Near-eye optical system and head-mounted display device

Abstract

Embodiments of the present application provide a near-eye optical system and a head-mounted display device; 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, the second optical element is configured to be movable 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: 0<[(φ1+φ2) / (φ1-φ2)]*(n2-n1)≤1, wherein φ1 and n1 are the optical power and the refractive index of the first lens respectively, and φ2 and n2 are the optical power and the refractive index of the second lens respectively.

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to the field of optical imaging technology, and more particularly, to a near-eye optical system and a head-mounted display device. BACKGROUND

[0002] The chromatic aberration and distortion requirements of the VR optical scheme are relatively high, and currently, software pre-correction is mainly used. However, software pre-correction increases the power consumption of the optical system. Especially when the field of view angle of the optical system is relatively large, the requirements for the optical scheme will be more stringent without software pre-correction, which leads to a large increase in production difficulty and cost. SUMMARY

[0003] The purpose of the present application is to provide a new technical scheme of 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, and the second optical element is configured to be movable along the optical axis relative to the first optical element;

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

[0006] 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;

[0007] The first optical element satisfies: 0 < [(φ1+φ2) / (φ1-φ2)]*(n2-n1) ≤ 1, where φ1 and n1 are the optical power and refractive index of the first lens respectively, and φ2 and n2 are the optical power and refractive index of the second lens respectively.

[0008] Optionally, the optical power φ1 of the first lens is positive, and the optical power φ2 of the second lens is negative.

[0009] Optionally, the ratio of the center thickness to the 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 between the first optical element and the second optical element.

[0011] The first optical element and the second optical element have a target interval A, 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, which emits light rays for image display.

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

[0014] Optionally, the near-eye optical system further comprises a third optical element, which is arranged between the second optical element and the display and is 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 third optical element has an optical power φ4, and φ4>0.

[0016] Optionally, in the case where the third optical element only uses the fourth lens, the fourth lens has an optical power φ4, and φ4>0.

[0017] Optionally, the second optical element has an optical power φ3, and the near-eye optical system satisfies the following relationship:

[0018] 0.2≤φ1 / (φ3+φ4)≤3.

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

[0020] In the case where the light rays emitted by the display are natural light, the light emitting surface of the display is provided with a superposition element for converting the natural light into circularly polarized light, and the superposition element comprises at least a phase retarder and a linear polarizer.

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

[0022] The phase retarder and the polarization reflection element are arranged in a stack and are arranged on a surface of the second lens close to the display.

[0023] Optionally, the near-eye optical system further comprises a polarizer, which is arranged on a side of the polarization reflection element away from the phase retarder, and the polarizer, the polarization reflection element and the phase retarder are arranged in a stack to form a composite film.

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

[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] The near-eye optical system according to the first aspect.

[0028] The application has the following beneficial effects:

[0029] The near-eye optical system provided by the embodiments of the application can realize low distortion, low chromatic aberration and variable focus optical effects by reasonable layout of the optical framework and reasonable constraints on the refractive index and optical power of the first optical element.

[0030] Other features and advantages of the present application will become apparent from the following detailed description of illustrative embodiments thereof, which proceeds with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0031] The accompanying drawings incorporated in and forming a part of the specification illustrate embodiments of the present application and, together with the description, serve to explain the principles of the present application.

[0032] Figure 1 Structure diagram of the near-eye optical system provided by the embodiments of the application;

[0033] Figure 2 Schematic diagram of the setting mode of the composite film provided by the embodiments of the application;

[0034] Figure 3 One of the point array diagrams of the near-eye optical system provided by Embodiment 1 of the application;

[0035] Figure 4 One of the modulation transfer function (MTF) curve diagrams of the near-eye optical system provided by Embodiment 1 of the application;

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

[0037] Figure 6 One of the sagittal chromatic aberration diagrams of the near-eye optical system provided by Embodiment 1 of the application;

[0038] Figure 7 The second point array diagram of the near-eye optical system provided by Embodiment 1 of the application;

[0039] Figure 8 The second modulation transfer function (MTF) curve diagram of the near-eye optical system provided by Embodiment 1 of the application;

[0040] Figure 9 The second field curvature and distortion diagram of the near-eye optical system provided by Embodiment 1 of the application;

[0041] Figure 10 The second sagittal chromatic aberration diagram of the near-eye optical system provided by Embodiment 1 of the application;

[0042] Figure 11 One of the spot array diagrams of the near-eye optical system provided for Embodiment 2 of the present application;

[0043] Figure 12 One of the modulation transfer function (MTF) curve diagrams of the near-eye optical system provided for Embodiment 2 of the present application;

[0044] Figure 13 One of the field curvature and distortion diagrams of the near-eye optical system provided for Embodiment 2 of the present application;

[0045] Figure 14 One of the sagittal chromatic aberration diagrams of the near-eye optical system provided for Embodiment 2 of the present application;

[0046] Figure 15 Two of the spot array diagrams of the near-eye optical system provided for Embodiment 2 of the present application;

[0047] Figure 16 Two of the modulation transfer function (MTF) curve diagrams of the near-eye optical system provided for Embodiment 2 of the present application;

[0048] Figure 17 Two of the field curvature and distortion diagrams of the near-eye optical system provided for Embodiment 2 of the present application;

[0049] Figure 18 Two of the sagittal chromatic aberration diagrams of the near-eye optical system provided for Embodiment 2 of the present application;

[0050] Figure 19 Two of the structural schematic diagrams of the near-eye optical system provided for Embodiment of the present application;

[0051] Figure 20 One of the spot array diagrams of the near-eye optical system provided for Embodiment 3 of the present application;

[0052] Figure 21 One of the modulation transfer function (MTF) curve diagrams of the near-eye optical system provided for Embodiment 3 of the present application;

[0053] Figure 22 One of the field curvature and distortion diagrams of the near-eye optical system provided for Embodiment 3 of the present application;

[0054] Figure 23 One of the sagittal chromatic aberration diagrams of the near-eye optical system provided for Embodiment 3 of the present application;

[0055] Figure 24 Two of the spot array diagrams of the near-eye optical system provided for Embodiment 3 of the present application;

[0056] Figure 25 Two of the modulation transfer function (MTF) curve diagrams of the near-eye optical system provided for Embodiment 3 of the present application;

[0057] Figure 26 Figure 2 is a field curvature and distortion map of the near-eye optical system provided in Example 3 of the present application;

[0058] Figure 27 Figure 4 is a sagittal chromatic aberration map of the near-eye optical system provided in Example 3 of the present application.

[0059] BRIEF DESCRIPTION OF DRAWINGS

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

[0061] 1, display; 2, screen protection element; 3, third lens; 4, second lens; 5, first lens; 6, human eye; 7, polarizing reflecting element; 8, phase retarder; 9, light splitting 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 figures. It should be noted that the relative arrangements, numerical expressions, and numerical values of the components and steps set forth in these embodiments are not limiting to the scope of the present application unless specifically stated otherwise.

[0063] The following description of at least one exemplary embodiment is merely exemplary in nature and is in no way intended to limit the application or its application or uses.

[0064] Techniques and equipment known to those of ordinary skill in the relevant art can not be discussed in detail, but should be considered part of the specification where appropriate.

[0065] In all of the examples shown and discussed herein, any specific values should be interpreted as merely exemplary and not as a limitation. Thus, other examples of the exemplary embodiments can have different values.

[0066] It should be noted that like numbers and letters refer to like items throughout the drawings, and once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0067] The near-eye optical system and head-mounted display device provided in the embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0068] According to one aspect of the embodiments of this application, a near-eye optical system is provided, which is suitable for wearable devices. The wearable device may be a head-mounted display (HMD), such as a VR head-mounted display. The VR head-mounted display may include, for example, VR smart glasses or a VR smart helmet, etc. This application does not specifically limit the form of the head-mounted display device.

[0069] The near-eye optical system proposed in this application's embodiments is described in [reference]. 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. 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 disposed on one surface of the third lens 3, with the phase retarder 8 located between the beam splitter 9 and the polarizing reflective element 7. The first optical element 100 should satisfy: 0 < [(φ1+φ2) / (φ1-φ2)]*(n2-n1) ≤ 1, where φ1 and n1 are the optical power and refractive index of the first lens 5, respectively, and φ2 and n2 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 onto the third lens 3, or it can be... Figure 1 As shown, the beam splitter 9 is positioned on the side of the third lens 3 closest to the first optical element 100. A more preferred embodiment is to position the beam splitter 9 on one surface of the third lens 3, allowing it to move along the optical axis with the third lens 3.

[0071] According to the near-eye optical system provided in the above embodiments of this application, the first optical element 100 and the second optical element 200, together with the phase delayer 8 and the polarization reflection element 7, can form a folded optical path. In this way, the projected light can be folded back between the first optical element 100 and the second optical element 200. The introduction of the folded optical path can reduce the size of the near-eye optical system along the optical axis while ensuring good imaging quality.

[0072] In the near-eye optical system provided in the above embodiments, see Figure 1The near-eye optical system comprises at least two optical elements, i.e., the first optical element 100 and the second optical element 200. The first optical element 100 is located close to the eye 6. The first optical element 100 comprises a first lens 5 and a second lens 4 arranged along the same optical axis. The two lenses satisfy the constraint condition: 0 < [(φ1+φ2) / (φ1-φ2)]*(n2-n1)≤1, where φ1 and n1 are the optical power and the refractive index of the first lens 5, and φ2 and n2 are the optical power and the refractive index of the second lens 4. The constraint condition of the optical parameters can correct the chromatic aberration and distortion of the image well, so that the near-eye optical system has low chromatic aberration and low distortion.

[0073] The near-eye optical system provided by the embodiment has low chromatic aberration and low distortion, and does not need to use software to correct the image.

[0074] The second optical element 200 is located away from the eye 6 relative to the first optical element 100. The second optical element 200 is designed to move away from or close to the first optical element 100 along the optical axis, so as to realize the 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 obtain good visual experience.

[0075] The near-eye optical system provided by the embodiment can obtain low chromatic aberration and low distortion images when the second optical element 200 moves to any position along the optical axis, even when the second optical element 200 moves to the two extreme positions of the refractive power.

[0076] Referring to FIGS. 1 and 2, Figure 5 and Figure 9 The absolute value of the distortion of the near-eye optical system provided by the embodiment is less than 3%. Referring to FIGS. 3 and 4, Figure 6 and Figure 10 The maximum chromatic aberration value of the near-eye optical system provided by the embodiment is less than 24 μm.

[0077] In the above embodiment, the second optical element 200 comprises at least one optical lens and a light splitting element 9. The light splitting element 9 is, for example, a half-mirror.

[0078] Specifically, the second optical element 200 can be composed of a third lens 3 and a light splitting element 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 light splitting element 9 is directly attached or coated on the surface of the third lens 3 close to the first optical element 100 (that is, the surface on the left side of the third lens 3 shown in the figure), see Figure 1 Figure 1 .

[0079] The light splitting element 9 can move with the third lens 3, and the design is based on the fact that the light incident into the near-eye optical system passes through the light splitting element 9 twice, and the light splitting element 9 can provide a larger optical power. The design of moving the light splitting element 9 is beneficial to realize zoom.

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

[0081] The driving force for driving the second optical element 200 to move can be realized by an external driving mechanism or can be realized by manual driving, and the present application does not limit this.

[0082] The near-eye optical system provided by the embodiment of the present application can realize a larger field of view angle on the premise of miniaturized design, and can have optical effects of low chromatic aberration and low distortion, and can also realize the effect of variable zoom.

[0083] According to the near-eye optical system provided by the embodiment of the present application, by reasonably arranging the optical framework and reasonably constraining the refractive index and optical power of the first optical element 100, the optical effects of low distortion, low chromatic aberration and variable zoom can be realized.

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

[0085] The light splitting element 9 can transmit a part of light and reflect another part of light.

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

[0087] It should be noted that the reflectivity and transmissivity of the light splitting element 9 can be flexibly adjusted according to specific needs, and the present application does not limit this in the embodiment.

[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 retarders such as a half-wave plate and the like according to requirements.

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

[0091] The polarization reflection element 7 is a polarization reflector that reflects horizontally linearly polarized light and transmits vertically linearly polarized light, or a polarization reflector that reflects linearly polarized light at any specific angle and transmits linearly polarized light in the direction perpendicular to the specific angle.

[0092] In the embodiment of the present application, the phase retarder 8 and the polarization reflection element 7 can be used to analyze and transmit light in cooperation.

[0093] It is emphasized that the optical elements, i.e., the light splitting element 9, the phase retarder 8, and the polarization reflection element 7, can form a folded light path on the side close to the human eye 6, and the arrangement positions of the optical elements are flexible, but it is necessary to ensure that the phase retarder 8 is between the light splitting element 9 and the polarization reflection element 7.

[0094] In some examples of the present application, the optical power φ1 of the first lens 5 is positive, and the optical power φ2 of the second lens 4 is negative.

[0095] According to the near-eye optical system provided by the embodiment of the present application, the first optical element 100 on the side of the human eye 6 is designed to include the first lens 5 and the second lens 4, as shown in 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 relative to the first lens 5, the optical power φ1 of the first lens 5 is greater than 0, and the optical power φ2 of the second lens 4 is less than 0. This combination of positive and negative optical powers on the side close to the human eye 6 is beneficial to correcting the aberration of the near-eye optical system. In addition, in cooperation with the constraint condition 0 < [(φ1+φ2) / (φ1-φ2)]*(n2-n1)≤1, the chromatic aberration and distortion of the near-eye optical system can be further reduced, so that the imaging quality can be improved 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 greater than or equal to 1.

[0097] According to the near-eye optical system provided by the embodiment of the present application, as shown in Figure 1The second optical element can 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 third lens 3 that can move, the distortion value of the edge field of view can be corrected, and the image quality can be improved.

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

[0099] In some examples of the present application, referring to 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 folded between the first optical element 100 and the second optical element 200; the first optical element 100 and the second optical element 200 have a target interval A, and the refractive index of the medium in the target interval A is n, and n≥1.

[0100] According to the above example, referring to Figure 1 The light emitted by the display 1 located at the rightmost side for imaging display is projected into the second optical element 200, the light is folded 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 length of the near-eye optical system can be effectively reduced.

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

[0102] The display 1 can be an LCD, an LED, an OLED, a Micro-OLED, a ULED, or other self-luminous screens, or a DMD or other reflective screens.

[0103] The display 1 can be an LCD, an LED, an OLED, a Micro-OLED, a ULED, or other self-luminous screens, or a DMD or other reflective screens.

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

[0105] In some examples of the present application, referring to Figure 19The near-eye optical system further comprises a third optical element disposed between the second optical element 200 and the display 1 and 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 third optical element has an optical power φ4, and φ4>0.

[0106] According to the above examples, referring to Figure 19 A third optical element can be introduced between the light-emitting side of the display 1 and the second optical element 200. The third optical element can comprise one or more optical lenses. The introduction of the third optical element can 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. In this way, the near-eye optical system can have good imaging quality in the full field of view.

[0108] In some examples of the present application, referring to Figure 19 In the case where the third optical element only uses the fourth lens 10, the optical power of the fourth lens 10 is φ4, and φ4>0.

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

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

[0111] It should be noted that the addition of optical elements on one side of the display 1 of the near-eye optical system can also appropriately improve the field of view and resolution of the near-eye optical system.

[0112] In some examples of the present application, the optical power of the second optical element 200 is φ3, and the near-eye optical system satisfies the following relationship: 0.2≤φ1 / (φ3+φ4)≤3.

[0113] According to the above examples, by the constraint conditions of the second optical element 200 and the third optical element, the optical power can be reasonably distributed, and the process implementation can be improved.

[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, the light-emitting surface of the display 1 is provided with a superposition element for converting the natural light into circularly polarized light, and the superposition element at least comprises a phase retardation plate and a linear polarization plate.

[0115] Referring toFigure 1 and Figure 7 When the display 1 emits natural light, the natural light needs to be first converted into circularly polarized light before being emitted into the left optical elements, and the light emitted by the first optical element finally enters the human eye 6 for imaging.

[0116] According to the above example, the phase retardation plate and the linear polarizing plate are combined into a stacked element and attached to the light-emitting surface of the display 1, which can reduce the assembly difficulty and realize the simultaneous placement of two optical elements in one assembly.

[0117] The transmission axis direction of the linear polarizing plate can be along the horizontal direction, the vertical direction, or any other direction.

[0118] The phase retardation plate is, for example, a quarter-wave plate, which can realize the conversion of linearly polarized light into circularly polarized light and the conversion of circularly polarized light into linearly polarized light.

[0119] Specifically, the fast axis or slow axis direction of the phase retardation plate arranged on the light-emitting surface of the display 1 is at an angle of 45° with the transmission axis direction of the linear polarizing plate.

[0120] In some examples of the present application, the light splitting element 9 is arranged on the surface of the third lens 3 away from the display 1. The phase retarder 8 and the polarized reflection element 7 are arranged in a stacked manner on the surface of the second lens 4 close to the display 1, as shown in Figure 2 .

[0121] According to the above example, no flat plate support is needed to support the light splitting element 9, the phase retarder 8, and the polarized reflection element 7 in the entire optical structure, which can simplify the optical structure.

[0122] The light splitting element 9 can be attached or plated on the surface of the third lens 3 away from the display 1, as shown in Figure 1 .

[0123] The polarized reflection element 7 and the phase retarder 8 are laminated and glued on the same surface of the second lens 4, specifically, attached to the surface of the second lens 4 close to the display 1, which is conducive to the alignment adjustment between the two, as shown in Figure 2 . The phase retarder 8 is, for example, a quarter-wave plate. The polarized reflection element 7 is, for example, a polarized reflection 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 by a support, and the phase retarder 8 and the polarization reflection element 7 can be laminated together and arranged on the side of the second lens 4 close to the display 1 by a support, as shown in Figure 1 .

[0125] In some examples of the present application, the near-eye optical system further comprises a polarizer 11 arranged on the side of the polarization reflection element 7 away from the phase retarder 8, and the polarizer 11, the polarization reflection element 7 and the phase retarder 8 are laminated to form a composite film.

[0126] Referring to Figure 2 , the near-eye optical system can further comprise a polarizer 11. The introduction of the polarizer 11 can reduce stray light, which is advantageous for improving the final imaging quality.

[0127] Among them, the polarizer 11 is, for example, a linear polarizer, and the transmission axis direction can be along the horizontal direction, the vertical direction or any other direction.

[0128] Among them, the polarizer 11 can be arranged on the side of the polarization reflection element 7 away from the phase retarder 8, and the polarizer 11, the polarization reflection element 7 and the phase retarder 8 are laminated to form a composite film.

[0129] Of course, please continue to refer to Figure 2 , the above-mentioned composite film can also introduce an anti-reflection film 12.

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

[0131] In some examples of the present application, the absolute value of the 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 by the embodiment of the present application, at least three optical lenses are used, that is, the first lens 5, the second lens 4 and the third lens 3 shown in Figure 1 . Of course, the near screen side of the near-eye optical system can also introduce a fourth lens 10, as shown in Figure 19 .

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

[0134] The three lenses used in the near-eye optical system have a material refractive index and Abbe number in the range of 1.4 < n < 2.0, 20 < v < 75.

[0135] The refractive index and Abbe number of the first lens 5 are n1 = 1.54, v1 = 55.7. The refractive index and Abbe number of the second lens 4 are n2 = 1.64, v2 = 23. The refractive index and Abbe number of the third lens 5 are n3 = 1.54, v3 = 56.3.

[0136] The central thickness T1 of the first lens 5 is in the range of 1 mm ≤ T1 ≤ 8 mm, and includes two optical surfaces, i.e. a first surface and a second surface, which can be aspherical surfaces. The first surface is away from the display 1, and the second surface is close to the display 1.

[0137] Optionally, an anti-reflection film can be attached to the two surfaces of the first lens 5.

[0138] The central thickness T2 of the second lens 4 is in the range of 1 mm ≤ T2 ≤ 10 mm, and includes two optical surfaces, i.e. a third surface and a fourth surface, which can be aspherical or planar surfaces. The third surface is away from the display 1, and the fourth surface is close to the display 1.

[0139] Optionally, referring to Figure 2 An anti-reflection film 12, a phase retarder 8, a polarized reflection element 7 (transmits P light and reflects S light), and a polarizer 11 (transmits P light) can be provided on the third surface. An anti-reflection film can be provided on the fourth surface.

[0140] The central thickness T3 of the third lens 3 is in the range of 1 mm ≤ T3 ≤ 8 mm, and includes two optical surfaces, i.e. a fifth surface and a sixth surface, which can be aspherical surfaces. The fifth surface is away from the display 1, and the sixth surface is close to the display 1.

[0141] Optionally, an anti-reflection film can be attached to the fifth surface, and a light splitting element 9 (i.e. a half mirror) can be attached or coated on the sixth surface.

[0142] Referring to 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, becomes linearly polarized light (S light) through the phase retarder 8 (quarter-wave plate) on the third surface of the second lens 4, is reflected through the polarized reflection element 7, becomes circularly polarized light again through the phase retarder 8, is reflected through the light-splitting element 9 on the sixth surface 32 of the third lens 3, becomes linearly polarized light (P light) again through the phase retarder 8, is transmitted through the fourth surface of the second lens 4 and the first lens 5, and enters the human eye 6.

[0144] The optical performance of the near-eye optical system provided in 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 seen from Figure 1 , which comprises 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 is capable of moving relative to the first optical element 100 along the optical axis;

[0147] The first optical element 100 comprises a first lens 5 and a second lens 4, as shown in Figure 2 , a polarizer 11, a polarized reflection element 7 and a phase retarder 8 are stacked to form a composite film on the third surface of the second lens 4; the optical power φ1 of the first lens 5 is positive, and the optical power φ2 of the second lens 4 is negative;

[0148] The second optical element 200 comprises a third lens 3 and a light-splitting element 9 arranged on the sixth surface of the third lens 3; the ratio of the central thickness to the edge thickness of the third lens 3 is ≥1;

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

[0150] The specific optical parameters of the near-eye optical system of this embodiment 1 are shown.

[0151] Table 1

[0152]

[0153]

[0154] The optical performance of the near-eye optical system provided by the embodiment 1 is shown by the point array diagram, the MTF curve diagram, the field curvature and distortion, and the axial chromatic aberration, respectively.

[0155] The point array diagram refers to a dispersed diagram formed by a point, in which many light rays emitted by the point are no longer concentrated on the same point on the image plane due to aberration after passing through the optical system, and is mainly used for evaluating the imaging quality of the projection optical system.

[0156] The MTF curve diagram is a modulation transfer function diagram, which represents the imaging clarity of the optical system by the contrast of black and white lines.

[0157] The axial chromatic aberration refers to the magnification chromatic aberration, which mainly refers to a root complex main light ray in the object side, which becomes multiple light rays when emitted on the image side due to the dispersion of the refractive system, and the difference between the focal point positions of blue light and red light on the image plane.

[0158] Figure 3 to Figure 6 An extreme case in which the second optical element 200 moves to change the refractive power in the near-eye display system provided by the embodiment 1 is shown.

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

[0160] Referring to Figure 4 , the MTF is greater than 0.6 at 24 lp / mm.

[0161] Referring to Figure 5 , the maximum distortion occurs at 1 field of view, and the absolute value is less than 3%.

[0162] Referring to Figure 6 , the maximum chromatic aberration value is less than 24 μm.

[0163] Figure 8 to Figure 11 Another extreme case in which the second optical element moves to change the refractive power in the near-eye display system provided by the embodiment 1 is shown.

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

[0165] Referring to Figure 9 , the MTF is greater than 0.3 at 24 lp / mm.

[0166] Referring to Figure 10 , the maximum distortion occurs at 1 field of view, and the absolute value is less than 3%.

[0167] Referring to Figure 11 , the maximum chromatic aberration value is less than 24 μm.

[0168] Embodiment 2

[0169] The near-eye optical system of this embodiment 2 has the same optical architecture as that of embodiment 1, which can be seen from Figure 1 The difference is that the optical parameters are different, which can be seen from 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 shown below through spot array diagram, MTF curve diagram, field curvature and distortion, and sagittal chromatic aberration, respectively.

[0174] Figure 11 to Figure 14 This shows one extreme case of the near-eye display system provided by this embodiment 2, in which the second optical element 200 moves to change the refractive power.

[0175] Referring to Figure 11 , the maximum value of the image point in the spot diagram is less than 8 μm.

[0176] Referring to Figure 12 , the MTF is >0.55 at 24 lp / mm.

[0177] Referring to Figure 13 , the maximum distortion occurs at 1 field of view, and the absolute value is less than 3%.

[0178] Referring to Figure 14 , the maximum chromatic aberration value is less than 24 μm.

[0179] Figure 15 to Figure 18 This shows another extreme case of the near-eye display system provided by this embodiment 2, in which the second optical element 200 moves to change the refractive power.

[0180] Referring to Figure 15 , the maximum value of the image point in the spot diagram is less than 30 μm.

[0181] Referring to Figure 16 , the MTF is >0.1 at 24 lp / mm.

[0182] Referring to Figure 17 , the maximum distortion occurs at 1 field of view, and the absolute value is less than 3%.

[0183] Referring to Figure 18 , the maximum chromatic aberration value is less than 24 μm.

[0184] Embodiment 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 piece of lens, i.e., a fourth lens 10, is used in the third optical element. The optical architecture shown in this embodiment 3 is shown in FIG. 3. Figure 19 .

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

[0187] Table 3

[0188]

[0189]

[0190] The optical performance of the near-eye optical system provided by this embodiment 3 is shown below through spot diagram, MTF curve, field curvature and distortion, and sagittal chromatic aberration, respectively.

[0191] Figure 20 to Figure 23 An extreme case of the near-eye display system provided by this embodiment 3 is shown, in which the second optical element 200 moves to change the dioptric power.

[0192] Referring to Figure 20 , the maximum value of the image point in the spot diagram is less than 7 μm.

[0193] Referring to Figure 21 , the MTF is >0.7 at 24 lp / mm.

[0194] Referring to Figure 22 , the maximum distortion occurs at 1 field of view, and the absolute value is less than 3%.

[0195] Referring to Figure 23 , the maximum chromatic aberration value is less than 24 μm.

[0196] Figure 24 to Figure 27 Another extreme case of the near-eye display system provided by this embodiment 3 is shown, in which the second optical element 200 moves to change the dioptric power.

[0197] Referring to Figure 24 , the maximum value of the image point in the spot diagram is less than 17 μm.

[0198] Referring to Figure 25 , the MTF is >0.3 at 24 lp / mm.

[0199] Referring to Figure 26 , the maximum distortion occurs at 1 field of view, and the absolute value is less than 3%.

[0200] Referring to Figure 27 , the maximum chromatic aberration value is less than 24 μm.

[0201] According to the above-mentioned embodiments 1 to 3, the near-eye optical system provided in the present application has low chromatic aberration and low distortion, and can ensure good optical performance when the second optical element 200 moves to realize zooming.

[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 comprises a VR smart glasses or a VR smart helmet, and the present application does not limit the same.

[0205] The specific implementation of the head-mounted display device of the embodiments of the present application can refer to the above-mentioned embodiments of the near-eye optical system, and therefore has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments. Therefore, it is not necessary to repeat them here.

[0206] In the above embodiments, the differences between the embodiments are mainly described. The different optimization features between the embodiments can be combined to form a better embodiment as long as they are not contradictory. In order to make the writing concise, it is not necessary to repeat them here.

[0207] Although some specific embodiments of the present application have been described in detail through examples, those skilled in the art should understand that the above examples are only for illustration, but not for limiting the scope of the present application. Those skilled in the art should understand that the above embodiments can 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 includes a first optical element (100), a polarization reflective element (7), a phase retarder (8), and a second optical element (200) arranged along the same optical axis, the second optical element (200) being 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) includes a third lens (3) and a beam splitter (9) disposed on a surface of the third lens (3), and the phase retarder (8) is located between the beam splitter (9) and the polarization reflection element (7); The first optical element (100) satisfies: 0<[(φ1+φ2) / (φ1-φ2)]*(n2-n1)≤1, where φ1 and n1 are the optical power and refractive index of the first lens (5) respectively, and φ2 and n2 are the optical power and refractive index of the second lens (4) respectively; The near-eye optical system also includes a display (1); The near-eye optical system further includes 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 includes a fourth lens (10), the fourth lens (10) having an optical power of φ4, and φ4 > 0; The optical power of the second optical element (200) is φ3, and the near-eye optical system satisfies the following relationship: 0.2≤φ1 / (φ3+φ4)≤3.

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); The first optical element (100) and the second optical element (200) have a target interval A, and the refractive index of the medium within the target interval A is n, and n≥1.

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

6. The near-eye optical system according to claim 1, 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 to convert the natural light into circularly polarized light, and the superimposed element includes at least a phase delay plate and a linear polarizer.

7. The near-eye optical system according to claim 1, characterized in that, The beam splitter (9) is disposed on the surface of the third lens (3) away from the display (1); The phase delayer (8) and the polarization reflection element (7) are stacked and disposed on the surface of the second lens (4) near the display (1).

8. The near-eye optical system according to claim 1, characterized in that, The near-eye optical system also includes a polarizer (11), which is disposed on the side of the polarization reflection element (7) away from the phase retarder (8), and the polarizer (11), the polarization reflection element (7) and the phase retarder (8) are stacked to form a composite film.

9. The near-eye optical system according to claim 1, characterized in that, The absolute value of the distortion of the near-eye optical system is less than 3%, and the maximum chromatic difference is less than 24 μm.

10. A head-mounted display device, characterized in that, include: shell; as well as The near-eye optical system as described in any one of claims 1-9.

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