Endoscope adaptive lens

Abstract

The utility model discloses an endoscope adaptive lens. The endoscope adaptive lens sequentially comprises a first lens group with positive focal power, a second lens group with negative focal power and a third lens group with positive focal power from an object side to an image side along an optical axis, wherein the first lens group comprises a first lens, a second lens and a third lens; the second lens group comprises a fourth lens, a fifth lens and a sixth lens; the third lens group comprises a seventh lens, an eighth lens, a ninth lens, a tenth lens, an eleventh lens, a twelfth lens, a thirteenth lens, a fourteenth lens and a fifteenth lens.

Description

Technical Field

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

[0002] An endoscope adapter lens, also known as a bayonet lens, is used to cooperate with an endoscope and simultaneously connect a camera device to transmit the image detected by the endoscope to the camera device for the user to observe better.

[0003] During the use of an endoscope, a single magnification image is difficult to meet the use requirements. Therefore, a zoomable adapter is needed to present images of different magnifications for the user to observe.

[0004] The currently used endoscope adapter lenses generally have the following disadvantages: 1) During the zooming process, first zoom and then adjust compensation, and the image formed during the intermediate process is blurred. 2) When the object distance changes, the position of the conjugate image changes accordingly. To make the position of the conjugate image consistent, the existing adapter lenses refocus by moving the compensation group, and 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. When the focusing is completed at different object distances, the image can always be clear during the zooming process. Summary of the Utility Model

[0006] The present application provides such an endoscope adapter lens, which sequentially includes, from the object side to the image side along the optical axis: 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; wherein, the first lens group sequentially includes, from the object side to the image side along the optical axis: a first lens, a second lens, and a third lens; the second lens group sequentially includes, from the object side to the image side along the optical axis: a fourth lens, a fifth lens, and a sixth lens; the third lens group sequentially includes, from the object side to the image side along the optical axis: a seventh lens, an eighth lens, a ninth lens, a tenth lens, an eleventh lens, a twelfth lens, a thirteenth lens, a fourteenth lens, and a fifteenth lens.

[0007] In one embodiment, the first lens group is a focusing group, which moves between the object side and the image side along the optical axis to make the positions of the conjugate image planes at different object distances consistent; the second lens group is a zooming group, which moves between the object side and the image side along the optical axis to achieve continuous zooming between the wide-angle end and the telephoto end; the third lens group is a compensation group, which moves between the object side and the image side along the optical axis to compensate for the change in the image plane position during the zooming process.

[0008] In one embodiment, the first lens has a negative focal power; the second lens has a positive focal power; and the third lens has a positive focal power.

[0009] In one embodiment, the object side and the image side of the first lens are both concave; the image side of the second lens is convex; and the object side of the third lens is convex.

[0010] In one embodiment, the fourth lens has a negative focal power; the fifth lens has a positive focal power; and the sixth lens has a negative focal power.

[0011] In one embodiment, the object side and the image side of the fourth lens are both concave; the object side of the fifth lens is concave and the image side is convex; the object side of the sixth lens is concave.

[0012] In one embodiment, the seventh lens has a positive focal power; the eighth lens has a positive focal power; the ninth lens has a negative focal power; the tenth lens has a positive focal power; the eleventh lens has a negative focal power; the twelfth lens has a positive focal power; the thirteenth lens has a negative focal power; the fourteenth lens has a negative focal power; and the fifteenth lens has a positive focal power.

[0013] In one embodiment, the object side and the image side of the seventh lens are both convex; the object side and the image side of the eighth lens are both convex; the object side of the ninth lens is concave; the image side of the eleventh lens is concave; the object side and the image side of the twelfth lens are both convex; the object side of the thirteenth lens is concave and the image side is convex; the object side of the fourteenth lens is concave; the image side of the fifteenth lens is convex.

[0014] In one embodiment, the focal power φ2 of the second lens group and the focal power φ3 of the third lens group satisfy: 1.45 ≤ |φ2| / φ3 ≤ 1.60.

[0015] In one embodiment, when the object distance of the endoscopic adapter lens is infinity, the first lens group is located at the first position on the optical axis; when the object distance of the endoscopic adapter lens is 300 mm, the first lens group is located at the second position on the optical axis, and the endoscopic adapter lens satisfies: 8.50 ≤ f1 / (d inf -d near ) ≤ 11.80, where f1 is the effective focal length of the first lens group, and (d inf -d near ) is the distance between the first position and the second position on the optical axis.

[0016] In one embodiment, the endoscopic 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 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: 0.15 ≤ (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 is the total effective focal length of the endoscopic adapter lens at the telephoto end.

[0018] In one embodiment, the endoscopic adapter lens satisfies: 0.35 ≤ S / f1 ≤ 0.53, where S is the entrance pupil distance of the endoscopic adapter lens and f1 is the effective focal length of the first lens group.

[0019] In one embodiment, the endoscopic 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 that the second lens group moves on the optical axis.

[0020] In one embodiment, the endoscopic 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 that the third lens group moves on the optical axis.

[0021] In one embodiment, the endoscopic adapter lens further includes a positioning surface disposed on the object side of the first lens. The endoscopic 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 endoscopic adapter lens, and TTL is the on-axis distance from the positioning surface to the imaging surface of the endoscopic adapter lens.

[0022] In one embodiment, the endoscopic adapter lens satisfies: 0.18 ≤ EPD / f1 ≤ 0.20, where EPD is the entrance pupil diameter of the endoscopic adapter lens and f1 is the effective focal length of the first lens group.

[0023] In one embodiment, the endoscopic adapter lens 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.

[0024] In one embodiment, the endoscopic 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.

[0025] In one embodiment, the endoscopic 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.

[0026] In one embodiment, the endoscopic 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.

[0027] The endoscopic adapter lens provided according to the embodiment of the present application includes a first lens group to a third lens group. By reasonably setting the optical power and the number of lenses of the first lens group to the third lens group, system aberrations can be corrected, the tolerance sensitivity can be reduced, and the resolution can be improved, which is beneficial to achieving at least one of the beneficial effects such as continuous zooming, independent zooming and focusing, infrared confocal, wide object distance range, and high resolution for the endoscopic adapter lens provided by the present application. Description of the Drawings

[0028] Other features, objects, and advantages of the present application will become more apparent by reading the detailed description of the non-limiting embodiments with reference to the following drawings:

[0029] Figure 1A and Figure 1B are respectively schematic structural diagrams of the endoscopic adapter lens according to Embodiment 1 of the present application at the wide-angle end and the telephoto end;

[0030] Figure 2A and Figure 2B are respectively schematic structural diagrams of the endoscopic adapter lens according to Embodiment 2 of the present application at the wide-angle end and the telephoto end;

[0031] Figure 3A and Figure 3B are respectively schematic structural diagrams of the endoscopic adapter lens according to Embodiment 3 of the present application at the wide-angle end and the telephoto end; and

[0032] Figure 4A and Figure 4B are respectively schematic structural diagrams of the endoscopic adapter lens according to Embodiment 4 of the present application at the wide-angle end and the telephoto end. Detailed Embodiments

[0033] To better understand the present application, various aspects of the present application will be described in more detail with reference to the drawings. It should be understood that these detailed descriptions are only descriptions of the exemplary embodiments of the present application and do not 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.

[0034] It should be noted that in this specification, the expressions such as first, second, third, etc. are only used to distinguish one feature from another, and do not represent any limitation on the features. Therefore, without departing from the teachings of the present application, the first lens discussed below may also be referred to as the second lens or the third lens.

[0035] In the drawings, for the sake of clarity, the thickness, dimensions and shape of the lenses have been slightly exaggerated. Specifically, the spherical or aspherical shapes shown in the drawings are shown by way of example. That is, the spherical or aspherical shapes are not limited to the spherical or aspherical shapes shown in the drawings. The drawings are for illustrative purposes only and are not drawn to an exact scale.

[0036] In this context, 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 being photographed is called the object side surface of the lens, and the surface of each lens closest to the imaging surface is called the image side surface of the lens.

[0037] It should also be understood that the terms "comprises", "comprising", "has", "including" and / or "including having", when used in this specification, indicate the presence of the stated features, elements and / or components, but do not preclude the presence or addition of one or more other features, elements, components and / or combinations thereof. In addition, when an expression such as "at least one of..." appears after a list of listed features, it modifies the entire list of listed features, rather than an individual element in the list. In addition, when describing embodiments of the present application, the use of "may" means "one or more embodiments of the present application". And the term "exemplary" is intended to refer to an example or illustration.

[0038] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It should also be understood that terms (such as those defined in a common dictionary) should be interpreted as having a meaning consistent with their meaning in the context of the relevant art, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0039] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0040] The features, principles and other aspects of the present application will be described in detail below.

[0041] The endoscope adapter lens according to an exemplary embodiment of the present application may include three lens groups with optical powers, namely, a first lens group with a positive optical power, a second lens group with a negative optical power, and a third lens group with a positive optical power. These three lens groups are arranged in sequence along the optical axis from the object side to the image side. Among them, the first lens group includes, in sequence along the optical axis from the object side to the image side: a first lens, a second lens, and a third lens; the second lens group includes, in sequence along the optical axis from the object side to the image side: a fourth lens, a fifth lens, and a sixth lens; the third lens group includes, in sequence along the optical axis from the object side to the image side: a seventh lens, an eighth lens, a ninth lens, a tenth lens, an eleventh lens, a twelfth lens, a thirteenth lens, a fourteenth lens, and a fifteenth lens.

[0042] In an exemplary embodiment of the present application, when the object distance changes, the first lens group, the second lens group, and the third lens group can all move along the optical axis. Among them, 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 for focusing to adjust the position of the conjugate image to the same position without changing the magnification, ensuring imaging stability. The second lens group is the zooming group. The second lens group can move along the optical axis between the object side and the image side to enable the endoscope adapter lens to achieve continuous zooming between the wide-angle end and the telephoto end. The third lens group is the compensating group. The compensating group compensates for the defocus caused by the movement of the zooming group during the zooming process to ensure real-time clarity of 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.

[0043] In an exemplary embodiment of the present application, the number of lenses with optical powers in the first lens group is three, the number of lenses with optical powers in the second lens group is three, and the number of lenses with optical powers in the third lens group is nine.

[0044] In an exemplary embodiment of the present 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 the endoscope adapter lens to perform continuous zooming. Specifically, by changing the position of the second lens group 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 to enable the endoscope adapter lens to perform continuous zooming.

[0045] In an exemplary embodiment of the present 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 corresponding to the movement of the second lens group to achieve the compensation effect, so that the imaging position of the endoscope adapter lens remains unchanged during the zooming process and the image formed is always clear.

[0046] In an exemplary embodiment of the present application, the second lens group and the third lens group form a linkage combination to achieve the zoom function of the system; that is, the second lens group moves for zooming, and the third lens group moves for compensation, both occurring simultaneously, ensuring that the imaging remains clear throughout the entire process of zooming.

[0047] The focusing function and the zoom function of the endoscope adapter lens provided in the present application can be performed independently. After the focusing for different object distances of the endoscope adapter lens is completed, during the process of zooming, clear imaging can be achieved. When this lens is applied to an endoscope, it is convenient for hand-held use during the surgical process.

[0048] In an exemplary embodiment of the present application, the first lens group includes, in order from the object side to the image side along the optical axis: a first lens with a negative optical power, a second lens with a positive optical power, and a third lens with a positive optical power.

[0049] In an exemplary embodiment of the present application, both the object side surface and the image side surface 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. As the first lens of the first lens group, the first lens has a negative optical power, the object side surface is concave, and the image side surface is concave. Setting the first lens in this shape can make the light rays have a gentle trend on the premise of meeting certain requirements for the field of view angle and image height, effectively correct aberrations, and reduce the sensitivity of the system to tolerances.

[0050] In an exemplary embodiment of the present application, the number of lenses with optical power in the second lens group is three. The second lens group includes, in order from the object side to the image side along the optical axis: a fourth lens with a negative optical power, a fifth lens with a positive optical power, and a sixth lens with a negative optical power.

[0051] In an exemplary embodiment of the present application, both the object side surface and the image side surface 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. As the first two lenses of the second lens group, the fourth lens has a negative optical power, the object side surface is concave, and the image side surface is concave. The fifth lens has a positive optical power, the object side surface is concave, and the image side surface is convex. Setting the fourth lens and the fifth lens in this shape is beneficial for the light rays passing through the first lens group to transition smoothly to the second lens group, reducing the tolerance sensitivity and correcting various aberrations of the system.

[0052] In an 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, achieving the infrared confocal function of the lens.

[0053] In an exemplary embodiment of the present application, the third lens group sequentially includes, from the object side to the image side along the optical axis: a seventh lens with a positive focal power; an eighth lens with a positive focal power; a ninth lens with a negative focal power; a tenth lens with a positive focal power; an eleventh lens with a negative focal power; a twelfth lens with a positive focal power; a thirteenth lens with a negative focal power; a fourteenth lens with a negative focal power; and a fifteenth lens with a positive focal power.

[0054] In an exemplary embodiment of the present application, both the object side surface and the image side surface of the seventh lens are convex surfaces; both the object side surface and the image side surface of the eighth lens are convex surfaces; the object side surface of the ninth lens is a concave surface; the image side surface of the eleventh lens is a concave surface; both the object side surface and the image side surface of the twelfth lens are convex surfaces; the object side surface of the thirteenth lens is a concave surface and the image side surface is a convex surface; the object side surface of the fourteenth lens is a concave surface; the image side surface of the fifteenth lens is a convex surface. The seventh lens has a positive focal power, the object side surface is convex, and the image side surface is convex. The eighth lens has a positive focal power, the object side surface is convex, and the image side surface is convex. The fifteenth lens has a positive focal power, the image side surface is convex, and the object side surface can be a convex surface or a concave surface. Reasonably setting the positions, focal powers, and shapes of the above three lenses is beneficial to meeting a certain field of view angle and image height, and at the same time, it can correct system aberrations, reduce tolerance sensitivity, and improve resolution.

[0055] In an exemplary embodiment of the present application, the eighth lens and the ninth lens can form a doublet lens, which is beneficial to reducing the system tolerance sensitivity.

[0056] In an exemplary embodiment of the present application, the eleventh lens, the twelfth lens, and the thirteenth lens can form a triplet lens, which is beneficial to correcting chromatic aberration and reducing the system tolerance sensitivity.

[0057] In an exemplary embodiment of the present application, the fourteenth lens and the fifteenth lens can form a doublet lens, which is beneficial to reducing the system tolerance sensitivity.

[0058] In an exemplary embodiment of the present application, the endoscopic adapter lens according to the present application further includes a diaphragm disposed between the first lens group and the second lens group. The diaphragm is beneficial to converging the light entering the lens, reducing the rear aperture diameter of the lens, and reducing the assembly sensitivity of the system. In an embodiment of the present application, the diaphragm can be disposed between the third lens and the fourth lens. However, it should be noted that the position of the diaphragm disclosed herein is only an example and not a limitation; in alternative embodiments, the diaphragm can also be disposed at other positions according to actual needs.

[0059] In an exemplary embodiment of the present application, the endoscopic 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. The protective glass plays a protective role of waterproof, dustproof, and scratch-resistant.

[0060] In an exemplary embodiment of the present application, the endoscopic adapter lens according to the present application can satisfy: 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 enables the optical powers of the second lens group and the third lens group to be matched within a reasonable range, achieving stable zooming with a focal length ranging from 14 mm to 32 mm; and ensuring a linear correlation between the zooming and compensation curves, such that the image quality remains clear in real time throughout the zooming process without blurring. When this lens is applied to an endoscope, it can improve the reliability of the endoscope during surgery.

[0061] In an exemplary embodiment of the present application, when the object distance of the endoscopic adapter lens according to the present application is infinity, the first lens group is located at the first position on the optical axis. When the object distance of the endoscopic adapter lens is 300 mm, the first lens group is located at the second position on the optical axis, and it can satisfy: 8.50 ≤ f1 / (d inf -d near ) ≤ 11.80, where f1 is the effective focal length of the first lens group, and (d inf -d near ) is the distance between the first position and the second position on the optical axis. Satisfying 8.50 ≤ f1 / (d inf -d near ) ≤ 11.80, when the object distance of the camera changes, the movement of the first lens group can adjust the corresponding conjugate image distance, enabling imaging on the same image plane, thereby achieving the focusing function and maintaining a stable image plane with clear imaging. When this lens is applied to an endoscope, it facilitates real-time focusing imaging of different spatial parts during surgery.

[0062] In an exemplary embodiment of the present application, the endoscopic adapter lens according to the present application can satisfy: 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 is the total effective focal length of the endoscopic adapter lens at the wide-angle end. Satisfying 0.35 ≤ (f2 + f3) / f w ≤ 0.45 is beneficial for the second lens group and the third lens group to achieve a minimum focal length of 14 mm during linkage, and to ensure a linear correlation between zooming and compensation, with clear imaging in real time throughout the process.

[0063] In an exemplary embodiment of the present application, the endoscopic adapter lens according to the present 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 tis the total effective focal length when the endoscope adapter lens is at the long focal end. It satisfies 0.15 ≤ (f2 + f3) / f t ≤ 0.20, which is beneficial for the second lens group and the third lens group to achieve the longest focal length of the lens up to 32 mm during linkage, and ensure the linear correlation between zooming and compensation, and keep the imaging clear in real time throughout the process.

[0064] In an exemplary embodiment of the present application, the endoscope adapter lens according to the present application can satisfy: 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 diaphragm passing through the first lens group and the positioning surface), and f1 is the effective focal length of the first lens group. The diaphragm is located behind the first lens group, and the image formed by the diaphragm passing through the first lens group is the entrance pupil of the optical imaging system. Among them, the positioning surface is located on the object side of the first lens. More specifically, the positioning surface is located at a position 3 mm 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 focus on different object distances while ensuring that the change in the entrance pupil position is within a small range, and can adapt to more front-end endoscope main lenses.

[0065] In an exemplary embodiment of the present application, the endoscope adapter lens according to the present application can satisfy: -1.28 ≤ f2 / Z2 ≤ -1.00, where f2 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. Satisfying -1.28 ≤ f2 / Z2 ≤ -1.00, the second lens group is a zoom group, which can reach the preset zoom range of the lens within a short axial movement distance, making the lens overall compact and lightweight, and convenient for handheld use. Specifically, Z2 is the axial distance between the position of the second lens group on the optical axis when the endoscope adapter lens is at the wide-angle end and the position of the second lens group on the optical axis when the endoscope adapter lens is at the long focal end.

[0066] In an exemplary embodiment of the present application, the endoscope adapter lens according to the present application can satisfy: 0.51 ≤ f3 / Z3 ≤ 0.62, where f3 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 0.51 ≤ f3 / Z3 ≤ 0.62, the third lens group is a compensation group corresponding to the second lens group, which can satisfy the compensation function of the zoom range within a short axial movement distance, ensure clear imaging, and make the lens overall compact and lightweight, and convenient for handheld use. Specifically, Z3 is the axial distance between the position of the third lens group on the optical axis when the endoscope adapter lens is at the wide-angle end and the position of the third lens group on the optical axis when the endoscope adapter lens is at the long focal end.

[0067] In an exemplary embodiment of the present application, the endoscope adapter lens according to the present application further includes a positioning surface disposed on the object side of the first lens. More specifically, the positioning surface is located 3 mm from the object side of the front protective glass of the endoscope adapter lens, and can satisfy: 0.21≤BFL / TTL≤0.26, 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 positioning surface to the imaging surface of the endoscope adapter lens. Satisfying 0.21≤BFL / TTL≤0.26 can accommodate filters and rear protective glass; can meet the requirements of the C interface, and can meet the requirements of the CS interface through the adapter ring; can also shorten the overall length of the lens, making the lens as a whole compact and light, and convenient for handheld use.

[0068] In an exemplary embodiment of the present application, the endoscope adapter lens according to the present application can satisfy: 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. When 0.18≤EPD / f1≤0.20 is satisfied, the image formed by the aperture through the first lens group is the entrance pupil of the optical imaging system. While the first lens group realizes focusing at different object distances, it ensures that the system entrance pupil diameter is greater than a fixed value, so that enough light enters the system to participate in imaging, thereby improving the brightness and clarity of the imaging.

[0069] In an exemplary embodiment of the present application, the endoscope adapter lens according to the present application can satisfy: -1.90≤L7_R1 / L7_R2≤-0.70, wherein 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. Satisfying -1.90≤L7_R1 / L7_R2≤-0.70, the seventh lens is placed at the front end of the third lens group in a biconvex shape and a certain range of optical power, receiving the light from the second lens group, reducing the height of the light, and reducing the incident angle of the light, which is conducive to correcting aberrations and reducing the sensitivity of tolerances.

[0070] In an exemplary embodiment of the present application, the endoscope adapter lens according to the present application satisfies: 2.40≤Vd6 / Vd5≤2.81, wherein Vd5 is the Abbe number of the fifth lens, and Vd6 is the Abbe number of the sixth lens. The fifth lens and the sixth lens satisfy 2.40≤Vd6 / Vd5≤2.81, which is beneficial to the correction of field curvature and the reduction of the defocus amount of the infrared spectrum relative to the visible spectrum, thereby realizing the infrared confocal function of the lens.

[0071] In an exemplary embodiment of the present application, the endoscope adapter lens according to the present 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 fact that the eleventh lens and the twelfth lens satisfy 2.50 ≤ Vd12 / Vd11 ≤ 3.20 is beneficial to correcting the chromatic aberration of the visible spectrum, reducing the secondary spectrum, and reducing the tolerance sensitivity.

[0072] In an exemplary embodiment of the present application, the endoscope adapter lens according to the present 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 fact that the twelfth lens and the thirteenth lens satisfy 2.40 ≤ Vd12 / Vd13 ≤ 3.18 is beneficial to correcting the chromatic aberration of the visible spectrum, reducing the secondary spectrum, and reducing the tolerance sensitivity.

[0073] In an exemplary embodiment, the first lens to the fifteenth lens can be spherical lenses or aspherical lenses. The present application does not specifically limit the specific number of spherical lenses and aspherical lenses. When focusing on reflecting the imaging quality, the number of aspherical lenses can be increased, and even all lenses can be aspherical lenses. The characteristic of an aspherical lens is that the curvature continuously changes from the center to the periphery of the lens. Different from a spherical lens with a constant curvature from the center to the periphery of the lens, an aspherical lens has better curvature radius characteristics and has the advantages of improving distortion aberration and astigmatism aberration. After using an aspherical lens, it is possible to eliminate the aberration that appears during imaging as much as possible, thereby improving the imaging quality of the lens. Optionally, the object side and the image side of the first lens to the fifteenth lens are spherical mirror surfaces.

[0074] The endoscope adapter lens of the present application has excellent resolution, with a resolution of more than 4K.

[0075] The endoscope adapter lens of the present application has the characteristics of a small volume and a short overall length. The distance TTL from the object side of the first lens to the imaging surface on the optical axis satisfies: TTL ≤ 70 mm, enabling the endoscope adapter lens to have a smaller overall length, meeting the miniaturization characteristics, and maximizing the performance with as small a volume as possible.

[0076] The endoscope adapter lens of the present application can focus on a wide range of object distances, and can ensure clear focus for object distances from 0.3 m to infinity throughout the zoom process, with good imaging effects.

[0077] The endoscope adapter lens of the present application can achieve infrared confocal, ensuring the imaging performance in the infrared band in the design, and combined with the use of an infrared fill light, enabling the lens to be applicable to night scenes and the endoscope field.

[0078] The endoscopic adapter lens of the present application can adopt a hybrid glass-plastic structure, which reduces the design cost while ensuring a large magnification ratio.

[0079] The single-component and assembly tolerances of the endoscopic adapter lens of the present application are good, and it has good manufacturability.

[0080] By reasonably setting the optical power of each lens group and the optical power and surface shape of each lens in the present application, it is beneficial for the endoscopic adapter lens to have good ability to correct optical aberrations and chromatic aberrations when switching between the wide-angle end and the telephoto end. At the same time, it is beneficial to reduce the tolerance sensitivity of the system and improve the uniformity of the picture and other effects.

[0081] Optionally, in other alternative exemplary embodiments, the above endoscopic adapter lens may further include a filter for correcting color deviation.

[0082] However, those skilled in the art should understand that without departing from the technical solutions claimed in the present application, the number of lenses constituting the endoscopic 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 endoscopic adapter lens is not limited to including fifteen lenses. If necessary, the endoscopic adapter lens may further include other numbers of lenses.

[0083] The following further describes specific embodiments of the endoscopic adapter lens applicable to the above embodiments with reference to the drawings.

[0084] Example 1

[0085] The following refers to Figure 1A and Figure 1B Describe the endoscopic adapter lens 100 according to Embodiment 1 of the present application. Figure 1A is a schematic structural diagram of the endoscopic adapter lens 100 according to Embodiment 1 of the present application when it is at the wide-angle end, Figure 1B is a schematic structural diagram of the endoscopic adapter lens 100 according to Embodiment 1 of the present application when it is at the telephoto end.

[0086] As Figure 1A and Figure 1B shown, the endoscopic adapter lens 100 sequentially includes, from the object side to the image side: a positioning surface D, a front protective glass B1, a first lens group G1 with positive optical power, a diaphragm STO, a second lens group G2 with negative optical power, a third lens group G3 with positive optical power, a rear protective glass B2, and an imaging surface Image.

[0087] In this embodiment and the following embodiments, the positioning surface D is located at a position 3 mm on 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 diaphragm passing through the first lens group and the positioning surface).

[0088] The front protective glass B1 has an object side surface S2 and an image side surface S3, and the rear protective glass B2 has an object side surface S30 and an image side surface S31.

[0089] 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 a negative optical power, its object side surface S4 is concave, and its image side surface S5 is concave. The second lens L2 may have a positive optical power, its object side surface S6 is concave, and its image side surface S7 is convex. The third lens L3 may have a positive optical power, its object side surface S8 is convex, and its image side surface S9 is convex.

[0090] The second lens group G2 includes a fourth lens L4, a fifth lens L5, and a sixth lens L6. The fourth lens L4 may have a negative optical power, its object side surface S11 is convex, and its image side surface S12 is concave. The fifth lens L5 may have a positive optical power, its object side surface S13 is concave, and its image side surface S14 is convex. The sixth lens L6 may have a negative optical power, its object side surface S14 is concave, and its image side surface S15 is convex. The fifth lens L5 and the sixth lens L6 are cemented together to form a doublet lens.

[0091] 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 a positive focal power, with its object side S16 being convex and its image side S17 being convex. The eighth lens L8 may have a positive focal power, with its object side S18 being convex and its image side S19 being convex. The ninth lens L9 may have a negative focal power, with its object side S19 being concave and its image side S20 being concave. The tenth lens L10 may have a positive focal power, with its object side S21 being convex and its image side S22 being convex. The eleventh lens L11 may have a negative focal power, with its object side S23 being convex and its image side S24 being concave. The twelfth lens L12 may have a positive focal power, with its object side S24 being convex and its image side S25 being convex. The thirteenth lens L13 may have a negative focal power, with its object side S25 being concave and its image side S26 being convex. The fourteenth lens L14 may have a negative focal power, with its object side S27 being concave and its image side S28 being convex. The fifteenth lens L15 may have a positive focal power, with its object side S28 being concave and its image side S29 being convex. The eighth lens L8 and the ninth lens L9 are cemented together to form a doublet lens. The eleventh lens L11, the twelfth lens L12, and the thirteenth lens L13 are cemented together to form a triplet lens. The fourteenth lens L14 and the fifteenth lens L15 are cemented together to form a doublet lens.

[0092] The aperture stop STO may be disposed between the first lens group G1 and the second lens group G2. More specifically, the aperture stop STO may be disposed between the third lens L3 and the fourth lens L4.

[0093] Light from the object sequentially passes through each surface (i.e., sequentially passes through the front protective glass B1, the first lens L1 to the fifteenth lens, and the rear protective glass B2) and finally forms an image on the imaging surface Image, where an image sensing chip may be disposed at the imaging surface.

[0094] Table 1 shows the basic parameter table of the endoscope adapter lens 100 of Embodiment 1, where the units of the radius of curvature and the thickness / distance are both millimeters (mm).

[0095]

[0096]

[0097] Table 1

[0098] 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. The first lens group G1 moves along the optical axis for focusing, and without changing the magnification, the position of the conjugate image is adjusted to the same position to ensure imaging stability. By changing the position of the second lens group G2 on the optical axis, the endoscopic 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 endoscopic 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 can be clearly focused during the zooming process of the endoscopic adapter lens.

[0099] Table 2 shows the values of T1, T2, and T3 in Table 1 when the endoscopic 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 overall optical length TTL, and the aperture value Fno of the endoscopic adapter lens 100 of Embodiment 1, where F and Fno change as the endoscopic 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.

[0100] Wide-angle end Telephoto end F (mm) <![CDATA[14.03(f w )]]> <![CDATA[31.09(f t )]]> Fno 2.70 5.98 TTL (mm) 69.600 69.600 T1 (mm) 1.049 6.329 T2 (mm) 11.264 0.723 T3 (mm) 1.000 6.260

[0101] Table 2

[0102] Example 2

[0103] The following refers to Figure 2A and Figure 2B describe the endoscopic adapter lens 200 according to Embodiment 2 of the present application. Figure 2A is a schematic structural diagram of the endoscopic adapter lens 200 according to Embodiment 2 of the present application when it is at the wide-angle end, Figure 2B is a schematic structural diagram of the endoscopic adapter lens 200 according to Embodiment 2 of the present application when it is at the telephoto end.

[0104] In this embodiment and the following embodiments, for the sake of simplicity, some descriptions similar to those in Embodiment 1 will be omitted.

[0105] As Figure 2A and Figure 2B shown, the endoscopic adapter lens 200 sequentially includes, from the object side to the image side: a positioning surface D, a front protective glass B1, a first lens group G1 with positive optical power, a diaphragm STO, a second lens group G2 with negative optical power, a third lens group G3 with positive optical power, a rear protective glass B2, and an imaging surface Image.

[0106] The front protective glass B1 has an object side surface S2 and an image side surface S3, and the rear protective glass B2 has an object side surface S30 and an image side surface S31.

[0107] 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 a negative focal power, its object side S4 is concave, and its image side S5 is concave. The second lens L2 may have a positive focal power, its object side S6 is convex, and its image side S7 is convex. The third lens L3 may have a positive focal power, its object side S8 is convex, and its image side S9 is convex.

[0108] The second lens group G2 includes a fourth lens L4, a fifth lens L5, and a sixth lens L6. The fourth lens L4 may have a negative focal power, its object side S11 is concave, and its image side S12 is concave. The fifth lens L5 may have a positive focal power, its object side S13 is concave, and its image side S14 is convex. The sixth lens L6 may have a negative focal power, its object side S14 is concave, and its image side S15 is concave. The fifth lens L5 and the sixth lens L6 are cemented together to form a doublet lens.

[0109] 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 a positive focal power, its object side S16 is convex, and its image side S17 is convex. The eighth lens L8 may have a positive focal power, its object side S18 is convex, and its image side S19 is convex. The ninth lens L9 may have a negative focal power, its object side S19 is concave, and its image side S20 is convex. The tenth lens L10 may have a positive focal power, its object side S21 is concave, and its image side S22 is convex. The eleventh lens L11 may have a negative focal power, its object side S23 is convex, and its image side S24 is concave. The twelfth lens L12 may have a positive focal power, its object side S24 is convex, and its image side S25 is convex. The thirteenth lens L13 may have a negative focal power, its object side S25 is concave, and its image side S26 is convex. The fourteenth lens L14 may have a negative focal power, its object side S27 is concave, and its image side S28 is concave. The fifteenth lens L15 may have a positive focal power, its object side S28 is convex, and its image side S29 is convex. The eighth lens L8 and the ninth lens L9 are cemented together to form a doublet lens. The eleventh lens L11, the twelfth lens L12, and the thirteenth lens L13 are cemented together to form a triplet lens. The fourteenth lens L14 and the fifteenth lens L15 are cemented together to form a doublet lens.

[0110] The stop STO may be disposed between the first lens group G1 and the second lens group G2. More specifically, the stop STO may be disposed between the third lens L3 and the fourth lens L4.

[0111] Light from an object sequentially passes through each surface (i.e., sequentially passes through the front protective glass B1, the first lens L1 to the fifteenth lens, and the rear protective glass B2) and finally forms an image on the imaging surface Image, where an image sensing chip may be disposed at the imaging surface.

[0112] Table 3 shows the basic parameter table of the endoscope adapter lens 200 of Embodiment 2, where the units of the radius of curvature and the thickness / distance are both millimeters (mm).

[0113]

[0114]

[0115] Table 3

[0116] 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 overall optical length TTL, and the aperture value Fno of the endoscope adapter lens 200 of Embodiment 2, where 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.

[0117] 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

[0118] Table 4

[0119] Example 3

[0120] The following refers to Figure 3A and Figure 3B describe the endoscope adapter lens 300 according to Embodiment 3 of the present application. 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 is a schematic structural diagram of the endoscope adapter lens 300 according to Embodiment 3 of the present application when it is at the telephoto end.

[0121] As Figure 3A and Figure 3B shown, the endoscope adapter lens 300 sequentially includes, from the object side to the image side: a positioning surface D, a front protective glass B1, a first lens group G1 with a positive optical power, a diaphragm STO, a second lens group G2 with a negative optical power, a third lens group G3 with a positive optical power, a rear protective glass B2, and an imaging surface Image.

[0122] The front protective glass B1 has an object side surface S2 and an image side surface S3, and the rear protective glass B2 has an object side surface S31 and an image side surface S32.

[0123] 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 a negative focal power, its object side S4 is concave, and its image side S5 is concave. The second lens L2 may have a positive focal power, its object side S6 is concave, and its image side S7 is convex. The third lens L3 may have a positive focal power, its object side S8 is convex, and its image side S9 is concave.

[0124] The second lens group G2 includes a fourth lens L4, a fifth lens L5, and a sixth lens L6. The fourth lens L4 may have a negative focal power, its object side S11 is concave, and its image side S12 is concave. The fifth lens L5 may have a positive focal power, its object side S13 is concave, and its image side S14 is convex. The sixth lens L6 may have a negative focal power, its object side S14 is concave, and its image side S15 is concave. The fifth lens L5 and the sixth lens L6 are cemented together to form a doublet lens.

[0125] 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 a positive focal power, its object side S16 is convex, and its image side S17 is convex. The eighth lens L8 may have a positive focal power, its object side S18 is convex, and its image side S19 is convex. The ninth lens L9 may have a negative focal power, its object side S19 is concave, and its image side S20 is concave. The tenth lens L10 may have a positive focal power, its object side S21 is convex, and its image side S22 is flat. The eleventh lens L11 may have a negative focal power, its object side S23 is convex, and its image side S24 is concave. The twelfth lens L12 may have a positive focal power, its object side S24 is convex, and its image side S25 is convex. The thirteenth lens L13 may have a negative focal power, its object side S25 is concave, and its image side S26 is convex. The fourteenth lens L14 may have a negative focal power, its object side S27 is concave, and its image side S28 is concave. The fifteenth lens L15 may have a positive focal power, its object side S29 is convex, and its image side S30 is convex. The eighth lens L8 and the ninth lens L9 are cemented together to form a doublet lens. The eleventh lens L11, the twelfth lens L12, and the thirteenth lens L13 are cemented together to form a triplet lens.

[0126] The stop STO may be disposed between the first lens group G1 and the second lens group G2. More specifically, the stop STO may be disposed between the third lens L3 and the fourth lens L4.

[0127] Light from an object sequentially passes through each surface (i.e., sequentially passes through the front protective glass B1, the first lens L1 to the fifteenth lens, and the rear protective glass B2) and finally forms an image on the imaging surface Image, where an image sensing chip may be provided at the imaging surface.

[0128] Table 5 shows the basic parameter table of the endoscope adapter lens 300 of Embodiment 3, where the units of the radius of curvature and the thickness / distance are both millimeters (mm).

[0129]

[0130] Table 5

[0131] 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 overall optical length TTL, and the aperture value Fno of the endoscope adapter lens 300 of Embodiment 2, where 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.

[0132] 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

[0133] Table 6

[0134] Example 4

[0135] The following refers to Figure 4A and Figure 4B to describe the endoscope adapter lens 400 according to Embodiment 4 of the present application. Figure 4A is a schematic structural diagram of the endoscope adapter lens 400 according to Embodiment 4 of the present application when it is at the wide-angle end, Figure 4B is a schematic structural diagram of the endoscope adapter lens 400 according to Embodiment 4 of the present application when it is at the telephoto end.

[0136] As Figure 4A and Figure 4B shown, the endoscope adapter lens 400 sequentially includes, from the object side to the image side: a positioning surface D, a front protective glass B1, a first lens group G1 with a positive optical power, a diaphragm STO, a second lens group G2 with a negative optical power, a third lens group G3 with a positive optical power, a rear protective glass B2, and an imaging surface Image.

[0137] The front protective glass B1 has an object side surface S2 and an image side surface S3, and the rear protective glass B2 has an object side surface S31 and an image side surface S32.

[0138] 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 a negative focal power, with its object side S4 being concave and its image side S5 being concave. The second lens L2 may have a positive focal power, with its object side S6 being concave and its image side S7 being convex. The third lens L3 may have a positive focal power, with its object side S8 being convex and its image side S9 being concave.

[0139] The second lens group G2 includes a fourth lens L4, a fifth lens L5, and a sixth lens L6. The fourth lens L4 may have a negative focal power, with its object side S11 being concave and its image side S12 being concave. The fifth lens L5 may have a positive focal power, with its object side S13 being concave and its image side S14 being convex. The sixth lens L6 may have a negative focal power, with its object side S14 being concave and its image side S15 being concave. The fifth lens L5 and the sixth lens L6 are cemented together to form a doublet lens.

[0140] 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 a positive focal power, with its object side S16 being convex and its image side S17 being convex. The eighth lens L8 may have a positive focal power, with its object side S18 being convex and its image side S19 being convex. The ninth lens L9 may have a negative focal power, with its object side S19 being concave and its image side S20 being concave. The tenth lens L10 may have a positive focal power, with its object side S21 being convex and its image side S22 being convex. The eleventh lens L11 may have a negative focal power, with its object side S23 being convex and its image side S24 being concave. The twelfth lens L12 may have a positive focal power, with its object side S24 being convex and its image side S25 being convex. The thirteenth lens L13 may have a negative focal power, with its object side S25 being concave and its image side S26 being convex. The fourteenth lens L14 may have a negative focal power, with its object side S27 being concave and its image side S28 being convex. The fifteenth lens L15 may have a positive focal power, with its object side S29 being concave and its image side S30 being convex. The eighth lens L8 and the ninth lens L9 are cemented together to form a doublet lens. The eleventh lens L11, the twelfth lens L12, and the thirteenth lens L13 are cemented together to form a triplet lens.

[0141] The aperture stop STO may be disposed between the first lens group G1 and the second lens group G2. More specifically, the aperture stop STO may be disposed between the third lens L3 and the fourth lens L4.

[0142] Light from the object sequentially passes through each surface (i.e., sequentially passes through the front protective glass B1, the first lens L1 to the fifteenth lens, and the rear protective glass B2) and finally forms an image on the imaging surface Image, where an image sensing chip may be provided at the imaging surface.

[0143] Table 7 shows the basic parameter table of the endoscope adapter lens 400 of Embodiment 4, where the units of the radius of curvature and the thickness / distance are both millimeters (mm).

[0144]

[0145] Table 7

[0146] 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 Embodiment 4, where 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.

[0147] 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

[0148] Table 8

[0149] In summary, Embodiments 1 to 4 respectively satisfy the relationships shown in Table 9.

[0150] Conditional formula / Example 1 2 3 4 <![CDATA[1.45 ≤ |φ2| / φ3 ≤ 1.60]]> 1.570 1.473 1.499 1.555 <![CDATA[8.50 ≤ f1 / (d inf -d near ) ≤ 11.80]]> 11.170 8.859 11.705 10.945 <![CDATA[2.00 ≤ f1 / Z1 ≤ 3.25]]> 2.045 3.209 2.082 2.153 <![CDATA[0.35 ≤ (f2 + f3) / f w ≤ 0.45]]> 0.425 0.371 0.392 0.414 <![CDATA[0.15 ≤ (f2 + f3) / f t ≤ 0.20]]> 0.192 0.167 0.178 0.187 <![CDATA[0.35 ≤ S / f1 ≤ 0.53]]> 0.521 0.387 0.501 0.507 <![CDATA[-1.28 ≤ f2 / Z2 ≤ -1.00]]> -1.101 -1.099 -1.153 -1.121 <![CDATA[0.51 ≤ f3 / Z3 ≤ 0.62]]> 0.574 0.533 0.595 0.603 0.21 ≤ BFL / TTL ≤ 0.26 0.194 0.196 0.195 0.225 <![CDATA[0.18 ≤ EPD / f1 ≤ 0.20]]> 0.200 0.186 0.195 0.196 -1.90 ≤ L7_R1 / L7_R2 ≤ -0.70 -1.029 -0.836 -1.000 -0.722 2.40 ≤ Vd6 / Vd5 ≤ 2.81 2.803 2.482 2.670 2.597 2.50 ≤ Vd12 / Vd11 ≤ 3.20 2.873 2.928 3.200 2.920 2.40 ≤ Vd12 / Vd13 ≤ 3.18 2.962 2.608 3.173 2.953

[0151] Table 9

[0152] The above description is only the preferred embodiments of the present application and the description of the applied technical principles. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solutions formed by the 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 technical solutions formed by mutually replacing the above features with the (but not limited to) technical features with similar functions disclosed in the present application.

Claims

1. An endoscope adapter lens, characterized in that: The lens system includes, in order from the object side to the image side along the optical axis: 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; wherein, The first lens group includes, in order from the object side to the image side along the optical axis: a first lens, a second lens and a third lens; The second lens group includes, in order from the object side to the image side along the optical axis: a fourth lens, a fifth lens and a sixth lens; The third lens group includes, in order from the object side to the image side along the optical axis, a seventh lens, an eighth lens, a ninth lens, a tenth lens, an eleventh lens, a twelfth lens, a thirteenth lens, a fourteenth lens and a fifteenth lens.

2. The endoscope adapter lens according to claim 1, characterized in that: The first lens group is a focusing group, which moves between the object side and the image side along the optical axis to achieve consistent positions of conjugate image planes at different object distances; The second lens group is a zoom group, which 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 is a compensation group, which moves between the object side and the image side along the optical axis to compensate for changes in the image plane position during zooming.

3. The endoscope adapter lens according to claim 1, characterized in that: The first lens has negative optical power, and both the object side surface and the image side surface thereof are concave; The second lens has positive refractive power, and its image side surface is convex; and The third lens has positive refractive power, and its object side surface is convex.

4. The endoscope adapter lens according to claim 1, characterized in that: The fourth lens has negative optical power, and both the object side surface and the image side surface thereof are concave; The fifth lens has positive refractive power, its object side surface is concave, and its image side surface is convex; and The sixth lens has negative optical power, and its object side surface is concave.

5. The endoscope adapter lens according to claim 1, characterized in that: The seventh lens has positive refractive power, and both the object side surface and the image side surface thereof 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 negative optical power, and its object side surface is concave; The tenth lens has positive optical power; The eleventh lens has negative optical power, and its image side surface is concave; The twelfth lens has positive refractive power, and both the object side surface and the image side surface thereof are convex surfaces; The thirteenth lens has negative optical power, and its object side surface is concave, and its image side surface is convex; The fourteenth lens has negative optical power, and its object side surface is concave; and The fifteenth lens has positive refractive power, and its image side surface is convex.

6. The endoscope adapter lens according to claim 1, characterized in that: 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.

7. The endoscope adapter lens according to claim 2, characterized in that: When the object distance of the endoscope adapter lens is infinite, the first lens group is located at a first position on the optical axis; When the object distance of the endoscope adapter lens is 300 mm, the first lens group is located at a second position on the optical axis; The endoscope adapter lens meets the following requirements: 8.50≤f1 / (d inf -d near )≤11.80, wherein f1 is the effective focal length of the first lens group, and (dinf-dnear) is the spacing distance between the first position and the second position on the optical axis.

8. The endoscope adapter lens according to claim 2, characterized in that: The endoscope adapter lens satisfies any one of the following conditional expressions: <h2 style=";text-align:left;direction:ltr">0.35≤(f2+f3) / f<h2 style=";text-align:left;direction:ltr"> w <h2 style=";text-align:left;direction:ltr"> ≤0.45,0.15≤(f2+f3) / f<h2 style=";text-align:left;direction:ltr"> t <h2 style=";text-align:left;direction:ltr"> ≤0.20,-1.28≤f2 / Z2≤-1.00,0.51≤f3 / Z3≤0.62, Wherein, 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 is the total effective focal length of the endoscope adapter lens when it is at the wide-angle end, f t is the total effective focal length of the endoscope adapter lens when it is at the telephoto end, Z2 is the distance the second lens group moves on the optical axis, and Z3 is the distance the third lens group moves on the optical axis.

9. The endoscope adapter lens according to claim 1 or 2, characterized in that: The endoscope adapter lens satisfies any one of the following conditional expressions: 0.35≤S / f1≤0.53, 0.18≤EPD / f1≤0.20, -1.90≤L7_R1 / L7_R2≤-0.70, 2.40≤Vd6 / Vd5≤2.81, 2.50≤Vd12 / Vd11≤3.20, 2.40≤Vd12 / Vd13≤3.18, Among them, S is the entrance pupil distance of the endoscope adapter lens, f1 is the effective focal length of the first lens group, EPD is the entrance pupil diameter of the endoscope adapter lens, L7_R1 is the curvature radius of the object side of the seventh lens, L7_R2 is the curvature radius of the image side of the seventh lens, Vd5 is the Abbe number of the fifth lens, Vd6 is the Abbe number of the sixth lens, 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.

10. The endoscope adapter lens according to claim 1 or 2, characterized in that: The endoscope adapter lens also includes a positioning surface disposed on the object side of the first lens; The endoscope adapter lens satisfies: 0.21≤BFL / TTL≤0.26, 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 positioning surface to the imaging surface of the endoscope adapter lens.

Images