CN109491049B

CN109491049B - Projection optical system and augmented reality glasses with same

Info

Publication number: CN109491049B
Application number: CN201811616806.8A
Authority: CN
Inventors: 赵望妮; 陈静; 聂红星
Original assignee: Goertek Optical Technology Co Ltd
Current assignee: Goertek Optical Technology Co Ltd
Priority date: 2018-12-26
Filing date: 2018-12-26
Publication date: 2023-08-29
Anticipated expiration: 2038-12-26
Also published as: CN109491049A

Abstract

The application discloses a projection optical system and augmented reality glasses with the same, wherein the projection optical system comprises a first lens group, the first lens group comprises four lenses, and the sequence from an object side to an image side is as follows: the lens comprises a first lens with positive focal power, a second lens with positive focal power, a third lens with negative focal power and a fourth lens with positive focal power, wherein the object side surface and the image side surface of the four lenses are of aspheric structures. In addition, the focal length of the first lens and the second lens satisfies the relation 0.5< f1/f2<25; the focal length of the third lens and the fourth lens satisfy the relation-5 < f3/f4<0, wherein f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, and f4 is the focal length of the fourth lens. The application provides a projection optical system and augmented reality glasses with the same, and aims to solve the problems of overlarge volume and low illumination of the projection optical system in the prior art.

Description

Projection optical system and augmented reality glasses with same

Technical Field

The application relates to the field of projection imaging, in particular to a projection optical system and augmented reality glasses with the same.

Background

The projection system is widely applied to projectors and augmented reality (Augmented Reality, AR) glasses, and in the existing projection system, aberration of an optical system is mainly reduced through different lens combinations, resolution is improved, and therefore good imaging quality is achieved. Especially for AR glasses, excessive lens combinations may lead to an increase in the size of the projection system, which is disadvantageous for the miniaturization development of AR glasses. In order to ensure imaging quality in the projection optical system of the prior AR glasses, five or more lenses are generally adopted for combination, more lenses can increase the size and weight of the AR glasses, and the light turning in the projection optical system can be increased, so that the illuminance of the whole optical system is affected, and the requirement of miniaturization of the AR glasses cannot be met.

Disclosure of Invention

The application mainly aims to provide a projection optical system and augmented reality glasses with the same, and aims to solve the problems that the projection optical system is overlarge in size and low in illuminance in the prior art.

In order to achieve the above objective, the present application provides a projection optical system, which includes a first lens group for increasing illuminance of the projection optical system, wherein the first lens group includes four lens assemblies, and the order from an object side to an image side is: the lens comprises a first lens with positive focal power, wherein the object side surface of the first lens is of a convex aspheric structure, and the image side surface of the first lens is of a concave aspheric structure; the object side surface of the second lens is of a convex aspheric structure, and the image side surface of the second lens is of a convex aspheric structure; the object side surface of the third lens is of a concave aspheric structure, and the image side surface of the third lens is of a convex aspheric structure; a fourth lens with positive focal power, wherein the object side surface of the fourth lens is of a concave aspheric structure, and the image side surface of the fourth lens is of a convex aspheric structure; the optical axes of the first lens, the second lens, the third lens and the fourth lens are positioned on the same straight line, and the following relation is satisfied: 0.5< f1/f2<25; -5< f3/f4<0; wherein f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, and f4 is the focal length of the fourth lens.

Optionally, the projection optical system satisfies the following relationship: 0.2< C1/C2<2;0.2< C3/C4<2; wherein C1 is the center thickness of the first lens, C2 is the center thickness of the second lens, C3 is the center thickness of the third lens, and C4 is the center thickness of the fourth lens.

Optionally, the projection optical system satisfies the following relationship: 1< A1/A3<10;0.01< A2/TTL <0.1;0.2< EFFL/TTL <1; wherein A1 is a distance between the image side surface of the first lens element and the object side surface of the second lens element along the optical axis, A2 is a distance between the image side surface of the second lens element and the object side surface of the third lens element along the optical axis, A3 is a distance between the image side surface of the third lens element and the object side surface of the fourth lens element along the optical axis, EFFL is a focal length of the projection optical system, and TTL is an optical total length of the projection optical system.

Optionally, the projection optical system satisfies the following relationship: vd1 is more than or equal to 55, vd2 is more than or equal to 55, vd3 is less than or equal to 30, vd4 is more than or equal to 55; the Vd1 is an abbe number of the first lens, the Vd2 is an abbe number of the second lens, the Vd3 is an abbe number of the third lens, and the Vd4 is an abbe number of the fourth lens.

Optionally, the first lens is a cyclic olefin polymer.

Optionally, the second lens is a cyclic olefin polymer.

Optionally, the third lens is a cyclic polyolefin resin.

Optionally, the fourth lens is a cyclic olefin polymer.

Optionally, the projection optical system further comprises a diaphragm, a right angle prism, a polarization splitting prism and an image plane; the diaphragm and the right-angle prism are arranged on one side, close to the object side, of the first lens group, and the polarization beam-splitting prism and the image plane are arranged on one side, close to the image side, of the first lens group; light rays pass through the diaphragm and then enter the right-angle prism, are reflected by the inclined surface of the right-angle prism and then are emitted out of the right-angle prism, enter the first lens group, and the light rays emitted from the first lens group reach the image surface after passing through the polarization beam splitter prism.

To achieve the above object, the present application proposes an augmented reality glasses including the projection optical system according to any one of the embodiments described above.

In the technical scheme provided by the application, the projection optical system comprises a first lens group, wherein the first lens group consists of four lenses, and the sequence from an object side to an image side is as follows: the lens comprises a first lens with positive focal power, a second lens with positive focal power, a third lens with negative focal power and a fourth lens with positive focal power, wherein the object side surface and the image side surface of the four lenses are of aspheric structures. In addition, the focal length of the first lens and the second lens satisfies the relation 0.5< f1/f2<25; the focal length of the third lens and the fourth lens satisfies a relation-5 < f3/f4<0. Compared with a projection optical system formed by combining five or more lenses in the prior art, the first lens group is combined by four lenses, so that the size of the projection optical system is effectively reduced, the turning times of light in the optical system are reduced, and the problems that the size of the existing projection optical system is large and the illumination of the projection optical system is low are solved.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to the structures shown in these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of a projection optical system according to the present application;

FIG. 2 is an axial spherical aberration diagram of embodiment 1 of the present application;

FIG. 3 is a vertical axis color difference chart of example 1 of the present application;

FIG. 4 is a graph showing field curvature and optical distortion in example 1 of the present application;

FIG. 5 is a modulation transfer function chart of embodiment 1 of the present application;

FIG. 6 is an axial spherical aberration diagram of embodiment 2 of the present application;

FIG. 7 is a vertical axis color difference chart of example 2 of the present application;

FIG. 8 is a graph showing field curvature and optical distortion in accordance with example 2 of the present application;

fig. 9 is a modulation transfer function chart of embodiment 2 of the present application.

Reference numerals illustrate:

Detailed Description

The following description of the embodiments of the present application will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

It should be noted that all directional indicators (such as up, down, left, right, front, and rear … …) in the embodiments of the present application are merely used to explain the relative positional relationship, movement, etc. between the components in a particular posture (as shown in the drawings), and if the particular posture is changed, the directional indicator is changed accordingly.

Furthermore, descriptions such as those referred to as "first," "second," and the like, are provided for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implying an order of magnitude of the indicated technical features in the present disclosure. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present application, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.

In the present application, unless specifically stated and limited otherwise, the terms "connected," "affixed," and the like are to be construed broadly, and for example, "affixed" may be a fixed connection, a removable connection, or an integral body; can be mechanically or electrically connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art according to the specific circumstances.

In addition, the technical solutions of the embodiments of the present application may be combined with each other, but it is necessary to be based on the fact that those skilled in the art can implement the technical solutions, and when the technical solutions are contradictory or cannot be implemented, the combination of the technical solutions should be considered as not existing, and not falling within the scope of protection claimed by the present application.

The application provides a projection optical system and augmented reality glasses with the same.

Referring to fig. 1, the projection optical system includes a first lens assembly 100, the first lens assembly 100 is configured to enhance illuminance of the projection optical system, the first lens assembly 100 includes four lens assemblies, in order from an object side to an image side: a first lens 10 having positive optical power, wherein an object-side surface of the first lens 10 has a convex aspheric structure, and an image-side surface has a concave aspheric structure; a second lens 20 having positive optical power, wherein an object-side surface of the second lens 20 has a convex aspherical structure, and an image-side surface has a convex aspherical structure; a third lens 30 having negative optical power, wherein an object-side surface of the third lens 30 has a concave aspheric structure, and an image-side surface has a convex aspheric structure; a fourth lens element 40 with positive refractive power, wherein an object-side surface of the fourth lens element 40 has a concave aspheric structure, and an image-side surface has a convex aspheric structure; the optical axes of the first lens 10, the second lens 20, the third lens 30, and the fourth lens 40 are positioned on the same straight line, and satisfy the following relationship: 0.5< f1/f2<25; -5< f3/f4<0; where f1 is the focal length of the first lens 10, f2 is the focal length of the second lens 20, f3 is the focal length of the third lens 30, and f4 is the focal length of the fourth lens 40.

In the technical scheme provided by the application, the projection optical system comprises a first lens group 100, wherein the first lens group 100 consists of four lenses, and the sequence from an object side to an image side is as follows: the object side surface and the image side surface of the four lenses are in an aspheric structure. Further, the focal length of the first lens 10 and the second lens 20 satisfies the relationship 0.5< f1/f2<25; the focal length of the third lens 30 and the fourth lens 40 satisfies the relationship-5 < f3/f4<0. Compared with a projection optical system formed by combining five or more lenses in the prior art, the first lens group 100 is combined by four lenses, so that the size of the projection optical system is effectively reduced, the turning times of light in the optical system are reduced, and the problems that the size of the existing projection optical system is large and the illumination of the projection optical system is low are solved.

In some alternative embodiments, the projection optical system satisfies the following relationship: 0< C1/C2<1,1< C3/C4<2.

In some alternative embodiments, the projection optical system satisfies the following relationship: 0< A1/A3<10,0< A2/TTL <1,0< EFFL/TTL <1.

Wherein f1 is the focal length of the first lens 10; f2 is the focal length of the second lens 20; f3 is the focal length of the third lens 30; f4 is the focal length of the fourth lens 40.

C1 is the center thickness of the first lens 10; c2 is the center thickness of the second lens 20; c3 is the center thickness of the third lens 30; c4 is the center thickness of the fourth lens 40.

A1 is a distance between the image side surface of the first lens element 10 and the object side surface of the second lens element 20 along the optical axis; a2 is the distance between the image side surface of the second lens element 20 and the object side surface of the third lens element 30 along the optical axis; a3 is a distance between the image side surface of the third lens element 30 and the object side surface of the fourth lens element 40 along the optical axis.

TTL is the total optical length of the projection optical system; EFFL is the focal length of the projection optical system.

In some alternative embodiments, the projection optical system satisfies the following relationship: vd1 is more than or equal to 55, vd2 is more than or equal to 55, vd3 is less than or equal to 30, vd4 is more than or equal to 55;

wherein Vd1 is the abbe number of the first lens 10, vd2 is the abbe number of the second lens 20, vd3 is the abbe number of the third lens 30, and Vd4 is the abbe number of the fourth lens 40.

In some alternative embodiments, the first lens 10, the second lens 20, and the fourth lens 40 are cycloolefin polymers (Cyclo Olefin Polymer, COP), and the third lens 30 is a cyclic polyolefin resin (Cyclo Olefin Copolymer, COC). It is understood that the present application is not limited thereto, and in order to meet the requirements of the projection optical system, in another embodiment, the lenses in the first lens group 100 may be other optical glass or optical plastic.

Referring to fig. 1, in the projection optical system of the present application, the projection optical system further includes a diaphragm 50, a prism 60, a polarization splitting prism 70, and an image plane 90; the diaphragm 50 and the prism 60 are disposed on a side of the first lens group 100 near the object side, and the polarization splitting prism 70 and the image plane 90 are disposed on a side of the first lens group 100 near the image side. In a specific embodiment, the light beam emitted from the diaphragm 50 after being reflected by the prism 60 is emitted out of the prism 60, and sequentially passes through the first lens 10, the second lens 20, the third lens 30 and the fourth lens 40 and then is emitted into the polarization splitting prism 70, after being split by the polarization splitting prism 70, one beam of light beam is transmitted on the splitting plane, after being emitted out of the polarization splitting prism 70, reaches the image plane 90, and the other beam of light beam is reflected on the splitting plane, and after being emitted out of the other surface of the polarization splitting prism 70, enters a subsequent illumination system or other optical systems.

In some alternative embodiments, the projection optical system further includes a protective glass 80, the protective glass 80 being disposed between the polarization splitting prism 70 and the image plane 90, and the protective glass 80 being used to protect the projection optical system.

The first embodiment projection optical system design data is shown in table 1 below:

TABLE 1

In example 1, the parameters are as follows:

f1 -26.99; f2 -6.75; f3 =8.89; f4 = -25.62. F1/f2=4.0; f2/f3= -0.35.

C1 =1.8; c2 =2.42; c3 =1.35; c4 =1.45. Then c1/c2=0.74; c3/c4=0.93.

A1＝0.51；A2＝1.43；A3＝0.1；TTL＝25，EFFL＝12.5。

A1/A3＝5.1；A2/TTL＝0.057；EFFL/TTL＝0.5。

Wherein, from the object side to the image side, the object side surface of the first lens 10 is an S1 surface 11, and the image side surface is an S2 surface 12; the object side surface of the second lens element 20 is an S3 surface 21, and the image side surface thereof is an S4 surface 22; the object side surface of the third lens element 30 is an S5 surface 31, and the image side surface thereof is an S6 surface 32; the fourth lens element 40 has an object-side surface of S7 surface 41 and an image-side surface of S8 surface 42. A2, A4, A8, a10, a12, a14, a16 are aspherical higher order coefficients of an aspherical lens, and are specifically shown in table 2.

TABLE 2

Surface numbering

A4

A6

A8

A10

A12

A14

A16

S1 surface

-9.6E-05

-2.1E-06

1.8E-05

-9.5E-07

-1.5E-08

2.7E-09

-8.0E-11

S2 surface

2.4E-04

8.6E-05

2.1E-05

-1.5E-06

-4.3E-08

7.1E-09

-2.0E-10

S3 surface

9.8E-04

-4.8E-05

-1.5E-05

6.0E-07

1.7E-08

-5.3E-10

-1.0E-11

S4 surface

-1.9E-03

-4.8E-05

-9.8E-06

-9.0E-07

1.1E-07

-1.7E-09

-3.0E-11

S5 surface

-6.2E-03

-1.1E-04

3.7E-05

-1.8E-06

1.0E-08

1.4E-09

-2.8E-11

S6 surface

-3.2E-03

2.9E-05

-5.2E-06

1.9E-07

2.0E-08

-1.3E-09

2.1E-11

S7 surface

8.3E-03

-5.2E-04

1.0E-05

-9.3E-08

-9.0E-09

4.7E-10

-4.0E-12

S8 surface

4.8E-03

-2.3E-04

-3.2E-07

4.3E-07

-9.2E-09

-1.0E-09

3.4E-11

Referring to fig. 2, fig. 2 is an axial spherical aberration chart of embodiment 1, wherein axial spherical aberration refers to a distance between an edge light focus and a paraxial focus in an optical system, and is used for evaluating imaging quality of an on-axis object point;

referring to fig. 3, fig. 3 is a vertical-axis chromatic aberration chart of embodiment 1, wherein the vertical-axis chromatic aberration refers to a chromatic aberration of magnification, and mainly refers to a multi-color principal ray of an object side, which is changed into a plurality of rays when exiting from an image side due to chromatic dispersion of a refraction system, and is the difference of focal positions of hydrogen blue light and hydrogen red light on an image plane;

referring to fig. 4, fig. 4 is a field curvature and an optical distortion chart of embodiment 1, wherein the field curvature is used to represent the position change of the beam image point at different field points away from the image plane, and the optical distortion refers to the vertical axis distance between the principal ray at the principal wavelength of a certain field and the image plane point away from the ideal image point;

referring to fig. 5, fig. 5 is a modulation transfer function chart of embodiment 1, wherein a modulation transfer function (Modulation Transfer Function, MTF) refers to a relationship between a modulation degree and a line pair per millimeter in an image, and is used for evaluating a scene detail reduction capability.

The second embodiment projection optical system design data is shown in table 3 below:

TABLE 3 Table 3

In example 2, the parameters are as follows:

f1 -20.24; f2 -5.62; f3 =6.94; f4 -15.52. F1/f2=3.6; f2/f3= -0.45.

C1 =1.27; c2 =1.62; c3 =0.98; c4 =1.16. Then c1/c2=0.78; c3/c4=0.84.

A1＝0.25；A2＝1.07；A3＝0.1；TTL＝19.2，EFFL＝9.4。

A1/A3＝2.5；A2/TTL＝0.056；EFFL/TTL＝0.49。

Wherein, from the object side to the image side, the object side surface of the first lens 10 is an S1 surface 11, and the image side surface is an S2 surface 12; the object side surface of the second lens element 20 is an S3 surface 21, and the image side surface thereof is an S4 surface 22; the object side surface of the third lens element 30 is an S5 surface 31, and the image side surface thereof is an S6 surface 32; the fourth lens element 40 has an object-side surface of S7 surface 41 and an image-side surface of S8 surface 42. A2, A4, A8, a10, a12, a14, a16 are aspherical higher order coefficients of an aspherical lens, and are specifically shown in table 4.

TABLE 4 Table 4

Surface numbering

A4

A6

A8

A10

A12

A14

A16

S1 surface

5.2E-04

6.5E-05

1.3E-04

-1.3E-05

-3.6E-07

1.1E-07

-5.3E-09

S2 surface

6.4E-04

3.4E-04

1.7E-04

-2.0E-05

-1.1E-06

2.8E-07

-1.3E-08

S3 surface

1.9E-03

-9.1E-05

-1.1E-04

6.8E-06

4.1E-07

-1.2E-08

-1.1E-09

S4 surface

-3.6E-03

-2.0E-04

-8.8E-05

-1.2E-05

2.7E-06

-7.9E-08

-2.0E-09

S5 surface

-1.3E-02

-5.2E-04

2.6E-04

-2.5E-05

3.6E-07

6.5E-08

-2.8E-09

S6 surface

-7.6E-03

-5.0E-05

-2.6E-05

3.0E-06

4.1E-07

-6.7E-08

2.4E-09

S7 surface

1.9E-02

-2.2E-03

9.1E-05

-9.3E-07

-3.0E-07

1.4E-08

2.8E-10

S8 surface

1.1E-02

-9.2E-04

-3.3E-06

5.6E-06

-2.1E-07

-4.3E-08

2.6E-09

Referring to fig. 6, fig. 6 is an axial spherical aberration chart of embodiment 2, wherein axial spherical aberration refers to a distance between an edge light focus and a paraxial focus in an optical system, and is used for evaluating imaging quality of an on-axis object point;

referring to fig. 7, fig. 7 is a vertical-axis chromatic aberration chart of embodiment 2, wherein the vertical-axis chromatic aberration refers to a chromatic aberration of magnification, and mainly refers to a multi-color principal ray of an object side, which is changed into a plurality of rays when exiting from an image side due to chromatic dispersion of a refraction system, and is the difference of focal positions of hydrogen blue light and hydrogen red light on an image plane;

referring to fig. 8, fig. 8 is a field curvature and an optical distortion chart of embodiment 2, wherein the field curvature is used to represent the position change of the beam image point at different field points away from the image plane, and the optical distortion refers to the vertical axis distance between the principal ray at the principal wavelength of a certain field and the image plane point away from the ideal image point;

referring to fig. 9, fig. 9 is a modulation transfer function chart of embodiment 2, wherein the modulation transfer function (Modulation Transfer Function, MTF) refers to a relationship between a modulation degree and a line pair per millimeter in an image, and is used for evaluating the scene detail reduction capability.

The foregoing description is only of the preferred embodiments of the present application and is not intended to limit the scope of the application, and all equivalent structural changes made by the description of the present application and the accompanying drawings or direct/indirect application in other related technical fields are included in the scope of the application.

Claims

1. The utility model provides a projection optical system, its characterized in that, projection optical system includes first lens group, first lens group is used for improving projection optical system's illuminance, first lens group comprises four lens subassembly, from the thing side to image side in proper order:

the lens comprises a first lens with positive focal power, wherein the object side surface of the first lens is of a convex aspheric structure, and the image side surface of the first lens is of a concave aspheric structure;

the object side surface of the second lens is of a convex aspheric structure, and the image side surface of the second lens is of a convex aspheric structure;

the object side surface of the third lens is of a concave aspheric structure, and the image side surface of the third lens is of a convex aspheric structure;

a fourth lens with positive focal power, wherein the object side surface of the fourth lens is of a concave aspheric structure, and the image side surface of the fourth lens is of a convex aspheric structure;

the optical axes of the first lens, the second lens, the third lens and the fourth lens are positioned on the same straight line, and the following relation is satisfied: 0.5< f1/f2<25; -5< f3/f4<0;

wherein f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, and f4 is the focal length of the fourth lens.

2. The projection optical system according to claim 1, wherein the projection optical system satisfies the following relationship: 0.2< C1/C2<2;0.2< C3/C4<2;

wherein C1 is the center thickness of the first lens, C2 is the center thickness of the second lens, C3 is the center thickness of the third lens, and C4 is the center thickness of the fourth lens.

3. The projection optical system according to claim 1, wherein the projection optical system satisfies the following relationship: 1< A1/A3<10;0.01< A2/TTL <0.1;0.2< EFFL/TTL <1;

wherein A1 is a distance between the image side surface of the first lens element and the object side surface of the second lens element along the optical axis, A2 is a distance between the image side surface of the second lens element and the object side surface of the third lens element along the optical axis, A3 is a distance between the image side surface of the third lens element and the object side surface of the fourth lens element along the optical axis, EFFL is a focal length of the projection optical system, and TTL is an optical total length of the projection optical system.

4. The projection optical system according to claim 1, wherein the projection optical system satisfies the following relationship: vd1 is more than or equal to 55, vd2 is more than or equal to 55, vd3 is less than or equal to 30, vd4 is more than or equal to 55;

the Vd1 is an abbe number of the first lens, the Vd2 is an abbe number of the second lens, the Vd3 is an abbe number of the third lens, and the Vd4 is an abbe number of the fourth lens.

5. The projection optical system of claim 4 wherein the first lens is a cyclic olefin polymer.

6. The projection optical system of claim 4 wherein the second lens is a cyclic olefin polymer.

7. The projection optical system according to claim 4, wherein the third lens is a cyclic polyolefin resin.

8. The projection optical system of claim 4 wherein the fourth lens is a cyclic olefin polymer.

9. The projection optical system according to any one of claims 1 to 8, further comprising a diaphragm, a right angle prism, a polarization splitting prism, and an image plane; the diaphragm and the right-angle prism are arranged on one side, close to the object side, of the first lens group, and the polarization beam-splitting prism and the image plane are arranged on one side, close to the image side, of the first lens group;

light rays pass through the diaphragm and then enter the right-angle prism, are reflected by the inclined surface of the right-angle prism and then are emitted out of the right-angle prism, enter the first lens group, and the light rays emitted from the first lens group reach the image surface after passing through the polarization beam splitter prism.

10. An augmented reality glasses, characterized in that it comprises the projection optical system according to claim 9.