Medical endoscope lens

Abstract

The present invention discloses a medical endoscope lens, comprising a first lens, a second lens, an aperture and a third lens arranged in sequence along an optical axis from the object side to the image side, the first lens to the third lens each comprising an object side surface facing the object side and allowing imaging light to pass through and an image side surface facing the image side and allowing imaging light to pass through, the first lens has positive refractive power, and the object side surface of the first lens is concave, and the image side surface is convex, the second lens has negative refractive power, and the object side surface of the second lens is convex, and the image side surface is concave, the third lens has positive refractive power, and the object side surface of the third lens is convex, and the image side surface is convex. The medical endoscope lens of the present invention is small in size and easy to use, and at the same time has good color reproduction, small distortion, high resolution, good imaging quality, and has a large magnification, and can also clearly observe some smaller lesion areas.

Description

Technical Field

[0001] The present invention relates to the technical field of optical lenses, and more particularly, to a medical endoscope lens. Background Art

[0002] Medical endoscopes are invasive examination tools. With the increasing trend of miniaturization of medical wounds, the requirements for endoscopes have shifted to small size while maintaining high-definition imaging. However, existing general endoscopes generally have the problem of being too large in size, and at the same time, they have a small designed focal length and a small magnification ratio, making it impossible to clearly observe some small lesion areas.

[0003] In view of this, the inventors of the present application have invented a medical endoscope lens. Summary of the Invention

[0004] The purpose of the present invention is to provide a medical endoscope lens with a small size, a large magnification ratio, and clear imaging.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions: A medical endoscope lens includes a first lens, a second lens, a diaphragm, and a third lens sequentially arranged along an optical axis from the object side to the image side. Each of the first lens to the third lens includes an object side facing the object side and allowing imaging light to pass through, and an image side facing the image side and allowing imaging light to pass through.

[0006] The first lens has a positive refractive power, and the object side of the first lens is concave, and the image side is convex.

[0007] The second lens has a negative refractive power, and the object side of the second lens is convex, and the image side is concave.

[0008] The third lens has a positive refractive power, and the object side of the third lens is convex, and the image side is convex.

[0009] Further, the first lens, the second lens, and the third lens are all plastic aspherical lenses, and the object sides and image sides of the first lens, the second lens, and the third lens are all aspherical surfaces.

[0010] Further, the lens satisfies: 45 < vd1 < 60, 20 < vd2 < 30, 45 < vd3 < 60, where vd1, vd2, and vd3 are the dispersion coefficients of the first lens, the second lens, and the third lens, respectively.

[0011] Further, the lens satisfies: 1.5 < nd1 < 1.6, 1.6 < nd2 < 1.7, 1.5 < nd3 < 1.6, where nd1, nd2, and nd3 are the refractive indices of the first lens, the second lens, and the third lens, respectively.

[0012] Furthermore, the effective apertures of the first lens, the second lens and the third lens are all less than 2.3 mm.

[0013] Furthermore, the total optical length TTL of the lens is less than 4.5 mm.

[0014] Furthermore, the focal length of the lens is f=2.7 mm.

[0015] Furthermore, the light transmission of the lens is F / #=2.8.

[0016] After adopting the above technical solution, the present invention has the following advantages:

[0017] The medical endoscope lens of the present invention is small in size and convenient to use, and has good color reproduction, small distortion, high resolution, good imaging quality, and a large magnification, so that some smaller lesion areas can be clearly observed. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a lens structure diagram of Embodiment 1 of the present invention;

[0019] Figure 2 This is a light path diagram of Embodiment 1 of the present invention;

[0020] Figure 3 is an MTF curve diagram of the lens under visible light in Example 1 of the present invention;

[0021] Figure 4 Graph showing field curvature and distortion of the lens under visible light in Embodiment 1 of the present invention;

[0022] Figure 5 is an illumination curve diagram of the lens under visible light in Example 1 of the present invention;

[0023] Figure 6 is a magnification chromatic aberration curve of the lens under visible light in Example 1 of the present invention;

[0024] Figure 7 is a lens structure diagram of embodiment 2 of the present invention;

[0025] Figure 8 This is a light path diagram of Embodiment 2 of the present invention;

[0026] Fig. 9 is an MTF curve diagram of the lens under visible light in Example 2 of the present invention;

[0027] Fig.10 Graph showing field curvature and distortion of the lens under visible light in Embodiment 2 of the present invention;

[0028] Fig.11 is an illumination curve diagram of the lens under visible light in Example 2 of the present invention;

[0029] Fig.12 is a magnification chromatic aberration curve of the lens under visible light in Example 2 of the present invention;

[0030] Fig.13 is a lens structure diagram of embodiment 3 of the present invention;

[0031] Fig.14 This is a light path diagram of Embodiment 3 of the present invention;

[0032] Fig.15 is an MTF curve diagram of the lens under visible light in Example 3 of the present invention;

[0033] Fig.16 Graph showing field curvature and distortion of the lens under visible light in Embodiment 3 of the present invention;

[0034] Fig.17 is an illumination curve diagram of the lens under visible light in Example 3 of the present invention;

[0035] Fig.18 is a magnification chromatic aberration curve of the lens under visible light in Example 3 of the present invention;

[0036] Fig.19 is a lens structure diagram of embodiment 4 of the present invention;

[0037] Fig. 20 This is a light path diagram of Embodiment 4 of the present invention;

[0038] Fig.21 is an MTF curve diagram of the lens under visible light in Example 4 of the present invention;

[0039] Fig. 22 Graph showing field curvature and distortion of the lens under visible light in Embodiment 4 of the present invention;

[0040] Fig.23 is an illumination curve diagram of the lens under visible light in Example 4 of the present invention;

[0041] Fig.24 4 is a graph showing the magnification chromatic aberration of the lens under visible light in Example 4 of the present invention.

[0042] Description of reference numerals:

[0043] 1. First lens; 2. Second lens; 3. Third lens; 4. Aperture; 5. Protective glass & filter. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0045] It should be noted that in the present invention, the terms "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element of the present invention must have a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0046] Here, "a lens having a positive refractive power (or a negative refractive power)" means that the paraxial refractive power of the lens calculated by Gaussian optical theory is positive (or negative). The "object side (or image side) of the lens" is defined as a specific range of the lens surface through which the imaging light passes. The concave and convexity of the lens surface can be judged according to the judgment method of ordinary knowledgeable people in this field, that is, the concave and convexity of the lens surface can be judged by the positive and negative signs of the radius of curvature (abbreviated as R value). R value can be commonly used in optical design software, such as Zemax or CodeV. R value is also commonly found in the lens data sheet of optical design software. For the object side, when the R value is positive, the object side is judged to be convex; when the R value is negative, the object side is judged to be concave. Conversely, for the image side, when the R value is positive, the image side is judged to be concave; when the R value is negative, the image side is judged to be convex.

[0047] The present invention discloses a medical endoscope lens, comprising a first lens 1, a second lens 2, an aperture 4 and a third lens 3 arranged in sequence along an optical axis from an object side to an image side, wherein the first lens 1 to the third lens 3 each include an object side surface facing the object side and allowing imaging light to pass through, and an image side surface facing the image side and allowing imaging light to pass through;

[0048] The first lens 1 has positive refractive power, and the object side surface of the first lens 1 is concave, and the image side surface is convex;

[0049] The second lens 2 has a negative refractive power, and the object side surface of the second lens 2 is a convex surface, and the image side surface is a concave surface;

[0050] The third lens element 3 has positive refractive power, and the object side surface and the image side surface of the third lens element 3 are convex.

[0051] Among them, the first lens 1, the second lens 2 and the third lens 3 are all plastic even-order aspheric lenses, and the object side and image side of the first lens 1, the second lens 2 and the third lens 3 are all aspheric, that is, the object side and image side of the first lens 1, the object side and image side of the second lens 2, and the object side and image side of the third lens 3 are all aspheric. The comprehensive lens focal length and concave-convex surface design can effectively reduce the lens cost, shorten the lens length and maintain system performance. By increasing the order of the even-order aspheric surface, the use efficiency of each lens is improved, thereby reducing the number of lenses used, effectively reducing the size of the lens, and achieving better imaging effects.

[0052] The aperture 4 is arranged between the second lens 2 and the third lens 3. By adjusting the distance between the lens and the aperture 4, astigmatism can be corrected, and in particular, coma, distortion and vertical axis aberration can be well corrected.

[0053] This lens meets: 45 <vd1<60,20<vd2<30,45<vd3<60,1.5<nd1<1.6,1.6<nd2<1.7,1.5<nd3<1.6,

[0054] Among them, vd1, vd2, and vd3 are the dispersion coefficients of the first lens 1, the second lens 2, and the third lens 3, respectively, and nd1, nd2, and nd3 are the refractive indices of the first lens 1, the second lens 2, and the third lens 3, respectively. By designing and using a positive power lens (the first lens 1 and the third lens 3) made of a high dispersion coefficient material and a negative power lens (the second lens 2) made of a low dispersion coefficient material, the chromatic aberration of the system can be effectively corrected to ensure the imaging quality.

[0055] The effective apertures of the first lens 1 , the second lens 2 and the third lens 3 are all less than 2.3 mm, and the total optical length TTL of the lens is less than 4.5 mm, so the size of the lens is small.

[0056] The focal length of the lens is f=2.7 mm, so the lens has a larger magnification, which ensures that even some smaller lesion areas can be clearly observed when used.

[0057] The lens has a light transmission of F / #=2.8, and is designed to take into account both low-light imaging and large depth of field requirements, meeting the requirements for use in medical endoscopes.

[0058] The full field of view of this lens is greater than 0.3 at the MTF200lp / mm frequency, and the lens has high resolution and good imaging quality.

[0059] The optical distortion of this lens is less than 5%, and the distortion is small, so the image will not be affected by excessive distortion.

[0060] The mini infrared imaging lens of the present invention will be described in detail below with reference to specific embodiments.

[0061] Example 1

[0062] Reference Figure 1 , Figure 2 As shown, the present invention discloses a medical endoscope lens, comprising a first lens 1, a second lens 2, an aperture 4 and a third lens 3 arranged in sequence along an optical axis from the object side to the image side, wherein the first lens 1 to the third lens 3 each include an object side surface facing the object side and allowing imaging light to pass through, and an image side surface facing the image side and allowing imaging light to pass through;

[0063] The first lens 1 has positive refractive power, and the object side surface of the first lens 1 is concave, and the image side surface is convex;

[0064] The second lens 2 has a negative refractive power, and the object side surface of the second lens 2 is a convex surface, and the image side surface is a concave surface;

[0065] The third lens element 3 has positive refractive power, and the object side surface and the image side surface of the third lens element 3 are convex.

[0066] The detailed optical data of this specific embodiment are shown in Table 1-1.

[0067] Table 1-1 Detailed optical data of Example 1

[0068]

[0069]

[0070] In this embodiment, the first lens 1, the second lens 2 and the third lens 3 are all plastic even-order aspheric lenses, and the object side surface and the image side surface of the first lens 1, the second lens 2 and the third lens 3 are all aspheric. The equation of the aspheric lens surface curve is expressed as follows:

[0071]

[0072] in,

[0073] z: Depth of the aspherical surface (the vertical distance between the point on the aspherical surface that is y away from the optical axis and the tangent plane that is tangent to the vertex on the optical axis of the aspherical surface);

[0074] c: the vertex curvature of the aspherical surface;

[0075] K: Conic Constant;

[0076] radial distance;

[0077] r n : normalization radius (NRADIUS);

[0078] u:r / r n ;

[0079] a m : mth order Q con Coefficient (is the m th Q con coefficient);

[0080] Q m con : mth order Q con Polynomial th Q con polynomial).

[0081] The aspheric surface data in this embodiment are shown in Table 1-2.

[0082] Table 1-2 Aspheric surface data of Example 1

[0083]

[0084] In this embodiment, please refer to the MTF curve of the lens under visible light. Figure 3 As can be seen from the figure, when the spatial frequency of this lens reaches 200lp / mm, the MTF value is greater than 0.3, the imaging quality is excellent, and the resolution of the lens is high. For the field curvature and distortion diagram of the lens under visible light, please refer to Figure 4 As can be seen from the figure, the field curvature curves of each wavelength basically overlap, and the lens chromatic aberration correction is good; at the same time, the optical distortion of the system is <+5%, and the distortion is small, which ensures the imaging quality, and the imaging picture will not be affected by excessive distortion. For the illumination curve of the lens under visible light, please refer to Figure 5 As can be seen from the figure, the imaging illumination is greater than >58%. For the magnification chromatic aberration curve of the lens under visible light, please refer to Figure 6 As can be seen from the figure, the lens magnification chromatic aberration correction is relatively good, less than 1um, within the diffraction limit range, the chromatic aberration is small, and the image color reproduction is high.

[0085] Example 2

[0086] like Figure 7 , Figure 8 As shown, the present embodiment is different from the embodiment 1 mainly in that the optical parameters such as the curvature radius of each lens surface and the lens thickness are different.

[0087] The detailed optical data of this specific embodiment are shown in Table 2-1.

[0088] Table 2-1 Detailed optical data of Example 2

[0089]

[0090] In this embodiment, the first lens 1, the second lens 2 and the third lens 3 are all plastic even-order aspheric lenses, and the object side surface and the image side surface of the first lens 1, the second lens 2 and the third lens 3 are all aspheric. The aspheric surface data in this embodiment are shown in Table 2-2.

[0091] Table 2-2 Aspheric surface data of Example 2

[0092]

[0093]

[0094] In this embodiment, please refer to the MTF curve of the lens under visible light. Fig. 9 As can be seen from the figure, when the spatial frequency of this lens reaches 200lp / mm, the MTF value is greater than 0.3, the imaging quality is excellent, and the resolution of the lens is high. For the field curvature and distortion diagram of the lens under visible light, please refer to Fig.10 As can be seen from the figure, the field curvature curves of each wavelength basically overlap, and the lens chromatic aberration correction is good; at the same time, the optical distortion of the system is <+4%, and the distortion is small, which ensures the imaging quality, and the imaging picture will not be affected by excessive distortion. For the illumination curve of the lens under visible light, please refer to Fig.11 As can be seen from the figure, the imaging illumination is greater than >58%. For the magnification chromatic aberration curve of the lens under visible light, please refer to Fig.12 As can be seen from the figure, the lens magnification chromatic aberration correction is relatively good, less than 1um, within the diffraction limit range, the chromatic aberration is small, and the image color reproduction is high.

[0095] Example 3

[0096] like Fig.13 , Fig.14 As shown, the present embodiment is different from the embodiment 1 mainly in that the optical parameters such as the curvature radius of each lens surface and the lens thickness are different.

[0097] The detailed optical data of this specific embodiment are shown in Table 3-1.

[0098] Table 3-1 Detailed optical data of Example 3

[0099]

[0100] In this embodiment, the first lens 1, the second lens 2 and the third lens 3 are all plastic even-order aspheric lenses, and the object side surface and the image side surface of the first lens 1, the second lens 2 and the third lens 3 are all aspheric. The aspheric surface data in this embodiment are shown in Table 3-2.

[0101] Table 3-2 Aspheric surface data of Example 3

[0102]

[0103] In this embodiment, please refer to the MTF curve of the lens under visible light. Fig.15 As can be seen from the figure, when the spatial frequency of this lens reaches 200lp / mm, the MTF value is greater than 0.3, the imaging quality is excellent, and the resolution of the lens is high. For the field curvature and distortion diagram of the lens under visible light, please refer to Fig.16 As can be seen from the figure, the field curvature curves of each wavelength basically overlap, and the lens chromatic aberration correction is good; at the same time, the optical distortion of the system is <4%, and the distortion is small, which ensures the imaging quality, and the imaging picture will not be affected by excessive distortion. Please refer to the illumination curve of the lens under visible light Fig.17 As can be seen from the figure, the imaging illumination is greater than >58%. For the magnification chromatic aberration curve of the lens under visible light, please refer to Fig.18 As can be seen from the figure, the lens magnification chromatic aberration correction is relatively good, less than 1um, within the diffraction limit range, the chromatic aberration is small, and the image color reproduction is high.

[0104] Example 4

[0105] like Fig.19 , Fig. 20 As shown, the present embodiment is different from the embodiment 1 mainly in that the optical parameters such as the curvature radius of each lens surface and the lens thickness are different.

[0106] The detailed optical data of this specific embodiment are shown in Table 4-1.

[0107] Table 4-1 Detailed optical data of Example 4

[0108]

[0109] In this embodiment, the first lens 1, the second lens 2 and the third lens 3 are all plastic even-order aspheric lenses, and the object side surface and the image side surface of the first lens 1, the second lens 2 and the third lens 3 are all aspheric. The aspheric surface data in this embodiment are shown in Table 4-2.

[0110] Table 4-2 Aspheric surface data of Example 4

[0111]

[0112] In this embodiment, please refer to the MTF curve of the lens under visible light. Fig.21 As can be seen from the figure, when the spatial frequency of this lens reaches 200lp / mm, the MTF value is greater than 0.3, the imaging quality is excellent, and the resolution of the lens is high. For the field curvature and distortion diagram of the lens under visible light, please refer to Fig. 22 As can be seen from the figure, the field curvature curves of each wavelength basically overlap, and the lens chromatic aberration correction is good; at the same time, the optical distortion of the system is <+2%, and the distortion is small, which ensures the imaging quality, and the imaging picture will not be affected by excessive distortion. For the illumination curve of the lens under visible light, please refer to Fig.23 As can be seen from the figure, the imaging illumination is greater than >58%. For the magnification chromatic aberration curve of the lens under visible light, please refer to Fig.24 As can be seen from the figure, the lens magnification chromatic aberration correction is relatively good, less than 1um, within the diffraction limit range, the chromatic aberration is small, and the image color reproduction is high.

[0113] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A medical endoscope lens, characterized in that: It includes a first lens, a second lens, a diaphragm, a third lens, and a protective glass that are sequentially arranged along an optical axis from the object side to the image side. Each of the first lens to the third lens includes an object side surface facing the object side and allowing imaging light to pass through, and an image side surface facing the image side and allowing imaging light to pass through. The components with optical refractive power in the lens are only the above-mentioned three lenses. The first lens has a positive refractive power, the object side surface of the first lens is concave, and the image side surface is convex. The second lens has a negative refractive power, the object side surface of the second lens is convex, and the image side surface is concave. The third lens has a positive refractive power, the object side surface of the third lens is convex, and the image side surface is convex. The focal length f of the lens is 2.7 mm.

2. A medical endoscope lens as claimed in claim 1, characterized in that: The first lens, the second lens, and the third lens are all plastic aspherical lenses, and the object side surfaces and the image side surfaces of the first lens, the second lens, and the third lens are all aspherical surfaces.

3. A medical endoscope lens as claimed in claim 1, characterized in that: This lens satisfies: 45 < vd1 < 60, 20 < vd2 < 30, 45 < vd3 < 60, where vd1, vd2, and vd3 are the dispersion coefficients of the first lens, the second lens, and the third lens respectively.

4. A medical endoscope lens as claimed in claim 1, characterized in that: This lens satisfies: 1.5 < nd1 < 1.6, 1.6 < nd2 < 1.7, 1.5 < nd3 < 1.6, where nd1, nd2, and nd3 are the refractive indices of the first lens, the second lens, and the third lens respectively.

5. The medical endoscope lens as claimed in claim 1, characterized in that: The effective apertures of the first lens, the second lens, and the third lens are all less than 2.3 mm.

6. The medical endoscope lens as claimed in claim 1, characterized in that: The overall optical length TTL of this lens is 4.502 mm, or TTL = 4.513 mm, or TTL = 4.509 mm.

7. The medical endoscope lens according to claim 1, characterized in that: The F-number of this lens is 2.8.

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