Near-eye optical system and head-worn display device

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 systems and head-mounted display devices Technical Field

[0001] 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

[0002] Currently, VR device optical solutions are relatively thick. For example, VR glasses differ from conventional eyewear, making them uncomfortable to wear, especially after extended periods of wear. Minimizing the thickness of the optical system within VR devices (along the optical axis) while ensuring high-definition imaging is a challenge.

[0003] Summary of the Invention

[0004] 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.

[0005] In a first aspect, the present application provides a near-eye optical system. The near-eye optical system includes a first imaging element and a second imaging element arranged along the same optical axis;

[0006] The first imaging element includes a polarization reflection element and a phase retarder;

[0007] 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.

[0008] Optionally, the first imaging element and the second imaging element are used to make the number of folds of the light in the optical path be ≥2;

[0009] The light can be refracted once in one of the optical components.

[0010] Optionally, the optical component includes at least one of a first liquid crystal film and a second liquid crystal film;

[0011] 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.

[0012] Optionally, the optical component includes any one of the first liquid crystal film and the second liquid crystal film, and the optical component further includes a dichroic film.

[0013] Optionally, the second imaging element includes a first lens;

[0014] Any one of the first liquid crystal film and the second liquid crystal film, and the beam splitting film are respectively provided on two surfaces of the first lens;

[0015] or,

[0016] Any one of the first liquid crystal film and the second liquid crystal film is stacked with the dichroic film and is disposed on any surface of the first lens.

[0017] 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.

[0018] Optionally, the second imaging element includes a first lens;

[0019] The first liquid crystal film and the second liquid crystal film are respectively arranged on two surfaces of the first lens;

[0020] or,

[0021] The first liquid crystal film and the second liquid crystal film are stacked and arranged on any surface of the first lens.

[0022] Optionally, the near-eye optical system further comprises a display, wherein the display is located on a side of the first imaging element facing away from the second imaging element;

[0023] The display can emit light for imaging display; wherein the light projected onto the first imaging element is linearly polarized light.

[0024] 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.

[0025] Optionally, the superimposed element is arranged on the light-emitting surface of the display.

[0026] 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.

[0027] Optionally, the overlapping element is provided on a surface of the second lens close to the display;

[0028] The surface of the first lens away from the display and the surface of the second lens close to the display are glued together or close to each other.

[0029] Optionally, the total optical length TTL of the near-eye optical system is ≤15 mm.

[0030] Optionally, 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;

[0031] The surface of the first lens close to the display is the surface through which light passes the most times in the near-eye optical system.

[0032] In a second aspect, the present application provides a head-mounted display device. The head-mounted display device includes:

[0033] a housing; and

[0034] The near-eye optical system as described in the first aspect.

[0035] The beneficial effects of this application are:

[0036] 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 (along the optical axis) is effectively reduced, thereby facilitating the realization of ultra-thin VR optical solutions.

[0037] 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

[0038] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the specification and, together with the description, serve to explain the principles of the specification.

[0039] FIG1 is a schematic diagram of a near-eye optical system according to an embodiment of the present invention;

[0040] FIG2 is a schematic diagram of the arrangement positions of an optical component, a phase retarder, and a polarizing reflective element provided in an embodiment of the present application;

[0041] FIG3 is a diagram of an optical path propagation path of a near-eye optical system provided in an embodiment of the present application;

[0042] FIG4 is a point array diagram of the near-eye optical system provided in FIG1 ;

[0043] FIG5 is a diagram of the modulation transfer function (MTF) of the near-eye optical system provided in FIG1 ;

[0044] FIG6 is a diagram of field curvature and distortion of the near-eye optical system provided in FIG1 ;

[0045] FIG7 is a diagram of vertical chromatic aberration of the near-eye optical system provided in FIG1 ;

[0046] FIG8 is a second structural diagram of the near-eye optical system provided in an embodiment of the present application;

[0047] FIG9 is a point array diagram of the near-eye optical system provided in FIG8 ;

[0048] FIG10 is a diagram of the modulation transfer function (MTF) of the near-eye optical system provided in FIG8 ;

[0049] FIG11 is a diagram of field curvature and distortion of the near-eye optical system provided in FIG8 ;

[0050] FIG12 is a diagram of vertical chromatic aberration of the near-eye optical system provided in FIG8 ;

[0051] FIG13 is another optical path diagram of the near-eye optical system provided by an embodiment of the present application;

[0052] FIG14 is another optical path propagation diagram of the near-eye optical system provided in an embodiment of the present application.

[0053] Description of reference numerals:

[0054] 01. Aperture; 1. Display; 2. First imaging element; 3. Second imaging element;

[0055] 21. Polarized reflective element; 22. Phase retarder; 23. Second lens; 231. Third surface; 232. Fourth surface;

[0056] 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

[0057] 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 arrangements of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application.

[0058] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present disclosure, its application, or uses.

[0059] 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.

[0060] 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.

[0061] It should be noted that like reference numerals and letters refer to like items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0062] The near-eye optical system and head-mounted display device provided in the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0063] According to one aspect of an embodiment of the present application, a near-eye optical system is provided. The near-eye optical system is suitable for use in a virtual reality display device, such as a VR head-mounted display device. Specifically, the VR head-mounted display device may be in the form of VR smart glasses or a VR smart helmet, etc., but the embodiments of the present application do not limit the specific form of the head-mounted display device.

[0064] The near-eye optical system proposed in an embodiment of the present application, as shown in FIG1 , includes a first imaging element 2 and a second imaging element 3 arranged sequentially along the same optical axis. The first imaging element 2 includes a polarizing reflective element 21 and a phase retarder 22. The second imaging element 3 includes 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.

[0065] The near-eye optical system provided by the above embodiment, in terms of its optical architecture, includes a first imaging element 2 and a second imaging element 3 arranged along the same optical axis. For example, the first imaging element 2 is located near the screen, and the second imaging element 3 is located near the aperture 01. The first imaging element 2 may not require a lens, while the second imaging element 3 may only require a single lens (see Figure 1). In other words, the entire near-eye optical system can utilize at least one lens, while still meeting the requirements of high-definition imaging. Since the number of lenses can be as low as one, this helps reduce the weight and volume of the entire near-eye display system.

[0066] According to the near-eye optical system provided in the above-mentioned embodiment of the present application, an optical component 31 is introduced into the second imaging element 3. Based on the principle of light polarization, the specially designed optical component 31 is combined with the polarizing reflective element 21 and phase retarder 22 located near the screen to form a new reentrant optical architecture. This can effectively reduce the thickness of the entire near-eye optical system (along the optical axis) while ensuring high-definition imaging, thereby facilitating the implementation of ultra-thin VR optical solutions.

[0067] The phase retarder 22 is, for example, a quarter-wave plate.

[0068] Of course, the phase retarder 22 can also be configured as other phase retarder plates, such as a half-wave plate, as needed.

[0069] 1 and 3 , the phase retarder 22 is located in the first imaging element 2 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 vice versa.

[0070] 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, as shown in Figure 3. The optical component 31 in the second imaging element 3 can directly process the circularly polarized light.

[0071] The polarized reflective element 21 is, for example, a linear polarizer, which is a polarizer that reflects horizontal linear polarized light and transmits vertical linear polarized light, or a polarizer that reflects linear polarized light at any other specific angle and transmits linear polarized light perpendicular to the angle.

[0072] According to the near-eye optical system provided by the embodiment of the present application, the polarized reflective element 21 and the phase retarder 22 provided on the near-screen side can make the light incident on the second imaging element 3 circularly polarized light. 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 this optical structure, 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 ultra-thin design of the near-eye optical system. The light undergoes multiple folds between the first imaging element 2 and the second imaging element 3, which is conducive to clear imaging.

[0073] Of course, in practical applications, two or more lenses can be used in the near-eye optical system as needed.

[0074] For example, two lenses can be used in the near-eye optical system, see Figure 8, and an additional lens can be set in the first imaging element 2, which can be used to support the polarization reflection element 21 and the phase retarder 22, for example.

[0075] It should be noted that for near-eye optical systems, the imaging effect can be improved as the number of lenses used increases, but this may increase the weight and production cost of the near-eye optical system.

[0076] As a preferred solution of the present application, 1 to 2 lenses can be used in the near-eye optical system.

[0077] 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 folded once in one of the optical components 31 .

[0078] 1 and 3 , the polarization reflection 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.

[0079] The polarized reflective 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. Thus, light used for imaging and 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, it is finally emitted from the second imaging element 3, forming a clear image at the aperture 01.

[0080] Specifically, the light used for imaging and display undergoes two folds between the polarizing reflective element 21, the phase retarder 22, and the optical component 31. Referring to Figure 3, on the side near the screen, horizontally polarized light passes through the polarizing reflective element 21 and then strikes the phase retarder 22. The phase retarder 22 converts the horizontally polarized light into left-handed circularly polarized light. The left-handed circularly polarized light is then reflected by the optical component 31 and converted into right-handed circularly polarized light. The right-handed circularly polarized light then passes through the phase retarder 22 and becomes vertically polarized light. The vertically polarized light then reflects from the polarizing reflective element 21 to the phase retarder 22 and becomes right-handed circularly polarized light. This represents the first fold of the light. The right-handed circularly polarized light then enters the second imaging element 3, where it undergoes a second fold by the optical component 31. Finally, the light exits the second imaging element 3 and enters the aperture 01 to form an image.

[0081] 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, thereby improving imaging clarity.

[0082] 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.

[0083] In some examples of the present application, referring to FIG3 , FIG13 , and FIG14 , 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.

[0084] According to the above example, the first liquid crystal film 311 and the second liquid crystal film 312 are different. After reflecting circularly polarized light, the first liquid crystal film 311 changes the handedness of the circularly polarized light, for example, converting left-handed circularly polarized light into right-handed circularly polarized light, or vice versa. However, after reflecting circularly polarized light, the second liquid crystal film 312 does not change the handedness of the circularly polarized light. For example, left-handed circularly polarized light remains left-handed circularly polarized light after reflection, and right-handed circularly polarized light remains right-handed circularly polarized light after reflection.

[0085] 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.

[0086] 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 same effect.

[0087] In some examples of the present application, referring to FIG. 3 and FIG. 14 , the optical component 31 includes either the first liquid crystal film 311 or the second liquid crystal film 312 , and the optical component 31 further includes a dichroic film 313 .

[0088] 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 circularly polarized light.

[0089] In some examples of the present application, referring to Figures 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 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 and the dichroic film 313 are stacked and arranged on any surface of the first lens 32.

[0090] 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 at the same time can realize optical imaging, eliminate chromatic aberration, etc., thereby improving the optical imaging effect.

[0091] In the above example, the optical assembly 31 is directly mounted on the first lens 32, eliminating the need for a separate flat support member to support the optical assembly 31. This simplifies the optical structure. In particular, by integrating the first lens 32 and the optical assembly 31 into a single structure, the second imaging element 3 can be installed in a single placement during assembly of the near-eye optical system.

[0092] In one example, referring to FIG3 , the optical assembly 31 is composed of the first liquid crystal film 311 and the bezel 313. The bezel 313 is disposed on the surface of the first lens 32 closest to the first imaging element 2 (i.e., the first surface 321 shown in FIG1 ), while the first liquid crystal film 311 is disposed on the surface of the first lens 32 further away from the first imaging element 2 (i.e., the second surface 322 shown in FIG1 ). Based on this optical architecture, right-handed circularly polarized light is incident on the second imaging element 3, is transmitted through the first liquid crystal film 311, and is reflected by the bezel 313 to become left-handed circularly polarized light. After being reflected by the first liquid crystal film 311, it becomes right-handed circularly polarized light. It then passes through the bezel 313 and the second surface 322 of the first lens 32, and enters the aperture 01 to form an image.

[0093] It should be noted that the present application does not impose any restrictions on the order in which the first liquid crystal film 311 and the bezel 313 are disposed. Referring to FIG3 , the first liquid crystal film 311 and the bezel 313 can be disposed sequentially between the first imaging element and the aperture 01. Of course, the positions of the first liquid crystal film 311 and the bezel 313 can also be interchanged.

[0094] 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 dichroic film 313 is disposed on a surface of the first lens 32 close to the first imaging element 2 .

[0095] 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 .

[0096] Of course, when the first liquid crystal film 311 and the dichroic film 313 are stacked, the stacking order of the two is not limited.

[0097] As shown in Figure 14 , when the second liquid crystal film 312 is incorporated into the optical assembly 31, it can selectively reflect and transmit circularly polarized light without changing the handedness of the circularly polarized light, further improving optical performance. Based on this, the optical assembly 31 is comprised of the second liquid crystal film 312 and the beam splitter film 313.

[0098] As a preferred solution, referring to FIG14 , the second liquid crystal film 312 can be disposed on the surface of the first lens 32 away from the first imaging element 2. In this case, the dichroic film 313 can be disposed on the surface of the first lens 32 closer 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. The circularly polarized light maintains its handedness when emitted to the aperture 01 for imaging, thereby improving imaging quality.

[0099] 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 .

[0100] According to the above example, the optical assembly 31 can be constructed without the use of the dichroic film 313. Instead, two liquid crystal films can be used. Specifically, the optical assembly 31 is composed of a first liquid crystal film 311 and a second liquid crystal film 312. The second liquid crystal film 312 is located closer to the aperture 01 than the first liquid crystal film 311. This design ensures that the second liquid crystal film 312, located closer to the aperture 01, does not change the handedness of circularly polarized light when reflecting it, thereby improving image quality.

[0101] 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 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.

[0102] 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 at the same time can realize optical imaging, eliminate chromatic aberration, etc., thereby improving the optical imaging effect.

[0103] In the above example, the optical assembly 31 is directly mounted on the first lens 32, eliminating the need for a separate flat support member to support the optical assembly 31. This simplifies the optical structure. In particular, by integrating the first lens 32 and the optical assembly 31 into a single structure, the second imaging element 3 can be installed in a single placement during assembly of the near-eye optical system.

[0104] In one example, referring to FIG13 , the optical assembly 31 is composed of a first liquid crystal film 311 and a second liquid crystal film 312. The first liquid crystal film 311 is disposed on the surface of the first lens 32 closest to the first imaging element 2 (i.e., the first surface 321 shown in FIG1 ), and the second liquid crystal film 312 is disposed on the surface of the first lens 32 further away from the first imaging element 2 (i.e., the second surface 322 shown in FIG1 ). Based on this optical architecture, right-handed circularly polarized light is incident on the second imaging element 3, is transmitted through the first liquid crystal film 311, and is reflected by the second liquid crystal film 312, remaining right-handed circularly polarized light. After reflection from the first liquid crystal film 311, it becomes left-handed circularly polarized light. It then passes through the second liquid crystal film 312 and the second surface 322 of the first lens 32, entering the aperture 01 to form an image.

[0105] In some examples of the present application, referring to FIG1 , the near-eye optical system further includes a display 1, which is located on the 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.

[0106] 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 .

[0107] 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.

[0108] 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 .

[0109] In the near-eye optical system provided in an embodiment of the present application, the first imaging element 2 may not use any optical lenses. In this case, to facilitate the installation of the polarizing reflective element 21 and the phase retarder 22, the polarizing reflective element 21 and the phase retarder 22 may be combined together and introduced between the display 1 and the second imaging element 3 via a support member. The polarizing reflective element 21 and the phase retarder 22 are superimposed and arranged to form an integral component. With this design, when assembling the near-eye optical system, the polarizing reflective element 21 and the phase retarder 22 can be installed by placing them once.

[0110] In some examples of the present application, the superimposed element is disposed on the light-emitting surface of the display 1 .

[0111] Since the first imaging element 2 does not need to use any optical lenses, in order to facilitate the placement of the polarizing reflective element 21 and the phase retarder 22, in addition to combining the polarizing reflective element 21 and the phase retarder 22, the superimposed element formed by the polarizing reflective element 21 and the phase retarder 22 can also be directly placed on the light-emitting surface of the display 1. This eliminates the need for additional support components and further simplifies the optical path structure.

[0112] In some examples of the present application, referring to FIG8 , 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 provided on any surface of the second lens 23 .

[0113] When a lens is introduced into the first imaging element 2, a superimposed element consisting of the polarizing reflective element 21 and the phase retarder 22 can be placed on the introduced lens. Using a lens in the first imaging element 2 is beneficial to improving imaging quality and reducing the total optical length.

[0114] In some examples of the present application, referring to FIG8 , the overlapping element is provided 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.

[0115] According to the optical structure provided by 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.

[0116] In some examples of the present application, the total optical length TTL of the near-eye optical system is ≤15 mm.

[0117] The thickness of the optical systems used in current VR devices is greater than 15mm, which is a significant gap from the form factor of glasses. However, the near-eye optical system provided in the embodiments of the present application can have a total optical length of no more than 15mm, achieving a reduction in system thickness while ensuring high-definition imaging. The thickness refers to the dimension of the near-eye optical system along the optical axis.

[0118] In some examples of the present application, 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: -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.

[0119] , 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 made as small as possible, which is beneficial to improving the image quality.

[0120] According to the near-eye optical system provided by the embodiment of the present application, it includes at least one lens, see the first lens 32 shown in FIG. 1.

[0121] Optionally, the refractive index n of the material used for the optical lens included in the near-eye optical system ranges from 1.4 < n < 2.0, and the dispersion coefficient v ranges from 20 < v < 75.

[0122] In one example, the refractive index n1 of the first lens 32 is 1.54, and the dispersion coefficient v1 is 55.7.

[0123] Among them, the central thickness T1 of the first lens 32 is: 1 mm ≤ T1 ≤ 14 mm. The first lens 3 includes two optical surfaces, that is, the first surface 321 close to the display 1 and the second surface 322 far from the display 1. The first surface 321 and the second surface 322 are aspherical or flat surfaces.

[0124] Embodiment 1

[0125] Referring to FIGS. 1 to 3, the near-eye optical system includes a display 1, a first imaging element 2, and a second imaging element 3 arranged in sequence along the same optical axis;

[0126] The first imaging element 2 includes a polarization reflection element 21 and a phase retarder 22, and the polarization reflection element 21 and the phase retarder 22 are stacked on the light-emitting surface of the display 1;

[0127] 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 beam splitting film 313. The first liquid crystal film 311 is disposed on the first surface 321 of the first lens 32, and the beam splitting film 313 is disposed on the second surface 322 of the first lens 32.

[0128] Table 1 shows the optical parameters of the near-eye optical system, which are specifically as follows.

[0129] Table 1

[0130] For the near-eye optical system provided in the above Embodiment 1, its optical performance can be as shown in FIGS. 4 to 7: FIG. 4 is a spot diagram schematic diagram of the near-eye optical system, FIG. 5 is a MTF curve diagram of the near-eye optical system, FIG. 6 is a field curvature and distortion diagram of the near-eye optical system, and FIG. 7 is a lateral chromatic aberration diagram of the near-eye optical system.

[0131] A spot diagram is a diffuse pattern formed when many light rays emitted from a single point, after passing through a near-eye optical system, intersect with the image plane due to aberrations, forming a pattern scattered over a certain range. This pattern can be used to evaluate the imaging quality of near-eye optical systems. As shown in Figure 4, the maximum image point size in this spot diagram is less than 4 μm.

[0132] The MTF curve, a modulation transfer function, measures the image clarity of a near-eye optical system by measuring the contrast between black and white line pairs. As shown in Figure 5, the center MTF is >0.2 at 30 lp / mm, indicating a clear image.

[0133] As shown in FIG6 , the maximum distortion occurs in 1 field of view, and the absolute value is less than 30%.

[0134] Vertical axial chromatic aberration, also known as chromatic aberration of magnification, primarily refers to the difference in the focal positions of blue and red light on the image plane, caused by the dispersion of a single, multi-colored principal ray on the object side. As shown in Figure 7, the maximum chromatic aberration in a near-eye optical system is less than 220μm.

[0135] Example 2

[0136] 8 , the difference between this embodiment 2 and the above-mentioned embodiment 1 is that:

[0137] 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 .

[0138] Table 2 shows the optical parameters of the near-eye optical system, which are as follows.

[0139] Table 2

[0140] 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 the point arrangement of the near-eye optical system, Figure 10 is an MTF curve diagram 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.

[0141] A spot diagram is a diffuse pattern formed when many light rays emitted from a single point, after passing through a near-eye optical system, intersect with the image plane due to aberrations, forming a pattern scattered over a certain range. This pattern can be used to evaluate the imaging quality of near-eye optical systems. As shown in Figure 9, the maximum image point size in this spot diagram is less than 2 μm.

[0142] The MTF curve, a modulation transfer function, measures the image clarity of a near-eye optical system by measuring the contrast between black and white line pairs. As shown in Figure 10, the center MTF is >0.8 at 30 lp / mm, indicating a clear image.

[0143] As shown in FIG11 , the maximum distortion occurs in 1 field of view, and the absolute value is less than 30%.

[0144] Vertical axial chromatic aberration, also known as chromatic aberration of magnification, primarily refers to the difference in the focal positions of blue and red light on the image plane, caused by the dispersion of a single, multi-colored principal ray on the object side. As shown in Figure 12, the maximum chromatic aberration in a near-eye optical system is less than 220μm.

[0145] According to another embodiment of the present application, a head-mounted display device is provided.

[0146] The head-mounted display device includes a housing and the near-eye optical system as described above.

[0147] 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.

[0148] 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, and therefore 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.

[0149] 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.

[0150] 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 for illustration only and are not intended to limit the scope of the present application. It should be understood by those skilled in the art that the above examples 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

1. 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.

2. 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 light path be ≥2; The light can be refracted once in one of the optical components (31).

3. The near-eye optical system according to claim 1, characterized in that: 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 such that when reflecting circularly polarized light, the rotation direction of the circularly polarized light does not change.

4. The near-eye optical system according to claim 3, characterized in that: The optical component (31) comprises any one of the first liquid crystal film (311) and the second liquid crystal film (312), and the optical component (31) further comprises a beam splitting film (313).

5. 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).

6. The near-eye optical system according to claim 3, characterized in that: 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 a side of the first liquid crystal film (311) away from the first imaging element (2).

7. 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).

8. 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.

9. The near-eye optical system according to claim 8, characterized in that: The polarized reflection 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).

10. The near-eye optical system according to claim 9, characterized in that: The superimposed element is arranged on the light-emitting surface of the display (1).

11. 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 between the display (1) and the second imaging element (3), and the overlapping element is arranged on any surface of the second lens (23).

12. 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.

13. 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.

14. The near-eye optical system according to claim 8, characterized in that: The reciprocal 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 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.

15. A head mounted display device, characterized in that: include: case; as well as A near-eye optical system as claimed in any one of claims 1 to 14.

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