Optical system and fluorescent endoscope

Abstract

The utility model relates to an optical system which comprises an eyepiece assembly and an objective lens assembly arranged on the object side of the eyepiece assembly. The objective lens assembly comprises a first lens with negative focal power, a second lens with negative focal power, a third lens with positive focal power, a first cemented lens group with negative focal power and a second cemented lens group with positive 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 second lens is a concave surface, and the object side surface of the third lens is a convex surface. The image side surface of the third lens is a convex surface, the first glued lens group comprises a fourth lens, a fifth lens and a sixth lens which are glued in sequence, the fourth lens has positive focal power, the fifth lens has negative focal power, and the sixth lens has negative focal power. The optical system can correct aberration such as distortion, chromatic aberration and field curvature, and has good imaging quality.

Description

Technical Field

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

[0002] Fluorescent endoscopes can enter the human body through natural channels or minimally invasive incisions, and are used to diagnose or treat the inside of the human body. Fluorescent endoscopes can work with fluorescent optical systems to focus and image visible light and near-infrared light at the same time. By injecting fluorescent contrast agents such as indocyanine green (ICG) into the patient's body and binding to plasma proteins, when illuminated by 780nm-810nm illumination light, the fluorescent contrast agent can be excited to emit 820nm-840nm near-infrared light. The optical system simultaneously captures images of visible light and near-infrared light, allowing doctors to clearly distinguish between lesions and normal areas, improving the accuracy of surgery.

[0003] However, the optical system used in the fluorescence endoscope in the related art has serious aberrations such as distortion and poor imaging quality, which affects the accuracy of diagnosis and treatment. Summary of the invention

[0004] Based on this, it is necessary to provide an optical system and a fluorescent endoscope to address the problems in the related art of serious aberrations such as distortion and poor imaging quality of the optical system used in fluorescent endoscopes, which affect the accuracy of diagnosis and treatment.

[0005] According to one aspect of the present application, an optical system is provided, comprising:

[0006] an eyepiece assembly having optical power;

[0007] The objective lens assembly is arranged on the light incident side of the eyepiece assembly, and the objective lens assembly comprises:

[0008] A first lens having negative optical power, wherein the object-side surface of the first lens is convex and the image-side surface is concave;

[0009] a second lens having negative optical power, wherein the image side surface of the second lens is a concave surface;

[0010] a third lens having positive refractive power, wherein the image side surface of the third lens is a convex surface;

[0011] a first cemented lens group with negative optical power, wherein the first cemented lens group comprises a fourth lens, a fifth lens and a sixth lens cemented in sequence, the fourth lens has positive optical power, the fifth lens has negative optical power, and the sixth lens has negative optical power;

[0012] a seventh lens having positive refractive power; and a second cemented lens group having positive refractive power.

[0013] In one embodiment, the objective lens assembly satisfies:

[0014] 6≤FW1 / CT2≤6.5;

[0015] Wherein, FW1 is the focal length of the objective lens assembly, and CT2 is the thickness of the second lens on the optical axis.

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

[0017] 5≤|f1 / CT1|≤7; and / or,

[0018] 2.5≤f3 / CT3≤3; and / or,

[0019] 2.5≤f7 / CT7≤4;

[0020] Among them, f1 is the effective focal length of the first lens, CT1 is the thickness of the first lens on the optical axis, f3 is the effective focal length of the third lens, CT3 is the thickness of the third lens on the optical axis, f7 is the effective focal length of the seventh lens, and CT7 is the thickness of the seventh lens on the optical axis.

[0021] In one embodiment, the object side surface and the image side surface of the fourth lens are both convex surfaces, the object side surface of the fifth lens is concave, the image side surface is convex, and the object side surface and the image side surface of the sixth lens are both concave surfaces; and / or,

[0022] The objective lens assembly satisfies: 1.8≤Vd5 / Vd6≤2.2; wherein Vd5 is the Abbe number of the fifth lens, and Vd6 is the Abbe number of the sixth lens.

[0023] In one embodiment, the second cemented lens group includes an eighth lens and a ninth lens cemented in sequence, the eighth lens has positive focal power, and the ninth lens has negative focal power;

[0024] The object side surface and the image side surface of the eighth lens are both convex surfaces, the object side surface of the ninth lens is concave, and the image side surface is convex; and / or,

[0025] The objective lens assembly satisfies: 1.8≤CT8 / CT9≤2.5; wherein CT8 is the thickness of the eighth lens on the optical axis, and CT9 is the thickness of the ninth lens on the optical axis.

[0026] In one embodiment, the optical system further comprises a rod lens assembly, wherein the rod lens assembly is disposed between the objective lens assembly and the eyepiece lens assembly along the optical path;

[0027] The rod mirror assembly includes a plurality of groups of rod mirrors sequentially arranged along the optical axis, each group of rod mirrors includes a third glued lens group and a fourth glued lens group with optical power, and the third glued lens group and the fourth glued lens group are mirror-symmetrical about a plane perpendicular to the optical axis.

[0028] In one embodiment, the third cemented lens group comprises a tenth lens and an eleventh lens cemented together; the tenth lens has positive focal power, the object side surface and the image side surface of the tenth lens are both convex surfaces, the eleventh lens has negative focal power, the object side surface of the eleventh lens is concave, and the image side surface is convex; and / or,

[0029] The third cemented lens group includes a tenth lens and an eleventh lens cemented together; the rod lens assembly satisfies: 8≤CT10 / CT11≤9; wherein CT10 is the thickness of the tenth lens on the optical axis, and CT11 is the thickness of the eleventh lens on the optical axis.

[0030] In one embodiment, the optical system satisfies: fM≤10mm; wherein fM is the effective focal length of the eyepiece assembly; and / or,

[0031] The eyepiece assembly comprises, in sequence from the object side to the image side along the optical axis, a twelfth lens with negative optical power, a thirteenth lens with positive optical power, and a fifth cemented lens group, the fifth cemented lens group comprises a fourteenth lens and a fifteenth lens, the fourteenth lens has positive optical power, and the fifteenth lens has negative optical power.

[0032] In one embodiment, when the eyepiece assembly includes the twelfth to fifteenth lenses, the eyepiece assembly satisfies:

[0033] 5≤|f12 / CT12|≤6; and / or,

[0034] 5≤f13 / CT13≤7; and / or,

[0035] 2≤CT15 / CT14≤2.8;

[0036] Among them, f12 is the effective focal length of the twelfth lens, CT12 is the thickness of the twelfth lens on the optical axis, f13 is the effective focal length of the thirteenth lens, CT13 is the thickness of the thirteenth lens on the optical axis, CT15 is the thickness of the fifteenth lens on the optical axis, and CT14 is the thickness of the fourteenth lens on the optical axis.

[0037] According to another aspect of the present application, a fluorescence endoscope is provided, comprising the above-mentioned optical system.

[0038] In the above optical system, when light enters, it first passes through the first lens and the second lens. By setting the first lens with negative optical power and a convex surface on the object side and a concave surface on the image side and the second lens with negative optical power and a concave surface on the image side, a wide range of field light can be obtained, which is beneficial to improving the endoscope imaging range. At the same time, the large field light can be smoothly transitioned to the rear lens group, which is beneficial to reasonably constraining the overall light trend of the optical system, and is beneficial to suppressing the generation of aberrations such as distortion, and reducing the burden of the light deflected by each lens on the image side of the second lens, so as to reduce the aberration sensitivity and tolerance sensitivity of the optical system, improve the imaging quality of the optical system, reduce the difficulty of preparation, and improve the molding yield. The third lens with positive optical power is mainly used to converge the light from the second lens, and the setting of the image side of the third lens as a convex surface is beneficial to shortening the axial size of the optical system. At the same time, the smoothness of light propagation can be further improved by cooperating with the first lens and the second lens, which can reduce the design and molding difficulty of each lens, and is beneficial to reducing the aberration sensitivity and tolerance sensitivity of the objective lens assembly, which is beneficial to improving the imaging quality of the objective lens assembly. The bonding design of the three lenses in the first bonded lens group is further conducive to shortening the axial size of the optical system, and the design of the optical power of the three lenses can effectively correct the chromatic aberration of the optical system and improve the imaging quality of the objective lens assembly. The seventh lens can converge and converge the light transmitted from the first bonded lens group, further integrate the light to improve the imaging quality. In other words, the seventh lens with positive optical power can reasonably constrain the transmission path of the light in conjunction with the first bonded lens group, which is conducive to compensating for aberrations such as meridian coma and distortion, and improving the imaging quality of the optical system. The second bonded lens group with negative optical power further shortens the axial size of the optical system, and is conducive to correcting the Petzval field curvature and astigmatism of the objective lens assembly, thereby improving the imaging quality of the objective lens assembly.

[0039] The optical system of the present application, through the coordination of the positive and negative optical powers of the lens in the objective lens assembly, and the design of the concave and convex surface of the lens, can make the light propagate smoothly, and at the same time correct aberrations such as distortion, chromatic aberration, and field curvature to improve the imaging quality of the optical system. On this basis, the spacing and gluing conditions of each lens are reasonably designed to make the optical system compact and conducive to its miniaturized design. The optical system of the present application can also increase the depth of field of the optical system, reduce the defocusing condition of the fluorescence band, so that the objective lens assembly can have good imaging quality for both visible light and near-infrared light, which is conducive to clearly distinguishing the lesion site and the normal site, and improving the accuracy of diagnosis and treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A schematic diagram of the structure of an optical system in some embodiments of the present application is shown.

[0041] Figure 2 A schematic diagram of the structure of the objective lens assembly in some embodiments of the present application is shown.

[0042] Figure 3 A schematic diagram of the structure of the eyepiece assembly in some embodiments of the present application is shown.

[0043] Figure 4 A schematic structural diagram of a rod mirror assembly in some embodiments of the present application is shown.

[0044] Figure 5 The modulation transfer function curve of the optical system in the first embodiment in the visible light band is shown.

[0045] Figure 6 The spot diagram of the optical system in the visible light band in the first embodiment is shown.

[0046] Figure 7 The field curvature and distortion curves of the optical system in the visible light band in the first embodiment are shown.

[0047] Figure 8 The modulation transfer function curve of the optical system in the fluorescence band in the first embodiment is shown.

[0048] Fig. 9 The spot diagram of the optical system in the fluorescence band in the first embodiment is shown.

[0049] Fig.10 The field curvature and distortion curves of the optical system in the fluorescence band in the first embodiment are shown.

[0050] Fig.11 The modulation transfer function curve of the optical system in the visible light band in the second embodiment is shown.

[0051] Fig.12 The spot diagram of the optical system in the visible light band in the second embodiment is shown.

[0052] Fig.13 The field curvature and distortion curves of the optical system in the visible light band in the second embodiment are shown.

[0053] Fig.14 The modulation transfer function curve of the optical system in the second embodiment in the fluorescence band is shown.

[0054] Fig.15 The spot diagram of the optical system in the fluorescence band in the second embodiment is shown.

[0055] Fig.16 The field curvature and distortion curves of the optical system in the fluorescence band in the second embodiment are shown.

[0056] Description of Figure Numbers:

[0057] 10. Optical system; 100. Objective lens assembly; L1. First lens; L2. Second lens; L3. Third lens; 110. First cemented lens group; L4. Fourth lens; L5. Fifth lens; L6. Sixth lens; L7. Seventh lens; 120. Second cemented lens group; L8. Eighth lens; L9. Ninth lens; 130. First protective element; 140. Steering element; 200. Rod lens assembly; 210. Third cemented lens group; L10. Tenth lens; L11. Eleventh lens; 220. Fourth cemented lens group; 300. Eyepiece assembly; L12. Twelfth lens; L13. Thirteenth lens; 310. Fifth cemented lens group; L14. Fourteenth lens; L15. Fifteenth lens; 320. Second protective element; N. Optical axis. DETAILED DESCRIPTION

[0058] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0059] In the description of the present 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 the present 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 the present application.

[0060] In addition, if the terms "first" or "second" appear, these terms are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, if the term "plurality" appears, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0061] In this application, unless otherwise clearly specified and limited, if the terms "installed", "connected", "connected", "fixed" and the like appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0062] In the present application, unless otherwise clearly specified and limited, if there is a description that a first feature is "above" or "below" a second feature, etc., or similar descriptions appear, it 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. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0063] 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 a central 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 a central element at the same time. 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 implementation method.

[0064] Endoscopes enter the human body through minimally invasive incisions to observe tissues, diagnose diseased tissues, or perform minimally invasive surgery. Endoscopes are used on surgical patients in a completely painless manner with a cold light source and a camera system. They can directly and clearly observe the patient's abdominal cavity, understand the pathogenic factors, and perform surgical treatment for abnormal conditions.

[0065] The fluorescence endoscope has the functions of laparoscopic endoscope imaging system and fluorescence angiography imaging system, providing real-time true high-definition white light and high-definition fluorescence imaging system for laparoscopic surgery. By injecting the fluorescent contrast agent ICG (indocyanine green) into the patient's body, ICG enters the body and combines with plasma proteins. It is stimulated by external light with a wavelength of 780 to 810 nm emitted by the fluorescence laparoscope, and near-infrared light with a wavelength of about 820 to 840 nm is emitted. The fluorescence image received by the fluorescence endoscope is displayed on the monitor, and the doctor can clearly distinguish the lesion site from the normal site, which improves the accuracy of the operation.

[0066] However, the fluorescence endoscope in the related art has insufficient depth of field, large aberration and poor light imaging quality.

[0067] Based on this, the present application provides an optical system 10 and a fluorescent endoscope, which can correct aberrations such as distortion, chromatic aberration, and field curvature to improve the imaging quality of the objective lens assembly 100.

[0068] See also Figure 1 As shown, the optical system 10 provided by the present application can be applied to medical devices such as endoscopes, such as fluorescent laparoscopes, etc., which includes an eyepiece assembly 300, an objective lens assembly 100 and a rod lens assembly 200. The light passes through the eyepiece assembly 300, the rod lens assembly 200 and the objective lens assembly 100 in sequence to form an image. The objective lens assembly 100 is used to collect light, and the rod lens assembly 200 transmits the light collected by the objective lens assembly 100 to the eyepiece assembly 300. The optical system 10 of the present application can also be equipped with an optical adapter, the effective focal length of the optical adapter includes but is not limited to 32mm, the eyepiece assembly 300 is used to magnify the image and transmit it to the optical adapter, and the optical adapter can adjust the light and transmit it to the image sensor. The optical adapter can use any suitable adapter lens, which is not limited here.

[0069] Combined with reference Figure 2 As shown, the objective lens assembly 100 of the optical system 10 is arranged on the light incident side of the eyepiece assembly 300, and the objective lens assembly 100 includes a first lens L1, a second lens L2, a third lens L3, a first cemented lens group 110, a seventh lens L7 and a second cemented lens group 120 arranged in sequence along the optical axis N. The first lens L1 has negative optical power, and the object side surface of the first lens L1 is convex, and the image side surface is concave. It can be understood that when the light enters the objective lens assembly 100, it first passes through the first lens L1 and the second lens L2. By arranging the first lens with negative optical power, the object side surface is convex, and the image side surface is concave, and the second lens with negative optical power and the image side surface is concave, a wide range of field light can be obtained, which is beneficial to improving the imaging range of the endoscope. At the same time, the large field light can be smoothly transitioned to the rear lens group, which is beneficial to reasonably constraining the overall light trend of the optical system, suppressing the generation of aberrations such as distortion, and reducing the burden of light deflection of each lens on the image side of the second lens, thereby reducing the aberration sensitivity and tolerance sensitivity of the optical system, improving the imaging quality of the optical system, reducing the difficulty of preparation, and improving the molding yield.

[0070] The second lens L2 smoothly transfers the large-field light collected by the first lens L1 to the rear lens group, making the overall light trend of the objective lens assembly 100 smoother and gentler, reducing the degradation of imaging quality caused by assembly errors of various lenses or parts in the objective lens assembly 100, improving the assembly fault tolerance, and avoiding the degradation of imaging quality caused by loosening or misalignment of parts due to long-term use, that is, the service life of the fluorescent endoscope can be improved.

[0071] In some embodiments, the objective lens assembly 100 satisfies, or the first lens L1 satisfies: 5≤|f1 / CT1|≤7, wherein f1 is the effective focal length of the first lens L1, and CT1 is the thickness of the first lens L1 on the optical axis N. By configuring the ratio of the effective focal length and the center thickness of the first lens L1L1, while being able to obtain a wide range of field angles, the axial dimension of the first lens L1L1 is shortened as much as possible, so as to facilitate further miniaturization of the objective lens assembly 100 and improve the success rate of designing and molding the first lens L1L1.

[0072] In some embodiments, the objective lens assembly 100 satisfies, or the second lens L2 satisfies: 6≤|FW1 / CT2|≤6.5, wherein FW1 is the focal length of the objective lens assembly 100, and CT2 is the thickness of the second lens L2 on the optical axis N. This improves the smoothness of light passing through the objective lens assembly 100, making the overall light trend smoother.

[0073] In some embodiments, the object side surface of the second lens L2 is a plane, and can be configured to be bonded with the first lens L1, so as to improve the integrity of the objective lens assembly 100, reduce the difficulty of lens installation of the objective lens assembly 100, and reduce the risk of poor light imaging quality caused by improper installation. Combined with the above-mentioned optical power and surface design of the second lens L2, the second lens L2 can improve the smoothness of the overall light trend of the objective lens assembly 100, eliminate aberrations, facilitate miniaturization, and reduce the difficulty of installation.

[0074] Among them, the gluing setting in the present application is not limited to the limitation of the gluing process. The two lenses can be glued together by optical glue or by other structural parts and other connection methods to be relatively fixed, which will not be repeated here.

[0075] The third lens L3 has positive focal power, and its image side surface is convex. The third lens L3 with positive focal power is mainly used to converge the light from the second lens L2. The setting of the image side surface of the third lens L3 as a convex surface is conducive to shortening the axial size of the objective lens assembly 100. At the same time, it can further improve the smoothness of light propagation in cooperation with the first lens L1 and the second lens L2, and can reduce the design and molding difficulty of each lens, and is conducive to reducing the aberration sensitivity and tolerance sensitivity of the objective lens assembly 100, which is conducive to improving the imaging quality of the objective lens assembly 100.

[0076] In some embodiments, the objective lens assembly 100 satisfies, or the third lens L3 satisfies: 2.5≤f3 / CT3≤3. While the third lens L3 is used to constrain the direction of the light path and suppress the phase difference, the axial size of the third lens L3 is reasonably set, which is convenient for designing the surface shape of the third lens L3 and is beneficial to the molding of the third lens L3.

[0077] The objective lens assembly 100 further includes a steering element 140 disposed between the second lens L2 and the third lens L3. The steering element 140 is used to deflect the light path at a certain angle. In some embodiments, the steering element 140 includes but is not limited to a steering flat crystal, or a steering prism formed by gluing a plurality of prisms. The angle at which the steering element 140 deflects the light path includes but is not limited to 15°, 30°, 45°, etc., so that the objective lens assembly 100 can adapt to the imaging angle of the endoscope. In some embodiments, the object side surface and the image side surface of the steering element 140 are planes, the object side surface of the third lens L3 is a plane, and the second lens L2, the steering element 140 and the third lens L3 are glued in sequence, so that the axial size of the objective lens assembly 100 can be reduced, the compactness of the structure of the objective lens assembly 100 can be improved, and the optical path matching degree of the object side and the image side of the steering element 140 can be improved, and the imaging quality of the objective lens assembly 100 can be improved.

[0078] Continue reading Figure 1 and Figure 2 As shown, the first cemented lens group 110 includes a fourth lens L4, a fifth lens L5 and a sixth lens L6 which are cemented in sequence, the fourth lens L4 has positive focal power, the fifth lens L5 has negative focal power, and the sixth lens L6 has negative focal power. The cementation of the fourth lens L4, the fifth lens L5 and the sixth lens L6 enables the first cemented lens group 110 to have negative focal power, and can effectively correct the chromatic aberration of the objective lens assembly 100, thereby improving the imaging quality of the objective lens assembly 100. At the same time, the cementation design of the three lenses in the first cemented lens group 110 is further conducive to shortening the axial dimension of the objective lens assembly 100.

[0079] In some embodiments, the object side surface and the image side surface of the fourth lens L4 are both convex, the object side surface and the image side surface of the fifth lens L5 are concave, and the object side surface and the image side surface of the sixth lens L6 are both concave. Combined with the bonding design and optical power matching design of the fourth lens L4, the fifth lens L5 and the sixth lens L6, the chromatic aberration of the objective lens assembly 100 can be effectively corrected, and the imaging quality of the objective lens assembly 100 for visible light and near-infrared light can be improved.

[0080] In some embodiments, the objective lens assembly 100 satisfies: 1.8≤Vd5 / Vd6≤2.2; wherein Vd5 is the Abbe number of the fifth lens L5, and Vd6 is the Abbe number of the sixth lens L6. The above conditional formula is helpful to improve the ability of the first cemented lens group 110 to correct the chromatic aberration of the objective lens assembly 100, thereby improving the imaging quality of the optical system 10.

[0081] In conjunction with the design of the optical power of the three lenses of the first cemented lens group 110, the seventh lens L7 is configured to have positive optical power, which converges and focuses the light transmitted from the first cemented lens group 110, further integrates the light and improves the imaging quality. In other words, the seventh lens L7 with positive optical power, in conjunction with the first cemented lens group 110, can reasonably constrain the transmission path of the light, which is beneficial to compensate for aberrations such as meridional coma and distortion, and improve the imaging quality of the objective lens assembly 100.

[0082] In some embodiments, the objective lens assembly 100 satisfies, or the seventh lens L7 satisfies: 2.5≤f7 / CT7≤4, wherein f7 is the effective focal length of the seventh lens L7, and CT7 is the thickness of the seventh lens L7 on the optical axis N. By reasonably configuring the ratio of the effective focal length and the center thickness of the seventh lens L7 as described above, the seventh lens L7 can reasonably constrain the optical path trend and compensate for aberrations such as meridian coma and distortion. At the same time, it is also beneficial to compress the axial size of the seventh lens L7, and the surface shape of the seventh lens L7 will not be too extreme, which is beneficial to the design and molding of the seventh lens L7.

[0083] The second cemented lens group 120 has positive optical power. The second cemented lens group 120 includes an eighth lens L8 and a ninth lens L9 that are cemented in sequence. The eighth lens L8 has positive optical power, and the ninth lens L9 has negative optical power. The cemented design of the two lenses in the second cemented lens group 120 is combined with the positive and negative optical power, which further shortens the axial size of the objective lens assembly 100, and is conducive to correcting the Petzval field curvature and astigmatism of the objective lens assembly 100, thereby improving the imaging quality of the objective lens assembly 100.

[0084] In some embodiments, the object side surface and the image side surface of the eighth lens L8 are both convex, and the object side surface of the ninth lens L9 is concave, and the image side surface is convex, which is beneficial to correct aberrations such as Petzval field curvature and astigmatism of the objective lens assembly 100, thereby improving the imaging quality of the objective lens assembly 100.

[0085] In some embodiments, the objective lens assembly 100 satisfies: 1.8≤CT8 / CT9≤2.5; wherein CT8 is the thickness of the eighth lens L8 on the optical axis N, and CT9 is the thickness of the ninth lens L9 on the optical axis N, thereby being able to suggest not to improve the structural compactness of the objective lens assembly 100, facilitating the realization of miniaturized design, and being conducive to correcting aberrations such as Petzval field curvature and astigmatism through the second cemented lens group 120.

[0086] The objective lens assembly 100 of the present application can correct aberrations such as distortion, chromatic aberration, and field curvature by matching the positive and negative focal powers of the lens and designing the concave and convex surfaces of the lens, and at the same time, the light can be further propagated smoothly, so as to further improve the imaging quality of the objective lens assembly 100. On this basis, the spacing and gluing conditions of each lens are reasonably designed, so that the objective lens assembly 100 has a compact structure, which is conducive to its miniaturized design. In addition, the objective lens assembly 100 of the present application can also increase the depth of field of the objective lens assembly 100, reduce the defocusing condition of the fluorescence band, so that the objective lens assembly 100 can have good imaging quality for both visible light and near-infrared light, which is conducive to clearly distinguishing the lesion site and the normal site, and improving the accuracy of diagnosis and treatment.

[0087] In some embodiments, the object side surface of the first lens L1 is an aspherical surface, and the image side surface of the first lens L1 and the object side surface and image side surface of the second lens L2 to the ninth lens L9 are all spherical surfaces. When light enters the optical system 10, it first enters the first lens L1, and is collected by the first lens L1 and propagates to the subsequent optical elements. The use of the aspherical first lens L1 is conducive to obtaining good incident light, improving the clarity of the image detected by the fluorescent endoscope, and is conducive to clearly distinguishing the lesion site from the normal site. In addition, the setting of the aspherical surface of the first lens L1 can enrich the adjustment ability of the first lens L1 to the light, so that the first lens L1 can suppress the generation of aberrations such as distortion while collecting light, thereby helping to improve the imaging quality of the optical system 10. Setting the remaining lenses except the first lens L1 as spherical surfaces is conducive to reducing the design and manufacturing difficulty of the optical system 10, and is also conducive to reducing the aperture of the optical system 10, thereby facilitating the assembly of the optical system 10 in a wide-spectrum endoscope, improving assembly efficiency, and reducing damage to patients during surgery.

[0088] In some embodiments, the effective focal length of the objective lens assembly 100 is 3mm-4mm, the maximum field of view angle is greater than or equal to 75°, the distortion is less than 10%, and the focal length control of the objective lens assembly 100 is less than 10%, which can collect large-angle light and achieve good imaging quality.

[0089] See also Figure 3As shown, the eyepiece assembly 300 of the optical system 10 of the present application includes, from the object side to the image side along the optical axis N, a twelfth lens L12 having negative optical power, a thirteenth lens L13 having positive optical power, and a fifth cemented lens group 310. The fifth cemented lens group 310 includes a fourteenth lens L14 and a fifteenth lens L15. The fourteenth lens L14 has positive optical power, and the fifteenth lens L15 has negative optical power. In some embodiments, the object side surface of the twelfth lens L12 is concave, and the image side surface is convex, the object side surface of the thirteenth lens L13 is concave, and the image side surface is convex, the object side surface and the image side surface of the fourteenth lens L14 are both convex, and the object side surface of the fifteenth lens L15 is concave, and the image side surface is convex. With such arrangement, through reasonable matching of the optical focal length and surface shape of each lens of the eyepiece assembly 300, multiple aberrations such as distortion and chromatic aberration can be effectively corrected, and the eyepiece assembly 300 arranged as above can improve the smoothness of the emitted light and the imaging quality, and can also roughly convert the light transmitted by the rod mirror assembly 200 into parallel light for emission, which can improve the imaging quality while increasing the magnification.

[0090] In some embodiments, the optical system 10, or the eyepiece assembly 300 satisfies: fM≤10mm, where fM is the effective focal length of the eyepiece assembly 300, so that the eyepiece assembly 300 can form a good match with the objective lens assembly 100 and the rod lens assembly 200, and the magnification can be improved and the imaging quality can be improved.

[0091] In some embodiments, the eyepiece assembly 300 satisfies: 5≤|f12 / CT12|≤6, wherein f12 is the effective focal length of the twelfth lens L12, and CT12 is the thickness of the twelfth lens L12 on the optical axis N, which is conducive to achieving the beam expansion effect and improving the light flatness. The eyepiece assembly 300 also satisfies: 5≤f13 / CT13≤7, wherein f13 is the effective focal length of the thirteenth lens L13, and CT13 is the thickness of the thirteenth lens L13 on the optical axis N, which is conducive to the cooperation between the twelfth lens L12 and the thirteenth lens L13, suppressing various aberrations while meeting the magnification requirements, and improving the effective focal length of the optical system 10. At the same time, it is also conducive to compressing the on-axis size of the eyepiece assembly 300, realizing a miniaturized design, and facilitating the design and molding of the lens. The eyepiece assembly 300 also satisfies: 2≤CT15 / CT14≤2.8, where CT15 is the thickness of the fifteenth lens L15 on the optical axis N, and CT14 is the thickness of the fourteenth lens L14 on the optical axis N. Combining the optical power and surface design of the fifteenth lens L15 and the fourteenth lens L14, it is possible to reasonably constrain the light beam trend, improve the imaging quality, and facilitate miniaturization design.

[0092] In some embodiments, the optical system 10 further includes a first protective element 130 and a second protective element 320. The first protective element 130 is disposed on the object side of the first lens L1 to provide protection for each lens in the objective lens assembly 100. The second protective element 320 is disposed on the image side of the fifteenth lens L15 to provide protection for each lens in the eyepiece assembly 300. The first protective element 130 and the second protective element 320 both include but are not limited to flat glass, and no further limitations are made herein.

[0093] See also Figure 4 As shown, the optical system 10 further includes a rod lens assembly 200, which is disposed on the image side of the objective lens assembly 100, or between the eyepiece assembly 300 and the objective lens assembly 100, and the magnification of the rod lens assembly 200 is 1. The rod lens assembly 200 includes a plurality of groups of rod lenses sequentially arranged along the optical axis N, which can be specifically arranged according to the light transmission length requirement, and the number of rod lenses can be an odd number, so that the required length can be reasonably set.

[0094] Each group of rod lenses includes a third glued lens group 210 and a fourth glued lens group 220 with optical power, and the third glued lens group 210 and the fourth glued lens group 220 are mirror-symmetrical about a plane perpendicular to the optical axis N. It can be understood that the third glued lens group 210 and the fourth glued lens group 220 have the same structure, but are symmetrically arranged.

[0095] In some embodiments, the third cemented lens group 210 includes a tenth lens L10 and an eleventh lens L11 that are cemented together, the tenth lens L10 has positive focal length, the object side surface and the image side surface of the tenth lens L10 are both convex, the eleventh lens L11 has negative focal length, the object side surface of the eleventh lens L11 is concave, and the image side surface is convex. The third cemented lens group 210 uses a positive and negative combination of cemented lens groups, which can effectively reduce aberrations such as Petzval sum, chromatic aberration, and spherical aberration, and has good light energy transmission efficiency, and the third cemented lens group 210 and the fourth cemented lens group 220 can achieve proportional image transmission, and the vertical axis chromatic aberrations such as vertical axis chromatic aberration, coma, and distortion of the third cemented lens group 210 and the fourth cemented lens group 220 are equal in size and opposite in sign, and can offset each other, and the imaging quality of the optical system 10 is improved by coordinating with the reasonable design of the objective lens assembly 100.

[0096] In some embodiments, the rod mirror assembly 200 satisfies: 8≤CT10 / CT11≤9, wherein CT10 is the thickness of the tenth lens L10 on the optical axis N, and CT11 is the thickness of the eleventh lens L11 on the optical axis N. This allows the relationship between the center thicknesses of the lenses in the rod mirror assembly 200 to be reasonably configured, and the focal length and surface design of each lens are coordinated, which is beneficial to maintaining good imaging quality while transmitting light.

[0097] In some embodiments, the lenses of the optical system 10 are coaxial, and the common axis of the lenses is the optical axis N of the optical system 10 .

[0098] In some embodiments, a multi-layer anti-reflection and band selective transmission film layer is set on any one or more lenses in the optical system 10, or at least one optical element of the first protection element 130, the second protection element 320 and the steering element 140 through a multi-layer coating technology to improve the transmittance of the optical system 10 to the visible light band and the infrared light band, thereby improving the light transmittance of the optical system 10 in a weak light environment, and effectively correcting the chromatic aberration of the optical system 10 to the visible light band and the infrared light band, thereby improving the imaging quality.

[0099] In some embodiments, the present application also provides a fluorescent endoscope having a wide spectrum, high imaging quality, and clear imaging. The fluorescent endoscope includes a housing and an optical system 10 as described in any of the above embodiments, and the housing can be a supporting structure of the optical system 10. Fluorescent endoscopes include but are not limited to fluorescent laparoscopic endoscopes, etc. The above optical system 10 is used in a fluorescent endoscope, which can have good imaging quality for both infrared light and visible light, thereby helping to improve the accuracy of diagnosis and treatment.

[0100] Based on the above optical system 10 , the present application provides the following first embodiment and second embodiment as examples, but the present application is not limited to the following embodiments.

[0101] First embodiment:

[0102] Refer to the following Table 1, which shows the parameter values ​​of the optical system 10 in the first embodiment, wherein FNO is the aperture number of the optical system 10, f is the effective focal length of the optical system 10, TTL is the total optical length of the optical system 10, FOV is the maximum field of view of the optical system 10, and ENPD is the entrance pupil diameter of the optical system 10.

[0103] Table 1

[0104] parameter First embodiment FNO 12.78 f(mm) 5.32 TTL(mm) 394 FOV(°) 80 ENPD 0.42 |f1 / CT1| 6.49 FW1 / CT2 6.38 f3 / CT3 2.68 Vd5 / Vd6 2.01 f7 / CT7 3.07 CT8 / CT9 2.04 CT10 / CT11 8.2 |f12 / CT12| 5.35 f13 / CT13 5.74 CT15 / CT14 2.51

[0105] Table 2 below shows the aspheric coefficients of the object side surface of the first lens L1 in the first embodiment. The aspheric surface design satisfies the following conditional formula:

[0106]

[0107] Among them, Z represents the axial distance from the surface to the vertex at a height y perpendicular to the optical axis N; c represents the curvature at the vertex of the aspheric surface; k represents the cone coefficient; A4, A6, A8, A10 represent the fourth-order, sixth-order, eighth-order, and tenth-order aspheric coefficients respectively. R in Table 2 represents the radius of curvature of the corresponding surface at the optical axis N.

[0108] Table 2

[0109]

[0110]

[0111] Combined with reference Figure 5-Figure 10 As shown, Figure 5 , Figure 6 and Figure 7 They are respectively a modulation transfer function curve diagram, a point array diagram, and a field curvature and distortion curve diagram of the optical system 10 in the first embodiment in the visible light band, such as visible light with a wavelength of 430-780nm, Figure 8 , Fig. 9 and Fig.10 They are respectively the modulation transfer function curve, point array diagram, field curvature and distortion curve diagram of the optical system 10 in the first embodiment in the fluorescence band (near infrared band, such as wavelength of 830-850nm). It can be seen that the imaging quality of the first embodiment of the present application is good, and the aberration is significantly corrected, which is mainly reflected in that the central field of view diffuse spot is smaller than the Airy disk and close to the diffraction limit, the distortion is effectively corrected, and the defocus amount in the near infrared band is small. It can be seen that the optical system 10 of the present application has good imaging quality, extremely small aberration, and clear image.

[0112] The following Table 3 and Figure 4 Partial data of the optical system 10 and the aspheric coefficient of the object side surface of the first lens L1 in the second embodiment are shown respectively. The meaning of each parameter can be obtained by referring to the first embodiment.

[0113] Table 3

[0114] parameter First embodiment FNO 12.78 f(mm) 5.29 TTL(mm) 411 FOV(°) 80 ENPD 0.42 |f1 / CT1| 6.489 FW1 / CT2 6.41 f3 / CT3 2.78 Vd5 / Vd6 2.01 f7 / CT7 3.57 CT8 / CT9 2.26 CT10 / CT11 8.56 |f12 / CT12| 5.35 f13 / CT13 6.18 CT15 / CT14 2.13

[0115] Table 4

[0116] Object side R 16.684 k -1.30197558 A4 0.00463440317931 A6 0.00014447274076 A8 -1.696910538e-005 A10 2.74253686e-006

[0117] Combination Figure 11-Figure 16 As shown, Fig.11 , Fig.12 and Fig.13 They are respectively a modulation transfer function curve diagram, a point diagram, and a field curvature and distortion curve diagram of the optical system 10 in the visible light band in the second embodiment, Fig.14 , Fig.15 and Fig.16 They are respectively the modulation transfer function curve, point diagram, field curvature and distortion curve of the optical system 10 in the second embodiment in the fluorescence band (near infrared band). Figure 11-Figure 16It can be seen that the optical system 10 in the second embodiment has good resolution, the central field of view diffuse spots are smaller than the Airy disk and close to the diffraction limit, the distortion is effectively corrected, and the defocus in the near-infrared band is small, that is, the optical system 10 can achieve good imaging quality for both visible light and near-infrared light, which is conducive to the fluorescent endoscope to collect clear and high-quality images, facilitate direct and clear observation of the patient's abdominal cavity situation, and understand the pathogenic factors.

[0118] The fluorescent endoscope of the present application adopts the above-mentioned optical system 10, so that the light propagates smoothly, and at the same time corrects aberrations such as distortion, chromatic aberration, and field curvature to improve the imaging quality of the optical system 10. It can also increase the depth of field of the optical system 10 and reduce the defocusing of the fluorescent band, so that the objective lens assembly 100 can have good imaging quality for both visible light and near-infrared light, which is conducive to clearly distinguishing the diseased area and the normal area, and improving the accuracy of diagnosis and treatment. The optical system 10 has a compact structure, which is conducive to the miniaturized design of the fluorescent endoscope.

[0119] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described 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.

[0120] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. An optical system, It is characterized in that The optical system comprises: an eyepiece assembly having optical power; The objective lens assembly is arranged on the light incident side of the eyepiece assembly, and the objective lens assembly comprises: A first lens having negative optical power, wherein the object-side surface of the first lens is convex and the image-side surface is concave; a second lens having negative optical power, wherein the image side surface of the second lens is a concave surface; a third lens having positive refractive power, wherein the image side surface of the third lens is a convex surface; a first cemented lens group with negative optical power, wherein the first cemented lens group comprises a fourth lens, a fifth lens and a sixth lens cemented in sequence, the fourth lens has positive optical power, the fifth lens has negative optical power, and the sixth lens has negative optical power; a seventh lens having positive refractive power; and a second cemented lens group having positive refractive power.

2. The optical system according to claim 1, It is characterized in that The objective lens assembly satisfies: 6≤FW1 / CT2≤6.5; Wherein, FW1 is the focal length of the objective lens assembly, and CT2 is the thickness of the second lens on the optical axis.

3. The optical system according to claim 1, It is characterized in that The objective lens assembly satisfies: 5≤|f1 / CT1|≤7; and / or, 2.5≤f3 / CT3≤3; and / or, 2.5≤f7 / CT7≤4; Among them, f1 is the effective focal length of the first lens, CT1 is the thickness of the first lens on the optical axis, f3 is the effective focal length of the third lens, CT3 is the thickness of the third lens on the optical axis, f7 is the effective focal length of the seventh lens, and CT7 is the thickness of the seventh lens on the optical axis.

4. The optical system according to claim 1, It is characterized in that The object side surface and the image side surface of the fourth lens are both convex surfaces, the object side surface of the fifth lens is concave, the image side surface is convex, and the object side surface and the image side surface of the sixth lens are both concave surfaces; and / or, The objective lens assembly satisfies: 1.8≤Vd5 / Vd6≤2.2; wherein Vd5 is the Abbe number of the fifth lens, and Vd6 is the Abbe number of the sixth lens.

5. The optical system according to claim 1, It is characterized in that The second cemented lens group comprises an eighth lens and a ninth lens which are cemented in sequence, the eighth lens has positive focal power, and the ninth lens has negative focal power; The object side surface and the image side surface of the eighth lens are both convex surfaces, the object side surface of the ninth lens is concave, and the image side surface is convex; and / or, The objective lens assembly satisfies: 1.8≤CT8 / CT9≤2.5; wherein CT8 is the thickness of the eighth lens on the optical axis, and CT9 is the thickness of the ninth lens on the optical axis.

6. The optical system according to claim 1, It is characterized in that The optical system further comprises a rod lens assembly, wherein the rod lens assembly is arranged between the objective lens assembly and the eyepiece lens assembly along the optical path; The rod mirror assembly includes a plurality of groups of rod mirrors sequentially arranged along the optical axis, each group of rod mirrors includes a third glued lens group and a fourth glued lens group with optical power, and the third glued lens group and the fourth glued lens group are mirror-symmetrical about a plane perpendicular to the optical axis.

7. The optical system according to claim 6, It is characterized in that The third cemented lens group comprises a tenth lens and an eleventh lens cemented together; the tenth lens has positive focal power, the object side surface and the image side surface of the tenth lens are both convex surfaces, the eleventh lens has negative focal power, the object side surface of the eleventh lens is concave, and the image side surface is convex; and / or, The third cemented lens group includes a tenth lens and an eleventh lens cemented together; the rod lens assembly satisfies: 8≤CT10 / CT11≤9; wherein CT10 is the thickness of the tenth lens on the optical axis, and CT11 is the thickness of the eleventh lens on the optical axis.

8. The optical system according to claim 1, It is characterized in that The optical system satisfies: fM≤10mm; wherein fM is the effective focal length of the eyepiece assembly; and / or, The eyepiece assembly comprises, in sequence from the object side to the image side along the optical axis, a twelfth lens with negative optical power, a thirteenth lens with positive optical power, and a fifth cemented lens group, the fifth cemented lens group comprises a fourteenth lens and a fifteenth lens, the fourteenth lens has positive optical power, and the fifteenth lens has negative optical power.

9. The optical system according to claim 8, It is characterized in that When the eyepiece assembly includes the twelfth to fifteenth lenses, the eyepiece assembly satisfies: 5≤|f12 / CT12|≤6; and / or, 5≤f13 / CT13≤7; and / or, 2≤CT15 / CT14≤2.8; Among them, f12 is the effective focal length of the twelfth lens, CT12 is the thickness of the twelfth lens on the optical axis, f13 is the effective focal length of the thirteenth lens, CT13 is the thickness of the thirteenth lens on the optical axis, CT15 is the thickness of the fifteenth lens on the optical axis, and CT14 is the thickness of the fourteenth lens on the optical axis.

10. A fluorescent endoscope, It is characterized in that Comprising the optical system according to any one of claims 1 to 9.

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