WO2023025327A1 - 一种大口径红外超透镜相机 - Google Patents

一种大口径红外超透镜相机 Download PDF

Info

Publication number
WO2023025327A1
WO2023025327A1 PCT/CN2022/120548 CN2022120548W WO2023025327A1 WO 2023025327 A1 WO2023025327 A1 WO 2023025327A1 CN 2022120548 W CN2022120548 W CN 2022120548W WO 2023025327 A1 WO2023025327 A1 WO 2023025327A1
Authority
WO
WIPO (PCT)
Prior art keywords
aperture
superlens
infrared
lens
diameter
Prior art date
Application number
PCT/CN2022/120548
Other languages
English (en)
French (fr)
Inventor
易飞
侯铭铭
陈岩
李林翰
Original Assignee
华中科技大学
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 华中科技大学 filed Critical 华中科技大学
Priority to US18/024,982 priority Critical patent/US11815665B2/en
Publication of WO2023025327A1 publication Critical patent/WO2023025327A1/zh

Links

Images

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B13/00—Optical objectives specially designed for the purposes specified below
    • G02B13/001—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras
    • G02B13/008—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras designed for infrared light
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
    • H04N23/50—Constructional details
    • H04N23/55—Optical parts specially adapted for electronic image sensors; Mounting thereof
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/002—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of materials engineered to provide properties not available in nature, e.g. metamaterials
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
    • H04N23/20—Cameras or camera modules comprising electronic image sensors; Control thereof for generating image signals from infrared radiation only
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
    • H04N23/50—Constructional details
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
    • H04N23/50—Constructional details
    • H04N23/51—Housings
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
    • H04N23/50—Constructional details
    • H04N23/52—Elements optimising image sensor operation, e.g. for electromagnetic interference [EMI] protection or temperature control by heat transfer or cooling elements
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
    • H04N23/50—Constructional details
    • H04N23/54—Mounting of pick-up tubes, electronic image sensors, deviation or focusing coils
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/30—Transforming light or analogous information into electric information
    • H04N5/33—Transforming infrared radiation

Definitions

  • the invention belongs to the technical field of infrared imaging and micro-nano photonics, and more specifically relates to a large-aperture infrared super-lens camera.
  • Infrared imaging technology is a technology that obtains the thermal radiation information of the target object and converts it into an image visible to the human eye. Compared with visible light imaging technology, this imaging technology has the advantages of strong concealment, anti-interference ability, and good environmental adaptability, so it is widely used in military fields such as night reconnaissance, infrared guidance, and missile early warning, as well as security monitoring, vehicle-mounted night vision, and industrial inspection. and other civilian fields.
  • infrared imaging technology is increasingly used in airborne, mobile and other occasions that are sensitive to equipment weight, volume and cost, light, compact and low-cost infrared cameras have become a research and development hotspot.
  • infrared cameras are also pursuing a larger focal length and magnification in a limited space, so as to obtain a significantly larger operating distance, hoping to identify farther target objects and further exploit the advantages of infrared imaging technology.
  • lighter and farther are the two major development trends of infrared imaging technology at present.
  • an electromagnetic metasurface is a two-dimensional array of sub-wavelength or wavelength-scale electromagnetic resonance units; from a functional point of view, it can regulate parameters such as the intensity, frequency, phase, and polarization of electromagnetic waves in the entire electromagnetic spectrum.
  • Electromagnetic metasurface-based imaging technology (metalens) is one of its branches.
  • the structure is lighter, the cost is lower, and it is more suitable for plane processing technology. Therefore, it has broad application prospects. If the metalens is used for infrared imaging , it is beneficial to reduce the weight, volume and cost of the infrared camera.
  • the caliber of the current infrared hyperlens camera is limited, and its focal length and magnification will also be limited under the condition that the F number of the hyperlens is guaranteed to meet the image signal-to-noise ratio, so the imaging distance (or The working distance) is also limited, which means that the current infrared super-lens camera cannot take into account the two goals of "lighter” and “further”, and there is a contradiction between weight and imaging distance (or working distance).
  • the present invention provides a large-aperture infrared super-lens camera, thereby solving the technical problems of the current infrared super-lens camera with small focal length, low magnification, and insufficient imaging distance.
  • a large-diameter infrared superlens camera including a large-diameter superlens, an infrared focal plane array detector, a superlens mechanical assembly and a housing;
  • the large-diameter superlens is arranged on the superlens mechanical assembly, and the superlens mechanical assembly is assembled on the housing, and the housing is provided with a telescopic member that can move axially along the mirror surface of the large-diameter superlens;
  • the metalens mechanical assembly is used to fix the large-diameter metalens
  • the telescopic member is used to move the large-diameter superlens along its mirror axis, so that the distance between the large-diameter superlens and the infrared focal plane array detector is greater than 30 mm;
  • the large-diameter metalens is used to bend the thermal radiation of the target object and focus it on the surface of the infrared focal plane array detector, and its diameter is greater than 50mm and its thickness is less than 2mm;
  • the infrared focal plane array detector is used to eliminate stray light and light outside the detection wavelength band, so as to realize detection and imaging.
  • the large-aperture metalens includes a metasurface microstructure array, a microstructure array thin-film coating, a base, and a base thin-film coating;
  • the thin-film coating of the microstructure array is coated on the surface of the metasurface microstructure array for antireflection of incident light, and its surface shape is the same as that of the metasurface microstructure array;
  • the base film coating is coated on the surface of the base for antireflection of incident light
  • the metasurface microstructure array is located on the rear surface of the substrate, wherein the rear surface of the substrate is the side along the incident light direction, where the light arrives later.
  • the metasurface microstructure array includes a plurality of columnar structural units arranged according to an ordered lattice period, wherein the heights of the columnar structural units are all the same, and are on the order of the detected wavelength; the columnar structure The diameter of the unit is in the order of subwavelength;
  • the period of the array composed of the columnar structural units is less than 10 microns, and the diameter of the array composed of the columnar structural units is equal to the aperture of the large-aperture metalens.
  • the material of the columnar structure unit includes silicon or germanium; the material of the microstructure array film coating includes zinc sulfide or germanium; the material of the substrate includes intrinsic double-thrown silicon, zinc sulfide or barium fluoride; The material of the base film coating includes zinc sulfide or germanium.
  • the caliber and F number of the large-aperture metalens are determined according to the following formula:
  • C is the pixel density of the target object in the detection image
  • L is the distance of the target object from the large-aperture infrared superlens camera
  • D is the aperture of the large-aperture superlens
  • F is the distance of the large-aperture superlens F number
  • P is the pixel pitch of the infrared focal plane array detector
  • C d is the minimum pixel density of the required target object in the detection image
  • SNR is the camera detection signal-to-noise ratio
  • K is the radiation degree of the target object
  • SNR d is the minimum required camera signal-to-noise ratio.
  • the metasurface microstructure array (101) is designed by the following method:
  • the surface phase distribution of the large-aperture metalens and the relationship between the phase and transmittance of the columnar structure unit and the size of the columnar structure unit determine the size of the columnar structure unit at each position in the metasurface microstructure array, And again use the diffraction design algorithm or the ray tracing algorithm for feedback optimization; wherein, the infrared transmittance of the columnar structural unit is greater than the required value of the infrared transmittance;
  • the thin film coating of the microstructure array is optimally designed through an electromagnetic field simulation algorithm according to the shape of the metasurface microstructure array;
  • the substrate is optimally designed by using a finite difference time domain method and a ray tracing method.
  • the metasurface microstructure array is prepared by semiconductor technology, including but not limited to stepping photolithography, step-scanning photolithography, nanoimprinting, laser direct writing, metal lift-off or ICP etching.
  • microstructure array thin film coating and the base thin film coating are prepared by an optical coating process, including but not limited to electron beam evaporation coating;
  • the substrate is processed by optical polishing.
  • the infrared focal plane array detector includes a detector window and an infrared focal plane array, and the detector window and the infrared focal plane array are sequentially arranged along the direction of incident light;
  • the detector window is used to filter out stray light and light outside the detection band
  • the infrared focal plane array is used for detecting and imaging the focused light.
  • the mechanical assembly of the superlens includes a buffer structure, the buffer structure is provided with a groove matching the edge of the large-diameter superlens, and the groove is provided for fixing the large-diameter superlens.
  • the material of the mechanical damping element includes but not limited to rubber, composite material or high damping alloy.
  • the contact surfaces of the housing, the metalens mechanical assembly and the infrared focal plane array detector are respectively provided with sealing gaskets;
  • the shell is provided with a thermal insulation coating, and the material of the thermal insulation coating includes but not limited to metal oxide fine powder or non-metallic hollow microspheres.
  • the large-diameter infrared superlens camera proposed by the present invention wherein the aperture of the large-diameter superlens is greater than 50mm, and the focal length is greater than 30mm.
  • the weight of the large-diameter superlens is kept very small, the magnification and imaging distance are greatly improved, overcoming the In the past, the problems of short focal length and small magnification of metalens cameras can detect and image medium and long-distance objects.
  • the present invention further obtains the method of determining the aperture and F number of the large-diameter super-lens according to the system parameters, better taking into account the two goals of "lighter” and “further”, and solves the contradiction between weight and imaging distance (or operating distance) .
  • the large-diameter infrared superlens camera proposed by the present invention does not need to complicatedly calculate the strict electromagnetic field of the whole large-diameter superlens in design technology, but divides the design of the large-diameter superlens into surface phase distribution design and local phase design (i.e. Phase design of columnar structural unit), only need to calculate the strict electromagnetic field of the columnar structural unit and the diffraction field or light field of the surface phase distribution, which greatly reduces the calculation scale and improves the design efficiency; in the simulation feedback optimization link, the diffraction algorithm is also introduced Or the ray tracing algorithm replaces the strict electromagnetic field algorithm, which further improves the calculation accuracy and improves the optimization efficiency.
  • the large-aperture infrared superlens camera proposed by the present invention uses stepping lithography, step-by-step scanning lithography, nanoimprinting or laser direct writing and other high-yield and large-area patterning processes to replace small-area electron beam exposure and
  • the ultraviolet projection lithography process expands the coverage area of the patterning process, increases the speed of patterning, and enables large-aperture metalens to be produced in large quantities.
  • the large-diameter super-lens camera proposed by the present invention, the large-diameter super-lens is coated with an anti-reflection film on both sides, which improves the transmittance of the super-lens; the mechanical assembly of the super-lens adopts a buffer structure, which can fix and adjust the super-lens With anti-shock protection, it avoids the poor mechanical performance of previous metalens cameras.
  • the casing of the large-aperture infrared super-lens camera proposed by the present invention adopts heat-insulating coating and sealing treatment, which can protect the lens from heat-insulation and waterproof, so that the lens has better athermalization and waterproof performance.
  • Fig. 1 is a schematic structural view of a large-aperture infrared super-lens camera proposed by an embodiment of the present invention
  • Fig. 2 is a structural schematic diagram of a large-aperture metalens proposed by an embodiment of the present invention
  • FIG. 3 is a schematic diagram of a columnar structural unit and a base in the form of a hexagonal lattice proposed by an embodiment of the present invention
  • Figure 4 is a top view of a columnar structural unit and a base in the form of a hexagonal lattice provided by an embodiment of the present invention
  • Fig. 5 is the surface phase distribution of the large aperture metalens provided by the embodiment of the present invention.
  • Fig. 6 is the phase and transmittance obtained under different diameters of the columnar structural unit provided by the embodiment of the present invention.
  • FIG. 7 is a top view of a large-area metasurface microstructure array in a large-aperture metalens designed according to an embodiment of the present invention
  • Figure 8 is a partial top view of the large-area metasurface microstructure array prepared by the process provided by the embodiment of the present invention.
  • Fig. 9 is a partial oblique view of the large-area metasurface microstructure array prepared by the process provided by the embodiment of the present invention.
  • Fig. 10 is a schematic diagram of four large-aperture superlenses 1 on a 6-inch silicon wafer prepared by the process provided by the embodiment of the present invention
  • Fig. 11 is a schematic structural view of a metalens mechanical assembly provided by an embodiment of the present invention.
  • Fig. 12 is a schematic structural diagram of a housing provided by an embodiment of the present invention.
  • Fig. 13 is a sample photo of the large-aperture metalens provided by the embodiment of the present invention.
  • Fig. 14 is a schematic diagram showing the comparison between the indoor 50m long-distance imaging experiment results and the recognition effect of the visible light short-focus lens provided by the embodiment of the present invention.
  • the present invention provides a large-diameter infrared superlens camera, including a large-diameter superlens 1 and an infrared focal plane array detector 2 placed in sequence along the incident light direction, and a superlens mechanical assembly 3 with shell4;
  • the large-diameter superlens 1 is used to bend light rays from the thermal radiation of the target object, and its diameter is greater than 50 mm, and its thickness is less than 2 mm; by using a small-thick large-diameter super-lens 1 for imaging, while maintaining the large-diameter super-lens 1 Under the premise of very small weight, the camera magnification and imaging distance are greatly improved, which overcomes the problems of short focal length and small magnification of previous super-lens cameras, and can detect and image medium and long-distance objects.
  • the caliber and F number of the large-aperture metalens 1 are determined according to the following formula:
  • C is the pixel density of the target object in the detection image
  • L is the distance between the target object and the above-mentioned large-diameter infrared superlens camera
  • D is the aperture of the above-mentioned large-diameter superlens
  • F is the F number of the above-mentioned large-diameter superlens
  • P is the pixel pitch of the above infrared focal plane array detector
  • C d is the minimum pixel density of the required target object in the detection image
  • SNR is the camera detection signal-to-noise ratio
  • K is the radiation degree of the target object, the detection environment, Parameters related to lens transmittance and detector responsivity
  • SNR d is the minimum required camera signal-to-noise ratio.
  • the above determination criteria take into account the weight parameters of the camera (the aperture and F number of the large-aperture super-lens) and the imaging distance parameter (the distance between the target object and the above-mentioned large-aperture infrared super-lens camera), which can better balance “lighter” and The two goals of "further” solve the contradiction between weight and imaging distance (or working distance).
  • the large-aperture metalens 1 includes a metasurface microstructure array 101, a microstructure array film coating 102 covering the metasurface microstructure array 101, a substrate 103, and a base film coating covering the substrate 103 104;
  • the metasurface microstructure array 101 is located on the rear surface of the above-mentioned substrate 103, wherein the rear surface of the above-mentioned substrate 103 is along the incident light direction, the side that the light arrives after;
  • the metasurface microstructure array 101 is composed of a series of columnar structural units 1011 are arranged according to the ordered lattice period, wherein, the heights of the above-mentioned columnar structural units 1011 are all the same, and are in the order of the detected wavelength, and the diameter of the above-mentioned columnar structural units 1011 is in the order of sub-wavelength.
  • the period of the array formed by the structural units 1011 is less than 10 microns, and the diameter of the array formed by the columnar structural units 1011 is equal to the aperture of the large aperture metalens 1, and the material of the columnar structural units 1011 is an infrared high refractive index material, including but Not limited to silicon, germanium, etc.;
  • the microstructure array thin film coating 102 covering the metasurface microstructure array is used for anti-reflection of incident light, and its surface shape follows the shape of the metasurface microstructure array 101, including but not limited to zinc sulfide , germanium coating;
  • the substrate 103 is made of a material highly transparent to infrared light, including but not limited to intrinsic double-polished silicon, zinc sulfide, barium fluoride, etc.;
  • the base film covering the substrate is coated with 104 layers for the enhancement of incident light Penetration, including but not limited to zinc sulfide, germanium coating.
  • the large-aperture superlens 1 is coated with an anti-reflection coating on both sides, which improves the transmittance of the camera.
  • the metasurface microstructure array 101 is designed as follows: according to the caliber and F number of the large-aperture metalens 1, use a diffraction design algorithm or a ray tracing algorithm to optimize the design of the large-aperture metalens 1 surface phase distribution. According to the strict electromagnetic field numerical algorithm, the relationship between the phase and transmittance of the columnar structural unit 1011 and the size of the columnar structural unit 1011 is obtained. According to the surface phase distribution of the large-aperture metalens 1, and the relationship between the phase and transmittance of the columnar structural unit 1011 and the size of the columnar structural unit 1011, determine the columnar structure at each position in the metasurface microstructure array 101.
  • the size of the structural unit 1011 is further optimized by using a diffraction design algorithm or a ray tracing algorithm.
  • the infrared transmittance of the columnar structural unit 1011 is greater than the required value of the infrared transmittance;
  • the microstructure array film coating 102 covering the metasurface microstructure array is simulated by electromagnetic field according to the shape of the metasurface microstructure array 101.
  • the base 103 is optimally designed by using the time domain finite difference method and ray tracing method.
  • the above design method does not require complex calculation of the strict electromagnetic field of the entire large-aperture metalens, but divides the design of the large-aperture metalens into surface phase distribution design and local phase design (that is, the phase design of the columnar structural unit), and only needs to calculate the columnar structure
  • the strict electromagnetic field of the unit and the diffraction field or ray field of the surface phase distribution greatly reduce the calculation scale and improve the design efficiency; in the simulation feedback optimization link, the diffraction algorithm or ray tracing algorithm is also introduced to replace the strict electromagnetic field algorithm, which further improves the Calculation accuracy improves optimization efficiency.
  • the metasurface microstructure array 101 is prepared by a large-area semiconductor process, including but not limited to stepping photolithography, step-by-step scanning photolithography, nanoimprinting, laser direct writing, metal lift-off , ICP etching, etc.; the microstructure array film coating 102 covering the metasurface microstructure array and the base film coating 104 covering the substrate 103 are prepared by an optical coating process, including but not limited to electron beam evaporation coating; the substrate 103 is optically polished deal with.
  • high-yield large-area patterning processes such as stepping lithography, step-by-step scanning lithography, nanoimprinting or laser direct writing are used to replace small-area electron beam exposure and ultraviolet projection lithography processes, expanding The coverage area of the patterning process is increased, the speed of patterning is increased, and large-aperture metalens can be prepared in large quantities.
  • the infrared focal plane array detector 2 is used to eliminate stray light and light outside the detection wavelength band, so as to realize detection and imaging.
  • the infrared focal plane array detector 1 includes a detector window and an infrared focal plane array arranged in sequence along the incident light direction; the detector window is used to filter out stray light and detection bands of the system the external light; the infrared focal plane array is used to detect and image the focused light.
  • the metalens mechanical assembly 3 is used to fix, adjust and protect the large-aperture metalens 1 against shocks.
  • the super lens mechanical assembly 3 is provided with a buffer structure 301, wherein the buffer structure 301 adopts a mechanical damping element 3011, and the material of the mechanical damping element 3011 includes but is not limited to rubber, composite material, high damping alloy, etc.;
  • the buffer structure 301 has a groove 3012 matching the edge of the large-diameter superlens 1, which can clamp the large-diameter superlens 1 and fix it and protect it against shocks;
  • the superlens mechanical assembly 3 is fixedly connected with the housing 4, and the housing 4 can pass through The telescopic member 5 expands and contracts, so that the superlens mechanical assembly 3 cooperates with the housing 4 to adjust the large-diameter superlens 1 .
  • the superlens mechanical assembly 3 is provided with a buffer structure 301, which can fix, adjust and protect the large-aperture super
  • the housing 4 is used for thermal insulation and waterproof protection of the lens.
  • the shell 4 is sealed with a heat-insulating coating 6.
  • the material of the heat-insulating coating 6 includes, but is not limited to, metal oxide micropowder, non-metallic hollow microspheres, etc., and the sealing process includes, but is not limited to, the use of sealing gaskets at the joints of the shell. 401.
  • the shell 4 enables the lens to have better athermalization and waterproof performance.
  • the distance between the large-aperture metalens 1 and the infrared focal plane array detector 2 is greater than 30mm.
  • the invention provides a large-diameter infrared super-lens camera, which improves the design efficiency of the large-diameter super-lens in terms of design technology; in terms of preparation technology, the large-diameter super-lens can be prepared in large quantities; thus the caliber of the large-diameter super-lens It can be greater than 50mm, and the focal length can be greater than 30mm.
  • the magnification and imaging distance are greatly improved, which solves the technical problems of small focal length, low magnification and insufficient imaging distance of the current infrared super-lens camera .
  • the invention maintains the advantages of the ultra-lens being light and thin (thickness less than 2mm) and can be mass-produced, making the camera light, compact and low-cost, greatly reducing the weight, volume and cost of the medium and long-distance infrared camera, and can be used for medium and long-distance detection Imaging, border security, medium and long-distance thermal sensing, smart home, intelligent environment perception and other occasions.
  • FIG. 1 it is a kind of large-diameter infrared superlens camera proposed by the present invention, comprising: large-diameter superlens 1, infrared focal plane array detector 2, superlens mechanical assembly 3, shell 4, telescopic member 5 and partition Thermal coating6.
  • the large-aperture metalens 1 is used to bend light rays from the thermal radiation of the target object, and its thickness is 0.5 mm; the aperture and F number of the large-aperture metalens 1 are further selected according to the following formula:
  • C is the pixel density of the target object in the detection image
  • L is the distance between the target object and the above-mentioned large-diameter infrared superlens camera
  • D is the aperture of the above-mentioned large-diameter superlens
  • F is the F number of the above-mentioned large-diameter superlens
  • P is the pixel pitch of the above infrared focal plane array detector
  • C d is the minimum pixel density of the required target object in the detection image
  • SNR is the camera detection signal-to-noise ratio
  • K is the radiation degree of the target object, the detection environment, Parameters related to lens transmittance and detector responsivity
  • SNR d is the minimum required camera signal-to-noise ratio.
  • F 1
  • P 17 ⁇ m
  • D 50.2mm
  • C 59m -1 >C d .
  • the large-aperture metalens has a diameter of 50.2 mm and an F-number of 1, which can simultaneously meet the requirements of the signal-to-noise ratio and imaging distance (not less than 50 meters) of this embodiment.
  • the above-mentioned determination criteria ensure that the appropriate parameters are selected under the required target parameters, and the weight parameters of the camera (the caliber and F number of the large-aperture super-lens) and the imaging distance parameter (the distance between the target object and the above-mentioned large-aperture infrared super-lens camera) are taken into account. ), which can better balance the two goals of "lighter” and “longer”, and solve the contradiction between weight and imaging distance (or working distance).
  • the specific structure of the large-aperture metalens in this embodiment is as shown in Figure 2, including a metasurface microstructure array 101, a microstructure array film coating 102 covering the metasurface microstructure array 101, a substrate 103 and a covering Base film coating 104 of base 103 .
  • the metasurface microstructure array 101 is located on the rear surface of the substrate 103 , wherein the rear surface of the substrate 103 is the side along the incident light direction that the light reaches later.
  • the metasurface microstructure array 101 is formed by a series of columnar structural units 1011 arranged in a hexagonal lattice period.
  • the heights of the columnar structural units 1011 are all the same and are on the order of the detected wavelength, the diameter of the columnar structural units 1011 is on the order of sub-wavelength, and the array period formed by the columnar structural units 1011 is less than 10 microns, the diameter of the array composed of the columnar structural units 1011 is equal to the aperture D of the large-aperture metalens 1 .
  • the working band is long-wave infrared, so the material of the columnar structural unit 1011 is intrinsic silicon.
  • the microstructure array thin film coating 102 covering the metasurface microstructure array 101 is used for anti-reflection of incident light, and its surface shape follows the shape of the metasurface microstructure array 101, using alternating coatings of zinc sulfide and germanium;
  • the substrate 103 is an intrinsic double-polished silicon wafer; the substrate film coating 104 covering the substrate 103 is used for anti-reflection of incident light, and alternate coatings of zinc sulfide and germanium are used.
  • the large-aperture super-lens 1 is coated with an anti-reflection film on both sides, which can increase the transmittance of the camera to more than 80% in theory.
  • the finite difference time domain algorithm a commonly used strict electromagnetic field numerical algorithm
  • the relationship between the phase and transmittance of the columnar structural unit 1011 and the size of the columnar structural unit 1011 (the diameter of the cylinder in this embodiment) is obtained.
  • the surface phase distribution of the above-mentioned large-aperture metalens 1 determines the columnar structure at each position in the above-mentioned large-area metasurface microstructure array 101
  • the size of the unit 1011 is further optimized by using the diffraction design algorithm. Specifically, the phase and transmittance of the columnar structure unit 1011 are substituted into the diffraction design algorithm, so that the simulation can reflect the optical performance of the metasurface microstructure array 101 .
  • the infrared transmittance of the above-mentioned columnar structural unit 1011 is greater than the required value of the infrared transmittance; the microstructure array film coating 102 covering the metasurface microstructure array 101 passes through a limited
  • the time domain difference algorithm is used for optimal design; the thickness of the substrate 103 is optimized for design using a ray tracing method.
  • Fig. 5 is the surface phase distribution of the large-aperture metalens 1 that is finally designed.
  • the height of the columnar structural unit 1011 is selected as 6 ⁇ m, and the period is 4 ⁇ m.
  • Fig. 6 shows the phase and transmittance of the columnar structural unit 1011. The relationship between the diameters of the structural units 1011 , FIG.
  • FIG. 7 is a top view of the metasurface microstructure array 101 in the designed large-aperture metalens 1 . All simulation designs are completed on a common computer, which verifies the high simulation design efficiency of the present invention for the large-aperture metalens 1 .
  • the metasurface microstructure array 101 is prepared by a large-area semiconductor process.
  • two processes stepping photolithography and ICP etching, are mainly used, and the stepping photolithography uses 9 masks. version, divided into 9 steps of photolithography, so that 9 exposure areas are spliced into an exposure area of a large-aperture metalens 1, and the photoresist pattern of the metasurface microstructure array 101 is produced; the ICP etching adopts the Bosch process to step
  • the photoresist pattern produced by conventional photolithography is used as an etching mask to obtain a metasurface microstructure array 101 with a high aspect ratio.
  • FIG. 9 are partial plan view and oblique view respectively of the metasurface microstructure array 101 manufactured according to the above process.
  • the microstructure array film coating 102 covering the metasurface microstructure array 101 and the base film coating 104 covering the substrate 103 are prepared by an optical coating process.
  • electron beam evaporation coating is adopted; the substrate is an intrinsic double-polished wafer, and both sides are polished.
  • FIG. 10 shows four large-diameter metalens 1 fabricated on a 6-inch silicon wafer, which verifies that the large-diameter metalens 1 of the present invention can be mass-produced on silicon wafers.
  • the infrared focal plane array detector 2 is used to eliminate stray light and light outside the detection wavelength band, so as to realize detection and imaging.
  • the infrared focal plane array detector 2 includes a detector window and an infrared focal plane array arranged in sequence along the incident light direction; the detector window is used to filter out the stray light of the system and the light outside the detection band; the infrared focal plane array It is used to detect and image the focused light.
  • the technical specifications of the infrared focal plane array detector 2 used in this embodiment are as follows: the working band is 8-14 ⁇ m; the pixel size is 17 ⁇ m; the array resolution is 1280 ⁇ 960.
  • the metalens mechanical assembly 3 is used to fix, adjust and protect the large-diameter metalens 1 against shocks.
  • the metalens mechanical assembly 3 includes a buffer structure 301 , wherein the buffer structure 301 is provided with a mechanical damping element 3011 .
  • the mechanical damping element 3011 is made of rubber; the buffer structure 301 has a groove 3012 matching the edge of the superlens, which can clamp the large-diameter superlens 1 and fix it and protect it against shocks.
  • the superlens mechanical assembly 3 is fixedly connected with the housing 4, and the housing 4 can be stretched through the telescopic member 5, so that the superlens mechanical assembly 3 and the housing 4 can be matched to adjust the superlens.
  • the housing 4 is used for thermal insulation and waterproof protection of the lens.
  • the shell 4 is sealed with a thermal insulation coating 6.
  • the material of the thermal insulation coating 6 is a composite emulsion
  • the filler is ultrafine hollow microspheres, metal oxide micropowder and titanium dioxide.
  • the sealing process in this embodiment is to use a sealing gasket 401 at the joint of the casing 4 .
  • the distance between the large-aperture metalens 1 and the infrared focal plane array detector 2 is greater than 30mm. This distance is 50mm in this embodiment.
  • Fig. 13 is a sample photo of the large-aperture superlens 1 of the present embodiment, which verifies the superlens aperture of the present invention Greater than 50mm.
  • the weight of the large-aperture metalens of this embodiment is only 3.7 grams as measured by an electronic weighing instrument.
  • the results of the indoor 50m long-distance imaging experiment show that the long-distance recognition can be performed on the 50m-distance target (arrow), as shown in Figure 14.
  • the embodiment of the present invention better balances the two goals of "lighter” and "longer”, and solves the contradiction between weight and imaging distance (or working distance).

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Electromagnetism (AREA)
  • Photometry And Measurement Of Optical Pulse Characteristics (AREA)
  • Lenses (AREA)

Abstract

本发明公开了一种大口径红外超透镜相机，属于红外成像与微纳光子学技术领域，包括大口径超透镜、红外焦平面阵列探测器、超透镜机械组装件和外壳，大口径超透镜的口径大于50mm，厚度小于2mm，大口径超透镜与红外焦平面阵列探测器的距离大于30mm；超透镜机械组装件采用缓冲结构对超透镜进行固定、调节与抗震保护；外壳采用隔热涂层并密封处理，对镜头进行隔热与防水保护。本发明采用严格电磁场数值、衍射设计算法与大面积半导体工艺制备方法，将超透镜的口径提升至50mm以上，在保证超透镜F数满足图像信噪比的要求下，大大提高了相机的焦距与放大率，克服了以往超透镜相机焦距短、放大率小、成像距离不够的问题，能对中远距离物体进行探测成像。

Description

一种大口径红外超透镜相机 【技术领域】
本发明属于红外成像与微纳光子学技术领域，更具体地，涉及一种大口径红外超透镜相机。
【背景技术】
红外成像技术是一种通过获取目标物体热辐射分别信息并将其转换为人眼可见图像的技术。该成像技术相比可见光成像技术，具有隐蔽性与抗干扰能力强、环境适应性好的优势，因此广泛引用于夜间侦查、红外制导、导弹预警等军事领域和安防监控、车载夜视、工业检测等民用领域。
近年来，随着红外成像技术越来越多地应用于机载、移动端等对设备重量、体积和成本敏感的场合、轻型、紧凑和低成本的红外相机成为研发热点。另一方面，红外相机也在有限的空间内，追求着更大的焦距与放大率，从而显著获得更大的作用距离，希望能识别更远的目标物体，进一步发挥红外成像技术的优势。综合来看，更轻、更远是目前红外成像技术的两大发展趋势。
然而，传统透镜由于依靠元件的曲面外形及其材料的光学特性实现对光的波前调控，难以将红外相机的重量、体积和成本进一步减小。电磁超表面作为纳米光子学领域中一个新颖的研究方向，则有望替代传统透镜，实现红外相机的“更轻”目标。从结构上讲，电磁超表面是亚波长或波长尺度电磁谐振单元的二维阵列；从功能上讲，它可以在整个电磁波谱范围内调控电磁波的强度、频率、相位、偏振等参量。基于电磁超表面的成像技术(超透镜)作为其中的一个分支，相比传统光学元件，结构轻便、成本低廉、更加适应平面加工工艺，因此具有广阔的应用前景，若把超透镜用于红外成像，则有利于减小红外相机的重量、体积和成本。
不幸的是，目前红外超透镜相机不能同时实现“更轻”与“更远”两大目标，其存在以下问题：
(1)目前的红外超透镜相机设计技术中，几乎不可能设计口径大于50mm的红外超透镜。目前普遍采用严格电磁场数值算法(如有限时域差分算法)来仿真红外超透镜的聚焦光斑，以此作为红外超透镜设计的依据。然而，当红外超透镜口径增大到50mm时需要成百上千万个柱状结构单元，这样大规模的仿真模型几乎不可能在一般的工程设计计算机上用可接受的时间成本来完成运行。
(2)目前的红外超透镜相机制备工艺中，制备口径大于50mm的红外超透镜是一个难题。目前在图形化工艺中普遍采用电子束曝光或紫外投影式光刻来制备红外超透镜。然而，电子束曝光是逐点曝光工艺，无法以可接受的尺寸精度与时间成本完成成百上千万个柱状结构单元的图形化；紫外投影式光刻虽然可以保证较高的产率，但受限于投影镜头的视场，紫外投影式光刻一次曝光的面积是有限的(通常为20mm*20mm)，不能覆盖大口径超透镜需要的曝光区域(至少为50mm*50mm)。
(3)结合以上两点，目前红外超透镜相机的口径是有限的，在保证超透镜F数满足图像信噪比的要求下，其焦距和放大率也将是有限的，因此成像距离(或作用距离)也就是有限的，这意味着目前红外超透镜相机不能兼顾“更轻”与“更远”两大目标，重量与成像距离(或作用距离)存在矛盾。
【发明内容】
针对现有技术的以上缺陷或改进需求，本发明提供了一种大口径红外超透镜相机，由此解决目前红外超透镜相机焦距小、放大率低、成像距离不够的技术问题。
为实现上述目的，按照本发明的一个方面，提供了一种大口径红外超透镜相机，包括大口径超透镜、红外焦平面阵列探测器、超透镜机械组装件和外壳；
所述大口径超透镜设置于所述超透镜机械组装件，所述超透镜机械组装件装配于所述外壳，所述外壳设有可使其沿大口径超透镜镜面轴向移动的伸缩构件；
所述超透镜机械组装件用于固定所述大口径超透镜；
所述伸缩构件用于使所述大口径超透镜沿其镜面轴向移动，以使所述大口径超透镜与所述红外焦平面阵列探测器之间的距离大于30mm；
所述大口径超透镜用于对目标物体的热辐射进行光线弯折并聚焦至所述红外焦平面阵列探测器表面，其口径大于50mm，厚度小于2mm；
所述红外焦平面阵列探测器用于消除杂散光和探测波段以外的光线，从而实现探测成像。
优选地，所述大口径超透镜包括超表面微结构阵列、微结构阵列薄膜涂层、基底和基底薄膜涂层；
所述微结构阵列薄膜涂层涂覆于所述超表面微结构阵列表面，用于对入射光的增透，其表面形状与所述超表面微结构阵列形状相同；
所述基底薄膜涂层涂覆于所述基底表面，用于对入射光的增透；
所述超表面微结构阵列位于所述基底的后表面，其中，所述基底的后表面为沿着入射光方向，光线后到达的一面。
优选地，所述超表面微结构阵列包括按照有序晶格周期排列多个柱状结构单元，其中，所述柱状结构单元的高度均相同，且介于所探测的波长量级；所述柱状结构单元的直径介于亚波长量级；
所述柱状结构单元所组成的阵列周期小于10微米，且所述柱状结构单元所组成的阵列直径等于所述大口径超透镜的口径。
优选地，所述柱状结构单元的材料包括硅或锗；所述微结构阵列薄膜涂层的材料包括硫化锌或锗；所述基底的材料包括本征双抛硅、硫化锌或氟化钡；所述基底薄膜涂层的材料包括硫化锌或锗。
优选地，所述大口径超透镜的口径与F数根据下式确定：
Figure PCTCN2022120548-appb-000001
Figure PCTCN2022120548-appb-000002
其中，C为目标物体在探测图像中的像素密度，L为目标物体离所述大口径红外超透镜相机的距离，D为所述大口径超透镜的口径，F为所述大口径超透镜的F数，P为所述红外焦平面阵列探测器的像元间距，C d为要求的目标物体在探测图像中的最小像素密度；SNR为相机探测信噪比，K为与目标物体辐射程度、探测环境、透镜透过率、探测器响应度相关的参数，SNR d为要求的最低相机信噪比。
优选地，所述超表面微结构阵列(101)通过以下方法设计：
根据所述大口径超透镜的口径与F数使用衍射设计算法或光线追迹算法，优化设计并获取所述大口径超透镜的表面相位分布；
获得所述柱状结构单元的相位及透过率与柱状结构单元尺寸的关系；
根据所述大口径超透镜的表面相位分布以及所述柱状结构单元的相位及透过率与柱状结构单元尺寸的关系，确定所述超表面微结构阵列中每个位置处柱状结构单元的尺寸，并再次用衍射设计算法或光线追迹算法加以反馈优化；其中，所述柱状结构单元的红外透过率大于红外透过率的需求值；
进一步优选地，所述微结构阵列薄膜涂层根据所述超表面微结构阵列形状，通过电磁场仿真算法进行优化设计；
进一步优选地，所述基底通过时域有限差分法与光线追迹法进行优化设计。
优选地，所述超表面微结构阵列采用半导体工艺制备，包括但不限于步进式光刻、分步扫描式光刻、纳米压印、激光直写、金属剥离或ICP刻蚀。
所述微结构阵列薄膜涂层与基底薄膜涂层采用光学镀膜工艺制备，包括但不限于电子束蒸发镀膜；
所述基底通过光学抛光处理。
优选地，所述红外焦平面阵列探测器包括探测器窗口和红外焦平面阵列，所述探测器窗口和红外焦平面阵列沿入射光方向依次设置；
所述探测器窗口用于滤除杂散光及探测波段外的光线；
所述红外焦平面阵列用于对聚焦后的光线进行探测成像。
优选地，所述超透镜机械组装件包括缓冲结构，所述缓冲结构设有与所述大口径超透镜边缘匹配的凹槽，所述凹槽内设有用于对所述大口径超透镜进行固定与抗震保护的机械阻尼件；
所述机械阻尼件的材料包括但不限于橡胶、复合材料或高阻尼合金。
优选地，所述外壳与所述超透镜机械组装件、红外焦平面阵列探测器的接触面分别设有密封垫圈；
所述外壳设有隔热涂层，所述隔热涂层的材料包括但不限于金属氧化物微粉或非金属空芯微珠。
总体而言，通过本发明所构思的以上技术方案与现有技术相比，能够取得下列有益效果：
1、本发明提出的大口径红外超透镜相机，其中大口径超透镜的口径大于50mm，焦距大于30mm，在保持大口径超透镜重量很小的前提下，放大率和成像距离大大提高，克服了以往超透镜相机焦距短、放大率小的问题，能对中远距离物体进行探测成像。本发明进一步得到大口径超透镜的口径与F数根据系统参数的确定方法，更好地兼顾“更轻”与“更远”两大目标，解决了重量与成像距离(或作用距离)的矛盾。
2、本发明提出的大口径红外超透镜相机在设计技术上无需复杂地计算整个大口径超透镜的严格电磁场，而是将大口径超透镜的设计分为表面相位分布设计与局部相位设计(即柱状结构单元的相位设计)，仅需计算柱 状结构单元的严格电磁场与表面相位分布的衍射场或光线场，大大减小了计算规模，提高了设计效率；在仿真反馈优化环节，亦引入衍射算法或光线追迹算法代替严格电磁场算法，进一步提高了计算准确度，提高了优化效率。
3、本发明提出的大口径红外超透镜相机用步进式光刻、分步扫描式光刻、纳米压印或激光直写等高产率大面积图形化工艺来代替小面积的电子束曝光与紫外投影式光刻工艺，拓展了图形化工艺的覆盖区域面积，增大了图形化的速度，使大口径超透镜可以大批量制备。
4、本发明提出的大口径红外超透镜相机中大口径超透镜双面镀增透膜，提高了超透镜的透过率；超透镜机械组装件采用缓冲结构，可对超透镜进行固定、调节与抗震保护，避免了以往超透镜相机较差的机械性能。
5、本发明提出的大口径红外超透镜相机中外壳采用隔热涂层并密封处理，可对镜头进行隔热与防水保护，使镜头具有更好的无热化与防水性能。
【附图说明】
图1是本发明实施例提出的大口径红外超透镜相机的结构示意图；
图2是本发明实施例提出的大口径超透镜的结构示意图；
图3是本发明实施例提出的一个柱状结构单元和一个六方晶格形式的基底示意图；
图4本发明实施例提供的一个柱状结构单元和一个六方晶格形式的基底俯视图；
图5是本发明实施例提供的大口径超透镜的表面相位分布；
图6是本发明实施例提供的柱状结构单元在不同直径下得到的相位和透过率；
图7是本发明实施例提供的设计所得的大口径超透镜中的大面积超表面微结构阵列的俯视图；
图8是本发明实施例提供的工艺制备所得的大面积超表面微结构阵列 的局部俯视图；
图9是本发明实施例提供的工艺制备所得的大面积超表面微结构阵列的局部斜视图；
图10是本发明实施例提供的工艺制备所得的1片6寸硅晶圆上的4个大口径超透镜1示意图；
图11是本发明实施例提供的超透镜机械组装件的结构示意图；
图12是本发明实施例提供的外壳的结构示意图；
图13是本发明实施例提供的大口径超透镜的样件照片；
图14是本发明实施例提供的室内50m远距离成像实验结果与可见光短焦镜头的识别效果对比示意图。
在所有附图中，相同的附图标记用来表示相同的元件或结构，其中：1-大口径超透镜；101-超表面微结构阵列；1011-柱状结构单元；102-微结构阵列薄膜涂层；103-基底；104-基底薄膜涂层；2-红外焦平面阵列探测器；3-超透镜机械组装件；301-缓冲结构；3011-机械阻尼件；3012-凹槽；4-外壳；401-密封垫圈；5-伸缩构件；6-隔热涂层。
【具体实施方式】
为了使本发明的目的、技术方案及优点更加清楚明白，以下结合附图及实施例，对本发明进行进一步详细说明。应当理解，此处所描述的具体实施例仅仅用以解释本发明，并不用于限定本发明。此外，下面所描述的本发明各个实施方式中所涉及到的技术特征只要彼此之间未构成冲突就可以相互组合。
如图1-14所示，本发明提供了一种大口径红外超透镜相机，包括沿入射光方向依次放置的大口径超透镜1和红外焦平面阵列探测器2，以及超透镜机械组装件3与外壳4；
其中，所述大口径超透镜1用于对目标物体的热辐射进行光线弯折，其口径大于50mm，厚度小于2mm；通过采用厚度小的大口径超透镜1进 行成像，在保持大口径超透镜1重量很小的前提下，相机放大率和成像距离大大提高，克服了以往超透镜相机焦距短、放大率小的问题，能对中远距离物体进行探测成像。优选地，大口径超透镜1的口径与F数根据下式确定：
Figure PCTCN2022120548-appb-000003
Figure PCTCN2022120548-appb-000004
式中，C为目标物体在探测图像中的像素密度，L为目标物体离上述大口径红外超透镜相机的距离，D为上述大口径超透镜的口径，F为上述大口径超透镜的F数，P为上述红外焦平面阵列探测器的像元间距，C d为要求的目标物体在探测图像中的最小像素密度；SNR为相机探测信噪比，K为与目标物体辐射程度、探测环境、透镜透过率、探测器响应度相关的参数，SNR d为要求的最低相机信噪比。上述确定准则同时考虑了相机的重量参数(大口径超透镜的口径与F数)与成像距离参数(目标物体离上述大口径红外超透镜相机的距离)，能更好地兼顾“更轻”与“更远”两大目标，解决了重量与成像距离(或作用距离)的矛盾。
本发明的一个实施例中，所述大口径超透镜1包括超表面微结构阵列101、覆盖超表面微结构阵列101的微结构阵列薄膜涂层102、基底103和覆盖基底103的基底薄膜涂层104；超表面微结构阵列101位于上述基底103的后表面，其中，上述基底103的后表面为沿着入射光方向，光线后到达的那一面；超表面微结构阵列101由一系列柱状结构单元1011按照有序晶格周期排列而成，其中，上述柱状结构单元1011的高度均相同，且介于所探测的波长量级，上述柱状结构单元1011的直径介于亚波长量级，所述柱状结构单元1011所组成的阵列周期小于10微米，所述柱状结构单元1011所组成的阵列直径等同于大口径超透镜1的口径，所述柱状结构单元1011 的材料采用红外高折射率材料，包括但不限于硅、锗等；覆盖超表面微结构阵列的微结构阵列薄膜涂层102用于入射光的增透，其表面形状跟随所述超表面微结构阵列101的形状，包括但不限于硫化锌、锗涂层；所述基底103采用对红外光高透的材料，包括但不限于本征双抛硅、硫化锌、氟化钡等；覆盖基底的基底薄膜涂104层用于入射光的增透，包括但不限于硫化锌、锗涂层。
本发明的一个实施例中，所述大口径超透镜1双面镀增透膜，提高了相机的透过率。
更进一步的说明，所述超表面微结构阵列101按如下方法设计：根据所述大口径超透镜1的口径与F数，使用衍射设计算法或光线追迹算法，优化设计所述大口径超透镜1的表面相位分布。根据严格电磁场数值算法，获得所述柱状结构单元1011的相位及透过率与柱状结构单元1011尺寸的关系。根据所述大口径超透镜1的表面相位分布，以及所述柱状结构单元1011的相位及透过率与柱状结构单元1011尺寸的关系，确定所述超表面微结构阵列101中每个位置处柱状结构单元1011的尺寸，并再次用衍射设计算法或光线追迹算法加以反馈优化。其中，所述柱状结构单元1011的红外透过率大于红外透过率的需求值；覆盖超表面微结构阵列的微结构阵列薄膜涂层102根据所述超表面微结构阵列101形状，通过电磁场仿真算法进行优化设计；基底103利用时域有限差分法与光线追迹法进行优化设计。上述设计方法无需复杂地计算整个大口径超透镜的严格电磁场，而是将大口径超透镜的设计分为表面相位分布设计与局部相位设计(即柱状结构单元的相位设计)，仅需计算柱状结构单元的严格电磁场与表面相位分布的衍射场或光线场，大大减小了计算规模，提高了设计效率；在仿真反馈优化环节，亦引入衍射算法或光线追迹算法代替严格电磁场算法，进一步提高了计算准确度，提高了优化效率。
本发明的一个实施例中，所述超表面微结构阵列101采用大面积半导 体工艺制备，包括但不限于步进式光刻、分步扫描式光刻、纳米压印、激光直写、金属剥离、ICP刻蚀等；覆盖超表面微结构阵列的微结构阵列薄膜涂层102与覆盖基底103的基底薄膜涂层104采用光学镀膜工艺制备，包括但不限于电子束蒸发镀膜；基底103经过光学抛光处理。上述制备工艺中用步进式光刻、分步扫描式光刻、纳米压印或激光直写等高产率大面积图形化工艺来代替小面积的电子束曝光与紫外投影式光刻工艺，拓展了图形化工艺的覆盖区域面积，增大了图形化的速度，使大口径超透镜可以大批量制备。
更进一步的说明，所述红外焦平面阵列探测器2用于消除杂散光和探测波段以外的光线，实现探测成像。本发明的一个实施例中，所述红外焦平面阵列探测器1包括沿入射光方向依次设置的探测器窗口和红外焦平面阵列；所述探测器窗口用于滤除系统的杂散光及探测波段外的光线；所述红外焦平面阵列用于对聚焦后的光线实现探测成像。
本发明的一个实施例中，所述超透镜机械组装件3用于对大口径超透镜1进行固定、调节与抗震保护。具体地，所述超透镜机械组装件3设有缓冲结构301，其中，缓冲结构301采用机械阻尼件3011，所述机械阻尼件3011的材料包括但不限于橡胶、复合材料、高阻尼合金等；缓冲结构301具有与大口径超透镜1边缘匹配的凹槽3012，可以夹取大口径超透镜1并对其进行固定与抗震保护；超透镜机械组装件3与外壳4固定相连，外壳4可通过伸缩构件5伸缩，从而超透镜机械组装件3与外壳4搭配对大口径超透镜1进行调节。所述超透镜机械组装件3设有缓冲结构301，可对大口径超透镜1进行固定、调节与抗震保护，避免了以往超透镜相机较差的机械性能。
本发明的一个实施例中，所述外壳4用于对镜头进行隔热与防水保护。优选地，外壳4采用隔热涂层6并密封处理，隔热涂层6材料包括但不限于金属氧化物微粉、非金属空心微珠等，密封处理包括但不限于在外壳连 接处采用密封垫圈401。所述外壳4使镜头具有更好的无热化与防水性能。
本发明中，所述大口径超透镜1与所述红外焦平面阵列探测器2的距离大于30mm。在大口径超透镜1与所述红外焦平面阵列探测器2之间不添加其他光学元件时，这为相机的焦距留出了必要的空间，是提高相机放大率的必要条件。
本发明提供了一种大口径红外超透镜相机，在设计技术上，提高了大口径超透镜的设计效率；在制备工艺上，使大口径超透镜可以大批量制备；从而大口径超透镜的口径可大于50mm，焦距可大于30mm，在保持大口径超透镜重量很小的前提下，放大率和成像距离大大提高，解决了目前红外超透镜相机焦距小、放大率低、成像距离不够的技术问题。同时本发明保持了超透镜轻薄(厚度小于2mm)、可大批量生产的优点，使得相机轻便、紧凑与低成本，大大减小了中远距离红外相机的重量、体积与成本，可用于中远距离探测成像、边界安防、中远距离热感应、智能家居、智能环境感知等场合。
下面通过具体实施例来进一步说明本发明的技术方案。
如图1所示为本发明提出的一种大口径红外超透镜相机，包括：大口径超透镜1、红外焦平面阵列探测器2、超透镜机械组装件3、外壳4、伸缩构件5以及隔热涂层6。
其中，大口径超透镜1用于对目标物体的热辐射进行光线弯折，其厚度为0.5mm；根据下式进一步选择大口径超透镜1的口径与F数：
Figure PCTCN2022120548-appb-000005
Figure PCTCN2022120548-appb-000006
式中，C为目标物体在探测图像中的像素密度，L为目标物体离上述大口径红外超透镜相机的距离，D为上述大口径超透镜的口径，F为上述大口径超 透镜的F数，P为上述红外焦平面阵列探测器的像元间距，C d为要求的目标物体在探测图像中的最小像素密度；SNR为相机探测信噪比，K为与目标物体辐射程度、探测环境、透镜透过率、探测器响应度相关的参数，SNR d为要求的最低相机信噪比。
本实施例中，P＝17μm，根据K的经验公式并代入经验值，在合适的SNR d下，选取F＝1。根据红外图像的约翰逊准则，辨认目标需要在临界方向上成像不少于12个像素，假设本实施例用于中大型室内智能感应(如体育馆)，需要探测人的全身热图像，从而辨认出人体并分析其移动位置及路线，为下一步控制室内设备(如空调、灯光、窗帘、投影仪等)提供信息，则目标物体为人，特征尺寸超过1m，考虑到相机还具有一定的像差与噪声，因此选取C d＝12*4＝48m -1。当成像距离L＝50m，F＝1，P＝17μm时，取D＝50.2mm，此时有C＝59m -1>C d。即大口径超透镜口径为50.2mm，F数为1，能同时满足本实施例信噪比与成像距离(不小于50米)的要求。上述确定准则保证在需求的目标参数下选取合适的参数，同时考虑了相机的重量参数(大口径超透镜的口径与F数)与成像距离参数(目标物体离上述大口径红外超透镜相机的距离)，能更好地兼顾“更轻”与“更远”两大目标，解决了重量与成像距离(或作用距离)的矛盾。
更进一步的说明，本实施例中大口径超透镜的具体结构如图2所示，包括超表面微结构阵列101、覆盖超表面微结构阵列101的微结构阵列薄膜涂层102、基底103和覆盖基底103的基底薄膜涂层104。超表面微结构阵列101位于所述基底103的后表面，其中，所述基底103的后表面为沿着入射光方向，光线后到达的那一面。本实施例为了获得较大的单元对相位的采样密度，所述超表面微结构阵列101由一系列柱状结构单元1011按照六方晶格周期排列而成。图3与图4进一步分别给出柱状结构单元1011和一个六方晶格形式的基底103的示意图和俯视图，需要说明的是，为了更好地表示柱状结构单元的结构，图中不包括覆盖超表面微结构阵列101的 微结构阵列薄膜涂层102和覆盖基底103的基底薄膜涂层104。其中，所述柱状结构单元1011的高度均相同，且介于所探测的波长量级，所述柱状结构单元1011的直径介于亚波长量级，所述柱状结构单元1011所组成的阵列周期小于10微米，所述柱状结构单元1011所组成的阵列直径等同于大口径超透镜1的口径D。本实施例中工作波段为长波红外，故所述柱状结构单元1011的材料采用本征硅。覆盖超表面微结构阵列101的微结构阵列薄膜涂层102用于入射光的增透，其表面形状跟随所述超表面微结构阵列101的形状，采用硫化锌与锗的交替涂层；所述基底103采用本征双抛硅晶圆；覆盖基底103的基底薄膜涂层104用于入射光的增透，采用硫化锌与锗的交替涂层。所述大口径超透镜1双面镀增透膜，理论上可将相机的透过率提高至80％以上。
本实施例中所述超表面微结构阵列101按如下方法设计：根据上述大口径超透镜1的口径D＝50.2mm与F＝1，使用光线追迹算法，优化设计上述大口径超透镜1的表面相位分布。根据时域有限差分算法(一种常用的严格电磁场数值算法)，获得上述柱状结构单元1011的相位及透过率与柱状结构单元1011尺寸(本实施例中为圆柱的直径)的关系。根据上述大口径超透镜1的表面相位分布，以及上述柱状结构单元1011的相位及透过率与柱状结构单元1011直径的关系，确定上述大面积超表面微结构阵列101中每个位置处柱状结构单元1011的尺寸，并再次用衍射设计算法加以反馈优化。具体地，衍射设计算法中代入柱状结构单元1011的相位与透过率，使仿真能反映超表面微结构阵列101的光学性能。其中，上述柱状结构单元1011的红外透过率大于红外透过率的需求值；覆盖超表面微结构阵列101的微结构阵列薄膜涂层102根据所述超表面微结构阵列101的形状，通过有限时域差分算法进行优化设计；基底103的厚度利用光线追迹法进行优化设计。按照上述方法，图5为最终设计得到的大口径超透镜1的表面相位分布，选取柱状结构单元1011的高度为6μm，周期为4μm，图6为柱状 结构单元1011的相位及透过率与柱状结构单元1011直径的关系，图7为设计得到的大口径超透镜1中的超表面微结构阵列101的俯视图。所有仿真设计都在普通计算机上完成，验证了本发明对大口径超透镜1很高的仿真设计效率。
更进一步的说明，所述超表面微结构阵列101采用大面积半导体工艺制备，本实施例中主要采用步进式光刻、ICP刻蚀两种工艺，其中步进式光刻采用9块掩膜版，分9次步进光刻，使9个曝光区域拼接为一个大口径超透镜1的曝光区域，产生超表面微结构阵列101的光刻胶图形；ICP刻蚀采用Bosch工艺，以步进式光刻产生的光刻胶图形作为刻蚀掩膜，获得高深宽比的超表面微结构阵列101。图8与图9分别为按以上工艺制得的超表面微结构阵列101的局部俯视图与斜视图。覆盖超表面微结构阵列101的微结构阵列薄膜涂层102与覆盖基底103的基底薄膜涂层104采用光学镀膜工艺制备。本实施例中采用电子束蒸发镀膜；基底为本征双抛片，两面均经过抛光处理。图10为1片6寸硅晶圆上制得4个大口径超透镜1，验证了本发明大口径超透镜1可以在硅晶圆上大批量制备。
更进一步的说明，所述红外焦平面阵列探测器2用于消除杂散光和探测波段以外的光线，实现探测成像。红外焦平面阵列探测器2包括沿入射光方向依次设置的探测器窗口和红外焦平面阵列；所述探测器窗口用于滤除系统的杂散光及探测波段外的光线；所述红外焦平面阵列用于对聚焦后的光线实现探测成像。本实施例中采用的红外焦平面阵列探测器2的技术指标如下：工作波段为8-14μm；像元尺寸为17μm；阵列分辨率为1280×960。
更进一步的说明，所述超透镜机械组装件3用于对大口径超透镜1进行固定、调节与抗震保护。如图11所示，超透镜机械组装件3包括缓冲结构301，其中，缓冲结构301设有机械阻尼件3011。本实施例中所述机械阻尼件3011采用橡胶；缓冲结构301具有与超透镜边缘匹配的凹槽3012，可以夹取大口径超透镜1并对其进行固定与抗震保护。如图1所示，超透 镜机械组装件3与外壳4固定相连，外壳4可通过伸缩构件5伸缩，从而使超透镜机械组装件3与外壳4搭配对超透镜进行调节。
更进一步的说明，所述外壳4用于对镜头进行隔热与防水保护。外壳4采用隔热涂层6并密封处理，本实施例中隔热涂层6材料采用一种复合乳液，填料为超细空心微珠、金属氧化物微粉与钛白粉。如图12所示，本实施例中密封处理为在外壳4连接处采用密封垫圈401。
更进一步的说明，所述大口径超透镜1与红外焦平面阵列探测器2的距离大于30mm。本实施例中这一距离为50mm。
为了验证本发明大口径红外超透镜相机的重量与成像距离性能，对本发明的实施例进行了实验测试，图13为本实施例大口径超透镜1的样件照片，验证了本发明超透镜口径大于50mm。用电子称量仪测得本实施例大口径超透镜重量仅为3.7克。室内50m远距离成像实验结果表明，对50m远的目标物(箭头处)可进行远距离识别，如图14所示。与可见光短焦镜头的识别效果对比，超透镜构成的红外相机具有更显著的识别效果。根据这一结果，本发明实施例更好地兼顾“更轻”与“更远”两大目标，解决了重量与成像距离(或作用距离)的矛盾。
本领域的技术人员容易理解，以上所述仅为本发明的较佳实施例而已，并不用以限制本发明，凡在本发明的精神和原则之内所作的任何修改、等同替换和改进等，均应包含在本发明的保护范围之内。

Claims (10)

  1. 一种大口径红外超透镜相机，其特征在于，包括大口径超透镜(1)、红外焦平面阵列探测器(2)、超透镜机械组装件(3)和外壳(4)；
    所述大口径超透镜(1)设置于所述超透镜机械组装件(3)，所述超透镜机械组装件(3)装配于所述外壳(4)，所述外壳(4)设有可使其沿大口径超透镜(1)镜面轴向移动的伸缩构件(5)；
    所述超透镜机械组装件(3)用于固定所述大口径超透镜(1)；
    所述伸缩构件(5)用于使所述大口径超透镜(1)沿其镜面轴向移动，以使所述大口径超透镜(1)与所述红外焦平面阵列探测器(2)之间的距离大于30mm；
    所述大口径超透镜(1)用于对目标物体的热辐射进行光线弯折并聚焦至所述红外焦平面阵列探测器(2)表面，其口径大于50mm，厚度小于2mm；
    所述红外焦平面阵列探测器(2)用于消除杂散光和探测波段以外的光线，从而实现探测成像。
  2. 根据权利要求1所述的一种大口径红外超透镜相机，其特征在于，所述大口径超透镜(1)包括超表面微结构阵列(101)、微结构阵列薄膜涂层(102)、基底(103)和基底薄膜涂层(104)；
    所述微结构阵列薄膜涂层(102)涂覆于所述超表面微结构阵列(101)表面，其表面形状与所述超表面微结构阵列(101)形状相同，用于对入射光的增透；
    所述基底薄膜涂层(104)涂覆于所述基底(103)表面，用于对入射光的增透；
    所述超表面微结构阵列(101)位于所述基底(103)的后表面，其中，所述基底(103)的后表面为沿着入射光方向，光线后到达的一面。
  3. 根据权利要求2所述的一种大口径红外超透镜相机，其特征在于， 所述超表面微结构阵列(101)包括按照有序晶格周期排列的多个柱状结构单元(1011)，其中，所述柱状结构单元(1011)的高度均相同，且介于所探测的波长量级；所述柱状结构单元的直径介于亚波长量级；
    所述柱状结构单元(1011)所组成的阵列周期小于10微米，且所述柱状结构单元(1011)所组成的阵列直径等于所述大口径超透镜(1)的口径。
  4. 根据权利要求3所述的一种大口径红外超透镜相机，其特征在于，所述柱状结构单元(1011)的材料包括硅或锗；所述微结构阵列薄膜涂层(102)的材料包括硫化锌或锗；所述基底(103)的材料包括本征双抛硅、硫化锌或氟化钡；所述基底薄膜涂层(104)的材料包括硫化锌或锗。
  5. 根据权利要求4所述的一种大口径红外超透镜相机，其特征在于，所述大口径超透镜(1)的口径与F数根据下式确定：
    Figure PCTCN2022120548-appb-100001
    Figure PCTCN2022120548-appb-100002
    其中，C为目标物体在探测图像中的像素密度，L为目标物体离所述大口径红外超透镜相机的距离，D为所述大口径超透镜的口径，F为所述大口径超透镜的F数，P为所述红外焦平面阵列探测器的像元间距，C d为要求的目标物体在探测图像中的最小像素密度；SNR为相机探测信噪比，K为与目标物体辐射程度、探测环境、透镜透过率、探测器响应度相关的参数，SNR d为要求的最低相机信噪比。
  6. 根据权利要求5所述的一种大口径红外超透镜相机，其特征在于，所述超表面微结构阵列(101)通过以下方法设计：
    根据所述大口径超透镜的口径与F数使用衍射设计算法或光线追迹算法，优化设计并获取所述大口径超透镜的表面相位分布；
    获得所述柱状结构单元的相位及透过率与柱状结构单元尺寸的关系；
    根据所述大口径超透镜的表面相位分布以及所述柱状结构单元的相位及透过率与柱状结构单元尺寸的关系，确定所述超表面微结构阵列中每个位置处柱状结构单元的尺寸，并再次用衍射设计算法或光线追迹算法加以反馈优化；其中，所述柱状结构单元的红外透过率大于红外透过率的需求值。
  7. 根据权利要求6所述的一种大口径红外超透镜相机，其特征在于，所述超表面微结构阵列(101)采用半导体工艺制备，包括但不限于步进式光刻、分步扫描式光刻、纳米压印、激光直写、金属剥离或ICP刻蚀。
    所述微结构阵列薄膜涂层(102)与基底薄膜涂层(104)采用光学镀膜工艺制备，包括但不限于电子束蒸发镀膜；
    所述基底(103)通过光学抛光处理。
  8. 根据权利要求1所述的一种大口径红外超透镜相机，其特征在于，所述红外焦平面阵列探测器(2)包括探测器窗口和红外焦平面阵列，所述探测器窗口和红外焦平面阵列沿入射光方向依次设置；
    所述探测器窗口用于滤除杂散光及探测波段外的光线；
    所述红外焦平面阵列用于对聚焦后的光线进行探测成像。
  9. 根据权利要求1所述的一种大口径红外超透镜相机，其特征在于，所述超透镜机械组装件(3)包括缓冲结构(301)，所述缓冲结构(301)设有与所述大口径超透镜(1)边缘匹配的凹槽(3012)，所述凹槽(3012)内设有用于对所述大口径超透镜(1)进行固定与抗震保护的机械阻尼件(3011)；
    所述机械阻尼件(3011)的材料包括但不限于橡胶、复合材料或高阻尼合金。
  10. 根据权利要求1所述的一种大口径红外超透镜相机，其特征在于，所述外壳(4)与所述超透镜机械组装件(3)、红外焦平面阵列探测器(2)的接触面分别设有密封垫圈(401)；
    所述外壳(4)设有隔热涂层(6)，所述隔热涂层(6)的材料包括但不限于金属氧化物微粉或非金属空芯微珠。
PCT/CN2022/120548 2021-10-25 2022-09-22 一种大口径红外超透镜相机 WO2023025327A1 (zh)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US18/024,982 US11815665B2 (en) 2021-10-25 2022-09-22 Large-aperture infrared metalens camera

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN202111239416.5 2021-10-25
CN202111239416.5A CN114025062B (zh) 2021-10-25 2021-10-25 一种大口径红外超透镜相机

Publications (1)

Publication Number Publication Date
WO2023025327A1 true WO2023025327A1 (zh) 2023-03-02

Family

ID=80057418

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2022/120548 WO2023025327A1 (zh) 2021-10-25 2022-09-22 一种大口径红外超透镜相机

Country Status (3)

Country Link
US (1) US11815665B2 (zh)
CN (1) CN114025062B (zh)
WO (1) WO2023025327A1 (zh)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114025062B (zh) * 2021-10-25 2022-07-05 华中科技大学 一种大口径红外超透镜相机
CN118295047A (zh) * 2023-01-05 2024-07-05 华为技术有限公司 一种超表面和成像装置

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110488394A (zh) * 2019-08-26 2019-11-22 华中科技大学 一种长波红外复合光学系统
CN111380612A (zh) * 2020-03-02 2020-07-07 华中科技大学 一种高光谱成像系统
CN112987203A (zh) * 2021-04-07 2021-06-18 中国科学院上海微系统与信息技术研究所 超表面透镜与探测器一体集成的红外光学系统及制作方法
CN113013268A (zh) * 2021-01-26 2021-06-22 中国科学院上海技术物理研究所 一种基于超表面透镜的小像元红外焦平面探测器
US20210231909A1 (en) * 2020-01-27 2021-07-29 University Of Washington Simultaneous focal length control and achromatic computational imaging with quartic metasurfaces
CN114025062A (zh) * 2021-10-25 2022-02-08 华中科技大学 一种大口径红外超透镜相机

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018204856A1 (en) * 2017-05-04 2018-11-08 President And Fellows Of Harvard College Meta-lens doublet for aberration correction
TWI728605B (zh) * 2018-12-20 2021-05-21 中央研究院 用於光場成像的超穎透鏡
CN111258058B (zh) * 2020-01-21 2021-09-03 中国科学院上海微系统与信息技术研究所 柔性遥感卫星光学镜片及其制作方法

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110488394A (zh) * 2019-08-26 2019-11-22 华中科技大学 一种长波红外复合光学系统
US20210231909A1 (en) * 2020-01-27 2021-07-29 University Of Washington Simultaneous focal length control and achromatic computational imaging with quartic metasurfaces
CN111380612A (zh) * 2020-03-02 2020-07-07 华中科技大学 一种高光谱成像系统
CN113013268A (zh) * 2021-01-26 2021-06-22 中国科学院上海技术物理研究所 一种基于超表面透镜的小像元红外焦平面探测器
CN112987203A (zh) * 2021-04-07 2021-06-18 中国科学院上海微系统与信息技术研究所 超表面透镜与探测器一体集成的红外光学系统及制作方法
CN114025062A (zh) * 2021-10-25 2022-02-08 华中科技大学 一种大口径红外超透镜相机

Also Published As

Publication number Publication date
CN114025062B (zh) 2022-07-05
US20230314776A1 (en) 2023-10-05
CN114025062A (zh) 2022-02-08
US11815665B2 (en) 2023-11-14

Similar Documents

Publication Publication Date Title
WO2023025327A1 (zh) 一种大口径红外超透镜相机
US10782513B2 (en) Total internal reflection aperture stop imaging
CN110488456A (zh) 光学透镜系统与成像系统
JP6164212B2 (ja) 撮像光学系、撮像装置
CN104516110A (zh) 一种共孔径宽波段红外光学系统
KR20170001640U (ko) 근적외선 이미징 렌즈
CN110376716B (zh) 一种近距离成像用微型成像镜头
WO2021017095A1 (zh) 一种摄像头模组
CN107991763A (zh) 一种高清长焦距长波红外镜头
CN105866936B (zh) 一种机载超广角全球面反射式光学系统
Ju et al. Optical design of reflecting omnidirectional zoom optical system with peripheral half-field of view from 110 to 72 for day and night surveillance
CN218956906U (zh) 一种大视场小f#高精度星敏感器光学系统
CN218995755U (zh) 定焦光学系统及监控摄像设备
CN113009675B (zh) 光学系统、取像模组及电子设备
CN114460729A (zh) 一种大相对孔径、大靶面非制冷红外连续变焦光学系统
GB2531726A (en) Compact multispectral wide angle refractive optical system
CN110716296B (zh) 一种大靶面小型化非制冷红外连续变焦光学系统
CN114252982A (zh) 焦距35mm的消热差红外镜头及其装配方法、成像方法
CN107121760A (zh) 一种宽波段制冷红外折反射全景镜头
CN115166955B (zh) 一种防辐射非制冷红外连续变焦光学系统及光学镜头
CN114089513B (zh) 一种-70℃~+100℃红外超宽温消热差光学系统
CN221668102U (zh) 一种长波红外大口径折超混合光学成像系统及红外相机
CN218497270U (zh) 一种离轴非球面反射镜补偿光学系统
RU2769088C1 (ru) Зеркально-линзовый объектив
CN114460730B (zh) 一种超小型化机载中波制冷红外连续变焦光学系统

Legal Events

Date Code Title Description
NENP Non-entry into the national phase

Ref country code: DE