Patent Application
20230384481
The present disclosure relates generally to optical lenses and, more specifically, to single nanostructure-integrated metalens configurations.
Various forms of optical sensors, such as for use in imaging, ranging, depth detection, etc., have entered into relatively widespread use. For example, optical sensors using a semiconductor-based sensor array (e.g., image detector array, photodetector array, image capture array, etc.) have been increasingly used in mobile devices. Mobile devices, such as smartphones, tablet devices, notebook computers, and even smartwatches, often include semiconductor-based optical sensor devices in the form of one or more cameras. Additionally, such mobile devices often include some form of semiconductor-based optical sensor device for light detection and ranging (e.g., using light detection and ranging (LiDAR) for face scanning and/or other depth mapping tasks).
For some applications, semiconductor-based optical sensor devices designed for imaging by detecting light of the infrared (IR) spectrum are utilized. Semiconductor-based optical sensor devices used for IR imaging applications generally include sensor array(s) configured to detect light within one or more IR sub-spectrum. Semiconductor-based optical sensor devices that support imaging within only a single IR sub-spectrum are most common because sensor arrays configured for detection of wavelengths spanning no more than one IR sub-spectrum are less complex to design and fabricate than sensor arrays configured for detection of wavelengths spanning multiple IR sub-spectrums. Examples of IR imaging applications include: thermal cameras, which typically utilize devices for imaging within at least the long-wave IR (LWIR) sub-spectrum (i.e., wavelengths of approximately 8 μm-14 μm); gas analysis systems, which typically utilize devices for imaging within at least the mid-wave IR (MWIR) sub-spectrum (i.e., wavelengths of approximately 3 μm-5 μm); and security imaging systems as well as 3D sensing systems, which typically utilize devices for imaging within at least the near IR (NIR) sub-spectrum (i.e., wavelengths of approximately 780 nm-2500 nm).
A goal in the implementation of semiconductor-based optical sensor devices for imaging in any spectrum is often miniaturization, particularly when the implementation is with respect to devices intended for handheld use which are designed for portability. It is difficult, however, to reduce the thickness of optical sensor devices. For example, optical lenses for light focusing are traditionally included in optical sensor devices used for imaging applications, wherein the optical lens is used to focus incident light onto the optical sensor device. In such systems, the curvature of the lens controls the optical performance of the optical sensor device. The refractive power of the lens decreases as the radius of curvature of the lens increases and, correspondingly, the refractive power of the lens increases as the radius of curvature decreases. This is because the thickness of the lens in an optical axis direction increases as the radius of curvature decreases. Miniaturization of an optical sensor device utilizing such a lens is, thus, subject to the thickness of the lens for providing the necessary optical performance.
In recent years, diffractive optical elements (DOEs), in which micro structured surface relief patterns cause light diffraction, have begun to be adopted for use with respect to optical sensor devices (e.g., for providing light focusing with respect to optical sensor devices). A DOE is comprised of a thin plate having micro-optic diffractive structures disposed in a predetermined mapping thereon configured to impose a certain spatial pattern of optical phase changes on an incident light beam. The micro-optic diffractive structures of a DOE modify the phase of incident light with the height of the structures (e.g., the thicker the material is forming a micro-optic diffractive structure, the larger the phase rotation provided by that micro-optic diffractive structure). This aspect of DOE implementations results in high costs (e.g., requires multiple fabrication steps to achieve the different structure heights) to achieve higher phase levels.
Metalens configurations, in which metasurfaces modulate the behaviors of electromagnetic waves and increase the effective optical path by the optical resonance of the nanostructures, have begun to receive attention for use as light focusing devices with respect to optical sensor devices used for imaging applications. Such optical sensor devices configured for light detection from within one or more IR sub-spectrum often include sensor arrays capable of detecting not just one wavelength of light from within the supported sub-spectrum, but a plurality of wavelengths from within the supported sub-spectrum. Therefore, in order to support the capabilities of the sensor arrays of an optical sensor device as fully as possible, metalens configurations are often utilized to focus a range of wavelengths of light as opposed to just a single wavelength of light. However, generally, the light focusing quality of a single metalens is poorer the further displaced a wavelength to be focused is from a center wavelength for which the metalens is designed. As a method for widening the range of wavelengths for which an optical sensor device may provide higher quality focusing support, existing metalens configurations often include a plurality of lenses, either a series of metalenses or a mixture of metalenses and conventional lenses. However, the use of more than one lens increases the overall thickness of the optical sensor device and presents a limitation on miniaturization. Further, even to the extent that existing metalens configurations including a plurality of lenses support light focusing for more than one wavelength of light, the range of supported wavelengths is typically of relatively narrowband (e.g., a range of 1 μm or less) because designing support for wider band wavelength ranges into a metalens configuration generally increases the design and fabrication complexity for the configuration substantially. Additionally, metalens configurations considered for light focusing in imaging applications have typically provided configurations in which the nanostructures are easily damaged, such as through their being exposed externally to the lens system.
An example of a metalens configuration proposed for imaging is described in United States patent publication US20220082731. In metalens embodiments of US20220082731, more than one metalens is used to focus light onto an image sensor, limiting the extent of miniaturization possible for the embodiment. Further, some metalens configurations of US20220082731 provide for the nanostructures to be included on the outward facing side of the metalenses, decreasing the durability of the resulting metalenses in the configuration.
International patent publication WO2022051971 also describes an example of a metalens configuration proposed for imaging. In metalens embodiments of WO2022051971, conventional lenses are used in addition to at least one metalens to focus light, limiting the extent of miniaturization possible for the embodiment. Further, the metalens embodiments of WO2022051971 support light focusing for no more than approximately a 1 μm band of wavelengths.
The present invention is directed to systems and methods which provide single nanostructure-integrated metalens configurations. In accordance with embodiments of the invention, a single metalens provides light focusing functionality, such as for infrared (IR) wavelengths. For example, a single metalens of some examples may be configured to provide light focusing functionality for a plurality of wavelengths within the IR spectrum.
A single nanostructure-integrated metalens configuration of embodiments comprises an optical substrate having a preconfigured mapping of integrated nanostructures providing metasurfaces for modulating the behaviors of electromagnetic waves to implement a thin, flat lens. In accordance with some examples, single nanostructure-integrated metalens configurations may provide a range of supported focal distances and relatively wide fields of view. Implementations of a single nanostructure-integrated metalens of embodiments of the invention are well suited for use in various optical sensor devices. For example, a single nanostructure-integrated metalens according to concepts herein may be utilized within a thermal imaging sensor, as a device for focusing wavelengths of light from within the long-wave IR (LWIR) sub-spectrum onto a sensor array included within the thermal imaging sensor. A single nanostructure-integrated metalens configuration for light focusing according to concepts herein may provide for greater levels miniaturization than that of existing light focusing lens configurations, making such metalens configuration a desirable focusing solution for handheld thermal imaging sensors for which portability is a concern. According to embodiments, a single nanostructure-integrated metalens configuration may be utilized to focus light comprising a single IR wavelength, a narrowband range of IR wavelengths (e.g., 1 μm or less), or a wideband range of IR wavelengths (e.g., a range of up to 6 μm), allowing the single nanostructure-integrated metalens to support the detection range of an sensor array included within a thermal imaging sensor as fully as possible. Further, wideband ranges of IR wavelengths or narrowband ranges of IR wavelengths focused by a single nanostructure-integrated metalens of embodiments herein may span no more than a single IR sub-spectrum or may span multiple IR sub-spectrums. Additionally, a single nanostructure-integrated metalens for light focusing according to concepts herein may provide focusing for incident light within a wide field of view, allowing the single nanostructure-integrated metalens to support imaging a greater expanse of on an object plane by just a single thermal imaging sensor.
Various corporeal aspects with respect to the nanostructure for a single nanostructure-integrated metalens configuration may be selected. For example, a form of nanostructure (e.g., one or more forms of nanostructures, such as nano cube, nano cuboid, nano cylinder, nano elliptic cylinder, etc.) may be selected for use with respect to a particular single nanostructure-integrated metalens. Additionally or alternatively, a period distance for the nanostructures (e.g., a center distance with respect to adjacent nanostructures such that adjacent nanostructures are spaced according to the period distance), a height of the nanostructures, and a lateral size of the nanostructures may be selected for a particular single nanostructure-integrated metalens configuration. In accordance with some examples, the period distance may be selected based at least in part on the center wavelength of the single nanostructure-integrated metalens. The period distance for the nanostructures may additionally be selected according to some examples based upon considerations such as the flexibility of the phase design, the field of vision, the fabrication difficulty, etc. The height of the nanostructures may be selected based at least in part on the center wavelength of the single nanostructure-integrated metalens, wherein all nanostructures of a single nanostructure-integrated metalens implementation have a same height according to some embodiments. Lateral size of the nanostructures of embodiments may be selected as a plurality of quantized lateral sizes for the nanostructures (e.g., 2, 4, 6, 8, 12, 16, etc. different lateral sizes, corresponding to the number of phase levels to be implemented), wherein the period distance for the nanostructures of some examples provides an upper boundary on the lateral size of the nanostructures. Uniformity of period distance, nanostructure height, and nanostructure form, as well as quantization of nanostructure lateral size are all factors that contribute to reduction of fabrication complexity for a single nanostructure-integrated metalens.
A configuration of nanostructures on a single nanostructure-integrated metalens may be determined according to a phase distribution of a preconfigured mapping designed so as to satisfy phase maps configured for focusing wavelengths of light. The preconfigured mapping may satisfy a single phase map or a plurality of phase maps. Phase maps for light focusing may be determined using empirical methods, numerical calculations, or a combination thereof. For example, determining phase maps using empirical methods may include designing and fabricating a single nanostructure-integrated metalens having a first configuration of nanostructures, measuring the phase distribution of the first configuration of nanostructures, adjusting the design based on the phase distribution of the first configuration, fabricating a single nanostructure-integrated metalens having a second configuration of nanostructures based on the adjusted design, and continuing this process until reaching a desired phase distribution. Additionally, examples of numerical calculations for determining phase maps for light focusing include but are not limited to binary diffractive phase functions (e.g., Binary2 lens phase function).
Single nanostructure-integrated metalens configurations of embodiments may be implemented in a variety of optical sensor devices. According to some examples, an imaging implementation may comprise an apparatus having a single nanostructure-integrated metalens for the focusing of light having wavelengths within the IR spectrum. The phase distribution of the single nanostructure-integrated metalens may satisfy a plurality of light focusing phase maps corresponding to a plurality of design wavelengths from within the IR spectrum. According to some embodiments, the design wavelengths may be from within a range restricted to a single IR sub-spectrum or may span multiple IR sub-spectrums. Because the phase distribution of the single nanostructure-integrated metalens may satisfy light focusing phase maps for a plurality of wavelengths, embodiments may support higher quality light focusing over wideband IR wavelength ranges while utilizing no additional optical elements (e.g., additional metalens (es), traditional lens(es), collimator(s), concentrator(s), mirror(s), etc.) in association with the single nanostructure-integrated metalens, facilitating a short total track length with respect to the apparatus and a lower number and cost of components in the apparatus. The apparatus may, for example, comprise a sensor array having a matrix of pixels configured to detect light from within a wavelength range encompassing the plurality of wavelengths corresponding to the plurality of light focusing phase maps satisfied by the phase distribution of the single nanostructure-integrated metalens (e.g., a 1-inch CMOS sensor). A barrel or other lens support structure may be included in the apparatus to hold the single nanostructure-integrated metalens at a desired, predetermined distance from the sensor array from within a range of focal distances corresponding to the plurality of light focusing phase maps satisfied by the phase distribution of the single nanostructure-integrated metalens. The single nanostructure-integrated metalens of the apparatus of embodiments is configured with nanostructures integrated on an optical substrate to focus light incident on the single nanostructure-integrated metalens onto the sensor array, wherein at least one side of the optical substrate deposited with nanostructures faces towards the inner side of the apparatus. Nanostructures of embodiments of a single nanostructure-integrated metalens may thus be disposed inside the apparatus, such as for providing protection with respect to the nanostructures. The single nanostructure-integrated metalens of embodiments may be configured with nanostructures integrated on the optical substrate so as to focus light incident on the optical substrate within a wide field of view (“FOV”) (e.g., 10°≤FOV≤90°). Additionally, the optical substrate may include a bandpass filtering layer for attenuating light having wavelengths outside the range spanning the plurality of wavelengths corresponding to the plurality of light focusing phase maps satisfied by the phase distribution of the single nanostructure-integrated metalens.
The foregoing has outlined rather broadly the features and technical advantages of the present disclosure in order that the detailed description that follows may be better understood. Additional features and advantages will be described hereinafter which form the subject of the claims herein. It should be appreciated by those skilled in the art that the conception and specific embodiments disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present designs. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope as set forth in the appended claims. The novel features which are believed to be characteristic of the designs disclosed herein, both as to the organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure.
For a more complete understanding of the present disclosure, reference is now made to the following descriptions taken in conjunction with the accompanying drawing, in which:
Support structure 130 provides structural support to hold single nanostructure-integrated metalens 110 in a desired predetermined relationship with an image detection plane of sensor array 120. A distance at which a single nanostructure-integrated metalens is held from an image detection plane of a sensor array may correspond to a focal distance (i.e., a distance at which light incident on a single nanostructure-integrated metalens having a particular wavelength is focused in the image plane) of single nanostructure-integrated metalens 110. For example, in some embodiments, single nanostructure-integrated metalens 110 may be configured to focus a single design wavelength of light (e.g., a center wavelength λc of single nanostructure-integrated metalens 110) such that there is a single focal distance for which single nanostructure-integrated metalens 110 focuses light having the single design wavelength most effectively. Support structure 130 of embodiments of single nanostructure-integrated metalens 110 may be configured to position the lens plane of single nanostructure-integrated metalens 110 the focal distance associated with the single design wavelength from the image detection plane of sensor array 120 so as to focus light having the single design wavelength onto the image detection plane of sensor array 120. In other embodiments, single nanostructure-integrated metalens 110 may be configured to focus a plurality of design wavelengths λn, each design wavelength associated with a design focal distance f n, such that single nanostructure-integrated metalens 110 may feature a range of focal distances, spanning between the smallest fn and the largest fn, for which single nanostructure-integrated metalens 110 is effective at focusing light. Embodiments of single nanostructure-integrated metalens 110 supporting focusing functionality for a plurality of design wavelengths λn may also feature a center wavelength λc and in such embodiments λc may correspond to the centermost wavelength of the range of wavelengths spanning between the smallest wavelength and the largest wavelength of the plurality of design wavelengths λn. Further, some embodiments of single nanostructure-integrated metalens 110 provide for selection of design wavelengths λn such that design focal distances fn are near in value to a center focal distance fc corresponding to center wavelength λc (e.g., the plurality of fn satisfy the relation 0.95≤fn/fc≤1.05). Additionally, support structure 130 of embodiments of single nanostructure-integrated metalens 110 may be configured to position the lens plane of single nanostructure-integrated metalens 110 a distance from within the range of focal distances from the image detection plane of sensor array 120 so as to focus light having wavelengths from within the range spanning the plurality of design wavelengths onto the image detection plane of sensor array 120.
Embodiments of support structure 130 may comprise a barrel (e.g., circular cylinder or ellipsoid cylinder wall open at both ends), a box (e.g., square or rectangular walls open at both ends), or other configuration providing mechanical means having a lumen allowing adequate light passage and configured to support single nanostructure-integrated metalens 110 in juxtaposition with sensor array 120. In accordance with some examples, support structure 130 is configured to engage an optical substrate of single nanostructure-integrated metalens 110 at a periphery of the optical substrate (e.g., around the circumference of the optical substrate, at an outer edge of a surface of the optical substrate immediately adjacent to the circumference of the optical substrate, etc.) selected so as to avoid damage of metastructures integrated on the surface of the optical substrate facing sensor array 120.
Sensor array 120 may comprise a matrix of pixels arranged in an image detection plane configured for imaging. The pixels of sensor array 120 may be configured to detect light having wavelengths from within a detection range of IR spectrum wavelengths (i.e., from approximately 780 nm to 14 μm), a detection range of visual spectrum wavelengths (i.e., from approximately 400 nm to 700 nm), a detection range of ultraviolet (UV) spectrum wavelengths (i.e. from approximately 10 nm to 400 nm), or a combination thereof. For example, sensor array 120 may comprise 13.2 mm by 8.8 mm matrix of IR light detecting pixels integrated onto a semiconductor substrate (e.g., a 1-inch complementary metal-oxide semiconductor (CMOS) sensor). According to some embodiments, the detection range of sensor array 120 may encompass a center wavelength λc of single nanostructure-integrated metalens 110. In other embodiments, the detection range of sensor array 120 may encompass a plurality of design wavelengths λn, in addition to a center wavelength λc of single nanostructure-integrated metalens 110, for which single nanostructure-integrated metalens 110 is configured to provide light focusing functionality.
In some embodiments, the detection range of sensor array 120 may span no more than a single IR sub-spectrum. For example, sensor array 120 may be configured to detect only wavelengths from within the long-wave IR (LWIR) sub-spectrum (i.e., wavelengths of approximately 8 μm-14 μm), only wavelengths from within the mid-wave IR (MWIR) sub-spectrum (i.e., wavelengths of approximately 3 μm-5 μm), or only wavelengths from within the near IR (NIR) sub-spectrum (i.e., wavelengths of approximately 780 nm-2500 nm). In other embodiments, the detection range of sensor array 120 may span wavelengths from multiple IR sub-spectrums. For example, sensor array 120 may include both pixels configured to detect LWIR wavelengths as well as pixels configured to detect MWIR wavelengths integrated onto a single semiconductor substrate, pixels configured to detect both LWIR wavelengths as well as MWIR wavelengths, or a combination thereof. Although the foregoing example is described with regard to embodiments having sensor array 120 configured to detect LWIR and MWIR wavelengths, other embodiments may feature sensor arrays configured to detect MWIR and NIR wavelengths, LWIR and NIR wavelengths, or a combination of LWIR, MWIR and NIR wavelengths.
Single nanostructure-integrated metalens 110 of embodiments provides a thin, flat lens configuration adapted for light focusing functionality. More specifically, embodiments of single nanostructure-integrated metalens 110 may be configured to focus light having wavelengths from within a range of IR spectrum wavelengths, a range of visual spectrum wavelengths, a range of UV spectrum wavelengths, or a combination thereof. Further, embodiments of single nanostructure-integrated metalens 110 configured for focusing IR wavelengths may be utilized to focus light having wavelength(s) from within any of the IR sub-spectrums (e.g., wavelengths from within LWIR sub-spectrum, MWIR sub-spectrum, NIR sub-spectrum, or a combination thereof). Additionally, embodiments of single nanostructure-integrated metalens 110 configured for focusing IR wavelengths may be utilized to focus light comprising a single IR wavelength, a narrowband range of IR wavelengths (e.g., 1 μm or less), or a wideband range of IR wavelengths (e.g., a range of up to 6 μm). Moreover, wideband ranges of IR wavelengths or narrowband ranges of IR wavelengths focused using single nanostructure-integrated metalens 110 of embodiments herein may span a single IR sub-spectrum (e.g., configured to focus only wavelengths from within the LWIR sub-spectrum, wavelengths within the MWIR sub-spectrum, or wavelengths within the NIR sub-spectrum) or may span multiple IR sub-spectrums (e.g., configured to focus wavelengths from within the LWIR sub-spectrum as well as wavelengths from within the MWIR sub-spectrum and/or the NIR sub-spectrum).
According to embodiments, single nanostructure-integrated metalens 110 comprises an optical substrate (e.g., a transparent substrate with a transparent spectral range of at least 50 nm corresponding to the center wavelength of the operation wavelength of an associated light source, such as 50 nm or greater transparent spectral range centered at the center frequency of sensor array 120), such as may comprise optical glass, quartz, fused silica, plastic, chalcogenides, germanium (Ge), silicon (Si), zinc selenide (ZnSe), zinc sulfide (ZnS), etc. For example, in some embodiments, single nanostructure-integrated metalens 110 may be configured to focus light over the entire transparent spectral range of the optical substrate such that transparent spectral range of the optical substrate is centered at both the center wavelength of the operation wavelength region of single nanostructure-integrated metalens 110 and at the center wavelength of a device (e.g., sensor array 120) to be used with single nanostructure-integrated metalens 110. The optical substrate of single nanostructure-integrated metalens 110 of embodiments has a preconfigured mapping of integrated nanostructures (e.g., nano cubes, nano cuboids, nano cylinders, nano elliptic cylinders, etc. of different, quantized lateral sizes) integrated thereon. The nanostructures may be comprised of various materials, such as dielectric material (e.g., silicon (Si), silicon nitride (SiN), gallium nitride (GaN), titanium dioxide (TiO2), etc.), plasmonic metallic materials (e.g. materials including gold (Au), silver (Ag), platinum (Pt), and/or palladium (Pd)), and/or other materials providing optical properties for modulating the behaviors of electromagnetic waves. In accordance with embodiments of single nanostructure-integrated metalens 110, the optical substrate is oriented such that a surface of the optical substrate upon which nanostructures are disposed upon faces sensor array 120 (e.g., a surface of the optical substrate having integrated nanostructures is incarcerated within a lumen of support structure 130, providing protection to the nanostructures of that surface).
As should be appreciated from the illustration of
Operations of flow 200 may, for example, be performed by one or more processor-based systems operating under control of instruction sets (e.g., computer executed logic, such as software, firmware, etc.) configured to provide operation as described herein. Such processor-based systems may comprise one or more processors, such as a CORE or PENTIUM processor; requisite computer/processor readable memory, such as random access memory (RAM), read only memory (ROM), flash memory, disk memory, solid state disk (SSD) memory, optical memory, and/or the like; and input/output components, such as display, network interface card (NIC), keyboard, digital pointer, printer, and/or the like; coupled to a processor of the one or more processors via a data bus and operable to provide functionality as described herein.
Block 210 of flow 200 illustrated in
A period distance (P) utilized according to examples is a row-to-row and column-to-column (e.g., perpendicular first and second axes) center distance implemented with respect to adjacent ones of nanostructures 112, as illustrated in
A height (H) of the nanostructures, as illustrated in
A lateral size (S) of the nanostructures, as illustrated in
In accordance with embodiments, single nanostructure-integrated metalens 110 may provide light focusing functionality for a single wavelength of light or a plurality of wavelengths of light. Block 220 of flow 200 illustrated in
In operation according to block 221 of embodiments of the invention, light focusing phase map(s) with respect to particular design wavelength(s) for single nanostructure-integrated metalens 110 may be computed using numerical calculations such as a phase focusing design technique (e.g., diffractive phase function) according to some examples. For example, calculations for phase focusing light to a nanostructure layer of a single nanostructure-integrated lens may be binary diffractive designed, such as based on the Binary2 lens phase function Φ2=MΣi=1NAip2i using an optical design program (e.g., ZEMAX). In other embodiments, light focusing phase map(s) with respect to particular design wavelength(s) for single nanostructure-integrated metalens 110 may be computed using empirical methods. For example, computing phase maps using empirical methods may comprise designing and fabricating a single nanostructure-integrated metalens having a first configuration of nanostructures, measuring the phase distribution of the first configuration of nanostructures, adjusting the design based on the phase distribution of the first configuration, fabricating a single nanostructure-integrated metalens having a second configuration of nanostructures based on the adjusted design, and continuing this process until reaching a desired phase distribution. Additionally, computation of light focusing phase map(s) with respect to particular design wavelength(s) for single nanostructure-integrated metalens 110, in accordance with some embodiments, may utilize a combination of numerical calculations and empirical methods.
At block 222 of the illustrated embodiment, a preconfigured mapping of integrated nanostructures (i.e., hereinafter referred to as a “preconfigured mapping”) is determined for single nanostructure-integrated metalens 110 which provides a desired spatial pattern of optical phase changes (e.g., phase rotation or offset) with respect to light incident on single nanostructure-integrated metalens 110. In embodiments, the preconfigured mapping defines a configuration for the nanostructures of single nanostructure-integrated metalens 110 such that nanostructures at position(s) (x,y) on the optical substrate of single nanostructure-integrated metalens 110 satisfy the consolidated phase retardation requirements (i.e., Φ(x,y,λn) of the phase map(s) determined during block 221.
Embodiments of single nanostructure-integrated metalens 110 configured to provide light focusing functionality in accordance with a preconfigured mapping (e.g., the preconfigured mapping for single nanostructure-integrated metalens 110 determined during block 222) satisfying one or more phase map(s) (e.g., the one or more phase map(s) determined during block 221) corresponding to one or more design wavelength(s) (e.g., design wavelength(s) λ1 through λn of block 221) are not limited to focusing light having wavelength of the one more design wavelength(s). Instead, embodiments of single nanostructure-integrated metalens 110 provide light focusing functionality for a continuous range of wavelengths encompassing the one or more design wavelength(s) of single nanostructure-integrated metalens 110. However, effectiveness of light focusing functionality decreases as a function of wavelength the further removed a wavelength of light is from a design wavelength of single nanostructure-integrated metalens 110. Therefore, embodiments of single nanostructure-integrated metalens 110 having more tightly grouped design wavelength pluralities provide more effective light focusing over the wavelength range spanned by a plurality of design wavelengths than single nanostructure-integrated metalens 110 embodiments having more widely spaced design wavelength pluralities provide over the wavelength range spanned by a plurality. For example, a single nanostructure-integrated metalens 110 embodiment having three design wavelengths of 9.5 μm, 10 μm, and 10.5 μm (e.g., λ1=9.5 μm, λ2=10 μm, and λ3=10.5 μm) provides more effective light focusing over the wavelength range from 9.5 μm to 10.5 μm than a single nanostructure-integrated metalens 110 embodiment having three design wavelengths of 8 μm, 10 μm, and 12 μm (e.g., λ1=8 μm, λ2=10 μm, and λ3=12 μm) provides over the wavelength range from 8 μm to 12 μm. However, for the same reasons as explained above, single nanostructure-integrated metalens 110 embodiments also do not provide effective light focusing for wavelengths outside the wavelength range spanned by the plurality of design wavelengths of the embodiment (i.e., effective light focusing bandwidth). Therefore, single nanostructure-integrated metalens 110 embodiments having more widely spaced design wavelength pluralities provide wider effective light focusing bandwidths than are provided by single nanostructure-integrated metalens 110 embodiments have more tightly grouped design wavelength pluralities of the same number of design wavelengths. For example, a single nanostructure-integrated metalens 110 embodiment having three design wavelengths of 9.5 μm, 10 μm, and 10.5 μm (e.g., λ1=9.5 μm, λ2=10 μm, and λ3=10.5 μm) provides an effective light focusing bandwidth of 1 μm whereas a single nanostructure-integrated metalens 110 embodiment having three design wavelengths of 8 μm, 10 μm, and 12 μm (e.g., λ1=8 μm, λ2=10 μm, and λ3=12 μm) provides an effective light focusing bandwidth of 4 μm.
Accordingly, the number of design wavelengths of single nanostructure-integrated metalens 110 as well as the distribution of those design wavelengths may, for example, be selected according to some examples based upon considerations such as the desired or acceptable performance of single nanostructure-integrated metalens 110, ease or difficulty of fabrication of the single nanostructure-integrated metalens, etc. For example, embodiments having more widely spaced distributions have wider effective light focusing bandwidths but provide less effective light focusing over the light focusing band, whereas embodiments having more tightly grouped distributions have narrower effective light focusing bandwidths but provide more effective light focusing over the light focusing band. Additionally, embodiments featuring greater numbers of design wavelengths may provide wider effective light focusing bandwidths without sacrificing effectiveness of light focusing within the band but support for a greater number of design wavelengths comes with increased design and fabrication complexity and associated costs. Because the phase distribution of a preconfigured mapping of single nanostructure-integrated metalens 110 may satisfy light focusing phase maps for a plurality of design wavelengths, embodiments may support higher quality light focusing over wideband wavelength ranges (e.g., wideband IR wavelength ranges) while utilizing no additional optical elements (e.g., additional metalenses, traditional lenses, etc.) in association with single nanostructure-integrated metalens 110, facilitating a short total track length with respect to the apparatus and a lower number and cost of components in the apparatus.
The foregoing exemplary operation according to flow 200 provides for determining corporeal aspects and a preconfigured mapping with respect to nanostructures for providing an implementation of single nanostructure-integrated metalens 110 configured to provide light focusing functionality for light having one or more wavelength(s) in accordance with embodiments of the invention. The determined preconfigured mapping, which satisfies one more phase map(s) corresponding to one or more design wavelength(s), may, for example, be utilized in integrating nanostructures having the determined corporeal aspects upon an optical substrate to provide an embodiments of single nanostructure-integrated metalens 110 in accordance with concepts herein. For example, techniques such as photolithography, soft lithography, laser ablation, chemical self-assembly, roll-to-roll nanoimprinting, etc. may be utilized in integrating nanostructures providing phase distribution according to the predetermined mapping which satisfies the determined phase map(s) and having the determined corporeal aspects with an optical substrate to provide an instance of single nanostructure-integrated metalens 110. As a specific example for light focusing of a single wavelength having an NIR center wavelength (e.g., λc=940 nm), nanostructures comprised of silicon (e.g., n=3.71 for λc of 940 nm) may be integrated on an optical glass substrate according to a phase distribution of a single phase map determined with respect to the single design wavelength (e.g., λ1=λc=940 nm) and having a height of 490 nm (e.g., H=490 nm), a period distance of 500 nm (e.g., P=400 nm) maintained with respect to adjacent nanostructures, and implementing 8 quantized lateral sizes (e.g., S143 π/4, S2→π/2, S3→3π/4, S4→π, S5→5π/4, S6→3π/2, S7→7π/4, and S8→2π), for use as a single nanostructure-integrated metalens configuration to be utilized in an optical sensor device for IR imaging applications (e.g., 3D sensing systems, security imaging systems, gas analysis systems, thermal camera systems, etc.). Additionally, as a specific example for light focusing of a plurality of wavelengths having an LWIR center wavelength (e.g., λc=10 μm), nanostructures comprised of silicon (e.g., n=3.4 for λc of 10 μm) may be integrated on a silicon substrate according to a phase distribution which satisfies three phase maps each determined with respect one of three design wavelengths (e.g., λ1=9 μm, λ2==10 μm, λ1=11 μm) and having a height of 5 μm (e.g., H=5 μm), a period distance of 4 μm (e.g., P=4 μm) maintained with respect to adjacent nanostructures, and implementing 8 quantized lateral sizes (e.g., S1→π/4, S2→π/2, S3→3π/4, S4→π, S5→5π/4, S6→3π/2, S7→7π/4, and S8→2π), for use as a single nanostructure-integrated metalens configuration to be utilized in an optical sensor device for IR imaging applications (e.g., 3D sensing systems, security imaging systems, gas analysis systems, thermal camera systems, etc.).
In some embodiments, optical sensor device 500 may also include a bandpass filtering layer 550 deposited on the surface of single nanostructure-integrated metalens 110 oriented facing away from the image detection plane of sensor array 120. Bandpass filtering layer 550 may be configured to attenuate light having wavelengths k a such that k a comprises wavelengths outside the effective light focusing bandwidth of single nanostructure-integrated metalens 110 (e.g., λa≤(λmin*0.9) and λa≥(λmax*1.1) wherein λmin is the smallest wavelength of λn and λmax is the largest wavelength of λn). λa may include all wavelengths outside the effective light focusing bandwidth of single nanostructure-integrated metalens 110 or only a subset of wavelengths outside the effective light focusing bandwidth of single nanostructure-integrated metalens 110. Embodiments of optical sensor device 500 including a bandpass filtering layer 550 may be desirable in instances wherein the range of wavelengths for which sensor array 120 detects light (i.e., imaging bandwidth) encompasses wavelengths beyond the desired range of wavelengths to be imaged.
Some embodiments of optical sensor devices configured for light focusing functionality, such as optical sensor device 500 illustrated in
Further, some embodiments of optical sensor devices configured for light focusing functionality having more than one lens structure may include a support structure adjustable to alter the distance(s) separating the more than one lens structures. For example, an embodiment of an optical sensor device having two nanostructure-integrated metalenses may include a support structure holding the two nanostructure-integrated metalenses as well as a sensor array such that light passing through the support structure must pass through both nanostructure-integrated metalenses before reaching the image detection plane of the sensor array. In the above-described embodiment, the two metalenses may be separated by a first distance, the metalens nearer the sensor array may be separated from the sensor array by a second distance, and the support structure may be adjustable to alter the distance separating the two metalenses. Additionally, in some embodiments, one or more of the nanostructure-integrated metalenses included in an optical sensor device may feature nanostructures on both faces of the metalens(es).
Although embodiments herein are predominantly described with reference to IR imaging systems, one of ordinary skill in the art will readily appreciate that concepts described herein may be utilized in other implementations. For example, some single nanostructure-integrated metalens embodiments configured to focus light having wavelengths from within a range of visual spectrum wavelengths may be included in optical sensor devices used for visual spectrum optical applications (e.g., mobile device cameras, visual spectrum laser systems, visual telescope systems, spectroscopy analysis systems, etc.). As another example, some single nanostructure-integrated metalens embodiments configured to focus light having wavelengths from within a range of UV spectrum wavelengths may be included in optical sensor devices used for UV spectrum optical applications (e.g., UV spectrum camera systems, UV spectrum laser systems, UV telescope systems, spectroscopy analysis systems, etc.).
Additionally, although the present disclosure and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the design as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the present disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present disclosure. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.
Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification.
This application is a continuation-in-part of U.S. patent application Ser. No. 17/746,508, titled “SINGLE NANOSTRUCTURE-INTEGRATED METALENS,” filed May 17, 2022, the disclosure of which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 17746508 | May 2022 | US |
| Child | 18448619 | US |
