3D endoscope imaging system and optical lens

Abstract

The invention discloses a 3D endoscope imaging system and an optical lens, and relates to the technical field of optical lenses. The invention provides a 3D endoscope imaging system, which comprises a first lens group, and the first lens group comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a fifth lens, a sixth lens and a seventh lens which are sequentially arranged along an optical axis from an object side to an image side, the second lens has positive diopter, the object side surface is a concave surface, and the image side surface is a convex surface; the third lens has negative diopter, and the object side surface and the image side surface of the third lens are convex surfaces; the fourth lens has positive diopter, and the object side surface and the image side surface of the fourth lens are concave surfaces; the fifth lens has negative diopter, and the object side surface and the image side surface of the fifth lens are convex surfaces; the first bonding lens comprises a sixth lens and a seventh lens, the sixth lens has positive diopter, the object side surface and the image side surface of the sixth lens are convex surfaces, the seventh lens has negative diopter, the object side surface of the seventh lens is a concave surface, and the image side surface of the seventh lens is a convex surface. The objective of the invention is to enhance the imaging effect of the endoscope.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical lenses, in particular to a 3D endoscope imaging system and an optical lens. BACKGROUND

[0002] With the continuous progress of science and technology, as a key component of endoscope imaging systems, the optimization of the performance of optical lenses plays a crucial role in improving the imaging quality and diagnosis and treatment effect of endoscopes. Traditional endoscope imaging systems have been unable to meet the needs of modern medicine in some aspects, such as limited field of view, low image resolution, and inconvenience in operation, etc.

[0003] Therefore, an innovative optical lens and 3D endoscope imaging system are urgently needed to enhance the imaging effect of endoscopes. SUMMARY

[0004] The main purpose of the present application is to provide a 3D endoscope imaging system and an optical lens, which aims to enhance the imaging effect of endoscopes.

[0005] To achieve the above-mentioned purpose, in a first aspect, the present application provides a 3D endoscope imaging system, comprising a first lens group, the first lens group comprising, in order from the object side to the image side along the optical axis: a first lens having a positive refractive power and a flat object side surface and a concave image side surface; a second lens having a positive refractive power and a concave object side surface and a convex image side surface; a third lens having a negative refractive power and both the object side surface and the image side surface being convex; a fourth lens having a positive refractive power and both the object side surface and the image side surface being concave; a fifth lens having a negative refractive power and both the object side surface and the image side surface being convex; a first cemented lens comprising a sixth lens and a seventh lens, the sixth lens having a positive refractive power and both the object side surface and the image side surface being convex, and the seventh lens having a negative refractive power and a concave object side surface and a convex image side surface.

[0006] Optionally, the first lens is of aspherical surface type, and the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens are all of spherical surface type.

[0007] Optionally, the clear aperture of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the first cemented lens is less than 3.5mm.

[0008] Optionally, an aperture stop is arranged between the image side surface of the third lens and the object side surface of the fourth lens.

[0009] Optionally, the first lens group satisfies: 14.30mm < f2 < 15.89mm, 3.30mm < f4 < 3.35mm, 7.25mm < f6 < 8.13mm; wherein f2, f4 and f6 are focal lengths of the second lens, the fourth lens and the first cemented lens respectively.

[0010] Optionally, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens are all made of glass, and each lens satisfies: 1.72 < Nd1 < 1.75, 28 < Vd1 < 33, wherein Nd1 represents the refractive index of the first lens, and Vd1 represents the Abbe number of the first lens; 1.60 < Nd2 < 1.62, 64 < Vd2 < 66, wherein Nd2 represents the refractive index of the second lens and the sixth lens, and Vd2 represents the Abbe number of the second lens and the sixth lens; 1.67 < Nd3 < 1.68, 30 < Vd3 < 33, wherein Nd3 represents the refractive index of the third lens and the fourth lens, and Vd3 represents the Abbe number of the third lens and the fourth lens; 1.50 < Nd4 < 1.52, 62 < Vd4 < 64, wherein Nd4 represents the refractive index of the fifth lens, and Vd4 represents the Abbe number of the fifth lens; 1.90 < Nd5 < 1.94, 18 < Vd5 < 22, wherein Nd5 represents the refractive index of the seventh lens, and Vd5 represents the Abbe number of the seventh lens.

[0011] Optionally, further comprising a light splitting prism and an imaging surface, the light splitting prism is located between the first lens group and the imaging surface; The first lens group is used to guide the reflected light of the object to be observed on the object side to the light splitting prism, The included angle between the light splitting surface of the light splitting prism and the optical axis is 45°, so that the light in the visible light band can be transmitted at the light splitting surface and imaged at the imaging surface, and the light in the infrared band can be reflected at the light splitting surface.

[0012] Optionally, a relay lens group is further arranged between the light splitting prism and the imaging surface, the relay lens group comprises a second cemented lens and a third cemented lens; The second cemented lens comprises an eighth lens and a ninth lens, the eighth lens has a negative refractive power and the object side surface is a convex surface and the image side surface is a concave surface, and the ninth lens has a positive refractive power and both the object side surface and the image side surface are convex surfaces; The third cemented lens comprises a tenth lens and an eleventh lens, the tenth lens has a positive refractive power and both the object side surface and the image side surface are convex surfaces, and the eleventh lens has a negative refractive power and the object side surface is a concave surface and the image side surface is a plane.

[0013] Optionally, the relay lens group satisfies: 15.55mm < f7 < 17.21mm, 10.13mm < f8 < 12.32mm, where f7 is the focal length of the second cemented lens, and f8 is the focal length of the third cemented lens.

[0014] Optionally, the second cemented lens and the third cemented lens are both made of glass, and each lens satisfies: 1.80 < Nd6 < 1.85, 35 < Vd6 < 38, where Nd6 represents the refractive index of the eighth lens, and Vd6 represents the Abbe number of the eighth lens; 1.68 < Nd7 < 1.74, 52 < Vd7 < 55, where Nd7 represents the refractive index of the ninth lens, and Vd7 represents the Abbe number of the ninth lens; 1.70 < Nd8 < 1.84, 51 < Vd8 < 53, where Nd8 represents the refractive index of the tenth lens, and Vd8 represents the Abbe number of the tenth lens; 1.79 < Nd9 < 1.82, 30 < Vd9 < 34, where Nd9 represents the refractive index of the eleventh lens, and Vd9 represents the Abbe number of the eleventh lens.

[0015] Optionally, the 3D endoscope imaging system satisfies: -11.5 < TTL / f < -15.6, where f is the effective focal length of the 3D endoscope imaging system, and TTL is the total optical length of the 3D endoscope imaging system.

[0016] In a second aspect, the present application provides an optical lens comprising the 3D endoscope imaging system as described above.

[0017] The present application can achieve the following beneficial effects: The 3D endoscope imaging system and the optical lens provided by the embodiments of the present application can effectively correct chromatic aberration, coma, astigmatism and other monochromatic aberrations through the alternating combination of positive and negative diopter lenses, so as to obtain clear and sharp images, which is conducive to observing fine tissues in medical diagnosis by the endoscope; the first cemented lens can reduce chromatic dispersion and chromatic aberration by cementing the sixth lens and the seventh lens, so as to ensure accurate color restoration during color imaging and avoid color edges or blurring; the first lens group has a compact structure, a moderate number of lenses and a reasonable arrangement, which is suitable for the slim design of the endoscope, is convenient for insertion into the body cavity, and at the same time maintains the optical performance. The first lens and the second lens both have positive diopter, which can efficiently collect light and improve image brightness as the front end of the system, and is suitable for the low light environment common in endoscopes; the first lens group can provide a basis for stereoscopic vision, support multi-view imaging of double-lens or single-lens through the control of light path and aberration, and realize depth perception and 3D reconstruction. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 A light ray guiding schematic diagram of a first lens group and a light splitting prism of an embodiment of the present application; Figure 2 A schematic diagram of a two-channel system of an embodiment of the present application; Figure 3 A visible light band diffraction MTF diagram when no relay lens group is arranged in an embodiment of the present application; Figure 4 An infrared band diffraction MTF diagram when no relay lens group is arranged in an embodiment of the present application; Figure 5 A relative illuminance diagram in a visible light band when no relay lens group is arranged in an embodiment of the present application; Figure 6 A spot diagram in a visible light band when no relay lens group is arranged in an embodiment of the present application; Figure 7 A distortion field curvature diagram in a visible light band when no relay lens group is arranged in an embodiment of the present application; Figure 8 A light ray propagation schematic diagram after a relay lens group is arranged in an embodiment of the present application; Figure 9 A visible light band diffraction MTF diagram when a relay lens group is arranged in an embodiment of the present application; Figure 10 An infrared band diffraction MTF diagram when a relay lens group is arranged in an embodiment of the present application; Figure 11 A relative illuminance diagram in a visible light band when a relay lens group is arranged in an embodiment of the present application; Figure 12 A spot diagram in a visible light band when a relay lens group is arranged in an embodiment of the present application; Figure 13 A distortion field curvature diagram in a visible light band when a relay lens group is arranged in an embodiment of the present application.

[0019] Reference signs in the drawings are as follows: G1-first lens, G2-second lens, G3-third lens, G4-fourth lens, G5-fifth lens, G6-sixth lens, G7-seventh lens, G8-eighth lens, G9-ninth lens, G10-tenth lens, G11-eleventh lens, 10-aperture stop, 20-light splitting prism, 30-imaging surface.

[0020] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0021] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort should fall within the protection scope of the present application.

[0022] It should be noted that all the direction indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present application are only used to explain the relative position relationship, motion condition, etc. between components in a certain specific posture (as shown in the drawings), and if the specific posture changes, the direction indications will also change accordingly.

[0023] In the present application, unless otherwise explicitly specified and limited, the terms “connection”, “fixation” and the like should be understood in a broad sense, for example, “fixation” can be fixed connection, or detachable connection, or integral; can be mechanical connection, or electrical connection; can be direct connection, or indirect connection through an intermediate medium; can be internal connection of two elements or interaction relationship between two elements, unless otherwise explicitly limited. For a person of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0024] In addition, if the present application has a description of “first”, “second” and the like, the description of “first”, “second” and the like is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by “first” and “second” can explicitly or implicitly include at least one of the features. In addition, the meaning of “and / or” appearing throughout the text includes three parallel solutions. For example, “A and / or B” includes A solution, or B solution, or A and B solution. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the fact that a person of ordinary skill in the art can realize it. When the combination of technical solutions contradicts each other or cannot be realized, it should be considered that the combination of technical solutions does not exist, and is not within the protection scope of the present application.

[0025] Embodiment 1 With reference to Figure 1 The first embodiment of the present application provides a 3D endoscope imaging system, comprising a first lens group, the first lens group comprising, in order from the object side to the image side along the optical axis: a first lens G1 having a positive refractive power and an object-side surface being a plane and an image-side surface being a concave surface; a second lens G2 having a positive refractive power and an object-side surface being a concave surface and an image-side surface being a convex surface; a third lens G3 having a negative refractive power and both the object side surface and the image side surface being convex; a fourth lens G4 having a positive refractive power and both the object side surface and the image side surface being concave; a fifth lens G5 having a negative refractive power and both the object side surface and the image side surface being convex; a first cemented lens comprising a sixth lens G6 having a positive refractive power and both the object side surface and the image side surface being convex, and a seventh lens G7 having a negative refractive power and the object side surface being concave and the image side surface being convex.

[0026] Specifically, the first lens G1 acts as an entrance lens of the system, mainly responsible for light collection and preliminary focusing. The object side surface of the first lens G1 is flat, which can reduce distortion and aberration, and at the same time protect the first lens group. The image side surface of the first lens G1 is concave, which helps to control the direction of light propagation and provide a moderate light angle for the subsequent lenses. The second lens G2 continues to focus the light and begins to correct the aberration. The concave object side surface of the second lens G2 can compensate for the spherical or coma aberration introduced by the first lens G1, and the convex image side surface of the second lens G2 enhances the convergence ability and improves the system focal length efficiency. The third lens G3 is mainly used for diverging light and correcting aberrations such as field curvature and astigmatism generated by the first lens G1 and the second lens G2. The double-convex design of the third lens G3 helps to balance the optical path, control the chief ray angle, and avoid image edge distortion. The fourth lens G4 has a positive refractive power, and both the object side surface and the image side surface of the fourth lens G4 are concave, which can be used for special aberration correction such as Petzval field curvature or distortion. The fourth lens G4 can adjust the optical path to ensure a flat image surface and improve the edge image quality. The fifth lens G5 is used to further diverge the light, which cooperates with the fourth lens G4 to optimize the aberration correction. The double-convex design of the fifth lens G5 can be used to control the back focal length of the system to adapt to the position of the imaging sensor of the endoscope. The sixth lens G6 acts as a positive lens of the first cemented lens, providing the main convergence ability while reducing chromatic dispersion; the seventh lens G7 acts as a negative lens of the first cemented lens, which, combined with the sixth lens G6, corrects chromatic and monochromatic aberrations through the cemented surface. The concave object side surface of the seventh lens G7 helps to match the optical path, and the convex image side surface of the seventh lens G7 maintains the convergence trend of the light. The first cemented lens is a key chromatic aberration correction element, which reduces the separation of light lines of different wavelengths through the cementing of positive and negative lenses, ensuring image color consistency and clarity.

[0027] The first lens group adopts an alternating positive and negative design, systematically corrects various aberrations, the first lens G1 and the second lens G2 are responsible for initial focusing, the third lens G3 and the fifth lens G5 introduce a diverging effect with negative refractive power, the fourth lens G4 adjusts the optical path with positive refractive power, the first cemented lens processes chromatic aberration, the whole realizes aberration balance and improves image quality. The first cemented lens reduces the distance between the air and the glass interface, reduces the adjustment difficulty and reflection loss, improves the system stability and environmental interference resistance, and is suitable for frequent use of endoscopes. The overall first lens group takes into account wide angle, small size and high resolution, and meets the requirements of 3D endoscopes for depth information and stereoscopic vision. The lens curvature and order optimize the optical path to ensure high-performance imaging in limited space.

[0028] Optionally, the first lens G1 is aspherical, and the second lens G2, the third lens G3, the fourth lens G4, the fifth lens G5, the sixth lens G6 and the seventh lens G7 are all spherical. While ensuring imaging quality, the processing difficulty and manufacturing cost are effectively reduced. The aspherical first lens G1 can more accurately correct the initial light entering the system, reducing aberrations, and subsequent spherical lenses simplify production processes and improve production efficiency while meeting optical performance requirements, making the optical lens have good performance, better cost performance and market competitiveness.

[0029] Optionally, the first lens G1, the second lens G2, the third lens G3, the fourth lens G4, the fifth lens G5 and the first cemented lens have an aperture diameter of less than 3.5mm.

[0030] Optionally, an aperture stop 10 is arranged between the image side of the third lens G3 and the object side of the fourth lens G4. By arranging the aperture stop 10 between the third lens G3 and the fourth lens G4, the diameters of the front and rear lenses can be optimized, and the first lens G1 and the second lens G2 can be prevented from becoming too large, thereby facilitating the miniaturization and light weight of the entire system.

[0031] Optionally, the first lens group satisfies: 14.30mm < f2 < 15.89mm, 3.30mm < f4 < 3.35mm, 7.25mm < f6 < 8.13mm; wherein f2, f4 and f6 are the focal lengths of the second lens G2, the fourth lens G4 and the first cemented lens respectively. Specifically, the focal length of the second lens G2 is for example: 14.30mm, 14.50mm, 14.80mm, 14.90mm, 15.10mm, 15.80mm and 15.89mm, etc., the focal length of the fourth lens G4 is for example: 3.30mm, 3.31mm, 3.32mm, 3.33mm, 3.34mm and 3.35mm, etc., and the focal length of the first cemented lens is for example: 7.25mm, 7.30mm, 7.50mm, 7.70mm, 7.90mm, 8.10mm and 8.13mm, etc.

[0032] Optionally, the first lens G1, the second lens G2, the third lens G3, the fourth lens G4, the fifth lens G5, the sixth lens G6 and the seventh lens G7 are all made of glass, and each lens satisfies: 1.72 < Nd1 < 1.75, 28 < Vd1 < 33, wherein Nd1 represents the refractive index of the first lens G1, for example 1.72, 1.73, 1.74 and 1.75, etc.; Vd1 represents the Abbe number of the first lens G1, for example 28, 29, 30, 31, 32 and 33, etc.; the first lens G1 is the first positive lens of the system, the high refractive index enables it to provide sufficient positive power with smaller curvature, effectively reducing the system aperture and spherical aberration, and the low Abbe number introduces a large amount of chromatic aberration, especially the focal separation of blue and red light.

[0033] 1.60 < Nd2 < 1.62, 64 < Vd2 < 66, wherein Nd2 represents the refractive index of the second lens G2 and the sixth lens G6, for example 1.60, 1.61 and 1.62, etc.; Vd2 represents the Abbe number of the second lens G2 and the sixth lens G6, for example 64, 65 and 66, etc.; the second lens G2 and the sixth lens G6 have a medium refractive index and an extremely high Abbe number, the second lens G2 immediately follows the first lens G1, and its low dispersion characteristic can immediately begin to compensate for most of the chromatic aberration generated by the first lens G1, the sixth lens G6 as a positive lens in the cemented group also uses its high Abbe number to offset the dispersion of negative lenses. With a medium refractive index, the cost and processing difficulty are balanced while providing positive power, and an extremely high Abbe number material is usually difficult to have a high refractive index.

[0034] 1.67≤Nd3≤1.68, 30≤Vd3≤33, where Nd3 represents the refractive index of the third lens G3 and the fourth lens G4, such as 16.7, 1.678, and 1.68; Vd3 represents the Abbe number of the third lens G3 and the fourth lens G4, such as 30, 31, 32, and 33. The third lens G3 and the fourth lens G4 are made of medium to high refractive index glass with low Abbe number. They are responsible for correcting the main monochromatic aberrations, such as spherical aberration and field curvature. Their high refractive index helps achieve the required negative / positive optical power with a small aperture and controls higher-order aberrations; their low Abbe number allows for partial cancellation of chromatic aberrations due to the positive and negative optical powers of the third lens G3 and the fourth lens G4 being close in position. Simultaneously, the overall dispersion effect of the third lens G3 and the fourth lens G4 can be optimized globally in conjunction with the first lens G1 and subsequent cemented lenses.

[0035] 1.50≤Nd4≤1.52, 62≤Vd4≤64, where Nd4 represents the refractive index of the fifth lens G5, such as 1.50, 1.51, and 1.52; Vd4 represents the Abbe number of the fifth lens G5, such as 62, 63, and 64; the fifth lens G5 uses glass with a low refractive index and an extremely high Abbe number. As a negative lens, the fifth lens G5 uses a high Abbe number material primarily to provide negative optical power to correct astigmatism and field curvature, while simultaneously introducing very little chromatic aberration, avoiding the additional chromatic aberration problems typically associated with negative lenses. The reason for using a low refractive index is that this type of glass is usually inexpensive, has good chemical stability and weather resistance, and is suitable for placement at the rear of the system.

[0036] 1.90≤Nd5≤1.94, 18≤Vd5≤22, where Nd5 represents the refractive index of the seventh lens G7, such as 1.90, 1.91, 1.92, 1.93, and 1.94; Vd5 represents the Abbe number of the seventh lens G7, such as 18, 19, 20, 21, and 22; the seventh lens G7 uses glass with ultra-high refractive index and ultra-low Abbe number. The seventh lens G7 acts as a negative lens in the first cemented lens, and its high refractive index allows it to have a very steep... The sharp concave surface provides powerful negative optical power without significantly increasing the overall thickness of the cemented assembly, which is beneficial for system miniaturization. The ultra-low Abbe number seventh lens G7 and the high Abbe number sixth lens G6 form an extreme chromatic aberration compensation pair. According to the achromatic formula for cemented lenses, the ratio of their optical power should be inversely proportional to the ratio of their Abbe numbers. The extremely high dispersion capability of the seventh lens G7 means that only a very small piece is needed to perfectly cancel the secondary spectrum and advanced chromatic aberrations left by all the previous lenses, thus achieving chromatic aberration correction.

[0037] Specifically, refractive index (Nd) is an indicator of the degree to which light bends in a medium. High refractive index materials can use a smaller curvature for the same refractive power, which helps in lens thinning and aberration control. Abbe number (Vd) is an indicator of the degree of dispersion of a medium. A high Abbe number (greater than 55) indicates low dispersion, while a low Abbe number (less than 35) indicates high dispersion. To correct chromatic aberration, lenses with high and low Abbe numbers need to be used in combination. By carefully matching high and low Abbe number glass, it means that there will be no color fringing in the image, and the focus will remain consistent at different wavelengths, thus achieving extremely high color fidelity and image sharpness. The first lens group widely uses high refractive index glass, such as the first lens G1, the third lens G3, the fourth lens G4, and the seventh lens. This allows for effective correction of aberrations, such as spherical aberration and coma, by controlling the lens curvature, even under the strict limitation of an aperture smaller than 3.5mm. High refractive index materials are key to achieving both miniaturization and high performance. The selection of materials not only considers chromatic aberration but also takes into account monochromatic aberration. Combining materials with different refractive indices provides more "control variables" to balance spherical aberration, field curvature, distortion, etc., ensuring uniform high resolution from the image center to the edge. Using a first cemented lens and matching its optical properties with the material reduces the number of lenses that need to be individually fixed and the number of air interfaces, making assembly and adjustment easier. It also reduces light energy reflection loss at multiple air interfaces, such as glare, and improves system contrast and signal-to-noise ratio.

[0038] In this embodiment, the physical optical parameters of the entire lens are shown in Table 1 below.

[0039] Table 1. Physical and optical parameters of the imaging system:

[0040] The higher-order coefficients of the aspherical lens in this embodiment are shown in Table 2 below.

[0041] Table 2. Coefficients of Higher-Order Terms for Aspherical Lenses:

[0042] In this embodiment, a high-definition imaging system with a focal length of 1.43mm, an f / # of 6.22, a maximum field of view of 86°, a total length of 15.81mm, and a full-image height of 3.9mm is achieved; wherein, the relative illumination of the lens is >80%; and the optical distortion of the lens is <20%.

[0043] Example 2 Based on Embodiment 1, this embodiment provides a 3D endoscope imaging system, which also includes a beam splitter 20 and an imaging surface 30, wherein the beam splitter 20 is located between the first lens group and the imaging surface 30. The first lens group is used to guide the reflected light from the object to be observed on the object side to the beam splitter 20; The angle between the beam-splitting surface of the beam-splitting prism 20 and the optical axis is 45°, so that the light in the visible light band can be transmitted at the beam-splitting surface and imaged at the imaging surface 30, and the light in the infrared band can be reflected at the beam-splitting surface.

[0044] Specifically, the beam-splitting prism 20 is located between the first lens group and the imaging surface 30. This means that the light first passes through the precise first lens group to correct aberrations and then enters the beam-splitting prism 20. The beam-splitting surface is an optical thin film with an angle of 45° with the optical axis. The light in the visible light band can be transmitted at the beam-splitting surface and directly reach the imaging surface 30 for imaging, which is used to obtain the true color and detail information of the object. The light in the infrared band is reflected at the beam-splitting surface, changing the direction by 90° and being guided to another path. Since the infrared light is reflected by the beam-splitting surface and does not reach the visible light sensor on the main imaging surface 30, it avoids the contamination of the visible light color image by the infrared light and ensures the accuracy of color reproduction. A complete 3D endoscope usually requires two independent optical paths to simulate the binocular parallax of the human eye. The system described here is only one of the channels. During use, the system will include two identical combinations of the first lens group, the beam-splitting prism 20 and the imaging surface 30, arranged side by side at a certain distance. They collect images simultaneously, generate depth information by calculating the parallax of the two images, and finally synthesize a 3D image.

[0045] Optionally, a relay lens group is further provided between the beam-splitting prism 20 and the imaging surface 30. The relay lens group includes a second cemented lens and a third cemented lens; The second cemented lens includes an eighth lens G8 and a ninth lens G9. The eighth lens G8 has a negative diopter, the object side is convex, and the image sides are concave. The ninth lens G9 has a positive diopter, and the object side and the image sides are convex; The third cemented lens includes a tenth lens G10 and an eleventh lens G11. The tenth lens G10 has a positive diopter, and the object side and the image sides are convex. The eleventh lens G11 has a negative diopter, the object side is concave, and the image side is flat.

[0046] Optionally, the relay lens group satisfies: 15.55mm < f7 < 17.21mm, 10.13mm < f8 < 12.32mm, where f7 is the focal length of the second cemented lens, such as 15.55mm, 15.60mm, 15.70mm, 15.90mm, 15.55mm, 16.00mm, 16.55mm, 17.00mm, and 17.21mm, etc., and f8 is the focal length of the third cemented lens, such as 10.13mm, 10.30mm, 10.50mm, 10.90mm, 11.10mm, 11.60mm, 11.90mm, 12.10mm, 12.20mm, and 12.32mm, etc.

[0047] Optionally, both the second and third cemented lenses are made of glass, and each lens satisfies the following: 1.80≤Nd6≤1.85、35≤Vd6≤38, where Nd6 represents the refractive index of the eighth lens G8 and Vd6 represents the Abbe number of the eighth lens G8; 1.68≤Nd7≤1.74、52≤Vd7≤55, where Nd7 represents the refractive index of the ninth lens G9 and Vd7 represents the Abbe number of the ninth lens G9; 1.70≤Nd8≤1.84、51≤Vd8≤53, where Nd8 represents the refractive index of the tenth lens G10 and Vd8 represents the Abbe number of the tenth lens G10; 1.79≤Nd9≤1.82、30≤Vd9≤34, where Nd9 represents the refractive index of the eleventh lens G11 and Vd9 represents the Abbe number of the eleventh lens G11.

[0048] Optionally, the 3D endoscope imaging system satisfies: -11.5≤TTL / f≤-15.6; where f is the effective focal length of the 3D endoscope imaging system and TTL is the total optical length of the 3D endoscope imaging system.

[0049] In this embodiment, the second cemented lens is dominated by the ninth lens G9 with positive refractive power, resulting in a strong positive optical power for the entire second cemented lens. As the first part of the relay lens group, the second cemented lens powerfully converges the light rays from the beam splitter 20, which have already been corrected by the previous group, reducing the lateral size of the beam. Its longer focal length is suitable for finely correcting the field curvature and astigmatism remaining from the first lens group, ensuring that the image plane is a flat plane. The eighth lens G8 has a high refractive index, enabling it to provide sufficient negative optical power at small curvatures. It is cemented with the ninth lens G9 to correct chromatic aberration. The low Abbe number of the eighth lens G8 is paired with the medium-high Abbe number of the ninth lens G9 to form a highly efficient achromatic unit.

[0050] The third cemented lens is dominated by the positive diopter of the tenth lens G10, but the negative diopter of the eleventh lens G11 provides a balancing effect. The third cemented lens is the last lens group in the optical path, directly facing the image sensor. The planar image-side surface of the eleventh lens G11 ensures that light enters each pixel of the sensor chip at a near-perpendicular angle, maximizing edge illumination and eliminating color drift and vignetting. The combination of the concave and planar surfaces of the eleventh lens G11 precisely controls and ultimately eliminates image distortion, ensuring undistorted images. The eleventh lens G11 also uses high-refractive-index and higher-dispersion glass, allowing it to provide sufficient negative diopter with a concave surface of relatively low curvature, forming a high-performance achromatic combination with the tenth lens G10. By adding a relay lens group, the optical path transmission distance is effectively extended while maintaining the overall optical performance stability of the system.

[0051] In this embodiment, the physical optical parameters of the entire lens are shown in Table 3 below.

[0052] Table 3. Physical and optical parameters of the imaging system:

[0053] The higher-order coefficients of the aspherical lens in this embodiment are shown in Table 4 below.

[0054] Table 4. Coefficients of Higher-Order Terms for Aspherical Lenses:

[0055] Embodiment 2 of the present invention achieves a focal length of -2.51mm and an F / # of 6.12. Compared with Embodiment 1, this embodiment adds a relay lens group with a total length of 71.04mm. The relative illumination of the lens is >80%, and the optical distortion of the lens is <20%.

[0056] In both Embodiment 1 and Embodiment 2, the structure of the first lens group is the same. Embodiment 2 is a further improvement on Embodiment 1, adding a relay lens group consisting of a second cemented lens and a third cemented lens between the beam splitter prism 20 and the imaging surface 30. Two structures are provided: one with a relay lens group and one without, to suit different medical endoscopic imaging needs. Embodiment 2, by introducing the relay lens group, effectively extends the optical path transmission distance while maintaining the overall optical performance stability of the system. In practical applications, Embodiment 1 is more suitable for scenarios with high space constraints, such as disposable endoscopes or miniature surgical instruments; while the relay lens group design of Embodiment 2 is more suitable for 3D stereoscopic imaging systems requiring long working distances, such as complex surgical equipment like laparoscopes or arthroscopes.

[0057] In Examples 1 and 2 of the present invention, the optimal object distance of the optical system is set to 35 mm. Figure 3 ,Figure 4 , Figure 9 and Figure 10 Analysis of the diffraction MTF curves of the lens in the visible and infrared bands shows that in the visible band (0.486um~0.656um), when the spatial frequency reaches 120lp / mm, the MTF value of each field of view is >0.3, and in the infrared band (0.700um~0.800um), when the spatial frequency reaches 120lp / mm, the MTF value of each field of view is >0.2. This indicates that both examples of the invention meet the angular resolution requirements specified by the endoscope standard.

[0058] In Examples 1 and 2 of the present invention, the illuminance curves of the optical system are as follows: Figure 5 and Figure 11 As can be seen, the relative illumination of the optical system is ≥80%, which ensures the uniformity of the image and can obtain a clearer image with consistent brightness. This avoids problems such as vignetting caused by uneven illumination, providing doctors with a more accurate and comprehensive surgical field of vision, and helping to improve the precision and safety of the surgery.

[0059] In Examples 1 and 2 of the present invention, the dot diagram of the optical system is as follows: Figure 6 and Figure 12 As can be seen, the spot diameters at all field-of-view heights of the optical system are small and the spot distribution is uniform, indicating that the optical system has good imaging quality and can effectively reduce the impact of aberrations on the imaging effect, resulting in a clearer final image. Figure 7 and Figure 13 This reflects the distortion and field curvature of the optical system, by Figure 7 and Figure 13 It is evident that the aberrations are well controlled, which effectively demonstrates that the optical system has high imaging quality.

[0060] Example 3 Based on Embodiment 1, this embodiment provides an optical lens, including the 3D endoscopic imaging system as described above.

[0061] Specifically, the optical lens includes a main lens barrel. A first lens group, a beam splitter 20, and a relay lens group are coaxially fixed inside the lens barrel in sequence along the optical axis from the object side to the image side, maintaining a predetermined air gap. An infrared light path exit window is provided on the side wall of the main lens barrel corresponding to the reflected light path of the beam splitter 20. This window can be used to mount a subsequent infrared camera or guide an infrared beam. An infrared anti-reflection window can be optionally installed in this window. The end of the main lens barrel is the image side, which has a sensor mounting flange. This flange has a positioning reference surface and high-precision threaded holes for rigidly and accurately connecting and fixing the image sensor module, ensuring that the sensor target surface is perpendicular to the optical axis and located at the designed image plane position. To achieve 3D stereoscopic vision, the optical lens in practical applications includes two identical and parallel imaging systems, as in Example 1, with a fixed distance between the optical axes of the two systems. These two systems can be integrated into a dual-channel lens barrel or mounted as two independent modules on a common structural component.

[0062] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A 3D endoscopic imaging system, characterized in that, Comprising a first lens group, the first lens group includes, arranged in sequence along the optical axis from the object side to the image side: A first lens, which has a positive diopter and the object side is a plane, and the image side is a concave surface; A second lens, which has a positive diopter and the object side is a concave surface, and the image side is a convex surface; A third lens, which has a negative diopter and both the object side and the image side are convex surfaces; A fourth lens, which has a positive diopter and both the object side and the image side are concave surfaces; A fifth lens, which has a negative diopter and both the object side and the image side are convex surfaces; A first cemented lens, which includes a sixth lens and a seventh lens, the sixth lens has a positive diopter and both the object side and the image side are convex surfaces, and the seventh lens has a negative diopter and the object side is a concave surface, and the image side is a convex surface.

2. The 3D endoscopic imaging system as described in claim 1, characterized in that, The first lens is of an aspherical surface type, and the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens are all of spherical surface types.

3. The 3D endoscopic imaging system as described in claim 1, characterized in that, The clear apertures of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the first cemented lens are less than 3.5 mm.

4. The 3D endoscopic imaging system as described in claim 1, characterized in that, An aperture stop is provided between the image side of the third lens and the object side of the fourth lens.

5. The 3D endoscopic imaging system as described in claim 1, characterized in that, The first lens group satisfies: 14.30 mm < f2 < 15.89 mm, 3.30 mm < f4 < 3.35 mm, 7.25 mm < f6 < 8.13 mm; where f2, f4 and f6 are the focal lengths of the second lens, the fourth lens and the first cemented lens respectively.

6. The 3D endoscopic imaging system as described in claim 1, characterized in that, The first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens are all made of glass, and each lens satisfies: 1.72 ≤ Nd1 ≤ 1.75, 28 ≤ Vd1 ≤ 33, where Nd1 represents the refractive index of the first lens, and Vd1 represents the Abbe number of the first lens; 1.60 ≤ Nd2 ≤ 1.62, 64 ≤ Vd2 ≤ 66, where Nd2 represents the refractive indices of the second lens and the sixth lens, and Vd2 represents the Abbe numbers of the second lens and the sixth lens; 1.67 ≤ Nd3 ≤ 1.68, 30 ≤ Vd3 ≤ 33, where Nd3 represents the refractive indices of the third lens and the fourth lens, and Vd3 represents the Abbe numbers of the third lens and the fourth lens; 1.50 ≤ Nd4 ≤ 1.52, 62 ≤ Vd4 ≤ 64, where Nd4 represents the refractive index of the fifth lens, and Vd4 represents the Abbe number of the fifth lens; 1.90 ≤ Nd5 ≤ 1.94, 18 ≤ Vd5 ≤ 22, where Nd5 represents the refractive index of the seventh lens, and Vd5 represents the Abbe number of the seventh lens.

7. The 3D endoscopic imaging system as described in claim 1, characterized in that, It further includes a beam splitting prism and an imaging surface, and the beam splitting prism is located between the first lens group and the imaging surface; The first lens group is used to guide the reflected light of the object to be observed on the object side to the beam splitting prism; The included angle between the beam splitting surface of the beam splitting prism and the optical axis is 45°, so that the light in the visible light band can be transmitted at the beam splitting surface and imaged at the imaging surface, and the light in the infrared band can be reflected at the beam splitting surface.

8. The 3D endoscopic imaging system as described in claim 7, characterized in that, A relay lens group is further provided between the beam splitting prism and the imaging surface, and the relay lens group includes a second cemented lens and a third cemented lens; The second cemented lens includes an eighth lens and a ninth lens. The eighth lens has a negative refractive power, with a convex object side and a concave image side. The ninth lens has a positive refractive power, with both the object side and the image side being convex. The third cemented lens includes a tenth lens and an eleventh lens. The tenth lens has a positive refractive power, with both the object side and the image side being convex. The eleventh lens has a negative refractive power, with a concave object side and a flat image side.

9. The 3D endoscopic imaging system as described in claim 8, characterized in that, The relay lens group satisfies: 15.55 mm < f7 < 17.21 mm, 10.13 mm < f8 < 12.32 mm, where f7 is the focal length of the second cemented lens and f8 is the focal length of the third cemented lens.

10. The 3D endoscopic imaging system as described in claim 8, characterized in that, Both the second cemented lens and the third cemented lens are made of glass, and each lens satisfies: 1.80 ≤ Nd6 ≤ 1.85, 35 ≤ Vd6 ≤ 38, where Nd6 represents the refractive index of the eighth lens and Vd6 represents the Abbe number of the eighth lens. 1.68 ≤ Nd7 ≤ 1.74, 52 ≤ Vd7 ≤ 55, where Nd7 represents the refractive index of the ninth lens and Vd7 represents the Abbe number of the ninth lens. 1.70 ≤ Nd8 ≤ 1.84, 51 ≤ Vd8 ≤ 53, where Nd8 represents the refractive index of the tenth lens and Vd8 represents the Abbe number of the tenth lens. 1.79 ≤ Nd9 ≤ 1.82, 30 ≤ Vd9 ≤ 34, where Nd9 represents the refractive index of the eleventh lens and Vd9 represents the Abbe number of the eleventh lens.

11. The 3D endoscopic imaging system as described in claim 7, characterized in that, The 3D endoscope imaging system satisfies: -11.5 ≤ TTL / f ≤ -15.6; where f is the effective focal length of the 3D endoscope imaging system and TTL is the total optical length of the 3D endoscope imaging system.

12. An optical lens, characterized in that, It includes the 3D endoscope imaging system according to any one of claims 1-11.

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