CN116859564A

CN116859564A - Visual system

Info

Publication number: CN116859564A
Application number: CN202310983042.0A
Authority: CN
Inventors: 张步康; 梁宁; 游金兴; 张晓彬; 金银芳; 戴付建; 赵烈烽
Original assignee: Zhejiang Sunny Optics Co Ltd
Current assignee: Zhejiang Sunny Optics Co Ltd
Priority date: 2023-08-04
Filing date: 2023-08-04
Publication date: 2023-10-10

Abstract

The invention provides a visual system. The visual system includes a lens barrel, and a first lens group, a first spacer, a second lens group, a second spacer, and a third lens group provided in the lens barrel, the first lens group including a first lens, the second lens group including a second lens, the third lens group including a third lens, a first side of the third lens being a plane, a portion of the first side or the second side of at least one of the first to third lenses having a reflective layer, a gap distance ET23 between a maximum outer diameter D2s of the first side of the second spacer, a minimum inner diameter D2s of the first side of the second spacer, a maximum effective diameter edge of the second side of the second lens, and a maximum effective diameter edge of the first side of the third lens satisfying: 0.6< ((D2 s-D2 s)/2)/ET 23<1.3. The invention solves the problems of overlarge height and difficult stray light improvement of the visual system in the prior art.

Description

Visual system

Technical Field

The invention relates to the technical field of optical imaging equipment, in particular to a visual system.

Background

With the development of virtual reality technology, various virtual reality display devices enter the life of people, for example, VR (virtual reality) head-mounted display devices, where the VR head-mounted display devices generally include a visual system, and the visual system can allow a user to enter the virtual world, and can implement interaction between the virtual world and the real world in combination with a perspective system. The visual system is a virtual reality technology, which utilizes a head-mounted display and a tracking device to make a user feel an immersive virtual world. The system may simulate real world or fictional environments such as game world, virtual travel, scientific research, and the like. The VR visual system has wide application prospects in the fields of games, entertainment, education, medical treatment and the like.

However, the existing visual system has some problems, such as excessively large overall height, difficult miniaturization, and easy generation of stray light in the refraction or reflection transmission process of marginal rays of the last lens in the system, which affects the imaging quality of the system.

That is, the prior art visual system has problems of excessively large height and difficulty in stray light improvement.

Disclosure of Invention

The invention mainly aims to provide a visual system to solve the problems of overlarge height and difficult stray light improvement of the visual system in the prior art.

In order to achieve the above object, according to one aspect of the present invention, there is provided a visual system comprising a lens barrel, and a first lens group, a first spacer, a second lens group, a second spacer, and a third lens group disposed in the lens barrel in this order from a first side to a second side, the first lens group including a first lens, the second lens group including a second lens, the third lens group including a third lens, a first side of the third lens being a plane, a portion of a first side or a second side of at least one of the first to third lenses having a reflective layer, the first side and the second side of the first spacer abutting a second side of the first lens group and a first side portion of the second lens group, respectively, the second spacer abutting the first side portion of the third lens group, a maximum outer diameter D2s of the first side of the second spacer, a minimum inner diameter D2s of the first side of the second spacer, a maximum effective diameter edge of the second side of the second lens, and a maximum effective diameter edge of the second side of the second lens satisfying a gap ET distance between the maximum effective edge of the first side of the third lens and the maximum effective diameter edge 23: 0.6< ((D2 s-D2 s)/2)/ET 23<1.3.

According to another aspect of the present invention, there is provided a visual system including a lens barrel, and a first lens group, a first spacer, a second lens group, a second spacer, and a third lens group disposed in the lens barrel in this order from a first side to a second side, the first lens group including a first lens, the second lens group including a second lens, the third lens group including a third lens, a first side of the third lens being a plane, a portion of a first side or a second side of at least one of the first to third lenses having a reflective layer, the first side and the second side of the first spacer being in abutment with a second side of the first lens group and a first side portion of the second lens group, respectively, the second spacer being in abutment with a first side portion of the third lens group, a radius of curvature R2 of the second side of the first lens, a radius of curvature R4 of the second side of the second lens, a minimum inner diameter d1s of the first side of the first spacer, and a minimum inner diameter d2s of the first side of the second spacer satisfying between: -3< R2/d1s+R4/d2s < -1.

Further, the third lens group further comprises a reflective polarizing element and a quarter wave plate, wherein the reflective polarizing element is in contact with the third lens, and the second side surface of the reflective polarizing element is attached to the first side surface of the quarter wave plate.

Further, the center thickness CT3 of the third lens, the center thickness CTRP of the reflective polarizing element, the center thickness CTQWP of the quarter wave plate, the on-axis distance EP01 from the first side of the barrel to the first side of the first spacer, the center thickness CP1 of the first spacer, the on-axis distance EP12 from the second side of the first spacer to the first side of the second spacer, and the center thickness CP2 of the second spacer satisfy: 1< (CT3+CTRP+CTQWP)/(EP 01+CP1+EP 12+CP2) <1.7.

Further, a portion of the second side of the third lens is plated with a reflective layer.

Further, the maximum length L from the first side of the barrel to the second side of the barrel, the on-axis distance TD from the first side of the first lens to the second side of the third lens, and the effective focal length f of the visual system satisfy: 2<L/TD+L/f <3.

Further, the radius of curvature R2 of the second side surface of the first lens, the radius of curvature R4 of the second side surface of the second lens, the minimum inner diameter d1s of the first side surface of the first spacer, and the minimum inner diameter d2s of the first side surface of the second spacer satisfy: -3< R2/d1s+R4/d2s < -1.

Further, the radius of curvature R2 of the second side surface of the first lens, the center thickness CT1 of the first lens, and the on-axis distance EP01 from the first side surface of the barrel to the first side surface of the first spacer satisfy: 7< (CT 1-R2)/EP 01<17.

Further, the radius of curvature R4 of the second side of the second lens, the on-axis distance EP12 from the second side of the first spacer to the first side of the second spacer, the center thickness CT2 of the second lens, and the refractive index N2 of the second lens satisfy: -10< r 4/(ep12+ct2) N2< -7.

Further, the effective focal length f of the visual system, the maximum length L from the first side surface of the lens barrel to the second side surface of the lens barrel and half of the maximum field angle semi-fov of the visual system satisfy the following conditions: 1.1< f tan (semi-fov)/L <1.5.

Further, the radius of curvature R6 of the second side surface of the three lenses, the effective focal length f3 of the third lens, the maximum outer diameter D0m of the second side surface of the lens barrel, and the minimum inner diameter D0s of the first side surface of the lens barrel satisfy: -5< R6/f3-D0m/D0s < -4 >.

Further, the effective focal length f3 of the third lens, the minimum inner diameter d0m of the second side surface of the lens barrel, and the minimum inner diameter d1m of the second side surface of the first spacer satisfy: 1< f 3/(d 0m-d1 m) <1.5.

Further, when the gap distance ET23 from the maximum effective diameter edge of the second side surface of the second lens to the maximum effective diameter edge of the first side surface of the third lens satisfies: when ET23>6mm, the vision system further includes a second auxiliary spacer located on the second side of the second lens and bearing against the first side portion of the second spacer.

Further, the gap distance ET23 between the center thickness CP2b of the second auxiliary spacer, the center thickness CP2 of the second spacer, the maximum effective diameter edge of the second side face of the second lens and the maximum effective diameter edge of the first side face of the third lens satisfies: 0.8< CP2b/ET23-CP2/ET23 is less than or equal to 1.

Further, the maximum outer diameter D2s of the first side of the second spacer, the maximum outer diameter D2bs of the first side of the second auxiliary spacer, the central thickness CTRP of the reflective polarizing element, and the central thickness CTQWP of the quarter wave plate satisfy: 15< (D2 s-D2 bs)/(CTRP+CTQWP) <26.

Further, the maximum outer diameter D2bs of the first side surface of the second auxiliary spacer, the maximum outer diameter D2bm of the second side surface of the second auxiliary spacer, the effective focal length f2 of the second lens, and the effective focal length f3 of the third lens satisfy: -5< f2/d2bs+f3/d2bm < -2.

Further, the center thickness CT2 of the second lens, the center thickness CT3 of the third lens, the center thickness CP2b of the second auxiliary spacer, and the center thickness CP2 of the second spacer satisfy: 2< (CT2+CT3)/(CP2b+CP2) <4.

Further, the abbe number V1 of the first lens and the abbe number V3 of the third lens satisfy: 0.8< V1/V3<1.1.

By applying the technical scheme of the invention, the visual system comprises a lens barrel, a first lens group, a first spacer, a second lens group, a second spacer and a third lens group which are sequentially arranged in the lens barrel from a first side to a second side, wherein the first lens group comprises a first lens, the second lens group comprises a second lens, the third lens group comprises a third lens, the first side surface of the third lens is a plane, a reflecting layer is arranged on a part of the first side surface or the second side surface of at least one of the first lens to the third lens, the first side surface and the second side surface of the first spacer are respectively abutted with the second side surface of the first lens group and the first side surface part of the second lens group, the second spacer is abutted with the first side surface part of the third lens group, and the maximum outer diameter D2s of the first side surface of the second spacer, the minimum inner diameter D2s of the first side surface of the second spacer, and the maximum effective diameter edge of the second side surface of the second lens meet a gap distance ET23 between the maximum effective diameter edge of the first side surface of the third lens and the second side surface of the third lens: 0.6< ((D2 s-D2 s)/2)/ET 23<1.3.

The visual system is provided with three lenses and two spacers matched with the three lenses, so that the effective focal length of the system is distributed at a reasonable level, the overall height of the visual system is prevented from being too high, and the miniaturization is facilitated. Through setting up the plane of the first side of third lens, simultaneously through the biggest and minimum internal diameter of the first side of second spacer and the edge interval of second lens and third lens, on the one hand avoid the complicated technology of curved surface pad pasting, improve the production yield, on the basis of can guaranteeing second spacer workability in addition, make the second spacer can intercept the edge parasitic light, reduce the production of system parasitic light, improve system imaging quality, further through the buffer characteristic of second spacer material, avoid follow-up reflective polarizing element and quarter wave plate and rigid plastic direct contact, improve the vibration resistance and the reliability ability of falling of visual system.

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 specification, illustrate embodiments of the application and together with the description serve to explain the application. In the drawings:

FIG. 1 illustrates a sizing diagram of a visual system of an alternative embodiment of the present application;

FIG. 2 illustrates an optical path profile of a vision system of example one of the present disclosure;

FIG. 3 is a schematic view showing a first state of the visual system according to the first example of the present application;

FIG. 4 is a schematic diagram showing the configuration of the vision system of example one of the present disclosure in a second state;

FIG. 5 is a schematic view showing a structure of a visual system according to an example I of the present application in a third state;

FIGS. 6 to 8 show on-axis chromatic aberration curves, astigmatism curves, distortion curves, respectively, of the visual system of example one;

FIG. 9 illustrates an optical path profile of a vision system of example two of the present application;

FIG. 10 is a schematic diagram showing the structure of a visual system of example II of the present application in a first state;

FIG. 11 is a schematic diagram showing the structure of the visual system of example II of the present application in a second state;

FIG. 12 is a schematic diagram showing the structure of a visual system according to example II of the present application in a third state;

Fig. 13 to 15 show an on-axis chromatic aberration curve, an astigmatic curve, and a distortion curve, respectively, of the visual system of example two;

FIG. 16 illustrates an optical path profile of a vision system of example three of this application;

FIG. 17 is a schematic diagram showing the configuration of the vision system of example three of this application in a first state;

FIG. 18 shows a schematic diagram of a visual system of example III of the present application in a second state;

FIG. 19 is a schematic view showing the structure of the visual system of example III of the present application in a third state;

fig. 20 to 22 show an on-axis chromatic aberration curve, an astigmatic curve, and a distortion curve of the visual system of example three, respectively.

Detailed Description

It should be noted that, without conflict, the embodiments of the present application and features of the embodiments may be combined with each other. The application will be described in detail below with reference to the drawings in connection with embodiments.

It is noted that all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs unless otherwise indicated.

In the present application, unless otherwise indicated, terms of orientation such as "upper, lower, top, bottom" are used generally with respect to the orientation shown in the drawings or with respect to the component itself in the vertical, upright or gravitational direction; also, for ease of understanding and description, "inner and outer" refers to inner and outer relative to the profile of each component itself, but the above-mentioned orientation terms are not intended to limit the present application.

It should be noted that in the present specification, the expressions of first, second, third, etc. are only used to distinguish one feature from another feature, and do not represent any limitation on the feature. Accordingly, a first lens discussed below may also be referred to as a second lens or a third lens without departing from the teachings of the present application.

In the drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for convenience of explanation. Specifically, the spherical or aspherical shape shown in the drawings is shown by way of example. That is, the shape of the spherical or aspherical surface is not limited to the shape of the spherical or aspherical surface shown in the drawings. The figures are merely examples and are not drawn to scale.

Herein, the paraxial region refers to a region near the optical axis. If the lens surface is convex and the convex position is not defined, then the lens surface is convex at least in the paraxial region; if the lens surface is concave and the concave position is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens adjacent to the first side becomes the first side of the lens and the surface of each lens adjacent to the second side is referred to as the second side of the lens. The determination of the surface shape in the paraxial region can be performed by a determination method by a person skilled in the art by positive or negative determination of the concave-convex with R value (R means the radius of curvature of the paraxial region, and generally means the R value on a lens database (lens data) in optical software). The first side face is determined to be convex when the R value is positive, and is determined to be concave when the R value is negative; the second side face is determined to be concave when the R value is positive, and is determined to be convex when the R value is negative.

The left side of the visual system is a first side, the right side of the visual system is a second side, the first side of the visual system is a second side, the second side is a light source side, and an image emitted by the light source side is imaged on the second side.

The invention provides a visual system for solving the problems of overlarge height and difficult stray light improvement of the visual system in the prior art.

Example 1

As shown in fig. 1 to 22, the visual system includes a lens barrel, and a first lens group, a first spacer, a second lens group, a second spacer, and a third lens group provided in this order in the lens barrel from a first side to a second side, the first lens group including a first lens, the second lens group including a second lens, the third lens group including a third lens, a first side surface of the third lens being a plane, a portion of a first side surface or a second side surface of at least one of the first lens to the third lens having a reflective layer, the first side surface and the second side surface of the first spacer being in abutment with the second side surface of the first lens group and the first side surface portion of the second lens group, respectively, the second spacer being in abutment with the first side surface portion of the third lens group, a maximum outer diameter D2s of the first side surface of the second spacer, a minimum inner diameter D2s of the first side surface of the second spacer, a gap distance ET between a maximum effective diameter edge of the second side surface of the second lens and a maximum effective diameter edge of the first side surface of the third lens satisfying a gap ET 23: 0.6< ((D2 s-D2 s)/2)/ET 23<1.3.

In this embodiment, the third lens group further includes a reflective polarizing element and a quarter wave plate in contact with the third lens, and the second side of the reflective polarizing element is attached to the first side of the quarter wave plate. The quarter wave plate can change the polarization state of light, and is matched with the reflective polarizing element, so that the refraction and reflection of the light path can be realized, the length of the light path is shortened, the overall height of the visual system is compressed, the small size is realized, and the miniaturization is satisfied. The composite film is formed by the reflective polarizing element and the quarter wave plate, so that one-time film sticking is realized, the complex process caused by multiple film sticking is avoided, and the production yield is improved.

In the present embodiment, the center thickness CT3 of the third lens, the center thickness CTRP of the reflective polarizing element, the center thickness CTQWP of the quarter wave plate, the on-axis distance EP01 from the first side face of the barrel to the first side face of the first spacer, the center thickness CP1 of the first spacer, the on-axis distance EP12 from the second side face of the first spacer to the first side face of the second spacer, and the center thickness CP2 of the second spacer satisfy: 1< (CT3+CTRP+CTQWP)/(EP 01+CP1+EP 12+CP2) <1.7. By restricting this relation, the third lens group is restricted from occupying the center distance of the entire system, and by restricting the center thickness of the third lens, the optical path returning length is controlled, so that the lens barrel can be made to satisfy miniaturization. Meanwhile, the axial distance from the first side face of the lens barrel to the first side face of the first spacer, the axial distance from the second side face of the first spacer to the first side face of the second spacer and the center thickness of the first spacer and the center thickness of the second spacer are controlled, so that the edge thicknesses of the first lens and the second lens are at reasonable level while the processability of the first spacer and the second spacer is ensured, and the assembly is facilitated.

In this embodiment, a portion of the second side of the third lens is plated with a reflective layer. The reflecting layer is plated on the second side surface of the third lens, so that the light which is reflected by the reflecting polarizing element for the first time is reflected for the second time, the reflection of the light path is realized, the distance of the light path along the optical axis direction is shortened under the condition that the same angle of view is obtained, the thickness of a visual system is reduced, the volume of the visual system applied to equipment is reduced, and the use experience of a user is improved.

In the present embodiment, the maximum length L from the first side of the lens barrel to the second side of the lens barrel, the on-axis distance TD from the first side of the first lens to the second side of the third lens, and the effective focal length f of the visual system satisfy: 2<L/TD+L/f <3. By controlling the relation, the effective focal length of the visual system is controlled, so that the aberration of the system is at a reasonable level, and the imaging of the system is facilitated. Further controlling the maximum length from the first side to the second side of the lens barrel is beneficial to the molding of the lens barrel and the miniaturization of the whole lens barrel.

In the present embodiment, the radius of curvature R2 of the second side surface of the first lens, the radius of curvature R4 of the second side surface of the second lens, the minimum inner diameter d1s of the first side surface of the first spacer, and the minimum inner diameter d2s of the first side surface of the second spacer satisfy: -3< R2/d1s+R4/d2s < -1. By controlling the relation, the curvature radius of the second side surfaces of the first lens and the second lens is limited, the sensitivity of the first lens and the second lens is reduced, the assembly yield is improved, and meanwhile, the minimum inner diameter of the first side surface of the first spacer and the minimum inner diameter of the first side surface of the second spacer are controlled, so that the luminous flux of the system is controlled, and the angle of view of the system is at a reasonable level.

In the present embodiment, the radius of curvature R2 of the second side surface of the first lens, the center thickness CT1 of the first lens, and the on-axis distance EP01 from the first side surface of the lens barrel to the first side surface of the first spacer satisfy: 7< (CT 1-R2)/EP 01<17. By controlling the relation, the curvature radius of the second side surface of the first lens and the center thickness of the first lens are controlled, and the light beam converging capability of the first lens is improved under the condition that the processability of the first lens is met. The axial distance from the first side surface of the lens barrel to the first side surface of the first spacer is further combined, so that the edge thickness of the first lens is at a reasonable level, and the assembly stability is improved.

In the present embodiment, the radius of curvature R4 of the second side of the second lens, the on-axis distance EP12 from the second side of the first spacer to the first side of the second spacer, the center thickness CT2 of the second lens, and the refractive index N2 of the second lens satisfy: -10< r 4/(ep12+ct2) N2< -7. By controlling this relation, the radius of curvature of the second side of the second lens, the center thickness of the second lens, and the refractive index of the second lens are controlled, and the optical power of the second lens is made to be at a reasonable level while satisfying the first lens workability. The axial distance from the second side surface of the first spacer to the first side surface of the second spacer is further controlled, so that the edge thickness of the second lens is at a reasonable level, and the stability of the assembly system is guaranteed.

In this embodiment, the effective focal length f of the visual system, the maximum length L from the first side of the lens barrel to the second side of the lens barrel, and half of the maximum field angle semi-fov of the visual system satisfy: 1.1< f tan (semi-fov)/L <1.5. By controlling the relation, the effective focal length of the visual system is controlled, so that the imaging quality is improved, and the maximum length from the first side face to the second side face of the lens barrel and half of the maximum field angle of the visual system are controlled, so that the light beam is restrained, the large field of view FOV is obtained, and the use experience of a user is improved.

In the present embodiment, the radius of curvature R6 of the second side surface of the three lenses, the effective focal length f3 of the third lens, the maximum outer diameter D0m of the second side surface of the lens barrel, and the minimum inner diameter D0s of the first side surface of the lens barrel satisfy: -5< R6/f3-D0m/D0s < -4 >. By the relation, the curvature radius of the second side surface of the third lens and the effective focal length of the third lens are controlled, and the focal power of the third lens is made to be at a reasonable level under the condition that the processability of the third lens is satisfied. The maximum outer diameter of the second side surface of the lens barrel and the minimum inner diameter of the first side surface of the lens barrel are further controlled in a combined mode, so that light beams can be restrained, and the influence of stray light is reduced under the condition that the view angle meeting design requirements is obtained.

In the present embodiment, the effective focal length f3 of the third lens, the minimum inner diameter d0m of the second side surface of the lens barrel, and the minimum inner diameter d1m of the second side surface of the first spacer satisfy: 1< f 3/(d 0m-d1 m) <1.5. By controlling the relation, the focal power of the third lens is controlled to be at a reasonable level, and the minimum inner diameter of the second side surface of the lens barrel and the minimum inner diameter of the second side surface of the first spacer are further controlled, so that the light beam is restrained, the optimization of stray light is facilitated, and the imaging quality is improved.

In the present embodiment, when the gap distance ET23 from the maximum effective diameter edge of the second side surface of the second lens to the maximum effective diameter edge of the first side surface of the third lens satisfies: when ET23>6mm, the vision system further includes a second auxiliary spacer located on the second side of the second lens and bearing against the first side portion of the second spacer. The gap distance from the maximum effective diameter edge of the second side surface of the second lens to the maximum effective diameter edge of the first side surface of the third lens influences the assembly and application of the quarter wave plate and the reflective polarizing element, when the distance is too small, the requirement on the thickness of the film material is high, the production and the assembly of the film material are not facilitated, when the distance is too large, the assembly with the second lens and the third lens is considered, a second auxiliary spacer is required to be added, and the assembly stability is met.

In the present embodiment, the gap distance ET23 between the center thickness CP2b of the second auxiliary spacer, the center thickness CP2 of the second spacer, the maximum effective diameter edge of the second side face of the second lens and the maximum effective diameter edge of the first side face of the third lens satisfies: 0.8< CP2b/ET23-CP2/ET23 is less than or equal to 1. Through the relation, the thickness of the second auxiliary spacer and the second spacer is controlled, the forming of the second auxiliary spacer and the assembly stability of the second spacer are improved, and meanwhile, the sum of the thicknesses of the second auxiliary spacer, the second spacer, the reflective polarizing element and the quarter wave plate is in a reasonable range through controlling the gap distance from the maximum effective diameter edge of the second side face of the second lens to the maximum effective diameter edge of the first side face of the third lens, so that overlong system is avoided.

In the present embodiment, the maximum outer diameter D2s of the first side surface of the second spacer, the maximum outer diameter D2bs of the first side surface of the second auxiliary spacer, the central thickness CTRP of the reflective polarizing element, and the central thickness CTQWP of the quarter wave plate satisfy: 15< (D2 s-D2 bs)/(CTRP+CTQWP) <26. The center thickness of the reflective polarizing element and the center thickness of the quarter wave plate are controlled, so that the planar attachment of the quarter wave plate and the reflective polarizing element is facilitated, and the attachment yield is improved; and simultaneously, the maximum outer diameter of the first side surface of the second spacer and the maximum outer diameter of the first side surface of the second auxiliary spacer are controlled, so that the external dimension of the lens barrel is in a reasonable range, and the miniaturized design of the head display device applied by the visual system is facilitated.

In the present embodiment, the maximum outer diameter D2bs of the first side surface of the second auxiliary spacer, the maximum outer diameter D2bm of the second side surface of the second auxiliary spacer, the effective focal length f2 of the second lens, and the effective focal length f3 of the third lens satisfy: -5< f2/d2bs+f3/d2bm < -2. By this relation, the maximum outer diameters of the first side and the second side of the second auxiliary spacer are controlled, which is advantageous for bearing against the second lens and the second spacer, and for assembly stability. And meanwhile, the effective focal lengths of the second lens and the third lens are controlled, so that the aberration of the system is at a reasonable level, and the imaging of the system is facilitated.

In the present embodiment, the center thickness CT2 of the second lens, the center thickness CT3 of the third lens, the center thickness CP2b of the second auxiliary spacer, and the center thickness CP2 of the second spacer satisfy the following conditions: 2< (CT2+CT3)/(CP2b+CP2) <4. The relative positional relation among the second lens, the third lens, the second auxiliary spacer and the second spacer in the lens barrel can be adjusted by the relational expression, and the effective focal length of the second lens and the third lens can be controlled within a certain range, so that the imaging quality of the system on the axis is good.

In the present embodiment, the abbe number V1 of the first lens and the abbe number V3 of the third lens satisfy: 0.8< V1/V3<1.1. The abbe number of the first lens and the abbe number of the third lens are controlled, chromatic aberration of the system is corrected, imaging quality of the visual system is improved, and wearing experience of a user is better.

Example two

As shown in fig. 1 to 22, the visual system includes a lens barrel, and a first lens group, a first spacer, a second lens group, a second spacer, and a third lens group provided in this order in the lens barrel from a first side to a second side, the first lens group including a first lens, the second lens group including a second lens, the third lens group including a third lens, a first side surface of the third lens being a plane, a portion of a first side surface or a second side surface of at least one of the first to third lenses having a reflective layer, the first side surface and the second side surface of the first spacer being in abutment with the second side surface of the first lens group and the first side surface portion of the second lens group, respectively, the second spacer being in abutment with the first side surface portion of the third lens group, a radius of curvature R2 of the second side surface of the first lens, a radius of curvature R4 of the second side surface of the second lens, a minimum inside diameter d1s of the first side surface of the first spacer, and a minimum inside diameter d2s of the first side surface of the second spacer being satisfied: -3< R2/d1s+R4/d2s < -1.

The visual system is provided with three lenses and two spacers matched with the three lenses, so that the effective focal length of the system is distributed at a reasonable level, the overall height of the visual system is prevented from being too high, and the miniaturization is facilitated. The plane of the first side surface of the third lens is arranged, the curvature radius of the second side surfaces of the first lens and the second lens is restrained, the sensitivity of the first lens and the second lens is reduced, the assembly yield is improved, the minimum inner diameter of the first side surface of the first spacer and the minimum inner diameter of the first side surface of the second spacer are controlled, the luminous flux of the system is controlled, and the view angle of the system is at a reasonable level.

Other parameter formulas in the first embodiment may also be included in the present embodiment, and will not be described here again.

The vision system in the present application may employ multiple lenses, such as the three described above. By reasonably distributing the effective focal length, the surface shape, the center thickness of each lens, the axial distance between each lens and the like, the sensitivity of the system can be effectively reduced, the machinability of the lens can be improved, and the visual system is more beneficial to production and machining and can be suitable for VR head-mounted equipment.

In the present application, at least one of the mirror surfaces of each lens is an aspherical mirror surface. The aspherical lens is characterized in that: the curvature varies continuously from the center of the lens to the periphery of the lens. Unlike a spherical lens having a constant curvature from the center of the lens to the periphery of the lens, an aspherical lens has a better radius of curvature characteristic, and has advantages of improving distortion aberration and improving astigmatic aberration. By adopting the aspherical lens, aberration occurring at the time of imaging can be eliminated as much as possible, thereby improving imaging quality.

However, those skilled in the art will appreciate that the number of lenses making up the vision system may be varied to achieve the various results and advantages described in this specification without departing from the scope of the application as claimed. For example, although three lenses are described as an example in the embodiment, the visual system is not limited to including three lenses. The vision system may also include other numbers of lenses, if desired.

FIG. 1 illustrates a parametric representation of a visual system according to an alternative embodiment of the present application. Parameters D2bm, D2bs, D2s, D1m, D1s, D0m, L, CP2b, CP2, EP01, CP1, EP01, etc. are indicated in fig. 1, so that the meaning of the parameters is clearly and intuitively understood. In order to facilitate the presentation of the visual system configuration and the specific surface type, these parameters will not be further shown in the drawings when specific examples are described below.

Examples of specific aspects, parameters, of the visual system applicable to the above-described embodiments are further described below with reference to the accompanying drawings.

In the following examples, the first state, the second state, and the third state are present, and parameters such as the radius of curvature, the center thickness, and the like of the first lens, the second lens, and the third lens of the visual system, and the distance between the lenses and the high order image coefficient thereof in the first state, the second state, and the third state in the same example are the same, but the parameters such as the lens barrel P0, the thickness of the spacer, the maximum thickness of the spacer, the inner diameter of the spacer, and the outer diameter of the spacer, and the distance between the spacers are different, and the shape of a part of the lenses is different. Or the primary structure for imaging is the same, while the secondary structure for imaging is different.

Any of the following examples one to three is applicable to all embodiments of the present application.

Example one

As shown in fig. 2 to 8, a visual system of example one of the present application is described. Fig. 2 shows a schematic optical path diagram of the vision system of example one, fig. 3 shows a schematic configuration of the vision system of example one in a first state, fig. 4 shows a schematic configuration of the vision system of example one in a second state, and fig. 5 shows a schematic configuration of the vision system of example one in a third state.

As shown in fig. 3 to 5, the visual system includes a lens barrel P0, and a first lens E1, a first spacer P1, a second lens E2, a second spacer P2, a reflective polarizing element RP, a quarter wave plate QWP, and a third lens E3, which are sequentially disposed in the lens barrel P0 from a first side to a second side.

In fig. 3 to 5, the first side surface and the second side surface of the first spacer P1 are respectively in contact with the second side surface S2 of the first lens and the first side surface S3 of the second lens, and the outer peripheral edge of the first spacer P1 is in contact with the inner wall surface portion of the lens barrel P0. The first side surface and the second side surface of the second spacer P2 are respectively in contact with the inner wall surface of the lens barrel P0 and the first side surface portion of the reflective polarizing element RP, and the outer periphery of the second spacer P2 is in contact with the inner wall surface portion of the lens barrel P0.

As shown in fig. 2, the light propagation path of the visual system is: the light emitted by the light emitting surface S9 of the light source is incident on the second side surface of the reflective polarizing element RP after passing through the third lens E3 and the quarter wave plate QWP, and is reflected for the first time, the light reflected for the first time is incident on the third lens E3 after passing through the quarter wave plate QWP, and is reflected for the second time on the partial reflecting layer of the second side surface of the third lens, and the light reflected for the second time is imaged at the stop position after passing through the first side surface S7 of the third lens, the quarter wave plate QWP, the reflective polarizing element RP, the second lens E2, and the first lens E1 in sequence.

In summary, the structural parameters of the visual system of example one in the first, second and third states 1-1, 1-2 and 1-3 are shown in reference to Table 1 in units of: mm.

Parameters/states	1-1	1-2	1-3
				d1s	44.59	43.42	44.58
d1m	44.59	43.42	44.58
				d2s	54.99	59.09	54.47
D2s	69.57	69.85	62.38
				d0s	42.41	41.41	42.56
d0m	75.44	73.44	71.87
				D0m	78.01	76.01	74.04
EP01	4.79	5.18	4.81
				CP1	0.03	0.05	0.05
EP12	6.97	7.07	7.15
				CP2	0.05	0.05	0.03
L	31.08	30.83	30.53

TABLE 1

In the first example, the first side S1 of the first lens is concave, and the second side S2 of the first lens is convex. The first side S3 of the second lens is concave, and the second side S4 of the second lens is convex. The first side S7 of the third lens is a plane, and the second side S8 of the third lens is a convex surface.

In example one, the effective focal length F of the visual system is 29.70mm, the effective focal length F1 of the first lens is 280.40mm, the effective focal length F2 of the second lens is 144.30mm, the effective focal length F3 of the third lens is 38.55mm, half of the maximum field angle of the visual system semi-fov is 53.00 °, and the F-number Fno of the visual system is 5.94.

Table 2 shows a basic structural parameter table for the visual system of example one, in which the radius of curvature and the thickness are each in millimeters (mm). The order of the surface numbers in the following table is opposite to the actual light path, and the light emitted from the light emitting surface S9 of the light source is imaged at the stop STO. For ease of understanding, S5 may be represented as the first side of the reflective polarizer RP, S6 may be represented as the common plane of the reflective polarizer RP and the quarter wave plate QWP, and S7 may also be represented as the common plane of the quarter wave plate QWP and the first side of the third lens in table 2.

Face number

Surface type

Radius of curvature

Thickness of (L)

Refractive index

Coefficient of dispersion

Refraction/reflection

STO

Diaphragm (STO)

Spherical surface

15

S1

First lens (E1)

Aspherical surface

-151.9822

2.3402

1.57

63.2

Refraction by refraction

S2

Aspherical surface

-74.9156

0.1000

Refraction by refraction

S3

Second lens (E2)

Aspherical surface

-174.8283

4.3699

1.49

70.4

Refraction by refraction

S4

Aspherical surface

-54.8911

0.1000

Refraction by refraction

S5

Reflective polarizing element (RP)

Spherical surface

Infinity is provided

0.2000

1.50

57.0

Refraction by refraction

S6

Quarter Wave Plate (QWP)

Spherical surface

Infinity is provided

0.2000

1.50

57.0

Refraction by refraction

S7

Third lens (E3)

Spherical surface

Infinity is provided

18.3343

1.58

62.9

Refraction by refraction

S8

Partially reflective layer (BS)

Aspherical surface

-120.6087

-18.3343

Reflection of

S7

Quarter Wave Plate (QWP)

Spherical surface

Infinity is provided

-0.2000

1.50

57.0

Refraction by refraction

S6

Reflective polarizing element (RP)

Spherical surface

Infinity is provided

0.2000

Reflection of

S7

Third lens (E3)

Spherical surface

Infinity is provided

18.3343

1.58

62.9

Refraction by refraction

S8

Aspherical surface

-120.6087

2.8399

Refraction by refraction

S9

Light source

Spherical surface

Infinity is provided

TABLE 2

In the first example, the two side surfaces of the first lens E1 and the second lens E2 and the second side surface S8 of the third lens are aspheric, and the surface shape of each aspheric lens can be defined by, but not limited to, the following aspheric equation:

Wherein z is the depth of the aspheric surface (the point on the aspheric surface at a distance y from the optical axis, the tangent plane tangent to the vertex on the aspheric surface, the perpendicular distance between the two); c is the curvature of the aspherical apex; k is the coefficient of the conical surface,is the radial distance; u is r/r _n ；r _n Is normalized radius; a, a _m Is the mth order Q ^con Coefficients; q (Q) ^con Is the mth order Q ^con A polynomial. The polynomial coefficients A3, A4, A5, A6, A7 that can be used for each of the aspherical mirrors S1-S8 in example one are given in Table 3 below.

Face number	A3	A4	A5	A6	A7
						S1	2.0498E+01	-2.3269E-01	-6.8805E-02	-7.5545E-03	-6.1529E-04
S2	3.1231E+01	-4.1706E-01	-1.0741E-01	1.0812E-02	-1.5358E-02
						S3	2.8767E+01	4.8343E-01	7.7260E-02	-1.8051E-02	-7.7906E-03
S4	2.2560E+01	-7.9322E-02	1.2777E-02	-7.5707E-04	1.7088E-03
						S8	2.7174E+01	5.9635E-02	-9.8518E-03	-1.2806E-03	3.5058E-05

TABLE 3 Table 3

FIG. 6 shows an on-axis chromatic aberration curve for a vision system of example one, which indicates the focus offset of light rays of different wavelengths after passing through the vision system. Fig. 7 shows an astigmatic curve of the visual system of example one, which represents meridional image surface curvature and sagittal image surface curvature. Fig. 8 shows distortion curves of the visual system of example one, which represent distortion magnitude values corresponding to different angles of view.

As can be seen from fig. 6 to 8, the visual system of example one can achieve good imaging quality.

Example two

As shown in fig. 9 to 15, a visual system of example two of the present application is described. Fig. 9 shows a schematic optical path diagram of the visual system of example two, fig. 10 shows a schematic structural diagram of the visual system of example two in a first state, fig. 11 shows a schematic structural diagram of the visual system of example two in a second state, and fig. 12 shows a schematic structural diagram of the visual system of example two in a third state.

As shown in fig. 10 to 12, the visual system includes a lens barrel P0, and a first lens E1, a first spacer P1, a second lens E2, a second auxiliary spacer P2b, a second spacer P2, a reflective polarizing element RP, a quarter wave plate QWP, and a third lens E3, which are sequentially disposed in the lens barrel P0 from the first side to the second side.

In fig. 10 to 12, the first side surface and the second side surface of the first spacer P1 are respectively in contact with the second side surface S2 of the first lens and the first side surface S3 of the second lens, and the outer peripheral edge of the first spacer P1 is in contact with the inner wall surface portion of the lens barrel P0. The first side surface and the second side surface of the second auxiliary spacer P2b are respectively abutted against the second side surface S4 of the second lens and the first side surface portion of the second spacer P2, the second side surface of the second spacer P2 is abutted against the first side surface portion of the reflective polarizing element RP, and the outer peripheral edges of the second auxiliary spacer P2b and the second spacer P2 are respectively abutted against the inner wall surface portion of the lens barrel P0.

As shown in fig. 9, the light propagation paths of the visual system are: the light emitted by the light emitting surface S9 of the light source is incident on the second side surface of the reflective polarizing element RP after passing through the third lens E3 and the quarter wave plate QWP, and is reflected for the first time, the light reflected for the first time is incident on the third lens E3 after passing through the quarter wave plate QWP, and is reflected for the second time on the partial reflecting layer of the second side surface of the third lens, and the light reflected for the second time is imaged at the stop position after passing through the first side surface S7 of the third lens, the quarter wave plate QWP, the reflective polarizing element RP, the second lens E2, and the first lens E1 in sequence.

In summary, the structural parameters of the visual system of example two in the first state 2-1, the second state 2-2, and the third state 2-3 are shown in reference to Table 4 in units of: mm.

Parameters/states	2-1	2-2	2-3
				d1s	43.42	43.42	42.42
d1m	43.42	43.42	42.42
				d2s	54.08	54.08	54.08
D2s	66.40	64.40	63.80
				D2bs	59.36	57.83	54.21
D2bm	59.11	58.34	58.51
				d0s	42.68	41.20	41.20
d0m	73.44	71.16	69.96
				D0m	76.01	73.73	70.93
EP01	4.38	3.58	3.71
				CP1	0.05	0.11	0.03
EP12	7.88	7.76	7.79
				CP2	0.05	0.11	0.03
CP2b	6.05	5.69	5.66
				L	30.81	28.58	28.58

TABLE 4 Table 4

In the second example, the first side S1 of the first lens is concave, and the second side S2 of the first lens is convex. The first side S3 of the second lens is concave, and the second side S4 of the second lens is convex. The first side S7 of the third lens is a plane, and the second side S8 of the third lens is a convex surface.

In example two, the effective focal length F of the visual system is 28.00mm, the effective focal length F1 of the first lens is 60.00mm, the effective focal length F2 of the second lens is-200.33 mm, the effective focal length F3 of the third lens is 37.95mm, half of the maximum field angle semi-fov of the visual system is 53.00 °, and the F number FNo of the visual system is 5.60.

Table 5 shows a basic structural parameter table for the visual system of example two, where the radius of curvature and thickness are each in millimeters mm. For ease of understanding, in table 5, S5 may be denoted as the first side of the reflective polarizing element RP, S6 may be denoted as the common plane of the reflective polarizing element RP and the quarter wave plate QWP, and S7 may also be denoted as the common plane of the quarter wave plate QWP and the first side of the third lens.

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TABLE 5

Table 6 shows polynomial coefficients that can be used for each aspherical surface in example two, where each aspherical surface profile can be defined by equation (1) given in example one above.

Face number	A3	A4	A5	A6	A7
						S1	2.7656E+01	2.7019E+00	-1.5625E-02	-2.2225E-01	1.0797E-01
S2	2.7372E+01	-2.2417E+00	2.1763E-01	3.4561E-01	-2.6918E-01
						S3	1.7869E+01	-2.3320E-01	-6.8649E-02	-2.4035E-02	-4.0882E-03
S4	1.8655E+01	-8.0363E-02	-2.6662E-02	8.6724E-03	-1.3748E-03
						S8	3.8206E+01	3.5400E-01	1.1722E-01	-5.9910E-02	-1.0716E-03

TABLE 6

Fig. 13 shows an on-axis chromatic aberration curve of the vision system for example two, which represents the convergent focus deviation of light rays of different wavelengths after passing through the vision system. Fig. 14 shows an astigmatic curve of the visual system of example two, which represents meridional image surface curvature and sagittal image surface curvature. Fig. 15 shows distortion curves of the visual system of example two, which represent distortion magnitude values corresponding to different angles of view.

As can be seen from fig. 13 to 15, the visual system according to example two can achieve good imaging quality.

Example three

As shown in fig. 16 to 22, a visual system of example three of the present application is described. Fig. 16 shows a schematic optical path diagram of the visual system of example three, fig. 17 shows a schematic structural diagram of the visual system of example three in a first state, fig. 18 shows a schematic structural diagram of the visual system of example three in a second state, and fig. 19 shows a schematic structural diagram of the visual system of example three in a third state.

As shown in fig. 17 to 19, the visual system includes a lens barrel P0, and a first lens E1, a first spacer P1, a second lens E2, a second auxiliary spacer P2b, a second spacer P2, a reflective polarizing element RP, a quarter wave plate QWP, and a third lens E3, which are sequentially disposed in the lens barrel P0 from the first side to the second side.

In fig. 17 to 19, the first side surface and the second side surface of the first spacer P1 are respectively in contact with the second side surface S2 of the first lens and the first side surface S3 of the second lens, and the outer peripheral edge of the first spacer P1 is in contact with the inner wall surface portion of the lens barrel P0. The first side surface and the second side surface of the second auxiliary spacer P2b are respectively abutted against the second side surface S4 of the second lens and the first side surface portion of the second spacer P2, the second side surface of the second spacer P2 is abutted against the first side surface portion of the reflective polarizing element RP, and the outer peripheral edges of the second auxiliary spacer P2b and the second spacer P2 are respectively abutted against the inner wall surface portion of the lens barrel P0.

As shown in fig. 16, the light propagation path of the visual system is: the light emitted by the light emitting surface S9 of the light source is incident on the second side surface of the reflective polarizing element RP after passing through the third lens E3 and the quarter wave plate QWP, and is reflected for the first time, the light reflected for the first time is incident on the third lens E3 after passing through the quarter wave plate QWP, and is reflected for the second time on the partial reflecting layer of the second side surface of the third lens, and the light reflected for the second time is imaged at the stop position after passing through the first side surface S7 of the third lens, the quarter wave plate QWP, the reflective polarizing element RP, the second lens E2, and the first lens E1 in sequence.

In summary, the structural parameters of the visual system of example three in the first, second and third states 3-1, 3-2 and 3-3 are shown in reference to Table 7 in units of: mm.

Parameters/states	3-1	3-2	3-3
				d1s	45.80	45.43	44.86
d1m	45.80	45.43	44.86
				d2s	58.64	58.08	57.64
D2s	72.03	72.03	68.31
				D2bs	64.02	64.02	58.22
D2bm	64.98	67.05	62.55
				d0s	45.53	45.53	45.53
d0m	75.17	75.17	75.17
				D0m	78.57	78.57	80.53
EP01	5.66	5.28	4.98
				CP1	0.05	0.11	0.21
EP12	11.11	11.38	11.64
				CP2	0.05	0.11	0.05
CP2b	6.27	6.22	5.78
				L	31.80	31.79	31.80

TABLE 7

In example three, the first side S1 of the first lens is convex, and the second side S2 of the first lens is convex. The first side S3 of the second lens is concave, and the second side S4 of the second lens is convex. The first side S7 of the third lens is a plane, and the second side S8 of the third lens is a convex surface.

In example three, the effective focal length F of the visual system is 28.39mm, the effective focal length F1 of the first lens is 54.73mm, the effective focal length F2 of the second lens is-250.03 mm, the effective focal length F3 of the third lens is 39.24mm, half of the maximum field angle of the visual system semi-fov is 52.85 °, and the F-number Fno of the visual system is 5.68.

Table 8 shows a basic structural parameter table for the visual system of example three, where the radius of curvature, thickness, are each in millimeters mm. For ease of understanding, S5 may be represented as the first side of the reflective polarizer RP, S6 may be represented as the common plane of the reflective polarizer RP and the quarter wave plate QWP, and S7 may also be represented as the common plane of the quarter wave plate QWP and the first side of the third lens in table 8.

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TABLE 8

Table 9 shows polynomial coefficients that can be used for each aspherical surface in example three, where each aspherical surface profile can be defined by equation (1) given in example one above.

Face number	A3	A4	A5	A6	A7
						S1	2.1735E+01	1.9480E-01	-7.1621E-02	3.7287E-02	-1.8540E-03
S2	3.1440E+01	-2.5945E+00	9.9288E-02	8.0994E-01	2.4201E-01
						S3	2.9052E+01	1.4466E+00	3.3916E-01	9.2965E-02	1.7672E-01
S4	2.1868E+01	-2.1517E-01	-5.2688E-02	1.8815E-02	-3.9602E-03
						S8	3.8062E+01	3.9813E-01	2.7613E-01	-8.3063E-02	-6.3311E-03

TABLE 9

Fig. 20 shows an on-axis chromatic aberration curve for the vision system of example three, which represents the convergent focus deviation of light rays of different wavelengths through the vision system. Fig. 21 shows an astigmatic curve of the visual system of example three, which represents meridional image surface curvature and sagittal image surface curvature. Fig. 22 shows distortion curves of the visual system of example three, which represent distortion magnitude values corresponding to different angles of view.

As can be seen from fig. 20 to 22, the visual system of example three can achieve good imaging quality.

In summary, the above examples one to three satisfy the relationships shown in table 10, respectively.

Table 10

The application also provides an imaging device, wherein the electronic photosensitive element can be a photosensitive coupling element (CCD) or a complementary metal oxide semiconductor element (CMOS). The imaging device may be a stand alone imaging device such as a digital camera or an imaging module integrated on a mobile electronic device such as a cell phone. The imaging device is equipped with the above-described visual system.

It will be apparent that the embodiments described above are merely some, but not all, embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present application without making any inventive effort, shall fall within the scope of the present application.

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 exemplary embodiments according to 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.

It should be noted that the terms "first," "second," and the like in the description and the claims of the present application and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that embodiments of the application described herein may be implemented in sequences other than those illustrated or otherwise described herein.

The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A visual system is characterized by comprising a lens barrel, a first lens group, a first spacer, a second lens group, a second spacer and a third lens group which are sequentially arranged in the lens barrel from a first side to a second side, wherein the first lens group comprises a first lens, the second lens group comprises a second lens, the third lens group comprises a third lens, a first side surface of the third lens is a plane,

a portion of a first side or a second side of at least one of the first to third lenses has a reflective layer, the first and second sides of the first spacer are respectively abutted with the second side of the first lens group and the first side portion of the second lens group, the second spacer is abutted with the first side portion of the third lens group,

The gap distance ET23 between the maximum outer diameter D2s of the first side surface of the second spacer, the minimum inner diameter D2s of the first side surface of the second spacer, and the maximum effective diameter edge of the second side surface of the second lens and the maximum effective diameter edge of the first side surface of the third lens satisfies: 0.6< ((D2 s-D2 s)/2)/ET 23<1.3.

2. The visual system of claim 1, wherein the third lens group further comprises a reflective polarizing element and a quarter wave plate in contact with the third lens, the second side of the reflective polarizing element being in registry with the first side of the quarter wave plate.

3. The vision system of claim 2, wherein a center thickness CT3 of the third lens, a center thickness CTRP of the reflective polarizing element, a center thickness CTQWP of the quarter wave plate, an on-axis distance EP01 of the first side of the barrel to the first side of the first spacer, a center thickness CP1 of the first spacer, an on-axis distance EP12 of the second side of the first spacer to the first side of the second spacer, and a center thickness CP2 of the second spacer satisfy: 1< (CT3+CTRP+CTQWP)/(EP 01+CP1+EP 12+CP2) <1.7.

4. The vision system of claim 1, wherein a portion of the second side of the third lens is coated with the reflective layer.

5. The visual system of claim 1, wherein an on-axis distance TD between the first side of the barrel to the second side of the barrel, the first side of the first lens to the second side of the third lens, and an effective focal length f of the visual system satisfy: 2<L/TD+L/f <3.

6. The visual system of claim 1, wherein a radius of curvature R2 of the second side of the first lens, a radius of curvature R4 of the second side of the second lens, a minimum inner diameter d1s of the first side of the first spacer, and a minimum inner diameter d2s of the first side of the second spacer satisfy: -3< R2/d1s+R4/d2s < -1.

7. The visual system of claim 1, wherein a radius of curvature R2 of the second side of the first lens, a center thickness CT1 of the first lens, and an on-axis distance EP01 from the first side of the barrel to the first side of the first spacer satisfy: 7< (CT 1-R2)/EP 01<17.

8. The visual system of claim 1, wherein a radius of curvature R4 of the second side of the second lens, an on-axis distance EP12 of the second side of the first spacer to the first side of the second spacer, a center thickness CT2 of the second lens, and a refractive index N2 of the second lens satisfy: -10< r 4/(ep12+ct2) N2< -7.

9. The visual system according to any one of claims 1 to 8, wherein an effective focal length f of the visual system, a maximum length L of the first side of the barrel to the second side of the barrel, and half of a maximum field angle semi-fov of the visual system satisfy: 1.1< f tan (semi-fov)/L <1.5.

10. The visual system according to any one of claims 1 to 8, wherein a radius of curvature R6 of the second side of the third lens, an effective focal length f3 of the third lens, a maximum outer diameter D0m of the second side of the barrel, and a minimum inner diameter D0s of the first side of the barrel satisfy: -5< R6/f3-D0m/D0s < -4 >.