Ultra-wide field flat optics

Abstract

Wide-angle optical capabilities are beneficial for imaging and image projection devices. Traditionally, wide-angle operation has been achieved through complex assemblies of optical elements. Recent advances have led to metasurface lenses, or metalenses. These are ultrathin, planar lenses equipped with nanoantennas that control the phase, amplitude, and / or polarization of light. Here, we present a metalense capable of diffraction-limited focusing and imaging across an unprecedented field of view (FOV) of over 170°. The lens is integrated on a monolithic, planar substrate with an aperture on one side and a single metasurface on the other. The metasurface corrects third-order Seidel aberrations, including coma, astigmatism, and field curvature. The metalenses have a flat focal plane, which can greatly simplify system configurations for imaging and projection. The metalens design is general and can be easily adapted to various meta-atom shapes and wavelength ranges to meet the demands of various applications.

Description

Background Art

[0001] Cross - Reference to Related Applications This application claims the benefit of U.S. Patent Application No. 62 / 897,452, filed on September 9, 2019, and U.S. Patent Application No. 62 / 884,645, filed on August 8, 2019, under 35 U.S.C. § 119(e), and the entire contents of those applications are incorporated herein by reference.

[0002] Government Support This invention was made with government support under grant number HR0011 - 1 - 72 - 0029 awarded by the Defense Advanced Research Projects Agency (DARPA). The government has certain rights in this invention.

[0003] Wide - angle optical systems are essential for high - performance imaging, detection, and projection of images or beams. One of the earliest examples of a wide - angle optical system is the panoramic camera invented by Thomas Sutton in 1858. This panoramic camera had a single water - filled spherical lens that produced an image on a curved glass plate covered with a light - sensitive emulsion. Since the manufacture and handling of the curved plate were clearly difficult, this method was quickly abandoned, but it outlines the fundamental challenges for achieving wide - field imaging. Since then, panoramic photography has evolved along the path of a flat detector plane, generally relying on compound lens assemblies known as fisheye lenses to reduce optical aberrations at large field - of - view angles. However, such multi - lens structures increase the size, weight, and assembly complexity of the optical system.

[0004] A metasurface lens, or metalens, is a device that can control the phase, amplitude, and / or polarization of propagating light using an array of subwavelength structures. Metalenses offer a promising solution enabling flat and compact individual optical components. The design of metalenses has been realized to reduce several types of aberrations, especially spherical aberration and chromatic aberration. However, it remains challenging to design a metalens that is not affected by angular-dependent coma aberration, field curvature, and astigmatism. These aberrations limit the usefulness of a single-element metalens.

[0005] A common method for designing a single-element metalens is to utilize a hyperbolic phase profile to achieve a spherical wavefront.

Equation

Equation

[0006] The deviation between the two distributions at different angles of incidence (AOI) results in third-order (Seidel) aberrations, such as coma aberration, astigmatism, and field curvature. These aberrations limit the field of view of the metalens. As an example, assuming a baseline metalens design with a diameter of 1 mm and a focal length of 2 mm operating at a wavelength of 5.2 μm, the conventional hyperbolic phase profile effectively suppresses spherical aberration and achieves diffraction-limited focusing with a Strehl ratio of 1 at normal incidence. However, when the AOI is greater than about 7°, coma aberration becomes dominant, the Strehl ratio drops below 0.8, and the performance of the metalens rapidly degrades from the diffraction limit. Due to the small field of view angle, the use of a single metalens in imaging and image projection applications is severely limited.

[0007] In order to suppress coma aberration and expand the diffraction-limited FOV, several metasurface designs have already been implemented. One way involves forming a metasurface on a spherical surface, which is difficult. Another way involves cascading multiple metasurfaces based on the design principles of conventional bulk optical systems. In the design of such a doublet metasurface, the focusing function is mainly executed by one of the doublet's metasurfaces, and the other metasurface functions to correct off-axis aberrations. This type of doublet can achieve a diffraction-limited FOV of up to approximately 56°. In comparison, the FOV of a conventional single-layer metasurface is usually limited to approximately 30°, the diffraction-limited spot size due to coma is large, the optical efficiency is as low as 6 - 20%, and it is highly sensitive to misalignment of the assembly. A metasurface with wide-angle performance comparable to that of conventional refractive power has not been realized until now.

Summary of the Invention

[0008] Here, a metasurface is introduced that can perform diffraction-limited imaging or beam / image projection over a very wide field of view (WFOV) close to 120°, 130°, 140°, 150°, 160°, 170°, or 180°. One example of the metasurface is monolithically integrated on a single-piece planar substrate and has an opening on one side and a single metasurface on the other side. The metasurface corrects one or more third-order Seidel aberrations, including coma aberration, astigmatism, and field curvature. The metasurface is further characterized by a planar focal plane, which can significantly simplify the system structure. This metasurface can be used in imaging, imaging / pattern projection, displays, augmented reality (AR), virtual reality (VR), three-dimensional (3D) sensing, holography, LIDAR, Fourier transform optics, etc. The metasurface can be easily adapted to various sub-wavelength structures and diffractive optical elements (DOEs), as well as wavelength ranges that meet the requirements of various applications.

[0009] The meta - surface on the metalens of the present invention can comprise an array of optically thin (e.g., with a thickness from 0.1 wavelength to 10 wavelengths), sub - wavelength array nano - antennas (also called meta - atoms) that can arbitrarily control the phase, amplitude, and / or polarization of the incident light wavefront. In the case of imaging applications, the on - demand wavefront manipulation method can significantly reduce the number of lenses and other optical elements to eliminate image aberrations. As a result, the optical system based on the metalens of the present invention may have significant advantages in terms of size, weight, performance, and cost (SWaP - C) compared to systems made of conventional optical components.

[0010] The optical component of the present invention can comprise a (transparent) substrate, an opaque layer on a first surface of the substrate, and a meta - surface on a second surface of the substrate opposite the first surface. The opaque layer defines an opening for transmitting light over the entire field of view of at least 120° (e.g., 130°, 140°, 150°, 160°, 170°, or greater). And the meta - surface focuses the light transmitted through the substrate by the opening.

[0011] The substrate can be planar or curved and has a thickness t sub and a refractive index n at the wavelength of light sub . The opening can have a diameter D in , in which case the meta - surface has a diameter D meta = D in +t sub tan[sin -1 (1 / n sub )].

[0012] The metasurface can be configured to focus light incident across all fields of view onto a focal plane parallel to the second surface of the substrate. In this case, the optical component may also include a detector array in the focal plane and be able to detect the light focused by the metasurface or the light source array in the focal plane, in which case the metasurface can collimate or focus the beam emitted by the light source array. The aperture can be configured to emit this collimated or focused beam.

[0013] The metasurface can converge light incident across all fields of view with a Strehl ratio of at least 80%. It may comprise an array of at least 1000×1000 meta-atoms. It can have different but continuous portions configured to capture input beams at various angles of incidence. And it can correct at least one third-order aberration.

[0014] The optical component can also include a second metasurface disposed on at least a portion of the aperture to filter or modulate the light transmitted by the aperture. For example, the second metasurface can be configured to filter the light transmitted by the aperture or to modulate the phase, amplitude, polarization, and / or wavelength of the light transmitted by the aperture. The second metasurface can be configured to generate 2D or 3D optical patterns, images, dot arrays, holograms, etc. The modulation provided by the second metasurface may depend on the characteristics of the incident beam (e.g., angle, spatial, polarization, spectral characteristics, etc.). The second metasurface can also be configured to change the polarization of the light transmitted by the aperture or the wavelength of the light transmitted by the aperture, for example, using non-linear effects. By combining an irradiation pattern with customizable or reconfigurable spatial, angle, polarization, and / or spectral characteristics with an object reconstruction algorithm associated with such modalities, the characteristics of the scene can be efficiently obtained.

[0015] The metalens of the present invention can be used in sensors and other devices. For example, the sensor of the present invention can include a substrate, a light source array supported by a first portion of the substrate, a first metalens, a second metalens, and a detector array supported by a second portion of the substrate. The first and second metalenses each include a respective planar substrate (or respective portions of the same planar substrate). Each metalens has a corresponding metasurface on a first surface of its planar substrate (portion) and a corresponding aperture on a second surface of its planar substrate (portion) facing the object. During operation, the light source array emits light that is projected by the first metalens toward the object over the entire field of view of at least about 120° (e.g., 130°, 140°, 150°, 160°, 170°, or more). The second metalens collects light scattered and / or reflected by the object over the entire field of view of at least about 120° (e.g., 130°, 140°, 150°, 160°, 170°, or more). And the detector array detects the light collected by the second metalens.

[0016] All combinations of the foregoing concepts and other concepts described in more detail below (provided such concepts are not mutually inconsistent) are part of the subject matter of the invention disclosed herein. In particular, all combinations of the subject matter recited in the claims at the end of this disclosure are part of the subject matter of the invention disclosed herein. Terms used herein that may also appear in any incorporated by reference disclosure should be given the meaning that most closely matches the particular concepts disclosed herein.

[0017] Those skilled in the art will understand that the drawings are mainly for illustrative purposes and are not intended to limit the scope of the subject matter of the invention described herein. The drawings are not necessarily to scale. In some cases, various aspects of the subject matter of the invention disclosed herein may be shown exaggerated or enlarged in the drawings to facilitate understanding of the various features. In the drawings, like reference characters generally refer to like features (e.g., functionally and / or structurally similar elements).

Brief Description of the Drawings

[0018]

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[0019] The wide field of view (WFOV) metasurface lens of the present invention has a simple and easy-to-manufacture configuration, comprising a single metasurface layer and an aperture integrated on the opposing surface of a single thin substrate. Since it can have a diffraction-limited FOV exceeding 170° and a planar focal plane, it can greatly simplify the array design of related detectors (for imaging and detection) or emitters (for image / beam projection, displays, etc.). It can operate over a wide range of wavelengths (e.g., from visible to infrared (IR)), depending on the design of the metasurface as well as the materials of the substrate and the metasurface. The metasurface can be designed to operate at any wavelength from the microwave to the ultraviolet (UV) region of the electromagnetic spectrum, with a bandwidth reaching up to 1 octave.

[0020] Furthermore, the design principle of the WFOV metasurface lens disclosed herein is general and applicable to any meta-atom configuration and wavelength range to meet the requirements of various applications. With an appropriate metasurface, the metasurface lens can become a panoramic metasurface lens with broadband operation and polarization diversity. As another example, nanorods or nanopillars can be used in a design that is not affected by polarization. For a desired wavelength range, various metasurface material systems can be selected, for example, including PbTe and CaF2, as well as a-Si and Al2O3.

[0021] The WFOV metasurface lens can be implemented using a Huygens metasurface with an ultra-thin meta-atom profile. The Huygens metasurface can be easily fabricated, but it may limit the response to wavelength and polarization. In any case, the WFOV design described herein is general and applicable to any meta-atom configuration. With an appropriate selection of meta-atoms, the metasurface lens can perform panoramic imaging (e.g., FOV exceeding 170°) on a broadband with polarization diversity.

[0022] Due to their extremely high WFOV, planar surface, and flat focal plane, the metalenses of the present invention are particularly well suited for sensing, image projection, LIDAR, imaging, optical projection, augmented reality / virtual reality, beam steering, and 3D sensing applications. For example, the beam projection functionality of the devices of the present invention can be used in LIDAR systems where the light emitters are individually modulated or switched on and off to steer, switch, or tailor the output beam for wide angle illumination. The same WFOV metalens can be used in detection modules for wide angle signal collection.

[0023] Wide Field of View (WFOV) Metalens 1A and 1B show perspective and side views, respectively, of an exemplary WFOV metalens 100. Metalens 100 comprises a single substrate 110 having an input aperture 130 located on one surface 112 and a metasurface 120 located on the other surface 114. Substrate 110 has n sub Refractive index and t sub The thickness is D in and various incidence angles θ in A light beam entering the input aperture 130 at D meta and is focused onto a flat focal plane 141.

[0024] Substrate 110 may be made of any suitable material that transmits light at the operating wavelength of the metalens. Substrate 110 may be rigid, flexible, or stretchable. It may be double-sided flat / planar, or warped, curved, or bent, depending on the application, as shown in Figures 1A and 1B. Suitable substrate materials include, but are not limited to, halide crystals, sapphire and other oxide crystals, quartz, chalcogenide crystals, glasses (e.g., oxide, chalcogenide, and other types of glasses), plastics, or semiconductor materials.

[0025] The metasurface 120 comprises an array of sub-wavelength optical structures (also known as meta-atoms, described and shown below) that modify the amplitude, phase, and / or polarization of the incident wavefront. These meta-atoms can have the same or different shapes, sizes, and orientations. For example, they may be rectangular, cylindrical, H-shaped, or L-shaped. They are arranged on a lattice with a pitch below the operating wavelength of the metalens 100. The lattice can be of any suitable period and shape (e.g., square, rectangular, or hexagonal). The lattice can also be aperiodic, for example, with a gap between adjacent meta-atoms, e.g., an interval defined by a constant gap distance, or with randomly placed meta-atoms, which is patterned to provide a desired phase profile across the metasurface 120.

[0026] The meta-atoms are fabricated from a transparent material (e.g., the same material as the substrate 110 and having meta-atoms formed by patterning one surface of the substrate 110). The shape, size, and layout of the meta-atoms can be selected such that the spectral response of the metasurface does not vary with AOI, and the optical phase / amplitude changes provided by the meta-atoms with varying AOI are automatically taken into account in their design. The metasurface 120 may also be designed for rotationally asymmetric focusing (e.g., focusing at some AOIs but not at others).

[0027] (Alternatively, the metasurface 120 may be replaced by a metamaterial, a multilayer metasurface, or a diffractive optical element (DOE) that provides the same or a similar effective phase profile. For example, the DOE may be implemented as a binary or multi-level grayscale DOE having a shape larger than the operating wavelength of the lens. Similarly, the overall lens structure functions as a diffractive optical lens.)

[0028] The aperture stop 130 is defined by a layer 132 of an opaque (e.g., absorptive or reflective) material on the upper surface 112 of the substrate 110. The upper surface 112 may also define a metasurface (not shown) that modulates the intensity and / or phase of the incident light to form an effective aperture stop, or may be partially or fully covered by a metasurface. (Alternatively, this metasurface may be replaced by a metamaterial, a multilayer metasurface, or a DOE.) The aperture stop 130 can be circular with a diameter obtained by the following formula. D in =D meta -2t sub tan[sin -1 (1 / n sub )] This diameter may range from microns to millimeters, and the numerical aperture (NA) ranges from 0 to 1. When the metalens is immersed in oil or another high refractive index material, the numerical aperture can be higher (e.g., 1.5).

[0029] The aperture may also be square, elliptical, hexagonal, rectangular, or any other suitable shape. Alternatively, the aperture may comprise one or more sub-regions, patches, or arrays configured to modulate or encode the input light in terms of spectrum, phase, amplitude, polarization, etc. For example, at least a portion of the aperture 130 may be patterned with another metasurface 134 that filters the light passing through the aperture 130. Optionally, the edge of the aperture stop 130 can be apodized, e.g., with Gaussian apodization or super-Gaussian apodization, to reduce harmful edge effects.

[0030] By spatially separating the metasurface 120 and the aperture stop 130 while disposing them on the same substrate, the metalens 100 can capture input beams at various angles of incidence (AOI) at various but continuous portions of the metasurface 120. For example, by optimizing for a performance index that describes the focusing quality at multiple AOIs, local optimization of the phase profile is promoted. The metasurface phase profile is designed such that the root mean square (RMS) wavefront error from an ideal spherical wavefront on the input aperture is always less than 0.0745 wavelengths. Thereby, the metalens 100 surely has a Strehl ratio of more than 80% over its entire field of view, which can be 120°, 130°, 140°, 150°, 160°, 170°, 175°, 179°, or nearly 180° for a flat substrate, whereby diffraction-limited performance can be achieved under various light irradiation conditions. For metalenses using a curved, bent, or warped substrate, the field of view can be even larger than 180°. As in the case of a flat surface, the incident light is refracted (or diffracted using the metasurface) from the input aperture to the back metasurface. Conventional fish-eye lenses mostly use a curved front lens to achieve FOV > 180°.

[0031] Depending on its dimensions, metasurface design, and substrate material, the metalens 100 can operate at any of various wavelengths. For example, the metalens 100 designed to operate at a wavelength of 5.2 μm can have a 2 mm thick calcium fluoride (CaF2) flat substrate 110 (n sub = 1.4) with a 1 mm diameter circular aperture 130 and a 5.2 mm × 5.2 mm metasurface 120. This metasurface 120 may comprise an array of 2,000 × 2,000 hoheneisen meta-atoms made of PbTe with a square lattice constant of 2.5 μm. The metasurface 120 can have a constant focal length of 2 mm corresponding to an effective numerical aperture (NA) of 0.24. At an incident angle of nearly 90°, the maximum angle of light propagation inside the substrate is 45.7°. As shown below, the phase response of the meta-atoms constituting the metasurface 120 depends slightly on the beam incident angle within the WFOV of the metalens.

[0032] The metalens 100 operates differently from a metalens designed with separate angular channels, where non-overlapping regions on the metasurface are dedicated to beams of different AOIs. Since the metalens has dedicated non-overlapping regions, a metalens with separated angular channels can achieve high-quality focusing only for a discrete set of incident angles. In the metalens 100 of the present invention, due to the properly designed metasurface phase profile and metalens structure, on the metasurface side 114 of the substrate 110, the incident angle continuously changes, and diffraction-limited focusing of beams with overlapping beam profiles becomes possible. Therefore, the metalens 100 can focus a beam without aberration or collimate a beam, and thus can project an image from or to any point on the front hemisphere for any light direction.

[0033] In addition to correcting aberrations such as coma and astigmatism, the metalens 100 uses a planar focal plane 141 across the entire FOV. Eliminating Petzval field curvature is beneficial in a wide range of applications including imaging and image projection by facilitating the integration of standard planar detectors or emitter arrays. For example, FIG. 1B shows an array of light sources 140 on the focal plane 141 for projecting beams collimated at different angles from a metalens. The light sources 140 within the array may be light-emitting diodes (LEDs), lasers, or any other (aperture-equipped) light source. The array of light source 140 arrays can comprise various light sources emitting at various wavelengths. The light source 140 may also comprise a broadband or wavelength-tunable light source depending on the application. (For imaging applications, the light source 140 can be replaced with an array of planar detectors within the focal plane 141, such as a CMOS or CCD array.)

[0034] Metalens Metasurface Design and Modeling The metalens can be designed using a hierarchical combination of full-wave simulations (e.g., the finite element method (FEM), the finite-difference time-domain (FDTD) method, and the finite integration technique (FIT)) and Kirchhoff diffraction integrals. At the subwavelength scale, full-wave simulations can be used to design and model the meta-atoms of the metasurface for the desired optical response. At the macroscopic system level, the diffraction integral method incorporating the full-wave simulation results can efficiently verify the focusing characteristics of the entire metalens, and it can be used to optimize the phase profile of the metasurface.

[0035] Figures 2A - 2F illustrate the design and modeling of the Hohenstein meta-atoms of the metasurface on one side of a metalens operating at a wavelength of 5.2 μm. Each Hohenstein meta-atom constitutes either a rectangular or an H-shaped block made of PbTe on a CaF2 substrate, as illustrated in Figures 2A and 2B respectively. The combination of PbTe and CaF2 is selected to utilize the low optical loss of these materials and the large refractive contrast in the mid-infrared spectral range, enabling metasurface operation in transmission mode while supporting both electric dipole (ED) and magnetic dipole (MD) resonances. Their shapes are designed to spectrally overlap the ED and MD resonances at the operating wavelength, resulting in a complete phase range of 360° (2π) with a nearly single transmittance that exploits the Kerker effect. The meta-atom library contains eight different meta-atoms that cover a 360° phase space in 45° discontinuous steps for linearly polarized TM light at a wavelength of 5.2 μm.

[0036] Figure 2C shows the simulated amplitude and phase responses of each of the eight meta-atoms within the meta-atom library at normal incidence. The meta-atoms are shown below the plot in Figure 2C and include three H-shaped meta-atoms and five rectangular atoms. The meta-atom dimensions are listed in Table 1 (below). [Table 1]

[0037] Figure 2D shows the simulated phase shifts of each meta - atom in the oblique AOI (inside the substrate). The incident light is TM - polarized. The results show that the response of the meta - atoms depends only slightly on the angle of incidence because the meta - atoms are designed to be little affected by the angle of incidence. The angle of 45.6° coincides with the angle of total reflection at the interface between air and calcium fluoride. This all - dielectric metasurface platform forms the basis for the high performance of the WFOV metalens.

[0038] Figure 2E shows the phase distribution of a metalens having a 2000×2000 meta - atom array of the metasurface. The black dashed circle in the center of the plot indicates the position of the opening on the surface of the substrate on the opposite side of the metasurface.

[0039] Figure 2F shows the simulated cross - sectional intensity distributions of the foci under various AOIs and the foci formed by a perfect lens of the same NA. The intensity distribution is asymmetric due to the oblique AOI. The peak amplitude decreases with the increase of the AOI, and more light appears in the side lobes. The RMS phase error compared with the ideal phase profile at all AOI values (Equation 2) is consistently less than 0.0745 wavelengths, and the Strehl ratio is surely better than 0.8. As a result, when compared with a perfect lens having the same NA and focal length, the design of the metalens achieves diffraction - limited focusing and imaging performance across the entire FOV. The simulated modulation transfer function (MTF) of the foci in Figure 6 further supports this conclusion.

[0040] The meta - atom simulations illustrated in Figures 2A - 2F were performed using the frequency - domain solver of the commercial software package CST Microwave Studio. For each meta - atom, the boundary conditions of the unit cell were used in both the negative and positive x - and y - directions, and the open - boundary condition was set along the z - axis. Each meta - atom was illuminated from the substrate side with an x - polarized plane wave directed in the positive z - direction. The results shown in Figure 2C are the phase and amplitude of the complex transmission coefficient derived between two open ports placed above and below each meta - atom.

[0041] The focusing and imaging operations of the WFOV metalens are modeled according to the Kirchhoff diffraction integral, which is a physically exact form of the Huygens–Fresnel principle. The model begins by calculating the Huygens point-spread function of the optical system. This incorporates an angle-dependent phase profile at the metasurface and propagates the wavefront emitted from each meta-atom to the image plane where its complex amplitude is derived, with the corresponding amplitude and phase. The diffraction of the wavefront through space is given by the interference or coherent sum of the wavefronts from the Huygens sources. The intensity at each point on the image plane is the square of the sum of the resulting complex amplitudes.

[0042] The initial optical structure and phase profile of the metalens can be designed using OpticStudio® (Zemax, LLC). Subsequently, an analytical model based on the Kirchhoff diffraction integral can be utilized to analyze the complete metasurface performance at various AOIs. The analytical model incorporates an angle-dependent phase mask following the individual meta-atom responses at various AOIs obtained from full-wave simulations (e.g., in FIGS. 5A - 5F, as described below). The optimization process of the phase profile involves iterative evaluations between OpticStudio® and the Kirchhoff diffraction integral model regarding the quality of focus, i.e., the Strehl ratio (SR AOI(i) ) at various AOIs. The following merit function (figure of merit, FOM) is maximized using numerical optimization.

Number

[0043] Using commercially available optical design software Zemax OpticStudio, the initial phase profile of the metasurface can be obtained under ideal conditions. The rotationally symmetric phase profile is represented in polynomial form.

Number

Number

Table 2

Table 3

[0044] Optimization starts with a standard hyperbolic phase profile that matches the specifications of the optical system (e.g., focal length and f / #) over a small AOI range as the initial input. When the first optimization cycle converges to the starting AOI range, the result is used as the input value for the next optimization iteration cycle with an extended AOI range. The process continues until the final result converges over the target AOI range (e.g., ±90°).

[0045] More specifically, numerical optimization using the Levenberg-Marquardt algorithm (also called the damped least squares method) is implemented to maximize a merit function (e.g., the FOM defined above) in each optimization cycle. Using the Kirchhoff diffraction integral, not only the FOM but also the stray ratio at each field of view angle can be numerically calculated. The angular-dependent response of each meta-atom is also incorporated to generate an angular-dependent phase mask after spatial and phase discretization / mapping of the initial phase profile. In each optimization cycle, the FOM with equal weights for all AOIs over the range is first used and maximized. Maximizing this equal-weight FOM may result in a stray ratio of less than 0.8 at some field of view angles. In this case, optimization is repeated using adjusted weighting coefficients until the stray ratio exceeds 0.8 for all AOIs within the target range. The final phase profile shown in Figure 3 obtained by the procedure achieves diffraction-limited focusing performance for continuously varying incident angles up to ±90°. The design coefficients of the phase profile are summarized in Table 1. Figure 4 shows the angle-dependent phase profile based on the phase shift of individual meta-atoms in a 1 mm diameter region at the center of the metasurface.

[0046] Figures 5A - 5F show the angular response of the meta-atoms for various linearly polarized light at oblique incidence. Figures 5A - 5C show the orientations of various linearly polarized light with respect to the H-shaped meta-atoms. Figure 5A shows y - z polarized light, Figure 5B shows polarized light rotated 45° between y - z and x - z, and Figure 5C shows x - z (TM) polarized light. The y-component of the electric field is equal to zero. Figures 5D - 5F show the angular response of the meta-atoms as a function of the angular incidence for each of these polarization states.

[0047] Figures 6A - 6D illustrate the WFOV metalens 600 designed to function at a wavelength of 940 nm and its performance. The WFOV metalens 600 comprises a planar sapphire substrate with a thickness of 3.9 mm, having a circular aperture 630 with a diameter of 1 mm on one side and a metasurface 620 on the other side. The metasurface 620 comprises an array of amorphous silicon posts 622 as meta - atoms, and focuses light onto a planar focal plane located 2.5 mm from the metasurface 620.

[0048] Figure 6B shows the simulated Strehl ratio (right axis) and focusing efficiency (left axis) as a function of the half - angle of the object of the WFOV metalens 600. The Strehl ratio consistently exceeds 0.8, indicating diffraction - limited focusing across the entire FOV of approximately 180°. Figure 6C shows the simulated modulation transfer function (MTF) of the WFOV metalens 600 at various AOIs and various incident planes, and the MTF of a diffraction - limited lens with the same NA. The MTF indicates that the WFOV metalens 600 has diffraction - limited focus at various AOIs.

[0049] Figures 7A - 7C illustrate simulated panoramic imaging using the WFOV metalens. Figure 7A shows an imaging simulation apparatus using a source image placed at an infinite distance from the metalens (not to scale). Figure 7B shows a monochromatic source image covering a 180° horizontal FOV, here showing the skyline of Paris. Figure 7C shows a simulated panoramic image formed by the ultra - wide - angle FOV metalens that details the aberration and diffraction effects. When the image sensor is replaced with a microdisplay and used, the same meta - optical device can be easily used to project an image into the far field with an ultra - wide - angle FOV.

[0050] Fabrication of the WFOV Metalens Figure 8 shows a WFOV metalens fabricated using electron beam lithography on a 2 mm thick CaF2 planar substrate by the double-resist layer lift-off method. The meta-atoms of this WFOV metalens shown in the upper left are made of thermally evaporated nanocrystalline PbTe and have a uniform thickness of 650 nm. The front aperture is defined by a metal tin layer using standard UV lithography.

[0051] More specifically, the metalens in Figure 8 was fabricated on a circular CaF2 substrate (Edmund Optics) with a diameter of 15 mm and a thickness of 2 mm. Considering the symmetry of the meta-surface layout, only a 2 mm × 3.6 mm portion of the meta-surface was necessary and fabricated to verify the performance of the WFOV. Before fabrication, the substrate surface was sequentially cleaned in an ultrasonic bath of acetone and isopropanol alcohol (IPA) for 3 minutes each continuously. Then, the sample was baked at 190 °C for 5 minutes to completely evaporate the solvent and adsorbed moisture on the surface. And the substrate was treated with oxygen plasma (150 W, 1 minute, pressure 0.8 Torr) to remove organic residue contaminants.

[0052] One side of the sample was covered with a two-layer photoresist composed of PMGI (thickness 800 nm) and ZEP520A (thickness 400 nm). The PMGI layer was spin-coated at 2400 revolutions per minute (rpm) for 1 minute and then baked at 190 °C for 3 minutes. The baking process is important to ensure the mechanical stability of the PMGI layer. The ZEP layer was spin-coated at 4000 rpm for 1 minute and baked at 190 °C for 2 minutes. During the execution of electron beam (e-beam) lithography, to prevent the charging effect, the sample was covered with a water-soluble conductive polymer (ESpacer 300Z, Showa Denko America, Inc.) and a conductive clamp was placed on the substrate.

[0053] The meta-surface pattern (Figure 8, right) was at a voltage of 125 kV, a current of 10 μA, and 380 μC / cm 2Written using an e-beam lithography system (Elionix ELS F-125) with proximity effect correction (PEC) using the base dose amount. The ZEP layer was developed by immersing the sample in water, ZEDN50, and IPA for 1 minute each. Subsequently, the PMGI layer was partially dissolved with an RD6 developer diluted at a 1:1 ratio with water. This partial dissolution should be carefully performed to achieve undercut without collapsing the pattern.

[0054] After photoresist development, a 650 nm thick PbTe film was deposited by thermal evaporation (custom-designed system, PVD Products, Inc.) at a rate of 17 Å / s and a base pressure of 10 -6 Torr. Prior to deposition, the sample was pre-cleaned with oxygen plasma to improve film adhesion. Subsequently, the meta-surface pattern was transferred by lifting off the material on top of the photoresist by immersing it in N-methyl-2-pyrrolidone (NMP) overnight.

[0055] On the opposite side of the sample, a circular opening with a diameter of 1 mm was patterned. The surface of the PbTe meta-surface that was patterned was protected by a dry film photoresist (DuPont MX5000 series) during the fabrication of the opening. To create the opening, the substrate was cleaned with oxygen plasma and spin-coated with a negative photoresist NR1000PY (Futurrex, Inc.) at 1500 rpm for 1 minute. Then, the sample was soft-baked at 115 °C, exposed to UV light through a mask for 40 seconds, and hard-baked at 155 °C. Subsequently, the exposed photoresist was developed in RD6 for 10 seconds and then rinsed with water. Next, a 200 nm layer of tin was deposited by thermal evaporation and lifted off by removing the photoresist with acetone. Finally, the dry film photoresist covering the meta-surface side was removed by overnight NMP treatment.

[0056] Characterization of the WFOV metalens Figures 9A - 9I illustrate the experimental characterization of the focus quality at various AOIs of the WFOV metalens 700 of FIG. 7. FIG. 9A shows a measurement apparatus 900, where the WFOV metalens 700 is illuminated from the aperture surface by a collimated and linearly polarized laser beam from a laser 910 with a wavelength of 5.2 μm. The laser 910 is mounted on a circular rail 912, enabling various AOIs from 0° to 85°. The maximum AOI of 85° was limited by the geometric constraints of the experimental apparatus 900 rather than the performance of the lens. The focused image was magnified using a pair of mid - infrared lenses 920 with a calibrated magnification of 120 ± 3 and projected onto a liquid - nitrogen - cooled InSb focal - plane array (FPA) camera 930.

[0057] Figures 9B - 9G show examples of the focused images measured by the FPA camera 930. The inset in FIG. 9H shows the cross - sectional optical intensity profiles of the focus at incident angles of 0°, 70°, and 85°, along with the simulated ideal focus profile from a lens without aberration having the same NA, for comparison. FIG. 9H also shows the measured Strehl ratio. At all incident angles, the Strehl ratio is maintained above 0.8, indicating the diffraction - limited focusing performance from the metalens 700.

[0058] FIG. 9I is a plot of the focusing efficiency of the metalens versus AOI for linear polarization. The focusing efficiency is defined as the ratio of the power confined at the focus to the power incident on the metasurface of the metalens. The data in FIG. 9I show a relatively weak dependence on AOI, with the focusing efficiency varying from 45% to 32% as the AOI changes from 0° to 85°. This relatively flat angular response serves the function of irradiating the entire image formed by the metalens almost uniformly.

[0059] The power P ms,foc (θ i ) focused by the metalens is the total incident power P0 transmitted through the front aperture (e.g., a 1 - mm circular aperture), the focusing efficiency f(θ i) and the Fresnel transmittance coefficient T that explains the reflection loss at the interface between air and the substrate (such as CaF₂). p (θ i ) can be expressed as P ms,foc (θ i ) = P0·T p (θ i ) f(θ i ) (3) The total incident power P0 can be further written as P0 = P0(0)·cos(θ i ), where P0(0) is the total incident power passing through the aperture at normal incidence (θ i = 0°). When the same collimated laser beam (having a beam diameter much larger than the aperture size) is incident obliquely on the metalens, a sine coefficient occurs because the power density decreases by a factor of cos(θ i ) due to geometric projection.

[0060] In FIGS. 9A to 9I, the measured values are η(θ i ), that is, the ratio focused on the total transmitted power by the metalens, and P ms,trans (θ i ), that is, the power transmitted by the metalens, and P ref (θ i ), that is, the power transmitted through the reference sample (a CaF₂ substrate having the same thickness and an aperture of 1 mm, but the back surface is not a meta - surface). According to these definitions, it is as follows. η(θ i ) = P ms,foc (θ i ) / P ms,trans (θ i ) (4) P ref (θ i ) = P0T p 2 (θ i ) = P0(0)cos(θ i )T p 2 (θ i ) (5)

[0061] In Equation (5), since there are two CaF2-air interfaces with the same transmittance, T p (θ i ) coefficient is squared. Finally, the value of the focusing efficiency f(θ i ) is given by the following equation.

Equation

[0062] P0, P ms,trans (θ i ), and P ref (θ i ) were measured using a large-area detector so as to capture all of the transmitted power. Next, T p (θ i ) was calculated from P0 and P ref (θ i ) according to Equation (5). P ms,foc (θ i ) was quantified by measuring the transmitted power P hole (θ i ) incident on a detector integrated with a 200-μm diameter pinhole. The FPA camera imaged the focal plane around the focus over the entire 200-μm diameter region. By integrating the light intensity values from the FPA camera for each pixel, the ratio of the power concentrated at the focus to the total power transmitted through the pinhole, i.e., P ms,foc (θ i ) / P hole (θ i ) was obtained. P ms,foc (θ i ) was obtained by P hole (θ i )×P ms,foc (θ i ) / P hole (θ i ). (Unfortunately, the FPA camera does not provide measured values of light intensity and instead only explicitly counts relative optical intensity.)

[0063] Imaging with a WFOV Metalen Figures 10A and 10B illustrate the wide - field - of - view (WFOV) imaging capability of the metalens 700. Figure 10A shows a measuring device 1000 where a laser 1010 irradiates an object 1014 through a diffuser 1012. The metalens 700 collects the light scattered by the object 1014 and projects it onto an InSb FPA camera 1030 through a mid - infrared lens 1020. In the experiment, the distance between the object 1014 and the metalens 700 is fixed at 2 mm to match the planar shape of the lens focal plane. The mid - infrared lens 1020 and the camera 1030 are mounted on a semi - circular rail 1032 so that they can rotate around an axis passing through the metalens 700 and perpendicular to the optical axis of the metalens 700. The object 1014 comprises a metal tin pattern that reproduces a USAF resolution test chart. The selected test target pattern (Group 5, Element 1) has three stripes each with a width of 15.6 μm, which is close to the ideal diffraction - limited resolution (13.2 μm) of the lens.

[0064] Figure 10B shows a clearly resolved image of the pattern recorded over the full angular range of the experimental setup 1000 in Figure 10A. This angular range is 0° to 82°, which is limited by the geometric constraints of the experimental setup 1000. The image in Figure 10B confirms the diffraction - limited imaging performance of the metalens over a very wide angular range.

[0065] Beam / Image Projection When the emitter array is disposed on the focal plane, a WFOV metasurface lens system can be used to project a beam or image at a large projection angle. In FIG. 1B, for example, light emitted from each light source (pixel) in an array of light sources 140 (e.g., a micro-LED display) is collimated by a metasurface 120 on one surface of a substrate 110 and directed toward an aperture 130 disposed on the other surface of the substrate 110 and is directed or projected in various directions. The output beam or image is coupled to another medium, such as free space, or another optical element or waveguide structure. The phase profile of the metasurface, the diffraction-limited focusing or collimation performance, can be achieved over a FOV of approximately 180° in air, which corresponds to a maximum refractive angle of approximately, e.g., approximately 42° within a substrate 110 having a refractive index of 1.5 at the operating wavelength. This is in stark contrast to existing meta-optical systems that use multiple metasurfaces to maintain imaging quality at large angles of incidence.

[0066] Using the WFOV metasurface lens 100, an array of beams generated from an emitter array 140 can be projected over a wide range of angles for applications such as 3D sensing, detection, ranging, communication, etc. Using the WFOV metasurface lens 100, an image generated from an emitter array 140 (e.g., a micro-display) can also be projected over a wide range of angles for applications such as displays, holography, AR / VR, etc. Some examples are described below.

[0067] 3D Sensing Using a WFOV Metasurface Lens Existing 3D depth sensors based on structured light (SL), time-of-flight (TOF), or active stereoscopic technology are constrained by a small FOV (usually less than 70°), and the resolution is typically limited to resolvable spots or angles of about 1,000×1,000. Another related technology is vision-based simultaneous localization and mapping (V-SLAM). Intel's RealSense® Tracking Camera T265 uses V-SLAM to provide an impressive stitched FOV of up to 163°, but it has two fish-eye imaging units, and the imaging quality of the fish-eye lenses is low, resulting in low resolution compared to standard camera optics, especially at large field-of-view angles.

[0068] Figures 11A and 11B show a 3D sensor 1100 with two WFOV metalenses 1112 and 1122. This 3D sensor 1100 utilizes the ultra-wide-angle FOV, diffraction-limited performance, planar focal plane, and simplicity of the WFOV metalenses 1112 and 1122 for 3D sensing applications such as optical touch interfaces, gesture control, face recognition, object detection / tracking, 3D scanning, navigation, etc.

[0069] The 3D sensor 1100 includes a pattern projection module 1110 that includes a first WFOV metalens 1112 and a light emitter array 1114 (e.g., a micro-LED or vertical-cavity surface-emitting laser (VCSEL) array), and a camera module 1120 that includes a second WFOV metalens 1122 and a photodetector array 1124. (In the case of stereoscopic sensing, the light emitter array 1114 can be replaced with a second photodetector array, and the pattern projection module 1110 can be changed to another camera module.) The pattern projection module 1110 and the camera module 1120 are attached to a substrate 1102 that may be a flexible or rigid component of plastic, glass, or other suitable material. The entire sensor 1100 may have a thickness of less than 7 mm (e.g., 3 mm or less) and can be fabricated with commercially available light emitter and photodetector arrays.

[0070] The pattern projection module 1110 projects a pattern, such as an array of dots or stripes, into free space having a wide angular range 1111 (e.g., 120°, 130°, 140°, 150°, 160°, 170°, or greater) and onto an object 1101 (e.g., a hand or fingertip). The image of the object 1101 illuminated by the pattern projector 1110 is captured by the camera module 1120 over the entire equally wide and overlapping FOV 1121. A processor (not shown) coupled to the pattern projection module 1110 and the camera module 1120 analyzes the image captured by the camera module 1120 to generate 3D information about the object 1101.

[0071] Ultra-wide-angle beam projection and detection angles 1111 and 1121 enable 3D sensing over a wide space and angular range. The diffraction-limited performance of the metalenses 1112 and 1122 enables high-quality pattern generation and high-resolution imaging. The simple optical module configuration enables high integration into mobile devices such as smartphones and tablets, and also improves the tolerance to misalignment of the assembly. The field of view of structured light projection and imaging is close to 180°, with diffraction-limited spatial resolution, providing accurate 3D sensing / imaging near the surface.

[0072] For example, a sensor 1100 (operating at 940 nm with an aperture size of 1 mm) using the near-infrared metalens 600 shown in FIG. 6A can operate with an average angular resolution of 0.1° over the entire 180° FOV due to diffraction-limited focusing / collimation. Thus, the sensor optics can support a resolution of approximately 1,800×1,800, showing a significant improvement compared to state-of-the-art 3D sensors, and the performance can be further improved by simply increasing the aperture size.

[0073] The sensors 1100 of FIGS. 11A and 11B are ultra-small and thin with a thickness of less than 7 mm, and are compatible with the integration of a micro-LED array (currently available with a pitch of less than 3 μm, corresponding to the diffraction-limited spatial resolution of 2.9 μm of the metalens) and an imager sensor. This sensor 1100 delivers each unit pixel on the source array 1114 to a point in the far field, and the front aperture of the first WFOV metalens 1112 can be integrated with another metasurface (e.g., any metasurface 134 in FIG. 1A) designed to further modify the radiated beam pattern (e.g., phase, amplitude, polarization), as well as the response that depends on wavelength, polarization, and / or angle. This another metasurface may be in or on an opening or another part of the transparent portion of the substrate, and can further improve the function of the metalens 1112 and increase the complexity and information density of the projection pattern exceeding 180° FOV. The second metasurface can be configured to filter or change the polarization of the light transmitted through the opening. Alternatively, the second metasurface can be configured to change the wavelength of the light transmitted through the opening, for example, by non-linear effects induced by the metasurface.

[0074] The metasurface on the aperture surface of the metalens 1112 can also "provide" an aperture by modulating the distribution of its phase, amplitude, spectrum, and / or polarization response to form an effective aperture. For example, since the metasurface on this aperture surface can modulate the phase distribution of the incident light, the light within the effective aperture region is transmitted or further modulated and propagates towards the metasurface on the back surface, while the incident light outside the aperture is scattered or deflected away from the region for WFOV imaging or sensing. The metasurface region outside the effective aperture can also be designed to have a minimum transmission power (e.g., by designing the reflection or absorption characteristics of the metasurface). The metasurface region outside the effective aperture can also be designed to have spectral or polarization filtering characteristics that block light having a specific wavelength or polarization.

[0075] Compared with state-of-the-art 3D sensing, 3D sensing using a WFOV metasurface has many advantages: (1) It can be widely applied to SL, TOF, and active stereo 3D depth sensing; (2) It simultaneously solves the FOV limitations related to the illumination and light reception (camera) optical systems; (3) Due to the diffraction-limited imaging and image projection capabilities of the metasurface optical system, it enables fine spatial resolution across the entire FOV without aberration; (4) The optical system is designed to operate at a single near-infrared wavelength (e.g., for VCSEL illumination) or across a narrow band (e.g., for micro-LED array illumination), so very high (e.g., nearly unity) optical efficiency can be achieved; (5) It is ultra-compact and has a minimum number of elements; and (6) Since different parts of the metasurface interact with light at different AOIs, the meta-atoms can be locally configured to exclude ambient light outside the operating wavelength. Different from conventional optical filters that cannot be used over a wide angular range because the passband spectrally shifts with the AOI, the unique ultra-wide-angle optical filter capability of the metasurface can significantly increase the signal-to-noise ratio (SNR) and dynamic range.

[0076] The high-resolution panoramic 3D sensors 1100 of FIGS. 11A and 11B have applications ranging from household appliances, robotics, augmented / integrated reality, automobiles, and unmanned aerial vehicles (UAVs), etc. For example, the wide sensing FOV enables gesture recognition and control near the surface using a single-point sensor, which is impossible with current 3D sensing methods. In augmented reality and virtual reality, fine sensor resolution and a large FOV (matching that of human vision) enable rapid and accurate reconstruction of the surrounding environment to create an immersive user experience.

[0077] WFOV Metasurfaces for Augmented Reality (AR) and Virtual Reality (VR) Microdisplays for augmented reality and virtual reality applications have recently gathered significant research and development efforts due to their wide implementation space in next-generation display technologies. From an optical configuration perspective, AR / VR displays can be classified into two main groups: bulk-optics-based systems and waveguide-based systems. Waveguide-based systems have gained increasing interest in recent years due to their compact form factor and ease of integration with glasses and other devices. However, state-of-the-art waveguide-based displays still have limited resolution and FOV. For example, the FOV of existing commercial waveguide AR / VR systems is typically less than 45°×45°, which is much smaller than the range of human vision. To improve the display quality, conventional optical engines use complex and multi-element optical systems that increase the size and weight of the system.

[0078] FIG. 12 shows an AR / VR system 1200 comprising an optical engine 1210 composed of a micro-LED array 1212 and a high-resolution WFOV projection metalens 1214. The WFOV projection metalens 1214 is coupled to a waveguide 1230 by an optical coupling structure 1220, such as a 3D freeform coupling structure (as shown in FIG. 12), a sub-wavelength optical structure, or a diffractive optical element. The waveguide 1222 is also coupled to or comprises a waveguide out-coupling structure 1224, such as another 3D freeform coupling structure, a sub-wavelength optical structure, or a diffractive optical element. The microdisplay 1212 emits a light beam, which is collimated by the WFOV metasurface projection optics 1214 and subsequently coupled to the waveguide 1230 by the optical coupling structure 1220. The waveguide 1222 directs the light towards the waveguide out-coupling structure 1224, and the image is projected directly out-of-plane to the eye(s) 1201 with a large FOV (e.g., close to 180 degrees).

[0079] When the aperture size is 2 mm, due to the imaging performance without aberration, the angular resolution of the WFOV metasurface projection optical system 1214 is 0.34 mRad at a wavelength of 550 nm, which is very close to the resolution of the human eye (for example, about 0.3 mRad). With a 180° FOV, this enables a resolution of more than 9000×9000 resolvable spots at each RGB wavelength, and a FOV of about 9 mm×9 mm on the microdisplay. The total thickness of the meta-optical system is only a few millimeters.

[0080] Meta-lens with a metasurface aperture Figures 13A and 13B show a meta-lens 1300 and 1302 that modulate the beams projected by emitters (e.g., LEDs or VCSELs) 1342a - 1342c within a light emitter array 1340, respectively. In Figure 13A, the light emitter array 1340 is in the planar focal plane of the meta-lens 1300, which comprises a transparent substrate 1310 having a first metasurface 1320 on one surface and a second metasurface 1334 on the other surface. The first metasurface 1320 collimates the beams emitted by the emitter 1342 that can cover a FOV of 120° or more. The collimated beams propagate through the substrate 1310 to the second metasurface 1334, and the second metasurface 1334 spreads over an area smaller than the area of the first metasurface 1310. The second metasurface 1334 modulates the phase, amplitude, polarization, and / or spectral characteristics of the collimated beams to generate a 2D or 3D optical pattern, dot array / cloud, image, hologram, or a pattern with different polarizations, and / or spectral characteristics. The first metasurface 1320 can also be configured to generate a 2D or 3D pattern that varies based on the incident angle, wavelength, polarization, etc. of the incident beam.

[0081] FIG. 13B shows a similar metalens 1302. The difference is that the second metasurface 1336 is configured to generate a pattern that varies as a function of the angle of incidence. In this case, the light from emitter 1342a generates an array of dots on a square grid, while the light from emitters 1342b and 1342c generates different sparse dot arrays. The second metasurface 1336 can also be configured to modulate the incident beam according to other beam characteristics including spatial, polarization, and / or spectral characteristics. For example, the second metasurface 1336 can also be configured to generate a pattern that depends on wavelength or polarization, such that the emitted light from the emitter array 1340 having various wavelength or polarization characteristics generates a customizable pattern. The responses depending on the incident beam characteristics of the first and second metasurfaces 1320 and 1336 can be utilized in a combined manner. Alternatively, the DOE can be used instead of or in combination with the second metasurfaces 1334 / 1336. An irradiation pattern with customizable or reconfigurable spatial, angular, polarization, and / or spectral characteristics can be combined with an object reconstruction algorithm associated with such modalities to efficiently obtain the characteristics of the scene.

[0082] Closing Although various embodiments of the invention have been described and illustrated herein, those skilled in the art will readily envision various other means and / or structures for performing the functions and / or obtaining the results and / or one or more of the advantages described herein. Each such variation and / or modification is to be regarded as within the scope of the embodiments of the invention described herein. More broadly, those skilled in the art will readily understand that all parameters, dimensions, materials, and configurations described herein are exemplary, and that the actual parameters, dimensions, materials, and / or configurations will depend on the particular application for which the teachings of the invention are used. Those skilled in the art will be able to recognize, or confirm, with the use of no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Accordingly, the foregoing embodiments are presented by way of example only, and within the scope of the appended claims and their equivalents, embodiments of the invention may be practiced otherwise than as specifically described and claimed. Embodiments of the inventions disclosed herein are directed to each of the individual features, systems, articles, materials, kits, and / or methods described herein. Furthermore, combinations of two or more such features, systems, articles, materials, kits, and / or methods are included within the scope of the inventions disclosed herein if such features, systems, articles, materials, kits, and / or methods are not mutually inconsistent.

[0083] Also, various inventive concepts may be embodied as one or more methods, of which examples are provided. The acts performed as a part of the method may be ordered in any suitable way. Accordingly, embodiments may be configured so that the acts are performed in an order different than illustrated, including performing some acts simultaneously, even though shown as sequential acts in exemplary embodiments.

[0084] All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in incorporated documents by reference, and / or ordinary meanings of defined terms.

[0085] In this specification and the claims, the indefinite articles "a" and "an" should be understood to mean "at least one" unless explicitly indicated to the contrary.

[0086] In this specification and the claims, the phrase "and / or" should be understood to mean "either or both" of the elements so combined, i.e., elements that are present conjunctively in some cases and disjunctively in other cases. Multiple elements listed together with "and / or" should be construed in the same fashion, i.e., as "one or more" of the elements so combined. Other elements other than those specifically identified by the "and / or" clause may optionally be present, whether or not they are related to those specifically identified elements. Thus, as a non-limiting example, "A and / or B" can refer, when used in combination with open-ended language such as "comprising", in one embodiment only A (optionally including elements other than B), in another embodiment only B (optionally including elements other than A), in yet another embodiment both A and B (optionally including other elements), and the like.

[0087] As used in this specification and the claims, "or" should be understood to have the same meaning as "and / or" as defined above. For example, when separating items in a list, "or" or "and / or" is inclusive, i.e., it includes any one or more of the listed elements and, in some cases, one or more additional unlisted items, and is also to be construed as including pluralities of them. In contrast, terms such as "only one of" or "exactly one of", or "consisting of" when used in the claims, only refer to exactly one of several or the listed elements. Generally, the term "or" as used in this specification is to be construed only as indicating an exclusive alternative (i.e., "one or the other but not both") when preceded by exclusive terms such as "either", "one of", "only one of", "exactly one of". "Consisting essentially of", when used in the claims, shall have the ordinary meaning as used in the field of patent law.

[0088] As used in this specification and the claims, the phrase "at least one" in relation to one or more elements should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but does not necessarily have to include at least one of all the elements specifically listed in the list of elements, nor does it exclude any combination of elements in the list of elements. This definition also allows for the possibility that elements other than those specifically identified in the list of elements referred to by the phrase "at least one" may exist as necessary, regardless of whether they are related to the specifically identified elements. Thus, by way of non-limiting example, "at least one of A and B" (or equivalently "at least one of A or B", or equivalently "at least one of A and / or B") can, in one embodiment, refer to including at least one, and optionally two or more, of A and no B (and optionally including elements other than B), in another embodiment, refer to including at least one, and optionally two or more, of B and no A (and optionally including elements other than A), and in yet another embodiment, refer to including at least one, and optionally two or more, of A, as well as at least one, and optionally two or more, of B (and optionally including other elements), and so on.

[0089] In the claims and the above specification, all transitional phrases, such as "comprising", "including", "possessing", "having", "containing", "involving", "holding", "consisting of", etc., should be understood to be open-ended, i.e., to mean including but not limited to. As defined in section 2111.03 of the United States Patent and Trademark Office Examination Procedure Manual, only the transitional phrases "consisting of" and "consisting essentially of" are exclusive or semi-exclusive transitional phrases, respectively.

Claims

1. A substrate, an opaque layer on a first surface of the substrate, with openings formed so that visible light or near-infrared light refracts over a certain field of view, a metasurface on a second surface of the substrate opposite the first surface, for focusing the visible light or near-infrared light refracted by the openings of the substrate and an optical component comprising the same.

2. The optical component according to claim 1, wherein the substrate is planar.

3. The optical component according to claim 1, wherein the substrate is curved.

4. A substrate, an opaque layer on a first surface of the substrate, with openings formed so that light transmits over a certain field of view, a metasurface on a second surface of the substrate opposite the first surface, for focusing the light transmitted through the substrate by the openings and comprising the same, wherein the substrate has a thickness t ｓｕｂ and a refractive index n at the wavelength of the light ｓｕｂ and the openings have a diameter D ｉｎ and the metasurface has a diameter D ｍｅｔａ = D ｉｎ + t ｓｕｂ tan[sin －１ (1 / n ｓｕｂ )], and an optical component.

5. The optical component according to claim 1, wherein the metasurface is configured to focus the visible light or near-infrared light incident over the entire field of view onto a focal plane parallel to the second surface of the substrate.

6. The optical component according to claim 5, further comprising a detector array for detecting the visible light or near-infrared light focused by the metasurface on the focal plane.

7. Further comprising a light source array on the focal plane, The meta-surface is configured to collimate the beam emitted by the light source array, and the opening is configured to emit the beam, the optical component according to claim 5.

8. The meta-surface and / or the opening are further configured to modulate the beam emitted by the light source array, the optical component according to claim 7.

9. The meta-surface is configured to focus incident light over the entire field of view with a Strehl ratio of at least 80%, the optical component according to claim 1.

10. The meta-surface comprises an array of at least 1000 meta-atoms × 1000 meta-atoms, the optical component according to claim 1.

11. The meta-surface has a plurality of continuous portions that capture input beams at various angles of incidence, the optical component according to claim 1.

12. The meta-surface is configured to correct at least one third-order spherical aberration, the optical component according to claim 1.

13. The meta-surface is a first meta-surface, and The optical component according to claim 1, further comprising a second meta-surface disposed on at least a part of the opening to modulate and / or filter the visible light or near-infrared light transmitted through the opening.

14. The second meta-surface is configured to modulate the visible light or near-infrared light refracted by the opening with a spatially-varying pattern that depends on the angle of incidence of the visible light or near-infrared light refracted by the opening, the optical component according to claim 13.

15. Refracting visible light or near-infrared light over a certain field of view through an opening formed on a first surface of a substrate, Focusing the visible light or near-infrared light by a metasurface on a second surface opposite to the first surface of the substrate A method comprising **Claim 16** The method according to claim 15, wherein focusing the visible light or near-infrared light includes focusing the visible light or near-infrared light incident over the entire field of view onto a focal plane parallel to the second surface of the substrate. **Claim 17** The method according to claim 16, further comprising detecting the visible light or near-infrared light focused by the metasurface using a detector array on the focal plane. **Claim 18** Collimating a beam emitted by a light source array on the focal plane using the metasurface, and Emitting the beam through the opening, the method according to claim 16 further comprising. **Claim 19** The method according to claim 15, wherein focusing the visible light or near-infrared light includes focusing the visible light or near-infrared light over the entire field of view with a Strehl ratio of at least 80%. **Claim 20** The method according to claim 15, wherein focusing the visible light or near-infrared light includes correcting at least one third-order aberration. **Claim 21** Based on the incident angle of the visible light or near-infrared light refracted by the opening, modulating at least the phase, amplitude, polarization, or wavelength of the visible light or near-infrared light transmitted through the opening using another metasurface disposed on at least a part of the opening, the method according to claim 15 further comprising. **Claim 22** The method according to claim 15, further comprising filtering the visible light or near-infrared light refracted by the opening using another metasurface disposed on at least a part of the opening. **Claim 23** A substrate, A light source array supported by a first portion of the substrate and emitting light; A first metalens optically communicating with the light source array and projecting the light emitted from the light source array onto an object over a certain field of view, the first metalens comprising a first planar substrate having a first meta-surface on a first surface facing the light source array and a first opening on a second surface; A second metalens optically communicating with the object and collecting the light scattered and / or reflected by the object over a certain field of view, the second metalens comprising a second planar substrate having a second opening on a first surface facing the object and a second meta-surface on a second surface; A detector array supported by a second portion of the substrate, optically communicating with the second metalens, and detecting the light collected by the second metalens; A sensor comprising the above.

24. A substrate; An opaque layer on a first surface of the substrate, with openings formed so that light can pass through; A first meta-surface provided in the opening on the first surface of the substrate, which deforms or modulates light incident on the first surface of the substrate at various angles; A second meta-surface on a second surface opposite to the first surface of the substrate, which generates an optical pattern that changes according to at least one of the incident angle, phase, amplitude, polarization, and spectral characteristics of the light that undergoes at least one of deformation, modulation, transmission by the opening and the first meta-surface; An optical component comprising the above.

25. The optical component according to claim 24, wherein the first meta-surface modulates the light according to at least one of the phase, amplitude, incident angle, polarization, and spectral characteristics of the light.

26. The optical component according to claim 24, wherein the optical component is immersed in another material.

27. The optical component according to claim 24, wherein the base material is a first base material, a second base material, a light source array supported by a first portion of the second base material, facing the optical component, and emitting light through the optical component to an object over a certain field of view, a wide-field metasurface optically communicating with the object and collecting the light that has been at least one of scattered and reflected by the object over the field of view, a detector array supported by a second portion of the second base material, optically communicating with the wide-field metasurface, and detecting the light collected by the wide-field metasurface and a sensor comprising the same.

28. The optical component according to claim 24, wherein the optical pattern is a two-dimensional optical pattern.

29. The optical component according to claim 24, wherein the optical pattern is a three-dimensional optical pattern.

30. The optical component according to claim 24, wherein the optical pattern is an array of dots or stripes.

31. The optical component according to claim 24, wherein the second metasurface generates an array of sparse dots that vary according to the angle of incidence.

32. The optical component according to claim 24, wherein the first metasurface collimates the light.

33. The optical component according to claim 1, wherein the opening has an apodized edge.

34. The optical component according to claim 1, wherein the metasurface has a phase profile designed to provide diffraction-limited focusing over the field of view.

35. The optical component according to claim 1, wherein the metasurface comprises a plurality of contiguous portions having a phase profile optimized for a performance index representing the focusing quality at a plurality of angles of incidence.

Images