteenth lens, the filter CG2, and the rear protective glass CG3 in sequence) and is finally imaged on the imaging surface IMA, where an image sensing chip may be provided.

[0097] Table 1 shows the basic parameters of the endoscope adapter lens 100 of Embodiment 1, where the units for radius of curvature and thickness / distance are millimeters (mm).

[0098]

[0099] Table 1

[0100] In Embodiment 1 and the following embodiments, when the object distance changes, the first lens group G1 remains fixed, while the second lens group G2 and the third lens group G3 move along the optical axis. By changing the position of the second lens group G2 on the optical axis, the endoscope adapter lens can be switched from the wide-angle end to the telephoto end or from the telephoto end to the wide-angle end, making the total effective focal length of the endoscope adapter lens continuously variable. At the same time, by adjusting the position of the third lens group G3 on the optical axis, the image plane of the endoscope adapter lens can be clearly focused during zooming.

[0101] Table 2 shows the values ​​of T1, T2, and T3 in Table 1 when the endoscope adapter lens 100 is at the wide-angle and telephoto ends, respectively. Table 2 also shows the total effective focal length F, total optical length TTL, and aperture value Fno of the endoscope adapter lens 100 in Embodiment 1, wherein F and Fno change as the endoscope adapter lens 100 switches from the wide-angle end to the telephoto end or vice versa, while TTL remains unchanged.

[0102] Wide angle end Telephoto end F (mm) 15.100 (FW) 34.006 (FT) Fno 2.9 6.5 TTL (mm) 55.519 55.519 T1 (mm) 0.277 5.278 T2 (mm) 5.806 1.164 T3 (mm) 4.620 4.260

[0103] Table 2

[0104] Example 2

[0105] The following is for reference Figure 2A and Figure 2B Description of an endoscope adapter lens 200 according to Embodiment 2 of this application. Figure 2A This is a schematic diagram of the endoscope adapter lens 200 in the wide-angle end according to Embodiment 2 of this application. Figure 2B This is a schematic diagram of the endoscope adapter lens 200 in embodiment 2 of this application when it is at the telephoto end.

[0106] In this embodiment and the following embodiments, for the sake of brevity, the omitted parts are similar to the description in Embodiment 1.

[0107] like Figure 2A and Figure 2B As shown, the endoscope adapter lens 200 includes, from the object side to the image side, the following components in sequence: positioning surface D, front protective glass CG1, first lens group G1 with positive optical power, aperture sTO, second lens group G2 with negative optical power, third lens group G3 with positive optical power, filter CG2, rear protective glass CG3, and imaging surface IMA.

[0108] The front protective glass CG1 has an object side S2 and an image side S3, the rear filter CG2 has an object side S30 and an image side S31, and the rear protective glass CG3 has an object side S32 and an image side S33.

[0109] The first lens group G1 includes a first lens L1 and a second lens L2. The first lens L1 may have positive optical power, with its object-side surface S4 being convex and its image-side surface S5 being convex. The second lens L2 may have negative optical power, with its object-side surface S5 being concave and its image-side surface S6 being convex. The first lens L1 and the second lens L2 are cemented together to form a cemented doublet lens.

[0110] The second lens group G2 includes a third lens L3, a fourth lens L4, a fifth lens L5, and a sixth lens L6. The third lens L3 can have negative optical power, with its object-side surface S8 being concave and its image-side surface S9 being concave. The fourth lens L4 can have negative optical power, with its object-side surface S10 being concave and its image-side surface S11 being concave. The fifth lens L5 can have positive optical power, with its object-side surface S12 being convex and its image-side surface S13 being convex. The sixth lens L6 can have negative optical power, with its object-side surface S13 being concave and its image-side surface S14 being convex. The fifth lens L5 and the sixth lens L6 are cemented together to form a cemented doublet lens.

[0111] The third lens group G3 includes the seventh lens L7, the eighth lens L8, the ninth lens L9, the tenth lens L10, the eleventh lens L11, the twelfth lens L12, the thirteenth lens L13, the fourteenth lens L14, and the fifteenth lens L15. The seventh lens L7 can have positive optical power, with its object-side surface S15 being convex and its image-side surface S16 being convex. The eighth lens L8 can have positive optical power, with its object-side surface S17 being convex and its image-side surface S18 being convex. The ninth lens L9 can have negative optical power, with its object-side surface S18 being concave and its image-side surface S19 being convex. The tenth lens L10 can have positive optical power, with its object-side surface S20 being concave and its image-side surface S21 being convex. The eleventh lens L11 can have negative optical power, with its object-side surface S22 being convex and its image-side surface S23 being concave. Lens L12, the twelfth lens, has positive optical power; its object-side surface S23 is convex, and its image-side surface S24 is convex. Lens L13, the thirteenth lens, has negative optical power; its object-side surface S25 is concave, and its image-side surface S26 is convex. Lens L14, the fourteenth lens, has negative optical power; its object-side surface S27 is concave, and its image-side surface S28 is convex. Lens L15, the fifteenth lens, has positive optical power; its object-side surface S28 is concave, and its image-side surface S29 is convex. Lens L8 and lens L9 are cemented together to form a cemented doublet. Lens L11, the eleventh lens, and lens L12, the twelfth lens, are cemented together to form a cemented doublet. Lens L14 and lens L15, the fourteenth lens, and lens L15, are cemented together to form a cemented doublet.

[0112] The aperture stop STO can be set between the first lens group G1 and the second lens group G2. More specifically, the aperture stop STO can be set between the second lens L2 and the third lens L3.

[0113] Light from the object passes through each surface in sequence (i.e., through the front protective glass CG1, the first lens L1 to the fifteenth lens, the filter CG2, and the rear protective glass CG3 in sequence) and is finally imaged on the imaging surface IMA, where an image sensing chip may be provided.

[0114] Table 3 shows the basic parameters of the endoscope adapter lens 200 of Example 2, where the units for radius of curvature and thickness / distance are millimeters (mm).

[0115]

[0116]

[0117] Table 3

[0118] Table 4 shows the values ​​of T1, T2, and T3 in Table 3 when the endoscope adapter lens 200 is at the wide-angle and telephoto ends, respectively. Table 4 also shows the total effective focal length F, total optical length TTL, and aperture value Fno of the endoscope adapter lens 200 in Embodiment 2, wherein F and Fno change as the endoscope adapter lens 200 switches from the wide-angle end to the telephoto end or vice versa, while TTL remains unchanged.

[0119] Wide angle end Telephoto end F (mm) 15.105 (FW) 33.999 (FT) Fno 2.9 6.5 TTL (mm) 55.517 55.517 T1 (mm) 0.278 5.336 T2 (mm) 5.766 1.165 T3 (mm) 4.667 4.210

[0120] Table 4

[0121] Example 3

[0122] The following is for reference Figure 3A and Figure 3B The endoscope adapter lens 300 according to Embodiment 3 of this application is described. Figure 3A This is a schematic diagram of the endoscope adapter lens 300 in the wide-angle end according to Embodiment 3 of this application. Figure 3B This is a schematic diagram of the endoscope adapter lens 300 in embodiment 3 of this application when it is at the telephoto end.

[0123] like Figure 3A and Figure 3B As shown, the endoscope adapter lens 300 includes, from the object side to the image side, the following components in sequence: positioning surface D, front protective glass CG1, first lens group G1 with positive optical power, aperture sTO, second lens group G2 with negative optical power, third lens group G3 with positive optical power, filter CG2, rear protective glass CG3, and imaging surface IMA.

[0124] The front protective glass CG1 has an object side S2 and an image side S3, the rear filter CG2 has an object side S30 and an image side S31, and the rear protective glass CG3 has an object side S32 and an image side S33.

[0125] The first lens group G1 includes a first lens L1 and a second lens L2. The first lens L1 may have positive optical power, with its object-side surface S4 being convex and its image-side surface S5 being convex. The second lens L2 may have negative optical power, with its object-side surface S5 being concave and its image-side surface S6 being convex. The first lens L1 and the second lens L2 are cemented together to form a cemented doublet lens.

[0126] The second lens group G2 includes a third lens L3, a fourth lens L4, a fifth lens L5, and a sixth lens L6. The third lens L3 can have negative optical power, with its object-side surface S8 being concave and its image-side surface S9 being concave. The fourth lens L4 can have negative optical power, with its object-side surface S10 being concave and its image-side surface S11 being concave. The fifth lens L5 can have positive optical power, with its object-side surface S12 being convex and its image-side surface S13 being convex. The sixth lens L6 can have negative optical power, with its object-side surface S13 being concave and its image-side surface S14 being convex. The fifth lens L5 and the sixth lens L6 are cemented together to form a cemented doublet lens.

[0127] The third lens group G3 includes the seventh lens L7, the eighth lens L8, the ninth lens L9, the tenth lens L10, the eleventh lens L11, the twelfth lens L12, the thirteenth lens L13, the fourteenth lens L14, and the fifteenth lens L15. The seventh lens L7 can have positive optical power, with its object-side surface S15 being convex and its image-side surface S16 being convex. The eighth lens L8 can have positive optical power, with its object-side surface S17 being convex and its image-side surface S18 being convex. The ninth lens L9 can have negative optical power, with its object-side surface S18 being concave and its image-side surface S19 being convex. The tenth lens L10 can have negative optical power, with its object-side surface S20 being convex and its image-side surface S21 being concave. The eleventh lens L11 can have negative optical power, with its object-side surface S22 being convex and its image-side surface S23 being concave. Lens L12, the twelfth lens, has positive optical power; its object-side surface S23 is convex, and its image-side surface S24 is convex. Lens L13, the thirteenth lens, has negative optical power; its object-side surface S25 is concave, and its image-side surface S26 is convex. Lens L14, the fourteenth lens, has negative optical power; its object-side surface S27 is concave, and its image-side surface S28 is concave. Lens L15, the fifteenth lens, has positive optical power; its object-side surface S28 is convex, and its image-side surface S29 is convex. Lens L8 and lens L9 are cemented together to form a cemented doublet. Lens L11, the eleventh lens, and lens L12, the twelfth lens, are cemented together to form a cemented doublet. Lens L14 and lens L15, the fourteenth lens, and lens L15, are cemented together to form a cemented doublet.

[0128] The aperture stop STO can be set between the first lens group G1 and the second lens group G2. More specifically, the aperture stop STO can be set between the second lens L2 and the third lens L3.

[0129] Light from the object passes through each surface in sequence (i.e., through the front protective glass CG1, the first lens L1 to the fifteenth lens, the filter CG2, and the rear protective glass CG3 in sequence) and is finally imaged on the imaging surface IMA, where an image sensing chip may be provided.

[0130] Table 5 shows the basic parameters of the endoscope adapter lens 300 of Embodiment 3, where the units for radius of curvature and thickness / distance are millimeters (mm).

[0131]

[0132]

[0133] Table 5

[0134] Table 6 shows the values ​​of T1, T2, and T3 in Table 5 when the endoscope adapter lens 300 is at the wide-angle and telephoto ends, respectively. Table 6 also shows the total effective focal length F, total optical length TTL, and aperture value Fno of the endoscope adapter lens 300 in Embodiment 2, wherein F and Fno change as the endoscope adapter lens 300 switches from the wide-angle end to the telephoto end or from the telephoto end to the wide-angle end, while TTL remains unchanged.

[0135] Wide angle end Telephoto end F (mm) 15.01 (FW) 34.003 (FT) Fno 2.8 6.4 TTL (mm) 56.256 56.256 T1 (mm) 0.267 4.986 T2 (mm) 6.271 1.202 T3 (mm) 4.679 5.030

[0136] Table 6

[0137] Example 4

[0138] The following is for reference Figure 4A and Figure 4B The endoscope adapter lens 400 according to Embodiment 4 of this application is described. Figure 4A This is a schematic diagram of the endoscope adapter lens 400 in the wide-angle end according to Embodiment 4 of this application. Figure 4B This is a schematic diagram of the endoscope adapter lens 400 in embodiment 4 of this application when it is at the telephoto end.

[0139] like Figure 4A and Figure 4B As shown, the endoscope adapter lens 400 includes, from the object side to the image side, the following components in sequence: positioning surface D, front protective glass CG1, first lens group G1 with positive optical power, aperture sTO, second lens group G2 with negative optical power, third lens group G3 with positive optical power, filter CG2, rear protective glass CG3, and imaging surface IMA.

[0140] The front protective glass CG1 has an object side S2 and an image side S3, the rear filter CG2 has an object side S29 and an image side S30, and the rear protective glass CG3 has an object side S31 and an image side S32.

[0141] The first lens group G1 includes a first lens L1 and a second lens L2. The first lens L1 may have positive optical power, with its object-side surface S4 being convex and its image-side surface S5 being convex. The second lens L2 may have negative optical power, with its object-side surface S5 being concave and its image-side surface S6 being convex. The first lens L1 and the second lens L2 are cemented together to form a cemented doublet lens.

[0142] The second lens group G2 includes a third lens L3, a fourth lens L4, a fifth lens L5, and a sixth lens L6. The third lens L3 can have negative optical power, with its object-side surface S8 being concave and its image-side surface S9 being concave. The fourth lens L4 can have negative optical power, with its object-side surface S10 being concave and its image-side surface S11 being concave. The fifth lens L5 can have positive optical power, with its object-side surface S12 being convex and its image-side surface S13 being convex. The sixth lens L6 can have negative optical power, with its object-side surface S13 being concave and its image-side surface S14 being convex. The fifth lens L5 and the sixth lens L6 are cemented together to form a cemented doublet lens.

[0143] The third lens group G3 includes the seventh lens L7, the eighth lens L8, the ninth lens L9, the tenth lens L10, the eleventh lens L11, the twelfth lens L12, the thirteenth lens L13, the fourteenth lens L14, and the fifteenth lens L15. The seventh lens L7 can have positive optical power, with its object-side surface S15 being convex and its image-side surface S16 being convex. The eighth lens L8 can have positive optical power, with its object-side surface S17 being convex and its image-side surface S18 being convex. The ninth lens L9 can have negative optical power, with its object-side surface S18 being concave and its image-side surface S19 being convex. The tenth lens L10 can have positive optical power, with its object-side surface S20 being concave and its image-side surface S21 being convex. The eleventh lens L11 can have negative optical power, with its object-side surface S22 being convex and its image-side surface S23 being concave. The twelfth lens L12 has positive optical power, with its object-side surface S23 being convex and its image-side surface S24 being convex. The thirteenth lens L13 has negative optical power, with its object-side surface S24 being concave and its image-side surface S25 being convex. The fourteenth lens L14 has negative optical power, with its object-side surface S26 being concave and its image-side surface S27 being convex. The fifteenth lens L15 has positive optical power, with its object-side surface S27 being concave and its image-side surface S28 being convex. The eighth lens L8 and the ninth lens L9 are cemented together to form a cemented doublet lens.

[0144] The eleventh lens L11, the twelfth lens L12, and the thirteenth lens L13 are cemented together to form a cemented triplet lens.

[0145] The fourteenth lens L14 and the fifteenth lens L15 are cemented together to form a cemented doublet lens.

[0146] The aperture stop STO can be set between the first lens group G1 and the second lens group G2. More specifically, the aperture stop STO can be set between the second lens L2 and the third lens L3.

[0147] Light from the object passes through each surface in sequence (i.e., through the front protective glass CG1, the first lens L1 to the fifteenth lens, the filter CG2, and the rear protective glass CG3 in sequence) and is finally imaged on the imaging surface IMA, where an image sensing chip may be provided.

[0148] Table 7 shows the basic parameters of the endoscope adapter lens 400 of Example 4, where the units for radius of curvature and thickness / distance are millimeters (mm).

[0149]

[0150] Table 7

[0151] Table 8 shows the values ​​of T1, T2, and T3 in Table 7 when the endoscope adapter lens 400 is at the wide-angle and telephoto ends, respectively. Table 8 also shows the total effective focal length F, total optical length TTL, and aperture value Fno of the endoscope adapter lens 400 in Embodiment 4, wherein F and Fno change as the endoscope adapter lens 400 switches from the wide-angle end to the telephoto end or vice versa, while TTL remains constant.

[0152]

[0153]

[0154] Table 8

[0155] In summary, Examples 1 to 4 satisfy the relationships shown in Table 9.

[0156] Conditional / Example 1 2 3 4 0.9 ≤ FG1 / FW ≤ 1.3 1.066 1.069 1.070 1.243 0.3 ≤ FG1 / FT ≤ 0.6 0.473 0.475 0.472 0.551 -0.5 ≤ FG2 / FW ≤ -0.2 -0.381 -0.381 -0.393 -0.443 -0.3 ≤ FG2 / FT ≤ 0 -0.169 -0.169 -0.173 -0.197 0.8 ≤ FG3 / FW ≤ 1.2 0.914 0.918 0.962 1.056 0.2 ≤ FG3 / FT ≤ 0.6 0.405 0.408 0.425 0.468 0.5 < ENP / FW < 0.8 0.670 0.670 0.674 0.779 0.2 < ENP / FT < 0.5 0.298 0.298 0.298 0.345 0.3 ≤ BFL / TTL ≤ 0.5 0.353 0.354 0.354 0.357 -1.6 ≤ FG2 / Z2 ≤ -1.0 -1.151 -1.139 -1.250 -1.139 5.6 ≤ FG3 / Z3 ≤ 6.0 5.924 5.782 5.785 5.722 1.4 ≤ nd1 ≤ 1.6 1.50 1.50 1.50 1.50 60 ≤ vd1 ≤ 85 81.6 81.6 81.6 81.6 1.75 ≤ nd2 ≤ 1.95 1.88 1.88 1.88 1.88 25 ≤ vd2 ≤ 45 40.9 40.8 41.0 40.8 1.3 ≤ nd8 ≤ 1.6 1.46 1.46 1.46 1.46 85 ≤ vd8 ≤ 95 90.2 90.2 90.2 90.2 1.6 ≤ nd9 ≤ 1.8 1.73 1.74 1.67 1.74 25 ≤ vd9 ≤ 40 35.5 34.6 31.1 34.6

[0157] Table 9

[0158] 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 endoscope adapter lens, characterized by, sequentially includes, along the optical axis from the object side to the image side: a first lens group with positive refractive power, the first lens group being a fixed group; a second lens group with negative refractive power, the second lens group being a zoom group; a third lens group with positive refractive power, the third lens group being a focus group; wherein, the second lens group moves along the optical axis between the object side and the image side to achieve continuous zooming between a wide angle end and a telephoto end; the third lens group moves along the optical axis between the object side and the image side to achieve compensation of image plane position change during zooming; the number of lens groups with refractive power in the endoscope adapter lens is three; the number of lenses with refractive power in the endoscope adapter lens is fifteen; the first lens group sequentially includes, along the optical axis from the object side to the image side: a first lens with positive refractive power; and a second lens with negative refractive power; the second lens group sequentially includes, along the optical axis from the object side to the image side: a third lens with negative refractive power; a fourth lens with negative refractive power; a fifth lens with positive refractive power; and a sixth lens with negative refractive power; the third lens group sequentially includes, along the optical axis from the object side to the image side: a seventh lens with positive refractive power; an eighth lens with positive refractive power; a ninth lens with negative refractive power; a tenth lens with refractive power; an eleventh lens with negative refractive power; a twelfth lens with positive refractive power; a thirteenth lens with negative refractive power; a fourteenth lens with negative refractive power; and a fifteenth lens with positive refractive power; the endoscope adapter lens satisfies: -1.6≤FG2 / Z2≤-1.0, where FG2 is the effective focal length of the second lens group, and Z2 is the distance that the second lens group moves on the optical axis.

2. The endoscope adapter lens according to claim 1, wherein the object side surface and the image side surface of the first lens are both convex surfaces; and the object side surface of the second lens is a concave surface, and the image side surface is a convex surface.

3. The endoscope adapter lens according to claim 1, wherein the object side surface and the image side surface of the third lens are both concave surfaces; the object side surface and the image side surface of the fourth lens are both concave surfaces; the object side surface and the image side surface of the fifth lens are both convex surfaces; and the object side surface of the sixth lens is a concave surface, and the image side surface is a convex surface.

4. The endoscope adapter lens according to claim 1, wherein the object side surface and the image side surface of the seventh lens are both convex surfaces; the object side surface and the image side surface of the eighth lens are both convex surfaces; the object side surface of the ninth lens is a concave surface, and the image side surface is a convex surface; the object side surface of the eleventh lens is a convex surface, and the image side surface is a concave surface; the object side surface and the image side surface of the twelfth lens are both convex surfaces; the object side surface of the thirteenth lens is a concave surface, and the image side surface is a convex surface; the object side surface of the fourteenth lens is a concave surface; the image side surface of the fifteenth lens is a convex surface.

5. The endoscope adapter lens according to any one of claims 1 to 4, wherein The endoscope adapter lens satisfies: 0.9≤FG1 / FW≤1.3, where FG1 is the effective focal length of the first lens group, and FW is the total effective focal length of the endoscope adapter lens at the wide-angle end.

6. The endoscope adapter lens according to any one of claims 1 to 4, wherein The endoscope adapter lens satisfies: 0.3≤FG1 / FT≤0.6, where FG1 is the effective focal length of the first lens group, and FT is the total effective focal length of the endoscope adapter lens at the telephoto end.

7. The endoscope adapter lens according to any one of claims 1 to 4, wherein The endoscope adapter lens satisfies: -0.5≤FG2 / FW≤-0.2, where FG2 is the effective focal length of the second lens group, and FW is the total effective focal length of the endoscope adapter lens at the wide-angle end.

8. The endoscope adapter lens according to any one of claims 1 to 4, wherein The endoscope adapter lens satisfies: -0.3≤FG2 / FT≤0, where FG2 is the effective focal length of the second lens group, and FT is the total effective focal length of the endoscope adapter lens at the telephoto end.

9. The endoscope adapter lens according to any one of claims 1 to 4, wherein The endoscope adapter lens satisfies: 0.8≤FG3 / FW≤1.2, where FG3 is the effective focal length of the third lens group, and FW is the total effective focal length of the endoscope adapter lens at the wide-angle end.

10. The endoscope adapter lens according to any one of claims 1 to 4, wherein The endoscope adapter lens satisfies: 0.2≤FG3 / FT≤0.6, where FG3 is the effective focal length of the third lens group, and FT is the total effective focal length of the endoscope adapter lens at the telephoto end.

11. The endoscope adapter lens according to any one of claims 1 to 4, wherein The endoscope adapter lens satisfies: 0.5<ENP / FW<0.8, where ENP is the distance from the entrance pupil position of the endoscope adapter lens to the position 2 mm on the object side of the front protective glass of the endoscope adapter lens, and FW is the total effective focal length of the endoscope adapter lens at the wide-angle end.

12. The endoscope adapter lens according to any one of claims 1 to 4, wherein The endoscope adapter lens satisfies: 0.2<ENP / FT<0.5, where ENP is the distance from the entrance pupil position of the endoscope adapter lens to the position 2 mm on the object side of the front protective glass of the endoscope adapter lens, and FT is the total effective focal length of the endoscope adapter lens at the telephoto end.

13. The endoscope adapter lens according to claim 1, wherein The endoscope adapter lens satisfies: 0.3≤BFL / TTL≤0.5, where BFL is the distance from the image side surface of the fifteenth lens to the imaging surface of the endoscope adapter lens, and TTL is the on-axis distance from the object side surface of the first lens to the imaging surface of the endoscope adapter lens.

14. The endoscope adapter lens according to any one of claims 1 to 4, wherein the endoscope adapter lens satisfies 5.6 ≤ FG3 / Z3 ≤ 6.0, where FG3 is an effective focal length of the third lens group, and Z3 is a distance of movement of the third lens group on the optical axis.

15. The endoscope adapter lens according to claim 1, wherein a refractive index nd1 of the first lens satisfies 1.4 ≤ nd1 ≤ 1.6; an Abbe number vd1 of the first lens satisfies 60 ≤ vd1 ≤ 85; a refractive index nd2 of the second lens satisfies 1.75 ≤ nd2 ≤ 1.95; an Abbe number vd2 of the second lens satisfies 25 ≤ vd2 ≤ 45.

16. The endoscope adapter lens according to claim 1, wherein a refractive index nd8 of the eighth lens satisfies 1.3 ≤ nd8 ≤ 1.6; an Abbe number vd8 of the eighth lens satisfies 85 ≤ vd8 ≤ 95; a refractive index nd9 of the ninth lens satisfies 1.6 ≤ nd9 ≤ 1.8; an Abbe number vd9 of the ninth lens satisfies 25 ≤ vd9 ≤ 40.

17. The endoscope adapter lens of claim 1, wherein, the endoscope adapter lens satisfies at least one of: 1.066 ≤ FG1 / FW ≤ 1.243, 0.472 ≤ FG1 / FT ≤ 0.551, -0.443 ≤ FG2 / FW ≤ -0.381, -0.197 ≤ FG2 / FT ≤ -0.169, 0.914 ≤ FG3 / FW ≤ 1.056, 0.405 ≤ FG3 / FT ≤ 0.468, 0.670 ≤ ENP / FW ≤ 0.779, 0.298 ≤ ENP / FT ≤ 0.345, 0.353 ≤ BFL / TTL ≤ 0.357, -1.250 ≤ FG2 / Z2 ≤ -1.139, 5.722 ≤ FG3 / Z3 ≤ 5.924, 40.8 ≤ vd2 ≤ 41.0, 1.67 ≤ nd9 ≤ 1.74, 31.1 ≤ vd9 ≤ 35.5, where FG1 is an effective focal length of the first lens group, FW is a total effective focal length of the endoscope adapter lens at a wide angle end, FT is a total effective focal length of the endoscope adapter lens at a telephoto end, FG2 is an effective focal length of the second lens group, FG3 is an effective focal length of the third lens group, ENP is a distance of an entrance pupil position of the endoscope adapter lens from a position of 2 mm on an object side of a front protective glass of the endoscope adapter lens, BFL is a distance of an image side surface of the fifteenth lens from an imaging surface of the endoscope adapter lens, TTL is an on-axis distance of an object side surface of the first lens from the imaging surface of the endoscope adapter lens, Z2 is a distance of movement of the second lens group on the optical axis, Z3 is a distance of movement of the third lens group on the optical axis, vd2 is an Abbe number of the second lens, nd9 is a refractive index of the ninth lens, and vd9 is an Abbe number of the ninth lens.

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