A front-end ultra-narrow diameter optical imaging module for ophthalmic fiber optic endoscope systems

Abstract

This invention relates to a front-end ultra-fine diameter optical imaging module for an ophthalmic fiber optic endoscope system. The module includes an ultra-fine diameter objective lens; the objective lens comprises a front lens group and a rear lens group; the front lens group includes a first lens element with negative optical power and a second lens element with negative optical power, both the first and second lens elements having an object-side surface and an image-side surface. The first object-side surface of the first lens element is planar, and the first image-side surface of the first lens element is concave. The second object-side surface of the second lens element is concave, and the second image-side surface of the second lens element is planar, with the concave surfaces fitted together. This front-end ultra-fine diameter optical imaging module for an ophthalmic fiber optic endoscope system effectively reduces the overall size, greatly reduces the difficulty of processing and assembly, and improves the stability of the system.

Description

Technical Field

[0001] This invention belongs to the field of ophthalmic endoscope technology, specifically relating to a front-end ultra-fine diameter optical imaging module for ophthalmic fiber optic endoscope systems. Background Technology

[0002] The human eye is an organ with a precise and complex anatomical structure. Traditional ophthalmic surgical microscopes struggle to directly observe deep, hidden areas within the eye, such as the anterior chamber angle, the posterior iris, the ciliary convexity, the pars plana of the ciliary body, and the peripheral retina. Furthermore, while existing fundus photography or scanning techniques can provide some retinal imaging, they typically cannot fully cover the entire retina due to limitations in the field of view. In contrast, ophthalmic endoscopes can not only access these difficult-to-observe areas but also provide targeted magnification and clear imaging of specific localized target areas. Therefore, as an innovative ultra-fine-diameter endoscopic technique, ophthalmic endoscopes demonstrate broad application potential in various applications within ophthalmology, including but not limited to:

[0003] 1) Assisted Vitreoretinal Surgery: Vitreoretinal surgery often involves complex cases that can lead to blindness, including proliferative diabetic retinopathy, retinal holes, vitreous hemorrhage, and macular holes. These sites are difficult to expose and have dense neurovascular networks, posing significant challenges and increasing surgical risks. For blind patients whose corneal opacity prevents clear visualization of intraocular structures using conventional methods, traditional surgical approaches are often inadequate. Ophthalmic endoscopes provide an effective means to address these issues.

[0004] 2) Assisting glaucoma surgery: In glaucoma surgery, including anterior segment corneal surgery and posterior segment iris surgery, the use of endoscopes allows doctors to accurately locate and treat the lesions in glaucoma, thereby improving the precision and safety of the surgery.

[0005] 3) Assisting in the diagnosis and treatment of choroidal diseases: Choroidal diseases include choroidal neovascularization, choroiditis, and choroidal tumors. Traditional diagnostic and treatment methods are limited, making accurate diagnosis and effective treatment difficult. Ophthalmic endoscopes can provide clear imaging, helping doctors to accurately observe and manage choroidal diseases, thus improving the effectiveness of diagnosis and treatment.

[0006] 4) Endoscopic vitrectomy for intraocular foreign bodies;

[0007] 5) Lacrimal duct obstruction surgery, etc.

[0008] The existing European patent publication EP1512366 A1, "Ophthalmic endoscope," discloses an ophthalmic endoscope technology whose core feature is an optical system capable of deflecting the beam and image within a range of 8° to 11°. This deflection capability allows the endoscope to directionally observe specific areas within the eye. While this technology meets basic visual needs, in complex ophthalmic surgeries, this fixed deflection range may be insufficient to provide a sufficiently wide field of view. This could force surgeons to frequently adjust the endoscope's position to obtain a comprehensive intraocular view, thus increasing surgical time and complexity. Furthermore, the patent document does not explicitly state whether the image transmission system supports high-resolution imaging, which is crucial in surgeries requiring high-precision vision (such as macular surgery or retinal repair). Insufficient image resolution may lead to the inability to accurately identify minute intraocular structures and lesions, thereby increasing surgical risks.

[0009] Chinese utility model patent CN204287581U discloses an objective lens for an ultra-fine optical system, proposing an ultra-fine objective lens with a diameter of less than 1.0 mm, designed to support small-incision surgeries. Although the design aims to reduce the diameter of the endoscope, the actual objective lens diameter is relatively large, making it difficult to control the endoscope's insertion end within 1.06 mm (19G), which limits the implementation of small-incision surgeries. Furthermore, the design does not consider the actual imaging media (such as the vitreous body) in ophthalmic surgery, which may lead to a reduced field of view, further limiting the field of vision. While biconvex or meniscus designs can achieve specific optical performance, they are difficult and costly to manufacture. The lack of an inter-assembly aperture may lead to increased light diffusion and stray light, thereby reducing image contrast and resolution. Simultaneously, the excessively long total radial length does not meet the requirements of flexible and precise surgeries and examinations for the volume of the endoscope's tip.

[0010] Chinese utility model patent CN204654878U discloses an ophthalmic endoscope and its fiber optic assembly, describing a design for an ophthalmic endoscope and fiber optic assembly that provides direct imaging via optical fiber. While its structure is simple, it also has shortcomings. Specifically, the technology lacks a focusing and correction mechanism for ultra-fine objectives, which may lead to reduced image resolution and contrast, and increased optical distortion and chromatic aberration. These problems limit the accuracy of imaging and the field of view, thus affecting the outcome of ophthalmic surgery.

[0011] This patent application is filed to address the problem that surgeons cannot obtain a wider intraocular field of view during ophthalmic surgery in existing technologies. Summary of the Invention

[0012] The purpose of this invention is to provide a front-end ultra-fine diameter optical imaging module for ophthalmic fiber optic endoscope systems that has a simple structure and a reasonable design in order to solve the above-mentioned problems.

[0013] The present invention achieves the above objectives through the following technical solutions:

[0014] The first aspect of the present invention provides a front-end ultra-narrow diameter optical imaging module for an ophthalmic fiber optic endoscope system, the module including an ultra-narrow diameter objective lens;

[0015] The ultra-fine diameter objective lens includes a front lens group and a rear lens group;

[0016] The front lens group includes a first lens element with negative optical power and a second lens element with negative optical power. Both the first lens element and the second lens element include an object side and an image side. The first object side of the first lens element is a plane, and the first image side of the first lens element is a concave surface. The second object side of the second lens element is a concave surface, and the second image side of the second lens element is a plane. The concave surfaces are arranged to fit together.

[0017] The rear lens group includes a third lens element with positive optical power and an independent fourth lens element. The third lens element includes a third object-side surface and a third image-side surface. The third object-side surface is a plane, and the third image-side surface is a convex surface. The fourth lens element includes a fourth lens with positive optical power and a fifth lens with negative optical power, which are fixedly connected.

[0018] The fourth lens includes a fourth object-side surface and a fourth image-side surface, the fourth object-side surface being convex and the fourth image-side surface being convex; the fifth lens includes a fifth object-side surface and a fifth image-side surface, the fifth object-side surface being concave and the fifth image-side surface being planar.

[0019] An aperture stop is also provided between the second lens element and the third lens element;

[0020] The second lens element is disposed after the first lens element, the third lens element is disposed after the second lens element, and the fourth lens element is disposed after the third lens element.

[0021] It should be noted that the ultra-narrow objective lens is responsible for collecting and focusing the light of the target image, the imaging light guide fiber bundle is responsible for transmitting the image signal, the metal cylindrical shell provides protection and support for the internal optical components, the front end refers to the end of the ultra-narrow objective lens that is close to the target eye tissue being examined, and the rear end refers to the end of the ultra-narrow objective lens that is close to the imaging light guide fiber.

[0022] Both the first lens element and the second lens element include a plano-concave negative lens. The concave surfaces of the first lens element and the second lens element are arranged opposite to each other, that is, the edge of the concave surface of the first lens element and the edge of the concave surface of the second lens element are in close contact.

[0023] Generally, using plano-concave negative lenses made of the same material allows for the use of the same processing drawings, simplifying the production process and improving manufacturing efficiency.

[0024] The third lens element includes a plano-convex positive lens, and the fourth lens element includes a cemented doublet positive lens. The cemented doublet positive lens includes a biconvex positive lens and a plano-concave negative lens, with the biconvex positive lens positioned in front of the plano-concave negative lens.

[0025] It should be noted that the plano-convex positive lens is responsible for focusing the light beam and reducing aberrations; the biconvex positive lens and the plano-concave negative lens are cemented together to form an independent cemented doublet positive lens element; the second lens element and the first lens element constitute the front-end object-side negative lens group, which is responsible for collecting more light rays from different angles; the third lens element and the fourth lens element constitute the rear-end image-side positive lens group, which is responsible for focusing the light beam, reducing aberrations, and improving the uniformity of the imaging plane.

[0026] A second aspect of the present invention provides a front-end ultra-narrow diameter optical imaging module for an ophthalmic fiber optic endoscope system. The module further includes the aforementioned ultra-narrow diameter objective lens, a new imaging light guide fiber bundle, and a housing, wherein the ultra-narrow diameter objective lens is disposed within the housing.

[0027] Furthermore, the ultra-narrow diameter objective lens is placed at the front end of the imaging optical fiber, and the two are coupled and fixed with the same stainless steel shell, which ensures the effective transmission of optical signals and reduces signal loss.

[0028] Generally, the ultra-fine objective lens is completely housed within a stainless steel cylindrical shell, protecting it from physical damage. The diameter of the stainless steel cylindrical shell is less than or equal to 0.8 mm, enabling miniaturization of the module. The end face of the imaging light guide fiber bundle that receives the light signal from the ultra-fine objective lens extends into the stainless steel cylindrical shell and is fixedly coupled to the ultra-fine objective lens. The numerical aperture of the ultra-fine objective lens in the image space matches the numerical aperture of a single fiber in the light guide fiber, and the root mean square diameter of the diffusion spot formed by the ultra-fine objective lens on the imaging plane is smaller than the imaging diameter of a single fiber. The number of cores in the imaging light guide fiber bundle is not less than 10,000 and can reach a maximum of 30,000, and the length of the imaging light guide fiber bundle is greater than 500 mm.

[0029] As a further optimization of the present invention, the ultra-narrow diameter objective lens satisfies the following relationship:

[0030] ImgH / ft > 0.9;

[0031] Wherein, ImgH represents the radius of the pixel region that can be effectively imaged on the end face of the imaging light guide fiber bundle; ft represents the effective focal length of the ultra-fine diameter objective lens.

[0032] As a further optimization of the present invention, the ultra-narrow diameter objective lens satisfies the following relationship:

[0033] CRA < 10°;

[0034] Wherein, CRA represents the maximum angle at which the ultra-narrow objective lens is incident on the principal ray of the imaging optical fiber bundle.

[0035] As a further optimization of the present invention, the ultra-narrow diameter objective lens satisfies the following relationship:

[0036] r2 = -r3;

[0037] 1 < r8 / r10 < 1.25;

[0038] Wherein, r2 represents the radius of curvature of the first image-side surface of the first lens element; r3 represents the radius of curvature of the second object-side surface of the second lens element; r8 represents the radius of curvature of the third image-side surface of the third lens element; and r10 represents the fourth image-side surface of the fourth lens.

[0039] As a further optimization of the present invention, the ultra-narrow diameter objective lens satisfies the following relationship:

[0040] 6 < TTL / ImgH < 10;

[0041] Wherein, TTL represents the axial distance from the first object side surface of the first lens element to the imaging surface of the ultra-narrow diameter objective lens, and ImgH represents the radius of the pixel area that can be effectively imaged on the end face of the imaging light guide fiber bundle.

[0042] As a further optimization of the present invention, the ultra-narrow diameter objective lens satisfies the following relationship:

[0043] 1.5 < ft / D < 3;

[0044] Where ft represents the effective focal length of the ultra-narrow objective lens, and D represents the light transmission diameter of the aperture stop.

[0045] As a further optimization of the present invention, the front lens group and the rear lens group include at least five lens groups, wherein the edge thickness of each lens group is not less than 0.12 mm and the center thickness is not less than 0.11 mm.

[0046] The front lens group and the rear lens group have the same external mechanical diameter, both less than 0.74 mm;

[0047] The distance between the second image-side surface of the second lens element and the third object-side surface of the third lens element is 0.30-0.45 mm;

[0048] The spatial distance from the first object side of the first lens element to the last image side of the fourth lens element is the objective lens length, which is 1.6-1.8 mm.

[0049] As a further optimization of the present invention, the aperture stop is made of circular Mylar sheet material with a thickness of 12μm; its central opening diameter is 0.12-0.15mm to control the propagation of light.

[0050] As a further optimization of the present invention, the working wavelength of the ultra-narrow diameter objective lens is 400-900nm.

[0051] As a further optimization of the present invention, the length from the rear end face of the fourth lens element to the receiving surface of the imaging light guide fiber bundle, i.e. the back focal length of the ultra-fine objective lens, is 0.25-0.4 mm.

[0052] It should also be noted that the objective lens has a working distance of 2.0-25.0 mm, while the axial length of the human eye is approximately 22.0-25.0 mm, allowing the objective lens to meet the imaging requirements of the internal structures of the human eye. This objective lens is suitable for various imaging media in intraocular imaging surgery. When the imaging media is vitreous humor or intraocular filling material (such as silicone oil, balanced salt solution, sodium hyaluronate, etc.), the maximum field of view of the objective lens system is not less than 100 degrees; while when the imaging media is air or gas filling material (such as sulfur hexafluoride SF6 or perfluoroethane C2F6), the maximum field of view is not less than 130 degrees, thus ensuring a wide field of view imaging effect and adaptability in different surgical environments. The cylindrical spacer placed between the ultra-fine diameter objective lens and the imaging light guide fiber bundle provides precise spacing control to match the back focal length of the objective lens and ensures correct focusing and transmission of light.

[0053] The beneficial effects of this invention are as follows: This invention adopts an ultra-fine objective lens design, which is suitable for the needs of small incisions in ophthalmic surgery, reduces the risk of postoperative leakage and infection, and promotes healing;

[0054] This invention takes into account actual imaging media, such as vitreous or other liquid fillers, to increase the imaging field of view, improve the clarity of the intraocular field of view, and acquire more image information of the target area; at the same time, the design of four independent lens elements effectively reduces the system size, reduces the difficulty of processing and assembly, and improves the system stability.

[0055] The objective lens assembly of this invention has a wide operating wavelength range, making it suitable for various ophthalmic applications and possessing great flexibility and versatility. Attached Figure Description

[0056] Figure 1 This is an overall schematic diagram of the front-end ultra-fine diameter optical imaging module of the present invention used in an ophthalmic fiber optic endoscope system;

[0057] Figure 2 This is a schematic diagram of the structure of an embodiment 1 of the front-end ultra-fine diameter optical imaging module of the present invention for an ophthalmic fiber optic endoscope system;

[0058] Figure 3 These are schematic diagrams of embodiments 2 and 3 of the present invention for the front-end ultra-fine diameter optical imaging module of an ophthalmic fiber optic endoscope system;

[0059] Figure 4 This is a schematic diagram illustrating the curved surface structure of the front-end ultra-fine diameter optical imaging module of the ophthalmic fiber optic endoscope system of the present invention.

[0060] Figure 5 This is a simplified schematic diagram of the light path for imaging with the ultra-narrow diameter objective lens of the present invention;

[0061] Figure 6 This is a point diagram illustrating the imaging quality of the ultra-narrow diameter objective lens of the present invention;

[0062] Figure 7 This is the MTF (Mean Transformer File) plot of the ultra-narrow diameter objective lens of the present invention;

[0063] Figure 8 This is a schematic diagram of the geometric structure of the front-end ultra-fine diameter optical imaging module of the ophthalmic fiber optic endoscope system of the present invention. Detailed Implementation

[0064] The present application will now be described in further detail with reference to the accompanying drawings. It should be noted that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0065] This invention provides a front-end ultra-fine aperture optical imaging module for an ophthalmic fiber optic endoscope system that is simple in structure, easy to manufacture and assemble, and has a large depth of field. The module includes an ultra-fine aperture objective lens, an imaging fiber optic bundle, and a metal cylindrical shell. The ultra-fine aperture objective lens is specifically designed to take into account the actual imaging media used in ophthalmic surgery, such as vitreous humor or other liquid fillers, thereby increasing the field of view in liquid media. This allows surgeons to obtain a clearer intraocular view during actual surgical procedures, thus improving the efficiency and reliability of minimally invasive ophthalmic surgery. This invention solves the technical problem that current ultra-fine endoscopic objective lens systems cannot simultaneously adapt to a large field of view, small aperture, and large depth of field. Furthermore, the ultra-fine aperture objective lens of this invention contains only five lenses, effectively reducing the overall size, greatly reducing the difficulty of manufacturing and assembly, and improving the stability of the system. Besides ophthalmology, this invention can also be applied to neurosurgery, general surgery, and other fields. Specific implementation examples are provided below.

[0066] Example 1

[0067] refer to Figure 1 The schematic diagram shows a front-end ultra-narrow diameter optical imaging module for an ophthalmic fiber optic endoscope system. The module actually includes an ultra-narrow diameter objective lens, which collects light signals inside a metal cylindrical shell B and sends them to the imaging light guide fiber bundle F.

[0068] For details, please refer to Figure 2 The schematic diagram shown indicates that the ultra-narrow diameter objective lens includes a front lens group G1 and a rear lens group G2.

[0069] The front lens group G1 includes a first lens element 1 with negative optical power and a second lens element 2 with negative optical power. Both the first lens element 1 and the second lens element 2 include an object side and an image side. The first object side of the first lens element 1 is a plane, and the first image side of the first lens element 1 is a concave surface. The second object side of the second lens element 2 is a concave surface, and the second image side of the second lens element 2 is a plane. The concave surfaces are arranged to fit together.

[0070] The rear lens group G2 includes a third lens element 3 with positive optical power and an independent fourth lens element 6. The third lens element 3 includes a third object side and a third image side. The third object side is a plane and the third image side is a convex surface. The fourth lens element 6 includes a fourth lens with positive optical power and a fifth lens with negative optical power, which are fixedly connected.

[0071] The fourth lens includes a fourth object-side surface and a fourth image-side surface, the fourth object-side surface being convex and the fourth image-side surface being convex; the fifth lens includes a fifth object-side surface and a fifth image-side surface, the fifth object-side surface being concave and the fifth image-side surface being planar.

[0072] An aperture stop A is also provided between the second lens element 2 and the third lens element 3;

[0073] The second lens element 2 is disposed after the first lens element 1, the third lens element 3 is disposed after the second lens element 2, and the fourth lens element 6 is disposed after the third lens element 3.

[0074] Both the first lens element 1 and the second lens element 2 include a plano-concave negative lens. The concave surface r2 of the first lens element 1 and the concave surface r3 of the second lens element 2 are arranged opposite to each other, that is, the edge of the concave surface r2 of the first lens element 1 and the edge of the concave surface r3 of the second lens element 2 are in close contact. In this embodiment, the distance between the centers of the first lens element 1 and the second lens element 2 is 0.08-0.09 mm.

[0075] The third lens element 3 includes a plano-convex positive lens, and the fourth lens element 6 includes a cemented doublet positive lens. The cemented doublet positive lens includes a biconvex positive lens 4 and a plano-concave negative lens 5, with the biconvex positive lens 4 disposed in front of the plano-concave negative lens 5.

[0076] It should be noted that the plano-concave negative lens of the first lens element 1 can be referred to as the first lens in the following text. Similarly, the plano-concave negative lens of the second lens element is referred to as the second lens. The third lens element 3 corresponds to the third lens, and the fourth lens element 6 corresponds to the fourth and fifth lenses. This part only refers to the names for the convenience of subsequent overall description.

[0077] It should be noted that, in this specification, "front end" or "front" refers to the end of the ultra-narrow diameter optical imaging module and the ultra-narrow diameter objective lens that is close to the target eye tissue being examined, and "rear end" or "rear" refers to the end of the ultra-narrow diameter objective lens that is close to the imaging light guide fiber bundle F.

[0078] The distance between the second image-side surface r4 of the second lens element 2 and the third object-side surface r7 of the third lens element 3 is 0.41-0.42 mm, and the optical axis spatial distance from the first object-side surface r1 of the first lens element 1 to the fifth image-side surface r11 of the fourth lens element 6, i.e. the objective lens length, is 1.725 mm.

[0079] In this embodiment, the aperture stop A is made of circular Mylar sheet material with a thickness of 12 μm and an outer diameter of 0.74 mm. A circular opening with a diameter of 0.14 mm is made at the center of the circular extinction Mylar sheet, serving as the aperture stop A to control the propagation of light. The aperture stop A is positioned between the second lens element 2 and the third lens element 3, closer to the third lens element 3.

[0080] The first lens element 1, the second lens element 2, the third lens element 3 and the fourth lens element 6 have the same external mechanical diameter, which is 0.74 mm.

[0081] The optical structural parameters of the ultra-fine diameter endoscope objective in this embodiment are as follows:

[0082] Lens surface Radius of curvature (r) Thickness (d) Refractive index (Nd) Abbe constant (Vd) r1 Infinity 0.11 1.95 32.3 r2 0.92 0.081 - - r3b -0.92 0.11 1.95 32.3 r4b Infinity 0.25 - - r5 (side view of the orifice) Infinity 0.012 - - r6 (Side view of the lumbar suture) Infinity 0.17 - - r7 Infinity 0.32 1.77 40.3 r8 -0.49 0.082 - - r9 0.84 0.44 1.74 52.0 r10 -0.44 0.15 1.97 18.0 r11 Infinity 0.365 - - Image Infinity - - -

[0083] Using the above structural parameters, the system has a numerical aperture (NA) of 0.109 and an image-space F-number of 3.81, demonstrating strong light-gathering capabilities. (See details...) Figure 4(a) briefly illustrates the light path of the objective lens imaging. When the imaging medium is vitreous or other liquid-filled material, the maximum field of view of the objective lens is 120 degrees; while when the imaging medium is air or a gas-filled material (such as sulfur hexafluoride SF6 or perfluoroethane C2F6), the maximum field of view of the objective lens system can reach 150 degrees. On the r1, r2, r3, r4, r7, r8, r9, and r11 curved surfaces of the ultra-fine diameter objective lens, an anti-reflection coating with a wavelength range of 400-900 nm is coated, supporting imaging from the visible to near-infrared bands and enhancing the light signal intensity of image plane I while reducing stray light. Furthermore, the module's working distance range is 2.0-25.0 mm, covering a full range of real-world ophthalmic scenarios, allowing for precise magnification of minute details at extremely close distances and observation of different intraocular structures at greater distances. This enables the endoscope to effectively image at different depths and positions, thereby improving the flexibility and accuracy of diagnosis.

[0084] This design uses lens radius curvature (r) and thickness (d) with two significant figures, compared to other designs that use three significant figures, which reduces manufacturing and measurement complexity. This reduces manufacturing costs, and the accuracy is sufficient for many practical applications, thus improving efficiency. Furthermore, the lens structure primarily uses a plano-concave or plano-convex form, which offers the following advantages compared to the complex meniscus structure used by others: 1) Lower manufacturing costs: Plano-concave or plano-convex structures are generally easier to manufacture, reducing costs, especially in mass production; 2) Higher stability and durability: These structures are generally more stable and durable, suitable for random and unstable environments; 3) Easier optical performance optimization: Compared to complex structures, plano-concave or plano-convex lenses are easier to optimize for optical performance, simplifying the design process while reducing optical interference and improving image quality; 4) Easier integration and assembly: Due to their simple structure, these lenses are easier to integrate with other optical components, simplifying the assembly process and accelerating product development cycles. This makes it a competitive choice for this application.

[0085] In order to control the optical lens spacing of the ultra-narrow diameter objective and the spatial position of the aperture stop A to ensure that the objective correctly refracts and collects light, the following method is adopted: a cylindrical spacer S1 is placed between the aperture stop A and the second lens; a cylindrical spacer S2 is placed between the aperture stop A and the third lens; and a cylindrical spacer S3 is placed between the third lens and the fourth lens.

[0086] In a specific embodiment, the ultra-narrow diameter objective lens, from left to right, consists of the first lens element 1, the second lens element 2, the cylindrical spacer S1, the aperture stop A, the cylindrical spacer S2, the third lens element 3, the cylindrical spacer S3, and the fourth lens element 6. In this embodiment, the total outer diameter of the fiber bundle F is 0.75mm ± 0.03mm, the effective image transmission surface diameter is 0.60 ± 0.03mm, the single fiber core spacing and the system imaging pixel size are 3.3μm, and the number of fiber cores, i.e., the number of pixels, is 30,000. Furthermore, to form the front-end ultra-narrow diameter optical imaging module, the ultra-narrow diameter objective lens and the imaging light guide fiber bundle F are coupled and fixed within the annular metal housing B. The length from the rear end face of the objective lens, i.e., the fifth image side surface r11 of the fourth lens element 6, to the receiving surface of the imaging light guide fiber bundle (i.e., the back focal length of the objective lens) is 0.365mm. A cylindrical spacer S4 is placed between the ultra-narrow diameter objective lens and the fiber bundle F to accommodate the back focal length of the objective lens.

[0087] In this embodiment, as Figure 6 As shown in (a), a point plot of the objective lens at different field points is presented. Specifically, Figure 6 In (a), the object planes 0.00 (degrees), 18.00 (degrees), 30.00 (degrees), 42.00 (degrees), 48.00 (degrees), and 60.00 (degrees) represent the center, 18°, 30°, 42°, 48°, and maximum field of view of 60°, respectively. Calculations show that at these field points, the root mean square diameters of the blur spot are 0.796 μm, 1.412 μm, 2.104 μm, 1.906 μm, 1.434 μm, and 1.814 μm, respectively. These values ​​are all less than 3.3 μm, which is less than the core diameter of a single fiber in the imaging fiber bundle F. This indicates that the light spot generated by the imaging system falls entirely within the fiber core, ensuring that the fiber can effectively capture and transmit all light rays.

[0088] Furthermore, in this embodiment, the half-image height of the ultra-fine objective lens reaches 0.3 mm, completely covering the effective image transmission surface of the fiber bundle and avoiding the loss of light energy information. Simultaneously, the numerical aperture of the image space of the objective lens (NA = 0.109) is smaller than the numerical aperture of a single fiber in the imaging light guide fiber F (NA = 0.41), fully demonstrating that the receiving capability of the fiber exceeds the output capability of the objective lens. This allows for the comprehensive capture of all light rays output by the objective lens, achieving efficient light energy transmission and effectively avoiding crosstalk between pixels, thus optimizing image quality. These characteristics make the ultra-fine objective lens of this embodiment an ideal choice for high-precision ophthalmic endoscopic imaging requirements.

[0089] at the same time, Figure 7(a) shows the MTF (Modulation Transfer Function) curve of the objective lens in this embodiment at the maximum field of view, i.e., 60 degrees at the edge. Based on the core diameter of a single optical fiber of 3.3 μm, the image resolution of the image bundle reaches [value missing].

[0090]

[0091] As shown in the figure, at a field of view of 60 degrees, the corresponding values ​​of the meridional (T) MTF curve and the sagittal (S) MTF curve at an abscissa of 175 lp / mm are both greater than 0.32. This means that at the edge of the field of view, this objective lens group can provide high resolution and good aberration correction, ensuring excellent imaging performance close to the diffraction limit. These characteristics make the ultra-narrow diameter objective lens of this embodiment an ideal choice for high-precision ophthalmic endoscopic imaging needs.

[0092] refer to Figure 8 The schematic diagram shown below lists the geometric dimensions of the outer casing B, Mylar sheet A, and gaskets S1-S4:

[0093]

[0094] This embodiment, through its ingeniously designed ultra-narrow diameter optical imaging module, not only achieves a 30,000-pixel imaging module with an external mechanical diameter of only 0.8 mm in an ophthalmic fiber optic endoscope system, but also provides high-precision, high-resolution imaging with a wide field of view for various imaging media that may be encountered in ophthalmic surgery, such as vitreous humor or gas-filled materials. This design integrates four independent lens elements and sophisticated optical control components, ensuring excellent imaging performance close to the diffraction limit within a maximum field of view of 120 to 150 degrees. This significantly improves diagnostic flexibility and accuracy, while simplifying the manufacturing process and reducing costs. It provides strong technical support for minimally invasive ophthalmic surgery and examinations, meeting the demands for high-precision ophthalmic endoscopic imaging.

[0095] It should be pointed out separately that, Figures 4 to 7 In this example, (a) represents the data in this embodiment, (b) represents the data in embodiment 2, and (c) represents the data in embodiment 3.

[0096] Generally, the first lens and the second lens are made of high-refractive-index glass material H-ZLAF89L.

[0097] Example 2

[0098] In this embodiment, it should be noted that, unless otherwise specified, all components and their characteristics that have not been redescribed maintain the same configuration and function as in Embodiment 1. Embodiment 2 mainly illustrates several key changes compared to Embodiment 1.

[0099] Compared to Example 1, Example 2 has the following changes:

[0100] like Figure 3 The structure shown in the upper-middle view of this embodiment, the ultra-narrow diameter objective lens, is composed of, from left to right, a first lens element 1a, a second lens element 2a, a cylindrical spacer S1a, an aperture stop A1, a cylindrical spacer S2a, a third lens element 3a, and a fourth lens element 6a; compared to Embodiment 1, as... Figure 3 and Figure 4 As shown in (b), the distance between the third lens element 3a and the fourth lens element 6a is 0, that is, the surface r8a of the third lens element 3a and the third image side surface r8a of the fourth lens element 6a are in direct contact at the center, providing mutual support without the need for a cylindrical spacer. In this way, no additional spacer is needed between the third lens element 3a and the fourth lens element 6a, which simplifies the objective lens structure system and reduces the difficulty of processing, assembling and testing the front-end ultra-fine diameter optical imaging module.

[0101] In this embodiment, the distance between the second image-side surface r4a of the second lens element 2a and the third object-side surface r7a of the third lens element 3a is 0.41-0.42 mm. The optical axis spatial distance from the first object-side surface r1a of the first lens element 1a to the fifth image-side surface r11a of the fourth lens element 6a, i.e., the total length of the objective lens, is 1.613 mm. The aperture stop A1 is positioned precisely between the second lens element 2a and the third lens element 3a.

[0102] The optical structural parameters of the ultra-fine diameter endoscope objective in this embodiment are as follows:

[0103] Using the above structural parameters, the system's numerical aperture is 0.132, and the image-space F-number is 3.73. When imaging...

[0104] Lens surface Radius of curvature (r) Thickness (d) Refractive index (Nd) Abbe constant (Vd) r1a Infinity 0.11 1.95 32.3 r2a 0.92 0.081 - - r3b -0.92 0.11 1.95 32.3 r4b Infinity 0.20 - - r5a (side view of the orifice) Infinity 0.012 - - r6a (side view of the lumbar suture) Infinity 0.20 - - r7a Infinity 0.32 1.77 40.3 r8a -0.49 0 - - r9a 0.78 0.39 1.74 52.0 r10a -0.47 0.19 1.97 18.0 r11a Infinity 0.40 - - Image Infinity - - -

[0105] When the medium is glass or other liquid filling material, the maximum field of view of the objective lens is 120 degrees; when the imaging medium is air or gas filling material (such as sulfur hexafluoride SF6 or perfluoroethane C2F6), the maximum field of view of the objective lens system can reach 150 degrees. In addition, the module working distance is 2.0-25.0 mm.

[0106] In this embodiment, the imaging light guide fiber bundle F1 used is the same as the imaging light guide fiber bundle F in Embodiment 1. To construct the front-end ultra-narrow diameter optical imaging module, the ultra-narrow diameter objective lens and the imaging light guide fiber bundle F1 are coupled and fixed within the annular metal housing B1. The length from the rear end face of the objective lens, i.e., the rear end face r11a of the fourth lens element 6a, to the receiving surface of the imaging light guide fiber bundle F1, i.e., the back focal length of the objective lens, is 0.40 mm. A cylindrical spacer S4a is placed between the objective lens and the fiber bundle F1 to accommodate the back focal length of the objective lens.

[0107] like Figure 6 As shown in (b), a point plot of the objective lens at different field points in this embodiment is illustrated. Figure 6 As shown in (b), the object planes 0.00 (degrees), 18.00 (degrees), 30.00 (degrees), 42.00 (degrees), 48.00 (degrees), and 60.00 (degrees) represent the center of the object-side field of view, 18 degrees, 30 degrees, 42 degrees, 48 ​​degrees, and the maximum field of view of 60 degrees, respectively. Calculations show that at each field of view point, the root mean square diameter of the speckle is 2.618 μm, 1.712 μm, 1.908 μm, 1.972 μm, 1.672 μm, and 2.516 μm, respectively. These values ​​are all less than 3.3 μm, which is less than the core diameter of a single fiber in the imaging fiber bundle F1.

[0108] Furthermore, in this embodiment, the half-image height of the objective lens reaches 0.3 mm, completely covering the effective image transmission surface of the fiber bundle and avoiding the loss of optical energy information. At the same time, the image space numerical aperture (NA = 0.132) of the objective lens is smaller than the numerical aperture (NA = 0.41) of a single fiber in the imaging light guide fiber F1.

[0109] Figure 7 (b) shows the MTF (Modulation Transfer Function) curves of the objective lens in this embodiment at the maximum field of view, i.e., 60 degrees at the edge. As can be seen from the figure, at a field of view of 60 degrees, the corresponding values ​​of the meridional (T) MTF curve and the sagittal (S) MTF curve at an abscissa of 175 lp / mm are both greater than 0.35.

[0110] The table lists the geometric dimensions of the outer casing B1, the Mylar sheet A1, and the gaskets S1a, S2a, and S4a.

[0111]

[0112] In summary, this embodiment simplifies the objective lens design, reduces manufacturing costs and assembly difficulty by adjusting the lens element structure, and provides a feasible solution with an external mechanical diameter of only 0.8mm, suitable for 30,000-pixel ultra-fine imaging modules.

[0113] Example 3

[0114] In Embodiment 3, unless otherwise specified, all components and their characteristics that are not redescribed maintain the same configuration and function as in Embodiment 2. Embodiment 3 primarily demonstrates several key changes compared to Embodiments 1 and 2.

[0115] Compared to Example 2, the module in Example 3 has a smaller external mechanical diameter of only 0.56mm, making it suitable for a 10,000-pixel fiber bundle F2. For example... Figure 3 As shown in the lower part of the structure, the ultra-narrow diameter objective lens in this embodiment is composed of, from left to right, a first lens element 1b, a second lens element 2b, a cylindrical spacer S1b, an aperture stop A2, a cylindrical spacer S2b, a third lens element 3b, and a fourth lens element 6b. Compared to Embodiment 2, as... Figure 3 and Figure 4 As shown in (c), the distance between the third lens element 3b and the fourth lens element 6b is 0, that is, the third image side r8b of the third lens element 3b and the fourth object side r9b of the fourth lens element 4b are in direct contact at the center, providing mutual support, and there is no need for a cylindrical spacer.

[0116] Specifically, the concave surface r2b of the first lens element 1b and the concave surface r3b of the second lens element 2b are closely fitted at their edges, and the distance between the centers of the first lens element 1b and the second lens element 2b is 0.05-0.06mm;

[0117] In this embodiment, the distance between the second image-side surface r4b of the second lens element 2b and the third object-side surface r7b of the third lens element 3b is 0.31-0.32 mm. The optical axis spatial distance from the first object-side surface r1b of the first lens element 1b to the fifth image-side surface r11 of the fourth lens element 6b, i.e., the total length of the objective lens, is 1.395 mm.

[0118] In this embodiment, the aperture stop A2 is made of circular Mylar film material with a thickness of 12 μm and an outer diameter of 0.50 mm. A circular opening with a diameter of 0.12 mm is formed at the center of the circular matte Mylar film, serving as the aperture stop A2, and is positioned precisely between the second lens element 2b and the third lens element 3b. The outer mechanical diameters of the first lens element 1, the second lens element 2, the third lens element 3, and the fourth lens element 6 are the same, numerically 0.50 mm.

[0119] The optical structural parameters of the ultra-fine diameter endoscope objective in this embodiment are as follows:

[0120]

[0121] Using the above structural parameters, the system numerical aperture is 0.164 and the image-space F number is 3.0.

[0122] When the imaging medium is glass or other liquid-filled material, the maximum field of view of the objective lens is 100 degrees; when the imaging medium is air or gas-filled material (such as sulfur hexafluoride (SF6) or perfluoroethane (C2F6)), the maximum field of view of the objective lens system can reach 130 degrees. Furthermore, the module working distance is 2.0-25.0 mm.

[0123] In this embodiment, the total outer diameter of the fiber bundle F2 is 0.44±0.03mm, the effective image transmission surface diameter is 0.325±0.02mm, the single fiber core spacing and the system imaging pixel size are 3.3μm, and the number of fiber cores, i.e. the number of pixels, is 10000.

[0124] In this configuration, the ultra-narrow diameter objective lens and the imaging light-guiding fiber bundle F2 are precisely coupled and fixed inside the annular metal housing 2B. The length from the rear end face of the objective lens (i.e., the fifth image-side surface r11 of the fourth lens element 6b) to the receiving surface I2 of the imaging light-guiding fiber bundle, which is the objective lens's back focal length, is 0.25 mm. The imaging light-guiding fiber bundle F2 extends into the cylindrical spacer S4b, with a 0.25 mm space at the front end to accommodate the objective lens's back focal length and ensure tight coupling between the fiber bundle and the annular metal housing 2B.

[0125] Figure 6 (c) shows a dot plot of the objective lens at different field-of-view points in this embodiment. As shown in 6(c), the object planes 0.00 (degrees), 18.00 (degrees), 30.00 (degrees), 42.00 (degrees), 48.00 (degrees), and 60.00 (degrees) represent the center of the object-side field of view, 18 degrees, 30 degrees, 42 degrees, 48 ​​degrees, and the maximum field of view of 60 degrees, respectively. Calculations show that at each field-of-view point, the root mean square diameter of the speckle is 1.418 μm, 1.066 μm, 1.420 μm, 1.478 μm, 1.360 μm, and 1.442 μm, respectively. These values ​​are all less than 3.3 μm, which is less than the core diameter of a single fiber in the imaging fiber bundle F2.

[0126] In addition, by Figure 6 (c) It can be seen that the half-image height of the objective lens is 0.162 mm, which can fill the effective image transmission surface of the fiber bundle without losing light energy information; the image space numerical aperture (NA = 0.164) of the objective lens matches the numerical aperture (NA = 0.41) of a single fiber in the imaging light guide fiber F, thereby ensuring high-quality image transmission, avoiding crosstalk between pixels, and achieving clear imaging.

[0127] Figure 6(c) shows the MTF (Modulation Transfer Function) curves of the objective lens in this embodiment at the maximum field of view, i.e., 60 degrees at the edge. As can be seen from the figure, at a field of view of 60 degrees, the corresponding values ​​of the meridional (T) MTF curve and the sagittal (S) MTF curve at an abscissa of 175 lp / mm are both greater than 0.52, ensuring excellent imaging performance close to the diffraction limit.

[0128] The table below lists the geometric dimensions of the outer casing B2, Mylar sheet A2, and gaskets S1b, S2b, and S4b:

[0129]

[0130] In summary, this embodiment achieves a more compact design and direct contact support by further reducing the module's outer diameter and optimizing the lens structure. Compared to Embodiments 1 and 2, the number of imaging pixels in the ophthalmic fiber optic endoscope imaging module of this embodiment is reduced from 30,000 to 10,000, but the module's outer diameter is reduced from 0.8 mm to 0.56 mm, bringing significant advantages to ophthalmic endoscopic surgery and examinations.

[0131] First, the thinner module allows for smaller incisions and more minimally invasive surgical procedures, reducing patient recovery time and the risk of postoperative complications. Second, the smaller outer diameter increases the module's flexibility and maneuverability, enabling access to narrower or more tortuous intraocular areas and enhancing accessibility for examination and treatment. Furthermore, the thinner module causes less disturbance to surrounding tissues during intraocular movement, contributing to improved surgical precision and safety.

[0132] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0133] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0134] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms should not be construed as necessarily referring to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0135] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A front-end ultra-fine diameter optical imaging module for an ophthalmic fiber optic endoscope system, characterized in that, This module includes ultra-fine diameter objectives; The ultra-fine diameter objective lens includes a front lens group and a rear lens group; The front lens group includes a first lens element with negative optical power and a second lens element with negative optical power. Both the first lens element and the second lens element include an object side and an image side. The first object side of the first lens element is a plane, and the first image side of the first lens element is a concave surface. The second object side of the second lens element is a concave surface, and the second image side of the second lens element is a plane. The concave surfaces are arranged to fit together. The rear lens group includes a third lens element with positive optical power and an independent fourth lens element. The third lens element includes a third object-side surface and a third image-side surface. The third object-side surface is a plane, and the third image-side surface is a convex surface. The fourth lens element includes a fourth lens with positive optical power and a fifth lens with negative optical power, which are fixedly connected. The fourth lens includes a fourth object-side surface and a fourth image-side surface, the fourth object-side surface being convex and the fourth image-side surface being convex; the fifth lens includes a fifth object-side surface and a fifth image-side surface, the fifth object-side surface being concave and the fifth image-side surface being planar. An aperture stop is also provided between the second lens element and the third lens element; The second lens element is disposed after the first lens element, the third lens element is disposed after the second lens element, and the fourth lens element is disposed after the third lens element.

2. The front-end ultra-fine diameter optical imaging module for an ophthalmic fiber optic endoscope system according to claim 1, characterized in that: Both the first lens element and the second lens element include a plano-concave negative lens. The concave surfaces of the first lens element and the second lens element are arranged opposite to each other, that is, the edge of the concave surface of the first lens element and the edge of the concave surface of the second lens element are in close contact. The third lens element includes a plano-convex positive lens, and the fourth lens element includes a cemented doublet positive lens. The cemented doublet positive lens includes a biconvex positive lens and a plano-concave negative lens, with the biconvex positive lens positioned in front of the plano-concave negative lens.

3. A front-end ultra-fine diameter optical imaging module for an ophthalmic fiber optic endoscope system, characterized in that, The module also includes the front-end ultra-narrow diameter optical imaging module as described in any one of claims 1-2, and the module also includes an imaging light guide fiber bundle and a housing, wherein the ultra-narrow diameter objective lens is disposed within the housing. As a further optimization of the present invention, the ultra-narrow diameter objective lens satisfies the following relationship: ImgH / ft > 0.9; Wherein, ImgH represents the radius of the pixel region that can be effectively imaged on the end face of the imaging light guide fiber bundle; ft represents the effective focal length of the ultra-fine diameter objective lens.

4. The front-end ultra-fine diameter optical imaging module for an ophthalmic fiber optic endoscope system according to claim 3, characterized in that: The ultra-fine diameter objective lens satisfies the following relationship: CRA < 10°; Wherein, CRA represents the maximum angle at which the ultra-narrow objective lens is incident on the principal ray of the imaging optical fiber bundle.

5. The front-end ultra-narrow diameter optical imaging module for an ophthalmic fiber optic endoscope system according to claim 3, characterized in that: The ultra-fine diameter objective lens satisfies the following relationship: r2＝-r3； 1﹤r8 / r10﹤1.25； Wherein, r2 represents the radius of curvature of the first image-side surface of the first lens element; r3 represents the radius of curvature of the second object-side surface of the second lens element; r8 represents the radius of curvature of the third image-side surface of the third lens element; and r10 represents the fourth image-side surface of the fourth lens.

6. The front-end ultra-fine diameter optical imaging module for an ophthalmic fiber optic endoscope system according to claim 3, characterized in that: The ultra-fine diameter objective lens satisfies the following relationship: 6 < TTL / ImgH < 10; Wherein, TTL represents the axial distance from the first object side surface of the first lens element to the imaging surface of the ultra-narrow diameter objective lens, and ImgH represents the radius of the pixel area that can be effectively imaged on the end face of the imaging light guide fiber bundle.

7. The front-end ultra-fine diameter optical imaging module for an ophthalmic fiber optic endoscope system according to claim 3, characterized in that: The ultra-fine diameter objective lens satisfies the following relationship: 1.5 < ft / D < 3; Where ft represents the effective focal length of the ultra-narrow objective lens, and D represents the light transmission diameter of the aperture stop.

8. The front-end ultra-fine diameter optical imaging module for an ophthalmic fiber optic endoscope system according to claim 3, characterized in that: The front lens group and the rear lens group include at least five lens groups, and the edge thickness of each lens group is not less than 0.12 mm and the center thickness is not less than 0.11 mm. The front lens group and the rear lens group have the same external mechanical diameter, both less than 0.74 mm; The distance between the second image-side surface of the second lens element and the third object-side surface of the third lens element is 0.30-0.45 mm; The spatial distance from the first object side of the first lens element to the last image side of the fourth lens element is the objective lens length, which is 1.6-1.8 mm.

9. The front-end ultra-fine diameter optical imaging module for an ophthalmic fiber optic endoscope system according to claim 3, characterized in that: The aperture stop is made of circular Mylar sheet material with a thickness of 12μm; Its central opening diameter is 0.12-0.15 mm.

10. The front-end ultra-narrow diameter optical imaging module for an ophthalmic fiber optic endoscope system according to claim 3, characterized in that: The length from the rear end face of the fourth lens element to the receiving surface of the imaging light guide fiber bundle, i.e. the back focal length of the ultra-fine objective lens, is 0.25-0.4 mm.

Images