A large depth of field medical endoscope lens

Abstract

The utility model discloses a big depth of field medical endoscope lens, including lens barrel and the mirror seat of being connected in the lens barrel, its characterized in that: lens barrel is provided with lens assembly and shading component in, lens assembly includes the window mirror, first lens, second lens, third lens, fourth lens, fifth lens, sixth lens and optical filter that set gradually, shading component includes first shading piece, second shading piece, third shading piece, fourth shading piece and fifth shading piece, first shading piece is established between first lens and second lens, second shading piece is established between second lens and third lens, third shading piece is established between third lens and fourth lens, fourth shading piece is established between fourth lens and fifth lens, fifth shading piece is established between fifth lens and sixth lens, the above-mentioned lens can realize high definition imaging in big depth of field range, and need not frequent focusing to clearly show the tissue of near and far, and the structure is simple and practical, and the volume is small, and it is convenient to promote.

Description

Technical Field

[0001] This utility model relates to a large depth-of-field medical endoscope lens, belonging to the field of optical technology. Background Technology

[0002] In the field of medical endoscope technology, existing endoscopic lens optical systems generally face the technical bottleneck of limited depth of field. Traditional endoscopes typically rely on narrowing the aperture to expand the depth of field, but this is limited by optical diffraction effects and light flux attenuation, easily leading to problems such as decreased image resolution and deteriorated signal-to-noise ratio in low-light environments. Furthermore, conventional designs require dynamic adjustment of the focal length via a mechanical focusing mechanism to adapt to observation targets at different distances. This not only increases system complexity but may also cause blurred vision due to focusing lag or camera shake during intracavitary operations, increasing the risk of missing small lesions or deep blood vessels. Although some technologies have attempted to use short focal length wide-angle lenses or hyperfocal length fixed focusing schemes, they still suffer from drawbacks such as difficulty in correcting edge distortion and uneven close-up image quality. Utility Model Content

[0003] This invention provides a large depth-of-field medical endoscope that achieves high-definition imaging over a large depth-of-field range without sacrificing resolution, light throughput, or system reliability, thereby meeting the stringent requirements of precision medicine for intraoperative visual stability and operational continuity.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows: A large depth-of-field medical endoscope includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens arranged sequentially along an optical axis from the object side to the image side. Each of the first to sixth lenses includes an object-side surface facing the object side and allowing imaging light to pass through, and an image-side surface facing the image side and allowing imaging light to pass through. The first lens has a negative refractive index, and its object-side surface is convex, while its image-side surface is concave. The second lens has a negative refractive index, and both its object-side and image-side surfaces are concave. The third lens has a positive refractive index, and both its object-side and image-side surfaces are convex. The fourth lens has a positive refractive index, and both its object-side and image-side surfaces are convex. The fifth lens has a negative refractive index, and both its object-side and image-side surfaces are concave. The sixth lens has a positive refractive index, and both its object-side and image-side surfaces are convex.

[0005] The aforementioned large depth-of-field medical endoscope also includes a light-shielding assembly, which includes a first light-shielding plate, a second light-shielding plate, a third light-shielding plate, a fourth light-shielding plate, and a fifth light-shielding plate. The first light-shielding plate is located between the first lens and the second lens; the second light-shielding plate is located between the second lens and the third lens; the third light-shielding plate is located between the third lens and the fourth lens; the fourth light-shielding plate is located between the fourth lens and the fifth lens; and the fifth light-shielding plate is located between the fifth lens and the sixth lens.

[0006] Each light-shielding plate is ring-shaped, adapted to the light-transmitting diameter of the corresponding lens. The inner hole matches the effective light-transmitting area of ​​the corresponding lens, and the outer circle fits against the inner wall of the lens barrel, providing 360° uniform light blocking. The design of the light-shielding plates can filter non-imaging light rays generated by reflection and refraction from the lens edge (such as reflections from the inner wall of the lens and oblique light scattering), preventing these rays from reaching the imaging surface after multiple reflections within the lens barrel, thus reducing glare, halo, and fogging.

[0007] Of the aforementioned lenses, only the first to sixth lenses have refractive power.

[0008] The lens openings at both ends of the aforementioned lens tube are a window lens and a filter, respectively, and the middle section contains a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens arranged in sequence.

[0009] Each lens is tightly fitted and connected to the inner wall of the lens barrel. For specific methods, refer to existing mature technologies.

[0010] Furthermore, in this optical imaging lens: f1=-0.698, f2=-1.1876, f3=0.7856, f4=0.4929, f5=-0.4410, f6=1.1171, where f1, f2, f3, f4, f5, and f6 are the focal lengths of the first lens, second lens, third lens, fourth lens, fifth lens, and sixth lens, respectively.

[0011] To achieve lightweight design and reduce costs, as a preferred technical solution of this invention, the first, second, third, fourth, fifth, and sixth lenses are all made of plastic aspherical lenses. The aspherical lenses correct for aberrations such as field curvature, astigmatism, spherical aberration, and coma. Since the cost of plastic lenses is far lower than that of glass lenses, the optical lens provided in this embodiment, by using six plastic aspherical lenses, achieves low cost and ensures normal operation of the black light lens even in high and low temperature environments.

[0012] Further optimization reveals that the first lens is made of EP5000 material; the third and fifth lenses are both made of EP8000 material; the second and sixth lenses are both made of APEL5514ML material; and the fourth lens is made of Zeonex K26R material.

[0013] The aforementioned EP5000 is a cyclic olefin copolymer (COC), belonging to Mitsubishi Chemical's "APEL" series of optical grade products; EP8000 is a cyclic olefin copolymer (COC), belonging to Mitsubishi Chemical's "EP" series of high-temperature optical grade products; APEL5514ML is a cyclic olefin copolymer (COC), belonging to Mitsui Chemicals' "APEL" series of high-crystallinity optical grade products; Zeonex K26R is a cyclic olefin polymer (COP), belonging to Japan Zeon Corporation's "ZEONEX" series of optical grade products.

[0014] D263T is an ultrathin borosilicate glass, belonging to the high-end optical glass series of the German company Schott; SAPPHIRE is a single-crystal alumina (α-Al2O3) with a hexagonal crystal structure.

[0015] As one of the preferred implementations, the aforementioned large depth-of-field medical endoscope includes a window mirror, a first lens, a first light-shielding plate, a second lens, a second light-shielding plate, a third lens, a third light-shielding plate, a fourth lens, a fourth light-shielding plate, a fifth lens, a fifth light-shielding plate, a sixth lens, and a filter arranged coaxially from the object side to the image side along the optical axis.

[0016] The aforementioned window mirror, first lens, first light-blocking plate, second lens, second light-blocking plate, third lens, third light-blocking plate, fourth lens, fourth light-blocking plate, fifth lens, fifth light-blocking plate, sixth lens, and filter are arranged coaxially.

[0017] To further improve imaging quality, the radius of curvature of the object-side surface of the first lens is 2.1328±0.0005mm, and the radius of curvature of the image-side surface of the first lens is 0.3549±0.0005mm; the radius of curvature of the object-side surface of the second lens is -9.0420±0.0005mm, and the radius of curvature of the image-side surface of the second lens is 0.7021±0.0005mm; the radius of curvature of the object-side surface of the third lens is 0.5220±0.0005mm, and the radius of curvature of the image-side surface of the third lens is 94.4146±0. The radius of curvature of the object side of the fourth lens is 0.8331±0.0005mm, and the radius of curvature of the image side of the fourth lens is -0.3212±0.0005mm; the radius of curvature of the object side of the fifth lens is -0.6047±0.0005mm, and the radius of curvature of the image side of the fifth lens is 0.6700±0.0005mm; the radius of curvature of the object side of the sixth lens is 2.4281±0.0005mm, and the radius of curvature of the image side of the sixth lens is -0.7580±0.0005mm.

[0018] To further improve image quality, the center-to-center spacing between the first and second lenses is 0.185±0.02 mm; between the second and third lenses is 0.188±0.02 mm; between the third and fourth lenses is 0.224±0.02 mm; between the fourth and fifth lenses is 0.401±0.02 mm; and between the fifth and sixth lenses is 0.288±0.02 mm. More preferably, the center thickness of the first lens is 0.02±0.02 mm; the center thickness of the second lens is 0.31±0.02 mm; the center thickness of the third lens is 0.05±0.02 mm; the center thickness of the fourth lens is 0.13±0.02 mm; the center thickness of the fifth lens is 0.05±0.02 mm; and the center thickness of the sixth lens is 0.07±0.02 mm.

[0019] Any technologies not mentioned in this utility model are based on existing technologies.

[0020] Compared with the prior art, the beneficial effects of this utility model are as follows: The overall design of this utility model, through the multi-layer lens and shield design, and the use of small aperture and aspherical lens to ensure its large depth of field performance, can ensure that the endoscope can clearly display near and far tissues without frequent focusing during medical examinations and surgeries, reducing image blurring caused by changes in distance during surgery. The overall design structure is simple and practical, small in size, has a relatively broad market prospect, and is easy to promote. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the medical endoscope of this utility model; Figure 2 This is a light focusing diagram of the medical endoscope of this utility model; Figure 3 This is a distortion curve of the medical endoscope of this utility model under visible light and an object distance of 6.5mm; In the diagram, 1-window mirror; 2-first lens; 3-lens tube; 4-second lens; 5-third lens; 6-fourth lens; 7-fifth lens; 8-sixth lens; 9-filter; 10-first light shield; 11-second light shield; 12-third light shield; 13-fourth light shield; 14-fifth light shield. Detailed Implementation

[0022] To better understand this utility model, the following embodiments further illustrate the content of this utility model, but the content of this utility model is not limited to the following embodiments.

[0023] The lens has a positive (or negative) refractive index, meaning that the paraxial refractive index of the lens, calculated using Gaussian optics theory, is positive (or negative). The object-side surface (or image-side surface) of the lens is defined as the specific range through which imaging rays pass on the lens surface. The convexity or concavity of a lens surface can be determined using methods commonly known in the field, namely, by the sign of the radius of curvature (R value). The R value is commonly used in optical design software. For the object-side surface, a positive R value indicates a convex surface, and a negative R value indicates a concave surface. Conversely, for the image-side surface, a positive R value indicates a concave surface, and a negative R value indicates a convex surface.

[0024] This utility model discloses a large depth-of-field medical endoscope, comprising a first lens to a sixth lens arranged sequentially along an optical axis from the object side to the image side; each of the first to sixth lenses includes an object-side surface facing the object side and allowing imaging light to pass through, and an image-side surface facing the image side and allowing imaging light to pass through; the first lens has a negative refractive index, the object-side surface of the first lens is convex, and the image-side surface of the first lens is concave; the second lens has a negative refractive index, the object-side surface of the second lens is concave, and the image-side surface of the second lens is concave; the third lens has a positive refractive index. The object-side surface of the third lens is convex, and the image-side surface of the third lens is concave; the fourth lens has positive refractive index, and both its object-side and image-side surfaces are convex; the fifth lens has negative refractive index, and both its object-side and image-side surfaces are concave; the sixth lens has positive refractive index, and both its object-side and image-side surfaces are convex; all six lenses are plastic aspherical lenses; the only lenses with refractive index in this optical imaging lens are the aforementioned first to sixth lenses.

[0025] Preferably, in this optical imaging lens: f1=-0.698, f2=-1.1876, f3=0.7856, f4=0.4929, f5=-0.4410, f6=1.1171, where f1, f2, f3, f4, f5, and f6 are the focal lengths of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens, respectively.

[0026] Preferably, the object-side surface and image-side surface of the first to sixth lenses are both high-order even-order aspherical surfaces, which can correct phase aberration and chromatic aberration and improve image quality.

[0027] The medical endoscope of the present invention will be described in detail below with reference to embodiments.

[0028] Example 1

[0029] like Figure 1As shown, a large depth-of-field medical endoscope includes an endoscope barrel and an endoscope mount connected to the endoscope barrel, and a lens assembly and a light-shielding assembly are disposed inside the endoscope barrel. like Figure 2 As shown, the lens assembly includes, from the object side to the image side along the optical axis, a window mirror 1, a first lens 2, a second lens 4, a third lens 5, a fourth lens 6, a fifth lens 7, a sixth lens 8, and a filter 9; each of the first lens 2 to the sixth lens 8 includes an object side facing the object side and allowing imaging light to pass through, and an image side facing the image side and allowing imaging light to pass through.

[0030] The first lens 2 has a negative refractive index, the object side of the first lens 2 is convex, and the image side of the first lens 2 is concave.

[0031] The second lens 4 has a negative refractive index, and the object side and image side of the second lens 4 are concave.

[0032] The third lens 5 has a positive refractive index, the object side of the third lens 5 is convex, and the image side of the third lens 5 is concave.

[0033] The fourth lens 6 has a positive refractive index, and the object side and the image side of the fourth lens 6 are both convex.

[0034] The fifth lens 7 has a negative refractive index. The object side of the fifth lens 7 is concave, and the image side of the fifth lens 7 is also concave.

[0035] The sixth lens 8 has a positive refractive index, and the object-side surface of the sixth lens 8 is convex, as is the image-side surface of the sixth lens 8.

[0036] Lens 2 through 8 are all plastic aspherical lenses.

[0037] The light-shielding assembly includes a first light-shielding sheet 10, a second light-shielding sheet 11, a third light-shielding sheet 12, a fourth light-shielding sheet 13, and a fifth light-shielding sheet 14; The first light-shielding plate 10 is disposed between the first lens 2 and the second lens 4; the second light-shielding plate 11 is disposed between the second lens 4 and the third lens 5; the third light-shielding plate 12 is disposed between the third lens 5 and the fourth lens 6; the fourth light-shielding plate 13 is disposed between the fourth lens 6 and the fifth lens 7; and the fifth light-shielding plate 14 is disposed between the fifth lens 7 and the sixth lens 8.

[0038] The aforementioned window mirror 1 and filter 9 are located at the mirror openings at both ends of the lens barrel 3 and are fixed with adhesive. Meanwhile, the first lens 2, the second lens 4, the third lens 5, the fourth lens 6, the fifth lens 7, and the sixth lens 8 are tightly connected to the inner wall of the lens barrel, and the overall structure is stable.

[0039] The first lens 2, the second lens 4, the third lens 5, the fourth lens 6, the fifth lens 7, and the sixth lens 8 mentioned above are made of plastic material, which has the advantages of being lightweight and not easily broken.

[0040] The aforementioned window mirror 1, first lens 2, first light shield 10, second lens 4, second light shield 11, third lens 5, third light shield 12, fourth lens 6, fourth light shield 13, fifth lens 7, fifth light shield 14, sixth lens 8, and filter 9 are arranged coaxially to prevent them from obstructing each other and affecting the image quality.

[0041] The parameters of each lens element in the lens are shown in Table 1 below.

[0042] Table 1 Design Values ​​for Medical Endoscopes

[0043] The surface numbers are assigned according to the surface sequence of each lens. "S1" represents the object-side surface (object-side face) of the first lens 2, "S2" represents the image-side surface (image-side face) of the first lens 2, and so on: S3 and S4 are the object-side and image-side faces of the second lens, respectively; S5 and S6 are the object-side and image-side faces of the third lens, respectively; S7 and S8 are the object-side and image-side faces of the fourth lens, respectively; S9 and S10 are the object-side and image-side faces of the fifth lens, respectively; and S11 and S12 are the object-side and image-side faces of the sixth lens, respectively. "S01" represents the object-side surface of the window mirror 1. "S02" represents the image-side surface of window mirror 1, "S03" represents the object-side surface of the filter, and "S04" represents the image-side surface of the filter; the radius of curvature represents the curvature of the lens surface, where "Infinity" indicates that the surface is flat and the radius of curvature is infinite; the thickness represents the central axial distance between the current surface and the next surface; the refractive index represents the ability of the material between the current surface and the next surface to deflect light, and a space indicates that the current position is air with a refractive index of 1; the Abbe number represents the dispersion characteristics of the material between the current surface and the next surface, and a space indicates that the current position is air.

[0044] Table 2 Design values ​​of aspherical conic coefficient for medical endoscopes

[0045]

[0046] "-9.095724e-02" means -9.095724×10 -2 All other coefficients are represented in this way.

[0047] The conicity of an aspherical surface can be limited by the following aspherical formula, but is not limited to the following methods:

[0048] In the formula, Z is the distance vector from the vertex of the aspherical surface along the optical axis at a position of height Y; R is the height of the aspherical surface; c is the curvature of the fitted sphere, which is numerically the reciprocal of the radius of curvature; k is the coefficient of the fitted cone; and AG are the coefficients of the 4th, 8th, 10th, 12th, 14th, and 16th order terms of the aspherical polynomial, respectively.

[0049] For example, Table 2 details the aspherical coefficients of each lens in this embodiment 1 according to a feasible implementation.

[0050] Table 3 Parameters of each light-shielding sheet

[0051] The medical endoscope in this embodiment achieves the following technical specifications: Focal length (EFL): 0.64mm; F-number (F / No.): 5.7; Overall length (TTL): 3.39mm; Field of view (FOV FOR 1 / 9”): H-120.4°, O-95.9°, V-141.4°; Optical distortion: -43%; Working distance (FOCUSING RANGE): 3~100mm.

[0052] This novel endoscope system employs a lens design with a large depth of field, effectively capturing clear images within an object distance range of 3mm to 100mm. Through precise aperture and focal length settings, the lens ensures a wide depth of field, enabling simultaneous clear imaging of objects at varying distances. Suitable for observation and inspection in confined spaces, it provides stable and clear image quality, meeting the high-precision imaging requirements of endoscopes in minute or complex environments.

[0053] Based on the above, the advantages of this utility model are as follows: The overall design of this utility model, through the multi-layer lens and shielding design, adopts a small aperture and aspherical lens to ensure its large depth of field performance, which can ensure that the endoscope can clearly display near and far tissues without frequent focusing during medical examinations and surgeries, reducing image blurring caused by changes in distance during surgery. The overall design structure is simple and practical, small in size, has a relatively broad market prospect, and is easy to promote.

[0054] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A large depth-of-field medical endoscope, characterized in that: The system includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens arranged sequentially along an optical axis from the object side to the image side. Each of the first to sixth lenses includes an object-side surface facing the object side and through which imaging rays pass, and an image-side surface facing the image side and through which imaging rays pass. The first lens has a negative refractive index, and its object-side surface is convex, while its image-side surface is concave. The second lens has a negative refractive index, and both its object-side and image-side surfaces are concave. The third lens has a positive refractive index, and both its object-side and image-side surfaces are convex. The fourth lens has a positive refractive index, and both its object-side and image-side surfaces are convex. The fifth lens has a negative refractive index, and both its object-side and image-side surfaces are concave. The sixth lens has a positive refractive index, and both its object-side and image-side surfaces are convex. It also includes a light-shielding assembly, which includes a first light-shielding sheet, a second light-shielding sheet, a third light-shielding sheet, a fourth light-shielding sheet, and a fifth light-shielding sheet; The first light-shielding plate is located between the first lens and the second lens; the second light-shielding plate is located between the second lens and the third lens; the third light-shielding plate is located between the third lens and the fourth lens; the fourth light-shielding plate is located between the fourth lens and the fifth lens; the fifth light-shielding plate is located between the fifth lens and the sixth lens. The object-side and image-side surfaces of the first to sixth lenses are all high-order even-order aspherical surfaces.

2. The large depth-of-field medical endoscope lens according to claim 1, characterized in that: The first lens, second lens, third lens, fourth lens, fifth lens, and sixth lens are all plastic aspherical lenses.

3. The large depth-of-field medical endoscope lens according to claim 2, characterized in that: The first lens is made of EP5000 material; the third and fifth lenses are both made of EP8000 material.

4. The large depth-of-field medical endoscope lens according to claim 2, characterized in that: The second and sixth lenses are both made of APEL5514ML material; the fourth lens is made of Zeonex K26R material.

5. The large depth-of-field medical endoscope according to any one of claims 1-4, characterized in that: It includes a window mirror, a first lens, a first light-blocking plate, a second lens, a second light-blocking plate, a third lens, a third light-blocking plate, a fourth lens, a fourth light-blocking plate, a fifth lens, a fifth light-blocking plate, a sixth lens, and a filter, arranged coaxially from the object side to the image side along the optical axis.

6. The large depth-of-field medical endoscope according to any one of claims 1-4, characterized in that: The radius of curvature of the object side of the first lens is 2.1328±0.0005mm, and the radius of curvature of the image side of the first lens is 0.3549±0.0005mm. The radius of curvature of the object side of the second lens is -9.0420±0.0005mm, and the radius of curvature of the image side of the second lens is 0.7021±0.0005mm. The radius of curvature of the object side of the third lens is 0.5220±0.0005mm, and the radius of curvature of the image side of the third lens is 94.4146±0.0005mm. The radius of curvature of the object side of the fourth lens is 0.8331±0.0005mm, and the radius of curvature of the image side of the fourth lens is -0.3212±0.0005mm. The radius of curvature of the object side of the fifth lens is -0.6047±0.0005mm, and the radius of curvature of the image side of the fifth lens is 0.6700±0.0005mm. The radius of curvature of the object side of the sixth lens is 2.4281±0.0005mm, and the radius of curvature of the image side of the sixth lens is -0.7580±0.0005mm.

7. The large depth-of-field medical endoscope according to any one of claims 1-4, characterized in that: The center-to-center distance between the first and second lenses is 0.185±0.02mm; the center-to-center distance between the second and third lenses is 0.188±0.02mm; the center-to-center distance between the third and fourth lenses is 0.224±0.02mm; the center-to-center distance between the fourth and fifth lenses is 0.401±0.02mm; and the center-to-center distance between the fifth and sixth lenses is 0.288±0.02mm.

8. The large depth-of-field medical endoscope according to any one of claims 1-4, characterized in that: The center thickness of the first lens is 0.02±0.02mm; the center thickness of the second lens is 0.31±0.02mm; the center thickness of the third lens is 0.05±0.02mm; the center thickness of the fourth lens is 0.13±0.02mm; the center thickness of the fifth lens is 0.05±0.02mm; and the center thickness of the sixth lens is 0.07±0.02mm.

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