Eyepiece group, optical imaging system and endoscope

Abstract

The utility model relates to an eyepiece group, an optical imaging system and an endoscope. The eyepiece group sequentially comprises a fourteenth lens with positive focal power from the object side to the image side along the optical axis, and a fourteenth lens with positive focal power, wherein the image side surface of the fourteenth lens is a convex surface; the fifteenth lens has negative focal power, and the object side surface and the image side surface of the fifteenth lens are concave surfaces; the sixteenth lens has positive focal power, and the object side surface and the image side surface of the sixteenth lens are convex surfaces; the seventeenth lens has negative focal power, and the object side surface and the image side surface of the seventeenth lens are concave surfaces; the eighteenth lens has positive focal power, and the object side surface and the image side surface of the eighteenth lens are convex surfaces; the fourteenth lens, the fifteenth lens, the sixteenth lens, the seventeenth lens and the eighteenth lens are sequentially glued. By using the eyepiece group and the optical imaging system, various aberrations such as distortion and chromatic aberration can be inhibited, so that the imaging resolution and the imaging quality of the endoscope can be improved.

Description

Technical Field

[0001] This application relates to the field of endoscope technology, and in particular to an eyepiece assembly, an optical imaging system, and an endoscope. Background Technology

[0002] An endoscope is a medical device that can enter a patient's body for diagnosis or treatment, including various types of endoscopes such as laparoscopes. Laparoscopic endoscopes typically include an optical imaging system and mechanical structures to support it. The optical imaging system usually consists of an objective lens group, a rod lens group, and an eyepiece group. Light collected by the objective lens group is transmitted through the rod lens group to the eyepiece group and then projected onto an image sensor to form an image. However, current laparoscopic endoscopes have poor imaging performance, especially for ultra-high-definition (4K) imaging, which is prone to distortion and chromatic aberration, affecting the comprehensiveness and accuracy of diagnosis and treatment. Utility Model Content

[0003] Therefore, it is necessary to provide an eyepiece assembly, an optical imaging system, and an endoscope to address the problem of poor imaging performance of current laparoscopic endoscopes.

[0004] An eyepiece assembly, comprising, along the optical axis from the object side to the image side, the following components:

[0005] A fourteenth lens with positive optical power, wherein the image-side surface of the fourteenth lens is convex;

[0006] A fifteenth lens with negative optical power, wherein both the object-side and image-side surfaces of the fifteenth lens are concave.

[0007] A sixteenth lens with positive optical power, wherein both the object-side and image-side surfaces of the sixteenth lens are convex.

[0008] A seventeenth lens with negative optical power, wherein both the object-side and image-side surfaces of the seventeenth lens are concave.

[0009] An eighteenth lens with positive optical power, wherein both the object-side surface and the image-side surface of the eighteenth lens are convex.

[0010] The fourteenth lens, the fifteenth lens, the sixteenth lens, the seventeenth lens, and the eighteenth lens are sequentially glued together.

[0011] The aforementioned eyepiece assembly features a rationally configured array of lenses in terms of optical power and surface shape. Combined with the sequential cementing design of these lenses, it allows for smooth light transitions and effectively suppresses various aberrations such as distortion and chromatic aberration. This enhances the imaging resolution and quality of the eyepiece assembly, meeting the comprehensiveness and accuracy requirements of diagnosis and treatment. Furthermore, it helps reduce the aberration sensitivity and tolerance sensitivity of each lens, thereby improving the molding and assembly yield of each lens.

[0012] In one embodiment, the eyepiece assembly satisfies the following condition:

[0013] f(B04)≤16.68mm;

[0014] 0.6 ≤ f(B04) / CT4 ≤ 0.9;

[0015] Where f(B04) is the focal length of the eyepiece group, and CT4 is the thickness of the eyepiece group on the optical axis;

[0016] And / or, the Abbe number of the fifteenth lens is greater than the Abbe numbers of the fourteenth and sixteenth lenses, and the Abbe number of the seventeenth lens is less than the Abbe numbers of the sixteenth and eighteenth lenses.

[0017] An optical imaging system includes, in sequence along the optical axis from the object side to the image side, an objective lens group, a rod lens group, and an eyepiece group as described in any of the above embodiments. The objective lens group includes multiple lenses with optical power, and the rod lens group is used to transmit the light collected by the objective lens group to the eyepiece group.

[0018] In one embodiment, the objective lens group includes a first cemented lens group and a second cemented lens group disposed on the image side of the first cemented lens group. The first cemented lens group includes, along the optical axis from the object side to the image side, a first lens with negative optical power, a second lens with negative optical power, a fourth lens with positive optical power, and a fifth lens with positive optical power. The second cemented lens group includes, along the optical axis from the object side to the image side, a sixth lens with positive optical power, a seventh lens with negative optical power, an eighth lens with positive optical power, a ninth lens with negative optical power, a tenth lens with positive optical power, and an eleventh lens with negative optical power.

[0019] In one embodiment, the object-side surface of the first lens is convex and the image-side surface is concave; the image-side surface of the second lens is concave; the image-side surface of the fourth lens is convex; the object-side surface of the fifth lens is concave and the image-side surface is convex; both the object-side and image-side surfaces of the sixth lens are convex; both the object-side and image-side surfaces of the seventh lens are concave; both the object-side and image-side surfaces of the eighth lens are convex; both the object-side and image-side surfaces of the ninth lens are concave; both the object-side and image-side surfaces of the tenth lens are convex; and the object-side and image-side surfaces of the eleventh lens are concave and the image-side surface is convex.

[0020] In one embodiment, the optical imaging system satisfies the following condition:

[0021] 2.73mm≤f(B01)≤3.71mm;

[0022] 26.54mm≤f(B02)≤35.9mm;

[0023] 0.87≤f(B02) / CT2≤1.18;

[0024] 0.43mm≤D≤0.6mm;

[0025] 2.1mm≤f(object)≤3.1mm;

[0026] Where f(B01) is the focal length of the first cemented lens group, f(B02) is the focal length of the second cemented lens group, CT2 is the thickness of the second cemented lens group on the optical axis, D is the entrance pupil diameter of the optical imaging system, and f(object) is the focal length of the objective lens group.

[0027] In one embodiment, the Abbe number of the seventh lens is less than the Abbe numbers of the sixth and eighth lenses, the Abbe numbers of the ninth and eleventh lenses are less than the Abbe number of the eighth lens, and the Abbe number of the tenth lens is less than the Abbe numbers of the ninth and eleventh lenses; and / or,

[0028] The first cemented lens assembly further includes a third deflecting prism located along the optical axis between the second lens and the fourth lens, the third deflecting prism being used to deflect the optical path; the objective lens assembly further includes an aperture stop disposed between the third deflecting prism and the fourth lens; and / or,

[0029] The object-side and image-side surfaces of the first lens are aspherical.

[0030] In one embodiment, the rod lens group includes a plurality of transmission lens groups arranged at intervals along the optical axis. The transmission lens group includes a third cemented lens group and a symmetrical lens group disposed on the image side of the third cemented lens group. The symmetrical lens group and the third cemented lens group are mirror-symmetrical about a plane perpendicular to the optical axis. The third cemented lens group includes a twelfth lens with positive optical power and a thirteenth lens disposed on the image side of the twelfth lens with negative optical power. The object-side and image-side surfaces of the twelfth lens are both convex, and the object-side surface of the thirteenth lens is concave and the image-side surface is convex.

[0031] In one embodiment, the optical imaging system satisfies the following condition:

[0032] 24.2mm≤f(B03)≤32.74mm;

[0033] 0.66≤f(B03) / CT3≤0.9;

[0034] 1mm≤T3≤10mm;

[0035] 1mm≤T4≤16mm;

[0036] Where f(B03) is the focal length of the third cemented lens group, CT3 is the thickness of the third cemented lens group on the optical axis, T3 is the air gap on the optical axis between the third cemented lens group and the symmetrical lens group in any of the transmission lens groups, and T4 is the air gap on the optical axis between two adjacent transmission lens groups.

[0037] An endoscope comprising an optical imaging system as described in any of the above embodiments. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the structure of an optical imaging system in some embodiments.

[0039] Figure 2 This is a schematic diagram of the objective lens assembly in some embodiments.

[0040] Figure 3 This is a schematic diagram of the structure of some components of the rod lens assembly in some embodiments.

[0041] Figure 4 This is a schematic diagram of the eyepiece assembly in some embodiments.

[0042] Figure 5 This is a modulation transfer function (MTF) curve of an optical imaging system in some embodiments.

[0043] Figure 6 This is a relative illumination diagram of the optical imaging system in some embodiments.

[0044] Figure 7 The diagram shows the field curvature and distortion curves of the optical imaging system in some embodiments.

[0045] Figure 8 This is a diagram showing the light spot pattern of an optical imaging system in some embodiments.

[0046] Figure 9 This is a graph showing the lateral color difference of an optical imaging system in some embodiments.

[0047] Figure label:

[0048] 100. Optical imaging system; 110. Objective lens group; 111. First cemented lens group; 1. First lens; 2. Second lens; 3. Third deflecting prism; 4. Fourth lens; 5. Fifth lens; 112. Second cemented lens group; 6. Sixth lens; 7. Seventh lens; 8. Eighth lens; 9. Ninth lens; 10. Tenth lens; 11. Eleventh lens; 120. Rod lens group; 121. Third cemented lens group; 12. Twelfth lens; 13. Thirteenth lens; 122. Symmetrical lens group; 130. Eyepiece group; 14. Fourteenth lens; 15. Fifteenth lens; 16. Sixteenth lens; 17. Seventeenth lens; 18. Eighteenth lens; 19. First protective element; 20. Second protective element. Detailed Implementation

[0049] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0050] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0051] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0052] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0053] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0054] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0055] Please see Figure 1 , Figure 1 The diagram illustrates the structure of an optical imaging system 100 in some embodiments of this application. The optical imaging system 100 provided in this application can be used in medical devices, such as in any suitable endoscope, including a laparoscope. When the insertion part of the endoscope is inserted into the patient's body, the optical imaging system 100 can acquire images of the lesion area to facilitate diagnosis or treatment by the doctor. The endoscope may also include a housing, within which the optical imaging system 100 is housed. The housing can be understood as a support structure for the optical imaging system 100. Figure 2 , Figure 3 and Figure 4As shown, in some embodiments, the optical imaging system 100 includes an objective lens group 110, a rod lens group 120, and an eyepiece group 130 along the optical axis from the object side to the image side. The objective lens group 110 is used to collect and adjust light, the rod lens group 120 is used to transmit the light collected by the objective lens group 110 to the eyepiece group 130, and the eyepiece group 130 can transmit the adjusted light to the imaging surface.

[0056] Furthermore, combined Figure 1 and Figure 2 As shown, in some embodiments, the objective lens group 110 includes a first cemented lens group 111 and a second cemented lens group 112 disposed on the image side of the first cemented lens group 111. The first cemented lens group 111 includes, along the optical axis from the object side to the image side, a first lens 1 with negative optical power, a second lens 2 with negative optical power, a fourth lens 4 with positive optical power, and a fifth lens 5 with positive optical power. The first lens 1, the second lens 2, the fourth lens 4, and the fifth lens 5 are cemented together in sequence. The second cemented lens group 112 includes, along the optical axis from the object side to the image side, a sixth lens 6 with positive optical power, a seventh lens 7 with negative optical power, an eighth lens 8 with positive optical power, a ninth lens 9 with negative optical power, a tenth lens 10 with positive optical power, and an eleventh lens 11 with negative optical power. The sixth lens 6, the seventh lens 7, the eighth lens 8, the ninth lens 9, the tenth lens 10, and the eleventh lens 11 are cemented together in sequence.

[0057] In some embodiments, the object-side surface of the first lens 1 is convex and the image-side surface is concave; the image-side surface of the second lens 2 is concave; the image-side surface of the fourth lens 4 is convex; the object-side surface of the fifth lens 5 is concave and the image-side surface is convex; the object-side surface and the image-side surface of the sixth lens 6 are both convex; the object-side surface and the image-side surface of the seventh lens 7 are both concave; the object-side surface and the image-side surface of the eighth lens 8 are both convex; the object-side surface and the image-side surface of the ninth lens 9 are both concave; the object-side surface and the image-side surface of the tenth lens 10 are both convex; and the object-side surface of the eleventh lens 11 is concave and the image-side surface is convex.

[0058] The aforementioned objective lens group 110 features a rationally configured optical power for each lens. Combined with the cemented design of lenses 1 to 5 and lenses 6 to 11, this allows for a smooth transition of light within the objective lens group 110. This facilitates the correction of aberrations such as distortion and chromatic aberration, reduces the aberration sensitivity and tolerance sensitivity of each lens within the objective lens group 110, and thus improves the imaging resolution and image quality of the objective lens group 110. When applied to endoscopes, this enhances the comprehensiveness and accuracy of diagnosis and treatment, while also improving the forming and assembly yield of each lens. The two sets of cemented prisms also contribute to the compactness of the objective lens group 110 structure and help reduce its axial dimensions.

[0059] Specifically, the negative optical power and surface design of the first lens 1 and the second lens 2 work together to bend and converge large-angle incident light rays, which helps to reduce the effective light transmission diameter of the lenses. This facilitates the design of a small endoscope head, reduces the risk of injury to the patient, and also helps to suppress large-angle distortion and other aberrations, improving the imaging quality of the objective lens group 110. Furthermore, it helps to reduce the burden on the refracted light rays of the image-side lenses of the second lens 2, thereby reducing the aberration sensitivity and tolerance sensitivity of the objective lens group 110, reducing the surface complexity of each lens, and improving the molding yield of each lens. The combined optical power and surface design of the image-side lenses of the second lens 2 also helps to smoothly transition light rays, correct various aberrations such as distortion and chromatic aberration, reduce aberration sensitivity, and improve imaging quality.

[0060] In some embodiments, the first cemented lens assembly 111 further includes a third deflecting prism 3 located along the optical axis between the second lens 2 and the fourth lens 4, with its two sides cemented to the second lens 2 and the fourth lens 4, respectively. The third deflecting prism 3 is used to deflect the light path, allowing the light collected by the first lens 1 and the second lens 2 to be deflected at a certain angle before reaching the lenses on the image side. This helps to expand the viewing angle of the objective lens assembly 110 to accommodate different shooting angles. It should be noted that... Figure 1 and Figure 2 In this design, the third deflecting prism 3 is represented by an equivalent flat glass plate. In reality, the third deflecting prism 3 can be composed of one or more prisms. The third deflecting prism 3 can deflect light through one or more reflections. The deflection angle of the third deflecting prism 3 includes, but is not limited to, 0°, 30°, and 70°, so that the objective lens group 110 can have a corresponding viewing angle. When the viewing angle of the objective lens group 110 is 0°, the third deflecting prism 3 can be made of flat glass.

[0061] In some embodiments, the object side of the second lens 2 is a plane, the object side of the fourth lens 4 is a plane, and the object side of the fourth lens 4 can be attached and glued to the image side of the third deflecting prism 3. This is beneficial to the support, positioning and fixing design of the lenses in the objective lens group 110, and helps to improve the assembly yield and structural reliability of the objective lens group 110.

[0062] In some embodiments, the objective lens group 110 further includes an aperture stop, which is disposed between the third deflecting prism 3 and the fourth lens 4, for example, on the image-side surface of the third deflecting prism 3. The front-positioned aperture stop design allows for reasonable control of light path in conjunction with the optical power and surface design of each lens, which helps to reduce the aperture of the optical imaging system 100, improves the structural compactness of the optical imaging system 100, and thus helps to reduce the maximum insertion width of the endoscope when the optical imaging system 100 is applied to an endoscope, reducing the harm to the patient caused by the endoscope.

[0063] In some embodiments, both the object-side and image-side surfaces of the first lens 1 are aspherical. Using an aspherical lens as the first lens 1 provides greater design flexibility in the direction perpendicular to the axial direction, allowing it to adapt to different field of view angles, effectively suppressing aberrations such as distortion at large angles, improving the imaging quality of the objective lens group 110, and meeting the doctor's requirements for image realism. In some embodiments, the object-side and image-side surfaces of the other lenses in the optical imaging system 100 besides the first lens 1 can be spherical. This helps reduce the design and molding difficulty of each lens and also helps to compress the radial dimensions of the optical imaging system 100.

[0064] In some embodiments, the Abbe number of the seventh lens 7 is less than that of the sixth lens 6 and the eighth lens 8, the Abbe number of the ninth lens 9 and the eleventh lens 11 is less than that of the eighth lens 8, and the Abbe number of the tenth lens 10 is less than that of the ninth lens 9 and the eleventh lens 11. By matching the Abbe numbers of each lens in the second cemented lens group 112 with the optical power and surface shape design of each lens in the second cemented lens group 112, it is beneficial to improve the correction effect of chromatic aberration, thereby improving the imaging quality of the objective lens group 110. In some embodiments, the Abbe number of the sixth lens 6 is 58, the Abbe number of the seventh lens 7 is 24, the Abbe number of the eighth lens 8 is 51, the Abbe number of the ninth lens 9 is 36, the Abbe number of the tenth lens 10 is 28, and the Abbe number of the eleventh lens 11 is 31.

[0065] In some embodiments, the objective lens group 110 satisfies the condition: 2.73mm ≤ f(B01) ≤ 3.71mm, where f(B01) is the focal length of the first cemented lens group 111. When the above condition is satisfied, the focal length of the first cemented lens group 111 can be rationally configured. Combined with the optical power and surface design of each lens in the first cemented lens group 111, the first cemented lens group 111 can effectively collect light while allowing for a smooth transition of light, thereby suppressing aberrations such as distortion. Simultaneously, it helps reduce the burden on the second cemented lens group 112 in deflecting light, which in turn helps reduce the aberration sensitivity and tolerance sensitivity of each lens in the second cemented lens group 112, improving the imaging quality of the objective lens group 110. Furthermore, it helps reduce the surface complexity of each lens, improving the molding yield of each lens.

[0066] In some embodiments, the objective lens group 110 satisfies the following conditions: 26.54mm ≤ f(BO2) ≤ 35.9mm; 0.87 ≤ f(BO2) / CT2 ≤ 1.18; where f(BO2) is the focal length of the second cemented lens group 112, and CT2 is the thickness of the second cemented lens group 112 on the optical axis, i.e., the distance on the optical axis from the object side of the sixth lens 6 to the image side of the eleventh lens 11. Satisfying the above conditions allows for a reasonable configuration of the focal length of the second cemented lens group 112 and the ratio of the focal length to the center thickness of the second cemented lens group 112. Combined with the optical power and surface design of each lens in the second cemented lens group 112, this facilitates a smooth transition of the light collected by the first cemented lens group 111 into the second cemented lens group 112, suppressing the generation of aberrations such as distortion and chromatic aberration, thereby improving the imaging quality of the objective lens group 110. It also helps to reduce the axial dimensions of the objective lens group 110, which is beneficial for the miniaturization design of the endoscope.

[0067] Combination Figure 1 and Figure 3 As shown, in some embodiments, the rod lens group 120 includes a plurality of transmission lens groups arranged sequentially at intervals along the optical axis. The number of transmission lens groups is odd; for example, the rod lens group 120 may include three transmission lens groups. Each transmission lens group includes a third cemented lens group 121 and a symmetrical lens group 122 disposed on the image side of the third cemented lens group 121. The symmetrical lens group 122 and the third cemented lens group 121 are mirror-symmetrically arranged about a plane perpendicular to the optical axis. Figure 1 and Figure 3 The diagram only illustrates one of the third cemented lens group 121 and one of the symmetrical lens groups 122 within the rod lens assembly 120. The symmetrical third cemented lens group 121 and symmetrical lens group 122 within the rod lens assembly 120 ensure that the magnification of the rod lens assembly 120 is -1, achieving proportional image transmission. Simultaneously, it ensures that the magnitudes of transverse aberrations such as chromatic aberration, coma, and distortion in the third cemented lens group 121 and the symmetrical lens group 122 are equal, with opposite signs, thus canceling each other out. This helps reduce aberrations introduced by the rod lens assembly 120 during image transmission, improving the imaging quality of the optical imaging system 100. The proper configuration of the rod lens assembly 120 also helps control the effective aperture size of the optical imaging system 100 and the maximum insertion width of the endoscope. This ensures sufficient light intake for the optical imaging system 100 while minimizing the maximum insertion width of the endoscope, for example, making it less than or equal to 10 mm, reducing harm to the patient.

[0068] In some embodiments, the third cemented lens group 121 includes a twelfth lens 12 with positive optical power and a thirteenth lens 13 disposed on the image side of the twelfth lens 12 with negative optical power. The object side and image side of the twelfth lens 12 are both convex, while the object side of the thirteenth lens 13 is concave and the image side is convex. By rationally configuring the optical power and surface shape of each lens in the rod lens group 120, the lenses in the third cemented lens group 121 and the symmetrical lens group 122 have a reasonable positive and negative pairing, which helps to reduce the Petzval sum and spherical aberration, while improving the light energy transmission efficiency of the rod lens group 120, thereby improving the imaging quality and imaging brightness of the optical imaging system 100.

[0069] Combination Figure 1 and Figure 4 As shown, in some embodiments, the eyepiece group 130 includes, along the optical axis from the object side to the image side, a fourteenth lens 14 with positive optical power, a fifteenth lens 15 with negative optical power, a sixteenth lens 16 with positive optical power, a seventeenth lens 17 with negative optical power, and an eighteenth lens 18 with positive optical power. The image-side surface of the fourteenth lens 14 is concave, the object-side and image-side surfaces of the fifteenth lens 15 are both concave, the object-side and image-side surfaces of the sixteenth lens 16 are both convex, the object-side and image-side surfaces of the seventeenth lens 17 are both concave, and the object-side and image-side surfaces of the eighteenth lens 18 are both convex. The fourteenth lens 14, fifteenth lens 15, sixteenth lens 16, seventeenth lens 17, and eighteenth lens 18 are sequentially cemented together.

[0070] The aforementioned eyepiece group 130 features a rationally configured array of optical power and surface shape for each lens. Combined with the sequential cementing design of the lenses, this allows for a smooth transition of light, effectively suppressing aberrations such as distortion and chromatic aberration. This enhances the imaging resolution and quality of the eyepiece group 130, meeting the comprehensive and accurate requirements of diagnosis and treatment. It also helps reduce the aberration sensitivity and tolerance sensitivity of each lens, improving the forming and assembly yield of each lens. Specifically, the positive optical power of the fourteenth lens 14, combined with its convex image-side surface, effectively converges light from the objective lens group 110. This reduces the burden on the refracted light rays from the image-side lenses of the fourteenth lens 14, further reducing the aberration sensitivity and tolerance sensitivity of the eyepiece group 130, suppressing spherical aberration, and improving the forming yield and imaging quality of each lens. The negative optical power and biconcave shape of the fifteenth lens 15, in conjunction with the fourteenth lens 14, can adjust the optical power distribution and control the light path, resulting in a smooth light transition and facilitating the correction of aberrations such as astigmatism. The positive optical power and biconvex shape of the sixteenth and eighteenth lenses 16, combined with the optical power and surface design of the fifteenth and seventeenth lenses 17, through a reasonable combination of positive and negative optical power, can balance the optical power distribution throughout the eyepiece group 130, rationally control the light path at various points, and prevent excessive convergence or divergence of light, thus helping to suppress aberrations such as astigmatism and coma and improving the imaging quality of the eyepiece group 130.

[0071] Meanwhile, through the rational configuration of the optical power and surface shape of each lens in the objective lens group 110 and the eyepiece group 130, the objective lens group 110 exhibits negative distortion, while the eyepiece group 130 exhibits positive distortion. The positive distortion of the eyepiece group 130 can cancel out the negative distortion of the objective lens group 110, which helps to suppress the distortion of the optical imaging system 100, for example, controlling the distortion of the optical imaging system 100 to around -3.2%, thereby improving the imaging quality of the optical imaging system 100. The rational combination of the objective lens group 110, the eyepiece group 130, and the rod lens group 120 enables the optical imaging system 100 to achieve good correction of aberrations in the visible light band of 435nm-656nm, meeting the high-definition imaging requirements of a 1 / 1.8-inch image sensor. In some embodiments, the object-side surface of the fourteenth lens 14 can be flat, which is beneficial for lens positioning, support, and assembly.

[0072] In some embodiments, the Abbe number of the fifteenth lens 15 is greater than that of the fourteenth lens 14 and the sixteenth lens 16, the Abbe number of the seventeenth lens 17 is less than that of the sixteenth lens 16 and the eighteenth lens 18, and the Abbe number of the sixteenth lens 16 is greater than that of the fourteenth lens 14 and the eighteenth lens 18. By designing the combination of Abbe numbers of the lenses in the eyepiece group 130, along with the cementing design of the lenses and the design of the optical power and surface shape, the eyepiece group 130's ability to correct chromatic aberration is improved, thereby enhancing the imaging quality of the optical imaging system 100. In some embodiments, the Abbe number of the fourteenth lens 14 is 39, the Abbe number of the fifteenth lens 15 is 64, the Abbe number of the sixteenth lens 16 is 47, the Abbe number of the seventeenth lens 17 is 24, and the Abbe number of the eighteenth lens 18 is 31.

[0073] In some embodiments, the optical imaging system 100 satisfies the following conditions: f(B04) ≤ 16.68 mm; 0.6 ≤ f(B04) / CT4 ≤ 0.9; where f(B04) is the focal length of the eyepiece group 130, and CT4 is the thickness of the eyepiece group 130 on the optical axis, i.e., the distance on the optical axis from the object side of the fourteenth lens 14 to the image side of the eighteenth lens 18. Satisfying the above conditions, combined with the reasonable configuration of the optical power and surface shape of each lens in the eyepiece group 130, allows the eyepiece group 130 to smoothly transition the light collected by the objective lens group 110, suppressing the generation of various aberrations such as distortion and chromatic aberration. This is beneficial for improving the imaging quality of the optical imaging system 100, and also helps to reduce the axial dimension of the eyepiece group 130, which is beneficial for the miniaturization design of the endoscope.

[0074] In some embodiments, the optical imaging system 100 satisfies the following conditions: 24.2mm≤f(B03)≤32.74mm; 0.66≤f(B03) / CT3≤0.9; 1mm≤T3≤10mm; 1mm≤T4≤16mm; where f(B03) is the focal length of the third cemented lens group 121, CT3 is the thickness of the third cemented lens group 121 on the optical axis, that is, the distance on the optical axis from the object side of the twelfth lens 12 to the image side of the thirteenth lens 13 in any third cemented lens group 121, T3 is the air gap on the optical axis between the third cemented lens group 121 and the symmetric lens group 122 in any transmission lens group, and T4 is the air gap on the optical axis between two adjacent transmission lens groups. When the above conditions are met, the focal length, thickness and spacing of the third cemented lens group 121 and the symmetrical lens group 122 can be reasonably configured, so that the rod lens group 120 can smoothly transmit light and suppress the aberrations introduced by the rod lens group 120 during image transmission, thereby improving the imaging quality of the optical imaging system 100. At the same time, it is also beneficial to compress the axial dimension of the rod lens group 120.

[0075] Please see again. Figure 1In some embodiments, the optical imaging system 100 further includes a first protective element 19 disposed on the object side of the first lens 1 and a second protective element 20 disposed on the image side of the eighteenth lens 18. The first protective element 19 and the second protective element 20 are both, but not limited to, flat glass. The first protective element 19 and the second protective element 20 can provide structural protection for the lenses in the objective lens group 110 and the eyepiece group 130.

[0076] In some embodiments, the entrance pupil diameter D of the optical imaging system 100 is 0.43mm-0.6mm, enabling the optical imaging system 100 to have sufficient light intake to meet the requirements of high-quality imaging, such as achieving a full-field contrast ratio greater than 0.29 when the resolution is 70 lp / mm. In some embodiments, the focal length f(object) of the objective lens group 110 is 2.1mm-3.1mm, which, combined with the design of the entrance pupil diameter, can effectively improve the depth of field range of the optical imaging system 100, for example, increasing the depth of field range of the optical imaging system 100 to 10mm-∞ (infinity), enabling clear imaging of a wider range of subjects and improving the comprehensiveness of diagnosis and treatment.

[0077] In some embodiments, the focal length of the eyepiece group 130 is less than or equal to 16.68 mm, which works well with the objective lens group 110 to achieve full-screen imaging with a 1 / 1.8-inch image sensor, thus improving the imaging quality of the optical imaging system 100. In some embodiments, the optical working distance of the optical imaging system 100 is 40 mm, the working length is 315 mm-325 mm, and the field of view is greater than 80°, which helps to increase the shooting range of the optical imaging system 100 and also helps to improve the comprehensiveness of diagnosis and treatment.

[0078] Please see Figures 5-9 As shown, Figure 5 This is a modulation transfer function (MTF) plot of the optical imaging system 100 in some embodiments. Figure 6 This is a relative illumination map of the optical imaging system 100 in some embodiments. Figure 7 Here are field curvature and distortion curves of the optical imaging system 100 in some embodiments. Figure 8 Here are some examples of light spot patterns from the optical imaging system 100 in certain embodiments. Figure 9 This is a graph showing the lateral color difference of the optical imaging system 100 in some embodiments. Figures 5-9As can be seen, under visible light (0.435um-0.656um), when the resolution meets 70lp / mm, the MTF value of the optical imaging system 100 is greater than 0.29 and close to the diffraction limit; the relative illumination of the edge field of view is greater than 90%, and there is no vignetting; the distortion is controlled within -3.3%, and the deformation of the image and the actual scene is small; the diffuse spots in the dot plot are all smaller than the Airy disk, and the spot diameters are all contained within the Airy disk, which is basically at the diffraction limit; the short-wavelength and long-wavelength chromatic aberrations are converged and concentrated, and the optical imaging system 100 has good imaging quality and imaging brightness.

[0079] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0080] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. An eyepiece assembly, characterized in that, Along the optical axis from the object side to the image side, the following are included in sequence: A fourteenth lens with positive optical power, wherein the image-side surface of the fourteenth lens is convex; A fifteenth lens with negative optical power, wherein both the object-side and image-side surfaces of the fifteenth lens are concave. A sixteenth lens with positive optical power, wherein both the object-side and image-side surfaces of the sixteenth lens are convex. A seventeenth lens with negative optical power, wherein both the object-side and image-side surfaces of the seventeenth lens are concave. An eighteenth lens with positive optical power, wherein both the object-side surface and the image-side surface of the eighteenth lens are convex. The fourteenth lens, the fifteenth lens, the sixteenth lens, the seventeenth lens, and the eighteenth lens are sequentially glued together.

2. The eyepiece assembly according to claim 1, characterized in that, The eyepiece assembly satisfies the following condition: f(B04)≤16.68mm; 0.6 ≤ f(B04) / CT4 ≤ 0.9; Where f(B04) is the focal length of the eyepiece group, and CT4 is the thickness of the eyepiece group on the optical axis; And / or, the Abbe number of the fifteenth lens is greater than the Abbe numbers of the fourteenth and sixteenth lenses, and the Abbe number of the seventeenth lens is less than the Abbe numbers of the sixteenth and eighteenth lenses.

3. An optical imaging system, characterized in that, Along the optical axis from the object side to the image side, it includes an objective lens group, a rod lens group, and an eyepiece group as described in claim 1 or 2. The objective lens group includes multiple lenses with optical power, and the rod lens group is used to transmit the light collected by the objective lens group to the eyepiece group.

4. The optical imaging system according to claim 3, characterized in that, The objective lens group includes a first cemented lens group and a second cemented lens group disposed on the image side of the first cemented lens group. The first cemented lens group includes, along the optical axis from the object side to the image side, a first lens with negative optical power, a second lens with negative optical power, a fourth lens with positive optical power, and a fifth lens with positive optical power. The second cemented lens group includes, along the optical axis from the object side to the image side, a sixth lens with positive optical power, a seventh lens with negative optical power, an eighth lens with positive optical power, a ninth lens with negative optical power, a tenth lens with positive optical power, and an eleventh lens with negative optical power.

5. The optical imaging system according to claim 4, characterized in that, The first lens has a convex object-side surface and a concave image-side surface; the second lens has a concave image-side surface; the fourth lens has a convex image-side surface; the fifth lens has a concave object-side surface and a convex image-side surface; the sixth lens has both a convex object-side surface and an convex image-side surface; the seventh lens has both a concave object-side surface and an convex image-side surface; the eighth lens has both a convex object-side surface and an convex image-side surface; the ninth lens has both a concave object-side surface and an convex image-side surface; the tenth lens has both a convex object-side surface and an eleventh lens has a concave object-side surface and a convex image-side surface.

6. The optical imaging system according to claim 4, characterized in that, The optical imaging system satisfies the following condition: 2.73mm≤f(B01)≤3.71mm; 26.54mm≤f(B02)≤35.9mm; 0.87≤f(B02) / CT2≤1.18; 0.43mm≤D≤0.6mm; 2.1mm≤f(object)≤3.1mm; Where f(B01) is the focal length of the first cemented lens group, f(B02) is the focal length of the second cemented lens group, CT2 is the thickness of the second cemented lens group on the optical axis, D is the entrance pupil diameter of the optical imaging system, and f(object) is the focal length of the objective lens group.

7. The optical imaging system according to claim 4, characterized in that, The Abbe number of the seventh lens is less than that of the sixth and eighth lenses; the Abbe numbers of the ninth and eleventh lenses are less than that of the eighth lens; and the Abbe number of the tenth lens is less than that of the ninth and eleventh lenses; and / or, The first cemented lens assembly further includes a third deflecting prism located along the optical axis between the second lens and the fourth lens, the third deflecting prism being used to deflect the optical path; the objective lens assembly further includes an aperture stop disposed between the third deflecting prism and the fourth lens; and / or, The object-side and image-side surfaces of the first lens are aspherical.

8. The optical imaging system according to claim 3, characterized in that, The rod lens group includes a plurality of transmission lens groups arranged at intervals along the optical axis. The transmission lens group includes a third cemented lens group and a symmetrical lens group disposed on the image side of the third cemented lens group. The symmetrical lens group and the third cemented lens group are mirror-symmetrical about a plane perpendicular to the optical axis. The third cemented lens group includes a twelfth lens with positive optical power and a thirteenth lens disposed on the image side of the twelfth lens with negative optical power. The object-side and image-side surfaces of the twelfth lens are both convex, and the object-side surface of the thirteenth lens is concave and the image-side surface is convex.

9. The optical imaging system according to claim 8, characterized in that, The optical imaging system satisfies the following condition: 24.2mm≤f(B03)≤32.74mm; 0.66≤f(B03) / CT3≤0.9; 1mm≤T3≤10mm; 1mm≤T4≤16mm; Where f(B03) is the focal length of the third cemented lens group, CT3 is the thickness of the third cemented lens group on the optical axis, T3 is the air gap on the optical axis between the third cemented lens group and the symmetrical lens group in any of the transmission lens groups, and T4 is the air gap on the optical axis between two adjacent transmission lens groups.

10. An endoscope, characterized in that, Includes the optical imaging system as described in any one of claims 3-9.

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