Near-eye optical system and head-mounted display device

Abstract

The embodiment of the invention provides a near-eye optical system and head-mounted display equipment. The near-eye optical system comprises a polarization reflection element, a phase delayer and a light splitting element which are arranged along the same optical axis, and the phase delayer is located between the light splitting element and the polarization reflection element. The near-eye optical system further comprises a first optical element, the first optical element is located between the light splitting element and the phase retarder, the first optical element is a lens group, and the focal power of the first optical element is phi 1. The near-eye optical system meets the following conditions: 0.5 < = sin (arctan (D / (2 * T1))) * phi 1 * D < = 1.5; wherein the center interval between the light splitting element and the polarization reflection element is T1, and the maximum optical aperture of the near-eye optical system is D. According to the near-to-eye optical system provided by the embodiment of the invention, the size of the near-to-eye optical system can be reduced while a large view field is ensured.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of optical imaging technology, and more specifically, to a near-eye optical system and a head-mounted display device. Background Art

[0002] The core component of virtual reality technology (VR technology) is the optical system used internally, and the quality of its displayed images will directly determine the quality of VR equipment. In order to enhance the user's immersive experience, higher requirements are placed on the field of view (FOV) of the optical system in VR equipment, that is, the FOV should be increased as much as possible. However, under the condition of a certain eye distance, the larger the FOV, the larger the size of the optical system will be, that is, there is a problem that is difficult to balance between a large FOV and the size of the optical system. Summary of the invention

[0003] The purpose of this application is to provide a new technical solution for a near-eye optical system and a head-mounted display device.

[0004] In a first aspect, the present application provides a near-eye optical system. The near-eye optical system comprises a polarization reflection element, a phase retarder and a beam splitter arranged along the same optical axis, and the phase retarder is located between the beam splitter and the polarization reflection element;

[0005] The near-eye optical system further comprises a first optical element, the first optical element is located between the beam splitter and the phase retarder, the first optical element is a lens group, and the optical power of the first optical element is φ1;

[0006] The near-eye optical system satisfies: 0.5≤sin(arctan(D / (2*T1)))*φ1*D≤1.5; wherein the center interval between the beam splitting element and the polarized reflection element is T1, and the maximum optical aperture of the near-eye optical system is D.

[0007] Optionally, the near-eye optical system satisfies: 0.98≤sin(arctan(D / (2*T1)))*φ1*D≤1.4.

[0008] Optionally, the first optical element includes N lenses, and N≥2.

[0009] Optionally, the first optical element includes a first lens and a second lens;

[0010] The beam splitter is disposed on a surface of the second lens away from the first lens, and the phase retarder and the polarization reflection element are stacked and disposed on a surface of the first lens away from the second lens.

[0011] Optionally, a curvature radius of a surface of the first lens away from the second lens is R, and R<0.

[0012] Optionally, the total optical focal length of the near-eye optical system is φ, and the near-eye optical system also satisfies: abs(1 / (R*φ))≤2.

[0013] Optionally, the edge interval between the light splitting element and the polarized reflection element is T2, and T2 and T1 satisfy: 0<(T2-T1) / (T2+T1)≤1.

[0014] Optionally, the near-eye optical system further includes a display screen, which emits light for imaging display, and the display screen is located on a side of the beam splitting element away from the first optical element.

[0015] Optionally, the near-eye optical system further includes a second optical element, the second optical element is located between the display screen and the beam splitting element, the second optical element includes at least one lens, and the optical focal length of the second optical element is positive.

[0016] Optionally, the second optical element is a third lens, and the optical power of the third lens is positive.

[0017] Optionally, the optical power of the first optical element is positive, and 0.005≤φ1≤0.1.

[0018] Optionally, a polarizer is arranged on a side of the polarized reflective element away from the phase retarder; the phase retarder, the polarized reflective element and the polarizer are stacked to form a composite film material.

[0019] Optionally, the display screen is configured to emit circularly polarized light or natural light;

[0020] In the case that the light emitted by the display screen is natural light, the light-emitting surface of the display screen is further provided with a superimposed element for converting the natural light into circularly polarized light, and the superimposed element at least includes a phase delay plate and a linear polarizer.

[0021] In a second aspect, the present application provides a head mounted display device. The head mounted display device comprises:

[0022] a housing; and

[0023] A near-eye optical system as described in the first aspect.

[0024] The beneficial effects of this application are:

[0025] According to the near-eye optical system provided in the embodiment of the present application, on the optical architecture of the folded light path, by reasonably constraining the relationship between the center interval T1 between the splitter element and the polarized reflection element, the optical focal length φ1 of the lens group between the two optical elements and the maximum optical aperture D of the near-eye optical system, the size of the near-eye optical system can be reduced while ensuring a large field of view, especially the radial size of the near-eye optical system can be reduced, and at the same time, the near-eye optical system can also take into account high-definition imaging.

[0026] 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

[0027] 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.

[0028] Figure 1 One of the structural schematic diagrams of the near-eye optical system provided in an embodiment of the present application;

[0029] Figure 2 The second structural schematic diagram of the near-eye optical system provided in the embodiment of the present application;

[0030] Figure 3 A schematic diagram of the arrangement of the composite membrane material provided in the embodiment of the present application;

[0031] Figure 4 A dot array diagram of the near-eye optical system provided in Example 1 of the present application;

[0032] Figure 5 A modulation transfer function MTF curve diagram of the near-eye optical system provided in Example 1 of the present application;

[0033] Figure 6 Field curvature and distortion diagram of the near-eye optical system provided in Example 1 of the present application;

[0034] Figure 7 A vertical axis chromatic aberration diagram of the near-eye optical system provided in Example 1 of the present application;

[0035] Figure 8 The third structural schematic diagram of the near-eye optical system provided in the embodiment of the present application;

[0036] Fig. 9 A dot array diagram of a near-eye optical system provided in Example 2 of the present application;

[0037] Fig.10 A modulation transfer function MTF curve diagram of the near-eye optical system provided in Example 2 of the present application;

[0038] Fig.11 Field curvature and distortion diagram of the near-eye optical system provided in Example 2 of the present application;

[0039] Fig.12 A vertical axis chromatic aberration diagram of the near-eye optical system provided in Example 2 of the present application;

[0040] Fig.13 A fourth structural schematic diagram of the near-eye optical system provided in an embodiment of the present application;

[0041] Fig.14 A dot array diagram of a near-eye optical system provided in Example 3 of the present application;

[0042] Fig.15 A modulation transfer function MTF curve diagram of the near-eye optical system provided in Example 3 of the present application;

[0043] Fig.16 Field curvature and distortion diagram of the near-eye optical system provided in Example 3 of the present application;

[0044] Fig.17 This is a vertical axis chromatic aberration diagram of the near-eye optical system provided in Example 3 of the present application.

[0045] Description of reference numerals:

[0046] 1. Display screen; 2. Screen protection glass; 3. Third lens; 31. Fifth surface; 32. Sixth surface; 4. Second lens; 41. Third surface; 42. Fourth surface; 5. First lens; 51. First surface; 52. Second surface; 6. Beam splitter; 7. Phase retarder; 8. Polarized reflective element; 9. Polarizer; 01. Human eye. DETAILED DESCRIPTION

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] According to one aspect of an embodiment of the present application, a near-eye optical system is provided, and the near-eye optical system is applicable to a wearable device. The wearable device may be a head mounted display (HMD), such as a VR head mounted display. The VR head mounted display device includes, for example, VR smart glasses or a VR smart helmet, and the form of the head mounted display device is not specifically limited in the embodiment of the present application.

[0054] The near-eye optical system proposed in the embodiment of the present application, see Figure 1 and Figure 2 , the near-eye optical system includes a polarizing reflection element 8, a phase retarder 7 and a beam splitter 6 arranged along the same optical axis, and the phase retarder 7 is located between the beam splitter 6 and the polarizing reflection element 8. The near-eye optical system also includes a first optical element, which is located between the beam splitter 6 and the phase retarder 7, and the first optical element is a lens group, and the optical power of the first optical element is φ1. The near-eye optical system satisfies: 0.5≤sin(arctan(D / (2*T1)))*φ1*D≤1.5; wherein the center interval between the beam splitter 6 and the polarizing reflection element 8 is T1, and the maximum optical aperture of the near-eye optical system is D.

[0055] According to the near-eye optical system provided by the above embodiment of the present application, it includes a beam splitter 6, a first optical element, a phase retarder 7 and a polarized reflective element 8 arranged in sequence along the same optical axis, and these elements cooperate with the first optical element to form a folded optical path; wherein the first optical element is a lens group, which is located between the beam splitter 6 and the phase retarder 7, and can make the incident light return between the beam splitter 6 and the polarized reflective element 8, and finally emit to the human eye 01 for imaging. The use of a folded optical path can make the structure of the entire near-eye optical system more compact, while ensuring the image quality of the image.

[0056] In addition, the optical parameter design of the near-eye optical system provided in the embodiment of the present application satisfies the optical parameter constraint condition of 0.5≤sin(arctan(D / (2*T1)))*φ1*D≤1.5, wherein D is the maximum optical aperture of the near-eye optical system, T1 is the center interval between the beam splitting element 6 and the polarized reflective element 8, see Figure 2 , φ1 is the focal power of the first optical element, and the focal power φ1 is designed to be greater than 0. By reasonably constraining the above optical parameters of the near-eye optical system, the radial size of the near-eye optical system can be effectively reduced while ensuring a large field of view FOV, and high-definition imaging can also be achieved. In other words, the formed near-eye optical system meets the development trend of VR devices with large FOV, high definition and small size.

[0057] The above D value is the maximum optical aperture value of all lenses in the near-eye optical system, which can be expressed as optical half-aperture*2. The optical half-aperture of a lens refers to the radial dimension from the center of the lens to the edge of the optically effective area on the lens.

[0058] The near-eye optical system provided in the embodiment of the present application has a field of view FOV of up to 100° or even higher, which can provide users with a better immersive experience.

[0059] Compared with the traditional folded optical path solution, the near-eye optical system provided in the embodiment of the present application can reduce its size in the radial direction, and its radial size can be reduced by about 20%, that is, the radial volume of the near-eye optical system can be compressed, which is different from the traditional method of only reducing the volume along the optical axis. The near-eye optical system provided in the embodiment of the present application compresses the radial size. When it is assembled on the VR device, the radial size of the system is small, which can save space for setting the left and right eye pupil distance adjustment parts.

[0060] It should be noted that the focal power is the reciprocal of the focal length of the lens. For example, the focal power φ1 of the first optical element is the reciprocal of the focal length of the first optical element.

[0061] See also Figure 1 and Figure 2 In the near-eye optical system, the first optical element is, for example, close to the human eye 01. At this time, the first optical element includes an optical lens with a maximum radial size, which can converge light into the human eye 01 to the greatest extent.

[0062] The near-eye optical system provided in the embodiment of the present application can not only reduce the size of the system under a large field of view, but also achieve high-definition imaging. Figure 5 , Fig.10 and Fig.15 , the MTF of the near-eye optical system is >0.2 at 19lp / mm, indicating that the imaging clarity of the near-eye optical system is better.

[0063] According to the near-eye optical system provided by the embodiment of the present application, in the optical architecture of the folded optical path, see Figure 2By reasonably constraining the relationship among the center interval T1 between the beam splitter element 6 and the polarized reflective element 8, the focal length φ1 of the lens group between the two optical elements, and the maximum aperture D of the near-eye optical system, the size of the near-eye optical system can be reduced while ensuring a large field of view (such as FOV ≥ 100°), especially the radial size of the near-eye optical system can be reduced (the radial size can be reduced by 20%), while the near-eye optical system can also take into account high-definition imaging.

[0064] In the near-eye optical system provided in the embodiment of the present application, the beam splitter element 6 is configured to allow a portion of light to be transmitted and another portion of light to be reflected.

[0065] For example, the light splitting element 6 is a semi-transmissive and semi-reflective film.

[0066] It should be noted that the reflectivity and transmittance of the light splitting element 6 can be flexibly adjusted according to specific needs, and this is not limited in the embodiments of the present application.

[0067] In the near-eye optical system provided in the embodiment of the present application, the phase retarder 7 can be used to change the polarization state of light, specifically, it can be used to convert linearly polarized light into circularly polarized light, or to convert circularly polarized light into linearly polarized light.

[0068] For example, the phase retarder 7 is a quarter wave plate.

[0069] Of course, the phase retarder 7 can be set to other phase retarder plates, such as a half-wave plate, etc. as needed.

[0070] In the near-eye optical system provided in the embodiment of the present application, the polarized reflective element 8 is a polarized reflector that reflects horizontal linear polarized light and transmits vertical linear polarized light, or a polarized reflector that reflects linear polarized light at any other specific angle and transmits linear polarized light in a direction perpendicular to the angle.

[0071] In the embodiment of the present application, the phase retarder 7 and the polarized reflective element 8 cooperate with each other and can be used to analyze and transmit light.

[0072] In some examples of the present application, the near-eye optical system satisfies: 0.98≤sin(arctan(D / (2*T1)))*φ1*D≤1.4.

[0073] The maximum optical aperture D of the near-eye optical system is, for example, 28 mm ≤ D ≤ 34 mm.

[0074] The optical focal length φ1 of the first optical element is, for example, 0.005≤φ1≤0.1.

[0075] In some examples of the present application, the first optical element includes N lenses, and N≥2.

[0076] Based on the above example, see Figure 1 and Figure 2 At least two lenses are arranged between the beam splitter element 6 and the phase retarder 7. This design can reduce the axial size of the near-eye optical system to achieve a lightweight design of the near-eye optical system while ensuring image quality.

[0077] That is to say, the near-eye optical system provided in the embodiment of the present application has its dimensions compressed in the optical axis direction and radial direction, which can further reduce the volume and weight of the near-eye optical system, while at the same time ensuring a large field of view and high-definition imaging.

[0078] It should be noted that more than two lenses can be introduced between the beam splitter element 6 and the phase retarder 7. Properly increasing the number of lenses is conducive to further reducing the total length (dimension in the optical axis direction) of the near-eye optical system, but it may increase the weight and production cost of the system. In practical applications, the number of lenses between the beam splitter element 6 and the polarized reflective element 8 can be adjusted according to specific needs, but at least two lenses are required between the two elements.

[0079] In some examples of this application, see Figure 1 and Figure 2 , the first optical element includes a first lens 5 and a second lens 4. The beam splitter 6 is disposed on the surface of the second lens 4 away from the first lens 5, the phase retarder 7 and the polarization reflection element 8 are stacked and disposed on the surface of the first lens 5 away from the second lens 4, see Figure 3 .

[0080] According to the above example, the first optical element comprises two lenses, for example, Figure 1 and Figure 2 The two lenses are respectively a first lens 5 and a second lens 4. The first lens 5 is closer to the human eye 01 than the second lens 4. The phase retarder 7 and the polarized reflective element 8 can be glued to the surface of the first lens 5 close to the human eye 01, and the beam splitter 6 can be separately arranged on the surface of the second lens 4 far from the human eye 01. The beam splitter 6 can be arranged on the surface of the second lens 4 far from the human eye 01 by, for example, attachment or plating.

[0081] For example, see Figure 1The first lens 5 includes a first surface 51 and a second surface 52, the first surface 51 is far away from the human eye 01, and the second surface 52 is close to the human eye 01, and the phase retarder 7 and the polarization reflection element 8 are stacked in sequence on the second surface 52.

[0082] For example, see Figure 1 The second lens 4 includes a third surface 41 and a fourth surface 42 , the third surface 41 is far away from the human eye 01 , the fourth surface 42 is close to the human eye 01 , and a spectroscopic element 6 is arranged on the third surface 41 .

[0083] According to the above example, the second lens 4 is used to support the splitter element 6, and the first lens 5 is used to support the phase delay device 7 and the polarization reflection element 8, so that there is no need to introduce additional support members in the optical path to support these elements that form the folded optical path.

[0084] According to the above example, the sum of the thickness of the first lens 5 , the thickness of the second lens 4 and the air space between the two is the interval T1 between the light splitting element 6 and the polarized reflection element 8 .

[0085] Based on the above example, see Figure 1 The first optical element may be composed of a first lens 5 and a second lens 4, for example. Since the first optical element is close to the human eye 01, the optical apertures of the first lens 5 and the second lens 4 may be designed to be relatively large. For example, the optical apertures of the first lens 5 and the second lens 4 may be the same, and both are lenses with the largest optical aperture in the near-eye optical system. Of course, one of the first lens 5 and the second lens 4 may be the lens with the largest optical aperture in the near-eye optical system, and this is not limited in the present application.

[0086] In some examples of the present application, the curvature radius of the surface of the first lens 5 away from the second lens 4 is R, and R<0.

[0087] See also Figure 1 The curvature radius R of the second surface 52 of the first lens 5 close to the human eye 01 is negative. This design can reduce the aperture of the lens.

[0088] It should be noted that the first lens 5 is, for example, the first lens close to the human eye 01, and its aperture is usually relatively large. By reducing its aperture, the aperture sizes of other lenses in the optical path can be reduced accordingly, thereby helping to reduce the radial size and weight of the entire near-eye optical system.

[0089] In some examples of the present application, the total optical focal length of the near-eye optical system is φ, and the near-eye optical system also satisfies: abs(1 / (R*φ))≤2.

[0090] According to the range of the constraint relationship between the total optical power φ of the near-eye optical system and the curvature radius R of the second surface 52 of the first lens 5 close to the human eye 01 in the above example, the radial size of the near-eye optical system can be further reduced.

[0091] Wherein, the range of the total optical focal length φ of the near-eye optical system is: 0.1≤φ≤1.

[0092] In some examples of this application, see Figure 2 The edge interval between the light splitting element 6 and the polarized reflection element 8 is T2, and T2 and T1 satisfy: 0<(T2-T1) / (T2+T1)≤1.

[0093] Wherein, T1 is the center distance between the light splitting element 6 and the polarized reflection element 8 .

[0094] By constraining the size of the center interval and the edge interval between the beam splitter element 6 and the polarized reflective element 8, the field curvature and distortion of the imaging can be improved under a large field of view (such as FOV ≥ 100°), especially the imaging quality of the edge field of view can be taken into account.

[0095] In some examples of this application, see Figure 1 The near-eye optical system further includes a display screen 1, which emits light for imaging display, and the display screen 1 is located on a side of the beam splitting element 6 away from the first optical element.

[0096] See also Figure 1 A protective glass 2 may be provided on the light emitting surface of the display screen 1 to protect the display screen 1 .

[0097] The display screen 1 may be, for example, a self-luminous screen such as LCD, LED, OLED, Micro-OLED, ULED, or a reflective screen such as DMD.

[0098] The display screen 1 can emit RGB light, for example, to form a color image.

[0099] In some examples of this application, see Figure 1 The near-eye optical system also includes a second optical element, which is located between the display screen 1 and the beam splitter 6. The second optical element includes at least one lens, and the optical power of the second optical element is positive.

[0100] According to the above example, in the near-eye optical system, at least one lens (the number of lenses ≥ 1) can be arranged between the display screen 1 and the beam splitter 6 , and adding a certain number of lenses to this position can improve image quality.

[0101] The optical power of the second optical element is φ2, -0.05≤φ2≤0.05.

[0102] It is more preferred that the focal length of the second optical element is designed to be positive, that is, 0≤φ2≤0.05. This design can effectively reduce the incident angle of the light of the beam splitter 6, reduce the coating difficulty, and also help reduce the process difficulty. In addition, the positive focal length provided by the second optical element can also take into account the imaging quality of the edge field of view.

[0103] Optionally, see Figure 1 , the second optical element is a third lens 3, and the optical power of the third lens 3 is positive.

[0104] That is to say, when the second optical element is a single lens, the optical power of the second optical element is the optical power of the single lens. For example, the second optical element is the third lens 3 mentioned above, and the optical power range of the third lens 3 is the range of φ2 mentioned above.

[0105] The preferred range of the third lens 3 is 0 to 0.05 (including both endpoints).

[0106] When the second optical element is composed of two or more lenses, the optical power of the second optical element is the combined optical power of all the lenses, and the specific power can refer to the above range of φ2.

[0107] In some examples of the present application, the optical power φ1 of the first optical element is positive, and 0.005≤φ1≤0.1.

[0108] See also Figure 1 The first optical element includes at least two lenses, for example, a first lens 5 and a second lens 4, and the combined optical power of the first lens 5 and the second lens 4 is positive.

[0109] It should be noted that in the near-eye optical system, the optical focal length of the first optical element located on the side of the human eye 01 is positive, and the optical focal length of the second optical element located on the side of the display screen 1 is also positive. This design can achieve a large field of view angle (for example, 100°) with a small screen size. The screen size is, for example, 0.9-1.4 inches, which is conducive to reducing the volume and weight of the entire near-eye optical system.

[0110] In some examples of this application, see Figure 3 A polarizer 9 is disposed on the side of the polarized reflective element 8 away from the phase retarder 7; the phase retarder 7, the polarized reflective element 8 and the polarizer 9 are stacked to form a composite film material.

[0111] See also Figure 3 The near-eye optical system may further include a polarizer 9. The introduction of the polarizer 9 may reduce stray light, which is beneficial for improving the final imaging quality.

[0112] The polarizer 9 is, for example, a linear polarizer, and the transmission axis direction thereof can be along the horizontal direction, the vertical direction or any other direction.

[0113] Of course, an anti-reflection film may also be introduced into the above-mentioned composite film material.

[0114] In some examples of the present application, the display screen 1 is configured to emit circularly polarized light or natural light; when the light emitted by the display screen 1 is natural light, the light-emitting surface of the display screen 1 is also provided with a superimposed element for converting the natural light into circularly polarized light, and the superimposed element includes at least a phase delay plate and a linear polarizer.

[0115] When the display screen 1 emits natural light, the polarization state of the natural light needs to be converted first, so that the natural light is first converted into circularly polarized light and then incident on the optical elements on the left, and finally the light emitted by the first optical element enters the human eye 01 for imaging.

[0116] According to the above example, the phase retarder and the linear polarizer are combined into a stacked element and mounted on the light-emitting surface of the display screen 1. This can reduce the difficulty of assembly and enable two optical elements to be placed at the same time in one assembly.

[0117] The transmission axis of the linear polarizer may be in the horizontal direction, the vertical direction or any other direction.

[0118] The phase retarder is, for example, a quarter wave plate, which can realize the conversion of linear polarized light into circular polarized light, or the conversion of circular polarized light into linear polarized light.

[0119] According to the near-eye optical system provided by the embodiment of the present application, the first optical element includes but is not limited to the use of two lenses, and a larger number of lenses, such as three lenses, can be used as needed. The second optical element includes but is not limited to the use of a single lens, and a larger number of lenses, such as two lenses, can be used as needed. In addition, it should be noted that the introduction of the second optical element is a preferred solution, and the introduction of the second optical element can improve the imaging quality.

[0120] According to the near-eye optical system provided in the embodiment of the present application, see Figure 1 , the light propagation is as follows:

[0121] The display screen 1 emits circularly polarized light, which is transmitted through the third lens 3 and the second lens 4, becomes linearly polarized light (S light) after passing through the phase retarder 7 on the second surface 52 of the first lens 5, is reflected by the polarization reflection element 8, and again becomes circularly polarized light after passing through the phase retarder 7, is reflected by the beam splitter 6 on the third surface 41 of the second lens 4, and then becomes linearly polarized light (P light) after passing through the phase retarder 7, and then is transmitted through the first lens 5 to enter the human eye 01.

[0122] The near-eye optical system of the present application embodiment, see Figure 1 , which includes a first lens 5, a second lens 4 and a third lens 3, wherein the refractive index and dispersion coefficient of the materials used in the first lens 5, the second lens 4 and the third lens 3 are in the range of: 1.4 <n<2.0,20<v<75。

[0123] For example, the first lens 5, the second lens 4 and the third lens 3 have the same refractive index and dispersion coefficient, which are all designed as: n=1.54, v=56.3.

[0124] The center thickness T1 of the first lens 5 is in the range of 1mm≤T1≤10mm, and it includes two optical surfaces, namely a first surface 51 and a second surface 52. The two surfaces can be aspherical surfaces or planes. The first surface 51 is close to the display screen 1, and the second surface 52 is far away from the display screen 1.

[0125] Wherein, an anti-reflection film may be selectively provided on the first surface 51 of the first lens 5 .

[0126] The above-mentioned composite film material can be mounted on the second surface 52 of the first lens 5, including the stacked phase retarder 7, the polarized reflective element 8 (transmitting P light and reflecting S light) and the polarizer 9. Of course, an anti-reflection film can also be introduced into the composite film material.

[0127] The central thickness T2 of the second lens 4 is in the range of 1mm≤T2≤8mm, and the second lens 4 comprises two optical surfaces, namely a third surface 41 and a fourth surface 42, which can be aspherical or flat. The third surface 41 is close to the display screen 1, and the fourth surface 42 is far from the display screen 1.

[0128] The light splitting element 6 may be disposed on the third surface 41 of the second lens 4 by coating or pasting.

[0129] Wherein, an anti-reflection film may be selectively provided on the fourth surface 42 of the second lens 4 .

[0130] The central thickness T3 of the third lens 3 is in the range of 1 mm ≤ T3 ≤ 8 mm, and the third lens 3 comprises two optical surfaces, namely a fifth surface 31 and a sixth surface 32 , which can be aspherical surfaces or plane surfaces. The fifth surface 31 is close to the display screen 1 , and the sixth surface 32 is far from the display screen 1 .

[0131] The fifth surface 31 and the sixth surface 32 may be selectively provided with an anti-reflection film.

[0132] The optical performance of the near-eye optical system provided by the embodiments of the present application is described below through Examples 1 to 3.

[0133] Example 1

[0134] The near-eye optical system provided in this embodiment 1 is shown in FIG. Figure 1 and Figure 2 , which comprises a polarizer 9, a polarization reflection element 8, a phase retarder 7, a first lens 5, a second lens 4, a beam splitter 6, a third lens 3 and a display screen 1 which are sequentially arranged along the same optical axis;

[0135] The polarizer 9, the polarization reflection element 8 and the phase retarder 7 are laminated and glued to form a composite film material, and the composite film material is disposed on the second surface 52 of the first lens 5;

[0136] The light splitting element 6 is disposed on the third surface 41 of the second lens 4;

[0137] The focal power φ1 of the first optical element is 0.012;

[0138] The focal power φ2 of the second optical element is: -0.05≤φ2≤0.05;

[0139] The maximum optical aperture D of the near-eye optical system is 34 mm;

[0140] The near-eye optical system satisfies: sin(arctan(D / (2*T1)))*φ1*D=1.4.

[0141] Table 1 shows the specific optical parameters of the near-eye optical system of this embodiment 1.

[0142] Table 1

[0143]

[0144] The optical performance of the near-eye optical system provided in this embodiment 1 is demonstrated below through a dot array diagram, an MTF curve diagram, field curvature and distortion, and vertical axis chromatic aberration.

[0145] A point diagram refers to a diffuse pattern formed in a certain range when many light rays emitted from one point pass through the optical system and their intersection with the image plane is no longer concentrated at the same point due to aberration. It is mainly used to evaluate the imaging quality of the projection optical system.

[0146] The MTF curve is a modulation transfer function graph that characterizes the imaging clarity of an optical system through the contrast of black and white line pairs.

[0147] Vertical axis chromatic aberration is also called magnification chromatic aberration, which mainly refers to a complex main light ray on the object side, which becomes multiple light rays when it emerges on the image side due to the dispersion of the refraction system, and the difference in the focal position of blue light and red light on the image plane.

[0148] See also Figure 4 , the maximum value of the image point in the point diagram is less than 45μm.

[0149] See also Figure 5 , MTF>0.4 at 19lp / mm.

[0150] See also Figure 6 , the maximum distortion occurs in 1 field of view, and the absolute value is less than 45%.

[0151] See also Figure 7 , the maximum color difference value is less than 160μm.

[0152] Example 2

[0153] The near-eye optical system shown in this embodiment 2 is shown in FIG. Figure 8 , the basic optical architecture is the same, the differences are:

[0154] (1) The focal power φ1 of the first optical element is 0.03;

[0155] (2) The maximum optical aperture D of the near-eye optical system is 28 mm;

[0156] (3) The near-eye optical system satisfies: sin(arctan(D / (2*T1)))*φ1*D=0.98;

[0157] The optical parameters of each optical element in the near-eye optical system of this embodiment 2 can be seen in Table 2.

[0158] Table 2

[0159]

[0160] The optical performance of the near-eye optical system provided by this embodiment 2 is demonstrated below through a dot array diagram, an MTF curve diagram, field curvature and distortion, and vertical axis chromatic aberration.

[0161] See also Fig. 9, the maximum value of the pixel in the point diagram is less than 32μm.

[0162] See also Fig.10 , MTF>0.2 at 19lp / mm.

[0163] See also Fig.11 , the maximum distortion occurs in 1 field of view, and the absolute value is less than 40%.

[0164] See also Fig.12 , the maximum color difference value is less than 160μm.

[0165] Example 3

[0166] The near-eye optical system shown in this embodiment 3 is shown in FIG. Fig.13 , which is different from the near-eye optical system shown in the aforementioned embodiment 1 in that:

[0167] (1) The focal power φ1 of the first optical element is 0.01;

[0168] (2) The maximum optical aperture D of the near-eye optical system is 32.5 mm;

[0169] (3) The near-eye optical system satisfies: sin(arctan(D / (2*T1)))*φ1*D=1.14;

[0170] The optical parameters of each optical element in the near-eye optical system of this embodiment 3 can be seen in Table 3.

[0171] Table 3

[0172]

[0173] The optical performance of the near-eye optical system provided by this embodiment 3 is demonstrated below through a dot array diagram, an MTF curve diagram, field curvature and distortion, and vertical axis chromatic aberration.

[0174] See also Fig.14 , the maximum value of the image point in the point diagram is less than 37μm.

[0175] See also Fig.15 , MTF>0.2 at 19lp / mm.

[0176] See also Fig.16 , the maximum distortion occurs in 1 field of view, and the absolute value is less than 40%.

[0177] See also Fig.17 , the maximum color difference value is less than 160μm.

[0178] According to another embodiment of the present application, a head-mounted display device is provided.

[0179] The head mounted display device comprises a housing and the near-eye optical system as described above.

[0180] The head mounted display device includes VR smart glasses or VR smart helmets, etc., which is not limited in the embodiments of the present application.

[0181] 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.

[0182] 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.

[0183] 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

1. A near-eye optical system, characterized in that: It comprises a polarized reflection element (8), a phase retarder (7) and a beam splitter (6) arranged along the same optical axis, wherein the phase retarder (7) is located between the beam splitter (6) and the polarized reflection element (8); The near-eye optical system further comprises a first optical element, the first optical element is located between the beam splitter (6) and the phase retarder (7), the first optical element is a lens group, and the optical power of the first optical element is φ1; The near-eye optical system satisfies: 0.5≤sin(arctan(D / (2*T1)))*φ1*D≤1.5; wherein the center interval between the beam splitting element (6) and the polarized reflection element (8) is T1, and the maximum optical aperture of the near-eye optical system is D.

2. The near-eye optical system according to claim 1, characterized in that: The near-eye optical system satisfies: 0.98≤sin(arctan(D / (2*T1)))*φ1*D≤1.

4.

3. The near-eye optical system according to claim 1, characterized in that: The first optical element includes N lenses, and N≥2.

4. The near-eye optical system according to claim 1, characterized in that: The first optical element comprises a first lens (5) and a second lens (4); The beam splitter (6) is arranged on a surface of the second lens (4) away from the first lens (5), and the phase retarder (7) and the polarized reflection element (8) are stacked and arranged on a surface of the first lens (5) away from the second lens (4).

5. The near-eye optical system according to claim 4, characterized in that: The radius of curvature of the surface of the first lens (5) away from the second lens (4) is R, and R<0.

6. The near-eye optical system according to claim 5, characterized in that: The total optical focal length of the near-eye optical system is φ, and the near-eye optical system also satisfies: abs(1 / (R*φ))≤2.

7. The near-eye optical system according to claim 1, characterized in that: The edge interval between the light splitting element (6) and the polarized reflection element (8) is T2, and the relationship between T2 and T1 satisfies: 0<(T2-T1) / (T2+T1)≤1.

8. The near-eye optical system according to any one of claims 1 to 7, characterized in that: The near-eye optical system further comprises a display screen (1), the display screen (1) emitting light for imaging display, and the display screen (1) is located on a side of the beam splitting element (6) facing away from the first optical element.

9. The near-eye optical system according to claim 8, characterized in that: The near-eye optical system further comprises a second optical element, the second optical element being located between the display screen (1) and the beam splitting element (6), the second optical element comprising at least one lens, and the optical focal length of the second optical element being positive.

10. The near-eye optical system according to claim 9, characterized in that: The second optical element is a third lens (3), and the optical power of the third lens (3) is positive.

11. The near-eye optical system according to claim 9, characterized in that: The optical power φ1 of the first optical element is positive, and 0.005≤φ1≤0.

1.

12. The near-eye optical system according to claim 8, characterized in that: A polarizer (9) is provided on the side of the polarized reflection element (8) facing away from the phase retarder (7); The phase retarder (7), the polarized reflection element (8) and the polarizer (9) are stacked to form a composite film material.

13. The near-eye optical system according to claim 8, characterized in that: The display screen (1) is configured to emit circularly polarized light or natural light; When the light emitted by the display screen (1) is natural light, the light-emitting surface of the display screen (1) is also provided with a superimposed element for converting the natural light into circularly polarized light, and the superimposed element comprises at least a phase delay plate and a linear polarizer.

14. A head mounted display device, characterized in that: include: shell; as well as, A near-eye optical system as claimed in any one of claims 1 to 13.

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