Objective optical system and electronic endoscope thereof

Abstract

The utility model provides an objective optical system and an electronic endoscope thereof, and relates to the technical field of medical instruments, and the objective optical system comprises a first lens group, a diaphragm, a second lens group, a third lens group and an optical filter which are sequentially arranged from an object side to an image side along an optical axis; the first lens group comprises a meniscus lens and a cylindrical lens, and the concave surface of the meniscus lens faces the cylindrical lens; the second lens group comprises a plano-convex lens, and a diaphragm is located between the cylindrical lens and the plane of the plano-convex lens; the third lens group comprises two groups of biconvex lenses and a biconcave lens arranged between the two groups of biconvex lenses, the two groups of biconvex lenses and the biconcave lens form a positive focal power lens group, and the plano-convex lenses and the third lens group are arranged at intervals in the optical axis direction. The electronic endoscope includes an objective optical system. By optimizing the structure and layout of the objective optical system, the definition of an imaging picture of the endoscope and the uniformity of the brightness of a display picture can be improved.

Description

Technical Field

[0001] This utility model relates to the technical field of medical instruments, and in particular to an objective lens optical system and its electronic endoscope. Background Technology

[0002] Endoscopes, as important medical optical instruments, are widely used in the diagnosis and treatment of the digestive, respiratory, and urinary systems. Traditional endoscopes mainly consist of a scope, lens, light source, and image transmission system. They can enter the human body through natural orifices or minimally invasive incisions to provide real-time internal images and assist doctors in performing precise operations.

[0003] The objective lens of an existing endoscope is a key component of the endoscope body and has a significant impact on the insertion width, image clarity and brightness of the endoscope, which is of great importance to improving the user experience during the surgical procedure.

[0004] Currently available endoscope objectives suffer from poor uniformity, with significantly lower illumination around the edges of the image plane compared to the center. Therefore, a novel objective optical system is urgently needed to address this issue. Utility Model Content

[0005] The purpose of this application is to provide an objective lens optical system and its electronic endoscope. By optimizing the structure and layout of the objective lens optical system, the clarity of the endoscope image and the uniformity of the display brightness can be improved.

[0006] In a first aspect, embodiments of this application provide an objective lens optical system, comprising: a first lens group, an aperture stop, a second lens group, a third lens group, and a filter arranged sequentially along the optical axis from the object side to the image side;

[0007] The first lens group includes a meniscus lens and a cylindrical lens, with the concave surface of the meniscus lens facing the cylindrical lens;

[0008] The second lens group includes a plano-convex lens, and the aperture stop is located between the plane of the cylindrical lens and the plano-convex lens;

[0009] The third lens group includes two sets of biconvex lenses and a biconcave lens disposed between the two sets of biconvex lenses. The three together constitute a positive power lens group. The plano-convex lens and the third lens group are arranged at intervals in the optical axis direction.

[0010] The focal length and air gap length of each lens group in the objective lens optical system satisfy the following condition:

[0011] -1.3 <f1 / f0<-1.0 (1)

[0012] 1.6 <f2 / f0<2.0 (2)

[0013] 3.1 <f3 / f0<3.6 (3)

[0014] 0.22 <L1 / f0<0.3 (4)

[0015] 0.52 <L2 / f0<0.8 (5)

[0016] Where f0 is the focal length of the objective lens optical system;

[0017] f1 is the focal length of the meniscus lens;

[0018] f2 is the focal length of the plano-convex lens;

[0019] f3 is the focal length of the third lens group;

[0020] L1 is the distance between the plano-convex lens and the third lens group along the optical axis;

[0021] L2 is the distance between the third lens group and the filter along the optical axis;

[0022] All units are in mm.

[0023] Furthermore, the two sets of biconvex lenses are cemented together with the biconcave lens to form a cemented triplet lens.

[0024] Furthermore, the meniscus lens, the plano-convex lens, the biconvex lens, and the biconcave lens are all spherical lenses.

[0025] Furthermore, the aperture includes a light-transmitting aperture and an annular light-blocking portion surrounding the light-transmitting aperture;

[0026] The light-transmitting aperture is arranged collinearly with the optical axis.

[0027] Furthermore, the annular light-shielding portion is coated on the end face of the cylindrical lens facing away from the meniscus lens.

[0028] Furthermore, the aperture has a circular light-transmitting hole with a diameter ranging from 0.5 to 1.0 mm.

[0029] Furthermore, the outer diameters of the first lens group, the second lens group, and the third lens group are all equal.

[0030] Furthermore, the outer diameters of the first lens group, the second lens group, and the third lens group range from 2.8 to 3.2 mm.

[0031] Furthermore, the field of view of the objective lens optical system is 75–85°.

[0032] The objective lens optical system provided in this application embodiment has at least the following beneficial effects:

[0033] Under the premise of satisfying the conditions of this application, the focal length and air gap length of each lens group in the objective lens optical system include a first lens group, an aperture stop, a second lens group, a third lens group, and a filter arranged sequentially along the optical axis from the object side to the image side. The first lens group includes a meniscus lens and a cylindrical lens. The meniscus lens can allow light with a larger field of view to enter the objective lens, increasing the field of view. The second lens group includes a plano-convex lens. The aperture stop is located between the plane of the cylindrical lens and the plano-convex lens. By setting the aperture of the aperture stop, the amount of light entering can be increased, thereby improving the overall illumination of the image plane. At the same time, the plano-convex lens can correct excess aberrations and reduce the angle of light rays, allowing light rays to enter the third lens group smoothly. The third lens group includes two sets of biconvex lenses and a biconcave lens disposed between the two sets of biconvex lenses. The three of them constitute a positive power lens group, which can correct chromatic aberration and reduce the angle of light rays when reaching the image plane, thereby improving the illumination of different fields of view of the image plane.

[0034] As mentioned above, this objective lens optical system can have a large field of view, allowing light from a larger field of view to enter the objective lens. Furthermore, by setting the aperture of the aperture stop, the amount of light entering is increased, thereby improving the overall illumination of the image surface. At the same time, based on correcting redundant aberrations and reducing the angle of light rays, more light rays are allowed to enter the third lens group. Based on correcting chromatic aberration, by reducing the angle at which light rays reach the image surface, the illumination of different fields of view on the image surface is increased, thereby achieving a relatively uniform illumination around the image surface and at the center, thus improving the clarity of the endoscopic image and the uniformity of the displayed image brightness.

[0035] Secondly, embodiments of this application provide an electronic endoscope, including the aforementioned objective lens optical system.

[0036] The electronic endoscope provided in this application includes an objective lens optical system. Therefore, the technical advantages and effects that the electronic endoscope can achieve also include the technical advantages and effects that the aforementioned objective lens optical system can achieve, which will not be repeated here. Attached Figure Description

[0037] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of the objective lens optical system provided in an embodiment of the present invention;

[0039] Figure 2MTF curve of the objective lens optical system provided in the embodiment of this utility model;

[0040] Figure 3 A spherical aberration curve of the objective lens optical system provided in an embodiment of this utility model;

[0041] Figure 4 A relative illumination curve of the objective lens optical system provided in an embodiment of this utility model.

[0042] icon:

[0043] 110 - Meniscus lens; 120 - Cylindrical lens;

[0044] 200-Planar-convex lens;

[0045] 310 - Biconvex lens; 320 - Biconcave lens;

[0046] 400-Filter. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0048] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0049] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0050] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this utility model is in use. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0051] Furthermore, terms such as "horizontal," "vertical," and "suspended" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," not that the structure must be completely horizontal, but can be slightly tilted.

[0052] In the description of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0053] The following detailed description, in conjunction with the accompanying drawings, outlines some embodiments of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0054] Reference Figure 1 This embodiment provides an objective lens optical system, which includes a first lens group, an aperture stop, a second lens group, a third lens group, and a filter 400 arranged sequentially along the optical axis from the object side to the image side. The first lens group includes a meniscus lens 110 and a cylindrical lens 120, with the concave surface of the meniscus lens 110 positioned close to the cylindrical lens 120. The second lens group includes a plano-convex lens 200, with the aperture stop located between the planes of the cylindrical lens 120 and the plano-convex lens 200. The third lens group includes two sets of biconvex lenses 310 and a biconcave lens 320 disposed between the two sets of biconvex lenses 310. The three lenses constitute a positive power lens group, wherein the plano-convex lens 200 and the third lens group are spaced apart along the optical axis. The focal length and air gap length of each lens group in the objective lens optical system satisfy the following condition:

[0055] -1.3 <f1 / f0<-1.0 (1)

[0056] 1.6 <f2 / f0<2.0 (2)

[0057] 3.1 <f3 / f0<3.6 (3)

[0058] 0.22 <L1 / f0<0.3 (4)

[0059] 0.52 <L2 / f0<0.8 (5)

[0060] Where f0 is the focal length of the objective lens optical system; f1 is the focal length of the meniscus lens 110; f2 is the focal length of the plano-convex lens 200; f3 is the focal length of the third lens group; L1 is the distance between the plano-convex lens 200 and the third lens group along the optical axis; L2 is the distance between the third lens group and the filter 400 along the optical axis; all units are mm.

[0061] In this embodiment, the focal length and air gap length of each lens group in the objective lens optical system, provided that the conditions of this application are met, are determined by the following: the objective lens optical system includes a first lens group, an aperture stop, a second lens group, a third lens group, and a filter 400 arranged sequentially along the optical axis from the object side to the image side. The first lens group includes a meniscus lens 110 and a cylindrical lens 120. The meniscus lens 110 allows light with a larger field of view to enter the objective lens, increasing the field of view. The second lens group includes a plano-convex lens 200, and the aperture stop is located at the position of the cylindrical lens 120. Between the plane of the plano-convex lens 200 and the plane of the plano-convex lens 200, the light intake can be increased by setting the aperture of the aperture stop, thereby improving the overall illumination of the image plane. At the same time, the plano-convex lens 200 can correct excess aberrations and reduce the angle of light rays, so that light rays can smoothly enter the third lens group. The third lens group includes two sets of biconvex lenses 310 and a biconcave lens 320 disposed between the two sets of biconvex lenses 310. The three of them constitute a positive power lens group, which can correct chromatic aberration and reduce the angle of light rays when they reach the image plane, thereby improving the illumination of different fields of view of the image plane.

[0062] As mentioned above, this objective lens optical system can have a large field of view, allowing light from a larger field of view to enter the objective lens. Furthermore, by setting the aperture of the aperture stop, the amount of light entering is increased, thereby improving the overall illumination of the image surface. At the same time, based on correcting redundant aberrations and reducing the angle of light rays, more light rays are allowed to enter the third lens group. Based on correcting chromatic aberration, by reducing the angle at which light rays reach the image surface, the illumination of different fields of view on the image surface is increased, thereby achieving a relatively uniform illumination around the image surface and at the center, thus improving the clarity of the endoscopic image and the uniformity of the displayed image brightness.

[0063] Specifically, such as Figure 1 As shown, the left side of the meniscus lens 110 is convex, and the right side is concave, with the concave side facing the cylindrical lens 120. In this embodiment, the filter 400 can be an infrared filter.

[0064] In this embodiment, the aperture includes a light-transmitting aperture and an annular light-blocking portion surrounding the light-transmitting aperture. The light-transmitting aperture is arranged collinearly with the optical axis, and light rays passing through the meniscus lens 110 and the cylindrical lens 120 can pass through the light-transmitting aperture of the aperture to ensure the amount of light entering.

[0065] Furthermore, an annular light-shielding part is coated on the end face of the cylindrical lens 120 facing away from the meniscus lens 110. This arrangement facilitates the arrangement of the aperture. In actual operation, an annular light-shielding part with a preset aperture can be coated on the end face of the cylindrical lens 120. The annular light-shielding part can be coated with black light-shielding material.

[0066] In this embodiment, the aperture of the light-transmitting hole ranges from 0.5 to 1.0 mm. For example, the aperture of the light-transmitting hole can be 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, etc. Selecting a light-transmitting hole with a suitable aperture can effectively increase the amount of light entering the image, thereby improving the image sharpness and overall illumination.

[0067] Please continue to refer to Figure 1 Two sets of biconvex lenses 310 and biconcave lenses 320 are cemented together to form a triplet lens. Specifically, the two concave surfaces of the biconcave lens 320 can be cemented and fixed to the corresponding biconvex lens 310 with ultraviolet glue. This arrangement can maintain the connection stability of the three and at the same time ensure that the plano-convex lens 200 and the third lens group are separated by a suitable distance.

[0068] In this embodiment, the meniscus lens 110, plano-convex lens 200, biconvex lens 310, and biconcave lens 320 are all spherical lenses. This embodiment uses spherical lenses instead of existing aspherical lenses, which, while meeting the usage requirements and effects of this application, also relatively reduces costs.

[0069] In this embodiment, the outer diameters of the first lens group, the second lens group, and the third lens group are all equal. Furthermore, the outer diameters of the first lens group, the second lens group, and the third lens group range from 2.8 to 3.2 mm. Exemplarily, the outer diameter ranges of the three can be 2.8 mm, 2.9 mm, 3.0 mm, 3.1 mm, 3.2 mm, etc. This configuration ensures that the objective lens optical system has a small outer diameter, thereby enabling a smaller diameter design for the endoscope insertion portion and helping to reduce the endoscope insertion area or width.

[0070] In this embodiment, the field of view of the objective lens optical system ranges from 75° to 85°. The meniscus lens 110 in this embodiment allows light rays with a larger field of view to enter the objective lens optical system, thereby achieving a larger field of view. Exemplarily, the field of view of the objective lens optical system can be 75°, 76°, 77°, 78°, 79°, 80°, 81°, 82°, 83°, 84°, 85°, etc.

[0071] like Figure 2 The figure shows the MTF curve of the objective lens optical system of this embodiment. The horizontal axis represents spatial frequency and the vertical axis represents contrast. The MTF curve shows that the objective lens optical system of this application can achieve a contrast ratio of over 0.28 in each field of view at a line logarithm of 200 lp / mm, which can greatly improve the clarity of the endoscope image.

[0072] like Figure 3 The figure shown is a spherical aberration curve of the objective lens optical system in this embodiment. The horizontal axis represents the axial imaging position, and the vertical axis represents different pupil radii. The spherical aberration of the objective lens optical system is <0.02mm, which ensures good imaging of the objective lens optical system. At the same time, the chromatic aberration at multiple wavelengths is <0.01mm, which ensures that there will be no color layering in the final image.

[0073] It should be noted that the "spherical aberration" mentioned above refers to the difference in imaging position between the maximum and minimum pupil radii; the "chromatic aberration" mentioned above refers to the difference in imaging position between different wavelengths.

[0074] like Figure 4 The figure shows the relative illumination curve of the objective lens optical system in this embodiment. The horizontal axis represents the field of view angle value, and the vertical axis represents the relative illumination. The relative illumination of the objective lens optical system is close to 100% in each field of view, which can effectively ensure the uniformity of image plane illumination in each field of view, thereby improving the uniformity of the endoscope display and enhancing the viewing effect.

[0075] This embodiment also provides an electronic endoscope, including the aforementioned objective lens optical system. Since the electronic endoscope provided in this embodiment includes the objective lens optical system of the aforementioned embodiment, the technical advantages and effects achieved by this electronic endoscope also include those achieved by the objective lens optical system, which will not be repeated here.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. An objective lens optical system, characterized in that, include: A first lens group, an aperture, a second lens group, a third lens group, and a filter are arranged sequentially along the optical axis from the object side to the image side. The first lens group includes a meniscus lens and a cylindrical lens, with the concave surface of the meniscus lens facing the cylindrical lens; The second lens group includes a plano-convex lens, and the aperture stop is located between the plane of the cylindrical lens and the plano-convex lens; The third lens group includes two sets of biconvex lenses and a biconcave lens disposed between the two sets of biconvex lenses. The three together constitute a positive power lens group. The plano-convex lens and the third lens group are arranged at intervals in the optical axis direction. The focal length and air gap length of each lens group in the objective lens optical system satisfy the following condition: -1.3 <f1 / f0<-1.0 (1) 1.6 <f2 / f0<2.0 (2) 3.1 <f3 / f0<3.6 (3) 0.22 <L1 / f0<0.3 (4) 0.52 <L2 / f0<0.8 (5) Where f0 is the focal length of the objective lens optical system; f1 is the focal length of the meniscus lens; f2 is the focal length of the plano-convex lens; f3 is the focal length of the third lens group; L1 is the distance between the plano-convex lens and the third lens group along the optical axis; L2 is the distance between the third lens group and the filter along the optical axis; All units are in mm.

2. The objective lens optical system according to claim 1, characterized in that, The two sets of biconvex lenses and the biconcave lens are cemented together to form a cemented triplet lens.

3. The objective lens optical system according to claim 1, characterized in that, The meniscus lens, the plano-convex lens, the biconvex lens, and the biconcave lens are all spherical lenses.

4. The objective lens optical system according to claim 1, characterized in that, The aperture includes a light-transmitting aperture and an annular light-blocking portion surrounding the light-transmitting aperture; The light-transmitting aperture is arranged collinearly with the optical axis.

5. The objective lens optical system according to claim 4, characterized in that, The annular light-shielding portion is coated on the end face of the cylindrical lens facing away from the meniscus lens.

6. The objective lens optical system according to claim 1, characterized in that, The aperture has a circular light-transmitting hole with a diameter ranging from 0.5 to 1.0 mm.

7. The objective lens optical system according to any one of claims 1-6, characterized in that, The outer diameters of the first lens group, the second lens group, and the third lens group are all equal.

8. The objective lens optical system according to claim 7, characterized in that, The outer diameter range of the first lens group, the second lens group, and the third lens group is 2.8 to 3.2 mm.

9. The objective lens optical system according to claim 1, characterized in that, The field of view of the objective lens optical system is 75–85°.

10. An electronic endoscope, characterized in that, Includes the objective lens optical system described in any one of claims 1-9.

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