Endoscope adaptive lens

Abstract

The utility model discloses an endoscope adaptive lens, which sequentially comprises a first lens group, a second lens group, a third lens group, a fourth lens group, a fifth lens group and a sixth lens group from an object side to an image side along an optical axis, the second lens group has negative focal power, and the second lens group is a zoom group; the third lens group has positive focal power, and the third lens group is a focusing group; wherein the number of the lenses with focal power in the first lens group is two; the number of the lenses with focal power in the second lens group is four; the number of the lenses with focal power in the third lens group is nine; the second lens group moves between the object side and the image side along the optical axis so as to realize continuous zooming between a wide-angle end and a long-focus end; and the third lens group moves between the object side and the image side along the optical axis so as to realize the compensation of the image surface position change in the zooming process.

Description

Technical Field

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

[0002] Endoscope adapter lenses, also known as bayonet lenses, are divided into fixed focal length and variable focal length. The zoom endoscope bayonet lens mainly includes an optical imaging lens group and a mechanical zoom module. Its main function is to connect the endoscope main mirror with the back-end display system, transmit the light beam collected by the main mirror to the back-end photosensitive chip, and display it on the display for medical staff to observe.

[0003] With the rapid development of endoscopes, the industry has higher and higher requirements for the performance of endoscopes. In order to obtain clear images of the lesion area to the greatest extent and improve the accuracy of diagnosis, the industry has put forward the demand for 4K (ultra-high definition) zoom endoscopes with good imaging quality.

[0004] However, the following problems still exist in the current zoom endoscope adapter lens: 1) The imaging quality of the zoom endoscope adapter lens is poor, and the resolution of the collected images is low, which cannot meet the 4K requirements; 2) The size of the zoom endoscope adapter lens is large, making it impossible to achieve a miniaturized design for the entire camera; 3) The entrance pupil position of the zoom endoscope adapter lens changes during the zoom process, and the imaging is unstable. Utility Model Content

[0005] The present application provides an endoscope adapter lens, which includes, in order from the object side to the image side along the optical axis: 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; a third lens group with positive optical power, which is a focusing group; wherein the number of lenses with optical power in the first lens group is two; the number of lenses with optical power in the second lens group is four; and the number of lenses with optical power in the third lens group is nine; 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; and the third lens group moves along the optical axis between the object side and the image side to achieve compensation for changes in image plane position during zooming.

[0006] In one embodiment, the first lens group includes, in order from the object side to the image side along the optical axis: a first lens having positive refractive power; and a second lens having 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 concave, and the image-side surface is convex.

[0008] In one embodiment, the second lens group includes, in order from the object side to the image side along the optical axis: a third lens having negative optical power; a fourth lens having negative optical power; a fifth lens having positive optical power; and a sixth lens having negative optical 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 includes, in order from the object side to the image side along the optical axis: a seventh lens having positive focal power; an eighth lens having positive focal power; a ninth lens having negative focal power; a tenth lens having focal power; an eleventh lens having negative focal power; a twelfth lens having positive focal power; a thirteenth lens having negative focal power; a fourteenth lens having negative focal power; and a fifteenth lens having positive focal power.

[0011] In one embodiment, 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 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 surfaces; 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, wherein 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.

[0013] In one embodiment, the endoscope adapter lens satisfies: 0.3≤FG1 / FT≤0.6, wherein 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.

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

[0015] In one embodiment, the endoscope adapter lens satisfies: -0.3≤FG2 / FT≤0, wherein 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.

[0016] In one embodiment, the endoscopic 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 endoscopic adapter lens at the wide-angle end.

[0017] In one embodiment, the endoscopic 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 endoscopic adapter lens at the telephoto end.

[0018] In one embodiment, the endoscopic adapter lens satisfies: 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.

[0019] In one embodiment, the endoscopic adapter lens satisfies: 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.

[0020] In one embodiment, the endoscopic adapter lens 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 endoscopic adapter lens, and TTL is the on-axis distance from the object side of the first lens to the imaging surface of the endoscopic adapter lens.

[0021] In one embodiment, the endoscopic 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 endoscopic 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; 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 according to the embodiment of the present application includes 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 optical focal length 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 confocality, wide object distance range and unchanged entrance pupil position during magnification change. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0027] Figure 1A and Figure 1B They are schematic diagrams of the structure of the endoscope adapter lens at the wide-angle end and the telephoto end according to Example 1 of the present application;

[0028] Figure 2A and Figure 2B They are schematic diagrams of the structure of the endoscope adapter lens at the wide-angle end and the telephoto end according to Embodiment 2 of the present application;

[0029] Figure 3A and Figure 3B They are schematic diagrams of the structure of the endoscope adapter lens at the wide-angle end and the telephoto end according to Example 3 of the present application;

[0030] Figure 4A and Figure 4B They are schematic diagrams of the structure of the endoscope adapter lens at the wide-angle end and the telephoto end according to Example 4 of the present application; DETAILED DESCRIPTION

[0031] In order to better understand the present application, a more detailed description will be made of various aspects of the present application with reference to the accompanying drawings. It should be understood that these detailed descriptions are only descriptions of exemplary embodiments of the present application, and are not intended to limit the scope of the present application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

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

[0033] In the drawings, the thickness, size and shape of the lenses have been slightly exaggerated for ease of explanation. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are shown by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to the shapes of the spherical or aspherical surfaces shown in the drawings. The drawings are only examples and are not drawn 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 position of the convex surface 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 position of the concave surface 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 object is called the object side of the lens, and the surface of each lens closest to the imaging plane is called the image side of the lens.

[0035] It should also be understood that the terms "comprises", "including", "having", "includes" 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. In addition, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire listed features rather than modifying the individual elements in the list. In addition, when describing embodiments of the present application, "may" is used to mean "one or more embodiments of the present application". And, the term "exemplary" is intended to refer to an example or illustration.

[0036] Unless otherwise defined, all terms (including technical terms and scientific terms) used in this article have the same meaning as those commonly understood by ordinary technicians in the field to which this application belongs. It should also be understood that terms (such as terms defined in commonly used dictionaries) should be interpreted as having the same meaning as their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined in this article.

[0037] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

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

[0039] According to the exemplary embodiment of the present application, the endoscope adapter lens may include three lens groups with optical power, namely, 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. The three lens groups are arranged in sequence from the object side to the image side along the optical axis. The first lens group is a fixed group, and the distance relative to the imaging surface is fixed. When the object distance changes, the second lens group and the third lens group move along the optical axis. Among them, the second lens group is a zoom group, and the second lens group can move between the object side and the image side along the optical axis so that the endoscope adapter lens can achieve continuous zoom between the wide-angle end and the telephoto end. The third lens group is a compensation group, and the compensation group compensates for the defocus caused by the movement of the zoom group during the zooming process to ensure the real-time clarity of the imaging; that is, the third lens group moves along the optical axis corresponding to the movement of the second lens group to achieve the compensation effect of the change in the image plane position during the zooming process, so that the endoscope adapter lens has a better imaging position during the continuous zooming process, and the imaging quality is stable.

[0040] In an exemplary embodiment of the present application, the number of lenses with optical power in the first lens group is two, and the first lens group includes, in order 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 the exemplary embodiment of the present application, both the object-side surface and the image-side surface of the first lens are convex surfaces, and the object-side surface of the second lens is concave, and the image-side surface is convex.

[0042] In the exemplary embodiment of the present 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. In addition, the first lens and the second lens can form a doublet lens with positive focal length, and the purpose of correcting axial chromatic aberration is achieved by reasonably matching the materials of the first lens and the second lens.

[0043] In an exemplary embodiment of the present application, the number of lenses with optical power in the second lens group is four, and the second lens group includes, from the object side to the image side along the optical axis, 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 includes three negative lenses and one positive lens, wherein the fifth lens and the sixth lens are double-cemented lenses. The three negative lenses in the second lens group are conducive to increasing the light divergence speed and improving the magnification efficiency. The provision of a group of cemented lenses is conducive to balancing the position chromatic aberration of the second lens group and improving the overall resolution.

[0044] In an exemplary embodiment of the present application, 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 concave, and the image side surface is convex.

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

[0046] In an exemplary embodiment of the present application, the number of lenses with optical power in the third lens group is nine, and the third lens group includes, in order from the object side to the image side along the optical axis: 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 the exemplary embodiment of the present application, 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 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 surfaces; 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 the exemplary embodiment of the present application, the eighth lens and the ninth lens may form a doublet lens, which is beneficial for reducing the system tolerance sensitivity.

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

[0050] In the exemplary embodiment of the present application, the fourteenth lens and the fifteenth lens can form a double cemented lens, which is beneficial for reducing the system tolerance sensitivity.

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

[0052] In an exemplary embodiment, the endoscope adapter lens according to the present application further includes an aperture arranged between the first lens group and the second lens group. The aperture is conducive to converging the light entering the lens, reducing the rear port diameter of the lens, and reducing the assembly sensitivity of the system. In an embodiment of the present application, the aperture can be arranged between the second lens and the third lens. However, it should be noted that the position of the aperture disclosed here is only an example and not a limitation; in alternative embodiments, the aperture can also be arranged at other positions according to actual needs.

[0053] In an exemplary embodiment, the endoscope adapter lens according to the present 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, and the protective glass plays a role in waterproofing, dustproofing, and anti-scratch protection.

[0054] In an exemplary embodiment, the endoscope adapter lens according to the present application may satisfy: 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. 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 at the wide-angle end is conducive to the smooth convergence of light into the optical system and improved resolution.

[0055] In an exemplary embodiment, the endoscope adapter lens according to the present application may satisfy: 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 is conducive to the smooth convergence of light into the optical system and improved resolution.

[0056] In an exemplary embodiment, the endoscope adapter lens according to the present application may satisfy: -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 when it is at the wide-angle end. Satisfying -0.5≤FG2 / FW≤-0.2, by reasonably controlling the focal length value of the second lens group, the imaging performance is achieved while ensuring the required zoom ratio during the zoom process.

[0057] In an exemplary embodiment, the endoscope adapter lens according to the present application may satisfy: -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. -0.3≤FG2 / FT≤0 is satisfied, and by reasonably controlling the focal length value of the second lens group, the imaging performance is achieved while ensuring the required zoom ratio during the zoom process.

[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 allocating 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 facilitating 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 allocating 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 facilitating 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 entrance pupil position 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 entrance pupil position 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 the present application can satisfy: 0.3≤BFL / TTL≤0.5, wherein 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 axial 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 the protective glass; it can meet the requirements of the C interface and the CS interface through an adapter ring; it can also shorten the overall length of the lens, making the lens compact and light as a whole, and convenient for handheld use.

[0063] In an exemplary embodiment, the endoscope adapter lens according to the present application can satisfy: -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. If -1.6≤FG2 / Z2≤-1.0 is satisfied, the second lens group is a zoom group, which can achieve the preset zoom range of the lens within a shorter axial movement distance, making the lens as a whole compact and light, and convenient for handheld use.

[0064] In an exemplary embodiment, the endoscope adapter lens according to the present application may satisfy: 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. Satisfying 5.6≤FG3 / Z3≤6.0, the third lens group is a compensation group corresponding to the second lens group, which can meet the compensation function of the zoom range within a shorter axial movement distance, ensure clear imaging, and make the lens as a whole compact and light, convenient for handheld use.

[0065] The endoscope adapter lens provided in the present application is beneficial to correcting the spherical aberration and axial chromatic aberration of the telephoto end of the first lens group by controlling the refractive index and Abbe number of the first lens and the second lens, 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 the present 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 the present 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 the present 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 the present application satisfies: 25≤vd2≤45.

[0070] The endoscope adapter lens provided in the present application helps light to pass smoothly through the optical system and reduce the system tolerance sensitivity by reasonably controlling the refractive index and Abbe number of the eighth lens and the ninth lens; it also helps to reduce the defocus amount of the infrared spectrum relative to the visible spectrum and realize 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 the present 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 the present 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 the present 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 the present application satisfies: 85≤vd8≤95.

[0075] In an exemplary embodiment, the first lens to the fifteenth lens may be a spherical lens or an aspherical lens. The present application does not specifically limit the specific number of spherical lenses and aspherical lenses. When focusing on imaging quality, the number of aspherical lenses can be increased, or even all lenses use aspherical lenses. The characteristic of an aspherical lens is that the curvature changes continuously from the center of the lens to the periphery. Unlike a spherical lens with a constant curvature from the center of the lens to the periphery, an aspherical lens has a better curvature radius characteristic, and has the advantages of improving distortion aberration and improving astigmatism aberration. After using an aspherical lens, the aberration that occurs during imaging can be eliminated as much as possible, thereby improving the imaging quality of the lens. Optionally, the object side and image side of the first lens to the fifteenth lens are spherical mirror surfaces.

[0076] The endoscope adapter lens of the present application has excellent resolution, with a resolution of more than 4K.

[0077] The endoscope adapter lens of the present application has the characteristics of small size and short total length. The distance TTL from the object side of the first lens to the imaging surface on the optical axis satisfies: TTL≤57mm, so that the endoscope adapter lens has a smaller total length, meets the miniaturization characteristics, and achieves maximum performance in the smallest possible volume.

[0078] The endoscope adapter lens of the present application can focus on a wide range of object distances, and can ensure clear focus at object distances from 0.3m to infinity throughout the entire zoom range, with good imaging effects.

[0079] The endoscope adapter lens of the present application can achieve infrared confocality, and the design ensures the imaging performance in the infrared band, and combined with the use of infrared fill light, the lens can be suitable for night scenes and endoscope fields.

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

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

[0082] The present application reasonably sets the optical focal length of each lens group as well as the optical focal length and surface shape of each lens, which is beneficial for the endoscope adapter lens to have a better ability to correct optical aberrations and chromatic aberrations when switching between the wide-angle end and the telephoto end. It is also beneficial for reducing the tolerance sensitivity of the system and improving the uniformity of the picture.

[0083] Optionally, in other alternative exemplary embodiments, the endoscope adapter lens may be further provided with a filter for correcting color deviation and / or a protective glass for protecting a photosensitive element located on the imaging surface.

[0084] The endoscope adapter lens according to the above-mentioned embodiment of the present application may adopt multiple lenses, for example, the fifteen lenses mentioned above. By reasonably allocating optical parameters such as the focal length, surface shape, center thickness of each lens and on-axis spacing between each lens, the endoscope adapter lens provided by the present application has at least one of the beneficial effects of high resolution (4K), small size (TTL≤57mm), infrared confocality, wide object distance range (object distance 0.3m to infinity) and unchanged entrance pupil position during magnification change, and can be adapted to the endoscope adapter lens.

[0085] However, those skilled in the art should understand that, without departing from the technical solution claimed in the present application, the number of lenses constituting the endoscope adapter lens can be changed to obtain the various results and advantages described in this specification. 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 necessary, the endoscope adapter lens may also include other numbers of lenses.

[0086] Specific embodiments of the endoscope adapter lens applicable to the above-mentioned embodiments will be further described below with reference to the accompanying drawings.

[0087] Example 1

[0088] The following reference Figure 1A and Figure 1B An endoscope adapter lens 100 according to Embodiment 1 of the present application is described. Figure 1Ais a schematic structural diagram of the endoscope adapter lens 100 according to Embodiment 1 of the present application when it is at the wide-angle end. Figure 1B It is a schematic structural diagram of the endoscope adapter lens 100 according to Embodiment 1 of the present 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, a positioning surface D, a front protective glass CG1, a first lens group G1 with positive focal length, an aperture STO, a second lens group G2 with negative focal length, a third lens group G3 with positive focal length, a filter CG2, a rear protective glass CG3 and an 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 surface S2 and an image side surface S3 , the filter rear CG2 has an object side surface S30 and an image side surface S31 , and the rear protective glass CG3 has an object side surface S32 and an image side surface S33 .

[0092] The first lens group G1 includes a first lens L1 and a second lens L2. The first lens L1 may have positive power, and its object side surface S4 is convex, and its image side surface S5 is convex. The second lens L2 may have negative power, and its object side surface S5 is concave, and its image side surface S6 is convex. The first lens L1 and the second lens L2 are cemented to form a 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 may have negative power, and its object side surface S8 is concave, and its image side surface S9 is concave. The fourth lens L4 may have negative power, and its object side surface S10 is concave, and its image side surface S11 is concave. The fifth lens L5 may have positive power, and its object side surface S12 is convex, and its image side surface S13 is convex. The sixth lens L6 may have negative power, and its object side surface S13 is concave, and its image side surface S14 is convex. The fifth lens L5 and the sixth lens L6 are cemented to form a doublet lens.

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

[0095] The stop STO may be disposed between the first lens group G1 and the second lens group G2 , and more specifically, the stop STO may be disposed between the second lens L2 and the third lens L3 .

[0096] Light from an object passes through each surface in sequence (i.e., passes 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 sensor chip may be provided.

[0097] Table 1 shows a basic parameter table of the endoscope adapter lens 100 of Example 1, wherein the units of the curvature radius and thickness / distance are both millimeters (mm).

[0098]

[0099]

[0100] Table 1

[0101] In Example 1 and the following embodiments, when the object distance changes, the first lens group G1 is fixed, and 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, so that the total effective focal length of the endoscope adapter lens is 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 the zooming process.

[0102] Table 2 shows the values ​​of T1, T2, and T3 in Table 1 when the endoscope adapter lens 100 is at the wide-angle end and the telephoto end, respectively. Table 2 also shows the total effective focal length F, the total optical length TTL, and the aperture value Fno of the endoscope adapter lens 100 of Example 1, wherein F and Fno change as the endoscope adapter lens 100 switches from the wide-angle end to the telephoto end or from the telephoto end to the wide-angle end, and TTL remains unchanged.

[0103] Wide-angle end Telephoto end F(mm) 15.095(FW) 33.994(FT) Fno 2.9 6.5 TTL(mm) 56.374 56.374 T1(mm) 0.264 4.219 T2(mm) 7.037 1.189 T3(mm) 2.725 4.617

[0104] Table 2

[0105] Example 2

[0106] The following reference Figure 2A and Figure 2B An endoscope adapter lens 200 according to Embodiment 2 of the present application is described. Figure 2A is a schematic structural diagram of the endoscope adapter lens 200 according to Embodiment 2 of the present application when it is at the wide-angle end. Figure 2B It is a structural schematic diagram of the endoscope adapter lens 200 according to Embodiment 2 of the present application when it is at the telephoto end.

[0107] In this embodiment and the following embodiments, for the sake of brevity, some descriptions similar to those in Embodiment 1 will be omitted.

[0108] like Figure 2A and Figure 2B As shown, the endoscope adapter lens 200 includes, from the object side to the image side, a positioning surface D, a front protective glass CG1, a first lens group G1 with positive focal length, an aperture STO, a second lens group G2 with negative focal length, a third lens group G3 with positive focal length, a filter CG2, a rear protective glass CG3 and an imaging surface IMA.

[0109] The front protective glass CG1 has an object side surface S2 and an image side surface S3 , the filter rear CG2 has an object side surface S30 and an image side surface S31 , and the rear protective glass CG3 has an object side surface S32 and an image side surface S33 .

[0110] The first lens group G1 includes a first lens L1 and a second lens L2. The first lens L1 may have positive power, and its object side surface S4 is convex, and its image side surface S5 is convex. The second lens L2 may have negative power, and its object side surface S5 is concave, and its image side surface S6 is convex. The first lens L1 and the second lens L2 are cemented to form a doublet lens.

[0111] 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 may have negative power, and its object side surface S8 is concave, and its image side surface S9 is concave. The fourth lens L4 may have negative power, and its object side surface S10 is concave, and its image side surface S11 is concave. The fifth lens L5 may have positive power, and its object side surface S12 is convex, and its image side surface S13 is convex. The sixth lens L6 may have negative power, and its object side surface S13 is concave, and its image side surface S14 is convex. The fifth lens L5 and the sixth lens L6 are cemented to form a doublet lens.

[0112] The third lens group G3 includes a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10, an eleventh lens L11, a twelfth lens L12, a thirteenth lens L13, a fourteenth lens L14, and a fifteenth lens L15. The seventh lens L7 may have positive power, and its object-side surface S15 is convex, and its image-side surface S16 is convex. The eighth lens L8 may have positive power, and its object-side surface S17 is convex, and its image-side surface S18 is convex. The ninth lens L9 may have negative power, and its object-side surface S18 is concave, and its image-side surface S19 is convex. The tenth lens L10 may have positive power, and its object-side surface S20 is concave, and its image-side surface S21 is convex. The eleventh lens L11 may have negative power, and its object-side surface S22 is convex, and its image-side surface S23 is concave. The twelfth lens L12 may have positive power, and its object-side surface S23 is convex, and its image-side surface S24 is convex. The thirteenth lens L13 may have negative power, and its object-side surface S25 is concave, and its image-side surface S26 is convex. The fourteenth lens L14 may have negative power, and its object-side surface S27 is concave, and its image-side surface S28 is convex. The fifteenth lens L15 may have positive power, and its object-side surface S28 is concave, and its image-side surface S29 is convex. The eighth lens L8 and the ninth lens L9 are cemented to form a doublet lens. The eleventh lens L11 and the twelfth lens L12 are cemented to form a doublet lens. The fourteenth lens L14 and the fifteenth lens L15 are cemented to form a doublet lens.

[0113] The stop STO may be disposed between the first lens group G1 and the second lens group G2 , and more specifically, the stop STO may be disposed between the second lens L2 and the third lens L3 .

[0114] Light from an object passes through each surface in sequence (i.e., passes 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 sensor chip may be provided.

[0115] Table 3 shows a basic parameter table of the endoscope adapter lens 200 of Example 2, wherein the units of the curvature radius and thickness / distance are both millimeters (mm).

[0116]

[0117]

[0118] Table 3

[0119] Table 4 shows the values ​​of T1, T2, and T3 in Table 3 when the endoscope adapter lens 200 is at the wide-angle end and the telephoto end, respectively. Table 4 also shows the total effective focal length F, the total optical length TTL, and the aperture value Fno of the endoscope adapter lens 200 of Example 2, wherein F and Fno change as the endoscope adapter lens 200 switches from the wide-angle end to the telephoto end or from the telephoto end to the wide-angle end, and TTL remains unchanged.

[0120] 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

[0121] Table 4

[0122] Example 3

[0123] The following reference Figure 3A and Figure 3B An endoscope adapter lens 300 according to Embodiment 3 of the present application is described. Figure 3A is a schematic structural diagram of the endoscope adapter lens 300 according to Embodiment 3 of the present application when it is at the wide-angle end. Figure 3B It is a structural schematic diagram of the endoscope adapter lens 300 according to Embodiment 3 of the present application when it is at the telephoto end.

[0124] like Figure 3A and Figure 3B As shown, the endoscope adapter lens 300 includes, from the object side to the image side, a positioning surface D, a front protective glass CG1, a first lens group G1 with positive focal length, an aperture STO, a second lens group G2 with negative focal length, a third lens group G3 with positive focal length, a filter CG2, a rear protective glass CG3 and an imaging surface IMA.

[0125] The front protective glass CG1 has an object side surface S2 and an image side surface S3 , the filter rear CG2 has an object side surface S30 and an image side surface S31 , and the rear protective glass CG3 has an object side surface S32 and an image side surface S33 .

[0126] The first lens group G1 includes a first lens L1 and a second lens L2. The first lens L1 may have positive power, and its object side surface S4 is convex, and its image side surface S5 is convex. The second lens L2 may have negative power, and its object side surface S5 is concave, and its image side surface S6 is convex. The first lens L1 and the second lens L2 are cemented to form a doublet lens.

[0127] 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 may have negative power, and its object side surface S8 is concave, and its image side surface S9 is concave. The fourth lens L4 may have negative power, and its object side surface S10 is concave, and its image side surface S11 is concave. The fifth lens L5 may have positive power, and its object side surface S12 is convex, and its image side surface S13 is convex. The sixth lens L6 may have negative power, and its object side surface S13 is concave, and its image side surface S14 is convex. The fifth lens L5 and the sixth lens L6 are cemented to form a doublet lens.

[0128] The third lens group G3 includes a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10, an eleventh lens L11, a twelfth lens L12, a thirteenth lens L13, a fourteenth lens L14, and a fifteenth lens L15. The seventh lens L7 may have positive power, and its object-side surface S15 is convex, and its image-side surface S16 is convex. The eighth lens L8 may have positive power, and its object-side surface S17 is convex, and its image-side surface S18 is convex. The ninth lens L9 may have negative power, and its object-side surface S18 is concave, and its image-side surface S19 is convex. The tenth lens L10 may have negative power, and its object-side surface S20 is convex, and its image-side surface S21 is concave. The eleventh lens L11 may have negative power, and its object-side surface S22 is convex, and its image-side surface S23 is concave. The twelfth lens L12 may have positive power, and its object-side surface S23 is convex, and its image-side surface S24 is convex. The thirteenth lens L13 may have negative power, and its object-side surface S25 is concave, and its image-side surface S26 is convex. The fourteenth lens L14 may have negative power, and its object-side surface S27 is concave, and its image-side surface S28 is concave. The fifteenth lens L15 may have positive power, and its object-side surface S28 is convex, and its image-side surface S29 is convex. The eighth lens L8 and the ninth lens L9 are cemented to form a doublet lens. The eleventh lens L11 and the twelfth lens L12 are cemented to form a doublet lens. The fourteenth lens L14 and the fifteenth lens L15 are cemented to form a doublet lens.

[0129] The stop STO may be disposed between the first lens group G1 and the second lens group G2 , and more specifically, the stop STO may be disposed between the second lens L2 and the third lens L3 .

[0130] Light from an object passes through each surface in sequence (i.e., passes 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 sensor chip may be provided.

[0131] Table 5 shows a basic parameter table of the endoscope adapter lens 300 of Example 3, wherein the units of the curvature radius and thickness / distance are both millimeters (mm).

[0132]

[0133]

[0134] Table 5

[0135] Table 6 shows the values ​​of T1, T2, and T3 in Table 5 when the endoscope adapter lens 300 is at the wide-angle end and the telephoto end, respectively. Table 6 also shows the total effective focal length F, the total optical length TTL, and the aperture value Fno of the endoscope adapter lens 300 of Example 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, and TTL remains unchanged.

[0136] 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

[0137] Table 6

[0138] Example 4

[0139] The following reference Figure 4A and Figure 4B An endoscope adapter lens 400 according to Embodiment 4 of the present application is described. Figure 4A is a structural schematic diagram of an endoscope adapter lens 400 according to Embodiment 4 of the present application when it is at a wide-angle end, Figure 4B It is a structural schematic diagram of the endoscope adapter lens 400 according to Embodiment 4 of the present application when it is at the telephoto end.

[0140] like Figure 4A and Figure 4B As shown, the endoscope adapter lens 400 includes, from the object side to the image side, a positioning surface D, a front protective glass CG1, a first lens group G1 with positive focal length, an aperture STO, a second lens group G2 with negative focal length, a third lens group G3 with positive focal length, a filter CG2, a rear protective glass CG3 and an imaging surface IMA.

[0141] The front protective glass CG1 has an object side surface S2 and an image side surface S3 , the filter rear CG2 has an object side surface S29 and an image side surface S30 , and the rear protective glass CG3 has an object side surface S31 and an image side surface S32 .

[0142] The first lens group G1 includes a first lens L1 and a second lens L2. The first lens L1 may have positive power, and its object side surface S4 is convex, and its image side surface S5 is convex. The second lens L2 may have negative power, and its object side surface S5 is concave, and its image side surface S6 is convex. The first lens L1 and the second lens L2 are cemented to form a doublet lens.

[0143] 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 may have negative power, and its object side surface S8 is concave, and its image side surface S9 is concave. The fourth lens L4 may have negative power, and its object side surface S10 is concave, and its image side surface S11 is concave. The fifth lens L5 may have positive power, and its object side surface S12 is convex, and its image side surface S13 is convex. The sixth lens L6 may have negative power, and its object side surface S13 is concave, and its image side surface S14 is convex. The fifth lens L5 and the sixth lens L6 are cemented to form a doublet lens.

[0144] The third lens group G3 includes a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10, an eleventh lens L11, a twelfth lens L12, a thirteenth lens L13, a fourteenth lens L14, and a fifteenth lens L15. The seventh lens L7 may have positive power, and its object-side surface S15 is convex, and its image-side surface S16 is convex. The eighth lens L8 may have positive power, and its object-side surface S17 is convex, and its image-side surface S18 is convex. The ninth lens L9 may have negative power, and its object-side surface S18 is concave, and its image-side surface S19 is convex. The tenth lens L10 may have positive power, and its object-side surface S20 is concave, and its image-side surface S21 is convex. The eleventh lens L11 may have negative power, and its object-side surface S22 is convex, and its image-side surface S23 is concave. The twelfth lens L12 may have positive power, its object-side surface S23 is convex, and its image-side surface S24 is convex. The thirteenth lens L13 may have negative power, its object-side surface S24 is concave, and its image-side surface S25 is convex. The fourteenth lens L14 may have negative power, its object-side surface S26 is concave, and its image-side surface S27 is convex. The fifteenth lens L15 may have positive power, its object-side surface S27 is concave, and its image-side surface S28 is convex. The eighth lens L8 and the ninth lens L9 are cemented together to form a doublet.

[0145] The eleventh lens L11, the twelfth lens L12 and the thirteenth lens L13 are cemented together to form a triplet lens.

[0146] The fourteenth lens L14 and the fifteenth lens L15 are cemented together to form a doublet lens.

[0147] The stop STO may be disposed between the first lens group G1 and the second lens group G2 , and more specifically, the stop STO may be disposed between the second lens L2 and the third lens L3 .

[0148] Light from an object passes through each surface in sequence (i.e., passes 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 sensor chip may be provided.

[0149] Table 7 shows a basic parameter table of the endoscope adapter lens 400 of Example 4, wherein the units of the curvature radius and thickness / distance are both millimeters (mm).

[0150]

[0151] Table 7

[0152] Table 8 shows the values ​​of T1, T2, and T3 in Table 7 when the endoscope adapter lens 400 is at the wide-angle end and the telephoto end, respectively. Table 8 also shows the total effective focal length F, the total optical length TTL, and the aperture value Fno of the endoscope adapter lens 400 of Example 4, wherein F and Fno change as the endoscope adapter lens 400 switches from the wide-angle end to the telephoto end or from the telephoto end to the wide-angle end, and TTL remains unchanged.

[0153] Wide-angle end Telephoto end F(mm) 12.989(FW) 29.306(FT) Fno 2.4 5.6 TTL(mm) 55.065 55.065 T1(mm) 0.278 5.336 T2(mm) 5.766 1.165 T3(mm) 4.667 4.210

[0154] Table 8

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

[0156] Conditional / Example 1 2 3 4 0.9≤FG1 / FW≤1.3 1.015 1.069 1.070 1.243 0.3≤FG1 / FT≤0.6 0.451 0.475 0.472 0.551 -0.5≤FG2 / FW≤-0.2 -0.394 -0.381 -0.393 -0.443 -0.3≤FG2 / FT≤0 -0.175 -0.169 -0.173 -0.197 0.8≤FG3 / FW≤1.2 0.989 0.918 0.962 1.056 0.2≤FG3 / FT≤0.6 0.439 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 0.320 0.354 0.354 0.357 -1.6≤FG2 / Z2≤-1.0 -1.504 -1.139 -1.250 -1.139 5.6≤FG3 / Z3≤6.0 5.780 5.782 5.785 5.722 1.4≤nd1≤1.6 1.59 1.50 1.50 1.50 60≤vd1≤85 62.7 81.6 81.6 81.6 1.75≤nd2≤1.95 1.91 1.88 1.88 1.88 25≤vd2≤45 32.9 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 1.67 1.74 1.67 1.74 25≤vd9≤40 31.1 34.6 31.1 34.6

[0157] Table 9

[0158] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with the technical features with similar functions disclosed in this application (but not limited to) by each other.

Claims

1. An endoscope adapter lens, characterized in that: Along the optical axis from the object side to the image side, they include: A first lens group having positive optical power, wherein the first lens group is a fixed group; A second lens group having negative optical power, wherein the second lens group is a zoom group; a third lens group having positive optical power, wherein the third lens group is a focusing group; in, The number of lenses having optical power in the first lens group is two; The number of lenses having optical power in the second lens group is four; The number of lenses having optical power in the third lens group is nine; 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 between the object side and the image side along the optical axis to compensate for changes in image plane position during zooming.

2. The endoscope adapter lens according to claim 1, characterized in that: The first lens group includes, in order from the object side to the image side along the optical axis: a first lens having positive refractive power, wherein both the object-side surface and the image-side surface are convex; and The second lens has negative optical power and its object side surface is concave and its image side surface is convex.

3. The endoscope adapter lens according to claim 1, characterized in that: The second lens group includes, in sequence from the object side to the image side along the optical axis: The third lens has negative optical power, and both the object side surface and the image side surface are concave; The fourth lens element has negative optical power, and both the object side surface and the image side surface are concave; a fifth lens element having positive refractive power, wherein both the object-side surface and the image-side surface are convex; and The sixth lens element has negative optical power and its object-side surface is concave and its image-side surface is convex.

4. The endoscope adapter lens according to claim 1, characterized in that: The third lens group includes, in order from the object side to the image side along the optical axis: The seventh lens has positive refractive power, and both the object side surface and the image side surface are convex; The eighth lens has positive refractive power, and both the object side surface and the image side surface are convex; The ninth lens has a negative optical power, and its object side surface is concave and its image side surface is convex; a tenth lens having optical power; The eleventh lens has a negative optical power, and its object side surface is convex and its image side surface is concave; A twelfth lens having positive refractive power, whose object-side surface and image-side surface are both convex; The thirteenth lens has a negative optical power, and its object side surface is concave and its image side surface is convex; A fourteenth lens having negative optical power, whose object side surface is concave; The fifteenth lens has positive refractive power and its image-side surface is convex.

5. The endoscope adapter lens according to any one of claims 1 to 4, characterized in that: The endoscope adapter lens satisfies any one of the following conditional expressions: 0.9≤FG1 / FW≤1.3, 0.3≤FG1 / FT≤0.6, Among them, FG1 is the effective focal length of the first lens group, FW is the total effective focal length of the endoscope adapter lens when it is at the wide-angle end, and FT is the total effective focal length of the endoscope adapter lens when it is at the telephoto end.

6. The endoscope adapter lens according to any one of claims 1 to 4, characterized in that: The endoscope adapter lens satisfies any one of the following conditional expressions: -0.5≤FG2 / FW≤-0.2, -0.3≤FG2 / FT≤0, -1.6≤FG2 / Z2≤-1.0, Among them, FG2 is the effective focal length of the second lens group, FW is the total effective focal length when the endoscope adapter lens is at the wide-angle end, FT is the total effective focal length when the endoscope adapter lens is at the telephoto end, and Z2 is the distance that the second lens group moves on the optical axis.

7. The endoscope adapter lens according to any one of claims 1 to 4, characterized in that: The endoscope adapter lens satisfies any one of the following conditional expressions: 0.8≤FG3 / FW≤1.2, 0.2≤FG3 / FT≤0.6, 5.6≤FG3 / Z3≤6.0, Among them, FG3 is the effective focal length of the third lens group, FW is the total effective focal length when the endoscope adapter lens is at the wide-angle end, FT is the total effective focal length when the endoscope adapter lens is at the telephoto end, and Z3 is the distance that the third lens group moves on the optical axis.

8. The endoscope adapter lens according to any one of claims 1 to 4, characterized in that: The endoscope adapter lens satisfies any one of the following conditional expressions: 0.5 <ENP / FW<0.8,0.2<ENP / FT<0.5, Wherein, ENP is the distance between the entrance pupil position of the endoscope adapter lens and the 2mm position on the object side of the front protective glass of the endoscope adapter lens, FW is the total effective focal length when the endoscope adapter lens is at the wide-angle end, and FT is the total effective focal length when the endoscope adapter lens is at the telephoto end.

9. The endoscope adapter lens according to claim 2, characterized in that: 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; The Abbe number vd2 of the second lens satisfies: 25≤vd2≤45.

10. The endoscope adapter lens according to claim 4, characterized in that: 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; The Abbe number vd9 of the ninth lens satisfies: 25≤vd9≤40; The endoscope adapter lens satisfies: 0.3≤BFL / TTL≤0.5, wherein 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 axial distance from the object side surface of the first lens to the imaging surface of the endoscope adapter lens.

Images