CN116300106A

CN116300106A - Optical system

Info

Publication number: CN116300106A
Application number: CN202310512281.8A
Authority: CN
Inventors: 赵世一; 冯梦怡; 游金兴; 张晓彬; 金银芳; 赵烈烽
Original assignee: Zhejiang Sunny Optics Co Ltd
Current assignee: Zhejiang Sunny Optics Co Ltd
Priority date: 2023-05-08
Filing date: 2023-05-08
Publication date: 2023-06-23

Abstract

An optical system includes a lens barrel, and a lens group, a reflection assembly, and a spacer group disposed in the lens barrel, the lens group including a first lens, a second lens, and a third lens sequentially arranged from a first side to a second side along an optical axis; the reflection assembly comprises a reflection type polarizing element, a quarter wave plate and a partial reflection layer; the spacer group includes a second spacer interposed between the second lens and the third lens and contacting a second side of the second lens; wherein, the curvature radius R4 of the second side surface of the second lens, the center thickness CT2 of the second lens on the optical axis, the outer diameter D2m of the second side surface of the second spacer, and the maximum thickness CP2 of the second spacer satisfy: 0.5< |R4×CT2|/(D2 m×CP2) <60.0.

Description

Optical system

Technical Field

The present application relates to the field of optical devices, and in particular to a three-piece optical system.

Background

With the concept of "meta-universe" being proposed, the manner of entertainment for users is increasingly abundant, and devices such as Virtual Reality (VR)/augmented Reality (Augmented Reality, AR) technology of human-computer interaction are increasingly favored by users. The optical systems used by VR/AR devices are typically aspheric or fresnel lenses, and these optical systems have a long body length, which can cause the center of gravity of the user to move forward when in use, severely affecting the user's experience.

In order to reduce the body length of the optical system, the optical system is configured as a two-piece type foldback system, which can compress the body length by folding the optical path and compress the body length to half that of a conventional optical system. When the two-piece foldback system is used, the gravity center of a user can be moved backwards, so that the experience of the user is enhanced. However, the external field imaging picture of the two-piece foldback system is blurred, and the imaging quality is poor.

Disclosure of Invention

The present application provides an optical system that at least solves or partially solves at least one problem, or other problems, present in the prior art.

An aspect of the present application provides an optical system including a lens barrel, and a lens group, a reflection assembly, and a spacer group disposed in the lens barrel, the lens group including a first lens, a second lens, and a third lens sequentially arranged from a first side to a second side along an optical axis; the reflection assembly comprises a reflection type polarizing element, a quarter wave plate and a partial reflection layer; the spacer group includes a second spacer interposed between the second lens and the third lens and contacting a second side of the second lens; wherein, the curvature radius R4 of the second side surface of the second lens, the center thickness CT2 of the second lens on the optical axis, the outer diameter D2m of the second side surface of the second spacer, and the maximum thickness CP2 of the second spacer satisfy: 0.5< |R4×CT2|/(D2 m×CP2) <60.0.

According to an exemplary embodiment of the present application, the reflective polarizing element is disposed between the first side and the second lens.

According to an exemplary embodiment of the present application, the partially reflective layer is arranged between the second lens and the third lens or between the third lens and the second side.

According to an exemplary embodiment of the present application, the first side of the first lens is configured as one of convex, concave or planar at the paraxial, and the second side of the first lens is configured as convex or planar at the paraxial.

According to one exemplary embodiment of the present application, the effective focal length f1 of the first lens and the total effective focal length f of the optical system satisfy: 4.0< f1/f <30.0, the effective focal length f2 of the second lens and the total effective focal length f of the optical system satisfy: -57.0< f2/f <14.0, the effective focal length f3 of the third lens and the total effective focal length f of the optical system satisfying: 6.0< f3/f <29.0.

According to an exemplary embodiment of the present application, the total effective focal length f of the optical system, half of the maximum field angle Semi-FOV of the optical system, the inner diameter d0s of the first side end face of the lens barrel, and the inner diameter d0m of the second side end face of the lens barrel satisfy: 0.2< TAN (Semi-FOV) × (d 0m-d0 s)/f <1.0.

According to an exemplary embodiment of the present application, the spacer group further includes a first spacer interposed between the first lens and the second lens and in contact with the second side of the first lens, and the effective focal length f1 of the first lens, the outer diameter D1s of the first side of the first spacer, and the outer diameter D1m of the second side of the first spacer satisfy: 0.5< f 1/(d1s+d1m) <4.5.

According to an exemplary embodiment of the present application, the spacer group further comprises a first spacer interposed between the first lens and the second lens and in contact with the second side of the first lens, wherein the total effective focal length f of the optical system, the inner diameter d1s of the first side of the first spacer and the inner diameter d1m of the second side of the first spacer satisfy: 5.0< (d1s+d1m)/f <7.0.

According to one exemplary embodiment of the present application, the spacer group further includes a first spacer interposed between the first lens and the second lens and in contact with the second side surface of the first lens, wherein a first side end surface of the lens barrel and the first spacer are spaced apart from each other along the optical axis by EP01, a maximum thickness of the first spacer CP1, a center thickness of the first lens CT1 on the optical axis, an air spacing of the first lens and the second lens T12 on the optical axis, and a center thickness of the reflective polarizing element d on the optical axis _RP The method meets the following conditions: 0.5<(EP01+CP1)/(CT1+T12+d _RP )<2.0。

According to an exemplary embodiment of the present application, the spacer group further comprises a first spacer interposed between the first lens and the second lens and in contact with the second side of the first lens, wherein an effective focal length f1 of the first lens, an effective focal length f2 of the second lens, an outer diameter D1m of the second side of the first spacer and an outer diameter D2s of the first side of the second spacer satisfy: 3.0< |f1+f2|/(d1m+d2s) <10.0.

According to an exemplary embodiment of the present application, the radius of curvature R3 of the first side of the second lens, the air space T12 of the first lens and the second lens on the optical axis, the inner diameter d2s of the first side of the second spacer, and the maximum thickness CP2 of the second spacer satisfy: 0< |R3×T12|/(d2s×CP2) <32.0.

According to an exemplary embodiment of the present application, the spacer group further includes a first spacer interposed between the first lens and the second lens and in contact with the second side of the first lens, wherein an effective focal length f2 of the second lens, an air interval T23 of the second lens and the third lens on the optical axis, an on-axis distance SAG22 from an intersection point of an interval EP12 of the first spacer and the second spacer along the optical axis with the second side of the second lens and the optical axis to an effective half-caliber vertex of the second side of the second lens satisfies: 2.0< |f2×t23|/|ep12×sag22| <67.0.

According to an exemplary embodiment of the present application, the spacer group further includes a lens disposed between the first lens and the second lensA first spacer in contact with the second side of the first lens, wherein an effective focal length f3 of the third lens, a center thickness CT3 of the third lens on the optical axis, and a center thickness d of the quarter-wave plate on the optical axis _QWP The interval EP12 of the first and second spacers along the optical axis and the maximum thickness CP2 of the second spacer satisfy: 10.0<f3/(d _QWP +CT3+CP2+EP12)<80.0。

According to an exemplary embodiment of the present application, the radius of curvature R5 of the first side surface of the third lens, the radius of curvature R6 of the second side surface of the third lens, the outer diameter D0s of the first side end surface of the lens barrel, and the outer diameter D0m of the second side end surface of the lens barrel satisfy: -2.5< (r5+r6)/(d0s+d0m) < -1.0.

The optical system provided by the application is configured into the three-piece type foldback system, through controlling the mutual relation among the curvature radius of the second side surface of the second lens, the center thickness of the second lens on the optical axis, the outer diameter of the second side surface of the second spacer and the maximum thickness of the second spacer, the incident light with poor edge quality of the second side surface of the second lens and the useless light generated by the reflection of the third lens can be effectively reduced, the uniformity of the light in the distribution of the projection surface of the first side is increased, and meanwhile, the field curvature of the optical system can be restrained within a reasonable range, so that the optical system obtains more light entering quantity, the imaging picture of the external view field of the optical system is ensured to be clear, the imaging quality of the optical system is improved, in addition, the appearance of the second spacer can be controlled, and the processability of the second spacer is improved.

Drawings

Other features, objects and advantages of the present application will become more apparent upon reading of the detailed description of non-limiting embodiments, made with reference to the following drawings, in which:

FIG. 1 shows a parametric schematic of an optical system according to the present application;

FIG. 2 shows a schematic structural view of an optical system according to the present application;

fig. 3 shows a schematic optical path diagram of an optical system according to a first embodiment of the present application;

fig. 4 shows a schematic structural view of an optical system of example 1 according to a first embodiment of the present application;

fig. 5 shows a schematic structural view of an optical system according to example 2 of the first embodiment of the present application;

fig. 6A to 6C show an on-axis chromatic aberration curve, an astigmatic curve, and a distortion curve, respectively, of the optical system according to the first embodiment of the present application;

fig. 7 shows a schematic view of an optical path of an optical system according to a second embodiment of the present application;

fig. 8 shows a schematic structural view of an optical system of example 1 according to a second embodiment of the present application;

fig. 9 shows a schematic structural view of an optical system according to example 2 of the second embodiment of the present application;

fig. 10A to 10C show an on-axis chromatic aberration curve, an astigmatic curve, and a distortion curve, respectively, of the optical system according to the second embodiment of the present application;

Fig. 11 shows a schematic optical path diagram of an optical system according to a third embodiment of the present application;

fig. 12 is a schematic diagram showing the structure of an optical system of example 1 according to a third embodiment of the present application;

fig. 13 shows a schematic structural view of an optical system according to example 2 of the third embodiment of the present application;

fig. 14A to 14C show an on-axis chromatic aberration curve, an astigmatic curve, and a distortion curve, respectively, of an optical system according to a third embodiment of the present application;

fig. 15 shows a schematic optical path diagram of an optical system according to a fourth embodiment of the present application;

fig. 16 is a schematic diagram showing the structure of an optical system of example 1 according to a fourth embodiment of the present application;

fig. 17 shows a schematic structural view of an optical system according to example 2 of the fourth embodiment of the present application; and

fig. 18A to 18C show an on-axis chromatic aberration curve, an astigmatism curve, and a distortion curve of the optical system according to the fourth embodiment of the present application, respectively.

Detailed Description

For a better understanding of the present application, various aspects of the present application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed description are merely illustrative of exemplary embodiments of the application and are not intended to limit the scope of the application in any way. Like reference numerals refer to like elements throughout the specification.

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 closest to the first side (e.g., the receiving portion side) is referred to as the first side of the lens, and the surface of each lens closest to the second side (e.g., the transmitting portion side) is referred to as the second side of the lens.

It will be further understood that the terms "comprises," "comprising," "includes," "including," "having," "containing," and/or "including," when used in this specification, specify the presence of stated features, elements, and/or components, but do not preclude the presence or addition of one or more other features, elements, components, and/or groups thereof. Furthermore, when describing embodiments of the present application, use of "may" means "one or more embodiments of the present application. Also, the term "exemplary" is intended to refer to an example or illustration.

Unless otherwise defined, all terms (including 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. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

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.

The features, principles, and other aspects of the present application are described in detail below.

As shown in fig. 3 to 5, 7 to 9, 11 to 13, and 15 to 17, an optical system according to an exemplary embodiment of the present application may include a lens barrel and a lens group disposed within the lens barrel, and the lens group may include a first lens, a second lens, and a third lens sequentially arranged from a first side to a second side along an optical axis. In the first lens to the third lens, an air space may be provided between any adjacent two lenses.

In an exemplary embodiment, the optical system may further include a reflection assembly disposed within the lens barrel, and the reflection assembly may include a reflective polarizing element, a quarter-wave plate, and a partially reflective layer, wherein the partially reflective layer has a semi-transmissive and semi-reflective effect on light. The reflective element has a reflective effect on the light entering the optical system, which does not mean that every element in the reflective element has a reflective effect on the light.

In an exemplary embodiment, the first side may be, for example, a receiving portion side, and the second side may be, for example, a transmitting portion side. Accordingly, the first side of each element (first lens, second lens, third lens, reflective polarizing element, quarter wave plate, and partially reflective layer) may be referred to as a near-receiving portion side, and the second side may be referred to as a near-transmitting portion side. The receiving part may be, for example, a human eye and the transmitting part may be, for example, a display screen.

In an exemplary embodiment, the reflective polarizing element may be disposed between the first side and the second lens. As an example, the reflective polarizing element may be disposed between the first side and the first lens or between the first lens and the second lens. As an example, the reflective polarizing element may be attached to the first side or the second side of the first lens. Through setting up reflective polarizing element in above-mentioned position, can guarantee that light just can turn back through reflective polarizing element after having passed through second lens, third lens to effectively prolong the optical path to folding light path, guaranteeing that optical system has under the condition of the same imaging magnification, effectively reducing optical system's body length, promote user's experience and feel.

In an exemplary embodiment, the partially reflective layer may be disposed between the second lens and the third lens or between the third lens and the second side. As an example, the partially reflective layer may be attached to the first side or the second side of the third lens. Through setting up partial reflection stratum in above-mentioned position, can guarantee that the light that turns back through reflective polarizing element must pass through the second lens, or just can turn back once more after second lens and the third lens to effectively prolong the optical path, and folding light path, under the circumstances that guarantee that optical system has the same imaging magnification, effectively reduce optical system's body length, promote user's experience and feel.

In an exemplary embodiment, a quarter wave plate may be disposed between the second lens and the third lens. As an example, a quarter wave plate may be attached to the first side of the third lens.

In an exemplary embodiment, the optical system may further include a spacer group disposed within the lens barrel, and the spacer group may include a first spacer, wherein the first spacer is disposed between the first lens and the second lens and is at least partially in contact with the second side of the first lens. The spacer is reasonably used, so that the stray light risk can be effectively avoided, the interference on the image quality is reduced, and the imaging quality of the optical system is further improved.

In other examples, the spacer group may further include a second spacer, wherein the second spacer may be disposed between the second lens and the third lens and at least partially in contact with the second side of the second lens. The first spacer and the second spacer may be two separate spacers. Alternatively, the first and second spacers may be step-over spacers, i.e., the sides of the first and second spacers that are close to the lens barrel may be connected together.

In other examples, a first auxiliary spacer may be included between the first spacer and the second lens that is at least partially in contact with the second side of the first spacer. The second spacer and the third lens may further include a second auxiliary spacer therebetween that is at least partially in contact with the second side of the second spacer.

In an exemplary embodiment, the optical system may further include a diaphragm, which may be disposed between the first side and the first lens. The receiving part on the first side can view the image projected by the emitting part on the second side at the position of the diaphragm, namely, the image light on the emitting part is finally projected to the receiving part after being refracted and reflected for many times by the third lens, the quarter wave plate, the second lens, the reflective polarizing element, the first lens and the like.

In an exemplary embodiment, a light source may be provided on the emitting part. The image light of the light source can be emitted from the emitting part, sequentially passes through the third lens, the quarter wave plate and the second lens, reaches the reflective polarizing element, and is reflected at the reflective polarizing element to form first reflected image light. The first reflected image light passes through the second lens, the quarter wave plate, and reaches the partially reflective layer on the second side of the third lens, and then is reflected at the partially reflective layer to form second reflected image light. The second reflected image light sequentially passes through the third lens, the quarter wave plate, the second lens, the reflective polarizing element and the first lens to the diaphragm (namely, the position where the receiving part views the image). In other examples, the first reflected image light may also pass through the second lens and reach the partially reflective layer on the near-transmitting portion side of the quarter-wave plate, and then be reflected at the partially reflective layer to form the second reflected image light, and the second reflected image light need not pass through the third lens. In other examples, the image light of the light source may pass through the first lens and be reflected by the reflective polarizing element on the first side of the first lens to form the first reflected image light, and the first reflected image light may pass through the first lens to be reflected by the partially reflective layer to form the second reflected image light. The optical system provided by the application folds the required optical path on the premise of not influencing the projection quality in a light reflection and refraction combined mode, and the length of the body of the optical system is effectively shortened.

In an exemplary embodiment, the first side of the first lens is configured as one of convex, concave, or planar at the paraxial, and the second side of the first lens is configured as convex or planar at the paraxial. By arranging the first side surface and the second side surface of the first lens in the form, the trend of light rays can be effectively controlled, light rays are more beneficial to converging, and when the first side surface or the second side surface of the first lens is arranged to be a plane, the attachment of the reflective polarizing element is beneficial.

In an exemplary embodiment, the radius of curvature R4 of the second side of the second lens, the center thickness CT2 of the second lens on the optical axis, the outer diameter D2m of the second side of the second spacer, and the maximum thickness CP2 of the second spacer may satisfy: 0.5< |R4×CT2|/(D2 m×CP2) <60.0. By controlling the conditional expression, the incident light rays with poor quality on the edge of the second side surface of the second lens and useless light rays generated by reflection of the third lens can be effectively reduced, the uniformity of the light rays in all directions on the projection surface of the first side is improved, the field curvature of the optical system can be restrained in a reasonable range, the optical system can obtain more light entering quantity, the imaging picture of the external vision field of the optical system is ensured to be clear, the imaging quality of the optical system is improved, in addition, the appearance of the second spacer can be controlled, and the processability of the second spacer is improved.

In an exemplary embodiment, the effective focal length f1 of the first lens and the total effective focal length f of the optical system may satisfy: 4.0< f1/f <30.0, the effective focal length f2 of the second lens and the total effective focal length f of the optical system can satisfy: -57.0< f2/f <14.0, and the effective focal length f3 of the third lens and the total effective focal length f of the optical system may satisfy: 6.0< f3/f <29.0. The effective focal length of the first lens, the effective focal length of the second lens and the ratio of the effective focal length of the third lens to the total effective focal length of the optical system are respectively constrained in a reasonable range, so that the focal power of each lens can be reasonably distributed while the optical system meets the characteristic of a large visual field, the aberration of the optical system can be effectively corrected on the premise of meeting the total effective focal length of the optical system, and the imaging quality of the optical system is improved.

In an exemplary embodiment, the total effective focal length f of the optical system, half of the maximum field angle Semi-FOV of the optical system, the inner diameter d0s of the first side end surface of the lens barrel, and the inner diameter d0m of the second side end surface of the lens barrel may satisfy: 0.2< TAN (Semi-FOV) × (d 0m-d0 s)/f <1.0. Through controlling the above conditional expression, the angle of view of the optical system can be effectively restrained for the optical system satisfies the characteristics of large visual field, and simultaneously the inner diameter of the second side end face of the lens barrel can be limited in a reasonable range, so that the lens barrel can shield redundant light from entering the lens barrel, and stray light is effectively avoided.

In an exemplary embodiment, the effective focal length f1 of the first lens, the outer diameter D1s of the first side surface of the first spacer, and the outer diameter D1m of the second side surface of the first spacer may satisfy: 0.5< f 1/(d1s+d1m) <4.5. Through controlling the conditional expression, the first lens can be made to be a positive lens, light convergence is facilitated, the outer diameters of the first side face and the second side face of the first spacer can be restrained within a reasonable range, the first spacer is ensured to be respectively and stably supported by the first lens and the second lens, and the assembly stability of the optical system is improved.

In an exemplary embodiment, the total effective focal length f of the optical system, the inner diameter d1s of the first side surface of the first spacer, and the inner diameter d1m of the second side surface of the first spacer may satisfy: 5.0< (d1s+d1m)/f <7.0. Through controlling the above conditional expression, the total effective focal length of the optical system can be limited in a reasonable range, the length of the optical system body is limited, the experience of a user is improved, meanwhile, the inner diameters of the first side face and the second side face of the first spacer can be limited in a reasonable range, stray light of the optical system is effectively improved, the first spacer is ensured to be respectively and stably supported by the first lens and the second lens, and the assembly stability of the optical system is improved.

In the exemplary embodiment, the interval EP01 between the first side end surface of the lens barrel and the first spacer along the optical axis, the maximum thickness CP1 of the first spacer, the center thickness CT1 of the first lens on the optical axis, the air interval T12 of the first lens and the second lens on the optical axis, and the center thickness d of the reflective polarizing element on the optical axis _RP Can satisfy the following conditions: 0.5<(EP01+CP1)/(CT1+T12+d _RP )<2.0. Through controlling the conditional expression, the central thickness of the first lens on the optical axis and the air intervals of the first lens and the second lens on the optical axis can be reasonably distributed, so that the field curvature of the optical system is restrained within a reasonable range, the optical system is ensured to have good imaging effect, the central thickness of the reflective polarizing element on the optical axis can be limited within a reasonable range, the haze of the reflective polarizing element is reduced, the transmissivity and the processability of the reflective polarizing element are improved, and the optical system is ensured to have good imaging effect.

In an exemplary embodiment, the effective focal length f1 of the first lens, the effective focal length f2 of the second lens, the outer diameter D1m of the second side surface of the first spacer, and the outer diameter D2s of the first side surface of the second spacer may satisfy: 3.0< |f1+f2|/(d1m+d2s) <10.0. Through controlling the above conditional expression, the focal power of the optical system can be limited, so that the adjustment of the focusing position of the light beam is facilitated, the length of the body of the optical system is shortened, the outer diameter of the second lens and the inner diameter of the corresponding part of the lens barrel can be restrained within a reasonable range, and the processability of the second lens and the lens barrel is improved.

In an exemplary embodiment, the radius of curvature R3 of the first side of the second lens, the air space T12 of the first lens and the second lens on the optical axis, the inner diameter d2s of the first side of the second spacer, and the maximum thickness CP2 of the second spacer may satisfy: 0< |R3×T12|/(d2s×CP2) <32.0. Through controlling the conditional expression, the inner diameter of the first side surface of the second spacer and the maximum thickness of the second spacer can be limited in a reasonable range, so that the structural appearance of the second spacer is restrained, the machinability of the second spacer is improved under the condition that the assembly requirement of an optical system is met, meanwhile, the curvature radius of the first side surface of the second lens and the air interval between the first lens and the second lens on the optical axis can be limited in a reasonable range, the structural compactness of the optical system is ensured, the off-axis aberration of the optical system is corrected, and the integral image quality of the optical system is improved.

In an exemplary embodiment, the effective focal length f2 of the second lens, the air interval T23 of the second lens and the third lens on the optical axis, the on-axis distance SAG22 from the intersection of the interval EP12 of the first spacer and the second spacer along the optical axis with the second side of the second lens and the optical axis to the effective half-caliber vertex of the second side of the second lens may satisfy: 2.0< |f2×t23|/|ep12×sag22| <67.0. Through controlling the conditional expression, the effective focal length, the edge thickness and the sagittal height of the second side face of the second lens can be limited, the shape of the second lens is effectively restrained, the processing difficulty of the second lens is reduced, the light ray trend is controlled, the ghost image generated by the second lens is optimized, the imaging quality of an optical system is improved, the air interval between the second lens and the third lens on the optical axis can be limited in a reasonable range, the off-axis aberration of the optical system is corrected, and the optical system is ensured to have a good imaging effect.

In an exemplary embodiment, the effective focal length f3 of the third lens, the center thickness CT3 of the third lens on the optical axis, and the center thickness d of the quarter wave plate on the optical axis _QWP The interval EP12 of the first and second spacers along the optical axis and the maximum thickness CP2 of the second spacer may satisfy: 10.0<f3/(d _QWP +CT3+CP2+EP12)<80.0. By controlling the conditional expression, the central thickness of the quarter wave plate on the optical axis can be limited within a reasonable range, the haze of the quarter wave plate is reduced, the transmissivity and the processability of the quarter wave plate are improved, the optical system is further ensured to have good imaging effect, and the central thickness of the third lens on the optical axis, the first spacer and the second spacer can be reasonably distributedThe distance between the two spacers along the optical axis and the maximum thickness of the second spacer ensure the machinability of the third lens, the first spacer and the second spacer on the premise that the length of the body of the optical system meets the requirement of miniaturized equipment.

In an exemplary embodiment, the radius of curvature R5 of the first side surface of the third lens, the radius of curvature R6 of the second side surface of the third lens, the outer diameter D0s of the first side end surface of the lens barrel, and the outer diameter D0m of the second side end surface of the lens barrel may satisfy: -2.5< (r5+r6)/(d0s+d0m) < -1.0. Through controlling the above conditional expression, the focal power of the third lens can be limited, the deflection angle of the marginal rays of the optical system is reasonably restrained, the sensitivity of the optical system is effectively reduced, the image quality and the relative illuminance of the optical system are improved, the outer diameters of the first side end face and the second side end face of the lens barrel can be limited in a reasonable range, the trend of the appearance opening angle of the lens barrel is smoother, and the processing difficulty of the lens barrel is reduced.

An optical system according to the above-described embodiments of the present application may employ multiple lenses, a reflective assembly, and at least one spacer, such as the three lenses, the reflective assembly, and the two spacers described above. By reasonably distributing parameters of each lens, each reflecting component and each spacer, the length of the body of the optical system can be reduced, the stray light phenomenon of the optical system can be improved, and the processability, the assembly stability and the imaging quality of the optical system can be improved. The optical system with the configuration has the characteristics of miniaturization, good assembly stability, less parasitic light, compact structure, good imaging quality and the like, and can well meet the use requirements of various portable electronic products in projection scenes.

In an embodiment of the present application, at least one of the mirrors of each of the first to third lenses is an aspherical mirror. 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 during 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 and spacers making up the optical system can be varied to achieve the various results and advantages described in the specification without departing from the technical solutions claimed herein.

Specific examples of the optical system applicable to the above-described embodiments are further described below with reference to the drawings.

First embodiment

An optical system according to a first embodiment of the present application is described below with reference to fig. 3 to 6C. Fig. 3 shows a schematic optical path diagram of an optical system according to a first embodiment of the present application; fig. 4 shows a schematic structural view of an optical system 110 according to example 1 of the first embodiment of the present application; fig. 5 shows a schematic structural diagram of an optical system 120 according to example 2 of the first embodiment of the present application.

As shown in fig. 3 to 5, each of the

optical systems

110, 120 includes a lens barrel P0, and a lens group, a reflection assembly, and a spacer group disposed within the lens barrel P0. The lens group sequentially comprises from a first side to a second side: a first lens E1, a second lens E2, and a third lens E3. In the present embodiment, the first side refers to the receiving portion side, and the second side refers to the transmitting portion side. The stop STO may be disposed between the receiving portion and the first lens E1. The reflection assembly includes: the reflective polarizing element RP, the quarter-wave plate QWP and the partial reflecting layer BS, wherein the reflective polarizing element RP is arranged between the first lens E1 and the second lens E2, and the quarter-wave plate QWP is arranged between the second lens E2 and the third lens E3. The spacer group includes: a first spacer P1 and a second spacer P2. In the present embodiment, the first side surfaces of the respective elements (the first lens E1, the second lens E2, the third lens E3, the reflective polarizing element RP, the quarter-wave plate QWP, and the partially reflective layer BS) are each referred to as a near-receiving portion side surface, and the second side surfaces are each referred to as a near-emitting portion side surface.

The first lens E1 has positive power, and its near-receiving portion side surface S1 is convex and its near-emitting portion side surface S2 is planar. The second lens E2 has positive power, and its near-receiving portion side surface S3 is convex, and its near-emitting portion side surface S4 is convex. The third lens E3 has positive power, and its near-receiving portion side surface S5 is concave and near-emitting portion side surface S6 is convex. The reflective polarizing element RP may be attached to the near-emission portion side surface S2 of the first lens E1. A quarter wave plate QWP may be attached to the near-receiving portion side S5 of the third lens E3. The partially reflective layer BS may be attached to the near-emission portion side S6 of the third lens E3.

In this example, the emitting portion may be provided with a light source. After the image light from the emission portion passes through the third lens E3, the quarter-wave plate QWP, the second lens E2 in order and reaches the reflective polarizing element RP, the first reflection occurs at the reflective polarizing element RP. After the light reflected once passes through the second lens E2, the quarter wave plate QWP, and reaches the partially reflective layer BS on the near-emission portion side of the third lens E3, a second reflection occurs at the partially reflective layer BS. The light reflected for the second time passes through the third lens E3, the quarter wave plate QWP, the second lens E2, the reflective polarizing element RP, the first lens E1, and finally, the receiving part in the projection space in this order. For example, the light reflected by the optical system twice is finally projected into eyes of a user.

Table 1 shows a basic parameter table of the optical system of the first embodiment, in which the unit of curvature radius, thickness/distance is millimeter (mm). The image light from the emitting portion passes through the elements in the order of number 19 to number 1 and is finally projected into a receiving portion such as human eyes in the space.

TABLE 1

In this embodiment, the total effective focal length f of the optical system is 15.94mm, the effective focal length f1 of the first lens is 473mm, the effective focal length f2 of the second lens is 84.33mm, the effective focal length f3 of the third lens is 325.02mm, the value of half of the maximum field angle Semi-FOV of the optical system is 45.0 °, and the value of the on-axis distance SAG22 from the intersection of the second side surface of the second lens and the optical axis to the effective half-caliber vertex of the second side surface of the second lens is-2.87 mm.

In the first embodiment, the near-receiving side surface S1 of the first lens E1, the near-receiving side surface S3 and the near-emitting side surface S4 of the second lens E2, and the near-receiving side surface S5 and the near-emitting side surface S6 of the third lens E3 are all aspherical surfaces, and the surface shape z of each aspherical lens can be defined by, but not limited to, the following aspherical formula:

wherein z is the depth of the aspheric surface (the point on the aspheric surface at a distance y from the optical axis, and the tangential plane tangential to the vertex on the optical axis of the aspheric surface, the perpendicular distance between the two); c is the curvature of the apex of the aspheric surface; 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) _m ^con Is the mth order Q ^con A polynomial. Table 2 shows the cone coefficients K and the polynomial coefficients a of the respective aspherical mirror surfaces S1, S3-S6 which can be used in the first embodiment ₀ 、a ₁ 、a ₂ And a ₃ 。

Face number	K	a0	a1	a2	a3
						S1	0.0000	1.10E+00	-8.97E-01	2.06E-01	0.00E+00
S3	0.0000	-7.46E+00	1.21E+00	-1.37E-01	-6.09E-02
						S4	0.0000	-2.34E+00	1.17E+00	-1.66E-01	0.00E+00
S5	0.0000	1.65E+00	4.67E-01	-6.10E-02	0.00E+00
						S6	0.0000	4.85E-01	1.11E-01	1.00E-01	0.00E+00

TABLE 2

Fig. 6A shows on-axis chromatic aberration curves of the

optical systems

110 and 120 of the first embodiment, which represent the convergent focus deviation of light rays of different wavelengths after passing through the

optical systems

110 and 120. Fig. 6B shows astigmatism curves of the

optical systems

110 and 120 of the first embodiment, which represent meridional image surface curvature and sagittal image surface curvature corresponding to different half angles of view. Fig. 6C shows distortion curves of the

optical systems

110 and 120 of the first embodiment, which represent distortion magnitude values corresponding to different half angles of view. As can be seen from fig. 6A to 6C, the

optical systems

110 and 120 according to the first embodiment can achieve good imaging quality.

Second embodiment

An optical system according to a second embodiment of the present application is described below with reference to fig. 7 to 10C. Fig. 7 shows a schematic view of an optical path of an optical system according to a second embodiment of the present application; fig. 8 shows a schematic structural view of an optical system 210 of example 1 according to a second embodiment of the present application; fig. 9 shows a schematic structural diagram of an optical system 220 according to example 2 of the second embodiment of the present application.

As shown in fig. 7 to 9, each of the

optical systems

210, 220 includes a lens barrel P0, and a lens group, a reflection assembly, and a spacer group disposed within the lens barrel P0. The lens group sequentially comprises from a first side to a second side: a first lens E1, a second lens E2, and a third lens E3. In the present embodiment, the first side refers to the receiving portion side, and the second side refers to the transmitting portion side. The stop STO may be disposed between the receiving portion and the first lens E1. The reflection assembly includes: the reflective polarizing element RP, the quarter-wave plate QWP and the partial reflecting layer BS, wherein the reflective polarizing element RP is arranged between the first lens E1 and the second lens E2, and the quarter-wave plate QWP is arranged between the second lens E2 and the third lens E3. The spacer group includes: a first spacer P1 and a second spacer P2. In the present embodiment, the first side surfaces of the respective elements (the first lens E1, the second lens E2, the third lens E3, the reflective polarizing element RP, the quarter-wave plate QWP, and the partially reflective layer BS) are each referred to as a near-receiving portion side surface, and the second side surfaces are each referred to as a near-emitting portion side surface.

The first lens E1 has positive power, and its near-receiving portion side surface S1 is convex and its near-emitting portion side surface S2 is planar. The second lens E2 has positive power, and its near-receiving portion side surface S3 is convex, and its near-emitting portion side surface S4 is convex. The third lens E3 has positive power, and its near-receiving portion side surface S5 is concave and near-emitting portion side surface S6 is convex. The reflective polarizing element RP may be attached to the near-emission portion side surface S2 of the first lens E1. Both the quarter wave plate QWP and the partially reflective layer BS may be attached to the near-receiving portion side surface S5 of the third lens E3, and the partially reflective layer BS is closer to the third lens E3 than the quarter wave plate QWP.

In this example, the emitting portion may be provided with a light source. After the image light from the emission portion passes through the third lens E3, the quarter-wave plate QWP, the second lens E2 in order and reaches the reflective polarizing element RP, the first reflection occurs at the reflective polarizing element RP. After the light reflected once passes through the second lens E2 and reaches the partially reflective layer BS on the near-emission portion side of the quarter-wave plate QWP, a second reflection occurs at the partially reflective layer BS. The light reflected for the second time passes through the quarter wave plate QWP, the second lens E2, the reflective polarizing element RP, the first lens E1, and finally, the receiving part in the projection space in this order. For example, the light reflected by the optical system twice is finally projected into eyes of a user.

Table 3 shows a basic parameter table of the optical system of the second embodiment, in which the unit of curvature radius, thickness/distance is millimeter (mm). The image light from the emitting portion passes through the elements in the order of number 17 to number 1 and is finally projected into a receiving portion such as human eyes in the space.

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TABLE 3 Table 3

In this embodiment, the total effective focal length f of the optical system is 15.63mm, the effective focal length f1 of the first lens is 370.34mm, the effective focal length f2 of the second lens is 62.19mm, the effective focal length f3 of the third lens is 448.13mm, the half of the maximum field angle Semi-FOV of the optical system is 50.0 °, and the on-axis distance SAG22 from the intersection point of the second side surface of the second lens and the optical axis to the effective half-caliber vertex of the second side surface of the second lens is-4.87 mm.

In the second embodiment, the near-receiving side surface S1 of the first lens E1, the near-receiving side surface S3 and the near-emitting side surface S4 of the second lens E2, and the near-receiving side surface S5 and the near-emitting side surface S6 of the third lens E3 are aspherical surfaces. Table 4 shows the cone coefficients K and the polynomial coefficients a of the respective aspherical mirror surfaces S1, S3-S6 which can be used in the second embodiment ₀ 、a ₁ 、a ₂ And a ₃ 。

Face number	K	a0	a1	a2	a3
						S1	0.0000	4.66E-01	-5.59E-02	-1.42E-03	0.00E+00
S3	0.0000	-3.96E-01	-7.15E-02	1.20E-02	0.00E+00
						S4	0.0000	2.28E+00	-3.62E-01	8.30E-02	-4.95E-03
S5	0.0000	-3.91E-01	7.29E-02	-8.55E-03	5.69E-04
						S6	0.0000	6.93E-01	-2.08E-01	3.15E-02	-1.34E-03

TABLE 4 Table 4

Fig. 10A shows on-axis chromatic aberration curves of the

optical systems

210 and 220 of the second embodiment, which represent the convergent focus deviation of light rays of different wavelengths after passing through the

optical systems

210 and 220. Fig. 10B shows astigmatism curves of the

optical systems

210 and 220 of the second embodiment, which represent meridional image surface curvature and sagittal image surface curvature corresponding to different half angles of view. Fig. 10C shows distortion curves of the

optical systems

210 and 220 of the second embodiment, which represent distortion magnitude values corresponding to different half angles of view. As can be seen from fig. 10A to 10C, the

optical systems

210 and 220 according to the second embodiment can achieve good imaging quality.

Third embodiment

An optical system according to a third embodiment of the present application is described below with reference to fig. 11 to 14C. Fig. 11 shows a schematic optical path diagram of an optical system according to a third embodiment of the present application; fig. 12 shows a schematic structural diagram of an optical system 310 according to example 1 of the third embodiment of the present application; fig. 13 shows a schematic structural diagram of an optical system 320 according to example 2 of the third embodiment of the present application.

As shown in fig. 11 to 13, each of the

optical systems

310, 320 includes a lens barrel P0, and a lens group, a reflection assembly, and a spacer group disposed within the lens barrel P0. The lens group sequentially comprises from a first side to a second side: a first lens E1, a second lens E2, and a third lens E3. In the present embodiment, the first side refers to the receiving portion side, and the second side refers to the transmitting portion side. The stop STO may be disposed between the receiving portion and the first lens E1. The reflection assembly includes: a reflective polarizing element RP, a quarter wave plate QWP and a partially reflective layer BS, wherein the reflective polarizing element RP is disposed between the receiving portion and the first lens E1, and the quarter wave plate QWP is disposed between the second lens E2 and the third lens E3. The spacer group includes: a first spacer P1 and a second spacer P2. In the present embodiment, the first side surfaces of the respective elements (the first lens E1, the second lens E2, the third lens E3, the reflective polarizing element RP, the quarter-wave plate QWP, and the partially reflective layer BS) are each referred to as a near-receiving portion side surface, and the second side surfaces are each referred to as a near-emitting portion side surface.

The first lens E1 has positive power, and its near-receiving portion side surface S1 is concave and near-emitting portion side surface S2 is convex. The second lens E2 has negative power, and its near-receiving portion side S3 is concave and near-emitting portion side S4 is convex. The third lens E3 has positive power, and its near-receiving portion side surface S5 is concave and near-emitting portion side surface S6 is convex. The reflective polarizer RP may be attached to the near-receiving portion side surface S1 of the first lens E1. A quarter wave plate QWP may be attached to the near-receiving portion side S5 of the third lens E3. The partially reflective layer BS may be attached to the near-emission portion side S6 of the third lens E3.

In this example, the emitting portion may be provided with a light source. After the image light from the emission portion passes through the third lens E3, the quarter-wave plate QWP, the second lens E2, and reaches the reflective polarizing element RP on the near-receiving portion side of the first lens E1 in order, the first reflection occurs at the reflective polarizing element RP. After the light reflected once passes through the first lens E1, the second lens E2, the quarter wave plate QWP and reaches the partially reflective layer BS on the near-emission portion side of the third lens E3, a second reflection occurs at the partially reflective layer BS. The light reflected for the second time passes through the third lens E3, the quarter wave plate QWP, the second lens E2, the first lens E1, the reflective polarizing element RP, and finally, the receiving part in the projection space in this order. For example, the light reflected by the optical system twice is finally projected into eyes of a user.

Table 5 shows a basic parameter table of the optical system of the third embodiment, in which the unit of curvature radius, thickness/distance is millimeter (mm). The image light from the emitting portion passes through the elements in the order of number 21 to number 1 and is finally projected into a receiving portion such as human eyes in the space.

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TABLE 5

In this embodiment, the total effective focal length f of the optical system is 16.93mm, the effective focal length f1 of the first lens is 68.97mm, the effective focal length f2 of the second lens is-959.16 mm, the effective focal length f3 of the third lens is 108.59mm, the value of half of the maximum field angle Semi-FOV of the optical system is 50.0 °, and the on-axis distance SAG22 from the intersection point of the second side surface of the second lens and the optical axis to the effective half-caliber vertex of the second side surface of the second lens is-2.31 mm.

In the third embodiment, the near-receiving portion side surface S1 and the near-emitting portion side surface S2 of the first lens E1, the near-receiving portion side surface S3 and the near-emitting portion side surface S4 of the second lens E2, and the near-receiving portion side surface S5 and the near-emitting portion side surface S6 of the third lens E3 are aspherical surfaces. Table 6 shows the cone coefficients K and polynomial coefficients a for the respective aspherical mirror surfaces S1-S6 that can be used in the third embodiment ₀ 、a ₁ 、a ₂ And a ₃ 。

Face number	K	a0	a1	a2	a3
						S1	0.0000	3.54E-01	1.05E-02	0.00E+00	0.00E+00
S2	0.0000	8.96E+00	-2.52E-01	2.36E-01	-1.79E-01
						S3	0.0000	1.43E+00	7.52E-02	8.56E-02	-2.73E-02
S4	-1.0000	2.75E+01	-1.18E+01	3.54E+00	8.80E-02
						S5	0.0000	4.57E+00	-1.41E+00	1.16E-01	-1.06E-01
S6	0.0000	4.00E+00	9.13E-01	1.01E-01	-1.18E-01

TABLE 6

Fig. 14A shows on-axis chromatic aberration curves of the

optical systems

310 and 320 of the third embodiment, which represent the convergent focus deviation of light rays of different wavelengths after passing through the

optical systems

310 and 320. Fig. 14B shows astigmatism curves of the

optical systems

310 and 320 of the third embodiment, which represent meridional image plane curvature and sagittal image plane curvature corresponding to different half angles of view. Fig. 14C shows distortion curves of the

optical systems

310 and 320 of the third embodiment, which represent distortion magnitude values corresponding to different half angles of view. As can be seen from fig. 14A to 14C, the

optical systems

310 and 320 according to the third embodiment can achieve good imaging quality.

Fourth embodiment

An optical system according to a fourth embodiment of the present application is described below with reference to fig. 15 to 18C. Fig. 15 shows a schematic optical path diagram of an optical system according to a fourth embodiment of the present application; fig. 16 shows a schematic structural view of an optical system 410 of example 1 according to a fourth embodiment of the present application; fig. 17 shows a schematic configuration of an optical system 420 according to example 2 of the fourth embodiment of the present application.

As shown in fig. 15 to 17, each of the

optical systems

410, 420 includes a lens barrel P0, and a lens group, a reflection assembly, and a spacer group disposed within the lens barrel P0. The lens group sequentially comprises from a first side to a second side: a first lens E1, a second lens E2, and a third lens E3. The stop STO may be disposed between the receiving portion and the first lens E1. In the present embodiment, the first side refers to the receiving portion side, and the second side refers to the transmitting portion side. The reflection assembly includes: a reflective polarizing element RP, a quarter wave plate QWP and a partially reflective layer BS, wherein the reflective polarizing element RP is disposed between the receiving portion and the first lens E1, and the quarter wave plate QWP is disposed between the second lens E2 and the third lens E3. The spacer group includes: a first spacer P1 and a second spacer P2. In the present embodiment, the first side surfaces of the respective elements (the first lens E1, the second lens E2, the third lens E3, the reflective polarizing element RP, the quarter-wave plate QWP, and the partially reflective layer BS) are each referred to as a near-receiving portion side surface, and the second side surfaces are each referred to as a near-emitting portion side surface.

The first lens E1 has positive optical power, and its near-receiving portion side surface S1 is a plane and its near-emitting portion side surface S2 is a convex surface. The second lens E2 has positive power, and its near-receiving portion side S3 is concave and near-emitting portion side S4 is convex. The third lens E3 has positive power, and its near-receiving portion side surface S5 is concave and near-emitting portion side surface S6 is convex. The reflective polarizer RP may be attached to the near-receiving portion side surface S1 of the first lens E1. A quarter wave plate QWP may be attached to the near-receiving portion side S5 of the third lens E3. The partially reflective layer BS may be attached to the near-emission portion side S6 of the third lens E3.

Table 7 shows a basic parameter table of the optical system of the fourth embodiment, in which the unit of curvature radius, thickness/distance is millimeter (mm). The image light from the emitting portion passes through the elements in the order of number 21 to number 1 and is finally projected into a receiving portion such as human eyes in the space.

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TABLE 7

In this embodiment, the total effective focal length f of the optical system is 16.60mm, the effective focal length f1 of the first lens is 126.67mm, the effective focal length f2 of the second lens is 216.92mm, the effective focal length f3 of the third lens is 136.93mm, the half of the maximum field angle Semi-FOV of the optical system is 50.0 °, and the on-axis distance SAG22 from the intersection point of the second side surface of the second lens and the optical axis to the effective half-caliber vertex of the second side surface of the second lens is-1.89 mm.

In the third embodiment, the near-emitting portion side surface S2 of the first lens E1, the near-receiving portion side surface S3 and the near-emitting portion side surface S4 of the second lens E2, and the near-receiving portion side surface S5 and the near-emitting portion side surface S6 of the third lens E3 are aspherical surfaces. Table 8 shows the cone coefficients K and the polynomial coefficients a of the respective aspherical mirror surfaces S2 to S6 which can be used in the third embodiment ₀ 、a ₁ 、a ₂ And a ₃ 。

Face number	K	a0	a1	a2	a3
						S2	5.8844	4.47E+00	-7.11E-01	1.43E-01	6.94E-02
S3	0.0000	2.26E-01	2.34E-01	6.41E-02	0.00E+00
						S4	0.0000	-1.14E-01	5.43E-01	-1.77E-02	-3.50E-02
S5	0.0000	3.45E-01	2.04E-01	-3.55E-02	0.00E+00
						S6	0.0000	-4.69E-01	2.00E-01	4.70E-02	1.29E-02

TABLE 8

Fig. 18A shows on-axis chromatic aberration curves of the

optical systems

410 and 420 of the fourth embodiment, which represent the convergent focus deviation of light rays of different wavelengths after passing through the

optical systems

410 and 420. Fig. 18B shows astigmatism curves of the

optical systems

410 and 420 of the fourth embodiment, which represent meridional image plane curvature and sagittal image plane curvature corresponding to different half angles of view. Fig. 18C shows distortion curves of the

optical systems

410 and 420 of the fourth embodiment, which represent distortion magnitude values corresponding to different half angles of view. As can be seen from fig. 18A to 18C, the

optical systems

410 and 420 according to the fourth embodiment can achieve good imaging quality.

Table 9 gives some basic parameters of the lens barrel P0, the spacer, such as D1s, D1m, D2s, D2m, D0s, D0m, EP01, CP1, EP12, CP2, and the like, of each of the examples in the first to fourth embodiments. The basic parameters listed in table 9 were measured according to the labeling method shown in fig. 1, and the basic parameters listed in table 9 were all measured in millimeters (mm).

Parameters/embodiments	1-1	1-2	2-1	2-2	3-1	3-2	4-1	4-2
									d1s	50.410	52.443	45.154	44.952	45.471	45.471	46.259	46.259
d1m	51.550	52.443	46.122	45.598	45.471	45.471	46.780	46.780
									D1s	53.087	55.369	47.830	47.474	49.160	48.860	48.935	48.935
D1m	53.952	55.369	49.024	48.300	49.160	48.860	49.532	49.532
									d2s	52.675	52.675	47.506	49.718	46.671	46.671	46.481	46.481
D2s	55.351	55.351	50.183	53.410	49.347	49.047	49.772	50.072
									D2m	56.936	56.536	50.695	53.410	50.157	50.157	50.369	50.669
d0s	45.912	48.274	44.490	44.270	45.564	45.564	46.272	46.272
									d0m	59.580	58.680	53.278	54.473	52.473	52.307	52.502	52.502
D0s	54.281	54.281	49.381	49.161	50.456	50.456	51.163	51.163
									D0m	61.990	60.880	55.478	56.673	54.673	54.507	54.702	54.532
EP01	3.119	3.885	3.219	2.968	2.576	2.419	2.988	2.699
									CP1	1.004	0.100	1.561	1.561	0.100	0.100	2.554	2.354
EP12	1.015	1.252	1.740	2.698	2.696	2.496	1.585	1.785
									CP2	1.331	1.281	1.330	0.100	2.630	2.730	1.401	1.401

Table 9 shows the values of the conditional expressions of the examples in the first to fourth embodiments in summary, table 10.

Condition/example	1-1	1-2	2-1	2-2	3-1	3-2	4-1	4-2
									\|R4×CT2\|/(D2m×CP2)	14.80	15.48	4.69	59.25	0.61	0.59	6.20	6.16
f1/f	29.68	29.68	23.70	23.70	4.07	4.07	7.63	7.63
									f2/f	5.29	5.29	3.98	3.98	-56.66	-56.66	13.07	13.07
f3/f	20.39	20.39	28.67	28.67	6.41	6.41	8.25	8.25
									TAN(Semi-FOV)×(d0m-d0s)/f	0.86	0.65	0.67	0.78	0.49	0.47	0.45	0.45
f1/(D1s+D1m)	4.42	4.27	3.82	3.87	0.70	0.71	1.29	1.29
									(d1s+d1m)/f	6.40	6.58	5.84	5.79	5.37	5.37	5.60	5.60
(EP01+CP1)/(CT1+T12+d _RP )	0.98	0.95	1.21	1.14	0.57	0.54	1.73	1.57
									\|f1+f2\|/(D1m+D2s)	5.10	5.03	4.36	4.25	9.04	9.09	3.46	3.45
\|R3×T12\|/(d2s×CP2)	0.57	0.60	2.49	31.61	0.16	0.15	13.96	13.96
									\|f2×T23\|/\|EP12×SAG22\|	28.96	23.46	4.55	2.93	61.54	66.47	39.05	34.67
f3/(d _QWP +CT3+CP2+EP12)	50.82	49.37	75.83	79.48	10.54	10.64	19.24	18.72
									(R5+R6)/(D0s+D0m)	-1.26	-1.27	-1.19	-1.18	-1.23	-1.23	-2.28	-2.29

Table 10

The present application also provides an optical apparatus that may be a stand-alone projection device, such as a projector, or may be a projection module integrated on a mobile electronic device, such as a VR/AR. The optical device is equipped with the optical system described above.

The foregoing description is only of the preferred embodiments of the present application and is presented as a description of the principles of the technology being utilized. It will be appreciated by persons skilled in the art that the scope of the invention referred to in this application is not limited to the specific combinations of features described above, but also covers other technical solutions which may be formed by any combination of the features described above or their equivalents without departing from the inventive concept. Such as the above-described features and technical features having similar functions (but not limited to) disclosed in the present application are replaced with each other.

Claims

1. An optical system, comprising:

a lens group including a first lens, a second lens, and a third lens sequentially arranged from a first side to a second side along an optical axis;

The reflection assembly comprises a reflection type polarizing element, a quarter wave plate and a partial reflection layer;

a spacer group including a second spacer interposed between the second lens and the third lens and in contact with a second side of the second lens; and

a lens barrel in which the lens group, the reflection assembly, and the spacer group are disposed,

wherein a curvature radius R4 of the second side surface of the second lens, a center thickness CT2 of the second lens on the optical axis, an outer diameter D2m of the second side surface of the second spacer, and a maximum thickness CP2 of the second spacer satisfy: 0.5< |R4×CT2|/(D2 m×CP2) <60.0.

2. The optical system of claim 1, wherein an effective focal length f1 of the first lens and a total effective focal length f of the optical system satisfy: 4.0< f1/f <30.0, the effective focal length f2 of the second lens and the total effective focal length f of the optical system satisfying: -57.0< f2/f <14.0, and the effective focal length f3 of the third lens and the total effective focal length f of the optical system satisfy: 6.0< f3/f <29.0.

3. The optical system according to claim 1, wherein a total effective focal length f of the optical system, a half of a maximum field angle Semi-FOV of the optical system, an inner diameter d0s of a first side end surface of the lens barrel, and an inner diameter d0m of a second side end surface of the lens barrel satisfy: 0.2< TAN (Semi-FOV) × (d 0m-d0 s)/f <1.0.

4. The optical system of any of claims 1-3, wherein the spacer group further comprises a first spacer disposed between the first lens and the second lens and in contact with the second side of the first lens,

wherein an effective focal length f1 of the first lens, an outer diameter D1s of the first side surface of the first spacer, and an outer diameter D1m of the second side surface of the first spacer satisfy: 0.5< f 1/(d1s+d1m) <4.5.

5. The optical system of any of claims 1-3, wherein the spacer group further comprises a first spacer disposed between the first lens and the second lens and in contact with the second side of the first lens,

wherein the total effective focal length f of the optical system, the inner diameter d1s of the first side surface of the first spacer, and the inner diameter d1m of the second side surface of the first spacer satisfy: 5.0< (d1s+d1m)/f <7.0.

6. The optical system of any of claims 1-3, wherein the spacer group further comprises a first spacer disposed between the first lens and the second lens and in contact with the second side of the first lens,

Wherein, the interval EP01 between the first side end surface of the lens barrel and the first spacer along the optical axis, the maximum thickness CP1 of the first spacer, the center thickness CT1 of the first lens on the optical axis, the air interval T12 between the first lens and the second lens on the optical axis and the center thickness d of the reflective polarizing element on the optical axis _RP The method meets the following conditions: 0.5<(EP01+CP1)/(CT1+T12+d _RP )<2.0。

7. The optical system of any of claims 1-3, wherein the spacer group further comprises a first spacer disposed between the first lens and the second lens and in contact with the second side of the first lens,

wherein an effective focal length f1 of the first lens, an effective focal length f2 of the second lens, an outer diameter D1m of the second side surface of the first spacer, and an outer diameter D2s of the first side surface of the second spacer satisfy: 3.0< |f1+f2|/(d1m+d2s) <10.0.

8. An optical system according to any one of claims 1-3, characterized in that the radius of curvature R3 of the first side of the second lens, the air spacing T12 of the first and second lenses on the optical axis, the inner diameter d2s of the first side of the second spacer and the maximum thickness CP2 of the second spacer satisfy: 0< |R3×T12|/(d2s×CP2) <32.0.

9. The optical system of any of claims 1-3, wherein the spacer group further comprises a first spacer disposed between the first lens and the second lens and in contact with the second side of the first lens,

wherein an effective focal length f2 of the second lens, an air interval T23 of the second lens and the third lens on the optical axis, an on-axis distance SAG22 from an intersection point of an interval EP12 of the first spacer and the second spacer along the optical axis with the second side surface of the second lens and the optical axis to an effective half-caliber vertex of the second side surface of the second lens, satisfy: 2.0< |f2×t23|/|ep12×sag22| <67.0.

10. The optical system of any of claims 1-3, wherein the spacer group further comprises a first spacer disposed between the first lens and the second lens and in contact with the second side of the first lens,

wherein the effective focal length f3 of the third lens, the center thickness CT3 of the third lens on the optical axis, and the center thickness d of the quarter wave plate on the optical axis _QWP The spacing EP12 of the first and second spacers along the optical axis and the maximum thickness CP2 of the second spacers satisfy: 10.0 <f3/(d _QWP +CT3+CP2+EP12)<80.0。