Endoscope adapter lens

Abstract

The application discloses an endoscope adapter lens, which comprises, in sequence from the object side to the image side along the optical axis, a first lens group with positive focal power, the first lens group being a focusing group; a second lens group with negative focal power, the second lens group being a zooming group; and a third lens group with positive focal power, the third lens group being a compensating group; wherein the first lens group moves between the object side and the image side along the optical axis to realize consistent conjugate image plane positions at different object distances; 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 of the change of the image plane position during zooming.

Description

Technical Field

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

[0002] Endoscope adapter lenses, also known as bayonet lenses, are used to work with endoscopes and connect to camera devices to transmit images detected by the endoscope to the camera device, making it easier for users to observe.

[0003] When using an endoscope, images at a single magnification are often insufficient to meet user needs. Therefore, a zoomable adapter is required to provide images at different magnifications for user observation.

[0004] Currently used endoscope adapter lenses generally have the following drawbacks: 1) During the zoom process, the image is blurred because the focus is adjusted first and then the compensation is adjusted. 2) When the object distance changes, the position of the conjugate image changes accordingly. In order to make the conjugate image position consistent, existing adapter lenses refocus by moving the compensation group. The movement of the compensation group changes the original magnification, and the imaging range changes accordingly.

[0005] Therefore, it is necessary to design an endoscope adapter lens with independent focusing and zooming functions, so that the image remains clear during zooming after focusing at different object distances. Summary of the Invention

[0006] This application provides an endoscope adapter lens, which comprises, along the optical axis from the object side to the image side, the following in sequence: a first lens group with positive optical power, which is a focusing 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 compensation group; wherein, the first lens group moves along the optical axis between the object side and the image side to achieve consistent conjugate image plane positions at different object distances; 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 image plane position during zooming.

[0007] In one embodiment, the first lens group sequentially includes, along the optical axis from the object side to the image side: a first lens having negative optical power; a second lens having positive optical power; and a third lens having positive optical power.

[0008] In one embodiment, the object-side and image-side surfaces of the first lens are both concave; the image-side surface of the second lens is convex; and the object-side surface of the third lens is convex.

[0009] In one embodiment, the second lens group includes, sequentially from the object side to the image side along the optical axis: a fourth lens having negative optical power; a fifth lens having positive optical power; and a sixth lens having negative optical power.

[0010] In one embodiment, the object-side and image-side surfaces of the fourth lens are both concave; the object-side surface of the fifth lens is concave and the image-side surface is convex; and the object-side surface of the sixth lens is concave.

[0011] In one embodiment, the third lens group includes, sequentially 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 positive 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.

[0012] In one embodiment, the object-side and image-side surfaces of the seventh lens are both convex; the object-side and image-side surfaces of the eighth lens are both convex; the object-side surface of the ninth lens is concave; the image-side surface of the eleventh lens is concave; the object-side and image-side surfaces 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.

[0013] In one embodiment, the optical power φ2 of the second lens group and the optical power φ3 of the third lens group satisfy: 1.45≤|φ2| / φ3≤1.60.

[0014] In one embodiment, when the object distance of the endoscope adapter lens is infinity, the first lens group is located at a first position on the optical axis; when the object distance of the endoscope adapter lens is 300mm, the first lens group is located at a second position on the optical axis. The endoscope adapter lens satisfies: 8.50≤f1 / (d inf -d near )≤11.80, where f1 is the effective focal length of the first lens group, (d inf -d near ) is the distance between the first position and the second position on the optical axis.

[0015] In one implementation, the endoscope adapter lens satisfies: 0.35 ≤ (f2 + f3) / f w ≤0.45, where f2 is the effective focal length of the second lens group, f3 is the effective focal length of the third lens group, and f w It is the total effective focal length of the endoscope adapter lens when it is at the wide-angle end.

[0016] In one implementation, the endoscope adapter lens satisfies: 0.15 ≤ (f2 + f3) / f t≤0.20, where f2 is the effective focal length of the second lens group, f3 is the effective focal length of the third lens group, and f t It is the total effective focal length of the endoscope adapter lens when it is at the telephoto end.

[0017] In one embodiment, the endoscope adapter lens satisfies: 0.35≤S / f1≤0.53, where S is the entrance pupil distance of the endoscope adapter lens and f1 is the effective focal length of the first lens group.

[0018] In one embodiment, the endoscope adapter lens satisfies: -1.28≤f2 / Z2≤-1.00, where f2 is the effective focal length of the second lens group and Z2 is the distance the second lens group moves along the optical axis.

[0019] In one embodiment, the endoscope adapter lens satisfies: 0.51≤f3 / Z3≤0.62, where f3 is the effective focal length of the third lens group and Z3 is the distance the third lens group moves along the optical axis.

[0020] In one embodiment, the endoscope adapter lens further includes a positioning surface disposed on the object side of the first lens, and the endoscope adapter lens satisfies: 0.21≤BFL / TTL≤0.26, 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 positioning surface to the imaging surface of the endoscope adapter lens.

[0021] In one embodiment, the endoscope adapter lens satisfies: 0.18≤EPD / f1≤0.20, where EPD is the entrance pupil diameter of the endoscope adapter lens and f1 is the effective focal length of the first lens group.

[0022] In one embodiment, the endoscope adapter lens satisfies: -1.90≤L7_R1 / L7_R2≤-0.70, where L7_R1 is the radius of curvature of the object side of the seventh lens, and L7_R2 is the radius of curvature of the image side of the seventh lens.

[0023] In one embodiment, the endoscope adapter lens satisfies: 2.40≤Vd6 / Vd5≤2.81, where Vd5 is the Abbe number of the fifth lens and Vd6 is the Abbe number of the sixth lens.

[0024] In one embodiment, the endoscope adapter lens satisfies: 2.50≤Vd12 / Vd11≤3.20, where Vd11 is the Abbe number of the eleventh lens and Vd12 is the Abbe number of the twelfth lens.

[0025] In one embodiment, the endoscope adapter lens satisfies: 2.40≤Vd12 / Vd13≤3.18, where Vd12 is the Abbe number of the twelfth lens and Vd13 is the Abbe number of the thirteenth lens.

[0026] The endoscope adapter lens provided according to the embodiments of this application includes three lens groups: a first lens group for focusing, a second lens group for zooming, and a third lens group for compensation. The focusing and zooming functions of the endoscope adapter lens can be performed independently. After the endoscope adapter lens has been focused at different object distances, the image can remain clear during the zooming process. By reasonably setting the optical power and operation mode of the first to third lens groups, the endoscope adapter lens provided by this application has at least one of the following beneficial effects: continuous zoom, independent focusing and zooming, infrared confocal focus, wide range of object distances, and high resolution. Attached Figure Description

[0027] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0028] Figure 1A and Figure 1B These are schematic diagrams of the endoscope adapter lens at the wide-angle end and the telephoto end according to Embodiment 1 of this application;

[0029] Figure 2A and Figure 2B These are schematic diagrams of the endoscope adapter lens at the wide-angle end and the telephoto end according to Embodiment 2 of this application;

[0030] Figure 3A and Figure 3B These are schematic diagrams of the endoscope adapter lens at the wide-angle and telephoto ends according to Embodiment 3 of this application; and

[0031] Figure 4A and Figure 4B These are schematic diagrams of the endoscope adapter lens at the wide-angle end and the telephoto end according to Embodiment 4 of this application. Detailed Implementation

[0032] To better understand this application, various aspects of this application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely illustrative of exemplary embodiments of this application and are not intended to limit the scope of this 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.

[0033] It should be noted that in this specification, the terms "first," "second," "third," etc., are used only to distinguish one feature from another and do not imply any limitation on the features. Therefore, without departing from the teachings of this application, the first lens discussed below may also be referred to as the second lens or the third lens.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] The features, principles and other aspects of this application are described in detail below.

[0040] 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. When the object distance changes, all three lens groups move along the optical axis. The first lens group is the focusing group; when the object distance changes, the position of the conjugate image changes accordingly. The first lens group moves along the optical axis to adjust the focus, ensuring the conjugate image is at the same position without changing the magnification, thus ensuring imaging stability. The second lens group is the zoom group; it 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 the compensation group; it 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 a manner corresponding to the movement of the second lens group to compensate for changes in the image plane position during zooming.

[0041] In an exemplary embodiment of this application, the position of the second lens group along the optical axis is adjustable; that is, the second lens group can move from the image side to the object side or from the object side to the image side along the optical axis to enable continuous zooming of the endoscope adapter lens. Specifically, by changing the position of the second lens group on the optical axis, the endoscope adapter lens can be switched from a wide-angle end to a telephoto end or from a telephoto end to a wide-angle end, thereby enabling continuous zooming of the endoscope adapter lens.

[0042] In an exemplary embodiment of this application, the position of the third lens group along the optical axis is adjustable. For example, the third lens group can move along the optical axis in a manner corresponding to the movement of the second lens group to achieve a compensation effect, so that the imaging position of the endoscope adapter lens remains unchanged during the zoom process and the image formed is always clear.

[0043] In an exemplary embodiment of this application, the second lens group and the third lens group form a linked combination to realize the zoom function of the system; that is, the second lens group moves to zoom and the third lens group moves to compensate, which are performed simultaneously to ensure that the image remains clear throughout the zoom process.

[0044] The focusing and zooming functions of the endoscope adapter lens provided in this application can be performed independently. After focusing the endoscope adapter lens at different object distances, clear imaging can be maintained throughout the zooming process. When this lens is used with an endoscope, it facilitates handheld use during the surgical procedure.

[0045] In an exemplary embodiment of this application, the first lens group has three lenses with optical power, and the first lens group includes, in sequence from the object side to the image side along the optical axis: a first lens with negative optical power, a second lens with positive optical power, and a third lens with positive optical power.

[0046] In an exemplary embodiment of this application, the object-side and image-side surfaces of the first lens are both concave; the image-side surface of the second lens is convex; and the object-side surface of the third lens is convex. As the first lens of the first lens group, the first lens has negative optical power, and both its object-side and image-side surfaces are concave. By setting the first lens in this shape, under the premise of meeting certain field of view and image height requirements, the light path is made smooth, which can effectively correct aberrations and reduce the system tolerance sensitivity.

[0047] In an exemplary embodiment of this application, the second lens group has three lenses with optical power, and the second lens group includes, in sequence along the optical axis from the object side to the image side: a fourth lens with negative optical power, a fifth lens with positive optical power, and a sixth lens with negative optical power.

[0048] In an exemplary embodiment of this application, the object-side and image-side surfaces of the fourth lens are both concave; the object-side surface of the fifth lens is concave, and the image-side surface is convex; the object-side surface of the sixth lens is concave. As the first two lenses of the second lens group, the fourth lens has negative optical power, with both the object-side and image-side surfaces concave, while the fifth lens has positive optical power, with both the object-side and image-side surfaces concave. Setting the fourth and fifth lenses in this shape helps to smoothly transition the light passing through the first lens group to the second lens group, reducing tolerance sensitivity and correcting various aberrations in the system.

[0049] 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.

[0050] 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 positive 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.

[0051] In an exemplary embodiment of this application, the object-side and image-side surfaces of the seventh lens are both convex; the object-side and image-side surfaces of the eighth lens are both convex; the object-side surface of the ninth lens is concave; the image-side surface of the eleventh lens is concave; the object-side and image-side surfaces 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. The seventh lens has positive optical power, a convex object-side surface, and a convex image-side surface; the eighth lens has positive optical power, a convex object-side surface, and a convex image-side surface; and the fifteenth lens has positive optical power and a convex image-side surface. The object-side surface can be either convex or concave. Reasonably setting the position, optical power, and shape of these three lenses helps to meet certain field of view angles and image heights, while also correcting system aberrations, reducing tolerance sensitivity, and improving resolution.

[0052] 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.

[0053] In an exemplary embodiment of this application, the eleventh lens, the twelfth lens, and the thirteenth lens can form a cemented triplet lens, which is beneficial for correcting chromatic aberration and reducing system tolerance sensitivity.

[0054] 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.

[0055] In an exemplary embodiment of this application, 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 an embodiment of this application, the aperture stop may be disposed between the third lens and the fourth lens. However, it should be noted that the position of the aperture stop disclosed herein is merely an example and not a limitation; in alternative embodiments, the aperture stop may be disposed in other positions as needed.

[0056] In an exemplary embodiment of this application, 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 provides waterproof, dustproof, and scratch-proof protection.

[0057] In an exemplary embodiment of this application, the endoscope adapter lens according to this application satisfies the following condition: 1.45 ≤ |φ2| / φ3 ≤ 1.60, where φ2 is the optical power of the second lens group and φ3 is the optical power of the third lens group. Satisfying 1.45 ≤ |φ2| / φ3 ≤ 1.60 ensures that the optical power of the second and third lens groups is within a reasonable range, enabling stable zooming from 14mm to 32mm. Furthermore, it ensures a linear correlation between the zoom and compensation curves, resulting in consistently clear image quality throughout the zooming process without blurring. When this lens is applied to an endoscope, it improves the reliability of the endoscope during surgical procedures.

[0058] In an exemplary embodiment of this application, when the object distance of the endoscope adapter lens is infinity, the first lens group is located at a first position on the optical axis; when the object distance of the endoscope adapter lens is 300mm, the first lens group is located at a second position on the optical axis, and can satisfy: 8.50≤f1 / (d inf -d near )≤11.80, where f1 is the effective focal length of the first lens group, (d inf -d near () is the distance between the first and second positions on the optical axis. It satisfies 8.50 ≤ f1 / (d) inf -d near With a focal length ≤ 11.80, when the object distance changes, the movement of the first lens group can adjust the corresponding conjugate image distance, ensuring that the image is focused on the same image plane, thus achieving focusing functionality, maintaining image plane stability, and providing clear imaging. When this lens is applied to an endoscope, it facilitates real-time focusing and imaging of different spatial locations during surgery.

[0059] In an exemplary embodiment of this application, the endoscope adapter lens according to this application satisfies: 0.35≤(f2+f3) / f w ≤0.45, where f2 is the effective focal length of the second lens group, f3 is the effective focal length of the third lens group, and f w This is the total effective focal length of the endoscope's adapter lens when it is at the wide-angle end. It satisfies 0.35 ≤ (f2 + f3) / f w A focal length of ≤0.45 is beneficial for the second and third lens groups to achieve a minimum focal length of 14mm during linkage, while ensuring a linear correlation between zoom and compensation, and maintaining real-time clarity in imaging throughout the entire process.

[0060] In an exemplary embodiment of this application, the endoscope adapter lens according to this application can satisfy: 0.15≤(f2+f3) / f t ≤0.20, where f2 is the effective focal length of the second lens group, f3 is the effective focal length of the third lens group, and f tThis is the total effective focal length of the endoscope's adapter lens when it is at the telephoto end. It satisfies 0.15 ≤ (f2 + f3) / f t A value of ≤0.20 is beneficial for the second and third lens groups to achieve a maximum focal length of 32mm during linkage, while ensuring a linear correlation between zoom and compensation, and maintaining real-time clarity in imaging throughout the entire process.

[0061] In an exemplary embodiment of this application, the endoscope adapter lens according to this application satisfies: 0.35≤S / f1≤0.53, where S is the entrance pupil distance of the endoscope adapter lens (i.e., the distance between the image formed by the aperture stop through the first lens group and the positioning surface), and f1 is the effective focal length of the first lens group. The aperture stop is located behind the first lens group, and the image formed by the aperture stop through the first lens group is the entrance pupil of the optical imaging system. The positioning surface is located on the object side of the first lens, more specifically, at a position 3mm on the object side of the front protective glass of the endoscope adapter lens. Satisfying 0.35≤S / f1≤0.53 is beneficial for the first lens group to maintain a small range of change in the entrance pupil position while focusing at different object distances, enabling it to adapt to more front-end endoscope main lenses.

[0062] In an exemplary embodiment of this application, the endoscope adapter lens according to this application satisfies: -1.28 ≤ f2 / Z2 ≤ -1.00, where f2 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 -1.28 ≤ f2 / Z2 ≤ -1.00 indicates that the second lens group is a zoom group, capable of achieving the lens's preset zoom range within a shorter axial movement distance, making the lens compact, lightweight, and convenient for handheld use. Specifically, Z2 is the axial distance between the position of the second lens group on the optical axis at the wide-angle end and the position of the second lens group on the optical axis at the telephoto end of the endoscope adapter lens.

[0063] In an exemplary embodiment of this application, the endoscope adapter lens according to this application satisfies: 0.51≤f3 / Z3≤0.62, where f3 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 0.51≤f3 / Z3≤0.62, 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 and lightweight, convenient for handheld use. Specifically, Z3 is the axial distance between the position of the third lens group on the optical axis at the wide-angle end and the position of the third lens group on the optical axis at the telephoto end of the endoscope adapter lens.

[0064] In an exemplary embodiment of this application, the endoscope adapter lens according to this application further includes a positioning surface disposed on the object side of the first lens. More specifically, the positioning surface is located 3mm from the object side of the front protective glass of the endoscope adapter lens, and satisfies: 0.21≤BFL / TTL≤0.26, 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 axial distance from the positioning surface to the imaging surface of the endoscope adapter lens. Satisfying 0.21≤BFL / TTL≤0.26 allows for the accommodation of the lower filter and the rear 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.

[0065] In an exemplary embodiment of this application, the endoscope adapter lens according to this application satisfies: 0.18≤EPD / f1≤0.20, where EPD is the entrance pupil diameter of the endoscope adapter lens, and f1 is the effective focal length of the first lens group. Satisfying 0.18≤EPD / f1≤0.20, the image formed by the aperture stop through the first lens group is the entrance pupil of the optical imaging system. The first lens group enables focusing at different object distances while ensuring that the system's entrance pupil diameter is always greater than a fixed value, allowing sufficient light to enter the system for imaging and improving the brightness and clarity of the image.

[0066] In an exemplary embodiment of this application, the endoscope adapter lens according to this application satisfies: -1.90≤L7_R1 / L7_R2≤-0.70, where L7_R1 is the radius of curvature of the object-side surface of the seventh lens, and L7_R2 is the radius of curvature of the image-side surface of the seventh lens. By satisfying -1.90≤L7_R1 / L7_R2≤-0.70, the seventh lens, with a biconvex shape and a certain range of optical power, is placed at the foremost end of the third lens group, receiving light from the second lens group, reducing the height of the light rays, and decreasing the incident angle of the light rays. This is beneficial for correcting aberrations and reducing tolerance sensitivity.

[0067] In an exemplary embodiment of this application, the endoscope adapter lens according to this application satisfies: 2.40≤Vd6 / Vd5≤2.81, where Vd5 is the Abbe number of the fifth lens and Vd6 is the Abbe number of the sixth lens. The fifth and sixth lenses satisfying 2.40≤Vd6 / Vd5≤2.81 is beneficial for both field curvature correction and reducing the defocusing of the infrared spectrum relative to the visible spectrum, thus achieving the infrared confocal function of the lens.

[0068] In an exemplary embodiment of this application, the endoscope adapter lens according to this application satisfies: 2.50 ≤ Vd12 / Vd11 ≤ 3.20, where Vd11 is the Abbe number of the eleventh lens and Vd12 is the Abbe number of the twelfth lens. The eleventh and twelfth lenses satisfying 2.50 ≤ Vd12 / Vd11 ≤ 3.20 is beneficial for correcting chromatic aberration in the visible spectrum, reducing secondary spectral density, and lowering tolerance sensitivity.

[0069] In an exemplary embodiment of this application, the endoscope adapter lens according to this application satisfies: 2.40 ≤ Vd12 / Vd13 ≤ 3.18, where Vd12 is the Abbe number of the twelfth lens and Vd13 is the Abbe number of the thirteenth lens. The twelfth and thirteenth lenses satisfying 2.40 ≤ Vd12 / Vd13 ≤ 3.18 is beneficial for correcting chromatic aberration in the visible spectrum, reducing secondary spectral density, and lowering tolerance sensitivity.

[0070] 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.

[0071] The endoscope adapter lens of this application has excellent resolution, with a resolution of 4K or higher.

[0072] The endoscope adapter lens of this application is characterized by its small size and short overall length. The distance TTL between the object side surface and the imaging surface of the first lens on the optical axis satisfies: TTL≤70mm, which makes the endoscope adapter lens have a small overall length, meets the miniaturization feature, and maximizes performance in the smallest possible volume.

[0073] 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.

[0074] 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.

[0075] The endoscope adapter lens of this application can adopt a glass-plastic hybrid structure, which reduces the design cost while ensuring a large magnification.

[0076] The endoscope adapter lens of this application has good individual component and assembly tolerances and good manufacturability.

[0077] 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.

[0078] Alternatively, in other alternative exemplary embodiments, the above-described endoscope adapter lens may also include a filter for correcting color deviation.

[0079] 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.

[0080] 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.

[0081] Example 1

[0082] 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 1A This 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.

[0083] 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 B1, 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, rear protective glass B2, and imaging surface Image.

[0084] In this embodiment and the following embodiments, the positioning surface D is located 3mm from the object side of the front protective glass B1 of the endoscope adapter lens. The positioning surface D can be used to calculate the entrance pupil position (the entrance pupil position is the distance between the image formed by the aperture through the first lens group and the positioning surface).

[0085] The front protective glass B1 has an object side S2 and an image side S3, and the rear protective glass B2 has an object side S30 and an image side S31.

[0086] The first lens group G1 includes a first lens L1, a second lens L2, and a third lens L3. The first lens L1 may have negative optical power, with its object-side surface S4 being concave and its image-side surface S5 being concave. The second lens L2 may have positive optical power, with its object-side surface S6 being concave and its image-side surface S7 being convex. The third lens L3 may have positive optical power, with its object-side surface S8 being convex and its image-side surface S9 being convex.

[0087] The second lens group G2 includes a fourth lens L4, a fifth lens L5, and a sixth lens L6. The fourth lens L4 can have negative optical power, with its object-side surface S11 being concave and its image-side surface S12 being concave. The fifth lens L5 can have positive optical power, with its object-side surface S13 being concave and its image-side surface S14 being convex. The sixth lens L6 can have negative optical power, with its object-side surface S14 being concave and its image-side surface S15 being concave. The fifth lens L5 and the sixth lens L6 are cemented together to form a cemented doublet lens.

[0088] 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 S16 being convex and its image-side surface S17 being convex. The eighth lens L8 can have positive optical power, with its object-side surface S18 being convex and its image-side surface S19 being convex. The ninth lens L9 can have negative optical power, with its object-side surface S19 being concave and its image-side surface S20 being convex. The tenth lens L10 can have positive optical power, with its object-side surface S21 being convex and its image-side surface S22 being convex. The eleventh lens L11 can have negative optical power, with its object-side surface S23 being concave and its image-side surface S24 being concave. Lens L12, the twelfth lens, has positive optical power; its object-side surface S24 is convex, and its image-side surface S25 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, lens L12, and lens L13 are cemented together to form a cemented triplicate lens. Lens L14 and lens L15 are cemented together to form a cemented doublet.

[0089] 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 third lens L3 and the fourth lens L4.

[0090] Light from the object passes through each surface in sequence (i.e., through the front protective glass B1, the first lens L1 to the fifteenth lens, and the rear protective glass B2 in sequence) and is finally imaged on the imaging surface Image, where an image sensing chip may be provided.

[0091] 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).

[0092]

[0093]

[0094] Table 1

[0095] In Embodiment 1 and the following embodiments, when the object distance changes, the first lens group G1, the second lens group G2, and the third lens group G3 all move along the optical axis. Focusing is achieved by moving the first lens group G1 along the optical axis, ensuring the conjugate image is positioned at the same location without changing the magnification, thus guaranteeing imaging stability. By changing the position of the second lens group G2 on the optical axis, the endoscope adapter lens can be switched from wide-angle to telephoto or vice versa, making the total effective focal length of the endoscope adapter lens continuously variable. Simultaneously, adjusting the position of the third lens group G3 on the optical axis ensures that the image plane of the endoscope adapter lens remains clearly focused during zooming.

[0096] 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.

[0097] Wide-angle end telephoto end F(mm) <![CDATA[14.14(f w )]]> <![CDATA[31.32(f t )]]> Fno 2.72 6.02 TTL(mm) 67.312 67.312 T1(mm) 0.496 6.281 T2(mm) 12.004 0.705 T3 (mm) 0.800 6.314

[0098] Table 2

[0099] Example 2

[0100] 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 the telephoto end according to Embodiment 2 of this application.

[0101] In this embodiment and the following embodiments, for the sake of brevity, the omitted parts are similar to the description in Embodiment 1.

[0102] 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 B1, 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, rear protective glass B2, and imaging surface Image.

[0103] The front protective glass B1 has an object side S2 and an image side S3, and the rear protective glass B2 has an object side S30 and an image side S31.

[0104] The first lens group G1 includes a first lens L1, a second lens L2, and a third lens L3. The first lens L1 may have negative optical power, with its object-side surface S4 being concave and its image-side surface S5 being concave. The second lens L2 may have positive optical power, with its object-side surface S6 being convex and its image-side surface S7 being convex. The third lens L3 may have positive optical power, with its object-side surface S8 being convex and its image-side surface S9 being convex.

[0105] The second lens group G2 includes a fourth lens L4, a fifth lens L5, and a sixth lens L6. The fourth lens L4 can have negative optical power, with its object-side surface S11 being concave and its image-side surface S12 being concave. The fifth lens L5 can have positive optical power, with its object-side surface S13 being concave and its image-side surface S14 being convex. The sixth lens L6 can have negative optical power, with its object-side surface S14 being concave and its image-side surface S15 being concave. The fifth lens L5 and the sixth lens L6 are cemented together to form a cemented doublet lens.

[0106] 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 S16 being convex and its image-side surface S17 being convex. The eighth lens L8 can have positive optical power, with its object-side surface S18 being convex and its image-side surface S19 being convex. The ninth lens L9 can have negative optical power, with its object-side surface S19 being concave and its image-side surface S20 being convex. The tenth lens L10 can have positive optical power, with its object-side surface S21 being concave and its image-side surface S22 being convex. The eleventh lens L11 can have negative optical power, with its object-side surface S23 being convex and its image-side surface S24 being concave. Lens L12, the twelfth lens, has positive optical power; its object-side surface S24 is convex, and its image-side surface S25 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, lens L12, and lens L13 are cemented together to form a cemented triplicate lens. Lens L14 and lens L15 are cemented together to form a cemented doublet.

[0107] 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 third lens L3 and the fourth lens L4.

[0108] Light from the object passes through each surface in sequence (i.e., through the front protective glass B1, the first lens L1 to the fifteenth lens, and the rear protective glass B2 in sequence) and is finally imaged on the imaging surface Image, where an image sensing chip may be provided.

[0109] 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).

[0110]

[0111]

[0112] Table 3

[0113] 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.

[0114] Wide-angle end telephoto end F(mm) <![CDATA[13.93(f w )]]> <![CDATA[30.88(f t )]]> Fno 2.68 5.94 TTL(mm) 67.910 67.910 T1(mm) 0.460 6.106 T2(mm) 11.547 0.774 T3 (mm) 0.300 5.428

[0115] Table 4

[0116] Example 3

[0117] 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.

[0118] 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 B1, 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, rear protective glass B2, and imaging surface Image.

[0119] The front protective glass B1 has an object side S2 and an image side S3, and the rear protective glass B2 has an object side S31 and an image side S32.

[0120] The first lens group G1 includes a first lens L1, a second lens L2, and a third lens L3. The first lens L1 may have negative optical power, with its object-side surface S4 being concave and its image-side surface S5 being concave. The second lens L2 may have positive optical power, with its object-side surface S6 being concave and its image-side surface S7 being convex. The third lens L3 may have positive optical power, with its object-side surface S8 being convex and its image-side surface S9 being concave.

[0121] The second lens group G2 includes a fourth lens L4, a fifth lens L5, and a sixth lens L6. The fourth lens L4 can have negative optical power, with its object-side surface S11 being concave and its image-side surface S12 being concave. The fifth lens L5 can have positive optical power, with its object-side surface S13 being concave and its image-side surface S14 being convex. The sixth lens L6 can have negative optical power, with its object-side surface S14 being concave and its image-side surface S15 being concave. The fifth lens L5 and the sixth lens L6 are cemented together to form a cemented doublet lens.

[0122] 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 S16 being convex and its image-side surface S17 being convex. The eighth lens L8 can have positive optical power, with its object-side surface S18 being convex and its image-side surface S19 being convex. The ninth lens L9 can have negative optical power, with its object-side surface S19 being concave and its image-side surface S20 being concave. The tenth lens L10 can have positive optical power, with its object-side surface S21 being convex and its image-side surface S22 being flat. The eleventh lens L11 can have negative optical power, with its object-side surface S23 being convex and its image-side surface S24 being concave. Lens L12, the twelfth lens, has positive optical power; its object-side surface S24 is convex, and its image-side surface S25 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 are cemented together to form a cemented doublet lens. Lens L11, lens L12, and lens L13, the eleventh lens, and lens L13 are cemented together to form a cemented triplicate lens.

[0123] 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 third lens L3 and the fourth lens L4.

[0124] Light from the object passes through each surface in sequence (i.e., through the front protective glass B1, the first lens L1 to the fifteenth lens, and the rear protective glass B2 in sequence) and is finally imaged on the imaging surface Image, where an image sensing chip may be provided.

[0125] 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).

[0126]

[0127]

[0128] Table 5

[0129] 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.

[0130] Wide-angle end telephoto end F(mm) <![CDATA[14.18(f w )]]> <![CDATA[31.23(f t )]]> Fno 2.73 6.00 TTL(mm) 69.270 69.270 T1(mm) 1.053 6.629 T2(mm) 11.821 0.868 T3 (mm) 0.350 5.727

[0131] Table 6

[0132] Example 4

[0133] 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.

[0134] 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 B1, 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, rear protective glass B2, and imaging surface Image.

[0135] The front protective glass B1 has an object side S2 and an image side S3, and the rear protective glass B2 has an object side S31 and an image side S32.

[0136] The first lens group G1 includes a first lens L1, a second lens L2, and a third lens L3. The first lens L1 may have negative optical power, with its object-side surface S4 being concave and its image-side surface S5 being concave. The second lens L2 may have positive optical power, with its object-side surface S6 being concave and its image-side surface S7 being convex. The third lens L3 may have positive optical power, with its object-side surface S8 being convex and its image-side surface S9 being concave.

[0137] The second lens group G2 includes a fourth lens L4, a fifth lens L5, and a sixth lens L6. The fourth lens L4 can have negative optical power, with its object-side surface S11 being concave and its image-side surface S12 being concave. The fifth lens L5 can have positive optical power, with its object-side surface S13 being concave and its image-side surface S14 being convex. The sixth lens L6 can have negative optical power, with its object-side surface S14 being concave and its image-side surface S15 being concave. The fifth lens L5 and the sixth lens L6 are cemented together to form a cemented doublet lens.

[0138] 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 S16 being convex and its image-side surface S17 being convex. The eighth lens L8 can have positive optical power, with its object-side surface S18 being convex and its image-side surface S19 being convex. The ninth lens L9 can have negative optical power, with its object-side surface S19 being concave and its image-side surface S20 being concave. The tenth lens L10 can have positive optical power, with its object-side surface S21 being convex and its image-side surface S22 being convex. The eleventh lens L11 can have negative optical power, with its object-side surface S23 being convex and its image-side surface S24 being concave. Lens L12, the twelfth lens, has positive optical power; its object-side surface S24 is convex, and its image-side surface S25 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 S29 is concave, and its image-side surface S30 is convex. Lens L8, the eighth lens, and lens L9 are cemented together to form a cemented doublet lens. Lens L11, lens L12, and lens L13, the eleventh lens, and lens L13 are cemented together to form a cemented triplicate lens.

[0139] 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 third lens L3 and the fourth lens L4.

[0140] Light from the object passes through each surface in sequence (i.e., through the front protective glass B1, the first lens L1 to the fifteenth lens, and the rear protective glass B2 in sequence) and is finally imaged on the imaging surface Image, where an image sensing chip may be provided.

[0141] 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).

[0142]

[0143]

[0144] Table 7

[0145] 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 unchanged.

[0146] Wide-angle end telephoto end F(mm) <![CDATA[14.03(f w )]]> <![CDATA[31.09(f t )]]> Fno 2.70 5.98 TTL(mm) 69.290 69.290 T1(mm) 1.197 6.484 T2(mm) 11.347 0.789 T3 (mm) 0.483 5.753

[0147] Table 8

[0148] In summary, Examples 1 to 4 satisfy the relationships shown in Table 9.

[0149]

[0150] Table 9

[0151] 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 in that, Along the optical axis from the object side to the image side, the following are included in sequence: A first lens group having positive optical power, wherein the first lens group is a focusing group; A second lens group with negative optical power, the second lens group being a zoom group; A third lens group with positive optical power, wherein the third lens group is a compensation group; in, The first lens group moves along the optical axis between the object side and the image side to achieve consistent conjugate image plane positions for different object distances; 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; 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. The number of lens groups with optical power in the endoscope adapter lens is three; The number of lenses with optical power in the endoscope adapter lens is fifteen; The first lens group comprises, along the optical axis from the object side to the image side, a first lens having negative optical power, a second lens having positive optical power, and a third lens having positive optical power. The second lens group comprises, along the optical axis from the object side to the image side, a fourth lens having negative optical power, a fifth lens having positive optical power, and a sixth lens having negative optical power. The third lens group comprises, along the optical axis from the object side to the image side, the following lenses in sequence: 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 positive 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. When the object distance of the endoscope adapter lens is infinity, the first lens group is located at the first position on the optical axis; When the object distance of the endoscope adapter lens is 300mm, the first lens group is located at the second position on the optical axis; The endoscope adapter lens satisfies: 8.50 ≤ f1 / (d inf -d near )≤11.80, where f1 is the effective focal length of the first lens group, (d inf -d near ) is the distance between the first position and the second position on the optical axis.

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

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

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

5. The endoscope adapter lens according to claim 1, wherein, Optical power of the second lens group 2 and the optical power of the third lens group 3 satisfies: 1.45 ≤ | 2| / 3≤1.

60.

6. The endoscope adapter lens according to claim 1, wherein, The endoscope adapter lens satisfies: 0.35 ≤ (f2 + f3) / f w ≤0.45, where f2 is the effective focal length of the second lens group, f3 is the effective focal length of the third lens group, and f w It is the total effective focal length of the endoscope adapter lens when it is at the wide-angle end.

7. The endoscope adapter lens according to claim 1, wherein, The endoscope adapter lens satisfies: 0.15 ≤ (f2 + f3) / f t ≤0.20, where f2 is the effective focal length of the second lens group, f3 is the effective focal length of the third lens group, and f t It is the total effective focal length of the endoscope adapter lens when it is at the telephoto end.

8. The endoscope adapter lens according to claim 1, wherein, The endoscope adapter lens satisfies the following condition: 0.35≤S / f1≤0.53, where S is the entrance pupil distance of the endoscope adapter lens and f1 is the effective focal length of the first lens group.

9. The endoscope adapter lens according to claim 1, wherein, The endoscope adapter lens satisfies: -1.28≤f2 / Z2≤-1.00, where f2 is the effective focal length of the second lens group and Z2 is the distance the second lens group moves on the optical axis.

10. The endoscope adapter lens according to claim 1, wherein, The endoscope adapter lens satisfies: 0.51≤f3 / Z3≤0.62, where f3 is the effective focal length of the third lens group and Z3 is the distance the third lens group moves along the optical axis.

11. The endoscope adapter lens according to claim 1, wherein, The endoscope adapter lens also includes a positioning surface placed on the object side of the first lens; The endoscope adapter lens satisfies: 0.21≤BFL / TTL≤0.26, 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 positioning surface to the imaging surface of the endoscope adapter lens.

12. The endoscope adapter lens according to claim 1, wherein, The endoscope adapter lens satisfies the following condition: 0.18≤EPD / f1≤0.20, where EPD is the entrance pupil diameter of the endoscope adapter lens, and f1 is the effective focal length of the first lens group.

13. The endoscope adapter lens according to claim 1, wherein, The endoscope adapter lens satisfies: -1.90≤L7_R1 / L7_R2≤-0.70, where L7_R1 is the radius of curvature of the object side of the seventh lens, and L7_R2 is the radius of curvature of the image side of the seventh lens.

14. The endoscope adapter lens according to claim 1, wherein, The endoscope adapter lens satisfies: 2.40≤Vd6 / Vd5≤2.81, where Vd5 is the Abbe number of the fifth lens and Vd6 is the Abbe number of the sixth lens.

15. The endoscope adapter lens according to claim 1, wherein, The endoscope adapter lens satisfies: 2.50≤Vd12 / Vd11≤3.20, where Vd11 is the Abbe number of the eleventh lens and Vd12 is the Abbe number of the twelfth lens.

16. The endoscope adapter lens according to claim 1, wherein, The endoscope adapter lens satisfies: 2.40≤Vd12 / Vd13≤3.18, where Vd12 is the Abbe number of the twelfth lens and Vd13 is the Abbe number of the thirteenth lens.

17. The endoscope adapter lens according to any one of claims 1-16, wherein, The endoscope adapter lens meets at least one of the following conditions: 8.859≤f1 / (d inf -d near )≤11.705, -1.251≤f² / Z²≤-1.099, Wherein, when the object distance of the endoscope adapter lens is infinity, the first lens group is located at the first position on the optical axis; when the object distance of the endoscope adapter lens is 300mm, the first lens group is located at the second position on the optical axis; f1 is the effective focal length of the first lens group; (d inf -d near f1 is the distance between the first position and the second position on the optical axis, f2 is the effective focal length of the second lens group, and Z2 is the distance the second lens group moves on the optical axis.

18. The endoscope adapter lens according to claim 1 or 3, wherein, The endoscope adapter lens satisfies: 2.482≤Vd6 / Vd5≤2.67, where Vd5 is the Abbe number of the fifth lens and Vd6 is the Abbe number of the sixth lens.

19. The endoscope adapter lens according to claim 1 or 4, wherein, The endoscope adapter lens satisfies: 2.632≤Vd12 / Vd11≤3.20, where Vd11 is the Abbe number of the eleventh lens, Vd12 is the Abbe number of the twelfth lens, and Vd13 is the Abbe number of the thirteenth lens.

Images