A high-resolution, wide-field-of-view medical endoscope optical path system

Abstract

This solution provides a high-resolution, wide-field-of-view medical endoscope optical path system, comprising, from the object side, an objective lens, a rod lens, and an eyepiece. The objective lens, from the object side, includes a light-gathering structure and a convex-concave-convex objective lens focal length structure composed of a convex lens, a concave lens, and a convex lens. The rod lens comprises multiple sets of single-lens groups arranged sequentially, each set being symmetrical. The left and right sides respectively include convex-concave-convex point diffusion function reduction structures composed of a convex lens, a concave lens, and a convex lens. The eyepiece comprises a convex lens, a convex lens, and a concave lens to form a convex-convex-concave structure. This improved combination of objective lens, rod lens, and eyepiece enhances the performance of the endoscope optical path system, such as improving image clarity, expanding the field of view, and increasing resolution, thereby improving the imaging quality of the endoscope and making a significant contribution to enhancing the diagnostic level of the medical endoscopy industry.

Description

Technical Field

[0001] This invention belongs to the field of medical devices, and in particular relates to a high-resolution, wide-field-of-view medical endoscope optical path system. Background Technology

[0002] An endoscope is a camera device equipped with a light that can be inserted into the body through the mouth, other natural orifices, or other non-natural orifices. Endoscopes can visualize lesions that cannot be seen with X-rays, making them extremely useful for diagnosing lesions.

[0003] The optical path system of an endoscope is a major component of the endoscope. It consists of the optical path system running sequentially along the optical axis from the objective side, objective lens, rod lens, eyepiece, adapter (replacing an ideal lens), to the image plane. Currently, existing medical endoscopes are typically paired with an f / 22 (22mm focal length) adapter, resulting in a field of view of 37.5°. With a half-image height greater than 2.5mm, the maximum angular resolution generally does not exceed 11.0°. This results in problems such as an excessively small field of view and low resolution, indicating significant room for improvement. This solution starts with the optical path system, improving the objective lens, rod lens, and eyepiece, and then using the improved combination of these elements to enhance the resolution of the endoscope's optical path system, expand the field of view, and thus improve the imaging quality of the endoscope. Summary of the Invention

[0004] The purpose of this invention is to address the above-mentioned problems by providing a high-resolution, wide-field-of-view medical endoscope optical path system.

[0005] To achieve the above objectives, the present invention adopts the following technical solutions:

[0006] A high-resolution, wide-field-of-view medical endoscope optical path system comprises, from the object side, an objective lens, a rod lens, and an eyepiece. The objective lens, from the object side, comprises, in sequence, a light-gathering structure and a convex-concave-convex objective lens focal length structure composed of a convex lens, a concave lens, and a convex lens. The rod lens comprises multiple sets of single-lens groups arranged sequentially, with each set of single-lens groups being symmetrical from left to right. The left and right portions respectively include a convex-concave-convex dot diffusion function reduction structure composed of a convex lens, a concave lens, and a convex lens. The eyepiece comprises, in sequence, a convex lens, a concave lens to form a convex-convex-concave structure.

[0007] The objective lens includes a light-gathering structure and a convex-concave-convex objective lens focal length structure. The light-gathering structure gathers light to maximize the field of view, while the convex-concave-convex objective lens focal length structure corrects spherical aberration, improving image quality. Each single-lens group consists of convex lenses, concave lenses, and convex lenses, making the entire single-lens group a positive lens, thus achieving a smaller point spread function and improving image quality and resolution. The convex-concave structure of the eyepiece also contributes to improving resolution. Therefore, the combination of the above-mentioned objective lens, rod lens, and eyepiece can expand the field of view, improve the image quality and resolution of the endoscope, and enhance the image clarity of the endoscope, thereby effectively improving the diagnostic level of the medical endoscopy industry.

[0008] In the aforementioned high-resolution, wide-field-of-view medical endoscope optical path system, the objective lens located between the light-gathering structure and the convex-concave-convex objective lens focal length structure also has lenses L3 and L4.

[0009] Both lenses L3 and L4 are plane mirrors;

[0010] Alternatively, lenses L3 and L4 can both be prisms, and L5 can also be replaced with a prism. L3, L4, and L5 together form a convex lens structure, and a suitable convex lens is selected according to the required viewing angle. The three prisms L3, L4, and L5 form a convex lens, which, together with L6 and L7, forms a convex-concave-convex objective lens focal length structure.

[0011] In the aforementioned high-resolution, wide-field-of-view medical endoscope optical path system, the objective lens located on the side of the convex-concave-convex objective lens focal length structure near the rod lens also includes a cemented lens group and a rod lens field curvature correction structure.

[0012] In the aforementioned high-resolution, wide-field-of-view medical endoscope optical path system, the cemented lens group includes L8 and L9;

[0013] L8 is a concave lens where both L8S1 and L8S2 are concave, and the radius of curvature of L8S2 is greater than that of L8S1; L9 is a convex lens where both L9S1 and L9S2 are convex, and the radius of curvature of L9S1 is greater than that of L9S2, and the radius of curvature of L9S1 is equal to that of L8S2 so that L9S1 and L8S2 are coupled.

[0014] The rod lens field curvature correction structure includes a convex lens L10, with L10S1 being convex and L10S2 being concave, and the radius of curvature of L10S2 being greater than that of L10S1.

[0015] S1 represents the left side, and S2 represents the right side.

[0016] In the aforementioned high-resolution, wide-field-of-view medical endoscope optical path system, the convex-concave-convex objective lens focal length structure includes a convex lens L5, a concave lens L6, and a convex lens L7, wherein L5S1 is planar, L5S2 and L6S1 are both convex, L6S2 and L7S1 are both concave, and L7S2 is convex.

[0017] The curvature radius relationship is: L5S2>L7S1>L6S1>L7S2>L6S2.

[0018] In the aforementioned high-resolution, wide-field-of-view medical endoscope optical path system, the light-gathering structure includes a concave lens L2, and the concave lens L2 has a convex surface on the object side L2S1 and a concave surface on the side of the convex-concave-convex objective lens focal length structure, and the radius of curvature of L2S1 is greater than that of L2S2.

[0019] In the aforementioned high-resolution, wide-field-of-view medical endoscope optical path system, the objective lens also includes a planar protective mirror L1 located on the concave lens L2 near the object side.

[0020] In the aforementioned high-resolution, wide-field-of-view medical endoscope optical path system, the rod lens includes three sets of single-lens groups arranged sequentially; each set of single-lens groups includes lenses L11, L12, L13, L14, L15, and L16, where L11, L12, and L13 are a convex lens, a concave lens, and a convex lens, respectively, forming the left side of the single-lens group, and L14, L15, and L16 are a convex lens, a concave lens, and a convex lens, respectively, forming the right side of the single-lens group.

[0021] The left side has a concave L11S1 and a convex L11S2. L12S1 and L11S2 are coupled to form a concave surface, and L13S2 is a convex surface. The right side is symmetrical to the left side. The curvature radius relationship is: L11S1 > L13S2 > L11S2 = L12S1. L12S2 and L13S1 are concave, convex, or planar surfaces.

[0022] In the aforementioned high-resolution, wide-field-of-view medical endoscope optical path system, the eyepiece sequentially comprises a convex lens L29, a convex lens L30, and a concave lens L31 to form a convex-convex-concave junction. Furthermore, L29S1 is concave, L29S2 is convex, L30S1 is concave, L30S2 is convex, and L31S1 and L30S2 are coupled to form a concave surface, while L31S2 is convex.

[0023] In the aforementioned high-resolution, wide-field-of-view medical endoscope optical path system, the eyepiece located behind lens L31 also includes lens L32, and L32 is a planar protective lens.

[0024] The advantages of this invention are: the combination of objective lens, rod lens and eyepiece through this improved structure can improve the performance of various aspects of the endoscope optical path system, such as improving imaging clarity, expanding the field of view and improving resolution, thereby improving the imaging quality of the endoscope and making an outstanding contribution to improving the diagnostic level of the medical endoscopy industry. Attached Figure Description

[0025] Figure 1 This is a structural diagram of the combination of objective lens, rod lens, and eyepiece in the optical path system of the medical endoscope of the present invention;

[0026] Figure 2 This is a structural diagram of the objective lens of the present invention at a 0° viewing angle;

[0027] Figure 3 This is a structural diagram of the objective lens of the present invention at a 30° viewing angle;

[0028] Figure 4 This is a structural diagram of the rod mirror of the present invention;

[0029] Figure 5 This is a structural diagram of a single-lens group in a rod lens;

[0030] Figure 6 This is a structural diagram of the eyepiece of the present invention;

[0031] Figures 7-11 These are the parameters of each lens in this embodiment;

[0032] Figure 12 The graph shows the variation of the system modulation function with focus distance.

[0033] Figure 13 The graph shows the variation of the system modulation transfer function with line aspect.

[0034] Figure 14 For the system field curvature and distortion diagram;

[0035] Figure 15 This is a graph showing the variation of system chromatic aberration with image plane height.

[0036] Figure 16 This is a graph showing the variation of the system's relative illumination with the field of view. Detailed Implementation

[0037] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0038] like Figure 1 As shown, this embodiment discloses a high-resolution, wide-field-of-view medical endoscope optical path system, which includes an objective lens, a rod lens, and an eyepiece in sequence from the object side. Other structures that are consistent with the prior art without any improvements are not described here.

[0039] In particular, such as Figure 2 , Figure 3 As shown, the objective lens, from the object side, includes a plane protective lens L1, a lens L2 forming a light-gathering structure, lenses L3 and L4, lenses L5, L6, and L7 forming a convex-concave-convex objective lens focal length structure, lenses L8 and L9 forming a cemented lens group, and a lens L10 forming a rod lens field curvature correction structure.

[0040] In the following, S1 represents the side of the lens closest to the object, i.e., the left side, and S2 represents the side of the lens furthest from the object, i.e., the right side.

[0041] Specifically, the flat protective mirror L1 is protected by a flat sapphire crystal.

[0042] Lens L2 is a concave lens with selectable focal lengths [-10mm, -3mm]. The side closest to the object, L2S1, is convex, while the side closest to L3, L2S2, is concave. The radius of curvature of L2S1 is greater than that of L2S2; L2S1's radius of curvature can be approximately 6mm (e.g., 5mm-7mm), and L2S2's radius of curvature can be approximately 2mm (e.g., 1mm-3mm). The distance between L1 and L2 is 0-2mm (e.g., 0.5mm). The concave lens structure of L2 effectively gathers light to widen the field of view.

[0043] Lenses L3 and L4 can both be plane mirrors, which can compensate for subsequent optical path differences;

[0044] Lenses L3 and L4 can also be prisms, in which case L5 is also replaced by a prism. The three prisms L3, L4, and L5 form a turning prism with a convex lens structure, which, together with L6 and L7, forms a convex-concave-convex objective lens focal length structure.

[0045] Lenses L5, L6, and L7 are convex lenses, with selectable focal lengths of [3mm, 5mm], [-50mm, -10mm], and [4mm, 6mm], respectively. L5S1 is planar, L5S2 and L6S1 are both convex, L6S2 and L7S1 are both concave, and L7S2 is convex. This convex-concave-convex structure can correct spherical aberration of the objective lens, and the combination of L5, L6, and L7 forms a lens with a focal length of X (2.5mm-5.0mm), which is the main contributor to the focal length of the objective lens (within the range of 0.8-1.2 of X).

[0046] The relationship between the radii of curvature of L5, L6, and L7 is: L5S2 > L7S1 > L6S1 > L7S2 > L6S2.

[0047] The radius of curvature of L5S2 can be around 4mm, such as 3mm-5mm;

[0048] The radius of curvature of L7S1 can be around 3mm, such as 2mm-4mm;

[0049] The radius of curvature of L6S1 can be around 3mm, such as 2mm-4mm;

[0050] The radius of curvature of L7S2 can be around 2mm, such as 1mm-3mm;

[0051] The radius of curvature of L6S2 can be around 2mm, such as 1mm-3mm.

[0052] L8 and L9 use cemented lenses with high refractive index and low Abbe number, and low refractive index and high Abbe number, respectively. L8 is a concave lens and L9 is a convex lens. The focal lengths of the two can be selected as [-3mm, -1.5mm] and [3.5mm, 5mm], respectively. The cemented lens group can correct the chromatic aberration of the system and improve the image quality.

[0053] Specifically, L8S1 and L8S2 are both concave surfaces; and the radius of curvature of L8S2 is greater than that of L8S1; the radius of curvature of L8S1 can be around 1.5mm, such as 0.5mm-2.5mm; the radius of curvature of L8S2 can be around 210mm, such as 200mm-220mm. L9S1 and L9S2 are both convex surfaces; and the radius of curvature of L9S1 is greater than that of L9S2, and the radius of curvature of L9S1 is equal to that of L8S2 to couple L9S1 and L8S2; the radius of curvature of L9S2 can be around 2.5mm, such as 1.5mm-3.5mm.

[0054] Lens L10 is a convex lens with focal lengths of [8mm, 20mm]. L10S1 is convex, and L10S2 is concave. The radius of curvature of L10S2 is greater than that of L10S1. The radius of curvature of L10S1 can be around 6mm, such as 5mm-7mm; the radius of curvature of L10S2 can be around 34mm, such as 32mm-36mm. The concave structure of L10S2 can correct the field curvature caused by the rod lens, thereby improving image resolution and quality.

[0055] Specifically, such as Figure 4 , Figure 5 As shown, the rod endoscope comprises three sets of single-lens groups arranged sequentially, each with the same structure. Each set is symmetrical, with the left and right sides each containing a convex-concave-convex point diffusion function reduction structure composed of a convex lens, a concave lens, and another convex lens. Using three identical sets of symmetrical single-lens groups in the rod endoscope extends the overall working length of the endoscope system while reducing manufacturing costs and eliminating axial aberrations.

[0056] Specifically, each single-lens group includes lenses L11, L12, L13, L14, L15, and L16. L11, L12, and L13 are convex, concave, and convex lenses, respectively, forming the left side of the single-lens group. L14, L15, and L16 are convex, concave, and convex lenses, respectively, forming the right side of the single-lens group. On the left side, L11S1 is concave, L11S2 is convex, L12S1 is coupled with L11S2 to form a concave surface, and L13S2 is convex. L12S2 and L13S1 are unconstrained and can be concave, convex, or planar. The right side is symmetrical to L11S1. The radius of curvature relationship is: L11S1 > L13S2 > L11S2 = L12S1. The convex-concave-convex combination structure of the single lens group makes the entire single lens group appear as a positive lens, thereby achieving a smaller point spread function effect. At the same time, the concave surface of L11S1 ensures that the rod lens can transmit a larger image plane (half-image plane greater than 1.9mm) with a small light-transmitting aperture (diameter less than 6.5mm), while ensuring that the NA of the rod lens is above 0.17, which can effectively increase the angular resolution and imaging height of the endoscope system.

[0057] Specifically, the focal length of the L11 is [6mm, 15mm], such as 8.732419mm;

[0058] The radius of curvature of L11S1 can be 20mm-30mm, such as 24.123156mm; the radius of curvature of L11S2 can be 5mm-8mm, such as 6.769709mm.

[0059] The focal length of the L12 is [-3mm, -6mm], such as -4.29962mm;

[0060] The focal length of the L13 is [15mm, 25mm], such as 21.67066mm.

[0061] The radius of curvature of L12S1 is the same as that of L11S2; L13S1 is preferably coupled with L12S2, so their radii of curvature are the same; the radius of curvature of L13S2 can be 12mm-16mm, such as 14.913970mm.

[0062] Specifically, such as Figure 6As shown, the eyepiece includes lenses L29, L30, L31, and L32, with lens L32 being a planar protective lens. L29, L30, and L31 are a convex lens, a convex lens, and a concave lens, respectively, forming a convex-convex-concave structure. Specifically, L29S1 is concave with a radius of curvature of 7mm-9mm; L29S2 is convex with a radius of curvature of 4.5mm-6.5mm; L30S1 is concave with a radius of curvature of 76mm-79mm; L30S2 is convex with a radius of curvature of 8mm-12mm; L31S1 and L30S2 are coupled to form a concave surface with a radius of curvature of 8mm-12mm; and L31S2 is convex with a radius of curvature of 21mm-25mm. The eyepieces L29-L30 have a convex-concave structure, and L29S1 is concave. This helps to adjust the field curvature of the system in conjunction with the rod lens, relieving pressure on the rod lens. At the same time, it ensures that the object-side focal length of the eyepiece is less than 16.3mm and the object-side NA is above 0.17. This ensures that when the system is used with the F22 adapter, the half-image height is above 2.7mm, and the overall system F# is below 7.87, thus ensuring an angular resolution of 13.3C / (°) or higher.

[0063] In this embodiment, the relative position and spacing of the lenses are ensured by spacers (hollow), and then the lenses are fixed to the tube wall with glue. If it is a cemented lens, there is no need for spacers, and they are directly fixed to each other with glue, and then the cemented lens is fixed to the tube wall with glue.

[0064] This embodiment uses Figures 7-11 Taking the parameters as an example, Figure 7 Mainly objective lens parameters, Figure 8 , Figure 9 Mainly rod lens parameters, Figure 10 The main parameters are those of the eyepiece. The second column in the diagram represents the lens number; L1_1 represents the S1 surface of the first lens, and L2_2 represents the S2 surface of the second lens.

[0065] The third column indicates the surface type, with Sphere indicating a spherical surface type. All surfaces in this system are spherical.

[0066] The fourth column represents the radius of curvature. "infinity" means the radius of curvature is infinite (in a plane); "6.096252" means the radius of curvature is 6.096252 mm with the center on the right; "-4.252331" means the radius of curvature is 4.252331 mm with the center on the left.

[0067] The fifth column indicates the distance from the next surface, in mm; the sixth column indicates the lens material.

[0068] The seventh column represents refraction; the eighth column represents the effective aperture, in mm.

[0069] Figure 11 The focal length of each lens is given. Since the three groups of single lenses in a rod lens have the same structure and each group is symmetrical, the above structure only describes the left side of the first group of single lenses. The right side of the first group and the other two groups will not be described in detail.

[0070] Figures 12-16 The above structure was designed using Code V design software. Figures 7-11 The performance parameters obtained are as follows: Figure 12 This is a graph showing the system modulation function as a function of focal distance, representing the change in lens resolution near the optimal image plane with distance at a system resolution of 60 lines parallel per millimeter. Figure 13 It is a graph showing the variation of the system modulation transfer function with line aspect, representing the change of the system's resolution with line aspect. Figure 14 For the system field curvature and distortion diagram; Figure 15 This is a graph showing the variation of system chromatic aberration with image plane height. Figure 16 This is a graph showing the relative illumination of the system as a function of the field of view. As can be seen from the aforementioned performance graphs, the endoscope implemented using this structure can achieve a high resolution and a large field of view.

[0071] In addition, the design simulation of this scheme also yielded a series of parameters for the endoscope system implemented with the above structure and parameters: F-number (FNO) is 7.87, magnification (RED) is 0.0940, optical working distance (OBJ DIS) is 40mm and entrance pupil distance (ENTRANCE PUPIL) is 2.8690mm.

[0072] The reciprocal of the limiting angle of resolution of the minimum resolvable equidistant fringe width at a given optical working distance, expressed in circles / degrees [C / (°)], is calculated using the formula (1).

[0073]

[0074] In the formula:

[0075] r a (d) indicates angular resolution.

[0076] r(d) represents the limit of distinguishable line pairs per millimeter, expressed in line pairs per millimeter (lp / mm).

[0077] 'a' represents the distance from the tip of the endoscope to the pupil, in millimeters (mm).

[0078] d represents the optical working distance, in millimeters (mm).

[0079] The system's F-number (FNO) is 7.87. According to the diffraction limit formula d = 1.22λ * F, where d is the minimum image-side resolution, λ is the wavelength, and F is the F-number; the wavelength of the light in the system is 550 nm, and F = 7.87 yields a minimum image-side resolution of 5.28 μm. The magnification (RED) is 0.0940; that is, the minimum object-side resolution is 56.17 μm; therefore, the object-side resolution (r(d)) is 17.803 lp / mm. Then, combining the optical working distance (OBJ DIS) of 40 mm and the entrance pupil distance (ENTRANCE PUPIL) of 2.8690 mm, i.e., the aforementioned d and a, we can calculate that the maximum angular resolution reaches 13.3 C / (°).

[0080] The combination of objective lens, rod lens, and eyepiece in this solution can improve the imaging clarity and field of view of the endoscope, thereby effectively improving the diagnostic level of the medical endoscopy industry.

[0081] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

[0082] Although this document uses terms such as objective lens, eyepiece, rod lens, single lens group, and lens element frequently, the possibility of using other terms is not excluded. These terms are used merely for the convenience of describing and explaining the essence of this invention; interpreting them as any additional limitation would contradict the spirit of this invention.

Claims

1. A high-resolution, wide-field-of-view medical endoscope optical path system, comprising, from the object side, an objective lens, a rod lens, and an eyepiece, characterized in that, The objective lens, from the object side, includes a light-gathering structure and a convex-concave-convex objective lens focal length structure consisting of a convex lens, a concave lens, and a convex lens in sequence. The light-gathering structure includes a concave lens L2. The concave lens L2 has a convex surface L2S1 near the object side and a concave surface L2S2 near the focal length structure of the convex-concave-convex objective lens. The radius of curvature of L2S1 is greater than that of L2S2. The convex-concave-convex objective lens focal length structure includes a convex lens L5, a concave lens L6, and a convex lens L7, wherein L5S1 is planar, L5S2 and L6S1 are both convex, L6S2 and L7S1 are both concave, and L7S2 is convex; the absolute value relationship of the radius of curvature is: L5S2>L7S1>L6S1>L7S2>L6S2; The objective lens is located on the side of the convex-concave objective lens focal length structure near the bar lens and also includes a cemented lens group and a bar lens field curvature correction structure. The cemented lens assembly includes L8 and L9; L8 is a concave lens where both L8S1 and L8S2 are concave surfaces; L9 is a convex lens where both L9S1 and L9S2 are convex surfaces. The rod lens field curvature correction structure includes a convex lens L10, with L10S1 being convex and L10S2 being concave. S1 represents the side of the lens closest to the object, and S2 represents the side of the lens furthest from the object. The rod lens includes multiple sets of single lens groups arranged in sequence, and each set of single lens groups is symmetrical from left to right. The left and right parts respectively include a convex-concave-convex dot diffusion function reduction structure composed of a convex lens, a concave lens, and a convex lens in sequence. The eyepiece comprises a convex lens, a convex lens, and a concave lens in sequence to form a convex-convex-concave structure; The eyepiece comprises a convex lens L29, a convex lens L30, and a concave lens L31 in sequence to form a convex-convex-concave structure. L29S1 is concave, L29S2 is convex, L30S1 is concave, L30S2 is convex, L31S1 and L30S2 are coupled to form a concave surface, and L31S2 is convex.

2. The high-resolution, wide-field-of-view medical endoscope optical path system according to claim 1, characterized in that, The objective lens, located between the light-gathering structure and the convex-concave-convex objective lens focal length structure, also includes lenses L3 and L4; Both lenses L3 and L4 are plane mirrors.

3. The high-resolution, wide-field-of-view medical endoscope optical path system according to claim 1, characterized in that, The objective lens also includes a planar protective mirror L1 located on the object side of the concave lens L2.

4. The high-resolution, wide-field-of-view medical endoscope optical path system according to any one of claims 1-3, characterized in that, The rod lens comprises three sets of single lenses arranged sequentially; Each single lens group includes lenses L11, L12, L13, L14, L15, and L16. L11, L12, and L13 are convex, concave, and convex lenses, respectively, forming the left side of the single lens group. L14, L15, and L16 are convex, concave, and convex lenses, respectively, forming the right side of the single lens group. Furthermore, L11S1 on the left side is concave, L11S2 is convex, L12S1 and L11S2 are coupled to form a concave surface, L13S2 is convex, and L12S2 and L13S1 are concave, convex, or planar surfaces. The right side is symmetrical to the left side.

5. The high-resolution, wide-field-of-view medical endoscope optical path system according to claim 1, characterized in that, The eyepiece located to the right of lens L31 also includes lens L32, and L32 is a planar protective lens.

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