Front-end superfine-diameter optical imaging module for ophthalmology optical fiber endoscope system

Abstract

The invention relates to a front-end superfine-diameter optical imaging module for an ophthalmic fiber-optic endoscope system. The front-end superfine-diameter optical imaging module for the ophthalmology optical fiber endoscope system comprises a superfine-diameter objective lens; the superfine-diameter objective lens comprises a front lens group and a rear lens group; the front lens group comprises a first lens element with negative focal power and a second lens element with negative focal power, each of the first lens element and the second lens element comprises an object side surface and an image side surface, the first object side surface of the first lens element is a plane, the first image side surface of the first lens element is a concave surface, and the second object side surface of the second lens element is a convex surface. The second object side surface of the second lens element is a concave surface, the second image side surface of the second lens element is a plane, and the concave surfaces are oppositely attached; according to the front-end superfine-diameter optical imaging module for the ophthalmic optical fiber endoscope system, the overall boundary dimension is effectively reduced, the machining and assembling difficulty is greatly reduced, and the stability of the system is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of ophthalmic endoscopes, and in particular relates to a front-end ultra-fine-diameter optical imaging module for an ophthalmic fiber optic endoscope system. Background Art

[0002] The human eye is an organ with a sophisticated and complex anatomical structure. It is difficult to directly observe deep hidden areas in the eye, such as the anterior chamber angle, the back of the iris, the ciliary convexity, the pars plana of the ciliary body, and the peripheral retina, using traditional ophthalmic surgical microscopes. In addition, although existing fundus photography or scanning technologies can provide a certain degree of retinal imaging, they are usually unable to fully cover the entire area of ​​the retina due to the limitations of the field of view. In contrast, ophthalmic endoscopes can not only access these difficult-to-observe areas, but also achieve targeted magnification and clear imaging of specific local target areas. Therefore, as an innovative ultra-fine endoscope technology, ophthalmic endoscopes show broad application potential in a variety of applications in the field of ophthalmology, such as exploration, positioning, inspection, and treatment, including but not limited to:

[0003] 1) Assisted vitreoretinal surgery: Vitreoretinal surgery usually involves complex cases that may lead to blindness, including proliferative diabetic retinopathy, retinal holes, vitreous hemorrhage, and macular holes. These areas are difficult to expose and have dense nerves and blood vessels, which poses great challenges to surgical operations and increases surgical risks. Traditional surgical methods are often unable to solve the problem of blind patients who cannot clearly observe the intraocular structure through conventional means due to corneal opacity. Ophthalmic endoscopes provide an effective means to solve these problems;

[0004] 2) Assisted 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 glaucoma lesions, thereby improving the accuracy and safety of the surgery;

[0005] 3) Assist 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 it difficult to accurately diagnose and effectively treat. Ophthalmic endoscopes can provide clear images, helping doctors to accurately observe and treat choroidal diseases and improve the effectiveness of diagnosis and treatment;

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

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

[0008] The existing European patent publication number EP1512366 A1, “Ophthalmic endoscope”, discloses an ophthalmic endoscope technology, whose core feature is the ability of the optical system to deflect light beams and images within a range of 8° to 11°. This deflection capability allows the endoscope to observe specific areas within the eye in a targeted manner. Although this technology meets basic visual needs, in complex ophthalmic surgeries, this fixed deflection range may not be sufficient to provide a sufficiently wide field of view, which may force the surgeon to frequently adjust the position of the endoscope to obtain a comprehensive intraocular view, thereby increasing the time and complexity of the operation. In addition, the patent document does not clarify whether the image transmission system supports high-resolution imaging, which is essential in surgeries that require high-precision vision (such as macular surgery or retinal repair). Insufficient image resolution may result in the inability to accurately identify tiny structures and lesions within the eye, thereby increasing surgical risks.

[0009] Chinese utility model patent CN204287581U discloses an objective lens of an ultra-fine optical system, which proposes an ultra-fine objective lens with a diameter of less than 1.0 mm, which is intended to support small incision surgery. Although the design goal is to reduce the diameter of the endoscope, the actual diameter of the objective lens is large, and it is difficult to control the insertion end of the endoscope within 1.06 mm (19G), which limits the implementation of small incision surgery. In addition, the design does not take into account the actual imaging medium (such as vitreous body) in ophthalmic surgery, which may lead to a reduction in the field of view angle and further limit the field of view. The objective lens adopts a biconvex or meniscus design. Although it can achieve specific optical properties, it is difficult to process and has high cost. The lack of an aperture between the lens groups may lead to increased light diffusion and stray light, thereby reducing image contrast and resolution. At the same time, the total radial length is too long, which does not meet the requirements of the front end volume of the endoscope for surgeries and inspections that require high flexibility and precision.

[0010] Chinese utility model patent CN204654878U discloses an ocular endoscope and its fiber optic assembly, which describes an ocular endoscope and fiber optic assembly design for direct imaging through optical fiber. Although its structure is simple, it also has shortcomings. Specifically, the technology lacks the focusing and correction mechanism of the ultra-fine objective lens, which may lead to reduced image resolution and contrast, and increased optical distortion and chromatic aberration. These problems limit the accuracy and field of view of imaging, thereby affecting the effect of ophthalmic surgery.

[0011] In order to solve the problem in the prior art that doctors cannot obtain more intraocular vision during ophthalmic surgery, this patent application is hereby proposed. Summary of the invention

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

[0013] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0014] A first aspect of the present invention provides a front-end ultra-fine diameter optical imaging module for an ophthalmic fiberoptic endoscope system, the module comprising an ultra-fine diameter objective lens;

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

[0016] The front lens group includes a first lens element with negative power and a second lens element with negative power, and the first lens element and the second lens element both include an object side surface and an image side surface, the first object side surface of the first lens element is a plane, the first image side surface of the first lens element is a concave surface, the second object side surface of the second lens element is a concave surface, the second image side surface of the second lens element is a plane, and the concave surfaces are relatively attached to each other;

[0017] The rear lens group includes a third lens element with positive 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 power and a fifth lens with negative power, and the two are fixedly connected;

[0018] The fourth lens comprises a fourth object-side surface and a fourth image-side surface, the fourth object-side surface is a convex surface, and the fourth image-side surface is a convex surface; the fifth lens comprises a fifth object-side surface and a fifth image-side surface, the fifth object-side surface is a concave surface, and the fifth image-side surface is a plane;

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

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

[0021] It should be noted that the ultra-fine objective lens is responsible for collecting and focusing the light of the target image, the imaging light-guiding 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-fine objective lens close to the target eye tissue to be explored, and the rear end refers to the end of the ultra-fine objective lens close to the imaging light-guiding fiber.

[0022] The first lens element and the second lens element both comprise plano-concave negative lenses, the concave surface of the first lens element is arranged opposite to the concave surface of the second lens element, that is, the edge of the concave surface of the first lens element is closely matched with the edge of the concave surface of the second lens element;

[0023] Generally, plano-concave negative lenses made of the same material are used. Such designs use the same processing drawings, which simplifies the production process and improves manufacturing efficiency;

[0024] The third lens element comprises a plano-convex positive lens, and the fourth lens element comprises a double cemented positive lens, wherein the double cemented positive lens comprises a biconvex positive lens and a plano-concave negative lens, and the biconvex positive lens is arranged before 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 double convex positive lens and the plano-concave negative lens are glued together to form a double-glued positive lens independent element; the second lens element and the first lens element constitute a front object side negative lens group, which is responsible for collecting more light at different angles; the third lens element and the fourth lens element constitute a rear image side positive lens group, which is responsible for focusing the light beam, reducing aberrations and improving the uniformity of the imaging plane.

[0026] The second aspect of the present invention provides a front-end ultra-fine diameter optical imaging module for an ophthalmic fiber optic endoscope system, which also includes the above-mentioned ultra-fine diameter objective lens part, a new imaging light-guiding fiber bundle, and a shell, and the ultra-fine diameter objective lens is arranged in the shell.

[0027] Furthermore, the ultra-fine objective lens is placed at the front end of the imaging light-guiding optical fiber, and the two are coupled and fixed with the same stainless steel housing, thereby ensuring the effective transmission of the optical signal and reducing the signal loss;

[0028] Generally, the ultrafine objective lens is completely contained in a stainless steel cylindrical shell to protect the objective lens from physical damage; the diameter of the stainless steel cylindrical shell is less than or equal to 0.8 mm, so as to realize the miniaturization of the module; the corresponding end face of the imaging light-guiding fiber bundle that receives the light signal of the ultrafine objective lens extends into the stainless steel cylindrical shell and is fixedly coupled with the ultrafine objective lens; the numerical aperture of the ultrafine diameter objective lens in the image space matches the numerical aperture of a single optical fiber in the light-guiding optical fiber, and the root mean square diameter of the diffuse spot formed by the ultrafine diameter objective lens on the imaging surface is smaller than the imaging diameter of a single optical fiber; the number of fiber cores of the imaging light-guiding fiber bundle is not less than 10,000 and can be up to 30,000, and the length of the imaging light-guiding fiber bundle is greater than 500 mm;.

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

[0030] ImgH / ft>0.9;

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

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

[0033] CRA﹤10°;

[0034] Wherein, CRA represents the maximum angle of the principal light of the ultra-fine objective lens incident on the imaging light-guiding fiber bundle.

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

[0036] r2=-r3;

[0037] 1﹤r8 / r10﹤1.25;

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

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

[0040] 6﹤TTL / ImgH﹤10;

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

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

[0043] 1.5﹤ft / D﹤3;

[0044] Wherein, ft represents the effective focal length of the ultra-fine objective lens, and D represents the clear diameter of the aperture stop.

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

[0046] The outer mechanical diameters of the front lens group and the rear lens group are the same, 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 surface of the first lens element to the final image side surface of the fourth lens element is the objective lens length of 1.6-1.8 mm.

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

[0050] As a further optimization solution of the present invention, the operating wavelength of the ultra-fine objective lens is 400-900nm.

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

[0052] It should also be added that the working distance of the objective lens is 2.0-25.0mm, the axial length of the human eye is about 22.0-25.0mm, and the objective lens is adapted to the imaging requirements of the internal structure of the human eye; the objective lens is suitable for a variety of imaging media in intraocular imaging surgery. When the imaging medium is vitreous or intraocular filling material during surgery (such as silicone oil, balanced salt solution, sodium hyaluronate, etc.), the maximum full field angle of the objective lens system is not less than 100 degrees; and when the imaging medium is air or gas filling material (such as sulfur hexafluoride SF6 or perfluoroethane C2F6), the maximum full field angle is not less than 130 degrees, thereby ensuring the large field imaging effect and adaptability in different surgical environments; the cylindrical spacer is placed between the ultra-fine diameter objective lens and the imaging light guide fiber bundle, providing precise spacing control to adapt to the back focal length of the objective lens, and ensuring the correct focusing and transmission of light.

[0053] The beneficial effects of the present invention are as follows: the present invention adopts an ultra-fine diameter objective lens design, which meets the requirements of small incisions in ophthalmic surgery, reduces the risk of postoperative leakage and infection, and promotes healing;

[0054] The present invention takes into account the actual imaging medium, such as vitreous body or other liquid fillers, to increase the imaging field angle, improve the clear field of view in the eye, and obtain more image information of the target part; at the same time, the design of four independent lens elements is adopted to effectively reduce the system size, reduce the difficulty of processing and assembly, and improve the stability of the system;

[0055] The objective lens group of the present invention has a wide operating wavelength range, can be applied to a variety of ophthalmic application scenarios, and has great flexibility and versatility. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0058] Figure 3 It is a schematic structural diagram of Embodiment 2 and Embodiment 3 of the front-end ultra-fine diameter optical imaging module for an ophthalmic optical fiber endoscope system of the present invention;

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

[0060] Figure 5 It is a simplified schematic diagram of the light path of the ultra-fine diameter objective lens imaging of the present invention;

[0061] Figure 6 is an imaging quality point diagram of the ultra-fine diameter objective lens of the present invention;

[0062] Figure 7 is the imaging quality MTF diagram of the ultra-fine diameter objective lens of the present invention;

[0063] Figure 8 It is a schematic diagram of the geometric structure of the front-end ultra-fine diameter optical imaging module of the present invention for an ophthalmic fiber optic endoscope system. DETAILED DESCRIPTION

[0064] The present application is further described in detail below in conjunction with the accompanying drawings. It is necessary to point out here that the following specific implementation methods are only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application. Technical personnel in this field can make some non-essential improvements and adjustments to the present application based on the above application content.

[0065] The present invention provides an ultra-fine diameter optical imaging module at the front end of an ophthalmic fiber optic endoscope system, which has a simple structure, is easy to process and assemble, and has a large depth of field. The module includes an ultra-fine diameter objective lens, an imaging light guide fiber bundle, and a metal cylindrical shell. The design of the ultra-fine diameter objective lens specifically takes into account the actual imaging medium in ophthalmic surgery, such as vitreous or other liquid fillers, so as to increase the size of the imaging field angle in the liquid medium. This enables doctors to obtain more clear views of the eye during actual surgical operations, thereby improving the efficiency and reliability of minimally invasive ophthalmic surgery. The invention solves the technical problem that the ultra-fine endoscope objective lens system existing in the current technology cannot adapt to a large field of view, a small aperture, and a large depth of field at the same time. In addition, the ultra-fine diameter objective lens of the present invention only contains five lenses, which effectively reduces the overall size, greatly reduces the difficulty of processing and assembly, and improves the stability of the system; in addition to being applicable to ophthalmology, the present invention can also be applied to neurosurgery, general surgery and other fields, and the specific implementation can refer to the following embodiments:

[0066] Example 1

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

[0068] Specifically, refer to Figure 2 As shown in the structural schematic diagram, the ultra-fine 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 power and a second lens element 2 with negative power, and the first lens element 1 and the second lens element 2 both include an object side surface and an image side surface, the first object side surface of the first lens element 1 is a plane, the first image side surface of the first lens element 1 is a concave surface, the second object side surface of the second lens element 2 is a concave surface, the second image side surface of the second lens element 2 is a plane, and the concave surfaces are relatively attached to each other;

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

[0071] The fourth lens comprises a fourth object-side surface and a fourth image-side surface, the fourth object-side surface is a convex surface, and the fourth image-side surface is a convex surface; the fifth lens comprises a fifth object-side surface and a fifth image-side surface, the fifth object-side surface is a concave surface, and the fifth image-side surface is a plane;

[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 behind the first lens element 1 , the third lens element 3 is disposed behind the second lens element 2 , and the fourth lens element 6 is disposed behind the third lens element 3 .

[0074] The first lens element 1 and the second lens element 2 both comprise plano-concave negative lenses, and the concave surface r2 of the first lens element 1 is arranged opposite to the concave surface r3 of the second lens element 2, that is, the edge of the concave surface r2 of the first lens element 1 is closely matched with the edge of the concave surface r3 of the second lens element 2. 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 double cemented positive lens, wherein the double cemented positive lens includes a biconvex positive lens 4 and a plano-concave negative lens 5 , and the biconvex positive lens 4 is arranged 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 may 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. The fourth lens element 6 corresponds to the fourth lens and the fifth lens. This part only refers to the name for the convenience of subsequent overall description.

[0077] It should be pointed out that, in this specification, the front end or front refers to the end of the ultra-fine diameter optical imaging module and the ultra-fine diameter objective lens close to the target eye tissue to be explored, and the rear end or rear refers to the end of the ultra-fine diameter objective lens 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, that is, the objective lens length, is 1.725 mm.

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

[0080] 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, which is 0.74 mm.

[0081] The optical structure parameters of the ultra-fine endoscope objective lens 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 of aperture) Infinity 0.012 - - r6 (aperture image side view) 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 plane Infinity - - -

[0083] Using the above structural parameters, the system's numerical aperture NA is 0.109 and the image-space F number is 3.81, showing a strong light collection capability. Figure 4(a) is a brief diagram of the light path of the objective lens imaging. When the imaging medium is vitreous or other liquid fillers, the maximum full field angle of the objective lens is 120 degrees; when the imaging medium is air or gas fillers (such as sulfur hexafluoride SF6 or perfluoroethane C2F6), the maximum full field angle of the objective lens system can reach 150 degrees. On the r1, r2, r3, r4, r7, r8, r9, and r11 surfaces on the ultra-fine diameter objective lens, an anti-reflection film with a wavelength range of 400-900nm is coated, which can support imaging from visible light to near-infrared bands, and enhance the light signal intensity of image plane I while reducing stray light. In addition, the working distance range of the module is 2.0-25.0mm, covering the full range of actual ophthalmic scenes, which can accurately magnify tiny details at ultra-close distances and observe different structures in the eye at a longer distance. This enables the endoscope to effectively image at different depths and positions, thereby improving the flexibility and accuracy of diagnosis.

[0084] This design uses two significant digits for the lens radius curvature (r) and thickness (d), which is different from other designs that use three significant digits, which reduces the complexity of manufacturing and measurement. This can reduce manufacturing costs, and in many practical applications, this accuracy is sufficient to meet the requirements, thereby improving efficiency. In addition, the lens structure mainly adopts a plano-concave or plano-convex form, which brings the following advantages compared to the complex meniscus structure used by others: 1) Lower manufacturing cost: Plano-concave or plano-convex structures are generally easier to manufacture, reducing manufacturing costs, especially in mass production; 2) Higher stability and durability: These structures are generally more stable and durable, and are suitable for random unstable environments; 3) Easier to optimize optical performance: Compared with complex structures, plano-concave or plano-convex lenses are easier to optimize optical performance, simplifying the design process, while reducing optical interference and improving imaging quality; 4) Easy to integrate and assemble: Due to their simple structure, these lenses are easier to integrate with other optical components, simplifying the assembly process and speeding up the product development cycle. This makes it a competitive choice in this application.

[0085] In order to control the optical lens spacing of the ultra-fine diameter objective lens and the spatial position of the aperture stop A to ensure that the objective lens 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-fine diameter objective lens is composed 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 arranged from left to right. In this embodiment, the total outer diameter of the optical fiber bundle F is 0.75 mm ± 0.03 mm, wherein the effective image transmission surface diameter is 0.60 ± 0.03 mm, the single fiber core spacing and the system imaging pixel size are 3.3 μm, and the number of fiber cores, i.e., the number of pixels, is 30,000. In addition, in order to form a front-end ultra-fine diameter optical imaging module, the ultra-fine diameter objective lens and the imaging light guide fiber bundle F are coupled and fixed in the annular metal housing B. The rear end face of the objective lens, i.e., the length from 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 0.365 mm. A cylindrical spacer S4 is placed between the ultra-fine objective lens and the optical fiber bundle F to accommodate the back focal length of the objective lens.

[0087] In this embodiment, if Figure 6 (a) shows the point diagram of the objective lens at different points in the field of view. Specifically, Figure 6 The object planes 0.00 (degrees), 18.00 (degrees), 30.00 (degrees), 42.00 (degrees), 48.00 (degrees) and 60.00 (degrees) in (a) represent the situation at the center of the object field of view, 18 degrees, 30 degrees, 42 degrees, 48 ​​degrees and the maximum field of view of 60 degrees, respectively. Through calculation, it can be known that at the above-mentioned field of view points, the root mean square diameter of the diffuse spot is 0.796μm, 1.412μm, 2.104μm, 1.906μm, 1.434μm and 1.814μm, respectively. These values ​​are all less than 3.3μm, that is, less than the core diameter of a single optical fiber in the imaging fiber bundle F, which indicates that the light spot generated by the imaging system falls completely inside the optical fiber core, ensuring that the optical fiber can effectively capture and transmit all light.

[0088] In addition, the half-image height of the ultra-fine objective lens in this embodiment reaches 0.3mm, which completely covers the effective image transmission surface of the optical fiber bundle and avoids the loss of light energy information; at the same time, the image space numerical aperture (NA=0.109) of the objective lens is smaller than the numerical aperture (NA=0.41) of a single optical fiber in the imaging light-guiding optical fiber F, which fully demonstrates that the receiving capacity of the optical fiber exceeds the output capacity of the objective lens, so that all the light output by the objective lens can be fully captured, achieving efficient light energy transmission, and effectively avoiding crosstalk between pixels, optimizing the imaging quality. These features make the ultra-fine objective lens of this embodiment an ideal choice for high-precision ophthalmic endoscopic imaging needs.

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

[0090]

[0091] As can be seen from the figure, when the field of view is 60 degrees, the corresponding values ​​of the meridian plane (T) MTF curve and the sagittal plane (S) MTF curve at the horizontal coordinate of 175lp / mm are both greater than 0.32, which means that at the edge of the field of view, the 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-fine diameter objective lens of this embodiment an ideal choice for high-precision ophthalmic endoscopic imaging needs.

[0092] refer to Figure 8 The following table lists the geometric dimensions of the housing B, Mylar sheet A and gaskets S1-S4:

[0093]

[0094] This embodiment uses a cleverly designed ultra-thin optical imaging module to not only achieve a 30,000-pixel imaging module with an external mechanical diameter of only 0.8 mm in an ophthalmic fiber endoscope system, but also provides high-precision, high-resolution imaging with a wide field of view for different imaging media that may be encountered in ophthalmic surgery, such as vitreous or gas fillings. The design integrates four independent lens elements and fine optical control elements to ensure excellent imaging performance close to the diffraction limit within a maximum field of view of 120 to 150 degrees, greatly improving the flexibility and accuracy of diagnosis, while simplifying the manufacturing process and reducing costs, providing strong technical support for minimally invasive ophthalmic surgery and examinations, and meeting the needs of high-precision ophthalmic endoscopic imaging.

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

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

[0097] Example 2

[0098] In this embodiment, it should be noted that, unless otherwise specified, all components and their characteristics that are not re-described maintain the same configuration and function as those of Embodiment 1. Embodiment 2 mainly shows several key changes compared with Embodiment 1.

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

[0100] like Figure 3 As shown in the upper middle view, the ultra-fine diameter objective lens of this embodiment is composed of 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 from left to right; compared with Example 1, 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 support to each other without the need for a cylindrical spacing gasket; in this way, no additional gasket support is required 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 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, that is, the total length of the objective lens is 1.613 mm. The aperture stop A1 is disposed in the middle of the second lens element 2a and the third lens element 3a.

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

[0103] With the above structural parameters, the system numerical aperture is 0.132 and the image space F number is 3.73.

[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 of aperture) Infinity 0.012 - - r6a (aperture image side view) 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 plane Infinity - - -

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

[0106] In this embodiment, the imaging light-guiding optical fiber bundle F1 used is the same as the imaging light-guiding optical fiber bundle F in Embodiment 1. In order to form a front-end ultra-fine diameter optical imaging module, the ultra-fine diameter objective lens and the imaging light-guiding optical fiber bundle F1 are coupled and fixed in an 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-guiding optical 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 optical fiber bundle F1 to adapt to the back focal length of the objective lens.

[0107] like Figure 6 (b) shows the point diagram of the objective lens at different viewing points in this embodiment. Figure 6 As shown in (b), the object plane 0.00 (degree), object plane 18.00 (degree), object plane 30.00 (degree), object plane 42.00 (degree), object plane 48.00 (degree) and object plane 60.00 (degree) represent the center of the object field of view, 18 degrees, 30 degrees, 42 degrees, 48 ​​degrees, and the maximum field of view of 60 degrees, respectively. After calculation, the root mean square diameter of the diffuse spot at each field point is 2.618μm, 1.712μm, 1.908μm, 1.972μm, 1.672μm, and 2.516μm, respectively. These values ​​are all less than 3.3μm, that is, less than the core diameter of a single optical fiber in the imaging fiber bundle F1.

[0108] In addition, the half-image height of the objective lens in this embodiment reaches 0.3 mm, which completely covers the effective image transmission surface of the optical fiber bundle and avoids the loss of light 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 optical fiber in the imaging light-guiding optical fiber F1.

[0109] Figure 7 (b) shows the MTF (Modulation Transfer Function) curve of the objective lens of this embodiment at the maximum field of view, i.e., at the edge of 60 degrees. It can be seen from the figure that when the field of view is 60 degrees, the corresponding values ​​of the meridian plane (T) MTF curve and the sagittal plane (S) MTF curve when the horizontal coordinate is 175lp / mm are both greater than 0.35.

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

[0111]

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

[0113] Example 3

[0114] In Example 3, unless otherwise specified, all components and their characteristics that are not re-described maintain the same configuration and function as those of Example 2. Example 3 mainly shows several key changes compared with Example 1 and Example 2.

[0115] Compared with Example 2, the external mechanical diameter of the module of Example 3 is smaller, only 0.56 mm, and is suitable for the 10,000-pixel optical fiber bundle F2. Figure 3 As shown in the lower part of the structure, the ultra-fine diameter objective lens of this embodiment is composed of 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 from left to right. Compared with Example 2, 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 surface r8b of the third lens element 3b and the fourth object side surface r9b of the fourth lens element 4b are in direct contact at the center, providing support to each other, and no cylindrical spacer is required.

[0116] In particular, the concave surface r2b of the first lens element 1b is closely matched with the edge of the concave surface r3b of the second lens element 2b, and the distance between the center of the first lens element 1b and the center of 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, that is, the total length of the objective lens is 1.395 mm.

[0118] In this embodiment, the aperture stop A2 is made of a circular Mylar sheet material with a thickness of 12 μm and an outer diameter of 0.50 mm; the circular opening is made in the center of the circular matte Mylar sheet, and the circular opening diameter is 0.12 mm, which is used as the aperture stop A2 and is arranged in the middle of 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, which is 0.50 mm in value.

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

[0120]

[0121] The diameter is 0.164 and the image space F number is 3.0.

[0122] When the imaging medium is glass or other liquid fillings, the maximum full field angle of the objective lens is equal to 100 degrees; when the imaging medium is air and gas fillings (such as sulfur hexafluoride (SF6) or perfluoroethane (C2F6)), the maximum full field angle of the objective lens system can reach 130 degrees. In addition, the module working distance is 2.0-25.0mm.

[0123] In this embodiment, the total outer diameter of the optical fiber bundle F2 is 0.44±0.03 mm, of which the effective image transmission surface diameter is 0.325±0.02 mm, the single fiber core spacing and the system imaging pixel size are 3.3 μm, and the number of fiber cores, i.e., the number of pixels, is 10,000.

[0124] In this configuration, the ultra-fine objective lens and the imaging light-guiding optical 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 face r11 of the fourth lens element 6b, to the receiving face I2 of the imaging light-guiding optical fiber bundle, i.e., the back focal length of the objective lens is 0.25 mm. The imaging light-guiding optical fiber bundle F2 extends into the cylindrical spacer S4b, with a space of 0.25 mm at the front end to adapt to the back focal length of the objective lens and ensure that the optical fiber bundle is tightly coupled with the annular metal housing 2B.

[0125] Figure 6 (c) shows the point diagram of the objective lens at different points in the field of view of this embodiment. As shown in 6(c), object plane 0.00 (degree), object plane 18.00 (degree), object plane 30.00 (degree), object plane 42.00 (degree), object plane 48.00 (degree) and object plane 60.00 (degree) represent the center of the object field of view, 18 degrees, 30 degrees, 42 degrees, 48 ​​degrees, and the maximum field of view of 60 degrees, respectively. After calculation, at each point in the field of view, the root mean square diameter of the diffuse spot is 1.418μm, 1.066μm, 1.420μm, 1.478μm, 1.360μm, and 1.442μm, respectively. These values ​​are all less than 3.3μm, that is, less than the core diameter of a single optical 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 optical fiber bundle without losing light energy information; the image space numerical aperture of the objective lens (NA=0.164) matches the numerical aperture of a single optical fiber in the imaging light-guiding optical fiber F (NA=0.41), thereby ensuring high-quality image transmission, avoiding crosstalk between pixels, and achieving clear imaging.

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

[0128] The following table lists the geometric dimensions of the housing 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 outer diameter of the module and optimizing the lens structure. Compared with Embodiment 1 and Embodiment 2, the number of imaging pixels of the ophthalmic fiber endoscopic imaging module of this embodiment is reduced from 30,000 to 10,000, but the outer diameter of the module is reduced from 0.8 mm to 0.56 mm, which brings significant advantages to ophthalmic endoscopic surgery and examination:

[0131] First, thinner modules allow for smaller incisions and more minimally invasive surgical procedures, reducing the patient's recovery time and the risk of postoperative complications. Second, the smaller outer diameter improves the flexibility and maneuverability of the module, enabling it to access narrower or tortuous intraocular areas, enhancing accessibility for inspection and treatment. In addition, thinner modules interfere less with surrounding tissues when moving within the eye, which helps improve surgical precision and safety.

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

[0133] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0134] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms should not be understood as necessarily referring to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0135] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A front-end ultra-fine diameter optical imaging module for an ophthalmic fiber endoscope system, characterized in that: The module includes an ultra-fine diameter objective lens; The ultra-fine diameter objective lens comprises a front lens group and a rear lens group; The front lens group includes a first lens element with negative power and a second lens element with negative power, and the first lens element and the second lens element both include an object side surface and an image side surface, the first object side surface of the first lens element is a plane, the first image side surface of the first lens element is a concave surface, the second object side surface of the second lens element is a concave surface, the second image side surface of the second lens element is a plane, and the concave surfaces are relatively attached to each other; The rear lens group includes a third lens element with positive 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 power and a fifth lens with negative power, and the two are fixedly connected; The fourth lens comprises a fourth object-side surface and a fourth image-side surface, the fourth object-side surface is a convex surface, and the fourth image-side surface is a convex surface; the fifth lens comprises a fifth object-side surface and a fifth image-side surface, the fifth object-side surface is a concave surface, and the fifth image-side surface is a plane; An aperture stop is also provided between the second lens element and the third lens element; The second lens element is disposed behind the first lens element, the third lens element is disposed behind the second lens element, and the fourth lens element is disposed behind the third lens element.

2. The front-end ultra-thin optical imaging module for an ophthalmic fiber endoscope system according to claim 1, characterized in that: The first lens element and the second lens element both comprise plano-concave negative lenses, the concave surface of the first lens element is arranged opposite to the concave surface of the second lens element, that is, the edge of the concave surface of the first lens element is closely matched with the edge of the concave surface of the second lens element; The third lens element comprises a plano-convex positive lens, and the fourth lens element comprises a double cemented positive lens, wherein the double cemented positive lens comprises a biconvex positive lens and a plano-concave negative lens, and the biconvex positive lens is arranged before the plano-concave negative lens.

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

4. The front-end ultra-thin optical imaging module for an ophthalmic fiber 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 of the principal light of the ultra-fine objective lens incident on the imaging light-guiding fiber bundle.

5. The front-end ultra-thin optical imaging module for an ophthalmic fiber 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； Among them, r2 represents the curvature radius of the first image side surface of the first lens element; r3 represents the curvature radius of the second object side surface of the second lens element; r8 represents the curvature radius of the third image side surface of the third lens element; r10 represents the fourth image side surface of the fourth lens element.

6. The front-end ultra-thin optical imaging module for an ophthalmic fiber 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 on-axis distance from the first object side surface of the first lens element to the imaging surface of the ultra-fine objective lens, and ImgH represents the radius of the pixel area on the end surface of the imaging light-guiding fiber bundle that can be effectively imaged.

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

8. The front-end ultra-thin optical imaging module for an ophthalmic fiber 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 in the five lens groups is not less than 0.12 mm, and the center thickness is not less than 0.11 mm; The outer mechanical diameters of the front lens group and the rear lens group are the same, 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 surface of the first lens element to the final image side surface of the fourth lens element is the objective lens length of 1.6-1.8 mm.

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

10. The front-end ultra-thin optical imaging module for an ophthalmic fiber 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-guiding optical fiber bundle, that is, the back focal length of the ultra-fine objective lens, is 0.25-0.4 mm.

Images