Waveguide and electronic device employing same

Abstract

Provided is a method comprising the steps of: by using a single optical element in which nanostructures are arranged on a two-dimensional plane, with a first period, obtaining diffraction paths in which first light and second light travel, respectively, by diffracting the first light and the second light which are incident on the optical element at the same angle, into a plurality of paths; determining, on the basis of the diffraction paths, a traveling angle at which the first light and the second light are diffracted in the same direction and travel; obtaining a plurality of combinations consisting of the first period, the traveling angle, the wavelength of the first light, and the wavelength of the second light; obtaining diffraction efficiencies of the first light and the second light respectively corresponding to the plurality of obtained combinations; and updating the structure of the optical element on the basis of the obtained diffraction efficiencies.

Description

Waveguide and electronic device employing it

[0001] The present disclosure relates to a waveguide for miniaturizing a device and an electronic device employing the same. Specifically, the present disclosure relates to an electronic device for providing light of an image to a user using a single waveguide.

[0002] Augmented reality (AR) devices are devices that allow users to experience augmented reality (AR), such as AR glasses. The imaging optical system of an AR device includes a component that generates images and a waveguide that transmits the generated images to the eyes. These AR devices require a wide field of view and high-quality images, while also being lightweight and compact.

[0003] Recently, waveguide-based optical systems are being researched and developed for AR devices such as AR glasses. Conventional waveguides input light into the waveguide using freeform surface reflection or multi-mirror reflection, or input-coupled diffractive elements such as diffractive optical elements or holographic optical elements. Conventional freeform surface reflection or multi-mirror reflection can have a simple structure and high light transmission efficiency, but have limited field of view and difficulty in thinning the waveguide. While thinning the waveguide using conventional input-coupled diffractive elements is relatively easy, the problem is that only the first-order diffracted light is utilized in the input-coupled diffractive element, resulting in low light transmission efficiency. Furthermore, because separate substrates are required for each of the three primary colors (RGB; Red, Green, Blue) of light, thinning the waveguide has been difficult.

[0004] In order to solve the above-described technical problem, a method according to an embodiment of the present disclosure includes a step of diffracting first light and second light incident on the optical element at the same angle into a plurality of paths using a single optical element in which nanostructures are arranged according to a first period on a two-dimensional plane, thereby obtaining diffraction paths along which the first light and the second light respectively proceed. The method includes a step of determining, based on the diffraction paths, a propagation angle at which the first light and the second light proceed by being diffracted in the same direction. The method includes a step of obtaining a plurality of combinations consisting of a first period, a propagation angle, a wavelength of the first light, and a wavelength of the second light. The method includes a step of obtaining diffraction efficiencies of the first light and the second light, each corresponding to the obtained plurality of combinations. The method includes a step of updating a structure of the optical element based on the obtained diffraction efficiencies.

[0005] An electronic device according to one embodiment of the present disclosure includes a memory storing one or more instructions. The electronic device includes at least one processor executing one or more instructions stored in the memory. The electronic device includes a waveguide including a single substrate guiding a plurality of lights. The electronic device includes an input-coupling element positioned on the substrate and configured to allow external light to be incident into the substrate. The electronic device includes an output-coupling element positioned on the substrate and configured to output the external light from the substrate. At least one of the input-coupling element and the output-coupling element includes a single optical element, wherein the optical element comprises nanostructures arranged in a first period on a two-dimensional plane and is configured to diffract first and second lights incident at the same angle into a plurality of paths, respectively. At least one processor can obtain diffraction paths along which the first and second lights travel, respectively, by executing one or more instructions using the optical element. At least one processor can determine a propagation angle at which the first light and the second light are diffracted and propagate in the same direction based on the diffraction path. At least one processor can obtain a plurality of combinations consisting of a first period, a propagation angle, a wavelength of the first light, and a wavelength of the second light. At least one processor can obtain a diffraction efficiency of the first light and the second light corresponding to each of the obtained plurality of combinations. At least one processor can update the structure of the optical element based on the obtained diffraction efficiency.

[0006] A computer-readable recording medium having recorded thereon a program for performing a method according to an embodiment of the present disclosure on a computer is provided.

[0007] The present disclosure can be readily understood by the following detailed description and its accompanying drawings, wherein reference numerals refer to structural elements.

[0008] FIG. 1 is a drawing illustrating a method of diffracting multiple lights into multiple paths using a single waveguide according to an embodiment of the present disclosure.

[0009] FIG. 2 is a conceptual diagram illustrating a plurality of light rays traveling in the same direction after diffraction according to one embodiment of the present invention traveling along a waveguide.

[0010] FIG. 3 is a conceptual diagram illustrating an optical element according to one embodiment of the present disclosure.

[0011] FIG. 4 is a conceptual diagram for explaining in detail the design of nanostructures in an optical element according to one embodiment of the present disclosure.

[0012] FIG. 5 is a flowchart illustrating a method for designing a single optical element for guiding light according to one embodiment of the present disclosure.

[0013] FIG. 6 is a flowchart illustrating an algorithm for optimizing a single optical element for guiding light according to one embodiment of the present disclosure.

[0014] FIG. 7 is a flowchart illustrating a method for ensuring robustness to optimize an optical element according to one embodiment of the present disclosure.

[0015] FIG. 8 is a schematic diagram illustrating an electronic device having an optical element according to one embodiment of the present disclosure.

[0016] FIG. 9 is a schematic diagram illustrating augmented reality glasses having an optical element according to one embodiment of the present disclosure.

[0017] The terms used in the embodiments of this specification have been selected from widely used, current terms, taking into account the functions of the present disclosure. However, these terms may vary depending on the intentions of those skilled in the art, precedents, the emergence of new technologies, etc. Furthermore, in certain cases, terms may be arbitrarily selected by the applicant, and in such cases, their meanings will be described in detail in the description of the relevant embodiments. Therefore, the terms used in this specification should not be defined simply as names of terms, but rather based on their meanings and the overall content of the present disclosure.

[0018] Singular expressions may include plural expressions unless the context clearly indicates otherwise. Terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the art described herein.

[0019] Throughout this disclosure, when a part is said to "include" a component, this does not exclude other components, but rather implies the inclusion of other components, unless otherwise specifically stated. Furthermore, terms such as "part," "module," and the like used herein refer to a unit that processes at least one function or operation, which may be implemented in hardware or software, or a combination of hardware and software.

[0020] As used herein, the expression "configured to" can be used interchangeably with, for example, "suitable for," "having the capacity to," "designed to," "adapted to," "made to," or "capable of." The term "configured to" does not necessarily mean something is "specifically designed to" in terms of hardware. Instead, in some contexts, the expression "a system configured to" can mean that the system is "capable of" in conjunction with other devices or components. For example, the phrase "a processor configured to perform A, B, and C" can mean a dedicated processor for performing the operations (e.g., an embedded processor), or a general-purpose processor (e.g., a CPU or an application processor) that can perform the operations by executing one or more software programs stored in memory.

[0021] Additionally, when a component is referred to as being "connected" or "connected" to another component in the present disclosure, it should be understood that the component may be directly connected or connected to the other component, but may also be connected or connected via another component in between, unless otherwise specifically stated.

[0022] Below, embodiments of the present disclosure are described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present disclosure. However, the present disclosure may be implemented in various different forms and is not limited to the embodiments described herein.

[0023] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0024] FIG. 1 is a drawing illustrating a method of diffracting multiple lights into multiple paths using a single waveguide according to an embodiment of the present disclosure.

[0025] Referring to FIG. 1, in one embodiment, an electronic device may be a device for providing an image to a user. The electronic device may include a waveguide (100) that guides light of the image in an intended direction. The electronic device may output light of the image toward the user using the waveguide (100). The waveguide (100) may be provided for each of the left and right eyes corresponding to the display unit, or may be provided for only one side.

[0026] For reference, FIG. 1 is a drawing centered on an optical element (10) that diffracts first light (L1), second light (L2), and third light (L3) into multiple paths to explain the principle for guiding the light of an image in an intended direction.

[0027] In one embodiment, the waveguide (100) may include a substrate (20) and an optical element (10).

[0028] The substrate (20) is configured to transmit light of a virtual image generated in the display unit to the user's pupil. The substrate (20) may have a flat plate shape. The substrate (20) may be formed into a single-layer structure in which light can be propagated while being reflected internally.

[0029] For example, the substrate (20) may be formed as a single-layer structure of a transparent material. Here, the transparent material means a material that allows light in the visible light band to pass through, and the transparency may not be 100% and may have a predetermined color. Since the substrate (20) is formed of a transparent material, the substrate (20) is configured to allow light from an external scene to pass through and be transmitted to the user's pupil. Since the user can view not only virtual images but also real scenes through the electronic device, the electronic device can implement augmented reality.

[0030] As another example, the substrate (20) may be formed as a single-layer structure of an opaque material. Since the substrate (20) is formed of an opaque material, the substrate (20) is configured to block light from an external scene. A user can view a virtual image through light from the virtual image guided through the substrate (20). An electronic device can realize augmented reality by acquiring light from an external scene through an image sensor and outputting the light from the external scene and the light from the virtual image together on a display unit.

[0031] The optical element (10) may be placed on a substrate (20). The optical element (10) may be an optical element configured to cause incident light to be diffracted and propagate along multiple paths. For example, the optical element (10) may be a diffractive element that diffracts incident light. The diffractive element may be implemented as a diffractive optical element (DOE), a holographic optical element (HOE), a polymer dispersed liquid crystal (PDLC), a metasurface, etc.

[0032] In one embodiment, the optical element (10) may include a structure in which nanostructures are installed in a periodic, repeating manner on a two-dimensional plane. In the present disclosure, the period in which the nanostructures are installed may be expressed as a first period (P1). The nanostructures in the optical element (10) will be specifically described using FIGS. 3 and 4. In addition, for convenience of explanation, FIG. 1 only restrictively expresses the area of ​​the first period (P1) of the optical element (10), and the optical element (10) may be a flat plate wider than the first period (P1).

[0033] The optical element (10) may be positioned on one side (20a) of the substrate (20). In FIG. 1, it is illustrated that a plurality of lights are diffracted by the optical element (10), pass through the optical element (10), and proceed into the inside of the substrate (20), but the technical idea of ​​the present disclosure is not limited thereto. For example, the optical element (10) may be positioned on the other side (20b) of the substrate (20). A plurality of lights may be incident on one side (20a) of the substrate (20), diffracted by the optical element (10) positioned on the other side (20b), and reflected by the optical element (10) and proceed into the inside of the substrate (20).

[0034] In one embodiment, the electronic device can propagate first light (L1), second light (L2), and third light (L3) along a set path through a waveguide (100), and provide an image or video to a user through the first light (L1), second light (L2), and third light (L3). The combination of the first light (L1), second light (L2), and third light (L3) can be light of an image output through a display unit of the electronic device.

[0035] In one embodiment, the first light (L1), the second light (L2), and the third light (L3) may include the three primary colors of light (RGB; Red, Green, Blue). For example, the first light (L1) may be red light, the second light (L2) may be green light, and the third light (L3) may be blue light.

[0036] In one embodiment, the first light (L1), the second light (L2), and the third light (L3) may be incident on the optical element (10). The first light (L1), the second light (L2), and the third light (L3) may be diffracted by the optical element (10) and then transmitted through the optical element (10). The first light (L1), the second light (L2), and the third light (L3) may be transmitted into the substrate (20).

[0037] In one embodiment, a first light (L1) may be incident toward an optical element (10). The first light (L1) may be diffracted by the optical element (10). The first light (L1) may transmit through the optical element (10) and propagate into the substrate (20). The first light (L1) may be diffracted by the optical element (10) and propagate along a first path (1), a second path (2), a third path (3), and a fourth path (4).

[0038] The light of the first diffraction order generated by the first light (L1) being diffracted by the optical element (10) can proceed along the first path (1). The light of the second diffraction order generated by the first light (L1) being diffracted by the optical element (10) can proceed along the second path (2). The light of the third diffraction order generated by the first light (L1) being diffracted by the optical element (10) can proceed along the third path (3). The light of the fourth diffraction order generated by the first light (L1) being diffracted by the optical element (10) can proceed along the fourth path (4). The diffraction order of the first light generated by the optical element (10) does not limit the technical idea of ​​the present disclosure, and for the convenience of explanation, the generation of the light of the fourth diffraction order is described as an example.

[0039] The path of light diffracted by the optical element (10) can be determined according to mathematical formula 1. However, mathematical formula 1 is only an example mathematical formula to aid explanation, and a more specific mathematical formula may be used, and the technical idea of ​​the present disclosure is not limited thereto.

[0040] [Mathematical Formula 1]

[0041]

[0042] In mathematical expression 1, Λ may denote a period in which nanostructures within the optical element (10) are repeatedly arranged. The unit of Λ may be distance. For example, the first period (P1; Period 1) illustrated in FIG. 1 may be substituted for Λ.

[0043] In mathematical equation 1, It may refer to the angle at which light incident on the optical element (10) is refracted after being diffracted. can be calculated as the angle at which light is refracted based on the normal vector of the incident surface onto which the light is incident.

[0044] For example, the first light (L1) can be incident on the optical element (10). The incident first light (L1) can be diffracted and can proceed along the first path (1), the second path (2), the third path (3), and the fourth path (4) depending on the diffraction order. In the case of the light of the fourth diffraction order in which the first light (L1) is diffracted and proceeds along the fourth path (4), is the first angle ( ) may be.

[0045] In Equation 1, m can be an integer. m can be one of all integers that satisfy the condition in Equation 1. Specifically, sin Since the value of has a range of -1 to 1, the value of m can be specified. Depending on the number of possible m, the possible Since the number of , the number of paths of light diffracted by the optical element (10) is determined.

[0046] In mathematical equation 1, may refer to the wavelength of light incident on the optical element (10). For example, the first light (L1) may be incident on the optical element (10). The wavelength of the first light (L1) is can be substituted into

[0047] In one embodiment, a first light (L1) may be incident toward an optical element (10). The first light (L1) may be diffracted by the optical element (10), and the maximum diffraction order may be determined based on the number of possible m.

[0048] [Equation 2]

[0049]

[0050] For example, if mathematical expression 1 is transformed into mathematical expression 2, Since m has a value greater than -1 and less than 1, over It may be an integer less than . Therefore, m, i.e., the maximum diffraction order of light incident on the optical element (10), can be determined according to the ratio of the period in which the nanostructures in the optical element (10) are repeatedly arranged and the wavelength of light incident on the optical element (10).

[0051] For example, the first light (L1) may be diffracted by the optical element (10), and light of the fourth diffraction order may be generated. The diffraction angle of the light of the fourth diffraction order generated by the first light (L1) being diffracted by the optical element (10) is the first angle ( ) may be.

[0052] In one embodiment, the period at which the nanostructures within the optical element (10) are repeatedly arranged may be greater than the wavelength of light incident on the optical element (10). The first period (P1) may be greater than the wavelength of the first light (L1), the wavelength of the second light (L2), and the wavelength of the third light (L3), respectively.

[0053] In one embodiment, the light of each diffraction order after the first light (L1) is diffracted by the optical element (10) may have its own diffraction efficiency. For example, the diffraction efficiency of the light of the first diffraction order that proceeds along the first path (1) after the first light (L1) is diffracted by the optical element (10) and the diffraction efficiency of the light of the second diffraction order that proceeds along the second path (2) after the first light (L1) is diffracted by the optical element (10) may be different from each other.

[0054] For reference, for convenience of explanation, the explanation regarding the diffraction of the second light (L2) and the third light (L3) overlaps with the explanation using the first light (L1), so it is simplified or omitted.

[0055] In one embodiment, the second light (L2) may be diffracted by the optical element (10), and light of the fifth diffraction order may be generated. The diffraction angle of the light of the fifth diffraction order generated by the second light (L2) being diffracted by the optical element (10) is the second angle ( ) may be. In one embodiment, the light of each diffraction order after the second light (L2) is diffracted by the optical element (10) may have its own diffraction efficiency.

[0056] In one embodiment, the third light (L3) may be diffracted by the optical element (10), and light of the 6th diffraction order may be generated. The diffraction angle of the light of the 6th diffraction order generated by the third light (L3) being diffracted by the optical element (10) is the third angle ( ) may be. In one embodiment, the light of each diffraction order after the third light (L3) is diffracted by the optical element (10) may have its own diffraction efficiency.

[0057] In one embodiment, the first angle ( ), second angle ( ) and the third angle ( ) may be the same. The light of the 4th diffraction order generated when the first light (L1) is diffracted by the optical element (10), the light of the 5th diffraction order generated when the second light (L2) is diffracted by the optical element (10), and the light of the 6th diffraction order generated when the third light (L3) is diffracted by the optical element (10) may propagate in the same direction into the substrate (20). Each diffraction order is merely an example and does not limit the technical idea of ​​the present disclosure.

[0058] An electronic device according to one embodiment can transmit light of a virtual image based on light of diffraction orders that propagate in the same direction after first light (L1), second light (L2), and third light (L3) are diffracted by a single optical element (10). The electronic device can provide a virtual image to a user through the transmitted light of the virtual image. The electronic device can implement augmented reality.

[0059] In one embodiment, among the lights of each diffraction order after the first light (L1) is diffracted by the optical element (10), the light of the 4th diffraction order may have the highest diffraction efficiency. Among the lights of each diffraction order after the second light (L2) is diffracted by the optical element (10), the light of the 5th diffraction order may have the highest diffraction efficiency. Among the lights of each diffraction order after the third light (L3) is diffracted by the optical element (10), the light of the 6th diffraction order may have the highest diffraction efficiency. The lights of each diffraction order that propagate in the same direction after the first light (L1), the second light (L2), and the third light (L3) are diffracted by the optical element (10) may each have the highest diffraction efficiency.

[0060] FIG. 2 is a conceptual diagram illustrating a plurality of light rays traveling in the same direction after diffraction according to one embodiment of the present invention traveling along a waveguide.

[0061] For convenience of explanation, details that overlap with those described using Fig. 1 are simplified or omitted. In Fig. 2, for convenience of explanation, the first light is described in detail as L11, L12, and L13, the second light as L21, L22, and L23, and the third light as L31, L32, and L33.

[0062] Referring to FIG. 2, in one embodiment, the waveguide may include an input-coupling element (200), a substrate (20), and an output-coupling element (300). The electronic device may transmit incident light to a target area (TA) using the waveguide. The electronic device may provide light of a virtual image output from a display unit to a user using the waveguide.

[0063] In one embodiment, an input-coupling element (200) may be disposed on a first surface of the substrate (20). The input-coupling element (200) may be formed by being attached to or coated on the first surface of the substrate (20).

[0064] In one embodiment, the input-coupling element (200) may be configured to propagate the incident light into the substrate (20) by diffracting the incident light. The input-coupling element (200) may be a meta element that propagates at least one of the first light (L11), the second light (L21), and the third light (L31) into the substrate (20). The meta element is an element having a metasurface structured with a pattern smaller than the wavelength of the incident light (i.e., a surf wavelength), and may be, for example, a metagrating or a metalens having a pattern smaller than the wavelength of the incident light, but is not limited thereto.

[0065] In one embodiment, the period of the pattern of the metaelement may be greater than the wavelength of the incident light. The input-coupling element (200) may be composed of the optical element (10) illustrated in FIG. 1.

[0066] As another example, the input-coupling element (200) may be formed by being attached to or coated on the second surface of the substrate (20). The second surface may be a surface opposite to the first surface among both surfaces of the substrate (20).

[0067] For reference, if the first area (A1) is enlarged, it can be expressed as a second area (A2). Using the second area (A2), the structure of the input-coupling element (200) as an optical element (10 in FIG. 1) and the directions in which the first light (L12), the second light (L22), and the third light (L32) propagate within the substrate (20) are explained.

[0068] In one embodiment, the input-coupling element (200) may be a meta-element. The input-coupling element (200) may be a combination of a plurality of nano-structures (11) arranged on a substrate (20). The input-coupling element (200) may diversify the diffraction orders of incident light incident on the optical system or diffract it at various angles depending on the arrangement shape of the plurality of nano-structures (11).

[0069] Here, the 'array shape' may mean at least one of the size, shape, arrangement spacing of each of the plurality of nanostructures (11), size distribution by position, shape distribution by position, and spacing distribution by position of the plurality of nanostructures (11) with respect to the area where the meta element is located. The detailed array shape of the plurality of nanostructures (11) included in the input-coupling element (200) may vary depending on the optical performance required for the input-coupling element (200). For example, the array shape of the nanostructures may vary depending on the wavelength band of the light to be diffracted through the input-coupling element (200), and the array shape of the nanostructures may vary so as to optimize the diffraction order and diffraction efficiency of the light after being diffracted through the input-coupling element (200).

[0070] In one embodiment, an output-coupling element (300) may be disposed on the second surface of the substrate (20). The output-coupling element (300) may be formed by being attached to or coated on the second surface of the substrate (20).

[0071] In one embodiment, the output-coupling element (300) may be configured to diffract light propagating within the substrate (20) and output the light propagating within the substrate (20) to the outside of the substrate (20). The output-coupling element (300) may be a meta element that outputs at least one of the first light (L12), the second light (L22), and the third light (L32) propagated within the substrate (20) to the outside of the substrate (20). The meta element is an element having a metasurface structured with a pattern smaller than the wavelength of the incident light (i.e., a surf wavelength), and may be, for example, a metagrating or a metalens having a pattern smaller than the wavelength of the incident light, but is not limited thereto.

[0072] In one embodiment, the period of the pattern of the metaelement may be greater than the wavelength of the incident light. The output-coupling element (300) may be composed of the optical element (10) illustrated in FIG. 1.

[0073] In one embodiment, the first light (L12) may be diffracted by the input-coupling element (200) and propagate into the substrate (20). The first light (L12) incident perpendicularly to the incident surface of the input-coupling element (200) may be diffracted at a predetermined angle ( ) and can be propagated into the substrate (20).

[0074] In one embodiment, the second light (L22) and the third light (L32) are also at a predetermined angle ( ) and can be propagated into the substrate (20). The input-coupling element (200) diffracts the first light (L11), the second light (L21), and the third light (L31) at a predetermined angle ( ) and can be diffracted in the same manner and propagated into the substrate (20).

[0075] In one embodiment, the substrate (20) may be formed into a structure in which light can be transmitted while being reflected internally. At a predetermined angle ( ) The first light (L12), the second light (L22), and the third light (L32) propagated into the substrate (20) can be propagated while being reflected inside the substrate (20).

[0076] In one embodiment, the first light (L13) may be diffracted by the output-coupling element (300) and propagate outside the substrate (20). The first light (L13) may be diffracted by the output-coupling element (300) and output to the target area (TA). The second light (L23) may be diffracted by the output-coupling element (300) and output to the target area (TA). The third light (L33) may be diffracted by the output-coupling element (300) and output to the target area (TA).

[0077] Specifically, the first light (L11) may be diffracted by the input-coupling element (200) and may proceed along multiple paths. Among the multiple paths along which the first light (L11) proceeds after being diffracted, for example, the light of the 4th diffraction order may be diffracted at a predetermined angle ( ) can proceed. Similarly, among the multiple paths that the second light (L21) travels after being diffracted, for example, the light of the 5th diffraction order can proceed at a predetermined angle ( ) can proceed. Among the multiple paths that the third light (L31) travels after being diffracted, for example, the light of the 6th diffraction order can proceed at a predetermined angle ( ) can proceed.

[0078] For example, light of the 4th diffraction order of the first light (L11), light of the 5th diffraction order of the second light (L21), and light of the 6th diffraction order of the third light (L31) can be propagated in the same direction into the substrate (20), and can be diffracted by the output-coupling element (300) and propagated to the outside of the substrate (20).

[0079] An electronic device according to one embodiment can provide light of a virtual image based on diffracted light traveling in the same direction among a plurality of paths along which a plurality of incident light rays travel after being diffracted by an optical element.

[0080] FIG. 3 is a conceptual diagram illustrating an optical element according to one embodiment of the present disclosure.

[0081] For convenience of explanation, parts that overlap with those described using Figures 1 and 2 are simplified or omitted.

[0082] Referring to FIG. 3, in one embodiment, the electronic device may diffract incident light using an optical element (160). The optical element (160) may be a diffractive element that diffracts incident light. The diffractive element may be implemented as a metasurface.

[0083] The optical element (160) may have a pattern formed in a circular shape, for example. The optical element (160) may have a pattern in which a certain shape is regularly repeated. That is, the optical element (160) may have a concentric pattern in which circular patterns having different radii are repeated.

[0084] However, the shape of the pattern of the optical element (160) illustrated in FIG. 3 is merely an example, and the technical concept of the present disclosure is not limited thereto. For example, the optical element (160) may have a pattern formed in a square shape. The optical element (160) may have a pattern in which square shapes are repeated. As another example, the optical element (160) generally has a circular pattern, but may also include some irregular patterns.

[0085] For convenience of explanation, the optical element (160) is described by enlarging the third region (A3) of the optical element (160). In one embodiment, the optical element (160) may include a substrate (20) and a plurality of nanostructures (11). The plurality of nanostructures (11) may constitute the optical element (10 of FIG. 1) illustrated in FIG. 1.

[0086] The substrate (20) may have a flat plate shape. A plurality of nanostructures (11) may be arranged on the substrate (20). The plurality of nanostructures (11) may extend perpendicularly to the upper surface of the substrate (20). As illustrated in FIG. 3, the plurality of nanostructures (11) may be rods having a rectangular parallelepiped shape. The plurality of nanostructures (11) may be a plurality of rods that are repeated according to a first period (P1). The plurality of nanostructures (11) may be arranged to be spaced apart from each other at a predetermined interval. The plurality of rods may include at least a first rod formed with a first height and a first width and a second rod formed with a second height and a second width. The diversity of the height, width, and interval of the rods is specifically described using FIG. 4. The plurality of rods further include a third rod, and a first interval between the first rod and the second rod and a second interval between the second rod and the third rod may be different from each other.

[0087] Although the heights of the plurality of nanostructures (11) in FIG. 3 are shown as being irregularly formed, the technical concept of the present invention is not limited thereto. For example, the plurality of nanostructures (11) may be arranged in a form in which the first height and the second height are regularly repeated. As another example, the plurality of nanostructures (11) may be formed to the same height.

[0088] The plurality of nanostructures (11) included in the optical element (160) can diffract a plurality of incident lights incident on the optical system so that they are refracted at the same angle, depending on their arrangement shape. For example, the optical element (160) can function as an input-coupling element for propagating light of a virtual image into the inside of a waveguide.

[0089] Here, the 'array shape' may mean at least one of the size, height, shape, arrangement spacing of each nanostructure (11), size distribution by position, shape distribution by position, and spacing distribution by position of the nanostructures (11). The detailed array shape of the nanostructure included in the optical element (160) may vary depending on the optical performance required for the optical element (160). For example, the array shape of the nanostructure may vary in order to control the diffraction angle for propagating incident light into the waveguide through the optical element (160), the diffraction efficiency of the diffracted light, etc.

[0090] In one embodiment, the optical element (160) may include a plurality of nanostructures (11) that are repeatedly arranged in a period on a two-dimensional plane. The arrangement shape of the plurality of nanostructures (11) may be repeated based on a first period (P1). The first period (P1) may be designed to be greater than the wavelength of incident light. For example, in a case where red light, green light, and blue light are incident on the optical element (160), the first period (P1) of the optical element (160) may be designed to be greater than the wavelength of red light.

[0091] In one embodiment, the substrate (20) and the plurality of nanostructures (11) may be formed integrally. For example, a dielectric material may be applied onto the substrate (20). An etching process may be performed so that the applied dielectric material may have a predetermined pattern. As a result of the etching process, a plurality of nanostructures (11) may be formed on the substrate (20).

[0092] By combining a plurality of nanostructures (11) formed in nano units, the first period (P1) of the optical element (160) can be designed to be large. At least, the first period (P1) of the optical element (160) can be designed to be larger than the wavelength of the incident light. For example, the first period (P1) should be designed to be sufficiently larger than the wavelength of the incident light, so that the maximum diffraction order of the light incident on the optical element (160) can be sufficiently large according to mathematical expression 2. The method of the present disclosure induces the incident light to be diffracted along various paths by the optical element (160), and transmits the diffracted light that propagates in the same direction after the incident light is diffracted into the substrate (20). The diffracted light that has progressed into the substrate (20) is emitted outside the substrate (20) by an output-coupling element composed of an optical element (160) and can be displayed to the user.

[0093] FIG. 4 is a conceptual diagram for explaining in detail the design of nanostructures in an optical element according to one embodiment of the present disclosure.

[0094] For convenience of explanation, parts that overlap with those described using Figure 3 are simplified or omitted.

[0095] Referring to FIG. 4, the optical element may include a substrate (20) and a plurality of nanostructures.

[0096] In one embodiment, the optical element may include a plurality of nanostructures that are repeated in a periodic manner. For example, a plurality of nanostructures may be arranged within a first period (P1). The plurality of nanostructures may include a plurality of rods (110, 120, 130) that are repeated in a first period (P1).

[0097] In one embodiment, the array shapes of the plurality of nanostructures can be formed differently from each other.

[0098] For example, among the plurality of nanostructures, a first rod (110) may be formed to have a first height (H1) and a first thickness (W1). A second rod (120) among the plurality of nanostructures may be formed to have a second height (H2) and a second thickness (W2). The first height (H1) and the second height (H2) may be different from each other. The first thickness (W1) and the second thickness (W2) may be different from each other. Of course, the first height (H1) and the second height (H2) may be the same, and the first thickness (W1) and the second thickness (W2) may be the same.

[0099] As another example, the first rod (110) may be formed as a rectangular solid column. The second rod (120) may be formed as a rectangular solid column. Of course, the shapes of the first rod (110) and the second rod (120) do not limit the technical concept of the present invention.

[0100] Descriptions regarding the third height (H3) and third thickness (W3) of the third rod (130) among the multiple nanostructures are omitted as they are the same as those described using the first rod (110) and the second rod (120).

[0101] As another example, among the plurality of nanostructures, the first rod (110) and the second rod (120) may be arranged to be spaced apart from each other by a first distance (I1). The second rod (120) and the third rod (130) may be arranged to be spaced apart from each other by a second distance (I2). The first distance (I1) and the second distance (I2) may be different from each other. Of course, the first distance (I1) and the second distance (I2) may be the same, and the technical idea of ​​the present invention is not limited thereto.

[0102] FIG. 5 is a flowchart illustrating a method for designing a single optical element for guiding light according to one embodiment of the present disclosure.

[0103] For convenience of explanation, parts that overlap with those described using Figures 1 to 4 are simplified or omitted.

[0104] In step S510, the electronic device can diffract the first and second lights incident on the optical element at the same angle into multiple paths using a single optical element. The electronic device can obtain the diffraction paths along which the first and second lights travel using a single optical element.

[0105] In one embodiment, the electronic device can output first light and second light using a display unit that outputs light of a virtual image. The electronic device can output the first light and the second light toward an optical element. The first light and the second light are incident perpendicularly to the incident surface of the optical element.

[0106] In one embodiment, the electronic device can diffract the first light and the second light using a single optical element, thereby allowing the first light and the second light to enter the substrate. The optical element and the substrate form a waveguide, and the first light and the second light can be diffracted by the optical element and then propagate into the substrate. The optical element can be disposed on the substrate.

[0107] In one embodiment, the optical element may have nanostructures arranged in a first period on a two-dimensional plane. The nanostructures may include a plurality of rods that repeat in the first period. The plurality of rods may include a first rod formed with at least a first height and a first width, and a second rod formed with a second height and a second width.

[0108] In one embodiment, first and second light incident vertically may be diffracted by the optical element. After being diffracted by the optical element, the first light may travel through multiple paths. The first light may travel through multiple paths based on diffraction orders. The diffraction orders may be determined based on the m value according to Equation 1. For example, the diffraction orders may be determined based on the period at which the nanostructures of the optical element are arranged and the wavelength of the incident light. As a specific example, when the integer values ​​of m according to Equation 1 are 1, 2, and 3, the incident light may be diffracted by the optical element and travel through three paths. The incident light may propagate into the substrate through three paths.

[0109] In one embodiment, the first light and the second light may include two lights among the three primary colors of light (RGB; Red, Green, Blue). The first light and the second light may each be one of red light, green light, and blue light. For convenience of explanation, the relationship between the first light and the second light is only described.

[0110] In step S520, the electronic device can determine the propagation angle at which the first light and the second light are diffracted and propagate in the same direction based on the diffraction path.

[0111] In one embodiment, the diffraction path may include a path along which the first light travels by being diffracted by the optical element and a path along which the second light travels by being diffracted by the optical element. The diffraction path may include multiple paths along which the first light travels and multiple paths along which the second light travels.

[0112] For example, the first light can travel in three paths after being diffracted by the optical element. The second light can travel in four paths after being diffracted by the optical element. Since the wavelengths of the first light and the second light are different, the possible values ​​of m may be different according to mathematical expression 1, and the diffraction orders may be different. For example, the propagation directions of the light of the third diffraction order of the first light and the light of the fourth diffraction order of the second light may be the same. The diffraction orders of the first light and the diffraction orders of the second light having the same propagation directions do not limit the technical idea of ​​the present disclosure. The electronic device can obtain the propagation angle of the light of the fourth diffraction order of the second light, which is the same as the propagation angle of the light of the third diffraction order of the first light. The propagation angle of the light may be determined as an angle bent based on the incident surface of the light incident perpendicularly to the optical element, but the method of calculating the propagation angle of the light is merely an example and does not limit the technical idea of ​​the present disclosure.

[0113] In one embodiment, a plurality of paths along which the first light is diffracted and propagates may have different propagation directions. A plurality of paths along which the second light is diffracted and propagates may have different propagation directions. The electronic device can determine each path whose propagation direction matches from the plurality of paths along which the first light is diffracted and propagates and the plurality of paths along which the second light is diffracted and propagates. The electronic device can determine one of the plurality of paths along which the first light is diffracted and propagates and one of the plurality of paths along which the second light is diffracted and propagates, and the propagation directions of the determined respective paths may match. The electronic device can obtain a propagation angle from each of the determined paths.

[0114] In step S530, the electronic device can obtain a plurality of combinations of a period in which the nanostructures of the optical element are arranged, an identical propagation angle of the first light and the second light, a wavelength of the first light, and a wavelength of the second light.

[0115] In one embodiment, depending on the wavelength of light incident on the optical element and the period of arrangement of nanostructures of the optical element, a possible value of m can be determined according to mathematical expression 1. That is, the diffraction order of the incident light can be determined. Furthermore, when first light and second light are incident on the optical element, the post-diffraction paths of the first light and the second light, whose propagation directions are the same, can be determined from a plurality of paths along which the first light is diffracted by the optical element and a plurality of paths along which the second light is diffracted by the optical element and a plurality of paths along which the second light is diffracted by the optical element. When first light and second light are incident on the optical element, the diffraction orders of the first light and the second light, whose propagation directions are the same, can be determined based on a plurality of paths along which the first light is diffracted by the optical element and a plurality of paths along which the second light is diffracted by the optical element and a plurality of paths along which the second light is diffracted by the optical element.

[0116] In one embodiment, the period at which the nanostructures of the optical element are arranged may be longer than the wavelength of the first light and the wavelength of the second light.

[0117] Consequently, when the first light and the second light are incident on the optical element and diffracted by the optical element, a plurality of combinations can be determined, which are composed of i) the period at which the nanostructures of the optical element are arranged, ii) the same propagation angle of the first light and the second light of the diffraction orders that propagate in the same direction after the first light and the second light are diffracted by the optical element, iii) the wavelength of the first light, and iv) the wavelength of the second light. For example, a combination that can be expressed by mathematical expression 3 can be determined.

[0118] [Equation 3]

[0119]

[0120] In mathematical expression 3, is the period in which the nanostructures of the optical element are arranged.

[0121] In mathematical expression 3, is the same propagation angle of the first and second light of the diffraction orders that propagate in the same direction after the first and second lights are diffracted by the optical element. For example, the first light may propagate through multiple paths after being diffracted by the optical element. The light of each diffraction order of the first light propagates through each path. The second light may propagate through multiple paths after being diffracted by the optical element. The light of each diffraction order of the second light propagates through each path. For example, the propagation direction of the light of the third diffraction order of the first light may be identical to the propagation direction of the light of the fourth diffraction order of the second light. At this time, It can be the propagation angle of light of the third diffraction order of the first light, and the propagation angle of light of the fourth diffraction order of the second light.

[0122] In mathematical expression 3, may be the wavelength of the first light diffracted by the optical element.

[0123] In mathematical expression 3, may be the wavelength of the second light diffracted by the optical element.

[0124] In one embodiment, the electronic device can obtain multiple combinations according to mathematical expression 3. For example, even if i) the period in which the nanostructures of the optical element are arranged, iii) the wavelength of the first light, and iv) the wavelength of the second light are determined, there can be multiple pairs of paths along which the first light and the second light proceed in the same direction after being diffracted by the optical element.

[0125] In step S540, the electronic device can obtain diffraction efficiencies of the first light and the second light, each corresponding to a plurality of obtained combinations.

[0126] In one embodiment, the diffraction efficiency may refer to the energy conservation ratio of incident light after the incident light is diffracted by the optical element. For example, one of the plurality of combinations may be a combination in which light of the third diffraction order of the first light and light of the fourth diffraction order of the second light propagate in the same direction. The electronic device may obtain the diffraction efficiency of the first light and the diffraction efficiency of the second light for the combination. Specifically, the electronic device may obtain at least one of the diffraction efficiency of the light of the third diffraction order of the first light and the diffraction efficiency of the light of the fourth diffraction order of the second light.

[0127] In one embodiment, the electronic device can determine, from among the acquired plurality of combinations, a combination that maximizes the diffraction efficiency of at least one of the first light and the second light. The electronic device can determine the period at which the nanostructures of the optical element are arranged so that the diffraction efficiency of at least one of the first light and the second light is maximized.

[0128] In one embodiment, the optical element may be configured such that, based on a plurality of paths along which the first light and the second light are diffracted and propagate, at least one of the first light and the second light has a maximum diffraction efficiency when the first light and the second light propagate in the same direction. For example, the light of the third diffraction order of the first light and the light of the fourth diffraction order of the second light may propagate in the same direction. The diffraction efficiency of at least one of the light of the third diffraction order of the first light among the plurality of paths along which the first light is diffracted and propagates and the light of the fourth diffraction order of the second light among the plurality of paths along which the second light is diffracted and propagates may be maximum.

[0129] In one embodiment, the electronic device can set a target efficiency. The electronic device can determine, from among the acquired plurality of combinations, a combination in which the diffraction efficiency of at least one of the first light and the second light matches the target diffraction efficiency. The electronic device can determine the period in which the nanostructures of the optical element are arranged so that the diffraction efficiency of at least one of the first light and the second light matches the target efficiency.

[0130] In step S550, the electronic device can update the structure of the optical element based on the obtained diffraction efficiency.

[0131] In one embodiment, the electronic device can update the structure of the optical element so that the periodicity of the arrangement of the nanostructures of the optical element is modified based on the obtained diffraction efficiency. The electronic device can modify the periodicity of the arrangement of the nanostructures of the optical element by updating the array shape of the optical element.

[0132] The term "array shape" may refer to at least one of the size, shape, and spacing of each of the plurality of nanostructures, the size distribution by position, the shape distribution by position, and the spacing distribution by position of the plurality of nanostructures with respect to the area where the meta element is located. By updating the array shape of the plurality of nanostructures, the period in which the nanostructures of the optical element are arranged may be modified. The period in which the nanostructures of the optical element are arranged may be modified depending on the combination of the plurality of nanostructures.

[0133] In one embodiment, the electronic device can update at least one of the period in which the nanostructures of the optical element are arranged, the number of nanostructures, the height of the nanostructures, and the arrangement of the nanostructures.

[0134] In one embodiment, the electronic device can determine the periodicity of the arrangement of nanostructures of the optical element based on the combination having the maximum diffraction efficiency among the obtained diffraction efficiencies. The electronic device can determine the arrangement shape of the nanostructures so as to satisfy the determined periodicity of the arrangement of nanostructures of the optical element.

[0135] In one embodiment, the electronic device can determine the periodicity of the arrangement of nanostructures of the optical element based on a combination of the obtained diffraction efficiencies having a target diffraction efficiency. The electronic device can determine the arrangement shape of the nanostructures of the optical element so as to satisfy the determined periodicity of the arrangement of nanostructures.

[0136] FIG. 6 is a flowchart illustrating an algorithm for optimizing a single optical element for guiding light according to one embodiment of the present disclosure.

[0137] For reference, Fig. 6 is a drawing for explaining in detail an algorithm for optimizing an optical element, and parts that overlap with those explained using Fig. 5 are simplified or omitted.

[0138] Referring to FIG. 6, an electronic device can update the structure of an optical element using an optimization algorithm according to steps S610 to S650. An optical element optimized by the optimization algorithm can be implemented, and an electronic device equipped with the optimized optical element can be provided.

[0139] In step S610, the electronic device may generate a random optical element. The optical element may be a diffractive element as described in FIGS. 3 and 4. The optical element may include a structure in which nanostructures are periodically and repeatedly installed on a two-dimensional plane. The random optical element may be an optical element in which nanostructures are installed according to a randomly set period. The random optical element may mean an optical element virtually designed so that nanostructures are randomly installed based on a randomly set period. The arrangement of the randomly installed nanostructures may be repeated according to the randomly set period.

[0140] In one embodiment, the electronic device can determine the number of nanostructures based on a randomly set period. The electronic device can determine the count per period of the nanostructures. In one embodiment, the electronic device can determine the height of each nanostructure.

[0141] In one embodiment, an electronic device may generate a random optical element based on a random number function. For example, the electronic device may use the random number function to determine numerical values ​​such as the period at which nanostructures of the random optical element are arranged, the height, spacing, and thickness of the nanostructures.

[0142] In step S620, the electronic device may filter random optical elements based on process conditions. The process conditions may be conditions that take into account realistic design possibilities of the optical elements.

[0143] For example, it may be difficult to form a nanostructure having a thickness less than a threshold value due to the process limitations of the nanostructure. The electronic device can obtain the thicknesses of a plurality of nanostructures included in the random optical element. The electronic device can determine whether the thicknesses of the plurality of nanostructures exceed the threshold value. If the thickness of at least one of the plurality of nanostructures does not exceed the threshold value, the electronic device can erase the random optical element including at least one of the plurality of nanostructures. Returning to step S610, the electronic device can generate a new random optical element.

[0144] The electronic device may determine that the process condition is satisfied if the thickness of at least one of the plurality of nanostructures exceeds a threshold value. The electronic device may perform the following operation according to step S630.

[0145] As another example, it may be difficult to form an arrangement of nanostructures with spacings below a threshold due to the processing limitations of nanostructures. An electronic device can acquire the spacing between multiple nanostructures included in a random optical element. The electronic device can determine whether the spacing between the multiple nanostructures exceeds a threshold.

[0146] The electronic device may determine that the process condition is not satisfied if the spacing between at least one pair of adjacent nanostructures among the plurality of nanostructures does not exceed a threshold value. The electronic device may erase a random optical element including at least one pair of adjacent nanostructures among the plurality of nanostructures. Returning to step S610, the electronic device may generate a new random optical element.

[0147] The electronic device may determine that the process condition is satisfied if the spacing between at least one pair of adjacent nanostructures among the plurality of nanostructures exceeds a threshold value. The electronic device may perform the following operation according to step S630.

[0148] In one embodiment, process conditions may be set by the user. In addition, threshold values ​​for the thickness or spacing of the nanostructures may also be set by the user, without limiting the technical concept of the present disclosure.

[0149] In step S630, the electronic device may filter random optical elements based on robustness. In the present disclosure, robustness may refer to the ability of an optical system or optical element to remain robust or stable against changes or external influences during a manufacturing process. Robustness may refer to the ability of an optical element to stably maintain its function despite small changes (perturbations) so that small structural changes in the optical element occurring during the manufacturing process do not cause significant (critical) differences in the diffraction angle, diffraction order, etc. of incident light diffracted by the optical element.

[0150] In one embodiment, an electronic device can obtain a comparative optical element by applying a small perturbation to a random optical element. A small perturbation may mean a minute change in the structure of the optical element. For example, the random optical element may include a nanostructure formed with a height of 10 nm, and the comparative optical element to which a small perturbation has been applied may include a nanostructure formed with a height of 10.1 nm. The minute degree of change is described as 1% as an example, but the minute degree may be set differently depending on the user's intention, the performance of the optimization algorithm, the required accuracy, etc., and does not limit the technical idea of ​​the present disclosure.

[0151] An electronic device can input light into a random optical element and a comparative optical element, and obtain the diffraction efficiency, diffraction angle, etc. of the incident light. Since the comparative optical element is obtained by applying a small change to the random optical element, the diffraction efficiency and diffraction angle of light diffracted by the comparative optical element may be similar to the diffraction efficiency and diffraction angle of light diffracted by the random optical element.

[0152] An electronic device can obtain the difference between the diffraction efficiency and diffraction angle of light diffracted by a comparison optical element and the diffraction efficiency and diffraction angle of light diffracted by a random optical element. The electronic device can determine whether the difference between the obtained diffraction efficiency and diffraction angle exceeds a threshold value.

[0153] If the difference between the obtained diffraction efficiency and the diffraction angle exceeds a threshold, the electronic device can determine that the robustness of the random optical element is not secured. The electronic device can then eliminate the random optical element with insufficient robustness. Returning to step S610, the electronic device can generate a new random optical element.

[0154] The electronic device can determine that the robustness of the random optical element is secured if the difference between the obtained diffraction efficiency and the diffraction angle does not exceed a threshold value. The electronic device can perform the following operation according to step S640.

[0155] In step S640, the electronic device can obtain the diffraction efficiency of light incident on the random optical element. The electronic device can diffract the first and second lights incident on the random optical element at the same angle into multiple paths, respectively, using the random optical element. The electronic device can obtain the diffraction paths along which the first and second lights respectively proceed, using the random optical element.

[0156] The diffraction path may include multiple paths along which a first light incident on a random optical element is diffracted and progresses, and multiple paths along which a second light incident on the random optical element is diffracted. The electronic device may determine, based on the diffraction path, the propagation angles along which the first light and the second light are diffracted and progress in the same direction.

[0157] The electronic device can obtain a plurality of combinations of a period in which the nanostructures of the optical element are arranged, the same propagation angles of the first light and the second light, the wavelength of the first light, and the wavelength of the second light. The electronic device can obtain diffraction efficiencies of the first light and the second light, each corresponding to the plurality of combinations of acquisitions. The electronic device can obtain diffraction efficiencies of light of diffraction orders that propagate in a first direction after the first light is diffracted by the random optical element, and diffraction efficiencies of light of diffraction orders that propagate in the first direction after the second light is diffracted by the random optical element.

[0158] Step S640 may include those described using steps S510 to S540 described in FIG. 5, and any redundant descriptions are simplified or omitted.

[0159] In step S650, the electronic device can update the structure of the optical element. The electronic device can update the structure of the optical element based on the diffraction efficiency of the acquired light. For example, the electronic device can change the periodic arrangement of the nanostructures of the optical element so as to maximize the diffraction efficiency of the acquired light.

[0160] The description related to step S650 is the same as that described using step S550 of FIG. 5, so any duplicate content is simplified or omitted.

[0161] In one embodiment, the operations according to steps S610 to S650 may be repeatedly performed until the structure of the random optical element is optimized. For example, if the structure of the random optical element is not changed even if the electronic device updates the structure of the random optical element based on the optical diffraction efficiency in step S650, the repeated performance of steps S610 to S650 may be stopped.

[0162] FIG. 7 is a flowchart illustrating a method for ensuring robustness to optimize an optical element according to one embodiment of the present disclosure.

[0163] Anything overlapping with what has been described using FIGS. 5 and 6 will be simplified or omitted. Specifically, the description shown in FIG. 7 specifically describes step S540, and also specifically describes steps S630 and S640 of FIG. 6.

[0164] Referring to FIG. 7, step S540 of FIG. 5 may include steps S710, S720, and S730.

[0165] In one embodiment, the optical element may include a first optical element and a second optical element. The first optical element may be a reference optical element, and the second optical element may refer to an optical element in which a nanostructure of the first optical element is perturbed. The first optical element may correspond to the random optical element described in FIG. 6. The second optical element may correspond to the comparative optical element described in FIG. 6.

[0166] In step S710, the electronic device can obtain a first diffraction efficiency of the first light diffracted by the first optical element and a second diffraction efficiency of the first light diffracted by the second optical element. For example, the first light can be diffracted through multiple paths by the first optical element. The electronic device can obtain a first diffraction efficiency of the light of the fourth diffraction order of the first light diffracted by the first optical element. The electronic device can obtain a second diffraction efficiency of the light of the fourth diffraction order of the first light diffracted by the second optical element.

[0167] For convenience of explanation, the explanation is based on the first light, but the same applies to the second light.

[0168] In step S720, the electronic device can determine whether the difference between the first diffraction efficiency and the second diffraction efficiency exceeds a threshold value.

[0169] If the difference in the obtained diffraction efficiency exceeds a threshold, the electronic device can determine that the robustness of the optical element is not secured. The electronic device can change the structure of the optical element. The electronic device can eliminate the optical element that lacks robustness. Returning to step S510, the electronic device can re-acquire the diffraction paths along which the first and second rays of light respectively proceed based on a new single optical element.

[0170] The electronic device may determine that the robustness of the optical element is secured if the difference in the obtained diffraction efficiencies does not exceed a threshold value. In step S730, the electronic device may obtain an average of the first diffraction efficiency and the second diffraction efficiency. Subsequently, step S550 may be performed. The electronic device may update the structure of the optical element based on the average of the obtained first diffraction efficiency and the second diffraction efficiency.

[0171] FIG. 8 is a schematic diagram illustrating an electronic device having an optical element according to one embodiment of the present disclosure.

[0172] Referring to FIG. 8, an electronic device according to one embodiment may include a waveguide (100) according to the above-described embodiments. The waveguide (100) may include an input-coupling element (200) and an output-coupling element (300). The drawing illustrates a case where the output-coupling element (300) is provided on the second surface (100b) of the waveguide (100), but may be provided on the first surface (100a) of the waveguide (100) or on both surfaces (i.e., the first surface (100a) and the second surface (100b)) of the waveguide (100). The waveguide (100) may further include an expanding element that expands the pupil of the input light. The expansion element may be positioned between the input-coupling element (200) and the output-coupling element (300), may overlap with the output-coupling element (300) in some area, or may overlap with the output-coupling element (300) in the same area. The input-coupling element (200), the output-coupling element (300), or the expansion element may be an optical element according to the embodiments described above. The optical element may be a metaelement, and the metaelement is an element having a metasurface structured with a pattern of a size smaller than the wavelength of incident light (i.e., a surf wavelength), for example, a metagrating or a metalens having a pattern of a size smaller than the wavelength of incident light, but is not limited thereto.

[0173] In one embodiment, the waveguide (100) may include a single substrate (20 in FIG. 1) that guides multiple lights.

[0174] In one embodiment, the input-coupling element (200) may be positioned on the waveguide (100). The input-coupling element (200) may be configured to allow external light to be incident into the substrate. The input-coupling element (200) may be configured with an optical element according to the embodiments described above. The input-coupling element (200) may diffract a plurality of incident lights so that they propagate in the same direction. The diffracted plurality of incident lights may propagate into the waveguide (100).

[0175] In one embodiment, the output-coupling element (300) may be positioned on the waveguide (100). The output-coupling element (300) may be configured to output external light from the substrate. The output-coupling element (300) may be configured with an optical element according to the embodiments described above. The output-coupling element (300) may diffract a plurality of incident lights so that they exit from the substrate. The diffracted plurality of incident lights may propagate outside the substrate.

[0176] In one embodiment, at least one of the input-coupling element (200) and the output-coupling element (300) may include a single optical element. The optical element may be an element in which nanostructures are arranged according to a first period on a two-dimensional plane. The optical element may be configured to diffract first light and second light incident at the same angle into a plurality of paths, respectively. The optical element may be an optical element according to the embodiments described above. The first light and the second light may each be one of red light, green light, and blue light.

[0177] The electronic device may further include a display unit (400) that emits light of an image (e.g., a virtual object). The light emitted by the display unit (400) is output to a target area through a waveguide (100). The input-coupling element (200) and the output-coupling element (300) may guide the light output from the display unit (400) to the target area.

[0178] Information processing and image formation for the display unit (400) may be performed directly in a computer of the electronic device itself, or may be performed in an external electronic device such as a smart phone, tablet, computer, laptop, or any other intelligent (smart) device connected to the electronic device. Signal transmission between the electronic device and the external electronic device may be performed via wired communication and / or wireless communication. The electronic device may be powered by at least one of a built-in power source (rechargeable battery) and an external device or an external power source.

[0179] In one embodiment, the electronic device may be an augmented reality device. In the present disclosure, the term 'augmented reality device' refers to a device capable of expressing augmented reality, and includes not only augmented reality glasses in the shape of glasses worn by a user on the face, but also a head-mounted display (HMD), an augmented reality helmet, a head-up display (HUD), etc. worn on the head.

[0180] FIG. 9 schematically illustrates an augmented reality device according to one embodiment.

[0181] Referring to FIG. 9, the augmented reality device may use the electronic device described with reference to FIG. 8 instead of the lens as the left-eye element and the right-eye element. That is, the augmented reality device may include an input-coupling element (200), an output-coupling element (300 in FIG. 8), a waveguide (100), and a display unit (400) according to the above-described embodiments for the left-eye element and the right-eye element, respectively. Each waveguide (100) may be fixed to a frame (90). Each display unit (400) may be positioned near the temple of the user's head and fixed to the frame (90). Each waveguide (100) includes an input-coupling element (200) for inputting light from the display unit (400) to the waveguide (100). Each waveguide (100) is positioned so that the area having the output-coupling element (300 in FIG. 8) faces the corresponding eye of the user (wearer). The display unit (400) is positioned opposite to the input-coupling element (200).

[0182] According to an embodiment of the present disclosure, a method may include a step of diffracting first light and second light incident on the optical element at the same angle into a plurality of paths using a single optical element in which nanostructures are arranged according to a first period on a two-dimensional plane, thereby obtaining diffraction paths along which the first light and the second light respectively proceed. The method may include a step of determining, based on the diffraction paths, a propagation angle at which the first light and the second light proceed by being diffracted in the same direction. The method may include a step of obtaining a plurality of combinations consisting of a first period, a propagation angle, a wavelength of the first light, and a wavelength of the second light. The method may include a step of obtaining diffraction efficiencies of the first light and the second light, each corresponding to the obtained plurality of combinations. The method may include a step of updating a structure of the optical element based on the obtained diffraction efficiencies.

[0183] In one embodiment, the first light and the second light may each be one of red light, green light, and blue light.

[0184] In one embodiment, the nanostructure may include a plurality of rods that repeat according to a first cycle. The plurality of rods may include a first rod formed with at least a first height and a first width, and a second rod formed with a second height and a second width.

[0185] In one embodiment, the plurality of loads may further include a third load. The first spacing between the first load and the second load and the second spacing between the second load and the third load may be different from each other.

[0186] In one embodiment, the step of obtaining the diffraction efficiency of the first light and the second light may include the step of determining, among the plurality of combinations obtained, a combination in which the diffraction efficiency of at least one of the first light and the second light is maximized.

[0187] In one embodiment, the step of obtaining the diffraction efficiency of the first light and the second light may include the step of setting the get efficiency. The step of obtaining the diffraction efficiency of the first light and the second light may include the step of determining, among the obtained plurality of combinations, a combination in which the diffraction efficiency of at least one of the first light and the second light matches the target efficiency.

[0188] In one embodiment, the step of updating the structure of the optical element may include the step of updating at least one of a first period of the optical element, a number of nanostructures, a height of the nanostructures, and an arrangement of the nanostructures.

[0189] In one embodiment, the optical element may include a first optical element and a second optical element having a perturbation applied to the nanostructure of the first optical element. The step of obtaining the diffraction efficiency of the first light and the second light may include the step of obtaining an average of the first diffraction efficiency of the first light diffracted by the first optical element and the second diffraction efficiency of the first light diffracted by the second optical element.

[0190] In one embodiment, the method may further include a step of changing the structure of the optical element when the difference between the first diffraction efficiency and the second diffraction efficiency exceeds a threshold value.

[0191] In one embodiment, the method may further include a step of updating the structure of the optical element based on an average of the first diffraction efficiency and the second diffraction efficiency, if the difference between the first diffraction efficiency and the second diffraction efficiency does not exceed a threshold value.

[0192] In one embodiment, the first period may be longer than the wavelength of the first light and the wavelength of the second light.

[0193] An electronic device according to an embodiment of the present disclosure may include a memory, at least one processor, a waveguide, an input coupling element, and an output coupling element. The memory may store one or more instructions. At least one processor may execute one or more instructions stored in the memory. The waveguide may include a single substrate that guides a plurality of lights. The input coupling element may be positioned on the substrate and configured to allow external light to be incident into the substrate. The output coupling element may be positioned on the substrate and configured to allow external light to be output from the substrate. At least one of the input coupling element and the output coupling element may include a single optical element. The optical element may be configured to diffract first and second lights incident at the same angle into a plurality of paths, respectively, in which nanostructures are arranged in a first period on a two-dimensional plane. At least one processor can obtain a diffraction path along which a first light and a second light propagate using an optical element by executing one or more instructions. At least one processor can determine a propagation angle along which the first light and the second light propagate by being diffracted in the same direction based on the diffraction path. At least one processor can obtain a plurality of combinations consisting of a first period, a propagation angle, a wavelength of the first light, and a wavelength of the second light. At least one processor can obtain a diffraction efficiency of the first light and the second light corresponding to each of the obtained plurality of combinations. At least one processor can update a structure of the optical element based on the obtained diffraction efficiency.

[0194] In one embodiment, the first light and the second light may each be one of red light, green light, and blue light.

[0195] In one embodiment, the optical element may be configured such that at least one of the first light and the second light has maximum diffraction efficiency when the first light and the second light propagate in the same direction, based on a plurality of paths along which the first light and the second light respectively diffract and propagate.

[0196] In one embodiment, the nanostructure may include a plurality of rods that repeat according to a first cycle. The plurality of rods may include a first rod formed with at least a first height and a first width, and a second rod formed with a second height and a second width.

[0197] In one embodiment, the plurality of loads may further include a third load. The first spacing between the first load and the second load and the second spacing between the second load and the third load may be different from each other.

[0198] In one embodiment, the first period may be longer than the wavelength of the first light and the wavelength of the second light.

[0199] In one embodiment, the electronic device may further include a display unit that outputs light of an image. The input-coupling element and the output-coupling element guide the light output from the display unit to a target area, wherein the target area may be a user's eye motion box.

[0200] In one embodiment, the device may include a left-eye element and a right-eye element corresponding to the user's left and right eyes. Each of the left-eye element and the right-eye element may include a display unit, a waveguide, an input-coupling element, and an output-coupling element.

[0201] A computer-readable recording medium having recorded thereon a program for performing a method according to an embodiment of the present disclosure on a computer may be provided.

[0202] A device-readable storage medium may be provided in the form of a non-transitory storage medium. Here, the term "non-transitory storage medium" simply means a tangible device that does not contain signals (e.g., electromagnetic waves). This term does not distinguish between cases where data is permanently stored in the storage medium and cases where data is temporarily stored. For example, a "non-transitory storage medium" may include a buffer in which data is temporarily stored.

[0203] According to one embodiment, the method according to various embodiments disclosed in the present document may be provided as included in a computer program product. The computer program product may be traded as a product between a seller and a buyer. The computer program product may be distributed in the form of a machine-readable storage medium (e.g., compact disc read-only memory (CD-ROM)), or may be distributed online (e.g., downloaded or uploaded) through an application store or directly between two user devices (e.g., smartphones). In the case of online distribution, at least a portion of the computer program product (e.g., a downloadable app) may be temporarily stored or temporarily generated in a machine-readable storage medium, such as the memory of a manufacturer's server, an application store's server, or an intermediary server.

Claims

1. A step of diffracting first and second lights incident at the same angle to the optical element into a plurality of paths using a single optical element in which nanostructures are arranged according to a first period on a two-dimensional plane, thereby obtaining diffraction paths along which the first and second lights respectively proceed; A step of determining a propagation angle at which the first light and the second light are diffracted and propagate in the same direction based on the diffraction path; A step of obtaining a plurality of combinations consisting of the first period, the progression angle, the wavelength of the first light, and the wavelength of the second light; A step of obtaining the diffraction efficiency of the first light and the second light, each corresponding to the obtained plurality of combinations; and A method comprising a step of updating the structure of the optical element based on the obtained diffraction efficiency.

2. In paragraph 1, A method wherein the first light and the second light are each one of red light, green light, and blue light.

3. In either of paragraphs 1 and 2, The above nanostructure comprises a plurality of rods that are repeated according to the first cycle, A method wherein the plurality of loads comprises a first load formed with at least a first height and a first width and a second load formed with a second height and a second width.

4. In paragraph 3, The above plurality of loads further includes a third load, A method wherein the first interval between the first load and the second load and the second interval between the second load and the third load are different from each other.

5. In any one of paragraphs 1 to 4, The step of obtaining the diffraction efficiency of the first light and the second light is: A method comprising the step of determining, among the plurality of combinations obtained above, a combination in which the diffraction efficiency of at least one of the first light and the second light is maximized.

6. In any one of paragraphs 1 to 4, The step of obtaining the diffraction efficiency of the first light and the second light is: Step of setting target efficiency; and A method comprising the step of determining, among the plurality of combinations obtained, a combination in which the diffraction efficiency of at least one of the first light and the second light matches the target efficiency.

7. In any one of paragraphs 1 to 6, The step of updating the structure of the optical element is: A method comprising the step of updating at least one of the first period of the optical element, the number of the nanostructures, the height of the nanostructures, and the arrangement of the nanostructures.

8. In any one of paragraphs 1 to 7, A method wherein the first period is longer than the wavelength of the first light and the wavelength of the second light.

9. Memory that stores one or more instructions; At least one processor executing one or more instructions stored in the memory; A waveguide (100) comprising a single substrate for guiding multiple lights; An input-coupling element (200) positioned on the substrate and configured to allow external light to enter the substrate; and An output-coupling element (300) positioned on the substrate and configured to output the external light from the substrate, At least one of the input-coupling element and the output-coupling element comprises a single optical element, wherein the optical element is configured to diffract first light and second light incident at the same angle into a plurality of paths, respectively, with the nanostructures arranged in a first period on a two-dimensional plane. The at least one processor, by executing the one or more instructions, Using the optical element, the first light and the second light are each obtained as a diffraction path along which they proceed, Based on the above diffraction path, the propagation angle at which the first light and the second light are diffracted and propagate in the same direction is determined, Obtaining a plurality of combinations consisting of the first period, the progression angle, the wavelength of the first light, and the wavelength of the second light, Obtain the diffraction efficiency of the first light and the second light corresponding to each of the obtained plurality of combinations, An electronic device that updates the structure of the optical element based on the obtained diffraction efficiency.

10. In paragraph 9, An electronic device wherein the first light and the second light are each one of red light, green light, and blue light.

11. In any one of the clauses 9 to 10, An electronic device wherein the optical element is configured such that at least one of the first light and the second light has maximum diffraction efficiency when the first light and the second light propagate in the same direction based on a plurality of paths along which the first light and the second light are diffracted and propagate.

12. In any one of the clauses 9 to 11, The above nanostructure comprises a plurality of rods that are repeated according to the first cycle, An electronic device wherein the plurality of loads includes a first load formed with at least a first height and a first width and a second load formed with a second height and a second width.

13. In paragraph 12, The above plurality of loads further includes a third load, An electronic device wherein a first gap between the first load and the second load and a second gap between the second load and the third load are different from each other.

14. In any one of the clauses 9 to 13, An electronic device wherein the first period is longer than the wavelength of the first light and the wavelength of the second light.

15. A computer-readable recording medium having recorded thereon a program for performing the method of any one of clauses 1 to 8 on a computer.

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