Optical module and head-mounted display device

Abstract

Embodiments of the present application provide an optical module and a head-mounted display device. The optical module comprises a display, a first imaging element, and a second imaging element. The first imaging element comprises a lens group arranged along the same optical axis, and a light splitting element, a first phase retarder and a first polarization reflector which are sequentially arranged between optical paths of the lens group. A first included angle is formed between the optical axis of the first imaging element and the central axis of the display, and the focal power φ1 of the first imaging element is zero. The second imaging element comprises a turning element and a second polarization reflector arranged on any side of the turning element, the second imaging element is located between the display and the first imaging element, and a second included angle is formed between the second imaging element and the optical axis of the first imaging element. According to a novel optical framework provided by the embodiments of the present application, a folding optical path matches the turning element, so that an AR optical scheme that a virtual picture and a real picture share an optical path is realized.

Description

Optical modules and head-mounted display devices Technical Field

[0001] The embodiments of the present application relate to the field of optical imaging technology. More specifically, the embodiments of the present application relate to an optical module and a head-mounted display device. Background Art

[0002] Augmented reality (AR) technology uses near-eye display solutions to overlay virtual images onto real scenes, providing users with an immersive and interactive experience. Currently, diffractive waveguides are commonly used as display solutions for AR.

[0003] However, existing diffraction waveguides have inherent drawbacks, such as low system efficiency and varying efficiency utilization rates due to the different paths taken by light with different viewing angles when propagating through the diffraction waveguide. In other words, existing diffraction waveguides have poor display effects.

[0004] Summary of the Invention

[0005] The purpose of this application is to provide a new technical solution for an optical module and a head-mounted display device.

[0006] In a first aspect, the present application provides an optical module. The optical module comprises:

[0007] monitor;

[0008] a first imaging element, the first imaging element comprising a lens group arranged along a common optical axis, and a beam splitter, a first phase retarder, and a first polarizing reflector sequentially arranged between optical paths of the lens group, wherein the optical axis of the first imaging element forms a first angle with a central axis of the display, and the optical power φ1 of the first imaging element is zero;

[0009] The second imaging element includes a turning element and a second polarizing reflector arranged on either side of the turning element. The second imaging element is located between the display and the first imaging element and forms a second angle with the optical axis of the first imaging element.

[0010] Optionally, the optical power φ2 of the second imaging element is zero.

[0011] Optionally, the optical module further includes a second phase retarder, and the second phase retarder is located between the second polarization reflector and the lens group.

[0012] Optionally, the lens group includes at least two lenses glued to each other to form a glued lens group, and the glued lens group forms a flat lens group with zero optical power.

[0013] Optionally, the lens assembly includes a first lens, a second lens, and a third lens glued together in sequence, the combined optical power of the first lens, the second lens, and the third lens is zero, and a surface of the first lens facing away from the second lens and a surface of the third lens facing away from the second lens have the same surface shape;

[0014] The surface of the first lens facing away from the second lens and the surface of the third lens facing away from the second lens are both flat surfaces, or arc surfaces that are curved toward the same side.

[0015] Optionally, the second phase retarder is located in the first imaging element and is arranged on a surface of the third lens facing away from the second lens.

[0016] Optionally, the second polarizing reflector is disposed on a surface of the turning element close to the display.

[0017] Optionally, the turning element is a flat plate element whose optical power is zero.

[0018] Optionally, the light splitting element is glued between the second lens and the third lens;

[0019] The first phase retarder and the first polarization reflector are stacked and glued between the second lens and the first lens.

[0020] Optionally, the optical module further includes a first polarizer, and the first polarizer is arranged on a side of the first polarizing reflector away from the first phase retarder;

[0021] The first polarizer, the first polarization reflector and the first phase retarder are stacked in sequence to form a composite film.

[0022] Optionally, the optical module is applied to an AR device.

[0023] Optionally, the display emits a first light and transmits it to the second polarized reflector;

[0024] The second polarization reflector reflects the horizontal polarization component of the first light to form horizontal linear polarized light, and the horizontal linear polarized light passes through the second phase retarder;

[0025] The second phase retarder converts the horizontal linear polarized light into left-handed circularly polarized light. The left-handed circularly polarized light is folded back between the beam splitter of the first imaging element and the first polarizing reflector, and finally emitted to the aperture through the first lens.

[0026] Optionally, a second light from the outside world passes through the turning element, and the second polarizing reflector modulates the second light into vertical linear polarized light, and the vertical linear polarized light passes through the second phase retarder; the second phase retarder converts the vertical linear polarized light into right-handed circularly polarized light, and the right-handed polarized light is projected into the first imaging element and modulated into vertical linear polarized light by the first phase retarder. After passing through the first polarizing reflector and the first lens, the vertical linear polarized light is projected onto the aperture.

[0027] Optionally, the focal length of the optical module is F, the thickness of the first imaging element along the optical axis is D, and D and F satisfy: 0.3≤D / F≤0.6.

[0028] Optionally, the absolute values ​​of the curvature radii of the two surfaces on which the first lens and the second lens are glued to each other are both C1, and the absolute values ​​of the curvature radii of the two surfaces on which the second lens and the third lens are glued to each other are both C2, then -0.6≤(C1-C2) / C1≤0.6.

[0029] In a second aspect, the present application provides a head-mounted display device. The head-mounted display device includes:

[0030] a housing; and

[0031] The optical module as described in the first aspect.

[0032] The beneficial effects of this application are:

[0033] According to an embodiment of the present application, a new AR near-eye display optical architecture is provided, which includes a real display, a turning element provided with a polarizing reflector and a group of folded optical path modules. The entire optical architecture combines the folded optical path and the turning element to realize the transmission of virtual image light and real image light using a common optical path, thereby realizing augmented reality display with good imaging quality.

[0034] Other features and advantages of the present specification will become apparent from the following detailed description of exemplary embodiments of the present specification with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the specification and, together with the description, serve to explain the principles of the specification.

[0036] FIG1 is an optical architecture diagram of an optical module provided in an embodiment of the present application;

[0037] FIG2 is a modulation transfer function (MTF) curve of the optical module provided in an embodiment of the present application at 450 nm;

[0038] FIG3 is a modulation transfer function (MTF) curve of the optical module provided in an embodiment of the present application at 540 nm;

[0039] FIG4 is a modulation transfer function (MTF) curve of the optical module provided in an embodiment of the present application at 610 nm.

[0040] Explanation of the accompanying drawings: 01, aperture; 001, first light; 1, display; 2, first lens; 3, second lens; 4, third lens; 5, second phase retarder; 6, turning element; 7, second polarizing reflector; 8, first polarizing reflector; 9, first phase retarder; 10, spectrometer; 11, first polarizer. DETAILED DESCRIPTION

[0041] 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 arrangements of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application.

[0042] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present disclosure, its application, or uses.

[0043] Techniques and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the techniques and equipment should be considered part of the specification.

[0044] 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.

[0045] It should be noted that like reference numerals and letters refer to like items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0046] The optical module and head-mounted display device provided in the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0047] According to one aspect of an embodiment of the present application, an optical module is provided. The optical module can be suitable for use in a head-mounted display (HMD), such as an augmented reality (AR) head-mounted display. The AR head-mounted display device includes, for example, AR smart glasses or an AR smart helmet. The specific form of the head-mounted display device is not limited in the embodiments of the present application.

[0048] The optical module provided in an embodiment of the present application, as shown in FIG1 , includes a display 1, a first imaging element, and a second imaging element. The first imaging element includes a lens group arranged along the same optical axis, and a beam splitter 10, a first phase retarder 9, and a first polarizing reflector 8 sequentially arranged between the optical paths of the lens group. The optical axis of the first imaging element forms a first angle with the central axis of the display 1, and the optical focal length φ1 of the first imaging element is zero. The second imaging element includes a turning element 6 and a second polarizing reflector 7 arranged on either side of the turning element 6. The second imaging element is located between the display 1 and the first imaging element, and forms a second angle with the optical axis of the first imaging element.

[0049] According to the above-mentioned embodiment of the present application, a new type of AR near-eye display optical module is provided, see Figure 1, in which the optical architecture shown includes a real display 1, a turning element 6 provided with a polarizing reflector (i.e., a second polarizing reflector 7) and a group of folded optical path modules, so that the entire optical architecture realizes the transmission of virtual image light and real image light using a common optical path by combining the folded optical path and the turning element 6, thereby realizing augmented reality display with good imaging quality.

[0050] The optical module provided in the above embodiment of the present application has two optical propagation paths. For the virtual optical path portion: the display 1 emits a first light ray 001, also known as a virtual light ray. The first light ray 001 is, for example, circularly polarized light. After the first light ray 001 is transmitted to the second polarizing reflector 7, the horizontal polarization component is reflected by the second polarizing reflector 7 and becomes horizontal linear polarized light, which then enters the first imaging element. The first light ray 001 will form a refracted reflection in the first imaging element based on the folded optical path design. In this process, the first light ray 001 is continuously amplified and transmitted, and finally enters the aperture 01. As for the real optical path portion: the second light ray (real light ray) in the external real world will pass through the turning element 6, and after passing through the second polarizing reflector 7, it will become vertical linear polarized light, and then pass through the first imaging element with zero optical power and enter the aperture 01. Through the fusion of the virtual optical path and the real optical path, the optical module provided in the embodiment of the present application forms an AR optical solution.

[0051] The optical module provided in this embodiment of the present application features a folded optical path for the first imaging element located near aperture 01 (e.g., the human eye). For example, the first light beam 001 emitted by the display 1 can achieve image amplification and transmission within a limited space, thereby reducing the overall optical length of the optical module, minimizing the size of the head-mounted display device and making it easier for users to wear.

[0052] In traditional AR near-eye display optical modules, a diffraction optical waveguide solution is usually used. However, this application adopts a folded optical path and a turning element 6. The optical solution provided in the embodiment of this application can improve the display effect of the imaging image, thereby enhancing the user's visual experience.

[0053] In the optical module of the embodiment of the present application, the display 1 is capable of emitting a first light 001 for imaging display, and the second imaging element is arranged in the light emitting direction of the display 1 .

[0054] The first light 001 emitted through the display 1 has, for example, a circular polarization state.

[0055] The display 1 is configured to emit visible light of at least one wavelength band.

[0056] For example, the display 1 can emit visible light of multiple different wavelength bands (such as RGB) to form a color image.

[0057] Optionally, a screen protection glass is provided on the light emitting surface of the display 1. The screen protection glass can be used to protect the display 1.

[0058] In the optical module of the embodiment of the present application, the optical axis of the first imaging element is perpendicular to the central axis of the display 1, that is, the first angle formed between the optical axis of the first imaging element and the central axis of the display 1 is 90°; and the turning element 6 is located between the display 1 and the first imaging element and is inclined at 45° to the central axis of the display 1 and the optical axis of the first imaging element, respectively, that is, the second angle formed between the turning element 6 and the optical axis of the first imaging element is 45°. Of course, it should be noted that this embodiment is only one of the preferred embodiments, and those skilled in the art will recognize that other angle settings can also achieve the technical effects of the present application.

[0059] The optical solution of the present application combines a folded optical path with a turning element 6, wherein some components are transposed by means of the turning element 6, thereby changing the occupied volume in the horizontal direction, and the saved volume can be used for the placement of other components.

[0060] The optical module provided in the above embodiments of the present application introduces a folded optical path into the AR optical system.

[0061] Specifically, the optical module provided by the above embodiment of the present application includes a beam splitter 10 , a first phase retarder 9 and a first polarization reflector 8 , which can be used to form a folded optical path on one side of the near aperture 01 .

[0062] The function of the beam splitter 10 is to split light, so that a portion of the first light 001 is transmitted and another portion of the first light 001 is reflected. In other words, the beam splitter 10 can transmit a portion of the light and reflect another portion of the light. The beam splitter 10 is, for example, a semi-transparent and semi-reflective film.

[0063] It should be noted that the reflectivity and transmittance of the light-splitting element 10 can be flexibly adjusted according to specific needs, and this is not limited in the embodiments of the present application.

[0064] The first phase retarder 9 is, for example, a quarter-wave plate. Of course, the first phase retarder 9 can also be configured as other phase retarder plates such as a half-wave plate as needed.

[0065] The first phase retarder 9 can be used to change the polarization state of light, for example, to convert linearly polarized light into circularly polarized light, or vice versa.

[0066] The first polarizing reflector 8 may be disposed on a side of the first phase retarder 9 away from the beam splitter 10 , so that the first phase retarder 9 is located between the beam splitter 10 and the first polarizing reflector 8 .

[0067] The first polarizing reflector 8 is, for example, a polarizing reflective film, which has a polarization transmission direction, which can also be understood as a transmission axis.

[0068] For example, when the polarization state of the first light 001 emitted by the display 1 is in the same direction as the transmission axis of the first polarizing reflector 8, the first light 001 can be transmitted, and when the polarization state of the first light 001 is in a different direction from the transmission axis, the first light 001 will be reflected.

[0069] Optionally, the spectroscopic element 10, the first phase retarder 9 and the first polarized reflector 8 can be independent optical devices or film structures. If they are film structures, they can be pasted or coated.

[0070] In some examples of the present application, referring to FIG. 1 , the optical power φ2 of the second imaging element is zero.

[0071] That is to say, in the optical module provided in the embodiment of the present application, the optical power of the first imaging element and the second imaging element can both be set to zero.

[0072] For example, the lens assembly in the first imaging element can be a flat plate lens assembly with no optical power, and the deflection element 6 in the second imaging element can be a flat plate element with no optical power. In this way, the real image formed by the second light projected from the outside world after passing through the deflection element 6 with no optical power and the flat plate lens assembly will not be distorted or warped, thereby improving the display quality of the optical module.

[0073] In some examples of the present application, referring to FIG. 1 , the optical module further includes a second phase retarder 5 , and the second phase retarder 5 is located between the second polarization reflector 7 and the lens group.

[0074] According to the optical module provided in the embodiment of the present application, for its virtual optical path, the first light 001 emitted by the display 1 is transmitted to the second polarizing reflector 7, and the horizontal polarization component is reflected by the second polarizing reflector 7 to become horizontal linear polarized light. After passing through the second phase retarder 5, it can become left-handed circularly polarized light, and then can enter the first imaging element. The left-handed circularly polarized light can be refracted in the first imaging element, and finally forms vertical linear polarized light and enters the aperture 01.

[0075] As for the actual optical path: the second light generated by the outside world passes through the turning element 6, passes through the second polarizing reflector 7, becomes vertical linear polarized light, and then passes through the second phase retarder 5 to become right-handed circularly polarized light. The right-handed polarized light can pass through the first imaging element without optical focal length, and is processed into vertical linear polarized light by the internal first phase retarder before entering the aperture 01.

[0076] The optical module provided in the embodiment of the present application can realize an AR optical solution based on the above-mentioned virtual optical path and real optical path.

[0077] In some examples of the present application, referring to FIG1 , the lens group includes at least two lenses cemented to each other to form a cemented lens group, and the cemented lens group forms a flat lens group with zero optical power.

[0078] In the above example, referring to Figure 1 , the first imaging element is located on one side of the near aperture 01 and is an optical structure with a folded optical path. The inclusion of a cemented lens assembly reduces chromatic aberration and improves image quality. Furthermore, the inclusion of a cemented lens assembly simplifies the assembly of the optical module and helps reduce its dimensions along the optical axis.

[0079] As shown in Figure 1, the cemented lens assembly is located on one side of the aperture 01. The two opposing outward-facing surfaces of the cemented lens assembly can be designed as flat surfaces, forming a flat lens assembly with no optical power. When a second light beam from the outside world enters, it can be folded and merged with the first light beam 001, thus forming an AR solution.

[0080] Of course, the lens group in the first imaging element includes but is not limited to the above-mentioned cemented lens group, that is, the lens group can also be composed of at least two separate lenses.

[0081] In some examples of the present application, referring to FIG1 , the lens group includes a first lens 2, a second lens 3, and a third lens 4 glued together in sequence, the combined optical power of the first lens 2, the second lens 3, and the third lens 4 is zero, and the surface of the first lens 2 facing away from the second lens 3 and the surface of the third lens 4 facing away from the second lens 3 have the same surface shape.

[0082] According to the above example, this is a more preferred solution. For the folded optical path composed of three lenses, it is beneficial to reduce the size along the optical axis and improve the imaging quality.

[0083] Of course, for the optical module provided in the embodiments of the present application, the number of lenses in the first imaging element can be two, three, or more. These lenses can be glued together to form an aphotic lens assembly. Furthermore, in the lens assembly, the optical surface closest to the aperture 01 and the optical surface farthest from the aperture 01 have the same surface shape, for example, both are flat or have the same surface shape and are curved toward the same side.

[0084] In some examples of the present application, referring to FIG. 1 , the second phase retarder 5 is located in the first imaging element and is arranged on a surface of the third lens 4 facing away from the second lens 3 .

[0085] According to the above example, there is no need to introduce additional flat support members into the optical path structure to support the second phase retarder 5 , which can simplify the optical structure and reduce production costs.

[0086] In some examples of the present application, referring to FIG. 1 , the second polarizing reflector 7 is disposed on a surface of the turning element 6 close to the display 1 .

[0087] Of course, the second polarizing reflector 7 can also be arranged on the surface of the turning element 6 away from the display 1 , and the setting position can be flexibly selected according to assembly requirements.

[0088] In some examples of the present application, the turning element 6 is a flat plate element, and its optical power is zero.

[0089] The structure of the turning element 6 can be the flat plate structure in the above example.

[0090] However, the turning element 6 is not limited to a flat plate structure, and may also be a free-form surface, a spherical surface, an aspherical surface, or the like.

[0091] In some examples of the present application, referring to FIG1 , the beam splitter 10 is glued between the second lens 3 and the third lens 4 , and the first phase retarder 9 and the first polarizing reflector 8 are stacked and glued between the second lens 3 and the first lens 2 .

[0092] Referring to Figure 1 , the first phase retarder 9 and the first polarizing reflector 8 are stacked. The transmission axis of the first polarizing reflector 8 forms a 45° angle with the fast or slow axis of the first phase retarder 9. Together, the first phase retarder 9 and the first polarizing reflector 8 can resolve and transmit light.

[0093] According to the above example, the first polarizing reflector 8 and the first phase retarder 9 are arranged on the same side of the second lens 3, which facilitates alignment adjustment between the two.

[0094] The first phase retarder 9 is, for example, a quarter wave plate. The first polarization reflector 8 is, for example, a linear polarizer, specifically a linear polarization reflective film.

[0095] Optionally, the optical module further includes a first polarizer 11, which is arranged on the side of the first polarizing reflector 8 away from the first phase retarder 9; the first polarizer 11, the first polarizing reflector 8 and the first phase retarder 9 are stacked in sequence to form a composite film.

[0096] According to the above example, the introduction of the first polarizer 11 can reduce stray light.

[0097] In some examples of the present application, the optical module is applied to an AR device.

[0098] In some examples of the present application, when the optical module is applied to an AR device, it has two light propagation paths, one of which is a virtual light path.

[0099] As for the virtual optical path, referring to FIG1 , the first light ray 001 emitted by the display 1 is transmitted to the second polarizing reflector 7; the second polarizing reflector 7 reflects the horizontal polarization component of the first light ray 001 to form horizontal linear polarized light, which then passes through the second phase retarder 5; the second phase retarder 5 converts the horizontal linear polarized light into left-handed circularly polarized light, which then returns between the beam splitter 10 of the first imaging element and the first polarizing reflector 8, and finally exits through the first lens 2 to the aperture 01.

[0100] Specifically, the first light 001 emitted by the display 1 is transmitted to the second polarizing reflector 7, and the horizontal polarization component is reflected by the second polarizing reflector 7 to become horizontal linear polarized light. After passing through the second phase retarder 5, it becomes left-handed circularly polarized light. It passes through the third lens 4, the beam splitter 10 and the second lens 3 in sequence, and becomes horizontal linear polarized light after passing through the first phase retarder 9. It is then reflected by the first polarizing reflector 8, and becomes left-handed circularly polarized light after passing through the first phase retarder 9. After passing through the third lens 4, it is reflected by the beam splitter 10 to become right-handed circularly polarized light. After passing through the third lens 4 and the first phase retarder 9, it becomes vertical linear polarized light. After passing through the first polarizing reflector 8 and the first lens 2, it enters the aperture 01.

[0101] Regarding the actual optical path: the second light from the outside passes through the turning element 6, and the second polarizing reflector 7 modulates the second light into vertical linear polarized light, and the vertical linear polarized light passes through the second phase retarder 5; the second phase retarder 5 converts the vertical linear polarized light into right-handed circularly polarized light, and the right-handed polarized light is projected into the first imaging element and modulated into vertical linear polarized light by the first phase retarder 9. After passing through the first polarizing reflector 8 and the first lens 2, the vertical linear polarized light is projected onto the aperture 01.

[0102] Specifically, the external second light first passes through the turning element 6 and becomes vertical linear polarized light after passing through the second polarizing reflector 7. Then, it passes through the second phase retarder 5 and becomes right-handed circularly polarized light. It then passes through the third lens 4, the beam splitter 10, and the second lens 3 in the first imaging element in sequence, and then passes through the first phase retarder 9 to become vertical linear polarized light. Finally, it passes through the first polarizing reflector 8 and the first lens 2 and enters the aperture 01.

[0103] The optical architecture provided in the embodiment of the present application realizes an AR module solution in which the virtual image and the display image share the same optical path by folding the optical path in combination with the turning element 6.

[0104] In some examples of the present application, the focal length of the optical module is F, the thickness of the first imaging element along the optical axis is D, and D and F satisfy: 0.3≤D / F≤0.6.

[0105] According to the above example, the optical module provided in the embodiment of the present application can adjust the total system length of the optical module by controlling the thickness of the lens group in the first imaging element.

[0106] In some examples of the present application, referring to FIG1 , the absolute values ​​of the curvature radii of the two surfaces on which the first lens 2 and the second lens 3 are bonded to each other are both C1, and the absolute values ​​of the curvature radii of the two surfaces on which the second lens 3 and the third lens 4 are bonded to each other are both C2, then -0.6≤(C1-C2) / C1≤0.6.

[0107] It should be noted that the absolute values ​​of the curvature radii of the two surfaces where the first lens 2 and the second lens 3 are glued to each other are the same, and the absolute values ​​of the curvature radii of the two surfaces where the second lens 3 and the third lens 4 are glued to each other are also the same. By controlling the curvature radii of the two glued surfaces, it is beneficial to ensure the imaging quality while reducing the total optical length of the optical module.

[0108] In a specific example, referring to FIG1 , the optical module includes a display 1, a first imaging element, and a second imaging element; wherein the optical axis of the first imaging element forms a first angle with the central axis of the display; the second imaging element is located between the display and the first imaging element, and forms a second angle with the optical axis of the first imaging element;

[0109] The first imaging element includes a first lens 2, a second lens 3, and a third lens 4 glued together in sequence. The combined optical power of the first lens 2, the second lens 3, and the third lens 4 is zero. The surface of the first lens 2 facing away from the second lens 3 and the surface of the third lens 4 facing away from the second lens 3 have the same surface shape and are both flat.

[0110] Furthermore, the beam splitter element 10 is glued and disposed between the second lens 3 and the third lens 4. The first phase retarder 9 and the first polarizing reflector 8 are stacked and glued and disposed between the second lens 3 and the first lens 2. The optical module further includes a second phase retarder 5. The second phase retarder 5 is within the first imaging element and is disposed on a surface of the third lens 4 facing away from the second lens 3.

[0111] The second imaging element includes a turning element 6 and a second polarizing reflector 7. The second polarizing reflector 7 is disposed on a surface of the turning element 6 close to the display 1. The turning element 6 is a flat plate element with zero optical power.

[0112] According to the above specific example, the specific optical parameters involved can be shown in Table 1 below.

[0113] Table 1

[0114] In Table 1 above, the surface of each optical device close to the aperture 01 is the front surface, and the surface away from the aperture 01 is the back surface.

[0115] Figures 2, 3, and 4 are the modulation transfer function (MTF) curves of the optical module at 450nm, 540nm, and 610nm, respectively. It can be seen from Figures 2 to 4 that:

[0116] At a spatial frequency of 15lp / mm and a wavelength of 450nm, the MTF value of the optical module is higher than 0.80; at a wavelength of 540nm, the MTF value of the optical module is higher than 0.60; and at a wavelength of 630nm, the MTF value of the optical module is higher than 0.40.

[0117] The optical module provided in the embodiments of the present application can improve imaging quality.

[0118] According to another embodiment of the present application, a head-mounted display device is provided.

[0119] The head-mounted display device includes a housing and the optical module as described above.

[0120] The head-mounted display device includes AR smart glasses or AR smart helmets, etc., which is not limited in the embodiments of the present application.

[0121] The specific implementation of the head-mounted display device of the embodiment of the present application can refer to the above-mentioned embodiments of the optical module, and therefore at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here one by one.

[0122] 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.

[0123] Although some specific embodiments of the present application have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present application. It should be understood by those skilled in the art that the above examples may be modified without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims

1. An optical module, characterized in that: include: Display (1); A first imaging element, the first imaging element comprising a lens group arranged along the same optical axis, and a beam splitter (10), a first phase retarder (9) and a first polarizing reflector (8) arranged in sequence between the optical paths of the lens group, the optical axis of the first imaging element forming a first angle with the central axis of the display (1), and the optical focal length φ1 of the first imaging element being zero; A second imaging element, the second imaging element comprising a turning element (6) and a second polarizing reflector (7) arranged on either side of the turning element (6), the second imaging element being located between the display (1) and the first imaging element and forming a second angle with the optical axis of the first imaging element.

2. The optical module according to claim 1, characterized in that: The optical power φ2 of the second imaging element is zero.

3. The optical module according to claim 1 or 2, characterized in that: The optical module further comprises a second phase retarder (5), wherein the second phase retarder (5) is located between the second polarization reflector (7) and the lens group.

4. The optical module according to claim 3, characterized in that: The lens group includes at least two lenses glued to each other to form a glued lens group, and the glued lens group forms a flat lens group with zero optical power.

5. The optical module according to claim 4, characterized in that: The lens assembly comprises a first lens (2), a second lens (3) and a third lens (4) which are glued together in sequence, the combined optical power of the first lens (2), the second lens (3) and the third lens (4) is zero, and a surface of the first lens (2) facing away from the second lens (3) and a surface of the third lens (4) facing away from the second lens (3) have the same surface shape; The surface of the first lens (2) facing away from the second lens (3) and the surface of the third lens (4) facing away from the second lens (3) are both planes, or arc surfaces and are bent towards the same side.

6. The optical module according to claim 5, characterized in that: The second phase retarder (5) is located in the first imaging element and is arranged on a surface of the third lens (4) facing away from the second lens (3).

7. The optical module according to claim 6, characterized in that: The second polarizing reflector (7) is arranged on a surface of the turning element (6) close to the display (1).

8. The optical module according to claim 1 or 2, characterized in that: The turning element (6) is a flat plate element, and its optical focal length is zero.

9. The optical module according to claim 7, characterized in that: The light splitting element (10) is glued and arranged between the second lens (3) and the third lens (4); The first phase retarder (9) and the first polarization reflector (8) are stacked and glued between the second lens (3) and the first lens (2).

10. The optical module according to claim 9, characterized in that: The optical module further comprises a first polarizer (11), wherein the first polarizer (11) is arranged on a side of the first polarization reflector (8) away from the first phase retarder (9); The first polarizer (11), the first polarization reflector (8) and the first phase retarder (9) are stacked in sequence to form a composite film.

11. The optical module according to claim 9 or 10, characterized in that: The optical module is applied to AR equipment.

12. The optical module according to claim 11, characterized in that: The display (1) emits a first light (001) and transmits it to the second polarized reflector (7); The second polarization reflector (7) reflects the horizontal polarization component of the first light (001) to form horizontal linear polarized light, and the horizontal linear polarized light passes through the second phase retarder (5); The second phase retarder (5) converts the horizontal linear polarized light into left-handed circularly polarized light, and the left-handed circularly polarized light is folded back between the beam splitter (10) of the first imaging element and the first polarizing reflector (8), and finally emitted to the aperture (01) through the first lens (2).

13. The optical module according to claim 12, characterized in that: A second light from the outside passes through the turning element (6), and the second polarization reflector (7) modulates the second light into vertical linear polarized light, and the vertical linear polarized light passes through the second phase retarder (5); The second phase retarder (5) converts the vertical linear polarized light into right-handed circularly polarized light. The right-handed polarized light is projected into the first imaging element and modulated into vertical linear polarized light by the first phase retarder (9). The vertical linear polarized light passes through the first polarizing reflector (8) and the first lens (2) and is then projected onto the aperture (01).

14. The optical module according to claim 7, characterized in that: The focal length of the optical module is F, and the thickness of the first imaging element along the optical axis is D. Then D and F satisfy: 0.3≤D / F≤0.

6.

15. The optical module according to claim 5, characterized in that: The absolute values ​​of the curvature radii of the two surfaces of the first lens (2) and the second lens (3) bonded to each other are both C1, and the absolute values ​​of the curvature radii of the two surfaces of the second lens (3) and the third lens (4) bonded to each other are both C2, then -0.6≤(C1-C2) / C1≤0.

6.

16. A head mounted display device, characterized in that: include: case; as well as An optical module as described in claims 1-15.

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