CN117806052A

CN117806052A - Meta-optical device and electronic device including the same

Info

Publication number: CN117806052A
Application number: CN202311278398.0A
Authority: CN
Inventors: 鲁埈锡; 金炅台; 金礼瑟; 尹珠煐; 金仁基
Original assignee: Academy Industry Foundation of POSTECH
Current assignee: Academy Industry Foundation of POSTECH
Priority date: 2022-09-30
Filing date: 2023-09-28
Publication date: 2024-04-02

Abstract

A meta-optical device for forming structured light by modulating incident light having a preset wavelength, comprising a plurality of super cells, each super cell comprising a plurality of nanostructures of shape size smaller than Yu Yushe wavelength, and the shape and arrangement of the plurality of nanostructures being designed to form the structured light into a pattern of dots having a viewing angle of greater than 160 ° in horizontal and vertical directions.

Description

Meta-optical device and electronic device including the same

Cross Reference to Related Applications

The present application is based on 35u.s.c. ≡119 and claims priority from korean patent application 10-2022-012588 filed at 9/30/2022 and korean patent application 10-2023-0055011 filed at 26/2023, 4/2023, the disclosures of which are incorporated herein by reference in their entireties.

Technical Field

The inventive concept relates to a meta-optical device (meta optical device) and an electronic device comprising the meta-optical device.

Background

The invention is funded by three-star research fund and hatching center of three-star electronics, with the project number of SRFC-IT1901-52.

Recently, object recognition of people and other objects has been performed using three-dimensional sensing technology that uses structured light for precise three-dimensional shape recognition through depth recognition.

The structured light is light having a specific preset pattern, and when the patterned light is reflected from the three-dimensional object, a pattern change occurs. Depth information about the object to which the structured light is irradiated may be obtained from such pattern change.

In order to generate structured light, a Diffractive Optical Element (DOE) is generally used, but the diffraction efficiency of the DOE decreases with an increase in the diffraction angle. Therefore, it is difficult for a depth recognition system using a DOE as an emitter to have a wide viewing angle. Accordingly, various ways are required to form structured light having a wide viewing angle.

Disclosure of Invention

The present inventive concept provides a meta-optical device and an electronic device including the same.

According to an aspect of the inventive concept, there is provided a meta-optical device for forming structured light by modulating incident light having a preset wavelength, the meta-optical device comprising a plurality of super-cells, each super-cell comprising a plurality of nanostructures, each nanostructure having a shape size smaller than the preset wavelength, wherein the shapes and arrangements of the plurality of nanostructures are configured to form the structured light into a dot pattern having a viewing angle of greater than 160 ° in horizontal and vertical directions.

In an example embodiment, the shape and arrangement of the plurality of nanostructures may be designed such that the ratio of the intensity of the mth order diffracted light to the intensity of the first order diffracted light is greater than about 50%. Herein, m may represent the maximum number of integers less than (n×p/λ), the nanostructures may be arranged in an n×n matrix in a single super cell, and P may represent the arrangement pitch of the nanostructures in each super cell.

The phase profile generated by each of the plurality of super cells may be represented as a second function obtained by iterative fourier transformation of a first function defined in a spatial frequency domain, and the first function may be defined as having a value of 1 within a circle having a radius of 1/λ, having a value of 0 in a remaining space in the spatial frequency domain defined by (fx, fy) satisfying the condition 1/(2P) fx 1/(2P), 1/(2P) fy 1/(2P), where P represents an arrangement pitch of the nanostructures, and λ represents a preset wavelength.

The arrangement pitch of the plurality of nanostructures may be less than or equal to λ/2 (λ is a preset wavelength).

Each of the plurality of nanostructures may be shaped as a pillar having a cross-section defined by a major axis and a minor axis, and a major axis direction of each of the plurality of nanostructures may be determined by a relative position of the nanostructures in each of the plurality of super cells.

The meta-optical device may further include a support layer supporting the plurality of nanostructures.

Each of the plurality of nanostructures may include a nanocomposite having a resin material and nanoparticles dispersed in the resin material.

The meta-optical device may be manufactured by using a flexible mold having an inverse pattern of the shape of the plurality of nanostructures.

The support layer may comprise a transparent plastic material having a curved shape.

According to another aspect of the inventive concept, there is provided a meta-optical device comprising a plurality of super cells, each super cell comprising a plurality of nanostructures and being periodically arranged, wherein a phase profile generated by each of the plurality of super cells is represented as a second function obtained by an iterative fourier transform of a first function defined in a spatial frequency domain, and the first function may be defined as having a value of 1 within a circle having a radius (sin ω)/λ, and having a value of 0 in a remaining space in a spatial frequency domain defined by (fx, fy) satisfying a condition of 1/(2P) fax 1/(2P), 1/(2P) fy 1/(2P), where ω represents a value of less than or equal to pi/2, P represents an arrangement pitch of the nanostructures, and λ represents a preset wavelength.

ω may be pi/2 radians.

The arrangement pitch of the plurality of nanostructures may be less than or equal to λ/2.

According to another aspect of the inventive concept, there is provided a meta-optical device comprising a plurality of super cells, each super cell comprising a plurality of nanostructures arranged periodically, wherein a phase profile generated by each of the plurality of super cells is represented as a second function obtained by iterative fourier transformation of a first function defined in a spatial frequency domain, and the first function may be defined as a first function defined as a second function defined in a spatial frequency domain, and the second function may be defined as a second function defined in a spatial frequency domain ₁ ) The circle of/lambda has a value of 1 and an inner diameter of (sin omega ₂ ) And has an outer diameter of (sin omega) ₃ ) At least the ring of #/λ has a value of 1 and has a value of 0 in the remaining space in the spatial frequency domain defined by (fx, fy) satisfying the conditions 1/(2P). Ltoreq.fx.ltoreq.1/(2P), 1/(2P). Ltoreq.fy.ltoreq.1/(2P), where ω ₁ 、ω ₂ And omega ₃ With omega ₁ <ω ₂ <ω ₃ And the relation of pi/2 is not more than, P represents the arrangement interval of the nano structures, and lambda represents the preset wavelength.

According to another aspect of the inventive concept, there is provided an electronic device comprising: a light source that generates source light; any one of the meta-optical devices configured to form a structured light from a source light and irradiate an object; a first sensor and a second sensor spaced apart from each other with the meta-optical device therebetween, the first sensor and the second sensor configured to detect light reflected from the object; and a processor configured to analyze signals detected from the first sensor and the sensor and calculate depth information about the object.

The electronic device may further comprise an image display unit displaying the image, wherein the processor is further configured to generate a depth image from the depth information, generate an additional image related to the depth image, and control the image display unit to display the depth image and the additional image.

The electronic device may comprise an eye-wearable apparatus.

Drawings

The embodiments will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a flow chart of a meta-optical device design method according to an embodiment;

FIG. 2 is a flow chart of a detailed process of setting a phase profile for structured light having a high viewing angle in a meta-optical device design method according to an embodiment;

FIG. 3A is a diagram illustrating a first function defined in the spatial frequency domain according to an embodiment of a meta-optical device design method;

FIG. 3B is a diagram showing a second function obtained by Fourier transforming the first function in the spatial frequency domain, according to an embodiment of the meta-optical device design method;

FIG. 3C is a diagram illustrating a function defining an array of supercells for use in a meta-optic design method according to an embodiment;

FIG. 3D is a diagram illustrating operations for generating a phase profile to be applied to an entire spatial domain according to an embodiment of a meta-optical device design method;

FIG. 3E is a diagram illustrating a phase profile generated in accordance with an embodiment of a meta-optical device design method;

FIG. 4 is a diagram illustrating shape parameters and efficiency according to shape parameters of a nanostructure applied to a meta-optical device according to an embodiment of a meta-optical device design method;

fig. 5A and 5B are a plan view and a sectional view, respectively, showing a schematic structure of a meta-optical device according to an embodiment;

FIG. 6 is a micrograph showing a meta-optical device manufactured by a meta-optical device design method according to an embodiment;

FIG. 7 is a graph showing the relationship of diffracted light intensity to diffraction order at each arrangement pitch of nanostructures in a meta-optical device according to an embodiment;

fig. 8 is a view showing a plurality of distribution diagrams of structured light in the spatial frequency domain in each case where the number of super cells is different in the meta optical device according to the embodiment;

FIG. 9 is a diagram illustrating another example of a first function defined in the spatial frequency domain according to an embodiment of a meta-optical device design method;

FIG. 10 is a diagram illustrating another example of a first function defined in the spatial frequency domain according to an embodiment of a meta-optical device design method;

fig. 11A to 11D are views illustrating a method of manufacturing a meta-optical device according to an embodiment;

FIG. 12 is a photograph showing a meta-optical device based on a curved plastic implementation according to an embodiment;

fig. 13 is a view showing a schematic structure of an electronic device according to an embodiment;

FIG. 14 is a diagram showing the structure of an empirical depth identification system using meta-optical devices according to an embodiment;

FIGS. 15A and 15B are photographs showing, from the front and side, structured light formed in the depth recognition system shown in FIG. 14;

FIG. 16 is a depth map showing the depths of two objects obtained by the depth recognition system shown in FIG. 14; and

fig. 17 is a view showing a schematic structure of an electronic device according to another embodiment.

Detailed Description

Hereinafter, various embodiments of the inventive concept are described in detail with reference to the accompanying drawings. The described embodiments are merely exemplary and various modifications of the embodiments are possible. In the following drawings, like reference numerals denote like parts, and the size of each part in the drawings may be exaggerated for clarity and convenience of explanation.

Hereinafter, what is described as "upper" or "over" may include not only directly contacted over but also non-contacted over.

Terms such as first and second may be used to describe various components, but are used only for the purpose of distinguishing one component from another. These terms do not limit the difference in materials or structures of the components.

Singular expressions may include plural expressions unless the context clearly indicates otherwise. Furthermore, when a portion "comprises" any component, this means that other components may be further included, rather than excluded, unless stated otherwise.

Furthermore, the terms "..part of the description and" module "refer to a unit that processes at least one function or operation, which may be implemented as hardware or software or a combination of hardware and software.

The use of the terms "above" and similar referents may correspond to the singular and plural, respectively.

The operations constituting the method may be performed in an appropriate order unless explicitly mentioned that the operations should be performed in the order described. Further, the use of all exemplary terms (e.g., etc.) is merely to explain the technical idea in detail, and the scope of the claims is not limited by these terms unless limited by the claims.

FIG. 1 is a flow chart of a meta-optical device design method according to an embodiment.

The meta-optical device may be a diffraction device comprising nanostructures with sub-wavelength dimensions. Sub-wavelength refers to a value smaller than the wavelength of the incident light to be modulated, or a value smaller than the center wavelength of the wavelength band of the incident light. The shape and arrangement of the nanostructures in the meta-optical device may be set to modulate the incident light into a desired shape. Sub-wavelength nanostructures may also be referred to as meta-atoms, and arrays in which the nanostructures are arranged may also be referred to as meta-surfaces.

The nanostructures may have a refractive index different from the surrounding material, and the refractive index profile may be formed by the shape and arrangement of the nanostructures. The shape of the wavefront is a surface defined by connecting points in the optical path that have the same phase, the shape of the wavefront being different before and after undergoing the refractive index profile, that is, the phase of the light after passing through the meta-optical device may be different from the phase of the light before the light is incident on the meta-optical device. The phase difference of the light is denoted as a phase delay and may be displayed as a phase delay profile with a position dependent distribution. Hereinafter, the phase of the meta-optical device refers to a phase delay, i.e., a relative phase with respect to the phase of the incident light before the incident light is incident on the meta-optical device, and the phase delay may be used interchangeably. Such as phase, phase delay profile, phase distribution function, etc., may be used together with the same meaning.

The meta-optic may exhibit various optical properties according to a phase profile indicated by the meta-optic. In an embodiment, the meta-optical device may be designed with a phase profile of structured light capable of forming a high viewing angle. The phase profile may achieve a viewing angle of about 180 ° in the range of about-90 ° to about 90 ° in the vertical and horizontal directions. However, the inventive concept is not so limited and the phase profile may be designed to achieve a desired viewing angle of the structured light.

In the meta-optical device designing method according to the embodiment, a phase profile may be first set to form structured light having a high viewing angle (S100).

Then, in order to generate a set phase profile by using the nanostructure, a phase delay value and a phase delay efficiency may be analyzed according to various shape parameters of the nanostructure (S200). The set phase profile may be generated by using nanostructures having shape dimensions of sub-wavelengths. In other words, the degree of retardation of the phase of light passing through the nanostructure can be controlled by adjusting the shape parameters of the nanostructure. The shape parameters of the nanostructures may also be related to the efficiency of the delay phase as desired. From the parameter data, details of the nanostructure to be applied to the meta-optical device may be determined.

Then, a nanostructure having a shape suitable for a specific phase may be arranged at each position corresponding to the phase profile (S300).

A detailed description about a meta-optical device design method is described with reference to fig. 2 to 4.

Fig. 2 is a flowchart of a detailed process of setting a phase profile for structured light having a high viewing angle in a meta-optical device design method according to an embodiment.

First, a first function may be defined and set in a spatial frequency domain (S110). Fig. 3A is a view showing a first function defined in a spatial frequency domain according to an embodiment of a meta-optical device design method. The first function is a function set in the spatial frequency domain so that light of various diffraction orders that can propagate can have uniform intensity. The first function may be defined as having a value of 1 within a circle having a radius of 1/λ and a value of 0 in the remaining space of the maximum resolvable spatial frequency domain, the maximum resolvable spatial frequency domain being a spatial frequency domain defined by (fx, fy) satisfying the condition 1/(2P). Ltoreq.fx.ltoreq.1/(2P), 1/(2P). Ltoreq.fy.ltoreq.1/(2P). Here, greek letter λ denotes a wavelength of incident light, capital letter P denotes a pixel pitch of a spatial domain, and the pixel pitch corresponds to an arrangement pitch of nanostructures to be arranged in the spatial domain.

Next, the first function may be transformed by fourier transformation, thereby setting a second function as a unit phase distribution (S120). The unit phase distribution refers to the phase profile of the super cell as a basic unit repeatedly arranged in the spatial domain. Fig. 3B is a view showing a second function obtained by fourier transforming the first function in the spatial frequency domain according to an embodiment of the meta-optical device design method. An Iterative Fourier Transform Algorithm (IFTA) may be used for the fourier transform described above. Referring to fig. 3B, assuming that a single super cell is composed of a plurality of pixels arranged in an n×n matrix at a pixel pitch P, a plurality of phase values may be allocated at each position corresponding to the spatial domain of the super cell in a range of about 0 to about 2 pi.

Then, by convolution of the second function and the super cell arrangement function, a phase profile applied to the entire spatial domain can be generated (S140).

Fig. 3C is a view showing a function defining a super cell array used when the meta-optical device design method according to an embodiment is performed, and fig. 3D is a view showing an operation for generating a phase profile to be applied to the entire spatial domain according to an embodiment of the meta-optical device design method. Fig. 3E is a diagram illustrating a phase profile generated according to an embodiment of a meta-optical device design method.

The super cell layout function shown in fig. 3C may be represented by a 2D dirac comb function. Referring to fig. 3C, the super cell arrangement function may be represented by a plurality of super cells arranged in an n×n matrix at an arrangement pitch nP. The phase profile shown in fig. 3E may be generated by the convolution operation shown in fig. 3D. A plurality of phase values to be realized over the whole spatial domain, i.e. at each position of the metasurface, may be set according to the generated phase profile.

The phase profile shown in fig. 3E may be implemented in various forms of meta-surfaces, i.e. the shape and arrangement of the nanostructures. Hereinafter, a meta-optical device whose meta-surface is realized by a phase profile is provided, but the meta-optical device according to the embodiment is not limited to the illustrated structure. In other words, the phase profile shown in fig. 3E may be implemented in various ways, in addition to the shape and arrangement of the nanostructures shown below.

Fig. 4 is a view showing shape parameters of a nanostructure to be applied to a meta-optical device and efficiency according to the shape parameters according to an embodiment of a meta-optical device design method.

One approach is known as geometric phase or Pancharatnam-Berry (PB) phase, where the meta-atoms that make up the meta-surface control the phase. According to this method, the phase of light passing through the meta-atom can be adjusted by twice the rotation angle θ of the meta-atom.

In this case, since phase adjustment occurs when circularly polarized light is converted from left to right (or from right to left), the higher the Conversion Efficiency (CE) of circularly polarized light is, the desired phase is achievedThe more efficient the bit adjustment. To improve efficiency, the method of finding L and W can be used by Rigorous Coupled Wave Analysis (RCWA) such that the term (t _l -t _s ) Maximizing/2, where t _l And t _s Representing the complex transmission coefficients of the meta-atoms in the major and minor axis directions, respectively. For example, when p=300 nm, h=475 nm, l=250 nm, and w=110 nm, high conversion efficiency of 0.88 can be obtained. However, the numerical values are exemplary, and detailed parameters for increasing the conversion efficiency may vary according to the detailed shape of the meta-atom and the relationship between the meta-atom and surrounding materials.

As described above, the arrangement angle θ of the nanostructures for setting the shape parameters may be adjusted to a relationship of Φ (x, y) =2θ (x, y), and then the nanostructures may be positioned on the spatial domain.

Although the nanostructure is formed as a rectangular parallel tube in fig. 4, the nanostructure is not limited thereto, and may have various cross-sectional shapes of the nano-pillar, for example, an elliptical pillar, as long as a long axis and a short axis are defined.

Fig. 5A and 5B are a plan view and a sectional view, respectively, showing a schematic structure of a meta-optical device according to an embodiment.

Referring to fig. 5A and 5B, the meta-optical device 100 according to an embodiment may include a plurality of super cells SC, and each super cell SC may include a plurality of nanostructures NS. The plurality of nanostructures NS may be provided in a configuration such that the nanostructures are supported by the support layer SU. Some of the plurality of nanostructures NS may be shown in the figure, and the entire nanostructure may be omitted. The nanostructure NS located at an arbitrary position Q (x, y) may have a rectangular parallelepiped shape in which a width, a length, and a height are defined and have a preset conversion efficiency, and may be arranged in such a configuration that an arrangement angle θ of a long axis of the cross-sectional nanostructure is Φ (x, y)/2 according to a phase value Φ (x, y) to be achieved at the position Q (x, y).

The arrangement pitch P of the nanostructures NS, i.e., the distance between the centers of adjacent nanostructures NS, may be set to λ/2 or less.

The nanostructure NS may be a material having a refractive index different from that of the surrounding material, and may be formed of, for example, a material having a refractive index higher than that of the surrounding material. For example, the nanostructure NS may include crystalline silicon (c-Si), polycrystalline silicon (p-Si), amorphous silicon (a-Si), and group III-V compound semiconductors (e.g., gallium phosphide (GaP), gallium nitride (GaN), gallium arsenide (GaAs), etc.), silicon carbide (SiC), titanium oxide (TiO 2), silicon nitride (SiN), and/or combinations thereof.

The nano-structure NS may include a nano-composite material including a resin material and nano-particles dispersed in the resin material. The resin material may include an Ultraviolet (UV) curable resin, and the nanoparticles may include silicon (Si) nanoparticles, titanium oxide (TiO 2) nanoparticles, and other nanoparticles made of the above various materials. Thus, the meta-optical device may be manufactured by using a flexible mold of the nanocomposite material. In this case, the nanostructure NS may be well formed on a support layer of various shapes and materials, for example, on a curved plastic layer in a desired shape and arrangement.

The material surrounding the nanostructure NS may include a dielectric material having a refractive index different from (e.g., lower than) the nanostructure NS. For example, the surrounding material may include silicon oxide (SiO 2) or air.

The support layer SU may include any one of glass (fused silica, BK7, etc.), quartz, polymer (polymethyl methacrylate (PMMA), SU-8, etc.), plastic, and semiconductor substrate. The support layer SU may comprise a material having a lower refractive index than the nanostructure NS. However, the support layer SU is not limited thereto.

The material, shape and arrangement of the nano-structures NS in the meta-optical device 100 according to an embodiment may be set to a phase profile of structured light suitable for forming a wide viewing angle. For example, as described above, the first function in the spatial frequency domain may be defined such that various propagation light beams diffracted from light having different diffraction orders have uniform intensities, and the structured light realized by the phase profile calculated from the first function may have a viewing angle of about 180 ° in the horizontal and vertical directions. However, the phase adjustment efficiency of the nanostructure NS for the phase profile may not be 100%, and thus the meta-optical device 100 may have a viewing angle of less than or equal to about 180 °. The meta-optical device 100 may generate structured light having a viewing angle greater than or equal to about 160 deg. in both the horizontal and vertical directions, for example.

The structured light generated in the meta-optical device 100 may have a regular dot pattern. However, the inventive concept is not limited thereto, and in a modified embodiment, the structured light may be modified to have a preset dot pattern.

The meta-optical device 100 may generate 1 st to m-th order diffracted light. Herein, when the nanostructures NS are arranged in an n×n matrix at an arrangement pitch P in a single super cell SC, the lower case letter m represents the largest number among integers smaller than (n×p/λ).

Since the phase profile applied to the design of the meta-optical device 100 is set in such a manner that various light beams diffracted from light having different diffraction orders have uniform intensities as described above, all light beams diffracted from light having all diffraction orders by the meta-optical device 100 can theoretically have uniform intensities. However, when an already set phase profile is implemented into the nanostructure NS, the implementation of the phase profile may not be performed with 100% accuracy, and thus the nanostructure NS may have a design error or a manufacturing error. When light is diffracted in the meta-optical device 100, the ratio of the intensity of the highest order diffracted light (e.g., mth order diffracted light) to the intensity of the first order diffracted light may be 20% or more, 30% or more, 40% or more, or 50% or more.

Fig. 6 is a micrograph showing a meta-optical device manufactured by the meta-optical device design method according to an embodiment.

The micrograph in fig. 6 demonstrates that the meta-optical device achieves structured light with a viewing angle of about 180 deg. and a diffraction efficiency of about 60% or higher.

Fig. 7 is a graph showing the relationship of the intensity of diffracted light at each arrangement pitch of the nanostructures in the meta-optical device according to the embodiment.

The graph in fig. 7 shows the relationship of the intensity of diffracted light with respect to the diffraction order when the pixel pitch, i.e., the arrangement pitch P of the nanostructures, is 300nm, 400nm, 500nm, 600nm, or 700 nm. In this case, the integer n of the n×n matrix in which the nanostructures are arranged in each super cell may be set to 12, 9, 7, 6, and 5, so that the highest diffraction order may be the same as ±5 in each case of n. The graph shows that as the arrangement pitch P increases, the intensity of higher order diffracted light decreases rapidly. When the arrangement pitch P is 300nm smaller than λ/2, the intensity ratio of the fifth-order diffracted light with respect to the first-order diffracted light is shown to be highest.

Fig. 8 is a view showing a plurality of distribution diagrams of structured light in the spatial frequency domain in each case where the number of super cells is different from each other in the meta optical device according to the embodiment.

In fig. 8, in each case denoted by a, b, c and d, respectively, the integer N of the n×n matrix in which the super cells are arranged is 2, 3, 4 and 5, respectively, the pixel pitch is 300nm, and the number of nanostructures in a single super cell in each case is 10×10. Although the number of nanostructures and the pixel pitch are related to the diffraction angle, the number of super cells may be related to the diameter (i.e., pyramid) of the diffracted beam, and may have no effect on the diffraction angle. As the integer N increases, the diameter of the diffracted beam decreases and the distribution of the structured light is uniform.

Fig. 9 is a view showing another example of the first function defined in the spatial frequency domain according to an embodiment of the meta-optical device design method.

The first function shown in fig. 3A is provided for deriving a phase profile for achieving a 180 ° view angle, but another example of the first function in this embodiment is provided for achieving any view angle of 2ω.

The first function shown in fig. 9 may be defined as having a value of 1 within a circle having a radius of (sin ω)/λ, and having a value of 0 in the remaining space in the spatial frequency domain defined by (fx, fy) satisfying the condition 1/(2P) fx 1/(2P), 1/(2P) fy 1/(2P). In this context, the capital letter P denotes the arrangement pitch of the nanostructures, the greek letter λ denotes the wavelength of the incident light to be modulated, and the greek letter ω denotes any value less than or equal to pi/2 (radians).

After setting the first function in this way, the phase profile to be applied to the spatial domain (metasurface domain) can be deduced in the same manner as described with reference to fig. 3B to 4, and a plurality of nanostructures suitable for each position can be arranged, thereby realizing a meta-optical device capable of representing a desired 2ω viewing angle.

Fig. 10 is a view showing another example of the first function defined in the spatial frequency domain according to an embodiment of the meta-optical device design method.

The first function in this embodiment may be provided to derive a phase profile representing an arbitrarily shaped viewing angle. As shown in fig. 10, the first function may be set to have a value of 1 within a circle having a radius r1, a value of 1 in a circle having an inner diameter r2 and an outer diameter r3, a value of 1 in a circle having an inner diameter r4 and an outer diameter r5, and a value of 0 in the remaining space in the spatial frequency domain defined by (fx, fy) satisfying the condition 1/(2P) +.fx+.1/(2P), 1/(2P) +.fy.ltoreq.1/(2P). In that case, r1 may be (sin ω ₁ ) The ratio of @ lambda, r2 may be (sin omega ₂ ) The ratio of @ lambda, r3 may be (sin omega ₃ ) The ratio of @ lambda, r4 may be (sin omega ₄ ) The ratio of @ lambda, r5 may be (sin omega ₅ ) λ. Furthermore, ω ₁ To omega ₅ Satisfy omega ₁ <ω ₂ <ω ₃ <ω ₄ <ω ₅ And under the condition of pi/2, the capital letter P represents the arrangement interval of the nano structures, and the Greek letter lambda represents the wavelength of the incident light to be modulated.

The meta-optical device may be designed by using a first function such that the viewing angle- ω is in the vertical and horizontal directions ₁ ～+ω ₁ 、-ω ₂ ～-ω ₃ 、+ω ₂ ～+ω ₃ 、-ω ₄ ～-ω ₅ 、+ω ₄ ～+ω ₅ Forming structured light within the range of (2).

Where the first function is set to have a value of 1 the value-1 region is provided as a single circle and two rings, but is not limited thereto, e.g., the value-1 region is modified as a single circle and a single ring.

Fig. 11A to 11D are views illustrating a method of manufacturing a meta-optical device according to an embodiment.

Fig. 11A illustrates a process of forming a flexible mold by copying the pattern 410a formed on the main stamp 410. The pattern 410a embossed or engraved on the master stamp 410 may have a shape corresponding to the shape and arrangement of the nanostructures of the meta-optical device to be manufactured. The master stamp 410 may be formed according to the shape and arrangement of the nanostructures, which are set to form a desired phase profile, i.e. structured light of a wide viewing angle. The pattern 410a of the master stamp 410 may be formed by, for example, an electron beam lithography process or the like. A layer of molding material having a soft material may be compressed over the main stamp 410. The molding material layer may include a first layer 420 and a second layer 430. The second layer 430, which is in direct contact with the pattern 410a of the master stamp 410, may include a material having a lower viscosity and a higher mechanical stiffness than the first layer 420. For example, the first layer 420 may include hard Polydimethylsiloxane (PDMS) and the second layer 430 may include hard polydimethylsiloxane (h-PDMS). However, this is an example of a layer of molding material, and the layer of molding material may comprise a single layer of flexible material. A layer of molding material may be placed over the master stamp 410, and then heat or pressure may be applied to the layer of molding material to imprint the pattern 410a of the master stamp 410 onto the second layer 430.

Referring to fig. 11B, a nanocomposite 450 may be coated on the flexible mold 440. The nanocomposite 450 may include a resin material 451 and nanoparticles 453 dispersed in the resin material 451. The flexible mold 440 may include a first layer 420 and a patterned second layer 431. The pattern 410a of the master stamp 410 may be imprinted on the second layer 431 such that an imprinted pattern 431a may be formed on the second layer 431. Although the detailed shape of the imprint pattern 431a is not shown in fig. 11B, the imprint pattern 431a may be an inverse pattern of the shape and arrangement of the nanostructures of the meta-optical device to be manufactured. The resin material 451 in the nanocomposite 450 may include a UV curable resin that fills the inside of the engraved region of the embossed pattern 431a in the form of an unhardened liquid.

Referring to fig. 11C, a support layer SU may be formed on the structure shown in fig. 11B, and then ultraviolet rays UV may be irradiated onto the flexible mold 440. Pressure may also be applied to the flexible mold 440 along with ultraviolet rays if desired. Thus, the resin material 451 of the nanocomposite 450 may be hardened. The support layer SU may include a flat substrate or may have a curved shape.

Thereafter, when the flexible mold 440 is removed, as shown in fig. 11D, the meta-optical device 100 is provided, the meta-optical device 100 having a nanostructure NS on the support layer SU, the nanostructure being formed of a nanocomposite material 450 including a resin material 451 and nanoparticles 453 dispersed in the resin material 451, and having a desired shape and arrangement.

According to the above-described manufacturing method, the flexible mold 440 can be repeatedly used to manufacture the meta-optical device 100, which is advantageous for mass-production of the meta-optical device 100. For example, a method of manufacturing the meta-optical device 100 by using an electron beam lithography process generally takes a long time and is very disadvantageous for mass production. However, in the manufacturing method according to the embodiment, a single main stamp 410 may be formed through an electron beam lithography process, a molding material layer may be formed on the main stamp 410, and the molding material layer may be hardened, thereby forming the flexible mold 440 in a short time.

Further, according to the above-described manufacturing method, since the flexible mold 440 can be used to form the nano-structure NS, the nano-structure can be easily formed even on the support layer SU having a curved shape of a desired shape and arrangement. In other words, the nano-structure NS can be well formed on the support layer SU regardless of the surface shape of the support layer SU due to the flexible nature of the flexible mold 440.

Fig. 12 is a photograph showing a meta-optical device based on a curved plastic implementation according to an embodiment.

As shown in fig. 12, the meta-surface may be implemented on curved transparent plastic provided as an ophthalmic lens. Thus, the meta-optical device 100 according to the embodiment can be easily used in an eye-wearable electronic apparatus.

The meta-optical device 100 according to an embodiment may be formed on various curved plastics and curved glass. For example, the meta-optical device 100 may be formed on a windshield or a side view mirror of a vehicle.

The meta-optical device 100 according to an embodiment may form a structured light projector together with a light source. The structured light projector may be applied to the depth recognition device together with the sensor. Depth recognition apparatuses may be used in various electronic apparatuses, for example, autopilot devices such as vehicles, autonomous vehicles, robots, and unmanned aerial vehicles, smart phones, smartwatches, mobile phones, personal Digital Assistants (PDAs), notebook computers, personal Computers (PCs), various wearable devices, virtual Reality (VR) devices, augmented Reality (AR) devices, other mobile or non-mobile computing devices, and internet of things (IoT) devices, etc.

Fig. 13 is a view showing a schematic structure of an electronic device according to an embodiment.

The electronic device 1000 may include an active stereoscopic based depth recognition device. The electronic device 1000 may include a structured light projector 500 that radiates structured light, first and second sensors 610 and 620 that detect the light, and a processor 700 that analyzes the light detected by the first and second sensors 610 and 620.

Structured light projector 500 may include a light source 510 for generating source light and a meta-optical device 520 for modulating the source light into structured light. The light source 510 may include a Light Emitting Diode (LED), a laser diode emitting laser light, and a Vertical Cavity Surface Emitting Laser (VCSEL). The light source 510 may emit source light, such as light in the near infrared, and visible wavelength bands. The wavelength of the source light emitted from the light source 510 may be not particularly limited, and may be set to emit light in a wavelength band suitable for an application using the structured light. The meta-optical device 520 may include the meta-optical device 100 described above and may be configured to form structured light of a wide viewing angle (FOV) according to the design method described above. The viewing angle of the structured light projector 500 may be in the range of, for example, about 160 ° to about 180 ° in the horizontal and vertical directions. However, the inventive concept is not limited thereto, and the structured light may have various forms of viewing angles, as shown in fig. 9 and 10. Accordingly, the structured light projector 500 can simultaneously irradiate a plurality of objects OBJ1, OBJ2, and OBJ3 arranged within the angle of view.

The first sensor 610 and the second sensor 620 may include a photodetector that detects light and generates an electrical signal. Each of the first sensor 610 and the second sensor 620 may include an array of light detecting elements. The first sensor 610 and the second sensor 620 may receive reflected light of the structured light irradiated to the objects OBJ1, OBJ2, and OBJ3. The first sensor 610 and the second sensor 620 may be provided to obtain information from different viewpoints at the objects OBJ1, OBJ2 and OBJ3. The first sensor 610 and the second sensor 620 may be located at opposite sides of the structured light projector 500 from each other. The first sensor 610, the structured light projector 500, and the second sensor 620 may be arranged in a string and spaced apart from each other by an appropriate distance. In the figure, the structured light projector 500 is shown between the first sensor 610 and the second sensor 620, but this is only an example. The first sensor 610 may be located between the second sensor 620 and the structured light projector 500, or may be changed to a different arrangement.

The first sensor 610 and the second sensor 620 may be located at relatively different positions from the structured light projector 500 such that the details of the reflected light detected from the objects OBJ1, OBJ2, and OBJ3 are different.

The processor 700 may calculate depth information of the objects OBJ1, OBJ2, and OBJ3 by analyzing the reflected light received from the first sensor 610 and the reflected light received from the second sensor 620. For example, reflected light reflected from the same position of the first object OBJ1 may be separately detected by the first sensor 610 and the second sensor 620, and coordinate values detected on each image plane of the first sensor 610 and the second sensor 620 may be compared, thereby calculating depth information on the corresponding position by a triangulation method. However, this is only an example embodiment, and various methods may be used to calculate depth information of the objects OBJ1, OBJ2, and OBJ 3.

The electronic device 1000 is shown to include the first sensor 610 and the second sensor 620, but the inventive concept is not limited thereto, and the electronic device 1000 may be configured to obtain depth information through only a single sensor according to a pattern of the structured light formed by the structured light projector 500. The object OBJ1, OBJ2 and OBJ3 may be irradiated with the structured light having the pre-designed preset pattern, and the pattern change occurring when the structured light is reflected from the object OBJ1, OBJ2 and OBJ3 may be tracked, thereby extracting depth information of the object OBJ1, OBJ2 and OBJ 3.

The electronic apparatus 1000 may obtain depth information of the objects OBJ1, OBJ2, and OBJ3 by using only one of the first sensor 610 and the second sensor 620. In addition, by using the first sensor 610 and the second sensor 620, depth information of the objects OBJ1, OBJ2, and OBJ3 can be obtained with higher accuracy.

Further, the processor 700 may control the overall operation of the electronic device 1000, for example, the operation of the first sensor 610 and the second sensor 620 and the operation of the light source 510 provided in the structured light projector 500.

The electronic device 1000 may further include memory. The programmed operation modules and other data required for the operation may be stored in the memory so that the processor 700 may perform the operations for extracting three-dimensional information about the objects OBJ1, OBJ2 and OBJ3 as described above.

The plurality of optical devices may be further arranged between the structured light projector 500 and the objects OBJ1, OBJ2, and OBJ3, and thus, the structured light emitted from the structured light projector 500 may be controlled to be directed to the objects OBJ1, OBJ2, and OBJ3, or may be further modulated by the optical devices. Further, an additional optical device such as a lens may be further disposed on each of the first sensor 610 and the second sensor 620 so as to collect reflected light reflected from the objects OBJ1, OBJ2, and OBJ 3.

Fig. 14 is a view showing the structure of an empirical depth identifying system using a meta optical device according to an embodiment, fig. 15A and 15B are photographs showing structural lights formed in the depth identifying system shown in fig. 14 from the front and the side, and fig. 16 is a depth map showing two object depths obtained by the depth identifying system shown in fig. 14.

Fig. 15A and 15B show structured light in which a laser light forms a dot pattern having a viewing angle of about 180 ° through a meta-surface. The structured light irradiates two objects (object 1 and object 2), images of the two objects (object 1 and object 2) are formed on the two cameras, and then depth information of the objects (object 1 and object 2) is obtained from the images. Stereo matching methods for finding the same point in the image of each camera use a Coherent Point Drift (CPD) algorithm to randomly obtain the best matching condition. Fig. 16 shows depth maps of two objects (object 1 and object 2) obtained as a result of experiments performed under the above conditions.

Experiments have shown that three-dimensional images of two objects (object 1 and object 2) located in a wide view angle can be well obtained by the depth recognition system using the meta-optical device according to the embodiment.

The electronic apparatus 2000 according to another embodiment may include an augmented reality device. The electronic device 2000 may include a structured light projector 500 that radiates structured light, first and second sensors 610 and 620 that detect the light, and a processor 800 that analyzes the light detected by the first and second sensors 610 and 620. The electronic device 2000 may further include an image display unit 900 on which an image is displayed.

The image display unit 900 may include various conventional display devices, for example, a liquid crystal on silicon (LCoS) device, a Liquid Crystal Display (LCD) device, an Organic Light Emitting Diode (OLED) display device, a Digital Micromirror Device (DMD), and a next generation display device such as a micro LED, a Quantum Dot (QD) LED, etc.

Similar to the processor 700 of the electronic device 1000 shown in fig. 13, the processor 800 may process the optical signals detected by the first sensor 610 and the second sensor 620 to obtain depth information about the objects OBJ1, OBJ2, and OBJ 3. Further, the processor 800 may control the image display unit 900 to process depth information obtained for the objects OBJ1, OBJ2, and OBJ3 into depth images and display the depth images on the image display unit 900, and may also control the image display unit 900 to display additional images related to the obtained depth images on the image display unit 900.

The electronic apparatus 2000 as an augmented reality device may be implemented as a wearable device such as a glasses type, a head-wearing type, a goggle type, or the like. The electronic apparatus 2000 may be implemented as a non-wearable device or may be provided in a driving apparatus such as a vehicle. For example, the augmented reality device may be applied to the front glass of a vehicle to reconstruct the surrounding in the driver's field of view into a depth image, i.e., a three-dimensional image, and to provide the driver with an associated additional image. In addition, structural parts of the augmented reality device, such as the structured light projector 500, may be disposed at other locations, such as a side surface, a rear surface, etc. of the vehicle, depth information of the surrounding environment in the blind spot of the driver may be obtained, and then the depth information may be reconstructed into a depth image and provided to the driver together with the relevant additional image.

The meta-optical device, its design method, its manufacturing method, and electronic apparatus including the meta-optical device have been described with reference to the embodiments shown in the drawings, but this is only an example, from which various modifications and other equivalent embodiments can be made by those skilled in the art. Accordingly, the disclosed embodiments should be considered in an illustrative rather than a limiting sense. The scope of the present specification is indicated in the scope of the claims rather than the foregoing description, and all differences within the equivalent scope should be construed as being included.

While the inventive concept has been particularly shown and described with reference to embodiments thereof, it will be understood that various changes in form and details may be made therein without departing from the spirit and scope of the appended claims.

Claims

1. A meta-optical device for forming structured light by modulating incident light having a preset wavelength, the meta-optical device comprising:

a plurality of super cells, each super cell comprising a plurality of nanostructures, each nanostructure having a shape size less than the predetermined wavelength,

wherein the shape and arrangement of the plurality of nanostructures is configured to form structured light having a pattern of dots with a viewing angle greater than 160 ° in the horizontal and vertical directions.

2. The meta-optical device of claim 1 wherein

The shape and arrangement of the plurality of nanostructures is designed such that the ratio of the intensity of the mth order diffracted light to the intensity of the first order diffracted light is greater than 50%,

wherein m represents the maximum number of integers less than (n×p/λ), n represents the number of nanostructures in each of the super cells, P represents the arrangement pitch of the nanostructures in each of the super cells, and λ represents the preset wavelength.

3. The meta-optical device of claim 1 wherein

The phase profile generated by each of the plurality of super cells is represented as a second function obtained by an iterative fourier transform of a first function, the first function being defined in the spatial frequency domain, and

the first function is defined as a value of 1 in a circle having a radius of 1/lambda, a value of 0 in the remaining space in the spatial frequency domain defined by (fx, fy) satisfying the condition 1/(2P). Ltoreq.fx.ltoreq.1/(2P), 1/(2P). Ltoreq.fy.ltoreq.1/(2P),

wherein P represents an arrangement pitch of the nanostructures, and λ represents the preset wavelength.

4. The meta-optical device of claim 1 wherein

The arrangement pitch of the plurality of nanostructures is less than or equal to λ/2 (λ represents the preset wavelength).

5. The meta-optical device of claim 1 wherein

Each of the plurality of nanostructures is shaped as a column having a cross-section defined by a major axis and a minor axis, an

The direction of the long axis of each of the plurality of nanostructures is determined by the relative position of the nanostructures in each of the plurality of supercells.

6. The meta-optical device of claim 1 further comprising

And a support layer supporting the plurality of nanostructures.

7. The meta-optical device of claim 6 wherein

Each of the plurality of nanostructures comprises:

a nanocomposite having a resin material and nanoparticles dispersed in the resin material.

8. The meta-optical device of claim 7 wherein

The meta-optical device is manufactured by using a flexible mold having an inverse pattern of the shape of the plurality of nanostructures.

9. The meta-optical device of claim 7 wherein

The support layer comprises a transparent plastic material having a curved shape.

10. A meta-optical device comprising:

a plurality of super cells, each super cell comprising a plurality of nanostructures arranged periodically,

wherein the phase profile generated by each of the plurality of super cells is represented as a second function obtained by an iterative fourier transform of a first function, the first function being defined in the spatial frequency domain, and

the first function is defined as having a value of 1 within a circle having a radius of (sin ω)/λ, and having a value of 0 in a remaining space in a spatial frequency domain defined by (fx, fy) satisfying the condition 1/(2P). Ltoreq.fx.ltoreq.1/(2P), 1/(2P). Ltoreq.fy.ltoreq.1/(2P), where ω represents a value of less than or equal to pi/2, P represents an arrangement pitch of the nanostructure, and λ represents the preset wavelength.

11. The meta-optical device of claim 10 wherein

Omega is pi/2 (radians).

12. A meta-optical device comprising:

the first function is defined as being at a radius (sin omega) ₁ ) The value of 1 in the circle of/lambda was found to be (sin omega) ₂ ) And has an outer diameter of (sin omega) ₃ ) Wherein λ is 1 in at least the ring and 0 in the remaining space in the spatial frequency domain defined by (fx, fy) satisfying the conditions 1/(2P). Ltoreq.fx.ltoreq.1/(2P), 1/(2P). Ltoreq.fy.ltoreq.1/(2P), wherein ω ₁ 、ω ₂ And omega ₃ With omega ₁ <ω ₂ <ω ₃ And the relation of pi/2 is not more than, P represents the arrangement interval of the nano structures, and lambda represents the preset wavelength.

13. An electronic device, comprising:

a light source that generates source light;

a meta-optical device as claimed in claim 1, configured to form structured light from the source light and illuminate an object;

a first sensor and a second sensor spaced apart from each other, the meta-optical device being located between the first sensor and the second sensor, and the first sensor and the second sensor being configured to detect light reflected from the object; and

A processor configured to analyze signals detected from the first sensor and the second sensor and calculate depth information about the object.

14. The electronic device of claim 13, further comprising

An image display unit for displaying the image,

wherein the processor is further configured to:

a depth image is generated from the depth information,

generating an additional image related to the depth image, and

and controlling the image display unit to display the depth image and the additional image.

15. The electronic device of claim 13, wherein

The electronic device includes an eye-wearable apparatus.