Optical filter device

Abstract

An optical filter device (8) for use with an image sensor (4), comprising at least one first filter element (10) including a plurality of first nanostructures (18) and at least one second filter element (12) including a plurality of second nanostructures (20). The plurality of first nanostructures (18) are configured such that at least one of the first filter elements (10) includes a first transmission wavelength, and the plurality of second nanostructures (20) are configured such that at least one of the second filter elements (12) includes a second transmission wavelength different from the first transmission wavelength.

Description

[Technical Field]

[0001] This disclosure relates to an optical filter device, an imaging system, and related methods. [Background technology]

[0002] Infrared cameras can have a wide range of applications. These applications, though not limited to them, may include the detection of atmospheric gases, including greenhouse gases such as carbon dioxide, methane, and nitrous oxide; the identification of ice and water; defects in plastic materials; cracks in vehicles, etc. However, an array of multiple filters may be required to distinguish selected image data from other image data and / or to improve the spectral resolution of the selected image data.

[0003] For example, Fabry-Perot resonator filter arrays can be used in the wavelength range of 1100 nm to 1600 nm. The manufacture of such filter arrays may involve numerous lithography steps, leading to increased manufacturing costs and / or time. Because these filter arrays are based on the constructive interference of light, they transmit multiples of the selected wavelength. For example, a Fabry-Perot resonator filter array configured to transmit light with a wavelength of approximately 1600 nm may also transmit light with wavelengths of 800 nm and 400 nm, which may be undesirable. Therefore, there is a need for improved infrared filter arrays.

[0004] This background serves solely as a context to help those skilled in the art better understand the following description. Therefore, none of the above descriptions should be construed as acknowledging that they are part of the state of the art or general knowledge. One or more aspects / embodiments of this disclosure may or may not address one or more of the issues in this background. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] U.S. Patent Application Publication No. 2005 / 233493 [Patent Document 2] U.S. Patent Application Publication No. 2006 / 266921 [Patent Document 3] U.S. Patent Application Publication No. 2016 / 142654 [Overview of the Initiative]

[0006] According to a first aspect of the present disclosure, an optical filter device for use with an image sensor is provided. The device includes at least one first filter element comprising a plurality of first nanostructures and at least one second filter element comprising a plurality of second nanostructures, wherein the plurality of first nanostructures are configured such that the at least one first filter element includes a first transmission wavelength, and the plurality of second nanostructures are configured such that the at least one second filter element includes a second transmission wavelength different from the first transmission wavelength.

[0007] By configuring multiple second nanostructures such that at least the second filter element includes a second transmission wavelength different from the first transmission wavelength, the device can, for example, enable the parallel acquisition of image data related to at least two different wavelengths using a single imaging sensor.

[0008] Multiple first nanostructures and multiple second nanostructures may enable the fabrication of at least one first filter element and at least one second filter element in a size or dimension corresponding to the size or dimension of a pixel of an image sensor, for example, in a substantially corresponding size or dimension.

[0009] Additionally or alternatively, detection of multiples of the transmission wavelength can be prevented by providing a plurality of first nanostructures on at least one first filter element and a plurality of second nanostructures on at least one second filter element. The at least one first filter element and the at least one second filter element may be configured to enable resonant coupling of surface plasmon polaritons (SPPs) on the surfaces of the respective first and second filter elements. Light or radiation incident on the at least one first and the at least one second filter element may result in extraordinary optical transmission (EOT).

[0010] The first and / or second transmission wavelengths may be between approximately 0.8 μm and approximately 7 μm. This may enable the detection of atmospheric gases such as greenhouse gases. Additionally or alternatively, this may enable the detection of water in soil, human skin, cracks or defects in materials such as plastics, and the differentiation of ice from water. In other words, the device may enable the detection of any material exhibiting an optical spectrum in the wavelength range of approximately 0.8 μm to approximately 7 μm.

[0011] At least one first filter element and at least one second filter element may be arranged to form an array of multiple filter elements. This may facilitate the use of the device in conjunction with an image sensor.

[0012] At least one or each of the at least one first element and at least one second filter element may include a metallic material layer. Multiple first nanostructures and multiple second nanostructures may be formed on the metallic material layer of at least one or each of the at least one first filter element and at least one second filter element. Alternatively, at least one or each of the at least one first filter element and at least one second filter element may include a glass material layer.

[0013] At least one or each of the at least one first element and at least one second filter element may include a dielectric material layer. The dielectric material layer may be located on the metal material layer of at least one or each of the at least one first filter element and at least one second filter element. Alternatively, the dielectric material layer may be located on the glass material layer of the at least one first filter element and at least one second filter element.

[0014] The metallic material layer may contain at least one of gold, silver, chromium, copper, and aluminum. The glass material layer may contain a chalcogenide glass material such as germanium-antimony-tellurium (GST). The dielectric material layer may contain an oxide material such as silicon dioxide and / or a silicon nitride material such as silicon nitride. The dielectric material layer can improve the transmission of at least one of at least one first filter element and at least one second filter element, or each of them.

[0015] At least one or each of the plurality of first and second nanostructures may include a plurality of pores, a plurality of slits, a plurality of grooves and / or a plurality of protrusions. The plurality of first and / or second nanostructures may be arranged in a periodic arrangement.

[0016] The first transmission wavelength may depend on the dimensions of each of the multiple first nanostructures and / or the periodicity of the multiple first nanostructures. The second transmission wavelength may depend on the dimensions of each of the multiple second nanostructures and / or the periodicity of the multiple second nanostructures. The dimensions of each of the multiple second nanostructures and / or the periodicity of the multiple second nanostructures may differ from the dimensions of each of the multiple first nanostructures and / or the periodicity of the multiple first nanostructures. The first transmission wavelength may be changed or modified by changing the dimensions of each of the multiple first nanostructures and / or the periodicity of the multiple first nanostructures. The second transmission wavelength may be changed or modified by changing the dimensions of each of the multiple second nanostructures and / or the periodicity of the multiple second nanostructures. Each of the at least one first filter element and at least one second filter element may include or define an electromagnetic metasurface.

[0017] The device may include at least one window or opening. The at least one window or opening may be positioned adjacent to at least one of at least one first filter element and at least one second filter element. The at least one window or opening may allow simultaneous acquisition of unfiltered image data as well as image data filtered by the at least one first filter element and / or at least one second filter element.

[0018] At least one first filter element, at least one second filter element, and / or at least one window or opening may be arranged alternately. For example, at least one first filter element, at least one second filter element, and / or at least one window or opening may be arranged to define a checkerboard pattern. Alternatively or additionally, at least one first filter element, at least one second filter element, and / or at least one window may be arranged to form a mosaic arrangement, such as a mosaic quarto arrangement, a random arrangement, or a semi-random arrangement.

[0019] The device may include at least one further filter element. The further element may include a plurality of further nanostructures. The plurality of further nanostructures may be configured such that at least one further filter element includes a further transmission wavelength different from the first and second transmission wavelengths.

[0020] According to a second aspect of the present disclosure, a method of generating an image acquired by an imaging system is provided. The imaging system includes an image sensor, the image sensor includes a pixel array, includes an optical filter device according to the first aspect, the at least one first filter element is associated with at least one first pixel of the pixel array, the at least one second filter element is associated with at least one second pixel of the pixel array, the method includes receiving data representing a first signal detected by the at least one first pixel, receiving data representing a second signal detected by the at least one second pixel, selecting at least one of the first signal and the second signal to generate the image, and generating the image using at least one of the selected first signal and second signal.

[0021] The method may enable so-called “post-processing” of the pixel array of the image sensor. For example, an image based on at least one first pixel and / or at least one second pixel associated with each of the at least one first filter element and / or the at least one second filter element may be generated.

[0022] The first and second signals may be received simultaneously or sequentially.

[0023] The method may include displaying the image. The image may include a filtered image.

[0024] At least one window or aperture may be associated with at least one third pixel of the pixel array. Alternatively or additionally, the pixel array may include another pixel. The other pixel may be configured to detect unfiltered light or radiation. The method may include receiving data representing a third signal detected by at least one third pixel or the other pixel. The method may include, for example, selecting the third signal to generate an unfiltered image. The method may include, for example, using the third signal to generate an unfiltered image. The method may include displaying the unfiltered image.

[0025] According to a third aspect of the present disclosure, an imaging system including an image sensor is provided. The image sensor includes a pixel array and an optical filter device according to the first aspect, and the at least one first filter element is associated with at least one first pixel of the pixel array, and the at least one second filter element is associated with at least one second pixel of the pixel array.

[0026] This device and / or system may enable multispectral imaging using, for example, a single image sensor. For example, this device and / or system can reduce the number of image sensors required for multispectral imaging. Some multispectral imaging systems may include multiple image sensors, each having its own filter. Each of the multiple image sensors may consume power and / or generate electrical noise. Therefore, the power consumption and / or electrical noise generation in an imaging system including this device may be reduced compared to a multispectral imaging system including multiple image sensors. This may lead to an improvement in the signal-to-noise ratio. This device may allow the imaging system to be more compact compared to a multispectral imaging system including multiple image sensors. Additionally or alternatively, the use of optical diffracting elements such as prisms and gratings, and related devices such as one or more actuators for moving the diffracting elements, may be avoided. This may facilitate the use of the imaging system in space-constrained devices, systems, or apparatus such as vehicles and satellites.

[0027] The device may be positioned relative to a pixel array such that at least one first filter element is associated with at least one first pixel of the pixel array, and at least one second filter element is associated with at least one second pixel of the pixel array.

[0028] The device may be arranged relative to a pixel array such that, for example, light or radiation detected by an image sensor passes through at least one first filter element and / or at least one second filter element before it enters at least one first pixel and / or at least one second pixel of the pixel array, respectively.

[0029] At least one window or aperture may be associated with at least one third pixel of the pixel array. The device may be positioned relative to the pixel array such that at least one window or aperture is associated with at least one third pixel of the pixel array.

[0030] The system includes a processing device configured to perform the method according to the second embodiment.

[0031] A fourth aspect of the present disclosure provides a computer program that includes instructions causing a processing device to perform the method according to the second aspect when the program is executed by the processing device.

[0032] A fifth aspect of the present disclosure provides a method for manufacturing an optical filter device for use with an image sensor. The method comprises forming at least one first filter element comprising a plurality of first nanostructures and forming at least one second filter element comprising a plurality of second nanostructures, wherein the plurality of first nanostructures are configured such that the at least one first filter element includes a first transmission wavelength, and the plurality of second nanostructures are configured such that the at least one second filter element includes a second transmission wavelength different from the first transmission wavelength.

[0033] A sixth aspect of the present disclosure provides a method for manufacturing an imaging system. The method includes providing an image sensor including a pixel array, providing an optical filter device according to a first aspect, and attaching the optical filter device to the image sensor such that at least one first filter element is associated with at least one first pixel of the pixel array and at least one second filter element is associated with at least one second pixel of the pixel array.

[0034] The above summary is intended to be illustrative and not limiting. This disclosure includes one or more corresponding aspects, embodiments, or features, either alone or in various combinations, whether specifically described (claimed) or not. Features defined above in accordance with any aspect of this disclosure, or defined below in relation to a particular embodiment of this disclosure, may be used alone or in combination with other defined features in any other aspect or embodiment, or may form a further aspect or embodiment of this disclosure. [Brief explanation of the drawing]

[0035] Next, some preferred embodiments of the present disclosure will be described, only illustratively, with reference to the accompanying drawings.

[0036] [Figure 1] A schematic diagram of an exemplary imaging system according to one embodiment is shown, and the imaging system includes an optical filter device and an image sensor. [Figure 2] Figure 1 shows a cross-sectional view of the imaging system. [Figure 3] Figure 1 shows a schematic diagram of an exemplary optical filter device for use in the imaging system. [Figure 4] Figure 1 shows a schematic diagram of another exemplary optical filter device for use in the imaging system shown. [Figure 5] A schematic diagram of another exemplary optical filter device for use in the imaging system shown in the figure is provided. [Figure 6] Schematic diagrams of exemplary first and second filter elements for use in any one of the optical filter devices shown in Figures 1 to 5 are provided. The first filter element includes a first nanostructure, and the second filter element includes a second nanostructure. [Figure 7] Figure 6 shows schematic diagrams of the unit cells of the first and second nanostructures. [Figure 8]The simulated transmission spectra of three exemplary filter elements are shown, one or more of which may be used in any one of the optical filter devices shown in Figures 1 to 5. [Figure 9] This is a flowchart outlining a method for generating images acquired by an imaging system according to one embodiment. [Figure 10A] A schematic representation of an exemplary matrix or array generated from image frames acquired by the image sensor in Figure 1 is shown. [Figure 10B] Figure 10A shows an enlarged view of the matrix or array. [Figure 11A] A schematic diagram shows an exemplary further matrix or array generated using multiple first signals from the matrix or array in Figure 10A. [Figure 11B] A schematic diagram shows an exemplary further matrix or array generated using multiple second signals from the matrix or array in Figure 10A. [Figure 12] This flowchart outlines a method for manufacturing an optical filter device according to one embodiment. [Figure 13] Figures 1 through 5 show schematic cross-sectional views of a filter element to be used in one of the optical filter devices. [Figure 14] This flowchart outlines a method for manufacturing an imaging system according to one embodiment. [Modes for carrying out the invention]

[0037] Figure 1 shows a schematic diagram of an exemplary imaging system 2 according to one embodiment. System 2 includes an image sensor 4 including a pixel array 6. Only some pixels 6a of the pixel array are shown in Figure 1. The pixel array 6 may include j columns of pixels and i rows of pixels. In the embodiment shown in Figure 1, j and i are equal to 4. However, it will be understood that in other embodiments, the pixel array may include more or fewer pixels than 4 columns and / or more or fewer pixels than 4 rows. For example, the pixel array may include 1280 columns of pixels and 1024 rows of pixels, or vice versa, or any other number of rows and columns. The number of rows and columns of the pixel array 6 may determine the size and / or resolution of the pixel array 6. The image sensor 4 may be provided in the form of a single-photon avalanche diode (SPAD) array. However, it will be understood that in other embodiments, other image sensors may be used, such as charge-coupled devices (CCDs), complementary metal-oxide-semiconductor CMOS sensors (e.g., CMOS sensors containing III-V compound semiconductor materials and / or II-VI compound semiconductor materials), and active pixel sensors.

[0038] System 2 includes an optical filter device 8. The device 8 includes at least one first filter element 10 and at least one second filter element 12. In the embodiment shown in Figure 1, the device 8 includes four first filter elements 10 and four second filter elements 12. Each of the first filter elements 10 includes a first transmission wavelength. Each of the second filter elements 12 includes a second transmission wavelength different from the first transmission wavelength. In other embodiments, it will be understood that the device may include more or fewer than four first filter elements and / or more or fewer than four second filter elements. Additionally or alternatively, the device may include at least one further filter element having further transmission wavelengths different from the first and second transmission wavelengths.

[0039] As can be seen from Figure 1, the first and second filter elements 10 and 12 are arranged to form a filter element array. This may facilitate the use of the device with an image sensor. In the embodiment shown in Figure 1, the filter element array includes k rows and l columns, where k=1 to i and l=1 to j. In other words, the filter element array may have the same or fewer columns and / or rows as the pixel array 6. The number of rows and columns of the filter element array may determine the size and / or resolution of the filter element array.

[0040] The device 8 may include at least one window 14. In the embodiment shown in Figure 1, the device 8 includes multiple windows 14, eight of which are shown. The windows 14 may also be referred to as openings or blank spaces. In other embodiments, it will be understood that the device may include more or fewer than eight windows. Some pixels 6a of the pixel array 6 are visible through the windows 14.

[0041] In the exemplary apparatus 8 shown in Figure 1, each first filter element 10 is positioned adjacent to a window 14, and each second filter element 12 is positioned adjacent to another window 14. However, it will be understood that in other embodiments, the windows, the first and second filter elements may be positioned differently, and / or the apparatus may not include windows.

[0042] The first and second filter elements 10 and 12 may each be associated with each pixel of the pixel array 6. For example, each first filter element 10 may be associated with each first pixel of the pixel array 6. The device 8 may be positioned relative to the pixel array 6 such that each first filter element 10 covers each first pixel. For example, the device 8 may be positioned relative to the pixel array 6 such that light or radiation detected by the image sensor 4 passes through each first filter element 10 before entering each first pixel.

[0043] Each of the second filter elements 12 is associated with each second pixel of the pixel array 6. The device 8 may be positioned relative to the pixel array 6 such that each second filter element 12 covers each second pixel. For example, the device 8 may be positioned relative to the pixel array 6 such that light or radiation detected by the image sensor 4 passes through the second filter elements 12 before entering each second pixel.

[0044] Each window 14 is associated with a third pixel of the pixel array 6, which is indicated by reference numeral 6a in Figure 1. Each window 14 may be positioned such that unfiltered light or radiation is detected by its respective third pixel.

[0045] In the embodiment shown in Figure 1, System 2 also includes a processing device 16. The processing device 16 may include one or more processors 16a, such as a field-programmable gate array (FPGA), a digital signal processor (DSP), or an application-specific integrated circuit (ASIC). The processing device 16 may include a storage medium 16b, such as a non-temporary computer-readable storage medium. The storage medium 16b may include volatile memory, such as random-access memory (RAM), non-volatile memory, such as read-only memory (ROM) and / or electrically erasable programmable ROM (EEPROM). System 2 may include a display screen 17 that displays one or more images acquired by the image sensor 4. The display screen 17 may be provided in the form of a CRT (cathode ray tube), plasma, LED (light-emitting diode), or LCD (liquid crystal display) screen or monitor. In other embodiments, it will be understood that the display may be provided separately from the system.

[0046] Figure 2 shows a cross-sectional view of system 2 shown in Figure 1. The device 8 may be positioned relative to the image sensor 4 such that the first filter element 10, the second filter element 12, and the window 14 are each associated with and / or aligned with the first, second, and third pixels, respectively. The device 8 may be positioned relative to the image sensor 4 such that light or radiation detected by the image sensor passes through the device 8 before entering the pixel array 6. The device 8 may be attached to the image sensor 4 using an adhesive layer 15, such as a transparent adhesive layer. The adhesive layer 15 may have a thickness of about 5 μm. However, it will be understood that in other embodiments, the device may be attached to the image sensor in a different manner.

[0047] Figure 3 shows a schematic diagram of an exemplary optical filter device 8 for use in the imaging system 2 shown in Figure 1. The device 8 shown in Figure 3 is similar to that shown in Figure 1. Therefore, any feature described with respect to Figure 1 can be applied to the device 8 shown in Figure 3. Only the differences will be described below.

[0048] In the embodiment shown in Figure 3, the apparatus 8 does not include the window 14. In this embodiment, each first filter element 10 is adjacent to one or more second filter elements 12. In other words, the first and second filter elements 10, 12 may be arranged alternately. For example, the first and second filter elements may be arranged to define a checkerboard pattern. This arrangement can reduce or minimize the number of image errors when generating the filtered image, as will be described later.

[0049] Figure 4 shows a schematic diagram of another exemplary optical filter device 8 for use in the imaging system 2 shown in Figure 1. The device 8 shown in Figure 4 is similar to that shown in Figure 1. Therefore, any feature described with respect to Figure 1 can be applied to the device 8 shown in Figure 4. Only the differences will be described below.

[0050] In the embodiment shown in Figure 4, the apparatus does not include a window 14. Two or more first filter elements 10 may be arranged adjacent to each other. For example, four first filter elements 10 may be arranged adjacent to each other to form, for example, a block of first filter elements 10. Two or more second filter elements 12 may be arranged adjacent to each other. For example, four second filter elements 12 may be arranged adjacent to each other to form, for example, a block of second filter elements. A block of first filter elements 10 may be arranged adjacent to a block of second filter elements 12. The size of the block of first filter elements and / or the size of the block of second filter elements may be selected based on the size or resolution of the pixel array 6, for example, to avoid an increase in the number of image errors and / or a decrease in the quality of the filtered image.

[0051] Figure 5 shows a schematic diagram of another exemplary optical filter device 8 for use in the imaging system 2 shown in Figure 1. The device 8 shown in Figure 5 is similar to that shown in Figure 1. Therefore, any feature described with respect to Figure 1 can be applied to the device 8 shown in Figure 5. Only the differences will be described below.

[0052] In the embodiment shown in Figure 5, the number of columns l is equal to 9 and the number of rows k is equal to 9. The device includes a plurality of filter elements 11a to 11i, nine of which are shown in Figure 5. Each of the filter elements 11a to 11i contains a different transmission wavelength. One of the filter elements 11a to 11i may include a first filter element 10, and another of the filter elements 11a to 11i may include a second filter element 12.

[0053] In the embodiment shown in Figure 5, the filter elements 11a to 11i are arranged to define a mosaic array, such as a four-part mosaic array. The exemplary device shown in Figure 5 may be suitable for use with an imaging sensor having a large pixel array. This arrangement can reduce or minimize the number of image errors when generating a filtered image, as will be discussed later.

[0054] Apparatus 8 is not limited to the exemplary apparatus disclosed herein. For example, other apparatuses may have a different number of filter elements and / or windows having different transmission wavelengths. Alternatively or additionally, the filter elements and / or windows may be arranged randomly or semi-randomly. This may reduce the number of image errors when generating filtered images. For example, a random or semi-random arrangement of filter elements and / or windows may result in fewer moiré patterns or similar interference fringes or interference patterns. In yet another embodiment, the apparatus may include rows and / or columns of filter elements having the same transmission wavelength. For example, a certain number of filter elements having different transmission wavelengths, a certain number of windows, and / or the arrangement of said filter elements and / or windows may be selected based on a selected or desired resolution of filtered and / or unfiltered image data.

[0055] Figure 6 shows schematic diagrams of exemplary first and second filter elements for use in the apparatus 8 shown in any one of Figures 1 to 5. Each of the filter elements 10, 11a-11i, and 12 described above includes multiple nanostructures. The nanostructures of the filter elements 10, 11a-11i, and 12 are configured to include different transmission wavelengths for each of the filter elements 10, 11a-11i, and 12.

[0056] By configuring nanostructures to transmit at different wavelengths, the apparatus 8 can enable parallel acquisition of image data related to at least two different wavelengths. In other words, the apparatus 8 and / or system 2 can enable multispectral imaging using, for example, a single imaging sensor. For example, the apparatus 8 and / or system 2 described herein can reduce the number of imaging sensors required for multispectral imaging. Some multispectral imaging systems may include multiple imaging sensors, each having its own filter. Each of the multiple imaging sensors may consume power and / or generate electrical noise. Therefore, the power consumption and / or electrical noise generation in imaging system 2 including apparatus 8 can be reduced compared to a multispectral imaging system including multiple imaging sensors. This can lead to an improvement in the signal-to-noise ratio. The apparatus 8 can make imaging system 2 more compact compared to a multispectral imaging system including multiple imaging sensors. Additionally or alternatively, the use of optical diffraction elements such as prisms, gratings, and related devices can be avoided. This can facilitate the use of imaging system 2 in space-constrained devices, systems, or apparatus such as vehicles and satellites.

[0057] The use of nanostructures may make it possible to manufacture each filter element 10, 11a-11i, 12 in a size or dimension corresponding to the size or dimension of each pixel in the pixel array 6, for example, in a substantially corresponding size or dimension.

[0058] Additionally or alternatively, by providing filter elements containing nanostructures, detection of multiples of different transmission wavelengths can be prevented. This is because filter elements 10, 11a-11i, and 12 can be configured to enable resonance coupling of surface plasmon polaritons (SPPs) on their surfaces. Light or radiation incident on filter elements 10, 11a-11i, and 12 may result in extraordinary optical transmission (EOT), as will be described later. The following description refers to the first and second filter elements 10 and 12 shown in Figures 1 to 4 above. However, it will be understood that any feature of the first and second filter elements 10 and 12 described below can also be applied to the filter elements 11a-11i shown in Figure 5.

[0059] The first filter element 10 includes a plurality of first nanostructures 18. The first nanostructures 18 are configured such that the first filter element 10 includes a first transmission wavelength. In other words, the first nanostructures 18 may be configured such that the first filter element 10 transmits light or radiation having a first wavelength. The terms "first transmission wavelength" and "first wavelength" may be used interchangeably.

[0060] The second filter element 12 includes a plurality of second nanostructures 20. The second nanostructures 20 are configured such that the second filter element 12 includes a second transmission wavelength. In other words, the second nanostructures may be configured such that the second filter element 12 transmits light or radiation having a second wavelength. The terms “second transmission wavelength” and “second wavelength” may be used interchangeably. As described above, the first and second transmission wavelengths are different. For example, at least one of the first and second transmission wavelengths may be greater than at least one of the other first and second transmission wavelengths.

[0061] The first and second transmission wavelengths may be between approximately 0.8 μm and approximately 7 μm. Thus, the apparatus 8 and / or system 2 may enable the detection of gases in the atmosphere, such as greenhouse gases. For example, the first transmission wavelength may include the emission wavelength of methane (CH4). In this example, the first transmission wavelength is approximately 1.6 μm. However, in other examples, it will be understood that the first transmission wavelength may be 2.3 μm or 3.3 μm. The second transmission wavelength may include the emission wavelength of carbon dioxide (CO2). In this example, the second transmission wavelength is approximately 4.2 μm. However, in other examples, it will be understood that the second transmission wavelength may be approximately 1.6 μm, 2 μm or 2.7 μm.

[0062] It will be understood that the first and / or second transmission wavelengths are not limited to the exemplary values ​​disclosed herein. For example, in other embodiments, the first or second transmission wavelength may include emission wavelengths of nitrogen oxides such as about 1.8 μm, 2.2 μm, 2.7 μm, 2.8 μm, 3.4 μm, 4.5 μm, or 5.2 μm. In addition, it will be understood that in other embodiments, only one of the first and second transmission wavelengths may be between about 0.8 μm and about 7 μm.

[0063] The apparatus 8 and / or system 2 described herein may have applications other than the detection of gases in the atmosphere. For example, the apparatus 8 and / or system 2 may enable the detection of water in soil, the detection of human skin, the detection of cracks or defects in materials such as plastics, the detection of any material exhibiting an optical spectrum in the wavelength range of about 0.8 μm to about 7 μm, and the identification of ice and water.

[0064] In this embodiment, the first and second nanostructures 18, 20 include a plurality of pores. However, it will be understood that in other embodiments, the first and / or second nanostructures may be implemented differently. For example, in such other embodiments, the first and / or second nanostructures may be implemented as slits, grooves, and / or protrusions such as columns, pyramids, cones, etc.

[0065] Some of the holes are circular, and some are elliptical. However, in other embodiments, it will be understood that all the holes may have the same shape, and / or at least one or all of the holes may have different shapes, such as square, rhombus, rectangle, triangle, or other polygonal shape.

[0066] In some embodiments, the first and second filter elements 10 and 12 may each include a metallic material layer 19a. The metallic material layer 19a may include a metallic material such as copper or aluminum, or a transition metal material such as gold, silver, or chromium. The metallic material layer may have a thickness of about 30 nm to 400 nm, preferably 50 nm to 100 nm, for example, between 80 nm. In such embodiments, the metallic material layer forms a metal-air interface with the air in the environment surrounding the apparatus 8. However, in other embodiments, it will be understood that at least one or each of the first and second filter elements may include a layer of glass material such as a chalcogenide glass material. The chalcogenide glass material may include germanium-antimony-tellurium (GST), etc. The chalcogenide glass material may change between an amorphous phase and a crystalline phase in response to, for example, thermal excitation. When the chalcogenide glass material changes between an amorphous phase and a crystalline phase, the resistivity of the chalcogenide glass material may also change. For example, the resistivity of chalcogenide glass materials can increase in the amorphous phase compared to the crystalline phase. In the crystalline phase, chalcogenide glass materials can behave like metals.

[0067] In some embodiments, the first and second filter elements 10, 12 may each include a metallic material layer and a dielectric material layer. The dielectric material layer may be placed on the metallic material layer to define the metal-dielectric interface. The dielectric material layer may include an oxide material such as silicon dioxide and / or a nitride material such as silicon nitride. The dielectric material layer may have a thickness between 200 nm and 400 nm, for example, about 300 nm. The dielectric material layer may be placed on the metallic material layer to increase the transmittance of the first and second filter elements 10, 12 and / or as a protective capping layer for the metallic material layer. In other embodiments, it will be understood that only one of the first and second filter elements may include a dielectric material layer, and / or the dielectric material layer may be placed on at least one of the first and second filter elements or on each of their respective glass material layers.

[0068] Each of the first and second filter elements includes or defines an electromagnetic metasurface. For example, the first nanostructure 18 and the second nanostructure 20 are arranged in a periodic array. The first and second nanostructures 18 and 20 are formed in a metallic material layer. The periodic array of the first and second nanostructures 18 and 20 in the metallic material layer can result in resonant coupling of SPPs on the surface of the metallic material layer. Light or radiation incident on the first and second filter elements 10 and 12 can result in EOT (anomalous light transmission), for example, due to resonant coupling and constructive interference of SPPs on the surface of the metallic material layer. Due to the discontinuity of dielectric constant at the metal-dielectric or metal-air interface, the SPPs have in-plane momentum. Under perpendicularly incident light or radiation, free-space radiation cannot directly couple to the SPPs. However, the first and second nanostructures 18 and 20 can provide additional momentum. For example, the SPP momentum vector is given by the following equation: k SPP =k sinθ +k i,j Here, k sinθ k is the momentum from light or radiation incident on the first and second filter elements 10 and 12, and k i,j This depends on the order of the diffraction grating. For normally incident light, k sinθis zero, and k SPP is given by the following equation. [Number] Here, p is the period of the first or second nanostructure 18, 20, i and j are the diffraction orders, ε m is the dielectric constant of the metal material layer, and ε d is the dielectric constant of the air and / or dielectric material layer. The first and second transmission wavelengths are considered to depend on the SPP momentum vector. The coupling between the incident light or radiation and the SPP depends on the period p of the first or second nanostructure 18, 20. Therefore, the first and second transmission wavelengths can be changed or adjusted by changing the periods of the first and second nanostructures 18, 20, respectively. Thereby, the possible wavelength ranges of the first and second transmission wavelengths of the first and second filter elements 10, 12 can be broadened, respectively.

[0069] In addition, the dimensions of each of the first nanostructures 18 and each of the second nanostructures 20 in the metal material layer can assist the resonant coupling of SPPs on the surface of the metal material layer. The dimensions of each of the first nanostructures 18 and each of the second nanostructures 20 can correspond to fractions of the first and second transmission wavelengths, respectively. Thereby, confinement of SPPs in the first and second nanostructures 18, 20 can be made possible. For example, the dimensions of each of the first nanostructures 18 and each of the second nanostructures 20 can be selected as approximately one-fourth of the first and second transmission wavelengths, respectively. The first and second transmission wavelengths can be changed or adjusted by changing the dimensions of each of the first nanostructures 18 and each of the second nanostructures 20. Thereby, the possible wavelength ranges of the first and second transmission wavelengths of the first and second filter elements 10, 12 can be broadened, respectively.

[0070] The size of each first and second filter element may correspond to the size of each first and second pixel. For example, each of the first and second filter elements may include the length L and width W shown in Figure 6 only for the first filter element 10 for clarity. The length L and width W of each first and second filter element 10, 12 may correspond to the length and width of each first and second pixel.

[0071] Figure 7 shows a schematic diagram of the unit cell UC of the first and second nanostructures 18 and 20 shown in Figure 6. The term “unit cell” may be understood as the smallest part of the arrangement of the first and second nanostructures 18 and 20, respectively. This represents the overall pattern of the arrangement of the first and second nanostructures 18 and 20, respectively. The unit cell UC is indicated by a dashed box in the first and second filter elements 10 and 12, respectively, shown in Figure 6. As seen in Figure 7, each unit cell UC contains six circular holes and two elliptical holes. The circular holes are located at the periphery of the unit cell and surround the elliptical holes. The circular holes are arranged to define the rectangular shape of the unit cell UC. However, it will be understood that the first and second filter elements 10 and 12 are not limited to the arrangements of the first and second nanostructures 18 and 20 disclosed herein. For example, in other embodiments, the nanostructures may be arranged in a square grid arrangement, a non-periodic arrangement, etc. Additionally or alternatively, in such other embodiments, the nanostructures may have different sizes or dimensions.

[0072] The period p of the first and second nanostructures 18 and 20 is shown in Figure 7 and may be understood as the distance between the center of the elliptical pore and the center of the circular pore.

[0073] Each elliptical hole includes a first axis a and a second axis b. The first axis a is also called the major axis or principal axis of the elliptical hole. The second axis b is also called the minor axis or secondary axis of the elliptical hole. The second axis b of each elliptical hole may be selected to correspond to about one-quarter of the first or second transmission wavelength. The ratio of the second axis to the first axis b / a may be selected in the range of about 0.86 to 0.88.

[0074] Each hole contains a diameter d. This diameter can be selected to be approximately the same as the first axis a of each elliptical hole.

[0075] In the example where the first transmission wavelength is approximately 1.6 μm, the second axis b of each elliptical pore in the first nanostructure 18 is approximately 400 nm, and the first axis a is approximately 454 nm to 465 nm. In such an example, the diameter d of each pore in the first nanostructure 18 is approximately 454 nm to 465 nm. The period p of the first nanostructure 18 may be approximately 1.17 μm.

[0076] In the example where the second transmission wavelength is approximately 4.2 μm, the second axis b of each elliptical pore in the second nanostructure 20 is approximately 1,050 nm, and the first axis a is approximately 1,193 nm to 1,220 nm. In such an example, the diameter d of each pore in the second nanostructure 20 is approximately 1,193 nm to 1,220 nm. The period p of the second nanostructure 20 may be approximately 1.17 μm.

[0077] Figures 5 and 6 show that the elliptical pores are positioned at a constant angle to at least one side of the unit cell UC. The first side of the unit cell may include or define the length L1 of the unit cell UC. The second side of the unit cell may include or define the width W1 of the unit cell UC. The length L1 of the unit cell UC can be considered to extend in the x-direction, as shown in the coordinate system shown in Figure 7. The width of the unit cell can be considered to extend in the y-direction, as shown in the coordinate system shown in Figure 7. At least one of the elliptical pores may be positioned such that the first axis a of the elliptical pore extends at an angle of approximately 45° to the length L1 of the unit cell UC. At least one of the elliptical pores may be positioned such that the first axis a of the elliptical pore extends at an angle of approximately 135°. This arrangement of elliptical pores may increase the containment of SPPs in the first and second nanostructures 18, 20. It will be understood that the implementation, size, and / or shape of the first and / or second nanostructures may be selected to increase the confinement of SPPs in the first and second nanostructures.

[0078] It will be understood that each of the filter elements 11a to 11i shown in Figure 5 contains multiple nanostructures. The nanostructures of each filter element may be configured such that each filter element 11a to 11i contains different transmission wavelengths. For example, the dimensions and / or shape of each nanostructure of each filter element 11a to 11i, and / or the period of each nanostructure of each filter element 11a to 11i may be selected so that each filter element 11a to 11i contains different transmission wavelengths. Any of the features described for the first and second nanostructures may be applied to the nanostructures of each filter element 11a to 11i.

[0079] Figure 8 shows simulated transmission spectra of three exemplary filter elements that may be used in any of the optical filter devices described herein. The transmission spectra shown in Figure 8 were simulated for three filter elements, including an array of nanostructures having the unit cell shown in Figure 7.

[0080] The transmission spectra shown in Figure 8 were simulated for a first filter element having a first transmission wavelength λ1, a second filter element having a second transmission wavelength λ2, and a third filter element having a third transmission wavelength λ3.

[0081] The transmission spectra shown in Figure 8 were simulated using a computer program configured to employ the time-domain finite difference (FDTD) method. However, it will be understood that any computer program configured to solve Maxwell's equations or perform exact coupled-wave analysis (RCWA) may be used to simulate the transmission spectra of the filter elements disclosed herein. The transmission spectra shown in Figure 8 were simulated for each of the three filter elements, each containing multiple nanostructures.

[0082] The nanostructures of the first, second, and third filter elements are arranged and / or formed in the same manner as the first or second nanostructures 18, 20 shown in Figures 6 and 7. However, the dimensions of each nanostructure differ in the simulated transmission spectrum. For example, each elliptical hole of the first filter element has a first axis a at approximately 325 nm and a second axis b at approximately 300 nm. Each circular hole of the first filter element has a diameter d at approximately 352 nm. The period of the nanostructure of the first filter element is approximately 0.92 μm. These dimensions of the first filter element and the period of the nanostructure result in a first transmission wavelength λ1 of approximately 1,350 nm.

[0083] Each elliptical hole in the second filter element has a first axis a of approximately 400 nm and a second axis b of approximately 340 nm. Each circular hole in the second filter element has a diameter d of approximately 400 nm. The period of the nanostructure of the second filter element is approximately 1.12 μm. These dimensions and the period of the nanostructure of the second filter element result in a second transmission wavelength λ2 of approximately 1,590 nm.

[0084] Each elliptical hole in the third filter element has a first axis a at approximately 418 nm and a second axis b at approximately 360 nm. Each circular hole in the third filter element has a diameter d at approximately 418 nm. The period of the nanostructure of the third filter element is approximately 1.17 μm. These dimensions and the period of the nanostructure of the third filter element result in a second transmission wavelength λ2 of approximately 1,650 nm.

[0085] Therefore, the transmission wavelength of the filter element can be changed by changing the size and / or period of the nanostructure of the filter element. In the transmission spectrum simulation, it was assumed that the nanostructures of the first, second, and third filter elements were formed on a gold layer with a thickness of 80 nm, on which a 300 nm silicon dioxide layer was placed. The relative dielectric constants of gold and silicon dioxide depended on the wavelength of light or radiation incident on the first, second, and third filter elements and were obtained from a materials library in a computer program. Alternatively, the relative dielectric constants of gold and silicon dioxide may be determined or simulated based on the refractive indices of gold and silicon dioxide, respectively.

[0086] In the transmission spectrum simulation, it was assumed that the angle of incidence of light or radiation to the surfaces of the first, second, and third filter elements was approximately 90°. In addition, the light or radiation incident on the first, second, and third filter elements was simulated to include plane waves. However, it will be understood that in other embodiments, one or more transmission spectra may be simulated based on an angle of incidence of light or radiation different from 90°, and / or light or radiation focused using an optical device such as a lens configured to focus light or radiation onto the surfaces of one or more filter elements, for example.

[0087] Figure 9 is a flowchart illustrating an overview of a method for generating an image acquired by an imaging system such as the imaging system 2 described above, according to one embodiment. As described above, system 2 may include a processing device 16. A computer program containing instructions to cause the processing device 16 to execute this method when the program is executed by the processing device 16 may be stored in the storage medium 16b.

[0088] In step 30, the method includes receiving data representing a first signal detected by a pixel. The first pixel may be associated with the first filter element 10 or at least one of the filter elements 11a to 11i. The method also includes receiving data representing a second signal detected by a second pixel. The second pixel may be associated with the second filter element 12 or at least one other of the filter elements 11a to 11i. The first and second signals, respectively, may represent the number or intensity of photons detected by the first and second pixels.

[0089] As described above, the first and second filter elements 10, 12 and / or filter elements 11a to 11i may be arranged to form an array of filter elements, for example, as shown in any one of Figures 1 to 5.

[0090] Therefore, the first and second signals may be represented as a matrix or array generated for each image frame acquired by the image sensor 4, or as part thereof.

[0091] Figure 10A schematically shows an exemplary matrix or array 22 containing the first and second signals 10a and 12a of the image frame acquired by the image sensor 4. The matrix or array 22 may have k rows and l columns. The size of the matrix or array 22 may be the same as the size of the pixel array 6.

[0092] Figure 10B shows an enlarged view of the matrix or array 22 shown in Figure 10A. The first and second signals 10a and 12a are arranged in the matrix or array 22 in the same manner as at least one of the first and second filter elements 10 and 12 or filter elements 11a to 11i and at least one other of the filter elements 11a to 11i. In this example, the arrangement of the first and second signals 10a and 12a in the matrix or array 22 corresponds to the apparatus 8 of the first and second filter elements 10 and 12 shown in Figure 3. However, it will be understood that in other embodiments, the first and second signals may be arranged differently.

[0093] In step 32, the method includes selecting at least one of the first and second signals to generate a filtered image. For example, it may be desirable to generate an image filtered by the first filter element 10, the second filter element 12, at least one of the filter elements 11a to 11i, or at least one other of the filter elements 11a to 11i of the device 8. Alternatively, it may be desirable to generate an image filtered by both the first and second filter elements 10 and 12 of the device 8, or by at least one of the filter elements 11a to 11i and at least one other of the filter elements 11a to 11i.

[0094] In step 34, the method includes generating a filtered image using at least one of the selected first and second signals 10a, 12a. At least one of the selected first and second signals 10a, 12a may be represented or provided as a further matrix or array.

[0095] Figure 11A schematically shows an exemplary further matrix or array 24a generated using the first signal 10a of the matrix or array 22 shown in Figure 10A. Figure 11B schematically shows an exemplary further matrix or array 24b generated using the second signal 12a of the matrix or array 22 shown in Figure 10A. From Figures 11A and 11B, it can be seen that the number of rows and columns of each of the further matrices or arrays 24a and 24b is less than the number of rows and columns of the matrix or array 22, for example, due to the arrangement of the first and second filter elements 10 and 12. In this example, each of the further matrices or arrays 24 contains k / 2 rows and l / 2 columns.

[0096] In step 36, the method includes displaying a further matrix or array 24 as a filtered image, for example, on a display screen 17.

[0097] System 2 and / or method may enable so-called "post-processing" of the pixel array 6 of the image sensor 4. For example, as described above, only images based on pixels of the pixel array 6 associated with the first or second filter elements 10, 12 or any of the filter elements 11a to 11i may be generated and / or displayed.

[0098] In addition, as described above, the apparatus 8 of the first and second filter elements 10, 12 and / or filter elements 11a to 11i may be selected such that the number of first filter elements 10 differs from the number of second filter elements 12, or at least one number of filter elements 11a to 11i differs from at least one other number of filter elements 11a to 11i. This may result in the resolution of the image generated using the first signal 10a being different from the resolution of the image generated using the second signal 12a.

[0099] As described above, in some embodiments, the apparatus 8 also includes a window 14. In such embodiments, the processing device 16 may be configured to generate an unfiltered image using a third signal detected by a third pixel.

[0100] For example, the method may include receiving data representing a third signal detected by a third pixel or another pixel configured to detect unfiltered light or radiation. For example, the other pixels may not be covered by the device 8. For example, in some embodiments, the size of the filter element array may be smaller than the size of the pixel array. This may result in one or more pixels of the pixel array not being covered by the device.

[0101] The third signal may indicate the number or intensity of photons detected by the third pixel or other pixels. The third signal may be represented as a matrix or array generated for each image frame acquired by the image sensor 4, or as part thereof. For example, the first, second, and third signals may be arranged in a matrix or array in the same manner as the first and second filter elements 10, 12 and window 14, as shown in Figure 1, for example.

[0102] The method may include selecting a third signal to generate an unfiltered image. The method may include generating an unfiltered image using the third signal. The third signal may be represented or provided as a further matrix or array. The method may include displaying the further matrix or array as an unfiltered image, for example, on a display screen. Therefore, by configuring the device 8 to include a window 14 or to be smaller than the pixel array 6, it may be possible to generate an unfiltered image in addition to, or in relation to, a filtered image.

[0103] Figure 12 is a flowchart illustrating an overview of a method for manufacturing an optical filter device according to one embodiment.

[0104] In step 40, the method includes forming a first filter element 10 comprising a plurality of first nanostructures 18.

[0105] In step 42, the method includes forming a second filter element 12 comprising a plurality of second nanostructures 20. Although Figure 12 shows steps 40 and 42 separately, it will be understood that the first and second filter elements 10 and 12 may be formed simultaneously.

[0106] This method may include using a lift-off process or the like to form the first and second filter elements 10 and 12. This may facilitate the manufacture of the apparatus and lead to a reduction in manufacturing time and / or manufacturing costs.

[0107] For example, the resist layer may be deposited on the substrate using a coating or spin coating process. The resist layer may contain a plastic material such as poly(methyl methacrylate) (PMMA). The substrate may contain a glass material such as borosilicate glass. An intermediate layer may be deposited on the substrate before the resist is deposited. The intermediate layer may contain a polymer material such as polydimethylglutarimide (PMGI) and / or a lift-off resist (LOR) layer.

[0108] This method may involve applying a pattern to a resist layer using a lithography process such as electron beam lithography or deep ultraviolet photolithography. The pattern may be applied to the resist layer in a single lithography process step. The pattern is an inversion pattern of first and second filter elements, each containing first and second nanostructures to be formed. Applying the pattern to the resist layer using a single lithography process step may facilitate the manufacture of the apparatus. This may lead to reduced manufacturing time and / or reduced manufacturing costs.

[0109] This method may include depositing a metallic material layer on a patterned resist layer using a deposition process such as an electron beam deposition process. Alternatively or additionally, this method may include depositing a glass material layer on a patterned resist using a deposition process such as thermal deposition or sputtering.

[0110] The method may include removing the resist layer and the metal material layer deposited thereon. This yields a patterned metal material layer on the substrate, for example, thereby forming the first and second filter elements. Alternatively or additionally, the method may include removing the resist layer and the glass material layer deposited thereon. This yields a patterned glass material layer on the substrate, for example, thereby forming the first and second filter elements. In some embodiments, it will be understood that at least one of the first and second filter elements may include a metal material layer, and at least one of the first and second filter elements may include a glass material layer.

[0111] In some embodiments, the method may involve depositing a dielectric material layer on a patterned metallic material layer or a patterned glass material layer using a deposition process such as a plasma-enhanced chemical vapor deposition (PECVD) process. It will be understood that at least one or each of the first and second filter elements may include a dielectric material layer.

[0112] It will be understood that the window may be formed in a manner similar to that of the first and second filter elements. In such embodiments, the pattern applied to the resist layer may be an inverted pattern of the first and second filter elements and the window to be formed.

[0113] It will be understood that this method may include one or more additional steps, such as an annealing step of a patterned metal layer or a patterned glass material layer on a substrate.

[0114] It will be understood that any of the filter elements 11a to 11i may be formed in the same manner as the first and / or second filter elements.

[0115] Figure 13 shows a schematic cross-sectional view of a filter element for use in one of the optical filter devices 8 shown in Figures 1 to 5. The filter element shown in Figure 13 may include a first filter element 10, a second filter element 12, or any of the filter elements 11a to 11i. The filter element shown in Figure 13 may be manufactured using the method described with respect to Figure 12.

[0116] As shown in Figure 13, the filter element may include a substrate 26. The filter element may include a metallic material layer 28. The metallic material layer 28 is placed on the substrate 26. Nanostructures, such as a first nanostructure, a second nanostructure, or any of the nanostructures of filter elements 11a to 11i (not shown in Figure 13), are formed on the metallic material layer 28. The filter element may include a dielectric material layer 30. The dielectric material layer 30 is placed on the metallic material layer 28. The substrate 26, metallic material layer 28, and dielectric layer 30 shown in Figure 13 may include any of the features of the substrate, metallic material layer, and / or dielectric material layer described above. In some embodiments, it will be understood that the dielectric material layer does not have to be placed on the metallic material layer. Although Figure 13 shows the filter element including a metallic material layer 28, in other embodiments, it will be understood that the filter element may include a glass material layer instead of, or in addition to, the metallic material layer, as described above.

[0117] Figure 14 is a flowchart illustrating an overview of a method for manufacturing an imaging system according to one embodiment.

[0118] In step 50, the method includes providing an image sensor including a pixel array such as the image sensor 4 described above.

[0119] In step 52, the method includes providing an optical filter device such as the optical filter device 8 described above.

[0120] In step 54, the method includes attaching an optical filter device to an image sensor such that a first filter element is associated with a first pixel of the pixel array and a second filter element is associated with a second pixel of the pixel array.

[0121] For example, the method may include manufacturing the imaging system using a flip-chip process. For example, the image sensor may be aligned with respect to an optical filter device. The image sensor may be attached to the optical filter device using an adhesive, such as an adhesive that is at least transparent in the infrared spectrum. The adhesive may include a light- or radiation-curing adhesive, such as an ultraviolet-curing adhesive. The image sensor and the optical filter device attached thereto may then be flipped so that the optical filter device is positioned above the image sensor.

[0122] Although the processing device 16 is described as local to or part of the image sensor 4, it will be understood that in other embodiments the processing device may be provided separately from and / or remotely from the image sensor. For example, in such other embodiments, the processing device may be part of a computer system that may include a personal computer, laptop computer, tablet computer, mobile phone, smartphone, PDA, etc.

[0123] In other such embodiments, the processing device may include a processor, which may be provided in the form of a central processing unit (CPU), a mathematical coprocessor (MCP), a graphics processing unit (GPU), etc. The processor may be a single-core or multi-core processor. The processing device may include memory and / or other data storage, which may be implemented in DRAM (dynamic random access memory), SSD (solid state drive), HDD (hard disk drive), or other suitable magnetic, optical, and / or electronic memory devices. The processor and / or memory and / or data storage may be located locally, for example, in a single device or in multiple devices communicating in a single location, or may be distributed across multiple local and / or remote devices. The processing device may include a communication module, for example, a wireless and / or wired communication module. The communication module may be configured to communicate via a cellular communication network, Wi-Fi, Bluetooth®, ZigBee®, near-field communication (NFC), IR, satellite communication, or other internet-enabled networks, etc. The communication module may be configured to communicate via Ethernet® or other wired networks or connections, via telecommunications networks such as POTS, PSTN, DSL, ADSL, optical carrier lines, and / or ISDN links or networks, via the cloud and / or the internet, or via other suitable data transmission networks. The communication module may be configured to communicate via optical communication such as optical wireless communication (OWC), optical free space communication, or Li-Fi, or via optical fiber, etc. The processing device may be configured to communicate with the image sensor via the communication module.

[0124] The display screen may be part of a computer system. The computer system may include input devices such as a computer keyboard, mouse, or trackball that allow the user to provide input to the computer system. Other types of devices may also be used. For example, the feedback provided to the user may be any form of sensory feedback, such as visual feedback, auditory feedback, or tactile feedback, and the input from the user may be received in any form, including acoustic, voice, or tactile input. In such other embodiments, the image sensor may include another processing device configured to transmit first, second, and / or third signals to the processing device. The other processing device may be the same as or similar to the processing device 16 described above.

[0125] It should be understood that the term "size" can be used interchangeably with the term "dimension."

[0126] It should be understood that the term "obtained" may be used interchangeably with the terms "acquired," "recorded," or "captured."

[0127] It will be understood that references to multiple features may be used interchangeably with references to the singular forms of those features, such as "at least one" and / or "each." For example, the singular forms of features such as "at least one" or "each" may be used interchangeably.

[0128] While this disclosure is described in terms of the embodiments described above, it should be understood that these embodiments are illustrative only and the claims are not limited to those embodiments. Those skilled in the art will be able to make modifications and substitutions that are deemed to fall within the scope of the appended claims in light of this disclosure. Each feature disclosed or illustrated herein may be incorporated into this disclosure alone or in appropriate combination with any other feature disclosed or illustrated herein.

Claims

1. An optical filter device for use with an image sensor, A first filter element comprising a plurality of first nanostructures, A second filter element comprising multiple second nanostructures and Includes, An apparatus wherein the plurality of first nanostructures are configured such that at least one first filter element includes a first transmission wavelength, and the plurality of second nanostructures are configured such that at least one second filter element includes a second transmission wavelength different from the first transmission wavelength.

2. The apparatus according to claim 1, wherein the first and / or second transmission wavelength is between approximately 0.8 μm and approximately 7 μm.

3. The apparatus according to claim 1 or 2, wherein the at least one first element and the at least one second filter element are arranged to form a filter element array.

4. The apparatus according to any one of claims 1 to 3, wherein at least one or each of the at least one first filter element and the at least one second filter element includes a metal material layer or a glass material layer, the plurality of first nanostructures and the plurality of second nanostructures are formed on the metal material layer or the glass material layer of at least one or each of the at least one first filter element and the at least one second filter element, and optionally, at least one or each of the at least one first filter element and the at least one second filter element includes a dielectric material layer disposed on the metal material layer or the glass material layer.

5. The apparatus according to claim 4, wherein the metal material layer comprises at least one of gold, silver, chromium, copper, and aluminum, or the glass material layer comprises a chalcogenide glass material, and optionally the dielectric material layer comprises an oxide material and / or a nitride material.

6. The apparatus according to any one of claims 1 to 5, wherein at least one or each of the plurality of first and second nanostructures includes a plurality of holes, a plurality of slits, a plurality of grooves and / or a plurality of protrusions.

7. The apparatus according to any one of claims 1 to 6, wherein the plurality of first and / or second nanostructures are arranged in a periodic arrangement.

8. The apparatus according to any one of claims 1 to 7, wherein the first transmission wavelength depends on the dimensions of each of the plurality of first nanostructures and / or the periodicity of the plurality of first nanostructures.

9. The apparatus of claim 8, wherein the second transmission wavelength depends on the dimensions and / or periodicity of each of the plurality of second nanostructures, and optionally, the dimensions and / or periodicity of each of the plurality of second nanostructures are different from the dimensions and / or periodicity of each of the plurality of first nanostructures.

10. The apparatus according to any one of claims 1 to 9, wherein each of the at least one first filter element and the at least one second filter element includes or defines an electromagnetic metasurface.

11. The device includes at least one window or opening, The at least one window or opening is positioned adjacent to at least one of the at least one first filter element and the at least one second filter element, The at least one first filter element, the at least one second filter element, and / or the at least one window or opening are arranged alternately. The at least one first filter element, the at least one second filter element, and / or the at least one window are arranged to form a mosaic arrangement, a random arrangement, or a semi-random arrangement. The apparatus according to any one of claims 1 to 10, wherein the apparatus is at least one of the following.

12. A method for generating an image acquired by an imaging system, The aforementioned imaging system is: An image sensor including a pixel array, The optical filter apparatus according to any one of claims 1 to 11 and Includes, The at least one first filter element is associated with at least one first pixel of the pixel array, and the at least one second filter element is associated with at least one second pixel of the pixel array. The aforementioned method, Receiving data representing a first signal detected by at least one first pixel, Receiving data representing a second signal detected by at least one second pixel, Selecting at least one of the first signal and the second signal to generate the aforementioned image, The image is generated using at least one of the selected first signal and second signal, The image may be displayed at will. Includes, The aforementioned image includes a filtered image, and the method is described.

13. The at least one window or aperture is associated with at least one third pixel of the pixel array, or the pixel array includes another pixel configured to detect unfiltered light or radiation. The aforementioned method, Receiving data representing a third signal detected by at least one third pixel or the other pixels, Selecting the third signal to generate an unfiltered image, Using the third signal described above to generate the unfiltered image, The option to display the unfiltered image and The method of claim 12, including the method of claim 12.

14. An imaging system, An image sensor including a pixel array, The optical filter apparatus according to any one of claims 1 to 11 and Includes, An imaging system in which the at least one first filter element is associated with at least one first pixel of the pixel array, and the at least one second filter element is associated with at least one second pixel of the pixel array.

15. The system according to claim 14, wherein the optical filter device is positioned relative to the pixel array so as to pass through the at least one first filter element and / or the at least one second filter element before the light or radiation detected by the image sensor is incident on the at least one first pixel and / or the at least one second pixel of the pixel array.

16. The system according to claim 14 or 15, wherein the at least one window or opening is associated with at least one third pixel of the pixel array.

17. The system according to any one of claims 14 to 16, wherein the system includes a processing device configured to perform the method described in claim 12 or 13.

18. A computer program that includes an instruction causing a processing device to perform the method according to claim 12 or 13 when the program is executed by the system according to any one of claims 14 to 16.

19. A method for manufacturing an optical filter device for use with an image sensor, Forming at least one first filter element comprising multiple first nanostructures, Forming at least one second filter element comprising multiple second nanostructures and Includes, A method comprising the plurality of first nanostructures configured such that at least one first filter element includes a first transmission wavelength, and the plurality of second nanostructures configured such that at least one second filter element includes a second transmission wavelength different from the first transmission wavelength.

20. A method for manufacturing an imaging system, To provide an image sensor including a pixel array, To provide an optical filter device according to any one of claims 1 to 11, The optical filter device is attached to the image sensor such that at least one first filter element is associated with at least one first pixel of the pixel array, and at least one second filter element is associated with at least one second pixel of the pixel array. Methods that include...

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