CN117784390A - Optical imaging system and endoscope - Google Patents

Abstract

The application discloses an optical imaging system and an endoscope. The optical imaging system comprises a front end objective lens group, a relay rod lens mechanism and a rear end eyepiece lens group which are sequentially arranged from an object side to an image side, wherein the relay rod lens mechanism comprises N groups of relay rod lens groups, N=2n+1, N is a natural number, N groups of relay rod lens groups are sequentially arranged from the object side to the image side along the optical axis of the optical imaging system, and each group of relay rod lens groups comprises a rod lens part and a cemented lens part which are mutually separated. The hard tube endoscope optical imaging system can solve the problems that an optical imaging system of a hard tube endoscope in the prior art is complex in structure, high in processing difficulty and high in production cost.

Description

Optical imaging system and endoscope

Technical Field

The application relates to the technical field of medical instruments, in particular to an optical imaging system and an endoscope.

Background

The optical imaging system of a hard tube endoscope is generally composed of a front-end objective lens, a relay imaging system and a rear-end eyepiece lens, wherein the objective lens has a critical influence on the imaging performance of the optical system. Because the hard tube endoscope has very high requirements on optical performance, high resolution, high relative illuminance and low distortion are required, enough lenses are required to optimize aberration and improve performance when an optical system is designed. This also results in the characteristics of complicated structure, high processing difficulty and high cost of many hard tube endoscopes on the market at present.

Disclosure of Invention

The main aim of the application is to provide an optical imaging system and an endoscope, so as to solve the problems of complex structure, high processing difficulty and high production cost of the optical imaging system of the hard tube endoscope in the prior art.

According to one aspect of the present application, there is provided an optical imaging system including a front-end objective lens group, a relay rod lens mechanism, and a rear-end eyepiece lens group disposed in this order from an object side to an image side,

the relay rod lens mechanism comprises N groups of relay rod lens groups, wherein N=2n+1, N is a natural number, N groups of relay rod lens groups are sequentially arranged from an object side to an image side along an optical axis of the optical imaging system, and each group of relay rod lens groups comprises a rod lens part and a cemented lens part which are mutually separated.

Further, the relay rod lens group comprises a first relay rod lens group, a second relay rod lens group and a third relay rod lens group;

the first relay rod lens group, the second relay rod lens group and the third relay rod lens group are symmetrically arranged along the middle point of the relay rod lens mechanism.

Further, the rod lens portions of the first relay rod lens group and the third relay rod lens group each include a first rod lens and a second rod lens, and the cemented lens portions of the first relay rod lens group and the third relay rod lens group each include a first cemented lens and a second cemented lens;

the first cemented lens, the first rod lens, the second rod lens and the second cemented lens are sequentially arranged from the object side to the image side along the optical axis.

Further, the rod lens portion of the second relay rod lens group includes a third rod lens and a fourth rod lens, and the cemented lens portion of the second relay rod lens group includes a third cemented lens, a fourth cemented lens, a fifth cemented lens, and a sixth cemented lens;

the third cemented lens, the third rod lens, the fourth cemented lens, the fifth cemented lens, the fourth rod lens and the sixth cemented lens are sequentially arranged along the optical axis from an object side to an image side.

Further, the set of rear-end eyepieces includes an object-side telecentric arrangement.

Further, the front end objective lens group comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens which are arranged along the optical axis from the object side to the image side in sequence,

the image side surface and the object side surface of the first lens are aspheric;

the second lens is a steering prism;

the object side surface of the third lens is a plane, and the image side surface of the third lens is a convex surface;

the fourth lens is a five-cemented lens, and the five-cemented lens is sequentially arranged from the object side to the image side as a convex-concave convex lens;

the fifth lens is a double-cemented lens, and the double-cemented lens is sequentially arranged as a convex-concave lens along the object side to the image side.

Further, the optical imaging system satisfies the relation: 1.8.ltoreq.R1+R2)/(R1-R2). Ltoreq.2.1, wherein R1 is the radius of curvature of the object side of the first lens and R2 is the radius of curvature of the image side of the first lens.

Further, the optical imaging system satisfies the relation: and f4/f is not more than 5.9 and not more than 6.3, wherein f4 is the effective focal length of the fourth lens, and f is the effective focal length of the front end objective lens group.

Further, the optical imaging system satisfies the relation: and f rod/f object is not more than 55 and not more than 67, wherein f rod is the effective focal length of the relay rod mirror mechanism, and f object is the effective focal length of the front end objective lens group.

In another aspect, the present application also provides an endoscope comprising the above optical imaging system.

In this application, stick mirror portion and the cemented lens portion in each group relay stick mirror group in the optical imaging system in this application are mutually separated, so set up, more be convenient for process relay stick mirror mechanism, can reduce the accumulation error in the relay stick mirror mechanism course of working to a certain extent. In addition, in the course of working of optical imaging system, relay rod mirror mechanism is because its length is comparatively longer, and the processing degree of difficulty is big and centering difficulty is unfavorable for the assembly, and this application is through making the rod mirror portion and the cemented lens portion separation of each group relay rod mirror group, during the processing, rod mirror portion and lens portion can process respectively, can reduce the processing degree of difficulty of relay rod mirror mechanism greatly, avoided the difficult problem of rod mirror portion centering, during the installation, the relative position of the rod mirror portion and the cemented lens portion that the separation set up can be adjusted, more be convenient for carry out optical imaging system's debugging. Compared with the prior art, the optical imaging system has the advantages that the structure is simpler, the processing and the assembly are more convenient, and the production cost of the optical imaging system can be greatly reduced.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the application and do not constitute an undue limitation to the application. In the drawings:

FIG. 1 is a front view of an optical imaging system disclosed in an embodiment of the present application;

FIG. 2 is a front view of a front end objective lens assembly of an optical imaging system disclosed in an embodiment of the present application;

FIG. 3 is a front view of a first relay rod lens set or a third relay rod lens set of an optical imaging system disclosed in an embodiment of the present application;

FIG. 4 is a front view of a second relay rod lens assembly of an optical imaging system disclosed in an embodiment of the present application;

FIG. 5 is a front view of a back end eyepiece group of an optical imaging system disclosed in an embodiment of this application;

FIG. 6 is a graph of optical modulation transfer functions of an optical imaging system disclosed herein;

FIG. 7 is a distortion chart of an optical imaging system disclosed herein;

FIG. 8 is an astigmatic diagram of an optical imaging system disclosed herein;

FIG. 9 is a graph of relative illuminance of an optical imaging system disclosed herein;

FIG. 10 is a graph of an optical modulation transfer function of another optical imaging system disclosed herein;

FIG. 11 is a distortion chart of another optical imaging system disclosed herein;

FIG. 12 is an astigmatic diagram of another optical imaging system disclosed herein;

fig. 13 is a graph of relative illuminance for another optical imaging system disclosed herein.

Wherein the above figures include the following reference numerals:

10. a front end objective lens group; 11. a first lens; 12. a second lens; 13. a third lens; 14. a fourth lens; 15. a fifth lens; 20. a relay rod mirror mechanism; 21. a first relay rod lens group; 22. the second relay rod lens group; 23. a third relay rod lens group; 221. a third rod mirror; 222. a fourth rod mirror; 223. a third cemented lens; 224. a fourth cemented lens; 225. a fifth cemented lens; 226. a sixth cemented lens; 201. a first rod mirror; 202. a second rod mirror; 203. a first cemented lens; 204. a second cemented lens; 30. a rear eyepiece group; 31. a sixth lens; 32. and a seventh lens.

Detailed Description

It should be noted that, in the case of no conflict, the embodiments and features in the embodiments may be combined with each other. The present application will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular is also intended to include the plural unless the context clearly indicates otherwise, and furthermore, it is to be understood that the terms "comprises" and/or "comprising" when used in this specification are taken to specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof.

The relative arrangement of the components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present application unless it is specifically stated otherwise. Meanwhile, it should be understood that the sizes of the respective parts shown in the drawings are not drawn in actual scale for convenience of description. Techniques, methods, and apparatus known to one of ordinary skill in the relevant art may not be discussed in detail, but should be considered part of the authorization specification where appropriate. In all examples shown and discussed herein, any specific values should be construed as merely illustrative, and not a limitation. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further discussion thereof is necessary in subsequent figures.

Referring to fig. 1-5, an optical imaging system is provided in an embodiment of the present application. The optical imaging system includes a front-end objective lens group 10, a relay rod lens mechanism 20, and a rear-end eyepiece lens group 30, which are disposed in this order from the object side to the image side.

The relay rod lens mechanism 20 includes N relay rod lens groups, where n=2n+1, N is a natural number, for example, 1, 2, 3, 4, etc., the N relay rod lens groups are sequentially disposed from the object side to the image side along the optical axis of the optical imaging system, and each relay rod lens group includes a rod lens portion and a cemented lens portion that are separated from each other.

The rod lens portions and the cemented lens portions in each group of relay rod lens groups in the optical imaging system in this embodiment are separated from each other, so that the relay rod lens mechanism 20 can be more conveniently processed, and the accumulated error in the processing process of the relay rod lens mechanism 20 can be reduced to a certain extent. In addition, in the course of working of optical imaging system, relay rod mirror mechanism 20 is because its length is comparatively longer, and the processing degree of difficulty is big and centering difficulty is unfavorable for the assembly, and this application is through making the rod mirror portion and the cemented lens portion separation of each group relay rod mirror group, during the processing, rod mirror portion and lens portion can process respectively, can reduce the processing degree of difficulty of relay rod mirror mechanism 20 greatly, avoided the difficult problem of rod mirror portion centering, during the installation, the relative position of the rod mirror portion and the cemented lens portion that separate set up can be adjusted, more be convenient for carry out optical imaging system's debugging.

Compared with the prior art, the optical imaging system in the embodiment has simpler structure, is more convenient to process and assemble, and can greatly reduce the production cost of the optical imaging system.

As shown in fig. 1 and 2, the front-end objective lens group 10 in the present embodiment includes a first lens 11, a second lens 12, a third lens 13, a fourth lens 14, and a fifth lens 15 disposed along the optical axis in order from the object side to the image side.

The image side surface and the object side surface of the first lens 11 are aspheric, and the first lens 11 adopts aspheric arrangement, so that distortion of an optical imaging system can be effectively improved, and field curvature of an objective lens end can be optimized to a certain extent. The second lens 12 is a steering prism, and can reasonably arrange the overall structure of the optical imaging system, so that the miniaturized design of the optical imaging system is realized, the steering prism in the embodiment is a 30-degree steering prism (the steering prism is a 0-degree view angle system after being unfolded), and of course, in other embodiments of the application, the steering degree of the steering prism can be designed and selected according to actual use requirements, and the application is not limited specifically. The object side surface of the third lens element 13 is a plane, and the image side surface of the third lens element is a convex surface, so as to facilitate light collection and improve the imaging resolution of the optical imaging system. The fourth lens 14 is a five-cemented lens, which is sequentially arranged from the object side to the image side as convex-concave convex lenses, the materials are arranged in an alternating order of high refractive index (1.7 to 2.0) and low refractive index (1.4 to 1.7), the structure can effectively compress the aperture of the objective lens group, can greatly inhibit the objective lens group from generating excessive field curvature, avoids adverse effect on the optimization of the system field curvature of the rear lens group, and has obvious improvement effect on the chromatic aberration of the system. The fifth lens element 15 is a cemented lens element, which is sequentially arranged from the object side to the image side as a convex-concave lens element, and is disposed between the fourth lens element 14 and the imaging plane of the front-end objective lens assembly 10, and has the main effects of assisting the fourth lens element 14 in optimizing the system curvature, reducing the manufacturing difficulty, facilitating the debugging, and improving the production yield. In addition, the third lens 13, the fourth lens 14 and the fifth lens 15 in the present embodiment are spherical mirrors, which has a simple structure and is convenient for processing.

Further, the optical imaging system in the present embodiment satisfies the relation: 1.8.ltoreq.R1+R2)/(R1-R2). Ltoreq.2.1, e.g. 1.8, 1.9, 2.0, 2.1 etc., wherein R1 is the radius of curvature of the object side of the first lens 11 and R2 is the radius of curvature of the image side of the first lens 11. By controlling the curvature radius of the object side surface and the image side surface of the first lens 11, the situation that the surface type of the first lens 11 is too gentle or too curved is avoided, a light beam from a large angle can be effectively converged, so that image source information of a wide viewing angle is converged and imaged on the human eye side, the deflection angle of light rays at the edge view field is effectively controlled, the total deflection angle of the light rays passing through the object side surface and the image side surface of the first lens 11 is in a reasonable range, the sensitivity of an optical imaging system can be effectively reduced, and meanwhile, the caliber of the optical imaging system can be effectively controlled.

Further, the optical imaging system satisfies the relation: the 5.9.ltoreq.f4/f species.ltoreq.6.3, e.g. 5.9, 6.0, 6.1, 6.2, 6.3 etc. Where f4 is the effective focal length of the fourth lens 14 and f is the effective focal length of the front-end objective lens assembly 10. By controlling the range of the ratio of the effective focal length of the fourth lens 14 to the effective focal length of the optical imaging system, the field curvature of the optical imaging system can be well optimized, the position of the entrance pupil can be controlled, and in addition, the optical imaging system can be made more compact in structure, which is helpful for reducing the total length of the optical imaging system.

Further, the optical imaging system satisfies the relation: 55.ltoreq.f rod/f.ltoreq.67, e.g. 55, 57, 59, 61, 63, 64, 67 etc. Where f rod is the effective focal length of the relay rod mirror mechanism 20 and f is the effective focal length of the front end objective lens assembly 10. The ratio of the effective focal length of the relay rod lens mechanism 20 to the effective focal length of the front end objective lens group 10 is controlled, so that the aberration of the relay rod lens mechanism 20 is balanced, and the tolerance sensitivity of the relay rod lens mechanism 20 is reduced; meanwhile, the incidence angle of the light can be well controlled, and the caliber of the relay rod mirror mechanism 20 can be controlled within a reasonable range.

Referring to fig. 1 to 4, in the actual design process, the relay rod lens mechanism 20 in the present embodiment includes an odd number of relay rod lens groups, and by setting the relay rod lens groups to the odd number, it can be ensured that the image on the image plane of the rear end eyepiece lens group 30 is an upright set image, which is more convenient for the user to observe.

Alternatively, the relay rod lens group in the present embodiment may be configured as 3 groups, 5 groups, 7 groups, or the like, and fig. 1 of the present application shows a case when the relay rod lens group is 3 groups. Specifically, the 3 relay rod lens groups include a first relay rod lens group 21, a second relay rod lens group 22, and a third relay rod lens group 23; the first relay rod lens group 21, the second relay rod lens group 22 and the third relay rod lens group 23 are sequentially arranged along the optical axis from the object side to the image side, and the first relay rod lens group 21, the second relay rod lens group 22 and the third relay rod lens group 23 are symmetrically arranged along the midpoint of the relay rod lens mechanism 20. In this embodiment, the first relay rod lens group 21, the second relay rod lens group 22 and the third relay rod lens group 23 are symmetrically configured, so that the relay rod lens mechanism 20 does not need to distinguish between the front and the back during actual assembly, thereby facilitating the rapid assembly of the optical imaging system and further reducing the production and processing costs of the optical imaging system in this embodiment.

Further, the rod lens portions of the first relay rod lens group 21 and the third relay rod lens group 23 in the present embodiment each include the first rod lens 201 and the second rod lens 202, and the cemented lens portions of the first relay rod lens group 21 and the third relay rod lens group 23 each include the first cemented lens 203 and the second cemented lens 204. Wherein the first cemented lens 203, the first rod mirror 201, the second rod mirror 202, and the second cemented lens 204 are disposed in order from the object side to the image side along the optical axis. That is, the two ends of the rod lens portion in the embodiment are provided with the cemented lens, so that the field curvature of the optical imaging system can be well corrected between the relay rod lens groups, and the imaging quality of the optical imaging system is improved.

The rod lens portions of the first relay rod lens group 21 and the third relay rod lens group 23 in other embodiments of the present application may further include three or more rod lenses, and the two or more rod lenses may meet the optical imaging requirement, and may reduce the production cost of the optical imaging system in this embodiment to some extent.

Optionally, the first cemented lens 203 and the second cemented lens 204 in the present embodiment are double cemented lenses, and the first cemented lens 203 and the second cemented lens 204 are symmetrically disposed about a midpoint of the first cemented lens 203 or the second cemented lens 204, so as to facilitate assembly. The double-cemented lens is assembled by adopting high (refractive index is 1.7-2.0) and low (refractive index is 1.4-1.7) refractive index materials, in particular to a combined structure of a convex lens and a concave lens, so that the field curvature of an optical imaging system can be well improved. In addition, the double-cemented lens is simple in structure and convenient to process, and the production cost of the optical imaging system disclosed by the embodiment of the application can be further reduced. Of course, in other embodiments of the present application, the number of lens blocks of the first and second cemented lenses 203 and 204 may also be designed and selected according to actual use requirements, which is not specifically limited in the present application.

Further, the rod lens portion of the second relay rod lens group 22 in the present embodiment includes a third rod lens 221 and a fourth rod lens 222, and the cemented lens portion of the second relay rod lens group 22 includes a third cemented lens 223, a fourth cemented lens 224, a fifth cemented lens 225, and a sixth cemented lens 226. Wherein a third cemented lens 223, a third rod lens 221, a fourth cemented lens 224, a fifth cemented lens 225, a fourth rod lens 222, and a sixth cemented lens 226 are disposed in order from the object side to the image side along the optical axis. In actual installation, the diaphragm of the optical imaging system is installed between the fourth cemented lens 224 and the fifth cemented lens 225, at this time, the fourth cemented lens 224 and the fifth cemented lens 225 located at two sides of the diaphragm are all double cemented lenses, and the double cemented lenses are assembled by adopting high (refractive index is 1.7 to 2.0) and low (refractive index is 1.4 to 1.7) refractive index materials, specifically, a combined structure of a convex lens and a concave lens, and the fourth cemented lens 224 and the fifth cemented lens 225 can well optimize chromatic aberration of the optical imaging system, so that the pressure of optimizing chromatic aberration of the front end objective lens group 10 is reduced.

Referring to fig. 5, the rear eyepiece 30 of this embodiment includes an object-side telecentric structure with an aperture stop imaged at infinity by the lens in front of it, so that the chief ray is parallel to the optical axis, with the result that the image point is blurred only with unchanged position center on the image plane as the object moves back and forth. The rear-end eyepiece 30 in this embodiment can be used to connect with the relay rod lens mechanism 20, and the virtual image plane of the relay rod lens mechanism 20 is used as the object plane of the rear-end eyepiece 30, so that a high-quality image can be obtained on the final image plane well in combination with an ideal lens group. In the application, a virtual image plane is arranged behind the relay rod lens group, light rays can be well converged on the image plane during tracking, and at the moment, an object space telecentric structure is used, so that the eyepiece group can be well connected; in addition, the field curvature on the virtual image plane at the front end of the rear end eyepiece group 30 is small, and the rear end eyepiece group 30 uses an object side telecentric structure, so that good optical performance on the image plane can be ensured.

Optionally, the rear-end eyepiece group 30 in this embodiment includes a sixth lens 31 and a seventh lens 32, where the sixth lens 31 is a biconvex lens, and the seventh lens 32 is a biconvex lens, so that light rays can be effectively converged on a final image plane after sequentially passing through the biconvex lens and the biconvex lens, and the rear-end eyepiece group has a simple structure and high imaging quality.

The optical imaging system of the present application will be described in detail below by way of specific examples.

Example 1

Referring to fig. 1 to 9, according to a first embodiment of the present application, there is provided an optical imaging system including a front-end objective lens group 10, a relay rod lens mechanism 20, and a rear-end eyepiece group 30, which are disposed in order from an object side to an image side.

The front end objective lens group 10, the relay rod lens mechanism 20 and the rear end eyepiece lens group 30 can be made of glass or plastic or a mixture of the glass and the plastic, so that the optical performance of the optical imaging system can be improved, and the strength and the service life of the optical imaging system can be improved. In actual assembly, the object side surface of the first lens 11 is provided with a protective glass, and the optical imaging system can be protected by the action of the protective glass.

Table 1 is a characteristic table of the optical imaging system in this embodiment, in which the units of radius and thickness are all mm.

Fig. 6 shows an optical modulation transfer function diagram of the optical imaging system in the present embodiment; fig. 7 shows a distortion graph of the optical imaging system disclosed in the present embodiment; FIG. 8 shows an astigmatic curve diagram of an optical imaging system disclosed in this embodiment; fig. 9 shows a relative illuminance map of the optical imaging system disclosed in the present embodiment. Wherein, the abscissa of fig. 7 is the distortion rate (%); the abscissa of fig. 8 is the focal length in mm, X represents sagittal imaging surface curvature, and Y represents meridional imaging surface curvature; the ordinate in fig. 9 is the relative illuminance (%), and the abscissa is the field of view. As can be seen from fig. 6 to 9, the optical imaging system according to the first embodiment can achieve good imaging quality.

Example two

Referring to fig. 1 to 5 and 10 to 13, according to a second embodiment of the present application, an optical imaging system is provided, which includes a front objective lens assembly 10, a relay rod lens mechanism 20, and a rear eyepiece lens assembly 30 sequentially disposed from an object side to an image side.

The front end objective lens group 10, the relay rod lens mechanism 20 and the rear end eyepiece lens group 30 can be made of glass or plastic or a mixture of the glass and the plastic, so that the optical performance of the optical imaging system can be improved, and the strength and the service life of the optical imaging system can be improved. In actual assembly, the object side surface of the first lens 11 is provided with a protective glass, and the optical imaging system can be protected by the action of the protective glass.

Table 2 is a characteristic table of the optical imaging system in this embodiment, in which the units of radius and thickness are all mm.

Fig. 10 shows an optical modulation transfer function diagram of the optical imaging system in the present embodiment; fig. 11 shows a distortion graph of the optical imaging system disclosed in the present embodiment; FIG. 12 shows an astigmatic curve diagram of an optical imaging system disclosed in this embodiment; fig. 13 shows a relative illuminance map of the optical imaging system disclosed in the present embodiment. Wherein, the abscissa of fig. 11 is the distortion rate (%); the abscissa of fig. 12 is the focal length in mm, X represents sagittal imaging surface curvature, and Y represents meridional imaging surface curvature; the ordinate in fig. 13 is the relative illuminance (%), and the abscissa is the field of view. As can be seen from fig. 11 to 13, the optical imaging system according to the second embodiment can achieve good imaging quality.

As can be seen from the above embodiments: the optical imaging system of the invention is respectively a front end objective lens group, a relay rod lens mechanism and a rear end eyepiece lens group along the light propagation direction. The first lens of the front-end objective lens group adopts an aspheric design, so that the distortion of an optical system can be effectively improved, and the front-end objective lens group has a vital effect on field curvature optimization of an objective lens. The other lenses are common spherical mirrors, so that the processing and detection are facilitated. The relay rod lens mechanism comprises three groups of relay rod lens groups, two groups of double-cemented lenses are respectively added at two ends of each group of relay rod lens groups and used for optimizing field curvature, the structures of the first group of relay rod lens groups and the third group of relay rod lens groups are identical, a diaphragm is positioned between the second group of relay rod lens groups, and two groups of double-cemented lenses are respectively arranged at two sides of the diaphragm and used for optimizing chromatic aberration.

The aperture of the optical imaging system is about 10mm, the field angle of the imaging system is about 76 degrees, the optical distortion is smaller than 6 percent, the F22 (focal length f=22mm) bayonet lens is adapted, the field angle of the rear-end eyepiece group is 14.2 degrees, an object side telecentric structure is adopted, light rays can be well converged on the image plane during tracking, and the object side telecentric structure can be well connected with a relay rod lens mechanism; in addition, the field curvature on the virtual image surface of the front end of the rear end eyepiece group is small, and the rear end eyepiece group adopts an object space telecentric structure, so that the good optical performance on the image surface can be ensured.

On the other hand, the embodiment of the present application also provides an endoscope including the above optical imaging system, and therefore, the endoscope includes all the technical effects of the above optical imaging system. Since the technical effects of the optical imaging system have been described in detail in the foregoing, a detailed description thereof will be omitted.

Spatially relative terms, such as "above … …," "above … …," "upper surface at … …," "above," and the like, may be used herein for ease of description to describe one device or feature's spatial location relative to another device or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "above" or "over" other devices or structures would then be oriented "below" or "beneath" the other devices or structures. Thus, the exemplary term "above … …" may include both orientations of "above … …" and "below … …". The device may also be positioned in other different ways (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

In addition, the terms "first", "second", etc. are used to define the components, and are merely for convenience of distinguishing the corresponding components, and unless otherwise stated, the terms have no special meaning, and thus should not be construed as limiting the scope of the present application.

The foregoing is merely a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and variations may be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims (10)

1. An optical imaging system is characterized by comprising a front end objective lens group (10), a relay rod lens mechanism (20) and a rear end eyepiece lens group (30) which are sequentially arranged from an object side to an image side,

the relay rod lens mechanism (20) comprises N groups of relay rod lens groups, N=2n+1, N is a natural number, N groups of relay rod lens groups are sequentially arranged from an object side to an image side along an optical axis of the optical imaging system, and each group of relay rod lens groups comprises a rod lens part and a cemented lens part which are mutually separated.

2. The optical imaging system of claim 1, wherein the relay rod lens group comprises a first relay rod lens group (21), a second relay rod lens group (22), and a third relay rod lens group (23);

the first relay rod lens group (21), the second relay rod lens group (22) and the third relay rod lens group (23) are symmetrically arranged along the middle point of the relay rod lens mechanism (20).

3. The optical imaging system according to claim 2, wherein the rod mirror portions of the first and third relay rod mirror groups (23) each comprise a first rod mirror (201) and a second rod mirror (202), and the cemented lens portions of the first and third relay rod mirror groups (23) each comprise a first cemented lens (203) and a second cemented lens (204);

wherein the first cemented lens (203), the first rod mirror (201), the second rod mirror (202), and the second cemented lens (204) are disposed in order from an object side to an image side along the optical axis.

4. The optical imaging system according to claim 2, wherein the rod lens portion of the second relay rod lens group (22) comprises a third rod lens (221) and a fourth rod lens (222), the cemented lens portion of the second relay rod lens group (22) comprising a third cemented lens (223), a fourth cemented lens (224), a fifth cemented lens (225), and a sixth cemented lens (226);

wherein the third cemented lens (223), the third rod lens (221), the fourth cemented lens (224), the fifth cemented lens (225), the fourth rod lens (222), and the sixth cemented lens (226) are sequentially disposed along the optical axis from an object side to an image side.

5. The optical imaging system of claim 1, wherein the set of rear end eyepieces (30) includes an object-side telecentric structure.

6. Optical imaging system according to any one of claims 1 to 5, characterized in that the front-end objective lens group (10) comprises a first lens (11), a second lens (12), a third lens (13), a fourth lens (14) and a fifth lens (15) arranged along the optical axis in order from the object side to the image side, wherein,

the image side surface and the object side surface of the first lens (11) are aspheric;

the second lens (12) is a steering prism;

the object side surface of the third lens (13) is a plane, and the image side surface is a convex surface;

the fourth lens (14) is a five-cemented lens, and the five-cemented lens is sequentially arranged from an object side to an image side as a convex-concave convex lens;

the fifth lens (15) is a double-cemented lens, which is sequentially arranged as a convex-concave lens from the object side to the image side.

7. The optical imaging system of claim 6, wherein the optical imaging system satisfies the relationship: 1.8.ltoreq.R1+R2)/(R1-R2). Ltoreq.2.1, wherein R1 is the radius of curvature of the object side surface of the first lens (11),

r2 is the radius of curvature of the image side surface of the first lens (11).

8. The optical imaging system of claim 6, wherein the optical imaging system satisfies the relationship: and f4/f is not more than 5.9 and not more than 6.3, wherein f4 is the effective focal length of the fourth lens (14), and f is the effective focal length of the front end objective lens group (10).

9. The optical imaging system of claim 6, wherein the optical imaging system satisfies the relationship: and f rod/f object is not more than 55 and not more than 67, wherein f rod is the effective focal length of the relay rod lens mechanism (20), and f object is the effective focal length of the front end objective lens group (10).

10. An endoscope, characterized in that it comprises the optical imaging system of any one of claims 1 to 9.