Objective lens group, fluorescent optical system, and endoscope

Abstract

The invention relates to an objective lens group, a fluorescent optical system and an endoscope. The objective lens group comprises a first lens with negative focal power, a second lens with negative focal power, a third lens with positive focal power, a fourth lens with positive focal power, a fifth lens with positive focal power, a sixth lens with negative focal power, a seventh lens with positive focal power and an eighth lens with negative focal power; a ninth lens having a negative focal power; a tenth lens having a positive focal power; and an eleventh lens having a negative focal power. The object side surface of the first lens is a convex surface, the image side surface of the first lens is a concave surface, the image side surface of the third lens is a convex surface, the image side surface of the sixth lens is a concave surface, the image side surface of the ninth lens is a concave surface, and the object side surface and the image side surface of the tenth lens are convex surfaces. The objective lens group can perform clear imaging on visible light and fluorescent light at the same time.

Description

Technical Field

[0001] The present application relates to the technical field of endoscopes, and in particular to an objective lens assembly, a fluorescence optical system, and an endoscope. Background Art

[0002] Fluorescent endoscopes, such as fluorescent laparoscopic and thoracoabdominal endoscopes, can enter the human body through natural channels or minimally invasive incisions for diagnosis or treatment. Fluorescent endoscopes can work with fluorescent optical systems to simultaneously focus visible and near-infrared light for imaging. By injecting fluorescent contrast agents such as indocyanine green (ICG) into the patient's body, the agent binds to plasma proteins. When illuminated with 780nm-810nm light, the fluorescent contrast agent is excited and emits near-infrared light of 820nm-840nm.

[0003] Fluorescence optical systems simultaneously capture images of visible and near-infrared light, enabling doctors to distinguish between diseased and normal areas, improving surgical precision. However, due to the wavelength difference between visible light and fluorescence, conventional fluorescence optical systems used in fluorescence endoscopes struggle to simultaneously capture clear images of both visible and fluorescence light, impacting the accuracy of diagnosis and treatment. Summary of the Invention

[0004] Based on this, it is necessary to provide an objective lens group, a fluorescence optical system and an endoscope to address the problem that traditional fluorescence optical systems are difficult to clearly image visible light and fluorescence at the same time.

[0005] An objective lens assembly comprising, from the object side to the image side along the optical axis, a first lens having negative optical power, a second lens having negative optical power, a third lens having positive optical power, a fourth lens having positive optical power, a fifth lens having positive optical power, a sixth lens having negative optical power, a seventh lens having positive optical power, an eighth lens having negative optical power, a ninth lens having negative optical power, a tenth lens having positive optical power, and an eleventh lens having negative optical power;

[0006] The object-side surface of the first lens is convex, and the image-side surface is concave. The image-side surface of the third lens is convex. The image-side surface of the sixth lens is concave. The image-side surface of the ninth lens is concave. Both the object-side surface and the image-side surface of the tenth lens are convex.

[0007] In the above-mentioned objective lens group, the negative optical focal length of the first lens and the second lens, and the convex-concave surface of the first lens are coordinated, which is conducive to expanding the incident angle of light and improving the light collecting ability of the edge field of view, thereby adapting to the field of view requirements of the endoscope. At the same time, it is also conducive to compressing the light beam angle, reducing the aperture of the image side lens, and suppressing the generation of stray light. The dispersion characteristics of the negative optical focal length of the first lens and the second lens can also preliminarily offset the focus shift of visible light and fluorescence, providing a good foundation for subsequent chromatic aberration correction. The positive optical focal length of the third lens, the fourth lens and the fifth lens are coordinated, which is conducive to quickly converging light and shortening the total length of the objective lens group. It is also conducive to reducing spherical aberration and improving center resolution. The negative optical focal length of the sixth lens and the concave surface of the image side can compensate for the field curvature generated by the positive lens, balance the flatness of the image plane, thereby suppressing the phenomenon of blurred imaging in the edge field of view, and are also conducive to achieving stronger deflection of fluorescence and balancing the field curvature shift of fluorescence. The coordination of the optical power and surface shape of the eighth, ninth, tenth and eleventh lenses is beneficial for correcting coma, improving asymmetric image quality, and improving edge smear of fluorescence images. It is also beneficial for suppressing astigmatism of the objective lens group and improving the coincidence of off-axis image points of fluorescence and visible light.

[0008] Therefore, the above-mentioned objective lens group, through the reasonable design of the optical focal length and surface shape of each lens, can simultaneously clearly image visible light and fluorescence, and can be used in fluorescence optical systems and endoscopes to effectively improve the accuracy of diagnosis and treatment.

[0009] In one embodiment, the objective lens assembly 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 sequentially cemented to form a first cemented lens assembly, 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 to form a second cemented lens assembly;

[0010] In one embodiment, the objective lens assembly satisfies the following conditional formula:

[0011] -18.45mm≤f(B01)≤-8.59mm;

[0012] 17.96mm≤f(B02)≤24.64mm;

[0013] 0.6≤f(B02) / CT2≤0.8;

[0014] 2.78mm≤f(object)≤3.3mm;

[0015] Wherein, 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, and f(object) is the focal length of the objective lens group.

[0016] In one embodiment, the objective lens assembly satisfies the following conditional formula:

[0017] -18.45mm≤f(B01)≤-7.5mm;

[0018] 17.96mm≤f(B02)≤24.64mm;

[0019] 2.78mm≤f(object)≤3.3mm;

[0020] Wherein, 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 f(object) is the focal length of the objective lens group.

[0021] In one embodiment, the image-side surface of the second lens is concave, the object-side surface of the fourth lens is convex, and the image-side surface is concave, the object-side surface and the image-side surface of the fifth lens are both convex, the object-side surface of the sixth lens is concave, the object-side surface and the image-side surface of the seventh lens are both convex, the object-side surface of the eighth lens is concave, and the image-side surface is convex, the object-side surface of the ninth lens is concave, and the object-side surface of the eleventh lens is concave, and the image-side surface is convex.

[0022] In one embodiment, the Abbe number of the fourth lens is greater than the Abbe number of the fifth lens, the Abbe number of the sixth lens is smaller than the Abbe number of the seventh lens, the Abbe number of the eighth lens is smaller than the Abbe number of the ninth lens, and the Abbe number of the tenth lens is greater than the Abbe number of the eleventh lens.

[0023] In one embodiment, the objective lens group further includes a steering element and an aperture stop, wherein the steering element is arranged between the second lens and the fifth lens, and the aperture stop is arranged between the steering element and the third lens.

[0024] In one embodiment, the Abbe number of the first lens is greater than the Abbe number of the second lens, and the Abbe number of the steering element is smaller than the Abbe number of the third lens.

[0025] A fluorescence optical system comprises a rod lens group, an eyepiece group and an objective lens group as described in any of the above embodiments, wherein the objective lens group, the rod lens group and the eyepiece group are arranged in sequence along the direction of light propagation, and the rod lens group and the eyepiece group each comprise a plurality of lenses with optical power.

[0026] In one embodiment, the eyepiece assembly includes, from the object side to the image side along the optical axis, a fifteenth lens having negative refractive power, a sixteenth lens having positive refractive power, a seventeenth lens having negative refractive power, an eighteenth lens having positive refractive power, a nineteenth lens having negative refractive power, a twentieth lens having positive refractive power, and a twenty-first lens having positive refractive power;

[0027] The object side surface of the fifteenth lens is convex, and the image side surface is concave, the object side surface and the image side surface of the sixteenth lens are both convex, the object side surface and the image side surface of the seventeenth lens are both concave, the object side surface and the image side surface of the eighteenth lens are both convex, the object side surface and the image side surface of the nineteenth lens are both concave, the object side surface and the image side surface of the twentieth lens are convex, and the image side surface is concave, and the object side surface and the image side surface of the twenty-first lens are both convex.

[0028] In one embodiment, the fifteenth lens, the sixteenth lens, the seventeenth lens, the eighteenth lens, the nineteenth lens, the twenty-first lens, and the twenty-first lens are cemented in sequence to form a fourth cemented lens group, and the fluorescence optical system satisfies the following conditional formula:

[0029] f(B04)≤17.85mm;

[0030] 0.7≤f(B04) / CT4≤0.9;

[0031] 29mm≤f(B03)≤31mm;

[0032] Wherein, f(B04) is the focal length of the fourth cemented lens group, CT4 is the thickness of the fourth cemented lens group on the optical axis, and f(B03) is the focal length of the third cemented lens group.

[0033] In one embodiment, the Abbe number of the fifteenth lens is greater than the Abbe number of the sixteenth lens, the Abbe number of the seventeenth lens is smaller than the Abbe number of the eighteenth lens, the Abbe number of the nineteenth lens is smaller than the Abbe number of the twentieth lens, and the Abbe number of the twentieth lens is greater than the Abbe number of the twenty-first lens.

[0034] In one embodiment, the eyepiece assembly includes, from the object side to the image side along the optical axis, a fifteenth lens having positive refractive power, a sixteenth lens having negative refractive power, a seventeenth lens having positive refractive power, an eighteenth lens having negative refractive power, and a nineteenth lens having positive refractive power;

[0035] The image side surface of the fifteenth lens is convex, the object side surface and the image side surface of the sixteenth lens are both concave, the object side surface and the image side surface of the seventeenth lens are both convex, the object side surface and the image side surface of the eighteenth lens are both concave, and the object side surface and the image side surface of the nineteenth lens are both convex.

[0036] In one embodiment, the fifteenth lens, the sixteenth lens, the seventeenth lens, the eighteenth lens, and the nineteenth lens are cemented in sequence to form a fourth cemented lens, and the fluorescence optical system satisfies the following conditional formula:

[0037] f(B04)≤16mm;

[0038] 0.6≤f(B04) / CT4≤0.85;

[0039] 29mm≤f(B03)≤32mm;

[0040] Wherein, f(B04) is the focal length of the fourth cemented lens group, CT4 is the thickness of the fourth cemented lens group on the optical axis, and f(B03) is the focal length of the third cemented lens group.

[0041] In one embodiment, the Abbe number of the fifteenth lens is smaller than that of the sixteenth lens, the Abbe number of the seventeenth lens is larger than that of the eighteenth lens, and the Abbe number of the eighteenth lens is smaller than that of the nineteenth lens.

[0042] In one embodiment, the rod lens group includes a plurality of rod lenses sequentially arranged along the optical axis from the object side to the image side, 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;

[0043] The third cemented lens group includes a twelfth lens with positive focal power, a thirteenth lens with negative focal power, and a fourteenth lens with positive focal power; the object-side surface and the image-side surface of the twelfth lens are both convex surfaces, the object-side surface and the image-side surface of the thirteenth lens are both concave surfaces, and the object-side surface and the image-side surface of the fourteenth lens are both convex surfaces.

[0044] An endoscope comprises the fluorescence optical system as described in any one of the above embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 Schematic diagram of the structure of the fluorescence optical system in the first embodiment.

[0046] Figure 2 Schematic diagram of the structure of the objective lens group in the first embodiment.

[0047] Figure 3Schematic diagram of the structure of the rod mirror assembly in the first embodiment.

[0048] Figure 4 Schematic diagram of the structure of the eyepiece assembly in the first embodiment.

[0049] Figure 5 FIG. 4 is a transfer function curve of the fluorescence optical system under visible light in the first embodiment.

[0050] Figure 6 4 is a defocus curve diagram of the fluorescence optical system in the first embodiment at 40 lp / mm under visible light.

[0051] Figure 7 FIG. 4 is a transfer function curve diagram of the fluorescence optical system under fluorescence in the first embodiment. FIG.

[0052] Figure 8 4 is a defocus curve diagram of the fluorescence optical system in the first embodiment at 40 lp / mm under fluorescence.

[0053] Figure 9 2 is a relative illumination diagram of the fluorescence optical system in the first embodiment.

[0054] Figure 10 Graphs showing the field curvature and distortion of the fluorescence optical system in the first embodiment.

[0055] Figure 11 FIG. 1 is a diagram showing light spots of the fluorescence optical system in the first embodiment.

[0056] Figure 12 Schematic diagram of the structure of the fluorescence optical system in the second embodiment.

[0057] Figure 13 Schematic diagram of the structure of the objective lens group in the second embodiment.

[0058] Figure 14 Schematic diagram of the structure of the rod mirror assembly in the second embodiment.

[0059] Figure 15 Schematic diagram of the structure of the eyepiece assembly in the second embodiment.

[0060] Figure 16 FIG. 4 is a transfer function curve diagram of the fluorescence optical system under visible light in the second embodiment.

[0061] Figure 17 4 is a defocus curve diagram of the fluorescence optical system in the second embodiment at 40 lp / mm under visible light.

[0062] Figure 18 FIG. 4 is a transfer function curve diagram of the fluorescence optical system under fluorescence in the second embodiment.

[0063] Figure 194 is a defocus curve diagram of the fluorescence optical system in the second embodiment at 40 lp / mm under fluorescence.

[0064] Figure 20 2 is a relative illumination diagram of the fluorescence optical system in the second embodiment.

[0065] Figure 21 Graphs showing the field curvature and distortion of the fluorescence optical system in the second embodiment.

[0066] Figure 22 FIG. 4 is a light spot diagram of the fluorescence optical system in the second embodiment. DETAILED DESCRIPTION

[0067] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0068] In the description of this application, it should be understood that if the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or position relationship indicated by these terms is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0069] In addition, if the terms "first" or "second" appear, these terms are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include at least one of such features. In the description of this application, if the term "plurality" appears, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0070] In this application, unless otherwise specified or limited, the terms "mounted," "connected," "connected," "fixed," etc., should be interpreted broadly. For example, these terms may refer to fixed connections, removable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediary; and internal communication between two components or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of these terms in this application based on the specific circumstances.

[0071] In this application, unless otherwise expressly specified or limited, if a first feature is described as being "above" or "below" a second feature, or similar descriptions, this may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, when a first feature is described as being "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is described as being "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0072] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element. If an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. If any, 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 embodiment.

[0073] See Figure 1 , Figure 1 The schematic diagram of the structure of the fluorescence optical system in the first embodiment of the present application is shown. The fluorescence optical system provided by the present application can be applied to medical devices, such as any applicable rigid tube endoscope, such as a fluorescence laparoscope, a fluorescence thoracoabdominal endoscope, etc. The fluorescence optical system can capture images of the lesion to facilitate diagnosis or treatment of the lesion by doctors.

[0074] In some embodiments, a fluorescence optical system includes an objective lens assembly, a rod lens assembly, and an eyepiece assembly, arranged sequentially along the optical axis from the object side to the image side. The objective lens assembly is used to collect light, and the rod lens assembly is used to transmit the light collected by the objective lens assembly to the eyepiece assembly. The fluorescence optical system may also be equipped with an optical adapter. The eyepiece assembly is used to magnify the image and transmit it to the optical adapter. The optical adapter can then adjust the light and transmit it to the image sensor. The optical adapter can use any suitable adapter lens and is not limited in this application.

[0075] Further, combined with Figure 1 and Figure 2 As shown, in some embodiments, the objective lens group includes, from the object side to the image side along the optical axis, 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. The first lens 2 has negative optical power, with the object-side surface of the first lens 2 being convex and the image-side surface being concave. The second lens 3 has negative optical power, the third lens 5 has positive optical power, and the image-side surface of the third lens 5 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 the image-side surface of the sixth lens 8 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 the image-side surface of the ninth lens 11 is concave. The tenth lens 12 has positive optical power, with both the object-side and image-side surfaces of the tenth lens 12 being convex. The eleventh lens 13 has negative optical power.

[0076] In the above-mentioned objective lens group, the negative focal lengths of the first lens 2 and the second lens 3, as well as the convex-concave surface of the first lens 2, are coordinated to expand the incident angle of light and enhance the light-gathering capability of the edge field of view, thereby adapting to the field of view requirements of the endoscope. At the same time, they are also conducive to compressing the light beam angle, reducing the aperture of the image side lens, and suppressing the generation of stray light. The dispersion characteristics of the negative focal lengths of the first lens 2 and the second lens 3 can also preliminarily offset the focus offset of visible light and fluorescence, providing a good foundation for subsequent chromatic aberration correction. The positive focal lengths of the third lens 5, the fourth lens 6, and the fifth lens 7 are coordinated to facilitate rapid convergence of light, shorten the total length of the objective lens group, and also help reduce spherical aberration and enhance center resolution. The negative focal length of the sixth lens 8 and the concave surface of the image side can compensate for the field curvature generated by the positive lens, balance the image flatness, thereby suppressing the phenomenon of blurred imaging of the edge field of view, and are also conducive to achieving stronger deflection of fluorescence and balancing the field curvature offset of fluorescence. The coordination of the optical power and surface shape of the eighth lens element 10, the ninth lens element 11, the tenth lens element 12, and the eleventh lens element 13 facilitates correction of coma, improves asymmetric image quality, and improves edge smear of the fluorescence image. Furthermore, it facilitates suppression of astigmatism of the objective lens group and improves the overlap of off-axis image points of fluorescence and visible light.

[0077] Therefore, the above-mentioned objective lens group, through the reasonable design of the optical focal length and surface shape of each lens, can simultaneously clearly image visible light and fluorescence (such as near-infrared light in the 820nm-840nm band). Its application in fluorescence optical systems and endoscopes can effectively improve the accuracy of diagnosis and treatment.

[0078] In some embodiments, the image side surface of the second lens 3 is concave, and the optical power and surface design of the first lens 2 and the second lens 3 are matched, which can well control the initial direction of the light, and is conducive to reducing the effective aperture of the lens in the objective lens group, making the structure of the objective lens group more compact, and is conducive to reducing 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 is conducive to balancing coma and astigmatism, and improving full-field imaging uniformity. 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 and improve the imaging resolution of the central field of view of the objective lens group. The fifth lens 7 and the sixth lens 8 cooperate, which is conducive to reducing the Petzval field curvature, balancing the flatness of the image plane, and improving imaging quality. The object-side surface and image-side surface of the seventh lens element 9 are both convex, while the object-side surface of the eighth lens element 10 is concave and the image-side surface is convex. The seventh lens element 9 can further converge light and improve the detail resolution capability of the objective lens group. The seventh lens element 9 and the eighth lens element 10 cooperate to correct spherical aberration and optimize the depth of field, enabling the fluorescence optical system to clearly image objects at a wider object distance range. The object-side surface of the ninth lens element 11 is concave. The ninth lens element 11 cooperates with the tenth lens element 12 to further balance field curvature and astigmatism, improving the uniformity of imaging clarity across the entire field of view. The object-side surface of the eleventh lens element 13 is concave and the image-side surface is convex.

[0079] In some embodiments, the objective lens assembly further includes a first protective element 1 and a deflection element 4. The first protective element 1 includes, but is not limited to, flat glass. The first protective element 1 is disposed on the object side of the first lens 2 and is used to provide protection for each lens in the objective lens assembly. The deflection element 4 is disposed between the second lens 3 and the third lens 5. The deflection element 4 includes, but is not limited to, a deflection flat crystal or a deflection prism formed by gluing multiple prisms together. The deflection element 4 is used to deflect the optical path to a certain angle, including but not limited to 0°, 30°, 45°, 70°, etc., to accommodate the imaging angle of the endoscope.

[0080] 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 to form a first cemented lens group. This not only improves the structural compactness of the objective lens group, but also facilitates the matching of the optical paths on the object and image sides of the steering element 4, ensuring good imaging quality. Furthermore, the configuration of the first cemented lens group, combined with the optical power and surface design of each lens in the first cemented lens group, also helps offset focus shift between visible light and fluorescence, reducing axial chromatic aberration of visible light and fluorescence, thereby improving the imaging quality of the objective lens group for visible light and fluorescence.

[0081] 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 deflection element 4 is less than that of the third lens 5. This allows for the rational combination of materials for the lenses in the first cemented lens assembly and the deflection element 4. This, combined with the optical power and surface design of the lenses in the first cemented lens assembly, facilitates the mutual offset of the dispersion characteristics of different materials, reduces chromatic aberration in visible light and fluorescence imaging, and improves the imaging quality of the fluorescence optical system for both visible light and fluorescence. For example, in the first embodiment, 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 deflection element 4 is 39, and the Abbe number of the third lens 5 is 64.

[0082] 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 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 second cemented lens group, helps offset chromatic aberration caused by the wavelength difference between visible light and fluorescent light, allowing the visible light and fluorescent light to be synchronously focused on the image plane, thereby meeting the requirements for clear imaging of both visible light and fluorescent light.

[0083] 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 a first embodiment, 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 focal length and surface design of each lens in the second cemented lens group are coordinated, which is conducive to offsetting each other through the dispersion characteristics of different materials, reducing the chromatic aberration of visible light and fluorescent imaging, and improving the imaging quality of visible light and fluorescence of the fluorescent optical system.

[0084] In some embodiments, the fluorescence optical system further includes an aperture stop, which is disposed between the deflection 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 trajectory of light, compress the aperture of the objective lens assembly, improve the compactness of the structure, and help reduce the maximum insertion width of the fluorescence optical system, thereby reducing damage to the patient during the use of the endoscope.

[0085] In some embodiments, the fluorescence optical system further includes a field stop 25 , which is disposed between the rod lens group and the eyepiece group.

[0086] Combine 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 rod lens groups spaced sequentially along the optical axis. The number of rod lenses can be an odd number, specifically set based on the required light transmission length. Each rod lens group 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-symmetric about a plane perpendicular to the optical axis. The combination of the third cemented lens group and the symmetrical cemented lens group can achieve proportional image transmission. The vertical axis chromatic aberration, coma, and even vertical axis chromatic aberration of the third cemented lens group and the symmetrical cemented lens group are equal in magnitude and opposite in sign, and can offset each other to improve the imaging quality of the fluorescence optical system.

[0087] In some embodiments, the third cemented lens group includes a twelfth lens 14 with positive power, a thirteenth lens 15 with negative power, and a fourteenth lens 16 with positive 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 described with reference to the third cemented lens group. By rationally configuring the optical power and surface shape of each lens, and employing a cemented lens group with a combination of positive and negative lenses, aberrations such as Petzval sum and spherical aberration can be effectively reduced, while achieving excellent light energy transmission efficiency, thereby improving the imaging quality of the fluorescence optical system.

[0088] In a first embodiment, the rod lens assembly satisfies the following conditions: 1mm≤T3≤4mm; 1mm≤T4≤6mm; wherein T3 is the distance on the optical axis between the third and symmetrical cemented lens groups in each rod lens assembly, 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 met, the distance between the third and fourth cemented lens groups is appropriate, allowing the aberrations of the third and fourth cemented lens groups to effectively offset each other, improving the image quality of the rod lens assembly, and also facilitating a more compact structure of the rod lens assembly. Furthermore, it facilitates a smooth transition of light between multiple rod lens groups, which also improves the image quality of the rod lens assembly.

[0089] Combine Figure 1 and Figure 4As shown, in the first embodiment, the eyepiece assembly includes, from the object side to the image side along the optical axis, a fifteenth lens 17 having negative refractive power, a sixteenth lens 18 having positive refractive power, a seventeenth lens 19 having negative refractive power, an eighteenth lens 20 having positive refractive power, a nineteenth lens 21 having negative refractive power, a twentieth lens 22 having positive refractive power, and a twenty-first lens 23 having positive refractive 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.

[0090] In the aforementioned eyepiece assembly, the negative power of the fifteenth lens 17, combined with the concave surface profile on the image side, can diverge light, enhancing the divergence effect on fluorescence, initially widening the angle between visible light and fluorescence, and providing adjustment space for chromatic aberration compensation of the image-side lens. The positive power of the sixteenth lens 18, combined with the convex surface profile on the object side, can partially offset the excessive divergence of fluorescence caused by the fifteenth lens 17, improving the brightness uniformity of visible light and fluorescence in the central field of view. The negative power of the seventeenth lens 19, combined with the concave surface profile on the image side, can correct the excessive convergence of fluorescence caused by the sixteenth lens 18, further approaching the intersection of visible light and fluorescence. The power and surface profile of the eighteenth lens 20 facilitate correction of spherical aberration for visible light and fluorescence, and in conjunction with the seventeenth lens 19, reduce the focus deviation between visible light and fluorescence. The power and surface profile of the nineteenth lens 21 can compensate for the field curvature produced by the eighteenth lens 20, while also improving the relative illumination of visible light and fluorescence across the entire field of view. The coordination of the optical power and surface shape of the twentieth lens 22 and the twenty-first lens 23 is beneficial to further reduce the chromatic aberration between visible light and fluorescence.

[0091] Therefore, the above-mentioned eyepiece group can have good imaging quality for both visible light and fluorescence through reasonable design of the optical focal length and surface shape of each lens, meet the imaging quality requirements of the fluorescence optical system, and is conducive to improving the accuracy of diagnosis and treatment when used in endoscopes.

[0092] In the first embodiment, the object-side surface of the fifteenth lens element 17 is convex; the image-side surface of the sixteenth lens element 18 is convex; the object-side surface of the seventeenth lens element 19 is concave; the object-side surface of the twentieth lens element 22 is convex, and the image-side surface is concave; and both the object-side and image-side surfaces of the twenty-first lens element 23 are convex. This arrangement, combined with the optical power and surface design of each lens element, allows for precise adjustment of the angle, focal position, and dispersion differences of visible light and fluorescence, effectively improving the imaging quality of the eyepiece assembly for both visible light and fluorescence.

[0093] In the first embodiment, 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 to form a fourth cemented lens group. The arrangement of the fourth cemented lens group, combined with the optical power and surface design of each lens in the eyepiece assembly, facilitates improved dispersion compensation for visible light and fluorescence, reduces defocus for visible light and fluorescence, and increases relative illumination at the edge of the field of view, thereby enhancing the image quality for visible light and fluorescence. It also facilitates the structural compactness of the eyepiece assembly.

[0094] In the first embodiment, 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 the first embodiment, 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 dispersion characteristics of the materials to offset each other, resulting in excellent imaging quality for both visible light and fluorescence in the eyepiece assembly.

[0095] refer to Figure 1-Figure 4 As shown, in the first embodiment, the objective lens group satisfies the following conditions: -18.45mm ≤ f(B01) ≤ -8.59mm; 17.96mm ≤ f(B02) ≤ 24.64mm. Here, 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-mentioned conditional formula is met, the divergent effect of the first cemented lens group on light and the convergent effect of the second cemented lens group on light can be reasonably configured, which is beneficial to suppressing the distortion of the objective lens group while increasing the field of view angle of the objective lens group, and at the same time 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, and the imaging quality of the objective lens group is improved. At the same time, it is beneficial to improve the phase difference correction of the objective lens group for visible light and fluorescence, reduce the focus deviation of visible light and fluorescence, and make the objective lens group have good imaging quality for both visible light and fluorescence.

[0096] In the first embodiment, the objective lens assembly satisfies the conditional expression: 0.6 ≤ f(B02) / CT2 ≤ 0.8; wherein f(B02) is the focal length of the second cemented lens assembly, and CT2 is the thickness of the second cemented lens assembly along the optical axis. For example, f(B02) / CT2 can be 0.6, 0.7, or 0.8. When this conditional expression is satisfied, the converging effect of the second cemented lens assembly on visible light and fluorescence can be balanced, reducing the defocus of visible light and fluorescence. Simultaneously, the surface curvature of each lens in the second cemented lens assembly is optimized, facilitating correction of aberrations such as spherical aberration and coma, reducing the tolerance sensitivity and imaging quality of the second cemented lens assembly, and further facilitating improved structural compactness of the objective lens assembly and reduced radial dimensions of the objective lens assembly, thereby reducing the maximum insertion width of the endoscope.

[0097] In the first embodiment, the eyepiece assembly satisfies the conditional equation: 0.7 ≤ f(B04) / CT4 ≤ 0.9, where f(B04) is the focal length of the fourth cemented lens assembly, and CT4 is the thickness of the fourth cemented lens assembly along the optical axis. For example, f(B04) / CT4 can be 0.7, 0.8, or 0.9. When this conditional equation is satisfied, the ratio of the focal length to the center thickness of the eyepiece assembly can be optimally configured, optimizing the light converging effect of the eyepiece assembly while also reducing the tolerance sensitivity of each lens in the eyepiece assembly, lowering the difficulty of manufacturing and molding each lens, improving assembly yield, and enhancing the structural compactness of the eyepiece assembly.

[0098] In the first embodiment, the fluorescence optical system satisfies the following conditions: 2.78 mm ≤ f(object) ≤ 3.3 mm; 29 mm ≤ f(B03) ≤ 31 mm; and f(B04) ≤ 17.85 mm. Here, f(object) is the focal length of the objective lens group, f(B03) is the focal length of the third cemented lens group, and f(B04) is the focal length of the fourth cemented lens group. For example, f(object) can be 2.78 mm, 2.85 mm, 3.05 mm, or 3.3 mm, f(B03) can be 29 mm, 30 mm, or 31 mm, and f(B04) can be 13.92 mm, 15.32 mm, 16.55 mm, or 17.85 mm. When the above conditions are met, the focal lengths of the objective lens group, the rod lens group and the eyepiece group can be reasonably configured, which is beneficial to expanding the depth of field of the fluorescence optical system. At the same time, the objective lens group produces negative distortion, which can compensate for the positive distortion produced by the eyepiece group, effectively suppress the distortion of the fluorescence optical system, and improve the imaging quality. In addition, the focal length of the rod lens group can be well adapted to the objective lens group and the eyepiece group, thereby improving the consistency and efficiency of image transmission. Through the reasonable design of the focal lengths of the objective lens group, the rod lens group and the eyepiece group, the structural compactness of the fluorescence optical system can also be improved, and the maximum insertion width of the fluorescence optical system can be reduced, thereby reducing the damage to the patient during the use of the endoscope.

[0099] In the first embodiment, the eyepiece assembly further includes a second protective element 24 provided on the image side of the twenty-first lens 23. The second protective element 24 includes but is not limited to flat glass and is used to provide protection for each lens in the eyepiece assembly.

[0100] In some embodiments, the object side surface and the image side surface of the first lens 2 may both be aspherical surfaces, and the material of the first lens 2 may be glass. The first lens 2 is arranged at a key position for collecting light in the fluorescence optical system. Using an aspherical glass lens 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 fluorescence optical system.

[0101] In some embodiments, with the exception of the first lens 2, the object-side and image-side surfaces of each lens in the objective lens group, the rod lens group, and the eyepiece group are spherical. While achieving the aforementioned effects, the provision of spherical surfaces also helps reduce the design and manufacturing difficulty of the fluorescence optical system, and helps reduce the aperture of the fluorescence optical system, thereby facilitating the assembly of the fluorescence optical system in a wide-spectrum endoscope and reducing damage to the patient during surgery. In some embodiments, the material of each lens in the fluorescence optical system can be glass, plastic, or any combination of glass and plastic. By using commonly available materials, the manufacturing difficulty and cost of the fluorescence optical system can be reduced.

[0102] In some embodiments, through the reasonable design of the fluorescence optical system, the fluorescence optical system can be matched with a 1 / 1.8-inch image sensor, and can have good imaging quality for both visible light and fluorescence. In addition, the imaging resolution of the fluorescence optical system is improved, the depth of field is expanded, and aberrations such as distortion can be effectively suppressed. At the same time, the tolerance sensitivity of each lens is low, which is conducive to improving the molding and assembly yield. The optical working distance of the fluorescence optical system can be 50mm, the working length can be 330mm-335mm, the field of view angle is greater than 80°, and the entrance pupil diameter can be 0.43mm-0.6mm. Combined 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 at W≤10mm.

[0103] See Figure 5-Figure 11 As shown, Figure 5 is a transfer function (MTF) curve of the fluorescence optical system in the first embodiment under visible light (0.435um-0.656um), Figure 6 : is the defocus curve of the fluorescence optical system in the first embodiment at 40lp / mm under visible light (0.435um-0.656um), Figure 7 is a transfer function curve of the fluorescence optical system in the first embodiment under fluorescence (0.830 μm), Figure 8This is a defocus curve diagram of the fluorescence optical system at 40lp / mm under fluorescence (0.830um) in the first embodiment. Figure 9 is the relative illumination diagram of the fluorescence optical system in the first embodiment, Figure 10 is a field curvature and distortion curve diagram of the fluorescence optical system in the first embodiment, Figure 11 FIG. 1 is a diagram showing light spots of the fluorescence optical system in the first embodiment.

[0104] Depend on Figure 5-Figure 11 As can be seen, the fluorescence optical system in the first embodiment, due to the offsetting negative distortion of the objective lens group and the positive distortion of the eyepiece group, can control the distortion of the fluorescence optical system to within -4.5%, effectively improving image quality and facilitating diagnosis and treatment. The fluorescence optical system also exhibits excellent image brightness, with relative illumination at the edge of the field of view exceeding 80% and no vignetting. When the resolution meets 40 lp / mm in visible light, the full-field contrast value is greater than 0.55, and when the resolution meets 40 lp / mm in fluorescence, the full-field contrast value is greater than 0.38. When focusing in visible light, the fluorescence defocus is less than 0.03mm, achieving clear imaging quality for both visible light and fluorescence, meeting the requirements of fluorescence endoscopy and facilitating improved diagnostic and treatment accuracy. The diffuse spots in the spot diagrams are all smaller than the Airy disk, and the spot diameters are all included within the Airy disk, essentially at the diffraction limit. Short-wave and long-wave chromatic aberrations are converged, demonstrating excellent imaging quality.

[0105] See Figure 12 、 Figure 13 and Figure 14 As shown, Figure 12-Figure 22 Corresponding to the fluorescence optical system in the second embodiment, in the second embodiment, the number of lenses in the objective lens group and the rod lens group, as well as the optical focal length and surface shape of each lens can be the same as those in the first embodiment. The following mainly describes the technical features of the second embodiment that are different from the first embodiment. The technical features not described in the second embodiment can be considered to be the same as the settings of the first embodiment, and can be obtained by referring to the above description of the first embodiment.

[0106] In the second embodiment, the objective lens assembly satisfies the following conditions: -18.45 mm ≤ f(B01) ≤ -7.5 mm; 17.96 mm ≤ f(B02) ≤ 24.64 mm. Here, f(B01) is the focal length of the first cemented lens assembly, and f(B02) is the focal length of the second cemented lens assembly. For example, f(B01) can be -18.45 mm, -15.5 mm, -12.19 mm, -10.05 mm, -8.59 mm, or -7.5 mm, and f(B02) can be 17.96 mm, 19.67 mm, 22.23 mm, 24.64 mm, or the like. When the above-mentioned conditional formula is met, the divergent effect of the first cemented lens group on light and the convergent effect of the second cemented lens group on light can be reasonably configured, which is beneficial to suppressing the distortion of the objective lens group while increasing the field of view angle of the objective lens group, and at the same time 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, and the imaging quality of the objective lens group is improved. At the same time, it is beneficial to improve the phase difference correction of the objective lens group for visible light and fluorescence, reduce the focus deviation of visible light and fluorescence, and make the objective lens group have good imaging quality for both visible light and fluorescence.

[0107] In the second embodiment, the Abbe number of the first lens 2 is 41, the Abbe number of the second lens 3 is 30, the Abbe number of the steering element 4 is 39, and the Abbe number of the third lens 5 is 64. The effects that can be achieved by this design can be obtained by referring to the above description.

[0108] In the second embodiment, the Abbe number of the fourth lens element 6 is 90.3, the Abbe number of the fifth lens element 7 is 23.8, the Abbe number of the sixth lens element 8 is 35, the Abbe number of the seventh lens element 9 is 60.3, the Abbe number of the eighth lens element 10 is 23.8, the Abbe number of the ninth lens element 11 is 90.3, the Abbe number of the tenth lens element 12 is 63.4, and the Abbe number of the eleventh lens element 13 is 23.8. The effects achievable by this design can be understood by referring to the above description.

[0109] Combine Figure 15 As shown, in the second embodiment, the eyepiece assembly includes, from the object side to the image side along the optical axis, a fifteenth lens 17 having positive refractive power, a sixteenth lens 18 having negative refractive power, a seventeenth lens 19 having positive refractive power, an eighteenth lens 20 having negative refractive power, and a nineteenth lens 21 having positive refractive power. The image-side surface of the fifteenth lens 17 is convex, the object-side surface of the sixteenth lens 18 is concave, the image-side surface of the seventeenth lens 19 is convex, and the object-side surface of the eighteenth lens 20 is concave.

[0110] In the above-mentioned eyepiece group, the positive focal power of the fifteenth lens 17 and the convex surface shape on the image side can preliminarily converge the light emitted by the rod lens group, enhance the convergence efficiency of fluorescence, and lay the foundation for the intersection calibration of visible light and fluorescence. The negative focal power of the sixteenth lens 18 and the concave surface shape on the object side can enhance the convergence effect on visible light and preliminarily compensate for the chromatic aberration of visible light and fluorescence. The positive focal power of the seventeenth lens 19 and the convex surface shape on the image side are conducive to correcting the dispersion difference between visible light and fluorescence. The negative focal power of the eighteenth lens 20 and the concave surface shape on the object side can converge divergent light, and at the same time, cooperate with the seventeenth lens 19 and the nineteenth lens 21 to well correct spherical aberration and field curvature. The positive focal power of the nineteenth lens 21 can reasonably transition the light to the image plane.

[0111] Therefore, the above-mentioned eyepiece assembly can achieve good imaging quality for both visible light and fluorescence by reasonably setting the optical power and surface shape of each lens.

[0112] In the second embodiment, the image-side surface of the sixteenth lens 18 is concave, the object-side surface of the seventeenth lens 19 is convex, the image-side surface of the eighteenth lens 20 is concave, and both the object-side and image-side surfaces of the nineteenth lens 21 are convex. Combined with the optical power and surface design of each lens in the eyepiece assembly, this can compensate for the dispersion differences between visible light and fluorescence, correct chromatic aberrations such as coma and astigmatism, and improve the relative illumination of the peripheral field of view. It also helps reduce the tolerance sensitivity of each lens, improving the molding and assembly yield of the eyepiece assembly. In the second embodiment, the object-side surface of the fifteenth lens 17 can be flat.

[0113] In the second embodiment, the fifteenth lens 17, the sixteenth lens 18, the seventeenth lens 19, the eighteenth lens 20, and the nineteenth lens 21 are cemented in sequence to form a fourth cemented lens. The arrangement of the fourth cemented lens group, combined with the optical power and surface design of each lens in the eyepiece assembly, facilitates improved dispersion compensation for visible light and fluorescence, reduces defocus for visible light and fluorescence, and increases relative illumination at the edge of the field of view, thereby enhancing the image quality for visible light and fluorescence. It also facilitates the structural compactness of the eyepiece assembly.

[0114] In the second embodiment, the Abbe number of the fifteenth lens 17 is smaller than that of the sixteenth lens 18, the Abbe number of the seventeenth lens 19 is larger than that of the eighteenth lens 20, and the Abbe number of the eighteenth lens 20 is smaller than that of the nineteenth lens 21. For example, in the second embodiment, the Abbe number of the fifteenth lens 17 is 39.2, the Abbe number of the sixteenth lens 18 is 64.2, the Abbe number of the seventeenth lens 19 is 47.2, the Abbe number of the eighteenth lens 20 is 23.8, and the Abbe number of the nineteenth lens 21 is 31.3. In this way, the Abbe numbers of the various lenses of the eyepiece assembly in the second embodiment can be rationally configured, thereby achieving chromatic aberration compensation for visible light and fluorescence through material chromatic aberration differences, reducing focus deviation of visible light and fluorescence, and improving relative illumination at the edge of the field of view, thereby enabling the eyepiece assembly to achieve excellent imaging quality for both visible light and fluorescence.

[0115] In the second embodiment, the eyepiece assembly further includes a second protective element 24 provided on the image side of the nineteenth lens 21. The second protective element 24 includes but is not limited to flat glass and is used to provide protection for each lens in the eyepiece assembly.

[0116] In the second embodiment, the eyepiece assembly satisfies the conditional equation: 0.6 ≤ f(B04) / CT4 ≤ 0.85; where f(B04) is the focal length of the fourth cemented lens assembly, and CT4 is the thickness of the fourth cemented lens assembly along the optical axis. For example, f(B04) / CT4 can be 0.6, 0.7, 0.8, or 0.85. When this conditional equation is satisfied, the ratio of the focal length to the center thickness of the eyepiece assembly can be optimally configured, optimizing the light converging effect of the eyepiece assembly while also reducing the tolerance sensitivity of each lens in the eyepiece assembly, lowering the difficulty of manufacturing and molding each lens, improving assembly yield, and enhancing the structural compactness of the eyepiece assembly.

[0117] In the second embodiment, the fluorescence optical system satisfies the following conditions: 2.78 mm ≤ f(object) ≤ 3.3 mm; 29 mm ≤ f(B03) ≤ 32 mm; and f(B04) ≤ 16 mm. Here, f(object) is the focal length of the objective lens group, f(B03) is the focal length of the third cemented lens group, and f(B04) is the focal length of the fourth cemented lens group. For example, f(object) can be 2.78 mm, 2.85 mm, 3.05 mm, or 3.3 mm, f(B03) can be 29 mm, 30 mm, 31 mm, or 32 mm, and f(B04) can be 13.92 mm, 14.11 mm, 15.32 mm, or 16 mm. When the above conditions are met, the focal lengths of the objective lens group, the rod lens group and the eyepiece group can be reasonably configured, which is beneficial to expanding the depth of field of the fluorescence optical system. At the same time, the objective lens group produces negative distortion, which can compensate for the positive distortion produced by the eyepiece group, effectively suppress the distortion of the fluorescence optical system, and improve the imaging quality. In addition, the focal length of the rod lens group can be well adapted to the objective lens group and the eyepiece group, thereby improving the consistency and efficiency of image transmission. Through the reasonable design of the focal lengths of the objective lens group, the rod lens group and the eyepiece group, the structural compactness of the fluorescence optical system can also be improved, and the maximum insertion width of the fluorescence optical system can be reduced, thereby reducing the damage to the patient during the use of the endoscope.

[0118] In a second embodiment, the rod lens assembly satisfies the following conditions: 1mm ≤ T3 ≤ 5mm; 1mm ≤ T4 ≤ 8mm; where T3 is the distance on the optical axis between the third and symmetrical cemented lens groups in each rod lens assembly, and T4 is the distance on the optical axis between two adjacent rod lens groups. For example, T3 can be 1mm, 2mm, 3mm, 4mm, or 5mm, and T4 can be 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, or 8mm. When the above conditions are met, the distance between the third and fourth cemented lens groups is appropriate, effectively offsetting the aberrations of the third and fourth cemented lens groups, improving the image quality of the rod lens assembly, and also contributing to a more compact structure of the rod lens assembly. Furthermore, it facilitates smooth light transitions between multiple rod lens groups, which also contributes to improved image quality of the rod lens assembly.

[0119] See Figure 16-Figure 22 As shown, Figure 16 is a transfer function (MTF) curve of the fluorescence optical system in the second embodiment under visible light (0.435um-0.656um), Figure 17 : is the defocus curve of the fluorescence optical system in the second embodiment at 40lp / mm under visible light (0.435um-0.656um), Figure 18 is a transfer function curve of the fluorescence optical system in the second embodiment under fluorescence (0.830 μm), Figure 19is a defocus curve diagram of the fluorescence optical system at 40lp / mm under fluorescence (0.830um) in the second embodiment, Figure 20 is the relative illumination diagram of the fluorescence optical system in the second embodiment, Figure 21 is a graph showing the field curvature and distortion of the fluorescence optical system in the second embodiment. Figure 22 FIG. 4 is a light spot diagram of the fluorescence optical system in the second embodiment.

[0120] Depend on Figure 16-Figure 22 As can be seen, the fluorescence optical system in the second embodiment, due to the offsetting negative distortion of the objective lens group and the positive distortion of the eyepiece group, can control the distortion of the fluorescence optical system to within -4.4%, effectively improving image quality and facilitating diagnosis and treatment. The fluorescence optical system also exhibits excellent image brightness, with relative illumination at the edge of the field of view exceeding 80% and no vignetting. When the resolution meets 40 lp / mm in visible light, the full-field contrast value is greater than 0.55, and when the resolution meets 40 lp / mm in fluorescence, the full-field contrast value is greater than 0.38. When focusing in visible light, the fluorescence defocus is less than 0.035mm, achieving clear imaging quality for both visible light and fluorescence, meeting the requirements of fluorescence endoscopy and facilitating improved diagnostic and treatment accuracy. The diffuse spots in the spot diagrams are all smaller than the Airy disk, and the spot diameters are all included within the Airy disk, essentially at the diffraction limit. Short-wave and long-wave chromatic aberrations are converged, demonstrating excellent imaging quality.

[0121] Based on the fluorescence optical system described in any of the above embodiments, the present application further provides an endoscope, comprising a structural component and a fluorescence optical system as described in any of the above embodiments. The structural component may be a physical support structure for the fluorescence optical system. Endoscopes include, but are not limited to, fluorescent laparoscopic endoscopes, fluorescent thoracoabdominal endoscopes, and the like. By employing the above-described fluorescence optical system in an endoscope, the endoscope can achieve good imaging quality for both infrared and visible light, thereby improving the accuracy of diagnosis and treatment.

[0122] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned 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.

[0123] The above-described embodiments merely represent several implementation methods of the present application. 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 a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. An objective lens assembly, characterized in that: The optical system comprises, from the object side to the image side along the optical axis, a first lens having negative optical power, a second lens having negative optical power, a third lens having positive optical power, a fourth lens having positive optical power, a fifth lens having positive optical power, a sixth lens having negative optical power, a seventh lens having positive optical power, an eighth lens having negative optical power, a ninth lens having negative optical power, a tenth lens having positive optical power, and an eleventh lens having 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 third lens is convex. The image-side surface of the sixth lens is concave. The image-side surface of the ninth lens is concave. Both the object-side surface and the image-side surface of the tenth lens are convex.

2. The objective lens assembly according to claim 1, wherein: The objective lens assembly 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 sequentially cemented to form a first cemented lens assembly. 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 to form a second cemented lens assembly. in: The objective lens group satisfies the following conditional formula: -18.45mm≤f(B01)≤-8.59mm; 17.96mm≤f(B02)≤24.64mm; 0.6≤f(B02) / CT2≤0.8; 2.78mm≤f(object)≤3.3mm; Wherein, 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, and f(object) is the focal length of the objective lens group; or, The objective lens group satisfies the following conditional formula: -18.45mm≤f(B01)≤-7.5mm; 17.96mm≤f(B02)≤24.64mm; 2.78mm≤f(object)≤3.3mm; Wherein, 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 f(object) is the focal length of the objective lens group.

3. The objective lens assembly according to claim 1, characterized in that: The image-side surface of the second lens is concave, the object-side surface of the fourth lens is convex, and the image-side surface is concave, the object-side surface and the image-side surface of the fifth lens are both convex, the object-side surface of the sixth lens is concave, the object-side surface and the image-side surface of the seventh lens are both convex, the object-side surface of the eighth lens is concave, and the image-side surface is convex, the object-side surface of the ninth lens is concave, and the object-side surface of the eleventh lens is concave, and the image-side surface is convex; and / or, The Abbe number of the fourth lens is greater than that of the fifth lens, the Abbe number of the sixth lens is smaller than that of the seventh lens, the Abbe number of the eighth lens is smaller 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 group also includes a steering element and an aperture stop, the steering element is arranged between the second lens and the fifth lens, the aperture stop is arranged between the steering element and the third lens, the Abbe number of the first lens is greater than the Abbe number of the second lens, and the Abbe number of the steering element is smaller than the Abbe number of the third lens.

4. A fluorescence optical system, characterized in that: It comprises a rod lens group, an eyepiece group and the objective lens group according to any one of claims 1 to 3, wherein the objective lens group, the rod lens group and the eyepiece group are arranged in sequence along the direction of light propagation, and the rod lens group and the eyepiece group each comprise a plurality of lenses with optical power.

5. The fluorescence optical system according to claim 4, characterized in that: The eyepiece assembly comprises, in order from the object side to the image side along the optical axis, a fifteenth lens having negative refractive power, a sixteenth lens having positive refractive power, a seventeenth lens having negative refractive power, an eighteenth lens having positive refractive power, a nineteenth lens having negative refractive power, a twentieth lens having positive refractive power, and a twenty-first lens having positive refractive power; The object side surface of the fifteenth lens is convex, and the image side surface is concave, the object side surface and the image side surface of the sixteenth lens are both convex, the object side surface and the image side surface of the seventeenth lens are both concave, the object side surface and the image side surface of the eighteenth lens are both convex, the object side surface and the image side surface of the nineteenth lens are both concave, the object side surface and the image side surface of the twentieth lens are convex, and the image side surface is concave, and the object side surface and the image side surface of the twenty-first lens are both convex.

6. The fluorescence optical system according to claim 5, characterized in that: 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 in sequence to form a fourth cemented lens group, and the fluorescence optical system satisfies the following conditional formula: f(B04)≤17.85mm; 0.7≤f(B04) / CT4≤0.9; 29mm≤f(B03)≤31mm; Wherein, f(B04) is the focal length of the fourth cemented lens group, CT4 is the thickness of the fourth cemented lens group on the optical axis, and f(B03) is the focal length of the third cemented lens group; and / or, The Abbe number of the fifteenth lens is greater than that of the sixteenth lens, the Abbe number of the seventeenth lens is smaller than that of the eighteenth lens, the Abbe number of the nineteenth lens is smaller than that of the twentieth lens, and the Abbe number of the twentieth lens is greater than that of the twenty-first lens.

7. The fluorescence optical system according to claim 4, wherein: The eyepiece assembly includes, in order from the object side to the image side along the optical axis, a fifteenth lens having positive refractive power, a sixteenth lens having negative refractive power, a seventeenth lens having positive refractive power, an eighteenth lens having negative refractive power, and a nineteenth lens having positive refractive power; The image side surface of the fifteenth lens is convex, the object side surface and the image side surface of the sixteenth lens are both concave, the object side surface and the image side surface of the seventeenth lens are both convex, the object side surface and the image side surface of the eighteenth lens are both concave, and the object side surface and the image side surface of the nineteenth lens are both convex.

8. The fluorescence optical system according to claim 7, wherein: The fifteenth lens, the sixteenth lens, the seventeenth lens, the eighteenth lens, and the nineteenth lens are cemented in sequence to form a fourth cemented lens, and the fluorescence optical system satisfies the following conditional formula: f(B04)≤16mm; 0.6≤f(B04) / CT4≤0.85; 29mm≤f(B03)≤32mm; Wherein, f(B04) is the focal length of the fourth cemented lens group, CT4 is the thickness of the fourth cemented lens group on the optical axis, and f(B03) is the focal length of the third cemented lens group; and / or, The Abbe number of the fifteenth lens is smaller than that of the sixteenth lens, the Abbe number of the seventeenth lens is larger than that of the eighteenth lens, and the Abbe number of the eighteenth lens is smaller than that of the nineteenth lens.

9. The fluorescence optical system according to claim 4, wherein: The rod lens group includes a plurality of rod lenses sequentially arranged 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; The third cemented lens group includes a twelfth lens with positive focal power, a thirteenth lens with negative focal power, and a fourteenth lens with positive focal power; the object-side surface and the image-side surface of the twelfth lens are both convex surfaces, the object-side surface and the image-side surface of the thirteenth lens are both concave surfaces, and the object-side surface and the image-side surface of the fourteenth lens are both convex surfaces.

10. An endoscope, characterized in that: Comprising the fluorescence optical system according to any one of claims 4 to 9.

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