Near-eye optical system and head-mounted display device

Abstract

Embodiments of the present application provide a near-eye optical system and a head-mounted display device; the near-eye optical system comprises a light splitting element, a phase retarder and a polarization reflector arranged along the same optical axis, and the phase retarder is located between the light splitting element and the polarization reflecter; the near-eye optical system further comprises a lens group, at least one lens in the lens group is located in the folded optical path formed by the light splitting element, the phase retarder and the polarization reflector, the polarization reflector forms a first reflection surface, and the light splitting element forms a second reflection surface; wherein the optical power of the first reflection surface is phi1, the optical power of the second reflection surface is phi2, the optical power of the near-eye optical system is phi, and the near-eye optical system satisfies the following relationship: 0.6<(phi1+phi2) / phi<1.1.

Description

TECHNICAL FIELD

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

[0002] With the development of virtual reality (VR) technology, the forms and types of VR products are increasingly diverse, and the application fields are increasingly wide. The current VR products usually transmit and magnify the display screen through an optical system, and then transmit the output image to the human eye. The human eye receives a virtual image of the display screen after magnification, so as to achieve the purpose of large-screen viewing through the VR product.

[0003] To solve the problem of too many lenses and heavy products in the straight-through VR optical path design, a Pancake design scheme is proposed. However, although the existing Pancake optical path can reduce the number of lenses used, the imaging quality is poor, which affects the wearing experience of users. SUMMARY

[0004] The purpose of the present application is to provide a new technical solution for a near-eye optical system and a head-mounted display device.

[0005] In a first aspect, the present application provides a near-eye optical system. The near-eye optical system comprises a light splitting element, a phase retarder and a polarization reflector arranged along the same optical axis, and the phase retarder is located between the light splitting element and the polarization reflector;

[0006] The near-eye optical system further comprises a lens group, at least one lens in the lens group is located in a folded optical path formed by the light splitting element, the phase retarder and the polarization reflector, the polarization reflector forms a first reflection surface, and the light splitting element forms a second reflection surface;

[0007] Wherein, the optical power of the first reflection surface is φ1, the optical power of the second reflection surface is φ2, the optical power of the near-eye optical system is φ, and the near-eye optical system satisfies the following relationship:

[0008] 0.6<(φ1+φ2) / φ<1.1.

[0009] Optionally, the near-eye optical system satisfies: 0.08<|φ-φ2| / φ<0.4.

[0010] Optionally, the sum of the optical powers of all lenses between the light splitting element and the human eye is φ3, and the near-eye optical system satisfies: 2.2<(φ1+φ2) / φ3<9.1.

[0011] Optionally, the near-eye optical system has an optical power of φ, and satisfies 0.65 < |φ-φ3| / φ < 0.9.

[0012] Optionally, the near-eye optical system further comprises a display screen, which is arranged on a side of the light splitting element away from the phase retarder.

[0013] The near-eye optical system has a field of view of FOV, an image height of H, and an axial distance of BFL from the light emitting surface of the display screen to the light splitting element, and satisfies 1.1 < tan(FOV / 2)*H / BFL < 10.5.

[0014] Optionally, the near-eye optical system satisfies 0.18 < tan(FOV / 2)*H / R < 0.4, where R is a radius of curvature of the light splitting element.

[0015] Optionally, the lens group comprises a first lens and a second lens arranged along the optical axis, the first lens is located away from the display screen, and the second lens is located close to the display screen.

[0016] The light splitting element and the phase retarder are arranged on at least one side of the second lens, and the polarization reflector is arranged on any side of the first lens.

[0017] Optionally, the light splitting element is arranged on a surface of the second lens close to the display screen, the phase retarder is arranged on a surface of the second lens away from the display screen, and the polarization reflector is arranged on any surface of the first lens.

[0018] The surface of the first lens on which the polarization reflector is arranged forms the first reflecting surface, and the surface of the second lens on which the light splitting element is arranged forms the second reflecting surface.

[0019] Optionally, the lens group comprises a first lens, a second lens, and a third lens arranged along the optical axis, the first lens is located away from the display screen, the third lens is located close to the display screen, and the second lens is arranged between the first lens and the third lens.

[0020] The light splitting element is arranged on any side of the third lens, the phase retarder is arranged on any side of the second lens, and the polarization reflector is arranged on any side of the first lens.

[0021] Optionally, the light splitting element is arranged on a surface of the third lens close to the display screen, the phase retarder is arranged on a surface of the second lens close to the display screen, and the polarization reflector is arranged on a surface of the first lens close to the display screen.

[0022] The first lens sets a surface of the polarization reflector to form the first reflection surface, and the third lens sets a surface of the light splitting element to form the second reflection surface.

[0023] Optionally, the light splitting element is arranged on a surface of the second lens close to the display screen, the phase retarder is arranged on a surface of the second lens away from the display screen, and the polarization reflector is arranged on a surface of the first lens close to the display screen.

[0024] The first lens sets a surface of the polarization reflector to form the first reflection surface, and the second lens sets a surface of the light splitting element to form the second reflection surface.

[0025] Optionally, the display screen is configured to emit circularly polarized light or natural light.

[0026] In a case where the light emitted by the display screen is natural light, a light-emitting surface of the display screen is 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 retarder.

[0027] In a second aspect, the present application provides a head-mounted display device. The head-mounted display device comprises:

[0028] a housing; and

[0029] The near-eye optical system according to the first aspect.

[0030] An advantage of the present application is that:

[0031] According to the near-eye optical system provided by the embodiments of the present application, the light splitting element, the phase retarder, the polarization reflector and the lens group are introduced in the optical path design, and the folding optical path can be formed by combination, the incident light is folded back at least once between the polarization reflector and the light splitting element, and the relationship among the optical power φ1 of the first reflection surface formed by the polarization reflector, the optical power φ2 of the second reflection surface formed by the light splitting element and the optical power φ of the entire near-eye optical system is reasonably constrained, so that the near-eye optical system has excellent imaging quality on the basis of forming a compact optical architecture, and the entire near-eye optical system can obtain better optical performance.

[0032] Other features of the present application, and their advantages, will become apparent from the following detailed description of exemplary embodiments of the present application with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0033] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present application and together with the description, serve to explain the principles of the present application.

[0034] Figure 1 Structure diagram of a near-eye optical system provided by an embodiment of the present application;

[0035] Figure 2 For Figure 1 Modulation transfer function (MTF) curve diagram of the near-eye optical system shown;

[0036] Figure 3 For Figure 1 Field curvature and distortion diagram of the near-eye optical system shown;

[0037] Figure 4 For Figure 1 Vernier chromatic aberration diagram of the near-eye optical system shown;

[0038] Figure 5 Structure diagram of a near-eye optical system provided by an embodiment of the present application;

[0039] Figure 6 For Figure 5 Modulation transfer function (MTF) curve diagram of the near-eye optical system shown;

[0040] Figure 7 For Figure 5 Field curvature and distortion diagram of the near-eye optical system shown;

[0041] Figure 8 For Figure 5 Vernier chromatic aberration diagram of the near-eye optical system shown;

[0042] Figure 9 Structure diagram of a near-eye optical system provided by an embodiment of the present application;

[0043] Figure 10 For Figure 9 Modulation transfer function (MTF) curve diagram of the near-eye optical system shown;

[0044] Figure 11 For Figure 9 Field curvature and distortion diagram of the near-eye optical system shown;

[0045] Figure 12 For Figure 9 Vernier chromatic aberration diagram of the near-eye optical system shown;

[0046] Figure 13 Structure diagram of a near-eye optical system provided by an embodiment of the present application;

[0047] Figure 14 For Figure 13 Modulation transfer function (MTF) curve diagram of the near-eye optical system shown;

[0048] Figure 15For Figure 13 Field curvature and distortion map of the near-eye optical system shown;

[0049] Figure 16 For Figure 13 Vernier chromatic aberration map of the near-eye optical system shown;

[0050] Figure 17 For the structure schematic diagram of the near-eye optical system provided by the embodiment of the present application is five;

[0051] Figure 18 For Figure 17 Modulation transfer function (MTF) curve of the near-eye optical system shown;

[0052] Figure 19 For Figure 17 Field curvature and distortion map of the near-eye optical system shown;

[0053] Figure 20 For Figure 17 Vernier chromatic aberration map of the near-eye optical system shown.

[0054] Explanation of reference signs:

[0055] 1, first lens; 11, first surface; 12, second surface; 2, second lens; 21, third surface; 22, fourth surface; 3, third lens; 31, fifth surface; 32, sixth surface; 4, light splitting element; 5, phase retarder; 6, polarizing reflector; 7, display screen; 01, human eye. DETAILED DESCRIPTION

[0056] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. Note that the relative arrangement, numerical expressions, and numerical values of the components and steps set forth in these embodiments are not limiting to the scope of the present application unless otherwise specifically stated.

[0057] The following description of at least one exemplary embodiment is merely exemplary in nature and is in no way intended to limit the application or its application or uses.

[0058] 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.

[0059] In all examples shown and discussed herein, any specific values should be interpreted as merely exemplary and not as a limitation. Thus, other examples of the exemplary embodiments can have different values.

[0060] It should be noted that like reference numerals and characters refer to like elements throughout the following figures and the detailed description, and thus, discussion of the same will not be repeated in connection with the following figures and the detailed description.

[0061] 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.

[0062] 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 display device. The form of the VR display device includes, for example, a VR smart glasses or a VR smart helmet, and the form of the VR display device is not specifically limited in the embodiments of the present application.

[0063] The near-eye optical system provided by the embodiments of the present application is shown in Figure 1 The near-eye optical system includes a light splitting element 4, a phase retarder 5 and a polarization reflector 6 arranged along the same optical axis, and the phase retarder 5 is located between the light splitting element 4 and the polarization reflector 6. The near-eye optical system further includes a lens group, at least one lens in the lens group is located in the folded optical path formed by the light splitting element 4, the phase retarder 5 and the polarization reflector 6. The polarization reflector 6 forms a first reflecting surface, the light splitting element 4 forms a second reflecting surface, the optical power of the first reflecting surface is φ1, the optical power of the second reflecting surface is φ2, the optical power of the near-eye optical system is φ, and the near-eye optical system satisfies: 0.6<(φ1+φ2) / φ<1.1.

[0064] According to the near-eye optical system provided by the embodiments of the present application, the polarization reflector 6, the phase retarder 5 and the light splitting element 4 and other optical films are introduced into the optical architecture. These optical films are matched with the lens group, and by reasonably arranging the positions of the optical films and the lenses in the lens group, the light rays for imaging display incident into the near-eye optical system can be folded back at least once between the polarization reflector 6 and the light splitting element 4. In this way, the imaging quality can be ensured on the premise of reducing the number of lenses, and the optical imaging effect of the folded optical path can be effectively improved.

[0065] The near-eye optical system provided by the embodiments of the present application is shown in Figure 1The polarization reflector 6 is located on one side close to the human eye 01, the light splitting element 4 is located on one side close to the display screen 7, the phase retarder 5 is located between the light splitting element 4 and the polarization reflector 6, the polarization reflector 6 is used to form a first reflecting surface, the light splitting element 4 is used to form a second reflecting surface, one or more lenses can be arranged between the two reflecting surfaces, the light rays are folded back between the two reflecting surfaces and pass through at least one lens, and the near-eye optical system is compact, small and light in size on the premise of ensuring imaging quality based on the folding of the light path and the lens.

[0066] In the near-eye optical system provided by the embodiments of the present application, by controlling the ratio range of the sum (i.e. φ1+φ2) of the optical power φ1 of the first reflecting surface formed by the polarization reflector 6 and the optical power φ2 of the second reflecting surface formed by the light splitting element 4 to the optical power φ of the entire near-eye optical system, the near-eye optical system based on the folded light path can obtain better optical performance, so that better imaging effect can be obtained.

[0067] The near-eye optical system provided by the embodiments of the present application is based on the folded light path design, a smaller number of lenses such as 1-3 lenses can be used, and by constraining the optical power of the two reflecting surfaces in the folded light path, good imaging effect can be achieved.

[0068] The near-eye optical system provided by the embodiments of the present application can have clear imaging, better resolution, small field curvature and small distortion in the entire field of view range under the condition of using fewer lenses.

[0069] It should be noted that the near-eye optical system provided by the embodiments of the present application includes but is not limited to using 1-3 lenses, and the number of lenses can also be increased as needed.

[0070] The light splitting element 4 can transmit a part of light and reflect another part of light. The light splitting element 4 is, for example, a half-reflective half-transmissive film (BS film).

[0071] It should be noted that the reflectivity and transmissivity of the light splitting element 4 can be flexibly adjusted according to specific needs, which is not limited in the embodiments of the present application.

[0072] The phase retarder 5 is 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. The phase retarder 5 is, for example, a quarter-wave plate (QWB film).

[0073] Of course, the phase retarder 5 here can also be set to other phase retarders such as a half-wave plate according to needs.

[0074] The polarization reflector 6 is a polarization reflector that reflects horizontally linearly polarized light and transmits vertically linearly polarized light, or a polarization reflector that reflects linearly polarized light of any other specific angle and transmits linearly polarized light of a direction perpendicular to the angle. The polarization reflector 6 is, for example, a polarization reflection film (RP film).

[0075] Referring to Figure 1 The near-eye optical system provided by the embodiment of the present application has a folded optical path as follows: light rays for imaging display, which are circularly polarized light, exit from the display screen 7 and are transmitted through the light splitting element 4, for example, with 50% of the light energy being converted into linearly polarized light. The linearly polarized light passes through the phase retarder 5 and is converted into linearly polarized light whose polarization direction is perpendicular to the transmission axis of the polarization reflector 6. The linearly polarized light is reflected by the polarization reflector 6 and passes through the phase retarder 5 again to be converted into circularly polarized light. The circularly polarized light then enters the light splitting element 4, 25% of the light rays being reflected. The reflected light passes through the phase retarder 5 and is converted into linearly polarized light. Due to the reflection, the polarization direction of the linearly polarized light is parallel to the transmission axis of the polarization reflector 6. At this time, the light rays can exit and enter the human eye 01 to form an image.

[0076] It should be noted that the above description of the folded optical path does not introduce a lens, because a lens can be arranged at any suitable position between the light paths of the light splitting element 4, the phase retarder 5, and the polarization reflector 6 as needed, which is not limited herein.

[0077] The lens in the near-eye optical system can be used to support the light splitting element 4, the phase retarder 5, and the polarization reflector 6. Of course, the lens can also reduce aberration.

[0078] In some examples of the present application, in the near-eye optical system, the light splitting element 4 is used to form a second reflecting surface, the optical power of the second reflecting surface is φ2, the optical power of the near-eye optical system is φ, and the near-eye optical system satisfies: 0.08<|φ-φ2| / φ<0.4.

[0079] By constraining the optical power φ2 of the second reflecting surface, i.e., the light splitting element 4 in the folded optical path, and the optical power of the entire near-eye optical system, the imaging effect can be further ensured.

[0080] Further, the near-eye optical system satisfies: 0.089≤|φ-φ2| / φ<0.26. On this basis, the optical performance of the near-eye optical system is further optimized.

[0081] The optical power φ1 of the first reflecting surface is, for example, -0.023≤φ1≤0.

[0082] The optical power φ2 of the second reflecting surface is positive, and further, the optical power φ2 of the second reflecting surface can be 0.037 < φ2 < 0.053.

[0083] In the folded optical path, by reasonably distributing and mutually matching the optical power φ1 of the first reflecting surface formed by the polarization reflector 6 and the optical power φ2 of the second reflecting surface formed by the light splitting element 4, the imaging aberration can be corrected, and the imaging quality can be improved.

[0084] In some examples of the present application, the sum of the optical powers of all lenses between the light splitting element 4 and the human eye is φ3, and the near-eye optical system satisfies 2.2 < (φ1 + φ2) / φ3 < 9.1.

[0085] Referring to Figure 1 The light reflected by the light splitting element 4, for example, a half-reflection half-transmission film, will pass through all the lenses between the light splitting element 4 and the human eye 01 (i.e., all the lenses in the straight-through optical path) in turn, and finally be incident on the human eye 01. By controlling the ratio of the sum of the optical power φ1 of the first reflecting surface formed by the polarization reflector 6 and the optical power φ2 of the second reflecting surface formed by the light splitting element 4 to the sum of the optical powers φ3 of all the lenses between the light splitting element 4 and the human eye 01 in the range of 2.2-9.1, the near-eye optical system can have better optical performance and ensure a larger field of view, for example, the field of view of the near-eye optical system can reach 75°-110°, which can provide the user with a better immersive experience.

[0086] According to the near-eye optical system provided by the embodiments of the present application, the range of (φ1 + φ2) / φ3 can also be optimized to 2.28, 2.94, 3.05, 4.56, and 9.06.

[0087] In some examples of the present application, the optical power of the near-eye optical system is φ, and the near-eye optical system satisfies 0.65 < |φ-φ3| / φ < 0.9.

[0088] Further, the value of |φ-φ3| / φ can be selected from any one of 0.69, 0.71, 0.73, 0.8, and 0.88, and can be determined according to the requirement of the imaging quality, which can ensure the imaging quality.

[0089] The optical power of the first reflecting surface formed by the polarization reflector 6 can be ≤ 0.

[0090] Further, the optical power of the first reflecting surface formed by the polarization reflector 6 is in the range of, for example, -0.022695 ≤ φ1 ≤ 0.

[0091] The optical power of the second reflecting surface formed by the light splitting element 4 can be positive.

[0092] Further, the light power of the second reflecting surface formed by the light splitting element 4 is for example in the range 0.037 < φ2 < 0.076.

[0093] In the optical path, the first reflecting surface formed by the polarization reflector 6 and the second reflecting surface formed by the light splitting element 4 can be used to correct imaging aberration by reasonable distribution of the light power.

[0094] In some examples of the present application, referring to Figure 1 , the near-eye optical system further comprises a display screen 7, which is arranged on the side of the light splitting element 4 away from the phase retarder 5. The near-eye optical system has a field of view FOV, an image height H, and an axial distance BFL from the light splitting element 4 to the light emitting surface of the display screen 7. The near-eye optical system satisfies the relationship: 1.1 < tan(FOV / 2)*H / BFL < 10.5.

[0095] In the above examples, the axial distance BFL from the light splitting element 4 to the light emitting surface of the display screen 7 is also the back focal length of the near-eye optical system. According to the optical parameter constraints in the above examples, the back focal length of the near-eye optical system and the size and quality of the imaging can be reasonably controlled while ensuring a large field of view.

[0096] Further, the near-eye optical system satisfies 1.3 < tan(FOV / 2)*H / BFL < 10.5.

[0097] The display screen 7 can emit light for imaging display. The display screen 7 can emit RGB light, for example, to form a color image.

[0098] The display screen 7 can be a self-luminous screen such as LCD, LED, OLED, Micro-OLED, ULED, etc., or a reflective screen such as DMD, etc.

[0099] A screen protection element can be arranged on the light emitting surface of the display screen 7.

[0100] The near-eye optical system provided by the embodiments of the present application can be matched with a medium or small size display screen. For example, the size of the display screen 7 can be no more than 2.1 inches. In the present application, by reasonably distributing the light power in the optical path, a larger field of view and better imaging quality can be ensured in the case of a small size display screen, and the weight of the near-eye optical system can also be reduced.

[0101] Of course, the near-eye optical system provided by the embodiments of the present application can also be matched with a large size screen, which is not limited in the present application.

[0102] In some examples of the present application, referring to Figure 1 , the near-eye optical system further comprises a display screen 7, which is arranged on the side of the light splitting element 4 away from the phase retarder 5. The field of view of the near-eye optical system is FOV, the image height of the near-eye optical system is H, the radius of curvature of the light splitting element 4 is R, and the near-eye optical system satisfies: 0.18 < tan(FOV / 2)*H / R < 0.4.

[0103] According to the optical parameter constraint in the above examples, the radius of curvature of the light splitting element 4 can be reasonably controlled under the premise of ensuring a large field of view, so that the surface shape of the light splitting element 4 can be controlled, and the manufacturing difficulty of the surface shape of the light splitting element 4 can be reduced.

[0104] In some examples of the present application, referring to Figure 1 , Figure 5 and Figure 9 , the lens group comprises a first lens 1 and a second lens 2 arranged along the optical axis, the first lens 1 is located away from the display screen 7, the second lens 2 is located close to the display screen 7, the light splitting element 4 and the phase retarder 5 are arranged on at least one side of the second lens 2, and the polarized reflector 6 is arranged on any side of the first lens 1.

[0105] Referring to Figure 1 and Figure 5 , the near-eye optical system provided by the embodiments of the present application can use only two lenses, i.e. the first lens 1 and the second lens 2 described above. Among them, the first lens 1 is located on one side of the near-eye 01, and the second lens 2 is located on one side of the display screen 7.

[0106] When the first lens 1 and the second lens 2 are used in the near-eye optical system, the second lens 2 can be between the light splitting element 4 and the phase retarder 5, and the first lens 1 can be between the phase retarder 5 and the polarized reflector 6. That is, the polarized reflector 6, the phase retarder 5 and the light splitting element 4 can be separated by the first lens 1 and the second lens 2. At this time, the light splitting element 4 and the phase retarder 5 are arranged on both sides of the second lens 2, referring to Figure 1 and Figure 5 .

[0107] Of course, the light splitting element 4 and the phase retarder 5 can also be arranged in a stack to form a laminated element. The laminated element can be arranged on any side of the second lens 2, as long as the phase retarder 5 is located between the light splitting element 4 and the polarized reflector 9. This laminated element design can realize the one-time loading of two optical film materials, and can simplify the assembly process.

[0108] In some examples of the present application, referring to Figure 1 , Figure 5 and Figure 9 , the light splitting element 4 is arranged on the surface of the second lens 2 close to the display screen 7, the phase retarder 5 is arranged on the surface of the second lens 2 away from the display screen 7, and the polarized reflector 6 is arranged on any surface of the first lens 1. The surface of the first lens 1 on which the polarized reflector 6 is arranged forms the first reflecting surface, and the surface of the second lens 2 on which the light splitting element 4 is arranged forms the second reflecting surface.

[0109] In consideration of the simplification of the process, the polarized reflector 6 is attached to any surface of the first lens 1, and the light splitting element 4 and the phase retarder 5 can also be arranged on the lens, for example, the two can be arranged on the two surfaces of the second lens 2 respectively. At this time, no additional light transmission support can be introduced in the optical path, and the optical path design can be simplified.

[0110] Referring to Figure 1 , Figure 5 and Figure 9 , the first lens 1 includes a first surface 11 and a second surface 12, the first surface 11 is away from the display screen 7, and the second surface 12 is close to the display screen 7.

[0111] For example, referring to Figure 1 , the polarized reflector 6 can be attached to the first surface 11.

[0112] For another example, referring to Figure 5 and Figure 9 , the polarized reflector 6 can also be attached to the second surface 12.

[0113] Referring to Figure 1 , Figure 5 and Figure 9 , the second lens 2 includes a third surface 21 and a fourth surface 22, the third surface 21 is away from the display screen 7, and the fourth surface 22 is close to the display screen 7.

[0114] For example, referring to Figure 1 , Figure 5 and Figure 9 , the light splitting element 4 can be arranged on the fourth surface 22 of the second lens 2 by means of attachment or plating, and the phase retarder 5 can be arranged on the third surface 21 of the second lens 2 by means of attachment.

[0115] Of course, the light splitting element 4 and the phase retarder 5 can also be stacked to form a stacked element, and the stacked element can be arranged on any surface of the second lens 2.

[0116] It should be noted that the number of lenses in the near-eye optical system can be appropriately increased, and the positions of the films can be appropriately adjusted according to the increased lenses.

[0117] In some examples of the present application, referring to Figure 13 and Figure 17 , the lens group includes a first lens 1, a second lens 2 and a third lens 3 arranged along the optical axis, the first lens 1 is located away from the display screen 7, the third lens 3 is located close to the display screen 7, and the second lens 2 is arranged between the first lens 1 and the third lens 3; the light splitting element 4 is arranged on either side of the third lens 3, the phase retarder 5 is arranged on either side of the second lens 2, and the polarized reflector 6 is arranged on either side of the first lens 1.

[0118] Referring to Figure 13 and Figure 17 , three lenses can also be used in the near-eye optical system provided by the embodiments of the present application. With the increase in the number of lenses, the imaging quality can be improved.

[0119] In some examples of the present application, referring to Figure 13 , the light splitting element 4 is arranged on the surface of the third lens 3 close to the display screen 7, the phase retarder 5 is arranged on the surface of the second lens 2 close to the display screen 7, and the polarized reflector 6 is arranged on the surface of the first lens 1 close to the display screen 7; the surface of the first lens 1 on which the polarized reflector 6 is arranged forms the first reflecting surface, and the surface of the third lens 3 on which the light splitting element 4 is arranged forms the second reflecting surface.

[0120] In addition to the film attachment mode shown in the above examples, other film attachment modes can also be used.

[0121] In some examples of the present application, referring to Figure 17 , the light splitting element 4 is arranged on the surface of the second lens 2 close to the display screen 7, the phase retarder 5 is arranged on the surface of the second lens 2 away from the display screen 7, and the polarized reflector 6 is arranged on the surface of the first lens 1 close to the display screen 7; the surface of the first lens 1 on which the polarized reflector 6 is arranged forms the first reflecting surface, and the surface of the second lens 2 on which the light splitting element 4 is arranged forms the second reflecting surface.

[0122] When three lenses are used in the near-eye optical system, the three lenses can be used to support the light splitting element 4, the phase retarder 5 and the polarized reflector 6 respectively, which facilitates the alignment of the three optical films and the assembly, and does not need to introduce additional light-transmitting supporting members.

[0123] Optionally, a linear polarizing film (POL film) can also be introduced into the near-eye optical system.

[0124] The linear polarizing film can be stacked with the polarizing reflector 6 to form a stacked element, and the polarizing reflector 6 is located between the phase retarder 5 and the linear polarizing film.

[0125] By introducing the linear polarizing film on the side of the polarizing reflector 6 away from the phase retarder 5, a part of the light will be reflected and another part of the light will be transmitted after the light passes through the polarizing reflector 6. At this time, the linear polarizing film can be used to make the light transmitted through the polarizing reflector 6 more pure to enter the human eye 01, avoiding the generation of stray light and other undesirable phenomena. The linear polarizing film and the polarizing reflector 6 form a stacked element, which can simplify the assembly process and place two optical films at one time.

[0126] Of course, an anti-reflection film (AR film) can also be introduced at a suitable position in the optical path, which is a high-transmittance optical film that can reduce reflection and make the light completely transmitted.

[0127] In some examples of the present application, the display screen 7 is configured to emit circularly polarized light or natural light. In the case where the light emitted by the display screen 7 is natural light, the light-emitting surface of the display screen 7 is provided with a composite film material for converting natural light into circularly polarized light, and the composite film material at least includes a phase retarder.

[0128] When the display screen 7 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 emitted into the left optical elements, and the outgoing light is imaged into the human eye 01.

[0129] The phase retarder and the polarizer can be combined into a composite film material and attached to the light-emitting surface of the display screen 7, which can reduce the assembly difficulty and place two optical elements at one time.

[0130] The phase retarder, for example, is a quarter-wave plate, which can convert linearly polarized light into circularly polarized light and convert circularly polarized light into linearly polarized light. The transmission axis direction of the polarizer can be along the horizontal direction, the vertical direction, or any other direction.

[0131] Specifically, the angle between the fast axis or slow axis direction of the phase retarder attached to the light-emitting surface of the display screen 7 and the transmission axis direction of the linear polarizer is 45°.

[0132] The optical performance of the near-eye optical system provided in the examples of the present application is described below through Examples 1 to 5.

[0133] Example 1

[0134] Referring to Figure 1 , Figure 1 The near-eye optical system provided by the embodiment 1 is shown, which comprises a light splitting element 4, a phase retarder 5 and a polarization reflector 6 arranged along the same optical axis, and the phase retarder 5 is located between the light splitting element 4 and the polarization reflector 6;

[0135] The near-eye optical system further comprises a lens group and a display screen 7, wherein the lens group comprises a first lens 1 and a second lens 2, the display screen 7 is arranged on the side of the light splitting element 4 away from the phase retarder 5, and the display screen 7 can emit light for imaging display;

[0136] The light splitting element 4 is arranged on the fourth surface 22 of the second lens 2, the phase retarder 5 is arranged on the third surface 21 of the second lens 2, the polarization reflector 6 is arranged on the second surface 12 of the first lens 1, the surface of the first lens 1 where the polarization reflector 6 is arranged is the first reflecting surface, and the surface of the second lens 2 where the light splitting element 4 is arranged is the second reflecting surface;

[0137] Wherein, the optical power of the first reflecting surface is φ1=-0.022695, the optical power of the second reflecting surface is φ2=0.044671, the optical power of the near-eye optical system is φ=0.0355, the system focal length is F=28.17mm, and the embodiment 1 is adapted to 100° FOV and 46m image plane size;

[0138] (φ1+φ2) / φ is about 0.62; |φ-φ2| / φ is about 0.258;

[0139] tan(FOV / 2)*H / BFL=tan(50°)*23 / 12.61=2.173;

[0140] tan(FOV / 2)*H / R=tan(50°)*23 / 69.26=0.369;

[0141] In addition, the sum of the optical powers of the second lens 2 and the first lens 1 between the light splitting element 4 and the human eye 01 is φ3=0.0096467; based on this, (φ1+φ2) / φ3 is about 2.28, and |φ-φ3| / φ is about 0.728.

[0142] Table 1 shows the optical parameters of the near-eye optical system provided by the embodiment 1.

[0143] Table 1

[0144] Serial number Part Radius Thickness Material (Nd) Diameter 1 Stop Infinity 15 4 2 First surface 11 Infinity 3.9 1.534 48 3 Second surface 12 -131.64 3.62 48 4 Third surface 21 -228.64 4.87 1.5447 51 5 Fourth surface 22 -69.26 12.61 51 6 Display Infinity 46

[0145] The optical performance of the near-eye optical system provided by the embodiment 1 is shown by MTF curve, field curvature and distortion, and axial chromatic aberration respectively.

[0146] The spot diagram refers to a diffused pattern formed by a point emitting many light rays, which are no longer concentrated on the same point on the image plane due to aberration after passing through the optical system, and is mainly used to evaluate the imaging quality of the projection optical system. For the near-eye optical system shown in Figure 1 The spot size value is less than 14 μm under the whole field of view, indicating clear imaging.

[0147] The MTF curve is a modulation transfer function diagram, which represents the imaging clarity of the optical system by the contrast of black and white lines. For the near-eye optical system shown in Figure 1 Referring to Figure 2 It can be seen that the MTF value is higher than 0.05 at 24 lp / mm, which indicates that the near-eye optical system has good resolution.

[0148] For the near-eye display system shown in Figure 1 The field curvature and distortion reflect the difference in the position of the clear imaging surface of different fields of view, as shown in Figure 3 It can be seen that the maximum field curvature is not more than 0.4 mm, and the distortion is not more than 35%.

[0149] For the near-eye display system shown in Figure 1 The chromatic aberration reflects the difference in the imaging position of different wavelengths of light on the image plane in different fields of view. The chromatic aberration of the near-eye optical system is shown in Figure 4 The maximum chromatic aberration of the field of view is less than 220 μm.

[0150] Embodiment 2

[0151] Referring to Figure 5 The near-eye optical system provided by the embodiment 2 has the same optical architecture as the near-eye optical system shown in the embodiment 1, and the number of lenses used is two. The difference lies in that:

[0152] The polarized reflector 6 is arranged on the first surface 11 of the first lens 1, and at this time, the first surface 11 of the first lens 1 on which the polarized reflector 6 is arranged is the first reflection surface;

[0153] The mounting position of the light splitting element 4 is unchanged, and the light splitting element is arranged on the fourth surface 22 of the second lens 2, which forms the second reflection surface;

[0154] The optical power of the first reflection surface is φ1=0, the optical power of the second reflection surface is φ2=0.037432, and the optical power of the near-eye optical system is φ=0.034388;

[0155] wherein the system focal length of the near-eye optical system is F=29.08mm;

[0156] This embodiment 2 is adapted to 80° FOV and 44.9m image plane size;

[0157] (φ1+φ2) / φ is about 1.09; |φ-φ2| / φ is about 0.089;

[0158] tan(FOV / 2)*H / BFL=tan(40°)*22.45 / 7.5=2.512;

[0159] tan(FOV / 2)*H / R=tan(40°)*22.45 / 82.68=0.228;

[0160] In addition, the sum φ3 of the optical power of the second lens 2 between the light splitting element 4 and the human eye 01 and the first lens 1 is 0.0041328, based on which, (φ1+φ2) / φ3 is about 9.06, and |φ-φ3| / φ is about 0.88.

[0161] Table 2 shows the optical parameters of the near-eye optical system provided by embodiment 2.

[0162] Table 2

[0163] Serial number Part Radius Thickness Material (Nd) Diameter 1 Stop Infinity 13 4 2 First surface 11 Infinity 3.5 1.5447 51.8 3 Second surface 12 220 4.16 51.8 4 Third surface 21 Infinity 6.85 1.5447 53.1 5 Fourth surface 22 -82.68 7.5 53.1 6 Display Infinity 44.9

[0164] For the near-eye optical system shown in Figure 5 The spot size value is less than 36μm under the whole field of view, which indicates clear imaging.

[0165] For the near-eye optical system shown in Figure 5 Referring to Figure 6 It can be seen that the MTF value is higher than 0.2 at 7.2lp / mm.

[0166] For the near-eye display system shown in Figure 5 The field curvature and distortion reflect the difference in the position of the clear imaging plane under different fields of view, as shown in Figure 7 It can be seen that the maximum field curvature is not more than 2mm, and the distortion is not more than 25%.

[0167] For the near-eye display system shown in Figure 5 The chromatic aberration reflects the difference in the imaging position of light of different wavelengths in the image plane under different fields of view, and the chromatic aberration of the near-eye optical system is shown in Figure 8 The maximum chromatic aberration under the maximum field of view is less than 150μm.

[0168] Embodiment 3

[0169] Referring to Figure 9 , Figure 9The near-eye optical system provided in this embodiment 3 is shown, and the optical architecture and the film attachment manner shown in embodiment 2 are the same, and the optical parameters of embodiment 3 can be seen from table 3.

[0170] The surface of the first lens 1 provided with the polarized reflector 6 forms the first reflection surface, and the surface of the second lens 2 provided with the light splitting element 4 forms the second reflection surface; the optical power of the first reflection surface is φ1=0, and the optical power of the second reflection surface is φ2=0.057462;

[0171] The system focal length of the near-eye optical system is F=15.73mm;

[0172] The optical power φ of the near-eye optical system is 0.06357;

[0173] This embodiment 3 is adapted to 100° FOV and 26mm image plane size;

[0174] (φ1+φ2) / φ is about 0.9; |φ-φ2| / φ is about 0.096;

[0175] tan(FOV / 2)*H / BFL=tan(50°)*13 / 2.3821=6.5;

[0176] tan(FOV / 2)*H / R=tan(50°)*13 / 53.86=0.288;

[0177] In addition, the sum of the optical powers of the two lenses between the light splitting element 4 and the human eye 01 is φ3=0.0126; based on this, (φ1+φ2) / φ3 is about 4.56, and |φ-φ3| / φ is about 0.8.

[0178] Table 3 shows the optical parameters of the near-eye optical system provided in embodiment 3.

[0179] Table 3

[0180] Serial number Part Radius Thickness Material (Nd) Diameter 1 Stop Infinity 15 4 2 First surface 11 Second surface 12 3.704 1.5447 44.5 3 Third surface 21 -100.191 0.9944 44.5 4 Fourth surface 22 -175.123 4.9104 1.5447 46.34 5 Fifth surface 31 -53.86 2.3821 46.34 6 Sixth surface 32 Display 7 26

[0181] The optical performance of the near-eye optical system provided in this embodiment 3 is shown by MTF curves, field curvature and distortion, and vertical axis chromatic aberration respectively.

[0182] For Infinity The spot size value is less than 33μm under the whole field of view of the shown near-eye optical system.

[0183] For Figure 9 The shown near-eye optical system is shown in Figure 9 It can be seen that the MTF value is higher than 0.2 at 12lp / mm.

[0184] ForFigure 10 The near-eye display system shown by Figure 9 It can be seen that the maximum field curvature is not more than 0.3 mm, and the distortion is not greater than 35%.

[0185] For Figure 11 The near-eye display system shown, the chromatic aberration of the near-eye optical system is as shown in Figure 9 The maximum field chromatic aberration is less than 310 mm.

[0186] Embodiment 4

[0187] Referring to Figure 12 Embodiment 4 and Embodiment 1 show the near-eye optical system, the difference is that:

[0188] The lens group includes three lenses, respectively, the first lens 1, the second lens 2 and the third lens 3, and the second lens 2 is located between the first lens 1 and the third lens 3;

[0189] The light splitting element 4 is arranged on the sixth surface 32 of the third lens 3, the phase retarder 5 is arranged on the fourth surface 22 of the second lens 2, and the polarized reflector 6 is arranged on the second surface 12 of the first lens 1;

[0190] The surface of the first lens 1 where the polarized reflector 6 is arranged is the first reflecting surface, and the surface of the third lens 3 where the light splitting element 4 is arranged is the second reflecting surface; wherein the optical power of the first reflecting surface is φ1=0, the optical power of the second reflecting surface is φ2=0.052834, and the optical power of the near-eye optical system is φ=0.034388;

[0191] The system focal length of the near-eye optical system is F=16.4735mm;

[0192] Embodiment 4 is adapted to 100° FOV and 26mm image size;

[0193] (φ1+φ2) / φ is about 0.87; |φ-φ2| / φ is about 0.13;

[0194] tan(FOV / 2)*H / BFL=tan(50°)*13 / 1.497=10.349;

[0195] tan(FOV / 2)*H / R=tan(50°)*13 / 58.577=0.264;

[0196] In addition, the sum of the optical powers of the two lenses between the light splitting element 4 and the human eye 01 is φ3=0.0173368; based on this, (φ1+φ2) / φ3 is about 3.05, and |φ-φ3| / φ is about 0.71.

[0197] Table 4 shows the optical parameters of the near-eye optical system provided by Example 4.

[0198] Table 4

[0199]

[0200]

[0201] For the near-eye optical system shown in Figure 13 The spot size value is less than 50 pm throughout the field of view, which indicates that the imaging is clear.

[0202] For the near-eye optical system shown in Figure 13 Referring to Figure 13 It can be seen that the MTF value is higher than 0.1 at 9.6 lp / mm

[0203] For the near-eye optical system shown in Figure 14 It can be seen that the maximum field curvature is not more than 0.8 mm, and the distortion is not greater than 40%. Figure 13

[0204] For the near-eye optical system shown in Figure 15 The chromatic aberration of the near-eye optical system is shown in Figure 13 The maximum field chromatic aberration is less than 230 pm.

[0205] Example 5

[0206] Referring to Figure 16 The near-eye optical system provided by this embodiment 5 is different from the near-eye optical system shown in Example 4 in that:

[0207] The light splitting element 4 is arranged on the surface (i.e. the fourth surface 22) of the second lens 2 close to the display screen 7, the phase retarder 5 is arranged on the surface (i.e. the third surface 21) of the second lens 2 away from the display screen 7, and the polarized reflector 6 is arranged on the surface (i.e. the second surface 12) of the first lens 1 close to the display screen 7;

[0208] The surface of the first lens 1 on which the polarized reflector 6 is arranged is the first reflecting surface, and the surface of the second lens 2 on which the light splitting element 4 is arranged is the second reflecting surface; the optical power of the first reflecting surface is φ1 = -0.013854, the optical power of the second reflecting surface is φ2 = 0.075902, and the optical power of the near-eye optical system is φ = 0.06909;

[0209] The system focal length of the near-eye optical system is F = 14.4737 mm;

[0210] ​The embodiment 5 is adapted to 78° FOV and 18.5mm image surface size;

[0211] (φ1+φ2) / φ is about 0.898; |φ-φ2| / φ is about 0.0986;

[0212] tan(FOV / 2)*H / BFL=tan(39°)*9.25 / 6.263=1.196;

[0213] tan(FOV / 2)*H / R=tan(39°)*9.25 / 40.77=0.184;

[0214] In addition, the sum of the optical powers of the two lenses between the light splitting element 4 and the human eye 01 is φ3, which is 0.02111; based on this, (φ1+φ2) / φ3 is about 2.94, and |φ-φ3| / φ is about 0.69.

[0215] Table 5 shows the optical parameters of the near-eye optical system provided by the embodiment 5.

[0216] Table 5

[0217] Figure 17 Serial number Part Radius Thickness Material (Nd) 1 Diameter Stop 14 4 2 Infinity 115.78 3.72 1.534 30 3 First surface 11 -114.36 0.51 30 4 Second surface 12 -157.26 5.872 1.5447 32.9 5 Third surface 21 -40.77 0.298 32.9 6 Fourth surface 22 -106.74 4.468 1.5447 25.6 7 Fifth surface 31 -71.34 1.497 8 Sixth surface 32 Display 7 18.5

[0218] For the near-eye optical system shown in Infinity The spot size value is less than 16μm under the whole field of view, which indicates that the imaging is clear.

[0219] For the near-eye optical system shown in Figure 17 Referring to Figure 17 It can be seen that the MTF value is higher than 0.1 at 24lp / mm.

[0220] For the near-eye display system shown in Figure 18 It can be seen from Figure 17 that the maximum field curvature is not more than 0.15mm, and the distortion is not greater than 20%.

[0221] For the near-eye display system shown in Figure 19 The chromatic aberration of the near-eye optical system is shown in Figure 17 Figure 20 The maximum field chromatic aberration is less than 150μm.

[0222] According to another embodiment of the present application, a head-mounted display device is provided.

[0223] The head-mounted display device includes a housing and a near-eye optical system as described above.

[0224] The head-mounted display device includes a VR smart glasses or a VR smart helmet, etc., which is not limited in the embodiments of the present application.

[0225] The specific implementation of the head-mounted display device of the embodiments of the present application can refer to the above-mentioned various embodiments of the near-eye optical system, and therefore has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be described one by one here.

[0226] In the above embodiments, the focus is on the differences between various embodiments, and the different optimization features between various embodiments can be combined to form a better embodiment as long as they are not contradictory. Considering the brevity of the writing, it will not be described here.

[0227] Although some specific embodiments of the present application have been described in detail through examples, those skilled in the art should understand that the above examples are only for illustration, not for limiting the scope of the present application. Those skilled in the art should understand that the above embodiments can be modified without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims

1. A near-eye optical system, characterized by, The optical system comprises a light splitting element (4), a phase retarder (5) and a polarization reflector (6) arranged along the same optical axis, and the phase retarder (5) is located between the light splitting element (4) and the polarization reflector (6); The near-eye optical system further comprises a lens group, at least one lens in the lens group is located in the folded optical path formed by the light splitting element (4), the phase retarder (5) and the polarization reflector (6), the polarization reflector (6) forms a first reflecting surface, and the light splitting element (4) forms a second reflecting surface; Wherein, the optical power of the first reflecting surface is φ1, the optical power of the second reflecting surface is φ2, the optical power of the near-eye optical system is φ, and the near-eye optical system satisfies the following relationship: 0.6< (φ1+φ2) / φ<1.1; The near-eye optical system satisfies: 0.08<|φ-φ2| / φ<0.

4.

2. The near-eye optical system of claim 1, wherein, The sum of the optical powers of all lenses between the light splitting element (4) and the human eye (01) is φ3, and the near-eye optical system satisfies: 2.2< (φ1+φ2) / φ3<9.

1.

3. The near-eye optical system of claim 2, wherein, The optical power of the near-eye optical system is φ, and the near-eye optical system satisfies: 0.65<|φ-φ3| / φ<0.

9.

4. The near-eye optical system of any one of claims 1-3, wherein, The near-eye optical system further comprises a display screen (7), and the display screen (7) is arranged on the side of the light splitting element (4) away from the phase retarder (5); The field of view of the near-eye optical system is FOV, the image height of the near-eye optical system is H, the axial distance from the light splitting element (4) to the light emitting surface of the display screen (7) is BFL, and the near-eye optical system satisfies: 1.1<tan (FOV / 2) *H / BFL<10.

5.

5. The near-eye optical system of claim 4, wherein, The radius of curvature of the light splitting element (4) is R, and the near-eye optical system satisfies: 0.18<tan (FOV / 2) *H / R<0.

4.

6. The near-eye optical system of claim 4, wherein, The lens group comprises a first lens (1) and a second lens (2) arranged along the optical axis, the first lens (1) is located away from the display screen (7), and the second lens (2) is located close to the display screen (7); The light splitting element (4) and the phase retarder (5) are arranged on at least one side of the second lens (2), and the polarization reflector (6) is arranged on any side of the first lens (1).

7. The near-eye optical system of claim 6, wherein, The light splitting element (4) is arranged on the surface of the second lens (2) close to the display screen (7), the phase retarder (5) is arranged on the surface of the second lens (2) away from the display screen (7), and the polarization reflector (6) is arranged on any surface of the first lens (1); Wherein, the surface of the first lens (1) on which the polarization reflector (6) is arranged forms the first reflecting surface, and the surface of the second lens (2) on which the light splitting element (4) is arranged forms the second reflecting surface.

8. The near-eye optical system of claim 4, wherein, The lens group comprises a first lens (1), a second lens (2) and a third lens (3) arranged along the optical axis, the first lens (1) is located on the side away from the display screen (7), the third lens (3) is located on the side close to the display screen (7), and the second lens (2) is arranged between the first lens (1) and the third lens (3); The light splitting element (4) is arranged on either side of the third lens (3), the phase retarder (5) is arranged on either side of the second lens (2), and the polarization reflector (6) is arranged on either side of the first lens (1).

9. The near-eye optical system of claim 8, wherein, The light splitting element (4) is arranged on the surface of the third lens (3) close to the display screen (7), the phase retarder (5) is arranged on the surface of the second lens (2) close to the display screen (7), and the polarization reflector (6) is arranged on the surface of the first lens (1) close to the display screen (7). The surface of the first lens (1) on which the polarization reflector (6) is arranged forms the first reflection surface, and the surface of the third lens (3) on which the light splitting element (4) is arranged forms the second reflection surface.

10. The near-eye optical system of claim 8, wherein, The light splitting element (4) is arranged on the surface of the second lens (2) close to the display screen (7), the phase retarder (5) is arranged on the surface of the second lens (2) away from the display screen (7), and the polarization reflector (6) is arranged on the surface of the first lens (1) close to the display screen (7). The surface of the first lens (1) on which the polarization reflector (6) is arranged forms the first reflection surface, and the surface of the second lens (2) on which the light splitting element (4) is arranged forms the second reflection surface.

11. The near-eye optical system of claim 4, wherein, The display screen (7) is configured to emit circularly polarized light or natural light; In the case that the light emitted by the display screen (7) is natural light, the light emitting surface of the display screen (7) is provided with a composite film material for converting natural light into circularly polarized light, and the composite film material at least comprises a phase retarder.

12. A head-mounted display device, comprising: Comprise: a housing; and The near-eye optical system of any one of claims 1-11. ​

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