CN116466488A

CN116466488A - Optical system and optical apparatus including the same

Info

Publication number: CN116466488A
Application number: CN202310341054.3A
Authority: CN
Inventors: 戴付建; 冯梦怡; 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: 2023-03-29
Filing date: 2023-03-29
Publication date: 2023-07-21

Abstract

The application discloses optical system and optical device including this optical system, this optical system includes in order from first side to second side along the optical axis: the optical lens comprises a first lens, a second lens, a reflective polarizing element, a quarter wave plate and a third lens, wherein the second side surface of the second lens is a plane; the second side surface of the third lens is provided with a partial reflecting layer; and the radius of curvature R1 of the first side surface of the first lens, the center thickness CT1 of the first lens on the optical axis, and the abbe number V1 of the first lens satisfy: 55.0 < R1/CT1+R1/V1 < 221.

Description

Optical system and optical apparatus including the same

Technical Field

The present application relates to the field of optical elements, and more particularly, to an optical system and an optical apparatus including the same.

Background

Since the concept of "meta-universe" was proposed, AR/VR came to the second time of development. The optical system plays an important role as an entrance for human-machine interaction in AR/VR devices, for example. The virtual reality head-mounted display device, namely VR glasses, is a device based on human-computer interaction and provided with a certain immersive experience. The user can see the enlarged virtual image formed by the screen after wearing the screen, and meanwhile, the parallax existing between the two eyes increases the stereoscopic impression of the screen.

The traditional fresnel optical path uses a large-sized display and a thicker lens, resulting in a VR device that is bulky and heavy, greatly reducing the user experience. However, the refraction-reflection optical scheme changes the structure of the Fresnel lens light path, shortens the total length of the light path, saves the assembly space, reduces the weight and makes the Fresnel lens light path the main direction of the VR device.

The optical path of the catadioptric optical system is complex, and the difference of the lens shape and the lens assembly position can lead to the difference of the performance of the optical system, so that the arrangement of the lens and the reflecting element is reasonably designed, and the catadioptric optical system with good imaging quality is one of the hot spots of the current research.

Disclosure of Invention

The application provides an optical system, the optical system includes in order from first side to second side along the optical axis: the optical lens comprises a first lens, a second lens, a reflective polarizing element, a quarter wave plate and a third lens, wherein the second side surface of the second lens is a plane; the second side surface of the third lens is provided with a partial reflecting layer; and the radius of curvature R1 of the first side surface of the first lens, the center thickness CT1 of the first lens on the optical axis, and the abbe number V1 of the first lens satisfy: 55.0 < R1/CT1+R1/V1 < 221.

In one embodiment, the effective focal length f1 of the first lens, the refractive index N1 of the first lens, and the radius of curvature R2 of the second side surface of the first lens satisfy: -12.0 < f1×n1/R2 < -2.0.

In one embodiment, the effective focal length f2 of the second lens, the refractive index N2 of the second lens, and the radius of curvature R3 of the first side of the second lens satisfy: 2.0 < f2×N2/R3 < 3.0.

In one embodiment, 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 satisfy: CT1/T12 is more than 6.0 and less than 20.0.

In one embodiment, the effective focal length f3 of the third lens, the refractive index N3 of the third lens, and the radius of curvature R6 of the second side surface of the third lens satisfy: -2.5 < f3XN3/R6 < -1.5.

In one embodiment, the radius of curvature R5 of the first side of the third lens, the radius of curvature R6 of the second side of the third lens, the center thickness CT3 of the third lens on the optical axis, and the air interval T23 of the second lens and the third lens on the optical axis satisfy: 4.0 < |R5/R6|+CT3/T23 < 5.0.

In one embodiment, the center thickness dqwp of the quarter wave plate on the optical axis, the air interval T23 of the second and third lenses on the optical axis, the center thickness CT3 of the third lens on the optical axis, and the distance TD between the first side of the first lens and the second side of the third lens on the optical axis satisfy: 1.5 < 3× (dqwp+T23+CT3)/TD < 2.5.

In one embodiment, the center thickness CT1 of the first lens on the optical axis, the center thickness CT2 of the second lens on the optical axis, the center thickness CT3 of the third lens on the optical axis, the center thickness dqwp of the quarter-wave plate on the optical axis, and the center thickness drp of the reflective polarizing element on the optical axis satisfy: 0.5 < CT 3/(CT1+CT2+drp+dqwp) < 2.0.

In one embodiment, the effective focal length f3 of the third lens, the maximum half field angle Semi-FOV of the optical system, and the radius of curvature R6 of the second side of the third lens satisfy: -2.5 < f3×tan (Semi-FOV)/R6 < -1.5.

In one embodiment, the radius of curvature R1 of the first side surface of the first lens, the radius of curvature R3 of the first side surface of the second lens, the abbe number V2 of the second lens, and the abbe number V1 of the first lens satisfy: 4.0 < |R1/R3|+V2/V1 < 7.0.

In one embodiment, the effective focal length f2 of the second lens, the abbe number Vrp of the reflective polarizing element, and the abbe number Vqwp of the quarter-wave plate satisfy: 1.0 < |f2|/(Vrp+Vqwp) < 2.5.

In another aspect, the present application also provides an optical apparatus including the optical system provided in at least one of the foregoing embodiments.

The optical system provided by the application is a three-piece type refraction-reflection optical system, on one hand, the light path refraction-reflection is realized by utilizing the additional function of the quarter wave plate on the polarized light phase, the light splitting function of the reflective polarizing element and the reflection function of the partial reflection layer, so that the height of the body can be better compressed, and the imaging quality is improved; on the other hand, the curvature radius of the first side surface of the first lens, the center thickness and the Abbe number of the first lens are controlled, so that the lens is beneficial to processing and forming of the lens, chromatic aberration of a correction system is beneficial to correction, system performance is improved, and experience of consumers is improved.

Drawings

Other features, objects and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments, taken in conjunction with the accompanying drawings. In the drawings:

fig. 1A is a diagram of a position distribution diagram and an optical path of a diaphragm, a first lens, a second lens, a reflective polarizing element, a quarter-wave plate, a third lens, and a partially reflective layer in an optical system according to an embodiment of the present application;

FIG. 1B is a schematic diagram of a ghost image produced by an optical system of the prior art;

FIG. 1C shows a schematic diagram of a portion of parameters of an optical system according to the present application;

fig. 2 shows a schematic structural view of an optical system according to embodiment 1 of the present application;

fig. 3A to 3C show an on-axis chromatic aberration curve, an astigmatism curve, and a distortion curve, respectively, of the optical system according to embodiment 1 of the present application;

fig. 4 shows a schematic structural view of an optical system according to embodiment 2 of the present application;

fig. 5A to 5C show an on-axis chromatic aberration curve, an astigmatism curve, and a distortion curve of the optical system according to embodiment 2 of the present application, respectively;

fig. 6 shows a schematic structural view of an optical system according to embodiment 3 of the present application;

fig. 7A to 7C show an on-axis chromatic aberration curve, an astigmatic curve, and a distortion curve of the optical system according to embodiment 3 of the present application, respectively;

fig. 8 shows a schematic structural view of an optical system according to embodiment 4 of the present application;

fig. 9A to 9C show an on-axis chromatic aberration curve, an astigmatism curve, and a distortion curve of the optical system according to embodiment 4 of the present application, respectively;

fig. 10 shows a schematic structural view of an optical system according to embodiment 5 of the present application;

fig. 11A to 11C show an on-axis chromatic aberration curve, an astigmatism curve, and a distortion curve of the optical system according to embodiment 5 of the present application, respectively;

fig. 12 shows a schematic structural view of an optical system according to embodiment 6 of the present application; and

fig. 13A to 13C show an on-axis chromatic aberration curve, an astigmatism curve, and a distortion curve of the optical system according to embodiment 6 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. The expression "and/or" includes any and all combinations of one or more of the associated listed items.

It should be noted that in this specification, the expressions first, second, etc. are only used to distinguish one feature from another feature, and do not represent any limitation of the feature. Accordingly, a first lens discussed below may also be referred to as a second lens, and a second lens may also be referred to as a first 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. In particular, 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.

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 a statement such as "at least one of the following" appears after a list of features that are listed, the entire listed feature is modified instead of modifying a separate element in the list. 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 with reference to the accompanying drawings and in connection with the embodiments.

The optical system according to an exemplary embodiment of the present application includes, in order from a first side to a second side along an optical axis: the optical lens comprises a first lens, a second lens, a reflective polarizing element, a quarter wave plate and a third lens.

In an exemplary embodiment, the first side of the reflective polarizing element is attached to the second side of the second lens, and the second side of the reflective polarizing element is attached to the first side of the quarter wave plate.

In an exemplary embodiment, the reflective polarizing element and the quarter wave plate are combined, and a required structure can be obtained through one-time attaching procedure operation instead of two-time attaching, so that the angle position error caused by attaching is reduced, and the imaging quality is improved.

In an exemplary embodiment, as shown in fig. 1A, an optical system according to the present application may be applied to, for example, a VR device, a first side may be, for example, a human eye side, a second side may be, for example, a screen side, and the optical system sequentially includes, along an optical axis, from the human eye side to the screen side: the lens system includes a first lens E1, a second lens E2, a reflective polarizing element RP, a quarter wave plate QWP, a third lens E3 and a partially reflective layer BS. The reflective polarizer RP may be attached to the near-screen side of the second lens E2, and the quarter-wave plate QWP may be attached to the near-screen side of the reflective polarizer RP. The partially reflective layer BS may have a semi-transmitting and semi-reflecting function. The partially reflective layer BS is, for example but not limited to, a mirror, which is capable of reflecting a portion of the light. For example, in some cases the partially reflective layer BS may be configured to allow a portion of light to be transmitted and another portion to be reflected when light passes through.

In an exemplary embodiment, as shown in fig. 1A, the optical system according to the present application further includes a stop STO provided on the human eye side and a display screen E4 provided on the screen side. The user's eyes can view the image projected from the display screen E4 at the position of the aperture stop, i.e. the image light on the display screen E4 is refracted and reflected for many times by the third lens E3, the quarter wave plate QWP, the reflective polarizing element RP, the second lens E2, the first lens E1, etc., and finally projected to the user's eyes.

Fig. 1A also shows a schematic view of the optical path turn-back of the optical system according to the present application, where the light emitted from the display screen E4 sequentially passes through the third lens E3, the quarter wave plate QWP, and reaches the reflective polarizing element RP, where it is reflected and passes through the quarter wave plate QWP and the third lens E3 again, where the light beam is reflected again at the partial reflection layer BS on the near-screen side of the third lens E3 and passes through the third lens E3, the quarter wave plate QWP, the reflective polarizing element RP, the second lens E2, and the first lens E1 in order, passes through the stop STO, and finally exits toward the human eye side. Compared with the ghost image generated by the optical system in the prior art shown in fig. 1B, the ghost image in the optical system can be greatly reduced by the optical system provided by the application. In addition, the optical path can be folded in a required mode through light reflection and refraction combination, and the length of an optical system can be effectively shortened.

To facilitate better understanding of the present invention, fig. 1C shows a schematic diagram of part of parameters of an optical system according to the present application, as shown in fig. 1C, CT1 represents a center thickness of a first lens on an optical axis, CT2 represents a center thickness of a second lens on the optical axis, CT3 represents a center thickness of a third lens on the optical axis, T12 represents an air space between the first lens and the second lens on the optical axis, T23 represents an air space between the second lens and the third lens on the optical axis, R1 represents a radius of curvature of a first side surface of the first lens, R2 represents a radius of curvature of a second side surface of the first lens, R3 represents a radius of curvature of a first side surface of the second lens, R4 represents a radius of curvature of a second side surface of the second lens, R5 represents a radius of curvature of a first side surface of the third lens, and R6 represents a radius of curvature of a second side surface of the third lens.

The optical system according to an exemplary embodiment of the present application includes, in order from a first side to a second side along an optical axis: the optical lens comprises a first lens, a second lens, a reflective polarizing element, a quarter wave plate and a third lens, wherein the second side surface of the second lens is a plane; the second side surface of the third lens is provided with a partial reflecting layer; and the radius of curvature R1 of the first side surface of the first lens, the center thickness CT1 of the first lens on the optical axis, and the abbe number V1 of the first lens satisfy: 55.0 < R1/CT1+R1/V1 < 221. The combination of the first lens, the second lens and the third lens can collect light, film coating or film pasting is carried out on the surface of the lens, the light path can be folded back, the length of an optical system is shortened, specifically, the reflective polarizing element can reflect polarized light in a certain direction, polarized light orthogonal to the polarized direction can be transmitted, the quarter wave plate can change the state of the polarized light, and the partial reflecting layer arranged on the second side surface of the third lens can transmit half of the light and reflect the other half of the light. Further, by controlling the curvature radius of the first side surface of the first lens and the center thickness and Abbe number of the first lens, on one hand, the lens is beneficial to processing and forming; on the other hand, the color difference of the system is corrected, the system performance is improved, and the experience of consumers is improved.

In an exemplary embodiment, the optical system of the present application may satisfy: -12.0 < f1×n1/R2 < -2.0, wherein f1 is the effective focal length of the first lens, N1 is the refractive index of the first lens, and R2 is the radius of curvature of the second side of the first lens. Satisfies-12.0 < f1xN1/R2 < -2.0, and is beneficial to reasonably distributing focal power, converging light rays and improving imaging quality by controlling the effective focal length and refractive index of the first lens and the curvature radius of the second side surface of the lens; while facilitating correction of aberrations of the system.

In an exemplary embodiment, the optical system of the present application may satisfy: 2.0 < f2×n2/R3 < 3.0, where f2 is the effective focal length of the second lens, N2 is the refractive index of the second lens, and R3 is the radius of curvature of the first side of the second lens. Satisfies 2.0 < f2×N2/R3 < 3.0, and is favorable for reasonably distributing optical power by controlling the effective focal length of the second lens, and the optical path can be optimized and the imaging quality can be improved by controlling the refractive index of the second lens; in addition, the curvature radius of the first side surface of the second lens is controlled, so that the height of light rays can be reduced, and the size of the optical system can be reduced.

In an exemplary embodiment, the optical system of the present application may satisfy: CT1/T12 is less than 20.0, wherein CT1 is the center thickness of the first lens on the optical axis, and T12 is the air interval between the first lens and the second lens on the optical axis. The method meets the requirements that CT1/T12 is smaller than 6.0 and smaller than 20.0, and is beneficial to forming the first lens and reducing the processing difficulty by controlling the center thickness of the first lens and the ratio of the air interval of the first lens and the second lens on the optical axis; on the other hand, the total length of the optical system is effectively limited, so that the optical equipment is more miniaturized.

In an exemplary embodiment, the optical system of the present application may satisfy the conditional expression-2.5 < f3xn3/r6 < -1.5, where f3 is the effective focal length of the third lens, N3 is the refractive index of the third lens, and R6 is the radius of curvature of the second side of the third lens. Satisfies-2.5 < f3XN3/R6 < -1.5, reasonably controls the focal power of the system and reduces the height of light rays by controlling the effective focal length and refractive index of the third lens and the curvature radius of the second side surface of the third lens, thereby reducing ghost images caused by edge reflection of the lens; and simultaneously, the formability of the third lens is also facilitated.

In an exemplary embodiment, the optical system of the present application may satisfy: 4.0 < |R5/R6|+CT3/T23 < 5.0, wherein R5 is the radius of curvature of the first side of the third lens, R6 is the radius of curvature of the second side of the third lens, CT3 is the center thickness of the third lens on the optical axis, and T23 is the air gap between the second lens and the third lens on the optical axis. Satisfies 4.0 < |R5/R6|+CT3/T23 < 5.0, and is beneficial to the compactness of the system, the total length of the optical system is reduced, the weight of the optical equipment is lighter, and the user experience is enhanced by controlling the ratio of the radius of curvature of the first side surface of the third lens to the radius of curvature of the second side surface of the third lens, the center thickness of the lens and the air interval between the second lens and the third lens; in addition, the processing and forming of the third lens are facilitated.

In an exemplary embodiment, the optical system of the present application may satisfy: 1.5 < 3× (dqwp+t23+ct 3)/TD < 2.5, wherein dqwp is the center thickness of the quarter wave plate on the optical axis, T23 is the air space between the second lens and the third lens on the optical axis, CT3 is the center thickness of the third lens on the optical axis, and TD is the distance between the first side of the first lens and the second side of the third lens on the optical axis. Satisfying 1.5 < 3× (dqwp+T23+CT3)/TD < 2.5, the tolerance of the lens assembly process is reasonably distributed by controlling the center thickness of the quarter wave plate, the air interval between the second lens and the third lens and the distance between the center thickness of the third lens and the first side surface of the first lens and the second side surface of the third lens on the optical axis, the total length of the system light path is effectively limited, the system is more compact, and the weight of equipment is reduced; meanwhile, the quarter wave plate is beneficial to being attached to or plated on the lens, and the manufacturability difficulty of film pasting or plating is reduced.

In an exemplary embodiment, the optical system of the present application may satisfy: CT 3/(Ct1+Ct2+drp+dqwp) < 2.0, wherein CT1 is the center thickness of the first lens on the optical axis, CT2 is the center thickness of the second lens on the optical axis, CT3 is the center thickness of the third lens on the optical axis, dqwp is the center thickness of the quarter wave plate on the optical axis, drp is the center thickness of the reflective polarizing element on the optical axis. The thickness of the lenses is effectively distributed by controlling the center thicknesses of the first lens and the second lens and the center thicknesses of the quarter wave plate and the reflective polarizing element, so that the system is more compact, the trend of light is optimized, and meanwhile, the formability of the first lens and the second lens is improved.

In an exemplary embodiment, the optical system of the present application may satisfy: -2.5 < f3×tan (Semi-FOV)/R6 < -1.5, wherein f3 is the effective focal length of the third lens, semi-FOV is the maximum half field angle of the optical system, R6 is the radius of curvature of the second side of the third lens. Satisfies-2.5 < f3×tan (Semi-FOV)/R6 < -1.5, and by controlling the effective focal length of the third lens and the tangent of the maximum half field angle and the radius of curvature of the second side surface of the third lens, the height of light can be further restricted on the premise of ensuring the field angle, thereby reducing the size of the display screen, and on the other hand, reducing ghost images introduced by reflection of the display screen and the lens.

In an exemplary embodiment, the optical system of the present application may satisfy: 4.0 < |R1/R3|+V2/V1 < 7.0, wherein R1 is the radius of curvature of the first side of the first lens, R3 is the radius of curvature of the first side of the second lens, V2 is the Abbe number of the second lens, and V1 is the Abbe number of the first lens. Satisfies 4.0 < |R1/R3|+V2/V1 < 7.0, and is beneficial to reducing chromatic aberration of the system and improving relative illuminance and imaging quality of the system by controlling the curvature radius of the first side surfaces of the first lens and the second lens and Abbe numbers of the first lens and the second lens; in addition, good processability of the lens can be ensured.

In an exemplary embodiment, the optical system of the present application may satisfy: 1.0 < |f2|/(Vrp+Vqwp) < 2.5, where f2 is the effective focal length of the second lens, vrp is the Abbe number of the reflective polarizing element, and Vqwp is the Abbe number of the quarter-wave plate. Satisfies 1.0 < |f2|/(Vrp+Vqwp) < 2.5, and by controlling the effective focal length of the second lens, the Abbe number of the reflective polarizing element and the Abbe number of the quarter-wave plate, the focal power of the second lens is more reasonable, meanwhile, the chromatic aberration introduced by the reflective polarizing element and the quarter-wave plate is reduced, and the imaging quality of the system is improved.

In an exemplary embodiment, the effective focal length f1 of the first lens may be, for example, in the range of-1167.0 mm to 78.0mm, the effective focal length f2 of the second lens may be, for example, in the range of-158.0 mm to 230.0mm, and the effective focal length f3 of the third lens may be, for example, in the range of 146.0mm to 212.0 mm.

According to some embodiments of the present application, the optical system according to the present application is a low-volume optical system of high definition imaging quality, and in application, the optical system according to the exemplary embodiments of the present application may be suitable for VR devices. By reasonably setting the effective focal length, the maximum field angle, the entrance pupil diameter, the center thickness of the lens, the refractive index, the Abbe number, the curvature radius and other parameters of the optical system, and by reasonably setting the diaphragm parameters, the purpose of wide angle of the VR device can be met, the chromatic aberration of the system can be corrected, and the imaging quality of the system can be improved.

In an exemplary embodiment, the optical system provided herein may be applied to, for example, VR devices, where the first side may be, for example, the human eye side and the second side may be, for example, the screen side.

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

Example 1

An optical system according to embodiment 1 of the present application is described below with reference to fig. 2 to 3C. Fig. 2 shows a schematic configuration of an optical system according to embodiment 1 of the present application.

As shown in fig. 2, the optical system sequentially includes, from a human eye side to a screen side: a stop STO, a first lens E1, a second lens E2, a reflective polarizing element RP, a quarter wave plate QWP, a third lens E3, a partially reflective layer BS, and a display screen E4.

The first lens E1 has positive focal power, and has a convex near-eye side and a convex near-screen side. The second lens E2 has negative focal power, and the side surface near the human eye is concave and the side surface near the screen is plane. The third lens E3 has positive power, and has a convex near-eye side and a convex near-screen side. The reflective polarizer RP is attached to the near-screen side of the second lens E2, and the quarter-wave plate QWP is attached to the near-screen side of the reflective polarizer RP. The partially reflecting layer BS is attached to the near-screen side of the third lens E3.

In this example, a light source may be provided on the display screen E4. The image light from the display screen E4 sequentially passes through the third lens E3, the quarter-wave plate QWP, and reaches the reflective polarizing element RP, is reflected at the reflective polarizing element RP for the first time and passes through the quarter-wave plate QWP, the third lens E3 again, and the light beam is reflected at the partial reflection layer BS on the near-screen side of the third lens E3 for the second time and passes through the third lens E3, the quarter-wave plate QWP, the reflective polarizing element RP, the second lens E2, and the first lens E1 in this order, passes through the aperture stop STO, and finally exits toward the human eye side.

In this example, the effective focal length f1 of the first lens is 75.94mm, the effective focal length f2 of the second lens is-153.86 mm, the effective focal length f3 of the third lens is 211.87mm, and the maximum half field angle Semi-FOV of the optical system is 53.0 °.

Table 1 shows basic parameters of the optical system of example 1, in which the unit of radius of curvature and thickness are both millimeters (mm). The image light from the display screen E4 passes through the respective components in the order of serial number 16 to serial number 1 and is finally projected into a target object in space such as human eyes.

TABLE 1

In embodiment 1, the near-human eye side and near-screen side of the first lens E1, the near-human eye side of the second lens E2, and the near-human eye side and near-screen side of the third lens E3 are all aspherical, and the surface profile x of each aspherical lens can be defined by, but not limited to, the following aspherical formula:

wherein x is the distance vector height from the vertex of the aspheric surface when the aspheric surface is at the position with the height h along the optical axis direction; c is the paraxial curvature of the aspheric surface, c=1/R (i.e., paraxial curvature c is the inverse of radius of curvature R in table 1 above); k is a conic coefficient, and in this embodiment and the following embodiments, the conic coefficient is 0; ai is the correction coefficient of the aspherical i-th order.

The higher order coefficients A4, A6, A8 and A10 that can be used for each of the aspherical mirror surfaces in example 1 are given in Table 2 below.

TABLE 2

Fig. 3A shows an on-axis chromatic aberration curve of the optical system of embodiment 1, which indicates the focus deviation of light rays of different wavelengths after passing through the lens. Fig. 3B shows an astigmatism curve of the optical system of embodiment 1, which represents meridional image plane curvature and sagittal image plane curvature. Fig. 3C shows a distortion curve of the optical system of embodiment 1, which represents distortion magnitude values corresponding to different half angles of view. As can be seen from fig. 3A to 3C, the optical system of embodiment 1 can achieve good imaging quality.

Example 2

An optical system according to embodiment 2 of the present application is described below with reference to fig. 4 to 5C. In this embodiment and the following embodiments, descriptions of portions similar to embodiment 1 will be omitted for brevity. Fig. 4 shows a schematic structural view of an optical system according to embodiment 2 of the present application.

As shown in fig. 4, the optical system sequentially includes, from a human eye side to a screen side: a stop STO, a first lens E1, a second lens E2, a reflective polarizing element RP, a quarter wave plate QWP, a third lens E3, a partially reflective layer BS, and a display screen E4.

The first lens E1 has negative focal power, and the side surface near the human eye is a convex surface and the side surface near the screen is a concave surface. The second lens E2 has positive focal power, and the side surface near the human eye is a convex surface and the side surface near the screen is a plane. The third lens E3 has positive power, and has a convex near-eye side and a convex near-screen side. The reflective polarizer RP is attached to the near-screen side of the second lens E2, and the quarter-wave plate QWP is attached to the near-screen side of the reflective polarizer RP. The partially reflecting layer BS is attached to the near-screen side of the third lens E3.

In this example, the effective focal length f1 of the first lens is-732.57 mm, the effective focal length f2 of the second lens is 209.72mm, the effective focal length f3 of the third lens is 158.04mm, and the maximum half field angle Semi-FOV of the optical system is 53.0 °.

Table 3 shows basic parameters of the optical system of example 2, in which the unit of radius of curvature and thickness are both millimeters (mm). The image light from the display screen E4 passes through the respective components in the order of serial number 16 to serial number 1 and is finally projected into a target object in space such as human eyes. Table 4 shows the higher order coefficients that can be used for each of the aspherical mirror surfaces in example 2, wherein each of the aspherical surface types can be defined by the formula (1) given in example 1 above.

TABLE 3 Table 3

TABLE 4 Table 4

Fig. 5A shows an on-axis chromatic aberration curve of the optical system of embodiment 2, which represents the focus deviation of light rays of different wavelengths after passing through the lens. Fig. 5B shows an astigmatism curve of the optical system of embodiment 2, which represents meridional image plane curvature and sagittal image plane curvature. Fig. 5C shows a distortion curve of the optical system of embodiment 2, which represents distortion magnitude values corresponding to different half angles of view. As can be seen from fig. 5A to 5C, the optical system according to embodiment 2 can achieve good imaging quality.

Example 3

An optical system according to embodiment 3 of the present application is described below with reference to fig. 6 to 7C. Fig. 6 shows a schematic structural diagram of an optical system according to embodiment 3 of the present application.

As shown in fig. 6, the optical system sequentially includes, from a human eye side to a screen side: a stop STO, a first lens E1, a second lens E2, a reflective polarizing element RP, a quarter wave plate QWP, a third lens E3, a partially reflective layer BS, and a display screen E4.

In this example, the effective focal length f1 of the first lens is-1077.83 mm, the effective focal length f2 of the second lens is 229.74mm, the effective focal length f3 of the third lens is 147.17mm, and the maximum half field angle Semi-FOV of the optical system is 53.0 °.

Table 5 shows basic parameters of the optical system of example 3, in which the unit of radius of curvature and thickness are both millimeters (mm). The image light from the display screen E4 passes through the respective components in the order of serial number 16 to serial number 1 and is finally projected into a target object in space such as human eyes. Table 6 shows the higher order coefficients that can be used for each of the aspherical mirror surfaces in example 3, wherein each of the aspherical surface types can be defined by the formula (1) given in example 1 above.

TABLE 5

TABLE 6

Fig. 7A shows an on-axis chromatic aberration curve of the optical system of embodiment 3, which indicates the focus deviation of light rays of different wavelengths after passing through the lens. Fig. 7B shows an astigmatism curve of the optical system of embodiment 3, which represents meridional image plane curvature and sagittal image plane curvature. Fig. 7C shows a distortion curve of the optical system of example 3, which represents distortion magnitude values corresponding to different half angles of view. As can be seen from fig. 7A to 7C, the optical system provided in embodiment 3 can achieve good imaging quality.

Example 4

An optical system according to embodiment 4 of the present application is described below with reference to fig. 8 to 9C. Fig. 8 shows a schematic structural diagram of an optical system according to embodiment 4 of the present application.

As shown in fig. 8, the optical system sequentially includes, from the human eye side to the screen side: a stop STO, a first lens E1, a second lens E2, a reflective polarizing element RP, a quarter wave plate QWP, a third lens E3, a partially reflective layer BS, and a display screen E4.

In this example, the effective focal length f1 of the first lens is 77.45mm, the effective focal length f2 of the second lens is-157.47 mm, the effective focal length f3 of the third lens is 210.41mm, and the maximum half field angle Semi-FOV of the optical system is 53.0 °.

Table 7 shows basic parameters of the optical system of example 4, in which the unit of radius of curvature and thickness are both millimeters (mm). The image light from the display screen E4 passes through the respective components in the order of serial number 16 to serial number 1 and is finally projected into a target object in space such as human eyes. Table 8 shows the higher order coefficients that can be used for each of the aspherical mirror surfaces in example 4, wherein each of the aspherical surface types can be defined by the formula (1) given in example 1 above.

TABLE 7

TABLE 8

Fig. 9A shows an on-axis chromatic aberration curve of the optical system of embodiment 4, which indicates the focus deviation of light rays of different wavelengths after passing through the lens. Fig. 9B shows an astigmatism curve of the optical system of embodiment 4, which represents meridional image plane curvature and sagittal image plane curvature. Fig. 9C shows a distortion curve of the optical system of example 4, which represents distortion magnitude values corresponding to different half angles of view. As can be seen from fig. 9A to 9C, the optical system provided in embodiment 4 can achieve good imaging quality.

Example 5

An optical system according to embodiment 5 of the present application is described below with reference to fig. 10 to 11C. Fig. 10 shows a schematic structural diagram of an optical system according to embodiment 5 of the present application.

As shown in fig. 10, the optical system sequentially includes, from the human eye side to the screen side: a stop STO, a first lens E1, a second lens E2, a reflective polarizing element RP, a quarter wave plate QWP, a third lens E3, a partially reflective layer BS, and a display screen E4.

In this example, the effective focal length f1 of the first lens is-1166.01 mm, the effective focal length f2 of the second lens is 223.01mm, the effective focal length f3 of the third lens is 146.73mm, and the maximum half field angle Semi-FOV of the optical system is 53.0 °.

Table 9 shows basic parameters of the optical system of example 5, in which the unit of radius of curvature and thickness are both millimeters (mm). The image light from the display screen E4 passes through the respective components in the order of serial number 16 to serial number 1 and is finally projected into a target object in space such as human eyes. Table 10 shows the higher order coefficients that can be used for each of the aspherical mirror surfaces in example 5, wherein each of the aspherical surface types can be defined by the formula (1) given in example 1 above.

TABLE 9

Table 10

Fig. 11A shows an on-axis chromatic aberration curve of the optical system of embodiment 5, which indicates the focus deviation of light rays of different wavelengths after passing through the lens. Fig. 11B shows an astigmatism curve of the optical system of embodiment 5, which represents meridional image plane curvature and sagittal image plane curvature. Fig. 11C shows a distortion curve of the optical system of example 5, which represents distortion magnitude values corresponding to different half angles of view. As can be seen from fig. 11A to 11C, the optical system provided in embodiment 5 can achieve good imaging quality.

Example 6

An optical system according to embodiment 6 of the present application is described below with reference to fig. 12 to 13C. Fig. 12 shows a schematic structural diagram of an optical system according to embodiment 6 of the present application.

As shown in fig. 12, the optical system sequentially includes, from the human eye side to the screen side: a stop STO, a first lens E1, a second lens E2, a reflective polarizing element RP, a quarter wave plate QWP, a third lens E3, a partially reflective layer BS, and a display screen E4.

In this example, the effective focal length f1 of the first lens is-603.37 mm, the effective focal length f2 of the second lens is 210.55mm, the effective focal length f3 of the third lens is 156.54mm, and the maximum half field angle Semi-FOV of the optical system is 53.0 °.

Table 11 shows basic parameters of the optical system of example 6, in which the unit of the radius of curvature and the thickness are both millimeters (mm). The image light from the display screen E4 passes through the respective components in the order of serial number 16 to serial number 1 and is finally projected into a target object in space such as human eyes. Table 12 shows the higher order coefficients that can be used for each of the aspherical mirror surfaces in example 6, wherein each of the aspherical surface types can be defined by the formula (1) given in example 1 above.

TABLE 11

Table 12

Fig. 13A shows an on-axis chromatic aberration curve of the optical system of embodiment 6, which indicates the focus deviation of light rays of different wavelengths after passing through the lens. Fig. 13B shows an astigmatism curve of the optical system of example 6, which represents meridional image plane curvature and sagittal image plane curvature. Fig. 13C shows a distortion curve of the optical system of example 6, which represents distortion magnitude values corresponding to different half angles of view. As can be seen from fig. 13A to 13C, the optical system provided in embodiment 6 can achieve good imaging quality.

In summary, the relationships shown in the optical system table 13 of examples 1 to 6.

Conditional\embodiment	1	2	3	4	5	6
							f1×N1/R2	-2.81	-8.79	-11.18	-2.83	-6.98	-5.57
R1/CT1+R1/V1	55.10	111.40	114.72	58.22	220.17	184.24
							f2×N2/R3	2.47	2.98	2.83	2.47	2.83	2.96
CT1/T12	15.58	13.56	8.19	15.69	6.01	19.48
							f3×N3/R6	-2.34	-1.93	-1.87	-2.32	-1.84	-1.89
\|R5/R6\|+CT3/T23	4.34	4.23	4.46	4.25	4.11	4.22
							3×(dqwp+T23+CT3)/TD	1.84	2.10	2.06	1.84	2.08	2.14
CT3/(CT1+CT2+drp+dqwp)	0.86	1.53	1.50	0.87	1.51	1.62
							f3×tan(Semi-FOV)/R6	-2.10	-1.70	-1.61	-2.08	-1.58	-1.67
\|R1/R3\|+V2/V1	4.82	4.37	4.60	4.95	6.50	5.44
							\|f2\|/(Vrp+Vqwp)	1.35	1.84	2.02	1.38	1.96	1.85
f1×N1/R2	-1.88	-5.26	-6.70	-1.90	-4.18	-3.34
							R1/CT1+R1/V1	55.10	111.40	114.72	58.22	220.17	184.24
f2×N2/R3	2.47	2.98	2.83	2.47	2.83	2.96
							CT1/T12	15.58	13.56	8.19	15.69	6.01	19.48
f3×N3/R6	-2.34	-1.93	-1.87	-2.32	-1.84	-1.89
							\|R5/R6\|+CT3/T23	4.34	4.23	4.46	4.57	4.11	4.22

TABLE 13

The present application also provides an optical device 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. The optical apparatus 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 should be understood by those skilled in the art that the scope of protection referred to in this application is not limited to the specific combination of the above technical features, but also encompasses other technical solutions formed by any combination of the above technical features or their equivalents without departing from the spirit of the application. 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, in order from a first side to a second side along an optical axis: a first lens, a second lens, a reflective polarizing element, a quarter wave plate and a third lens, wherein,

the second side surface of the second lens is a plane;

the second side surface of the third lens is provided with a partial reflecting layer; and

the curvature radius R1 of the first side surface of the first lens, the center thickness CT1 of the first lens on the optical axis, and the abbe number V1 of the first lens satisfy: 55.0 < R1/CT1+R1/V1 < 221.

2. The optical system of claim 1, wherein the effective focal length f1 of the first lens, the refractive index N1 of the first lens, and the radius of curvature R2 of the second side of the first lens satisfy:

-12.0＜f1×N1/R2＜-2.0。

3. the optical system of claim 1, wherein the effective focal length f2 of the second lens, the refractive index N2 of the second lens, and the radius of curvature R3 of the first side of the second lens satisfy:

2.0＜f2×N2/R3＜3.0。

4. the optical system according to claim 1, wherein a center thickness CT1 of the first lens on the optical axis, an air interval T12 of the first lens and the second lens on the optical axis satisfy:

6.0＜CT1/T12＜20.0。

5. the optical system of claim 1, wherein the effective focal length f3 of the third lens, the refractive index N3 of the third lens, and the radius of curvature R6 of the second side of the third lens satisfy:

-2.5＜f3×N3/R6＜-1.5。

6. the optical system according to claim 1, wherein a radius of curvature R5 of the first side surface of the third lens, a radius of curvature R6 of the second side surface of the third lens, a center thickness CT3 of the third lens on the optical axis, and an air gap T23 of the second lens and the third lens on the optical axis satisfy:

4.0＜|R5/R6|+CT3/T23＜5.0。

7. the optical system according to claim 1, wherein a center thickness dqwp of the quarter wave plate on the optical axis, an air interval T23 of the second lens and the third lens on the optical axis, a center thickness CT3 of the third lens on the optical axis, a distance TD from a first side surface of the first lens to a second side surface of the third lens on the optical axis satisfy: 1.5 < 3× (dqwp+T23+CT3)/TD < 2.5.

8. The optical system according to claim 1, wherein a center thickness CT1 of the first lens on the optical axis, a center thickness CT2 of the second lens on the optical axis, a center thickness CT3 of the third lens on the optical axis, a center thickness dqwp of the quarter-wave plate on the optical axis, and a center thickness drp of the reflective polarizing element on the optical axis satisfy: 0.5 < CT 3/(CT1+CT2+drp+dqwp) < 2.0.

9. The optical system according to any one of claims 1 to 8, wherein the effective focal length f3 of the third lens, the maximum half field angle Semi-FOV of the optical system, and the radius of curvature R6 of the second side of the third lens satisfy: -2.5 < f3×tan (Semi-FOV)/R6 < -1.5.

10. An optical device comprising an optical system according to at least one of claims 1 to 9.