Optical modules and head mounted display devices

Abstract

The embodiment of the present application discloses an optical module and a head-mounted display device; the optical module includes a first lens and a flat plate element; the optical module also includes a beam splitter, a first phase retarder and a polarized reflective element, the first phase retarder is located between the beam splitter and the polarized reflective element; the beam splitter and the first phase retarder are located on either side of the first lens; the polarized reflective element is provided on any surface of the flat plate element, and the flat plate element is configured to be able to flip and swap the positions of its two surfaces relative to the first lens, so that the optical module can be switched between a first state and a second state; when the optical module is in the first state, the surface of the flat plate element provided with the polarized reflective element is away from the first lens; when the optical module is switched to the second state, the surface of the flat plate element provided with the polarized reflective element faces the first lens. The optical solution of the present application can be used by people wearing glasses or people without myopia, and can also be used by people with myopia without wearing glasses.

Description

Technical Field

[0001] The present application belongs to the field of optical display technology. Specifically, the present application relates to an optical module and a head-mounted display device. Background Art

[0002] The main working principle of Virtual Reality (VR) equipment is that the image displayed on the monitor is transmitted and amplified through a series of optical devices, and then the image is received by the human eye, and what the human eye observes is an enlarged virtual image.

[0003] In order to obtain a virtual reality device with good imaging quality and visual experience: on the one hand, a folded optical path solution is used inside it. Due to its light and thin characteristics, the folded optical path solution gradually replaces the traditional Fresnel solution and becomes the mainstream development trend. On the other hand, the existing optical structure is not friendly to the wearing experience of myopic people. Myopic users must wear glasses to use virtual reality devices, and current virtual reality devices do not support myopia adjustment function. Summary of the invention

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

[0005] According to a first aspect of an embodiment of the present application, an optical module is provided, the optical module comprising a first lens and a flat plate element;

[0006] The optical module further includes a beam splitter, a first phase retarder and a polarized reflective element, wherein the first phase retarder is located between the beam splitter and the polarized reflective element; the beam splitter and the first phase retarder are located on either side of the first lens;

[0007] The polarized reflective element is disposed on any surface of the flat plate element, and the flat plate element is configured to be able to flip and swap the positions of its two surfaces relative to the first lens, so that the optical module can be switched between the first state and the second state;

[0008] When the optical module is in the first state, the surface of the flat element provided with the polarized reflective element faces away from the first lens; when the optical module is switched to the second state, the surface of the flat element provided with the polarized reflective element faces toward the first lens.

[0009] Optionally, the first lens is located between the beam splitter and the first phase retarder;

[0010] The optical module further includes a polarizing element, and the polarizing element is located on a side of the polarizing reflective element away from the first phase retarder.

[0011] Optionally, the optical module further includes a second lens, and the second lens is located on a side of the flat plate element away from the first lens, and a distance between the second lens and the flat plate element is 0.3 mm to 1 mm.

[0012] Optionally, the optical module further includes a polarizing element, and the polarizing element is located on a side of the second lens close to the flat element.

[0013] Optionally, the polarizing element is disposed on a surface of the second lens close to the flat element.

[0014] Optionally, the optical module further includes a display, and the display is located on a side of the first lens away from the flat panel element.

[0015] Optionally, the beam splitter element is disposed on a surface of the first lens close to the display, and the first phase retarder is disposed on a surface of the first lens far from the display.

[0016] Optionally, the minimum effective focal length of the first lens and the second lens is MinEFL, and MinEFL satisfies: 7f>MinEFL>5f;

[0017] The maximum effective focal length of the first lens and the second lens is MaxEFL, and MaxEFL satisfies: 11f>MaxEFL>8f;

[0018] Wherein, f is the focal length of the optical module.

[0019] Optionally, the focal length f of the optical module is 27 mm to 33 mm.

[0020] Optionally, the effective focal length EFL1 of the first lens is 170 mm to 225 mm, and the focal length EFL2 of the second lens is 190 mm to 280 mm.

[0021] Optionally, the sum of the effective focal length EFL1 of the first lens and the focal length EFL2 of the second lens is 400 mm to 460 mm.

[0022] Optionally, the display is configured to emit circularly polarized light or linearly polarized light;

[0023] When the light emitted by the display is linearly polarized light, a second phase retarder is arranged between the display and the first lens, and the second phase retarder is used for converting the linearly polarized light into circularly polarized light.

[0024] Optionally, the distance between the first lens and the flat plate element is L1, and L1 satisfies: 4.5mm<L1<6.5mm;

[0025] The distance between the first lens and the display is L2, and L2 satisfies: 3mm<L2<4.5mm.

[0026] Optionally, the center thickness of the first lens is T1, and T1 satisfies: 5mm<T1<7.5mm;

[0027] The thickness of the flat plate element is 2 mm to 4.5 mm.

[0028] According to a second aspect of an embodiment of the present application, a head mounted display device is also provided, including:

[0029] a housing; and

[0030] An optical module as described above.

[0031] According to the optical module provided in the embodiment of the present application, a flat element is introduced into the optical path, and a polarizing reflective element is arranged on one surface of the flat element, and the flat element can be flipped in the optical path. In this way, the orientation of the polarizing reflective element can be changed by swapping the two surfaces of the flat element in the optical path, thereby realizing the zoom function of the optical module, and making the optical module suitable for groups with normal vision and myopia. When the surface of the flat element on which the polarizing reflective element is arranged is away from the human eye, myopic users can choose to obtain a good visual experience without wearing glasses.

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

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

[0034] Figure 1 One of the structural schematic diagrams of the optical module provided in the embodiment of the present application;

[0035] Figure 2 The second structural diagram of the optical module provided in the embodiment of the present application;

[0036] Figure 3 The third structural diagram of the optical module provided in the embodiment of the present application;

[0037] Figure 4 A fourth structural diagram of an optical module provided in an embodiment of the present application;

[0038] Figure 5 A fifth structural diagram of an optical module provided in an embodiment of the present application;

[0039] Figure 6 A schematic diagram of the structure of the optical module provided in Example 1 of the present application in a first state;

[0040] Figure 7 for Figure 6 The spot diagram of the optical module shown;

[0041] Figure 8 A schematic diagram of the structure of the optical module provided in Example 1 of the present application in the second state;

[0042] Fig. 9 for Figure 8 The spot diagram of the optical module shown;

[0043] Fig.10 A schematic diagram of the structure of the optical module provided in Example 2 of the present application in a first state;

[0044] Fig.11 for Fig.10 The spot diagram of the optical module shown;

[0045] Fig.12 A schematic diagram of the structure of the optical module provided in Example 2 of the present application in the second state;

[0046] Fig.13 for Fig.12 The spot diagram of the optical module shown;

[0047] Fig.14 A schematic diagram of the structure of the optical module provided in Example 3 of the present application in a first state;

[0048] Fig.15 for Fig.14 The spot diagram of the optical module shown;

[0049] Fig.16 A schematic diagram of the structure of the optical module provided in Example 3 of the present application in the second state;

[0050] Fig.17 for Fig.16 Spot diagram of the optical module is shown.

[0051] Description of reference numerals:

[0052] 10. First lens; 20. Second lens; 30. Flat plate element; 40. Beam splitter element; 50. First phase retarder; 60. Polarized reflection element; 70. Polarizing element; 80. Display; 01. Human eye. DETAILED DESCRIPTION

[0053] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application.

[0054] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present application, its application, or uses.

[0055] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the specification.

[0056] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0057] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0058] According to one aspect of an embodiment of the present application, an optical module is provided, which is a folded optical path optical structure design, which can be suitable for use in a head mounted display (HMD). For example, a VR head mounted device may include VR glasses or a VR helmet, etc., and the embodiment of the present application does not specifically limit this.

[0059] The present application embodiment provides an optical module, such as Figures 1 to 4 As shown, the optical module includes a first lens 10 and a flat plate element 30; the optical module also includes a beam splitter 40, a first phase retarder 50 and a polarization reflection element 60, wherein the first phase retarder 50 is located between the beam splitter 40 and the polarization reflection element 60; the beam splitter 40 and the first phase retarder 50 are located on either side of the first lens 10;

[0060] The polarized reflective element 60 is disposed on any surface of the flat element 30, and the flat element 30 is configured to be able to flip and swap the positions of its two surfaces relative to the first lens 10, so that the optical module can be switched between the first state and the second state;

[0061] When the optical module is in the first state, the surface of the flat element 30 provided with the polarized reflective element 60 faces away from the first lens 10 ; when the optical module switches to the second state, the surface of the flat element 30 provided with the polarized reflective element 60 faces the first lens 10 .

[0062] In the embodiment of the present application, a lens is arranged in the optical module, namely the first lens 10 mentioned above, and a flat element 30 is introduced in the optical path. The center of the flat element 30 is located on the optical axis of the first lens 10. The flat element 30 and the first lens 10 are adjacent and spaced apart. The flat element 30 has two opposite surfaces, such as Figure 1 As shown, the two surfaces are respectively a first surface P1S1 and a second surface P1S2 .

[0063] For example, the first state of the optical module is set as the default state, at this time, the first surface P1S1 of the flat element 30 faces the first lens 10, and the second surface P1S2 of the flat element 30 faces away from the first lens 10, and the polarized reflective element 60 can be mounted on the second surface P1S2, so that the polarized reflective element 60 is set toward the human eye 01. In this case, the optical module is suitable for use by myopic people wearing glasses or by non-myopic people.

[0064] For example, when used by myopic people, the positions of the first surface P1S1 and the second surface P1S2 can be swapped by flipping the flat element 30. In this case, the optical module is suitable for myopic people to use without wearing glasses.

[0065] It should be noted that the present application includes but is not limited to setting the first state of the optical module to the default state and setting the second state to the adjusted state. In other words, the second state of the optical module may also be set to the default state and the first state to the adjusted state, which is not limited in the present application embodiment.

[0066] In the embodiment of the present application, the polarized reflective element 60 is disposed on one surface of the flat element 30. It should be emphasized that the flat element 30 is not fixed in the optical path, but can be mechanically flipped to swap the positions of the two surfaces. This design allows the user to select different experience scenarios, such as wearing glasses or not wearing glasses, simply by flipping the flat element 30.

[0067] For example, Figure 1 and Figure 2As shown, the surface of the flat element 30 provided with the polarized reflective element 60 is set as the second surface P1S2. In the optical module, when the second surface P1S2 is away from the first lens 10, that is, toward the wearer's face, the myopic user needs to wear glasses to use it. In another case, Figure 3 and Figure 4 As shown, the flat element 30 is mechanically flipped so that the second surface P1S2 (on which the polarizing reflective element 60 is mounted) is swapped with the first surface P1S1. After the swap, the second surface P1S2 is turned to face the first lens 10. At this time, the first surface P1S1 of the flat element 30, which is not provided with the polarizing reflective element 60 (the opposite side of the second surface P1S2), will face the wearer's face, so the user does not need to wear glasses to use it even if he is nearsighted.

[0068] See also Figures 1 to 4 ,Depend on Figure 3 and Figure 4 The adjusted optical module is shown with Figure 1 and Figure 2 It can be seen from the comparison of the optical module before adjustment that the overall light propagation path of the optical module has not changed much, mainly because when the light propagates to the flat element 30 after passing through the first lens 10, the surface close to the human eye 01 is provided with a polarized reflection element 60 before adjustment, and after adjustment, the surface far from the human eye 01 is provided with a polarized reflection element 60. Through the above adjustment, there is no change in the overall optical elements used, only the arrangement order of the two surfaces (P1S1 and P1S2) of the flat element 30 in the optical path is swapped. The field of view FOV and the total optical length TTL of the adjusted optical module are basically unchanged, the maximum spot size is 70um at the maximum field of view, for example, and the virtual image distance is 250mm, for example, which can meet the needs of people with myopia of 400 degrees (-4D).

[0069] The optical module of the embodiment of the present application can achieve the focusing function of the entire optical module by adjusting the position of the polarized reflective element 60 in the optical path relative to the human eye 01. Specifically, the optical module of the embodiment of the present application can be applied to groups with different visual acuity, such as -0.5D or -4D.

[0070] In addition, it should be noted that by optimizing the surface shape or increasing the number of optical elements, the optical module can also achieve a wider range of myopia diopter adjustment.

[0071] One technical effect of the optical module of the embodiment of the present application is that it can support users to independently choose to wear or not wear glasses for visual experience.

[0072] The optical module of the embodiment of the present application can meet the scenario of multiple people using one device. For example, it can meet the use of people who are not myopic in the family. Specifically, the flat element 30 is adjusted so that the surface with the polarized reflective element 60 faces the wearer's face, which can meet the use of users with normal vision and those wearing glasses. And the flat element 30 is turned over and adjusted so that the surface without the polarized reflective element 60 faces the wearer's face, which can meet the use of people with myopia without wearing glasses.

[0073] According to an embodiment of the present application, a folded optical path solution is provided. According to the optical module provided by the embodiment of the present application, a flat plate element 30 is introduced into the optical path. By setting a polarizing reflective element 60 on a surface of the flat plate element 30, and making the flat plate element 30 flippable in the optical path, the orientation of the polarizing reflective element 60 can be changed by swapping the two surfaces of the flat plate element 30 in the optical path, thereby realizing the zoom function of the optical module, and making the optical module suitable for groups with normal vision and myopia; wherein, when the surface of the flat plate element 30 on which the polarizing reflective element 60 is provided is away from the human eye 01, myopic users can choose to obtain a good visual experience without wearing glasses.

[0074] The optical module provided in the embodiment of the present application provides a good wearing experience for myopic people, allowing users to choose to wear glasses or take off glasses to use the product. In the embodiment of the present application, through the zoom solution of the folded optical path, through mechanical adjustment, myopic users can use the product without wearing glasses. At the same time, the structure of the optical module is relatively simple, the production cost is low, and the yield rate is high.

[0075] In addition, the method of causing the flat plate element 30 to generate the flipping motion may be, for example, through a driving mechanism or manually driven, which is not limited in the embodiment of the present application.

[0076] In the embodiment of the present application, the material of the flat element 30 may be, for example, a glass material or a plastic material, which has extremely high light transmittance and will not affect light propagation.

[0077] The optical module of the embodiment of the present application further includes the above-mentioned beam splitter 40 and the first phase retarder 50 .

[0078] The beam splitter 40 allows a portion of light to pass through and a portion of light to be reflected.

[0079] The light splitting element 40 is, for example, a semi-reflective and semi-transmissive film.

[0080] The first phase retarder 50 can be used to change the polarization state of light in the folded optical path structure, for example, it can convert linearly polarized light into circularly polarized light, or convert circularly polarized light into linearly polarized light.

[0081] The first phase retarder 50 is, for example, a quarter wave plate.

[0082] Both the beam splitter 40 and the first phase retarder 50 may be disposed on either side of the first lens 10 .

[0083] Optionally, the beam splitter element 40 and the first phase retarder 50 can be bonded together to form a superimposed element, and the superimposed element can be arranged in the first lens 10 or independently arranged in the optical path, and there is no specific limitation on this in the embodiment of the present application.

[0084] Optionally, the light splitting element 40 and the first phase retarder 50 may also be arranged at intervals, such as Figure 1 As shown, the two are separated by a first lens 10 .

[0085] The polarization reflection element 60 can be used to reflect S polarization light through P polarization light; or, the polarization reflection element 60 can be used to reflect P polarization light through S polarization light. The first phase retarder 50 cooperates with the polarization reflection element 60 to analyze and transmit light.

[0086] Optionally, the polarized reflective element 60 may be a thin film structure, which may be attached to one of the surfaces of the flat element 30 by, for example, optical adhesive. Figure 1 What is shown in the figure is mounted on the second surface P1S2 of the planar element 30. Of course, it can also be set on the first surface P1S1, and there is no limitation to this).

[0087] In the optical module of the present application, the polarized reflective element 60 is separately arranged from the first phase retarder 50, so as to facilitate the adjustment of the position of the polarized reflective element 60 in the optical path. It should be noted that the first phase retarder 50 needs to be located between the beam splitter 40 and the polarized reflective element 60. In the present application, the polarized reflective element 60 is supported in the optical path by a flat plate element 30 alone, which is separated from the first phase retarder 50. Even if the polarized reflective element 60 is flipped and changed in position with the flat plate element 30, the arrangement order of the beam splitter 40, the first phase retarder 50 and the polarized reflective element 60 will not be affected, and the first phase retarder 50 can still be located between the beam splitter 40 and the polarized reflective element 60.

[0088] The optical module provided in the embodiment of the present application is a folded optical path optical structure design, such as Figures 1 to 4 As shown, the optical lenses and optical elements in the optical module can be arranged in a set manner and located on the same optical axis. The size of the entire optical path structure is small and does not occupy a large space.

[0089] In some examples of this application, such as Figures 1 to 4As shown, the first lens 10 is located between the beam splitter 40 and the first phase retarder 50 ; the optical module further includes a polarizing element 70 , and the polarizing element 70 is located on a side of the polarizing reflective element 60 away from the first phase retarder 50 .

[0090] like Figures 1 to 4 As shown, the beam splitter 40 may be located on a side of the first lens 10 away from the flat plate element 30, the first phase retarder 50 may be located on a side of the first lens 10 close to the flat plate element 30, and the first lens 10 is disposed between the beam splitter 40 and the first phase retarder 50. That is, the beam splitter 40 and the first phase retarder 50 may be separated by the first lens 10.

[0091] Of course, the beam splitter 40 and the first phase retarder 50 may also be located together on a side of the first lens 10 away from the flat plate element 30 , or located on a side of the first lens 10 close to the flat plate element 30 .

[0092] It should be noted that the beam splitter 40 and the first phase retarder 50 can be independent optical devices arranged in the optical path. Both the beam splitter 40 and the first phase retarder 50 can be mounted on the first lens 10, which can reduce the difficulty of assembling the optical module.

[0093] In the embodiments of the present application, Figure 1 As shown, the optical module may further include a polarizing element 70, which can transmit P-polarized light, reduce stray light, and help improve imaging quality.

[0094] In the embodiment of the present application, the polarizing element 70 and the polarizing reflecting element 60 may be arranged at an interval, so that the polarizing reflecting element 60 can independently perform flipping motion with the flat element 30 to change the position / orientation in the light path.

[0095] When the optical module only includes the first lens 10, the polarizing element 70 can be disposed as an independent device in the optical path, so that it is located on the side of the polarizing reflective element 60 away from the first phase retarder 50. Of course, the polarizing element 70 can also be disposed on the flat element 30.

[0096] The polarizing element 70 is, for example, a polarizing film.

[0097] In some examples of this application, such as Figures 1 to 4 As shown, the optical module further includes a second lens 20 , which is located on a side of the flat plate element 30 away from the first lens 10 , and a distance between the second lens 20 and the flat plate element 30 is 0.3 mm to 1 mm.

[0098] It is understandable that the optical module of the present application may also include two lenses, such as Figure 1 As shown, the first lens 10 and the newly introduced second lens 20 are included. At this time, the flat plate element 30 supporting the polarized reflection element 60 can be located between the first lens 10 and the second lens 20 .

[0099] It should be noted that the number of lenses in the optical module of the present application is not specifically limited, and can be one, two, or greater than or equal to three. As the number of lenses increases, the imaging quality can be improved, but the size of the optical module will be affected. Among them, it is more preferred to set two lenses in the optical path, which can not only improve the imaging quality, but also make the optical module have good imaging quality.

[0100] Optionally, the first lens 10 and the second lens 20 are plano-convex lenses.

[0101] For example, the first lens 10 includes two surfaces, namely a third surface L1S1 and a fourth surface L1S2, wherein the surface shape of the third surface L1S1 is designed to be a convex surface, and the surface shape of the fourth surface L1S2 is designed to be a plane, and the curvature of the third surface L1S1 of the first lens 10 satisfies the following conditions:

[0102] 85 <abs(R_L1S1)<110,ABS(Conic_L1S1)<5。

[0103] For example, the second lens 20 includes two surfaces, namely a fifth surface L2S1 and a sixth surface L2S2, wherein the surface shape of the fifth surface L2S1 is designed to be a plane, the surface shape of the sixth surface L2S2 is designed to be a convex surface, and the curvature of the sixth surface L2S2 of the second lens 20 satisfies the following conditions:

[0104] 90 <abs(R_L2S2)<140,ABS(Conic_L2S2)<5。

[0105] Of course, the first lens 10 and the second lens 20 include but are not limited to the above-mentioned surface shapes, which are not limited in the embodiments of the present application.

[0106] In addition, the material of the lens in the optical module can be PMMA material. Of course, the lens can also be other materials such as glass, COC, COP and other materials. There is no specific limitation on this in the embodiments of the present application.

[0107] Optionally, the flat plate element 30 may also be a PMMA flat plate or a glass flat plate.

[0108] In addition, the flat plate element 30 may also be replaced by other shapes such as a plano-convex element, a plano-concave element, a bi-concave element, or a bi-convex element.

[0109] In the optical module of the embodiment of the present application, the distance between the second lens 20 and the flat element 30 can be set to 0.3mm~1mm, which will not increase the size of the optical module, is conducive to realizing the lightness and thinness of the optical module, and at the same time can ensure the imaging quality, and can also adjust the position of the virtual image by utilizing the focusing of the optical module.

[0110] For example, the distance between the second lens 20 and the flat element 30 is 0.3 mm, which can better reduce the size of the optical module and ensure better imaging quality, and also make the optical module suitable for -0.5D or -4D myopic people to use the optical module without wearing glasses.

[0111] Optionally, if Figures 1 to 4 As shown, the optical module further includes a polarizing element 70 , and the polarizing element 70 is located on a side of the second lens 20 close to the flat element 30 .

[0112] For example, the polarizing element 70 is disposed on a surface of the second lens 20 close to the flat element 30 .

[0113] The polarizing element 70 can transmit P-polarized light, thereby reducing stray light and improving imaging quality.

[0114] After the second lens 20 is introduced into the optical module, the polarizing element 70 can be arranged close to the second lens 20 or directly bonded to the surface of the second lens 20 by optical adhesive. In this way, the polarizing element 70 can be arranged separately from the polarizing reflective element 60, so that the polarizing reflective element 60 can move independently with the flat element 30 and change the position / orientation in the optical path, and at the same time, the arrangement of the optical film will not be affected. For example, the polarizing reflective element 60 can be located between the first phase retarder 50 and the polarizing element 70.

[0115] The optical structure design of the present application realizes a new optical module focusing mode or method, which not only meets the use needs of the group wearing glasses or the non-myopic user group, but also meets the use needs of the myopic group when not wearing glasses.

[0116] In some examples of this application, such as Figures 1 to 4 As shown, the optical module further includes: a display 80 , and the display 80 is located on a side of the first lens 10 away from the flat element 30 .

[0117] Optionally, the display 80 is configured to emit circularly polarized light or linearly polarized light; when the light emitted by the display 80 is linearly polarized light, a second phase retarder ( Figures 1 to 4 The second phase retarder is used to convert linearly polarized light into circularly polarized light.

[0118] The display 80 has a light emitting surface, and a screen protection sheet may be attached to the light emitting surface of the display 80 , for example.

[0119] The light emitted by the light emitting surface of the display 80 may be linearly polarized light, circularly polarized light or natural light, which is not limited in the embodiments of the present application.

[0120] It should be noted that when the light emitted from the light emitting surface of the display 80 is circularly polarized light, the second phase retarder and the second polarization element mentioned above may be omitted.

[0121] In addition, when it is necessary to set a second phase retarder at the light-emitting surface of the display 80, a polarizing element (polarizing film) can be introduced into the optical path. At this time, the second phase retarder and the newly introduced polarizing element can be stacked and arranged on the light-emitting surface of the display 80. Of course, the two can also be arranged at intervals. The second phase retarder is located between the newly introduced polarizing element and the light-emitting surface of the display 80.

[0122] Optionally, the size of the display 80 can be 2.5 inches. In the first state, the optical module can obtain a FOV of about 100°, a spot size of the entire field of view of <45um, high imaging quality, and a virtual image distance of 2000mm, which can match people with myopia around 50 degrees (-0.5D).

[0123] When the optical module is adjusted from the first state to the second state, the optical path structure is as follows Figure 3 and Figure 4 As shown, the surface of the flat element 30 provided with the polarized reflective element 60 is away from the human eye 01, and the overall optical path does not change much. The main thing is that when the optical path propagates to the flat element 30 after passing through the first lens 10, the surface close to the human eye is provided with the polarized reflective element 60 before adjustment, and the surface away from the human eye is provided with the polarized reflective element 60 after adjustment. Through the adjustment, the overall optical elements used do not change at all, and after the adjustment, the field of view FOV and the total optical length TTL of the optical module are basically unchanged. The maximum spot size is 70um at the maximum field of view, and the virtual image distance is 250mm, which can meet the needs of people with myopia of 400 degrees (-4D).

[0124] In some examples of this application, such as Figure 1 As shown, the beam splitter 40 is disposed on a surface of the first lens 10 close to the display 80 , and the first phase retarder 50 is disposed on a surface of the first lens 10 far from the display 80 .

[0125] For example, the beam splitter 40 and the first phase retarder 50 can be respectively disposed on two surfaces of the first lens 10. The beam splitter 40 can be disposed on the surface (L1S1 surface) of the first lens 10 close to the display 80 by coating, and the first phase retarder 50 can be mounted on the surface (L1S2 surface) of the first lens 10 far from the display 80 by optical film.

[0126] Among them, the surface of the lens on which the optical film is attached by optical adhesive can be designed to be flat. The use of a flat film attachment method in the optical path can reduce the difficulty of optical film attachment. Of course, it is also possible to use a curved surface / cylindrical surface, etc. for attachment, which is not specifically limited in the embodiments of the present application.

[0127] In some examples of the present application, when the optical module includes two lenses, namely a first lens 10 and a second lens 20, the minimum effective focal length of the first lens 10 and the second lens 20 is MinEFL, and MinEFL satisfies: 7f>MinEFL>5f; the maximum effective focal length of the first lens 10 and the second lens 20 is MaxEFL, and MaxEFL satisfies: 11f>MaxEFL>8f; wherein f is the focal length of the optical module.

[0128] In order to meet the needs of people with different vision, the optical module of the embodiment of the present application can adjust the effective focal length of the first lens 10 and the second lens 20 in the optical module, and adjust the position of the polarized reflective element 60 attached to the flat element 30 in the optical module, so that the optical module of the embodiment of the present application can be applied to people with different vision. The optical module of the embodiment of the present application can be used by people who wear glasses or people who are not myopic, and can also be used by people with myopia without wearing glasses.

[0129] In addition, by optimizing the face shape or increasing the number of optical elements, it can also be suitable for myopic people with greater vision to use without wearing glasses.

[0130] Optionally, the focal length f of the optical module is 27 mm to 33 mm.

[0131] The effective focal length EFL1 of the first lens 10 is 170 mm to 225 mm, and the focal length EFL2 of the second lens 20 is 190 mm to 280 mm.

[0132] The sum of the effective focal length EFL1 of the first lens 10 and the focal length EFL2 of the second lens 20 is 400 mm to 460 mm.

[0133] By adjusting the parameters of the focal length of the optical module and the effective focal lengths of the two lenses, the optical module of the embodiment of the present application can be suitable for, for example, -0.5D diopter or -4D diopter. At -0.5D, it can meet the needs of people wearing glasses or non-myopic people, and at -4D, it can meet the needs of people with 400-degree myopia without wearing glasses.

[0134] In some examples of this application, such as Figure 5 The distance between the first lens 10 and the flat panel element 30 is L1, and L1 satisfies: 4.5 mm<L1<6.5 mm; the distance between the first lens 10 and the display 80 is L2, and L2 satisfies: 3 mm<L2<4.5 mm.

[0135] Optionally, if Figure 5 As shown, the central thickness of the first lens 10 is T1, and T1 satisfies: 5mm<T1<7.5mm; the thickness of the flat plate element 30 is 2mm~4.5mm.

[0136] In the embodiment of the present application, the first lens 10 and the flat panel element 30 are designed to be relatively thin, and the distance between the first lens 10, the flat panel element 30 and the display 80 is also relatively small, which is conducive to reducing the size of the optical module, achieving a thin and light final product, and improving the comfort of the user when wearing it. At the same time, the image quality can be better.

[0137] like Figure 5 As shown, when the optical module further includes a second lens 20, optionally, a center thickness T2 of the second lens 20 is: 4 mm<T2<6 mm.

[0138] The second lens 20 on the side close to the human eye 01 is also relatively light and thin, and will not increase the size and weight of the optical module. It can support the polarizing element 70 and also improve the imaging effect of the optical module.

[0139] The FOV of the optical module provided in the embodiment of the present application is ≥100°.

[0140] In the optical module of the embodiment of the present application, the image displayed on the display 80 can be transmitted through the folded light path through refraction and reflection and amplified before being input into the human eye 01 , and the human eye 01 will be able to see the amplified virtual image.

[0141] The optical module of the embodiment of the present application can be used in conjunction with a 2.4 or 2.5-inch Micro OLED / LCD display chip to achieve a 100-degree field of view.

[0142] At the same time, the total optical length of the optical module is about 24mm, the size of the optical module is small, and the imaging quality is good.

[0143] The optical module of the embodiment of the present application is described below with reference to specific embodiments.

[0144] Example 1

[0145] The optical module shown in this embodiment 1 is as follows: Figure 6 and Figure 8 As shown, it includes a first lens 10, a second lens 20, a flat panel element 30 and a display 80, wherein the flat panel element 30 is located between the first lens 10 and the second lens 20, and the first lens 10 is close to the display 80;

[0146] The optical module further includes a beam splitter 40, a first phase retarder 50 and a polarized reflective element 60. The beam splitter 40 is disposed on a third surface L1S1 of the first lens 10 close to the display 80. The first phase retarder 50 is disposed on a fourth surface L1S2 of the first lens 10 far from the display 80. The polarized reflective element 60 is disposed on a second surface P1S2 of the flat element 30. The flat element 30 also has a first surface P1S1. The polarized element 70 is disposed on a fifth surface L2S1 of the second lens 20 close to the display 80.

[0147] The flat plate element 30 is configured to be able to flip relative to the first lens 10 to exchange the positions of the two surfaces, so that the optical module can be switched between the first state and the second state; when the optical module is in the first state, Figure 6 As shown, the surface of the flat element 30 provided with the polarized reflective element 60 is away from the first lens 10; when the optical module is switched to the second state, as shown Figure 8 As shown, the surface of the flat plate element 30 provided with the polarized reflection element 60 is flipped to face the first lens 10 .

[0148] like Figure 6 and Figure 8 As shown, the light propagation path of the optical module is as follows:

[0149] The display 80 emits circularly polarized light. After the circularly polarized light passes through the third surface L1S1 (on which the beam splitter 40 is disposed) of the first lens 10 close to the display 80, about 50% of the light is transmitted and then transmitted through the first lens 10 to the second surface L1S2. After being converted by the first phase retarder 50, it becomes linearly polarized light. Then, after passing through the first surface P1S1 of the flat element 30, it passes through the second surface P1S2. Then, it is reflected by the polarization reflection element 60 attached to the second surface P1S2 and returns to the first surface P1S1 and then to the fourth surface L1S2 of the first lens 10. After passing through the first phase retarder 50, it becomes circularly polarized light and returns to the third surface L1S1 of the first lens 10 again. After passing through the beam splitter 40, a part of the light is reflected back to the first lens 10 and then reaches the fourth surface L1S2 of the first lens 10 again. After passing through the first phase retarder 50, it becomes linearly polarized light and passes through the first surface P1S1 and the second surface P1S2 of the flat element 30 again. After being reflected by the beam splitter 40 , the linear polarized light is in the same direction as the transmission light axis of the polarized reflective element 60 . After being transmitted out of the polarized reflective element 60 , the linear polarized light passes through the polarizing element 70 on the second lens 20 , and finally enters the human eye 01 after being transmitted through the surface L2S2 of the second lens 20 .

[0150] In the optical module provided in the present embodiment 1, the display 80 is a 2.4-inch Micro OLED / LCD display chip, which can achieve a 100-degree viewing angle, and the total optical length TTL of the optical module is 24 mm.

[0151] When the optical module is in the first state, Figure 6 As shown, the second surface P1S2 of the flat element 30 is facing the human eye 01, that is, the polarized reflection element 60 is facing the human eye 01. At this time, the virtual image distance VID of the optical module is 2000mm, and the focal length f of the optical module is 29.19mm, wherein the effective focal length EFL1 of the first lens 10 is 172.96mm, and the effective focal length EFL2 of the second lens 20 is 260.6mm.

[0152] The optical module (with a diopter of -0.5D) can match people who wear glasses or are not nearsighted in the first state. Figure 7 As shown, within the entire field of view, the maximum spot size is less than 35.1um at 1.0F.

[0153] Table 1 shows the optical parameters of the optical module in the first state;

[0154] The polarized reflective element 60 is mounted on the second surface P1S2 of the flat element 30 , and the polarized reflective element 60 faces the human eye 01 .

[0155] Table 1

[0156] Surf Type Radius Thickness GLASS ClearDiam MechDiam Conic 4th OBJ STANDARD Infinity -2000.000 2383.507 2383.507 0 0 STO STANDARD Infinity 13.000 2.000 2.000 0 0 2 EVENASPH 128.786 4.500 PMMA 21.000 22.000 -0.878 -1.746E-06 3 STANDARD Infinity 0.300 21.000 22.000 0 0 4 STANDARD Infinity 2.313 PMMA 27.400 27.500 0 0 5 STANDARD Infinity 5.426 27.400 27.500 0 0 6 STANDARD Infinity 7.000 PMMA 28.800 29.000 0 0 7 EVENASPH -95.251 -7.000 MIRROR 28.800 29.000 -0.706 -1.879E-07 8 STANDARD Infinity -5.426 28.800 29.000 0 0 9 STANDARD Infinity -2.313 PMMA 27.400 27.500 0 0 10 STANDARD Infinity 2.313 MIRROR 27.400 27.500 0 0 11 STANDARD Infinity 5.426 27.400 27.500 0 0 12 STANDARD Infinity 7.000 PMMA 28.800 29.000 0 0 13 EVENASPH -95.251 4.000 28.800 29.000 -0.706 -1.879E-07 14 STANDARD Infinity 0.500 BK7 23.000 23.000 0 0 15 STANDARD Infinity 0.020 23.000 23.000 0 0 IMA STANDARD Infinity 0.000 22.147 22.147 0 0

[0157] like Figure 8 As shown, when the optical module is in the second state, the first surface P1S1 and the second surface P1S2 of the flat element 30 are swapped in the optical path, that is, the first surface P1S1 of the flat element 30 faces the human eye 01, that is, the polarized reflection element 60 changes from facing the human eye 01 to away from the human eye 01. At this time, the virtual image distance VID of the optical module is 250mm, and the focal length f of the optical module is 28.74mm, wherein the effective focal length EFL1 of the first lens 10 is 172.96mm, and the effective focal length EFL2 of the second lens 20 is 260.6mm.

[0158] The optical module (with a visual acuity of -4D) can be used by people with myopia of about 400 degrees without wearing glasses in the second state. Fig. 9 As shown, within the entire field of view, the maximum spot size is less than 70um at 1.0F.

[0159] Table 2 shows the optical parameters of the optical module in the second state;

[0160] The polarized reflective element 60 is mounted on the second surface P1S2 of the flat element 30 , and the polarized reflective element 60 faces away from the human eye 01 .

[0161] Table 2

[0162] Surf Type Radius Thickness GLASS ClearDiam MechDiam Conic 4th OBJ STANDARD Infinity -250.000 297.938 297.938 0 0 STO STANDARD Infinity 13.000 2.000 2.000 0 0 2 EVENASPH 128.786 4.500 PMMA 21.000 22.000 -0.878 -1.746E-06 3 STANDARD Infinity 0.300 21.000 22.000 0 0 4 STANDARD Infinity 2.313 PMMA 27.400 27.500 0 0 5 STANDARD Infinity 5.426 27.400 27.500 0 0 6 STANDARD Infinity 7.000 PMMA 28.800 29.000 0 0 7 EVENASPH -95.251 -7.000 MIRROR 28.800 29.000 -0.706 -1.879E-07 8 STANDARD Infinity -5.426 28.800 29.000 0 0 9 (virtual surface) STANDARD Infinity 0.000 27.400 27.500 0 0 10 (virtual surface) STANDARD Infinity 0.000 27.400 27.500 0 0 11 STANDARD Infinity 5.426 MIRROR 27.400 27.500 0 0 12 STANDARD Infinity 7.000 PMMA 28.800 29.000 0 0 13 EVENASPH -95.251 4.000 28.800 29.000 -0.706 -1.879E-07 14 STANDARD Infinity 0.500 BK7 23.000 23.000 0 0 15 STANDARD Infinity 0.020 23.000 23.000 0 0 IMA STANDARD Infinity 0.000 22.545 22.545 0 0

[0163] Example 2

[0164] The optical module shown in this embodiment 2 is as follows: Fig.10 and Fig.12 As shown, the difference between the optical module shown in Example 1 is that:

[0165] When the optical module is in the first state, Fig.10 As shown, the focal length f of the optical module is 27.08 mm, the effective focal length EFL1 of the first lens 10 is 176.86 mm, and the effective focal length EFL2 of the second lens 20 is 276.5 mm.

[0166] The optical module (with a diopter of -0.5D) can match people who wear glasses or are not nearsighted in the first state. Fig.11 As shown, within the entire field of view, the maximum spot size is less than 78um at 1.0F.

[0167] Table 3 shows the optical parameters of the optical module of Example 2 in the first state;

[0168] Table 3

[0169] Surf Type Radius Thickness GLASS ClearDiam MechDiam Conic 4th 0 STANDARD Infinity -2000.000 2383.507 2383.507 0 0 1 STANDARD Infinity 13.000 2.000 2.000 0 0 2 EVENASPH 136.612 4.500 PMMA 20.500 21.000 -1.001 1.22E-06 3 STANDARD Infinity 0.300 21.000 21.000 0 0 4 STANDARD Infinity 2.000 PMMA 26.500 26.500 0 0 5 STANDARD Infinity 6.033 26.500 26.500 0 0 6 STANDARD Infinity 5.416 PMMA 27.700 27.700 0 0 7 EVENASPH -87.392 -5.416 MIRROR 27.700 27.700 -1.001 2.78E-07 8 STANDARD Infinity -6.033 27.700 27.700 0 0 9 STANDARD Infinity -2.000 PMMA 26.400 26.500 0 0 10 STANDARD Infinity 2.000 MIRROR 26.500 26.500 0 0 11 STANDARD Infinity 6.033 26.500 26.500 0 0 12 STANDARD Infinity 5.416 PMMA 27.700 27.700 0 0 13 EVENASPH -87.392 3.499 27.700 27.700 -1.001 2.78E-07 14 STANDARD Infinity 0.500 BK7 22.288 22.288 0 0 15 STANDARD Infinity 0.019 22.226 22.288 0 0 16 STANDARD Infinity 0.000 22.123 22.123 0 0

[0170] The optical module shown in the second embodiment is different from the first embodiment in that:

[0171] like Figure 12 As shown, when the optical module is in the second state, the focal length f of the optical module is 26.69 mm, the effective focal length EFL1 of the first lens 10 is 176.86 mm, and the effective focal length EFL2 of the second lens 20 is 276.5 mm.

[0172] The optical module (with a visual acuity of -4D) can be used by people with myopia of about 400 degrees without wearing glasses in the second state. Figure 13 As shown, within the entire field of view, the maximum spot size is less than 93um at 0.8F.

[0173] Table 4 shows the optical parameters of the optical module of Example 2 in the second state;

[0174] Table 4

[0175]

[0176]

[0177] Example 3

[0178] The optical module shown in this embodiment 3 is as follows: Figure 14 and Figure 16 As shown, the difference between the optical module shown in Example 1 is that:

[0179] When the optical module is in the first state, Figure 14 As shown, the focal length f of the optical module is 32.4 mm, the effective focal length EFL1 of the first lens 10 is 221.5 mm, and the effective focal length EFL2 of the second lens 20 is 191 mm.

[0180] The optical module (with a diopter of -0.5D) can match people who wear glasses or are not nearsighted in the first state. Figure 15 As shown, within the entire field of view, the maximum spot size is less than 66um at 0.6F.

[0181] Table 5 shows the optical parameters of the optical module of Example 3 in the first state;

[0182] Table 5

[0183] Surf Type Radius Thickness GLASS ClearDiam MechDiam Conic 4th 0 STANDARD Infinity -2000.000 2383.507 2383.507 0 0 1 STANDARD Infinity 13.000 2.000 2.000 0 0 2 EVENASPH 94.491 4.499 PMMA 21.000 21.000 -5.000 -6.427E-06 3 STANDARD Infinity 0.680 21.000 21.000 0 0 4 STANDARD Infinity 2.800 PMMA 29.600 29.600 0 0 5 STANDARD Infinity 6.468 29.600 29.600 0 0 6 STANDARD Infinity 6.433 PMMA 31.500 31.500 0 0 7 EVENASPH -109.427 -6.433 MIRROR 31.500 31.500 -5.000 -9.479E-07 8 STANDARD Infinity -6.468 31.500 31.500 0 0 9 STANDARD Infinity -2.800 PMMA 29.600 29.600 0 0 10 STANDARD Infinity 2.800 MIRROR 29.600 29.600 0 0 11 STANDARD Infinity 6.468 29.600 29.600 0 0 12 STANDARD Infinity 6.433 PMMA 31.500 31.500 0 0 13 EVENASPH -109.427 4.000 31.500 31.500 -5.000 -9.479E-07 14 STANDARD Infinity 0.500 BK7 23.155 23.155 0 0 15 STANDARD Infinity 0.020 23.074 23.155 0 0 16 STANDARD Infinity 0.000 22.969 22.969 0 0

[0184] The optical module shown in the third embodiment is different from the first embodiment in that:

[0185] like Figure 16 As shown, when the optical module is in the second state, the focal length f of the optical module is 31.85 mm, the effective focal length EFL1 of the first lens 10 is 221.5 mm, and the effective focal length EFL2 of the second lens 20 is 191 mm.

[0186] The optical module (with a visual acuity of -4D) can match people who wear glasses or are not nearsighted in the second state. Figure 17 As shown, within the entire field of view, the maximum spot size is less than 82um at 1.0F.

[0187] Table 6 shows the optical parameters of the optical module of Example 3 in the second state;

[0188] Table 6

[0189] Surf Type Radius Thickness GLASS ClearDiam MechDiam Conic 4th 0 STANDARD Infinity -250.000 297.938 297.938 0 0 1 STANDARD Infinity 13.000 2.000 2.000 0 0 2 EVENASPH 94.491 4.499 PMMA 21.000 21.000 -5.00 -6.427E-06 3 STANDARD Infinity 0.680 21.000 21.000 0 0 4 STANDARD Infinity 2.800 PMMA 29.600 29.600 0 0 5 STANDARD Infinity 6.468 29.600 29.600 0 0 6 STANDARD Infinity 6.433 PMMA 31.500 31.500 0 0 7 EVENASPH -109.427 -6.433 MIRROR 31.500 31.500 -5.00 -9.479E-07 8 STANDARD Infinity -6.468 31.500 31.500 0 0 9 (Virtual Surface) STANDARD Infinity 0.000 29.600 29.600 0 0 10 (Virtual Surface) STANDARD Infinity 0.000 29.600 29.600 0 0 11 STANDARD Infinity 6.468 MIRROR 29.600 29.600 0 0 12 STANDARD Infinity 6.433 PMMA 31.500 31.500 0 0 13 EVENASPH -109.427 4.000 31.500 31.500 -5.00 -9.479E-07 14 STANDARD Infinity 0.500 BK7 23.775 23.775 0 0 15 STANDARD Infinity 0.022 23.632 23.775 0 0 16 STANDARD Infinity 0.000 23.522 23.522 0 0

[0190] The optical module of the embodiment of the present application is an optical system based on a folded optical path solution, which achieves focusing by adjusting key optical elements. It not only meets the usage needs of groups wearing glasses or non-myopic users, but also meets the usage needs when not wearing glasses.

[0191] According to another aspect of an embodiment of the present application, a head-mounted display device is further provided, the head-mounted display device comprising a housing and the optical module as described above.

[0192] The head-mounted display device is, for example, a VR head-mounted device, including VR glasses or a VR helmet, etc., and the embodiments of the present application do not impose specific restrictions on this.

[0193] The specific implementation of the head mounted display device of the embodiment of the present application can refer to the above-mentioned display module embodiments, which will not be repeated here.

[0194] The above embodiments focus on the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. Considering the simplicity of the text, they will not be repeated here.

[0195] Although some specific embodiments of the present application have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are only for illustration, not for limiting the scope of the present application. It should be understood by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims

1. An optical module, characterized in that: It comprises a first lens (10) and a flat plate element (30); The optical module further comprises a beam splitter (40), a first phase retarder (50) and a polarized reflective element (60), wherein the first phase retarder (50) is located between the beam splitter (40) and the polarized reflective element (60); the beam splitter (40) and the first phase retarder (50) are located on either side of the first lens (10); The polarized reflection element (60) is arranged on any surface of the flat element (30), and the flat element (30) is configured to be able to flip and exchange the positions of its two surfaces relative to the first lens (10), so that the optical module can be switched between the first state and the second state; When the optical module is in the first state, the surface of the flat plate element (30) on which the polarized reflection element (60) is provided faces away from the first lens (10); when the optical module is switched to the second state, the surface of the flat plate element (30) on which the polarized reflection element (60) is provided faces toward the first lens (10).

2. The optical module according to claim 1, characterized in that: The first lens (10) is located between the beam splitting element (40) and the first phase retarder (50); The optical module further comprises a polarizing element (70), wherein the polarizing element (70) is located on a side of the polarizing reflection element (60) away from the first phase retarder (50).

3. The optical module according to claim 1, characterized in that: The optical module further comprises a second lens (20), the second lens (20) being located on a side of the flat plate element (30) away from the first lens (10), and the distance between the second lens (20) and the flat plate element (30) being 0.3 mm to 1 mm.

4. The optical module according to claim 3, characterized in that: The optical module further comprises a polarizing element (70), and the polarizing element (70) is located on a side of the second lens (20) close to the flat plate element (30).

5. The optical module according to claim 4, characterized in that: The polarizing element (70) is arranged on a surface of the second lens (20) close to the flat plate element (30).

6. The optical module according to any one of claims 1 to 5, characterized in that: The optical module further comprises a display (80), wherein the display (80) is located on a side of the first lens (10) facing away from the flat panel element (30).

7. The optical module according to claim 6, characterized in that: The light splitting element (40) is arranged on a surface of the first lens (10) close to the display (80), and the first phase retarder (50) is arranged on a surface of the first lens (10) far from the display (80).

8. The optical module according to claim 6, characterized in that: The minimum effective focal length of the first lens (10) and the second lens (20) is MinEFL, and MinEFL satisfies: 7f>MinEFL>5f; The maximum effective focal length of the first lens (10) and the second lens (20) is MaxEFL, and MaxEFL satisfies: 11f>MaxEFL>8f; Wherein, f is the focal length of the optical module.

9. The optical module according to claim 6, characterized in that: The focal length f of the optical module is 27 mm to 33 mm.

10. The optical module according to claim 6, characterized in that: The effective focal length EFL1 of the first lens (10) is 170 mm to 225 mm, and the focal length EFL2 of the second lens (20) is 190 mm to 280 mm.

11. The optical module according to claim 6, characterized in that: The sum of the effective focal length EFL1 of the first lens (10) and the focal length EFL2 of the second lens (20) is 400 mm to 460 mm.

12. The optical module according to claim 6, characterized in that: The display (80) is configured to emit circularly polarized light or linearly polarized light; When the light emitted by the display (80) is linearly polarized light, a second phase retarder is arranged between the display (80) and the first lens (10), and the second phase retarder is used to convert the linearly polarized light into circularly polarized light.

13. The optical module according to claim 6, characterized in that: The distance between the first lens (10) and the flat plate element (30) is L1, and L1 satisfies: 4.5 mm < L1 < 6.5 mm; The distance between the first lens (10) and the display (80) is L2, and L2 satisfies: 3mm<L2<4.5mm.

14. The optical module according to claim 1, characterized in that: The central thickness of the first lens (10) is T1, and T1 satisfies: 5mm<T1<7.5mm; The thickness of the flat plate element (30) is 2 mm to 4.5 mm.

15. A head mounted display device, characterized in that: include: case; as well as An optical module as claimed in any one of claims 1 to 14.

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