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 imaging element and a second imaging element arranged in sequence along the same optical axis; the first imaging element comprises at least one lens; the second imaging element comprises a second lens and a third lens, and a light splitting element, a first phase retarder and a polarization reflection element arranged in sequence between the second lens and the third lens; wherein the optical power of the third lens away from the surface of the second lens is φ1, the optical power of the third lens close to the surface of the second lens is φ2, and the optical power of the surface of the second lens close to the first imaging element is φ3, and φ1, φ2 and φ3 satisfy: -1 < φ1 / (φ2+φ3) < 0. The near-eye optical system provided by the embodiments of the present application realizes the optical imaging effect of low chromatic aberration and low distortion under a certain field of view angle.

Description

TECHNICAL FIELD

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

[0002] The VR technology has a relatively high requirement on chromatic aberration and distortion of an internal optical system. In the prior art, software pre-correction is provided to improve the chromatic aberration and distortion of the optical system. However, in actual application, it is found that providing the software pre-correction increases the power consumption of the entire optical system, especially when the field of view is relatively large, the requirement on the optical performance of the optical system is more stringent without the software pre-correction, thereby increasing the production difficulty and cost. SUMMARY

[0003] The purpose of the present application is to provide a new technical solution of a near-eye optical system and a head-mounted display device, which can realize low chromatic aberration and low distortion optical imaging effect under a large field of view.

[0004] In a first aspect, the present application provides a near-eye optical system. The near-eye optical system comprises a first imaging element and a second imaging element arranged in sequence along the same optical axis;

[0005] The first imaging element comprises at least one lens;

[0006] The second imaging element comprises a second lens and a third lens, and a light splitting element, a first phase retarder and a polarization reflection element arranged in sequence between the second lens and the third lens;

[0007] Wherein, the optical power of the surface of the third lens away from the second lens is φ1, the optical power of the surface of the third lens close to the second lens is φ2, and the optical power of the surface of the second lens close to the first imaging element is φ3, and φ1, φ2 and φ3 satisfy: -1 < φ1 / (φ2+φ3) < 0.

[0008] Optionally, the radius of the surface of the third lens away from the second lens is R1, and the radius of the surface of the third lens close to the second lens is R2;

[0009] The radius of the surface of the second lens close to the third lens is R3, and the radius of the surface of the second lens close to the first imaging element is R4;

[0010] The R1, R2, R3 and R4 satisfy: {(R1-R2) / (R3-R4)} < 10. 2

[0011] Optionally, the first imaging element comprises a first lens;​

[0012] the thinnest position on the first lens has a first thickness value T min , the thickest position on the first lens has a second thickness value T max , the first thickness value T min and the second thickness value T max satisfy: 0.03≤|T min -T max | / T max <1.

[0013] Optionally, the radius of any surface of the first lens is R, the radius of the surface of the second lens close to the first imaging element is R4, R and R4 satisfy: 20<│R4│+│R│<100.

[0014] Optionally, the near-eye optical system further comprises a display, the display is located on the side of the first imaging element away from the second imaging element.

[0015] Optionally, the polarization reflection element is arranged on the surface of the third lens close to the display, and the surface of the third lens away from the display is a concave surface.

[0016] Optionally, the light splitting element is arranged on the surface of the second lens close to the display, the first phase retarder and the polarization reflection element are arranged on the surface of the third lens close to the display.

[0017] Optionally, the near-eye optical system further comprises a first polarization element, the first polarization element is located in the second imaging element, and the first polarization element and the polarization reflection element and the light splitting element are arranged to form a composite film material, the polarization reflection element is located between the first polarization element and the first phase retarder.

[0018] Optionally, the light splitting element is arranged on the surface of the second lens close to the display, the first phase retarder is arranged on the surface of the second lens away from the display, and the polarization reflection element is arranged on the surface of the third lens close to the display.

[0019] Optionally, the near-eye optical system further comprises a first polarization element, the first polarization element is located in the second imaging element, and the first polarization element and the polarization reflection element are arranged to form a composite film material, the polarization reflection element is located between the first polarization element and the first phase retarder.

[0020] Optionally, the display is configured to be capable of emitting circularly polarized light or natural light.

[0021] When the light emitted by the display is natural light, a superposition element is arranged between the display and the first imaging element, which is capable of converting the natural light into circularly polarized light, and the superposition element comprises a second polarization element and a second phase retarder.

[0022] Optionally, 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 70 μm.

[0023] Optionally, the first imaging element comprises at least one lens, and the first imaging element comprises at least one reverse curve.

[0024] Optionally, at least one surface of the first lens is a reverse curve.

[0025] Optionally, the reverse curve satisfies D2 / D1<1 and H1 / H2<1; wherein D1 is the maximum semi-oral radius of the reverse curve, D2 is the distance from the position of the reverse curve point to the center of the lens, H1 is the minimum sag of the reverse curve, and H2 is the maximum sag of the reverse curve.

[0026] Optionally, the total optical power of the near-eye optical system is φ, and 0≤φ≤0.6;

[0027] The lens of the non-folding optical path in the near-eye optical system comprises a first lens and a third lens;

[0028] The combined optical power of the first lens and the third lens is φ 13 , then φ 13 satisfies 0.01≤φ 13 / φ≤0.2.

[0029] In a second aspect, the present application provides a head-mounted display device. The head-mounted display device comprises:

[0030] a housing; and

[0031] The near-eye optical system according to the first aspect.

[0032] The beneficial effects of the present application are:

[0033] According to the near-eye optical system provided by the embodiments of the present application, through the new optical architecture, especially the new optical parameter design of the second imaging element located on the side of the near pupil, the low chromatic aberration and low distortion optical imaging effect of the near-eye optical system can be realized under the premise of a larger field of view, so that the optical performance of the near-eye optical system can be improved.

[0034] Other features of the present application and its advantages will become apparent from the following detailed description of exemplary embodiments thereof, taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0035] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present specification and, together with the description, serve to explain the principles of the present specification.

[0036] Figure 1 Structure schematic diagram of near-eye optical system provided for an embodiment of the present application;

[0037] Figure 2 An embodiment schematic diagram for introducing optical elements forming a folded optical path in a near-eye optical system;

[0038] Figure 3 A point array diagram of the near-eye optical system provided; Figure 1 A modulation transfer function (MTF) diagram of the near-eye optical system provided;

[0039] Figure 4 A point array diagram of the near-eye optical system provided; Figure 1 A modulation transfer function (MTF) diagram of the near-eye optical system provided;

[0040] Figure 5 A field curvature and distortion diagram of the near-eye optical system provided; Figure 1 A field curvature and distortion diagram of the near-eye optical system provided;

[0041] Figure 6 A field curvature and distortion diagram of the near-eye optical system provided; Figure 1 A field curvature and distortion diagram of the near-eye optical system provided;

[0042] Figure 7 Another embodiment schematic diagram for introducing optical elements forming a folded optical path in a near-eye optical system;

[0043] Figure 8 Structure schematic diagram of near-eye optical system provided for an embodiment of the present application;

[0044] Figure 9 A point array diagram of the near-eye optical system provided; Figure 8 A modulation transfer function (MTF) diagram of the near-eye optical system provided;

[0045] Figure 10 A field curvature and distortion diagram of the near-eye optical system provided; Figure 8 A field curvature and distortion diagram of the near-eye optical system provided;

[0046] Figure 11 A field curvature and distortion diagram of the near-eye optical system provided; Figure 8 A field curvature and distortion diagram of the near-eye optical system provided;

[0047] Figure 12 A field curvature and distortion diagram of the near-eye optical system provided; Figure 8 A field curvature and distortion diagram of the near-eye optical system provided;

[0048] Figure 13 Structure schematic diagram of near-eye optical system provided for an embodiment of the present application;

[0049] Figure 14Point array map of the near-eye optical system provided in Figure 13 Point array map of the near-eye optical system provided in

[0050] Figure 15 Modulation transfer function (MTF) map of the near-eye optical system provided in Figure 13 Modulation transfer function (MTF) map of the near-eye optical system provided in

[0051] Figure 16 Curvature of field and distortion map of the near-eye optical system provided in Figure 13 Curvature of field and distortion map of the near-eye optical system provided in

[0052] Figure 17 Vernier chromatic aberration map of the near-eye optical system provided in Figure 13 Vernier chromatic aberration map of the near-eye optical system provided in

[0053] Figure 18 Structure schematic diagram No. 4 of the near-eye optical system provided in the embodiments of the present application

[0054] Figure 19 Point array map of the near-eye optical system provided in Figure 18 Point array map of the near-eye optical system provided in

[0055] Figure 20 Modulation transfer function (MTF) map of the near-eye optical system provided in Figure 18 Modulation transfer function (MTF) map of the near-eye optical system provided in

[0056] Figure 21 Curvature of field and distortion map of the near-eye optical system provided in Figure 18 Curvature of field and distortion map of the near-eye optical system provided in

[0057] Figure 22 Vernier chromatic aberration map of the near-eye optical system provided in Figure 18 Vernier chromatic aberration map of the near-eye optical system provided in

[0058] Figure 23 Schematic diagram of the concave surface in the near-eye optical system provided in the embodiments of the present application

[0059] BRIEF DESCRIPTION OF DRAWINGS

[0060] 01, diaphragm; 1, display; 2, screen protection element; 3, first lens; 31, first surface; 32, second surface; 4, second lens; 41, third surface; 42, fourth surface; 5, third lens; 51, fifth surface; 52, sixth surface; 6, light splitting element; 7, first phase retarder; 8, polarization reflecting element; 9, first polarization element; 10, anti-reflection element; 11, fourth lens; 111, seventh surface; 112, eighth surface. DETAILED DESCRIPTION

[0061] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. Note that the relative arrangement, numerical expressions, and numerical values of components and steps set forth in these embodiments are not limiting to the scope of the present application unless otherwise specifically stated.

[0062] 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 and uses.

[0063] Techniques and devices known to those of ordinary skill in the relevant art can not be discussed in detail herein, but should be considered as part of the specification.

[0064] In all of the compositions and methods shown and discussed herein, any particular value is to be construed as merely exemplary, and not a limitation. Other examples of the exemplary embodiments can have different values.

[0065] It should be noted that like reference numerals and letters refer to like items throughout the attached drawings, and thus once an item is defined in one drawing, it is not necessary that it be further discussed in subsequent drawings.

[0066] The near-eye optical system and the head-mounted display device provided by the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0067] According to an aspect of the embodiments of the present application, a near-eye optical system is provided, which can be used in a virtual reality display device, such as a VR head-mounted display device. Specifically, the VR head-mounted display device includes a VR smart glasses or a VR smart helmet, etc., and the embodiments of the present application do not limit the specific form of the head-mounted display device.

[0068] The near-eye optical system provided by the embodiments of the present application, as shown in Figure 1 , includes a first imaging element and a second imaging element arranged in sequence along the same optical axis. The first imaging element includes at least one lens. The second imaging element includes a second lens 4 and a third lens 5, and a light splitting element 6, a first phase retarder 7 and a polarization reflection element 8 arranged in sequence between the second lens 4 and the third lens 5; wherein the optical power of the third lens 5 away from the surface of the second lens 4 is φ1, the optical power of the third lens 5 close to the surface of the second lens 4 is φ2, and the optical power of the second lens 4 close to the surface of the first imaging element is φ3, and φ1, φ2 and φ3 satisfy: -1 < φ1 / (φ2+φ3) < 0.

[0069] The near-eye optical system provided in the above embodiment, from the perspective of its overall optical architecture, includes a first imaging element and a second imaging element spaced apart along the same optical axis. The first imaging element, for example, is located near the screen and needs to include at least one lens. Meanwhile, the second imaging element, located near the aperture 01, needs to include two lenses. In other words, the entire near-eye optical system requires at least three lenses.

[0070] For example, four lenses may be used in the near-eye optical system. In this case, the additional lens may be provided in the first imaging element. Figure 18 , specifically, it can be located on the side of the first lens 3 away from the second lens 4. That is, the first imaging element can also use two lenses.

[0071] It should be noted that the near-eye optical system provided in the embodiment of the present application requires at least three lenses. However, in actual applications, the number of lenses can be increased according to specific needs.

[0072] As the number of lenses increases, the imaging effect can be improved and the total optical length of the system can be appropriately reduced, but the weight and production cost of the entire near-eye optical system may increase.

[0073] As a preferred solution of the present application, three lenses can be used in the near-eye optical system. In this case, the optical performance of the near-eye optical system is better.

[0074] According to the near-eye optical system provided in an embodiment of the present application, it is a folded optical path structure, in which a second imaging element is provided on one side of the near aperture 01, and a plurality of optical elements for forming a folded optical path are introduced into the second imaging element, such as the above-mentioned spectrometer element 6, the first phase delay element 7 and the polarization reflection element 8.

[0075] Specifically, see Figure 1 In the second imaging element, the third lens 5 is a lens close to the aperture 01, the second lens 4 is a lens far from the aperture 01, the beam splitter 6, the first phase retarder 7 and the polarizing reflective element 8 are arranged between the optical path formed by the second lens 4 and the third lens 5, and the first phase retarder 7 is located between the beam splitter 6 and the polarizing reflective element 8. In this optical structure, the third lens 5 is far from the surface of the second lens 4 (see Figure 1 The sixth surface 52 shown in FIG) has a focal length of φ1, and the surface of the third lens 5 close to the second lens 4 (see FIG) Figure 1 The optical power of the fifth surface 51 shown in FIG is φ2, and the surface of the second lens 4 close to the first imaging element (see FIG.Figure 1 The optical power of the third surface 41 shown in the middle is φ3, and the three optical powers φ1, φ2 and φ3 in the scheme provided in the embodiments of the present application satisfy: -1< φ1 / (φ2+φ3)< 0. On this basis, the near-eye optical system can have low chromatic aberration and low distortion optical performance while ensuring a certain field of view.

[0076] The near-eye optical system provided in the embodiments of the present application has the advantages of small volume based on the optical architecture of the folded optical path, and can achieve thin and light design of a virtual reality display device (VR device) using the near-eye optical system, which is more suitable for users to wear and use, and can improve the comfort of wearing and does not cause fatigue after a long time of wearing. More notably, the new design of the two lens parameters in the folded optical path in the present application can improve the optical performance of imaging.

[0077] The near-eye optical system provided in the embodiments of the present application is a folded optical path, and in addition to containing at least three lenses for imaging, the near-eye optical system also contains optical devices such as a light splitting element 6, a first phase retarder 7 and a polarization reflection element 8 for forming a folded optical path.

[0078] The optical devices described above are usually in the form of a film material, which can be used to form a folded optical path in the second imaging element, so that the light rays are folded therein to extend the propagation path of the light rays, which is beneficial to the final clear imaging.

[0079] The light splitting element 6 is, for example, a semi-transparent and semi-reflective film.

[0080] It should be noted that the reflectivity and transmissivity of the light splitting element 6 can be flexibly adjusted according to specific needs, and the embodiments of the present application do not limit this.

[0081] The first phase retarder 7 is, for example, a quarter-wave plate.

[0082] Of course, the first phase retarder 7 here can also be set to other phase retarders such as a half-wave plate according to needs.

[0083] In the near-eye optical system provided in the embodiments of the present application, referring to Figure 1 The first phase retarder 7 is located in the second imaging element close to the side of the diaphragm 01, and can be used to change the polarization state of the light rays. For example, it is used to convert linearly polarized light into circularly polarized light, or to convert circularly polarized light into linearly polarized light.

[0084] The polarization reflection element 8 is, for example, a linear polarizer, which is a polarization reflection element that reflects horizontally linearly polarized light and transmits vertically linearly polarized light, or any other polarization reflection element that reflects linearly polarized light at a specific angle and transmits linearly polarized light at a direction perpendicular to the specific angle.

[0085] According to the near-eye optical system provided in the embodiments of the present application, by means of a new optical architecture, especially by means of a new optical parameter design of the second imaging element on one side of the near pupil 01, low chromatic aberration and low distortion optical imaging effects can be achieved under the premise of a certain field of view, so as to improve the optical performance of the entire near-eye optical system.

[0086] The larger field of view range in the present application is, for example, 50°-80°.

[0087] In some examples of the present application, referring to Figure 1 , the third lens 5 has a radius R1 away from the surface of the second lens 4, and a radius R2 close to the surface of the second lens 4. The second lens 4 has a radius R3 close to the surface of the third lens 5, and a radius R4 close to the surface of the first imaging element. On this basis, the above-mentioned R1, R2, R3 and R4 satisfy the relationship: {(R1-R2) / (R3-R4)} 2 ≤10.

[0088] Referring to Figure 1 , the surface of the third lens 5 away from the surface of the second lens 4 is defined as the sixth surface 52, and the surface of the third lens 5 close to the surface of the second lens 4 is defined as the fifth surface 51; the surface of the second lens 4 close to the surface of the third lens 5 is defined as the fourth surface 42, and the surface of the second lens 4 close to the surface of the first imaging element is defined as the third surface 41.

[0089] According to the above examples, by reasonably constraining the radial dimensions of the two lenses in the second imaging element, the chromatic aberration of the near-eye optical system can be effectively reduced under the premise of a larger field of view, for example, 50°-80°. This realizes a very important function of the near-eye optical system, that is, to minimize chromatic aberration or even eliminate chromatic aberration in near-eye imaging, so that the user can observe a very clear image at any position when using the near-eye optical system to view the image.

[0090] In some examples of the present application, referring to Figure 1 , the first imaging element includes a first lens 3; the thinnest position on the first lens 3 has a first thickness value T min ; the thickest position on the first lens 3 has a second thickness value T max ; the first thickness value T min is less than the second thickness value Tmax between 0.03 and 1. min -T max | / T max <1.

[0091] According to the above examples, referring to Figure 1 , the first imaging element is located on the near screen side, and when only one lens is used, that is, only a single first lens 3 is arranged on the near screen side, the ratio a between the difference between the thinnest point and the thickest point of the entire aperture of the first lens 3 and the thickest point satisfies the relationship: 0.03≤a<1, where a=|T min -T max | / T max The optical parameter design can reduce the field curvature and distortion of the near-eye optical system to some extent, and can better achieve the function of the near-eye optical system. The optical parameter can also constrain the thickness of the first lens 3. That is, in the case of ensuring that the first lens 3 has a suitable thickness, the optical performance of the near-eye optical system is improved.

[0092] In some examples of the present application, referring to Figure 1 , the radius of any surface of the first lens 3 is R, and the radius of the surface of the second lens 4 close to the first imaging element is R4, then R and R4 satisfy: 20<│R4│+│R│<100.

[0093] According to the above examples, the first lens 3 includes two surfaces, by constraining the radius R of any surface of the first lens 3 and the radius R4 of the surface of the second lens 4 close to the first lens 3, so that R and R4 satisfy the relationship in the above examples, the imaging quality can be improved while reducing the tolerance sensitivity of the near-eye optical system, thereby reducing the processing difficulty of the entire near-eye optical system.

[0094] In some examples of the present application, referring to Figure 1 , the near-eye optical system further includes a display 1, and the display 1 is located on the side of the first imaging element away from the second imaging element.

[0095] In the near-eye display system, the display 1 can emit light for imaging display.

[0096] The display 1 can emit light of multiple different wavebands, for example, and can form a color image at the position of the diaphragm 01.

[0097] Optionally, a screen protection element 2 is arranged on the light emitting surface of the display 1. The screen protection element 2 can effectively protect the display 1.

[0098] In some examples of the present application, referring to Figure 1 , Figure 2 and Figure 7 , the polarization reflection element 8 is arranged on the surface of the third lens 5 close to the display 1, and the surface of the third lens 5 away from the display 1 is concave.

[0099] According to the above examples, the polarization reflection element 8 for forming a folded optical path is arranged on the third lens 5 on the side of the near-iris 01, specifically, on the surface of the third lens 5 close to the display 1, i.e. the fifth surface 51, referring to Figure 1 , the fifth surface 51 forms the reflecting surface of the third lens 5, and at the same time, the sixth surface 52 of the third lens 5 can be designed as a concave surface, thus providing a negative optical power, which can further improve the process implementation of the lens while ensuring the optical performance.

[0100] It should be noted that in the near-eye optical system, the number of lenses used includes but is not limited to three. The increased lenses can be placed in the first imaging element. For example, between the first lens 3 and the display 1, referring to the fourth lens 11 shown in Figure 18 . Appropriately increasing the number of lenses helps to improve the optical performance.

[0101] In some examples of the present application, referring to Figure 1 and Figure 2 , the light splitting element 6 is arranged on the surface of the second lens 4 close to the display 1, and the first phase retarder 7 and the polarization reflection element 8 are arranged on the surface of the third lens 5 close to the display 1.

[0102] Among them, the light splitting element 6 is, for example, a quarter-wave plate, which can be directly attached or plated on the surface of the second lens 4 close to the display 1 (the third surface 41 shown in Figure 1 ). The first phase retarder 7 and the polarization reflection element 8 are arranged together on the surface of the third lens 5 close to the display 1 (the fifth surface 51 shown in Figure 1 ). No separate flat support is needed in the optical architecture to support the above-mentioned optical elements.

[0103] Among them, the included angle between the reflection direction of the polarization reflection element 8 and the fast axis or slow axis of the first phase retarder 7 is 45°, which can convert left-handed circularly polarized light into linearly polarized light in the reflection direction of the polarization reflection element 8.

[0104] According to the above examples, the polarization reflection element 8 and the first phase retarder 7 are arranged on the same side of the first lens 3, which helps to reduce the assembly process difficulty.

[0105] Optionally, referring to Figure 2 , the near-eye optical system further comprises a first polarizing element 9, the first polarizing element 9 is located in the second imaging element, and the first polarizing element 9 and the polarization reflection element 8 and the light splitting element 6 are stacked to form a composite film, and the polarization reflection element 8 is located between the first polarizing element 9 and the first phase retarder 7.

[0106] That is, the transmission direction of the first polarizing element 9 and the polarization reflection element 8 is consistent, and the use of the first polarizing element 9 can be used to reduce ghost images and stray light.

[0107] Optionally, an anti-reflection element 10 can also be introduced in the composite film, referring to Figure 2 , the anti-reflection element 10 is located on the surface of the first phase retarder 7 away from the polarization reflection element 8.

[0108] In some examples of the present application, referring to Figure 1 and Figure 7 , the light splitting element 6 is arranged on the surface of the second lens 4 close to the display 1, the first phase retarder 7 is arranged on the surface of the second lens 4 away from the display 1, and the polarization reflection element 8 is arranged on the surface of the third lens 5 close to the display 1.

[0109] According to the above examples, unlike the assembly method shown in Figure 2 , referring to Figure 7 , Figure 7 , the first phase retarder 7 and the polarization reflection element 8 are separated, so that the first phase retarder 7 and the polarization reflection element 8 are respectively attached to the second lens 4 and the third lens 5. This design can reduce the incident angle of light incident to the polarization reflection element 8, which is beneficial to improve the imaging clarity of the near-eye optical system in the entire field of view.

[0110] Optionally, referring to Figure 7 , the near-eye optical system further comprises a first polarizing element 9, the first polarizing element 9 is located in the second imaging element, and the first polarizing element 9 and the polarization reflection element 8 are stacked.

[0111] Optionally, referring to Figure 7 , when the first phase retarder 7 and the polarization reflection element 8 are arranged separately, an anti-reflection element 10 can be introduced on one side of the first phase retarder 7, and at this time, the first phase retarder 7 and the anti-reflection element 10 are arranged on the surface of the second lens 4 away from the display 1.

[0112] In some examples of the present application, the display 1 is configured to emit circularly polarized light or natural light; when the display 1 emits natural light, a superposition element is arranged between the display 1 and the first imaging element, which can be used to convert natural light into circularly polarized light, and the superposition element includes a second polarization element and a second phase retarder.

[0113] The superposition element is mainly used to form circularly polarized light from the light incident into the first imaging element. In the present application, the superposition element is directly arranged on the light-emitting surface of the display 1, so that the display 1 can directly emit circularly polarized light.

[0114] 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 70 μm.

[0115] That is, the near-eye optical system provided by the embodiments of the present application has low chromatic aberration and low distortion optical performance.

[0116] In some examples of the present application, referring to Figure 1 , the first imaging element includes at least one lens, and the first imaging element includes at least one reverse curve.

[0117] The first imaging element is located near the side of the display 1, and the first imaging element includes one or more lenses, at least one of which has a reverse curve. That is, the entire first imaging element includes at least one reverse curve. According to the optical architecture provided by the embodiments of the present application, the design of introducing at least one reverse curve into the first imaging element can improve high-order aberration, thereby improving optical performance.

[0118] In some examples of the present application, referring to Figure 1 , the first imaging element includes a first lens 3, and at least one surface of the first lens 3 is a reverse curve.

[0119] In some examples of the present application, referring to Figure 23 , the reverse curve satisfies D2 / D1<1 and H1 / H2<1; wherein D1 is the maximum semi-diameter of the reverse curve, D2 is the distance from the position of the reverse curve to the center of the lens, H1 is the minimum sag of the reverse curve, and H2 is the maximum sag of the reverse curve.

[0120] According to the above examples, when a lens with a reverse curve is introduced into the first imaging element, by further constraining the shape of the reverse curve, the aberration of the near-eye optical system can be further improved, and the optical imaging performance of the near-eye optical system can be improved.

[0121] In some examples of the present application, referring to Figure 1, the total optical power of the near-eye optical system is φ, 0≤φ≤0.6; the optical lens in the near-eye optical system without folding light path includes the first lens 3 and the third lens 5; the combined optical power of the first lens 3 and the third lens 5 is φ 13 , then φ 13 and φ satisfy: 0.01≤φ 13 / φ≤0.2.

[0122] According to the near-eye optical system provided by the embodiment of the present application, when the optical structure as shown in the figure is used in the case of three lenses, the first lens 3 and the third lens 5 on both sides are located outside the folding light path, at this time, by restricting the relationship between the combined optical power of the two and the optical power of the whole system, the incident angle of the light on the lens surface can be reduced, the transmittance is improved, and the imaging clarity is improved. Figure 1 Figure 2 According to the near-eye optical system provided by the embodiment of the present application, when the optical structure as shown in the figure is used in the case of three lenses, the first lens 3 and the third lens 5 on both sides are located outside the folding light path, at this time, by restricting the relationship between the combined optical power of the two and the optical power of the whole system, the incident angle of the light on the lens surface can be reduced, the transmittance is improved, and the imaging clarity is improved.

[0123] According to the near-eye optical system provided by the embodiment of the present application, when the optical structure as shown in the figure is used in the case of three lenses, the first lens 3 and the third lens 5 on both sides are located outside the folding light path, at this time, by restricting the relationship between the combined optical power of the two and the optical power of the whole system, the incident angle of the light on the lens surface can be reduced, the transmittance is improved, and the imaging clarity is improved. Figure 1 The light propagation process of the near-eye optical system is as follows:

[0124] The light emitted by the display 1 is circularly polarized light, which is transmitted through the first lens 3, the second lens 4, becomes linearly polarized light (S light) through the first phase retarder 7 on the fifth surface 51 of the third lens 5, is reflected through the polarization reflection element 8, becomes circularly polarized light again through the first phase retarder 7, is reflected through the third surface 41 of the second lens 4, then becomes linearly polarized light (P light) through the first phase retarder 7, is then transmitted through the third lens 5, and forms a picture by hitting the aperture 01.

[0125] Figure 1 According to the near-eye optical system provided by the embodiment of the present application, when the optical structure as shown in the figure is used in the case of three lenses, the first lens 3 and the third lens 5 on both sides are located outside the folding light path, at this time, by restricting the relationship between the combined optical power of the two and the optical power of the whole system, the incident angle of the light on the lens surface can be reduced, the transmittance is improved, and the imaging clarity is improved. Figure 8 Figure 13 According to the near-eye optical system provided by the embodiment of the present application, when the optical structure as shown in the figure is used in the case of three lenses, the first lens 3 and the third lens 5 on both sides are located outside the folding light path, at this time, by restricting the relationship between the combined optical power of the two and the optical power of the whole system, the incident angle of the light on the lens surface can be reduced, the transmittance is improved, and the imaging clarity is improved.

[0126] Optionally, the refractive index n of the material used by each optical lens in the near-eye optical system ranges from 1.4 to 2.0, and the dispersion coefficient v ranges from 20 to 75.

[0127] For example, the refractive index n1 of the first lens 3 is 1.54, and the dispersion coefficient v1 is 56.3. The refractive index n2 of the second lens 4 is 1.54, and the dispersion coefficient v2 is 56.3. The refractive index n3 of the third lens 5 is 1.54, and the dispersion coefficient v3 is 55.7.

[0128] For example, the central thickness T1 of the first lens 3 is 1mm≤T1≤8mm.

[0129] ​​​The first lens 3 includes two optical surfaces, namely a first surface 31 close to the display 1 and a second surface 32 away from the display 1. The first surface 31 and the second surface 32 are both aspherical. Anti-reflection coatings may be provided on both the first surface 31 and the second surface 32.

[0130] For example, the center thickness T2 of the second lens 4 is: 1 mm≤T2≤10 mm.

[0131] The second lens 4 includes two optical surfaces: a third surface 41 proximal to the display 1 and a fourth surface 42 distal to the display 1. Both the third surface 41 and the fourth surface 42 are aspherical. A beam splitter 6, i.e., a semi-transmissive, semi-reflective film, may be disposed on the third surface 41. The fourth surface 42 is a flat or aspherical surface and may be provided with an anti-reflective film.

[0132] For example, the center thickness T3 of the third lens 5 is: 1 mm≤T3≤6 mm.

[0133] The third lens 5 includes two optical surfaces, namely a fifth surface 51 close to the display 1 and a sixth surface 52 away from the display 1. The fifth surface 51 and the sixth surface 52 may be aspherical. Figure 2 The composite film shown includes an anti-reflection element 10, a first phase retarder 7 (quarter-wave plate), a polarized reflective element 8 (transmits P light and reflects S light), and a first polarizing element 9 (transmits P light), which can reduce stray light. An anti-reflection film layer can also be provided on the sixth surface 52.

[0134] The following four embodiments provide a more detailed description of the near-eye optical system provided by the present application. The near-eye optical systems shown in Examples 1 to 3 all use three lenses, while the near-eye optical system shown in Example 4 uses four lenses.

[0135] Example 1

[0136] See also Figure 1 and Figure 2 The near-eye optical system includes a display 1, a first imaging element, and a second imaging element arranged in sequence along the same optical axis; wherein the first imaging element has a first lens 3, and the second imaging element includes a second lens 4 and a third lens 5, as well as a beam splitter 6, a first phase retarder 7, and a polarizing reflection element 8;

[0137] The spectral element 6 is arranged on the third surface 41 of the second lens 4, the first phase retarder 7, the polarization reflection element 8 and the first polarization element 9 are arranged on the fifth surface 51 of the third lens 5, and the sixth surface 52 is a concave surface.

[0138] Table 1 shows the optical parameters of the near-eye optical system, as follows.

[0139] Table 1

[0140]

[0141] The optical performance of the near-eye optical system provided in the above embodiment 1 can be as shown in Figures 3 to 6 Figure 3 is a schematic diagram of a point diagram of a near-eye optical system, Figure 4 is a MTF curve diagram of a near-eye optical system, Figure 5 is a field curvature distortion diagram of a near-eye optical system, Figure 6 is a sagittal chromatic aberration diagram of a near-eye optical system.

[0142] The point diagram refers to a diffused pattern formed by a plurality of light rays emitted from a point after passing through the near-eye optical system, and the intersection points of the light rays with the image plane are no longer concentrated at the same point due to aberrations. The point diagram can be used to evaluate the imaging quality of the near-eye optical system. Referring to Figure 3 , the maximum value of the image point in the point diagram is less than 11 μm.

[0143] The MTF curve diagram is a modulation transfer function diagram, and the contrast of the black and white lines represents the imaging clarity of the near-eye optical system. Referring to Figure 4 , the central MTF is greater than 0.3 at 40 lp / mm, and the imaging is clear.

[0144] Referring to Figure 5 , the maximum distortion occurs at 1 field of view, and the absolute value is less than 3%.

[0145] Sagittal chromatic aberration, also known as magnification chromatic aberration, mainly refers to a single color main light ray in the object field, which becomes multiple light rays in the image field due to the existence of chromatic dispersion in the refractive system. The difference between the focal point positions of blue light and red light on the image plane. Referring to Figure 6 , the maximum chromatic aberration value of the near-eye optical system is less than 16 μm.

[0146] Embodiment 2

[0147] Referring to Figure 7 and Figure 8 , the difference between embodiment 2 and the above embodiment 1 is that:

[0148] ​The spectral element 6 is arranged on the third surface 41 of the second lens 4, the first phase retarder 7 is arranged on the fourth surface 42 of the second lens 4, and the polarization reflection element 8 and the first polarization element 9 are arranged on the fifth surface 51 of the third lens 5.

[0149] Table 2 shows the optical parameters of the near-eye optical system, as follows.

[0150] Table 2

[0151]

[0152] The optical performance of the near-eye optical system provided in this embodiment 2 can be as shown in the following figures. Figures 9 to 12 Figure 9 is a schematic diagram of the spot diagram of the near-eye optical system, Figure 10 is a MTF curve diagram of the near-eye optical system, Figure 11 is a field curvature distortion diagram of the near-eye optical system, Figure 12 is a sagittal chromatic aberration diagram of the near-eye optical system.

[0153] The spot diagram refers to a diffused pattern formed by a point emitting many light rays after passing through the near-eye optical system, and the intersection points with the image plane are no longer concentrated in the same point due to aberration. It can be used to evaluate the imaging quality of the near-eye optical system. Referring to Figure 9 , the maximum value of the image point in the spot diagram is less than 16 μm.

[0154] The MTF curve diagram is a modulation transfer function diagram, which represents the imaging clarity of the near-eye optical system through the contrast of black and white lines. Referring to Figure 10 , the central MTF is >0.2 at 40 lp / mm, and the imaging is clear.

[0155] Referring to Figure 11 , the maximum distortion occurs at 1 field of view, and the absolute value is less than 3%.

[0156] Sagittal chromatic aberration, also known as magnification chromatic aberration, mainly refers to a root complex main light ray in the object side, which becomes multiple light rays when exiting the image side due to the existence of chromatic dispersion in the refractive system. The difference between the focal point positions of blue light and red light on the image plane. Referring to Figure 12 , the maximum chromatic aberration value of the near-eye optical system is less than 16 μm.

[0157] Embodiment 3

[0158] Referring to Figure 13 , the near-eye optical system provided in this embodiment 3 is different from the near-eye optical system shown in embodiment 1 in that the parameters of the optical elements are different.

[0159] Table 3 shows the optical parameters of the near-eye optical system, as follows.​

[0160] Table 3

[0161]

[0162] The optical performance of the near-eye optical system provided in this embodiment 3 can be shown as follows: Figures 14 to 17 Figure 13 is a schematic diagram of a point spread of the near-eye optical system, Figure 14 is a curve diagram of MTF of the near-eye optical system, Figure 15 is a field curvature distortion diagram of the near-eye optical system, Figure 16 is a sagittal chromatic aberration diagram of the near-eye optical system.

[0163] The point spread refers to a diffused pattern formed by a plurality of light rays emitted from a point after passing through the near-eye optical system, and the intersection points of the light rays with the image plane are no longer concentrated at the same point due to aberration. The point spread can be used to evaluate the imaging quality of the near-eye optical system. Referring to FIG. 6, the maximum value of the image point in the point spread is less than 14 μm. Figure 14

[0164] The MTF curve diagram is a modulation transfer function diagram, and the imaging clarity of the near-eye optical system is represented by the contrast of the black and white lines. Referring to FIG. 7, the central MTF is greater than 0.4 at 40 lp / mm, and the imaging is clear. Figure 15

[0165] Referring to FIG. 8, the maximum distortion occurs at 1 field of view, and the absolute value is less than 3%. Figure 16

[0166] The sagittal chromatic aberration, also known as the rate of chromatic aberration, mainly refers to a primary chromatic ray in the object side, which becomes a plurality of light rays when exiting the image side due to the dispersion of the refractive system. The difference between the focal point positions of the blue light and the red light on the image plane. Referring to FIG. 9, the maximum chromatic aberration value of the near-eye optical system is less than 16 μm. Figure 17

[0167] Embodiment 4

[0168] Referring to FIG. 10, the near-eye optical system provided in this embodiment 4 is different from the near-eye optical system shown in embodiment 1 in that a lens is added between the display 1 and the first lens 3, that is, the fourth lens 11 shown in Figure 18 . That is, the near-eye optical system provided in this embodiment 4 uses four lenses. Figures 19 to 22

[0169] ​​​​​​According to the foregoing embodiments 1-3 and the present embodiment 4, it is to be noted that the near-eye optical system provided in the present embodiments uses at least three lenses. Of course, the number of lenses can be increased according to specific requirements, and as long as at least three lenses are used in the entire near-eye optical system, the number of added lenses can be unlimited, and will not be illustrated one by one here.

[0170] Table 4 shows the optical parameters of the near-eye optical system, as follows.

[0171] Table 4

[0172]

[0173]

[0174] The optical performance of the near-eye optical system provided in the present embodiment 4 can be as shown in Figure 19 . Figure 20 is a schematic diagram of the spot diagram of the near-eye optical system, Figure 21 is a MTF curve diagram of the near-eye optical system, Figure 22 is a field curvature distortion diagram of the near-eye optical system, Figure 19 is a sagittal chromatic aberration diagram of the near-eye optical system.

[0175] The spot diagram refers to a diffused diagram formed by a point emitting many light rays, after passing through the near-eye optical system, due to aberration, the intersection points of the light rays with the image plane are no longer concentrated at the same point, which can be used to evaluate the imaging quality of the near-eye optical system. Referring to Figure 20 , the maximum value of the image point in the spot diagram is less than 11 μm.

[0176] The MTF curve diagram is a modulation transfer function diagram, and the contrast of the black and white lines represents the imaging clarity of the near-eye optical system. Referring to Figure 21 , the central MTF is >0.6 at 40 lp / mm, and the imaging is clear.

[0177] Referring to Figure 22 , the maximum distortion occurs at 1 field of view, and the absolute value is less than 3%.

[0178] Sagittal chromatic aberration, also known as magnification chromatic aberration, mainly refers to a primary chromatic main light ray in the object side, which becomes multiple light rays when exiting the image side due to the existence of chromatic dispersion in the refractive system. The difference between the focal point positions of blue light and red light on the image plane. Referring to ​ , the maximum chromatic aberration value of the near-eye optical system is less than 16 μm.

[0179] According to another embodiment of the present application, a head-mounted display device is provided.

[0180] The head-mounted display device includes a housing and a near-eye optical system as described above.

[0181] The head-mounted display device can be in the form of a VR glasses or a VR helmet, and the present application is not limited in this regard.

[0182] The specific implementation of the head-mounted display device 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, which will not be repeated here.

[0183] The above embodiments mainly describe the differences between the various embodiments. The different optimization features between the various embodiments can be combined to form a more optimal embodiment as long as they are not contradictory. In view of the brevity of the writing, this will not be repeated here.

[0184] 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, 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 by, The first imaging element and the second imaging element are sequentially arranged along the same optical axis; The first imaging element comprises at least one lens; The second imaging element comprises a second lens (4) and a third lens (5), and a light splitting element (6), a first phase retarder (7) and a polarization reflection element (8) sequentially arranged between the second lens (4) and the third lens (5); Wherein, the optical power of the third lens (5) away from the surface of the second lens (4) is φ1, the optical power of the third lens (5) close to the surface of the second lens (4) is φ2, and the optical power of the second lens (4) close to the first imaging element is φ3, and φ1, φ2 and φ3 satisfy: -1<φ1 / (φ2+φ3)<0; The third lens (5) and the second lens (4) are both meniscus lenses, and the concave surface faces the stop (01).

2. The near-eye optical system of claim 1, wherein, The radius of the third lens (5) away from the surface of the second lens (4) is R1, and the radius of the third lens (5) close to the surface of the second lens (4) is R2; The radius of the second lens (4) close to the surface of the third lens (5) is R3, and the radius of the second lens (4) close to the first imaging element is R4; satisfies {(R1-R2) / (R3-R4)} between the R1, the R2, the R3, and the R4 2 ≤ 10.

3. The near-eye optical system of claim 1 or 2, wherein, The first imaging element comprises a first lens (3); the thinnest position on the first lens (3) has a first thickness value T min the thickest position on the first lens (3) has a second thickness value T max the first thickness value T min and the second thickness value T max satisfy: 0.03≤|T min -T max | / T max <1.

4. The near-eye optical system of claim 3, wherein, The radius of any surface of the first lens (3) is R, and the radius of the surface of the second lens (4) close to the first imaging element is R4, and R and R4 satisfy: 20<│R4│+│R│<100.

5. The near-eye optical system of claim 4, wherein, The near-eye optical system further comprises a display (1), and the display (1) is located on the side of the first imaging element away from the second imaging element.

6. The near-eye optical system of claim 5, wherein, The polarization reflection element (8) is arranged on the surface of the third lens (5) close to the display (1), and the surface of the third lens (5) away from the display (1) is concave.

7. The near-eye optical system of claim 6, wherein, The light splitting element (6) is arranged on the surface of the second lens (4) close to the display (1), the first phase retarder (7) and the polarization reflection element (8) are arranged on the surface of the third lens (5) close to the display (1).

8. The near-eye optical system of claim 7, wherein, The near-eye optical system further comprises a first polarization element (9), and the first polarization element (9) is located in the second imaging element, and the first polarization element (9) and the polarization reflection element (8) and the light splitting element (6) are stacked to form a composite film material, and the polarization reflection element (8) is located between the first polarization element (9) and the first phase retarder (7).

9. The near-eye optical system of claim 6, wherein, The light splitting element (6) is arranged on the surface of the second lens (4) close to the display (1), the first phase retarder (7) is arranged on the surface of the second lens (4) away from the display (1), and the polarization reflection element (8) is arranged on the surface of the third lens (5) close to the display (1).

10. The near-eye optical system of claim 9, wherein, The near-eye optical system further comprises a first polarization element (9), and the first polarization element (9) is located in the second imaging element, and the first polarization element (9) and the polarization reflection element (8) are stacked.

11. The near-eye optical system of claim 5, wherein, The display (1) is configured to emit circularly polarized light or natural light; When the light emitted by the display (1) is natural light, a superposition element is arranged between the display (1) and the first imaging element, which is capable of converting the natural light into circularly polarized light, and the superposition element comprises a second polarization element and a second phase retarder.

12. The near-eye optical system of claim 1, wherein, An absolute value of distortion of the near-eye optical system is less than 3%, and a maximum chromatic aberration value is less than 70 μm.

13. The near-eye optical system of claim 1, wherein, The first imaging element comprises at least one lens, and the first imaging element comprises at least one reverse curve.

14. The near-eye optical system of claim 3, wherein, At least one surface of the first lens (3) is a reverse curve.

15. The near-to-eye optical system of claim 13 or 14, wherein, The reverse curve satisfies D2 / D1<1 and H1 / H2<1; wherein D1 is a maximum semi-oral radius of the reverse curve, D2 is a distance from a position at which the reverse curve generates a reverse curve point to a center of the lens, H1 is a minimum sag of the reverse curve, and H2 is a maximum sag of the reverse curve.

16. The near-eye optical system of claim 3, wherein, A total optical power of the near-eye optical system is φ, and 0≤φ≤0.6; The lenses in the non-folding optical path of the near-eye optical system comprise the first lens (3) and the third lens (5); The combined optical power of the first lens (3) and the third lens (5) is φ 13 then φ 13 satisfies: 0.01≤φ 13 / φ≤0.

2.

17. A head-mounted display device, comprising: Comprise: a housing; and The near-eye optical system according to any one of claims 1-16.

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