Optical device, head mounted display device and adjustment method of head mounted display device

Abstract

The embodiments of the present application provide an optical device, a head-mounted display device and an adjustment method for the head-mounted display device; the optical waveguide structure includes an optical substrate and a first transparent substrate, and the optical substrate and the first transparent substrate are stacked; the optical substrate has a coupling-in region and an out-coupling region, and the first transparent substrate has a first region and a second region; the first transparent substrate is provided with a first light modulation component in the first region, and the first light modulation component is used to convert the image light projected by the display screen into circularly polarized light; the first transparent substrate is provided with a zoom group in the second region, and the zoom group includes at least one sub-zoom group, and the sub-zoom group includes a first liquid crystal layer and a first metasurface structure, and the first liquid crystal layer is configured to switch between a first orientation and a second orientation to transmit circularly polarized light of different rotation directions to the first metasurface structure; the first metasurface structure forms virtual image planes of at least two focal lengths according to the received circularly polarized light of different rotation directions.

Description

Technical Field

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

[0002] In AR (Augmented Reality) products, such as AR head-mounted display devices, optical waveguides are usually used as core components. The incident light can be transmitted in the optical waveguide based on the principle of total reflection. A diffraction grating is set on the surface of the optical waveguide, which is used to couple the light into the optical waveguide or couple the light out of the optical waveguide for display imaging.

[0003] The essence of AR technology is to achieve interaction between people and the real world through the integration of the virtual world and the real world. When the human eye views an object, the parallax between the left and right eyes can form a three-dimensional image in the human brain, and when viewing images in different positions, the left and right eyeballs can automatically adjust so that the two images of the left and right eyes can be integrated in the human brain.

[0004] In the related art, a single-focus optical design is usually adopted. The image distance of the image presented by the single-focus optical design is constant for the human eye, so that the human eye does not need to adjust the diopter when viewing the image. However, due to the conflict between the convergence rotation of the human eye and the constant diopter adjustment (i.e., convergence conflict), the human eye is prone to eye fatigue and dizziness when continuously viewing dynamic 3D images. Summary of the invention

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

[0006] In a first aspect, the present application provides an optical device. The optical device comprises an optical substrate and a first transparent substrate, wherein the optical substrate and the first transparent substrate are stacked;

[0007] The optical base has an incoupling region and an outcoupling region, and the first transparent substrate has a first region corresponding to the incoupling region and a second region corresponding to the outcoupling region;

[0008] A first light modulating component is disposed on a side of the first transparent substrate facing away from the optical base and in the first region, wherein the first light modulating component is configured to convert image light projected by a target display screen into circularly polarized light;

[0009] A zoom group is disposed on a side of the first transparent substrate away from the optical base and in the second region, the zoom group includes at least one sub-zoom group, the sub-zoom group includes a first liquid crystal layer and a first metasurface structure, and the first metasurface structure is disposed away from the first transparent substrate relative to the first liquid crystal layer;

[0010] The first liquid crystal layer is configured to switch between a first orientation and a second orientation to transmit circularly polarized light of different rotation directions to the first metasurface structure; the first metasurface structure forms virtual image planes of at least two focal lengths according to the received circularly polarized light of different rotation directions.

[0011] Optionally, the first light modulation component includes a second liquid crystal layer, and the second liquid crystal layer is configured to convert the linearly polarized light into circularly polarized light.

[0012] Optionally, the first light modulation component further includes a third liquid crystal layer, the second liquid crystal layer and the third liquid crystal layer are stacked, and the third liquid crystal layer is arranged away from the first transparent substrate relative to the second liquid crystal layer;

[0013] The third liquid crystal layer is configured to convert image light projected by the target display screen into linearly polarized light.

[0014] Optionally, the first liquid crystal layer is connected to an electronic control component, so that the first liquid crystal layer can be switched between a first orientation and a second orientation;

[0015] In the first orientation, the first liquid crystal layer can reflect circularly polarized light of a first rotation direction and can transmit circularly polarized light of a second rotation direction;

[0016] In the second orientation, the first liquid crystal layer is capable of reflecting circularly polarized light of the second hand direction and transmitting circularly polarized light of the first hand direction.

[0017] Optionally, the first liquid crystal layer is a cholesteric liquid crystal layer.

[0018] Optionally, the first metasurface structure is a metalens.

[0019] Optionally, the first metasurface structure includes a plurality of structural units, and each structural unit is provided with a region for distinguishing between focusing circularly polarized light of the first rotation direction or focusing circularly polarized light of the second rotation direction.

[0020] Optionally, the zoom group includes three sub-zoom groups, and the first liquid crystal layer in each sub-zoom group is individually connected to an electric control component to form virtual image planes with six focal lengths.

[0021] Optionally, the optical device further comprises a second transparent substrate, the second transparent substrate is stacked with the optical base, and the first transparent substrate and the second transparent substrate are respectively located on two opposite sides of the optical base;

[0022] The second transparent substrate has a third area corresponding to the outcoupling area;

[0023] A second light modulation component and a zoom compensation group are arranged on a side of the third area away from the optical base, and the zoom compensation group is arranged close to the second transparent substrate relative to the second light modulation component;

[0024] The second light modulation component is configured to convert ambient light into circularly polarized light;

[0025] The zoom compensation group is configured to compensate for a zoom parameter of the zoom group.

[0026] Optionally, the zoom compensation group includes at least one sub-zoom compensation group, the sub-zoom compensation group includes a fourth liquid crystal layer and a second metasurface structure, and the second metasurface structure is arranged relative to the fourth liquid crystal layer and close to the second transparent substrate;

[0027] The fourth liquid crystal layer is configured to switch between a first orientation and a second orientation to project circularly polarized light of different rotation directions onto a second metasurface structure; the second metasurface structure receives the circularly polarized light and transmits the circularly polarized light to the zoom group, wherein the optical focal length of the second metasurface structure is opposite to the optical focal length of the first metasurface structure to compensate for the zoom parameter of the zoom group.

[0028] Optionally, the second light modulation component comprises a fifth liquid crystal layer and a sixth liquid crystal layer, the fifth liquid crystal layer and the sixth liquid crystal layer are stacked, and the fifth liquid crystal layer is arranged away from the second transparent substrate relative to the sixth liquid crystal layer;

[0029] The fifth liquid crystal layer is configured to convert ambient light into linearly polarized light;

[0030] The sixth liquid crystal layer is configured to convert the linearly polarized light into circularly polarized light.

[0031] Optionally, the zoom compensation group includes three groups of sub-zoom compensation groups, the fourth liquid crystal layer in each sub-zoom compensation group is individually connected to an electric control component, and the optical focal length of the second metasurface structure in each sub-zoom compensation group is opposite to the optical focal length of the corresponding first metasurface structure.

[0032] In a second aspect, a head mounted display device is provided, wherein the head mounted display device comprises the optical device as described in the first aspect.

[0033] In a third aspect, a method for adjusting a head mounted display device is provided. The method for adjusting the head mounted display device comprises:

[0034] Obtain human eye information data;

[0035] Determine the human eye focusing position information according to the human eye information data;

[0036] The orientation of the first liquid crystal layer is adjusted according to the human eye focus position information, and the first metasurface structure forms virtual image planes of at least two focal lengths according to the received circularly polarized light of different rotation directions, so that the optical device can achieve zoom.

[0037] According to an embodiment of the present application, an optical device is provided. The optical device includes an optical base and a first transparent substrate, wherein a zoom group is arranged in a second region of the first transparent substrate corresponding to the outcoupling region, wherein a first liquid crystal layer in the zoom group can switch between a first orientation and a second orientation, and circularly polarized light of different rotation directions generated by the first liquid crystal layer is focused differently at the human eye through a first metasurface structure, so that convergence conflict is not likely to occur when a viewer views a three-dimensional image, thereby improving user experience.

[0038] 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

[0039] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the specification and, together with the description, serve to explain the principles of the specification.

[0040] Figure 1 Shown is a schematic diagram of the structure of an optical device provided in an embodiment of the present application.

[0041] Figure 2 Shown is a light path structure diagram of the image light projected from the target display screen through the zoom group.

[0042] Figure 3 Shown is a light path structure diagram of ambient light passing through the zoom compensation group and the zoom group.

[0043] Figure 4 Shown is a schematic diagram of the electrical control principle of the zoom group.

[0044] Figure 5 Shown is a schematic diagram of the structure of a head mounted display device provided in an embodiment of the present application.

[0045] Description of reference numerals:

[0046] 1. Optical substrate; 10. Optical machine module; 100. Optical device;

[0047] 2. first transparent substrate; 21. first light modulating component; 211. second liquid crystal layer; 212. third liquid crystal layer; 22. zoom group; 221. sub-zoom group; 222. first liquid crystal layer; 223. first metasurface structure;

[0048] 3. second transparent substrate; 31. second light modulating component; 311. fifth liquid crystal layer; 312. sixth liquid crystal layer; 32. zoom compensation group; 321. sub-zoom compensation group; 322. fourth liquid crystal layer; 323. second metasurface structure;

[0049] 4. Head-mounted display device; 41. Spectacle frame; 42. Eye tracker. DETAILED DESCRIPTION

[0050] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application.

[0051] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present application, its application, or uses.

[0052] 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.

[0053] 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.

[0054] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0055] The present application provides an optical device 100. Figure 1-Figure 4 The optical device 100 includes: an optical substrate 1 and a first transparent substrate 2, and the optical substrate 1 and the first transparent substrate 2 are stacked.

[0056] The optical base 1 has a coupling-in region and a coupling-out region, and the first transparent substrate 2 has a first region corresponding to the coupling-in region and a second region corresponding to the coupling-out region.

[0057] A first light modulation component 21 is disposed on a side of the first transparent substrate 2 facing away from the optical base 1 and in the first region. The first light modulation component 21 is configured to convert image light projected by a target display screen into circularly polarized light.

[0058] A zoom group 22 is arranged on the side of the first transparent substrate 2 away from the optical base 1 and in the second area, the zoom group 22 includes at least one sub-zoom group 221, the sub-zoom group 221 includes a first liquid crystal layer 222 and a first meta-surface structure 223, and the first meta-surface structure 223 is arranged away from the first transparent substrate 2 relative to the first liquid crystal layer 222.

[0059] The first liquid crystal layer 222 is configured to switch between a first orientation and a second orientation to transmit circularly polarized light of different rotation directions to the first metasurface structure 223; the first metasurface structure 223 forms virtual image planes of at least two focal lengths according to the received circularly polarized light of different rotation directions.

[0060] In the above-mentioned embodiment, the optical device 100 includes an optical base 1 and a first transparent substrate 2, wherein the first transparent substrate 2 and the optical base 1 are stacked, and the first transparent substrate 2 plays a role in protecting the optical base 1, for example, the first transparent substrate 2 plays a role in dustproofing and waterproofing the optical base 1. In a specific embodiment, the optical base 1 and the first transparent substrate 2 can be fixed by bonding, for example, they can be fixed by optical glue.

[0061] In the above embodiment, the first transparent substrate 2 is arranged close to the human eye side and the light source side, wherein the human eye side and the light source side are located on the same side. For example, an optical machine module 10 is arranged on the light source side, and the image light emitted by the optical machine module 10 passes through the first transparent substrate 2 and is then coupled into the optical base 1 through the coupling region of the optical base 1.

[0062] The optical substrate 1 has a coupling-in region and a coupling-out region, wherein a coupling-in grating is arranged in the coupling-in region, and a coupling-out grating is arranged in the coupling-out region, wherein the coupling-in grating couples the light passing through the first region of the first transparent substrate 2 into the optical substrate 1, and the light coupled into the optical substrate 1 is totally reflected in the optical substrate 1, and can eventually be coupled out from the coupling-out grating of the optical substrate 1, and finally emitted through the second region of the first transparent substrate 2, and finally enter the human eye.

[0063] In the above-mentioned embodiment, the optical device is provided for zooming based on circularly polarized light, so it is necessary to make the light coupled into the optical substrate 1 circularly polarized light. That is, the optical device modulates the circularly polarized light, rather than modulating the parameters of other light. For example, zooming is not achieved by modulating the wavelength of the light (when the wavelength of the light is modulated, it is easy to expand the dispersion and affect the imaging quality, which is a situation that users do not want to see), or zooming is achieved by modulating the phase of the light (modulating the phase of the light is easy to produce wavefront aberration).

[0064] Specifically, a first light modulator 21 is arranged on the side of the first transparent substrate 2 facing away from the optical base 1 and in the first area, wherein the first light modulator 21 can convert the image light projected by the display screen into circularly polarized light. Specifically, the light emitted by the display screen and the external ambient light can be converted into circularly polarized light. However, the external ambient light enters the optical base 1, and since the transmission condition of the external ambient light does not meet the total reflection condition, the external ambient light will not be transmitted in the optical base 1. Therefore, in this embodiment, the light transmitted from the first area of ​​the first transparent substrate 2 to the optical base 1, ultimately only the image light projected by the optical machine module 10 can be transmitted to the outcoupling area of ​​the optical base 1, and emitted through the zoom group 22 of the first transparent substrate 2.

[0065] The circularly polarized light converted by the first light modulation component 21 is coupled into the optical base 1 from the coupling-in region of the optical base 1. The converted circularly polarized light is totally reflected in the optical base 1, and then coupled out from the coupling-out region of the optical base 1. Finally, it is emitted through the second region of the first transparent substrate 2 and finally enters the human eye.

[0066] In the above-mentioned embodiment, a zoom group 22 is arranged on the side of the first transparent substrate 2 away from the optical base 1 and in the second area. The zoom group 22 is used to zoom the circularly polarized light, so that the image projected by the display screen can be presented in a virtual image plane of various focal lengths, so as to avoid convergence conflicts when the human eye views through an optical device, and avoid the phenomenon of eye fatigue and dizziness when the human eye needs to readjust the focus and convergence during the switching process between reality and virtuality.

[0067] Specifically, a zoom group 22 is arranged on the side of the first transparent substrate 2 away from the optical base 1 and in the second area, wherein the zoom group 22 includes at least one sub-zoom group 221. The focal length of each sub-zoom group 221 can be adjusted according to the type of circularly polarized light transmitted to the first metasurface structure 223, so that the zoom group 22 has different focal lengths, and then the image projected by the target display screen is zoomed, so that the optical device can present the picture in the image in the virtual image plane corresponding to a variety of focal lengths as needed, that is, a multi-focal plane display is formed. In this embodiment, at least two focal planes can be realized to avoid convergence conflicts when the human eye views through the optical device, and to avoid eye fatigue and dizziness when the human eye needs to readjust the focus and adjust the convergence during the switching between reality and virtuality.

[0068] Specifically, the sub-zoom group 221 includes a first liquid crystal layer 222 and a first metasurface structure 223, wherein the first liquid crystal layer 222 is attached to the surface of the second region of the first transparent substrate 2, and the first metasurface structure 223 is combined with the first liquid crystal layer 222. For example, the first metasurface structure 223 and the first liquid crystal layer 222 are bonded together by optical glue. In this embodiment, the structure of the sub-zoom group 221 is limited, and the weight of the optical device can be reduced. The optical device is applied to the head-mounted display device 4, and the lightweight design of the head-mounted display device 4 is realized.

[0069] The first liquid crystal layer 222 can switch between a first orientation and a second orientation, and the first metasurface structure 223 performs zooming based on circularly polarized light. The first metasurface structure 223 generates different wavefront modulations for the circularly polarized light of the first rotation direction and the circularly polarized light of the second rotation direction, which is specifically manifested in different focal lengths for the circularly polarized light of the first rotation direction and the circularly polarized light of the second rotation direction.

[0070] For example, when the first liquid crystal layer 222 allows the transmission of circularly polarized light of the second rotation direction, the first metasurface structure 223 receives the circularly polarized light of the second rotation direction, and the circularly polarized light of the second rotation direction is focused at the first position through the first metasurface structure 223; when the first metasurface structure 223 allows the transmission of circularly polarized light of the first rotation direction, the first metasurface structure 223 receives the circularly polarized light of the first rotation direction, and the circularly polarized light of the first rotation direction is focused at the second position through the first metasurface structure 223; in this embodiment, the first liquid crystal layer 222 is actively controlled so that the first liquid crystal layer 222 can selectively allow the transmission of circularly polarized light of the first rotation direction, or allow the transmission of circularly polarized light of the second rotation direction.

[0071] That is, when the first liquid crystal layer 222 allows the circularly polarized light of the second hand direction to be transmitted, after the circularly polarized light of the second hand direction passes through the first metasurface structure 223, the first metasurface structure 223 can focus the circularly polarized light of the second hand direction (focus at the first position) to form a first focal length;

[0072] When the first liquid crystal layer 222 allows the circularly polarized light of the first hand direction to pass through, after the circularly polarized light of the first hand direction passes through the first metasurface structure 223, the first metasurface structure 223 focuses the circularly polarized light of the first hand direction (focuses at a second position) to form a second focal length.

[0073] In the process of continuously switching the state of the first liquid crystal layer 222, the first metasurface structure 223 receives circularly polarized light of different rotation directions to focus the circularly polarized light of different rotation directions at different positions, so that the focal length of the sub-zoom group 221 is continuously changed, so that the picture in the image is presented in the virtual image plane corresponding to the two focal lengths (for example, the circularly polarized light of the first rotation direction corresponds to the virtual image plane of the second focal length, and the circularly polarized light of the second rotation direction corresponds to the virtual image plane of the first focal length); optionally, when the zoom group 22 includes multiple sub-zoom layers, the zoom group 22 realizes different zoom ranges (that is, it can zoom at different focal planes), and the picture in the image is presented in the virtual image plane corresponding to multiple focal lengths, that is, a multi-focal plane display is formed.

[0074] For example, it can also be understood that: the first metasurface structure 223 is a liquid crystal layer structure having different focusing effects on circularly polarized light of the first rotation direction and circularly polarized light of the second rotation direction, and the first metasurface structure 223 forms virtual image planes of different focal lengths according to the received circularly polarized light of different rotation directions, for example, the first liquid crystal layer 222 allows the circularly polarized light of the second rotation direction to pass through, wherein the first metasurface structure 223 receives the circularly polarized light of the second rotation direction to focus the circularly polarized light of the second rotation direction at the first position to form a virtual image plane. At this time, the state of the first liquid crystal layer 222 is actively switched, so that the first liquid crystal layer 222 allows the circularly polarized light of the first rotation direction to pass through, wherein the first metasurface structure 223 receives the circularly polarized light of the first rotation direction to focus the circularly polarized light of the first rotation direction at the second position to form a virtual image plane, wherein the virtual image plane at the first position and the virtual image plane at the second position have different focal lengths, forming virtual image planes of different focal lengths. For example, the microstructure of the structural unit within the first metasurface structure 223 is passively controlled to prepare the first metasurface structure 223 so that the first metasurface structure 223 itself has different regions. In the first metasurface structure 223, the metasurface structures in different regions have different focusing effects on the circularly polarized light of the first rotation direction and the circularly polarized light of the second rotation direction.

[0075] The first metasurface structure 223 is located on the light-emitting side of the first liquid crystal layer 222. The first metasurface structure 223 can produce different focusing effects for circularly polarized light of different rotation directions, so as to perform focused imaging at the human eye, improve convergence conflict, and eliminate the discomfort of the viewer.

[0076] Therefore, in the above embodiment, an optical device 100 is provided. The optical device 100 includes an optical base 1 and a first transparent substrate 2, wherein a zoom group 22 is arranged in a second region of the first transparent substrate 2 corresponding to the outcoupling region, wherein a first liquid crystal layer 222 in the zoom group 22 can switch between a first orientation and a second orientation, and a first metasurface structure 223 produces different focusing effects at the human eye on circularly polarized light of different rotation directions generated by the first liquid crystal layer 222, so that convergence conflicts are not likely to occur when a viewer views a three-dimensional image, thereby ensuring the imaging quality. On the other hand, the zoom group 22 includes the first liquid crystal layer 222 and the first metasurface structure 223, which reduces the weight of the optical device, and the optical device is applied to a head-mounted display device 4, realizing a lightweight head-mounted display device 4.

[0077] In an optional embodiment, the optical machine module 10 includes a display screen and a collimated light path, which can parallelize the light projected by the display screen into the optical device.

[0078] In one embodiment, the first light modulation component 21 includes a second liquid crystal layer 211 , and the second liquid crystal layer 211 is configured to convert the linearly polarized light into circularly polarized light.

[0079] In one embodiment, the first light modulation component further includes a third liquid crystal layer 212, the second liquid crystal layer 211 and the third liquid crystal layer 212 are stacked, and the third liquid crystal layer 212 is arranged away from the first transparent substrate 2 relative to the second liquid crystal layer 211; the third liquid crystal layer 212 is configured to convert the image light projected by the target display screen into linearly polarized light.

[0080] It should be emphasized that when the image light emitted by the target display screen is linearly polarized light, at this time, the first light modulation component 21 may only include the second liquid crystal layer 211 .

[0081] In the above embodiment, the first light modulation component 21 includes a second liquid crystal layer 211 and a third liquid crystal layer 212. The first light modulation component 21 is composed of a liquid crystal layer, and the light emitted by the display screen is modulated by the liquid crystal layer. Compared with the prior art, in which the light is modulated by a wafer, the liquid crystal layer can be attached to the first transparent substrate 2 in this embodiment to reduce the weight of the optical device.

[0082] Specifically, the second liquid crystal layer 211 and the third liquid crystal layer 212 are stacked in the first area of ​​the first transparent substrate 2. For example, the second liquid crystal layer 211 is attached to the surface of the first area of ​​the first transparent substrate 2 facing away from the optical base 1, and the third liquid crystal layer 212 is attached to the second liquid crystal layer 211. That is, the third liquid crystal layer 212 is arranged closer to the optical machine module 10 relative to the second liquid crystal layer 211.

[0083] The third liquid crystal layer 212 can convert the image light projected by the target display screen into linear polarized light, that is, the third liquid crystal layer 212 can achieve the effect of a polarizer. The second liquid crystal layer 211 can convert linear polarized light into circular polarized light, and the second liquid crystal layer 211 can achieve the effect of a quarter wave plate. The third liquid crystal layer 212 converts the light emitted from the display screen into linear polarized light after passing through the third liquid crystal layer 212, and then into circular polarized light after passing through the second liquid crystal layer 211, and finally couples into the optical substrate 1 through the coupling region of the optical substrate 1, and is transmitted in the optical substrate 1.

[0084] It should be noted that the second liquid crystal layer 211 and the third liquid crystal layer 212 have different internal structures, and the liquid crystal layer can have different modulation effects on light by adjusting the pitch (Pitch) of the liquid crystal molecules in the liquid crystal layer. It is well known to those skilled in the art that the liquid crystal layer has different modulation effects on light (for example, adjusting the polarization state of light) by adjusting the pitch (Pitch) of the liquid crystal molecules in the liquid crystal layer, and the internal structures of the second liquid crystal layer 211 and the third liquid crystal layer 212 are not described in detail here.

[0085] In this embodiment, the structure of the first light modulation component 21 is limited, the overall weight of the optical device is reduced, and the optical device is applied to the head-mounted display device 4 to achieve a lightweight design of the head-mounted display device 4.

[0086] In one embodiment, the first liquid crystal layer 222 is connected to an electronic control component so that the first liquid crystal layer 222 switches between the first orientation and the second orientation;

[0087] In the first orientation, the first liquid crystal layer 222 can reflect circularly polarized light of a first rotation direction and can transmit circularly polarized light of a second rotation direction;

[0088] In the second orientation, the first liquid crystal layer 222 can reflect circularly polarized light of the second rotation direction and transmit circularly polarized light of the first rotation direction.

[0089] In the above embodiment, the first liquid crystal layer 222 is connected to the electric control component, and the first liquid crystal layer 222 can be switched between the first orientation and the second orientation by, for example, controlling the voltage / electric field of the first liquid crystal layer 222, so as to allow the transmission of circularly polarized light of different rotation directions. For example, when a voltage is applied to the first liquid crystal layer 222, the first liquid crystal layer 222 is in the first orientation; when no voltage is applied to the first liquid crystal layer 222, the first liquid crystal layer 222 is in the second orientation.

[0090] For example, when the first liquid crystal layer 222 is in a first orientation, the first liquid crystal layer 222 reflects circularly polarized light of a first rotation direction and transmits circularly polarized light of a second rotation direction. For example, when the first liquid crystal layer 222 is in a right-handed state, the first liquid crystal layer 222 can reflect right-handed circularly polarized light and transmit left-handed circularly polarized light.

[0091] When the first liquid crystal layer 222 is in the second orientation, the first liquid crystal layer 222 reflects the second circularly polarized light and transmits the first circularly polarized light. For example, when the first liquid crystal layer 222 is in the left-handed state, the first liquid crystal layer 222 can reflect the left-handed circularly polarized light and transmit the right-handed circularly polarized light.

[0092] In this embodiment, a zoom group 22 is arranged on the surface of the second area of ​​the first transparent substrate 2 away from the optical base 1. The polarization state conversion of the light in the zoom group 22 is realized by the liquid crystal layer. On the one hand, the image projected by the optical machine module 10 is zoomed by the zoom group 22 so that the image can be presented in a virtual image plane of a variety of focal lengths, thereby further improving the convergence conflict and eliminating the discomfort of the viewer. On the other hand, the polarization state conversion of the light in the zoom group 22 is realized by the liquid crystal layer. The zoom group 22 can be attached to the first transparent substrate 2, which reduces the weight of the optical device. The optical device is applied to the head-mounted display device 4 to realize the lightweight setting of the head-mounted display device 4.

[0093] In one embodiment, the first liquid crystal layer 222 is a cholesteric liquid crystal layer.

[0094] In the above specific embodiment, the first liquid crystal layer 222 is a cholesteric liquid crystal layer, that is, the first liquid crystal layer 222 has cholesteric liquid crystal molecules with a helical structure, and the cholesteric liquid crystal molecules with a helical structure are controlled by voltage / electric field to allow circularly polarized light of different rotation directions to pass through.

[0095] In one embodiment, the first metasurface structure 223 is a metalens.

[0096] Specifically, the structures of different areas of the same structural unit in the metalens produce different wavefront modulations for left-handed circularly polarized light and right-handed circularly polarized light. Specifically, this manifests as different focal lengths for left-handed circularly polarized light and right-handed circularly polarized light, that is, the metalens produces different focusing effects for circularly polarized light of different rotation directions.

[0097] In one embodiment, the first metasurface structure 223 includes a plurality of structural units, each of which is provided with a region for focusing the circularly polarized light of the first rotation direction or the circularly polarized light of the second rotation direction.

[0098] Specifically, by setting the structural unit (microstructure) in the first metasurface structure 223, modulation of circularly polarized light can be achieved. For example, the structural unit in the metalens is controlled, and each structural unit is only about 100 nanometers, and each 100 nanometers or so will distinguish the area that focuses specifically on left-handed circularly polarized light or right-handed circularly polarized light. In a specific embodiment, the structural unit includes two areas, and the structures of the two areas are different, one of which is specifically focused on right-handed circularly polarized light, and the other area is specifically focused on left-handed circularly polarized light.

[0099] It should be noted that modulating the imaging performance of the meta-lens, such as chromatic aberration, aberration, polarization control, and wavelength control, is a well-known method for those skilled in the art. However, the present application embodiment prepares the structural unit structure inside the meta-lens to achieve polarization modulation. Compared with modulating the wavelength of light (which is prone to amplifying the dispersion effect) or modulating the phase of light (which is prone to wavefront aberration), the present application embodiment achieves better multi-focal imaging by modulating polarization.

[0100] In one embodiment, referring to Figure 2 and Figure 3 The zoom group 22 includes three sub-zoom groups 221, and the first liquid crystal layer 222 in each sub-zoom group 221 is individually connected to an electric control component to form virtual image planes with six focal lengths.

[0101] In the above embodiment, the zoom group 22 includes three sub-zoom groups 221. The three sub-zoom groups 221 include a first sub-zoom group, a second sub-zoom group and a third sub-zoom group. The first sub-zoom group, the second sub-zoom group and the third sub-zoom group are stacked and arranged in the second area of ​​the first transparent substrate 2. Therefore, in this embodiment, six focal planes are realized by the three sub-zoom groups 221, so that the zoom group 22 can switch in six different focal length ranges to achieve near eye to infinity.

[0102] For example, the first sub-zoom group includes a first liquid crystal layer 222 and a first metasurface structure 223. The second sub-zoom group includes a first liquid crystal layer 222 and a first metasurface structure 223. The third sub-zoom group includes a first liquid crystal layer 222 and a first metasurface structure 223.

[0103] The first metasurface structure 223 in the first sub-zoom group, the first metasurface structure 223 in the second sub-zoom group 221, and the first metasurface structure 223 in the third sub-zoom group 221 must not be of the same design so as to focus on the same focal length position; and they must not focus on the same focal position after zooming during the zooming process.

[0104] For example, for the first sub-zoom group, the circularly polarized light transmitted in the optical substrate 1 first passes through the first liquid crystal layer 222 of the first sub-zoom group 221. For example, at this time, the first liquid crystal layer 222 is in the first orientation, and the first liquid crystal layer 222 allows the circularly polarized light with the opposite rotation direction to be transmitted. After the circularly polarized light is transmitted, the first metasurface structure 223 focuses the circularly polarized light to the first focal plane according to the type of circularly polarized light it receives; if the first liquid crystal layer 222 is in the second orientation at this time, the first liquid crystal layer 222 allows the circularly polarized light with the opposite rotation direction to be transmitted. After the circularly polarized light is transmitted, the first metasurface structure 223 focuses the circularly polarized light to the second focal plane according to the type of circularly polarized light it receives. Therefore, in this embodiment, the first sub-zoom group 221 has two different focal lengths for circularly polarized light with different rotation directions, forming two focal planes. The focal lengths corresponding to the two focal planes are completely different.

[0105] Similarly, for the second sub-zoom group, the circularly polarized light transmitted from the first sub-zoom group passes through the first liquid crystal layer 222 of the second sub-zoom group, and the orientation of the first liquid crystal layer 222 in the second sub-zoom group 221 is controlled, so that one of the circularly polarized light rotation directions can be selectively allowed to pass through. After the circularly polarized light passes through, the first metasurface structure 223 in the second sub-zoom group 221 focuses the circularly polarized light to a third focal plane according to the type of circularly polarized light it receives. If the orientation of the first liquid crystal layer 222 in the second sub-zoom group 221 is changed at this time, the first metasurface structure 223 in the second sub-zoom group focuses the circularly polarized light to a fourth focal plane according to the type of circularly polarized light it receives.

[0106] Similarly, for the third sub-zoom group, the circularly polarized light transmitted from the second sub-zoom group passes through the first liquid crystal layer 222 of the third sub-zoom group, and the orientation of the first liquid crystal layer 222 in the third sub-zoom group is controlled, so that one of the circularly polarized light rotation directions can be selectively allowed to pass through. After the circularly polarized light passes through, the first metasurface structure 223 in the third sub-zoom group focuses the circularly polarized light to the fifth focal plane according to the type of circularly polarized light it receives. If the orientation of the first liquid crystal layer 222 in the third sub-zoom group is changed at this time, the first metasurface structure 223 in the third sub-zoom group 221 focuses the circularly polarized light to the sixth focal plane according to the type of circularly polarized light it receives.

[0107] For example, the structures in the structural units of the first metasurface structure 223 in the first sub-zoom group, the first metasurface structure 223 in the second sub-zoom group 221, and the first metasurface structure 223 in the third sub-zoom group 221 can be changed to passively control the first metasurface structure 223. For example, the first metasurface structures 223 in the three sub-zoom groups 221 are prepared differently, so that the first metasurface structures 223 in the three sub-zoom groups 221 have different focal lengths for circularly polarized light of different rotation directions.

[0108] In this embodiment, the zoom group 22 includes three sub-zoom groups 221, each sub-zoom group 221 includes a first liquid crystal layer 222 and a first metasurface structure 223, and voltages are applied to the three first liquid crystal layers 222 respectively, so that the zoom group 22 can achieve zooming of six focal planes (for example, a zoom range of 0-2.5D can be achieved), thereby expanding the zoom range.

[0109] It should be noted that the present embodiment does not limit the number of sub-zoom groups 221 included in the zoom group 22 , as long as the real-time zooming of the zoom group 22 can be achieved by processing the sub-zoom groups 221 .

[0110] In one embodiment, referring to Figure 1 , the optical device further comprises a second transparent substrate 3, the second transparent substrate 3 is stacked with the optical base 1, and the first transparent substrate 2 and the second transparent substrate 3 are respectively located on two opposite sides of the optical base 1;

[0111] The second transparent substrate 3 has a third area corresponding to the outcoupling area;

[0112] A second light modulation component 31 and a zoom compensation group 32 are disposed on a side of the third region away from the optical base 1. The zoom compensation group 32 is disposed close to the second transparent substrate 3 relative to the second light modulation component 31.

[0113] The second light modulation component 31 is configured to convert ambient light into circularly polarized light;

[0114] The zoom compensation group 32 is configured to compensate for the zoom parameters of the zoom group 22 .

[0115] In this embodiment, the optical device further includes a second transparent substrate 3, wherein the second transparent substrate 3 and the first transparent substrate 2 are arranged on two opposite sides of the optical base 1. For example, the second transparent substrate 3 is arranged on the side away from the human eye, and the second transparent substrate 3 and the optical base 1 can be fixed by bonding, for example, by optical glue.

[0116] Generally, the ambient light on the side of the optical base 1 away from the human eye will enter the human eye through the second transparent substrate 3, the optical base 1 and the zoom group 22, that is, while the zoom group 22 zooms the circularly polarized light transmitted by the optical base 1, the ambient light on the side away from the human eye will also be zoomed accordingly, so that the light transmitted in the optical base 1 cannot be clearly presented to the human eye. For example, the composition of the ambient light is relatively complex, and more than half of the light in the ambient light is circularly polarized light. After the circularly polarized light in the ambient light passes through the optical base 1 and the zoom group 22, the circularly polarized light in the ambient light will have focal length compensation. This situation is not ideal and will cause the human eye to see the picture unclearly. That is, in this embodiment, it is only desired to zoom the projected image light in the optical machine module 10, and it is not desired to zoom the ambient light.

[0117] Therefore, in the above embodiment, the second transparent substrate 3 has a third area corresponding to the outcoupling area, and the second light modulation component 31 and the zoom compensation group 32 are arranged on the side of the third area away from the optical base 1 .

[0118] Specifically, the ambient light is converted into circularly polarized light by the second light modulating component 31. The zoom compensation group 32 compensates the zoom parameter of the zoom group 22. For example, if the zoom group 22 realizes 1D diopter adjustment, the zoom compensation group 32 needs to realize -D diopter adjustment to offset the influence of the zoom group 22 on the ambient light.

[0119] For example, ambient light is modulated by the second light modulator 31 to become circularly polarized light, and the circularly polarized light passes through the zoom compensation group 32, the optical base 1 and the zoom group 22 to offset the influence of the optical device on the ambient light, thereby improving the clarity of the image viewed by the human eye.

[0120] In one embodiment, referring to Figure 1 and Figure 3 As shown, the zoom compensation group 32 includes at least one sub-zoom compensation group 321, and the sub-zoom compensation group 321 includes a fourth liquid crystal layer 322 and a second metasurface structure 323, and the second metasurface structure 323 is arranged relative to the fourth liquid crystal layer 322 and close to the second transparent substrate 3;

[0121] The fourth liquid crystal layer 322 is configured to switch between a first orientation and a second orientation to project circularly polarized light of different rotation directions onto the second metasurface structure 323; the second metasurface structure 323 receives the circularly polarized light and transmits the circularly polarized light to the zoom group 22, wherein the optical focal length of the second metasurface structure 323 is opposite to the optical focal length of the first metasurface structure 223 to compensate for the zoom parameter of the zoom group 22.

[0122] In the above embodiment, the zoom compensation group 32 includes a fourth liquid crystal layer 322 and a second metasurface structure 323 , wherein the second metasurface structure 323 can be adhered to the surface of the second transparent substrate 3 , and the fourth liquid crystal layer 322 can be attached to the second metasurface structure 323 .

[0123] In the above embodiment, the fourth liquid crystal layer 322 can switch between the first orientation and the second orientation. The function of the fourth liquid crystal layer 322 is the same as that of the first liquid crystal layer 222 discussed above, which is to selectively allow circularly polarized light of one rotation direction to pass through. Therefore, in this embodiment, the fourth liquid crystal layer 322 is not described in detail.

[0124] In the above embodiment, after the second metasurface structure 323 receives circularly polarized light of different rotation directions, it transmits the corresponding circularly polarized light through the optical substrate 1, the first liquid crystal layer 222 and the first metasurface structure 223. Since the optical focal lengths of the second metasurface structure 323 and the first metasurface structure 223 are opposite, the circularly polarized light of different rotation directions passes through the second metasurface structure 323 and the first metasurface structure 223 in sequence, which is equivalent to passing through flat glass. The human eye, at its focusing position, can see the virtual image magnified and projected by the zoom group 22 and the scene in the environment, thereby realizing AR display.

[0125] Reference Figure 3 As shown, the zoom compensation group 32 includes three sub-zoom compensation groups 321, specifically, a zoom compensation group located on the left (including a fourth liquid crystal layer 322 and a second meta-surface structure 323), a zoom compensation group located in the middle (including a fourth liquid crystal layer 322 and a second meta-surface structure 323), and a zoom compensation group located on the right (including a fourth liquid crystal layer 322 and a second meta-surface structure 323).

[0126] The zoom group 22 includes three sub-zoom groups 221, specifically, a zoom group on the left (including a first liquid crystal layer 222 and a first meta-surface structure 223), a zoom group in the middle (including a first liquid crystal layer 222 and a first meta-surface structure 223), and a zoom group on the right (including a first liquid crystal layer 222 and a first meta-surface structure 223).

[0127] The optical focal length of the second metasurface structure 323 in the zoom compensation group on the left is opposite to the optical focal length of the first metasurface structure 223 in the zoom group on the left; the optical focal length of the second metasurface structure 323 in the zoom compensation group in the middle is opposite to the optical focal length of the first metasurface structure 223 in the zoom group in the middle; the optical focal length of the second metasurface structure 323 in the zoom compensation group on the right is opposite to the optical focal length of the first metasurface structure 223 in the zoom group on the right.

[0128] Therefore, in the above embodiment, in a specific embodiment, the zoom group on the side of the optical base 1 close to the human eye can achieve 5D diopter adjustment, and the zoom compensation group on the outer side of the optical base can achieve -5D diopter adjustment to offset the impact of the zoom system on ambient light.

[0129] In one embodiment, the second optical adjustment component includes a fifth liquid crystal layer 311 and a sixth liquid crystal layer 312, the fifth liquid crystal layer 311 and the sixth liquid crystal layer 312 are stacked, and the fifth liquid crystal layer 311 is arranged away from the second transparent substrate 3 relative to the sixth liquid crystal layer 312;

[0130] The fifth liquid crystal layer 311 is configured to convert ambient light into linearly polarized light;

[0131] The sixth liquid crystal layer 312 is configured to convert the linearly polarized light into circularly polarized light.

[0132] In the above embodiment, the second light modulating component 31 is composed of a liquid crystal layer, and the ambient light is modulated by the liquid crystal layer. Compared with the prior art, in which light is modulated by a wafer, the liquid crystal layer can be attached to the second transparent substrate 3 in this embodiment to reduce the weight of the optical device.

[0133] Specifically, the fifth liquid crystal layer 311 and the sixth liquid crystal layer 312 are stacked and disposed in the third region of the second transparent substrate 3 .

[0134] The fifth liquid crystal layer 311 can convert ambient light into linearly polarized light, that is, the fifth liquid crystal layer 311 can achieve the effect of a polarizer, and the sixth liquid crystal layer 312 can convert linearly polarized light into circularly polarized light, that is, the sixth liquid crystal layer 312 can achieve the effect of a quarter wave plate.

[0135] It should be noted that the fifth liquid crystal layer 311 and the sixth liquid crystal layer 312 have different internal structures, and the pitch of the liquid crystal molecules in the liquid crystal layer can be adjusted to make the liquid crystal layer have different modulation effects on light. It is well known to those skilled in the art that the pitch of the liquid crystal molecules in the liquid crystal layer can be adjusted to make the liquid crystal layer have different modulation effects on light (for example, adjusting the polarization state of light), and the internal structures of the fifth liquid crystal layer 311 and the sixth liquid crystal layer 312 are not described in detail here.

[0136] In this embodiment, the structure of the second light modulation component 31 is limited, the overall weight of the optical device is reduced, and the optical device is applied to the head-mounted display device 4 to achieve a lightweight design of the head-mounted display device 4.

[0137] In one embodiment, the zoom compensation group 32 includes three groups of sub-zoom compensation groups 321, the fourth liquid crystal layer 322 in each sub-zoom compensation group 321 is individually connected to an electric control component, and the optical focal length of the second metasurface structure 323 in each sub-zoom compensation group 321 is opposite to the optical focal length of the corresponding first metasurface structure 223.

[0138] In the above embodiment, the zoom compensation group 32 and the zoom group 22 are mirror-symmetrical with respect to the optical base 1 in structure.

[0139] In this embodiment, the zoom compensation group 32 includes three sub-zoom compensation groups 321. The three sub-zoom compensation groups 321 include a first sub-zoom compensation group, a second sub-zoom compensation group and a third sub-zoom compensation group. The first sub-zoom compensation group, the second sub-zoom compensation group and the third sub-zoom compensation group are stacked and arranged in the third area of ​​the second transparent substrate 3. The first sub-zoom compensation group corresponds to the first sub-zoom group in position, the second sub-zoom compensation group corresponds to the second sub-zoom group in position, and the third sub-zoom compensation group corresponds to the third sub-zoom group in position. The zoom compensation group 32 and the zoom group 22 have opposite optical focal lengths.

[0140] For example, the first sub-zoom compensation group includes a fourth liquid crystal layer 322 and a second metasurface structure 323, wherein the second metasurface structure 323 corresponds to the first metasurface structure 223 in the first sub-zoom group, and the two have opposite optical focal lengths. For example, the first metasurface structure 223 corresponds to two focal lengths, and the second metasurface structure 323 corresponds to two focal lengths. The focal lengths of the two metasurface structures are opposite, so that the optical focal lengths of the first metasurface structure 223 and the second metasurface structure 323 are opposite.

[0141] The second sub-zoom compensation group includes a fourth liquid crystal layer 322 and a second metasurface structure 323 , wherein the second metasurface structure 323 corresponds to the first metasurface structure 223 in the second sub-zoom group, and the optical powers of the two are opposite.

[0142] The third sub-zoom compensation group includes a fourth liquid crystal layer 322 and a second metasurface structure 323 , wherein the second metasurface structure 323 corresponds to the first metasurface structure 223 in the third sub-zoom group, and the optical powers of the two are opposite.

[0143] In this embodiment, the structures of the zoom compensation group 32 and the zoom group 22 are limited so that the zoom group 22 on the side of the optical base 1 close to the human eye can achieve positive refractive power (for example, 5D optical focal length) adjustment, and the zoom compensation group 32 on the outer side of the optical base 1 can achieve -5D refractive power adjustment to offset the influence of the optical device on ambient light.

[0144] According to the optical device 100 provided in the embodiment of the present application, the optical substrate 1 therein may be a waveguide substrate, or may be other substrates or optical devices, and the present application does not impose any limitation on this.

[0145] In a second aspect, a head mounted display device 4 is provided. The head mounted display device 4 comprises:

[0146] a housing; and

[0147] As described in the first aspect, the optical device is arranged on the housing.

[0148] In some examples of the present application, the head mounted device may be augmented reality smart glasses, etc. The specific implementation of the head mounted device in the embodiment of the present application may refer to the above-mentioned embodiments of the optical device, which will not be described in detail here.

[0149] In a third aspect, a method for adjusting a head mounted display device 4 is provided. The method for adjusting includes:

[0150] S01: Acquire human eye information data;

[0151] S02: Determine the human eye focus position information according to the human eye information data;

[0152] S03: adjusting the orientation of the first liquid crystal layer 222 according to the human eye focus position information, so that the optical device can achieve zooming.

[0153] In the above-mentioned embodiment, for example, the head mounted display device 4 may be augmented reality smart glasses.

[0154] The smart glasses include two frames 41 , and one of the optical devices described above is arranged on each frame 41 .

[0155] In the above step S01, the method of obtaining the human eye information data includes, for example, setting two eye trackers 42 on the smart glasses. When the human eye looks at different objects, the distance between the two pupils and the size of the pupils will change. By setting two eye trackers 42 on the smart glasses (the eye trackers 42 are set next to the nose pads), the distance between the two pupils, the size of the pupils, and the direction in which the eyes are looking can be identified. That is, the human eye information data includes the distance between the two pupils, the size of the pupils, and the direction in which the eyes are looking.

[0156] Of course, there are many ways to obtain human eye information data, including but not limited to the above description.

[0157] In the above step S02, the human eye information data obtained by the eye tracker 42 is sent to the built-in processing unit for calculation to obtain the current eye focus position, and the position information is converted into a control signal, thereby determining the position information of the human eye focus.

[0158] In the above step S03, after obtaining the position information of the human eye focus, the focal length of the zoom group 22 can be adjusted according to the virtual image plane corresponding to the position information of the human eye focus, thereby bringing a more realistic immersive visual experience to the viewer.

[0159] Specifically, the focusing position information of the human eye is transmitted to the electronic control component, and the electronic control component applies voltage to the first liquid crystal layer 222, which can selectively allow circularly polarized light of one rotation direction to pass through. Then, the first metasurface structure 223 projects the circularly polarized light onto a virtual image plane according to the type of the circularly polarized light, thereby realizing the zoom of the optical device.

[0160] 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.

[0161] Although some specific embodiments of the present invention have been described in detail by way of example, it will be appreciated 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 invention. It will be appreciated by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.

Claims

1. An optical device, characterized in that: It comprises an optical substrate (1) and a first transparent substrate (2), wherein the optical substrate (1) and the first transparent substrate (2) are stacked; The optical base (1) has a coupling-in region and a coupling-out region, and the first transparent substrate (2) has a first region corresponding to the coupling-in region, and a second region corresponding to the coupling-out region; A first light modulation component (21) is arranged on a side of the first transparent substrate (2) facing away from the optical base (1) and in the first region, and the first light modulation component (21) is configured to be able to convert image light projected by a target display screen into circularly polarized light; A zoom group (22) is arranged on a side of the first transparent substrate (2) facing away from the optical base (1) and in the second region, the zoom group (22) comprising at least one sub-zoom group (221), the sub-zoom group (221) comprising a first liquid crystal layer (222) and a first metasurface structure (223), the first metasurface structure (223) being arranged away from the first transparent substrate (2) relative to the first liquid crystal layer (222); The first liquid crystal layer (222) is configured to switch between a first orientation and a second orientation to transmit circularly polarized light of different rotation directions to the first metasurface structure (223); the first metasurface structure (223) forms virtual image planes of at least two focal lengths according to the received circularly polarized light of different rotation directions.

2. The optical device according to claim 1, characterized in that The first light modulation component (21) comprises a second liquid crystal layer (211), wherein the second liquid crystal layer (211) is configured to convert linearly polarized light into circularly polarized light.

3. The optical device according to claim 2, characterized in that: The first light modulation component further comprises a third liquid crystal layer (212), the second liquid crystal layer (211) and the third liquid crystal layer (212) are stacked, and the third liquid crystal layer (212) is arranged away from the first transparent substrate (2) relative to the second liquid crystal layer (211); The third liquid crystal layer (212) is configured to convert the image light projected by the target display screen into linearly polarized light.

4. The optical device according to claim 1, characterized in that: The first liquid crystal layer (222) is connected to an electric control component, so that the first liquid crystal layer (222) can be switched between a first orientation and a second orientation; In the first orientation, the first liquid crystal layer (222) is capable of reflecting circularly polarized light of a first rotation direction and transmitting circularly polarized light of a second rotation direction; In the second orientation, the first liquid crystal layer (222) is capable of reflecting circularly polarized light of the second rotation direction and transmitting circularly polarized light of the first rotation direction.

5. The optical device according to claim 1, characterized in that: The first liquid crystal layer (222) is a cholesteric liquid crystal layer.

6. The optical device according to claim 1, characterized in that: The first metasurface structure (223) is a metalens.

7. The optical device according to claim 1 or 6, characterized in that: The first metasurface structure includes a plurality of structural units, and each structural unit is provided with a region for focusing circularly polarized light of a first rotation direction or circularly polarized light of a second rotation direction.

8. The optical device according to claim 1, characterized in that: The zoom group (22) comprises three groups of sub-zoom groups (221), and the first liquid crystal layer (222) in each group of the sub-zoom groups (221) is individually connected to an electric control component to form virtual image planes of six focal lengths.

9. The optical device according to claim 1, characterized in that: The optical device further comprises a second transparent substrate (3), the second transparent substrate (3) being stacked with the optical base (1), and the first transparent substrate (2) and the second transparent substrate (3) being respectively located on two opposite sides of the optical base (1); The second transparent substrate (3) has a third area corresponding to the outcoupling area; A second light modulation component (31) and a zoom compensation group (32) are arranged on a side of the third region away from the optical base (1); the zoom compensation group (32) is arranged relative to the second light modulation component (31) and close to the second transparent substrate (3); The second light modulation component (31) is configured to convert ambient light into circularly polarized light; The zoom compensation group (32) is configured to compensate for the zoom parameters of the zoom group (22).

10. The optical device according to claim 9, characterized in that: The zoom compensation group (32) comprises at least one sub-zoom compensation group (321), the sub-zoom compensation group (321) comprising a fourth liquid crystal layer (322) and a second metasurface structure (323), the second metasurface structure (323) being arranged relative to the fourth liquid crystal layer (322) and close to the second transparent substrate (3); The fourth liquid crystal layer (322) is configured to switch between a first orientation and a second orientation to project circularly polarized light of different rotation directions onto the second metasurface structure (323); the second metasurface structure (323) receives the circularly polarized light and transmits the circularly polarized light to the zoom group (22), wherein the optical focal length of the second metasurface structure (323) is opposite to the optical focal length of the first metasurface structure (223) to compensate for the zoom parameter of the zoom group (22).

11. The optical device according to claim 10, characterized in that: The second light modulation component (31) comprises a fifth liquid crystal layer (311) and a sixth liquid crystal layer (312), the fifth liquid crystal layer (311) and the sixth liquid crystal layer (312) being stacked, and the fifth liquid crystal layer (311) being arranged away from the second transparent substrate (3) relative to the sixth liquid crystal layer (312); The fifth liquid crystal layer (311) is configured to convert ambient light into linearly polarized light; The sixth liquid crystal layer (312) is configured to convert the linearly polarized light into circularly polarized light.

12. The optical device according to claim 10, characterized in that: The zoom compensation group (32) comprises three groups of sub-zoom compensation groups (321), the fourth liquid crystal layer (322) in each group of sub-zoom compensation groups (321) is individually connected to an electric control component, and the optical focal length of the second metasurface structure (323) in each group of sub-zoom compensation groups (321) is opposite to the optical focal length of the first metasurface structure (223) corresponding thereto.

13. A head mounted display device, characterized in that: include: An optical device as claimed in any one of claims 1 to 12.

14. A method for adjusting a head mounted display device as claimed in claim 13, characterized in that: The adjustment method comprises: Obtain human eye information data; Determine the human eye focusing position information according to the human eye information data; The orientation of the first liquid crystal layer (222) is adjusted according to the human eye focus position information, and the first metasurface structure (223) forms virtual image planes of at least two focal lengths according to the received circularly polarized light of different rotation directions, so that the optical device can achieve zooming.

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