Eyepiece group, optical imaging system, and endoscope

Abstract

This application relates to an eyepiece assembly, an optical imaging system, and an endoscope. The eyepiece assembly includes a fifteenth lens with negative optical power, a sixteenth lens with positive optical power, a seventeenth lens with negative optical power, an eighteenth lens with positive optical power, a nineteenth lens with negative optical power, a twentieth lens with positive optical power, and a twenty-first lens with positive optical power. The image-side surface of the fifteenth lens is concave, the object-side surface of the sixteenth lens is convex, the image-side surface of the seventeenth lens is concave, both the object-side and image-side surfaces of the eighteenth lens are convex, and both the object-side and image-side surfaces of the nineteenth lens are concave. The above-described eyepiece assembly can provide good imaging quality for both visible light and fluorescence.

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] Fluorescent endoscopes, such as laparoscopic and thoracic-laparoscopic endoscopes, can be inserted into the human body through minimally invasive incisions for diagnosis and treatment. Fluorescent endoscopes can be used in conjunction with optical imaging systems to simultaneously focus visible and near-infrared light. By injecting fluorescent contrast agents such as indocyanine green (ICG) into the patient, they bind to plasma proteins. When illuminated with 780nm-810nm light, the fluorescent contrast agent is excited to emit near-infrared light at 820nm-840nm.

[0003] Optical imaging systems simultaneously acquire images of visible and near-infrared light, enabling doctors to distinguish between lesions and normal areas, thus improving surgical precision. However, due to the wavelength difference between visible light and fluorescence, traditional optical imaging systems used in fluorescein endoscopes struggle to simultaneously capture clear images of both, affecting the accuracy of diagnosis and treatment. Utility Model Content

[0004] Therefore, it is necessary to provide an eyepiece assembly, an optical imaging system, and an endoscope to address the problem that traditional optical imaging systems cannot simultaneously and clearly image visible light and fluorescence.

[0005] An eyepiece assembly, comprising, along the optical axis from the object side to the image side, a fifteenth lens with negative optical power, a sixteenth lens with positive optical power, a seventeenth lens with negative optical power, an eighteenth lens with positive optical power, a nineteenth lens with negative optical power, a twentieth lens with positive optical power, and a twenty-first lens with positive optical power.

[0006] The image-side surface of the fifteenth lens is concave, the object-side surface of the sixteenth lens is convex, the image-side surface of the seventeenth lens is concave, both the object-side and image-side surfaces of the eighteenth lens are convex, and both the object-side and image-side surfaces of the nineteenth lens are concave.

[0007] In the aforementioned eyepiece group, the negative optical power of the fifteenth lens and its concave surface shape on the image side work together to diverge light, enhancing the divergence of fluorescence and initially widening the angle between visible light and fluorescence, thus providing adjustment space for chromatic aberration compensation by the image-side lens. The positive optical power of the sixteenth lens and its convex surface shape on the object side partially counteract the excessive fluorescence divergence of the fifteenth lens, improving the brightness uniformity of visible light and fluorescence in the central field of view. The negative optical power of the seventeenth lens and its concave surface shape on the image side correct the excessive fluorescence convergence of the sixteenth lens, bringing the intersection points of visible light and fluorescence closer together. The optical power and surface shape of the eighteenth lens help correct spherical aberration in visible light and fluorescence, and, in conjunction with the seventeenth lens, reduce the focal deviation between visible light and fluorescence. The optical power and surface shape design of the nineteenth lens compensate for the field curvature produced by the eighteenth lens, while simultaneously improving the relative illumination of visible light and fluorescence across the entire field of view. The optical power and surface shape of the twentieth and twenty-first lenses work together to further reduce chromatic aberration between visible light and fluorescence.

[0008] Therefore, the above-mentioned eyepiece group, through the rational design of the optical power and surface shape of each lens, can have good imaging quality for both visible light and fluorescence, meeting the imaging quality requirements of optical imaging systems. When applied to endoscopes, it is beneficial to improve the accuracy of diagnosis and treatment.

[0009] In one embodiment, the fifteenth lens, the sixteenth lens, the seventeenth lens, the eighteenth lens, the nineteenth lens, the twentieth lens, and the twenty-first lens are sequentially cemented together to form a fourth cemented lens group;

[0010] The eyepiece assembly satisfies the following condition:

[0011] f(B04)≤17.85mm;

[0012] 0.7 ≤ f(B04) / CT4 ≤ 0.9;

[0013] Where f(B04) is the focal length of the fourth cemented lens group, and CT4 is the thickness of the fourth cemented lens group on the optical axis.

[0014] In one embodiment,

[0015] The object-side surface of the fifteenth lens is convex.

[0016] The image-side surface of the sixteenth lens is convex.

[0017] The object-side surface of the seventeenth lens is concave;

[0018] The object-side surface of the twentieth lens is convex, and the image-side surface is concave.

[0019] The object-side and image-side surfaces of the 21st lens are both convex.

[0020] In one embodiment, the Abbe number of the fifteenth lens is greater than that of the sixteenth lens, the Abbe number of the seventeenth lens is less than that of the eighteenth lens, the Abbe number of the nineteenth lens is less than that of the twentieth lens, and the Abbe number of the twentieth lens is greater than that of the twenty-first lens.

[0021] An optical imaging system includes a rod lens group, an objective lens group, a field stop, and an eyepiece group as described in any of the above embodiments. The objective lens group, the rod lens group, the field stop, and the eyepiece group are arranged sequentially along the direction of light propagation. Both the rod lens group and the objective lens group include multiple lenses with optical power.

[0022] In one embodiment, the objective 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 third lens with positive optical power, a fourth lens with positive optical power, a fifth lens with positive optical power, a sixth lens with negative optical power, a seventh lens with positive optical power, an eighth lens with negative optical power, a ninth lens with negative optical power, a tenth lens with positive optical power, and an eleventh lens with negative optical power.

[0023] 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 third lens is convex; the object-side surface of the fourth lens is convex, and the image-side surface is concave; both the object-side and image-side surfaces of the fifth lens are convex; both the object-side and image-side surfaces of the sixth lens are concave; both the object-side and image-side surfaces of the seventh lens are convex; both the object-side and image-side surfaces of the eighth lens are concave, and the image-side surface of the ninth lens are concave; both the object-side and image-side surfaces of the tenth lens are convex; and both the object-side and image-side surfaces of the eleventh lens are concave, and the image-side surface of the eleventh lens is concave.

[0024] In one embodiment, the objective lens group further includes a steering element disposed between the second lens and the third lens, wherein the first lens, the second lens, the steering element and the third lens are sequentially cemented together to form a first cemented lens group, and the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens, the tenth lens and the eleventh lens are sequentially cemented together to form a second cemented lens group.

[0025] The objective lens assembly satisfies the following condition:

[0026] -18.45mm≤f(B01)≤-8.59mm;

[0027] 17.96mm≤f(B02)≤24.64mm;

[0028] 0.6 ≤ f(B02) / CT2 ≤ 0.8;

[0029] 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, and CT2 is the thickness of the second cemented lens group on the optical axis.

[0030] In one embodiment, the Abbe number of the fourth lens is greater than that of the fifth lens, the Abbe number of the sixth lens is less than that of the seventh lens, the Abbe number of the eighth lens is less than that of the ninth lens, and the Abbe number of the tenth lens is greater than that of the eleventh lens.

[0031] And / or,

[0032] The objective lens assembly satisfies the following condition:

[0033] 2.78mm ≤ f(object) ≤ 3.3mm;

[0034] Where f(object) is the focal length of the objective lens group;

[0035] And / or,

[0036] The optical imaging system further includes a steering element and an aperture stop. The steering element is disposed between the second lens and the fourth lens, and the aperture stop is disposed between the steering element and the third lens. The Abbe number of the first lens is greater than that of the second lens, and the Abbe number of the steering element is less than that of the third lens.

[0037] In one embodiment, the rod lens group includes multiple rod lenses arranged sequentially from the object side to the image side along the optical axis. The rod lenses include a third cemented lens group and a symmetrical cemented lens group, and the third cemented lens group and the symmetrical cemented lens group are mirror-symmetrical about a plane perpendicular to the optical axis.

[0038] The third cemented lens group includes a twelfth lens with positive optical power, a thirteenth lens with negative optical power, and a fourteenth lens with positive optical power. The object-side and image-side surfaces of the twelfth lens are both convex, the object-side and image-side surfaces of the thirteenth lens are both concave, and the object-side and image-side surfaces of the fourteenth lens are both convex.

[0039] The rod lens group satisfies the following condition:

[0040] 1mm≤T3≤4mm;

[0041] 1mm≤T4≤6mm;

[0042] 29mm≤f(B03)≤31mm;

[0043] Wherein, T3 is the distance on the optical axis between the third cemented lens group and the symmetrical cemented lens group in each group of rod lenses, T4 is the distance on the optical axis between two adjacent groups of rod lenses, and f(B03) is the focal length of the third cemented lens group.

[0044] An endoscope comprising an optical imaging system as described in any of the above embodiments. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the structure of an optical imaging system in some embodiments.

[0046] Figure 2 This is a schematic diagram of the objective lens assembly in some embodiments.

[0047] Figure 3 This is a schematic diagram of the rod lens assembly in some embodiments.

[0048] Figure 4 This is a schematic diagram of the eyepiece assembly in some embodiments.

[0049] Figure 5 This is a transfer function graph of the optical imaging system under visible light in some embodiments.

[0050] Figure 6 This is a defocusing curve of the optical imaging system at 40 lp / mm in visible light in some embodiments.

[0051] Figure 7 The graph shows the transfer function of the optical imaging system under fluorescence in some embodiments.

[0052] Figure 8 This is a defocusing curve of the optical imaging system at 40 lp / mm under fluorescence in some embodiments.

[0053] Figure 9 This is a relative illumination diagram of the optical imaging system in some embodiments.

[0054] Figure 10 The diagram shows the field curvature and distortion curves of the optical imaging system in some embodiments.

[0055] Figure 11 This is a diagram showing the light spot pattern of an optical imaging system in some embodiments. Detailed Implementation

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] Please see Figure 1 , Figure 1 The diagram illustrates the structure of an optical imaging system in some embodiments of this application. The optical imaging system provided in this application can be applied to medical devices, such as any suitable rigid endoscope like a fluorescence laparoscope or fluorescence thoracic and laparoscopic endoscope. The optical imaging system can acquire images of lesions to facilitate diagnosis or treatment by doctors.

[0063] In some embodiments, the optical imaging system includes an objective lens group, a rod lens group, and an eyepiece group arranged sequentially along the optical axis from the object side to the image side. The objective lens group is used to collect light, and the rod lens group is used to transmit the light collected by the objective lens group to the eyepiece group. The optical imaging system may also be equipped with an optical adapter. The eyepiece group is used to magnify the image and transmit it to the optical adapter, which can adjust the light and transmit it to the image sensor. The optical adapter can use any suitable adapter lens, which is not limited in this application.

[0064] Furthermore, combined Figure 1 and Figure 2As shown, in some embodiments, the objective lens group includes, sequentially from the object side to the image side, a first lens 2, a second lens 3, a third lens 5, a fourth lens 6, a fifth lens 7, a sixth lens 8, a seventh lens 9, an eighth lens 10, a ninth lens 11, a tenth lens 12, and an eleventh lens 13 along the optical axis. The first lens 2 has negative optical power, its object side is convex, and its image side is concave. The second lens 3 has negative optical power, the third lens 5 has positive optical power, and its image side is convex. The fourth lens 6 has positive optical power, the fifth lens 7 has positive optical power, the sixth lens 8 has negative optical power, and its image side is concave. The seventh lens 9 has positive optical power, the eighth lens 10 has negative optical power, the ninth lens 11 has negative optical power, and its image side is concave. The tenth lens 12 has positive optical power, and both its object side and image side are convex. The eleventh lens 13 has negative optical power.

[0065] The aforementioned objective lens group, with its negative optical power of the first lens 2 and the second lens 3, and the convex-concave surface of the first lens 2, effectively widens the angle of incidence and enhances the light-gathering ability at the edge of the field of view, thus meeting the visual field requirements of endoscopes. It also helps to compress the beam angle, reduce the aperture of the image-side lens, and suppress stray light generation. The dispersive characteristics of the negative optical power of the first lens 2 and the second lens 3 can also initially compensate for the focal shift of visible light and fluorescence, providing a good foundation for subsequent chromatic aberration correction. The positive optical power of the third lens 5, the fourth lens 6, and the fifth lens 7, combined, facilitates rapid light convergence, shortens the overall length of the objective lens group, and also helps to reduce spherical aberration and improve central resolution. The negative optical power of the sixth lens 8 and its concave surface of the image-side lens can compensate for the field curvature generated by the positive lens, balance the image plane flatness, and thus suppress the blurring of the edge of the field of view. It also helps to achieve stronger refraction of fluorescence, balancing the field curvature shift of fluorescence. The optical power and surface shape of the eighth lens 10, the ninth lens 11, the tenth lens 12 and the eleventh lens 13 are matched, which is beneficial to correct coma, improve asymmetric image quality, and improve edge trailing of fluorescence images. At the same time, it is beneficial to suppress astigmatism of the objective lens group and improve the coincidence of off-axis image points of fluorescence and visible light.

[0066] Therefore, the aforementioned objective lens assembly, through the rational design of the optical power and surface shape of each lens, can simultaneously produce clear images of visible light and fluorescence (such as near-infrared light in the 820nm-840nm band). When applied to optical imaging systems and endoscopes, it can effectively improve the accuracy of diagnosis and treatment.

[0067] In some embodiments, the image-side surface of the second lens 3 is concave. The optical power and surface design of the first lens 2 and the second lens 3 are coordinated to effectively control the initial direction of light rays, which helps to reduce the effective aperture of the lenses in the objective lens group, making the structure of the objective lens group more compact, and also helps to reduce axial aberrations such as spherical aberration. The object-side surface of the fourth lens 6 is convex, and the image-side surface is concave, which helps to balance coma and astigmatism and improve the uniformity of imaging across the entire field of view. The object-side surface and image-side surface of the fifth lens 7 are both convex, and the object-side surface of the sixth lens 8 is concave. The fifth lens 7 can effectively converge light rays and improve the imaging resolution of the objective lens group for the central field of view. The fifth lens 7 and the sixth lens 8 work together to reduce the Pitzvalve field curvature, balance the flatness of the image plane, and improve image quality. The seventh lens 9 has convex object-side and image-side surfaces, while the eighth lens 10 has a concave object-side surface and a convex image-side surface. The seventh lens 9 further converges light rays, improving the objective lens group's ability to resolve details. The combination of the seventh lens 9 and the eighth lens 10 helps correct spherical aberration and optimize the depth of field, enabling the optical imaging system to clearly image objects over a wider range of object distances. The ninth lens 11 has a concave object-side surface. The ninth lens 11, in conjunction with the tenth lens 12, further balances field curvature and astigmatism, improving the uniformity of image sharpness across the entire field of view. The eleventh lens 13 has a concave object-side surface and a convex image-side surface.

[0068] In some embodiments, the objective lens assembly further includes a first protective element 1 and a steering element 4. The first protective element 1 is, but is not limited to, a flat glass plate and is disposed on the object side of the first lens 2 to provide protection for each lens in the objective lens assembly. The steering element 4 is disposed between the second lens 3 and the third lens 5 and is, but is not limited to, a steering flat glass or a steering prism formed by cementing together multiple prisms. The steering element 4 is used to deflect the light path at a certain angle, including but not limited to 0°, 30°, 45°, 70°, etc., to adapt to the imaging angle of the endoscope.

[0069] In some embodiments, the object-side and image-side surfaces of the steering element 4 are planar, the object-side surface of the second lens 3 is planar, and the object-side surface of the third lens 5 is planar. The first lens 2, the second lens 3, the steering element 4, and the third lens 5 are sequentially cemented together to form a first cemented lens group. This not only improves the structural compactness of the objective lens group but also enhances the matching degree of the optical paths on the object-side and image-side of the steering element 4, ensuring good image quality. Furthermore, the arrangement of the first cemented lens group, combined with the optical power and surface design of each lens in the first cemented lens group, helps to counteract the focal shift of visible light and fluorescence, and reduces the axial chromatic aberration of visible light and fluorescence, thereby improving the imaging quality of the objective lens group for visible light and fluorescence.

[0070] In some embodiments, the Abbe number of the first lens 2 is greater than that of the second lens 3, and the Abbe number of the steering element 4 is less than that of the third lens 5. This allows for a reasonable combination of materials for each lens in the first cemented lens assembly and the steering element 4. Combined with the optical power and surface design of each lens in the first cemented lens assembly, this facilitates the mutual cancellation of chromatic aberration in visible light and fluorescence imaging through the dispersion characteristics of different materials, thereby improving the imaging quality of the fluorescence optical system for visible light and fluorescence. For example, in some embodiments, the Abbe number of the first lens 2 is 41, the Abbe number of the second lens 3 is 23.8, the Abbe number of the steering element 4 is 39, and the Abbe number of the third lens 5 is 64.

[0071] In some embodiments, the fourth lens 6, the fifth lens 7, the sixth lens 8, the seventh lens 9, the eighth lens 10, the ninth lens 11, the tenth lens 12, and the eleventh lens 13 are sequentially cemented together to form a second cemented lens group. The arrangement of the second cemented lens group, combined with the optical power and surface design of each lens in the group, helps to counteract the chromatic aberration caused by the wavelength difference between visible light and fluorescence, enabling visible light and fluorescence to be simultaneously focused on the image plane, thus meeting the requirements for clear imaging of both visible light and fluorescence.

[0072] In some embodiments, the Abbe number of the fourth lens 6 is greater than that of the fifth lens 7, the Abbe number of the sixth lens 8 is less than that of the seventh lens 9, the Abbe number of the eighth lens 10 is less than that of the ninth lens 11, and the Abbe number of the tenth lens 12 is greater than that of the eleventh lens 13. In some embodiments, the Abbe number of the fourth lens 6 is 90.3, the Abbe number of the fifth lens 7 is 20.9, the Abbe number of the sixth lens 8 is 31.4, the Abbe number of the seventh lens 9 is 54.5, the Abbe number of the eighth lens 10 is 23.8, the Abbe number of the ninth lens 11 is 64.2, the Abbe number of the tenth lens 12 is 60.4, and the Abbe number of the eleventh lens 13 is 31.4. In this way, the materials of each lens in the second cemented lens group can be reasonably matched, and the optical power and surface design of each lens in the second cemented lens group can be combined to help cancel each other out by the dispersion characteristics of different materials, reduce the chromatic aberration of visible light and fluorescence imaging, and improve the imaging quality of visible light and fluorescence of the optical imaging system.

[0073] In some embodiments, the optical imaging system further includes an aperture stop disposed between the steering element 4 and the third lens 5. Thus, in conjunction with the optical power and surface design of each lens in the objective lens assembly, the aperture stop can effectively control the direction of light, compress the aperture of the objective lens assembly, improve structural compactness, and help reduce the maximum insertion width of the optical imaging system, thereby helping to reduce the risk of injury to the patient from the use of the endoscope.

[0074] In some embodiments, the optical imaging system further includes a field stop 25, which is disposed between the bar lens group and the eyepiece group.

[0075] Combination Figure 1 and Figure 3 As shown, in some embodiments, the magnification of the rod lens group is 1. The rod lens group includes multiple sets of rod lenses arranged at intervals along the optical axis. The number of rod lenses can be odd, and can be set according to the light transmission length requirements. Each set of rod lenses includes a third cemented lens group and a symmetrical cemented lens group with optical power. The third cemented lens group and the symmetrical cemented lens group are mirror-symmetrical about the plane perpendicular to the optical axis. The cooperation of the third cemented lens group and the symmetrical cemented lens group can achieve proportional image transmission. Moreover, the transverse chromatic aberration, coma, and even transverse chromatic aberration of the third cemented lens group and the symmetrical cemented lens group are equal in magnitude but opposite in sign, and can cancel each other out, thereby improving the imaging quality of the optical imaging system.

[0076] In some embodiments, the third cemented lens group includes a twelfth lens 14 with positive optical power, a thirteenth lens 15 with negative optical power, and a fourteenth lens 16 with positive optical power. The object-side and image-side surfaces of the twelfth lens 14 are both convex, the object-side and image-side surfaces of the thirteenth lens 15 are both concave, and the object-side and image-side surfaces of the fourteenth lens 16 are both convex. The arrangement of the symmetrical cemented lens group can be obtained by referring to the third cemented lens group. By rationally configuring the optical power and surface shape of each lens, and using a cemented lens group with a combination of positive and negative optical power, it is possible to effectively reduce Petzval sum and spherical aberration, while also having good light energy transmission efficiency, which is beneficial to improving the imaging quality of the optical imaging system.

[0077] In some embodiments, the rod lens group satisfies the following conditions: 1mm ≤ T3 ≤ 4mm; 1mm ≤ T4 ≤ 6mm; where T3 is the distance on the optical axis between the third cemented lens group and the symmetrical cemented lens group in each rod lens group, and T4 is the distance on the optical axis between two adjacent rod lens groups. For example, T3 can be 1mm, 2mm, 3mm, or 4mm, and T4 can be 1mm, 2mm, 3mm, 4mm, 5mm, or 6mm. When the above conditions are satisfied, the distance between the third and fourth cemented lens groups is appropriate, so that the aberrations of the third and fourth cemented lens groups can be effectively canceled out, improving the image transmission quality of the rod lens group. It also helps to improve the structural compactness of the rod lens group, and further facilitates the smooth transition of light between multiple rod lens groups, which also helps to improve the image transmission quality of the rod lens group.

[0078] Combination Figure 1 and Figure 4As shown, in some embodiments, the eyepiece group includes, along the optical axis from the object side to the image side, a fifteenth lens 17 with negative optical power, a sixteenth lens 18 with positive optical power, a seventeenth lens 19 with negative optical power, an eighteenth lens 20 with positive optical power, a nineteenth lens 21 with negative optical power, a twentieth lens 22 with positive optical power, and a twenty-first lens 23 with positive optical power. The image-side surface of the fifteenth lens 17 is concave, the object-side surface of the sixteenth lens 18 is convex, the image-side surface of the seventeenth lens 19 is concave, both the object-side and image-side surfaces of the eighteenth lens 20 are convex, and both the object-side and image-side surfaces of the nineteenth lens 21 are concave.

[0079] In the aforementioned eyepiece group, the negative optical power of the fifteenth lens 17, combined with its concave surface shape on the image side, can diverge light and enhance the divergence of fluorescence, thus initially widening the angle between visible light and fluorescence and providing adjustment space for chromatic aberration compensation by the image-side lens. The positive optical power of the sixteenth lens 18, combined with its convex surface shape on the object side, can partially offset the excessive divergence of fluorescence by the fifteenth lens 17, improving the brightness uniformity of visible light and fluorescence in the central field of view. The negative optical power of the seventeenth lens 19, combined with its concave surface shape on the image side, can correct the excessive convergence of fluorescence by the sixteenth lens 18, bringing the intersection points of visible light and fluorescence closer together. The optical power and surface shape of the eighteenth lens 20 are beneficial for correcting spherical aberration of visible light and fluorescence, and, in conjunction with the seventeenth lens 19, reduce the focal deviation between visible light and fluorescence. The optical power and surface shape design of the nineteenth lens 21 can compensate for the field curvature produced by the eighteenth lens 20, while simultaneously improving the relative illumination of visible light and fluorescence across the entire field of view. The optical power and surface shape of the twentieth lens 22 and the twenty-first lens 23 are matched to further reduce the chromatic aberration between visible light and fluorescence.

[0080] Therefore, the above-mentioned eyepiece group, through the rational design of the optical power and surface shape of each lens, can have good imaging quality for both visible light and fluorescence, meeting the imaging quality requirements of optical imaging systems. When applied to endoscopes, it is beneficial to improve the accuracy of diagnosis and treatment.

[0081] In some embodiments, the object-side surface of the fifteenth lens 17 is convex; the image-side surface of the sixteenth lens 18 is convex; the object-side surface of the seventeenth lens 19 is concave; the object-side surface of the twentieth lens 22 is convex and the image-side surface is concave; and both the object-side and image-side surfaces of the twenty-first lens 23 are convex. This configuration, combined with the optical power and surface design of each lens, allows for effective adjustment of the angle of light, focal position, and dispersion differences of visible light and fluorescence, thereby significantly improving the imaging quality of the eyepiece assembly for visible light and fluorescence.

[0082] In some embodiments, the fifteenth lens 17, the sixteenth lens 18, the seventeenth lens 19, the eighteenth lens 20, the nineteenth lens 21, the twentieth lens 22, and the twenty-first lens 23 are sequentially cemented together to form a fourth cemented lens group. The arrangement of the fourth cemented lens group, in conjunction with the optical power and surface design of each lens in the eyepiece group, is beneficial for improving dispersion compensation for visible light and fluorescence, reducing defocusing of visible light and fluorescence, and increasing the relative illumination of the edge field of view, thereby improving the imaging quality of visible light and fluorescence. It also helps to improve the structural compactness of the eyepiece group.

[0083] In some embodiments, the Abbe number of the fifteenth lens 17 is greater than that of the sixteenth lens 18, the Abbe number of the seventeenth lens 19 is less than that of the eighteenth lens 20, the Abbe number of the nineteenth lens 21 is less than that of the twentieth lens 22, and the Abbe number of the twentieth lens 22 is greater than that of the twenty-first lens 23. For example, in some embodiments, the Abbe number of the fifteenth lens 17 is 70.4, the Abbe number of the sixteenth lens 18 is 23.8, the Abbe number of the seventeenth lens 19 is 36.3, the Abbe number of the eighteenth lens 20 is 70.4, the Abbe number of the nineteenth lens 21 is 28.3, the Abbe number of the twentieth lens 22 is 55.5, and the Abbe number of the twenty-first lens 23 is 39.2. This arrangement allows the chromatic aberration of visible light and fluorescence to be corrected by utilizing the dispersive properties of the materials, resulting in good imaging quality for both visible light and fluorescence in the eyepiece assembly.

[0084] refer to Figures 1-4 As shown, in some embodiments, the objective lens group satisfies the following conditions: -18.45mm ≤ f(B01) ≤ -8.59mm; 17.96mm ≤ f(B02) ≤ 24.64mm; where f(B01) is the focal length of the first cemented lens group and f(B02) is the focal length of the second cemented lens group. For example, f(B01) can be -18.45mm, -15.5mm, -12.19mm, -10.05mm, -8.59mm, etc., and f(B02) can be 17.96mm, 19.67mm, 22.23mm, 24.64mm, etc. When the above conditions are met, the diverging effect of the first cemented lens group and the converging effect of the second cemented lens group can be reasonably configured. This is beneficial for increasing the field of view of the objective lens group while suppressing the distortion of the objective lens group, while improving the relative illumination of the edge field of view. The tolerance sensitivity of the objective lens group is reduced through the smooth transition of light, thereby improving the imaging quality of the objective lens group. At the same time, it is beneficial for improving the phase difference correction of the objective lens group for visible light and fluorescence, reducing the focus deviation of visible light and fluorescence, so that the objective lens group has good imaging quality for both visible light and fluorescence.

[0085] In some embodiments, the objective lens group satisfies the condition: 0.6 ≤ f(BO2) / CT2 ≤ 0.8; where f(BO2) is the focal length of the second cemented lens group, and CT2 is the thickness of the second cemented lens group along the optical axis. For example, f(BO2) / CT2 can be 0.6, 0.7, or 0.8, etc. When the above condition is satisfied, the converging effect of the second cemented lens group on visible light and fluorescence can be balanced, the defocusing amount of visible light and fluorescence can be reduced, and the surface curvature of each lens in the second cemented lens group can be optimized. This is beneficial for correcting aberrations such as spherical aberration and coma, reducing the tolerance sensitivity and imaging quality of the second cemented lens group, and also helps to improve the structural compactness of the objective lens group and reduce the radial dimension of the objective lens group, thereby reducing the maximum insertion width of the endoscope.

[0086] In some embodiments, the eyepiece group satisfies the condition: 0.7 ≤ f(B04) / CT4 ≤ 0.9; where f(B04) is the focal length of the fourth cemented lens group, and CT4 is the thickness of the fourth cemented lens group along the optical axis. For example, f(B04) / CT4 can be 0.7, 0.8, or 0.9, etc. When the above condition is satisfied, the ratio of the focal length to the center thickness of the eyepiece group can be reasonably configured. This optimizes the light-converging effect of the eyepiece group while reducing the tolerance sensitivity of each lens in the eyepiece group, reducing the manufacturing and molding difficulty of each lens, improving the assembly yield, and also improving the structural compactness of the eyepiece group.

[0087] In some embodiments, the optical imaging system satisfies the following: 2.78mm ≤ f(object) ≤ 3.3mm; 29mm ≤ f(BO3) ≤ 31mm; f(BO4) ≤ 17.85mm; where f(object) is the focal length of the objective lens group, f(BO3) is the focal length of the third cemented lens group, and f(BO4) is the focal length of the fourth cemented lens group. For example, f(object) can be 2.78mm, 2.85mm, 3.05mm, or 3.3mm, etc.; f(BO3) can be 29mm, 30mm, or 31mm, etc.; and f(BO4) can be 13.92mm, 15.32mm, 16.55mm, or 17.85mm, etc. When the above conditions are met, the focal lengths of the objective lens group, rod lens group, and eyepiece group can be reasonably configured, which is beneficial to expanding the depth of field of the optical imaging system. At the same time, the negative distortion of the objective lens group can compensate for the positive distortion of the eyepiece group, effectively suppressing the distortion of the optical imaging system and improving image quality. In addition, the focal length of the rod lens group can be well matched with the objective lens group and the eyepiece group, improving the consistency and efficiency of image transmission. Through the reasonable design of the focal lengths of the objective lens group, rod lens group, and eyepiece group, the structural compactness of the optical imaging system can also be improved, and the maximum insertion width of the optical imaging system can be reduced, thereby reducing the damage to patients during the use of the endoscope.

[0088] In some embodiments, the eyepiece assembly further includes a second protective element 24 disposed on the image side of the twenty-first lens 23. The second protective element 24 includes, but is not limited to, a flat glass plate, for providing protection for each lens in the eyepiece assembly.

[0089] In some embodiments, the object side and image side of the first lens 2 can both be aspherical, the material of the first lens 2 can be glass, the first lens 2 is set at a key position for light collection in the optical imaging system, and the use of aspherical glass as the first lens 2 can enrich the first lens 2's ability to adjust light, so that the first lens 2 can suppress the generation of aberrations such as distortion while collecting light, thereby helping to improve the imaging quality of the optical imaging system.

[0090] In some embodiments, except for the first lens 2, the object-side and image-side surfaces of all lenses in the objective lens group, rod lens group, and eyepiece group are spherical. While achieving the aforementioned effects, the spherical surface also helps reduce the design and manufacturing difficulty of the optical imaging system, and facilitates a smaller aperture, thus aiding in the assembly of the optical imaging system in a broadband endoscope and reducing patient injury during surgery. In some embodiments, the materials of each lens in the optical imaging system can be glass or plastic, or any combination of glass and plastic. By using commonly available materials, the manufacturing difficulty and cost of the optical imaging system are reduced.

[0091] In some embodiments, through rational design, the optical imaging system can be matched with a 1 / 1.8-inch image sensor, achieving good imaging quality for both visible light and fluorescence. Furthermore, the imaging resolution of the optical imaging system is improved, the depth of field is expanded, and aberrations such as distortion are effectively suppressed. Simultaneously, the low tolerance sensitivity of each lens is beneficial for improving molding and assembly yield. The optical working distance of the optical imaging system can be 50mm, the working length can be 330mm-335mm, the field of view is greater than 80°, and the entrance pupil diameter can be 0.43mm-0.6mm. With the design of each lens, the depth of field range can be increased to 3mm-200mm, and the maximum insertion width W of the endoscope can be controlled to W≤10mm.

[0092] Please see Figures 5-11 As shown, Figure 5 The graph shows the MTF (Mean Transfer Function) of the optical imaging system in some embodiments under visible light (0.435µm-0.656µm). Figure 6 This is a defocusing curve of the optical imaging system in some embodiments at 40 lp / mm in the visible light (0.435 μm-0.656 μm) range. Figure 7 The graph shows the transfer function of the optical imaging system in some embodiments under fluorescence (0.830 μm). Figure 8This is a defocusing curve of the optical imaging system at 40 lp / mm under fluorescence (0.830 μm) in some embodiments. Figure 9 This is a relative illumination map of the optical imaging system in some embodiments. Figure 10 These are field curvature and distortion curves of the optical imaging system in some embodiments. Figure 11 This is a diagram showing the light spot pattern of an optical imaging system in some embodiments.

[0093] Depend on Figures 5-11 As can be seen, because the negative distortion of the objective lens group cancels out the positive distortion of the eyepiece group, the distortion of the optical imaging system can be controlled within -4.5%, effectively improving image quality and benefiting diagnosis and treatment. Simultaneously, the optical imaging system possesses excellent image brightness, with a relative illumination of over 80% at the edge of the field of view and no vignetting. Under visible light, the resolution meets 40 lp / mm, and the full-field contrast ratio is greater than 0.55. Under fluorescence, the resolution meets 40 lp / mm, and the full-field contrast ratio is greater than 0.38. Under visible light focusing, the fluorescence defocus is less than 0.03 mm, providing clear image quality for both visible and fluorescence, meeting the requirements of fluorescence endoscopy and improving the accuracy of diagnosis and treatment. In the dot matrix diagram, the diffuse spots are all smaller than the Airy disk, and the spot diameters are all included within the Airy disk, essentially at the diffraction limit. Short-wavelength and long-wavelength chromatic aberrations converge and are concentrated, indicating good image quality.

[0094] Based on the optical imaging system described in any of the above embodiments, this application also provides an endoscope, including a structural component and the optical imaging system as described in any of the above embodiments. The structural component can be a physical support structure for the optical imaging system. The endoscope includes, but is not limited to, a fluorescence laparoscope, a fluorescence thoracic and laparoscopic endoscope, etc. By employing the above-described optical imaging system in the endoscope, the endoscope can achieve good imaging quality for both infrared and visible light, thereby improving the accuracy of diagnosis and treatment.

[0095] 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.

[0096] 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 group, characterized by, The eyepiece group includes, along the optical axis from the object side to the image side, a fifteenth lens with negative optical power, a sixteenth lens with positive optical power, a seventeenth lens with negative optical power, an eighteenth lens with positive optical power, a nineteenth lens with negative optical power, a twentieth lens with positive optical power, and a twenty-first lens with positive optical power. The image-side surface of the fifteenth lens is concave, the object-side surface of the sixteenth lens is convex, the image-side surface of the seventeenth lens is concave, both the object-side and image-side surfaces of the eighteenth lens are convex, and both the object-side and image-side surfaces of the nineteenth lens are concave.

2. The eyepiece group of claim 1, wherein The fifteenth lens, the sixteenth lens, the seventeenth lens, the eighteenth lens, the nineteenth lens, the twentieth lens, and the twenty-first lens are cemented together in sequence to form the fourth cemented lens group; The eyepiece assembly satisfies the following condition: f(B04)≤17.85mm; 0.7 ≤ f(B04) / CT4 ≤ 0.9; Where f(B04) is the focal length of the fourth cemented lens group, and CT4 is the thickness of the fourth cemented lens group on the optical axis.

3. The eyepiece assembly according to claim 1, characterized in that, The object-side surface of the fifteenth lens is convex. The image-side surface of the sixteenth lens is convex. The object-side surface of the seventeenth lens is concave; The object-side surface of the twentieth lens is convex, and the image-side surface is concave. The object-side and image-side surfaces of the 21st lens are both convex.

4. The eyepiece group of claim 1, wherein The Abbe number of the fifteenth lens is greater than that of the sixteenth lens, the Abbe number of the seventeenth lens is less than that of the eighteenth lens, the Abbe number of the nineteenth lens is less than that of the twentieth lens, and the Abbe number of the twentieth lens is greater than that of the twenty-first lens.

5. An optical imaging system characterized by, It includes a rod lens group, an objective lens group, a field stop, and an eyepiece group as described in any one of claims 1-4, wherein the objective lens group, the rod lens group, the field stop, and the eyepiece group are arranged sequentially along the direction of light propagation, and both the rod lens group and the objective lens group include multiple lenses with optical power.

6. The optical imaging system of claim 5, wherein, The objective 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 third lens with positive optical power, a fourth lens with positive optical power, a fifth lens with positive optical power, a sixth lens with negative optical power, a seventh lens with positive optical power, an eighth lens with negative optical power, a ninth lens with negative optical power, a tenth lens with positive optical power, and an eleventh lens with negative optical power. 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 third lens is convex; the object-side surface of the fourth lens is convex, and the image-side surface is concave; both the object-side and image-side surfaces of the fifth lens are convex; both the object-side and image-side surfaces of the sixth lens are concave; both the object-side and image-side surfaces of the seventh lens are convex; both the object-side and image-side surfaces of the eighth lens are concave, and the image-side surface of the ninth lens are concave; both the object-side and image-side surfaces of the tenth lens are convex; and both the object-side and image-side surfaces of the eleventh lens are concave, and the image-side surface of the eleventh lens is concave.

7. The optical imaging system of claim 6, wherein, The objective lens group further includes a steering element disposed between the second lens and the third lens. The first lens, the second lens, the steering element and the third lens are cemented together in sequence to form a first cemented lens group. The fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens, the tenth lens and the eleventh lens are cemented together in sequence to form a second cemented lens group. The objective lens assembly satisfies the following condition: -18.45mm≤f(B01)≤-8.59mm; 17.96mm≤f(B02)≤24.64mm; 0.6 ≤ f(B02) / CT2 ≤ 0.8; 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, and CT2 is the thickness of the second cemented lens group on the optical axis.

8. The optical imaging system of claim 6, wherein, The Abbe number of the fourth lens is greater than that of the fifth lens, the Abbe number of the sixth lens is less than that of the seventh lens, the Abbe number of the eighth lens is less than that of the ninth lens, and the Abbe number of the tenth lens is greater than that of the eleventh lens. And / or, The objective lens assembly satisfies the following condition: 2.78mm ≤ f(object) ≤ 3.3mm; Where f(object) is the focal length of the objective lens group; And / or, The optical imaging system further includes a steering element and an aperture stop. The steering element is disposed between the second lens and the fourth lens, and the aperture stop is disposed between the steering element and the third lens. The Abbe number of the first lens is greater than that of the second lens, and the Abbe number of the steering element is less than that of the third lens.

9. The optical imaging system of claim 5, wherein, The rod lens group includes multiple rod lenses arranged sequentially from the object side to the image side along the optical axis. The rod lenses include a third cemented lens group and a symmetrical cemented lens group. The third cemented lens group and the symmetrical 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, a thirteenth lens with negative optical power, and a fourteenth lens with positive optical power. The object-side and image-side surfaces of the twelfth lens are both convex, the object-side and image-side surfaces of the thirteenth lens are both concave, and the object-side and image-side surfaces of the fourteenth lens are both convex. The rod lens group satisfies the following condition: 1mm≤T3≤4mm; 1mm≤T4≤6mm; 29mm≤f(B03)≤31mm; Wherein, T3 is the distance on the optical axis between the third cemented lens group and the symmetrical cemented lens group in each group of rod lenses, T4 is the distance on the optical axis between two adjacent groups of rod lenses, and f(B03) is the focal length of the third cemented lens group.

10. An endoscope characterized by comprising: Includes the optical imaging system as described in any one of claims 5-9.

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