CN115793231A - Medical endoscope optical path system with high resolution and large field angle - Google Patents

Abstract

This scheme provides a medical endoscope optical path system of big angle of vision of high resolution includes objective, rod lens and eyepiece from the object side in proper order, objective include the convex-concave convex object mirror focus structure that light draws in the structure and constitute by convex lens, concave lens, convex lens in proper order from the object side in proper order, the rod lens including the multiunit monolens group that sets gradually, and every monolens group bilateral symmetry of group, left side part and right side part reduce the structure including the convex-concave bump diffusion function that constitutes by convex lens, concave lens, convex lens in proper order respectively, the eyepiece include convex lens, concave lens in order to constitute convex-concave structure in proper order. The combination of the objective lens, the rod lens and the eyepiece, which is improved by the structure, can improve various performances of an endoscope light path system, such as the imaging definition, the field angle and the resolution, thereby improving the imaging quality of the endoscope and making a prominent contribution to the improvement of the diagnosis level of the medical endoscope industry.

Description

Medical endoscope optical path system with high resolution and large field angle

Technical Field

The invention belongs to the field of medical instruments, and particularly relates to a medical endoscope optical path system with high resolution and large field angle.

Background

An endoscope is a camera device equipped with light that can enter the body through the mouth, other natural orifices, or other non-natural orifices. Since a lesion which cannot be displayed by an X-ray can be seen by an endoscope, it is very useful for finding a lesion.

The optical path system of the endoscope is a main component of the endoscope and is an optical path system from an object space, an objective lens, a rod lens, an eyepiece and an adapter (an ideal lens is replaced) to an image surface in sequence along the optical axis direction. The existing medical endoscope is usually matched with an f22 (focal length is 22 mm) adapter, the field angle is 37.5 degrees, and the maximum angular resolution cannot exceed 11.0C/(°) under the condition that the half-image height is more than 2.5 mm. The problems of small angle of view, low resolution and the like exist, so that the method still has a large improvement space. The scheme starts from an optical light path system, improves the resolution of the optical light path system of the endoscope by improving the objective lens, the rod lens and the eyepiece and combining the improved objective lens, the rod lens and the eyepiece, enlarges the field angle and further improves the imaging quality of the endoscope.

Disclosure of Invention

In view of the above problems, an object of the present invention is to provide an optical path system for a medical endoscope with high resolution and a large angle of view.

In order to achieve the purpose, the invention adopts the following technical scheme:

the utility model provides a medical endoscope optical light path system of big angle of vision of high resolution includes objective, rod lens and eyepiece from the object side in proper order, objective include the convex-concave convex objective focus structure that light draws in the structure and constitute by convex lens, concave lens, convex lens in proper order from the object side in proper order, the rod lens including the multiunit monoscopic group that sets gradually, and every monoscopic group bilateral symmetry, left side part and right side part respectively include in proper order that the structure is reduced to the convex-concave bump diffusion function that constitutes by convex lens, concave lens, convex lens, the eyepiece include convex lens, concave lens in proper order in order to constitute convex-concave structure.

The objective lens comprises a light gathering structure and a convex-concave convex objective lens focal length structure, light can be gathered through the light gathering structure so as to expand the field angle as far as possible, meanwhile, the spherical aberration of the objective lens can be corrected through the convex-concave objective lens focal length structural design, and the imaging quality is improved. Each single lens group is composed of a convex lens, a concave lens and a convex lens, so that the single lens group is integrally represented as a positive lens to achieve the effect of a small point spread function, the imaging quality and the resolution ratio are further improved, and the convex-concave structure of the ocular lens can also play the effect of improving the resolution ratio. Therefore, the combination of the objective lens, the rod lens and the eyepiece can expand the field angle, improve the imaging quality and resolution of the endoscope and improve the imaging definition of the endoscope, thereby effectively improving the diagnosis level of the medical endoscope industry.

In the optical path system of the medical endoscope with high resolution and large field angle, the objective lens is positioned between the light ray gathering structure and the convex-concave convex objective lens focal length structure and is also provided with lenses L3 and L4;

the lenses L3 and L4 are plane mirrors;

or the lenses L3 and L4 are both prisms, and at this time L5 is also replaced by a prism, the three lenses L3, L4, and L5 form a steering prism with a convex lens structure, and a suitable steering prism is selected according to a required viewing angle. The three prisms L3, L4 and L5 form a convex lens, and form a convex concave-convex objective lens focal length structure with the rear prisms L6 and L7.

In the optical path system of the medical endoscope with high resolution and large field angle, the objective lens is positioned at one side of the focal length structure of the convex-concave objective lens close to the rod lens, and the optical path system further comprises a cemented lens group and a rod lens field curvature correcting structure.

In the above medical endoscope optical path system with high resolution and large field angle, the cemented lens group includes L8 and L9;

l8 is a concave lens with concave surfaces of L8S1 and L8S2, and the curvature radius of L8S2 is larger than that of L8S 1; l9 is a convex lens with convex surfaces of L9S1 and L9S2, the curvature radius of L9S1 is larger than that of L9S2, and the curvature radius of L9S1 is equal to that of L8S2 so as to couple L9S1 and L8S 2;

the rod lens field curvature correcting structure comprises a convex lens L10, wherein L10S1 is a convex surface, L10S2 is a concave surface, and the curvature radius of L10S2 is larger than that of L10S 1;

s1 denotes the left side, and S2 denotes the right side.

In the above medical endoscope optical path system with high resolution and large field angle, the convex-concave objective focal length structure includes a convex lens L5, a concave lens L6, and a convex lens L7, wherein L5S1 is a plane, L5S2 and L6S1 are both convex surfaces, L6S2 and L7S1 are both concave surfaces, and L7S2 is a convex surface;

the curvature radius relation is as follows: L5S2 > L7S1 > L6S1 > L7S2 > L6S2.

In the above medical endoscope optical path system with high resolution and large field angle, the light converging structure includes a concave lens L2, and a surface L2S1 of the concave lens L2 close to the object side is a convex surface, a surface L2S2 close to the focal length structure of the convex-concave object lens is a concave surface, and the curvature radius of the L2S1 is greater than that of the L2S2;

in the above-described medical endoscope optical path system with high resolution and a large angle of view, the objective lens further includes a flat protective mirror L1 on the side of the concave lens L2 closer to the object side.

In the optical path system of the medical endoscope with high resolution and large field angle, the rod lens comprises three groups of single lenses which are arranged in sequence; each single lens group comprises lenses L11, L12, L13, L14, L15 and L16, wherein the lenses L11, L12 and L13 are respectively convex lenses, concave lenses and convex lenses to form the left part of the single lens group, and the lenses L14, L15 and L6 are respectively convex lenses, concave lenses and convex lenses to form the right part of the single lens group.

L11S1 of the left part is concave, L11S2 is convex, L12S1 and L11S2 are coupled into a concave surface, L13S2 is convex, and the right part is symmetrical to the left part; the curvature radius relation is as follows: L11S1 > L13S2 > L11S2= L12S1; L12S2 and L13S1 are concave, convex or plane.

In the optical path system for a medical endoscope with high resolution and large field angle, the eyepiece comprises a convex lens L29, a convex lens L30 and a concave lens L31 in sequence to form a convex-concave junction. And L29S1 is concave, L29S2 is convex, L30S1 is concave, L30S2 is convex, L31S1 and L30S2 are the concave surface of coupling, and L31S2 is the convex surface.

In the optical path system for a medical endoscope with high resolution and large field angle, the eyepiece lens is positioned at the rear side of the lens L31 and further comprises a lens L32, and the lens L32 is a plane protective lens.

The invention has the advantages that: the combination of the objective lens, the rod lens and the eyepiece, which is improved by the structure, can improve various performances of an endoscope light path system, such as imaging definition, field angle and resolution, thereby improving the imaging quality of the endoscope and making outstanding contribution to improving the diagnosis level of the medical endoscope industry.

Drawings

FIG. 1 is a combined structure diagram of an objective lens, a rod lens and an eyepiece in an optical path system of a medical endoscope according to the present invention;

FIG. 2 is a 0 ° view angle configuration of the objective lens of the present invention;

FIG. 3 is a 30 DEG view angle structure of the objective lens of the present invention;

FIG. 4 is a diagram of a rod mirror of the present invention;

FIG. 5 is a block diagram of a single set of lenses in a rod lens;

FIG. 6 is a diagram of the eyepiece of the present invention;

FIGS. 7-11 show the parameters of the lenses of this embodiment;

FIG. 12 is a graph of system modulation function as a function of focal distance;

FIG. 13 is a diagram of the modulation transfer function of the system plotted against the line;

FIG. 14 is a graph of system field curvature and distortion;

FIG. 15 is a diagram of system chromatic aberration with image plane height;

fig. 16 is a graph of system relative illuminance as a function of field of view.

Detailed Description

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

As shown in fig. 1, this embodiment discloses an optical path system of a medical endoscope with high resolution and large field angle, which includes an objective lens, a rod lens and an eyepiece in sequence from an object side, and other structures that are consistent with the prior art and are not improved are not described herein.

Specifically, as shown in fig. 2 and 3, the objective lens includes, in order from the object side, a plane protection lens L1, a lens L2 forming a light converging structure, lenses L3 and L4, lenses L5, L6 and L7 forming a convex-concave objective lens focal length structure, lenses L8 and L9 forming a cemented lens group, and a lens L10 forming a rod field curvature correcting structure.

Hereinafter, S1 denotes a surface of the respective lens close to the object side, i.e., a left surface, and S2 denotes a surface of the respective lens away from the object side, i.e., a right surface.

Specifically, the flat protective glass L1 is protected with flat sapphire.

The lens L2 is a concave lens, the focal length is [ -10mm, -3mm ], the object side face L2S1 is convex, the L3 side face L2S2 is concave, the radius of curvature of L2S1 is greater than that of L2S2, the radius of curvature of L2S1 can be about 6mm, such as about 5mm-7mm, the radius of curvature of L2S2 can be about 2mm, such as about 1mm-3mm. The distance between L1 and L2 is 0-2mm, such as 0.5mm. The concave lens structure of the lens L2 can play a role of gathering light to expand the angle of field.

The lenses L3 and L4 can be plane mirrors, and can offset the subsequent optical path difference;

the lenses L3 and L4 may be both prisms, in which case L5 is also replaced by a prism, three prisms L3, L4, and L5 form a steering prism with a convex lens structure, and form a convex concave-convex objective lens focal length structure with the following prisms L6 and L7. (ii) a

The lens L5 is a convex lens, the lens L6 is a concave lens, the lens L7 is a convex lens, and the focal lengths can be respectively selected from 3mm, 5mm, [ -50mm, -10mm ], [4mm and 6mm ]. L5S1 is the plane, and L5S2 and L6S1 all are the convex surface, and L6S2 and L7S1 all are the concave surface, and L7S2 is the convex surface. The convex-concave convex structure can correct the spherical aberration of the objective lens, and the lens groups with the focal length X (2.5 mm-5.0 mm) formed by matching the convex and concave parts L5, L6 and L7 become the main contribution of the focal length (within the range of 0.8-1.2 of X) of the objective lens.

The curvature radius relations of L5, L6 and L7 are as follows: L5S2 > L7S1 > L6S1 > L7S2 > L6S2.

The radius of curvature of L5S2 may be about 4mm, e.g. 3mm-5mm;

the radius of curvature of L7S1 may be about 3mm, such as 2mm-4mm;

the radius of curvature of the L6S1 can be about 3mm, such as 2mm-4mm;

the radius of curvature of L7S2 may be about 2mm, such as 1mm-3mm;

the radius of curvature of the L6S2 may be about 2mm, such as 1mm to 3mm.

L8 and L9 respectively use a cemented lens with high refractive index, low Abbe number and low refractive index, high Abbe number, L8 is a concave lens, L9 is a convex lens, the focal lengths of the cemented lens and the convex lens can be selected to be [ -3mm, -1.5mm ], [3.5mm, 5mm ], and the cemented lens group can achieve the effects of correcting the chromatic aberration of a system and improving the imaging quality.

Specifically, both L8S1 and L8S2 are concave; and the curvature radius of L8S2 is larger than that of L8S 1; the curvature radius of L8S1 can be about 1.5mm, such as 0.5mm-2.5mm; the radius of curvature of the L8S2 may be about 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 so as to couple L9S1 and L8S 2; the radius of curvature of the L9S2 may be about 2.5mm, such as 1.5mm to 3.5mm.

The lens L10 adopts a convex lens with a focal length of [8mm,20mm ], the L10S1 is convex, the L10S2 is concave, and the curvature radius of the L10S2 is larger than that of the L10S 1. The curvature radius of L10S1 can be about 6mm, such as 5mm-7mm; the radius of curvature of L10S2 may be about 34mm, such as 32mm to 36mm. The concave structure of the L10S2 can achieve the effects of correcting the field curvature caused by the rod lens and improving the imaging resolution and quality.

Specifically, as shown in fig. 4 and 5, the rod mirror includes three groups of single mirrors arranged in sequence, and each group of single mirrors has the same structure. And each single lens group is bilaterally symmetrical, and the left part and the right part respectively comprise a convex-concave convex point diffusion function reduction structure which is sequentially composed of a convex lens, a concave lens and a convex lens. The rod mirror is composed of three identical mirror groups and a single mirror group in bilateral symmetry, so that the total working length of the endoscope system can be prolonged, the processing cost is reduced, and axial aberration is eliminated.

Specifically, each single lens group comprises lenses L11, L12, L13, L14, L15 and L16, wherein L11, L12 and L13 are respectively a convex lens, a concave lens and a convex lens to form the left portion of the single lens group, and L14, L15 and L6 are respectively a convex lens, a concave lens and a convex lens to form the right portion of the single lens group. L11S1 of the left part is concave, L11S2 is convex, L12S1 and L11S2 are coupled into a concave surface, L13S2 is convex, L12S2 and L13S1 are free of constraint and can be concave, convex or plane, and the right part is symmetrical with the concave surface, convex or plane. The curvature radius relation is as follows: L11S1 > L13S2 > L11S2= L12S1. The convex and concave combined structure of the single lens group enables the single lens group to be integrally represented as a positive lens, so that a small point spread function effect is achieved, meanwhile, the L11S1 adopts the concave surface to ensure that the rod lens can transmit a large image plane (a half image plane is larger than 1.9 mm) under a small light-transmitting aperture (the diameter is smaller than 6.5 mm), and meanwhile, the rod lens NA is ensured to be more than 0.17, so that the angular resolution and the imaging height of the endoscope system can be effectively increased.

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

the radius of curvature of L11S1 may be from 20mm to 30mm, such as 24.123156mm; the radius of curvature of L11S2 may be 5mm-8mm, such as 6.769709mm;

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

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

The curvature radius of the L12S1 is consistent with that of the L11S 2; L13S1 is preferably coupled to L12S2 so that the radii of curvature of the two are identical; the radius of curvature of L13S2 may be 12mm to 16mm, such as 14.913970mm.

Specifically, as shown in fig. 6, the eyepiece includes lenses L29, L30, L31, and L32, and the lens L32 is a plane protection mirror. L29, L30, L31 are respectively convex lens, concave lens to form a convex-concave structure. The L29S1 is concave, and the curvature radius can be 7mm-9mm; L29S2 is a convex surface, and the curvature radius can be 4.5mm-6.5mm; the L30S1 is concave, and the curvature radius can be 76mm-79mm; L30S2 is convex, and the curvature radius can be 8mm-12mm; L31S1 and L30S2 are coupled into a concave surface, and the curvature radius can be 8mm-12mm; the L31S2 is convex, and the curvature radius can be 21mm-25mm. The whole L29-L30 of eyepiece is protruding concave structure, and L29S1 adopts the concave surface, can play the effect of cooperation rod mirror adjustment system field curvature, alleviates the pressure of rod mirror, can guarantee simultaneously that eyepiece objective focus is less than 16.3mm, and objective NA is more than 0.17 to reach whole system and can reach half image plane height more than 2.7mm at cooperation F22 adapter, whole system F # guarantees below 7.87 that the angular resolution can reach more than 13.3C/(°).

The relative position and the interval between the lenses in the embodiment are ensured by spacers (hollow), and then the lenses and the pipe wall are fixed by glue; if the cemented lens is not provided with a spacer, the cemented lens and the pipe wall are fixed directly by glue.

In this embodiment, the parameters shown in fig. 7-11 are taken as examples, fig. 7 mainly shows objective parameters, fig. 8 and 9 mainly show rod parameters, and fig. 10 mainly shows eyepiece parameters. The second column in the figure 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;

the third column represents a surface type, sphere represents a spherical surface type, and all the surfaces are spherical in the system;

the fourth column indicates the radius of curvature, infinity indicates the radius of curvature (plane); 6.096252 The radius of curvature is 6.096252mm, and the center of the circle is on the right; -4.252331 represents a radius of curvature of 4.252331mm, centered on the left;

the fifth column represents the distance from the next face in mm; the sixth column represents lens material;

the seventh column represents refraction; the eighth column indicates the effective aperture in mm.

Fig. 11 shows the focal lengths of the lenses, and since the three groups of single lenses of the rod lens have the same structure and are symmetrical to each other, the structure is only described in the left portion of the first group of single lenses, and the description of the right portion of the first group and the remaining two groups is omitted.

FIGS. 12-16 show the performance of the above structure and the parameters of FIGS. 7-11 using code V design software: FIG. 12 is a diagram of the system modulation function as a function of focal distance, showing the resolution of the lens near the optimal image plane as a function of distance, with the system 60 being oriented toward/mm; fig. 13 is a diagram of the system modulation transfer function in line up, showing the system resolution of the system in line up; FIG. 14 is a diagram of system field curvature and distortion; FIG. 15 is a diagram of system chromatic aberration varying with image plane height; fig. 16 is a graph of relative system illuminance as a function of field of view. From the performance diagrams, the endoscope realized by the structure can achieve an endoscope system with higher resolution and larger field angle.

In addition, the scheme also obtains a series of parameters of the endoscope system realized by the structure and the parameters through code V design simulation: the F Number (FNO) was 7.87, the magnification (RED) was 0.0940, the optical working distance (OBJ DIS) was 40mm and the ENTRANCE PUPIL distance (ENTRANCE PUPIL) was 2.8690mm.

The reciprocal of the limiting resolution angle of the center of the entrance pupil of the optical lens for the minimum distinguishable equidistant fringe width at a given optical working distance is expressed in cycles/degree [ C/(°) ] and the calculation formula is shown in formula (1)

In the formula:

r _a (d) Indicating angular resolution

r (d) represents the number of distinguishable line pairs per millimeter in units of line pairs per millimeter (lp/mm)

a represents the distance in millimeters (mm) from the end of the endoscope to the pupil

d represents an optical working distance in millimeters (mm).

F Number (FNO) of the system is 7.87 according to the diffraction limit formula d =1.22 λ × F, where d is the image space minimum resolving distance, λ is the wavelength, F is the F number; the wavelength of light in the system is 550nm, and the minimum resolution distance of an image space is 5.28um when F = 7.87. Magnification (RED) is 0.0940; i.e. the minimum resolving distance of the object is 56.17um; the object resolution (r (d)) was therefore 17.803lp/mm; then, in combination with an optical working distance (OBJ DIS) of 40mm and an ENTRANCE PUPIL distance (ENTRANCE PUPIL) of 2.8690mm, i.e., d and a above, a maximum angular resolution of 13.3C/(°) can be calculated.

The combination of the objective lens, the rod lens and the eyepiece can improve the imaging definition and the view field angle of the endoscope, so that the diagnosis level of the medical endoscope industry is effectively improved.

The specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the invention as defined in the appended claims.

Although the terms objective, eyepiece, rod, single lens set, optic, etc. are used more often herein, the possibility of using other terms is not excluded. These terms are used merely to more conveniently describe and explain the nature of the present invention; they are to be construed as being in any sense inconsistent with the present invention.

Claims (10)

1. The utility model provides a medical endoscope optical light path system of big angle of vision of high resolution includes objective, rod lens and eyepiece from the object side in proper order, its characterized in that, objective include the convex-concave convex objective focus structure that light draws in the structure and constitute by convex lens, concave lens, convex lens in proper order from the object side in proper order, the rod lens including the multiunit list group that sets gradually, and every group list mirror group bilateral symmetry, left side part and right side part reduce the structure including the convex-concave bump spread function that constitutes by convex lens, concave lens, convex lens in proper order respectively, the eyepiece include convex lens, concave lens in proper order in order to constitute convex-concave structure.

2. The optical path system for medical endoscope with high resolution and large field angle as claimed in claim 1, wherein the objective lens is located between the light converging structure and the convex-concave objective lens focal length structure, and further comprises lenses L3 and L4;

the lenses L3 and L4 are plane mirrors;

or the lenses L3 and L4 are prisms, and L5 is also replaced by a prism, and the three lenses L3, L4, and L5 form a steering prism with a convex lens structure.

3. The optical path system for a medical endoscope with high resolution and large field angle as claimed in claim 2, wherein the objective lens is located at the side of the convex-concave objective lens focal length structure close to the rod lens, and further comprises a cemented lens group and a rod curvature of field correcting structure.

4. The high resolution, large field angle medical endoscope optical path system according to claim 3, wherein said cemented lens group comprises L8 and L9;

l8 is a concave lens with concave surfaces of L8S1 and L8S 2; l9 is a convex lens with both convex surfaces of L9S1 and L9S 2;

the rod lens field curvature correcting structure comprises a convex lens L10, wherein L10S1 is a convex surface, and L10S2 is a concave surface;

s1 denotes the left side, and S2 denotes the right side.

5. The optical path system for medical endoscope with high resolution and large field angle as claimed in claim 1, wherein the focal length structure of convex-concave object lens comprises a convex lens L5, a concave lens L6 and a convex lens L7 in sequence, wherein L5S1 is a plane, L5S2 and L6S1 are both convex, L6S2 and L7S1 are both concave, and L7S2 is a convex.

6. The optical path system of claim 1, wherein the light converging structure comprises a concave lens L2, and the concave lens L2 is convex near the object side L2S1 and concave near the convex-concave object focal length structure side L2S 2.

7. The optical path system for a high-resolution and large-field angle medical endoscope according to claim 1, wherein the objective lens further includes a plane protection mirror L1 on a side of the concave lens L2 close to the object side.

8. The optical path system for a high resolution and large field angle medical endoscope according to any one of claims 1-7, wherein said rod lens comprises three groups of single lens arranged in sequence;

each single lens group comprises lenses L11, L12, L13, L14, L15 and L16, wherein the lenses L11, L12 and L13 are respectively convex lenses, concave lenses and convex lenses to form the left part of the single lens group, and the lenses L14, L15 and L6 are respectively convex lenses, concave lenses and convex lenses to form the right part of the single lens group;

and L11S1 of the left side part is a concave surface, L11S2 is a convex surface, L12S1 and L11S2 are coupled into a concave surface, L13S2 is a convex surface, L12S2 and L13S1 are concave surfaces, convex surfaces or planes, and the right side part is symmetrical to the left side part.

9. The optical path system of a medical endoscope with high resolution and large field angle as claimed in any one of claims 1-7, wherein the eyepiece comprises a convex lens L29, a convex lens L30, and a concave lens L31 in sequence to form a convex-concave structure, wherein L29S1 is concave, L29S2 is convex, L30S1 is concave, L30S2 is convex, L31S1 and L30S2 are coupled to form a concave, and L31S2 is convex.

10. The optical path system for a medical endoscope with high resolution and large field angle as claimed in claim 9, wherein said eyepiece further comprises a lens L32 located at the right side of the lens L31, and the lens L32 is a plane protective glass.

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