Optical imaging system, optical microstructure and head-mounted display device

Abstract

The invention provides an optical imaging system, an optical microstructure and a head-mounted display device, the optical imaging system comprises a display screen and a reflective polarizer, and further comprises an optical structure layer, the optical structure layer comprises a plurality of optical microstructures arranged in parallel, and each optical microstructure comprises a first coupling-in structure, a second coupling-in structure, a microcavity and a coupling-out structure; the first coupling-in structure is used for coupling first circularly polarized light from one side of the display screen into the microcavity, the microcavity is used for transmitting the first circularly polarized light to the coupling-out structure, and the coupling-out structure is used for coupling out the first circularly polarized light and emitting the first circularly polarized light to the reflective polarizer; the second coupling-in structure is used for coupling the first circularly polarized light from one side of the reflective polarizer into the microcavity, the microcavity is also used for converting the first circularly polarized light from the second coupling-in structure into second circularly polarized light, and the coupling-out structure is also used for coupling out the second circularly polarized light and emitting the second circularly polarized light to the reflective polarizer. The optical imaging system has the advantages of being low in cost, easy to implement and the like.

Description

Technical Field

[0001] The present application relates to the field of optical technology, and in particular to an optical imaging system, an optical microstructure and a head-mounted display device. Background Art

[0002] With the development of near-eye display technology, head-mounted display devices (HMD) are widely used in work, life, entertainment and other occasions. The most critical component in HMD is the optical imaging system. In order to reduce the volume of the optical imaging system, an ultra-short-throw optical folded light path (pancake) solution can be used to achieve a lightweight design of the imaging system through light reflection and light polarization state change.

[0003] The related technology provides an optical imaging system, which realizes the transflection of light by setting a magnetic response layer (MRL) between a display screen and a reflective polarizer (RF), that is, the forward visible light from the front to the back is transmitted through the MRL, and the reverse visible light from the back to the front is reflected, which can reduce the light intensity loss while realizing the folding of the light path.

[0004] However, the production cost of MRL is high, the application environment requirements are strict, and because it requires the intervention of a strong magnetic field, the strong magnetic field may cause magnetic interference to other electronic components in the HMD. The above reasons have greatly reduced the availability of optical imaging systems based on the MRL solution and made implementation difficult. Based on this, providing a low-cost and easy-to-implement optical imaging system has become a technical problem to be solved. Summary of the invention

[0005] The embodiments of the present application provide an optical imaging system, an optical microstructure and a head-mounted display device. The optical imaging system of the present application realizes the transflection of light by setting an optical structure layer based on a microcavity, and has the advantages of low cost and easy implementation.

[0006] In a first aspect, an optical imaging system is provided, comprising a display screen and a reflective polarizer, and further comprising: an optical structure layer, located between the display screen and the reflective polarizer, the optical structure layer comprising a plurality of optical microstructures arranged in parallel, the optical microstructures comprising a first coupling-in structure, a second coupling-in structure, a microcavity and a coupling-out structure; the first coupling-in structure is used to couple a first circularly polarized light from one side of the display screen into the microcavity, the microcavity is used to transmit the first circularly polarized light to the coupling-out structure, the coupling-out structure is used to couple the first circularly polarized light out and emit it toward the reflective polarizer; the second coupling-in structure is used to couple the first circularly polarized light from one side of the reflective polarizer into the microcavity, the microcavity is also used to convert the first circularly polarized light from the second coupling-in structure into a second circularly polarized light, and the coupling-out structure is also used to couple the second circularly polarized light out and emit it toward the reflective polarizer.

[0007] The optical imaging system provided by the embodiment of the present application includes a display screen, an optical structure layer and a reflective polarizer arranged in sequence, and the optical structure layer includes a plurality of optical microstructures arranged in parallel, and the optical microstructure includes structures such as microcavities, so that the optical microstructure can transmit the first circularly polarized light from one side of the display screen, reflect the first circularly polarized light from one side of the reflective polarizer and convert it into a second circularly polarized light. The optical structure layer is enabled to realize the transflection of light and break the forward and reverse time reversal symmetry of the light field. Compared with the MRL scheme in the related art, the optical structure layer in the present application is a purely passive hardware structure layer that does not require external field drive, has no special requirements for manufacturing materials, is easy to manufacture, has a simple production process, can reuse the existing optical light path design of other parts, and the system assembly steps are the same as normal optical modules. The above reasons make the optical imaging system provided by the embodiment of the present application have the advantages of low cost and easy implementation, which is conducive to the large-scale promotion and application of products.

[0008] In addition, compared with the 50 / 50 beam splitter (semi-transparent and semi-reflective film) solution in the related art, the optical imaging system provided by the embodiment of the present application has no light intensity loss in the subsequent process except for the loss of 50% of the light intensity in the initial polarization stage, that is, the setting of the optical structure layer will not cause additional light intensity loss, which is equivalent to the optical imaging system provided by the embodiment of the present application of the related art having a light intensity increase of nearly four times.

[0009] Optionally, the microcavity in the embodiment of the present application may be a microcavity structure based on a whispering gallery mode (whispering gallery mode), and the first circularly polarized light may be transmitted in the microcavity by total reflection.

[0010] Optionally, the microcavity in the embodiment of the present application may include one microcavity, or may be formed by a plurality of microcavities connected to each other.

[0011] Optionally, the first circularly polarized light in the embodiment of the present application may be left-handed circularly polarized light, and the second circularly polarized light may be right-handed circularly polarized light. Alternatively, the first circularly polarized light may be right-handed circularly polarized light, and the second circularly polarized light may be left-handed circularly polarized light.

[0012] In a possible implementation, the first coupling structure includes a first coupling lens and a first coupling waveguide, the light incident surface of the first coupling lens faces the display screen, and the first coupling lens is connected to the microcavity through the first coupling waveguide.

[0013] The above arrangement is helpful to simplify the structural design of the optical microstructure, reduce the difficulty of processing, and facilitate the coupling of the first circularly polarized light from one side of the display screen into the optical microstructure.

[0014] In a possible implementation, the outcoupling structure includes an outcoupling lens and an outcoupling waveguide, the light-emitting surface of the outcoupling lens faces the reflective polarizer, and the outcoupling lens is connected to the microcavity through the outcoupling waveguide.

[0015] The above arrangement is helpful to simplify the structural design of the optical microstructure and reduce the difficulty of processing. In addition, the transmitted light and the reflected light can share the same outcoupling structure, which can facilitate the transmitted light and the reflected light to be directed to the reflective polarizer.

[0016] In a possible implementation, the second coupling structure includes a second coupling lens and a second coupling waveguide, the light incident surface of the second coupling lens faces the reflective polarizer, and the second coupling lens is connected to the microcavity through the second coupling waveguide.

[0017] The above arrangement is helpful to simplify the structural design of the optical microstructure, reduce the difficulty of processing, and facilitate the coupling of the first circularly polarized light from one side of the reflective polarizer into the optical microstructure.

[0018] In a possible implementation manner, the optical imaging system further includes: an imaging lens, and the optical structure layer is located on one surface of the imaging lens.

[0019] The imaging lens is located between the display screen and the reflective polarizer, and is used to transmit and refract light. The optical imaging system can set different lens types and lens quantities according to actual needs, and improve the imaging quality through the combination of lenses to meet more imaging needs. For example, the imaging clarity can be improved by increasing the number of imaging lenses. The optical structure layer is formed on one of the surfaces of the imaging lens, which is conducive to facilitating the processing of the optical structure layer and reducing the volume and weight of the optical imaging system.

[0020] Optionally, the imaging lens includes one or more of a Fresnel lens, a plano-convex lens, a bi-convex lens, a positive meniscus lens, a plano-concave lens, a bi-concave lens or a negative meniscus lens.

[0021] Optionally, the imaging lens may be an optical resin lens or a glass lens.

[0022] In a possible implementation, the first coupling structure is arranged in one-to-one correspondence with the pixel points of the display screen. Through the above arrangement, it is possible to ensure that the brightness of the picture presented by the display screen is uniform and the image is clear.

[0023] In one possible implementation, the microcavity includes at least one of a microring (eg, a circular ring or an elliptical ring), a microsphere, a microdisk, a microcolumn, a microtube, a microbubble, a microcore ring, a deformable cavity, a Fabry-Perot cavity, or a photonic crystal microcavity.

[0024] In a possible implementation, the optical imaging system also includes a first quarter wave plate located between the optical structure layer and the reflective polarizer, wherein the first quarter wave plate is used to convert the first circularly polarized light from the outcoupling structure into the first polarized light, and convert the second circularly polarized light from the outcoupling structure into the second polarized light, and convert the first polarized light from the reflective polarizer into the first circularly polarized light; and the reflective polarizer is used to reflect the first polarized light from the first quarter wave plate, and transmit the second polarized light from the first quarter wave plate.

[0025] In one possible implementation, the first circularly polarized light is left-handed circularly polarized light, the second circularly polarized light is right-handed circularly polarized light, the first polarized light is S light, and the second polarized light is P light; or, the first circularly polarized light is right-handed circularly polarized light, the second circularly polarized light is left-handed circularly polarized light, the first polarized light is P light, and the second polarized light is S light.

[0026] In a possible implementation, the optical imaging system also includes a first polarizer and a second quarter-wave plate located between the display screen and the optical structure layer, wherein the first polarizer is used to transmit second polarized light; and the second quarter-wave plate is used to convert the second polarized light from the first polarizer into the first circularly polarized light and emit it toward the first coupling structure.

[0027] In a second aspect, an optical microstructure is provided, including a first coupling-in structure, a second coupling-in structure, a microcavity and a coupling-out structure; the first coupling-in structure is used to couple the first circularly polarized light from one side of the display screen into the microcavity, the microcavity is used to transmit the first circularly polarized light to the coupling-out structure, and the coupling-out structure is used to couple the first circularly polarized light out and emit it toward a reflective polarizer; the second coupling-in structure is used to couple the first circularly polarized light from one side of the reflective polarizer into the microcavity, the microcavity is also used to convert the first circularly polarized light from the second coupling-in structure into a second circularly polarized light, and the coupling-out structure is also used to couple the second circularly polarized light out and emit it toward the reflective polarizer.

[0028] In a possible implementation, the first coupling structure includes a first coupling lens and a first coupling waveguide, the light incident surface of the first coupling lens is used to face the display screen, and the first coupling lens is connected to the microcavity through the first coupling waveguide.

[0029] In a possible implementation, the outcoupling structure includes an outcoupling lens and an outcoupling waveguide, the light-emitting surface of the outcoupling lens is used to face the reflective polarizer, and the outcoupling lens is connected to the microcavity through the outcoupling waveguide.

[0030] In a possible implementation, the second coupling structure includes a second coupling lens and a second coupling waveguide, the light incident surface of the second coupling lens is used to face the reflective polarizer, and the second coupling lens is connected to the microcavity through the second coupling waveguide.

[0031] In one possible implementation, the microcavity includes at least one of a microring, a microsphere, a microdisk, a microcolumn, a microtube, a microbubble, a microcore torus, a deformable cavity, a Fabry-Perot cavity, or a photonic crystal microcavity.

[0032] In a possible implementation, the first circularly polarized light is left-handed circularly polarized light, and the second circularly polarized light is right-handed circularly polarized light; or, the first circularly polarized light is right-handed circularly polarized light, and the second circularly polarized light is left-handed circularly polarized light.

[0033] In a third aspect, a head-mounted display device is provided, comprising the optical imaging system provided by any one of the implementations of the first aspect or the optical microstructure provided by any one of the implementations of the second aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a structural schematic diagram of an optical imaging system provided by related technology 1.

[0035] Figure 2 yes Figure 1 Schematic diagram of the imaging principle of the optical imaging system shown.

[0036] Figure 3 It is a structural schematic diagram of the optical imaging system provided by the related technology 2.

[0037] Figure 4 yes Figure 3 Schematic diagram of the imaging principle of the optical imaging system shown.

[0038] Figure 5 This is a schematic diagram of wearing a head-mounted display device provided in an embodiment of the present application.

[0039] Figure 6 It is a schematic diagram of a head-mounted display device applied in a certain gaming scenario.

[0040] Figure 7 yes Figure 6 The diagram shown is a schematic diagram of the interaction of the game scene in the virtual world.

[0041] Figure 8 It is a schematic diagram of the modular structure of the main body.

[0042] Fig. 9 It is a simplified schematic diagram of the split structure of the head-mounted display device.

[0043] Fig.10 It is a schematic diagram of the structure of the optical imaging system provided in an embodiment of the present application.

[0044] Fig.11 It is a schematic diagram of the imaging principle of the optical imaging system provided in an embodiment of the present application.

[0045] Fig.12 It is a top view of the optical structure layer provided in an embodiment of the present application.

[0046] Fig.13 It is a schematic diagram of the structure of the optical microstructure provided in the embodiment of the present application.

[0047] Fig.14 It is a schematic diagram of the propagation of light in an optical microstructure.

[0048] Fig.15 It is a schematic diagram of the optical path loss of the related technology 1 and the solution of this application.

[0049] Reference numerals:

[0050] 100, optical imaging system; 110, display screen; 120, reflective polarizer; 130, first quarter wave plate; 140, first polarizer; 150, second quarter wave plate; 160, third quarter wave plate; 170, second polarizer;

[0051] 200, head mounted display device; 210, main body; 211, housing; 212, control device; 213, eye tracking system; 214, wireless communication module; 220, wearing part;

[0052] 300, optical structure layer; 310, optical microstructure; 311, microcavity; 312, first coupling-in lens; 313, first coupling-in waveguide; 314, coupling-out lens; 315, coupling-out waveguide; 316, second coupling-in lens; 317, second coupling-in waveguide;

[0053] L1, first circularly polarized light; L2, second circularly polarized light. DETAILED DESCRIPTION

[0054] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0055] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installation" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0056] In the description of the present application, it should be understood that the terms "upper", "lower", "side", "front", "rear", etc. indicate orientations or positional relationships based on the installation, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0057] It should also be noted that, in the embodiments of the present application, the same figure mark is used to represent the same component or the same part. For the same parts in the embodiments of the present application, the figure may only mark one of the parts or components as an example. It should be understood that the figure mark also applies to other identical parts or components.

[0058] Head-mounted display (HMD) can use additional information generated by computers to enhance or expand the real-world scene seen by users, greatly changing the way humans interact with computers or the outside world. This type of device combines multiple technologies from different research fields and is quickly applied to entertainment, scientific research, simulation training, telemedicine and other fields.

[0059] HMD based on virtual reality (VR) technology can project digital content into the human eye, making people feel as if they are in a virtual world and achieving an immersive virtual experience. The most critical component in VR equipment is the optical imaging system. Figure 1 1 is a schematic diagram of the structure of an optical imaging system provided by a related art. Figure 1 As shown in the figure, the light emitted by the display screen is refracted by the imaging lens and then enters the pupil of the human eye. The reverse extension line of the light entering the pupil of the human eye converges at a distance to form a virtual image. The image seen by the human eye is the virtual image. The so-called virtual image is the image displayed on the magnified display screen. The angle of the virtual image to the human eye is the field of view (FoV).

[0060] Due to the authenticity requirements of VR devices, the image distance of any object needs to match the imaging angle of the entrance pupil in order to achieve a sufficiently realistic effect. Therefore, the light path in the VR device, while considering the main light beam, the back-tracing of the light from the entrance pupil must be self-consistent with the actual object image points displayed on the display in the actual physical environment. And due to the need to match the angle with the physical depth of the actual object, the light path in the VR device must be physically very long, which will be much greater than the thickness of the device we wear comfortably. So it is similar to Figure 1 and Figure 2 The pancake folded optical path design shown is bound to be used in VR devices.

[0061] Figure 2 yes Figure 1 The imaging principle diagram of the optical imaging system is shown in FIG. Figure 1 and Figure 2 As shown, the optical imaging system includes a display screen, a quarter wave plate (1 / 4) QWP 1, a polarizer (POL) 1, QWP2, a 50 / 50 beam splitter (BS), QWP3, a reflective polarizer (RP), POL2 and an imaging lens.

[0062] The display screen is an image source for displaying images. The display screen may be a microdisplay. For example, it may be a liquid crystal display (LCD), a liquid crystal on silicon (LCoS) display, an organic light-emitting diode (OLED) display, or a micro-light emitting diode (Micro-LED) display. The video light emitted by the display screen may be polarized light or non-polarized light. For example, LCD emits polarized light, and OLED emits non-polarized light.

[0063] The quarter wave plate QWP can also be called a 45-degree phase retarder. The quarter wave plate is made of birefringent materials. When the light vector of linear polarized light is ±45° with the fast axis or slow axis of the wave plate, the light passing through the quarter wave plate is circularly polarized light; conversely, when the circularly polarized light passes through the 1 / 4 wave plate, it becomes linearly polarized light.

[0064] Polarizer POL refers to an optical element that can convert natural light into polarized light. Polarizers can be divided into natural polarizers and artificial polarizers. Natural polarizers are made of crystals. Artificial polarizers can be composite materials laminated by polarizing films, inner protective films, pressure-sensitive adhesive layers and outer protective films. According to the background color of the polarizer, polarizers can be divided into two types: black and white polarizers and color polarizers. According to the application of the polarizer, polarizers can be divided into three types: transmission, transflection and reverse transmission. For example, an absorptive polarizer has the function of shielding and transmitting incident light. For example, longitudinal light can be transmitted and transverse light can be shielded; or, transverse light can be transmitted and longitudinal light can be shielded. In an embodiment of the present application, the polarizer can be a linear polarizer. For example, a metal wire grid type, a multilayer birefringent polymer film type or a MacNeille type, etc. The polarized light transmitted by the linear polarizer is linearly polarized light, and the linear polarized light can be P light or S light. It can be understood that non-polarized light contains both p light and S light. P light refers to light whose polarization direction is parallel to a reference plane. The reference plane is related to the structure of the polarizer. S light refers to light whose polarization direction is perpendicular to the reference plane. Figure 1 and Figure 2 POL1 and POL2 in the circuit transmit P light and block S light.

[0065] The 50 / 50 beam splitter BS is used for transflection in the folded light path. Each transflection will indiscriminately lose half of the light intensity. Its transflection has the characteristics of non-mutual benefit and non-distinction. The 50 / 50 beam splitter can be, for example, a semi-transparent and semi-reflective film, which is a film that allows the incident light to be partially transmitted and partially reflected. For example, a film with a transmittance and a reflectance of 50%. Among them, transmission is the emission phenomenon of the incident light after it passes through an object through refraction. The object to be transmitted is a transparent or translucent body, such as glass or a color filter. If the transparent body is colorless, except for a small amount of light being reflected, most of the light is transmitted through the object. In order to indicate the degree of light transmission of an object, the ratio of the intensity of the incident light after the incident light passes through the film to the intensity of the incident light is usually used to represent the transmittance (transmissivity). The ratio of the intensity of the reflected light to the intensity of the incident light represents the reflectivity (reflectivity).

[0066] The reflective polarizer RP can make the polarizer have the function of selective reflection. For example, the reflective polarizer can include a wire grid polarizer, which is used to transmit light in the P polarization state and reflect light in the S polarization state, that is, transmit P light and reflect S light. Of course, in some cases, the reflective polarizer can also be configured to transmit S light and reflect P light.

[0067] Imaging lens is an optical element made of transparent material. The material of imaging lens can be glass or optical resin. Optical resin is an organic compound that is easy to injection mold or compression mold, not easy to break, has good light transmittance, and has a density of less than 1.6g / cm 3 . Glass lenses can also be called phase-independent imaging lenses. Optical resin lenses can also be called phase-dependent imaging lenses. A phase-independent imaging lens means that when light passes through the device, light with different polarization directions will not introduce a phase difference, or it can be understood that the device does not have a birefringence effect. A phase-dependent imaging lens means that when passing through the device, the polarization characteristics will change, resulting in stray light or ghosting. The device has a birefringence effect, which reduces the imaging clarity. For example, light that should be transmitted linearly polarized (such as P light or S light) becomes transmitted elliptically polarized light, and light that should be transmitted circularly polarized becomes transmitted elliptically polarized light. Typically, the imaging lens used in an optical imaging system is a glass lens. In addition, in order to further improve the imaging clarity, the aberration compensation can be performed by increasing the number of imaging lenses in the optical imaging system to improve the imaging clarity.

[0068] The aforementioned quarter wave plate QWP, polarizer POL, 50 / 50 beam splitter BS and reflective polarizer RP etc. can be formed on the surface of the imaging lens in the form of a coating layer or a film layer. Figure 1 and Figure 2The 50 / 50 beam splitter BS and QWP3 are respectively formed on two opposite surfaces of one of the imaging lenses, while RP and POL2 are stacked on the surface of the other imaging lens facing the human eye.

[0069] like Figure 1 and Figure 2 As shown in the figure, the pancake folded optical path solution is currently used as the main solution in VR devices. The idea of ​​implementing the folded optical path is to use a reflective polarizer RP on one side to transmit P light and reflect S light; and a 50 / 50 beam splitter BS on the other side that does not distinguish between polarization states, thereby achieving the folding of the optical path. How the polarization state of light changes between the two sides requires the embedding of a quarter-wave plate QWP and a polarizer POL, etc. The specific implementation process will not be repeated here.

[0070] It should be noted that because the entrance side is a 50 / 50 beam splitter BS, the refraction and reflection of the VR device light path will cause 1-1 / 2×1 / 2=3 / 4 of the light intensity to be lost. In addition, because the light path needs to be polarized before entering the side, 1 / 2 of the light intensity will be lost at the beginning. Therefore, without considering the actual situation that the efficiency of the film in polarization state conversion is limited, theoretically Figure 1 and Figure 2 The optical imaging system shown will cause at least 1-1 / 2×1 / 2×1 / 2=7 / 8 of the actual entrance pupil light intensity loss.

[0071] In response to the above-mentioned problem of light intensity loss, some solutions based on special optical surfaces of the Faraday effect are proposed in the relevant technology, such as magneto-optic materials into waveguides under external field embedding. The purpose of this solution is to reduce the light field reflected back during transmission, that is, a structure is needed to break the symmetry of the physical field in the two directions of light from front to back and from back to front. The general method is to form a film with a material with magnetic response, which will break the time reversal symmetry of the light field in the forward and reverse directions under a magnetic field of a certain intensity.

[0072] Figure 3 It is a structural schematic diagram of the optical imaging system provided by the related technology 2. Figure 4 yes Figure 3 The imaging principle diagram of the optical imaging system is shown in Figure 1. Figure 3 and Figure 4In the optical imaging system shown, the 50 / 50 beam splitter in the aforementioned embodiment can be replaced by a magnetic response layer (MRL), which is made of magnetic response material and can realize transreflection of light under the action of a magnetic field (B-filed), that is, it can transmit forward light from the front to the back and reflect reverse light from the back to the front, thereby breaking the forward and reverse time reversal symmetry of visible light. Compared with the 50 / 50 beam splitter in the aforementioned embodiment, the MRL will not cause additional light loss, thereby reducing the light intensity loss of the entire optical imaging system.

[0073] However, Figure 3 and Figure 4 Although the optical imaging system shown solves the light intensity loss problem of the pancake folding optical path solution, it also introduces the following three obvious problems:

[0074] (1) High cost. The magnetic material itself is a heavy metal hybrid. Therefore, the MRL film layer must be processed using a complementary metal oxide semiconductor (CMOS) process to form a structure that is optimally coupled to the external field. This has a very high implementation cost.

[0075] (2) The application environment is demanding. Generally, if you want to break the time reversal symmetry in the visible light band, you need a magnetic field of about two Tesla (T). This field strength is beyond the normal range for humans and will respond to local electromagnetic field perturbations.

[0076] (3) It is difficult to integrate magnetic films into actual devices. Since strong electromagnetic fields are required, other electronic components in the HMD will inevitably experience changes in electrical or optical properties under strong fields or perturbations that cannot be isolated. Therefore, it is very difficult to integrate magnetic films in actual applications.

[0077] Based on the above analysis, it can be seen that by transmitting the forward visible light from the front to the back and reflecting the reverse visible light from the back to the front through MRL, the light intensity loss can be reduced while achieving the folding of the optical path. However, the production cost of MRL is high, the requirements for the application environment are strict, and because of the need for the intervention of strong magnetic fields, the strong magnetic field may cause magnetic interference to other electronic components in the HMD. The above reasons have greatly reduced the availability of the optical imaging system based on the MRL solution, and the implementation is difficult. Based on this, providing a low-cost and easy-to-implement optical imaging system has become a technical problem to be solved.

[0078] The embodiment of the present application provides an optical imaging system, which realizes the transflection of light by setting an optical structure layer based on a microcavity. The optical structure layer is a purely passive hardware structure layer that does not require external field drive, so that the optical imaging system provided by the embodiment of the present application has the advantages of low cost and easy implementation. The optical imaging system can be applied to a head-mounted display device. In order to facilitate the understanding of the technical solution of the present application, the head-mounted display device with the optical imaging system provided by the embodiment of the present application is first introduced below, that is, the application background of the optical imaging system is first introduced.

[0079] Please refer to the synchronization Figures 5 to 9 The embodiment of the present application provides a head-mounted display device 200, which refers to a display device for a wearer to wear on his head to provide an immersive experience different from a television, a mobile phone, etc. The head-mounted display device 200 can be a VR device, an augmented reality (AR) display device, or a mixed reality (MR) display device, etc. The head-mounted display device 200 can be in the form of glasses, a helmet, or a mask, etc., but is not limited thereto.

[0080] Figure 5 2 is a schematic diagram of wearing a head mounted display device 200 provided in an embodiment of the present application. Figure 5 As shown, when the head-mounted display device 200 is worn on the user's head, the user's eyes can see the image presented on the display screen of the head-mounted display device 200. When the display screen is transparent, the user's eyes can also see the physical object in front through the display screen. The application scenarios of the head-mounted display device 200 mainly involve various types of interactions with virtual scenes. For example, it can be an application that can recognize human gestures and facial expressions and perform high-bitrate interactions in real time with a certain communication protocol. The head-mounted display device 200 provided in an embodiment of the present application is introduced below in conjunction with a specific application scenario.

[0081] Figure 6 It is a schematic diagram of the head mounted display device 200 applied to a certain game scenario. Figure 7 yes Figure 6 The interactive diagram of the game scene in the virtual world is shown in Figure 1. Figure 6 and Figure 7 The game scene shown can connect two people who are not originally in the same physical space, and respectively input their real-time body movement images, sounds and other information into their respective head-mounted display devices 200, and use it to fully immerse themselves in a new reality that is rebuilt based on the reality structure and in which all the interactors exist, with an extremely high sense of immersion.

[0082] Figure 6 and Figure 7 The figure shows a certain imagined game scene, in which the physical scene and user of the person using the head mounted display device 200 on the left are mapped into the virtual reality perceived by the user on the right, and the actions and person of the user of the head mounted display device 200 on the right are mapped into the real environment perceived by the user on the left with a virtual interactive tool (here, a "bow and arrow"). Such a game scene is constructed, and two users with a physical space span can be in the constructed virtual world with an immersive interactive experience at the same time.

[0083] like Figure 5 As shown, the head mounted display device 200 provided in the embodiment of the present application includes a main body 210 and a wearing part 220. When a user wears the head mounted display device 200, the main body 210 is located in front of the user's eyes to provide a display image for the user's eyes, and the wearing part 220 is used to be fixed on the user's head or ear to achieve reliable wearing of the head mounted display device 200. Figure 5 In the illustration, the wearing portion 220 is in the form of a strap. In other embodiments, the wearing portion 220 can also be in the form of a glasses temple, or in the form of a helmet to hold the main body 210 on the user's head. When the wearing portion 220 is in the form of a helmet, the wearing portion 220 and the main body 210 can also be in an integrated structure.

[0084] Figure 8 2 is a schematic diagram of the modular structure of the main body 210. Figure 8 As shown, the main body 210 includes a housing 211, and various functional modules such as the optical imaging system 100, a control device 212, an eye tracking system 213, and a wireless communication module 214. The housing 211 is used to install the above-mentioned various functional modules. For example, each functional module can be installed inside the housing 211, or be arranged on the housing 211.

[0085] Specifically, the shell 211 is used to provide the outer structure of the main body 210 , and the remaining modules can be accommodated inside the shell 211 and protected by the shell 211 .

[0086] Fig. 9 2 is a simplified schematic diagram of the split structure of the head mounted display device 200. Fig. 9 As shown, the optical imaging system 100 may include components such as a display screen and an imaging lens, which are used to provide a display screen for the user, for example, to realize the display of a virtual screen. The number of optical imaging systems 100 may be two, corresponding to the left eye and right eye of the user respectively. The two optical imaging systems 100 may achieve the purpose of stereoscopic display by means of interlaced display, screen exchange or parallax fusion.

[0087] like Figure 8 , Fig. 9 As shown, the control device 212 is electrically connected to the optical imaging system 100 and is used to control the screen displayed by the optical imaging system 100. The control device 212 may include, for example, functional devices such as a mainboard, a system-on-chip (SoC), and a graphics processing unit (GPU). For example, the mainboard and SoC may be used as the control device 212 to output the GPU-rendered image to the display screens of the left and right optical imaging systems 100. The display screens corresponding to the left and right eyes will simulate the physical depth and light field angle of the actual object points as completely as possible and output the image in accordance with the inversion result of the image distortion caused by the optical system by the SoC. The eye tracking system 213 is also electrically connected to the control device 212 and is used to identify the user's line of sight direction using eye tracking technology. In some embodiments, the control device 212 may include a portion electrically connected to the optical imaging system 100, and a portion electrically connected to the eye tracking system 213, and the two portions are independently arranged inside the housing 211. In other embodiments, the control device 212 may also be a whole, and the present application does not specifically limit the specific implementation of the control device 212.

[0088] The head-mounted display device 200 may also include a wireless communication module 214 disposed inside the housing 211 to achieve wireless communication with other devices. The wireless communication module 214 may include, for example, a wireless fidelity (Wi-Fi) module, a Bluetooth (BT) module, etc., but is not limited thereto. In addition, the head-mounted display device 200 may also include a battery for powering the above-mentioned modules, a camera module for shooting images or videos, a speaker for outputting audio, a microphone for obtaining user voice commands, and one or more of various sensors and other functional modules, which are not limited in this application.

[0089] The embodiments of the present application mainly involve structural improvements to the optical imaging system 100 in the head-mounted display device 200. As a core component in the head-mounted display device 200, the optical imaging system 100 provided in the embodiments of the present application is further introduced below in conjunction with the accompanying drawings.

[0090] Fig.10 Schematic diagram of the structure of the optical imaging system 100 provided in an embodiment of the present application. Fig.11 FIG. 1 is a schematic diagram of the imaging principle of the optical imaging system 100 provided in an embodiment of the present application. Fig.10 and Fig.11As shown, the optical imaging system 100 provided in the embodiment of the present application includes a display screen 110 and a reflective polarizer 120, and an optical structure layer 300 disposed between the display screen 110 and the reflective polarizer 120. The display screen 110 and the reflective polarizer 120 can refer to the aforementioned Figure 1-Figure 4 The optical structure layer 300 is in the form of a film or sheet and is disposed between the above two, with one surface facing the display screen 110 and the other surface facing the reflective polarizer 120.

[0091] Fig.12 FIG. 3 is a top view of the optical structure layer 300 provided in an embodiment of the present application. Fig.12 As shown, the optical structure layer 300 includes a plurality of optical microstructures 310 arranged in parallel, and the plurality of optical microstructures 310 are arranged in parallel on a surface parallel to the display screen 110, thereby forming the optical structure layer 300. In other words, the plurality of optical microstructures 310 are arranged in parallel along the surface of the optical structure layer 300. The plurality of optical microstructures 310 are arranged in an array in a certain manner and at a certain spacing, and a gap may be formed between two adjacent optical microstructures 310, and the gap at any position may be equal.

[0092] Fig.13 3 is a schematic diagram of the structure of the optical microstructure 310 provided in an embodiment of the present application. Fig.14 Schematic diagram of light propagation in the optical microstructure 310. Figure 12-14 As shown, the optical microstructure 310 includes a first coupling-in structure, a second coupling-in structure, a microcavity 311 and an outcoupling structure.

[0093] The first coupling-in structure is used to couple the first circularly polarized light L1 from one side of the display screen 110 into the microcavity 311, and the microcavity 311 is used to transmit the first circularly polarized light L1 to the coupling-out structure, and the coupling-out structure is used to couple the first circularly polarized light L1 out of the microcavity 311 and emit it to the reflective polarizer 120. In other words, the optical microstructure 310 can transmit light from the front to the back (i.e., from the display screen 110 to the user's eyeball), and after the first circularly polarized light L1 enters the optical microstructure 310, it is still emitted as the first circularly polarized light L1, that is, the polarization state (phase) of the light does not change.

[0094] The second coupling structure is used to couple the first circularly polarized light L1 from one side of the reflective polarizer 120 into the microcavity 311, and the microcavity 311 is also used to convert the first circularly polarized light L1 from the second coupling structure into the second circularly polarized light L2, and the coupling-out structure is also used to couple out the second circularly polarized light L2 and emit it toward the reflective polarizer 120. In other words, the optical microstructure 310 can also reflect light from the back to the front (i.e., from the human eye to the display screen 110), and after the first circularly polarized light L1 enters the optical microstructure 310, the first circularly polarized light L1 is converted into the second circularly polarized light L2 and emitted as the second circularly polarized light L2, that is, the polarization state (phase) of the light changes.

[0095] For example, the first circularly polarized light L1 may be Fig.11 The left-handed (L) circularly polarized light in the second circularly polarized light L2 is Fig.11 Alternatively, the first circularly polarized light L1 may be right-handed circularly polarized light, and the second circularly polarized light L2 may be left-handed circularly polarized light.

[0096] The optical imaging system 100 provided in the embodiment of the present application includes a display screen 110, an optical structure layer 300 and a reflective polarizer 120 arranged in sequence, and the optical structure layer 300 includes a plurality of optical microstructures 310 arranged in parallel, and the optical microstructure 310 includes structures such as a microcavity 311, so that the optical microstructure 310 can transmit the first circularly polarized light L1 from one side of the display screen 110, reflect the first circularly polarized light L1 from one side of the reflective polarizer 120 and convert it into a second circularly polarized light L2. The optical structure layer 300 is enabled to realize the transflection of light and break the forward and reverse time reversal symmetry of the light field. Compared with the MRL scheme in the related art 2, the optical structure layer 300 in the present application is a purely passive hardware structure layer that does not require external field drive, has no special requirements for the manufacturing materials, is easy to manufacture, has a simple production process, can reuse the existing optical light path design of other parts, and the system assembly steps are the same as those of normal optical modules. The above reasons make the optical imaging system 100 provided in the embodiment of the present application have the advantages of low cost and easy implementation, which is conducive to the large-scale promotion and application of products.

[0097] Fig.15 It is a schematic diagram of the optical path loss of the related technology 1 and the solution of this application. Fig.15 Part (a) is a schematic diagram of optical path loss in related technology 1. Fig.15 Part (b) of FIG. 1 is a schematic diagram of the optical path loss of the present application scheme, such as Fig.15As shown, compared with the 50 / 50 beam splitter (semi-transparent and semi-reflective film) solution in the related art one, the optical imaging system 100 provided in the embodiment of the present application has no light intensity loss in the subsequent process except for the loss of 50% of the light intensity in the initial polarization stage, that is, the setting of the optical structure layer 300 will not cause additional light intensity loss, which is equivalent to the related art one. The light intensity of the optical imaging system 100 provided in the embodiment of the present application is increased by nearly four times.

[0098] In the embodiment of the present application, the microcavity 311 is a key core component of the optical structure layer 300 to achieve light transmission and reflection. The microcavity 311 can convert the first circularly polarized light L1 from one side of the reflective polarizer 120 into the second circularly polarized light L2. The microcavity 311 in the embodiment of the present application is further introduced below.

[0099] Microcavity, also known as optical microcavity, has attracted much attention and in-depth research due to its huge application potential and scientific significance. Microcavity mainly includes geometric shapes such as microspheres, microcolumns, and microrings. It is a morphology-dependent optical resonant cavity. Among them, the microcavity based on the whispering gallery mode is the most representative. The light waves in the microcavity are totally reflected at the microcavity interface, which will produce a resonance mode called the whispering gallery mode (WGM), which is also the whispering gallery mode. Compared with other optical resonant cavities, microcavities have a high Q value (greater than 10 6 ), low mode volume, small size and easy integration, and has been applied to high-sensitivity biochemical sensing, ultra-low threshold lasers and nonlinear effects.

[0100] Optionally, the microcavity 311 in the embodiment of the present application may be a microcavity structure based on a whispering gallery mode (whispering gallery mode), and the first circularly polarized light L1 may be transmitted in the microcavity 311 by total reflection.

[0101] Optionally, the microcavity 311 in the embodiment of the present application includes a microring (eg Figure 12-14 As shown, for example, a circular ring or an elliptical ring), a microsphere, a microdisk, a microcolumn, a microtube, a microbubble, a microcore ring, a deformable cavity, a Fabry-Perot cavity or at least one of a photonic crystal microcavity.

[0102] Optionally, the microcavity 311 in the embodiment of the present application may include one microcavity, or may be formed by a plurality of microcavities connected to each other.

[0103] In the design process of the microcavity 311, considering that the human eye can only observe the visible light band, it is first necessary to consider that the width and thickness of the microcavity 311 must match the range of the visible light band, and determine the relevant parameters based on the n and k values ​​of the specific materials. Secondly, considering that the visible light may propagate in the microcavity 311 along the clockwise direction or the counterclockwise direction, in order to ensure that the visible light can be smoothly projected to the reflective polarizer 120 instead of being reflected back to the display screen 110, the second step should be to consider coupling the counterclockwise propagation direction of the etched microcavity 311 to the visible light band. For example, a strong continuous wave (continuous wave, CW) laser beam can be input to modulate the forward and reverse directions of the visible light band transmission, that is, to ensure that the visible light propagates along the counterclockwise direction. Fig.14 The light field is transmitted in the counterclockwise direction, thereby achieving the effect of complete transmission of the forward light field and complete reflection of the reverse light field. The specific reference formulas used to modulate the light field are as follows: Formula (1) and Formula (2):

[0104]

[0105]

[0106] Where I is the light intensity, Q is the quality factor of the microcavity 311, n and n' are the refractive index of the linear and nonlinear microcavity 311, respectively, and V mode is the volume of the microcavity 311, η is the coupling coefficient of the microcavity 311, and the rest are generally understood as the central wavelength (λ0), the half-width of the offset wavelength (δλ), the intensity of the modulated laser beam (P in ).

[0107] like Fig.13 and Fig.14 As shown in part (a) of the figure, in the embodiment of the present application, the first coupling structure includes a first coupling lens 312 and a first coupling waveguide 313. The light incident surface of the first coupling lens 312 faces the display screen 110, and the first coupling lens 312 is connected to the microcavity 311 through the first coupling waveguide 313.

[0108] At this time, the first circularly polarized light L1 from the display screen 110 can enter the first coupling waveguide 313 through the light incident surface of the first coupling lens 312, and continue to be coupled into the microcavity 311 through the first coupling waveguide 313, and then be coupled into the microcavity 311. Fig.14 The first circularly polarized light L1 is transmitted counterclockwise as shown in FIG. 1 , and then coupled out through the outcoupling structure and emitted to the reflective polarizer 120 .

[0109] The first coupling lens 312 can be set as large as possible so as to capture as much light as possible to ensure light transmission efficiency. The first coupling lens 312 can be a bowl-shaped structure or a frustum-shaped structure, with a larger side as a light incident surface facing the display screen 110, and a smaller side opposite to the larger side can be connected to the first coupling waveguide 313. The first coupling waveguide 313 can be a rod-shaped structure as a whole, for example, a straight rod-shaped structure, one end of which is connected to the first coupling lens 312, and the other end is connected to the microcavity 311, so as to ensure that the light can form a passage.

[0110] The above configuration is helpful to simplify the structural design of the optical microstructure 310 , reduce the difficulty of processing, and facilitate the coupling of the first circularly polarized light L1 from one side of the display screen 110 into the optical microstructure 310 .

[0111] like Fig.13 and Fig.14 As shown in part (b) of the figure, in the embodiment of the present application, the second coupling structure includes a second coupling lens 316 and a second coupling waveguide 317, the light incident surface of the second coupling lens 316 faces the reflective polarizer 120, and the second coupling lens 316 is connected to the microcavity 311 through the second coupling waveguide 317.

[0112] At this time, the first circularly polarized light L1 from the reflective polarizer 120 can enter the second coupling waveguide 317 through the light incident surface of the second coupling lens 316, and continue to be transmitted through the second coupling waveguide 317 and coupled into the microcavity 311, and then the first circularly polarized light L1 is transmitted through the second coupling waveguide 317 and coupled into the microcavity 311. Fig.14 The first circularly polarized light L1 is transmitted counterclockwise as shown in the figure, during which the first circularly polarized light L1 is converted into the second circularly polarized light L2, and then the second circularly polarized light L2 is coupled out through the outcoupling structure and emitted to the reflective polarizer 120.

[0113] Similarly, the second coupling lens 316 can be set as large as possible so as to capture as much light as possible to ensure the light transmission efficiency. The second coupling lens 316 can be a bowl-shaped structure or a frustum-shaped structure, with a larger side as the light incident surface facing the reflective polarizer 120, and a smaller side opposite to the larger side can be connected to the second coupling waveguide 317. The second coupling waveguide 317 can be a rod-shaped structure as a whole, for example, a straight rod-shaped structure, one end of which is connected to the second coupling lens 316, and the other end is connected to the microcavity 311 to ensure that the light can form a passage.

[0114] The above configuration is helpful to simplify the structural design of the optical microstructure 310 , reduce the difficulty of processing, and facilitate the coupling of the first circularly polarized light L1 from one side of the reflective polarizer 120 into the optical microstructure 310 .

[0115] Optionally, the first coupling waveguide 313 and the second coupling waveguide 317 can form a straight rod-shaped structure as a whole, that is, a part of the straight rod-shaped structure is used as the first coupling waveguide 313, and the other part is used as the second coupling waveguide 317, so as to simplify the processing technology. Alternatively, the first coupling waveguide 313 and the second coupling waveguide 317 can also be connected to the microcavity 311 as two independent rod-shaped structures, which is not limited in the present application.

[0116] like Fig.13 and Fig.14 As shown, in the embodiment of the present application, the outcoupling structure includes an outcoupling lens 314 and an outcoupling waveguide 315 . The light-emitting surface of the outcoupling lens 314 faces the reflective polarizer 120 , and the outcoupling lens 314 is connected to the microcavity 311 through the outcoupling waveguide 315 .

[0117] At this time, the first circularly polarized light L1 in the microcavity 311 can be coupled out through the coupling waveguide 315 and transmitted to the coupling lens 314, and then the first circularly polarized light L1 is emitted to the reflective polarizer 120 through the coupling lens 314. The second circularly polarized light L2 in the microcavity 311 can also be coupled out through the coupling waveguide 315 and transmitted to the coupling lens 314, and then the second circularly polarized light L2 is emitted to the reflective polarizer 120 through the coupling lens 314.

[0118] Similarly, the outcoupling lens 314 may also be in a bowl-shaped structure or a frustum-shaped structure, with a larger side as the light-emitting surface facing the reflective polarizer 120, and a smaller side opposite to the larger side may be connected to the outcoupling waveguide 315. The outcoupling waveguide 315 may be in a rod-shaped structure as a whole, for example, a straight rod-shaped structure, one end of which is connected to the outcoupling lens 314, and the other end of which is connected to the microcavity 311, so as to ensure that the light can form a passage.

[0119] The above arrangement is helpful to simplify the structural design of the optical microstructure 310 and reduce the difficulty of processing. In addition, the transmitted light and the reflected light can share the same outcoupling structure, which can facilitate the transmitted light and the reflected light to be directed to the reflective polarizer 120 .

[0120] Optionally, the first coupling structure may be formed at Fig.13 or Fig.14 The first coupling-in lens 312, the second coupling-in lens 316 and the coupling-out lens 314 can have the same shape and size, and the light incident surface of the second coupling-in lens 316 and the light emitting surface of the coupling-out lens 314 can be located on the same plane. The coupling-out waveguide 315 can be arranged parallel or approximately parallel to the first coupling-in waveguide 313 and / or the second coupling-in waveguide 317.

[0121] Optionally, the optical microstructure 310 can be made into an integrated structure by one or more materials through a process such as one-piece molding. For example, the constituent materials of the optical microstructure 310 include high molecular polymers (such as polyester amide long-chain molecules), silicon dioxide, silicon nitride, lithium niobate, calcium fluoride, barium fluoride, magnesium fluoride, diamond, glass or silicon-based materials, etc.

[0122] like Fig. 9 and Fig.10 As shown, the optical imaging system 100 provided in the embodiment of the present application further includes an imaging lens, and the optical structure layer 300 is located (formed on) one of the surfaces of the imaging lens.

[0123] The imaging lens is located between the display screen 110 and the reflective polarizer 120, and is used to transmit and refract light. The optical imaging system 100 can be set with different lens types and lens quantities according to actual needs, and the imaging quality can be improved by combining lenses to meet more imaging needs. For example, the imaging clarity can be improved by increasing the number of imaging lenses. The optical structure layer 300 is formed on one of the surfaces of the imaging lens, which is conducive to facilitating the processing of the optical structure layer 300 and reducing the volume and weight of the optical imaging system 100.

[0124] Optionally, the imaging lens includes one or more of a Fresnel lens, a plano-convex lens, a bi-convex lens, a positive meniscus lens, a plano-concave lens, a bi-concave lens or a negative meniscus lens.

[0125] Optionally, the imaging lens may be an optical resin lens or a glass lens.

[0126] As a possible implementation, the imaging lens may be a glass lens, the optical structure layer 300 may be composed of materials such as polyesteramide long-chain molecules and silicon dioxide, and the optical structure layer 300 is formed on the surface of the glass lens facing the display screen 110, and the glass lens constitutes the substrate of the optical structure layer 300. In this case, polyesteramide long-chain molecules may be used to make three lenses and silicon dioxide may be used to make the waveguide of the middle layer (i.e., the first coupling waveguide 313, the second coupling waveguide 317, and the coupling waveguide 315) and the microcavity 311 structure, and the optical structure layer 300 may be formed by processing according to the following process steps:

[0127] (1) By performing processes such as spin coating, exposure, and etching on the surface of the glass lens facing the display screen 110, a lens array of the second coupling-in lens 316 and the coupling-out lens 314 is obtained;

[0128] (2) Continue to perform chemical vapor deposition (CVD) growth, exposure, etching and other processes to obtain the waveguides of the middle layer (i.e., the first coupling waveguide 313, the second coupling waveguide 317 and the coupling waveguide 315) and the microcavity 311;

[0129] (3) Repeat the spin coating, exposure and etching processes in step (1) to obtain another layer of lens array (ie, the first coupling lens 312).

[0130] Further, in the embodiment of the present application, the first coupling structure is set in one-to-one correspondence with the pixel points of the display screen 110. That is, at this time, the first coupling lens 312 is set in one-to-one correspondence with the pixel points (main light) of the display screen 110, and the first coupling lens 312 is matched with the screen display unit of the display screen 110. For example, the sizes of the two are basically the same, and the minimum divergence angle and divergence distance of the main light in the actual device need to be considered. Through the above settings, it can be ensured that the brightness of the picture presented by the display screen 110 is uniform and the imaging is clear.

[0131] Furthermore, if Fig.10 and Fig.11 As shown, in the embodiment of the present application, the optical imaging system 100 further includes a first quarter wave plate 130 located between the optical structure layer 300 and the reflective polarizer 120, wherein the first quarter wave plate 130 is used to convert the first circularly polarized light L1 from the outcoupling structure into the first polarized light, and convert the second circularly polarized light L2 from the outcoupling structure into the second polarized light, and convert the first polarized light from the reflective polarizer 120 into the first circularly polarized light L1. The reflective polarizer 120 is used to reflect the first polarized light from the first quarter wave plate 130, and transmit the second polarized light from the first quarter wave plate 130.

[0132] Specifically, after the first circularly polarized light L1 from one side of the display screen 110 enters the optical microstructure 310, it is transmitted out through the coupling-out lens 314. After the first quarter-wave plate 130 receives the first circularly polarized light L1 from the coupling-out lens 314, it converts the first circularly polarized light L1 into the first polarized light and emits it toward the reflective polarizer 120. The reflective polarizer 120 continues to reflect the first polarized light back to the first quarter-wave plate 130. The first quarter-wave plate 130 converts the first polarized light back to the first circularly polarized light L1 and emits it into the optical microstructure 310 through the second coupling-in lens 316. The optical microstructure 310 converts the first circularly polarized light L1 into the second circularly polarized light L2 and transmits it out through the coupling-out lens 314. After the first quarter-wave plate 130 receives the second circularly polarized light L2 from the coupling-out lens 314, it converts the second circularly polarized light L2 into the second polarized light and emits it toward the reflective polarizer 120, and the reflective polarizer 120 transmits it toward the human eye.

[0133] Alternatively, if Fig.11 As shown, in the embodiment of the present application, the first circularly polarized light L1 is left-handed (L) circularly polarized light, the second circularly polarized light L2 is right-handed (R) circularly polarized light, the first polarized light is S light, and the second polarized light is P light.

[0134] At this time, after the left-handed circularly polarized light enters the optical microstructure 310, it is transmitted to the first quarter-wave plate 130 through the coupling-out lens 314. The first quarter-wave plate 130 converts the left-handed circularly polarized light into S light and emits it to the reflective polarizer 120. The reflective polarizer 120 reflects the S light back to the first quarter-wave plate 130. The first quarter-wave plate 130 converts the S light into left-handed circularly polarized light and then emits it into the optical microstructure 310. The optical microstructure 310 converts the left-handed circularly polarized light into right-handed circularly polarized light and then emits it to the first quarter-wave plate 130. The first quarter-wave plate 130 converts the right-handed circularly polarized light into P light and emits it to the reflective polarizer 120. The P light is transmitted from the reflective polarizer 120 to the human eye.

[0135] Optionally, in the embodiment of the present application, the first circularly polarized light L1 may also be right-handed circularly polarized light, in which case the second circularly polarized light L2 is left-handed circularly polarized light, the first polarized light is P light, and the second polarized light is S light.

[0136] Furthermore, if Fig.10 and Fig.11As shown, in an embodiment of the present application, the optical imaging system 100 also includes a first polarizer 140 and a second quarter-wave plate 150 located between the display screen 110 and the optical structure layer 300, wherein the first polarizer 140 is used to transmit the second polarized light (e.g., P light) and shield the first polarized light (e.g., S light); the second quarter-wave plate 150 is used to convert the second polarized light from the first polarizer 140 into a first circularly polarized light L1 (e.g., left-handed circularly polarized light) and direct it toward the first coupling structure of the optical microstructure 310.

[0137] Furthermore, if Fig.10 and Fig.11 As shown, in the embodiment of the present application, the optical imaging system 100 further includes a third quarter wave plate 160 located between the display screen 110 and the first polarizer 140, and a second polarizer 170 located on the human eye side of the reflective polarizer 120. The third quarter wave plate 160, the first polarizer 140 and the second quarter wave plate 150 can be stacked in sequence on the surface of the display screen 110 facing the human eye, the optical structure layer 300 is disposed on the surface of one of the lenses facing the display screen 110, and the first quarter wave plate 130 is disposed on the surface of the lens facing the human eye; the reflective polarizer 120 and the second polarizer 170 are stacked on the surface of the other lens facing the human eye.

[0138] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. An optical imaging system, characterized in that: The invention comprises a display screen (110) and a reflective polarizing plate (120), and further comprises: An optical structure layer (300) is located between the display screen (110) and the reflective polarizer (120), the optical structure layer (300) comprising a plurality of optical microstructures (310) arranged in parallel, the optical microstructures (310) comprising a first coupling-in structure, a second coupling-in structure, a microcavity (311), and an outcoupling structure; The first coupling-in structure is used to couple the first circularly polarized light (L1) from one side of the display screen (110) into the microcavity (311), the microcavity (311) is used to transmit the first circularly polarized light (L1) to the coupling-out structure, and the coupling-out structure is used to couple the first circularly polarized light (L1) out and emit it toward the reflective polarizer (120); The second coupling-in structure is used to couple the first circularly polarized light (L1) from one side of the reflective polarizer (120) into the microcavity (311); the microcavity (311) is also used to convert the first circularly polarized light (L1) from the second coupling-in structure into second circularly polarized light (L2); and the coupling-out structure is also used to couple out the second circularly polarized light (L2) and emit it toward the reflective polarizer (120).

2. The optical imaging system according to claim 1, characterized in that: The first coupling structure comprises a first coupling lens (312) and a first coupling waveguide (313); the light incident surface of the first coupling lens (312) faces the display screen (110); and the first coupling lens (312) is connected to the microcavity (311) via the first coupling waveguide (313).

3. The optical imaging system according to claim 1 or 2, characterized in that: The outcoupling structure comprises an outcoupling lens (314) and an outcoupling waveguide (315); the light-emitting surface of the outcoupling lens (314) faces the reflective polarizer (120); and the outcoupling lens (314) is connected to the microcavity (311) via the outcoupling waveguide (315).

4. The optical imaging system according to any one of claims 1 to 3, characterized in that: The second coupling structure comprises a second coupling lens (316) and a second coupling waveguide (317), wherein the light incident surface of the second coupling lens (316) faces the reflective polarizer (120), and the second coupling lens (316) is connected to the microcavity (311) via the second coupling waveguide (317).

5. The optical imaging system according to any one of claims 1 to 4, characterized in that: The optical imaging system further comprises: An imaging lens, wherein the optical structure layer (300) is located on one of the surfaces of the imaging lens.

6. The optical imaging system according to any one of claims 1 to 5, characterized in that: The first coupling structures are arranged in one-to-one correspondence with the pixels of the display screen (110).

7. The optical imaging system according to any one of claims 1 to 6, characterized in that: The microcavity (311) includes at least one of a microring, a microsphere, a microdisk, a microcolumn, a microtube, a microbubble, a microcore ring, a deformable cavity, a Fabry-Perot cavity or a photonic crystal microcavity.

8. The optical imaging system according to any one of claims 1 to 7, characterized in that: The optical imaging system further comprises a first quarter wave plate (130) located between the optical structure layer (300) and the reflective polarizer (120), wherein: The first quarter wave plate (130) is used to convert the first circularly polarized light (L1) from the outcoupling structure into first polarized light, and to convert the second circularly polarized light (L2) from the outcoupling structure into second polarized light, and to convert the first polarized light from the reflective polarizer (120) into the first circularly polarized light (L1); The reflective polarizer (120) is used to reflect the first polarized light from the first quarter wave plate (130) and transmit the second polarized light from the first quarter wave plate (130).

9. The optical imaging system according to claim 8, characterized in that: The first circularly polarized light (L1) is left-handed circularly polarized light, the second circularly polarized light (L2) is right-handed circularly polarized light, the first polarized light is S light, and the second polarized light is P light; or, The first circularly polarized light (L1) is right-handed circularly polarized light, the second circularly polarized light (L2) is left-handed circularly polarized light, the first polarized light is P light, and the second polarized light is S light.

10. The optical imaging system according to any one of claims 1 to 9, characterized in that: The optical imaging system further comprises a first polarizing plate (140) and a second quarter-wave plate (150) located between the display screen (110) and the optical structure layer (300), wherein: The first polarizer (140) is used to transmit the second polarized light; The second quarter wave plate (150) is used to convert the second polarized light from the first polarizer (140) into the first circularly polarized light (L1), and direct the light toward the first coupling structure.

11. An optical microstructure, characterized in that: It includes a first coupling-in structure, a second coupling-in structure, a microcavity (311) and an outcoupling structure; The first coupling-in structure is used to couple the first circularly polarized light (L1) from one side of the display screen (110) into the microcavity (311), the microcavity (311) is used to transmit the first circularly polarized light (L1) to the coupling-out structure, and the coupling-out structure is used to couple the first circularly polarized light (L1) out and emit it toward the reflective polarizer (120); The second coupling-in structure is used to couple the first circularly polarized light (L1) from one side of the reflective polarizer (120) into the microcavity (311); the microcavity (311) is also used to convert the first circularly polarized light (L1) from the second coupling-in structure into second circularly polarized light (L2); and the coupling-out structure is also used to couple out the second circularly polarized light (L2) and emit it toward the reflective polarizer (120).

12. The optical microstructure according to claim 11, characterized in that: The first coupling structure comprises a first coupling lens (312) and a first coupling waveguide (313); the light incident surface of the first coupling lens (312) is used to face the display screen (110); and the first coupling lens (312) is connected to the microcavity (311) via the first coupling waveguide (313).

13. The optical microstructure according to claim 11 or 12, characterized in that: The outcoupling structure comprises an outcoupling lens (314) and an outcoupling waveguide (315); the light-emitting surface of the outcoupling lens (314) is used to face the reflective polarizer (120); and the outcoupling lens (314) is connected to the microcavity (311) via the outcoupling waveguide (315).

14. The optical microstructure according to any one of claims 11 to 13, characterized in that: The second coupling structure comprises a second coupling lens (316) and a second coupling waveguide (317); the light incident surface of the second coupling lens (316) is used to face the reflective polarizer (120); and the second coupling lens (316) is connected to the microcavity (311) via the second coupling waveguide (317).

15. The optical microstructure according to any one of claims 11 to 14, characterized in that: The microcavity (311) includes at least one of a microring, a microsphere, a microdisk, a microcolumn, a microtube, a microbubble, a microcore ring, a deformable cavity, a Fabry-Perot cavity or a photonic crystal microcavity.

16. The optical microstructure according to any one of claims 11 to 15, characterized in that: The first circularly polarized light (L1) is left-handed circularly polarized light, and the second circularly polarized light (L2) is right-handed circularly polarized light; or, The first circularly polarized light (L1) is right-handed circularly polarized light, and the second circularly polarized light (L2) is left-handed circularly polarized light.

17. A head mounted display device, characterized in that: The optical imaging system comprises the optical imaging system as claimed in any one of claims 1 to 10 or the optical microstructure as claimed in any one of claims 11 to 16.

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