A near-eye display system based on multi-focal achromatic superlenses

Abstract

The application discloses a near-eye display system based on a multi-focus achromatic super lens, and relates to the near-eye display field.The near-eye display system comprises an image source, a polarization modulation unit and a multi-focus achromatic super lens.The image source is a transparent micro-nano display screen array, and parallel light beams are formed through a collimating structure to be focused by the multi-focus achromatic super lens.The polarization modulation unit modulates the polarization state of original light emitted by the image source to obtain polarized light with left-handed circular polarization state.When the multi-focus achromatic super lens receives single-color left-handed circular polarized light of m primary colors, one focal length contained in single-color light of different primary colors can be focused on the same imaging plane to realize achromatic function.The multi-focus achromatic super lens is used to replace an optical lens which is large in volume and heavy in weight, so that the near-eye display system has the advantages of small volume, light weight and compact specification, and the wearing comfort can be improved.

Description

Technical Field

[0001] This invention relates to the field of near-eye displays, and in particular to a near-eye display system based on a multifocal achromatic superlens. Background Technology

[0002] Near-eye display technology is commonly used in Augmented Reality (AR) and Virtual Reality (VR) applications to project digital information or virtual images directly into the user's field of vision. With the increasing maturity and popularity of AR and VR technologies, near-eye display devices have become a key component of these technologies. They provide users with personalized and customized experiences, combining the virtual and real worlds to expand people's perception and interaction methods. Near-eye display technology has already been applied in multiple fields, including entertainment, education, healthcare, and industry. With continuous technological advancements, more new application scenarios are expected to emerge, driving the development of related industries. However, the optical lenses used in near-eye display systems suffer from large size and weight, which reduces the wearing comfort of users of head-mounted display devices with such systems. Furthermore, traditional lenses in near-eye displays may cause color aberration, resulting in color deviations between the displayed image and the real scene, leading to color shifts or unevenness in the image, reducing the realism of the visual experience, causing visual discomfort, and leading to eye fatigue and discomfort. Summary of the Invention

[0003] In view of the aforementioned deficiencies of the prior art, the technical problem to be solved by the present invention is to provide a near-eye display system based on a multifocal achromatic superlens. The aim is to use the optimized optical design of the multifocal achromatic superlens to converge incident light of different wavelengths to a single focal point, thereby providing more accurate and realistic color reproduction. Furthermore, the superlens is small in size and lightweight, which helps to achieve a lighter and more compact design for near-eye display devices, improving wearing comfort and portability.

[0004] To achieve the above objectives, the present invention provides a near-eye display system based on a multifocal achromatic superlens, the near-eye display system comprising, from far to near the human eye: an image source, a polarization modulation unit, and a multifocal achromatic superlens; the polarization modulation unit and the multifocal achromatic superlens are disposed on the light-emitting side of the image source;

[0005] The image source is a transparent micro-nano display array, and a parallel beam is formed by a collimation structure for the multifocal achromatic superlens to focus;

[0006] The polarization modulation unit modulates the polarization state of the original light emitted from the image source to obtain polarized light with a left-handed circular polarization state.

[0007] When the multifocal achromatic superlens receives monochromatic left-handed circularly polarized light, it has at least m different focal lengths; when the multifocal achromatic superlens receives monochromatic left-handed circularly polarized light of m primary colors, the focal length contained in each of the different primary colors can be focused on the same imaging plane to achieve the achromatic function; where m is a natural number greater than 1.

[0008] The multifocal achromatic superlens converges received left-handed circularly polarized light of different wavelengths to the center of the human eye's pupil, thereby forming a retinal projection display with a certain depth of field; the image presented by the projection display is a virtual image at a certain distance on the side of the multifocal achromatic superlens away from the human eye.

[0009] In one specific embodiment, when the original light rays of different primary colors emitted by the image source are left-handed circularly polarized light, the polarization modulation unit includes a polarization rotator and a quarter-wave plate; the polarization rotator is disposed on the light-emitting side of the image source, and the quarter-wave plate is disposed between the polarization rotator and the multifocal achromatic superlens.

[0010] In one specific embodiment, the achromatic superlens converges left-handed circularly polarized light rays of different primary colors to the same focal point.

[0011] In one specific embodiment, the incident light from the multifocal achromatic superlens is left-handed circularly polarized light, and the phase modulation of the left-handed circularly polarized light by the multifocal superlens satisfies the following formula:

[0012]

[0013] Where λ represents the wavelength of the left-hand circularly polarized light; φ represents the modulation phase of the left-hand circularly polarized light at the coordinate (x,y) position in the multifocal superlens; and f represents the focal length of the multifocal achromatic superlens for the left-hand circularly polarized light.

[0014] In one specific embodiment, the multifocal achromatic superlens includes: a substrate and m nanostructures, i.e., the focal length of each primary color through a specific nanostructure is the same; the m nanostructures are arranged alternately in a ring on the substrate.

[0015] In one specific embodiment, a phase modulation unit is formed by using a first preset number of the nanostructures, a second preset number of the nanostructures, and a third preset number of the nanostructures; the phase modulation unit is inserted and arranged on the substrate.

[0016] In one specific embodiment, the cross-section of the nano-dielectric pillars in the metasurface is a rectangular anisotropic structure, so as to have different amplitude and phase responses to left-handed circularly polarized light of different wavelengths; the height of the silicon nano-dielectric pillars in the multifocal achromatic superlens is 100-500 nm, and the maximum aspect ratio is 2:1-5:1; the arrangement period of the nano-dielectric pillars is 100-500 nm.

[0017] In one specific embodiment, the multifocal achromatic superlens is large enough to cover the transparent display screen; the focal length is determined according to the distance from the microdisplay screen to the human eye.

[0018] The beneficial effects of this invention are as follows: 1. This invention proposes a near-eye display system based on a multifocal achromatic superlens. The multifocal achromatic superlens has an optimized optical design, converging incident light of different wavelengths to the same focal point, providing more accurate and realistic color reproduction. Furthermore, the superlens is small in size and lightweight, which helps to achieve a lighter and more compact near-eye display device design, improving wearing comfort and portability. 2. This invention converts light of different wavelengths emitted from the image source into left-handed circularly polarized light through a polarization modulation unit. The multifocal achromatic superlens converges the received left-handed circularly polarized light of different wavelengths to the center of the human eye's pupil, thereby forming a retinal projection display with a certain depth of field. Compared with the large and heavy optical lenses used in related near-eye display systems, using a multifocal achromatic superlens instead of large and heavy optical lenses gives the near-eye display system based on the multifocal achromatic superlens the advantages of small size, light weight, and compact specifications, improving the wearing comfort of users of head-mounted display devices with this system. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of a near-eye display system based on a multifocal achromatic superlens provided in a specific embodiment of the present invention;

[0020] Figure 2 This is a schematic diagram illustrating the situation in which the polarization modulation unit modulates the polarization state of the light emitted from the image source to obtain circularly polarized light in an embodiment of the present invention;

[0021] Figure 3 This is a schematic diagram of a multifocal achromatic superlens focusing left-handed circularly polarized light incident at 450nm, 520nm, and 632nm in an embodiment of the present invention;

[0022] Figure 4 These are schematic diagrams of the overall structure of the multifocal achromatic superlens and the structure of a single superatom in an embodiment of the present invention;

[0023] Figure 5This is a schematic diagram of the phase modulation unit composed of the first nanostructure, the second nanostructure, and the third nanostructure arranged on the substrate in an embodiment of the present invention.

[0024] Figure 6 This is a graph showing the relationship between phase shift and the rotation angle of a rectangular cylinder for three different wavelengths of left-handed circularly polarized light in an embodiment of the present invention.

[0025] Figure 7 This is the electric field intensity distribution of left-handed circularly polarized light incident at different wavelengths in an embodiment of the present invention. Detailed Implementation

[0026] This invention discloses a near-eye display system based on a multifocal achromatic superlens. Those skilled in the art can refer to the content of this document and appropriately modify the technical details to achieve the desired implementation. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The methods and applications of this invention have been described through preferred embodiments. Those skilled in the art can clearly modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit, and scope of this invention to implement and apply the technology of this invention.

[0027] The image formed on a bird's retina is the result of the combined action of the cornea and lens's accommodation mechanisms. On land, birds' eyes are considered to be looking straight ahead, with parallel light rays focusing precisely on the retina, resulting in a clear and focused image. This is because the cornea plays a crucial role in accommodation. However, once immersed in water, the refractive power of the cornea becomes negligible. To maintain image quality, birds can drastically change the shape of the lens, bending it to compensate for the loss of corneal curvature. Inspired by bird eyes, this invention proposes a near-eye display system based on a multifocal achromatic superlens. The multifocal achromatic superlens features an optimized optical design that converges incident light of different wavelengths to a single focal point, providing more accurate and realistic color reproduction. Furthermore, the superlens is small and lightweight, enabling the design of lighter and more compact near-eye display devices, improving wearing comfort and portability.

[0028] like Figures 1-7 As shown, in the first embodiment of the present invention, a near-eye display system based on a multifocal achromatic superlens 102 is provided. The near-eye display system includes, from far to near the human eye, an image source 100, a polarization modulation unit 101, and a multifocal achromatic superlens 102; the polarization modulation unit 101 and the multifocal achromatic superlens 102 are disposed on the light-emitting side of the image source 100.

[0029] The image source 100 is a transparent micro-nano display array, and a parallel light beam is formed by a collimation structure for the multifocal achromatic superlens 102 to focus;

[0030] The polarization modulation unit 101 modulates the polarization state of the original light emitted by the image source 100 to obtain polarized light with a left-handed circular polarization state.

[0031] When the multifocal achromatic superlens 102 receives monochromatic left-handed circularly polarized light, it has at least m different focal lengths; when the multifocal achromatic superlens 102 receives monochromatic left-handed circularly polarized light of m primary colors, the focal length contained in each of the different primary colors of monochromatic light can be focused on the same imaging plane to achieve the achromatic function; where m is a natural number greater than 1.

[0032] The multifocal achromatic superlens 102 converges the received left-handed circularly polarized light of different wavelengths to the center of the human eye's pupil, thereby forming a retinal projection display with a certain depth of field; the image presented by the projection display is a virtual image at a certain distance on the side of the multifocal achromatic superlens 102 away from the human eye.

[0033] In this embodiment, when the original light rays of different primary colors emitted by the image source 100 are left-handed circularly polarized light, the polarization modulation unit 101 includes a polarization rotator and a quarter-wave plate; the polarization rotator is disposed on the light-emitting side of the image source 100, and the quarter-wave plate is disposed between the polarization rotator and the multifocal achromatic superlens 102.

[0034] In this embodiment, the achromatic superlens converges the left-handed circularly polarized light rays of different primary colors to the same focal point.

[0035] In this embodiment, the incident light from the multifocal achromatic superlens 102 is left-handed circularly polarized light, and the phase modulation of the left-handed circularly polarized light by the multifocal superlens satisfies the following formula:

[0036]

[0037] Where λ represents the wavelength of the left-hand circularly polarized light; φ represents the modulation phase of the left-hand circularly polarized light at the coordinate (x,y) position in the multifocal superlens; and f represents the focal length of the multifocal achromatic superlens 102 for the left-hand circularly polarized light.

[0038] In this embodiment, the multifocal achromatic superlens 102 includes: a substrate and m nanostructures, that is, the focal length of each primary color through a specific nanostructure is the same; the m nanostructures are arranged alternately in a ring on the substrate.

[0039] In this embodiment, a phase modulation unit is formed by using a first preset number of the nanostructures, a second preset number of the nanostructures, and a third preset number of the nanostructures; the phase modulation unit is inserted and arranged on the substrate.

[0040] In this embodiment, the cross-section of the nano-dielectric pillars in the metasurface is a rectangular anisotropic structure, so as to have different amplitude and phase responses to left-handed circularly polarized light of different wavelengths; the height of the silicon nano-dielectric pillars in the multifocal achromatic superlens 102 is 100-500 nm, and the maximum aspect ratio is 2:1-5:1; the arrangement period of the nano-dielectric pillars is 100-500 nm.

[0041] In this embodiment, the multifocal achromatic superlens 102 is large enough to cover the transparent display screen; the focal length is determined according to the distance from the microdisplay screen to the human eye.

[0042] In this embodiment, the finite-difference-time-domain (FDTD) method can be used to perform numerical analysis on the superlens design. After the entire lens is constructed, all boundary conditions are set to a perfect match, and the light source used for the layer is a full-field scattering plane light source.

[0043] Alternatively, a single-layer multifocal achromatic metasurface can be used, which has a simple structure and is easy to manufacture.

[0044] Specifically, when the designed superlens structure receives monochromatic left-handed circularly polarized light, it has three different focal lengths; when it receives monochromatic left-handed circularly polarized light of three primary colors (450nm, 520nm, and 632nm), one of the focal lengths of each primary color is the same, thus achieving the achromatic function.

[0045] See Figure 1 The diagram shows a near-eye display system based on a multifocal achromatic superlens 102. This embodiment provides a near-eye display system based on a multifocal achromatic superlens 102, including: an image source 100, a polarization modulation unit 101, and a multifocal achromatic superlens 102.

[0046] The polarization modulation unit 101 and the multifocal achromatic superlens 102 are respectively disposed on the light-emitting side of the image source 100;

[0047] The image source 100 is a transparent micro-nano display array, which forms a parallel light beam through a collimation structure for the multifocal achromatic superlens 102 to focus;

[0048] The polarization modulation unit 101 modulates the polarization state of the light emitted from the image source 100 to obtain light with a left-handed circular polarization state.

[0049] When the superlens structure receives monochromatic left-handed circularly polarized light, it has three different focal lengths; when it receives monochromatic left-handed circularly polarized light of three primary colors (450nm, 520nm, and 632nm), one of the focal lengths of each primary color is the same, thus achieving the function of achromatic aberration.

[0050] The multifocal achromatic superlens 102 converges received left-handed circularly polarized light of different wavelengths to the center of the human eye's pupil, thereby forming a retinal projection display with a certain depth of field. The projected image is a virtual image located at a certain distance from the human eye on the side of the multifocal achromatic superlens 102, and the virtual image is equivalently located on the virtual image plane 103. Furthermore, left-handed circularly polarized light of the same incident wavelength has different focal lengths after being converged by the multifocal achromatic superlens 102.

[0051] The polarization modulation unit 101 is used to modulate the polarization state of the light emitted from the image source 100, see [link / reference] Figure 2 The diagram shows the polarization modulation unit 101 modulating the polarization state of light emitted from the image source 100 to obtain circularly polarized light. The polarization modulation unit 101 includes a polarization rotator and a quarter-wave plate. The polarization rotator is disposed on the light-emitting side of the image source 100; the quarter-wave plate is disposed between the polarization rotator and the multifocal achromatic superlens 102.

[0052] See Figure 3 The diagram shows a multifocal achromatic superlens 102 focusing monochromatic left-handed circularly polarized light of different incident wavelengths to different focal points. When the superlens structure receives monochromatic left-handed circularly polarized light, it has three different focal lengths. When receiving monochromatic left-handed circularly polarized light of three primary colors (450nm, 520nm, and 632nm), one focal length for each primary color is the same, thus achieving achromatic aberration.

[0053] Preferred, such as Figure 4 As shown in (a), the designed multifocal achromatic superlens 102 has a radius of 10 μm and a focal length of 10 μm, and the number of nanomaterial arrays is 70*70. Figure 4 As shown in (b), the cross-section of the nano-dielectric pillars in the metasurface is a rectangular anisotropic structure, so as to have different amplitude and phase responses to left-handed circularly polarized light of different wavelengths; the height of the silicon nano-dielectric pillars in the multifocal achromatic superlens 102 is 100-500 nm, and the maximum aspect ratio is 2:1-5:1; the arrangement period of the nano-dielectric pillars is 100-500 nm.

[0054] Preferably, x, y, and h are the length, width, and height of the silicon nanotube dielectric pillar, respectively, with a depth-to-width ratio of 3:1. The structural unit period is P, and the rotation angle of the silicon nanotube dielectric pillar is θ. The rotation angle of the silicon nanotube dielectric pillar at different positions in the multifocal achromatic superlens 102 can be obtained from the following formula:

[0055]

[0056] Figure 4 (b) The parameters of the structural unit are shown in Table 1:

[0057] Table 1: Structural parameters of silicon nanotube dielectric pillars (unit / nm)

[0058] 195 100 300 290 0-180

[0059] like Figure 5 The diagram shows a schematic of the phase modulation unit, composed of the first, second, and third nanostructures of the designed multifocal achromatic superlens 102, arranged on the substrate; see also... Figure 5 The diagram shows a multifocal superlens with alternating ring arrangements of a first nanostructure, a second nanostructure, and a third nanostructure. The first nanostructure 500, the second nanostructure 501, and the third nanostructure 502 are arranged alternately in a ring on the substrate. The first nanostructure can focus left-handed circularly polarized light with a wavelength of 450 nm to 10 μm; the second nanostructure can focus left-handed circularly polarized light with a wavelength of 520 nm to 10 μm; and the third nanostructure can focus left-handed circularly polarized light with a wavelength of 632 nm to 10 μm.

[0060] The output phase modulated based on the geometric phase principle depends only on the azimuth angle θ of the nanoblock, such as... Figure 6 As shown, we investigated the output phase of Si nanopillars with rotation angles of 0-180° when 450nm, 520nm, and 632nm left-handed circularly polarized light was incident. It can be seen that the azimuth angle of the Si nanopillars matches the geometric phase relationship. This is because of the high refractive index of silicon, the coupling effect between adjacent nanopillars is very weak, so each nanopillar can be considered an isolated waveguide. This ensures that the phase design of each rectangular pillar unit basically conforms to the geometric phase principle, maintaining accuracy.

[0061] like Figure 7 As shown, the focusing characteristics of the superlens under left-handed circularly polarized light of different wavelengths were analyzed, verifying the effectiveness of the designed multifocal achromatic focusing mechanism. Figure 7 As shown in (a) and (b), the focusing characteristics of the superlens under incident 450nm left-handed circularly polarized light. Figure 7As shown in (c) and (d), the focusing characteristics of the superlens under incident left-handed circularly polarized light at 520m. Figure 7 As shown in (e) and (f), the focusing characteristics of the superlens under 632nm left-handed circularly polarized light incidence are demonstrated. When left-handed circularly polarized light of 450nm, 520nm, and 632nm is incident, three different focal points are produced, achieving multifocal performance. Furthermore, when left-handed circularly polarized light of 450nm, 520nm, and 632nm is incident, achromatic focusing characteristics are achieved in the same depth plane. Figure 7 (a) xy plane (b) xz plane, electric field intensity distribution under 450nm left-handed circularly polarized light. Figure 7 (c) xy plane (d) xz plane, electric field intensity distribution under 520nm left-handed circularly polarized light. Figure 7 (e)xy plane (f)xz plane, electric field intensity distribution under 632nm left-handed circularly polarized light.

[0062] In summary, this embodiment proposes a near-eye display system based on a multifocal achromatic superlens. A polarization modulation unit converts light of different wavelengths emitted from the image source into left-handed circularly polarized light. The multifocal achromatic superlens then converges the received left-handed circularly polarized light of different wavelengths to the center of the human eye's pupil, thereby forming a retinal projection display with a certain depth of field. Compared to the large and heavy optical lenses used in related near-eye display systems, using a multifocal achromatic superlens instead of large and heavy optical lenses gives the near-eye display system based on a multifocal achromatic superlens advantages such as small size, light weight, and compact design. This improves the wearing comfort of users of head-mounted display devices equipped with a near-eye display system based on a multifocal achromatic superlens.

[0063] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0064] The various embodiments in this specification are described in a related manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions of the method embodiments.

[0065] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A near-eye display system based on a multifocal achromatic superlens, characterized in that, The near-eye display system includes, from far to near the human eye, an image source, a polarization modulation unit, and a multifocal achromatic superlens; the polarization modulation unit and the multifocal achromatic superlens are disposed on the light-emitting side of the image source; The image source is a transparent micro-nano display array, and a parallel beam is formed by a collimation structure for the multifocal achromatic superlens to focus; The polarization modulation unit modulates the polarization state of the original light emitted from the image source to obtain polarized light with a left-handed circular polarization state. When the multifocal achromatic superlens receives monochromatic left-handed circularly polarized light, it has at least m different focal lengths; when the multifocal achromatic superlens receives monochromatic left-handed circularly polarized light of m primary colors, the focal length contained in each of the different primary colors can be focused on the same imaging plane to achieve the achromatic function; where m is a natural number greater than 1. Light rays are directly converged to the pupil of the human eye after passing through the multifocal achromatic superlens to complete the image formation; The multifocal achromatic superlens converges received left-handed circularly polarized light of different wavelengths to the center of the human eye's pupil, thereby forming a retinal projection display with a certain depth of field; the image presented by the projection display is a virtual image at a certain distance on the side of the multifocal achromatic superlens away from the human eye. The nano-dielectric pillars in the metasurface of the multifocal achromatic superlens have a rectangular anisotropic cross-section to provide different amplitude and phase responses to left-handed circularly polarized light of different wavelengths. The height of the nano-dielectric pillars in the multifocal achromatic superlens is 100~500nm, and the maximum aspect ratio is 2:1~5:

1. The arrangement period of the nano-dielectric pillars is 100~500nm.

2. The near-eye display system based on a multifocal achromatic superlens according to claim 1, characterized in that, When the original light rays of different primary colors emitted by the image source are left-handed circularly polarized light, the polarization modulation unit includes a polarization rotator and a quarter-wave plate; the polarization rotator is disposed on the light-emitting side of the image source, and the quarter-wave plate is disposed between the polarization rotator and the multifocal achromatic superlens.

3. The near-eye display system based on a multifocal achromatic superlens according to claim 1, characterized in that, The multifocal achromatic superlens converges the received left-handed circularly polarized light rays of different primary colors to the same focal point.

4. The near-eye display system based on a multifocal achromatic superlens according to claim 1, characterized in that, The incident light from the multifocal achromatic superlens is left-handed circularly polarized light, and the phase modulation of the left-handed circularly polarized light by the multifocal achromatic superlens satisfies the following formula: in, Indicates the wavelength of left-handed circularly polarized light; The coordinate (x, y) position in the multifocal achromatic superlens represents the modulation phase of the left-hand circularly polarized light, where f represents the focal length of the multifocal achromatic superlens for the left-hand circularly polarized light.

5. The near-eye display system based on a multifocal achromatic superlens according to claim 1, characterized in that, The multifocal achromatic superlens comprises: a substrate and m nano-dielectric pillars, meaning that the focal length of each primary color through the nano-dielectric pillars is the same; the m nano-dielectric pillars are arranged alternately in a ring on the substrate.

6. The near-eye display system based on a multifocal achromatic superlens according to claim 5, characterized in that, A phase modulation unit is formed by using a first preset number of nano-dielectric pillars, a second preset number of nano-dielectric pillars, and a third preset number of nano-dielectric pillars; the phase modulation unit is inserted and arranged on the substrate.

7. The near-eye display system based on a multifocal achromatic superlens according to claim 1, characterized in that, The multifocal achromatic superlens is large enough to cover the transparent micro / nano display array; the focal length is determined by the distance from the transparent micro / nano display array to the human eye.

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