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 first optical element, a polarization reflection element, a phase retarder and a second optical element which are arranged along the same optical axis, and the second optical element is configured to be capable of moving along the optical axis relative to the first optical element; the first optical element comprises a first lens and a second lens; the second optical element comprises a third lens and a light splitting element arranged on one surface of the third lens, and the phase retarder is located between the light splitting element and the polarization reflection element; the first optical element satisfies the following condition: 0 < [(phi 1 + phi 2) / (phi 1-phi 2)] * (n2-n1) < = 1, phi 1 and n1 are respectively the focal power and the refractive index of the first lens, and phi 2 and n2 are respectively the focal power and the refractive index of the second lens.

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] VR optical solutions have high requirements for chromatic aberration and distortion, and currently mainly use software pre-correction. However, software pre-correction will increase the power consumption of the optical system. In particular, when the field of view of the optical system is relatively large, without software pre-correction, the requirements for the optical solution will be stricter, which will greatly increase the difficulty and cost of production. 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 first optical element, a polarization reflection element, a phase retarder, and a second optical element arranged along the same optical axis, wherein the second optical element is configured to be movable along the optical axis relative to the first optical element;

[0005] The first optical element includes a first lens and a second lens;

[0006] The second optical element includes a third lens and a beam splitter disposed on a surface of the third lens, and the phase retarder is located between the beam splitter and the polarized reflective element;

[0007] The first optical element satisfies: 0<[(φ 1 +φ 2 ) / (φ 1 -φ 2 )]*(n 2 -n 1 )≤1, where φ 1 、n 1 are the focal power and refractive index of the first lens, respectively, 2 、n 2 are the optical power and refractive index of the second lens respectively.

[0008] Optionally, the optical power φ of the first lens is 1 is positive, the focal power φ of the second lens 2 is negative.

[0009] Optionally, a ratio of a center thickness to an edge thickness of the third lens is ≥1.

[0010] Optionally, the first optical element and the second optical element form a folded optical structure, so that the projected light can be folded back between the first optical element and the second optical element;

[0011] There is a target interval A between the first optical element and the second optical element, and the refractive index of the medium in the target interval A is n, and n≥1.

[0012] Optionally, the near-eye optical system further comprises a display, emitting light for imaging display;

[0013] The display is disposed on a side of the second optical element facing away from the first optical element.

[0014] Optionally, the near-eye optical system further comprises a third optical element, which is disposed between the second optical element and the display and is located on the same optical axis as the first optical element and the second optical element;

[0015] The third optical element comprises at least a fourth lens, and the optical power of the third optical element is φ 4 , and φ 4 >0.

[0016] Optionally, when the third optical element only uses the fourth lens, the optical power of the fourth lens is φ 4 , and φ 4 >0.

[0017] Optionally, the focal power of the second optical element is φ 3 , the near-eye optical system satisfies the following relationship:

[0018] 0.2≤φ 1 / (φ 3 +φ 4 )≤3.

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

[0020] In the case that the light emitted by the display is natural light, a superimposed element is disposed on the light emitting surface of the display to convert the natural light into circularly polarized light, and the superimposed element at least includes a phase delay plate and a linear polarizer.

[0021] Optionally, the light splitting element is disposed on a surface of the third lens away from the display;

[0022] The phase retarder and the polarized reflective element are stacked and arranged on a surface of the second lens close to the display.

[0023] Optionally, the near-eye optical system further comprises a polarizer, wherein the polarizer is arranged on a side of the polarizing reflective element away from the phase retarder, and the polarizer, the polarizing reflective element and the phase retarder are stacked to form a composite film material.

[0024] Optionally, the absolute value of distortion of the near-eye optical system is less than 3%, and the maximum chromatic aberration value is less than 24 μm.

[0025] In a second aspect, the present application provides a head mounted display device. The head mounted display device comprises:

[0026] a housing; and

[0027] A near-eye optical system as described in the first aspect.

[0028] The beneficial effects of this application are:

[0029] According to the near-eye optical system provided in the embodiment of the present application, through the reasonable layout of the optical structure and the reasonable constraints on the refractive index and optical focal length of the first optical element therein, an optical effect of low distortion, low chromatic aberration and variable focus can be achieved.

[0030] 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

[0031] 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.

[0032] Figure 1 One of the structural schematic diagrams of the near-eye optical system provided in an embodiment of the present application;

[0033] Figure 2 A schematic diagram of the arrangement of the composite membrane material provided in the embodiment of the present application;

[0034] Figure 3 One of the dot array diagrams of the near-eye optical system provided in Example 1 of the present application;

[0035] Figure 4 One of the modulation transfer function MTF curves of the near-eye optical system provided in Example 1 of the present application;

[0036] Figure 5 One of the field curvature and distortion diagrams of the near-eye optical system provided in Example 1 of the present application;

[0037] Figure 6 One of the vertical axis chromatic aberration diagrams of the near-eye optical system provided in Example 1 of the present application;

[0038] Figure 7 The second dot array diagram of the near-eye optical system provided in Example 1 of the present application;

[0039] Figure 8 A second modulation transfer function MTF curve diagram of the near-eye optical system provided in Example 1 of the present application;

[0040] Fig. 9 The second diagram of field curvature and distortion of the near-eye optical system provided in Example 1 of the present application;

[0041] Fig.10 The second vertical axis chromatic aberration diagram of the near-eye optical system provided in Example 1 of the present application;

[0042] Fig.11 One of the dot array diagrams of the near-eye optical system provided in Example 2 of the present application;

[0043] Fig.12 One of the modulation transfer function MTF curves of the near-eye optical system provided in Example 2 of the present application;

[0044] Fig.13 One of the field curvature and distortion diagrams of the near-eye optical system provided in Example 2 of the present application;

[0045] Fig.14 One of the vertical axis chromatic aberration diagrams of the near-eye optical system provided in Example 2 of the present application;

[0046] Fig.15 The second dot array diagram of the near-eye optical system provided in Example 2 of the present application;

[0047] Fig.16 A second modulation transfer function MTF curve diagram of the near-eye optical system provided in Example 2 of the present application;

[0048] Fig.17 The second diagram of field curvature and distortion of the near-eye optical system provided in Example 2 of the present application;

[0049] Fig.18 The second vertical axis chromatic aberration diagram of the near-eye optical system provided in Example 2 of the present application;

[0050] Fig.19 The second structural schematic diagram of the near-eye optical system provided in the embodiment of the present application;

[0051] Fig. 20 One of the dot array diagrams of the near-eye optical system provided in Example 3 of the present application;

[0052] Fig.21 One of the modulation transfer function MTF curves of the near-eye optical system provided in Example 3 of the present application;

[0053] Fig. 22 One of the field curvature and distortion diagrams of the near-eye optical system provided in Example 3 of the present application;

[0054] Fig.23 One of the vertical axis chromatic aberration diagrams of the near-eye optical system provided in Example 3 of the present application;

[0055] Fig.24 The second dot array diagram of the near-eye optical system provided in Example 3 of the present application;

[0056] Fig.25 A second modulation transfer function MTF curve diagram of the near-eye optical system provided in Example 3 of the present application;

[0057] Fig.26 The second diagram of field curvature and distortion of the near-eye optical system provided in Example 3 of the present application;

[0058] Fig. 27 This is the second vertical axis chromatic aberration diagram of the near-eye optical system provided in Example 3 of the present application.

[0059] Description of reference numerals:

[0060] 100, a first optical element; 200, a second optical element;

[0061] 1. Display; 2. Screen protection element; 3. Third lens; 4. Second lens; 5. First lens; 6. Human eye; 7. Polarized reflection element; 8. Phase retarder; 9. Spectral element; 10. Fourth lens; 11. Polarizer; 12. Anti-reflection film. DETAILED DESCRIPTION

[0062] 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.

[0063] 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.

[0064] 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.

[0065] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] The near-eye optical system proposed in the embodiment of the present application, see Figure 1 , the near-eye optical system includes a first optical element 100, a polarizing reflective element 7, a phase retarder 8 and a second optical element 200 arranged along the same optical axis, wherein the second optical element 200 is configured to be movable relative to the first optical element 100 along the optical axis. The first optical element 100 includes a first lens 5 and a second lens 4. The second optical element 200 may include a third lens 3 and a beam splitter 9 arranged on a surface of the third lens 3, and the phase retarder 8 is located between the beam splitter 9 and the polarizing reflective element 7. The first optical element 100 should satisfy: 0<[(φ 1 +φ 2 ) / (φ 1 -φ 2 )]*(n 2 -n 1 )≤1, where φ 1 、n 1 are respectively the focal power and refractive index of the first lens 5, φ 2 、n 2 are the optical power and refractive index of the second lens 4 respectively.

[0070] According to the above example, the second optical element 200 includes, for example, a third lens 3 and a beam splitter 9. The beam splitter 9 can be directly mounted or plated on the third lens 3. Figure 1 As shown, the beam splitter 9 is arranged on a side of the third lens 3 close to the first optical element 100. A more preferred solution is to arrange the beam splitter 9 on a surface of the third lens 3 so that it moves along the optical axis with the third lens 3.

[0071] According to the near-eye optical system provided by the above-mentioned embodiments of the present application, the first optical element 100 and the second optical element 200 can form a folded light path in combination with the phase retarder 8 and the polarization reflection element 7, so that the projected light can be folded back between the first optical element 100 and the second optical element 200. The introduction of the folded light path can ensure good imaging quality while reducing the size of the near-eye optical system along the optical axis.

[0072] In the near-eye optical system provided in the above embodiment, see Figure 1 , which includes at least two optical elements, namely the first optical element 100 and the second optical element 200. The first optical element 100 is located on the side close to the human eye 6, for example. The first optical element 100 itself can include a first lens 5 and a second lens 4 spaced apart along the same optical axis, and the two optical lenses should satisfy: 0<[(φ 1 +φ 2 ) / (φ 1 -φ 2 )]*(n 2 -n 1 )≤1, φ 1 、n 1 are respectively the focal power and refractive index of the first lens 5, φ 2 、n 2 are respectively the focal power and refractive index of the second lens 4, and the optical parameter constraint design can well correct the chromatic aberration and distortion of imaging, so that the formed near-eye optical system has the optical performance of low chromatic aberration and low distortion.

[0073] The near-eye optical system provided in the embodiment of the present application has optical performance of low chromatic aberration and low distortion, and does not require software to correct the imaging.

[0074] The second optical element 200 is located on a side away from the human eye 6 relative to the first optical element 100. In addition, the second optical element 200 is designed to be able to move away from or closer to the first optical element 100 along the optical axis, thereby achieving a variable focus effect of the entire near-eye optical system. In this way, users with different vision can use the near-eye optical system and can all obtain a good visual experience.

[0075] The near-eye optical system provided in the embodiment of the present application can obtain an image with low chromatic aberration and low distortion as the second optical element 200 moves along the optical axis, no matter where the second optical element 200 moves to, even if it moves to the two extreme positions of the diopter.

[0076] See also Figure 5 and Fig. 9As shown in FIG. 1 , the absolute value of the distortion of the near-eye optical system provided by the embodiment of the present application is less than 3%. Figure 6 and Fig.10 As shown, the maximum chromatic aberration value of the near-eye optical system provided by the embodiment of the present application is less than 24 μm.

[0077] In the above embodiment, the second optical element 200 includes at least one optical lens and a beam splitter 9. The beam splitter 9 is, for example, a semi-reflective and semi-transmissive film.

[0078] Specifically, the second optical element 200 may be composed of a third lens 3 and a beam splitter 9, and the third lens 3 is configured to be movable along the optical axis relative to the first optical element 100, that is, the third lens 3 is a movable lens in the entire near-eye optical system. On this basis, the beam splitter 9 is directly mounted or plated on the surface of the third lens 3 close to the first optical element 100 (i.e. Figure 1 On the surface of the third lens 3 on the left side shown), see Figure 1 .

[0079] Among them, the beam splitter element 9 can move with the third lens 3. This design is based on the fact that the light incident into the near-eye optical system will pass through the beam splitter element 9 twice. The beam splitter element 9 can provide a larger optical focal length. The design allows the beam splitter element 9 to move, which is conducive to achieving zoom.

[0080] It should be noted that the second optical element 200 includes but is not limited to a single optical lens, and multiple optical lenses can be provided as needed.

[0081] The driving force for driving the second optical element 200 to move may be realized by an external driving mechanism or by manual driving, which is not limited in the present application.

[0082] The near-eye optical system provided in the embodiment of the present application can achieve a larger field of view angle under the premise of miniaturized design, and at the same time can have an optical effect of low chromatic aberration and low distortion, and can also achieve a zoom effect.

[0083] According to the near-eye optical system provided in the embodiment of the present application, through the reasonable layout of the optical structure and the reasonable constraints on the refractive index and optical focal length of the first optical element 100 therein, an optical effect of low distortion, low chromatic aberration and variable focus can be achieved.

[0084] The near-eye optical system provided in the above-mentioned embodiments of the present application is a folded optical path.

[0085] The light splitting element 9 can allow a portion of light to be transmitted and another portion of light to be reflected.

[0086] The light splitting element 9 is, for example, a semi-transmissive and semi-reflective film.

[0087] It should be noted that the reflectivity and transmittance of the light splitting element 9 can be flexibly adjusted according to specific needs, and this is not limited in the embodiments of the present application.

[0088] The phase retarder 8 is, for example, a quarter wave plate.

[0089] Of course, the phase retarder 8 can also be set as other phase retarder plates such as a half-wave plate as needed.

[0090] In the near-eye optical system proposed in the embodiment of the present application, the phase retarder 8 is arranged in the folded light path located on the side close to the human eye 6 to change the polarization state of the light, for example, to convert linearly polarized light into circularly polarized light, or to convert circularly polarized light into linearly polarized light.

[0091] The polarized reflective element 7 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 perpendicular to the angle.

[0092] In the embodiment of the present application, the phase retarder 8 and the polarized reflective element 7 cooperate with each other to analyze and transmit the light.

[0093] It should be emphasized that the optical elements such as the spectroscopic element 9, the phase retarder 8 and the polarized reflection element 7 can form a folded light path on the side close to the human eye 6. The layout positions of the above-mentioned optical elements are relatively flexible, but it needs to be ensured that the phase retarder 8 is between the spectroscopic element 9 and the polarized reflection element 7.

[0094] In some examples of the present application, the optical power φ of the first lens 5 is 1 is positive, the focal power φ of the second lens 4 2 is negative.

[0095] According to the near-eye optical system provided in the embodiment of the present application, the first optical element 100 located on the side of the human eye 6 is designed to include a first lens 5 and a second lens 4, see Figure 1 , the first lens 5 is closer to the human eye 6, the second lens 4 is farther away from the human eye 6 than the first lens 5, and the optical power φ of the first lens 5 1 >0, and the φ of the second lens 4 2 <0, this combination of positive and negative focal powers, and located on the side close to the human eye 6, is conducive to correcting the aberration of the near-eye optical system, combined with 0<[(φ 1 +φ 2) / (φ 1 -φ 2 )]*(n 2 -n 1 )≤1, the chromatic aberration and distortion of the near-eye optical system can be further reduced, which can improve the imaging quality in many aspects. This makes the formed near-eye optical system have good optical performance.

[0096] In some examples of the present application, the ratio of the center thickness to the edge thickness of the third lens 3 is ≥1.

[0097] According to the near-eye optical system provided in the embodiment of the present application, see Figure 1 The second optical element may use a third lens 3, and the third lens 3 is configured to be able to translate along the optical axis. In combination with the above example, by constraining the thickness of the movable third lens 3, it can help correct the distortion value of the edge field of view and improve the image quality.

[0098] However, if the ratio of the center thickness to the edge thickness of the third lens 3 is less than 1, the distortion of the edge field of view cannot be improved.

[0099] In some examples of this application, see Figure 1 The first optical element 100 and the second optical element 200 form a folded optical structure, so that the projected light can be reflected between the first optical element 100 and the second optical element 200; there is a target interval A between the first optical element 100 and the second optical element 200, and the refractive index of the medium in the target interval A is n, and n≥1.

[0100] Based on the above example, see Figure 1 , the light for imaging display emitted by the display 1 located on the far right is projected into the second optical element 200, the light is folded back twice between the second optical element 200 and the first optical element 100, and the light passes through the target interval A between the second optical element 200 and the first optical element 100 twice. When the refractive index n of the medium in the target interval A satisfies: n≥1, the total system length of the near-eye optical system can be effectively reduced.

[0101] In some examples of this application, see Figure 1 The near-eye optical system further comprises a display 1 for emitting light for imaging display. The display 1 is arranged on a side of the second optical element 200 away from the first optical element 100 .

[0102] The display 1 may be a self-luminous screen such as LCD, LED, OLED, Micro-OLED, ULED, or a reflective screen such as DMD.

[0103] In this case, for example, a screen protection element 2 may be arranged on the luminous surface of the display 1 .

[0104] The display 1 can emit RGB light, for example, to form a color image.

[0105] In some examples of this application, see Fig.19 The near-eye optical system further comprises a third optical element, which is disposed between the second optical element 200 and the display 1 and is located on the same optical axis as the first optical element 100 and the second optical element 200. The third optical element comprises at least a fourth lens 10, and the optical power of the third optical element is φ 4 , and φ 4 >0.

[0106] Based on the above example, see Fig.19 A third optical element may be introduced between the light emitting side of the display 1 and the second optical element 200. The third optical element may include one or more optical lenses. The introduction of the third optical element may improve the image quality and reduce the total length of the near-eye optical system to a certain extent.

[0107] The overall optical power of the third optical element is positive, which can help improve the image quality of the edge field of view, so that the near-eye optical system can have good imaging quality in the whole field of view.

[0108] In some examples of this application, see Fig.19 , when the third optical element only uses the fourth lens 10, the optical power of the fourth lens 10 is φ 4 , and φ 4 >0.

[0109] That is to say, when the third optical element includes only one lens, the optical power of the lens is designed to be positive.

[0110] When the third optical element includes two or more lenses, the combined optical power formed therefrom is positive.

[0111] It should be noted that, by adding an optical element on one side of the display 1 of the near-eye optical system, the field of view and resolution of the near-eye optical system can be appropriately improved.

[0112] In some examples of the present application, the optical power of the second optical element 200 is φ 3 , the near-eye optical system satisfies the following relationship: 0.2≤φ 1 / (φ 3 +φ4 )≤3.

[0113] According to the above example, by setting constraints on the second optical element 200 and the third optical element, it is possible to achieve a reasonable distribution of optical power and improve process feasibility.

[0114] In some examples of the present application, the display 1 is configured to emit circularly polarized light or natural light. In the case where the light emitted by the display 1 is natural light, a superimposed element is provided on the light-emitting surface of the display 1 to convert the natural light into circularly polarized light, and the superimposed element includes at least a phase retarder and a linear polarizer.

[0115] See also Figure 1 and Figure 7 The near-eye optical system also includes a display 1. When the display 1 emits natural light, it is necessary to convert the polarization state of the natural light first, so that the natural light is first converted into circularly polarized light and then emitted into the optical elements on the left. Finally, the light emitted by the first optical element enters the human eye 6 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 1. This can reduce the difficulty of assembly and enable two optical elements to be placed simultaneously 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 and the conversion of circular polarized light into linear polarized light.

[0119] Specifically, the fast axis or slow axis direction of the phase retarder disposed on the light-emitting surface of the display 1 and the transmission axis direction of the linear polarizer form an angle of 45°.

[0120] In some examples of the present application, the beam splitter 9 is disposed on the surface of the third lens 3 away from the display 1. The phase retarder 8 and the polarized reflective element 7 are stacked and disposed on the surface of the second lens 4 close to the display 1, see Figure 2 .

[0121] According to the above example, there is no need to introduce a flat support member in the entire optical structure to support the beam splitter element 9, the phase retarder 8 and the polarization reflection element 7, so the optical architecture can be simplified.

[0122] The light splitting element 9 can be disposed on the surface of the third lens 3 away from the display 1 by, for example, attaching or plating. Figure 1 .

[0123] The polarized reflective element 7 and the phase retarder 8 are laminated and glued and then glued and arranged on the same surface of the second lens 4, specifically, mounted on the surface of the second lens 4 close to the display 1, which is conducive to the alignment adjustment between the two. Figure 2 The phase retarder 8 is, for example, a quarter wave plate. The polarized reflective element 7 is, for example, a polarized reflective film.

[0124] It should be noted that, in the present application, the light splitting element 9 can also be arranged on the side of the third lens 3 away from the display 1 through a support, and the phase retarder 8 and the polarized reflection element 7 can be superimposed together and arranged on the side of the second lens 4 close to the display 1 through a support, see Figure 1 .

[0125] In some examples of the present application, the near-eye optical system also includes a polarizer 11, which is arranged on the side of the polarizing reflective element 7 away from the phase retarder 8, and the polarizer 11, the polarizing reflective element 7 and the phase retarder 8 are stacked to form a composite film material.

[0126] See also Figure 2 The near-eye optical system may further include a polarizer 11. The introduction of the polarizer 11 may reduce stray light, which is beneficial for improving the final imaging quality.

[0127] The polarizer 11 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.

[0128] The polarizer 11 may be located on a side of the polarizing reflective element 7 away from the phase retarder 8 , and the polarizer 11 , the polarizing reflective element 7 and the phase retarder 8 are stacked to form a composite film.

[0129] Of course, please continue to see Figure 2 , an anti-reflection film 12 may also be introduced into the above-mentioned composite film material.

[0130] The anti-reflection film 12 can be glued and arranged on the side of the polarization reflection element 7 away from the phase retarder 8, for example.

[0131] In some examples of the present application, the absolute value of distortion of the near-eye optical system is less than 3%, and the maximum chromatic aberration value is less than 24 μm.

[0132] According to the near-eye optical system provided in the embodiment of the present application, at least three optical lenses are used, namely Figure 1The first lens 5, the second lens 4 and the third lens 3 shown in FIG. Of course, the near-screen side of the near-eye optical system can also be additionally introduced with a fourth lens 10, see Fig.19 .

[0133] It should be noted that the near-eye optical system of the embodiment of the present application uses at least three lenses, namely, a first lens 5, a second lens 4 and a third lens 3. The three lenses are described below.

[0134] The near-eye optical system uses three lenses, and the refractive index and dispersion coefficient of the materials used in the three lenses are in the range of: 1.4 <n<2.0,20<v<75。

[0135] The refractive index and dispersion coefficient of the first lens 5 are: 1 =1.54, v 1 =55.7. The refractive index and dispersion coefficient of the second lens 4 are: n 2 =1.64, v 2 =23. The refractive index and dispersion coefficient of the third lens 5 are: n 3 =1.54, v 3 =56.3.

[0136] The center thickness T of the first lens 5 1 Range: 1mm≤T 1 ≤8mm, it includes two optical surfaces, namely a first surface and a second surface, the two surfaces may be aspherical surfaces. The first surface is far away from the display 1, and the second surface is close to the display 1.

[0137] Optionally, anti-reflection films may be applied to both surfaces of the first lens 5 .

[0138] The central thickness T of the second lens 4 2 Range: 1mm≤T 2 ≤10mm, it includes two optical surfaces, namely the third surface and the fourth surface, the two surfaces can be aspherical surfaces or plane surfaces. The third surface is far away from the display 1, and the fourth surface is close to the display 1.

[0139] Optionally, see Figure 2 A composite film is disposed on the third surface, and the composite film may include an anti-reflection film 12, a phase retarder 8, a polarized reflection element 7 (transmitting P light and reflecting S light) and a polarizer 11 (transmitting P light). An anti-reflection film may be disposed on the fourth surface.

[0140] The central thickness T of the third lens 3 3 Range: 1mm≤T 3≤8mm, it includes two optical surfaces, namely the fifth surface and the sixth surface, the two surfaces may be aspherical surfaces. The fifth surface is far away from the display 1, and the sixth surface is close to the display 1.

[0141] Optionally, an anti-reflection film material is mounted on the fifth surface, and a light splitting element 9 (ie, a semi-reflective and semi-transparent film) is mounted or plated on the sixth surface.

[0142] See also Figure 1 , the light propagation process of the near-eye optical system is as follows:

[0143] The display 1 emits circularly polarized light, which is transmitted through the third lens 3, converted into linearly polarized light (S light) through the phase retarder 8 (quarter wave plate) on the third surface of the second lens 4, reflected through the polarization reflection element 7, converted into circularly polarized light through the phase retarder 8, reflected through the beam splitter 9 on the sixth surface 32 of the third lens 3, converted into linearly polarized light (P light) through the phase retarder 8 again, transmitted through the fourth surface of the second lens 4 and the first lens 5, and hits the human eye 6.

[0144] 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.

[0145] Example 1

[0146] The optical architecture of the near-eye optical system provided in this embodiment 1 can be found in Figure 1 , comprising a first optical element 100, a second optical element 200 and a display 1 arranged along the same optical axis, and the second optical element 200 can move along the optical axis relative to the first optical element 100;

[0147] The first optical element 100 includes a first lens 5 and a second lens 4, see Figure 2 The polarizer 11, the polarization reflection element 7 and the phase retarder 8 are stacked to form a composite film material disposed on the third surface of the second lens 4; the optical power of the first lens 5 is φ 1 is positive, the focal power φ of the second lens 4 2 is negative;

[0148] The second optical element 200 includes a third lens 3 and a beam splitter 9 disposed on a sixth surface of the third lens 3; the ratio of the center thickness to the edge thickness of the third lens 3 is ≥1;

[0149] A folded optical structure is formed between the first optical element 100 and the second optical element 200, so that the projected light can be reflected between the first optical element 100 and the second optical element 200; there is a target interval A between the first optical element 100 and the second optical element 200, and the refractive index of the medium in the target interval A is n, and n≥1.

[0150] Specific optical parameters of the near-eye optical system of the first embodiment are shown.

[0151] Table 1

[0152]

[0153]

[0154] 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.

[0155] 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.

[0156] 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.

[0157] 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.

[0158] Figures 3 to 6 A limit case in which the second optical element 200 moves to change the diopter in the near-eye display system provided in Embodiment 1 is shown.

[0159] See also Figure 3 , the maximum value of the image point in the point diagram is less than 7μm.

[0160] See also Figure 4 , MTF>0.6 at 24lp / mm.

[0161] See also Figure 5 , the maximum distortion occurs in 1 field of view, and the absolute value is less than 3%.

[0162] See also Figure 6 , the maximum color difference value is less than 24μm.

[0163] Figures 8 to 11Another limit of the change in the refractive power of the second optical element in the near-eye display system provided in Embodiment 1 is shown.

[0164] See also Figure 8 , the maximum value of the image point in the point diagram is less than 25μm.

[0165] See also Fig. 9 , MTF>0.3 at 24lp / mm.

[0166] See also Fig.10 , the maximum distortion occurs in 1 field of view, and the absolute value is less than 3%.

[0167] See also Fig.11 , the maximum color difference value is less than 24μm.

[0168] Example 2

[0169] The optical structure of the near-eye optical system shown in the second embodiment is the same as that of the first embodiment described above. Figure 1 .The difference is: the optical parameters are different, see Table 2 below.

[0170] Table 2 shows the specific optical parameters of the near-eye optical system.

[0171] Table 2

[0172]

[0173] 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.

[0174] Figures 11 to 14 A limit case in which the second optical element 200 moves to change the diopter in the near-eye display system provided in Embodiment 2 is shown.

[0175] See also Fig.11 , the maximum value of the image point in the point diagram is less than 8μm.

[0176] See also Fig.12 , MTF>0.55 at 24lp / mm.

[0177] See also Fig.13 , the maximum distortion occurs in 1 field of view, and the absolute value is less than 3%.

[0178] See also Fig.14 , the maximum color difference value is less than 24μm.

[0179] Figures 15 to 18 Another extreme case in which the second optical element 200 moves to change the diopter in the near-eye display system provided by Embodiment 2 is shown.

[0180] See also Fig.15 , the maximum value of the image point in the point diagram is less than 30μm.

[0181] See also Fig.16 , MTF>0.1 at 24lp / mm.

[0182] See also Fig.17 , the maximum distortion occurs in 1 field of view, and the absolute value is less than 3%.

[0183] See also Fig.18 , the maximum color difference value is less than 24μm.

[0184] Example 3

[0185] The near-eye optical system shown in this embodiment 3 is different from the near-eye optical system shown in the aforementioned embodiment 1 in that a third optical element is added between the second optical element 200 and the display 1, and a lens, namely, a fourth lens 10, is used in the third optical element. Fig.19 .

[0186] Table 3 shows the specific optical parameters of the near-eye optical system, which are as follows.

[0187] Table 3

[0188]

[0189]

[0190] 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.

[0191] Figure 20 to Figure 23 A limit case in which the second optical element 200 moves to change the diopter in the near-eye display system provided in Embodiment 3 is shown.

[0192] See also Fig. 20 , the maximum value of the image point in the point diagram is less than 7μm.

[0193] See also Fig.21 , MTF>0.7 at 24lp / mm.

[0194] See also Fig. 22 , the maximum distortion occurs in 1 field of view, and the absolute value is less than 3%.

[0195] See also Fig.23 , the maximum color difference value is less than 24μm.

[0196] Figure 24 to Figure 27 Another extreme case in which the second optical element 200 moves to change the diopter in the near-eye display system provided in Embodiment 3 is shown.

[0197] See also Fig.24 , the maximum value of the image point in the point diagram is less than 17μm.

[0198] See also Fig.25 , MTF>0.3 at 24lp / mm.

[0199] See also Fig.26 , the maximum distortion occurs in 1 field of view, and the absolute value is less than 3%.

[0200] See also Fig. 27 , the maximum color difference value is less than 24μm.

[0201] According to the above-mentioned embodiments 1 to 3, the near-eye optical system provided by the present application has optical properties of low chromatic aberration and low distortion, and can ensure good optical properties by achieving zooming as the second optical element 200 moves.

[0202] According to another embodiment of the present application, a head-mounted display device is provided.

[0203] The head mounted display device comprises a housing and the near-eye optical system as described above.

[0204] 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.

[0205] 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.

[0206] 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.

[0207] 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: The invention comprises a first optical element (100), a polarization reflection element (7), a phase retarder (8), and a second optical element (200) arranged along the same optical axis, wherein the second optical element (200) is configured to be movable along the optical axis relative to the first optical element (100); The first optical element (100) comprises a first lens (5) and a second lens (4); The second optical element (200) comprises a third lens (3) and a beam splitter element (9) arranged on a surface of the third lens (3), and the phase retarder (8) is located between the beam splitter element (9) and the polarized reflection element (7); The first optical element (100) satisfies the following: 0<[(φ1+φ2) / (φ1-φ2)]*(n2-n1)≤1, wherein φ1 and n1 are respectively the optical focal length and refractive index of the first lens (5), and φ2 and n2 are respectively the optical focal length and refractive index of the second lens (4).

2. The near-eye optical system according to claim 1, characterized in that: The optical power φ1 of the first lens (5) is positive, and the optical power φ2 of the second lens (4) is negative.

3. The near-eye optical system according to claim 1, characterized in that: The ratio of the center thickness to the edge thickness of the third lens (3) is ≥1.

4. The near-eye optical system according to claim 1, characterized in that: The first optical element (100) and the second optical element (200) form a folded optical structure, so that the projected light can be folded back between the first optical element (100) and the second optical element (200); A target interval A is provided between the first optical element (100) and the second optical element (200), and the refractive index of the medium in the target interval A is n, and n≥1.

5. The near-eye optical system according to any one of claims 1 to 4, characterized in that: The near-eye optical system further comprises a display (1) which emits light for imaging display; The display (1) is arranged on a side of the second optical element (200) facing away from the first optical element (100).

6. The near-eye optical system according to claim 5, characterized in that: The near-eye optical system further comprises a third optical element, which is arranged between the second optical element (200) and the display (1) and is located on the same optical axis as the first optical element (100) and the second optical element (200); The third optical element at least comprises a fourth lens (10), and the optical power of the third optical element is φ4, and φ4>0.

7. The near-eye optical system according to claim 6, characterized in that: When the third optical element uses only the fourth lens (10), the optical power of the fourth lens (10) is φ4, and φ4>0.

8. The near-eye optical system according to claim 7, characterized in that: The optical focal length of the second optical element (200) is φ3, and the near-eye optical system satisfies the following relationship: 0.2≤φ1 / (φ3+φ4)≤3.

9. The near-eye optical system according to claim 8, characterized in that: The display (1) is configured to emit circularly polarized light or natural light; When the light emitted by the display (1) is natural light, the light-emitting surface of the display (1) is 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.

10. The near-eye optical system according to claim 8, characterized in that: The light splitting element (9) is arranged on a surface of the third lens (3) away from the display (1); The phase retarder (8) and the polarized reflection element (7) are stacked and arranged on a surface of the second lens (4) close to the display (1).

11. The near-eye optical system according to claim 10, characterized in that: The near-eye optical system further comprises a polarizer (11), wherein the polarizer (11) is arranged on a side of the polarizing reflective element (7) away from the phase retarder (8), and the polarizer (11), the polarizing reflective element (7) and the phase retarder (8) are stacked to form a composite film material.

12. The near-eye optical system according to claim 1, wherein: The absolute value of distortion of the near-eye optical system is less than 3%, and the maximum chromatic aberration value is less than 24 μm.

13. 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 12.

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