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; wherein the near-eye optical system comprises a polarization reflection element, a phase retarder and a light splitting element arranged along the same optical axis; the near-eye optical system further comprises a first lens and a second lens arranged along the optical axis, the polarization reflection element and the phase retarder are sequentially arranged between the first lens and the second lens, and the light splitting element is located on a side of the second lens away from the first lens; a surface of the first lens close to the polarization reflection element is a first surface, and the first surface satisfies: 0 2 +(D1 / 2) 2 ]*φ1≤1; wherein φ1 is an optical power of the first lens, S1 and D1 are a maximum sag and a radial aperture of the first surface respectively.

Description

TECHNICAL FIELD

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

[0002] With the development of the light and thin requirements of VR devices, the size of the display used in the VR device is getting smaller and smaller, and along with the requirement of the field of view angle getting larger and larger, which leads to the decline of the imaging definition of the VR device. At present, large FOV and high definition are the trend of VR development, but generally speaking, the larger the FOV is, the worse the image quality of the edge field of view will be, and how to ensure the imaging quality while ensuring the large FOV is a problem to be solved. 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.

[0004] In a first aspect, embodiments of the present application provide a near-eye optical system, the near-eye optical system comprising a polarization reflection element, a phase retarder and a light splitting element arranged along the same optical axis;

[0005] The near-eye optical system further comprises a first lens and a second lens arranged along the optical axis, the polarization reflection element and the phase retarder are arranged between the first lens and the second lens in sequence, and the light splitting element is located on a side of the second lens away from the first lens.

[0006] The surface of the first lens close to the polarization reflection element is a first surface, and the first surface satisfies: 0 2 +(D1 / 2) 2 ]*φ1≤1; wherein φ1 is the optical power of the first lens, S1 and D1 are the maximum sag and the radial aperture of the first surface respectively.

[0007] Optionally, the first surface of the first lens satisfies: 0.3 2 +(D1 / 2) 2 ]*φ1<0.7.

[0008] Optionally, the first surface of the first lens satisfies: 0.4 2 +(D1 / 2) 2 ]*φ1<0.6.

[0009] Optionally, in the radial direction from the center on the first surface, the slope of the sag of two adjacent points a and b is k, and k satisfies: -1≤k≤1; wherein the slope of the sag k is the ratio of the sag difference h1 between the adjacent points a and b and the diameter difference d1 between the points a and b, and the interval between the points a and b is ≤0.01mm.

[0010] Optionally, in the radial direction from the center on the first surface, the inflection point A of the slope of the sag is located at ≥10mm in the radial direction from the center on the first surface.

[0011] Optionally, the phase retarder and the polarization reflection element are stacked to form a superposition element.

[0012] The superposition element is arranged on the first surface of the first lens or on the surface of the second lens close to the first lens.

[0013] Optionally, the optical power φ1 of the first lens is 0.019≤φ1≤0.021;

[0014] The radial diameter D1 of the first surface of the first lens is 40mm≤D1≤42mm;

[0015] The maximum sag S1 of the first surface of the first lens is 1.5mm≤S1≤3mm.

[0016] Optionally, the light splitting element is arranged on the surface of the second lens away from the first lens.

[0017] Optionally, the near-eye optical system further comprises a display screen, the display screen is arranged on the side of the second lens away from the first lens, at least one lens is arranged between the display screen and the light splitting element, and the optical power of the at least one lens is positive or the combined optical power of all lenses is positive.

[0018] Optionally, a third lens is arranged between the display screen and the light splitting element, and the optical power of the third lens is >0.

[0019] Optionally, a double-layer protective glass is arranged on the light-emitting surface of the display screen.

[0020] The thickness of the double-layer protective glass is ≤5mm.

[0021] Optionally, the display screen is configured to emit circularly polarized light or natural light.

[0022] In the case that the light emitted by the display screen is natural light, a composite film is further arranged on the light-emitting surface of the display screen to convert the natural light into circularly polarized light, and the composite film at least comprises a phase retarder and a linear polarizer.

[0023] Optionally, a polarizer is arranged on the side of the polarization reflection element away from the phase retarder, and the phase retarder, the polarization reflection element and the polarizer are arranged in a stack.

[0024] In a second aspect, the present application provides a head-mounted display device. The head-mounted display device comprises:

[0025] a housing; and

[0026] The near-eye optical system according to the first aspect.

[0027] The present application has the following beneficial effects:

[0028] According to the near-eye optical system provided by the embodiments of the present application, by optimizing the surface shape of the optical lens in the optical path, the image quality of the edge field of view can be improved under the premise of ensuring a large field of view; and the volume of the entire near-eye optical system can be reduced based on the folded optical path design, so that the thin design of the near-eye optical system is realized.

[0029] Other features of the present application and the advantages thereof will become more apparent from the following detailed description of exemplary embodiments thereof with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0030] The accompanying drawings incorporated in and forming a part of the specification illustrate embodiments of the present application and, together with the description, serve to explain the principles of the present application.

[0031] Figure 1 A structure schematic diagram of the near-eye optical system provided by the embodiments of the present application;

[0032] Figure 2 A film attachment schematic diagram of the first surface of the first lens provided by the embodiments of the present application;

[0033] Figure 3 A surface shape schematic diagram of each lens of the near-eye optical system provided by the embodiments of the present application;

[0034] Figure 4 A curve diagram of the aperture and sagitta of the first surface of the first lens in the embodiments of the present application; Figure 3 A curve diagram of the aperture and sagitta of the first surface of the first lens in the embodiments of the present application;

[0035] Figure 5 A curve diagram of the aperture and sagitta slope of the first surface of the first lens in the embodiments of the present application; Figure 3 A curve diagram of the aperture and sagitta slope of the first surface of the first lens in the embodiments of the present application;

[0036] Figure 6 A point array diagram of the near-eye optical system shown in the embodiments of the present application; Figure 1 A point array diagram of the near-eye optical system shown in the embodiments of the present application;

[0037] Figure 7 A point array diagram of the near-eye optical system shown in the embodiments of the present application; Figure 1Modulation transfer function (MTF) curve diagram of the near-eye optical system shown;

[0038] Figure 8 For Figure 1 Field curvature and distortion diagram of the near-eye optical system shown;

[0039] Figure 9 For Figure 1 Vernier chromatic aberration diagram of the near-eye optical system shown;

[0040] Figure 10 Structure schematic diagram of the near-eye optical system provided by the embodiment of the present application No. 2;

[0041] Figure 11 For Figure 10 Point array diagram of the near-eye optical system shown;

[0042] Figure 12 For Figure 10 Modulation transfer function (MTF) curve diagram of the near-eye optical system shown;

[0043] Figure 13 For Figure 10 Field curvature and distortion diagram of the near-eye optical system shown;

[0044] Figure 14 For Figure 10 Vernier chromatic aberration diagram of the near-eye optical system shown;

[0045] Figure 15 Structure schematic diagram of the near-eye optical system provided by the embodiment of the present application No. 3;

[0046] Figure 16 For Figure 15 Point array diagram of the near-eye optical system shown;

[0047] Figure 17 For Figure 15 Modulation transfer function (MTF) curve diagram of the near-eye optical system shown;

[0048] Figure 18 For Figure 15 Field curvature and distortion diagram of the near-eye optical system shown;

[0049] Figure 19 For Figure 15 Vernier chromatic aberration diagram of the near-eye optical system shown.

[0050] Explanation of reference signs:

[0051] 1, display screen; 2, double-layer protective glass; 21, first glass layer; 22, second glass layer; 3, polarizer; 4, third lens; 41, fifth surface; 42, sixth surface; 5, second lens; 51, third surface; 52, fourth surface; 6, first lens; 61, first surface; 611, anti-reflection film; 62, second surface; 7, polarized reflection element; 8, phase retarder; 9, light splitting element; 01, human eye. DETAILED DESCRIPTION

[0052] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of the components and steps set forth in the examples, as well as the numerical expressions and numerical values, are not limiting to the scope of the present application unless specifically stated otherwise.

[0053] The following description of at least one exemplary embodiment is merely exemplary in nature and is in no way intended to limit the scope of the application, its application, or uses.

[0054] Techniques and equipment known to those of ordinary skill in the relevant art can not be discussed in detail, but should be considered part of the specification where appropriate.

[0055] In all examples shown and discussed herein, any specific value should be interpreted as merely exemplary and not as a limitation. Thus, other examples of the exemplary embodiments can have different values.

[0056] It should be noted that like numbers and letters refer to like items throughout the drawings, and once an item is defined in one drawing, it need not be discussed further in subsequent drawings.

[0057] 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.

[0058] According to an aspect of the embodiments of the present application, a near-eye optical system is provided, which is suitable for a wearable device. The wearable device can be a head-mounted display (HMD), such as a VR head-mounted display device. The VR head-mounted display device includes, for example, a VR smart glasses or a VR smart helmet, and the form of the head-mounted display device is not specifically limited in the embodiments of the present application.

[0059] The near-eye optical system provided by the embodiments of the present application is described below with reference to Figure 1, the near-eye optical system comprises a polarization reflection element 7, a phase retarder 8 and a light splitting element 9 arranged along the same optical axis, and further comprises a first lens 6 and a second lens 5 arranged along the optical axis, the polarization reflection element 7 and the phase retarder 8 are sequentially arranged between the first lens 6 and the second lens 5, and the light splitting element 9 is located on the side of the second lens 5 away from the first lens 6. Wherein, the surface of the first lens 6 close to the polarization reflection element 7 is a first surface 61, and the first surface 61 satisfies the parameter design: 0 < sqrt[S1 2 +(D1 / 2) 2 ]*φ1≤1, wherein φ1 is the optical power of the first lens 6, S1 and D1 are the maximum sag and the radial aperture of the first surface 61 respectively, and refer to Figure 3 .

[0060] According to the near-eye optical system provided by the above-mentioned embodiments of the present application, referring to the optical structure shown in Figure 1 , by reasonably constraining the three optical parameters of the first surface 61 of the first lens 6 arranged in the folded optical path, the surface shape of the first lens 6 is optimized. Wherein, the first surface 61 of the first lens 6 is designed to be adjacent to the polarization reflection element 7, for example.

[0061] In the embodiments of the present application, the surface shape of the first lens 6, such as the surface shape of the first surface 61, can ensure the improvement of the imaging quality of the edge field in the case of large field of view. Here, the large field of view is, for example, FOV of 105°.

[0062] From the prior art, the larger the FOV design of the near-eye optical system, the worse the image quality of the edge field. The near-eye optical system provided by the embodiments of the present application can ensure the imaging quality while ensuring the large FOV by optimizing the surface shape of at least one lens in the optical path, which solves the problem that the large FOV and high-definition imaging cannot be considered in the prior art.

[0063] In the near-eye optical system provided by the embodiments of the present application, the first surface 61 of the first lens 6 should satisfy the above-mentioned constraint condition: 0 < sqrt[S1 2 +(D1 / 2) 2 ]*φ1≤1, wherein φ1 is the optical power of the first lens 6 and the optical power φ1 should be positive, S1 and D1 are the maximum sag and the radial aperture of the first surface 61 respectively, and sqrt is the square root calculation.

[0064] For the constraint formula of the above-mentioned first surface 61, it should be noted that S1 2 and (D1 / 2) 2After the summation, a square root calculation is performed, and the result is multiplied by the optical power φ1 of the first lens 6. The resulting value should be in the range of 0 to 1 (including the end value 1).

[0065] According to the near-eye optical system provided in the embodiments of the present application, referring to Figure 1 the optical structure shown in the figure, Figure 6 the point array diagram of the near-eye optical system in Figure 1 is shown, for example, from Figure 6 It can be seen from the figure that in the full field of view range, the maximum value of the image points in the point array diagram is less than 66 μm, that is, clear imaging can still be achieved in the edge field of view.

[0066] The near-eye optical system provided in the embodiments of the present application is a folded optical path, specifically, the light splitting element 9, the phase retarder 8 and the polarization reflection element 7 are designed in the optical path, and the phase retarder 8 is located between the light splitting element 9 and the polarization reflection element 7.

[0067] The light splitting element 9 can transmit a part of light and reflect another part of light.

[0068] The light splitting element 9 is, for example, a semi-transparent and semi-reflective film.

[0069] It should be noted that the reflectivity and transmissivity of the light splitting element 9 can be flexibly adjusted according to specific needs, which is not limited in the embodiments of the present application.

[0070] The phase retarder 8 is, for example, a quarter-wave plate.

[0071] Of course, the phase retarder 8 can also be set to other phase retarders such as a half-wave plate according to needs.

[0072] In the near-eye optical system provided in the embodiments of the present application, the phase retarder 8 located in the folded optical path close to the human eye 01 can be used to change the polarization state of the light. For example, it is used to convert linearly polarized light into circularly polarized light, or to convert circularly polarized light into linearly polarized light.

[0073] The polarization reflection element 7 is a polarization reflector that reflects horizontally linearly polarized light and transmits vertically linearly polarized light, or any other specific angle linearly polarized light and transmits linearly polarized light in the direction perpendicular to the angle.

[0074] In the embodiments of the present application, the phase retarder 8 and the polarization reflection element 7 cooperate to analyze and transmit the light.

[0075] It is emphasized that the optical elements of the light splitting element 9, the phase retarder 8 and the polarization reflection element 7 can form a folded optical path on the side of the near-eye 01, and the arrangement positions of the above-mentioned optical elements are flexible, but it is necessary to ensure that the phase retarder 8 is between the light splitting element 9 and the polarization reflection element 7.

[0076] According to the near-eye optical system provided in the embodiments of the present application, by optimizing the surface shape of the optical lens in the optical path, the image quality of the edge field of view can be improved under the premise of ensuring a large field of view, and based on the design of the entire optical path as a folded optical path, the volume of the entire near-eye optical system can be reduced, and the thin design of the near-eye optical system can be realized.

[0077] The first surface 61 of the first lens 6 can satisfy: 0.3 < sqrt[S1 2 +(D1 / 2) 2 ]*phi1 < 0.7.

[0078] Further, the first surface 61 of the first lens 6 can satisfy: 0.4 < sqrt[S1 2 +(D1 / 2) 2 ]*phi1 < 0.6.

[0079] By continuously optimizing the first surface 61 of the first lens 6, the image quality of the edge field of view can be further improved, so that the user can obtain a better visual experience.

[0080] In some examples of the present application, referring to Figure 3 and Figure 4 , in the radial direction from the center on the first surface 61, the sagittal slope of the adjacent two points a and b is k, and k satisfies: -1 <= k <= 1; wherein the sagittal slope k is the ratio of the sagittal height difference h1 between the adjacent points a and b to the aperture difference d1 between the points a and b, and the interval between the points a and b is <= 0.01 mm.

[0081] The first lens 6 provided in the embodiments of the present application, referring to Figure 4 , Figure 4 shows the change of the sagittal height in the radial direction from the center point on the first surface 61.

[0082] In Figure 4 , the points a and b are adjacent points with a very close interval, for example, the interval is 0.01 mm. At this time, the sagittal slope k of the adjacent two points, i.e., the points a and b, can refer to Figure 4, the algorithm is as follows: (the ordinate of point a-the ordinate of point b) / (the abscissa of point a-the abscissa of point b), that is, h1 / d1 in the above example, and the value of k should be controlled in -1~1 (including -1 and 1). In this way, while optimizing the surface shape of the first lens 6, the slope of different regions of the first surface 61 of the first lens 6 can be prevented from being too large, so that the surface shape of the same surface is not too different, which is beneficial to reduce the difficulty of film pasting of the first surface 61.

[0083] In some examples of the present application, referring to Figure 5 , the inflection point A of the sagittal slope k is located at ≥10 mm in the radial direction from the center on the first surface 61.

[0084] When the absolute value of the sagittal slope k of the first surface 61 is controlled to be ≤1, and the slope inflection point A occurs at ≥10 mm in the radial direction from the center mentioned in the above example, the complexity of the surface shape of the first surface 61 (the first surface 61 is a curved surface, and the production process is complex) can be further reduced, the production difficulty of the lens can be reduced, and the process realizability of the curved film pasting can be ensured.

[0085] In some examples of the present application, referring to Figure 2 , the phase retarder 8 and the polarization reflection element 7 are stacked to form a superposition element. The superposition element can be arranged on the first surface 61 of the first lens 6, or on the surface of the second lens 5 close to the first lens 6.

[0086] Referring to Figure 1 , the first lens 6 is, for example, a lens close to the human eye 01, the second lens 5 is arranged along the same optical axis as the first lens 6, and the second lens 5 is away from the human eye 01 relative to the first lens 6.

[0087] Among them, the first lens 6 can include a first surface 61 away from the human eye 01 and a second surface 62 close to the human eye 01.

[0088] Among them, the second lens 5 can include a third surface 51 away from the human eye 01 and a fourth surface 52 close to the human eye 01, and the fourth surface 52 of the second lens 5 is close to the first surface 61 of the first lens 6.

[0089] In one example, referring to Figure 2 , the phase retarder 8 and the polarization reflection element 8 are sequentially stacked and arranged on the first surface 61 of the first lens 6. At this time, the first surface 61 can form a polarization reflection surface.

[0090] By directly supporting the phase retarder 8 and the polarization reflection element 7 by the first lens 6, a support in the optical path can be omitted, and the optical path assembly can be simplified.

[0091] Of course, the phase retarder 8 and the polarization reflection element 7 can also be stacked and arranged on the fourth surface 52 of the second lens 5.

[0092] It should be noted that no matter which of the above examples is used to assemble the phase retarder 8 and the polarization reflection element 7 in the optical path, the phase retarder 8 is ensured to be between the light splitting element 9 and the polarization reflection element 7.

[0093] In addition, the phase retarder 8 and the polarization reflection element 7 can also be independently arranged in the space between the second lens 5 and the first lens 6 by a support.

[0094] For the above-mentioned phase retarder 8 and polarization reflection element 7, both can be formed into a stacked element by optical glue. Among them, the phase retarder 8 is, for example, a quarter-wave plate, and the polarization reflection element 7 is, for example, a polarization reflection film.

[0095] In some examples of the present application, the optical power φ1 of the first lens 6 is 0.019≤φ1≤0.021, the radial aperture D1 of the first surface 61 of the first lens 6 is 40mm≤D1≤42mm, and the maximum sag S1 of the first surface 61 of the first lens 6 is 1.5mm≤S1≤3mm.

[0096] According to the near-eye optical system provided by the embodiment of the present application, the first surface 61 of the first lens 6 should satisfy the parameter design: 0 2 +(D1 / 2) 2 ]*φ1≤1.

[0097] For example, the optical power φ1 of the first lens 6 is 0.02807, the radial aperture D1 of the first surface 61 of the first lens 6 is 41.4mm, and the maximum sag S1 of the first surface 61 of the first lens 6 is 2.6mm.

[0098] For example, the optical power φ1 of the first lens 6 is 0.01996, the radial aperture D1 of the first surface 61 of the first lens 6 is 41.3mm, and the maximum sag S1 of the first surface 61 of the first lens 6 is 1.95mm.

[0099] For example, the optical power φ1 of the first lens 6 is 0.01981, the radial aperture D1 of the first surface 61 of the first lens 6 is 41.6 mm, and the maximum sag S1 of the first surface 61 of the first lens 6 is 1.8 mm.

[0100] According to the above examples, the size of the first lens 6 can also be well controlled, which is conducive to controlling the volume and weight of the entire near-eye optical system.

[0101] In some examples of the present application, referring to Figure 1 , the light splitting element 9 is arranged on the surface of the second lens 5 away from the first lens 6.

[0102] Referring to Figure 1 , the surface of the second lens 5 away from the first lens 6 is the third surface 51 thereof, that is, the light splitting element 9 can be arranged on the third surface 51. For example, the light splitting element 9 is a half-transmission half-reflection film.

[0103] When the light splitting element 9 is arranged on the third surface 51 and the light splitting element 9 is a half-transmission half-reflection film, the half-transmission half-reflection film can be arranged on the third surface 51 by coating or pasting.

[0104] Of course, the light splitting element 9 can also be supported on the third surface 51 side by a support.

[0105] The light splitting element 9, the phase retarder 8, and the polarization reflection element 7, in combination with a plurality of lenses, can form a folded light path.

[0106] In some examples of the present application, referring to Figure 1 , the near-eye optical system further comprises a display screen 1 arranged on the side of the second lens 5 away from the first lens 6, and at least one lens is arranged between the display screen 1 and the light splitting element 9, and the optical power of the at least one lens is positive or the combined optical power of all lenses is positive.

[0107] That is, the number of lenses between the light splitting element 9 (i.e., the half-transmission half-reflection film) and the display screen 1 is ≥1, and when only one lens is arranged therebetween, the optical power of the lens should be positive, and when two or more lenses are arranged therebetween, the combined optical power of the lenses should be controlled to be positive, which can effectively reduce the light incidence angle of the half-transmission half-reflection film, reduce the coating difficulty of the third surface 51 of the second lens 5, and also improve the image quality.

[0108] In some examples of the present application, referring to Figure 1 , Figure 10 and Figure 15The third lens 4 is arranged between the display screen 1 and the light splitting element 9, and the optical power of the third lens 4 is greater than 0.

[0109] According to the near-eye optical system provided in the embodiments of the present application, at least three lenses can be used in the whole optical path design, that is, the first lens 6 close to the human eye 01, the third lens 4 close to the display screen 1, and the second lens 5 between the first lens 6 and the third lens 4. That is to say, the optical scheme of the present application can realize the image quality of the edge field under the large field of view on the basis of the folded optical path by matching three lenses and optimizing the surface type of one of the lenses.

[0110] It should be noted that the number of lenses used in the near-eye optical system provided in the embodiments of the present application can be adjusted as needed, for example, the number of lenses on the side close to the display screen 1 can be increased.

[0111] That is to say, the near-eye optical system provided in the embodiments of the present application can also include four or more lenses. With the increase of the number of lenses, the total length of the system can be reduced and the image quality can be further improved, but the weight of the product can be affected.

[0112] In some examples of the present application, a double-layer protective glass 2 is arranged on the light-emitting surface of the display screen 1. The thickness of the double-layer protective glass 2 is less than or equal to 5 mm.

[0113] In the near-eye optical system provided in the embodiments of the present application, a double-layer protective glass 2 is designed in front of the display screen 1, which includes a first glass layer 21 and a second glass layer 22 as shown in the middle of the figure. Figure 1 The two glass layers can be bonded by, for example, optical adhesive.

[0114] The double-layer protective glass 2 designed on the light-emitting surface of the display screen 1 can effectively improve the tolerance of the optical scheme to the dirt on the screen surface.

[0115] However, considering the imaging quality and the weight of the product, the thickness of the double-layer protective glass 2 should not be too thick, and is preferably not more than 5 mm.

[0116] That is to say, referring to Figure 1 The light emitted by the display screen 1 is transmitted through the double-layer protective glass 2 on the surface, and then transmitted through the third lens 4 and the second lens 5, reflected through the first surface 61 of the first lens 6, reflected through the third surface 51 of the second lens 5, and finally transmitted through the second lens 5 and the first lens 6 to enter the human eye 01.

[0117] In some examples of the present application, the display screen 1 is configured to emit circularly polarized light or natural light. In the case where the light emitted by the display screen 1 is natural light, the light-emitting surface of the display screen 1 is further provided with a composite film (not shown in the figure) for converting natural light into circularly polarized light, and the composite film at least includes a phase retarder and a linear polarizer. Figure 1

[0118] The near-eye optical system further includes a display screen 1 that emits light for imaging display.

[0119] For example, the display screen 1 can emit RGB light to form a color image.

[0120] The display screen 1 can be a self-luminous screen such as an LCD, an LED, an OLED, a Micro-OLED, an ULED, etc., or a reflective screen such as a DMD, etc.

[0121] When the display screen 1 emits natural light, the natural light needs to be first converted in polarization state, so that the natural light is first converted into circularly polarized light before being incident into the optical elements on the left side, and finally the light emitted by the first lens 6 is incident into the human eye 01 for imaging.

[0122] According to the above example, the phase retarder and the linear polarizer are combined into a stacked element and attached to the light-emitting surface of the display screen 1, which can reduce the assembly difficulty and realize the simultaneous placement of two optical elements in one assembly.

[0123] The transmission axis direction of the linear polarizer can be along the horizontal direction, the vertical direction, or any other direction.

[0124] The phase retarder is, for example, a quarter-wave plate, which can realize the conversion of linearly polarized light into circularly polarized light and the conversion of circularly polarized light into linearly polarized light.

[0125] Specifically, the fast axis or the slow axis direction of the phase retarder attached to the light-emitting surface of the display screen 1 forms an angle of 45° with the transmission axis direction of the linear polarizer.

[0126] In some examples of the present application, the polarization reflection element 7 is provided with a polarizer 3 on the side away from the phase retarder 8, and the phase retarder 8, the polarization reflection element 7, and the polarizer 3 are stacked.

[0127] Referring to Figure 2 The near-eye optical system can further include a polarizer 3, and the introduction of the polarizer 3 can reduce stray light, which is advantageous for improving the final imaging quality.

[0128] The polarizer 3 is, for example, a linear polarizer, and the transmission axis direction of the linear polarizer can be along the horizontal direction, the vertical direction, or any other direction.​

[0129] The polarizer 3 may be located on a side of the polarizing reflective element 7 away from the phase retarder 8 , and the polarizer 3 , the polarizing reflective element 7 and the phase retarder 8 may be stacked to form a laminated element.

[0130] Of course, please continue to see Figure 2 , an anti-reflection film 611 may also be introduced into the above-mentioned stacked element.

[0131] The anti-reflection film 611 can be glued and arranged on the side of the polarization reflection element 7 facing away from the phase retarder 8, for example.

[0132] According to the near-eye optical system provided in the embodiment of the present application, at least three lenses are used, namely the first lens 6, the second lens 5, and the third lens 4 shown in the figure. Of course, the near-eye optical system includes but is not limited to three lenses, and the examples of lenses used can be adjusted as needed.

[0133] The near-eye optical system provided in the embodiment of the present application uses three lenses, namely the first lens 6, the second lens 5 and the third lens 4 mentioned above. The refractive index and dispersion coefficient of the materials used in the three lenses are in the range of: 1.4 <n<2.0,20<v<75。

[0134] In one example, the refractive index n and the dispersion coefficient v of the first lens 6, the second lens 5 and the third lens 4 are the same, and are all designed to be n3=1.54 and v3=56.3.

[0135] The first lens 6 has a center thickness T1 in the range of 1 mm ≤ T1 ≤ 8 mm and includes two optical surfaces, namely a first surface 61 and a second surface 62 , which may be aspherical. The first surface 61 is close to the display screen 1 , while the second surface 62 is far away from the display screen 1 .

[0136] Wherein, the first surface 61 of the first lens 6 is provided with the following Figure 2 The phase retarder 8, polarization reflection element 7 (transmits P light and reflects S light) and polarizer 3 (transmits P light) shown can of course also introduce an anti-reflection film 611.

[0137] An anti-reflection film material may be selectively provided on the second surface 62 of the first lens 6 .

[0138] The second lens 5 has a center thickness T2 in the range of 1 mm ≤ T2 ≤ 10 mm and includes two optical surfaces, namely a third surface 51 and a fourth surface 52 . These two surfaces can be aspherical or flat. The third surface 51 is close to the display screen 1 , while the fourth surface 52 is far away from the display screen 1 .

[0139] The light splitting element 9 can be arranged on the third surface 51 of the second lens 5.

[0140] An anti-reflection film can be arranged on the fourth surface 52 of the second lens 5.

[0141] The third lens 4 has a central thickness T3 in the range of 1mm≤T3≤8mm, and includes two optical surfaces, i.e., a fifth surface 41 and a sixth surface 42, which can be aspherical or planar. The fifth surface 41 is close to the display screen 1, and the sixth surface 42 is away from the display screen 1.

[0142] An anti-reflection film can be arranged on each of the two surfaces of the third lens 4.

[0143] Referring to Figure 1 , the light propagation process of the near-eye optical system is as follows:

[0144] The display screen 1 emits circularly polarized light, which is transmitted through the double-layer protective glass 2, the third lens 4 and the second lens 5, is changed into linearly polarized light (S light) by the phase retarder 8 on the first surface 61 of the first lens 6, is reflected by the polarization reflection element 7, is changed into circularly polarized light again by the phase retarder 8, is reflected by the light splitting element 9 on the third surface 51 of the second lens 5, is changed into linearly polarized light (P light) again by the phase retarder 8, is transmitted through the second surface 62 of the first lens 6, and enters the human eye 01.

[0145] The optical performance of the near-eye optical system provided in the embodiments of the present application is described below by way of Examples 1 to 3.

[0146] Example 1

[0147] Referring to Figures 1 to 5 , the near-eye optical system includes a first lens 6, a polarization reflection element 7, a phase retarder 8, a second lens 5, a light splitting element 9, a third lens 4, a double-layer protective glass 2 and a display screen 1 arranged along the same optical axis;

[0148] The double-layer protective glass 2 is arranged on the light-emitting surface of the display screen 1, the light splitting element 9 is arranged on the third surface 51 of the second lens 5, the phase retarder 8, the polarization reflection element 7 and the polarizer 3 form a superposition element arranged on the first surface 61 of the first lens 6, and the phase retarder 8 is located between the light splitting element 9 and the polarization reflection element 7; the third lens 4 is located between the display screen 1 and the light splitting element 9.

[0149] The first surface 61 satisfies the parameter design: 02 +(D1 / 2) 2 ]*φ1≤1, wherein the optical power φ1 of the first lens 6 is 0.02807, the radial aperture D1 of the first surface 61 of the first lens 6 is 41.4 mm, and the maximum sag S1 of the first surface 61 of the first lens 6 is 2.6 mm.

[0150] Table 1 shows the specific optical parameters of the near-eye optical system of the present embodiment 1.

[0151] Table 1

[0152]

[0153] The optical performance of the near-eye optical system provided in the present embodiment 1 can be shown as follows: Figures 6 to 9 Figure 6 is a schematic diagram of a spot diagram, Figure 7 is a MTF curve diagram, Figure 8 is a field curvature distortion diagram, Figure 9 is a lateral chromatic aberration diagram.

[0154] The spot diagram refers to a diffused pattern 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 FIG. 6, the maximum value of the image point in the spot diagram of the near-eye optical system provided in the present embodiment 1 is less than 66 μm, and the imaging of the entire field of view is very clear. Figure 6 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 FIG. 7, the MTF of the near-eye optical system provided in the present embodiment 1 is >0.2 at 40 lp / mm, and the imaging is clear.

[0155] Figure 7 Referring to FIG. 8, the maximum distortion of the near-eye optical system provided in the present embodiment 1 occurs at 1 field of view, and the absolute value is less than 40%.

[0156] Referring to FIG. 9, the maximum chromatic aberration value of the near-eye optical system provided in the present embodiment 1 is less than 190 μm. Figure 8 Lateral 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 dispersion of the refractive system, and the difference in the focal point positions of the blue light and the red light on the image plane. Referring to FIG. 10, the maximum chromatic aberration value of the near-eye optical system provided in the present embodiment 1 is less than 190 μm.

[0157] Figure 9 Embodiment 2

[0158] Referring to FIG. 11, the maximum value of the image point in the spot diagram of the near-eye optical system provided in the present embodiment 2 is less than 66 μm, and the imaging of the entire field of view is very clear.

[0159] Referring to FIG. 12, the MTF of the near-eye optical system provided in the present embodiment 2 is >0.2 at 40 lp / mm, and the imaging is clear. Figure 10 ​​​The optical structure provided in Embodiment 2 is basically the same as the optical structure of Embodiment 1, and the difference between the two is that the optical power φ1 of the first lens 6 is 0.01996, the radial aperture D1 of the first surface 61 of the first lens 6 is 41.3 mm, and the maximum sag S1 of the first surface 61 of the first lens 6 is 1.95 mm. In addition, the optical parameters of the near-eye optics provided in Embodiment 2 can be seen in Table 2 below.

[0160] Table 2

[0161]

[0162] The optical performance of the near-eye optical system provided in Embodiment 2 can be as shown in Figures 11 to 14 . Figure 11 is a schematic diagram of a point array, Figure 12 is an MTF curve diagram, Figure 13 is a field curvature distortion diagram, Figure 14 is a vertical axis chromatic aberration diagram.

[0163] As shown in Figure 11 , the maximum value of the image point in the point array of the near-eye optical system provided in Embodiment 2 is less than 87 μm, and the imaging of the entire field of view is clear.

[0164] As shown in Figure 12 , the MTF of the near-eye optical system provided in Embodiment 2 is >0.2 at 40 lp / mm, and the imaging is clear.

[0165] As shown in Figure 13 , the maximum distortion of the near-eye optical system provided in Embodiment 2 occurs at 1 field of view, and the absolute value is less than 40%.

[0166] As shown in Figure 14 , the maximum chromatic aberration value of the near-eye optical system provided in Embodiment 2 is less than 190 μm.

[0167] Embodiment 3

[0168] As shown in Figure 15 , the optical structure provided in Embodiment 3 is basically the same as the optical structure of Embodiment 1, and the difference between the two is that the optical power φ1 of the first lens 6 is 0.01981, the radial aperture D1 of the first surface 61 of the first lens 6 is 41.6 mm, and the maximum sag S1 of the first surface 61 of the first lens 6 is 1.8 mm. In addition, the optical parameters of the near-eye optics provided in Embodiment 3 can be seen in Table 3 below.

[0169] Table 3

[0170]

[0171] The optical performance of the near-eye optical system provided in this embodiment 3 can be as follows: Figures 16 to 19 As shown: Figure 16 is a point diagram diagram. Figure 17 is the MTF curve graph, Figure 18 is the field curvature distortion diagram, Figure 19 This is a diagram of vertical chromatic aberration.

[0172] See also Figure 16 As shown, in the near-eye optical system provided by this embodiment 3, the maximum value of the image point in the point diagram is less than 106 μm, and the image of the entire field of view is very clear.

[0173] See also Figure 17 As shown, the near-eye optical system provided in this embodiment 3 has an MTF greater than 0.2 at 40 lp / mm, and the imaging is clear.

[0174] See also Figure 18 As shown, in the near-eye optical system provided by this embodiment 3, the maximum distortion occurs in one field of view, and the absolute value is less than 40%.

[0175] See also Figure 19 As shown, the near-eye optical system provided by this embodiment 3 has a maximum chromatic aberration value of less than 190 μm.

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

[0177] The head-mounted display device includes 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, and therefore 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 for illustration only and are not intended to limit the scope of the present application. It should be understood by those skilled in the art that the above examples 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 near-eye optical system comprises a polarization reflection element (7), a phase retarder (8), and a beam splitter (9) arranged along the same optical axis; The near-eye optical system further comprises a first lens (6) and a second lens (5) arranged along the optical axis, the polarizing reflection element (7) and the phase retarder (8) are sequentially arranged between the first lens (6) and the second lens (5), and the beam splitter (9) is located on a side of the second lens (5) away from the first lens (6); The surface of the first lens (6) close to the polarized reflective element (7) is a first surface (61), and the first surface (61) satisfies: 0<sqrt[S1 2 +(D1 / 2) 2 ]*φ1≤1; wherein φ1 is the optical power of the first lens (6), S1 and D1 are the maximum sag height and radial diameter of the first surface (61), respectively; The phase retarder (8) and the polarized reflective element (7) are stacked to form a superimposed element; the superimposed element is provided on the first surface (61) of the first lens (6), or on the surface of the second lens (5) close to the first lens (6); The light splitting element (9) is arranged on a surface of the second lens (5) away from the first lens (6); The near-eye optical system further comprises a display screen (1), wherein the display screen (1) is arranged on a side of the second lens (5) facing away from the first lens (6), and at least one lens is arranged between the display screen (1) and the beam splitting element (9), and the optical power of the at least one lens is positive or the combined optical power of all lenses is positive; A third lens (4) is provided between the display screen (1) and the light splitting element (9).

2. The near-eye optical system according to claim 1, wherein: The first surface (61) of the first lens (6) satisfies: 0.3<sqrt[S1 2 +(D1 / 2) 2 ]*φ1<0.

7.

3. The near-eye optical system according to claim 1, wherein: The first surface (61) of the first lens (6) satisfies: 0.4<sqrt[S1 2 +(D1 / 2) 2 ]*φ1<0.

6.

4. The near-eye optical system according to claim 1, wherein: In the radial direction from the center on the first surface (61), the sagittal slope of two adjacent points a and b is k, and k satisfies: -1≤k≤1; wherein the sagittal slope k is the ratio of the sagittal difference h1 between adjacent points a and b to the caliber difference d1 between points a and b, and the interval between points a and b is ≤0.01 mm.

5. The near-eye optical system according to claim 4, wherein: In the radial direction from the center of the first surface (61), the inflection point A of the sagittal slope is located at a position ≥10 mm in the radial direction from the center of the first surface (61).

6. The near-eye optical system according to claim 1, wherein: The optical power φ1 of the first lens (6) is 0.019≤φ1≤0.021; The radial diameter D1 of the first surface (61) of the first lens (6) is 40 mm ≤ D1 ≤ 42 mm; The maximum sagittal height S1 of the first surface (61) of the first lens (6) is 1.5 mm ≤ S1 ≤ 3 mm.

7. The near-eye optical system according to claim 1, wherein: The optical power of the third lens (4) is positive.

8. The near-eye optical system according to claim 7, wherein: A double layer of protective glass (2) is provided on the light-emitting surface of the display screen (1); The thickness of the double-layer protective glass (2) is ≤5 mm.

9. The near-eye optical system according to claim 8, wherein: 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 further provided with a composite film material for converting the natural light into circularly polarized light, and the composite film material at least includes a phase delay plate and a linear polarizer.

10. The near-eye optical system according to claim 1, wherein: A polarizer (3) is provided on the side of the polarized reflective element (7) facing away from the phase retarder (8), and the phase retarder (8), the polarized reflective element (7) and the polarizer (3) are stacked.

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

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