Multifunctional metasurface flat optical system

Abstract

A meta-optical system is described that includes a multifunctional metasurface formed from a plurality of meta-atoms. The multifunctional metasurface may exhibit two or more different optical functions for two or more different states of light incident on the metasurface. The different states of light include different polarizations, different wavelengths, and different angles of incidence. The different optical functions include distance sensing, focusing, divergence, image formation, and patterned light formation. The multifunctional metasurface can selectively impart different phase profiles to an incident beam depending on the optical state of the incident beam.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Application No. 63 / 283,803, filed November 29, 2021, entitled “Multifunctional Metasurface Flat Optics,” which is incorporated by reference in its entirety herein.

[0002] (Government support) This invention was made with Government support under Grant No. HR0011-1-72-0029 awarded by the Defense Advanced Research Projects Agency (DARPA). The Government has certain rights in this invention. [Background technology]

[0003] Meta-optics continue to be developed as alternative optical components and systems to more conventional lens, phase mask, and filter optical systems. Meta-optics include a patterned array of microscale structures on at least one surface of a substrate through which light passes. The shape of the structures and their layout on the surface may be designed to provide a desired far-field pattern or wavefront of the light field incident on the meta-optic. Meta-optics can be designed to compensate for optical aberrations (e.g., to obtain high-resolution, very wide field of view imaging). The advantage of meta-optics over conventional optical systems is that high-quality optics can be fabricated on substrates with flat surfaces using conventional microfabrication techniques instead of grinding and polishing curved surfaces on one or more lenses to form a compound lens with at best similar optical performance. Summary of the Invention

[0004] The present technology relates to optical systems and optical systems, including subwavelength optics, metasurfaces, metamaterials, multifunctional flat optical devices, architectures, and systems that provide improved performance, novel functionality, and greater structural simplicity compared to conventional bulk optical systems. Such optical devices and systems are useful for computational imaging, three-dimensional (3D) sensing, imaging, and other applications. More generally, applications of multifunctional metasurface flat optical systems include, but are not limited to, imaging, sensing, and optical computing techniques such as machine vision, image classification, compressed sensing, multispectral imaging, brightfield imaging, computation, and polarimetry.

[0005] In some implementations, a meta-optic may exhibit two or more optical states or optical functions. Each meta-optic optical state may capture different information of the scene (e.g., using different spectral or polarization channels) or perform different optical functions for subsequent data fusion or reconstruction (e.g., one state for imaging and one state for performing edge detection). Edge detection may be performed using a two-dimensional Laplace operator phase profile to perform second order spatial differentiation. In another embodiment, one optical state may be used to capture spatial information, one state may be used to capture spectral / polarization information, etc.

[0006] The meta-optics architecture of the present invention may include a substrate and a multiplexed metasurface positioned on one side of the substrate. The multiplexed metasurface is configured to operate in at least two modes that affect incident light differently according to the properties of the light (e.g., its polarization, wavelength, angle of incidence, etc.). As an example, to realize a polarization-dependent multifunctional meta-optics system, the multiplexed metasurface is designed to provide different optical responses to light having different polarization states (e.g., a first optical response to x-polarized light and a second optical response to y-polarized light) or different wavelengths to obtain, for example, different information about the imaged scene. By providing different optical responses, the meta-optics system can effectively operate as a wavefront coding element with different functions. By switching polarizers, filters, or illumination sources to change the polarization state, wavelength, or angle of incidence of the incident light, a desired optical response can be selected from the multiplexed meta-optics system. In some implementations, three or more optical responses are possible from the meta-optics system. In addition to different optical responses to different polarization states, meta-optics may also be designed to exhibit other optical responses to other conditions of incident light (e.g., different wavelength conditions, different incidence angle conditions, etc.) to provide multiplexed functionality for multiple tasks.

[0007] The techniques may be implemented as an optical system that includes a substrate and a metasurface disposed on a first side of the substrate, the metasurface configured to impart a depth-sensitive phase profile to incident light in a first state and to impart a depth-insensitive phase profile to the incident light in a second state, different from the first state.

[0008] Another embodiment of the present technology includes a confocal zoom lens. The confocal zoom lens of the present invention may include a first transparent substrate, a second transparent substrate spaced apart from the first transparent substrate, a first metasurface disposed on the surface of the first transparent substrate, and a second metasurface disposed on the surface of the second transparent substrate. Alternatively, the first and second metasurfaces may be disposed on the first and second surfaces of the same transparent substrate. In both cases, the first and second metasurfaces are configured to generate a first light intensity / field distribution from light in a first state and a second light intensity / field distribution from light in a second state that is different from the first light intensity / field distribution. For example, the first and second metasurfaces may focus horizontally and vertically polarized light to the same focal plane with different magnifications.

[0009] All combinations of the foregoing concepts and additional concepts discussed in more detail below (provided such concepts are not mutually inconsistent) are contemplated as part of the inventive subject matter disclosed herein. In particular, all combinations of the subject matter recited in the claims that appear at the end of this disclosure are considered to be part of the inventive subject matter disclosed herein. Terms explicitly used in any disclosure incorporated by reference herein should be given the meaning most consistent with the specific concepts disclosed herein. [Brief description of the drawings]

[0010] Those skilled in the art will appreciate that the drawings are presented primarily for illustrative purposes and are not intended to limit the scope of the inventive subject matter described herein. The drawings are not necessarily to scale, and in some instances, various aspects of the inventive subject matter disclosed herein may be shown exaggerated or enlarged in the drawings to facilitate an understanding of different features. In the drawings, like reference characters generally refer to like features (e.g., functionally similar and / or structurally similar elements).

[0011] [Figure 1A-B]Figure 1A shows a perspective view of a 3D imaging / sensing meta-optical system architecture incorporating a front metasurface for computational imaging and a rear metasurface for wide field-of-view (FOV) imaging. Figure 1B shows an elevation view of the 3D imaging / sensing meta-optical system architecture of Figure 1A. [Figure 1C] FIG. 1C shows five 9 × 9 unit cell arrays of meta-atoms arranged to form different supercells for the metasurface. [Figure 2A] FIG. 2A shows a perspective view of a polarization-sensitive amorphous silicon-on-silica meta-atom suitable for use in the metasurfaces of the present invention. [Figure 2B] FIG. 2B plots the difference between the simulated phase profiles of the meta-atom of FIG. 2A for x- and y-polarized light. [Figure 2C] FIG. 2C shows a portion of a metasurface layout having an array of polarization-sensitive meta-atoms, each similar to FIG. 2A but with different x- and y-dimensions. [Diagram 3] FIG. 3 is a flow chart of a modified direct search process for selecting and arranging meta-atoms across a metasurface. [Figure 4A] FIG. 4A shows a model for simulating the performance of a depth-sensitive metaoptical system that produces a rotating focal spot as a function of depth or distance from the metaoptical system. [Figure 4B] FIG. 4B is a plot of focal orientation versus depth for the meta-optical system of FIG. 4A (phase profile shown in inset image). [Figure 4C] FIG. 4C plots a simulation of the point spread function of a point source object positioned at different depths from the meta-optical system of FIG. 4A. [Figure 5A] FIG. 5A illustrates the image reconstruction and depth estimation process using the meta-optics system of the present invention. [Figure 5B]FIG. 5B shows a simulation of a 3D object (left), a simulation of a reconstructed image of the 3D object obtained with the metaoptical system of the present invention and the process of FIG. 5A (center), and the double helix point spread function (DH-PSF) of the metaoptical system of the present invention (right). [Figure 5C] FIG. 5C plots the estimated depth of a 3D object imaged from the meta-optics based on the DH-PSF versus the actual depth of the 3D object from the meta-optics. [Figure 6] FIG. 6 is a schematic diagram of a confocal zoom lens with two multiplexed metasurfaces (MS-1 and MS-2), with solid and dashed lines showing light with different properties (e.g., different polarization states). [Figure 7A] FIG. 7A shows the design and optical simulation results of a 10X parfocal zoom lens incorporating two multiplexed metasurfaces operating at a 40 degree FOV in a first state (e.g., polarization 1) with near diffraction-limited imaging performance. [Figure 7B] FIG. 7B shows the 10X parfocal zoom lens of FIG. 7A operating in a second state (eg, polarization 2) with near diffraction-limited imaging performance and with a 4 degree FOV. [Figure 8] FIG. 8 shows a diagram and an example of an optical system including a multifunction meta-optical system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] I. Computational Meta-Optics for 3D Imaging 3D imaging / sensing architectures based on computational metasurface flat optics offer dramatically enhanced performance and ultra-compact, flat form factors. This approach combines ultra-wide field of view (FOV) and computational imaging capabilities with just a single component optics, although in some cases, more than one optics can be used. Compact, multi-function meta-optic devices include the following features: (1) multi-function multiplexed flat optics design, (2) ultra-wide field of view (e.g., 100° to nearly 180°) with high-resolution imaging, (3) extended depth of field (EDOF), and (4) an integrated, ultra-compact, and lightweight optical architecture. The multiplexed metaoptics and wide field of view features can be separated for some implementations to provide different FOVs, e.g., 1°, 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80°, 90°, 100°, 110°, 120°, 130°, 140°, 150°, 160°, 170°, 180°, or any subrange between 1° and 180°. Advantageously, a metaoptics system having one or more metasurfaces can simultaneously achieve both wide field of view and multiplexed optical functionality without any modifications to the metaoptics system during use.

[0013] The optical structures and metasurface designs of such multifunctional meta-optics are compatible with foundry fabrication, thus enabling low-cost manufacturing and integration with commercially available image sensors and light emitters in ultra-compact sensor modules. For example, meta-optics sensor modules may have form factors of 0.1 cubic centimeters (cc) to 10 cc, or in some cases, 0.1 cc to 1 cc.

[0014] Existing 3D sensors typically rely on active illumination and / or triangulation techniques to recognize depth, which may be done, for example, in structured light (SL), time-of-flight (TOF), and active / passive stereoscopic imaging approaches. Alternatively, depth information may be extracted using depth from defocus (DFD) methods that analyze axially-dependent image aberrations that arise when defocusing an imaging system. While simplifying the optical system configuration, such DFD approaches suffer from degradation of depth accuracy or require dynamic image acquisition, since the depth resolution of conventional lenses is fundamentally limited by their point spread functions (PSFs), which change slowly with the depth of the object. The term "depth" is typically used in the art to refer to the distance of an object from an imaging lens or system.

[0015] Alternative approaches to determining depth have been developed by spatially manipulating the PSF to enhance its depth discrimination capabilities. Among the different methods, the double-helix PSF (DH-PSF) approach has been successfully shown to be effective in distinguishing depth by generating a 3D PSF that generates two lobes that continuously rotate as the depth of the object from the imaging lens or imaging system changes. The DH-PSF functionality has been realized either by incorporating a spatial light modulator (SLM) that switches its phase profile between the DH-PSF and a depth-insensitive phase, or by using a dual-aperture metasurface configuration with a pair of laterally adjacent phase masks that generate side-by-side images for capture by an image sensor. Although both approaches show improved performance in terms of depth accuracy and depth of field, the former results in a rather complex optical setup (including an SLM, a 4f correlator, and an imaging lens) and the latter relies on a shared aperture that ultimately sacrifices efficiency and camera miniaturization and is difficult to incorporate other optical functions.

[0016] 1A and 1B show a multifunctional multiplexed metasurface flat optical system, also referred to as metaoptical system 100, with significantly improved optical performance and potentially very small optical system dimensions. The metaoptical system includes a single flat transparent substrate 105 with a first multiplexed metasurface 110 (for computational imaging) positioned on the front surface (first surface) and a second metasurface 120 (for wide-field imaging) positioned on the back surface (second surface). The forward multiplexed metasurface is configured to operate in at least two modes (e.g., providing at least two optical functions) that encode the phase front of the incident beam, which differ depending on the properties of the incident light (e.g., its polarization, wavelength, incidence angle, etc.). With respect to the incidence angle, different optical functions can be derived for different incidence angle values ​​(e.g., two different elevation angles) and / or different incidence angle directions (e.g., the same elevation angle at two different azimuth angles). Furthermore, different optical functions can be derived for different orbital angular momentum. The encoding may be used to aid in post-processing of the image and / or to modulate the light differently to achieve different optical functions.

[0017] In some cases, light rays 160 having different angles of incidence (AOI) may be generated by the first metasurface 110 and then transmitted to the rear side second metasurface 120 and focused onto a planar (i.e., flat) image plane 140 where the image sensor is located, although in some implementations the image plane may be curved in one dimension (cylindrical, parabolic, etc.) or two dimensions (spherical, parabolic, etc.). The focal points may in some cases be spatially separated on the image plane 140, so that their corresponding electronic images (which may be captured, for example, by a CCD camera or CMOS imaging array) may be operated independently of each other. The separation of the light rays may depend on the polarization, wavelength, or angle of incidence of the light incident on the first metasurface 110.

[0018] Several exemplary multifunction metaoptics are considered herein. A first example is a multifunction metaoptic that can switch between at least two optical functions based on the polarization state or orbital angular momentum (OAM) state of the incident light. The polarization states may include traditional orthogonal states, such as vertical and horizontal (or sagittal and tangential), right and left circular polarization, and different elliptical polarization states. For polarization multiplexed metasurfaces, switching between polarization states can effectively select the particular function for which the metasurface is designed (e.g., converging or diverging lens). Polarization switching can be done by rotating a polarizer in the incident light beam path of an unpolarized light source, by rotating a half-wave plate in the beam path of a polarized light source, by rotating a polarized light source, etc. In some cases, a controllable liquid crystal device may be used to change the polarization state of the incident light, or the liquid crystal device may act as a filter. In such implementations, changing the polarization state effectively changes the phase profile presented by the metasurface. In other cases, filters or pixelated filter arrays with different filtering characteristics may be integrated into an image sensor or sensor pixel array, such that images generated corresponding to different light characteristics (e.g., polarization states or wavelengths) may be captured by different sensors or sensor pixels. OAM-selective metasurfaces may be constructed to capture images in different OAM modes. Such metasurfaces may further be stacked together to form multiplexed OAM metasurfaces to capture images of multiple OAM modes.

[0019] The switching of polarization (and therefore the efficient switching of meta-optical phase profiles) allows the front metasurface to capture different information of the scene, enabling high-quality 3D scene reconstruction or information extraction via post-processing. For 3D sensing or passive ranging, for example, a forward multiplexed metasurface may be designed to have at least two distinct phase profiles under light with different polarizations: (1) a depth-sensitive phase profile that produces two focal points that rotate as the object shifts in depth, and (2) a depth-insensitive phase profile that produces a depth-insensitive response, as described further below. Assuming that eight phase levels are used to cover a phase range of twoπ, the forward multiplexed metasurface can produce a total of eight .... 2 = 64 different types of meta-atoms, each providing a distinct combination of two phase values ​​under different polarizations. If more phase profiles (i.e., optical functions) and / or phase levels are included, a total of m can be added to achieve n arbitrary phase profiles with m distinct phase levels. n A meta-atom design may be used.

[0020] The posterior metasurface can be designed to be polarization insensitive (e.g., symmetric meta-atom shapes for different polarizations) to maintain a wide light collection angle under all circumstances, or polarization sensitive to further multiplex the computational process. In addition to polarization, metasurfaces can also be designed to impart different phase profiles based on other properties of the incident light (e.g., wavelength, angle of incidence, etc.). These phase profiles can provide additional multiplexing capabilities to accomplish multiple tasks, including other optical processing / computational tasks assigned to each metasurface.

[0021] Depending on the properties of the incident light, meta-atoms may also be configured to provide different functions / responses when used as individual meta-atoms or groups of meta-atoms (i.e., supercells). FIG. 1C shows an example of five different supercells 170-1, 170-2, ... 170-5, each composed of 81 unit cells 175 of meta-atoms. Each unit cell 175 may contain many meta-atoms. There may be any number of unit cells 175 that make up the supercell 170. Such supercells of meta-atoms may be in-plane (e.g., meta-atoms positioned on the same surface across a substrate), out-of-plane (e.g., meta-atoms positioned on different surfaces or layers on a substrate), or a combination of both. Multiple layers of meta-atoms may be stacked to provide different optical functions or responses.

[0022] The metasurface may include a plurality of supercells 170 arranged in an array. The supercells 170 may be configured to provide different collective optical responses depending on the characteristics of the incident light. For example, the metasurface may be characterized by at least two pitches and may operate at at least two wavelengths. For example, individual meta-atoms within a unit cell 175 and / or their spacing or pitch are configured to modulate light of a first wavelength (e.g., a smaller wavelength), and a group of multiple meta-atoms (e.g., unit cells 175, or supercells 170) and / or their spacing or pitch are configured to modulate light of a second wavelength (e.g., a larger wavelength).

[0023] Different supercells 170 may provide different optical functions. For example, the unit cells 175 of supercell 170-2 may be rearranged to form different supercells 170-3, 170-4, 170-5 to provide different optical functions, as shown in FIG. 1C. The unit cells 175 and supercell 170 may be designed to operate at a first and a second wavelength, respectively. For the four supercells 170-2, 170-3, 170-4, 170-5 shown in FIG. 1C, the unit cells 175 may provide different phase profiles (variation across the supercell) to a light beam of a first wavelength incident on the supercell 170, while a light beam of a second wavelength may see a uniform phase profile (no phase variation across the supercell). Different arrangements of unit cells may form metasurfaces to provide multiplexed functions at two or more wavelengths. For example, a first light beam of a first wavelength incident on a supercell may undergo a first optical transformation (e.g., a collimated beam of the first wavelength may be diverged by the supercell), while a second light beam of a second wavelength incident on the same supercell may undergo a second optical transformation different from the first optical transformation (e.g., a collimated beam at the second wavelength may be converged by the supercell).

[0024] 2A, 2B, and 2C show an exemplary meta-atom design and its performance at a wavelength of 670 nm. FIG. 2A shows an exemplary meta-atom 200 that includes a rectangular block 210 of a high refractive index material (e.g., amorphous silicon) on a low refractive index substrate 205 (e.g., fused silica). Varying the geometry of the block 210 in an array of meta-atoms 200 provides various polarization-dependent phase responses under x- and y-polarized light, as plotted in FIG. 2B. Each data point in FIG. 2B is for a single meta-atom design in an array of identical meta-atoms 200, each meta-atom 200 having a length y and width x, indicated by the axes on the plot. The phase difference imparted by the meta-atom 200 between x- and y-polarized light incident on the array is plotted as a relative phase value, in radians, indicated by gray shading. The entire plot includes meta-atoms with different lateral dimensions (length y and width x). The meta-atoms have a fixed height of 450 nm and a fixed pitch of 300 nm. In this example, the meta-atoms 200 are asymmetric about an optical axis that extends vertically through the center of the rectangular block 210, giving the meta-atoms different responses to different polarizations. For symmetric meta-atoms (e.g., cylinders), different wavelengths can be used to elicit different optical responses from the meta-atoms.

[0025] 2C shows a portion of a polarization-sensitive metasurface 250 constructed from meta-atoms 200 in a meta-atom library. Blocks 210 of meta-atoms 200 may vary in shape across the metasurface 250. An array of meta-atoms may be arranged to form unit cells (e.g., supercells), or building blocks, that make up the entire polarization-sensitive metasurface of a meta-optical system. Polarization-sensitive metasurfaces can be created using inverse design methods to extract information about a scene being imaged or otherwise sensed with the meta-optical system.

[0026] According to one implementation, the entire polarization-sensitive metasurface is designed to impart a depth-sensitive phase profile that can generate two focal points (for one polarization) from a single point source, where the two focal points rotate as a function of the depth / distance of the point source from the metasurface. When the distance between the point source and the metasurface is changed, the two focal points rotate in the image plane around the optical axis of the metasurface according to the depth of the object. Metasurfaces may be designed to provide optical transformations (for one polarization) such as a double helix PSF (DH-PSF) based on the phase-only superposition of Laguerre-Gaussian modes, but the performance of metasurfaces is usually limited by background noise, works over a limited range of distances between the metasurface and the point source, and provides limited depth accuracy. To overcome these limitations, we utilize a gradient-based numerical optimization method to enhance and precisely design metasurfaces that can provide improved DH-PSF intensity distributions in response to changes in distance between the object and the metasurface. The gradient-based numerical optimization method allows us to customize the inverse design targets to achieve not only compliance with manufacturing tolerances, but also improved depth-sensing accuracy and / or improved range of metasurface-to-object distance, high-resolution imaging, improved optical efficiency, and increased signal-to-noise ratio (SNR).

[0027] To improve optical performance and increase design complexity compared to existing approaches, an end-to-end design framework is used to efficiently develop meta-optical systems that can provide multiple optical functions in a single optical system. One of the optical functions may be, for example, a DH-PSF. FIG. 3 illustrates a modified Direct Binary Search (DBS) process 300 (a perturbation-based iterative method) for selecting and arranging meta-atoms to form at least one metasurface of a meta-optical system. In this process, the meta-atoms are used as building blocks to construct at least one multiplexed multifunctional metasurface to extract various information of a scene imaged or otherwise sensed by the meta-optical system. The DBS process 300 begins with an initial metasurface design (to impart an initial phase profile 310 to an incident beam) for a particular optical function. The process 300 then sequentially replaces each meta-atom across the metasurface with an alternative design from a library of different meta-atom designs and adopts the one that results in the best performance. In general, the dimensions, geometry, symmetry, pitch, and distance between meta-atoms (i.e., meta-atom pitch) of the meta-atoms can be varied to produce desired performance. In some cases, an application-specific weighted figure of merit (FOM) is first defined for the performance evaluation (e.g., PSF intensity distribution, wavefront aberration function, optical intensity distribution, efficiency, state-to-state contrast, etc.) and one or more meta-optical parameters (e.g., meta-atom design, meta-atom spacing, meta-atom dimensions, meta-atom material, optical response, meta-optical dimensions, meta-optical shape, meta-optical shape, etc.).

[0028] Optimization of a metasurface begins with an initial phase profile 310 and / or amplitude distribution to be imparted by the metasurface to an incident beam for selected input optical conditions (e.g., polarization, wavelength, bandwidth, OAM, and / or angle of incidence). At each iteration, the design parameters are perturbed (operation 320), either randomly or in a specific order. The FOM is continuously evaluated using an optical diffraction integral model (or other optical simulation or analytical model) (operation 330) to simulate the output optical field from the metasurface. The output optical field may be evaluated to determine if the perturbation on the unit cell improved the output optical field and improved the optical performance of the meta-optical system (operation 335). If the replacement did not improve the optical performance, the replacement is discarded (operation 350) and a library of meta-atoms is checked to determine if all meta-atom designs from the library have been tried (operation 345). If the replacement improved performance, the new meta-atom is retained (operation 340) and a library of meta-atoms is checked to determine if all meta-atom designs from the library have been tried (operation 345). The meta-atom designs in the library may include meta-atoms of different shapes, sizes, spacings, and / or materials. When all designs from the library have been tried for the i-th meta-atom, process 300 may move to the next (i+1)-th meta-atom in the array and repeat the steps beginning with sequential replacement of meta-atoms (operation 320). Process 300 continues until all meta-atoms of the metasurface have been perturbed at least once according to process 300.

[0029] In some cases, process 300 can be performed meta-atom-by-meta-atom for each meta-atom of a metasurface (i.e., moving through each meta-atom of the metasurface one at a time). In other cases, process 300 can be performed meta-atom-by-meta-atom for each meta-atom in a unit cell, and the unit cells can be stepped through by re-running process 300 for each unit cell. In some cases where there are identical unit cells distributed across the metasurface, all of the i-th meta-atoms that are identical and in the same position in each identical unit cell can be replaced in the same step (operation 320) that replaces the meta-atom in process 300. According to some implementations, all of the identical meta-atoms (having the same shape and size) in a metasurface, whether or not the meta-optic contains unit cells, can be replaced in the same step (operation 320) that repeats process 300 to improve the optical performance of the meta-optic.

[0030] For multiplexed, multifunctional metasurfaces, where a single meta-atom may respond differently under different conditions (e.g., under different input light characteristics), multiple objectives are included in the FOM and may be simultaneously or sequentially improved using DBS process 300. Process 300 may terminate when a predefined (e.g., user-specified) FOM improvement threshold is achieved for at least one of the optical functions provided by the meta-optics (decision 337), or when a maximum number of iterations is reached, or when the library of meta-atoms is exhausted for each meta-atom of the metasurface. The FOM may be one or more characteristics of the point spread function (e.g., intensity distribution, Strehl ratio, FWHM, etc.) and / or one or more characteristics of the modulation transfer function (e.g., contrast at a particular spatial frequency or set of spatial frequencies). In some cases, one or more other metrics may additionally or alternatively be used for the FOM (e.g., background noise, phase error, etc.). Preferably, the predefined FOM improvement is achieved for all meta-atoms before the maximum number of iterations is reached or before the library is exhausted. Using this inverse optimization method, high-performance phase profiles can be designed and tuned to extract different information of a scene (such as depth-sensitive, extended depth-of-focus, large field-of-view, or broadband metasurface phase profiles), which are significantly more versatile or computationally efficient than traditional analytical or brute-force generation solutions, respectively.

[0031] 4A, 4B, and 4C show the performance of an exemplary single-layer, depth-sensitive metaoptic (without wide-angle FOV metasurface) with a lens diameter of 1 mm, and a target distance sensing range of 5 cm to 25 cm. The metaoptic orients (rotates) the image depending on the distance of the object being imaged from the metasurface of the metaoptic. In this example, the object being imaged is a point source and is imaged as two separated point sources that rotate depending on the distance between the object and the metasurface. One way to form two separated images of a single point source with a single metaoptic is to superimpose two meta-atom patterns on the metaoptic, each pattern corresponding to a lens that focuses at a different location than the other meta-atom pattern and corresponding lens. For the metaoptic of FIG. 4A, the rotation of the two imaged point sources is approximately 80 degrees for a 20 cm change in distance. The metaoptic provides a DH-PSF optical function, as can be seen in the series of images in FIG. 4C.

[0032] In FIG. 4B, the solid line represents the target response for which the meta-optical system was designed using the DBS process 300 described above. The plotted points represent simulation results using optical analysis based on optical diffraction integral. The meta-optical system imparts a phase profile to light of a first polarization state (e.g., horizontally polarized) that generates a DH-PSF. The simulation results show that the correlation between the rotation angle and depth of the two foci accurately matches the target performance, covering an angle range and depth range of about 80° and 20 cm, respectively. These results indicate that the meta-optical system can be used to sense object depth over a large depth range based on the DH-PSF rotation angle of the recorded image.

[0033] The optical system of FIG. 4A can further impart a cubic phase profile that exhibits a nearly invariant object-to-distance response to light of a second polarization state (e.g., vertically polarized). As a result, the lens provides polarization multiplexed depth-sensitive and depth-insensitive phase profiles. Additionally, other optical computing functions can also be included in the multiple states of the multifunctional metasurface design for additional data extraction, e.g., the metasurface may encode a phase profile that operates as a 2D Laplace operator for edge detection and image discrimination, for performing second-order spatial differentiation.

[0034] FIG. 5A shows a process 500 for image reconstruction and depth estimation from light focused onto a focal plane imaging array or other detector array by a suitably designed multifunction meta-optics system. Two raw sub-images 510-1, 510-2 under different polarizations are first captured by the depth-sensitive and depth-insensitive optical functions of the optical system (e.g., as described above in FIGS. 4A-4C). The distance-insensitive function acts as an extended depth-of-field (EDOF) lens for the first polarization. The distance-sensitive function acts as a DH-PSF lens. An initial transverse image 520 is generated by deconvolution of the raw depth-insensitive sub-image 510-1 with a randomly selected point spread function (PSF) 515 generated for the EDOF lens within its designed depth-of-field range. Further, the sub-image 510-2 captured by the DH-PSF function of the meta-optics is deconvolved using the selected DH-PSF to estimate the distance to at least one object in the image. The selected DH-PSF determines the estimated distance, and the object with the sharpest features (e.g., the least fuzzy edges) is located at the estimated distance. If all objects (or objects of interest) in the image are at the same distance, a DH-PSF can be selected and several iterations of deconvolving the distance sensing sub-image 510-2 can be performed to obtain an estimated distance to the object. Once the estimated distance is obtained, the EDOFPSF can be revised to deconvolve the distance-insensitive sub-image 510-1 to improve the transverse image 520. Iterative cycles of selecting a DH-PSF and revising the EDOFPSF may be performed to improve the estimated distance to one or more objects in the transverse image 520 and improve the quality of the transverse image 520.

[0035] As an example, Scene I S The image reconstruction may be performed by solving Tikhonov's regularized least squares problem.

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[0036] If the reconstruction process involves co-optimization with the multifunction meta-optics system using variables from both sides, a different loss function L (e.g., the mean squared error with respect to the ground truth image) can be defined on the reconstructed image.

number

[0037] 5B and 5C show primary results showing highly accurate depth estimation and high-quality image reconstruction obtained over a large depth range using the process of FIG. 5A. Compared to conventional lenses without wavefront coding, multifunctional meta-optics with multiple PSFs (e.g., EDOF PSF, and DH-PSF) can provide improvements in distance sensing, extended depth of field, and broadband operation. Multifunctional metasurfaces (computational flat optics layers) can be easily fabricated on the surface or aperture of wide-angle FOV metalens to realize wide-angle, high-resolution extended depth of field 3D imaging.

[0038] The optical sensing / imaging system may include a multi-function meta-optic, a switchable filter (e.g., a switchable, polarization or wavelength filter), and at least one image sensor (e.g., a CMOS or CCD imaging array) located at an image plane of the meta-optic. Depending on the characteristics of the incident light on the system, the meta-optic can provide different optical functions to operate on the incident light to achieve different light intensity / field distributions on the image sensor. The switchable filter can be switched to selectively transmit light of different characteristics (e.g., polarization states, or wavelengths) onto the image sensor. A liquid crystal device is one example of a switchable filter that may be used to select the polarization state of light transmitted to the system or to the image sensor, or to act as a wavelength filter. The switchable filter can be used to further improve the selectivity of the light characteristics and reduce crosstalk in the optical system between light of different characteristics. In some cases, the switchable filter can further generate light output in two positions. For example, light of a first characteristic is transmitted by the filter to form a first image at a first position, and light of a second characteristic is reflected to form a second image at a second position. A switchable filter is an example of an active filter that can be physically reconfigured (e.g., rotated from a first orientation to a second orientation) under external control to perform two different optical functions. The sensing / imaging system may further include a light emitter for active illumination of the scene imaged by the system. For example, the image sensor may include a light emitter that illuminates the scene with light of different polarizations by switching between different light emitters or switching a polarizing filter between different polarization states. In another example, the sensing system may include a light emitter that illuminates the scene with light of different wavelengths by switching between different light emitters or switching between spectral filters that pass different emission wavelengths from a common light emitter. The light emitter may also be configured to emit a structured light pattern to illuminate the scene.

[0039] Parfocal Zoom Lenses FIG. 6 shows a confocal zoom lens 600 with a multiplexed metasurface architecture (a confocal zoom lens is a zoom lens that remains in focus when its magnification / focal length is changed). The confocal zoom lens 600 may include a first (incoming) metasurface MS-1 having meta-atoms 200 formed on a first surface of a first substrate 610, and a second (outgoing) metasurface MS-2 having meta-atoms 200 formed on a second surface of the same substrate or formed on a second substrate 620, as shown in FIG. 6. If the metasurfaces are on separate substrates, the substrates may be separated by an air gap 630 or another substrate. Alternatively, the metasurfaces may be on the outer and / or inner (facing) surfaces of the substrate.

[0040] The meta-atoms 200 in at least one of the metasurfaces of the confocal zoom lens operate in at least two modes that affect the incident light differently according to the properties (e.g., polarization, wavelength, angle of incidence, etc.) of the incident light. By switching, stepping, or sweeping the polarization, wavelength, angle of incidence, or other properties of the incident light, the optical functions of the first and second metasurfaces can be accessed independently. For example, the first metasurface MS-1 may operate as a converging lens for vertically polarized light and as a diverging lens for horizontally polarized light, while the second metasurface MS-2 may operate as a converging lens for both horizontally and vertically polarized light. Independently controllable changes in the focusing properties of the two metasurfaces may provide an optical zoom with a fixed track length of the optical train. (One or both metasurfaces may be sensitive to changes in the polarization or wavelength of the incident light.) In this way, variation in optical magnification can be achieved without moving one substrate 610 relative to the other substrate 620, or one metasurface MS-1 relative to the other metasurface MS-2. The parfocal zoom lens can then be implemented in a very compact package (eg, having a form factor occupying less than 10 cubic centimeters, or even less than 1 cubic centimeter).

[0041] Active or passive beam splitters or filters can be used in conjunction with the multifunctional metasurface. In one embodiment, a beam splitter (e.g., a polarizing beam splitter or a dichroic mirror) may be added to split and direct light with different properties (e.g., different polarization states or wavelengths) to different detector arrays. As a result, different images generated by the multifunctional metasurface may be captured simultaneously or sequentially by different detector arrays according to the properties of the light. Simultaneous image capture can be obtained by using light with 45 degree, elliptical, or circular polarization, and a beam splitter or filter splits the horizontal and vertical polarization components into two different optical paths. In some cases, the metasurface or multifunctional metasurface can split the horizontal and vertical polarization components into two different optical paths. In some embodiments, a pixelated filter array with different filtering properties can be integrated into the image sensor pixel array. As a result, different images generated by the multifunctional lens may be captured by different detector pixels according to the different properties of the light (e.g., polarization states, wavelengths, etc.).

[0042] Parfocal zoom lens 600 may be included in an optical system that includes an optical device 660 located at an image plane of zoom lens 600. The optical device may be an image sensor (e.g., a CMOS, or CCD imaging array) when zoom lens 600 is used to image a scene. In other implementations, described further below, optical device 660 may be an emitter array or a microdisplay when zoom lens 600 is used to project an image.

[0043] In addition to passive imaging / sensing, the parfocal zoom lens 600 of the present invention may further operate in an active illumination mode by including an illuminator 650. For example, the parfocal zoom lens 600 may be used in conjunction with an illuminator 650 that illuminates a scene with light of different polarizations by switching between different illuminators or polarizing filters. Liquid crystal devices may also be used to adjust the polarization state of the light or to act as wavelength filters. In another embodiment, the parfocal zoom lens 600 may be used in conjunction with an illuminator 650 that illuminates a scene with light of different wavelengths by switching between different illuminators or spectral filters. Structured light patterns may also be utilized to illuminate a scene.

[0044] In some implementations, the metasurface MS-1 of a parfocal zoom lens or other lens may be configured to achieve a variable aperture by selectively allowing or preventing a zone of the metasurface (e.g., zone 1 of metasurface MS-1 in FIG. 6) from transmitting incident light in a particular state (e.g., polarization state, wavelength, AOI, incident position, etc.). For example, horizontally polarized light (indicated by solid lines in FIG. 6) entering one or more selected zones of the metasurface (e.g., outer zone 2 of MS-1 in FIG. 6) may be deflected and captured inside the first substrate via total internal reflection, as illustrated, while vertically polarized light (indicated by dashed lines) is transmitted and reshaped through the same zone. Some zones of metasurface MS-1, or any metasurface, may also be designed to absorb, reflect, or otherwise block or attenuate incident light. In some cases, a zone on a first metasurface of a metaoptic (e.g., zone 2 on metasurface MS-1) can deflect light of a first wavelength, polarization, or angle of incidence to a region on a subsequent surface where the deflected light is reflected, blocked, or otherwise prevented from participating in imaging, patterning, or optical sensing by the metaoptic or optical system, while light of a second wavelength, polarization, or angle of incidence may not be polarized by the first zone and may participate in imaging, patterning, or optical sensing.

[0045] 7A and 7B show an example configuration of a parfocal zoom lens 600 that can provide at least 10X optical zoom and is implemented in a structure as shown in FIG. 6. In some cases, 5X to 50X optical zoom may be achieved with a parfocal zoom lens utilizing meta-atoms on two metasurfaces according to the described implementation. For the illustrated example operating at 670 nm wavelength, polarization multiplexed metasurfaces MS-1, MS-2 may be used, where the meta-atoms are formed from amorphous silicon and the substrate is formed from silica. Imaging at other wavelengths is possible by selecting different materials and / or scaling the size and spacing of the meta-atoms. Spaces between multiple surfaces in the optical system (including optical component surfaces, window surfaces, image sensor surfaces, etc.) may be filled with air or another medium (e.g., epoxy, glass / polymer spacers, etc.).

[0046] The confocal zoom lens 600 of Figures 7A and 7B has an entrance pupil diameter that is controllably adjusted from 0.8 mm to 1.6 mm, although other values ​​are possible. The fixed track length from the first metasurface to the image plane is about 4.82 mm. The back focal length is about 2.46 mm. The field of view may be varied from 40° to 4° between the two polarization states while achieving near diffraction-limited imaging performance. Switching between horizontal and vertical polarization states changes the effective focal length of the confocal zoom lens 600 by a factor of about 10X. The effective aperture of the confocal zoom lens can be varied between two or more sizes by configuring two or more zones of the metasurface (e.g., MS-1) to have different responses to incident light of different characteristics (e.g., polarization, wavelength, incidence angle characteristics). For example, a portion or zone of the meta-atom array (e.g., zone 2 in FIG. 6) may be configured to internally reflect light of a first polarization and transmit light of a second polarization, thereby varying the transmittance of the zone and the effective aperture size of the confocal zoom lens. In the illustrated example of FIG. 6, light of the first polarization is coupled into the first substrate 610 at an angle less than the critical angle of the first substrate. In another example, the phase imparted by a portion of the meta-atom array for a first polarization or wavelength can selectively direct a portion of the incident beam in one direction compared to the phase imparted for a second polarization or wavelength such that the effective aperture size of the optical system can be varied between two values. More generally, the spectral, angular, and / or spatial response of a portion of the meta-atom array can be designed to selectively modulate, transmit, or block a portion of the light beam incident on the meta-atom array according to the wavelength, AOI, and incident position of the incident beam, respectively, to achieve multiple optical functions for a meta-optical system, such as the confocal zoom lens described above. The selective modulation (eg, beam steering), transmission, or blocking may be switched between two or more states.

[0047] The zoom optical sensing / imaging system may include a zoom meta-optics such as those in FIG. 6 and FIG. 7A, a switchable filter, and an image sensor. Depending on the characteristics of the light, the meta-optics can provide different optical functions to operate on the incident light to achieve variable magnification or light intensity / field distribution on the image sensor located at the image plane of the optical system. The switchable filter can be switched to selectively transmit light of different characteristics (e.g., a polarization state selected from among different polarization states, or a wavelength selected from among different wavelengths) onto the image sensor. The liquid crystal modulator may also be used to adjust the polarization state of the light or to act as a wavelength filter. The optical sensing / imaging system may further include a light emitter for active illumination. For example, the sensing / imaging system may include a light emitter that illuminates a scene with light of different polarizations by switching between different light emitters or polarizing filters (e.g., tunable liquid crystal waveplates or filters). In another embodiment, the sensing / imaging system may include a light emitter that illuminates a scene with light of different wavelengths by switching between different light emitters or spectral filters. Structured light patterns may also be utilized.

[0048] The parfocal zoom lens of FIG. 6 or FIG. 7A may easily enable high quality image / pattern projection with variable magnification or projection of various patterned light intensity / field distributions when used in reverse with an image sensor replaced by an emitter array (e.g., VCSEL, microLED, etc.) or microdisplay. The reconfigurable optical projector system may include at least one zoom meta-optics lens, an emitter array or microdisplay, and optional switchable filters, as described above. Depending on the characteristics of the light, the meta-optics modulates the light to provide different optical functions to achieve variable magnification or light intensity / field distribution of the emitted light by the reconfigurable optical projector system. If necessary, the switchable filters can be switched to selectively transmit light of different characteristics (e.g., polarization state or wavelength) emitted by the emitter array. For example, the optical projector system may include an emitter array or microdisplay that projects an image with light of different polarizations by switching between different emitters or polarizing filters. The liquid crystal device may also be used to adjust or select the polarization state of the light or to act as a wavelength filter. In another embodiment, the optical projector system may include an array of emitters or a microdisplay that projects images with different wavelengths of light by switching between different emitters or spectral filters. Structured light patterns may also be projected.

[0049] Additional optical functions can be achieved using one, two, or more metasurfaces in addition to those described for the optical devices above. For example, additional metasurfaces may be used for beam steering on a distance sensing meta-optic or a confocal zoom lens to allow for sweeping and imaging a larger field of view than would be possible without beam steering. In some implementations, different optical functions may be combined in one metasurface. For example, half of the meta-atoms on the surface may be designed to provide a first optical function and half of the meta-atoms on the surface may be designed to provide a second optical function. The two halves of the meta-atoms may be superimposed on one another, distributed across the metasurface, or separated into different spatial regions or unit cells. According to one embodiment, meta-atoms for imaging functions (e.g., distance sensing, or a confocal zoom lens) may be combined with meta-atoms for beam steering, each of which may have a base selectable between two or more states based on different properties of the incident light. In addition to zoom, beam steering, or computational imaging functions (such as distance sensing, or pattern generation), other optical functions may also be realized. In general, depending on the characteristics of the incident light, a meta-optic (including one, two, or more metasurfaces) may be configured to provide different optical functions to generate variable light intensity / electric field distributions. Thus, reconfigurable optical sensing, imaging, and / or image projection based on light properties such as polarization, OAM, wavelength, and AOI may be realized.

[0050] FIG. 8 illustrates an example of an optical system 800 including a multifunction meta-optic 100 and a switchable filter 810. The meta-optic 100 may be positioned to view a scene or object 802. The optical system 800 may be configured to form an image on an image plane 820, which may be flat (as shown) or curved. At least one optical device 660 may be located at the image plane to record an image (e.g., an image sensor) or to project an image (e.g., an image projector). Some systems may include a light source 805 (such as an emitter array) for generating light having two or more optical properties (e.g., different polarization states, different wavelengths, different OAMs). The systems described may further include at least one image sensor and / or projector. In general, the reconfigurable multifunction optical sensing, imaging, and / or projection systems described herein may include at least one meta-optic and a switchable filter (optionally optical illumination or projection). Depending on the properties of the light, the meta-optic (which may include one, two, or more metasurfaces) may operate on the light incident on the meta-optic to provide different optical functions, for example, achieving variable light intensity / field distributions on an image sensor or emitted by a light source or microdisplay.

[0051] The multi-function meta-optic may be implemented and / or included within an optical system in a variety of configurations. Exemplary configurations are listed below. Corresponding methods of using the meta-optic and operating the optical system may also be implemented.

[0052] (1) An optical system comprising: a substrate; and a metasurface including a plurality of meta-atoms disposed on a first side of the substrate and configured to impart a depth-sensitive phase profile to a first incident light in a first state and to impart a depth-insensitive phase profile to a second incident light in a second state, different from the first state.

[0053] (2) The optical system of configuration 1, wherein the depth-sensitive phase profile is characterized by two foci whose positions vary with depth, and the depth-insensitive phase profile includes a cubic phase profile.

[0054] (3) The optical system according to configuration 1 or 2, wherein the first state is a first polarization state and the second state is a second polarization state.

[0055] (4) The optical system of configurations 1 or 2, wherein the first state is a first wavelength state and the second state is a second wavelength state.

[0056] (5) The optical system of any one of configurations 1 to 4, further comprising a second metasurface disposed on a second side of the substrate opposite the first side of the substrate and configured to form an image on an image plane of a scene viewed by the optical system.

[0057] (6) The optical system according to configuration 5, wherein the image plane is flat.

[0058] (7) The optical system of configuration 6, wherein the second metasurface is configured to direct the first incident light and the second incident light toward the image plane.

[0059] (8) An optical sensing system comprising: The optical system according to any one of configurations 1 to 7, a filter in optical communication with the optical system; a first image sensor in optical communication with the filter to receive the first incident light in a first state and not to receive the second incident light in a second state; and a second image sensor in optical communication with the filter to receive the first incident light in the second state and not receive the first incident light in the first state.

[0060] (9) An optical sensing system comprising: The optical system according to any one of configurations 1 to 7, a switchable filter in optical communication with the optical system; An optical sensing system comprising an image sensor in optical communication with an optical system.

[0061] (10) The optical sensing system of configuration 9, wherein the switchable filter, in a first configuration, transmits a first light of a first polarization state and suppresses transmission of a second light of a second polarization state, and, in a second configuration, transmits a second light of the second polarization state and suppresses transmission of the first light of the first polarization state.

[0062] (11) The optical sensing system of configuration 9, wherein the switchable filter, in a first configuration, transmits a first light of a first wavelength and suppresses transmission of a second light of a second wavelength, and, in a second configuration, transmits a second light of a second wavelength and suppresses transmission of the first light of the first wavelength.

[0063] (12) The optical sensing system according to any one of the first to eleventh aspects, An optical sensing system comprising light emitters configured to illuminate a scene viewed by an optical system with light of different polarizations.

[0064] (13) The optical sensing system according to any one of the first to eleventh aspects, The light system further comprises an illuminator configured to illuminate a scene viewed by the optical system with light of different wavelengths.

[0065] (14) A multifunction optical system comprising: a first transparent substrate; a second transparent substrate spaced from the first transparent substrate; a first metasurface comprising a first plurality of meta-atoms disposed on a first surface of the first transparent substrate; and a second metasurface comprising a second plurality of meta-atoms disposed on a second surface of the second transparent substrate, wherein the first metasurface and the second metasurface are configured to focus a first incident light in a first state onto an image plane having a first magnification or perform a first optical function, and to focus a second incident light in a second state different from the first state onto an image plane having a second magnification different from the first magnification or perform a second optical function different from the first optical function, wherein a relative position of the first transparent substrate, the second transparent substrate, and the image plane remains unchanged when focusing the first incident light into the first state and focusing the second incident light into the second state.

[0066] (15) The multifunction optical system of configuration 14, wherein the first metasurface is configured to converge a first incident light in a first state and diverge a second incident light in a second state, and the second metasurface is configured to converge the first incident light in the first state and converge the second incident light in the second state, such that the multifunction optical system functions as a parfocal zoom lens.

[0067] (16) The multifunction optical system of configuration 14, wherein the first metasurface defines a first zone configured to transmit a first incident light in a first state and a second incident light in a second state, and a second zone configured to transmit the first incident light in the first state and block, absorb, reflect, and / or deflect the second incident light in the second state.

[0068] (17) The multifunction optical system of configuration 14, wherein the first metasurface defines a first zone configured to transmit a first incident light in a first state and a second incident light in a second state, and a second zone configured to transmit the first incident light in the first state and couple the second incident light into the first transparent substrate at an angle less than a critical angle of the first transparent substrate in the second state.

[0069] (18) A multifunction optical system comprising: a transparent substrate; a first metasurface comprising a first plurality of meta-atoms disposed on a first surface of the transparent substrate; and a second metasurface comprising a second plurality of meta-atoms disposed on a second surface of the transparent substrate or on a second surface of a second transparent substrate, wherein the first metasurface and the second metasurface are configured to perform a first optical function for a first incident light in a first state and a second optical function for a second incident light in a second state different from the first state, wherein the first optical function comprises distance sensing, projecting an image, or projecting a pattern of the first incident light.

[0070] (19) The multifunction optical system of configuration 18, wherein the first metasurface is configured to converge a first incident light in a first state and diverge a second incident light in a second state, and the second metasurface is configured to converge the first incident light in the first state and converge the second incident light in the second state, such that the multifunction optical system functions as a parfocal zoom lens.

[0071] (20) The multifunction optical system of configuration 18, wherein the first metasurface defines a first zone configured to transmit a first incident light in a first state and a second incident light in a second state, and a second zone configured to transmit the first incident light in the first state and block, absorb, reflect, and / or deflect the second incident light in the second state.

[0072] (21) The multifunction optical system of configuration 18, wherein the first metasurface defines a first zone configured to transmit a first incident light in a first state and a second incident light in a second state, and a second zone configured to transmit the first incident light in the first state and couple the second incident light in the second state to a region of the second metasurface configured to block, absorb, reflect, and / or deflect the second incident light.

[0073] (22) An optical sensing / imaging system comprising: a multifunction optical system according to any one of configurations 18 to 21; a switchable filter in optical communication with the multifunction optical system; and an image sensor in optical communication with the multifunction optical system, wherein the switchable filter transmits a first incident light of a first polarization state, a first wavelength, or a first orbital angular momentum in a first configuration, and transmits a second incident light of a second polarization state, a second wavelength, or a second orbital angular momentum in a second configuration.

[0074] (23) The optical sensing / imaging system of any one of configurations 18 to 22, further comprising a light emitter configured to illuminate a scene viewed by the multifunction optical system with light of different wavelengths, different polarization states, or different orbital angular momentum.

[0075] (24) An optical projection system comprising: a multifunction optical system according to any one of configurations 18 to 21; a switchable filter in optical communication with the multifunction optical system; and an array of light emitters in optical communication with the multifunction optical system, wherein the switchable filter is configured to selectively transmit a first incident light of a polarization state selected from among different polarization states, a wavelength selected from among different wavelengths, or an orbital angular momentum selected from among different orbital angular momentum.

[0076] (25) The optical projection system of configuration 24, wherein the light emitter array is a microdisplay.

[0077] Conclusion While 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 that may perform the functions and / or obtain one or more of the results and / or advantages described herein, and each such variation and / or modification is deemed to be within the scope of the embodiments of the invention described herein. Moreover, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary, and that the actual parameters, dimensions, materials, and / or configurations will depend on the particular application in which the teachings of the invention are used. Those skilled in the art will recognize, or be able to ascertain, using no more than routine experimentation, many equivalents to the specific inventive embodiments described herein. Thus, the foregoing embodiments are presented by way of example only, and it will be understood that, within the scope of the appended claims and their equivalents, the embodiments of the invention may be practiced otherwise than as specifically described and claimed. The inventive embodiments of the present disclosure are directed to each individual feature, system, article, material, kit, and / or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and / or methods is included within the inventive scope of the present disclosure, if such features, systems, articles, materials, kits, and / or methods are not mutually inconsistent.

[0078] Also, various inventive concepts may be embodied as one or more methods, examples of which are provided. The acts performed as part of a method may be ordered in any suitable manner. Thus, embodiments may be constructed to perform acts in an order other than that illustrated, including performing some acts simultaneously despite being shown as sequential acts in the illustrated embodiments.

[0079] All definitions and uses herein should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and / or ordinary meanings of the defined terms.

[0080] As used herein, in the specification and the claims, the indefinite articles "a" and "an" should be understood to mean "at least one," unless clearly indicated to the contrary.

[0081] The term "and / or" as used herein in the specification and claims should be understood to mean "either or both" of the elements so conjoined, i.e., elements that are conjunctive in some cases and disjunctive in other cases. Multiple elements listed with "and / or" should be construed in the same manner, i.e., "one or more" of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the "and / or" clause, whether related or unrelated to the elements specifically identified. Thus, as a non-limiting example, a reference to "A and / or B," when used in combination with open-ended language such as "comprising," can refer in one embodiment to only A (optionally including elements other than B), in another embodiment to only B (optionally including elements other than A), and in yet another embodiment to both A and B (optionally including other elements).

[0082] As used herein and in 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" shall be interpreted as being inclusive, i.e., including at least one of, but also including two or more of, the several or listed elements, and optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as "only one of" or "exactly one of," or "consisting of," when used in the claims, shall refer to the inclusion of exactly one element of the several or listed elements. In general, as used herein, the term "or" shall only be interpreted as indicating exclusive alternatives (i.e., "one or the other, but not both") when preceded by an exclusive term, such as "either," "one of," "only one of," or "exactly one of." "Consisting essentially of," when used in the claims, shall have its ordinary meaning as used in the field of patent law.

[0083] As used in this specification and claims, the phrase "at least one" in connection with a list of one or more elements should be understood to mean at least one element selected from one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed in the list of elements, and not excluding any combination of elements in the list of elements. This definition also allows for the optional presence of elements other than those specifically identified in the list of elements to which the phrase "at least one" refers, whether related or unrelated to the specifically identified elements. Thus, as a 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 refer in one embodiment to at least one, optionally two or more, A, and no B (and optionally including elements other than B); in another embodiment to at least one, optionally two or more, B, and no A (and optionally including elements other than A); in yet another embodiment to at least one, optionally two or more, A, and at least one, optionally two or more, B (and optionally including other elements); and so forth.

[0084] In the claims and the above specification, all transitional phrases, such as "comprising," "including," "holding," "having," "including," "involving," "holding," "comprising," etc., are to be understood to be open-ended, i.e., meaning including, but not limited to. Only the transitional phrases "consisting of" and "consisting essentially of" shall be closed or semi-closed transitional phrases, respectively, as defined in the United States Patent Office Manual of Patent Examining Procedures, Section 2111.03.

Claims

1. A substrate, a metasurface including a plurality of meta-atoms disposed on a first side of the substrate and configured to impart a depth-sensitive phase profile to a first incident light in a first state and to impart a depth-insensitive phase profile to a second incident light in a second state different from the first state; Equipped with each meta-atom of the plurality of meta-atoms is a microfabricated structure disposed on a first side of the substrate, and the first incident light and the second incident light are detectable by a CCD camera or a CMOS imaging array; optical system.

2. The optical system of claim 1 , wherein the depth-sensitive phase profile is characterized by two foci whose positions vary with depth, and the depth-insensitive phase profile comprises a cubic phase profile.

3. The optical system of claim 1 , wherein the first state is a first polarization state and the second state is a second polarization state.

4. The optical system of claim 1 , wherein the first state is a first wavelength state and the second state is a second wavelength state.

5. 10. The optical system of claim 1, further comprising a second metasurface disposed on a second side of the substrate opposite the first side of the substrate and configured to form an image on an image plane of a scene viewed by the optical system.

6. The optical system of claim 5 wherein the image plane is flat.

7. The optical system of claim 6 , wherein the second metasurface is configured to direct the first incident light and the second incident light toward the image plane.

8. 1. An optical sensing system, comprising: The optical system according to claim 1 ; a filter in optical communication with the optical system; a first image sensor in optical communication with the filter to receive the first incident light in the first state and not receive the second incident light in the second state; a second image sensor in optical communication with the filter to receive the first incident light in the second state and not receive the first incident light in the first state; An optical sensing system comprising:

9. 1. An optical sensing system, comprising: The optical system according to claim 1 ; a switchable filter in optical communication with the optical system; an image sensor in optical communication with the optical system; An optical sensing system comprising:

10. 10. The optical sensing system of claim 9, wherein the switchable filter, in a first configuration, transmits first light of a first polarization state and suppresses transmission of second light of a second polarization state, and, in a second configuration, transmits the second light of the second polarization state and suppresses transmission of the first light of the first polarization state.

11. 10. The optical sensing system of claim 9, wherein the switchable filter, in a first configuration, transmits first light at a first wavelength and suppresses transmission of second light at a second wavelength, and, in a second configuration, transmits the second light at the second wavelength and suppresses transmission of the first light at the first wavelength.

12. The optical sensing system of claim 9 , further comprising an illuminator configured to illuminate a scene viewed by the optical system with light of different polarizations.

13. The optical sensing system of claim 9 , further comprising an illuminator configured to illuminate a scene viewed by the optical system with light of different wavelengths.

Images