Porosity-metasurface and hybrid refraction-metasurface imaging systems

Abstract

Hybrid imaging systems with conventional optical elements and metasurface elements and light sources and / or detectors, and methods of making and operating such optical arrangements are provided. The systems and methods describe integrating apertures with metasurface elements and integrating refractive optics with metasurface elements in illumination sources and sensors.

Description

Technical Field

[0001] The present disclosure relates to optical arrangements of metasurface elements, integrated systems having refractive optics, light sources and / or detectors and such metasurface elements, and methods of manufacturing such optical arrangements and integrated systems. Background Art

[0002] Metasurface elements are diffractive optical devices in which individual waveguide elements have sub-wavelength spacing and have a planar profile. Metasurface elements have recently been developed for use in the UV-IR band (300 to 10,000 nm). Compared to traditional refractive optical devices, metasurface elements suddenly introduce a phase shift to the light field. This makes the thickness of the metasurface element comparable to the wavelength of light that the metasurface element is designed to operate, while the thickness of traditional refractive surfaces is 10 to 100 times (or more) larger than the wavelength of light that the refractive surface is designed to operate. In addition, metasurface elements do not vary in the thickness of the constituent elements, and are therefore able to shape light without any curvature, which is required for refractive optical devices. Compared to traditional diffractive optical elements (DOEs), such as binary diffractive optical devices, metasurface elements are able to impart a range of phase shifts on the incident light field, at least the metasurface element can have a phase shift between 0 and 2π, where the range has at least 5 different values, while binary DOEs can only impart two different phase shift values ​​and are typically limited to a phase shift of 0 or 1π. Compared to multi-level DOE, metasurface elements do not require the height of their constituent elements to change along the optical axis, only the in-plane geometry of the metasurface element features changes. Summary of the invention

[0003] The present application relates to optical arrangements of metasurface elements, integrated systems having light sources and / or detectors and such metasurface elements, and methods for manufacturing such optical arrangements and integrated systems.

[0004] Many embodiments relate to an imaging system comprising:

[0005] at least one image sensor;

[0006] a substrate layer having a substrate thickness disposed at a first distance above the at least one image sensor, the substrate layer being configured to be transmissive to a target wavelength of light, the substrate layer having a first surface distal from the at least one image sensor and a second surface proximate to the at least one image sensor;

[0007] an aperture disposed on the first surface of the substrate and having an aperture opening disposed therein; and

[0008] a single layer of a plurality of identical or unique nanostructured elements comprising a metasurface disposed on the second surface such that light impinging on the aperture openings passes through at least a portion of the metasurface such that a specified angular deflection is imparted thereby;

[0009] wherein the distance between the apertures and the layer of metasurface elements is separated by a second distance determined by the thickness of the substrate; and

[0010] The layers of apertures and metasurface elements are configured to collect light having a specified operating bandwidth across a specified field of view and to shift incident light so that it is focused on the at least one image sensor at a chief ray angle of zero or near zero degrees.

[0011] In yet many embodiments, the system further includes a glass cover disposed atop the at least one image sensor.

[0012] In still further embodiments, the first distance is determined by a spacer layer comprising one of a solid spacer material or an air gap.

[0013] In still further embodiments, the field of view is at least ±30 degrees.

[0014] In still yet many embodiments, the system further includes a narrow bandwidth optical filter disposed between the metasurface element and the at least one image sensor.

[0015] Various embodiments are directed to an imaging system comprising:

[0016] at least one image sensor;

[0017] a substrate layer having a substrate thickness, the substrate layer being configured to be transmissive to a target wavelength of light, the substrate layer having a first surface distal from the at least one image sensor and a second surface proximate to the at least one image sensor;

[0018] an aperture disposed over the substrate and having an aperture opening disposed therein; and

[0019] a single layer of a plurality of identical or unique nanostructured elements comprising a metasurface disposed on one of the first surface or the second surface such that light impinging on the aperture openings passes through at least a portion of the metasurface such that a specified angular deflection is imparted thereby;

[0020] wherein the distance between the pores and the supersurface layer is separated by a first distance; and

[0021] The pores and the metasurface layer are configured to collect light with a specified operating bandwidth across a specified field of view and to shift incident light so that it is focused on the at least one image sensor at a chief ray angle of zero or near zero degrees.

[0022] In yet various embodiments, the system further includes an air gap between the second surface of the substrate and the image sensor.

[0023] In still various embodiments, a spacer layer is disposed within the air gap.

[0024] In yet various other embodiments, the supersurface layer is disposed on the first surface.

[0025] In still further various embodiments, the system further includes a narrow bandwidth optical filter disposed on the second surface between the metasurface element and the at least one image sensor.

[0026] In yet other various embodiments, at least a portion of the pores are interconnected with the first surface.

[0027] In yet various other embodiments, the supersurface layer is disposed on the second surface.

[0028] In yet further various embodiments, the image sensor is in contact with the second surface.

[0029] In yet various other embodiments, the field of view is at least ±30 degrees.

[0030] Several embodiments relate to an imaging system comprising:

[0031] at least one image sensor;

[0032] a substrate layer having a substrate thickness, the substrate layer being configured to be transmissive to a target wavelength of light, the substrate layer having a first surface distal from the at least one image sensor and a second surface proximate to the at least one image sensor;

[0033] at least one refractive lens disposed above the substrate and configured to focus illumination light on the first surface of the substrate layer; and

[0034] a single layer of a plurality of identical or unique nanostructured elements comprising a metasurface disposed on one of the first surface or the second surface such that light impinging on the at least one refractive lens passes through at least a portion of the metasurface elements such that an angular deflection is imparted thereby;

[0035] wherein the at least one refractive lens is separated from the layer of metasurface elements by a first distance; and

[0036] wherein the layers of refractive lenses and metasurface elements are configured to collect light having a specified operating bandwidth across a specified field of view and to shift incident light so that it is focused on the at least one image sensor at a chief ray angle of zero or near zero degrees.

[0037] In yet further embodiments, the system further includes an air gap between the second surface of the substrate and the image sensor.

[0038] In still further embodiments, a spacer layer is disposed within the air gap.

[0039] In yet further embodiments, the supersurface layer is disposed on the first surface.

[0040] In still further embodiments, the system further includes a narrow bandwidth optical filter disposed on the second surface between the metasurface element and the at least one image sensor.

[0041] In yet further embodiments, at least a portion of at least one of the refractive lenses is interconnected with the first surface.

[0042] In yet some other embodiments, the supersurface layer is disposed on the second surface.

[0043] In still further embodiments, the image sensor is in contact with the second surface.

[0044] In yet further embodiments, the field of view is at least ±30 degrees.

[0045] In still further embodiments, the at least one refractive lens is selected from the group consisting of plano-convex, convex-plan, bi-convex, bi-concave, plano-concave, or concave-plan.

[0046] In yet further embodiments, the system includes at least two refractive lenses, the at least two refractive lenses comprising a convex-concave lens and a meniscus-convex lens.

[0047] In yet some further embodiments, the system comprises at least three refractive lenses, wherein the at least three refractive lenses include a convex-concave lens, a bi-convex lens, and a concave-planar lens.

[0048] In various of the above embodiments, at least the imaging sensor and the metasurface have a rectangular geometry.

[0049] In yet various of the above embodiments, at least one refractive lens proximate to the metasurface has a circular geometry.

[0050] In still various above embodiments, the image sensor is characterized by a vertical dimension v and a horizontal dimension h, and wherein the at least one refractive lens is characterized by an f-number N of the lens, wherein N is defined as N=f / D, wherein f is the focal length of the optical system and D is the diameter of the lens, and wherein the metalens width is given by: =v+f / N, and wherein the metalens length I is given by: l=h+f / N.

[0051] Additional embodiments and features are described in part in the following description, and in part will become apparent to those skilled in the art after reference to this specification, or may be learned by practicing the present disclosure. A further understanding of the nature and advantages of the present disclosure may be achieved by reference to the remainder of this specification and the drawings, which form a part of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The description will be more fully understood with reference to the following drawings, which present exemplary embodiments of the invention and should not be construed as a complete recitation of the scope of the invention.

[0053] Figure 1 A schematic diagram is provided according to an embodiment of the present invention, which illustrates a pore-metasurface imaging system with a glass cover above an image sensor.

[0054] Figure 2 A schematic diagram is provided according to an embodiment of the present invention, which illustrates a ray tracing diagram, wherein the ray tracing diagram includes Figure 1 Chief ray angle at the image sensor plane of the pore-metasurface imaging system.

[0055] Figure 3 A schematic diagram is provided according to an embodiment of the present invention, which illustrates a pore-metasurface imaging system having an air gap between the pore and the metasurface.

[0056] Figure 4 A schematic diagram is provided according to an embodiment of the present invention, which illustrates a ray tracing diagram, wherein the ray tracing diagram includes Figure 3 Chief ray angle at the image sensor plane of the pore-metasurface imaging system.

[0057] Figure 5 A schematic diagram is provided according to an embodiment of the present invention, which illustrates a pore-metasurface imaging system incorporating an air gap above the image sensor and a metasurface layer closer to the object plane.

[0058] Figure 6 A schematic diagram is provided according to an embodiment of the present invention, which illustrates a pore-metasurface imaging system having an air gap above the image sensor and a metasurface layer closer to the image plane.

[0059] Figure 7A schematic diagram is provided according to an embodiment of the present invention, which illustrates an pore-metasurface imaging system having an air gap above the image sensor and a spacer between the pore and the metasurface.

[0060] Fig. 8A Data graphs are provided according to embodiments of the present invention that show relative illumination versus field of view for a pore-metasurface imaging system.

[0061] Figure 8B Data graphs are provided according to embodiments of the present invention that show the field of view versus the degree of distortion for a pore-metasurface imaging system.

[0062] Figure 8C A data graph is provided according to an embodiment of the present invention, which shows the modulus transfer function over a 40-degree field of view of a pore-metasurface imaging system.

[0063] Fig.8D Images of standard test targets taken using a pore-metasurface imaging system according to an embodiment of the present invention are provided.

[0064] Fig. 9 Schematic diagrams illustrating a single refractive element and metasurface hybrid imaging system are provided according to embodiments of the present invention.

[0065] Fig. 10A and 10B Schematic diagrams illustrating multiple refractive elements and a metasurface hybrid imaging system are provided according to embodiments of the present invention.

[0066] Fig.11A A schematic diagram of an image sensor wafer according to an embodiment of the present invention is provided.

[0067] Fig. 11B A schematic diagram of an image sensor die according to an embodiment of the invention is provided.

[0068] Fig. 12A A schematic diagram of a spacer wafer according to an embodiment of the present invention is provided.

[0069] Fig. 12B A schematic diagram of a spacer according to an embodiment of the present invention is provided.

[0070] Fig.13 A schematic diagram is provided illustrating an integrated hybrid imaging system incorporating refractive elements and metasurface elements and spacers in accordance with an embodiment of the present invention.

[0071] Fig.14 Schematic diagrams are provided illustrating an integrated hybrid imaging system incorporating a refractive element with a metasurface element in accordance with an embodiment of the present invention.

[0072] Fig.15A schematic diagram is provided that illustrates a fabrication process for a hybrid refractive element and metasurface imaging system in accordance with an embodiment of the present invention.

[0073] Fig.16 Schematic diagrams are provided illustrating an imaging system incorporating rectangular metasurface lens elements according to an embodiment of the present invention.

[0074] Fig.17A and 17B A schematic diagram is provided according to an embodiment of the present invention, which illustrates imaging sensing ( Fig.17A ) and rectangular metasurface lens elements ( Fig. 17B )'s relative size.

[0075] Figures 18A to 18D A schematic diagram is provided that illustrates an optical system of N number of apertures on N number of rectangular lenses on a single image sensor in accordance with an embodiment of the present invention. DETAILED DESCRIPTION

[0076] Turning now to the drawings, hybrid imaging systems with conventional optical elements and metasurface elements and light sources and / or detectors, and methods of making and operating such optical arrangements are provided. Many embodiments relate to systems and methods for integrating apertures and metasurface elements in illumination sources and sensors. Various embodiments relate to systems and methods for integrating refractive optics and metasurface elements in illumination sources and sensors.

[0077] Many embodiments of optical imaging systems may incorporate a single aperture and a single metasurface layer that can be used to correct aberrations over a large field of view. Many embodiments of such single aperture and metasurface imaging systems are configured to be telecentric over a large field of view (e.g., having an angle of incidence close to 0 degrees at the image sensor plane) so that there is no falloff of relative illumination over the field of view (e.g., so that the intensity of on-axis light rays is nearly the same as the intensity at the edge of the field of view).

[0078] In many embodiments, hybrid refractive optics and metasurface imaging systems may include metasurface elements that are standalone (i.e., not directly integrated into the system with a specific illuminator or sensor). In some embodiments, the optical system may consist of a single physical component or substrate with metasurface elements disposed on either side thereof. In some embodiments, multiple refractive optics may be combined with at least one metasurface element to make a more complex system.

[0079] In embodiments of hybrid aperture or refractive optical devices and metasurface imaging systems, the metasurface may be disposed on a surface of a supporting substrate facing the aperture or facing the imaging system. In various embodiments, an air gap may be disposed between the aperture and the metasurface structure and / or between the metasurface substrate and the imaging system. The air gap between the elements may further include a spacer structure to provide support for the elements.

[0080] In many embodiments, the metasurface elements may be freestanding or may be embedded within another material. In various such embodiments, the choice of the embedded material includes appropriate selection of refractive index and absorption properties. In many such embodiments, the embedded material may provide mechanical stability and protection as well as additional design freedom, thereby enabling the metasurface to perform the desired optical function.

[0081] In some embodiments, a spacer layer with a defined thickness (e.g., working distance) may be deposited on a CMOS image sensor, LED, VCSEL, etc. to implement an optical distance suitable for a desired camera design, illuminator design, or optimal system performance. In various such embodiments, the spacer layer material may be organic or inorganic, and may have a lower refractive index than the dielectric elements making up the metasurface. In some such embodiments, the thickness of the spacer layer may be modified to provide appropriate optical spacing for a particular optical system.

[0082] Various embodiments also relate to methods for manufacturing hybrid metasurface imaging systems. In some such embodiments, the method involves manufacturing metasurface elements on a wafer with other devices such as sensors or illuminators, thereby avoiding expensive manufacturing processes in some embodiments, such as mechanical assembly of small-size elements or active alignment of optical devices with sensors. In some such embodiments, the metasurface element can be integrated with the sensor (or illuminator) in a series of operations of semiconductor manufacturing. In many such embodiments, the sequence may include: (i) sensor or illuminator, (ii) optional microlens array / collimator, optional filter, optional spacer layer, optional metasurface element, optional additional spacer layer, optional refractive optical device or aperture element, optional anti-reflection (AR) layer, optional protective layer. In many such embodiments, the element sequence may include: (i) sensor or illuminator, (ii) optional microlens array / collimator, optional filter, optional spacer layer, optional metasurface element, optional additional spacer layer, and optional refractive element or aperture.

[0083] Embodiments for implementing a pore / metasurface imaging system

[0084] Typically, in order to form an optical system that is corrected for aberrations over a selected field of view, the system must include multiple optical surfaces or multiple optical elements (e.g., two or more than two). This is true for both conventional refractive optical systems and metasurface optical systems. Specifically, only optical systems with two or more metasurfaces and sufficiently low aberrations over a field of view are presented. Various embodiments are directed to imaging systems that integrate apertures with a single metasurface element, which allow the combined system to achieve high quality imaging over a large field of view, telecentricity over a large field of view (e.g., near 0 degrees of incidence at the image sensor plane) without attenuation of relative illumination.

[0085] Specifically, such systems can be used in imaging systems such as CMOS cameras (e.g., imaging systems used in cell phones, computers, tablet computers, etc., which are used to collect images of scenes in visible light or infrared for biometric verification). These CMOS imaging systems require an increased field of view (FOV), independent control of the chief ray angle (CRA) at the CMOS image sensor as a function of field height, and minimal optical distortion of the scene being imaged. These terms will be understood to have conventional meanings to those skilled in the art. For traditional imaging systems including refractive lenses, up to five or six unique lenses must be combined to perform this function. Similarly, conventional metasurface imaging systems implement multiple metasurface elements to provide sufficient degrees of freedom to adequately control these parameters (CRA, FOV, and minimize distortion). However, various embodiments show that by combining pores with a single metasurface, combining imaging systems with wide FOV, controllable distortion and controllable CRA can be achieved according to embodiments.

[0086] Figures 1 to 7 An exemplary embodiment of such a system is described in . As shown, in many such embodiments, the system (10a-10d) generally includes a pore structure (12a-12d) disposed at a set distance (13a-13d) from a metasurface layer (14a-14d), which itself is at a set distance (15a-15d) from an image sensor (16a-16d). As will be described in more detail below, in such systems, it should be understood that the distance between the pore and the metasurface layer and the distance between the metasurface layer and the imaging system (e.g., the back focal length of the imaging system) can take the form of an air gap or an optically transmissive material (e.g., a substrate, etc.).

[0087] For purposes of many embodiments, the pore structure (12a to 12d) includes: a first pore structure portion (18a to 18d) that is transmissive to light at a wavelength of interest; and a second pore structure portion (20a to 20d) that is at a distance (d ap) can be completely transmitted by light at the wavelength of interest. In various embodiments, such a pore structure does not impart an optical function (e.g., does not deflect light), but rather limits the lateral extent of the light beam entering the imaging system, or otherwise equivalently sets the entrance aperture of the imaging system.

[0088] For purposes of many embodiments, the metasurface layers (14a to 14e) generally include a substrate having a thickness (t sub ) on a substrate (24a to 24e) defined by the invention, which may be formed of any material that is transmissive to the wavelength of interest. In many embodiments of the hybrid pore / metasurface imaging system, the metasurface layer is the only functional layer provided that significantly deflects incident light to form a focused image (e.g., the metasurface layer serves as an arbitrary phase mask).

[0089] Embodiments of the nanostructures typically include identical or unique three-dimensional elements (e.g., square, circular, triangular, elliptical, etc.) having a characteristic size less than the wavelength of light within a specified operating bandwidth and configured to apply a phase shift to the impinging light in a plurality of planes separated by a macroscopic distance (a distance of 10 or more wavelengths), so that the metasurface layers perform a single optical function in combination. Each individual metasurface in an optical system can be configured to have a certain specific 2D phase and transmission function φ(x,y) and t(x,y) that it implements. Although in general, each metasurface can have a unique distribution of phase and transmission, the nanostructure elements that constitute any metasurface embedded in the same material, with the same basic composition and at a specific wavelength are the same. In most practical single wavelength applications, the transmittance can be configured to be maximized (close to 1) and uniform across the metasurface, while the phase can be configured to take a value between 0 and 2π. In general, according to embodiments, for a certain wavelength of interest, material system (metasurface material and embedded material), fixed thickness and element spacing, a set of in-plane dimensions of the constituent nanostructures can be configured such that a phase delay of 0 to 2π can be left on the incident light field. Thus, for different implementations of the metasurface design under fixed material and wavelength conditions, the only variable between designs is the distribution of the appropriate nanostructured elements across the metasurface.

[0090] According to some embodiments, the metasurface layer can be designed to be independent, that is, the metasurface element protrudes from the end of the substrate and is separated only by an air gap, and the process is completed at this step. In other embodiments, the metasurface can be further configured to have an AR coating or mechanical protection. In some such embodiments, in order to protect the metasurface and provide improved functionality, the metasurface constituent elements and the substrate surface can be coated with some materials or material layers. In an embodiment with an embedded metasurface element, an element of any material with desired optical properties can be embedded in a lower refractive index medium. The low refractive index medium completely encapsulates the metasurface and extends a certain thickness above the metasurface element. The low refractive index medium acts as a protective barrier for the metasurface element (i.e., provides mechanical stability) and provides additional design freedom for systems that allow optimization of certain properties (e.g., the total transmittance or efficiency of the metasurface).

[0091] The metasurface layer or metasurface system according to the embodiments can be manufactured in large quantities using any suitable manufacturing technology, including, for example, photolithography, machining, etching, and standard CMOS manufacturing technology, as previously described in U.S. Patent Application No. 16 / 120,174 filed on August 31, 2018, the disclosure of which is incorporated herein by reference. The metasurface substrate can be any low refractive index material, for example, a polymer, SiO2, glass. The metasurface element can also be any material that has been optimized for a specific bandwidth, for example, silicon, TiO2, alumina, metal, etc.

[0092] The imaging system may take the form of a single monolithic image sensor or pixel array. Such image sensors and pixel arrays may take any suitable form including, for example, CMOS sensors.

[0093] Figure 1 Schematic illustrations of implementations of various embodiments of such hybrid pore / metasurface imaging systems are provided. As shown, in many embodiments, a pore / metasurface that is transmissive to a wavelength of interest and has a thickness (t sub ) of a substrate layer (24a) having: a pore structure (12a) which is not transmissive to light at a wavelength of interest and at a certain distance (d ap ) is completely transmissive to the light at the wavelength of interest, disposed on a first side away from the imager (16a); and a metasurface layer (14a) composed of nanostructures (22a) having the same height, disposed on a second side close to the imager (16a). In such embodiments, the pore structure (12a) and the metasurface layer (14a) are separated by a substrate thickness (t sub) is defined by a first distance (13a). In addition, in such embodiments, the pore structure (12a) and the supersurface layer (14a) can be directly deposited on the substrate (24a) or bonded via an adhesive. A gap (t air ) formed by the back focal length (15a). Although not required, many embodiments of such imaging systems may further include an optional glass cover or filter (26) that does not affect the imaging performance of the device but provides other functionality (e.g., optical or structural).

[0094] It should be understood that in such embodiments, the apertures do not impart an optical function (do not deflect light), but rather merely limit the lateral extent of the light beam that can enter the imaging system, or equivalently set the entrance aperture or f / # of the system. At the same time, the metasurface layer may include the only functional optical layer that, in such embodiments, significantly deflects light to form a focused image. In some such embodiments, the metasurface layer may act as an arbitrary phase mask that imparts any value of 0 to 2π phase shift to incident light at any radial position of the lens.

[0095] refer to Figure 2 , provide the basis Figure 1A ray tracing diagram of an exemplary embodiment of a system including a single aperture (12a) and a single metasurface (14a) combined on a single substrate (24a) throughout the embodiment illustrated in FIG. (Although not described in detail herein, it should be understood that these metasurface elements may be fabricated using methods as described herein or in previously referenced U.S. Patent Application No. 16 / 120,174 using a suitable conformal deposition process such as low pressure chemical vapor deposition or atomic layer deposition.) In this exemplary embodiment, the aperture and metasurface elements have been configured such that they are combined to form a good image across a wide FOV (±40 degrees in this example, however, it should be understood that this is not a limiting condition). It has been unexpectedly discovered that embodiments of this single aperture and single metasurface system as shown naturally produce telecentric (i.e., having a 0 degree CRA) focused light rays at the image plane. Simply put, while conventional refractive and metasurface designs require complex, multi-element systems to achieve such telecentric designs, in accordance with an embodiment, only a single aperture and a single metasurface element are required to achieve similar telecentricity. This telecentricity, in turn, produces improved optical properties. Specifically, a low (e.g., zero or near-zero degree CRA) allows the bandwidth of the optical filter (26) to be narrowed for narrowband applications. In conventional refractive designs, the CRA is typically about 15 to 30 degrees, especially for compact mobile applications. These larger CRAs, in turn, require a significant increase in the filter bandwidth, thereby allowing more ambient light to enter the detector. In narrowband applications (e.g., near-IR VCSEL arrays), such ambient light can be a persistent source of noise. Thus, for example Figure 2 Embodiments of the combined metasurface / filter system shown in allow for better ambient light performance.

[0096] although Figure 1 and 2 One arrangement of optical elements is provided for a hybrid pore / metasurface imaging system, but it should be understood that many other arrangements of elements may be implemented. For example, Figure 3 A schematic illustration of an embodiment of an imaging system is provided in which the positions of the air gap and the substrate have been replaced. This structure allows for a thinner imaging system but requires a more complex assembly process. Specifically, as Figure 3 As shown in FIG. 1 , such an imaging system embodiment includes a substrate (24b) that is transmissive to the wavelength of interest and has a provided thickness (t sub), the substrate having a metasurface layer (14b) composed of nanostructures (22b) having the same height disposed on a first side away from the imager (16b) and disposed on a second side close to the imager (16b). In such embodiments, the metasurface layer (14b) and the imager (16b) can be directly bonded via an adhesive or other suitable means. A substrate having a thickness (t sub ) formed by the back focal length (15b). This distance is used as a free parameter to design an imaging system with optimal performance and will vary based on, for example, the desired f / # or field of view of the imaging system. In such embodiments, such an imaging system does not need to be Figure 1 The optional glass cover or filter used as substrate (24b) in the embodiment shown in FIG. 2 provides such dual functionality. In such embodiments, light at the wavelength of interest is not transmitted and at a certain distance (d ap ) can be completely transmitted by the light at the wavelength of interest, and the super surface layer (14b) is separated by air gaps (t air ) defined by a first distance (13b).

[0097] refer to Figure 4 , provide the basis Figure 3 A ray tracing diagram of an exemplary embodiment of a system of the embodiment illustrated in , which system includes a single aperture (12b) together with a single metasurface (14b) and imager (16b) combined on a single substrate (24b). (Although not described in detail herein, it should be understood that these metasurface elements can be fabricated using methods as described herein or in previously referenced U.S. Patent Application No. 16 / 120,174, using a suitable conformal deposition process such as low pressure chemical vapor deposition or atomic layer deposition.) In this exemplary embodiment, the aperture and metasurface elements have been configured so that they are combined to form a good image across a wide FOV (±40 degrees in this example, however, it should be understood that this is not a limiting condition). It has been unexpectedly discovered that embodiments of this single aperture and single metasurface system as shown naturally produce telecentric (i.e., having a 0 degree CRA) focused light rays at the image plane.

[0098] although Figure 1 and 4 An arrangement of optical elements is provided for a hybrid pore / metasurface imaging system in which the elements are in direct contact with the image sensor, but it should be understood that many other arrangements of elements with spacers disposed between the image sensor and the substrate supporting the metasurface layer can be implemented. For example, Figure 5 A schematic illustration of an embodiment of an imaging system is provided in which a second air gap (28) is disposed within the imaging system.

[0099] Specifically, if Figure 5 As shown in FIG. 1 , such an imaging system embodiment includes a substrate (24c) that is transmissive to the wavelength of interest and has a provided thickness (t sub ), the substrate having a metasurface layer (14c) consisting of nanostructures (22c) of the same height disposed on a first side away from the imager (16c) and a second air gap (28) disposed between the metasurface layer and a second side close to the imager (16c). An advantage of such an embodiment with an air gap is that compared to, for example Figure 1 In the embodiment shown in FIG, light passes through the system at a higher angle, thus allowing the overall form factor of the metasurface optical system to be reduced. In addition, the gap between the metasurface substrate and the image sensor allows the introduction of other optical elements, including, for example, microlens arrays or optical color filters, to improve the optical function of the imaging system.

[0100] In such embodiments, the metasurface layer (14c) and the imager (16c) may be deposited directly on the substrate (24c) or bonded via an adhesive. Such embodiments may also include a suitable spacer (30) to support the substrate (24c) and maintain a distance between the substrate and the image sensor (16c). A distance (15c) is disposed between the metasurface layer (14c) and the imager (16c), the distance being defined by the substrate thickness (t sub ) and the spacer height (t spacer ) is formed by the combination of the back focal length. The spacer (30) can be fixed to the image sensor (16c) and the substrate layer (24c) so as to be (t spacer ) produces a fixed distance, or the substrate can be placed into a standard optical column, and (t spacer ) can be adjusted after assembly. Such embodiments allow the surface (34) of the substrate (24c) proximal to the image sensor (16c) to remain unpatterned, thereby allowing an optional optical filter to be integrated directly thereon.

[0101] Although one embodiment of a hybrid aperture / metasurface configuration with an air gap above the image sensor has been described, Figure 6 As shown in , in various embodiments, the metasurface layer (14d) may also be disposed on the surface of the substrate (24d) near the image sensor (16d), which faces the air gap (32) supported by the spacer (30'). This implementation allows the metasurface element to be protected from environmental contamination. In addition, such embodiments allow the surface (34') of the metasurface substrate (24d) away from the image sensor (16d) to remain unpatterned, never allowing the optional optical filter to be directly integrated on the substrate. Again, in such embodiments, the spacer (30') may be fixed to the image sensor (16d) and the substrate (24d), thereby (tspacer ) produces a fixed distance, or the substrate (24d) can be placed into a standard optical tube and (t spacer ) can be adjusted after assembly.

[0102] therefore, Figure 5 and 6 The embodiments illustrated in illustrate that the metasurface elements may be arranged to face inwardly or outwardly relative to the air gap between the substrate and the image sensor. Figure 5 and 6 The production of the metasurface system described in can follow the process described in, for example, U.S. Patent Application No. 16 / 120,174. The spacer layer can be any low refractive index material, for example, polymer, SiO2, glass.

[0103] although Figure 3 , 5 6 show embodiments of hybrid pore / metasurface imaging systems with air gaps between the pores and the metasurface substrate, but these embodiments will require a separate support structure to fix the pores and ensure the pore distance (t air ) remains constant. However, the porous structure (12e) can also be directly attached to the substrate layer (24e). Figure 7 An exemplary embodiment of such an imaging system is illustrated in FIG. As shown, in this exemplary embodiment, the top aperture (12e) has an aperture body (36) having a width d ap,top The pore body sets the entrance pore of the system and has a certain distance (t ap ) pores, and in the pores of (t ap ) is set by the width of the metasurface layer and by (d ap,bottom ) is given by the minimum angle set by the half field of view of the imaging system relative to the width of the aperture. Figure 7 The embodiment shown in depicts a system in which the metasurface layer (14e) is disposed on a surface of a substrate (24e) away from an image sensor (16e), but it should be understood that the metasurface layer may also be disposed on a surface (34″) of the substrate that is close to the image sensor. In addition, it should be understood that although the exemplary embodiment does not include a spacer structure (30″) and an air gap between the substrate (24e) and the image sensor (16e), the embodiment may omit this element and mount the substrate directly on top of the image sensor.

[0104] A property of embodiments of such telecentric designs is that the metasurface imaging system provides relatively uniform illumination (referred to as "relative illumination" by those skilled in the art) at the image sensor. Fig. 8AA data plot of relative illumination of an exemplary system according to an embodiment is provided, and the data plot shows that the relative illumination of the pore / metasurface imaging system is maintained at 100% across the entire field of view, which is a great improvement over conventional systems, which may have a difference between the center and the edge of 50% or more. Therefore, embodiments of the imaging system are able to collect more total illumination across the entire field of view. Embodiments of the metasurface system also provide additional design changes relative to traditional refractive lens systems. A typical CMOS image sensor (CIS) requires a microlens to be associated with each pixel. Because there is a large variation in the CRA across a given sensor plane inherent in a refractive optical system, the microlens array on the CIS also requires complex CRA specifications. However, in an embodiment of a metasurface system as described herein, the CRA of the microlens array can be configured to be a constant 0 degree across the CIS, thereby allowing the design and manufacture of the microlens array to be simpler. Alternatively, in certain embodiments, the microlens array can be completely removed from the CIS, thereby eliminating the process steps of CIS production. In addition, such a pore metasurface system with 0 CRA allows limiting the persistent problem of what is referred to as "pixel crosstalk" by those skilled in the art in traditional imaging systems. Traditional refractive systems that send light into image sensors tend to couple light into neighboring pixels, which adds noise to the system.

[0105] Conventional metasurface systems can be configured with multiple metasurface layers to control FOV and distortion. Compared to typical systems that include an equivalent number of refractive elements, the introduction of additional metasurface elements allows for the realization of separate arbitrary phase distributions, providing more degrees of freedom to control the path of light. In embodiments of current imaging systems using a single metasurface layer, it is not possible to simultaneously control CRA and correct grid distortion. Therefore, a certain amount of grid distortion is unavoidable. For example, Figure 8B Provides data plots based on Figure 1 The distortion of the embodiment shown in FIG. 1 varies with the field at the CMOS image sensor of the imaging system. Figure 8C For example Figure 1 The embodiment of the imaging system shown in shows a plot of the modulus transfer function over the field of view. Fig.8D Provides standard test images, with instructions based on Figures 8A to 8C The imaging system of the embodiment shown in FIG. 1 has grid distortion. As shown, at the edges of the field of view, the quality degrades. However, embodiments of the present invention show that all wavelengths of light are tightly bunched, indicating that the distortion can be simply corrected using known image processing software.

[0106] Embodiments of hybrid refractive and metasurface elements

[0107] Although embodiments incorporating pores and a single metasurface layer have been described, it should be understood that embodiments also relate to hybrid systems of metasurface elements incorporating refractive lens elements. Fig. 9 Schematic illustrations of implementations of various embodiments of such hybrid refractive lens / metasurface imaging systems are provided. In many embodiments, the hybrid imaging surface is composed of at least one of each of the following: a refractive lens having one or more curvature surfaces, and a metasurface layer on a substrate, wherein all elements constituting the metasurface have the same height. More generally, a hybrid optical system may include any number of refractive elements and multiple metasurface layers. In certain embodiments, having a metasurface element on a substrate layer as the final component before an image sensor provides a specific advantage in creating a so-called image space telecentric imaging system. In addition, the substrate on which the metasurface layer is formed may have a set of deposited filter layers. As described in the embodiment in which the filter is incorporated, the metasurface layer is closer to the object plane of the imaging system, and the near infrared filter is closer to the image sensor.

[0108] Fig. 9 Exemplary embodiments of hybrid refractive element / metasurface imaging systems are described in the accompanying drawings. In many embodiments, the system includes: at least one refractive optical device (38) disposed at a set distance from a substrate layer (40) that is transmissive to the wavelength of interest and has a thickness (t sub ), having a metasurface layer (42) composed of nanostructures (44) of equal height disposed on a first surface (45) thereof remote from an image sensor (46); and an optional optical filter (48) disposed on a second side (47) of the substrate close to the imager.

[0109] although Fig. 9 The embodiments shown in illustrate a hybrid system having a single refractive optic and a single metasurface layer, but it should be understood that the embodiments may also incorporate other arrangements of refractive optics. Fig. 10A and 10B A diagram illustrating such a metasurface / refractive hybrid system is provided in FIG. Fig. 10A A hybrid system comprising two refractive elements (50 and 51) and a metasurface layer (52) system is described, wherein the two refractive elements are convex-concave and concave-convex. Fig. 10B A hybrid system comprising three refractive elements (54, 55, 56) and a metasurface element (58) is described, wherein the three refractive elements are convex-concave, bi-convex, and concave-planar, respectively.

[0110] With respect to the refractive optical elements in the hybrid system described above, i.e., the elements before the metasurface layer, it should be understood that the surface curvature of these elements can take any positive, negative, or infinite value. Thus, although a specific arrangement of refractive elements is shown in the drawings, the refractive elements can take any suitable form and combination for a particular application, including, for example, plano-convex, convex-planar, bi-convex, bi-concave, plano-concave, or concave-planar.

[0111] Embodiments of implementing an image sensor wafer

[0112] Imaging systems known in the art are typically composed exclusively of conventional refractive lenses (glass or plastic materials with at least one curved surface). According to embodiments, a single metasurface layer is disposed in conjunction with one or more curved refractive lenses. Unexpectedly, it has been discovered that inclusion of a single metasurface layer renders the optical system telecentric. Specifically, in many such embodiments, inclusion of a metasurface element as the final element prior to the image plane renders the system telecentric.

[0113] Embodiments of the metasurface layer can be integrated with a CMOS image sensor (CIS) as a cover glass and filter, while the refractive optics can be assembled in a barrel, as is conventionally done in an optical imaging module. In certain embodiments, the glass on which the metasurface layer is fabricated, in addition to being a cover glass for the CIS, can also be pre-deposited with a dielectric layer and act as a near-infrared bandpass or longpass filter. Such embodiments provide a single component that functions in the optical imaging process and eliminates unwanted wavelengths from being incident on the image sensor.

[0114] Although the above embodiments focus on hybrid metasurface imaging systems with a single sensor element, e.g. Figures 1 to 10B , but the metasurface element can also be integrated with an image sensor wafer containing multiple image sensor dies. Fig.11A A diagram illustrating a schematic diagram of an image sensor wafer is shown in FIG. As shown, an embodiment may include an image sensor wafer (60) including a set of image sensor dies (62), although this is shown in a periodically spaced 2D array, it should be understood that the array need not be periodically spaced. Fig. 11B , each sensor die (62) in turn includes an image sensor active area (64). Although each image sensor may be identical, in many embodiments, the characteristics of each sensor may generally be unique. Because each imager making up the array may have unique properties, an array with metasurface elements that each have uniquely designed properties may also be advantageous.

[0115] It should be understood that only the active area (64) needs to be available for imaging. The area outside the image sensor active area (66) can be used to attach lenses or spacers. In addition, in various embodiments, the metasurface substrate can be offset from the image array by a spacer. Fig. 12A and 12B , respectively, illustrate an exemplary embodiment of a spacer wafer (70) comprising: a plurality of spacer openings adapted to be attached to a sensor wafer; and a spacer die (72) adapted to be attached to an image sensor or lens die. The design and thickness of the spacer layer will depend on the particular configuration, but in many embodiments, the thickness is configured to allow light from an illumination source to be sufficiently diffused before interacting with the image sensor. Again, the function of each metasurface element in the array may generally be unique and may be patterned on top of each individual image sensor in the array using any suitable technique, such as outlined in U.S. Patent Application No. 16 / 120,174. For example, a metasurface may be fabricated directly on each individual image sensor in the array, or a suitable dielectric spacer may be deposited on the image sensor, followed by integration of the metasurface on top of the combined dielectric layer and image sensor. In such embodiments, the metasurface may provide a specific radiation pattern for each image sensor, and the entire system (image sensor properties, geometric parameters, and metasurface-enabled radiation pattern) may be iteratively optimized for a specific set of performance parameters.

[0116] In various other embodiments, a dielectric material with a refractive index less than that of the material that the image sensors are made of can be deposited and planarized so that a single metasurface can be patterned on top of the dielectric material. This is in contrast to embodiments where each image sensor in the array has a unique metasurface patterned on its facets. Again, in such embodiments, the combined system can be optimized to achieve the desired performance. Finally, in all of the above embodiments, wafer-level optical processes can be used to achieve integration of the metasurface with the image sensor array. In such embodiments, the spacer layer can be air rather than a solid dielectric, Fig.13 and 14 A description of an exemplary embodiment of such an apparatus is shown in .

[0117] Specifically, Fig.13A schematic diagram of an embodiment comprising an image sensor die (74) and a lens die (76) separated by a spacer (78) is shown. In such embodiments, the spacer (78) controls the distance between the metasurface area (80) and the image sensor active area (82). The spacer in such embodiments can be attached to the image sensor die or image sensor wafer, and then the lens can be attached to the spacer. Alternatively, the spacer can first be attached to the lens, and then the sensor is attached to the spacer. In such embodiments, the spacer can be attached using an adhesive (e.g., a UV cured epoxy or a heat cured epoxy), solder, or fusion bonding.

[0118] Fig.14 An exemplary embodiment is described that does not include a spacer. In such an embodiment, the thickness of the lens die (84) determines the distance between the image sensor active area (86) and the metasurface area (88). The image sensor die (90) and the lens die (84) can be attached directly using adhesive, solder, fusion bonding, bump bonding, etc. Alternatively, the image sensor wafer and the lens wafer can be attached directly at the wafer level as previously described.

[0119] like Fig.15 As shown in FIG. 1 , in certain embodiments, the refractive lens (91) of the hybrid system may first be assembled in a lens barrel (92), as is already known in the art. The metasurface element (94) may then be combined with a CMOS image sensor element (96), as described above with respect to the above Fig.13 and 14 The two subassemblies are then assembled together to form the final system. In such embodiments, the refractive lens can be configured to be screwed into a housing (98) so that the distance (t) between the refractive element and the metasurface can be adjusted. gap ).

[0120] Embodiment Implementation

[0121] As is well known in the art, an image of a scene formed by a circular, radially symmetric lens or a system of circular, radially symmetric lenses will also be circular. Therefore, the geometry of the image formed is often referred to as the image circle of the lens. However, in modern photography, the medium that records the image (e.g., a CMOS image sensor) often has a rectangular shape. In camera design, the image circle of a lens is designed so that the diameter D of the image circle is image At least as large as the diagonal d of the image sensor. However, since the image sensor is rectangular, only a portion of the image circle falls on the image sensor. Therefore, most of the lens area onto which light from the scene is incident is not used in the final formation of the image from the camera system.

[0122] In conventional injection molded plastic refractive lenses, the shape of the lens remains perfectly circular. A circular shape is used because from a manufacturing perspective, circular shapes and radially symmetrical lenses are the easiest to implement and the most repeatable in production. In addition, the cost increase is minimal to manufacture a circular lens with a larger area rather than a rectangular lens with a smaller area. Therefore, conventional cameras use circular lenses, and only a portion of the light that impinges on the entire circular lens is collected by the rectangular image sensor. Those portions of the circular lens where light is incident but does not contribute to light falling on the image sensor are not used in the final image formation.

[0123] For metasurface lenses according to various embodiments, the shape of the lens can be engineered so that the image it forms uniquely matches a specific image sensor size. Compared to conventional refractive lenses, in many such embodiments, the lens shape is configured to no longer be circular and the lens is configured to no longer form an image circle. In various embodiments, the metasurface lens is formed in a rectangular configuration with specific dimensions, and therefore the scene image formed is also rectangular. In the ideal case of this design embodiment, all light impinging on the rectangular metasurface lens falls on the image sensor. The embodiment of the metasurface with a rectangular lens breaks the radial symmetry, and therefore the image formed by the lens is no longer circular or radially symmetric.

[0124] Thus, in many embodiments of lens systems, metasurface lens elements can be formed in a rectangular configuration. Advantages of such rectangular or non-circular lenses include limiting the total area of ​​the lens, eliminating portions of the lens that would otherwise be illuminated by light and subsequently not form an image on the image sensor, and simplifying post-processing of the lens wafer. Specific embodiments of rectangular metasurface lenses and imaging systems are described herein.

[0125] Many embodiments of metasurface lens systems with non-circular configurations have the following in common: an entrance aperture that serves as a stop for the lens system, and a metasurface lens that serves as the final active optical surface before the image sensor plane. In such embodiments, the cross-section of the entrance aperture (and stop) can be circular, as in conventional optical systems, while the metasurface lens can be patterned into a rectangular or other arbitrary shape.

[0126] Fig.16An illustration of an exemplary embodiment of a light-clearing aperture metasurface is provided, wherein an imaging system (100) includes: a rectangular image sensor (102) that is offset from a single rectangular metasurface (104); and a circular entrance aperture (106) that is offset from a rectangular metasurface lens (104). In embodiments implementing a hybrid metasurface refractive system, the optical system includes an entrance aperture, at least one refractive lens, and a metasurface lens, wherein the metasurface lens is the last optical lens element in the system before the image sensor. In these embodiments of such hybrid systems, the entrance aperture and at least one refractive lens may still have circular or radially symmetric cross-sections. Thus, embodiments of such hybrid systems would include a circular aperture (106) offset from at least one circular refractive lens (not shown), which is then offset from a rectangular metasurface lens (104), such as Fig.16 . Again, in such embodiments, the metasurface lens has rectangular dimensions configured to match a particular image sensor. Although the examples herein describe implementations in which only the metasurface lens elements have rectangular cross-sections, this need not be limiting. For example, the entrance aperture (and the stop of the optical system) may also be rectangular or at least one of the refractive lenses may also be rectangular, as long as at least the metasurface lens element that is the last lens element before the image sensor has a rectangular cross-section.

[0127] In some cases, the size of the rectangular lens in the system can be completely characterized by the size of the image sensor and the specifications of the lens in the system. Fig.17A As shown in , the image sensor is characterized by its vertical dimension v and horizontal dimension h, respectively. A lens system is most commonly characterized by the f-number N of the lens, which is defined as N=f / D, where f is the focal length of the optical system and D is the diameter of the lens. Thus, Fig. 17B As shown in , the desired rectangular metalens width can be shown as w=v+f / N, and the length can be shown as l=h+f / N. Such a definition of the lens size will produce an image that fills the sensor geometry almost perfectly. In practice, the image formed by the imaging system needs to be slightly larger than the image sensor size. This oversizing of the image allows for greater tolerances in the final assembly of the lens system. A typical oversizing range may take the nominal rectangular lens size as given above, and increase each dimension by 40 microns.

[0128] Although the above example specifies a single circular aperture coupled to a rectangular lens, in other embodiments, an optical system having N number of apertures on N number of rectangular lenses on a single image sensor may also be provided. For example, the circular apertures and rectangular metasurface lenses may be arranged in a 2×2 grid on a single image sensor. Figures 18A to 18B An example of this system is shown in . Fig.18AA single image sensor die (110) is shown, and a single spacer (112) may be Fig.18B The spacer is shown placed around the single image sensor die. Fig. 18C The distance between the rectangular hypersurface (114) and the image sensor (110) shown in FIG. 1A . The final element in the assembly contains a set of circular apertures (116) disposed in association with an additional spacer layer (118) to set the distance between the rectangular hypersurface and the circular apertures. Fig.18D A cross-sectional view of the entire assembly is shown in FIG.

[0129] although FIG. 18A to FIG. 18D An example of a 2×2 array of circular apertures on a rectangular metasurface is provided, but in general, the grid of circular apertures and rectangular metasurface lenses can be arranged in any manner (symmetrical or asymmetrical, e.g., 3×3 or 5×2). In addition, each individual rectangular metasurface and circular aperture that makes up the system has a unique size relative to other aperture metasurface pairs in the system. For example, each aperture diameter in the array may generally be unique, or each rectangular lens may be unique. However, the distance between the metasurface lens and the image sensor and between the metasurface lens and the circular aperture is generally fixed for the entire system. Changing the mechanical parameters of each individual component of the array, such as aperture size, allows the optical properties of each camera in the array to be unique. For example, each sub-camera may have a unique f / #, field of view, resolution, etc., according to an embodiment.

[0130] Principle of Equivalence

[0131] Therefore, although the present invention has been described in certain specific aspects, many additional modifications and variations will be apparent to those skilled in the art. Therefore, it should be understood that the present invention may be implemented in a manner other than that specifically described. Therefore, the embodiments of the present invention should be considered in all aspects to be illustrative rather than restrictive.

Claims

1. An imaging system, comprising: at least one image sensor; a substrate layer having a substrate thickness disposed at a first distance above the at least one image sensor, the substrate layer being configured to be transmissive to a target wavelength of light, the substrate layer having a first surface distal from the at least one image sensor and a second surface proximate to the at least one image sensor; an aperture disposed on the first surface of the substrate and having an aperture opening disposed therein; a spacer layer that creates an air gap between the second surface of the substrate layer and the at least one image sensor; and a metasurface comprising a single layer of a plurality of identical or unique nanostructured elements disposed on the second surface such that light impinging on the aperture openings passes through at least a portion of the metasurface such that a specified angular deflection is imparted thereby; wherein the pores are separated from the metasurface by a second distance determined by the thickness of the substrate; wherein the apertures and the metasurface are configured to collect light having a specified operating bandwidth across a specified field of view and to shift incident light so that it is focused on the at least one image sensor at a chief ray angle of zero or near zero degrees; and Wherein the at least one image sensor and the metasurface have a rectangular geometry.

2. The imaging system of claim 1, further comprising a glass cover disposed atop the at least one image sensor.

3. The imaging system of claim 1, wherein the first distance is determined by a spacer layer comprising one of a solid spacer material or an air gap.

4. The imaging system of claim 1, wherein the field of view is at least ±30 degrees.

5. The imaging system of claim 1, further comprising a narrow bandwidth optical filter disposed between the metasurface element and the at least one image sensor.

6. An imaging system comprising: at least one image sensor; a substrate layer having a substrate thickness, the substrate layer being configured to be transmissive to a target wavelength of light, the substrate layer having a first surface distal from the at least one image sensor and a second surface proximate to the at least one image sensor; an aperture disposed above the substrate and having an aperture opening disposed therein; a spacer layer that creates an air gap between the second surface of the substrate layer and the at least one image sensor; and a metasurface comprising a monolayer of a plurality of identical or unique nanostructured elements disposed on one of the first surface or the second surface such that light impinging on the aperture openings passes through at least a portion of the metasurface such that a specified angular deflection is imparted thereby; wherein the pores are separated from the metasurface by a first distance; wherein the apertures and the metasurface are configured to collect light having a specified operating bandwidth across a specified field of view and to shift incident light so that it is focused on the at least one image sensor at a chief ray angle of zero or near zero degrees; and Wherein the at least one image sensor and the metasurface have a rectangular geometry.

7. The imaging system of claim 6, wherein the metasurface is disposed on the first surface.

8. The imaging system of claim 7, further comprising a narrow bandwidth optical filter disposed on the second surface between the metasurface and the at least one image sensor.

9. The imaging system of claim 7, wherein at least a portion of the aperture is interconnected with the first surface.

10. The imaging system of claim 6, wherein the metasurface is disposed on the second surface.

11. The imaging system of claim 6, wherein the image sensor is in contact with the second surface.

12. The imaging system of claim 6, wherein the field of view is at least ±30 degrees.

13. An imaging system comprising: at least one image sensor; a substrate layer having a substrate thickness, the substrate layer being configured to be transmissive to a target wavelength of light, the substrate layer having a first surface distal from the at least one image sensor and a second surface proximate to the at least one image sensor; at least one refractive lens disposed above the substrate and configured to focus illumination light on the first surface of the substrate layer; a spacer layer that creates an air gap between the second surface of the substrate layer and the at least one image sensor; and a metasurface comprising a single layer of a plurality of identical or unique nanostructured elements disposed on one of the first surface or the second surface such that light impinging on the at least one refractive lens passes through at least a portion of the metasurface elements such that an angular deflection is imparted thereby; wherein the at least one refractive lens is separated from the metasurface by a first distance; wherein the refractive lens and the metasurface are configured to collect light having a specified operating bandwidth across a specified field of view and to shift incident light so that it is focused on the at least one image sensor at a chief ray angle of zero or near zero degrees; and Wherein the at least one image sensor and the metasurface have a rectangular geometry.

14. The imaging system of claim 13, wherein the metasurface is disposed on the first surface.

15. The imaging system of claim 14, further comprising a narrow bandwidth optical filter disposed on the second surface between the metasurface element and the at least one image sensor.

16. The imaging system of claim 13, wherein at least a portion of at least one of the refractive lenses is interconnected with the first surface.

17. The imaging system of claim 13, wherein the metasurface is disposed on the second surface.

18. The imaging system of claim 14, wherein the image sensor is in contact with the second surface.

19. The imaging system of claim 13, wherein the field of view is at least ±30 degrees.

20. The imaging system of claim 13, wherein the at least one refractive lens is selected from the group consisting of: plano-convex, convex-plan, bi-convex, bi-concave, plano-concave, or concave-plan.

21. The imaging system of claim 13, comprising at least two refractive lenses, the at least two refractive lenses comprising a convex-concave lens and a meniscus lens.

22. The imaging system of claim 13, comprising at least two refractive lenses, the at least two refractive lenses comprising a convex-concave lens, a bi-convex lens, and a concave-planar lens.

23. The imaging system of claim 13, wherein the at least one refractive lens proximate the metasurface has a circular geometry.

24. The imaging system of claim 13, wherein the image sensor is characterized by a vertical dimension v and a horizontal dimension h, and wherein the at least one refractive lens is characterized by an f-number N of the lens, wherein N is defined as N=F / d, where f is the focal length of the optical system and D is the diameter of the lens, and wherein the metalens width is given by: w=v+f / N, and where the metalens length l is given by: l=h+f / N.

Images