CN219737881U - Optical system and optical apparatus including the same - Google Patents

Abstract

The utility model discloses an optical system and an optical apparatus including the same, the optical system includes: the element group sequentially comprises from a first side to a second side along the optical axis: the light source device comprises a first element group, a second element group and a third element group, wherein the first element group comprises a light filter and a reflective polarizing element; the second element group has positive optical power and comprises a quarter wave plate and a first lens; the third element group comprises a second lens, and the second lens has positive optical power or negative optical power; at least one spacing element, including a first spacing element, disposed between the second element group and the third element group and abutting against the second side surface of the first lens; a lens barrel for accommodating the lens group and at least one spacer element; the effective focal length FG2 of the second element group, the center thickness CTF of the optical filter on the optical axis, the center thickness CTQ of the quarter wave plate on the optical axis, the center thickness CT1 of the first lens on the optical axis, and the maximum thickness CP1 of the first spacer element along the optical axis direction satisfy: 1.5< FG2/(CTF+CTQ+CT1+CP1) <2.9.

Description

Optical system and optical apparatus including the same

Technical Field

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

Background

With the development of science and technology, the bottom commonality rapid maturity of near-to-eye display, perception interaction, rendering processing and the like in VR/AR is gradually improved, and a stepped immersion feeling is brought to a user. But is limited by the film pasting technology at present, the degree of freedom of a curved surface in an optical system is low, and the performance improvement space of a conventional structural system is not large. The refraction and reflection type optical structure in the VR scheme can not only greatly reduce the volume of equipment, but also improve the use feeling, and is expected by consumers more and more. The optical path of the catadioptric optical system is complex, and the performance of the optical system is different due to the difference of the lens shape and the lens assembly position, so that designing a catadioptric optical system with good imaging quality is one of the hot spots of current research.

Disclosure of Invention

The present utility model provides an optical system including: the element group sequentially comprises from a first side to a second side along the optical axis: the light source device comprises a first element group, a second element group and a third element group, wherein the first element group comprises a light filter and a reflective polarizing element; the second element group has positive optical power and comprises a quarter wave plate and a first lens; the third element group comprises a second lens, and the second lens has positive optical power or negative optical power; at least one spacing element, including a first spacing element, disposed between the second element group and the third element group and abutting against the second side surface of the first lens; a lens barrel for accommodating the lens group and at least one spacer element; the effective focal length FG2 of the second element group, the center thickness CTF of the optical filter on the optical axis, the center thickness CTQ of the quarter wave plate on the optical axis, the center thickness CT1 of the first lens on the optical axis, and the maximum thickness CP1 of the first spacer element along the optical axis direction satisfy: 1.5< FG2/(CTF+CTQ+CT1+CP1) <2.9.

In one embodiment, the radius of curvature R1 of the first side surface of the first lens, the inner diameter D0s of the first side end surface of the lens barrel, and the outer diameter D0s of the first side end surface of the lens barrel satisfy: 0.8< R1/(d0s+d0s) <1.4.

In one embodiment, the radius of curvature R2 of the second side of the first lens and the inner diameter d1s of the first side of the first spacer element satisfy: -2< R2/d1s < -1.1.

In one embodiment, the at least one spacer element further comprises a first auxiliary spacer element disposed between the first spacer element and the second lens and abutting the second side of the first spacer element; and an air interval T12 between the first lens and the second lens on the optical axis, a maximum thickness CP1 of the first spacing element in the optical axis direction, and a maximum thickness CP1b of the first auxiliary spacing element in the optical axis direction satisfy: 0.3< T12/(CP1+CP1b) <1.1.

In one embodiment, the radius of curvature R3 of the first side of the second lens, the inner diameter D1bm of the second side of the first auxiliary spacer element and the outer diameter D1bm of the second side of the first auxiliary spacer element satisfy: -2.2< R3/(d1bm+D1bm) < -0.7.

In one embodiment, the inner diameter d0s of the first side end surface of the lens barrel, the inner diameter d0m of the second side end surface of the lens barrel, and the entrance pupil diameter EPD of the optical system satisfy: 1.2< (d 0m-d0 s)/EPD <2.3.

In one embodiment, the spacing distance EP01 between the first side end surface of the lens barrel and the first side surface of the first spacing element in the optical axis direction, the central thickness CTR of the reflective polarizing element on the optical axis, the central thickness CTQ of the quarter-wave plate on the optical axis, and the central thickness CT1 of the first lens on the optical axis satisfy: 0.7< ep 01/(ctr+ctq+ct1) <1.1.

In one embodiment, the effective focal length f of the optical system, the inner diameter D1m of the second side of the first spacer element and the outer diameter D1m of the second side of the first spacer element satisfy: 2.3< f/(D1 m-D1 m) <4.2.

In one embodiment, the distance TD on the optical axis from the first side of the first lens to the second side of the second lens, the inner diameter D1bs of the first side of the first auxiliary spacer element and the outer diameter D1bs of the first side of the first auxiliary spacer element satisfy: 1.4< TD/(D1 bs-D1 bs) <4.0.

In one embodiment, the outer diameter D1s of the first side of the first spacer element, the central thickness CT1 of the first lens on the optical axis and the central thickness CT2 of the second lens on the optical axis satisfy: 4.2< d1 s/(CT 1+ CT 2) <6.5.

In one embodiment, the outer diameter D0m of the second side end surface of the lens barrel and the effective focal length FG2 of the second element group satisfy: 2.5< D0m/FG2<2.9.

In one embodiment, the maximum thickness CP1 of the first spacer element in the optical axis direction, the center thickness CTF of the optical filter on the optical axis, the center thickness CTR of the reflective polarizing element on the optical axis, and the center thickness CTQ of the quarter-wave plate on the optical axis satisfy: 0< CP1/(CTF+CTR+CTQ) <1.2.

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

The optical system provided by the utility model comprises three element groups, wherein the first element group comprises an optical filter and a reflective polarizing element, the second element group comprises a quarter wave plate and a first lens, and the third element group comprises a second lens; through the reasonable control of the relation between each element group and the interval element, the incidence angle of light on the optical filter can be balanced well, the problem of light leakage between the second element group and the first interval element when incidence is large in angle is avoided, and the imaging quality of the optical system is improved.

Drawings

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

FIG. 1 shows a schematic diagram of a structural layout and some parameters of an optical system according to the present utility model;

fig. 2A to 2C show schematic structural views of an optical system according to embodiment 1 of the present utility model;

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

fig. 4A to 4C show schematic structural views of an optical system according to embodiment 2 of the present utility model;

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 utility model, respectively;

fig. 6A to 6C show schematic structural diagrams of an optical system according to embodiment 3 of the present utility model;

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

Detailed Description

For a better understanding of the utility model, various aspects of the utility model will be described in more detail with reference to the accompanying drawings. It should be understood that the detailed description is merely illustrative of exemplary embodiments of the utility model and is not intended to limit the scope of the utility model 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 utility model.

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 utility model, use of "may" means "one or more embodiments of the utility model. 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 utility model 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, without conflict, the embodiments of the present utility model and features of the embodiments may be combined with each other. The utility model will be described in detail below with reference to the drawings in connection with embodiments.

The features, principles and other aspects of the present utility model will be described in detail below with reference to the attached drawings and in connection with the following embodiments.

Fig. 1 shows a schematic diagram of the structural layout and some parameters of an optical system according to the utility model. As shown in fig. 1, CP1 represents the maximum thickness of the first spacer element in the optical axis direction, L represents the distance from the first side end surface of the barrel to the second side end surface of the barrel in the optical axis direction, EP01 represents the distance between the first side end surface of the barrel and the first side surface of the first spacer element in the optical axis direction, CP1b represents the maximum thickness of the first auxiliary spacer element in the optical axis direction, D0s represents the outer diameter of the first side end surface of the barrel, D1s represents the outer diameter of the first side surface of the first spacer element, D0s represents the inner diameter of the first side end surface of the barrel, D1bs represents the inner diameter of the first side surface of the first auxiliary spacer element, D1m represents the inner diameter of the second side surface of the first spacer element, D1bm represents the outer diameter of the second side surface of the first auxiliary spacer element, D1m represents the outer diameter of the second side surface of the first spacer element, D0s represents the outer diameter of the second side surface of the barrel, D0m represents the outer diameter of the second side surface of the barrel.

The optical system according to an exemplary embodiment of the present utility model may include a lens barrel, and an element group and at least one spacer element disposed within the lens barrel, the element group including a first element group, a second element group, and a third element group in order from a first side to a second side along an optical axis, wherein the first element group includes an optical filter and a reflective polarizing element; the second element group has positive optical power and comprises a quarter wave plate and a first lens; the third element group includes a second lens, and the second lens has positive or negative optical power. The at least one spacing element comprises a first spacing element which is arranged between the second element group and the third element group and is abutted against the second side surface of the first lens. The effective focal length FG2 of the second element group, the center thickness CTF of the optical filter on the optical axis, the center thickness CTQ of the quarter wave plate on the optical axis, the center thickness CT1 of the first lens on the optical axis, and the maximum thickness CP1 of the first spacer element along the optical axis direction satisfy: 1.5< FG2/(CTF+CTQ+CT1+CP1) <2.9. Through the arrangement, the relation between each element group and the interval element is reasonably controlled, the incidence angle of light on the optical filter can be well balanced, the problem of light leakage between the second element group and the first interval element when the incidence angle is large is avoided, and the imaging quality of the optical system is improved.

In an exemplary embodiment, the first and second sides of the filter are planar, which facilitates attachment of the reflective polarizing element. Illustratively, the reflective polarizing element is attached to the second side of the optical filter, and the quarter-wave plate is attached to the first side of the first lens.

In an exemplary embodiment, the optical system further includes a partially reflective layer, which may be attached to the second side of the first lens, the first side of the second lens, or the second side. The partially reflective layer may have a better average light reflectivity, where average light reflectivity may refer to an average of the reflectivity of the partially reflective layer for light of different wavelengths. 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, the optical system of the present utility model may satisfy: 0.8< R1/(d0s+d0s) <1.4, wherein R1 is the radius of curvature of the first side surface of the first lens, D0s is the inner diameter of the first side end surface of the lens barrel, and D0s is the outer diameter of the first side end surface of the lens barrel. Satisfies 0.8< R1/(d0s+D0s) <1.4, satisfies the structural support of the lens by controlling the curvature radius of the first side surface of the first lens and the inner and outer diameter values of the first side end surface of the lens barrel, and is beneficial to lens molding.

In an exemplary embodiment, the optical system of the present utility model may satisfy: -2< R2/d1s < -1.1, wherein R2 is the radius of curvature of the second side of the first lens and d1s is the inner diameter of the first side of the first spacer element. Satisfying-2 < R2/d1s < -1.1, the optical power value of the first lens can be limited by controlling the ratio of the curvature radius of the second side surface of the first lens to the inner diameter of the first side surface of the first interval element, which is beneficial to lens molding and the assembly stability of the first interval element.

In an exemplary embodiment, the at least one spacer element of the optical system of the present utility model further comprises a first auxiliary spacer element, which is disposed between the first spacer element and the second lens and abuts against the second side of the first spacer element.

In an exemplary embodiment, the optical system of the present utility model may satisfy: 0.3< T12/(CP1+CP1b) <1.1, wherein T12 is the air space between the first lens and the second lens on the optical axis, CP1 is the maximum thickness of the first spacer element along the optical axis direction, and CP1b is the maximum thickness of the first auxiliary spacer element along the optical axis direction. Satisfying 0.3< T12/(CP1+CP1b) <1.1, restricting the position of the first auxiliary spacing element, controlling the maximum thickness of the first spacing element, and indirectly controlling the height of the lens barrel. By reasonably distributing the air space between the first lens and the second lens on the optical axis, the assembly stability of the first lens and the second lens can be improved.

In an exemplary embodiment, the optical system of the present utility model may satisfy: -2.2< R3/(d1bm+d1bm) < -0.7, where R3 is the radius of curvature of the first side of the second lens, D1bm is the inner diameter of the second side of the first auxiliary spacer element, and D1bm is the outer diameter of the second side of the first auxiliary spacer element. Satisfying-2.2 < R3/(d1bm+D1bm) < -0.7, limiting the curvature radius of the first side surface of the second lens, and being beneficial to reducing the sensitivity of the second lens, thereby improving the assembly yield; secondly, the support of the structure to the lens can be satisfied by controlling the inner diameter and the outer diameter of the second side surface of the first auxiliary spacer element, while ensuring the workability of the spacer element.

In an exemplary embodiment, the optical system of the present utility model may satisfy: 1.2< (d 0m-d0 s)/EPD <2.3, wherein d0s is the inner diameter of the first side end surface of the lens barrel, d0m is the inner diameter of the second side end surface of the lens barrel, and EPD is the entrance pupil diameter of the optical system. Satisfying 1.2< (d 0m-d0 s)/EPD <2.3, and by controlling the entrance pupil diameter of the optical system, the optical system satisfies ergonomics, thereby being beneficial to the immersion experience of the VR lens; meanwhile, the inner diameters of the first side end face and the second side end face of the lens barrel are controlled, the light inlet quantity can be effectively controlled, the light rays are utilized to participate in imaging more effectively, the reflection route of the redundant light rays can be better changed, the generation of stray light is reduced, and the imaging definition is improved.

In an exemplary embodiment, the optical system of the present utility model may satisfy: 0.7< EP 01/(ctr+ctq+ct1) <1.1, wherein EP01 is a distance between the first side surface of the barrel and the first side surface of the first spacer element in the optical axis direction, CTR is a center thickness of the reflective polarizing element on the optical axis, CTQ is a center thickness of the quarter-wave plate on the optical axis, and CT1 is a center thickness of the first lens on the optical axis. Satisfying 0.7< ep 01/(ctr+ctq+ct1) <1.1, being advantageous in balancing the workability of the first spacing element and the compactness required for the overall structure, while guaranteeing the supporting performance of the first spacing element; and meanwhile, the thicknesses of the reflective polarizing element and the quarter-wave plate are limited, so that the structural support of the reflective polarizing element and the quarter-wave plate is ensured without interfering with the assembly of the first lens.

In an exemplary embodiment, the optical system of the present utility model may satisfy: 2.3< f/(D1 m-D1 m) <4.2, where f is the effective focal length of the optical system, D1m is the inner diameter of the second side of the first spacer element, and D1m is the outer diameter of the second side of the first spacer element. The method satisfies 2.3< f/(D1 m-D1 m) <4.2, and the overall size of the device can be controlled under the condition of ensuring the performance of the optical system by controlling the effective focal length of the optical system and the inner diameter and the outer diameter of the second side surface of the first interval element, so that the device satisfies ergonomics and is favorable for the immersion experience of the VR lens.

In an exemplary embodiment, the optical system of the present utility model may satisfy: 1.4< TD/(D1 bs-D1 bs) <4.0, where TD is the distance on the optical axis between the first side of the first lens and the second side of the second lens, D1bs is the inner diameter of the first side of the first auxiliary spacer element, and D1bs is the outer diameter of the first side of the first auxiliary spacer element. Satisfying 1.4< TD/(D1 bs-D1 bs) <4.0, indirectly controlling the maximum angle of view of the optical system by controlling the on-axis distance from the first side surface of the first lens to the second side surface of the second lens, and improving the wearing experience of consumers by increasing the angle of view; by controlling the inner and outer diameters of the first side of the first auxiliary spacer element, the imaging quality of the control system is facilitated, thereby improving the immersion experience of the device.

In an exemplary embodiment, the optical system of the present utility model may satisfy: 4.2< D1 s/(CT 1+ CT 2) <6.5, wherein D1s is the outer diameter of the first side of the first spacer element, CT1 is the center thickness of the first lens on the optical axis, and CT2 is the center thickness of the second lens on the optical axis. Satisfying 4.2< d1 s/(CT 1+ CT 2) <6.5, by controlling the center thicknesses of the first lens and the second lens, and the outer diameter of the first side surface of the first spacer element, the thickness ratio of the first lens and the second lens can be ensured, thereby facilitating the molding of the first lens and the second lens.

In an exemplary embodiment, the optical system of the present utility model may satisfy: 2.5< D0m/FG2<2.9, wherein D0m is the outer diameter of the second side end face of the barrel, FG2 is the effective focal length of the second element group. Satisfies 2.5< D0m/FG2<2.9, and is beneficial to controlling the lens shape of the first lens by controlling the effective focal length of the second element group and the outer diameter of the second side end face of the lens barrel, thereby ensuring the molding of the first lens.

In an exemplary embodiment, the optical system of the present utility model may satisfy: 0< CP1/(CTF+CTR+CTQ) <1.2, wherein CP1 is the maximum thickness of the first spacer element in the direction of the optical axis, CTF is the center thickness of the optical filter on the optical axis, CTR is the center thickness of the reflective polarizing element on the optical axis, and CTQ is the center thickness of the quarter-wave plate on the optical axis. Satisfies 0< CP1/(CTF+CTR+CTQ) <1.2, and by controlling the maximum thickness of the first interval element along the optical axis direction and the central thickness of the optical filter, the reflective polarizing element and the quarter-wave plate on the optical axis, on one hand, the optical power of the system is reasonably distributed, and on the other hand, the central thicknesses of the quarter-wave plate and the reflective polarizing element are controlled, thereby being beneficial to the curved surface attachment of the quarter-wave plate and the plane attachment of the reflective polarizing element.

According to some embodiments of the utility model, the optical system according to the utility model is a low-volume optical system of high definition imaging quality, which optical system according to an exemplary embodiment of the utility model may be suitable for VR devices in application. 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. By arranging the spacing elements between the lenses, the lens processing and forming performance can be facilitated, the sensitivity of the lenses can be reduced, the assembly yield can be improved, and the miniaturization target of the head-mounted equipment can be met on the premise of ensuring the performance of the optical system.

In an exemplary embodiment, the optical system provided by the present utility model 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.

In an exemplary embodiment, the optical system according to the present utility model further includes a diaphragm disposed on the human eye side and a display screen disposed on the screen side. The eyes of the user can watch the image projected by the display screen at the position of the aperture, namely, the image light on the display screen is finally projected to the eyes of the user after being refracted and reflected for many times by the second lens, the first lens, the quarter wave plate, the reflection polarizing element, the optical filter and the like.

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 utility model is described below with reference to fig. 2A to 3C. Fig. 2A to 2C show schematic structural views of an optical system according to three embodiments of example 1 of the present utility model, respectively.

As shown in fig. 2A to 2C, the optical system sequentially includes, from a human eye side to a screen side: a stop STO (not shown), a filter IR, a reflective polarizing element RP, a quarter wave plate QWP, a first lens E1, a partially reflective layer BS (not shown), a second lens E2, and a display screen IMG. Wherein the filter IR and the reflective polarizing element RP belong to a first element group, the quarter-wave plate QWP and the first lens E1 belong to a second element group, and the second lens E2 belongs to a third element group. The near-human eye side surface and the near-screen side surface of the optical filter IR are both planes, the reflective polarizing element RP is attached to the near-screen side surface of the optical filter IR, and the quarter wave plate QWP is attached to the near-human eye side surface of the first lens E1. A partially reflective layer BS (not shown) is attached to the human eye-proximal side of the second lens E2.

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

In this example, the effective focal length FG2 of the second element group is 28.60mm, the effective focal length f of the optical system is 29.35mm, the entrance pupil diameter EPD of the optical system is 5.00mm, the distance TD between the first side surface of the first lens and the second side surface of the second lens on the optical axis is 17.94mm, the center thickness CTF of the filter on the optical axis is 0.80mm, the center thickness CTR of the reflective polarizing element on the optical axis is 0.20mm, and the center thickness CTQ of the quarter-wave plate on the optical axis is 0.20mm.

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). Image light from the display screen IMG passes through the respective components in the order of serial number 18 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-screen side of the first lens E1 is an aspherical surface, and the surface shape x of the 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; ai is the correction coefficient of the aspherical i-th order. The higher order coefficients A4, A6, A8, A10, A12, A14, A16, A18 and A20 that can be used for the aspherical mirror surfaces in example 1 are given in Table 2 below.

Part name	First lens E1
		Surface of the body	Near screen side
A4	1.1746E-06
		A6	-1.9180E-11
A8	1.9663E-13
		A10	-1.6585E-16
A12	5.1303E-20
		A14	0.0000E+00
A16	0.0000E+00
		A18	0.0000E+00
A20	0.0000E+00

TABLE 2

As shown in fig. 2A to 2C, the optical system may include two spacing elements, a first spacing element P1 and a first auxiliary spacing element P1b, respectively, between the first lens E1 and the second lens E2, respectively. The first spacer element P1 is disposed between the first lens element E1 and the second lens element E2 and abuts against the near-screen side surface of the first lens element E1, and the first auxiliary spacer element P1b is disposed between the first spacer element P1 and the second lens element E2 and abuts against the near-screen side surface of the first spacer element P1. As shown in fig. 2A to 2C, the optical system may further include a lens barrel P0 accommodating the reflective polarizing element RP, the quarter-wave plate QWP, the first lens E1, the second lens E2, the first spacer P1, and the first auxiliary spacer P1b.

Table 3 shows the structure parameter tables of the respective spacer elements in three embodiments in the optical system of example 1, wherein each structure parameter in table 3 has a unit of millimeter (mm).

TABLE 3 Table 3

It should be understood that in this example, the structures and parameters of each spacer element are merely exemplified for three embodiments, and the specific structures and actual parameters of each spacer element are not explicitly defined. The specific structure and actual parameters of each spacer may be set in any suitable manner in actual production.

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 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 utility model is described below with reference to fig. 4A to 5C. In this embodiment and the following embodiments, descriptions of portions similar to embodiment 1 will be omitted for brevity. Fig. 4A to 4C show schematic structural views of an optical system according to three embodiments of example 2 of the present utility model, respectively.

As shown in fig. 4A to 4C, the optical system sequentially includes, from the human eye side to the screen side: a stop STO (not shown), a filter IR, a reflective polarizing element RP, a quarter wave plate QWP, a first lens E1, a second lens E2, a partially reflective layer BS (not shown), and a display screen IMG. Wherein the filter IR and the reflective polarizing element RP belong to a first element group, the quarter-wave plate QWP and the first lens E1 belong to a second element group, and the second lens E2 belongs to a third element group. The near-human eye side surface and the near-screen side surface of the optical filter IR are both planes, the reflective polarizing element RP is attached to the near-screen side surface of the optical filter IR, and the quarter wave plate QWP is attached to the near-human eye side surface of the first lens E1. A partially reflective layer BS (not shown) is attached to the near-screen side of the second lens E2.

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

In this example, the effective focal length FG2 of the second element group is 29.28mm, the effective focal length f of the optical system is 29.50mm, the entrance pupil diameter EPD of the optical system is 5.00mm, the distance TD on the optical axis from the first side surface of the first lens to the second side surface of the second lens is 18.74mm, the center thickness CTF of the filter on the optical axis is 0.80mm, the center thickness CTR of the reflective polarizing element on the optical axis is 0.20mm, and the center thickness CTQ of the quarter-wave plate on the optical axis is 0.50mm.

Table 4 shows basic parameters of the optical system of example 2, in which the unit of radius of curvature and thickness are both millimeters (mm). Image light from the display screen IMG passes through the respective components in the order of serial number 20 to serial number 1 and is finally projected into a target object in space such as human eyes. Table 5 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.

Sequence number	Surface type	Radius of curvature	Thickness of (L)	Refractive index	Abbe number	Refraction/reflection
							0	Spherical surface	Infinity is provided	Infinity is provided			Refraction by refraction
1	Spherical surface	Infinity is provided	15.0000			Refraction by refraction
							2	Spherical surface	Infinity is provided	0.8000	1.52	64.17	Refraction by refraction
3	Spherical surface	Infinity is provided	0.2000	1.52	64.17	Refraction by refraction
							4	Spherical surface	Infinity is provided	1.4998			Refraction by refraction
5	Spherical surface	175.0000	0.5000	1.48	60.00	Refraction by refraction
							6	Spherical surface	175.0000	15.6448	1.48	60.00	Refraction by refraction
7	Aspherical surface	-82.4212	1.0000			Refraction by refraction
							8	Spherical surface	-113.1580	2.0956	1.67	19.00	Refraction by refraction
9	Spherical surface	-113.1580	-2.0956	1.67	19.00	Reflection of
							10	Spherical surface	-113.1580	-1.0000			Refraction by refraction
11	Aspherical surface	-82.4212	-15.6448	1.48	60.00	Refraction by refraction
							12	Spherical surface	175.0000	-0.5000	1.48	60.00	Refraction by refraction
13	Spherical surface	175.0000	-1.4998			Refraction by refraction
							14	Spherical surface	Infinity is provided	1.4998			Reflection of
15	Spherical surface	175.0000	0.5000	1.48	60.00	Refraction by refraction
							16	Spherical surface	175.0000	15.6448	1.48	60.00	Refraction by refraction
17	Aspherical surface	-82.4212	1.0000			Refraction by refraction
							18	Spherical surface	-113.1580	2.0956	1.67	19.00	Refraction by refraction
19	Spherical surface	-113.1580	0.5532			Refraction by refraction
							20	Spherical surface	Infinity is provided	0.0000			Refraction by refraction

TABLE 4 Table 4

Part name	First lens E1
		Surface of the body	Near screen side
A4	6.4273E-07
		A6	1.2825E-10
A8	2.1014E-13
		A10	-1.1885E-16
A12	2.7918E-20
		A14	0.0000E+00
A16	0.0000E+00
		A18	0.0000E+00
A20	0.0000E+00

TABLE 5

As shown in fig. 4A to 4C, the optical system may include two spacing elements, a first spacing element P1 and a first auxiliary spacing element P1b, respectively, between the first lens E1 and the second lens E2, respectively. The first spacer element P1 is disposed between the first lens element E1 and the second lens element E2 and abuts against the near-screen side surface of the first lens element E1, and the first auxiliary spacer element P1b is disposed between the first spacer element P1 and the second lens element E2 and abuts against the near-screen side surface of the first spacer element P1. As shown in fig. 4A to 4C, the optical system may further include a lens barrel P0 accommodating the reflective polarizing element RP, the quarter-wave plate QWP, the first lens E1, the second lens E2, the first spacer P1, and the first auxiliary spacer P1b.

Table 6 shows the structure parameter tables of the respective spacer elements in three embodiments in the optical system of example 2, wherein each structure parameter in table 6 has a unit of millimeter (mm).

Structural parameters	Embodiment 1	Embodiment 2	Embodiment 3
				d1s	69.5768	69.5768	67.8961
d1m	69.2696	69.2696	67.8961
				D1s	76.9113	76.0113	76.5000
D1m	77.3379	76.3841	76.5000
				d1bs	67.9582	68.0582	69.0065
d1bm	67.9582	68.0582	68.6256
				D1bs	78.6000	77.7000	75.6151
D1bm	78.6000	77.7000	75.8379
				d0s	70.6000	70.9000	69.7000
d0m	81.8102	80.9102	80.3102
				D0s	77.6769	77.6769	76.6686
D0m	84.1800	83.2800	82.6800
				EP01	12.7016	12.7016	12.8066
CP1	1.7115	1.6485	0.1050
				CP1b	0.1050	0.0680	1.4015

TABLE 6

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 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 utility model is described below with reference to fig. 6A to 7C. Fig. 6A to 6C show schematic structural views of an optical system according to three embodiments of example 3 of the present utility model, respectively.

As shown in fig. 6A to 6C, the optical system sequentially includes, from the human eye side to the screen side: a stop STO (not shown), a filter IR, a reflective polarizing element RP, a quarter wave plate QWP, a first lens E1, a partially reflective layer BS (not shown), a second lens E2, and a display screen IMG. Wherein the filter IR and the reflective polarizing element RP belong to a first element group, the quarter-wave plate QWP and the first lens E1 belong to a second element group, and the second lens E2 belongs to a third element group. The near-human eye side surface and the near-screen side surface of the optical filter IR are both planes, the reflective polarizing element RP is attached to the near-screen side surface of the optical filter IR, and the quarter wave plate QWP is attached to the near-human eye side surface of the first lens E1. A partially reflective layer BS (not shown) is attached to the near-screen side of the first lens E1.

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

In this example, the effective focal length FG2 of the second element group is 28.18mm, the effective focal length f of the optical system is 28.00mm, the entrance pupil diameter EPD of the optical system is 5.00mm, the distance TD between the first side surface of the first lens and the second side surface of the second lens on the optical axis is 12.15mm, the center thickness CTF of the filter on the optical axis is 0.80mm, the center thickness CTR of the reflective polarizing element on the optical axis is 0.20mm, and the center thickness CTQ of the quarter-wave plate on the optical axis is 0.30mm.

Table 7 shows basic parameters of the optical system of example 3, in which the unit of radius of curvature and thickness are both millimeters (mm). Image light from the display screen IMG passes through the respective components in 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 3, wherein each of the aspherical surface types can be defined by the formula (1) given in example 1 above.

Sequence number	Surface type	Radius of curvature	Thickness of (L)	Refractive index	Abbe number	Refraction/reflection
							0	Spherical surface	Infinity is provided	Infinity is provided			Refraction by refraction
1	Spherical surface	Infinity is provided	15.0000			Refraction by refraction
							2	Spherical surface	Infinity is provided	0.8000	1.52	64.17	Refraction by refraction
3	Spherical surface	Infinity is provided	0.2000	1.52	64.17	Refraction by refraction
							4	Spherical surface	Infinity is provided	3.2678			Refraction by refraction
5	Spherical surface	175.0000	0.3000	1.52	40.43	Refraction by refraction
							6	Spherical surface	175.0000	9.0945	1.52	40.43	Refraction by refraction
7	Spherical surface	-113.1580	-9.0945	1.52	40.43	Reflection of
							8	Spherical surface	175.0000	-0.3000	1.52	40.43	Refraction by refraction
9	Spherical surface	175.0000	-3.2678			Refraction by refraction
							10	Spherical surface	Infinity is provided	3.2678			Reflection of
11	Spherical surface	175.0000	0.3000	1.52	40.43	Refraction by refraction
							12	Spherical surface	175.0000	9.0945	1.52	40.43	Refraction by refraction
13	Spherical surface	-113.1580	1.0537			Refraction by refraction
							14	Aspherical surface	-285.3638	2.0000	1.67	19.00	Refraction by refraction
15	Aspherical surface	-196.9259	8.2840			Refraction by refraction
							16	Spherical surface	Infinity is provided	0.0000			Refraction by refraction

TABLE 7

TABLE 8

As shown in fig. 6A to 6C, the optical system may include two spacing elements, a first spacing element P1 and a first auxiliary spacing element P1b, respectively, between the first lens E1 and the second lens E2, respectively. The first spacer element P1 is disposed between the first lens element E1 and the second lens element E2 and abuts against the near-screen side surface of the first lens element E1, and the first auxiliary spacer element P1b is disposed between the first spacer element P1 and the second lens element E2 and abuts against the near-screen side surface of the first spacer element P1. As shown in fig. 6A to 6C, the optical system may further include a lens barrel P0 accommodating the reflective polarizing element RP, the quarter-wave plate QWP, the first lens E1, the second lens E2, the first spacer P1, and the first auxiliary spacer P1b.

Table 9 shows the structure parameter tables of the respective spacer elements in the optical system of example 3 in three embodiments, wherein each structure parameter in table 9 has a unit of millimeter (mm).

Structural parameters	Embodiment 1	Embodiment 2	Embodiment 3
				d1s	59.3625	59.7625	59.9302
d1m	59.3625	59.7625	59.9302
				D1s	70.6090	69.4090	69.8090
D1m	70.6090	69.4090	69.8090
				d1bs	60.5222	60.5222	60.5222
d1bm	62.5978	62.5978	62.5978
				D1bs	68.9096	67.3757	67.6017
D1bm	69.6467	68.6197	68.4467
				d0s	66.6000	66.6000	66.6000
d0m	74.0726	73.2726	72.7726
				D0s	72.5672	72.5672	69.7242
D0m	77.0000	76.6000	74.3800
				EP01	10.0080	9.9460	9.8960
CP1	0.2100	0.1050	0.0680
				CP1b	2.3661	2.3830	2.6197

TABLE 9

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 embodiment 3, which represents distortion magnitude values corresponding to different angles of view. As can be seen from fig. 7A to 7C, the optical system provided in embodiment 3 can achieve good imaging quality.

In summary, the relationships shown in the optical system table 10 of examples 1 to 3.

Table 10

The present utility model also provides an optical device, which may be a stand-alone projection device such as a projector, or 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 above description is only illustrative of the preferred embodiments of the present utility model and of the principles of the technology employed. It will be appreciated by those skilled in the art that the scope of the utility model is not limited to the specific combination of the above technical features, but also encompasses other technical features which may be combined with any combination of the above technical features or their equivalents without departing from the spirit of the utility model. Such as the above-mentioned features and the technical features disclosed in the present utility model (but not limited to) having similar functions are replaced with each other.

Claims (13)

1. An optical system, comprising:

the element group sequentially comprises from a first side to a second side along the optical axis: a first element group, a second element group, and a third element group, wherein,

the first element group comprises an optical filter and a reflective polarizing element;

the second element group has positive optical power and comprises a quarter wave plate and a first lens;

the third element group includes a second lens, and the second lens has positive optical power or negative optical power;

at least one spacing element, including a first spacing element, disposed between the second element group and the third element group and abutting against the second side surface of the first lens;

a lens barrel for accommodating the lens group and the at least one spacer element;

the effective focal length FG2 of the second element group, the center thickness CTF of the optical filter on the optical axis, the center thickness CTQ of the quarter-wave plate on the optical axis, the center thickness CT1 of the first lens on the optical axis, and the maximum thickness CP1 of the first spacer element along the optical axis direction satisfy:

1.5<FG2/(CTF+CTQ+CT1+CP1)<2.9。

2. the optical system of claim 1, wherein a radius of curvature R1 of the first side surface of the first lens, an inner diameter D0s of the first side end surface of the lens barrel, and an outer diameter D0s of the first side end surface of the lens barrel satisfy:

0.8<R1/(d0s+D0s)<1.4。

3. the optical system of claim 1, wherein the radius of curvature R2 of the second side of the first lens and the inner diameter d1s of the first side of the first spacer element satisfy: -2< R2/d1s < -1.1.

4. The optical system of claim 1, wherein the at least one spacer element further comprises a first auxiliary spacer element disposed between the first spacer element and the second lens and disposed against a second side of the first spacer element; and

an air interval T12 between the first lens and the second lens on the optical axis, a maximum thickness CP1 of the first spacing element along the optical axis direction, and a maximum thickness CP1b of the first auxiliary spacing element along the optical axis direction satisfy: 0.3< T12/(CP1+CP1b) <1.1.

5. The optical system of claim 4, wherein a radius of curvature R3 of the first side of the second lens, an inner diameter D1bm of the second side of the first auxiliary spacer element, and an outer diameter D1bm of the second side of the first auxiliary spacer element satisfy: -2.2< R3/(d1bm+D1bm) < -0.7.

6. The optical system according to claim 1, wherein an inner diameter d0s of the first side end surface of the lens barrel, an inner diameter d0m of the second side end surface of the lens barrel, and an entrance pupil diameter EPD of the optical system satisfy:

1.2<(d0m-d0s)/EPD<2.3。

7. the optical system according to claim 1, wherein a separation distance EP01 between the first side end surface of the lens barrel and the first side surface of the first separation element in the optical axis direction, a center thickness CTR of the reflective polarizing element on the optical axis, a center thickness CTQ of the quarter-wave plate on the optical axis, and a center thickness CT1 of the first lens on the optical axis satisfy: 0.7< ep 01/(ctr+ctq+ct1) <1.1.

8. The optical system of claim 1, wherein an effective focal length f of the optical system, an inner diameter D1m of the second side of the first spacing element, and an outer diameter D1m of the second side of the first spacing element satisfy: 2.3< f/(D1 m-D1 m) <4.2.

9. The optical system of claim 4, wherein a distance TD on the optical axis from the first side of the first lens to the second side of the second lens, an inner diameter D1bs of the first side of the first auxiliary spacer element, and an outer diameter D1bs of the first side of the first auxiliary spacer element satisfy: 1.4< TD/(D1 bs-D1 bs) <4.0.

10. The optical system according to any one of claims 1 to 9, wherein an outer diameter D1s of the first side surface of the first spacer element, a center thickness CT1 of the first lens on the optical axis, and a center thickness CT2 of the second lens on the optical axis satisfy: 4.2< d1 s/(CT 1+ CT 2) <6.5.

11. The optical system according to any one of claims 1 to 9, wherein an outer diameter D0m of the second side end face of the lens barrel and an effective focal length FG2 of the second element group satisfy: 2.5< D0m/FG2<2.9.

12. The optical system according to any one of claims 1 to 9, wherein a maximum thickness CP1 of the first spacer element in the optical axis direction, a center thickness CTF of the optical filter on the optical axis, a center thickness CTR of the reflective polarizing element on the optical axis, and a center thickness CTQ of the quarter-wave plate on the optical axis satisfy: 0< CP1/(CTF+CTR+CTQ) <1.2.

13. An optical device comprising an optical system according to at least one of claims 1 to 12.