Near-eye optical system and head-mounted display device

Abstract

The embodiment of the invention provides a near-eye optical system and head-mounted display equipment. The near-eye optical system comprises a first optical element, a polarization reflection element, a phase retarder, a light splitting element and a second optical element which are arranged along the same optical axis, and the phase retarder is located between the light splitting element and the polarization reflection element; the first optical element comprises n1 lenses, n1 is greater than or equal to 2, and the focal power of the first optical element is phi 1; the second optical element comprises n2 lenses, n2 is greater than or equal to 1, and the focal power of the edge area of the second optical element is phi 2; and the near-eye optical system meets the condition that (phi 1 / n1 + phi 2 / n2) / (phi 1 + phi 2) is greater than 0 and less than or equal to 3. According to the near-to-eye optical system provided by the embodiment of the invention, the imaging quality can be ensured while a large view field is ensured.

Description

Technical Field

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

[0002] The core component of virtual reality technology (VR technology) is the optical system used internally, and the quality of its displayed images will directly determine the quality of VR equipment. In order to enhance the user's immersive experience, higher requirements are placed on the field of view (FOV) of the optical system in VR equipment, that is, the FOV should be increased as much as possible. Generally speaking, the larger the FOV, the worse the image quality at the edge of the field of view. How to ensure the image quality while ensuring a large FOV is a problem that needs to be solved at present. Summary of the invention

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

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

[0005] The first optical element comprises n1 lenses, and n1≥2, and the optical power of the first optical element is φ1;

[0006] The second optical element comprises n2 lenses, where n2≥1, and the optical power of the edge region of the second optical element is φ2;

[0007] The near-eye optical system satisfies: 0<(φ1 / n1+φ2 / n2) / (φ1+φ2)≤3.

[0008] Optionally, the first optical element includes a first lens and a second lens, and the first lens and the second lens are glued to each other; wherein the second lens is located between the first lens and the second optical element.

[0009] Optionally, the near-eye optical system satisfies: 0<(φ1 / n1+φ2 / n2) / (φ1+φ2)<1.

[0010] Optionally, the near-eye optical system satisfies: 0.5≤(φ1 / n1+φ2 / n2) / (φ1+φ2)≤0.8.

[0011] Optionally, the beam splitter element is located between the second optical element and the first optical element, the phase retarder and the polarization reflection element are arranged in the first optical element; and the optical focal length φ2 of the edge area of ​​the second optical element is greater than 0.

[0012] Optionally, the second optical element is a third lens, the optical focal length of an edge region of the third lens is φ2, and φ2>0.

[0013] Optionally, the second optical element includes a third lens and a fourth lens, the third lens is close to the first optical element, and the fourth lens is far away from the first optical element;

[0014] The combined optical power of the edge area of ​​the third lens and the edge area of ​​the fourth lens is φ2, and φ2>0.

[0015] Optionally, the near-eye optical system further comprises a display screen, which emits light for imaging display;

[0016] The display screen is located on a side of the second optical element away from the first optical element, and two layers of protective glass are stacked on the light-emitting surface of the display screen.

[0017] Optionally, the total thickness of the two layers of protective glass is H, and 0.7 mm≤H≤2 mm.

[0018] Optionally, the beam splitter element is disposed on a surface of the second lens facing away from the first lens; the phase retarder and the polarized reflective element are sequentially stacked on a surface where the second lens and the first lens are glued together.

[0019] Optionally, the near-eye optical system further includes a polarizer, which is disposed on a side of the polarizing reflective element away from the phase retarder, and the polarizer, the polarizing reflective element and the phase retarder are stacked to form a composite film material.

[0020] Optionally, the display screen is configured to emit circularly polarized light or natural light;

[0021] In the case that the light emitted by the display screen is natural light, the light-emitting surface of the display screen is further provided with a superimposed element for converting the natural light into circularly polarized light, and the superimposed element at least includes a phase delay plate and a linear polarizer.

[0022] In a second aspect, the present application provides a head mounted display device. The head mounted display device comprises:

[0023] a housing; and

[0024] A near-eye optical system as described in the first aspect.

[0025] The beneficial effects of this application are:

[0026] According to the near-eye optical system provided in the embodiment of the present application, by reasonably constraining the relationship between the number of lenses and the optical focal length, it is possible to ensure a large field of view FOV while taking into account the final imaging quality, especially the image quality of the edge field of view can be guaranteed.

[0027] Other features and advantages of the present specification will become apparent from the following detailed description of exemplary embodiments of the present specification with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the specification and, together with the description, serve to explain the principles of the specification.

[0029] Figure 1 One of the structural schematic diagrams of the near-eye optical system provided in an embodiment of the present application;

[0030] Figure 2 A schematic diagram of the arrangement of the composite membrane material provided in the embodiment of the present application;

[0031] Figure 3 A dot array diagram of the near-eye optical system provided in Example 1 of the present application;

[0032] Figure 4 A modulation transfer function MTF curve diagram of the near-eye optical system provided in Example 1 of the present application;

[0033] Figure 5 Field curvature and distortion diagram of the near-eye optical system provided in Example 1 of the present application;

[0034] Figure 6 A vertical axis chromatic aberration diagram of the near-eye optical system provided in Example 1 of the present application;

[0035] Figure 7 The second structural schematic diagram of the near-eye optical system provided in the embodiment of the present application;

[0036] Figure 8 A dot array diagram of a near-eye optical system provided in Example 2 of the present application;

[0037] Fig. 9 A modulation transfer function MTF curve diagram of the near-eye optical system provided in Example 2 of the present application;

[0038] Fig.10 Field curvature and distortion diagram of the near-eye optical system provided in Example 2 of the present application;

[0039] Fig.11A vertical axis chromatic aberration diagram of the near-eye optical system provided in Example 2 of the present application;

[0040] Fig.12 The third structural schematic diagram of the near-eye optical system provided in the embodiment of the present application;

[0041] Fig.13 A dot array diagram of a near-eye optical system provided in Example 3 of the present application;

[0042] Fig.14 A modulation transfer function MTF curve diagram of the near-eye optical system provided in Example 3 of the present application;

[0043] Fig.15 Field curvature and distortion diagram of the near-eye optical system provided in Example 3 of the present application;

[0044] Fig.16 This is a vertical axis chromatic aberration diagram of the near-eye optical system provided in Example 3 of the present application.

[0045] Description of reference numerals:

[0046] 1. Display screen; 2. First protective glass; 3. Second protective glass; 4. Third lens; 41. Fifth surface; 42. Sixth surface; 5. Second lens; 51. Third surface; 52. Fourth surface; 6. First lens; 61. First surface; 62. Second surface; 7. Polarizer; 8. Polarized reflective element; 9. Phase retarder; 10. Spectral element; 11. Fourth lens; 111. Seventh surface; 112. Eighth surface; 01. Human eye. DETAILED DESCRIPTION

[0047] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application.

[0048] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present application, its application, or uses.

[0049] Techniques and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the techniques and equipment should be considered part of the specification.

[0050] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0051] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0052] The near-eye optical system and the head-mounted display device provided in the embodiments of the present application are described in detail below in conjunction with the accompanying drawings.

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

[0054] The near-eye optical system proposed in the embodiment of the present application, see Figure 1 , the near-eye optical system includes a first optical element, a polarized reflection element 8, a phase retarder 9, a beam splitter 10 and a second optical element arranged along the same optical axis; wherein the phase retarder 9 is located between the beam splitter 10 and the polarized reflection element 8; the first optical element includes n1 lenses, and n1≥2, and the optical focal length of the first optical element is φ1; the second optical element includes n2 lenses, and n2≥1, and the optical focal length of the edge area of ​​the second optical element is φ2; the near-eye optical system satisfies: 0<(φ1 / n1+φ2 / n2) / (φ1+φ2)≤3.

[0055] According to the near-eye optical system provided by the above embodiment of the present application, it includes a first optical element and a second optical element arranged along the same optical axis, wherein the first optical element is, for example, located on a side close to the human eye 01, and the second optical element is, for example, located on a side away from the human eye 01, that is, on a side close to the screen, see Figure 1 Specifically, the first optical element and the second optical element include different numbers of lenses, respectively. For example, the first optical element has at least two lenses, and the second optical element has at least one lens.

[0056] In addition to the first optical element and the second optical element, the near-eye optical system also uses the beam splitter 10, the phase retarder 9 and the polarized reflective element 8, which can be used to form a folded optical path, and the light is folded back and finally emitted to the human eye 01 for imaging. The introduction of the folded optical path can reduce the size of the near-eye optical system along the optical axis while ensuring the imaging quality.

[0057] In the near-eye optical system provided in the above embodiment, the relationship between the first optical element and the second optical element should satisfy: 0<(φ1 / n1+φ2 / n2) / (φ1+φ2)≤3, wherein n1 is the number of lenses in the first optical element, and n1≥2, n2 is the number of lenses in the second optical element, and n2≥1, φ1 is the optical focal length of the first optical element, and φ2 is the optical focal length of the edge area of ​​the second optical element. Through the above constraints, that is, the relationship between the number of lenses and the optical focal length φ1 in the first optical element and the number of lenses and the optical focal length φ2 in the edge area of ​​the lenses in the second optical element, the image quality of the final image can be guaranteed under the premise of a large field of view, especially the image quality of the edge field of view can be improved; wherein the large field of view FOV can, for example, reach 105°, or even larger.

[0058] The range of the edge region of the second optical element is explained as follows:

[0059] When the second optical element is a single lens, see Figure 1 The edge area of ​​the second optical element is the area outside the 0.7 diameter of the lens, that is, the area outside 70% of the lens.

[0060] When the second optical element includes two or more lenses, the edge area of ​​the second optical element refers to the edge area of ​​each lens included therein. Fig.12 The second optical element, for example, includes two lenses away from the human eye 01. At this time, the edge area of ​​the second optical element refers to the edge area of ​​the two lenses, and the optical focal length of the edge area of ​​the second optical element is the combined optical focal length of the edge areas of the two lenses; wherein the edge area of ​​each lens refers to the area outside the 0.7 diameter of the lens, that is, the area outside 70% of the lens.

[0061] It should be noted that the optical power is the reciprocal of the focal length of the lens.

[0062] The range of the focal power φ1 of the first optical element is: 0.01≤φ1≤0.1.

[0063] The optical focal length φ2 of the edge region of the second optical element is 0≤φ2≤0.1.

[0064] The near-eye optical system provided in the embodiment of the present application designs the optical power of the two optical elements to be positive, so that high-definition imaging can be achieved in a large field of view. Figure 4 , Fig. 9 and Fig.14 , the MTF of the near-eye optical system is >0.2 at 39lp / mm, which indicates that the imaging clarity of the near-eye optical system is better.

[0065] Wherein, the first optical element includes but is not limited to using two lenses, and more lenses, such as three lenses, can be used as needed. Figure 1 Taking the optical architecture shown as an example, the newly added lens can be placed between the human eye 01 and the first lens 6.

[0066] Wherein, the second optical element includes but is not limited to using a single lens, and more lenses can be used as needed, such as two lenses, see Fig.12 .

[0067] The near-eye optical system provided in the embodiment of the present application can achieve a larger field of view angle, such as FOV of up to 105°, under the premise of miniaturized design, while ensuring the imaging quality, especially improving the imaging quality of the edge field of view.

[0068] In the near-eye optical system provided in the embodiment of the present application, the beam splitting element 10 can allow a portion of light to be transmitted and another portion of light to be reflected.

[0069] The light splitting element 10 is, for example, a semi-transmissive and semi-reflective film.

[0070] It should be noted that the reflectivity and transmittance of the light splitting element 10 can be flexibly adjusted according to specific needs, and this is not limited in the embodiments of the present application.

[0071] In the near-eye optical system provided in the embodiment of the present application, the phase retarder 9 can be used to change the polarization state of light, for example, to convert linearly polarized light into circularly polarized light, or to convert circularly polarized light into linearly polarized light.

[0072] The phase retarder 9 is, for example, a quarter wave plate.

[0073] Of course, the phase retarder 9 can be set to other phase retarder plates, such as a half-wave plate, etc. as needed.

[0074] In the near-eye optical system provided in the embodiment of the present application, the polarized reflective element 8 is a polarized reflector that reflects horizontal linear polarized light and transmits vertical linear polarized light, or a polarized reflector that reflects linear polarized light at any other specific angle and transmits linear polarized light in a direction perpendicular to the angle.

[0075] In the embodiment of the present application, the phase retarder 9 cooperates with the polarized reflection element 8 to analyze and transmit the light.

[0076] It should be noted that the optical elements such as the spectroscopic element 10, the phase retarder 9 and the polarized reflection element 8 form a folded light path on the side close to the human eye 01. The layout positions of the above-mentioned optical elements in the lens group are relatively flexible, but it must be ensured that the phase retarder 9 is between the spectroscopic element 10 and the polarized reflection element 8.

[0077] Optionally, the near-eye optical system satisfies 0<(φ1 / n1+φ2 / n2) / (φ1+φ2)<1.

[0078] Furthermore, the near-eye optical system satisfies 0.5≤(φ1 / n1+φ2 / n2) / (φ1+φ2)≤0.8.

[0079] By further constraining the relationship between the number of lenses n1 of the first optical element, the optical focal length φ1 of the first optical element, and the number of lenses n2 of the second optical element, and the optical focal length φ2 of the edge area of ​​the second optical element, it is possible to ensure better image quality in a large field of view.

[0080] In some examples of this application, see Figure 1 The first optical element includes a first lens 6 and a second lens 5, and the first lens 6 and the second lens 5 are glued to each other; wherein the second lens 5 is located between the first lens 6 and the second optical element.

[0081] According to the above example, the first optical element can be composed of the first lens 6 and the second lens 5 glued together. The gluing design can effectively reduce the stray light of the near-eye optical system, thereby further improving the imaging quality.

[0082] In some examples of the present application, the beam splitter 10 is located between the second optical element and the first optical element, the phase retarder 9 and the polarization reflection element 8 are arranged in the first optical element; and the optical focal length φ2 of the edge area of ​​the second optical element is greater than 0.

[0083] See also Figure 1 , the beam splitter element 10 is, for example, a semi-transparent and semi-reflective film, and the beam splitter element 10 can be combined with the first optical element. At this time, the second optical element is located outside the beam splitter element 10, and the focal power φ2 of the edge area of ​​the second optical element is designed to be positive, which can effectively reduce the incident angle of light on the lens surface where the semi-transparent and semi-reflective film is located, and can reduce the difficulty of coating. Wherein, the range of the focal power φ2 of the edge area of ​​the second optical element is, for example: 0≤φ2≤0.1.

[0084] Specifically, see Figure 2The light splitting element 10 (semi-transparent and semi-reflective film) can be plated on the surface where the second lens 5 and the first lens 6 are glued together, that is, Figure 1 On the fourth surface 52 shown in FIG.

[0085] In addition, the second optical element is used to provide positive optical power, so that the imaging quality of the marginal field of view can be taken into consideration.

[0086] In some examples of this application, see Figure 1 and Figure 7 The second optical element is a third lens 4, the optical focal length of the edge area of ​​the third lens 4 is φ2, and φ2>0.

[0087] That is to say, when the second optical element is a single lens, the optical focal length of the edge region of the second optical element is the optical focal length of the edge region of the single lens. For example, if the second optical element is the third lens 4 mentioned above, the optical focal length of the edge region of the third lens 4 is the above-mentioned φ2, which may range from 0 to 0.1 (including the endpoint values).

[0088] The edge area of ​​the third lens 4 refers to the area outside the 0.7 diameter of the third lens 4, that is, the area outside 70% of the third lens.

[0089] In the optical solution provided in the embodiment of the present application, the number of lenses in the second optical element is n2≥1.

[0090] In some other examples of the present application, the second optical element includes a third lens 4 and a fourth lens 11, the third lens 4 is close to the first optical element, and the fourth lens 11 is far away from the first optical element; the combined optical focal length of the edge area of ​​the third lens 4 and the edge area of ​​the fourth lens 11 is φ2, and φ2>0.

[0091] When the second optical element has two or more lenses, the optical focal length φ2 of the edge area of ​​the second optical element is the combined optical focal length of the edge areas of all the lenses it contains, and the combined optical focal length range should also satisfy the above-mentioned range of φ2, that is, 0 to 0.1 (including the endpoint values).

[0092] The edge area of ​​the third lens 4 refers to the area outside the 0.7 diameter of the third lens 4, that is, the area outside 70% of the third lens. The edge area of ​​the fourth lens 11 refers to the area outside the 0.7 diameter of the fourth lens 11, that is, the area outside 70% of the fourth lens.

[0093] It should be noted that, for the near-eye optical system provided in the embodiment of the present application, the first optical element uses at least two lenses, and the second optical element uses at least one lens. Adding lenses to the first optical element and / or the second optical element can improve the imaging quality and help reduce the overall length of the optical system, but may involve an increase in system weight and an increase in cost.

[0094] In some examples of this application, see Figure 1 The near-eye optical system further comprises a display screen 1, which emits light for imaging display. The display screen 1 is located on the side of the second optical element away from the first optical element, and two layers of protective glass are stacked on the light-emitting surface of the display screen 1.

[0095] The total thickness of the two layers of protective glass is H, and 0.7 mm ≤ H ≤ 2 mm.

[0096] Specifically, see Figure 1 , a first protective glass 2 and a second protective glass 3 are stacked on the light-emitting surface of the display screen 1 to form a double layer of protective glass on the light-emitting surface of the display screen 1. Designing two layers of protective glass in front of the display screen 1 can effectively improve the tolerance of the optical solution to screen surface dirt. Moreover, the incident angle of light incident on the display screen 1 can also match the light-emitting angle of the display screen 1, which is conducive to improving the imaging brightness.

[0097] It should be noted that the thickness of the first protective glass 2 and the second protective glass 3 after being stacked should be reasonably controlled, and the total thickness should not be too thick. The minimum total thickness can be controlled at 0.7 mm and the maximum can be controlled at 2 mm.

[0098] Optionally, the total thickness H of the two layers of protective glass can be 0.7 mm, 1 mm, 1.2 mm, 1.5 mm, 1.7 mm, or 2 mm. Of course, it can also be flexibly designed according to specific needs.

[0099] The display screen 1 may be a self-luminous screen such as LCD, LED, OLED, Micro-OLED, ULED, or a reflective screen such as DMD.

[0100] The display screen 1 can emit RGB light, for example, to form a color image.

[0101] In some examples of this application, see Figure 1 and Figure 2 The beam splitter 10 is disposed on the surface of the second lens 5 away from the first lens 6; the phase retarder 9 and the polarized reflective element 8 are sequentially stacked on the surface where the second lens 5 and the first lens 6 are glued.

[0102] According to the above example, there is no need to introduce a flat support member in the entire optical structure to support the beam splitter element 10, the phase retarder 9 and the polarization reflection element 8, which can simplify the optical architecture.

[0103] The light splitting element 10 can be disposed on the non-bonded surface of the second lens 5 by, for example, bonding or plating. The non-bonded surface of the second lens 5 is the surface close to the display screen 1, i.e. Figure 1 The third surface 51 is shown in FIG.

[0104] After the phase retarder 9 and the polarized reflective element 8 are laminated and glued, the two can be glued and arranged on the surface where the second lens 5 and the first lens 6 are glued, that is, the surface of the second lens 5 away from the display screen 1 ( Figure 1 and Figure 2 Since the second lens 5 and the first lens 6 are glued to each other, the phase retarder 9 and the polarization reflection element 8 are glued and arranged between the second lens 5 and the first lens 6.

[0105] According to the above example, the beam splitter 10, the phase retarder 9 and the polarization reflection element 8 are combined with the first optical element, which is also beneficial for assembly because multiple optical elements can be placed at one time.

[0106] The beam splitter 10 is, for example, a semi-transparent and semi-reflective film, the phase retarder 9 is, for example, a quarter-wave plate, and the polarized reflective element 8 is, for example, a polarized reflective film.

[0107] In some examples of this application, see Figure 2 The near-eye optical system also includes a polarizer 7, which is arranged on the side of the polarizing reflection element 8 away from the phase retarder 9, and the polarizer 7, the polarizing reflection element 8 and the phase retarder 9 are stacked to form a composite film material.

[0108] See also Figure 2 The near-eye optical system may further include a polarizer 7. The introduction of the polarizer 7 may reduce stray light, which is beneficial to improving the final imaging quality.

[0109] The polarizer 7 is, for example, a linear polarizer, and the transmission axis direction thereof can be along the horizontal direction, the vertical direction or any other direction.

[0110] Of course, an anti-reflection film may also be introduced into the above-mentioned composite film material.

[0111] In some examples of the present application, the display screen 1 is configured to emit circularly polarized light or natural light; when the light emitted by the display screen 1 is natural light, the light-emitting surface of the display screen 1 is also provided with a superimposed element for converting the natural light into circularly polarized light, and the superimposed element includes at least a phase delay plate and a linear polarizer.

[0112] When the display screen 1 emits natural light, the polarization state of the natural light needs to be converted first, so that the natural light is first converted into circularly polarized light and then incident on the optical elements on the left, and finally the light emitted by the first optical element enters the human eye 01 for imaging.

[0113] According to the above example, the phase retarder and the linear polarizer are combined into a stacked element and mounted on the light-emitting surface of the display screen 1. This can reduce the difficulty of assembly and enable two optical elements to be placed at the same time in one assembly.

[0114] The transmission axis of the linear polarizer may be in the horizontal direction, the vertical direction or any other direction.

[0115] The phase retarder is, for example, a quarter wave plate, which can realize the conversion of linear polarized light into circular polarized light and the conversion of circular polarized light into linear polarized light.

[0116] According to the near-eye optical system provided in the embodiment of the present application, see Figure 1 , the light propagation is as follows:

[0117] The display screen 1 emits circularly polarized light, which is transmitted through the first protective glass 2 and the second protective glass 3, becomes linearly polarized light (S light) after passing through the phase retarder 9 on the fourth surface 52 of the second lens 5, is reflected by the polarization reflection element 8, and again becomes circularly polarized light after passing through the phase retarder 9, is reflected by the beam splitting element 10 on the third surface 51 of the second lens 5, and then becomes linearly polarized light (P light) after passing through the phase retarder 9, and then is transmitted through the first lens 6 to enter the human eye 01.

[0118] According to the near-eye optical system provided in the embodiment of the present application, at least three optical lenses are used, namely Figure 1 The first lens 6, the second lens 5, and the third lens 4 are shown in FIG. Of course, a fourth lens 11 may be additionally introduced into the near-screen side of the near-eye optical system, as shown in FIG. Fig.12 .

[0119] The first lens 6 and the second lens 5 form a first optical element. The third lens 4 alone forms a second optical element, or the third lens 4 and the fourth lens 11 form a second optical element.

[0120] The near-eye optical system of the embodiment of the present application uses at least three lenses, namely, a first lens 6, a second lens 5 and a third lens 4, see Figure 1 and Figure 7 , the following describes these three lenses.

[0121] See also Figure 1 and Figure 7 The refractive index and dispersion coefficient of the materials used in the first lens 6, the second lens 5 and the third lens 4 are in the range of: 1.4 <n<2.0,20<v<75。

[0122] For example, the first lens 6, the second lens 5 and the third lens 4 have the same refractive index and dispersion coefficient, which are all designed as: n=1.54, v=56.3.

[0123] The center thickness T1 of the first lens 6 is in the range of 1mm≤T1≤8mm, and it includes two optical surfaces, namely a first surface 61 and a second surface 62 . The two surfaces may be aspherical surfaces. The first surface 61 is close to the display screen 1 , and the second surface 62 is far away from the display screen 1 .

[0124] Wherein, an anti-reflection film may be selectively provided on the second surface 62 of the first lens 6 .

[0125] The central thickness T2 of the second lens 5 is in the range of 1 mm ≤ T2 ≤ 10 mm, and the second lens 5 comprises two optical surfaces, namely a third surface 51 and a fourth surface 52 , which can be aspherical surfaces or plane surfaces. The third surface 51 is close to the display screen 1 , and the fourth surface 52 is far from the display screen 1 .

[0126] Among them, see Figure 2 A composite film material may be disposed on the fourth surface 52 of the second lens 5, and the composite film material may include a phase retarder 9, a polarized reflective element 8 (transmitting P light and reflecting S light) and a polarizer 7 (transmitting P light), and an anti-reflection film may also be introduced. A beam splitter 10 may be disposed on the third surface 51 of the second lens 5.

[0127] The fourth surface 52 of the second lens 5 is glued to the first surface 41 of the first lens 4 .

[0128] The first surface 61 and the fourth surface 52 may have the same surface shape, which is beneficial for gluing the two together.

[0129] Of course, the first surface 61 and the fourth surface 52 may have different surface shapes.

[0130] The central thickness T3 of the third lens 4 is in the range of 1 mm ≤ T3 ≤ 8 mm, and the third lens 4 comprises two optical surfaces, namely a fifth surface 41 and a sixth surface 42 , which can be aspherical surfaces or plane surfaces. The fifth surface 41 is close to the display screen 1 , and the sixth surface 42 is far from the display screen 1 .

[0131] The fifth surface 41 and the sixth surface 42 may be selectively provided with an anti-reflection film.

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

[0133] Example 1

[0134] The near-eye optical system provided in this embodiment 1 is shown in FIG. Figure 1 , which comprises a first optical element, a second optical element and a display screen 1 which are sequentially arranged along the same optical axis;

[0135] The first optical element comprises a first lens 6 and a second lens 5, and the first lens 6 and the second lens 5 are glued together, and the optical power φ1 of the first optical element is 0.04;

[0136] The second optical element only uses the third lens 4. In this case, the focal length of the edge area of ​​the third lens 4 is φ2, and φ2 is 0.015; wherein the edge area of ​​the third lens 4 is the area outside the 0.7 aperture;

[0137] The second lens 5 is located between the first lens 6 and the third lens 4 .

[0138] The near-eye optical system also includes a beam splitter 10, a phase retarder 9, a polarizing reflective element 8 and a polarizer 7 arranged along the same optical axis; wherein the beam splitter 10 is arranged on a surface (third surface 51) of the second lens 5 close to the display screen 1, and the phase retarder 9, the polarizing reflective element 8 and the polarizer 7 are stacked on a surface (fourth surface 52) of the second lens 5 away from the display screen 1.

[0139] Table 1 shows the specific optical parameters of the near-eye optical system of this embodiment 1.

[0140] Table 1

[0141]

[0142] The optical performance of the near-eye optical system provided in this embodiment 1 is demonstrated below through a dot array diagram, an MTF curve diagram, field curvature and distortion, and vertical axis chromatic aberration.

[0143] A point diagram refers to a diffuse pattern formed in a certain range when many light rays emitted from one point pass through the optical system and their intersection with the image plane is no longer concentrated at the same point due to aberration. It is mainly used to evaluate the imaging quality of the projection optical system.

[0144] The MTF curve is a modulation transfer function graph that characterizes the imaging clarity of an optical system through the contrast of black and white line pairs.

[0145] Vertical axis chromatic aberration is also called magnification chromatic aberration, which mainly refers to a complex main light ray on the object side, which becomes multiple light rays when it emerges on the image side due to the dispersion of the refraction system, and the difference in the focal position of blue light and red light on the image plane.

[0146] See also Figure 3 , the maximum value of the pixel in the point diagram is less than 46μm.

[0147] See also Figure 4 , MTF>0.29 at 39lp / mm.

[0148] See also Figure 5 , the maximum distortion occurs in 1 field of view, and the absolute value is less than 40%.

[0149] See also Figure 6 , the maximum color difference value is less than 200μm.

[0150] Example 2

[0151] The near-eye optical system shown in this embodiment 2 is shown in FIG. Figure 7 The basic optical structure is the same as that of the above-mentioned embodiment 1, and will not be described again here. The difference between the two is that:

[0152] (1) The focal power φ1 of the first optical element is 0.02, and the second optical element is only the third lens 4. The focal power of the edge area of ​​the third lens is φ2, and φ2 is 0.03.

[0153] (2) The optical parameters of the optical elements are different, as shown in Table 2 below.

[0154] Table 2

[0155]

[0156] The optical performance of the near-eye optical system provided by this embodiment 2 is demonstrated below through a dot array diagram, an MTF curve diagram, field curvature and distortion, and vertical axis chromatic aberration.

[0157] See also Figure 8 , the maximum value of the pixel in the point diagram is less than 32μm.

[0158] See also Fig. 9, MTF>0.2 at 39lp / mm.

[0159] See also Fig.10 , the maximum distortion occurs in 1 field of view, and the absolute value is less than 40%.

[0160] See also Fig.11 , the maximum color difference value is less than 200μm.

[0161] Example 3

[0162] The near-eye optical system shown in this embodiment 3 is shown in FIG. Fig.12 , which is different from the near-eye optical system shown in the aforementioned embodiment 1 in that:

[0163] (1) A fourth lens 11 is added to the second optical element, and the fourth lens 11 is located between the display screen 1 and the third lens 4; in this case, the second optical element includes the third lens 4 and the fourth lens 11;

[0164] (2) The focal power φ1 of the first optical element is 0.019;

[0165] The second optical element includes a third lens 4 and a fourth lens 11, and the combined focal length of the edge area of ​​the third lens 4 and the edge area of ​​the fourth lens 11 is φ2, and φ2 is 0.042;

[0166] The edge area of ​​the third lens 4 refers to the area outside the 0.7 diameter of the third lens 4, that is, the area occupying 70% of the third lens; the edge area of ​​the fourth lens 11 refers to the area outside the 0.7 diameter of the fourth lens 11, that is, the area occupying 70% of the fourth lens.

[0167] (3) The optical parameters of the optical elements are different, as shown in Table 3 below. Table 3 shows the specific optical parameters of the near-eye optical system.

[0168] Table 3

[0169]

[0170]

[0171] The optical performance of the near-eye optical system provided by this embodiment 3 is demonstrated below through a dot array diagram, an MTF curve diagram, field curvature and distortion, and vertical axis chromatic aberration.

[0172] See also Fig.13 , the maximum value of the pixel in the point diagram is less than 32μm.

[0173] See also Fig.14 , MTF>0.2 at 39lp / mm.

[0174] See also Fig.15 , the maximum distortion occurs in 1 field of view, and the absolute value is less than 40%.

[0175] See also Fig.16 , the maximum color difference value is less than 200μm.

[0176] According to another embodiment of the present application, a head-mounted display device is provided.

[0177] The head mounted display device comprises a housing and the near-eye optical system as described above.

[0178] The head mounted display device includes VR smart glasses or VR smart helmets, etc., which is not limited in the embodiments of the present application.

[0179] The specific implementation of the head-mounted display device of the embodiment of the present application can refer to the above-mentioned embodiments of the near-eye optical system, so it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here one by one.

[0180] The above embodiments focus on the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. Considering the simplicity of the text, they will not be repeated here.

[0181] Although some specific embodiments of the present application have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are only for illustration, not for limiting the scope of the present application. It should be understood by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims

1. A near-eye optical system, characterized in that: The optical device comprises a first optical element, a polarized reflective element (8), a phase retarder (9), a beam splitter (10), and a second optical element arranged along the same optical axis; wherein the phase retarder (9) is located between the beam splitter (10) and the polarized reflective element (8); The first optical element comprises n1 lenses, and n1≥2, and the optical power of the first optical element is φ1; The second optical element comprises n2 lenses, where n2≥1, and the focal power of the edge region of the second optical element is φ2; The near-eye optical system satisfies: 0<(φ1 / n1+φ2 / n2) / (φ1+φ2)≤3.

2. The near-eye optical system according to claim 1, wherein: The near-eye optical system satisfies: 0<(φ1 / n1+φ2 / n2) / (φ1+φ2)<1.

3. The near-eye optical system according to claim 1, characterized in that: The near-eye optical system satisfies: 0.5≤(φ1 / n1+φ2 / n2) / (φ1+φ2)≤0.

8.

4. The near-eye optical system according to claim 1, characterized in that: The first optical element comprises a first lens (6) and a second lens (5), and the first lens (6) and the second lens (5) are glued to each other; wherein the second lens (5) is located between the first lens (6) and the second optical element.

5. The near-eye optical system according to claim 1, characterized in that: The beam splitter (10) is located between the second optical element and the first optical element, and the phase retarder (9) and the polarization reflection element (8) are arranged in the first optical element; The optical focal length φ2 of the edge region of the second optical element is greater than 0.

6. The near-eye optical system according to any one of claims 1 to 5, characterized in that: The second optical element is a third lens (4), the optical focal length of the edge region of the third lens (4) is φ2, and φ2>0.

7. The near-eye optical system according to any one of claims 1 to 3, characterized in that: The second optical element comprises a third lens (4) and a fourth lens (11), wherein the third lens (4) is close to the first optical element, and the fourth lens (11) is far from the first optical element; The combined optical power of the edge area of ​​the third lens (4) and the edge area of ​​the fourth lens (11) is φ2, and φ2>0.

8. The near-eye optical system according to claim 1, characterized in that: The near-eye optical system further comprises a display screen (1), wherein the display screen (1) emits light for imaging display; The display screen (1) is located on a side of the second optical element facing away from the first optical element, and two layers of protective glass are stacked on the light-emitting surface of the display screen (1).

9. The near-eye optical system according to claim 8, characterized in that: The total thickness of the two layers of protective glass is H, and 0.7 mm≤H≤2 mm.

10. The near-eye optical system according to claim 4, characterized in that: The light splitting element (10) is arranged on a surface of the second lens (5) facing away from the first lens (6); The phase retarder (9) and the polarized reflection element (8) are sequentially stacked on the surface where the second lens (5) and the first lens (6) are glued together.

11. The near-eye optical system according to claim 10, characterized in that: The near-eye optical system further comprises a polarizer (7), wherein the polarizer (7) is arranged on a side of the polarizing reflective element (8) away from the phase retarder (9), and the polarizer (7), the polarizing reflective element (8) and the phase retarder (9) are stacked to form a composite film material.

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

13. A head mounted display device, characterized in that: include: shell; as well as, A near-eye optical system as claimed in any one of claims 1 to 12.

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