WO2019001275A1 - Optical imaging system for endoscope - Google Patents

Abstract

An optical imaging system for an endoscope comprises an objective lens system (1), a relay lens system (2) and an ocular lens system (3) that are sequentially cemented as a whole in a light propagation direction. The objective lens system (1) is a retrofocus structure, and comprises a first protective window (11), a plano-concave lens (12), a deflecting prism (13), a first plano-convex lens (14), a first cemented doublet lens (15), a second cemented doublet lens (16), a third cemented doublet lens (17) and a second plano-convex lens (18) that are sequentially cemented in a light propagation direction. The relay lens system comprises n sets of relay lens groups, and each set of relay lens groups are all of dual-telecentric structures. The relay lens groups are formed by symmetrically arranging two cemented quintuplet rod-shaped lenses. The ocular lens system (3) is of a telecentric structure in object space, and comprises a first cemented triplet lens (31), a second cemented triplet lens (32), a second convex lens (33), a second protective window (34) and a second aperture diaphragm (35) that are sequentially cemented in a light propagation direction. The optical imaging system has optical imaging performance with a high resolution and a low distortion less than 5%.

Description

Endoscopic optical imaging system Technical field

The present invention relates to an optical imaging system, and in particular to an optical imaging system for an endoscope.

Background technique

The endoscope consists of an imaging objective at the end, a imaging system in the middle, and a proximal eyepiece, where the imaging objective plays a decisive role in the imaging performance of the endoscope. Medical diagnosis and surgery require the endoscope to have a large field of view, high resolution, low distortion and thin diameter, which puts high demands on the objective lens imaging system and the image conversion system of the endoscope.

The existing endoscope optical system is composed of a flat concave negative lens, a steering prism, a plano-convex lens, and a subsequent cemented lens. It is a distortion of the position correction correction system through the position of the positive and negative lenses in the objective lens group, but does not give a achievable Relative distortion values; some are endoscopic objectives designed with sapphire material, which consists of two plano-convex mirrors with a maximum optical distortion of 20%.

In summary, the existing endoscope optical system can not correct the large field of view optical distortion and at the same time ensure the optical high-definition imaging in the full field of view. In view of this, there is an urgent need to develop a large field of view rigid tube endoscope optical system, which has the characteristics of low distortion and full field in-field high-definition imaging.

technical problem

The technical problem to be solved by the present invention is that overcoming the optical system of the prior art, the optical field distortion of the large field of view and the optical high-definition imaging in the full field of view are not well corrected, and a technical problem is provided. An optical imaging system for endoscopes with high definition resolution and optical imaging performance with distortion less than 5%.

Technical solution

In order to achieve the above object, the solution of the present invention is an optical imaging system for an endoscope comprising an objective lens system, a relay mirror system and an eyepiece system which are sequentially glued together in the direction of light propagation, the relay mirror system Located between the objective system and the eyepiece system; its innovations are:

The objective lens system is an anti-distance structure, and the objective lens system includes a first protection window sequentially glued along the direction of light propagation, a first plano-concave mirror, a steering prism, a first plano-convex lens, a first double cemented lens, and a second double a cemented lens, a third double cemented lens, and a second plano-convex lens;

The relay mirror system includes n sets of relay mirror groups, and each set of relay mirror groups is a double telecentric structure, and the relay mirror group is symmetrically arranged by two five-glued rod mirrors, and two An aperture stop is arranged at a center between the five glued rod mirrors, wherein the five glued rod mirrors are glued by a meniscus concave mirror, a second plano concave lens, a rod mirror, a third flat concave mirror and a first convex lens, wherein n is an odd number;

The eyepiece system is an object-side telecentric structure, and the eyepiece system includes a first three-glued lens, a second three-glued lens, a second convex lens, a second protective window, and a second aperture stop glued along a direction of light propagation;

The second plano-convex lens of the objective system is located outside the meniscus concave mirror at one end of the relay mirror system, and the first three cemented lens of the eyepiece system is located outside the first convex lens at the other end of the relay mirror system.

In the above technical solution, the first aperture stop is disposed in the steering prism of the objective lens system.

In the above technical solution, the first protection window of the objective lens system, the first plano-concave mirror, the steering prism, the first plano-convex lens, the first double cemented lens, the second double cemented lens, the third double cemented lens, and the second The plano-convex lens is sequentially bonded by ultraviolet photosensitive glue or methanol glue or optical epoxy glue.

In the above technical solution, the meniscus concave mirror, the second plano concave lens, the rod mirror, the third flat concave mirror and the first convex lens of the five-glued rod mirror are sequentially glued with ultraviolet photosensitive glue or methanol glue or optical epoxy glue. to make.

In the above technical solution, the first three cemented lens, the second three cemented lens, the second convex lens, the second protective window and the second aperture stop of the eyepiece system are sequentially used with ultraviolet photosensitive glue or methanol glue or optical epoxy glue. Glued together.

In the above technical solution, the first three-glued lens and the second three-glued lens of the eyepiece system are all glued by three lenses with ultraviolet photosensitive glue or methanol glue or optical epoxy glue.

In the above technical solution, the first protection window of the objective lens system is quartz glass or sapphire.

In the above technical solution, the second protection window of the eyepiece system is quartz glass or sapphire.

Beneficial effect

The positive effect of the present invention is that after the optical imaging system of the endoscope of the present invention is used, since the objective lens system of the present invention is an anti-distance structure, and the objective lens system includes the first protection which is sequentially glued in the direction of light propagation. a window, a first plano-concave mirror, a steering prism, a first plano-convex lens, a first double cemented lens, a second double cemented lens, a third double cemented lens, and a second plano-convex lens; the objective lens system has positive power a double-bonded lens in which a lens is bonded to a lens having a negative power to properly correct on-axis and off-axis chromatic aberration; the relay mirror system includes n sets of relay mirror groups, and each The group of relay mirrors is a double telecentric structure, and the relay lens group is symmetrically arranged by two five-glued rod mirrors, and an aperture stop is arranged at a center between the two five-glued rod mirrors, The five-glued rod mirror is made of a meniscus concave mirror, a second plano-concave lens, a rod-shaped mirror, a third flat-concave mirror and a first convex lens, wherein n is an odd number; the eyepiece system is an object-side telecentric structure, and the eyepiece The system includes the direction of light propagation Glued first three cemented lens, second three cemented lens, second convex lens, second protective window and second aperture stop; since the objective lens system of the invention is an anti-distance structure, the eyepiece system is an object-centered telecentric structure In order to ensure the connection with the diaphragm of the relay mirror system, and determine the focal length of the eyepiece group according to the field of view required by the field of view and the back-end photography system required to directly observe through the eyepiece; the present invention has the advantages of:

1. The laparoscopic system is a large field of view system. The objective lens system of the present invention adopts a flat concave mirror, and the optical distortion of the objective lens is less than 5% through the optimized design of the aspherical surface, and the 1920*1080 height is realized in the full field of view. Clear imaging;

Second, the endoscope's relay system requires no new aberrations and high light transmittance. The present invention uses a completely identical rod mirror to achieve this purpose; two strictly symmetrically arranged rods The mirror forms a set of double telecentric optical systems, and the vertical axis aberrations are well corrected. The same rod mirror is used to facilitate the fabrication of components.

DRAWINGS

1 is a schematic structural view of an optical imaging system of an endoscope according to the present invention;

2 is a schematic structural view of an objective lens system of the present invention;

3 is a schematic view showing a prism assembly structure of the present invention;

4 is a schematic structural view of a relay mirror system of the present invention;

Figure 5 is a schematic view of the eyepiece system of the present invention;

6 is an MTF graph of an optical imaging system of an endoscope of the present invention;

Figure 7 is a distortion diagram of an optical imaging system of an endoscope of the present invention;

Figure 8 is a graph showing an image illuminance of an optical imaging system of an endoscope of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be further described below in conjunction with the drawings and the given embodiments, but is not limited thereto.

As shown in Figures 1, 2, 3, 4, 6, 7, and 8, an optical imaging system for an endoscope includes an objective lens system 1, a relay mirror system 2, and an eyepiece that are sequentially glued together in the direction of light propagation. System 3, the relay mirror system 2 is located between the objective lens system 1 and the eyepiece system 3;

The objective lens system 1 is an anti-distance structure, and the objective lens system 1 includes a first protection window 11 which is sequentially glued in the direction of light propagation, a first plano-concave mirror 12, a steering prism 13, a first plano-convex lens 14, and a first double a cemented lens 15, a second double cemented lens 16, a third double cemented lens 17 and a second plano-convex lens 18;

The relay mirror system 2 includes n sets of relay mirror groups, and each set of relay mirror groups is a double telecentric structure, and the relay mirror group is formed by two five-glued rod mirrors symmetrically arranged, and two An aperture stop is provided at a center between the five glued rod mirrors, and the five-glued rod mirror is composed of a meniscus concave mirror 21, a second plano-concave lens 22, a rod mirror 23, a third flat concave mirror 24, and a first convex lens 25. Glued, wherein n is an odd number;

The eyepiece system 3 is an object-side telecentric structure, and the eyepiece system 3 includes a first three-bonded lens 31, a second three-bonded lens 32, a second convex lens 33, a second protective window 34, and the first glued in the direction of light propagation. Two aperture stop 35;

The second plano-convex lens 18 of the objective lens system 1 is located outside the meniscus concave mirror 21 at one end of the relay mirror system 2, and the first three cemented lens 31 of the eyepiece system 3 is located at the other convex lens 25 at the other end of the relay mirror system 2. The outside.

As shown in FIG. 3, the steering prism 13 of the objective lens system 1 of the present invention is provided with a first aperture stop, and the entrance pupil of the first aperture stop is located at the front focal plane of the objective lens to form an image telecentric optical path. The uniformity of the image surface illumination and the pupil of the relay mirror system 2 of the double telecentric structure are ensured.

As shown in FIG. 2, the first protection window 11, the first flat concave mirror 12, the steering prism 13, the first plano-convex lens 14, the first double cemented lens 15, and the second double cemented lens 16 of the objective lens system 1 of the present invention are shown in FIG. The third double-bonded lens 17 and the second plano-convex lens 18 are sequentially bonded by ultraviolet photosensitive glue or methanol glue or optical epoxy glue. The advantage of this design is that the plano-concave mirror rapidly reduces the angle of incidence of the beam of the large field of view, reducing the high-level aberrations, and the subsequent lenses balance the residual aberrations.

Embodiments of the invention

The meniscus concave mirror 21, the second plano concave lens 22, the rod mirror 23, the third flat concave mirror 24 and the first convex lens 25 of the five-glued rod mirror of the present invention are sequentially glued with ultraviolet photosensitive glue or methanol glue or optical epoxy glue. Made. The advantage of this design is to ensure that the rod mirror does not deform when it is sterilized at high temperatures.

The first three cemented lens 31, the second three cemented lens 32, the second convex lens 33, the second protective window 34 and the second aperture stop 35 of the eyepiece system 3 of the present invention sequentially use ultraviolet photosensitive glue or methanol glue or optical ring Oxygen glue is glued together. The advantage of this design is that the eyepiece magnifies the small size of the intermediate image surface, and the pupil is matched with the human eye or the subsequent bayonet. The eyepiece balances the residual aberration after the combination of the objective lens and the rod mirror.

The first three-glued lens 31 and the second three-glued lens 32 of the eyepiece system 3 of the present invention are all glued by three lenses with ultraviolet photosensitive glue or methanol glue or optical epoxy glue. The advantage of this design is that it can balance the chromatic aberration.

The data is as follows:

Serial number	Radius of curvature r	Surface spacing d	Refractive index n	Abbe number vd
61	7.635	3	2.02	29.1
62	-9.174	1.3	1.73	28.4
63	2.65	2.2	1.53	77
64	6.878	1.4

First three cemented lenses (31)

Serial number	Radius of curvature r	Surface spacing d	Refractive index n	Abbe number vd
65	-2.65	1.9	1.9	31.3
66	-2.69	1.1	1.72	34.7
67	9.094	2.9	1.68	55.2
68	-6.67	0.5

Second three cemented lens (32)

The first protective window 11 of the objective lens system 1 of the present invention is quartz glass or sapphire. The benefits of this design are: sapphire hardness of 9 and quartz hardness of 7.5, which effectively protects.

The second protective window 34 of the eyepiece system 3 of the present invention is quartz glass or sapphire. The benefits of this design are: sapphire hardness of 9 and quartz hardness of 7.5, which effectively protects.

As shown in FIG. 2, the design of the objective lens system 1 of the present invention is beneficial on the one hand to correct the 75° large field of view aberration, and on the other hand increases the rear working distance of the lens; the steering prism 13 of the objective lens system 1 a first aperture stop is provided, and the entrance pupil of the first aperture stop is located at the front focal plane of the objective lens to form an image telecentric optical path, which ensures the uniform illumination of the image plane and the relay mirror system with the double telecentric structure. The pupils are connected. For laparoscopes of different length specifications, the relay mirror system 2 can be composed of an odd array of the above-described relay mirror sets.

As shown in FIG. 2, in the objective lens system 1 of the present invention, by appropriately maintaining the thickness of the plano-convex mirror, the off-axis aberration such as astigmatism can be well corrected, and at the same time, the lens having positive power and having The first double cemented lens in which the negative power lens is joined can well correct the chromatic aberration on the shaft and off-axis.

As shown in FIG. 3, in the relay mirror system 2 of the present invention, the concave mirror corrects the axial aberration, and the convex mirror assumes the power.

As shown in FIG. 4, the eyepiece system 3 of the present invention is designed as an object-distance telecentric structure to ensure the connection with the pupil of the front-end relay mirror system 2, and to view the field of view and back-end photography required for direct observation through the eyepiece. The system determines the focal length of the eyepiece group for the field of view. The field of view of the eyepiece system 3 of the present invention has a pupil diameter of 3.7 mm and an exit pupil distance of 8 mm.

As shown in Fig. 1, Table 3 below is the design data of the embodiment.

Among them, the object surface of 1~17 is the objective structure parameter. When optimizing the design, the radius of the concave surface should be controlled so that the platform has sufficient width to avoid water leakage after gluing.

The object surface of 18~59 is the structural parameter of the steering system. The image focus of the objective lens system coincides with the object focus of the steering system to form a double telecentric system. Because it is a double far center light path, the thickness error of the spacer ring has little effect on the image quality.

Table 3 :

Serial number	Radius of curvature r	Surface spacing d	Refractive index n	Abbe number vd
Object	Infinity	40
1	Infinity	0.8	1.77	72.2
2	Infinity	0.8	1.58	40.9
3	3.19	0.68
4	Infinity	8	2.02	29.1
5	Infinity	3	1.81	25.4
6	-4.479	0.8
7	-3.5	0.8	1.72	29.6
8	4.3	2.4	1.61	57.9
9	-4.479	0.15
10	4	1.97	1.79	44.1
11	2.83	2.7	1.53	77
12	3.436	0.44
13	7.22	2.1	1.57	57.5
14	-2.074	1.2	2.02	29.1
15	-4.91	0.17
16	10.93	2.1	1.77	49.6
17	Infinity	0.341567
18	Infinity	3.195
19	-25.212	1.7	2.02	29.1
20	-8.077	1.7	1.5	56.4
twenty one	Infinity	46.2	1.46	65.8
twenty two	Infinity	1.7	1.85	32.2
twenty three	13.41	1.7	1.84	43.0
twenty four	-31.5	1.38
25	Infinity	1.38
26	31.5	1.7	1.84	43.0
27	-13.41	1.7	1.85	32.2
28	Infinity	46.2	1.46	65.8
29	Infinity	1.7	1.5	56.4
30	8.077	1.7	2.02	29.1
31	25.212	3.195
32	Infinity	3.195
33	-25.212	1.7	2.02	29.1
34	-8.077	1.7	1.5	56.4
35	Infinity	46.2	1.46	65.8
36	Infinity	1.7	1.85	32.2
37	13.41	1.7	1.84	43.0
38	-31.5	1.38
39	Infinity	1.38
40	31.5	1.7	1.84	43.0
41	-13.41	1.7	1.85	32.2
42	Infinity	46.2	1.46	65.8
43	Infinity	1.7	1.5	56.4
44	8.077	1.7	2.02	29.1
45	25.212	3.195
46	Infinity	3.195
47	-25.212	1.7	2.02	29.1
48	-8.077	1.7	1.5	56.4
49	Infinity	46.2	1.46	65.8
50	Infinity	1.7	1.85	32.2
51	13.41	1.7	1.84	43.0
52	-31.5	1.38
53	Infinity	1.38
54	31.5	1.7	1.84	43.0
55	-13.41	1.7	1.85	32.2
56	Infinity	46.2	1.46	65.8
57	Infinity	1.7	1.5	56.4
58	8.077	1.7	2.02	29.1
59	25.212	3.195
60	Infinity	8.41607
61	7.635	3	2.02	29.1
62	-9.174	1.3	1.73	28.4
63	2.65	2.2	1.53	77
64	6.878	1.4
65	-2.65	1.9	1.9	31.3
66	-2.69	1.1	1.72	34.7
67	9.094	2.9	1.68	55.2
68	-6.67	0.5
69	18.5	1.5	1.73	54.5
70	-71.04	3.5
71	Infinity	3	1.77	72.2
72	Infinity	8

Since the imaging surface of the endoscope is a minimally invasive surface, in order to prevent the adhesion of the wound from affecting the visual observation and operation during the operation, an air-blasting treatment is required, so that the object surface is a spherical arc surface.

As shown in FIGS. 6, 7, and 8, which are the MTF curve, the distortion curve, and the image surface illuminance curve of the mirror of the present invention, the present invention discloses an optical body of an endoscope having an outer diameter of 6 mm and a 75° field of view. Imaging system with high definition resolution and optical imaging performance with distortion less than 0.5%. In the objective lens system, the off-axis aberration such as astigmatism can be well corrected by appropriately maintaining the thickness of the plano-convex mirror, and the lens having positive power is engaged with the lens having negative power. The first double-bonded lens can well correct the on-axis and off-axis chromatic aberration, and the optimized design of it provides high-definition imaging in the full field of view. The rod mirror system is composed of an odd array of rod mirrors, and a single five-glued rod mirror is formed by a meniscus concave mirror, a plano-concave lens, a rod mirror, a flat concave mirror and a convex lens, wherein two concave mirrors are formed. The axial aberrations are well corrected; two symmetrically arranged rod mirrors form a set of repeating mirrors with a double telecentric structure. The eyepiece system is an object-centered telecentric structure that satisfies the field of view angle 2ω=15.19° according to the requirements of the rear-end camera system. Therefore, the optical system of the rigid-tube laparoscope of the present invention has high-definition, low-distortion, optical imaging performance of 75° field of view.

In view of the above-described embodiments of the present invention, various changes and modifications may be made by those skilled in the art without departing from the scope of the invention. The technical scope of the present invention is not limited to the contents of the specification, and the technical scope thereof must be determined according to the scope of the claims.

Claims (8)

1. An optical imaging system for an endoscope comprising an objective lens system (1), a relay mirror system (2) and an eyepiece system (3) which are sequentially glued together in a direction of light propagation, the relay mirror system (2) Located between the objective system (1) and the eyepiece system (3); characterized by:

   The objective lens system (1) is an anti-distance structure, and the objective lens system (1) includes a first protection window (11), a first plano-concave mirror (12), and a steering prism (13) which are sequentially glued in the direction of light propagation. a first plano-convex lens (14), a first double cemented lens (15), a second double cemented lens (16), a third double cemented lens (17) and a second plano-convex lens (18);

   The relay mirror system (2) includes n sets of relay mirror groups, and each set of relay mirror groups is a double telecentric structure, and the relay mirror group is formed by two five-glued rod mirrors symmetrically arranged. And an aperture stop is arranged at the center between the two five-glued rod mirrors, and the five-glued rod mirror is composed of a meniscus concave mirror (21), a second concave concave lens (22), a rod mirror (23), and a third flat The concave mirror (24) and the first convex lens (25) are glued together, wherein n is an odd number;

   The eyepiece system (3) is an object-side telecentric structure, and the eyepiece system (3) includes a first three-bonded lens (31), a second three-glued lens (32), and a second convex lens that are glued in the direction of light propagation ( 33), a second protective window (34) and a second aperture stop (35);

   The second plano-convex lens (18) of the objective lens system (1) is located outside the meniscus concave mirror (21) at one end of the relay mirror system (2), and the first three cemented lens (31) of the eyepiece system (3) is located The outer side of the first convex lens (25) at the other end of the relay mirror system (2).
2. The optical imaging system of an endoscope according to claim 1, characterized in that the steering prism (13) of the objective lens system (1) is provided with a first aperture stop.
3. The optical imaging system of an endoscope according to claim 1, characterized in that: the first protective window (11) of the objective lens system (1), the first plano-concave mirror (12), the steering prism (13), The first plano-convex lens (14), the first double-bonded lens (15), the second double-bonded lens (16), the third double-bonded lens (17) and the second plano-convex lens (18) are sequentially made of ultraviolet photosensitive glue or methanol glue Or optical epoxy glue glued together.
4. The optical imaging system for an endoscope according to claim 1, wherein the meniscus concave mirror (21), the second plano-concave lens (22), the rod mirror (23), and the third of the five-glued rod mirror are used. The flat concave mirror (24) and the first convex lens (25) are sequentially bonded by ultraviolet photosensitive glue or methanol glue or optical epoxy glue.
5. The optical imaging system of an endoscope according to claim 1, wherein the first three cemented lenses (31), the second three cemented lenses (32), and the second convex lenses (33) of the eyepiece system (3) The second protective window (34) and the second aperture stop (35) are sequentially glued with ultraviolet photosensitive glue or methanol glue or optical epoxy glue.
6. An optical imaging system for an endoscope according to claim 1 or 5, wherein the first three cemented lenses (31) and the second three cemented lenses (32) of the eyepiece system (3) are each three The lenses are glued with UV or UV glue or optical epoxy.
7. The optical imaging system of an endoscope according to claim 1, characterized in that the first protective window (11) of the objective system (1) is quartz glass or sapphire.
8. The optical imaging system of an endoscope according to claim 1, characterized in that the second protective window (34) of the eyepiece system (3) is quartz glass or sapphire.