WO2025060719A1 - Near-eye optical system and head-worn display device - Google Patents

Abstract

Embodiments of the present application provide a near-eye optical system and a head-worn display device. The near-eye optical system comprises a first imaging element and a second imaging element which are arranged along a same optical axis. The first imaging element comprises a polarization reflection element and a phase retarder. The second imaging element comprises at least one lens and at least one optical assembly, and the optical assembly is configured to be used for selectively reflecting and transmitting circularly polarized light. According to the near-eye optical system provided by the embodiments of the present application, an ultrathin VR scheme can be achieved.

Description

Near-eye optical system and head-mounted display device Technical Field

The embodiments of the present application relate to the field of optical display technology, and more specifically, to a near-eye optical system and a head-mounted display device.

Background Art

At present, the optical solution of VR equipment is relatively thick. Taking VR glasses as an example, they are somewhat different from conventional glasses, and users do not feel comfortable wearing them, especially after wearing them for a long time. How to minimize the thickness of the optical system inside the VR device (along the optical axis) while ensuring high-definition imaging is a problem that needs to be solved.

Summary of the invention

The purpose of this application is to provide a new technical solution for a near-eye optical system and a head-mounted display device, which can achieve a lightweight design of the near-eye optical system while taking into account high-definition imaging.

In a first aspect, the present application provides a near-eye optical system. The near-eye optical system comprises a first imaging element and a second imaging element arranged along the same optical axis;

The first imaging element includes a polarized reflection element and a phase retarder;

The second imaging element includes at least one lens and at least one optical component, wherein the optical component is configured to selectively reflect and transmit circularly polarized light.

Optionally, the first imaging element and the second imaging element are used to make the number of folds of the light in the light path be ≥2;

The light can be refracted once in one of the optical components.

Optionally, the optical component includes at least one of a first liquid crystal film and a second liquid crystal film;

Wherein, the second liquid crystal film is configured so that when reflecting circularly polarized light, the rotation direction of the circularly polarized light does not change.

Optionally, the optical component includes any one of the first liquid crystal film and the second liquid crystal film. One, and the optical component also includes a beam splitter film.

Optionally, the second imaging element comprises a first lens;

Any one of the first liquid crystal film and the second liquid crystal film, and the light-splitting film are respectively disposed on two surfaces of the first lens;

or,

Any one of the first liquid crystal film and the second liquid crystal film is stacked with the light-splitting film and is disposed on any surface of the first lens.

Optionally, the optical component consists of the first liquid crystal film and the second liquid crystal film, wherein the second liquid crystal film is located on a side of the first liquid crystal film away from the first imaging element.

Optionally, the second imaging element comprises a first lens;

The first liquid crystal film and the second liquid crystal film are respectively disposed on two surfaces of the first lens;

or,

The first liquid crystal film and the second liquid crystal film are stacked and arranged on any surface of the first lens.

Optionally, the near-eye optical system further comprises a display, wherein the display is located on a side of the first imaging element away from the second imaging element;

The display can emit light for imaging display; wherein the light projected onto the first imaging element is linearly polarized light.

Optionally, the polarized reflective element and the phase retarder are stacked to form a superimposed element, and the superimposed element is located between the display and the second imaging element.

Optionally, the superimposed element is arranged on the light emitting surface of the display.

Optionally, the first imaging element further includes a second lens, and the second lens is located between the display and the second imaging element, and the overlapping element is arranged on any surface of the second lens.

Optionally, the overlapping element is arranged on a surface of the second lens close to the display;

Wherein, a surface of the first lens away from the display and a surface of the second lens close to the display are glued together or close to each other.

Optionally, the total optical length TTL of the near-eye optical system is ≤15 mm.

Optionally, the reciprocal of the radius a of the surface through which the light passes most times is proportional to the total radius of the near-eye optical system. The focal length f satisfies: -1＜a/f＜0;

The surface of the first lens close to the display is the surface through which the light passes most times in the near-eye optical system.

In a second aspect, the present application provides a head-mounted display device. The head-mounted display device includes:

a housing; and

A near-eye optical system as described in the first aspect.

The beneficial effects of this application are:

According to the near-eye optical system provided in the embodiment of the present application, through the principle of polarization of light, specially designed optical components are combined with polarization reflection elements and phase delay devices to form a new reentrant optical architecture. In this way, while ensuring high-definition imaging, the thickness of the entire near-eye optical system is effectively reduced (along the optical axis), thereby facilitating the realization of an ultra-thin VR optical solution.

Other features and advantages of the present specification will become apparent from the following detailed description of exemplary embodiments of the present specification with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the specification and, together with the description, serve to explain the principles of the specification.

FIG1 is a schematic diagram of a near-eye optical system according to an embodiment of the present application;

FIG2 is a schematic diagram of the arrangement positions of an optical component, a phase retarder, and a polarization reflection element provided in an embodiment of the present application;

FIG3 is a light path propagation diagram of a near-eye optical system provided in an embodiment of the present application;

FIG4 is a dot array diagram of the near-eye optical system provided in FIG1 ;

FIG5 is a modulation transfer function MTF diagram of the near-eye optical system provided in FIG1 ;

FIG6 is a diagram of field curvature and distortion of the near-eye optical system provided in FIG1 ;

FIG7 is a diagram of vertical axis chromatic aberration of the near-eye optical system provided in FIG1 ;

FIG8 is a second schematic diagram of the structure of the near-eye optical system provided in an embodiment of the present application;

FIG9 is a dot array diagram of the near-eye optical system provided in FIG8 ;

FIG10 is a modulation transfer function MTF diagram of the near-eye optical system provided in FIG8 ;

FIG11 is a diagram of field curvature and distortion of the near-eye optical system provided in FIG8 ;

FIG12 is a vertical axis chromatic aberration diagram of the near-eye optical system provided in FIG8 ;

FIG13 is another optical path propagation path diagram of the near-eye optical system provided in an embodiment of the present application;

FIG. 14 is another optical path propagation diagram of the near-eye optical system provided in an embodiment of the present application.

Description of reference numerals:

01. Aperture; 1. Display; 2. First imaging element; 3. Second imaging element;

21. polarized reflection element; 22. phase retarder; 23. second lens; 231. third surface; 232. fourth surface;

31. Optical component; 311. First liquid crystal film; 312. Second liquid crystal film; 313. Bezel; 32. First lens; 321. First surface; 322. Second surface.

DETAILED DESCRIPTION

Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangement of components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present application.

The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present application, its application, or uses.

Techniques and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the techniques and equipment should be considered part of the specification.

In all examples shown and discussed herein, any specific values should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

The near-eye optical system and the head-mounted display device provided in the embodiments of the present application are described in detail below in conjunction with the accompanying drawings.

According to one aspect of an embodiment of the present application, a near-eye optical system is provided, wherein the near-eye optical system is applicable to a virtual reality display device, such as a VR head-mounted display device. The form of the head-mounted display device includes VR smart glasses or VR smart helmets, etc. The embodiments of the present application do not limit the specific form of the head-mounted display device.

The near-eye optical system proposed in the embodiment of the present application, as shown in FIG1, comprises a first imaging element 2 and a second imaging element 3 arranged in sequence along the same optical axis. The first imaging element 2 comprises a polarized reflection element 21 and a phase retarder 22. The second imaging element 3 comprises at least one lens and at least one optical component 31, wherein the optical component 31 is configured to selectively reflect and transmit circularly polarized light.

According to the near-eye optical system provided by the above embodiment, from the perspective of its optical architecture, it includes a first imaging element 2 and a second imaging element 3 arranged along the same optical axis, wherein the first imaging element 2 is located on the side of the near screen, and the second imaging element 3 is located on the side of the near aperture 01. Among them, no lens may be used in the first imaging element 2, and only one lens may be used in the second imaging element 3, as shown in FIG1. In other words, at least one lens may be used in the entire near-eye optical system, and on this basis, the requirements of high-definition imaging can be taken into account. Since the number of lenses used can be as low as one, this is conducive to reducing the weight and volume of the entire near-eye display system.

According to the near-eye optical system provided by the above embodiment of the present application, an optical component 31 is introduced into the second imaging element 3. Through the principle of light polarization, the specially designed optical component 31 is matched with the polarization reflection element 21 and the phase retarder 22 arranged on the near-screen side to form a new return optical architecture, which can effectively reduce the thickness (along the optical axis direction) of the entire near-eye optical system while ensuring high-definition imaging, thereby facilitating the realization of an ultra-thin VR optical solution.

The phase retarder 22 is, for example, a quarter wave plate.

Of course, the phase retarder 22 can also be configured as other phase retarder plates, such as a half-wave plate, as required.

1 and 3 , the phase retarder 22 is located in the first imaging element 2 disposed near the screen, and is used to convert the polarization state of light near the screen, for example, to convert linearly polarized light into circularly polarized light, or to convert circularly polarized light into linearly polarized light.

In the optical solution provided in the embodiment of the present application, the phase retarder 22 can make the light incident on the second imaging element 3 circularly polarized, see Fig. 3. The optical component 31 in the second imaging element 3 can directly process the circularly polarized light.

The polarized reflective element 21 is, for example, a linear polarizer, which is, for example, a horizontal linear polarizer. A polarizing reflector is a polarizing reflector that reflects linear polarized light at a vertical angle and transmits linear polarized light at a vertical angle, or a polarizing reflector that reflects linear polarized light at any other specific angle and transmits linear polarized light at a direction perpendicular to the angle.

According to the near-eye optical system provided by the embodiment of the present application, the polarized reflection element 21 and the phase retarder 22 arranged on the near-screen side can make the light directed to the second imaging element 3 circularly polarized light, and the optical component 31 in the second imaging element 3 can selectively reflect and transmit the incident circularly polarized light, which realizes a new folding optical path optical structure, under which only one lens can be introduced into the second imaging element 3, thereby reducing the number of lenses used in the entire near-eye optical system, thereby facilitating the realization of an ultra-thin design of the near-eye optical system. The light is folded back multiple times between the first imaging element 2 and the second imaging element 3, which is conducive to clear imaging.

Of course, in practical applications, two or more lenses may be used in the near-eye optical system as needed.

For example, two lenses may be used in the near-eye optical system, see FIG. 8 , and an additional lens may be disposed in the first imaging element 2 , which lens may be used to support the polarizing reflection element 21 and the phase retarder 22 , for example.

It should be noted that, for near-eye optical systems, the imaging effect can be improved as the number of lenses used increases, but the weight and production cost of the near-eye optical system may increase.

As a preferred solution of the present application, 1 to 2 lenses may be used in the near-eye optical system.

In some examples of the present application, referring to FIG. 1 and FIG. 3 , the first imaging element 2 and the second imaging element 3 are used to make the light bend ≥ 2 times in the optical path; wherein the light can be bend once in one of the optical components 31 .

1 and 3 , the polarized reflective element 21 , the phase retarder 22 , and the optical component 31 are introduced into the optical architecture of the near-eye optical system to form a folded optical path.

The polarized reflection element 21 and the phase retarder 22 are both located in the first imaging element 2, and the optical component 31 is located in the second imaging element 3. In this way, the light used for imaging display passes through the first imaging element 2 and the second imaging element 3, and after being folded back at least twice between the two imaging elements, the light finally emerges from the second imaging element 3 to form a clear image at the aperture 01.

Specifically, the light used for imaging display will be reflected by the polarized reflection element 21, the phase The retarder 22 and the optical component 31 are folded twice. Referring to FIG3 , on the side near the screen, the horizontal linear polarized light passes through the polarization reflection element 21 and is directed to the phase retarder 22. The phase retarder 22 converts the horizontal linear polarized light into left-handed circularly polarized light. The left-handed circularly polarized light is reflected by the optical component 31 and converted into right-handed circularly polarized light. The right-handed circularly polarized light passes through the phase retarder 22 and becomes vertical linear polarized light. The vertical linear polarized light is reflected by the polarization reflection element 21 to the phase retarder 22 and becomes right-handed circularly polarized light. At this time, the light is folded for the first time. After that, the right-handed circularly polarized light is incident on the second imaging element 3. The optical component 31 folds the right-handed circularly polarized light once. Finally, the light is emitted from the second imaging element 3 and enters the aperture 01 for imaging.

Optionally, the number of the optical components 31 may be increased in the second imaging element 3 to increase the number of light refracting times, which may improve imaging clarity.

It should be noted that, in order to ensure the clarity of imaging, the optical solution of the present application is designed so that the light needs to be refracted at least twice in the entire optical path.

In some examples of the present application, referring to FIG3, FIG13 and FIG14 respectively, the optical component 31 includes at least one of a first liquid crystal film 311 and a second liquid crystal film 312. The second liquid crystal film 312 is configured to reflect circularly polarized light without changing the handedness of the circularly polarized light.

According to the above example, the first liquid crystal film 311 is different from the second liquid crystal film 312. After the first liquid crystal film 311 reflects circularly polarized light, the rotation direction of the circularly polarized light will change, for example, left-handed circularly polarized light is converted into right-handed circularly polarized light, or right-handed circularly polarized light is converted into left-handed circularly polarized light. However, after the second liquid crystal film 312 reflects circularly polarized light, the rotation direction of the circularly polarized light does not change, for example, left-handed circularly polarized light is still left-handed circularly polarized light after reflection, and right-handed circularly polarized light is still right-handed circularly polarized light after reflection.

The optical component 31 including a liquid crystal film is introduced into the second imaging element 3 to modulate the handedness of the circularly polarized light.

In the optical solution provided in the embodiment of the present application, either the first liquid crystal film 311 or the second liquid crystal film 312 can be used in combination with a dichroic film 313 , or the first liquid crystal film 311 and the second liquid crystal film 312 can be used in combination to achieve the desired effect.

In some examples of the present application, referring to FIG. 3 and FIG. 14 , the optical component 31 includes any one of the first liquid crystal film 311 and the second liquid crystal film 312 , and the optical component 31 A beam splitting film 313 is also included.

According to the above example, the optical component 31 may include two different optical films, one is a dichroic film 313 (i.e., a semi-reflective and semi-transmissive film), and the other is a first liquid crystal film 311 or a second liquid crystal film 312. Combining any liquid crystal film with the dichroic film 313 can achieve selective reflection and transmission of circularly polarized light and at least one refraction of the circularly polarized light.

In some examples of the present application, referring to FIGS. 1 to 3 , the second imaging element 3 includes a first lens 32; any one of the first liquid crystal film 311 and the second liquid crystal film 312, and the dichroic film 313 are disposed on two surfaces of the first lens 32; or, any one of the first liquid crystal film 311 and the second liquid crystal film 312 and the dichroic film 313 are stacked and disposed on any surface of the first lens 32.

According to the above example, a lens, namely the above-mentioned first lens 32, is used in the second imaging element 3. The first lens 32 can support the optical component 31 and can also realize optical imaging, eliminate chromatic aberration, etc., thereby improving the optical imaging effect.

In the above example, the optical component 31 is directly arranged on the first lens 32, and there is no need to introduce an additional flat support to support the optical component 31, so that the optical structure can be simplified. In particular, by forming the first lens 32 and the optical component 31 into an integral structure, when assembling the near-eye optical system, the installation of the second imaging element 3 can be completed by placing it once.

In one example, referring to FIG3 , the optical component 31 is composed of the first liquid crystal film 311 and the beam splitter film 313, and the beam splitter film 313 is arranged on the surface of the first lens 32 close to the first imaging element 2 (i.e., the first surface 321 shown in FIG1 ), and the first liquid crystal film 311 is arranged on the surface of the first lens 32 away from the first imaging element 2 (i.e., the second surface 322 shown in FIG1 ). Based on this optical structure, right-handed circularly polarized light is incident on the second imaging element 3, is transmitted through the first liquid crystal film 311, is reflected through the beam splitter film 313, becomes left-handed circularly polarized light, is reflected through the first liquid crystal film 311, becomes right-handed circularly polarized light, and then is transmitted through the beam splitter film 313 and the second surface 322 of the first lens 32, and enters the aperture 01 for imaging.

It should be noted that the arrangement order of the first liquid crystal film 311 and the light splitting film 313 is not limited in the present application. Referring to FIG. 3 , the first liquid crystal film 311 and the light splitting film 313 can be arranged in sequence between the first imaging element and the aperture 01 . Of course, they can also be interchanged. The positions of the first liquid crystal film 311 and the dichroic film 313 .

For example, the first liquid crystal film 311 is disposed on a surface of the first lens 32 close to the first imaging element 2 , and the light-splitting film 313 is disposed on a surface of the first lens 32 close to the first imaging element 2 .

Alternatively, the dichroic film 313 is disposed on a surface of the first lens 32 close to the first imaging element 2 , and the first liquid crystal film 311 is disposed on a surface of the first lens 32 close to the first imaging element 2 .

Of course, when the first liquid crystal film 311 and the light-splitting film 313 are stacked, the stacking order of the two is not limited.

14 , when the second liquid crystal film 312 is introduced into the optical component 31, the second liquid crystal film 312 can realize the selective reflection and transmission of circularly polarized light without changing the rotation direction of the circularly polarized light, which can further improve the optical performance. On this basis, the optical component 31 is composed of the second liquid crystal film 312 and the beam splitter film 313.

As a more preferred solution, referring to FIG. 14 , the second liquid crystal film 312 can be disposed on the surface of the first lens 32 away from the first imaging element 2, and the beam splitter film 313 can be disposed on the surface of the first lens 32 close to the first imaging element 2. In this case, the second liquid crystal film 312 near the aperture 01 does not change the handedness of the reflected circularly polarized light, and the circularly polarized light maintains the handedness and is emitted to the aperture 01 for imaging, which can improve the imaging quality.

In some examples of the present application, referring to FIG. 13 , the optical component 31 is composed of a first liquid crystal film 311 and a second liquid crystal film 312 , wherein the second liquid crystal film 312 is located on a side of the first liquid crystal film 311 away from the first imaging element 2 .

According to the above example, the optical component 31 may not use the beam splitter film 313, but two liquid crystal films, that is, the optical component 31 is composed of the first liquid crystal film 311 and the second liquid crystal film 312, wherein the second liquid crystal film 312 is located on the side closer to the aperture 01 than the first liquid crystal film 311. This design allows the second liquid crystal film 312 on the side closer to the aperture 01 to not change the handedness of the circularly polarized light when reflecting the circularly polarized light, so that the imaging quality is better.

In some examples of the present application, the second imaging element 3 includes a first lens 32; the first liquid crystal film 311 and the second liquid crystal film 312 are disposed on two surfaces of the first lens 32; or the first liquid crystal film 311 and the second liquid crystal film 312 are stacked and arranged Placed on any surface of the first lens 32.

According to the above example, a lens, namely the above-mentioned first lens 32, is used in the second imaging element 3. The first lens 32 can support the optical component 31 and can also realize optical imaging, eliminate chromatic aberration, etc., thereby improving the optical imaging effect.

In the above example, the optical component 31 is directly arranged on the first lens 32, and there is no need to introduce an additional flat support to support the optical component 31, so that the optical structure can be simplified. In particular, by forming the first lens 32 and the optical component 31 into an integral structure, when assembling the near-eye optical system, the installation of the second imaging element 3 can be completed by placing it once.

In one example, referring to FIG. 13 , the optical component 31 is composed of the first liquid crystal film 311 and the second liquid crystal film 312, and the first liquid crystal film 311 is arranged on the surface of the first lens 32 close to the first imaging element 2 (i.e., the first surface 321 shown in FIG. 1 ), and the second liquid crystal film 312 is arranged on the surface of the first lens 32 away from the first imaging element 2 (i.e., the second surface 322 shown in FIG. 1 ). Based on this optical structure, right-handed circularly polarized light is incident on the second imaging element 3, is transmitted through the first liquid crystal film 311, is reflected through the second liquid crystal film 312, and is still right-handed circularly polarized light. After being reflected through the first liquid crystal film 311, it becomes left-handed circularly polarized light, and then is transmitted through the second liquid crystal film 312 and the second surface 322 of the first lens 32, and enters the aperture 01 to form an image.

In some examples of the present application, referring to FIG. 1 , the near-eye optical system further includes a display 1, which is located on a side of the first imaging element 2 away from the second imaging element 3; the display 1 is capable of emitting light for imaging display; wherein the light projected onto the first imaging element 2 is linearly polarized light.

In the near-eye display system, the display 1 can, for example, emit light of multiple different wavelength bands, and ultimately form a color image at the position of the aperture 01 .

The display 1 can directly project linearly polarized light. Of course, a linearly polarized light conversion element can also be provided on the light-emitting surface of the display 1 so that the light emitted by the display 1 is linearly polarized light.

In some examples of the present application, referring to FIG. 2 , the polarized reflective element 21 and the phase retarder 22 are stacked to form a superimposed element, and the superimposed element is located between the display 1 and the second imaging element 3 .

In the near-eye optical system provided by the embodiment of the present application, no optical lens may be used in the first imaging element 2. In this case, in order to facilitate the installation of the polarized reflection element 21 and the phase retarder 22, the polarized reflection element 21 and the phase retarder 22 may be combined together and introduced between the display 1 and the second imaging element 3 through a support. The polarized reflection element 21 and the phase retarder 22 are superimposed and arranged to form an integral part. With such a design, when assembling the near-eye optical system, the installation of the polarized reflection element 21 and the phase retarder 22 can be completed by placing them once.

In some examples of the present application, the superimposed element is disposed on the light emitting surface of the display 1 .

Since no optical lens may be used in the first imaging element 2, in order to facilitate the arrangement of the polarized reflection element 21 and the phase retarder 22, in addition to combining the polarized reflection element 21 and the phase retarder 22 together, the superimposed element formed by the polarized reflection element 21 and the phase retarder 22 may be directly arranged on the light-emitting surface of the display 1. In this way, the introduction of additional supporting members can be omitted, and the optical path structure can be further simplified.

In some examples of the present application, referring to FIG. 8 , the first imaging element 2 further includes a second lens 23 , and the second lens 23 is located between the display 1 and the second imaging element 3 , and the overlapping element is disposed on any surface of the second lens 23 .

After the lens is introduced into the first imaging element 2, the superimposed element composed of the polarized reflection element 21 and the phase retarder 22 can be arranged on the introduced lens. Using a lens in the first imaging element 2 is beneficial to improving the imaging quality and reducing the total optical length.

In some examples of the present application, referring to FIG8 , the overlapping element is disposed on the surface of the second lens 23 close to the display 1. The surface of the first lens 32 away from the display 1 and the surface of the second lens 23 close to the display 1 are glued or close to each other.

According to the optical architecture provided in the above example, the second lens 23 in the first imaging element 2 and the first lens 32 in the second imaging element 3 are close to each other or directly glued together, and the overall optical structure is compact, which is conducive to the lightweight design of the system.

In some examples of the present application, the total optical length TTL of the near-eye optical system is ≤15 mm.

The thickness of the optical system used in current VR devices is greater than 15mm, which is a certain distance from the glasses. However, the total optical length of the near-eye optical system provided by the embodiment of the present application can be no more than 15mm, which reduces the thickness of the system while ensuring high-definition imaging. The thickness refers to the dimension of the near-eye optical system along the optical axis.

In some examples of the present application, the inverse of the radius a of the surface through which the light passes the most times and the total focal length f of the near-eye optical system satisfy: -1＜a/f＜0; wherein the surface of the first lens 32 close to the display 1 is the surface through which the light passes the most times in the near-eye optical system.

The surface of the first lens 32 close to the display 1 is the first surface 321. Through the optical parameter constraints in the above example, the angle of the light incident on the first surface 321 can be as small as possible, which is beneficial to improving image quality.

The near-eye optical system provided according to an embodiment of the present application includes at least one lens, see the first lens 32 shown in FIG. 1 .

Optionally, the optical lenses included in the near-eye optical system use a material with a refractive index n in the range of 1.4<n<2.0 and a dispersion coefficient v in the range of 20<v<75.

In one example, the refractive index _n1 of the first lens 32 is 1.54, and the dispersion coefficient _v1 is 55.7.

The center thickness _T1 of the first lens 32 is: _{1mm≤T1≤14mm} . The first lens 3 comprises two optical surfaces, namely a first surface 321 close to the display 1 and a second surface 322 far from the display 1. The first surface 321 and the second surface 322 are aspherical or flat surfaces.

Example 1

1 to 3 , the near-eye optical system includes a display 1, a first imaging element 2, and a second imaging element 3 which are sequentially arranged along the same optical axis;

The first imaging element 2 includes a polarized reflection element 21 and a phase retarder 22, and the polarized reflection element 21 and the phase retarder 22 are stacked on the light emitting surface of the display 1;

The second imaging element 3 includes a first lens 32 and an optical component 31 . The optical component 31 includes a first liquid crystal film 311 and a dichroic film 313 . The first liquid crystal film 311 is disposed on a first surface 321 of the first lens 32 . The dichroic film 313 is disposed on a second surface 322 of the first lens 32 .

Table 1 shows the optical parameters of the near-eye optical system, which are as follows.

Table 1

The optical performance of the near-eye optical system provided in the above-mentioned embodiment 1 can be shown in Figures 4 to 7: Figure 4 is a schematic diagram of the point arrangement diagram of the near-eye optical system, Figure 5 is an MTF curve diagram of the near-eye optical system, Figure 6 is a field curvature distortion diagram of the near-eye optical system, and Figure 7 is a vertical axis chromatic aberration diagram of the near-eye optical system.

The spot diagram refers to a diffuse diagram formed by many light rays emitted from a point after passing through the near-eye optical system. Due to aberration, the intersection points of the light rays with the image plane are no longer concentrated at the same point, but are scattered in a certain range. It can be used to evaluate the imaging quality of the near-eye optical system. As shown in FIG4 , the maximum value of the image point in the spot diagram is less than 4 μm.

The MTF curve is a modulation transfer function graph that characterizes the imaging clarity of the near-eye optical system through the contrast of black and white line pairs. As shown in Figure 5, the center MTF is >0.2 at 30lp/mm, and the image is clear.

As shown in FIG6 , the maximum distortion occurs in 1 field of view, and the absolute value is less than 30%.

Vertical axis chromatic aberration is also called magnification chromatic aberration, which mainly refers to the difference in the focal position of blue light and red light on the image plane, because a principal ray of complex color on the object side becomes multiple rays when it is emitted on the image side due to the dispersion of the refraction system. As shown in Figure 7, the maximum chromatic aberration value of the near-eye optical system is less than 220μm.

Example 2

Referring to FIG8 , the difference between this embodiment 2 and the above-mentioned embodiment 1 is that:

A second lens 23 is introduced into the first imaging element 2 , and the polarizing reflection element 21 and the phase retarder 22 are stacked on a third surface 231 of the second lens 23 .

Table 2 shows the optical parameters of the near-eye optical system, which are as follows.

Table 2

The optical performance of the near-eye optical system provided in this embodiment 2 can be shown in Figures 9 to 12: Figure 9 is a schematic diagram of a point array of the near-eye optical system, Figure 10 is a MTF curve of the near-eye optical system, Figure 11 is a field curvature distortion diagram of the near-eye optical system, and Figure 12 is a vertical axis chromatic aberration diagram of the near-eye optical system. Difference picture.

The spot diagram refers to a diffuse diagram formed by the intersection of many light rays emitted from a point and the image plane after passing through the near-eye optical system, which is no longer concentrated at the same point due to aberration, but is spread over a certain range. It can be used to evaluate the imaging quality of the near-eye optical system. As shown in FIG9 , the maximum value of the image point in the spot diagram is less than 2 μm.

The MTF curve is a modulation transfer function graph that characterizes the imaging clarity of the near-eye optical system through the contrast of black and white line pairs. As shown in Figure 10, the center MTF is >0.8 at 30lp/mm, and the image is clear.

As shown in FIG11 , the maximum distortion occurs in 1 field of view, and the absolute value is less than 30%.

Vertical axis chromatic aberration is also called magnification chromatic aberration, which mainly refers to the difference between the focal positions of blue light and red light on the image plane, when a complex main light on the object side becomes multiple light rays due to the dispersion of the refraction system when it is emitted on the image side. As shown in Figure 12, the maximum chromatic aberration value of the near-eye optical system is less than 220μm.

According to another embodiment of the present application, a head-mounted display device is provided.

The head mounted display device comprises a housing and the near-eye optical system as described above.

Among them, the head-mounted display device can be in the form of VR glasses or VR helmets, which is not limited in the embodiments of the present application.

The specific implementation of the head-mounted display device of the embodiment of the present application can refer to the above-mentioned embodiments of the near-eye optical system, so it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here one by one.

The above embodiments focus on the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. Considering the simplicity of the text, they will not be repeated here.

Although some specific embodiments of the present application have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are only for illustration, not for limiting the scope of the present application. It should be understood by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims (15)

A near-eye optical system, characterized in that it comprises a first imaging element (2) and a second imaging element (3) arranged along the same optical axis; The first imaging element (2) comprises a polarized reflection element (21) and a phase retarder (22); The second imaging element (3) comprises at least one lens and at least one optical component (31), wherein the optical component (31) is configured to selectively reflect and transmit circularly polarized light. The near-eye optical system according to claim 1, characterized in that the first imaging element (2) and the second imaging element (3) are used to make the number of refracted light in the optical path be ≥2; The light can be refracted once in one of the optical components (31). The near-eye optical system according to claim 1, characterized in that the optical component (31) comprises at least one of a first liquid crystal film (311) and a second liquid crystal film (312); The second liquid crystal film (312) is configured such that when reflecting circularly polarized light, the rotation direction of the circularly polarized light does not change. The near-eye optical system according to claim 3, characterized in that the optical component (31) includes any one of the first liquid crystal film (311) and the second liquid crystal film (312), and the optical component (31) further includes a beam splitter film (313). The near-eye optical system according to claim 4, characterized in that the second imaging element (3) comprises a first lens (32); Any one of the first liquid crystal film (311) and the second liquid crystal film (312), and the light-splitting film (313) are respectively arranged on two surfaces of the first lens (32); or, Any one of the first liquid crystal film (311) and the second liquid crystal film (312) is stacked with the light splitting film (313) and is arranged on any surface of the first lens (32). The near-eye optical system according to claim 3, characterized in that the optical component (31) consists of the first liquid crystal film (311) and the second liquid crystal film (312), wherein the second liquid crystal film (312) is located on a side of the first liquid crystal film (311) facing away from the first imaging element (2). The near-eye optical system according to claim 6, characterized in that the second imaging element (3) comprises a first lens (32); The first liquid crystal film (311) and the second liquid crystal film (312) are respectively arranged on two surfaces of the first lens (32); or, The first liquid crystal film (311) and the second liquid crystal film (312) are stacked and arranged on any surface of the first lens (32). The near-eye optical system according to claim 5 or 7, characterized in that the near-eye optical system further comprises a display (1), wherein the display (1) is located on a side of the first imaging element (2) facing away from the second imaging element (3); The display (1) is capable of emitting light for imaging display; wherein the light projected onto the first imaging element (2) is linearly polarized light. The near-eye optical system according to claim 8, characterized in that the polarized reflective element (21) and the phase retarder (22) are stacked to form a superimposed element, and the superimposed element is located between the display (1) and the second imaging element (3). The near-eye optical system according to claim 9, characterized in that the overlapping element is arranged on the light-emitting surface of the display (1). The near-eye optical system according to claim 9, characterized in that the first imaging element (2) further comprises a second lens (23), and the second lens (23) is located on the display (1) and the second imaging element (3), the superimposed element is arranged on any surface of the second lens (23). The near-eye optical system according to claim 11, characterized in that the overlapping element is arranged on a surface of the second lens (23) close to the display (1); Wherein, the surface of the first lens (32) away from the display (1) and the surface of the second lens (23) close to the display (1) are glued together or close to each other. The near-eye optical system according to claim 8, characterized in that the total optical length TTL of the near-eye optical system is ≤15 mm. The near-eye optical system according to claim 8, characterized in that the reciprocal a of the radius of the surface through which the light passes the most times and the total focal length f of the near-eye optical system satisfy the following relationship: -1＜a/f＜0; The surface of the first lens (32) close to the display (1) is the surface through which light passes most times in the near-eye optical system. A head mounted display device, comprising: a housing; and A near-eye optical system as claimed in any one of claims 1 to 14.