CN216454904U

CN216454904U - Medical endoscope lens

Info

Publication number: CN216454904U
Application number: CN202123154071.1U
Authority: CN
Inventors: 范智宇; 张荣曜; 李坤泓; 施纯乾
Original assignee: Xiamen Leading Optics Co Ltd
Current assignee: Xiamen Leading Optics Co Ltd
Priority date: 2021-12-15
Filing date: 2021-12-15
Publication date: 2022-05-10
Anticipated expiration: 2031-12-15

Abstract

The utility model discloses a medical endoscope camera lens, include first lens, second lens, diaphragm and the third lens that set gradually along an optical axis from the thing side to picture side, first lens to third lens include one orientation thing side and make the image side that imaging light passes through and one orientation picture side and make imaging light pass through separately, first lens utensil positive diopter, and the thing side of first lens is the concave surface, and the image side is the convex surface, second lens utensil negative diopter, and the thing side of second lens is the convex surface, and the image side is the concave surface, third lens utensil positive diopter, and the thing side of third lens is the convex surface, and the image side is the convex surface. The utility model discloses medical endoscope head is small convenient to use, and its color reductibility is good simultaneously, the distortion is little, the resolution ratio is high, and the imaging quality is good, and its great magnification that possesses, also can clearly survey some less pathological change regions.

Description

Medical endoscope lens

Technical Field

The utility model relates to an optical lens technical field particularly, relates to a medical endoscope camera lens.

Background

Medical endoscopes are one type of invasive examination tool. With the trend of increasingly miniaturization of medical wounds, the requirement for the endoscope is changed to be small, and meanwhile high-definition imaging is kept.

In view of the above, the inventor of the present application invented a medical endoscope lens.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a medical endoscope camera lens that small, magnification is big, the formation of image is clear.

In order to achieve the above purpose, the utility model adopts the following technical scheme: a medical endoscope lens comprises a first lens, a second lens, a diaphragm and a third lens which are sequentially arranged along an optical axis from an object side to an image side, wherein the first lens to the third lens respectively comprise an object side surface facing the object side and allowing imaging light rays to pass and an image side surface facing the image side and allowing the imaging light rays to pass;

the first lens has positive diopter, the object side surface of the first lens is a concave surface, and the image side surface of the first lens is a convex surface;

the second lens has negative diopter, and the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface;

the third lens has positive diopter, and the object side surface of the third lens is a convex surface, and the image side surface of the third lens is a convex surface.

Furthermore, the first lens element, the second lens element and the third lens element are all plastic aspheric lens elements, and the object-side surface and the image-side surface of the first lens element, the second lens element and the third lens element are aspheric.

Further, the lens satisfies: 45< vd1<60, 20< vd2<30, and 45< vd3<60, wherein vd1, vd2, and vd3 are the abbe numbers of the first lens, the second lens, and the third lens, respectively.

Further, the lens satisfies: 1.5< nd1<1.6, 1.6< nd2<1.7, 1.5< nd3<1.6, wherein nd1, nd2 and nd3 are refractive indexes of the first lens, the second lens and the third lens respectively.

Further, the effective apertures of the first lens, the second lens and the third lens are all smaller than 2.3 mm.

Further, the total optical length TTL of the lens is less than 4.5 mm.

Further, the focal length f of the lens is 2.7 mm.

Further, the light transmittance F/#ofthe lens is 2.8.

After the technical scheme is adopted, the utility model has the advantages of as follows:

the utility model discloses medical endoscope head is small convenient to use, and its color reductibility is good simultaneously, the distortion is little, the resolution ratio is high, and the imaging quality is good, and its great magnification that possesses, also can clearly survey some less pathological change regions.

Drawings

Fig. 1 is a lens structure diagram according to embodiment 1 of the present invention;

fig. 2 is a light path diagram of embodiment 1 of the present invention;

fig. 3 is a graph of MTF curve of the lens in the visible light in embodiment 1 of the present invention;

fig. 4 is a graph of curvature of field and distortion of the lens in the embodiment 1 of the present invention under visible light;

fig. 5 is a graph of illuminance curve of the lens in the visible light according to embodiment 1 of the present invention;

fig. 6 is a graph of the magnification chromatic aberration of the lens in the visible light in embodiment 1 of the present invention;

fig. 7 is a lens structure diagram according to embodiment 2 of the present invention;

fig. 8 is a light path diagram of embodiment 2 of the present invention;

fig. 9 is a graph of MTF curve of the lens in the visible light according to embodiment 2 of the present invention;

fig. 10 is a graph of curvature of field and distortion of the lens in embodiment 2 of the present invention under visible light;

fig. 11 is a graph of illuminance under visible light for a lens in embodiment 2 of the present invention;

fig. 12 is a graph of the magnification chromatic aberration of the lens in the visible light in embodiment 2 of the present invention;

fig. 13 is a lens structure view according to embodiment 3 of the present invention;

fig. 14 is a light path diagram according to embodiment 3 of the present invention;

fig. 15 is a graph of MTF curve of the lens in the visible light according to embodiment 3 of the present invention;

fig. 16 is a graph of curvature of field and distortion of the lens in the visible light according to embodiment 3 of the present invention;

fig. 17 is a graph showing an illuminance curve of the lens in the visible light according to embodiment 3 of the present invention;

fig. 18 is a graph of the magnification chromatic aberration under visible light for the lens in embodiment 3 of the present invention;

fig. 19 is a lens structure view according to embodiment 4 of the present invention;

fig. 20 is a light path diagram according to embodiment 4 of the present invention;

fig. 21 is a graph of MTF curve of the lens in the visible light according to embodiment 4 of the present invention;

fig. 22 is a graph of curvature of field and distortion of the lens in the visible light according to embodiment 4 of the present invention;

fig. 23 is a graph of illuminance under visible light for a lens in embodiment 4 of the present invention;

fig. 24 is a graph of the magnification chromatic aberration of the lens in the visible light according to embodiment 4 of the present invention.

Description of reference numerals:

1. a first lens; 2. a second lens; 3. a third lens; 4. a diaphragm; 5. protective glass & filter.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

In the present invention, it should be noted that the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are all based on the orientation or position relationship shown in the drawings, and are only for convenience of description and simplification of the present invention, but do not indicate or imply that the device or element of the present invention must have a specific orientation, and thus, should not be construed as limiting the present invention.

As used herein, the term "a lens element having a positive refractive index (or a negative refractive index)" means that the paraxial refractive index of the lens element calculated by Gaussian optics is positive (or negative). The term "object-side (or image-side) of a lens" is defined as the specific range of imaging light rays passing through the lens surface. The determination of the surface shape of the lens can be performed by the judgment method of a person skilled in the art, i.e., by the sign of the curvature radius (abbreviated as R value). The R value may be commonly used in optical design software, such as Zemax or CodeV. The R value is also commonly found in lens data sheets (lens data sheets) of optical design software. When the R value is positive, the object side is judged to be a convex surface; and when the R value is negative, judging that the object side surface is a concave surface. On the contrary, regarding the image side surface, when the R value is positive, the image side surface is judged to be a concave surface; when the R value is negative, the image side surface is judged to be convex.

The utility model discloses a medical endoscope lens, which comprises a first lens 1, a second lens 2, a diaphragm 4 and a third lens 3 which are arranged in sequence from an object side to an image side along an optical axis, wherein the first lens 1 to the third lens 3 respectively comprise an object side face which faces the object side and enables imaging light to pass and an image side face which faces the image side and enables the imaging light to pass;

the first lens 1 has positive diopter, and the object side surface of the first lens 1 is a concave surface, and the image side surface is a convex surface;

the second lens element 2 has negative diopter, and the object-side surface of the second lens element 2 is a convex surface and the image-side surface is a concave surface;

the third lens element 3 has a positive refractive power, and the object-side surface of the third lens element 3 is a convex surface and the image-side surface is a convex surface.

The first lens element 1, the second lens element 2, and the third lens element 3 are plastic even-order aspheric lens elements, and the object-side surface and the image-side surface of the first lens element 1, the second lens element 2, and the third lens element 3 are aspheric surfaces, that is, the object-side surface and the image-side surface of the first lens element 1, the object-side surface and the image-side surface of the second lens element 2, and the object-side surface and the image-side surface of the third lens element 3 are aspheric surfaces. By combining the focal power and the concave-convex surface design of the lens, the cost of the lens can be effectively reduced, the length of the lens can be shortened, and the system performance can be maintained. The use efficiency of each lens is improved by increasing the order of the even aspheric surface, so that the use number of the lenses can be reduced, the size of the lens is effectively reduced, and a better imaging effect is achieved.

Wherein, the diaphragm 4 is arranged between the second lens 2 and the third lens 3, and astigmatism can be corrected by adjusting the distance between the lens and the diaphragm 4, and particularly coma aberration, distortion and vertical axis aberration can be corrected well.

The lens satisfies: 45< vd1<60, 20< vd2<30, 45< vd3<60, 1.5< nd1<1.6, 1.6< nd2<1.7, 1.5< nd3<1.6,

wherein vd1, vd2 and vd3 are respectively the dispersion coefficients of the first lens 1, the second lens 2 and the third lens 3, and nd1, nd2 and nd3 are respectively the refractive indexes of the first lens 1, the second lens 2 and the third lens 3. By the matched design and use of the positive focal power lens (the first lens 1 and the third lens 3) made of high-dispersion coefficient materials and the negative focal power lens (the second lens 2) made of low-dispersion coefficient materials, the chromatic aberration of the system can be effectively corrected, and the imaging quality is ensured.

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

The focal length f of the lens is 2.7mm, so that the lens has larger magnification, and the lens can ensure that some smaller lesion areas can be clearly observed in use.

The light transmission F/#ofthe lens is 2.8, the design of low-illumination imaging and large depth of field requirements is considered, and the use requirement of the medical endoscope is met.

The full field of view of the lens is larger than 0.3 under the frequency of MTF200lp/mm, the lens resolution is high, and the imaging quality is good.

The optical distortion of the lens is less than 5%, the distortion is small, and the appearance of an imaging picture cannot be influenced by overlarge distortion.

The mini infrared imaging lens of the present invention will be described in detail with reference to the following embodiments.

Example 1

Referring to fig. 1 and 2, the present invention discloses a medical endoscope lens, which includes a first lens 1, a second lens 2, a diaphragm 4 and a third lens 3 sequentially disposed along an optical axis from an object side to an image side, wherein the first lens 1 to the third lens 3 respectively include an object side surface facing the object side and allowing an imaging light to pass through and an image side surface facing the image side and allowing the imaging light to pass through;

The detailed optical data of this embodiment are shown in Table 1-1.

Table 1-1 detailed optical data for example 1

In this embodiment, the first lens element 1, the second lens element 2, and the third lens element 3 are all plastic even-order aspheric lens elements, and the object-side surface and the image-side surface of the first lens element 1, the second lens element 2, and the third lens element 3 are all aspheric surfaces. The equation for the surface curve of an aspherical lens is expressed as follows:

wherein the content of the first and second substances,

z: depth of the aspheric surface (the vertical distance between a point on the aspheric surface that is y from the optical axis and a tangent plane tangent to the vertex on the optical axis of the aspheric surface);

c: the curvature of the aspheric vertex (the vertex curvature);

k: cone coefficient (Conic Constant);

radial distance (radial distance);

r_n: normalized radius (normalization radius (NRADIUS));

u：r/r_n；

a_m: mth order Q^conCoefficient (is the m)^thQ^con coefficient)；

Q_m ^con: mth order Q^conPolynomial (the m)^thQ^con polynomial)。

The aspherical surface data in this example is shown in tables 1 to 2.

Table 1-2 aspheric data of example 1

In this embodiment, please refer to fig. 3 for an MTF graph of the lens under visible light, and it can be seen from the graph that when the spatial frequency of the lens reaches 200lp/mm, the MTF value is greater than 0.3, the imaging quality is good, and the resolution of the lens is high. Please refer to fig. 4 for a graph of field curvature and distortion of the lens under visible light, and it can be seen from the graph that field curvature curves of various wavelengths are basically overlapped, and chromatic aberration correction of the lens is better; meanwhile, the optical distortion of the system is less than + 5%, the distortion is small, the imaging quality is ensured, and the appearance of an imaging picture is not influenced by overlarge distortion. Referring to fig. 5, the illumination curve of the lens under visible light shows that the imaging illumination is greater than > 58%. Please refer to fig. 6, which shows that the magnification chromatic aberration of the lens under visible light is corrected well, less than 1um, and within the diffraction limit, the chromatic aberration is small, and the image color reducibility is high.

Example 2

As shown in fig. 7 and 8, the present example is different from example 1 mainly in the optical parameters such as the curvature radius of each lens surface and the lens thickness.

The detailed optical data of this embodiment is shown in Table 2-1.

Table 2-1 detailed optical data for example 2

In this embodiment, the first lens element 1, the second lens element 2, and the third lens element 3 are all plastic even-order aspheric lens elements, and the object-side surface and the image-side surface of the first lens element 1, the second lens element 2, and the third lens element 3 are all aspheric surfaces. The aspherical surface data in this embodiment is shown in table 2-2.

Table 2-2 aspheric data of example 2

In this embodiment, please refer to fig. 9 for an MTF graph of the lens under visible light, and it can be seen from the graph that when the spatial frequency of the lens reaches 200lp/mm, the MTF value is greater than 0.3, the imaging quality is good, and the resolution of the lens is high. Please refer to fig. 10 for a graph of field curvature and distortion of the lens under visible light, and it can be seen from the graph that field curvature curves of various wavelengths are basically overlapped, and chromatic aberration correction of the lens is better; meanwhile, the optical distortion of the system is less than + 4%, the distortion is small, the imaging quality is ensured, and the appearance of an imaging picture is not influenced by overlarge distortion. Referring to fig. 11, the illumination curve of the lens under visible light shows that the imaging illumination is greater than > 58%. Please refer to fig. 12, which shows that the magnification chromatic aberration of the lens under visible light is corrected well, less than 1um, and within the diffraction limit, the chromatic aberration is small, and the image color reducibility is high.

Example 3

As shown in fig. 13 and 14, the present example is different from example 1 mainly in the optical parameters such as the curvature radius of each lens surface and the lens thickness.

The detailed optical data of this example are shown in Table 3-1.

Table 3-1 detailed optical data for example 3

In this embodiment, the first lens element 1, the second lens element 2, and the third lens element 3 are all plastic even-order aspheric lens elements, and the object-side surface and the image-side surface of the first lens element 1, the second lens element 2, and the third lens element 3 are all aspheric surfaces. The aspherical surface data in this example is shown in Table 3-2.

Table 3-2 aspheric data of example 3

In this embodiment, please refer to fig. 15 for an MTF graph of the lens under visible light, and it can be seen from the graph that when the spatial frequency of the lens reaches 200lp/mm, the MTF value is greater than 0.3, the imaging quality is good, and the resolution of the lens is high. Please refer to fig. 16 for the field curvature and distortion diagram of the lens under visible light, and it can be seen from the diagram that the field curvature curves of the wavelengths are basically overlapped, and the chromatic aberration correction of the lens is better; meanwhile, the optical distortion of the system is less than 4%, the distortion is small, the imaging quality is ensured, and the appearance of an imaging picture is not influenced by overlarge distortion. Referring to fig. 17, the illuminance graph of the lens under visible light shows that the imaging illuminance is greater than > 58%. Please refer to fig. 18, which shows that the magnification chromatic aberration of the lens under visible light is corrected well, less than 1um, and within the diffraction limit, the chromatic aberration is small, and the image color reducibility is high.

Example 4

As shown in fig. 19 and 20, the present example is different from example 1 mainly in the optical parameters such as the curvature radius of each lens surface and the lens thickness.

The detailed optical data of this embodiment is shown in Table 4-1.

Table 4-1 detailed optical data for example 4

In this embodiment, the first lens element 1, the second lens element 2, and the third lens element 3 are all plastic even-order aspheric lens elements, and the object-side surface and the image-side surface of the first lens element 1, the second lens element 2, and the third lens element 3 are all aspheric surfaces. The aspherical surface data in this example is shown in Table 4-2.

Table 4-2 aspheric data of example 4

In this embodiment, please refer to fig. 21 for the MTF graph of the lens under visible light, and it can be seen from the graph that when the spatial frequency of the lens reaches 200lp/mm, the MTF value is greater than 0.3, the imaging quality is good, and the resolution of the lens is high. Please refer to fig. 22 for a graph of field curvature and distortion of the lens under visible light, and it can be seen from the graph that field curvature curves of various wavelengths are basically overlapped, and chromatic aberration correction of the lens is better; meanwhile, the optical distortion of the system is less than + 2%, the distortion is small, the imaging quality is ensured, and the appearance of an imaging picture is not influenced by overlarge distortion. Referring to fig. 23, the illumination curve of the lens under visible light shows that the imaging illumination is greater than > 58%. Please refer to fig. 24, which shows that the magnification chromatic aberration of the lens under visible light is corrected well, less than 1um, and within the diffraction limit, the chromatic aberration is small, and the image color reducibility is high.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention should be covered by the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A medical endoscope lens, characterized in that: the imaging lens comprises a first lens, a second lens, a diaphragm and a third lens which are sequentially arranged along an optical axis from an object side to an image side, wherein the first lens to the third lens respectively comprise an object side surface facing the object side and allowing imaging light rays to pass through and an image side surface facing the image side and allowing the imaging light rays to pass through;

the second lens has negative diopter, the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface;

2. A medical endoscope lens according to claim 1 and also comprising: the first lens, the second lens and the third lens are all plastic aspheric lenses, and the object side surfaces and the image side surfaces of the first lens, the second lens and the third lens are all aspheric surfaces.

3. A medical endoscope lens according to claim 1 and also comprising: the lens satisfies the following conditions: 45< vd1<60, 20< vd2<30, and 45< vd3<60, wherein vd1, vd2, and vd3 are the abbe numbers of the first lens, the second lens, and the third lens, respectively.

4. A medical endoscope lens according to claim 1 and also comprising: the lens satisfies the following conditions: 1.5< nd1<1.6, 1.6< nd2<1.7, 1.5< nd3<1.6, wherein nd1, nd2 and nd3 are refractive indexes of the first lens, the second lens and the third lens respectively.

5. A medical endoscope lens according to claim 1 and also comprising: the effective apertures of the first lens, the second lens and the third lens are all smaller than 2.3 mm.

6. A medical endoscope lens according to claim 1 and further comprising: the total optical length TTL of the lens is less than 4.5 mm.

7. A medical endoscope lens according to claim 1 and also comprising: the focal length f of the lens is 2.7 mm.

8. A medical endoscope lens according to claim 1 and also comprising: the clear light F/#ofthe lens is 2.8.