Optical system and wearable display device

Abstract

The utility model provides an optical system and wearable display equipment. The optical system comprises a first lens, a second lens and a third lens which are arranged in sequence, the surfaces of the first sides of the first lens, the second lens and the third lens are concave surfaces, and the surfaces of the second sides of the first lens, the second lens and the third lens are convex surfaces; the focal lengths of the first lens and the third lens are positive focal lengths, and the focal length of the second lens is negative focal length; wherein the first side is the side, facing the human eyes, of the optical system. According to the optical system provided by the invention, the surface of the first side of each lens is set to be the concave surface, the second side of each lens is set to be the convex surface, the focal lengths of the first lens and the third lens are positive focal lengths, and the focal length of the second lens is negative focal length, so that a space formed between the concave surface and human eyes can be formed under the condition that enough optical performance is ensured; therefore, the wearing comfort of the user is improved.

Description

Technical Field

[0001] The present application relates to the field of optical systems, and in particular to an optical system and a wearable display device. Background Art

[0002] With the advancement of technology, wearable devices such as VR (Virtual Reality) and MR (Mixed Reality) are receiving more and more attention. As a result, the demand for the wearing experience of the devices is gradually increasing. Due to the increasing requirements for thinness and lightness of existing VR and MR devices, and in order to ensure that the optical system has sufficient optical performance (such as ensuring the size of the field of view FOV (field of view)), the distance between the optical system and the entrance pupil position in the device is constantly compressed (usually the maximum distance from the human eye to the optical system (i.e. Eye Relief) is less than 15mm), resulting in many devices. When worn, the human eye easily interferes with the optical system, and the human eye can feel the heat emitted by the optical system, which reduces the wearing comfort. Summary of the invention

[0003] In view of this, the present application provides an optical system and a wearable display device, which at least partially solve the problems existing in the prior art.

[0004] In one aspect of the present application, an optical system is provided, comprising:

[0005] The first lens, the second lens and the third lens are arranged in sequence.

[0006] The surfaces of the first sides of the first lens, the second lens and the third lens are all concave surfaces, and the surfaces of the second sides are all convex surfaces;

[0007] The focal lengths of the first lens and the third lens are both positive focal lengths, and the focal length of the second lens is negative focal length;

[0008] The first side is the side of the optical system facing the human eye.

[0009] In an exemplary embodiment of the present application, the first lens satisfies the following conditions:

[0010] 5.5<F1 / F<11.5;

[0011] Wherein, F1 is the focal length of the first lens, and F is the total focal length of the optical system.

[0012] In an exemplary embodiment of the present application, the second lens satisfies the following conditions:

[0013] -38<F2 / F<-28;

[0014] Wherein, F2 is the focal length of the second lens, and F is the total focal length of the optical system.

[0015] In an exemplary embodiment of the present application, the third lens satisfies the following conditions:

[0016] 5<F3 / F<13;

[0017] Wherein, F3 is the focal length of the third lens, and F is the total focal length of the optical system.

[0018] In an exemplary embodiment of the present application, the first lens and the second lens satisfy the following conditions:

[0019] 0.7<R 1，2 / R 2，1 <1.0;

[0020] Among them, R 1，2 is the radius of curvature of the surface of the second side of the first lens; R 2，2 is the radius of curvature of the surface of the first side of the second lens.

[0021] In an exemplary embodiment of the present application, the second lens and the third lens satisfy the following conditions:

[0022] 0.7<R 2，2 / R 3，1 <1.2;

[0023] Among them, R 2，2 is the radius of curvature of the surface of the second side of the second lens; R 3，1 is the radius of curvature of the surface of the first side of the third lens.

[0024] In an exemplary embodiment of the present application, the optical system further comprises a display screen; a display surface of the display screen is opposite to the second side of the third lens;

[0025] The display surface meets the following conditions:

[0026] L / Y<0.45;

[0027] Wherein, L is the shortest distance from the display surface to the surface of the first side of the first lens; Y is the length of the diagonal of the display surface.

[0028] In an exemplary embodiment of the present application, the optical system further includes:

[0029] A reflective polarizing film and a 1 / 4 phase delay film are disposed between the first lens and the second lens, wherein the reflective polarizing film is close to the first lens;

[0030] A semi-transparent and semi-reflective film is arranged on the second side surface of the third lens.

[0031] In an exemplary embodiment of the present application, the display screen is a Micro Oled display screen or a Fast LCD display screen;

[0032] In the case that the display screen is a Micro Oled display screen, a linear polarizer and a 1 / 4 phase retarder are stacked on the display surface, and the linear polarizer is located between the display surface and the 1 / 4 phase retarder.

[0033] In another aspect of the present application, a wearable display device is provided, wherein the optical system described in any one of the above items is arranged in the wearable display device.

[0034] Beneficial effects:

[0035] The optical system provided by the present application sets each lens to have a concave surface on the first side (the side facing the human eye) and a convex surface on the second side, and the focal lengths of the first lens and the third lens are both positive focal lengths, and the focal length of the second lens is negative focal length, which can achieve the space formed between the concave surface and the human eye while ensuring sufficient optical performance, so as to improve the user's comfort when wearing. According to experimental measurements, the above structural design can make the eye relief greater than or equal to 17mm when the field of view FOV of the wearable display device equipped with the optical system is greater than or equal to 110°. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0037] Figure 1 A schematic diagram of the structure of an optical system provided in an embodiment of the present application;

[0038] Figure 2 A schematic diagram of a first light propagation path in an optical system provided in an embodiment of the present application;

[0039] Figure 3 A schematic diagram of a second light propagation path in an optical system provided in an embodiment of the present application;

[0040] Figure 4 A diagram showing parameter data of an optical system provided in an embodiment of the present application;

[0041] Figure 5A schematic diagram of the MTF curve of the optical system provided in an embodiment of the present application.

[0042] The first lens 1; the second lens 2; the third lens 3; the display screen 4; the reflective polarizing film 5; the 1 / 4 phase delay film 6; the semi-transparent and semi-reflective film 7; the 1 / 4 phase delay plate 8; and the linear polarizing plate 9. DETAILED DESCRIPTION

[0043] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0044] It should be noted that the following embodiments and features in the embodiments may be combined with each other in the absence of conflict; and, based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without making any creative work are within the scope of protection of the present disclosure.

[0045] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein may be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present disclosure, it should be understood by those skilled in the art that an aspect described herein may be implemented independently of any other aspect, and two or more of these aspects may be combined in various ways. For example, any number of aspects described herein may be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein may be used to implement this device and / or practice this method.

[0046] Please refer to Figure 1 As shown, in one aspect of the present application, an optical system is provided, comprising:

[0047] A first lens 1, a second lens 2 and a third lens 3 arranged in sequence;

[0048] The surfaces of the first sides of the first lens 1, the second lens 2 and the third lens 3 are all concave surfaces, and the surfaces of the second sides are all convex surfaces;

[0049] The focal lengths of the first lens 1 and the third lens 3 are both positive focal lengths, and the focal length of the second lens 2 is negative focal length;

[0050] The first side is the side of the optical system facing the human eye (which can be understood as the side facing the aperture).

[0051] Specifically, the first lens 1 , the second lens 2 and the third lens 3 can all be made of glass material or resin material, which can be selected according to actual needs.

[0052] In this embodiment, the above-mentioned concave surface and convex surface can be understood as follows: Figure 1 As shown, when the surface is the first side (i.e. Figure 1 If the line on its cross section shows a middle to second side (i.e. Figure 1 When the surface is the surface of the second side, if the lines on the cross section show that the middle is convex toward the second side, it is a convex surface. For ease of understanding, taking a football as an example, the same surface area of ​​a football has a concave inner surface and a convex outer surface.

[0053] In this embodiment, the focal lengths of the first lens 1 and the third lens 3 are both positive focal lengths, which can be understood as the first lens 1 and the third lens 3 are both convex lenses, that is, the thickness of the central region of the lens is greater than the thickness of the peripheral edge region. The focal length of the second lens 2 is a negative focal length, which can be understood as the second lens 2 is a concave lens, that is, the thickness of the central region is less than the thickness of the peripheral edge region.

[0054] It is worth noting that, in this embodiment, by adjusting the curvature radius of the surface of each lens, even when the surface of the first side of each lens is concave and the surface of the second side is convex, it is possible to ensure that the focal lengths of the first lens 1 and the third lens 3 are both positive focal lengths, and the focal length of the second lens 2 is negative focal length. Further, in this embodiment, the total focal length of the optical system is a positive focal length.

[0055] The optical system provided by the present application sets each lens to have a concave surface on the first side (the side facing the human eye) and a convex surface on the second side, and the focal lengths of the first lens 1 and the third lens 3 are both positive focal lengths, and the focal length of the second lens 2 is negative focal length, which can achieve the space formed between the concave surface and the human eye while ensuring sufficient optical performance, so as to improve the user's comfort when wearing. According to experimental measurements, through the above structural design, when the field of view angle FOV of the wearable display device provided with the optical system is greater than or equal to 110°, the eye relief can be greater than or equal to 17mm.

[0056] In an exemplary embodiment of the present application, the first lens 1 satisfies the following conditions:

[0057] 5.5<F1 / F<11.5;

[0058] Wherein, F1 is the focal length of the first lens 1, and F is the total focal length of the optical system.

[0059] In this embodiment, by controlling the proportional relationship between the focal length of the first lens 1 and the total focal length of the optical system, the surface of the first side of the first lens 1 can be more concave toward the second side, which is beneficial to increase EyeRelief.

[0060] In an exemplary embodiment of the present application, the second lens 2 satisfies the following conditions:

[0061] -38<F2 / F<-28;

[0062] Wherein, F2 is the focal length of the second lens 2, and F is the total focal length of the optical system.

[0063] In this embodiment, by controlling the proportional relationship between the focal length of the second lens 2 and the total focal length of the optical system, the surface of the first side of the second lens 2 can be more concave toward the second side, and then the surface of the second side of the first lens 1 can be more convex toward the second side, so that when it is necessary to control the overall focal length of the first lens 1, the surface of the first side has a larger selection space, which is conducive to increasing the Eye Relief.

[0064] In an exemplary embodiment of the present application, the third lens 3 satisfies the following conditions:

[0065] 5<F3 / F<13;

[0066] Wherein, F3 is the focal length of the third lens 3, and F is the total focal length of the optical system.

[0067] In this embodiment, by controlling the proportional relationship between the focal length of the second lens 2 and the total focal length of the optical system, the surface of the first side of the second lens 2 can be more concave toward the second side, and then the surface of the second side of the first lens 1 and the second lens 2 as a whole can be more convex toward the second side, so that when it is necessary to control the overall focal length of the first lens 1 and the second lens 2, the surface of the first side has a larger selection space, which is conducive to increasing the Eye Relief.

[0068] In some preferred embodiments, the first lens 1, the second lens 2 and the third lens 3 satisfy at least two of the following conditions simultaneously:

[0069] 5.5<F1 / F<11.5; -38<F2 / F<-28; 5<F3 / F<13.

[0070] According to tests and measurements, if the first lens 1, the second lens 2 and the third lens 3 meet the above three conditions at the same time, the Eye Relief can be increased to 16 mm to 17 mm while the overall length of the optical system is short, thereby further improving the wearing comfort of the user.

[0071] In an exemplary embodiment of the present application, the first lens 1 and the second lens 2 satisfy the following conditions:

[0072] 0.7<R1，2 / R 2，1 <1.0;

[0073] Among them, R 1，2 is the radius of curvature of the surface of the second side of the first lens 1; R 2，2 is the radius of curvature of the surface of the first side of the second lens 2 .

[0074] In this embodiment, the surface of the second side of the first lens 1 and the surface of the first side of the second lens 2 are arranged opposite to each other, and the radius of curvature between them satisfies 0.7<R 1，2 / R 2，1 <1.0, so that the distance between the central areas of the first lens 1 and the second lens 2 is small, making the overall structure of the optical system compact, which is beneficial to improving the Eye Relief and reducing the overall length of the optical system while ensuring the FOV.

[0075] In an exemplary embodiment of the present application, the second lens 2 and the third lens 3 satisfy the following conditions:

[0076] 0.7<R 2，2 / R 3，1 <1.2;

[0077] Among them, R 2，2 is the radius of curvature of the surface of the second side of the second lens 2; R 3，1 is the curvature radius of the surface of the first side of the third lens 3.

[0078] In this embodiment, the surface of the second side of the second lens 2 and the surface of the first side of the third lens 3 are arranged opposite to each other, and the curvature radius between them satisfies 0.7<R 1，2 / R 2，1 <1.0, so that the distance between the central areas of the second lens 2 and the third lens 3 is small, making the overall structure of the optical system compact, which is beneficial to improving the Eye Relief and reducing the overall length of the optical system while ensuring the FOV.

[0079] In some preferred embodiments, the optical system satisfies the following two conditions simultaneously:

[0080] 0.7<R 1，2 / R 2，1 <1.0;0.7<R 2，2 / R 3，1 <1.2.

[0081] In this way, the overall structure of the optical system can be kept as compact as possible, further improving the Eye Relief.

[0082] In an exemplary embodiment of the present application, the optical system further includes:

[0083] A reflective polarizing film 5 and a 1 / 4 phase delay film 6 are disposed between the first lens 1 and the second lens 2, wherein the reflective polarizing film 5 is close to the first lens 1;

[0084] A semi-transparent and semi-reflective film 7 is arranged on the second side surface of the third lens 3 .

[0085] In this embodiment, by setting a reflective polarizing film 5 and a 1 / 4 phase delay film 6 between the first lens 1 and the second lens 2, and setting a semi-transparent semi-reflective film 7 on the second side surface of the third lens 3, the light incident from the second side of the optical system can be emitted from the first side of the optical system after multiple refractions and reflections (the path of light propagation will be described in detail later). As a result, the propagation path of the light becomes longer, and the angle changes during the propagation process. In this way, on the one hand, it is beneficial to shorten the overall length of the optical system, and on the other hand, it is beneficial to increase the FOV.

[0086] In an exemplary embodiment of the present application, the optical system further comprises a display screen 4; a display surface of the display screen 4 is opposite to the second side of the third lens 3;

[0087] The display surface meets the following conditions:

[0088] L / Y<0.45;

[0089] Wherein, L is the shortest distance from the display surface to the surface of the first side of the first lens 1; Y is the length of the diagonal of the display surface.

[0090] In this embodiment, the display surface meets the above conditions, so that the total length of the optical system can be reduced, the size and weight of the optical system can be reduced, and the optical system structure is more compact and occupies less space.

[0091] In a preferred embodiment, the optical system comprises:

[0092] A first lens 1 , a second lens 2 , and a third lens 3 are arranged in sequence, and a display screen 4 is arranged on a second side of the third lens 3 .

[0093] The surfaces of the first side of the first lens 1 , the second lens 2 and the third lens 3 are all concave surfaces, and the surfaces of the second side of the first lens 1 , the second lens 2 and the third lens 3 are all convex surfaces.

[0094] The focal lengths of the first lens 1 and the third lens 3 are both positive focal lengths, and the focal length of the second lens 2 is negative focal length.

[0095] The display surface of the display screen 4 is opposite to the second side of the third lens 3 .

[0096] The first side is the side of the optical system facing the human eye.

[0097] The optical system further includes a reflective polarizing film 5 and a 1 / 4 phase delay film 6 disposed between the first lens 1 and the second lens 2, and a semi-transparent and semi-reflective film 7 disposed on the second side surface of the third lens 3;

[0098] The reflective polarizing film 5 is close to the first lens 1 .

[0099] And the optical system meets the following conditions at the same time:

[0100] 5.5<F1 / F<11.5;

[0101] -38<F2 / F<-28;

[0102] 5<F3 / F<13;

[0103] 0.7<R 1，2 / R 2，1 <1.0;

[0104] 0.7<R 2，2 / R 3，1 <1.2;

[0105] L / Y<0.45.

[0106] Please refer to Figure 2 As shown, in this embodiment, the propagation path of the light is as follows:

[0107] 1. The right circularly polarized light RCP (Right Cricular Polarized) emitted by the display screen 4 passes through the BS beam splitter (i.e., the semi-transparent and semi-reflective film 7), and then enters the third lens 3 from the surface of the second side of the third lens 3, and the polarization state does not change.

[0108] 2. The right-handed circularly polarized light RCP emitted from the surface of the first side of the third lens 3 is incident on the surface of the second side of the second lens 2 .

[0109] 3. The right-handed circularly polarized light RCP emitted from the surface of the first side of the second lens 2 is converted into P linearly polarized light after passing through the QWP1 / 4 phase delay film 6.

[0110] 4. The P linear polarized light reaches the reflective polarizing film 5 and is reflected. The reflective polarizing film 5 reflects the P linear polarized light.

[0111] 5. The P linearly polarized light passes through the 1 / 4 phase retardation film 6 for the second time, and is transformed back into the right-handed circularly polarized light RCP, and is incident on the second lens 2 from the surface of the first side of the second lens 2.

[0112] 6. The right-handed circularly polarized light RCP emitted from the surface on the second side of the second lens 2 enters the third lens 3 from the surface on the first side of the third lens 3 .

[0113] 7. The right circularly polarized light RCP emitted from the surface of the second side of the third lens 3 is reflected by the BS beam splitter (ie, the semi-transparent and semi-reflective film 7) and becomes left circularly polarized light LCP (Left Cricular Polarized).

[0114] 8. After the left-handed circularly polarized light LCP passes through the third lens 3 and the second lens 2 in sequence (the specific path can be referred to above and will not be repeated here), it passes through the 1 / 4 phase delay film 6 for the third time and becomes S linearly polarized light.

[0115] 9. The S-linear polarized light passes through the reflective polarizing film 5 and the first lens 1 and enters the human eye.

[0116] Illustrative, Figure 2 The transition from position A to position B is the above 1-4 process, the transition from position B to position C is the 4-7 process, and the transition from position C to position D and continuing the propagation is the 7-9 process.

[0117] Furthermore, Figure 3 A schematic diagram of the overall propagation path of light in more directions is provided to provide a more comprehensive understanding of the light propagation of the optical system provided in this embodiment.

[0118] In this embodiment, the light can smoothly enter the human eye after propagating along the above path. And through experimental measurement, the optical system in this embodiment can achieve a FOV of more than 110°, a PPD (Pixels Per Degree) of more than 35, and an Eye relief of more than 17.

[0119] In an exemplary embodiment of the present application, the plastic material used for the first lens 1 and the third lens 3 is APEL5514, and the high-refractive index plastic material used for the second lens 2 is EP7000. The combination of high and low refractive index materials makes it easier to calibrate dispersion and chromatic aberration.

[0120] In an exemplary embodiment of the present application, the display screen 4 is a Micro Oled display screen 4 or a Fast LCD display screen 4;

[0121] In the case where the display screen 4 is a Micro Oled display screen 4 , a linear polarizer 9 and a 1 / 4 phase retarder 8 are stacked on the display surface, and the linear polarizer 9 is located between the display surface and the 1 / 4 phase retarder 8 .

[0122] In specific implementation, the display screen 4 can be determined to be a Micro Oled display screen 4 or a Fast LCD display screen 4 according to actual needs. And because the Fast LCD display screen 4 emits circularly polarized light, it is necessary to set a linear polarizer 9 and a 1 / 4 phase delay plate 8 on its display surface so that the light emitted from the 1 / 4 phase delay plate 8 is right-handed polarized light.

[0123] In some exemplary embodiments of the present application, the size of the display surface is 24.2 mm*22.38 mm, and its diagonal length is 32.96 mm. The overall structure of the optical system designed according to the modified size and meeting L / Y<0.45 can be made more compact, so as to improve the lightness and thinness of the wearable display device in which it is located.

[0124] In some preferred embodiments, the invention comprises:

[0125] A first lens 1 , a second lens 2 , and a third lens 3 are arranged in sequence, and a display screen 4 is arranged on a second side of the third lens 3 .

[0126] The surfaces of the first side of the first lens 1 , the second lens 2 and the third lens 3 are all concave surfaces, and the surfaces of the second side of the first lens 1 , the second lens 2 and the third lens 3 are all convex surfaces.

[0127] The focal lengths of the first lens 1 and the third lens 3 are both positive focal lengths, and the focal length of the second lens 2 is negative focal length.

[0128] The display surface of the display screen 4 is opposite to the second side of the third lens 3 .

[0129] The first side is the side of the optical system facing the human eye, the display screen 4 is a Micro Oled display screen 4, the display surface of the display screen 4 is 24.2 mm*22.38 mm in size, and the diagonal length is 32.96 mm.

[0130] The optical system further includes a reflective polarizing film 5 and a 1 / 4 phase delay film 6 disposed between the first lens 1 and the second lens 2, and a semi-transparent and semi-reflective film 7 disposed on the second side surface of the third lens 3;

[0131] The reflective polarizing film 5 is close to the first lens 1 .

[0132] And the optical system meets the following conditions at the same time:

[0133] 5.5<F1 / F<11.5;

[0134] -38<F2 / F<-28;

[0135] 5<F3 / F<13;

[0136] 0.7<R1，2 / R 2，1 <1.0;

[0137] 0.7<R 2，2 / R 3，1 <1.2;

[0138] L / Y<0.45.

[0139] Furthermore, the parameters of each optical element in the optical system meet Figure 4 The data shown in .

[0140] Note: Figure 4 In the table, Surf1 represents the surface of the first side of the corresponding optical element, and Surf2 represents the surface of the second side of the corresponding optical element. The surfaces from bottom to top in the table are the propagation paths of the light.

[0141] The MTF curve of the optical system provided in this embodiment is as follows: Figure 5 As shown, from Figure 5 It can be determined from the contents shown in that the optical system provided by this embodiment has excellent optical resolution.

[0142] Furthermore, through experimental measurements, the PPD of the optical system in this embodiment can be increased to 37, the FOV can be increased to 110°, and the Eyelief can be increased to 17 mm.

[0143] Thus, the optical system provided by this embodiment (whose optical performance parameters are as follows: PPD < 23; FOV range: 90° to 105°; Eye Relief ≤ 15 mm) for some scenes has the following beneficial effects:

[0144] 1. The angular resolution PPD is greatly improved, and the screen effect is basically eliminated;

[0145] 2. The field of view angle FOV reaches 110°, which further reduces the field of view occlusion of the human eye and provides a stronger sense of immersion when worn;

[0146] 3. Eye relief can be increased to 17mm, further expanding the distance from the human eye to the center of the first lens 1, so that it can adapt to more people and more face shapes. The wearing experience is not easy to feel the radiant heat from the screen, and the wearing comfort is also improved.

[0147] In another aspect of the present application, a wearable display device is provided, wherein the optical system described in any one of the above items is arranged in the wearable display device.

[0148] Specifically, the wearable display device may be a VR device or an MR device.

[0149] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. An optical system, characterized in that: include: A first lens, a second lens, and a third lens arranged in sequence; The surfaces of the first sides of the first lens, the second lens and the third lens are all concave, and the surfaces of the second sides are all convex; The focal lengths of the first lens and the third lens are both positive, and the focal length of the second lens is negative; Wherein, the first side is the side of the optical system facing the human eye; The first lens meets the following conditions: 5.5<F1 / F<11.5; Wherein, F1 is the focal length of the first lens, and F is the total focal length of the optical system.

2. The optical system according to claim 1, wherein: The second lens meets the following conditions: -38<F2 / F<-28; Wherein, F2 is the focal length of the second lens, and F is the total focal length of the optical system.

3. The optical system according to claim 1, wherein: The third lens meets the following conditions: 5<F3 / F<13; Wherein, F3 is the focal length of the third lens, and F is the total focal length of the optical system.

4. The optical system according to any one of claims 1 to 3, characterized in that: The following conditions are met between the first lens and the second lens: 0.7<R 1，2 / R 2，1 <1.0; Among them, R 1，2 is the radius of curvature of the surface of the second side of the first lens; R 2，2 is the radius of curvature of the surface of the first side of the second lens.

5. The optical system according to any one of claims 1 to 3, characterized in that: The following conditions are met between the second lens and the third lens: 0.7<R 2，2 / R 3，1 <1.2; Among them, R 2，2 is the radius of curvature of the surface of the second side of the second lens; R 3，1 is the curvature radius of the surface of the first side of the third lens.

6. The optical system according to any one of claims 1 to 3, characterized in that: Also includes a display screen; the display surface of the display screen is opposite to the second side of the third lens; The display surface meets the following conditions: L / Y<0.45; Wherein, L is the shortest distance from the display surface to the surface of the first side of the first lens; Y is the length of the diagonal of the display surface.

7. The optical system according to any one of claims 1 to 3, characterized in that: Also includes: a reflective polarizing film and a 1 / 4 phase delay film disposed between the first lens and the second lens, wherein the reflective polarizing film is close to the first lens; A semi-transparent and semi-reflective film is provided on the second side surface of the third lens.

8. The optical system according to claim 6, wherein: The display screen is a Micro Oled display screen or a Fast LCD display screen; In the case that the display screen is a Micro Oled display screen, a linear polarizer and a 1 / 4 phase retarder are stacked on the display surface, and the linear polarizer is located between the display surface and the 1 / 4 phase retarder.

9. A wearable display device, characterized in that: The wearable display device is provided with an optical system as described in any one of claims 1-8.

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