Endoscope imaging system and hard tube type endoscope

Abstract

The invention provides an endoscope imaging system and a hard tube type endoscope, and belongs to the technical field of optical imaging, the endoscope imaging system comprises an objective lens, a relay lens and an ocular lens of an object space telecentric structure, the objective lens comprises a first lens, a second lens, a third lens with positive focal power and a bonding lens group with positive focal power, the second lens is a steering prism, the image side surface and the object side surface of the first lens are aspheric surfaces, the balsaming lens group comprises a fourth lens, a fifth lens and a sixth lens, the fourth lens is a doublet lens, the fifth lens is a triplet lens, the sixth lens is a doublet lens, the relay lens comprises an odd number of rod lens groups which are arranged at intervals, and the rod lens groups are arranged at intervals. The eyepiece comprises a seventh lens, an eighth lens and a ninth lens, and the seventh lens, the eighth lens and the ninth lens are all doublet lenses. By optimizing the structural design of the optical system, the defocusing amount is reduced, seamless switching of visible light and near-infrared light dual-mode imaging can be achieved, and meanwhile high-quality imaging is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical imaging technology, in particular to an endoscope imaging system and a rigid endoscope. BACKGROUND

[0002] Medical endoscopes, as important tools for modern minimally invasive surgery and medical examination, can provide real-time and intuitive observation of internal organs and tissues for doctors. The internal structure integrates precise optical systems, mechanical transmission devices and illumination technology, and through the coordinated work of various systems, it realizes high-definition imaging and precise operation, significantly improving the accuracy and safety of clinical diagnosis and treatment.

[0003] According to the different imaging structures, medical endoscopes can be mainly divided into three categories: rigid endoscopes, optical fiber (soft tube) endoscopes and electronic endoscopes. Among them, the optical system of the rigid endoscope is usually composed of an objective lens, a relay lens and an ocular lens: the objective lens is located at the front end of the endoscope, responsible for collecting the image of the target area, determines the angle of view and the field of view, the relay lens acts as a relay system, mainly undertakes the functions of image conversion (converts the inverted real image formed by the objective lens into a positive image) and transmission, and the ocular lens mainly magnifies the image and outputs it through the eyecup for the doctor to observe.

[0004] At present, although the traditional white light endoscope commonly used in clinical practice has realized high-definition imaging, it still has obvious shortcomings in the identification and positioning of specific tissues such as precancerous lesions. In order to break through this limitation, the existing technology has developed a fluorescence endoscope system, which innovatively integrates dual-band imaging function: on the one hand, it obtains morphological information of the tissue surface through the 400nm-700nm visible light band (white light mode), and on the other hand, it realizes fluorescence imaging of deep tissues through the 800nm-900nm near-infrared band (fluorescence mode), which can clearly show key anatomical structures such as gallbladder duct, lymphatic vessels and blood vessel network, significantly improving the identification rate of diseased tissues. However, when the system switches between the two modes, due to the difference in dispersion characteristics of light of different wavelengths in the optical system, significant defocusing phenomenon occurs, forcing the operator to interrupt the surgical procedure and repeatedly adjust the focus, which not only affects the diagnosis efficiency, but also may endanger the safety and continuity of the operation. SUMMARY

[0005] Therefore, the purpose of the present application is to provide an endoscope imaging system and a rigid endoscope, which can realize seamless switching between visible light and near-infrared light dual-mode imaging by optimizing the design of the optical system structure, reducing the defocusing amount, and ensuring the imaging quality.

[0006] To achieve the above purpose, the technical solution adopted by the present application is as follows: In a first aspect, the present application provides an endoscope imaging system, which comprises, in order from the object side to the image side along the optical axis, an objective lens, a relay lens and an ocular lens of an object-side telecentric structure, wherein the objective lens comprises, in order from the object side to the image side along the optical axis, a first lens with negative focal power, a second lens, a third lens with positive focal power, and a cemented lens group with positive focal power, the second lens is a turning prism, the image side and the object side of the first lens are both aspherical surfaces, the cemented lens group comprises a fourth lens, a fifth lens and a sixth lens, the fourth lens is a double cemented lens, the fifth lens is a triple cemented lens, and the sixth lens is a double cemented lens, the relay lens comprises an odd number of rod lens groups arranged in order and spaced apart from each other along the optical axis from the object side to the image side, the field of view of each virtual image plane of the rod lens group has consistent clarity, the ocular lens comprises, in order from the object side to the image side along the optical axis, a seventh lens, an eighth lens and a ninth lens, and the seventh lens, the eighth lens and the ninth lens are all double cemented lenses; wherein the ocular lens has an exit angle of ≤14°, the defocus amount of white light and fluorescence of the endoscope imaging system is not more than 0.02 mm, the central field of view MTF of the endoscope imaging system in white light mode is greater than 0.13 at 180 lp / mm, the edge field of view MTF of the endoscope imaging system in white light mode is greater than 0.09 at 180 lp / mm, the central field of view MTF of the endoscope imaging system in fluorescence mode is greater than 0.23 at 100 lp / mm, and the edge field of view MTF of the endoscope imaging system in fluorescence mode is greater than 0.20 at 100 lp / mm.

[0007] In addition, the endoscope imaging system according to the present application has the following additional technical features. Further, the fourth lens comprises a first concave lens and a first convex lens cemented along the optical axis from the object side to the image side, the refractive index of the first concave lens is greater than that of the first convex lens, and the sixth lens comprises a second convex lens and a second concave lens cemented along the optical axis from the object side to the image side, the refractive index of the first concave lens is 1.7-2.1, and the refractive index of the first convex lens is 1.5-1.8.

[0008] Further, the total field of view is 75°-85°.

[0009] Further, the endoscope imaging system satisfies the following optical parameter conditions:

[0010] Wherein, f is the total effective focal length of the endoscope imaging system, in millimeters, and EPD is the entrance pupil diameter of the endoscope imaging system, in millimeters.

[0011] Further, the endoscope imaging system also satisfies the following optical parameter conditions:

[0012] wherein f1 is the effective focal length of the objective lens, in millimeters, and f is the total effective focal length of the endoscope imaging system, in millimeters.

[0013] Further, the endoscope imaging system also satisfies the following optical parameter conditions:

[0014] wherein D is the maximum diameter of the effective surface of the optical element in the endoscope imaging system, in millimeters.

[0015] Further, the rod lens groups on both sides of the optical axis direction are symmetrically arranged relative to the center of the rod lens group at the middle position.

[0016] Further, each of the rod lens groups comprises a first rod lens, a tenth lens, an eleventh lens and a second rod lens, which are sequentially and spacedly arranged along the optical axis direction from the object side to the image side; wherein the tenth lens and the eleventh lens are both doublet lenses.

[0017] Further, the object side surface and the image side surface of the first rod lens and the second rod lens are both convex, the tenth lens comprises a third convex lens and a third concave lens which are cemented along the optical axis direction from the object side to the image side, the object side surface and the image side surface of the third convex lens are both convex, the object side surface and the image side surface of the third concave lens are both concave, the eleventh lens comprises a fourth concave lens and a fourth convex lens which are cemented along the optical axis direction from the object side to the image side, the object side surface and the image side surface of the fourth concave lens are both concave, and the object side surface and the image side surface of the fourth convex lens are both convex.

[0018] In a second aspect, the present application also provides a rigid tube endoscope device applying the aforementioned endoscope imaging system.

[0019] The beneficial effects of the present application at least include: by combining aspherical lens with cemented lens, odd number of symmetric rod lens design and object side telecentric eyepiece structure, the defocus amount of white light and fluorescent imaging is not more than 0.02mm, the problem of repeated focusing when switching modes is solved; at the same time, by MTF optimization and chromatic aberration control, the defocus amount of the white light and fluorescent of the endoscope imaging system is not more than 0.02mm, the central field of view MTF in white light mode is greater than 0.13 at 180lp / mm, the edge field of view MTF in white light mode is greater than 0.09 at 180lp / mm, the central field of view MTF in fluorescent mode is greater than 0.23 at 100lp / mm, the edge field of view MTF in fluorescent mode is greater than 0.20 at 100lp / mm, the sagittal chromatic aberration is not more than 1.9μm, the distortion is not more than 6%, the field curvature is not more than 0.20mm, high-definition imaging can be realized, the clinical high-resolution requirement is met, and by controlling the system outer diameter to be not more than 6mm and the eyepiece light exit angle to be not more than 14°, miniaturization and clinical operability are achieved; in addition, the symmetric relay rod lens group and the split lens design significantly improve the production efficiency and assembly accuracy. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 FIG. 1 is a structural schematic diagram of an endoscope imaging system in an embodiment of the present application; Figure 2 FIG. 2 is a structural schematic diagram of an objective lens in an embodiment of the present application; Figure 3 FIG. 3 is a structural schematic diagram of a relay lens in an embodiment of the present application; Figure 4 FIG. 4 is a structural schematic diagram of an eyepiece in an embodiment of the present application; Figure 5 FIG. 5 is an optical modulation function diagram of the endoscope imaging system in embodiment 1 in white light mode; Figure 6 FIG. 6 is a sagittal chromatic aberration diagram of the endoscope imaging system in embodiment 1 in white light mode; Figure 7 FIG. 7 is a field curvature diagram of the endoscope imaging system in embodiment 1 in white light mode; Figure 8 FIG. 8 is a distortion diagram of the endoscope imaging system in embodiment 1 in white light mode; Figure 9 FIG. 9 is an optical modulation function diagram of the endoscope imaging system in embodiment 1 in fluorescent mode; Figure 10 FIG. 10 is a sagittal chromatic aberration diagram of the endoscope imaging system in embodiment 1 in fluorescent mode; Figure 11 FIG. 11 is a field curvature diagram of the endoscope imaging system in embodiment 1 in fluorescent mode; Figure 12 Distortion map for the endoscope imaging system in Example 1 of the present application in fluorescence mode; Figure 13 Optical modulation function map for the endoscope imaging system in Example 2 of the present application in white light mode; Figure 14 Vignetting map for the endoscope imaging system in Example 2 of the present application in white light mode; Figure 15 Field curvature map for the endoscope imaging system in Example 2 of the present application in white light mode; Figure 16 Distortion map for the endoscope imaging system in Example 2 of the present application in white light mode; Figure 17 Optical modulation function map for the endoscope imaging system in Example 2 of the present application in fluorescence mode; Figure 18 Vignetting map for the endoscope imaging system in Example 2 of the present application in fluorescence mode; Figure 19 Field curvature map for the endoscope imaging system in Example 2 of the present application in fluorescence mode; Figure 20 Distortion map for the endoscope imaging system in Example 2 of the present application in fluorescence mode; The following detailed description will further describe the present application with reference to the above mentioned figures. DETAILED DESCRIPTION

[0021] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. In the drawings, several embodiments of the present application are shown. However, the present application can be realized in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of the present application will be more thorough and complete.

[0022] It should be noted that in the present specification, the expressions first, second, third, etc. are used only to distinguish one feature from another feature, and do not indicate any limitation on the features. Thus, the first lens discussed below can also be referred to as the second lens or the third lens without departing from the teachings of the present application.

[0023] In the drawings of the present application, the thickness, size, and shape of the lenses have been slightly exaggerated for ease of explanation. Specifically, the shape of the spherical surface or aspherical surface shown in the drawings is shown by way of example. That is, the shape of the spherical surface or aspherical surface is not limited to the shape of the spherical surface or aspherical surface shown in the drawings. The drawings are merely examples and are not drawn to scale.

[0024] In the present disclosure, the paraxial region refers to a region near the optical axis. If a lens surface is convex and the position of the convex surface is not specified, it means that the lens surface is convex at least in the paraxial region. If a lens surface is concave and the position of the concave surface is not specified, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the object is referred to as the object side surface of the lens, and the surface of each lens closest to the image plane is referred to as the image side surface of the lens.

[0025] It should also be understood that the word "comprise", "comprising", "include", "including", and / or "contains", "containing", when used in this specification, mean the presence of stated features, elements, and / or components but do not preclude the presence or addition of one or more other features, elements, components, and / or groups thereof. In addition, when expressions such as "at least one of" appear after a list of items, it modifies the entire list of items and not the individual items in the list. Furthermore, when describing embodiments of the present application, the word "may" means "one or more embodiments of the present application". Also, the word "exemplary" is intended to mean an example or an illustration.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0027] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0028] The features, principles, and other aspects of the present application are described in detail below.

[0029] Please refer to Figures 1 to 4 An endoscope imaging system is provided in the present application, which comprises, in order from the object side to the image side along the optical axis direction, an objective lens 10, a relay lens 20, and an objective lens 30 of the object side telecentric structure.

[0030] The objective lens 10 is located at the front end of the endoscope, is responsible for collecting the image of the target area, and determines the imaging angle and field of view. Specifically, the objective lens 10 includes a first lens 11 with negative focal power, a second lens 12, a third lens 13 with positive focal power, a cemented lens group with positive focal power, arranged in order from the object side to the image side along the optical axis direction. The second lens 12 is a turning prism, the image side and the object side of the first lens 11 are both aspheric surfaces, the cemented lens group includes a fourth lens 14, a fifth lens 15 and a sixth lens 16, the fourth lens 14 is a double cemented lens, the fifth lens 15 is a triple cemented lens, and the sixth lens 16 is a double cemented lens. It should be noted that, except for the first lens 11, the remaining lenses in the objective lens 10 are ordinary spherical mirrors, and the material can be selected from crystal, plastic or glass. Since the first lens 11 has negative focal power, it has a diverging effect on the light beam, has a large light aperture for the subsequent optical system, and introduces large spherical aberration and positional chromatic aberration. The double cementing and triple cementing of the fourth lens 14, the fifth lens 15 and the sixth lens 16 can correct the spherical aberration and the positional chromatic aberration, and at the same time, the third lens 13 with positive focal power and the cemented lens group with positive focal power and the first lens 11 with negative focal power can complement each other to correct the coma, astigmatism and field curvature.

[0031] Exemplarily, the second lens 12 adopts a 30° turning prism, which is equivalent to a 0° view angle system after optical expansion. It can be understood that the turning angle of the second lens 12 can be different according to the needs of actual application, that is, the turning angle of the turning prism can be appropriately adjusted and optimized according to specific application scenarios and design requirements to achieve the best performance. For example, the turning angle of the second lens 12 can be adjusted as needed within the range of 0°-45° to adapt to the optical system requirements of various miniaturized endoscopes.

[0032] The image turning mirror 20 acts as a relay system, mainly responsible for image turning (converting the inverted real image formed by the objective lens into a positive image) and transmission. Specifically, the image turning mirror 20 includes an odd number of rod lens groups (21, 22, 23) arranged in order from the object side to the image side along the optical axis direction, and the field of view clarity of the virtual image plane after the rod lens group is consistent.

[0033] The eyepiece forms an object side telecentric structure, mainly magnifies the image transmitted by the image turning mirror and outputs through the eyecup for the doctor to observe. Specifically, the eyepiece 30 includes a seventh lens 31, an eighth lens 32 and a ninth lens 33 arranged in order from the object side to the image side along the optical axis direction. The seventh lens 31, the eighth lens 32 and the ninth lens 33 are all double cemented lenses. It should be noted that the lenses in the eyepiece 30 are all ordinary spherical mirrors, and the material can be selected from crystal, plastic or glass.

[0034] In addition, the exit angle (exit cone angle) of the eyepiece 30 is less than or equal to 14°, the defocus amount of the white light and the fluorescence of the endoscope imaging system is less than or equal to 0.02 mm, the central field of view MTF of the endoscope imaging system in the white light mode is greater than 0.13 at 180 lp / mm, the edge field of view MTF of the endoscope imaging system in the white light mode is greater than 0.09 at 180 lp / mm, the central field of view MTF of the endoscope imaging system in the fluorescence mode is greater than 0.23 at 100 lp / mm, and the edge field of view MTF of the endoscope imaging system in the fluorescence mode is greater than 0.20 at 100 lp / mm.

[0035] In the embodiment, by strictly controlling the exit angle of the eyepiece 30 to be less than or equal to 14°, the ideal coupling of the output light beam of the eyepiece 30 and the imaging device can be ensured, the edge illumination attenuation caused by excessive divergence of light is avoided, the uniformity of image brightness is maintained, the smaller exit angle provides comfortable observation conditions for medical staff, effectively reduces visual fatigue caused by long-time surgery, and stray light interference is inhibited. The first lens 11 in the objective lens 10 at the front end adopts an aspherical surface design, which not only significantly improves the distortion performance of the system, but also plays a key role in optimizing the field curvature of the objective lens 10. The eyepiece 30 uses the virtual image plane formed by the relay lens 20 as the object plane, and adopts a material far from the design of the structure, so that the chief ray is strictly parallel to the optical axis, ensuring that the image center remains stable when the object position changes, and using the material far from the structure can ensure good optical performance on the image plane, thereby providing high-quality imaging effects in the entire field of view.

[0036] In some optional embodiments, the object side surface of the first lens 11 is convex at the position of the optical axis, and the image side surface of the first lens 11 is concave at the position of the optical axis.

[0037] In some optional embodiments, the object side surface of the third lens 13 is a plane, and the image side surface of the third lens 13 is convex.

[0038] In some optional embodiments, the fourth lens 14 includes a first concave lens and a first convex lens cemented along the optical axis direction from the object side to the image side, the refractive index of the first concave lens is greater than the refractive index of the first convex lens, and the sixth lens 16 includes a second convex lens and a second concave lens cemented along the optical axis direction from the object side to the image side.

[0039] In the embodiment, the fourth lens 14 adopts the structure of cementing a concave-convex lens, and through the optimized combination of high and low refractive index materials, the chromatic aberration problem of the system can be effectively corrected, which has a certain degree of improvement effect on the aberration of the objective lens 10 at the front end, and helps to reduce the volume of the system. It can be understood that, in order to further reduce the chromatic aberration of the system, the fourth lens 14 can be made of a low-dispersion material.

[0040] In some alternative embodiments, the object side surface of the first concave lens is convex, and the image side surface of the first concave lens is concave.

[0041] In some alternative embodiments, the object side surface of the first convex lens is convex, and the image side surface of the first convex lens is concave.

[0042] In some alternative embodiments, the refractive index of the first concave lens is 1.7-2.1, and the refractive index of the first convex lens is 1.5-1.8.

[0043] In some alternative embodiments, the object side surface and the image side surface of the first lens piece of the fifth lens 15 are both convex, the object side surface and the image side surface of the second lens piece of the fifth lens 15 are both concave, and the object side surface and the image side surface of the third lens piece of the fifth lens 15 are both convex.

[0044] In the embodiment, the fifth lens 15 is a three-cemented lens, which is conducive to correcting chromatic aberration of the optical system, and can be produced and detected as a whole, thereby improving production efficiency and simplifying the manufacturing process.

[0045] In some alternative embodiments, the object side surface and the image side surface of the second convex lens are both convex, the object side surface of the second concave lens is concave, and the image side surface of the second concave lens is convex.

[0046] In the embodiment, the sixth lens 16 adopts a convex-concave lens cemented structure, which can integrate the tolerance requirements of multiple optical elements into a single element tolerance, significantly reduce the eccentricity sensitivity of the system, solve the process problems of lens processing and system assembly in traditional design, improve the yield of the optical imaging system, and further reduce the production cost of the optical imaging system disclosed in the embodiment.

[0047] In some alternative embodiments, the object side surface and the image side surface of the first lens piece of the seventh lens 31 are both convex, the object side surface of the second lens piece of the seventh lens 31 is concave, the image side surface of the second lens piece of the seventh lens 31 is convex, the object side surface of the first lens piece of the eighth lens 32 is concave, the image side surface of the first lens piece of the eighth lens 32 is convex, the object side surface of the second lens piece of the eighth lens 32 is concave, the image side surface of the second lens piece of the eighth lens 32 is convex, the object side surface and the image side surface of the first lens piece of the ninth lens 33 are both convex, the object side surface of the second lens piece of the ninth lens 33 is concave, and the image side surface of the second lens piece of the ninth lens 33 is convex.

[0048] In the embodiment, by optimizing the double-cemented lens combination and the precise power distribution, various aberrations can be effectively corrected to ensure the imaging clarity in the full field of view. The object-side telecentric design formed by the seventh lens 31, the eighth lens 32 and the ninth lens 33 can connect the virtual image plane of the relay lens, maintain the image plane uniformity and the imaging quality, and ensure the consistency of the clarity of each field of view on the virtual image plane at the front end of the eyepiece.

[0049] In some optional embodiments, the full field of view angle of the endoscope imaging system is 75° to 85°. This design not only provides the user with sufficient observation range, but also avoids the decrease of the edge image quality caused by the excessively large field of view, which is helpful for observing the lesion area comprehensively.

[0050] In some optional embodiments, the endoscope imaging system provided in the application meets the following optical parameter conditions:

[0051] Wherein, f is the total effective focal length of the endoscope imaging system, and the unit is millimeter; and EPD is the entrance pupil diameter of the endoscope imaging system, and the unit is millimeter.

[0052] For example, the value of f / EPD is 7.0, 7.1, 7.2, 7.3, 7.4, 7.5. When the endoscope imaging system provided in the application meets the above condition formula, the system can realize a larger focal length in a limited physical size, thereby improving the clarity and resolution of imaging, and the range of the ratio ensures that the system has moderate light flux and depth of field, avoiding the increase of the system volume caused by the excessively large entrance pupil, or the influence of the imaging signal-to-noise ratio caused by the excessively small entrance pupil.

[0053] In some optional embodiments, the endoscope imaging system provided in the application also meets the following optical parameter conditions:

[0054] Wherein, f1 is the effective focal length of the objective lens 10, and the unit is millimeter; and f is the total effective focal length of the endoscope imaging system, and the unit is millimeter.

[0055] For example, the value of f1 / f is 0.85, 0.86, 0.87, 0.88, 0.89, 0.90, 0.91, 0.92, 0.93, 0.94. When the endoscope imaging system provided in the application meets the above condition formula, the ratio range optimizes the power distribution of the objective lens 10 and the entire system, which not only ensures the sufficient working distance, but also controls the total length of the system within a reasonable range.

[0056] In some optional embodiments, the endoscope imaging system also meets the following optical parameter conditions:

[0057] D is the maximum diameter of the effective surface of the optical element in the endoscope imaging system, in millimeters.

[0058] Exemplarily, D is 3, 4, 5, or 6. When the endoscope imaging system provided in the present application satisfies the above condition, the design makes the system meet the miniaturization requirement of medical endoscopes, not only improves the flexibility of the instrument control, but also reduces the discomfort of the patient, while ensuring sufficient optical performance.

[0059] In some optional embodiments, the rod lens groups on both sides of the optical axis direction are symmetrically arranged relative to the center of the rod lens group at the middle position. Exemplarily, the relay lens 20 includes a first rod lens group 21, a second rod lens group 22, and a third rod lens group 23 along the optical axis direction from the object side to the image side, i.e., the relay lens 20 is composed of three groups of rod lens groups with the same structure, and the diaphragm is arranged at the middle position of the second rod lens group 22. It can be understood that the relay lens 20 includes but is not limited to 3 groups, 5 groups, or 7 groups, etc. The number of rod lens groups can be selected according to different application requirements.

[0060] In the present embodiment, such a design of the relay lens 20 provides a flexible spatial layout scheme for the small caliber and long working distance of the system, and the configuration of the odd-numbered rod lens groups ensures the erecting property of the imaging of the eyepiece 30 at the rear end, improves the intuitiveness and easy observability of the imaging, and improves the observation experience of the user. At the same time, through the symmetrical design, the off-axis aberration generated by the relay lens 20 is small. In addition, each rod lens group has the same structure and size, which enables the production process to be highly standardized and simplified, and the symmetrical layout makes the mechanical stress uniformly distributed, which can overcome the problem of axis deviation caused by thermal expansion or assembly tolerance in traditional asymmetric structures.

[0061] In some optional embodiments, each group of rod lens groups includes a first rod lens 201, a tenth lens 202, an eleventh lens 203, and a second rod lens 204 arranged in sequence and spaced apart along the optical axis direction from the object side to the image side; wherein the tenth lens 202 and the eleventh lens 203 are both doublet lenses.

[0062] In the embodiment, the separation design of the rod lens and the cemented lens helps to reduce the accumulated error in the processing, simplifies the assembly process of the system, and improves the flexibility of the debugging and calibration of the optical imaging system. In addition, the combination of the double cemented lens and the rod lens can compensate for the spherical aberration, field curvature and axial chromatic aberration by the chromatic aberration correction ability (by matching high-dispersion and low-dispersion optical materials) of the double cemented lens and the long optical path characteristic of the rod lens. In addition, the double cemented lens can eliminate the air gap and improve the anti-vibration performance to ensure the stability of the optical axis. The integrated structure of the rod lens provides rigid support, and the combination of the double cemented lens and the rod lens forms a stable optical module to reduce the influence of temperature change on the imaging quality.

[0063] It can be understood that the number of lens blocks of the tenth lens 202 and the eleventh lens 203 can be designed and selected according to actual use requirements.

[0064] In some optional embodiments, the object side and the image side of the first rod lens 201 and the second rod lens 204 are both convex, the tenth lens 202 includes a third convex lens and a third concave lens cemented along the optical axis direction from the object side to the image side, the object side and the image side of the third convex lens are both convex, and the object side and the image side of the third concave lens are both concave. The eleventh lens 203 includes a fourth concave lens and a fourth convex lens cemented along the optical axis direction from the object side to the image side, the object side and the image side of the fourth concave lens are both concave, and the object side and the image side of the fourth convex lens are both convex.

[0065] In a second aspect, the application further provides a hard tube endoscope device applying the foregoing endoscope imaging system.

[0066] Some specific but non-limiting examples of the embodiments of the application will be described in more detail below. Figures 5 to 20 Some specific but non-limiting examples of the embodiments of the application will be described in more detail below.

[0067] Embodiment 1: The endoscope imaging system provided by the application includes an objective lens 10, a relay lens 20 and an objective side telecentric structure eyepiece 30 in sequence along the optical axis direction from the object side to the image side.

[0068] In terms of structure, the objective lens 10 includes, in order from the object side to the image side in the optical axis direction, a protection glass, a first lens 11 having a negative refractive power, and a second lens 12, a third lens 13 having a positive refractive power, and a cemented lens group having a positive refractive power.Specifically, a protective glass is arranged in front of the first lens of the objective lens 10, so that the whole optical system has stronger environmental adaptability and durability, the image side surface and the object side surface of the first lens 11 are aspherical surfaces, the object side surface of the first lens 11 is convex at the position of the optical axis, the image side surface of the first lens 11 is concave at the position of the optical axis, the second lens 12 adopts a 30° turning prism, the object side surface of the third lens 13 is a plane, the image side surface of the third lens 13 is convex, the cemented lens group includes the fourth lens 14, the fifth lens 15 and the sixth lens 16, the fourth lens 14 is a double cemented lens, the object side surface of the first lens piece of the fourth lens 14 is convex, and the image side surface of the first lens piece of the fourth lens 14 is concave, the object side surface of the second lens piece of the fourth lens 14 is convex, and the image side surface of the second lens piece of the fourth lens 14 is concave, the fifth lens 15 is a triple cemented lens, the object side surface and the image side surface of the first lens piece of the fifth lens 15 are both convex, the object side surface of the second lens piece of the fifth lens 15 is concave, the image side surface of the second lens piece of the fifth lens 15 is concave, the object side surface of the third lens piece of the fifth lens 15 is convex, the image side surface of the third lens piece of the fifth lens 15 is convex, the sixth lens 16 is a double cemented lens, the object side surface and the image side surface of the first lens piece of the sixth lens 16 are both convex, the object side surface of the second lens piece of the sixth lens 16 is concave, and the image side surface of the second lens piece of the sixth lens 16 is convex, the eyepiece 30 includes the seventh lens 31, the eighth lens 32 and the ninth lens 33 arranged in the order of the object side to the image side along the optical axis, the seventh lens 31, the eighth lens 32 and the ninth lens 33 are all double cemented lenses, the object side surface and the image side surface of the first lens piece of the seventh lens 31 are both convex, the object side surface of the second lens piece of the seventh lens 31 is concave, the image side surface of the second lens piece of the seventh lens 31 is convex, the object side surface of the first lens piece of the eighth lens 32 is concave, the image side surface of the first lens piece of the eighth lens 32 is convex, the object side surface of the second lens piece of the eighth lens 32 is concave, the image side surface of the second lens piece of the eighth lens 32 is convex, the object side surface and the image side surface of the first lens piece of the ninth lens 33 are both convex, the object side surface of the second lens piece of the ninth lens 33 is concave, and the image side surface of the second lens piece of the ninth lens 33 is convex, the turning mirror 20 includes the first rod lens group 21, the second rod lens group 22 and the third rod lens group 23 arranged in the order along the optical axis, each rod lens group includes the first rod lens 201, the tenth lens 202, the eleventh lens 203 and the second rod lens 204 arranged in the order of the object side to the image side, the tenth lens 202 and the eleventh lens 203 are both double cemented lenses, the object side surface and the image side surface of the first rod lens 201 are both convex, the object side surface and the image side surface of the first lens piece of the tenth lens 202 are both convex, the object side surface and the image side surface of the second lens piece of the tenth lens 202 are both concave, the object side surface and the image side surface of the first lens piece of the eleventh lens 203 are both concave, the object side surface and the image side surface of the second lens piece of the eleventh lens 203 are both convex, and the object side surface and the image side surface of the second rod lens 204 are both convex.

[0069] In terms of optical parameters, the aperture of the endoscope imaging system is 6mm, and the full field angle of the endoscope imaging system is in the range of 75°-82°.

[0070] Figure 5 and Figure 9 respectively describe the MTF curve diagrams of the endoscope imaging system designed in the lens combination manner of embodiment 1 in the visible light waveband of 400nm-700nm and in the near-infrared waveband of 700nm-900nm. In the MTF curve diagrams, the horizontal axis represents spatial frequency (unit: lp / mm), and the vertical axis represents MTF value. The MTF curve diagram can represent the imaging modulation degree of the lens at different spatial frequencies under each field of view. It can be known from the MTF curve diagrams that the central field of view MTF of the endoscope imaging system under white light mode is greater than 0.13 at 180lp / mm, the edge field of view MTF is greater than 0.09 at 180lp / mm, the central field of view MTF of the endoscope imaging system under fluorescence mode is greater than 0.23 at 100lp / mm, and the edge field of view MTF is greater than 0.20 at 100lp / mm, which indicates that the endoscope imaging system has high-resolution imaging capability in the full field of view range, and this performance index can enable the system to clearly display the fine structure of the tissue, thereby meeting the needs of precision medicine.

[0071] Figure 6 and Figure 10 respectively describe the sagittal chromatic aberration diagrams of the endoscope imaging system designed in the lens combination manner of embodiment 1 in the visible light waveband of 400nm-700nm and in the near-infrared waveband of 700nm-900nm. In the sagittal chromatic aberration diagrams, the base point of the graph is on the optical axis, the top point of the graph represents the maximum field radius, the positive field angle and the height in the Y direction are used, and the horizontal coordinate unit is micrometer. It can be known from the sagittal chromatic aberration diagrams that the sagittal chromatic aberration is not more than 1.9μm, which indicates that the endoscope imaging system has good chromatic aberration control in a wide waveband range, thereby improving the color accuracy and contrast of the imaging.

[0072] Figure 7 and Figure 11 respectively describe the field curvature diagrams of the endoscope imaging system designed in the lens combination manner of embodiment 1 in the visible light waveband of 400nm-700nm and in the near-infrared waveband of 700nm-900nm. In the field curvature diagrams, the horizontal coordinate represents the defocus amount of the image point, the unit is millimeter, and the defocus amount of the image point relative to the ideal image plane in the optical axis direction is specifically represented, the vertical axis is represented by the actual field angle, and represents different positions of the imaging area from the center to the edge. It can be known from the field curvature diagrams that the field curvature of the endoscope imaging system in the embodiment is not more than 0.20mm, which indicates that the field curvature and astigmatism of each field of view are well corrected, so that the center and edge of the field of view can have clear imaging.

[0073] Figure 8 and Figure 12 The distortion graphs of the endoscope imaging system designed in the lens combination manner of the embodiment 1 in the visible light waveband of 400nm-700nm and in the near-infrared waveband of 700nm-900nm are respectively shown in FIG. 3 and FIG. 4. In the distortion graphs, the abscissa represents the distortion rate (unit: %), and the ordinate represents the field of view angle (unit: degree). It can be seen from the distortion graphs that the optical distortion of each field of view is within 6%, which indicates that the image deformation caused by the chief ray is small, so that the imaging quality of the system presents an excellent state. The distortion below 6% makes the deformation of the image edge area almost imperceptible, which is beneficial to the consistency of the image geometry with the actual object, avoids excessive deformation of the image, is beneficial to the evaluation of the lesion size in the minimally invasive surgery, and improves the accuracy of diagnosis.

[0074] Embodiment 2: As shown in FIG. 5 and FIG. 6, another structure of the endoscope imaging system provided by the present application is different from the embodiment 1 in that the specific parameters of at least part of the optical elements in the endoscope imaging system are changed. Figures 13 to 20

[0075] Figure 13 and Figure 17 The MTF curve graphs of the endoscope imaging system designed in the lens combination manner of the embodiment 2 in the visible light waveband of 400nm-700nm and in the near-infrared waveband of 700nm-900nm are respectively shown in FIG. 5 and FIG. 6. In the MTF curve graphs, the abscissa represents the spatial frequency (unit: lp / mm), and the ordinate represents the MTF value. The MTF curve graph can represent the lens imaging modulation under different spatial frequencies in each field of view. It can be seen from the MTF curve graphs that the center field of view MTF of the endoscope imaging system under the white light mode is greater than 0.13 at 180lp / mm, the edge field of view MTF is greater than 0.09 at 180lp / mm, the center field of view MTF of the endoscope imaging system under the fluorescence mode is greater than 0.23 at 100lp / mm, and the edge field of view MTF is greater than 0.20 at 100lp / mm, which indicates that the endoscope imaging system has high resolution imaging capability in the full field of view range. This performance index can make the system clearly display the fine structure of the tissue, and meet the needs of precision medicine.

[0076] Figure 14 and Figure 18 ​The sagittal chromatic aberration graphs of the endoscope imaging system designed by the lens combination of Example 2 are respectively described in the visible light waveband of 400nm-700nm and the near-infrared waveband of 700nm-900nm. In the sagittal chromatic aberration graph, the base point of the graph is on the optical axis, the top point of the graph represents the maximum field radius, the positive field angle and the height in Y direction are used, and the horizontal coordinate unit is micrometer. It can be known from the sagittal chromatic aberration graph that the sagittal chromatic aberration is not more than 1.9μm, which indicates that the endoscope imaging system has good chromatic aberration control in a wide waveband range, thereby the color accuracy and contrast of imaging can be improved.

[0077] Figure 15 and Figure 19 The field curvature graphs of the endoscope imaging system designed by the lens combination of Example 2 are respectively described in the visible light waveband of 400nm-700nm and the near-infrared waveband of 700nm-900nm. In the field curvature graph, the horizontal coordinate represents the defocus amount of the image point, the unit is millimeter, and the defocus amount of the image point relative to the ideal image surface in the optical axis direction is specifically represented, the vertical coordinate is represented by the actual field angle, and the different positions of the imaging area from the center to the edge are represented. It can be known from the field curvature graph that the field curvature of the endoscope imaging system in the embodiment is not more than 0.20mm, which indicates that the field curvature and astigmatism of each field are well corrected, so that the center and edge of the field can have clear imaging.

[0078] Figure 16 and Figure 20 The distortion graphs of the endoscope imaging system designed by the lens combination of Example 2 are respectively described in the visible light waveband of 400nm-700nm and the near-infrared waveband of 700nm-900nm. In the distortion graph, the horizontal coordinate represents the distortion rate (unit: %), and the vertical coordinate represents the field angle (unit: degree). It can be known from the distortion graph that the optical distortion of each field is within 6%, which indicates that the image deformation caused by the main light beam is small, so that the imaging quality of the system presents an excellent state. The distortion of less than 6% makes the deformation of the image edge area almost imperceptible, which is beneficial to the consistency of the image geometric shape and the actual object, avoids excessive deformation of the image, is beneficial to the evaluation of the lesion size in the minimally invasive surgery, and improves the accuracy of diagnosis.

[0079] In summary, the endoscope imaging system in the embodiment optimizes the optical structure, controls the defocus amount of the optical imaging system within 0.02mm when working in white light and fluorescence, so that the medical staff does not need to refocus when switching between white light and fluorescence modes using the endoscope, realizes the confocal of white light and fluorescence modes, reduces the operation frequency, and improves the efficiency of lesion examination of the lesion part. At the same time, the center field MTF of the endoscope imaging system in the white light mode is greater than 0.13 at 180lp / mm, the edge field MTF of the endoscope imaging system in the white light mode is greater than 0.09 at 180lp / mm, the center field MTF of the endoscope imaging system in the fluorescence mode is greater than 0.23 at 100lp / mm, the edge field MTF of the endoscope imaging system in the fluorescence mode is greater than 0.20 at 100lp / mm, the optical distortion is less than 6%, the vertical chromatic aberration is not more than 1.9μm, and the field curvature is not more than 0.20mm. The performance indicators meet the high-resolution imaging in the full field of view, enable the system to clearly display the fine structure of the tissue, and meet the needs of precision medicine.

[0080] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily mean the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0081] The above-described embodiments only express several implementation manners of the present application, which are described in a more specific and detailed manner, but cannot be understood as the limitation of the protection scope of the present application. It should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present application, which are all within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. An endoscopic imaging system, characterized by, The objective lens, the relay lens and the ocular lens of the objective lens system are arranged in sequence from the object side to the image side along the optical axis direction. The objective lens comprises, arranged in sequence from the object side to the image side along the optical axis direction, a first lens with negative focal power, a second lens, a third lens with positive focal power, and a cemented lens group with positive focal power, the second lens is a turning prism, the image side surface and the object side surface of the first lens are both aspherical surfaces, the cemented lens group comprises a fourth lens, a fifth lens and a sixth lens, the fourth lens is a double cemented lens, the fifth lens is a triple cemented lens, and the sixth lens is a double cemented lens. The relay lens comprises an odd number of rod lens groups arranged in sequence and spaced apart from each other along the optical axis direction from the object side to the image side, and the clarity of each field of view of the virtual image surface behind the rod lens group is consistent. The ocular lens comprises a seventh lens, an eighth lens and a ninth lens arranged in sequence from the object side to the image side along the optical axis direction, and the seventh lens, the eighth lens and the ninth lens are all double cemented lenses. The light exit angle of the ocular lens is less than or equal to 14 degrees, the defocus amount of the endoscope imaging system under white light and fluorescence is not more than 0.02 mm, the central field of view MTF of the endoscope imaging system under white light mode is greater than 0.13 at 180 lp / mm, the edge field of view MTF of the endoscope imaging system under white light mode is greater than 0.09 at 180 lp / mm, the central field of view MTF of the endoscope imaging system under fluorescence mode is greater than 0.23 at 100 lp / mm, and the edge field of view MTF of the endoscope imaging system under fluorescence mode is greater than 0.20 at 100 lp / mm.

2. The endoscopic imaging system of claim 1, wherein, The fourth lens comprises a first concave lens and a first convex lens cemented in sequence along the optical axis direction from the object side to the image side, the refractive index of the first concave lens is greater than that of the first convex lens, and the sixth lens comprises a second convex lens and a second concave lens cemented in sequence along the optical axis direction from the object side to the image side, the refractive index of the first concave lens is 1.7-2.1, and the refractive index of the first convex lens is 1.5-1.

8.

3. The endoscopic imaging system of claim 1, wherein, The total field of view angle is 75-85 degrees.

4. The endoscopic imaging system of claim 1, wherein, The endoscope imaging system satisfies the following optical parameter conditions: Wherein, f is the total effective focal length of the endoscope imaging system, and the unit is millimeter, and EPD is the entrance pupil diameter of the endoscope imaging system, and the unit is millimeter.

5. The endoscopic imaging system of claim 1, wherein, The endoscope imaging system also satisfies the following optical parameter conditions: Wherein, f1 is the effective focal length of the objective lens, and the unit is millimeter, and f is the total effective focal length of the endoscope imaging system, and the unit is millimeter.

6. The endoscopic imaging system of claim 1, wherein, The endoscope imaging system also satisfies the following optical parameter conditions: Wherein, D is the maximum diameter of the effective surface of the optical element in the endoscope imaging system, and the unit is millimeter.

7. The endoscopic imaging system of claim 1, wherein, The rod lens groups on both sides of the optical axis direction are symmetrically arranged relative to the center of the rod lens group in the middle position.

8. The endoscopic imaging system of claim 7, wherein, Each group of the rod lens group comprises a first rod lens, a tenth lens, an eleventh lens and a second rod lens arranged in sequence and spaced apart from each other along the optical axis direction from the object side to the image side, and the tenth lens and the eleventh lens are both double cemented lenses.

9. The endoscopic imaging system of claim 8, wherein, The object side surface and the image side surface of the first rod lens and the second rod lens are both convex, the tenth lens comprises a third convex lens and a third concave lens cemented along the optical axis direction from the object side to the image side, the object side surface and the image side surface of the third convex lens are both convex, the object side surface and the image side surface of the third concave lens are both concave, the eleventh lens comprises a fourth concave lens and a fourth convex lens cemented along the optical axis direction from the object side to the image side, the object side surface and the image side surface of the fourth concave lens are both concave, and the object side surface and the image side surface of the fourth convex lens are both convex.

10. A rigid endoscope, characterized by An endoscope imaging system as claimed in any one of claims 1 to 9 is applied.

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