1. An optical system for augmented reality, comprising a beam splitter (a1) located a distance in front of the visual axis of the eye; the spectroscope element (A1) is a free-form surface, the side facing the eyes is a front surface (S1) coated with a certain transmittance inverse ratio film layer, the other side is a rear surface (S2) coated with a reflection reducing film, and the spectroscope element satisfies the following relation:

-55<R<-90；

1.5mm<TC<2.5mm；

wherein R is a curvature radius of the spectroscope element (A1), and TC is a center thickness of the spectroscope (A1).

2. An augmented reality optical system as claimed in claim 1 further satisfying the following relationship:

18°<θ<25°；

32mm＜d＜45mm；

wherein, theta is an included angle between the optical axis of the spectroscope element (A1) and the visual axis, and d is the distance from the human eye to the center of the spectroscope.

3. An augmented reality optical system as claimed in claim 1 wherein the beam splitter is a free-form surface.

4. An augmented reality optical system as claimed in claim 1, wherein the free form surface beam splitter (a1) is spherically connected except for the active area.

5. An augmented reality optical system as claimed in claim 1, wherein the following relationship is satisfied:

40°<FOV<55°；

wherein the FOV is a field angle of the augmented reality optical system.

Background

With the technical development of virtual reality and augmented reality, in recent years, head-mounted AR and VR devices are widely used in various industries, because the head-mounted AR and VR devices need to be worn on the head, and the requirements for portability and small size are particularly important. At present, most of head-mounted AR and VR equipment has the problems that under the condition of realizing light and small size, the image quality is often insufficient and cannot meet the requirements; this patent will be further described in order to achieve the features of lightness, portability, etc. with good image quality.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides an augmented reality optical system, aiming at solving the technical problem of realizing lightness and portability under the condition of meeting good image quality.

To achieve the above object, the present invention provides an optical system for augmented reality, comprising a spectroscope (a1) located at a distance in front of the visual axis of an eye; the beam splitter element (A1) is a free-form surface, the side facing the eyes is a front surface (S1) coated with a certain transmittance inverse ratio film layer, and the other side is a rear surface (S2) coated with an antireflection film; and the beam splitting mirror element satisfies the following relation: -55< R < -90; 1.5mm < TC <2.5 mm; wherein R is a curvature radius of the spectroscope element (A1), and TC is a center thickness of the spectroscope (A1).

Preferably, the optical system for augmented reality satisfies the following relation: 18 ° < θ <25 °; d is more than 32mm and less than 45 mm; wherein, theta is the included angle between the optical axis of the free-form surface spectroscope element (A1) and the visual axis, and d is the distance from the human eye to the center of the spectroscope.

Preferably, the beam splitter (a1) is a free-form surface.

Preferably, the beam splitter (a1) has a more curved area, except for the effective area, which is engaged by a spherical surface.

Preferably, the augmented reality optical system further satisfies the following relation: 40 ° < FOV <55 °;

generally, compared with the prior art, the above technical solution conceived by the present invention has the following advantages:

(1) the spectroscope of the augmented reality system is a free-form surface, so that the system has good correction capability on the aberration of the system and has good imaging effect; (2) the optical system has a larger view field angle; (3) the angle between the optical axis and the visual axis of the spectroscope is moderate, the distance from human eyes to the spectroscope is small, and the size of a packaging structure is reduced well.

Drawings

FIG. 1 is a schematic structural diagram of an embodiment of the present invention;

FIG. 2 is a distorted grid pattern of embodiment 1 of the present invention;

FIG. 3 is a distorted grid pattern of embodiment 2 of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

1. An optical system for augmented reality, comprising a beam splitter (a1) located a distance in front of the visual axis of the eye; the beam splitter element (A1) is a free-form surface, the side facing the eyes is a front surface (S1) coated with a certain transmittance inverse ratio film layer, and the other side is a rear surface (S2) coated with an antireflection film; and the beam splitting mirror element satisfies the following relation:

-55<R<-90；

1.5mm<TC<2.5mm；

wherein R is a radius of curvature of the beam splitter element (A1), and TC is a center thickness of the beam splitter (A1);

this augmented reality optical system's spectroscope curvature radius is great, and the spectroscope effective area is comparatively mild, and is comparatively comfortable when people look at the image, and the center of spectroscope is thick less in addition, and under the injection moulding allowed the condition, it is thick to be favorable to alleviateing the holistic weight of product to reduce the center.

2. The optical system for augmented reality is characterized by further satisfying the following relation:

18°<θ<25°；

32mm＜d＜45mm；

wherein, theta is an included angle between the optical axis of the spectroscope element (A1) and the visual axis, and d is the distance from the human eye to the center of the spectroscope. The angle between the optical axis and the visual axis of the spectroscope of the augmented reality optical system is small, image light can be better reflected to enter human eyes, on the premise that the display (A2) does not block the light entering the human eyes, the value of d is constant, and the smaller the angle theta is, so that the size can be favorably reduced, and the requirements of lightness, smallness and portability are met.

3. The optical system for augmented reality is characterized in that the spectroscope is a free-form surface.

The free-form surface is used for design, the aberration of each view field can be well corrected, and extra lens groups are not required to be introduced to correct the aberration, so that the image quality of the system is improved, and the cost is reduced.

4. The optical system for augmented reality is characterized in that the free-form surface spectroscope (A1) is connected with the curved area by a spherical surface except the effective area.

The free-form surface is designed, a bad place is except an effective area, the free-form surface can become extremely bent and is not beneficial to processing, and if the bent part is cut off, the free-form surface is not beneficial to making a structure for leaning outside. In order to solve the problem, the patent provides a method, the bent part can be removed, and then the spherical surface with the curvature similar to that of the free-form surface is used for extending the section, so that the effect of natural transition is achieved, the external structural bearing can be met, and the processing requirement can be met.

5. The optical system for augmented reality is characterized by satisfying the following relation:

40°<FOV<55°；

wherein the FOV is a field angle of the augmented reality optical system.

An augmented reality optical system has a larger angle of view, under the condition that the distance d from human eyes to a free-form surface spectroscope (A1) is the same, the angle of view is large, the visible range is wide, the horizontal angle of view of a single eye of a person can reach 154 degrees under the general condition, the comfortable angle of view is 60 degrees, and the angle of view of the system can be well matched with the comfortable angle of view of the human eyes.

Example 1

As a specific embodiment of the present invention, the parameters of the augmented reality optical system are shown in the following tables 1 and 2:

TABLE 1 structural parameter table of augmented reality optical system

TABLE 2 free-form surface coefficient of the reflecting surface of an augmented reality optical system beamsplitter

In this embodiment, the object distance is 2000mm and the distance from the human eye to the beam splitter is 42 mm. The overall volume will be slightly larger but the imaging quality will be better.

Example 2

As a specific embodiment of the present invention, the parameters of the augmented reality optical system are shown in the following tables 3 and 4:

TABLE 3 structural parameter table of augmented reality optical system

TABLE 4 free-form surface coefficient of splitter mirror reflection surface of augmented reality optical system

In this embodiment, the object distance is 2000mm, and the distance from the human eye to the beam splitter is 35 mm. Smaller than in example 1, the image quality was comparable to that in example 1.

It will be understood by those skilled in the art that the foregoing is merely a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included within the scope of the present invention.