CN114690304B - Near-far field double-channel image display method based on super-surface material - Google Patents
Near-far field double-channel image display method based on super-surface material Download PDFInfo
- Publication number
- CN114690304B CN114690304B CN202210334315.4A CN202210334315A CN114690304B CN 114690304 B CN114690304 B CN 114690304B CN 202210334315 A CN202210334315 A CN 202210334315A CN 114690304 B CN114690304 B CN 114690304B
- Authority
- CN
- China
- Prior art keywords
- nano
- brick
- dimensional code
- super
- light intensity
- Prior art date
- Legal status (The legal status 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 status listed.)
- Active
Links
- 238000000034 method Methods 0.000 title claims abstract description 28
- 239000000463 material Substances 0.000 title claims abstract description 26
- 239000002086 nanomaterial Substances 0.000 claims abstract description 33
- 238000013461 design Methods 0.000 claims abstract description 29
- 239000011449 brick Substances 0.000 claims description 88
- 230000010287 polarization Effects 0.000 claims description 18
- 238000009826 distribution Methods 0.000 claims description 13
- 239000000758 substrate Substances 0.000 claims description 10
- 238000005457 optimization Methods 0.000 claims description 6
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims description 5
- 230000005540 biological transmission Effects 0.000 claims description 5
- 229910052709 silver Inorganic materials 0.000 claims description 5
- 239000004332 silver Substances 0.000 claims description 5
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 4
- 238000001514 detection method Methods 0.000 claims description 4
- 238000011156 evaluation Methods 0.000 claims description 4
- 229910052710 silicon Inorganic materials 0.000 claims description 4
- 239000010703 silicon Substances 0.000 claims description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 3
- 238000004422 calculation algorithm Methods 0.000 claims description 3
- 238000002922 simulated annealing Methods 0.000 claims description 3
- 238000004088 simulation Methods 0.000 claims description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 2
- 229910052782 aluminium Inorganic materials 0.000 claims description 2
- 239000005350 fused silica glass Substances 0.000 claims description 2
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 2
- 229910052737 gold Inorganic materials 0.000 claims description 2
- 239000010931 gold Substances 0.000 claims description 2
- 230000003121 nonmonotonic effect Effects 0.000 claims description 2
- 239000011521 glass Substances 0.000 claims 1
- 238000003384 imaging method Methods 0.000 abstract description 4
- 230000003287 optical effect Effects 0.000 abstract description 4
- 238000012545 processing Methods 0.000 abstract description 4
- 238000005516 engineering process Methods 0.000 description 7
- 230000008859 change Effects 0.000 description 6
- 239000012802 nanoclay Substances 0.000 description 3
- 238000004364 calculation method Methods 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000004927 fusion Effects 0.000 description 2
- 230000010354 integration Effects 0.000 description 2
- 238000002834 transmittance Methods 0.000 description 2
- 238000013459 approach Methods 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000001093 holography Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000008092 positive effect Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000002310 reflectometry Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 239000002210 silicon-based material Substances 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/30—Polarising elements
- G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
-
- 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
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/0012—Optical design, e.g. procedures, algorithms, optimisation routines
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/32—Holograms used as optical elements
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
- G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
- G03H1/02—Details of features involved during the holographic process; Replication of holograms without interference recording
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
- G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
- G03H1/04—Processes or apparatus for producing holograms
- G03H1/0402—Recording geometries or arrangements
- G03H1/041—Optical element in the object space affecting the object beam, not otherwise provided for
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
- G06K19/00—Record carriers for use with machines and with at least a part designed to carry digital markings
- G06K19/06—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code
- G06K19/06009—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code with optically detectable marking
- G06K19/06037—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code with optically detectable marking multi-dimensional coding
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
- G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
- G03H1/02—Details of features involved during the holographic process; Replication of holograms without interference recording
- G03H2001/0208—Individual components other than the hologram
- G03H2001/0216—Optical components
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
- G03H2223/00—Optical components
- G03H2223/22—Polariser
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Engineering & Computer Science (AREA)
- Theoretical Computer Science (AREA)
- Holo Graphy (AREA)
Abstract
The invention discloses a near-far field double-channel image display method based on a super-surface material, which utilizes two-dimension code image recognition redundancy, intensity modulation redundancy and holographic design redundancy, and the extra design freedom degree given by the redundancy is realized by carefully designing the steering angle of a nano structure, and the reconstruction of a twin-image-free holographic image is realized in the far field while encoding a two-dimension code pattern on the structural surface of a super-surface formed by a single nano structure. The method has strong expansibility and robustness, not only expands to other optical platforms and working wave bands, but also is suitable for large-area processing and production. And because of different imaging modes in the near field and the far field and different decoding conditions, the invention has wide application prospect in the fields of high-end anti-counterfeiting, image display and the like.
Description
Technical Field
The invention belongs to the technical field of micro-nano optics, and particularly relates to a near-far field double-channel image display method based on a super surface.
Background
The super surface has super light wave control capability, so that the amplitude, the phase and the polarization can be precisely regulated and controlled, and the super surface is the first choice of the current high-performance, high-capacity and multifunctional optical platform. In recent years, image display technology based on a super-surface material has been widely focused by students at home and abroad due to the characteristics of lightweight, miniaturization, large capacity, high density and the like. In 2018, bao et al have encoded two-dimensional codes on the surface of a piece of super-surface material by designing related pixels composed of various nano structures, and decode the two-dimensional code images by a specific wavelength and an incident angle. In the same year Zhang et al encoded a two-dimensional code image in a beam of laser, and needed to decode the image by means of an analyzer. In addition, many holographic image display technologies based on the super-surface material have been proposed by researchers, and the reconstruction of the target holographic image is achieved in the far field by optimally designing the material, size and arrangement of the nano-structure. Thereafter, researchers have fully explored various degrees of freedom of regulation in nanostructures, enabling the display of near-field images and far-field images simultaneously based on a single supersurface consisting of a single nanostructure, a variable-size nanostructure, or a stacked structure.
The invention provides a novel super-surface near-far field dual-channel image display technology. The design of the super-surface array arrangement is carried out by utilizing a single nano structure, so that a holographic image without twin images can be reproduced in a distance while a two-dimensional code image is encoded on the surface (near field) of the super-surface material. The novel image display technology enriches the research field of image display and has good development prospect in the fields of high-end anti-counterfeiting, image hiding and the like.
Disclosure of Invention
In order to solve the limitation of the current near-far field image display technology based on the single nanostructure super surface, the invention aims to provide a near-far field double-channel image display method based on the super surface, which utilizes the redundancy of image recognition, intensity modulation and holographic design, and realizes the fusion of a binary image and a twin-image-free holographic image by designing the steering angle of the single nanostructure, thereby realizing a novel near-far field double-channel image display technology.
In order to achieve the above purpose, the invention is realized by the following technical scheme:
the supersurface is formed by an array of a plurality of nano-tile structural units on a plane, the nano-tile structural units consisting of a transparent substrate and nano-tiles deposited thereon. The steering angle of the nano brick structural unit is theta, and the value range of theta is [0, pi ]. The surface of the transparent substrate on which the nano bricks are deposited is a square working surface with the side length of C, and the side length of C is a sub-wavelength level; the length L, the width W and the height H of the nano brick are all sub-wavelength levels; and according to the selected working wavelength and the wanted electromagnetic response characteristic, the specific geometric dimension is obtained through electromagnetic simulation optimization. An xoy coordinate system is established by taking a right-angle side of the unit structure as an x axis and a y axis, a long side of the nano brick is a long axis, a short side of the nano brick is a short axis, and an included angle between the long axis and the x axis of the nano brick is a steering angle theta of the nano brick.
On the basis of the technical scheme, preferably, the transparent substrate is made of fused silica glass material, and the nano brick is made of gold, silver, aluminum, silicon and other materials or is made of SOI material to design nano units.
The intensity control redundancy of the nano structures and the redundancy of the two-dimensional code and holographic image design are utilized, and the fusion of the two-dimensional code image and the holographic image without twin images can be realized on a super surface by arranging the steering angle of each nano structure in the array structure. And the information of the two channels is mutually independent and can be designed at will, so that the method has strong flexibility. The invention can be applied to the fields of high-end anti-counterfeiting, polarization display, image hiding and the like.
The invention provides a near-far field double-channel image display method based on a super-surface material, which comprises the following steps:
1) The super surface is formed by arranging a plurality of nano brick structure units on a plane, and the corresponding relation between the emergent light intensity and the steering angle of the nano brick structure units in the range of [0,180 ° ] value is obtained by utilizing the emergent light intensity modulation function of the nano brick structure units and the gray information of the two-dimensional code image;
2) A two-dimensional code image is encoded on the near field of the super surface by utilizing the nano brick structure unit, and white pixels in the encoded two-dimensional code image are led into noise points to enable gray values of the white pixels to be converted into noise point pixels between (0 and 1) due to the redundancy of identification and detection of the two-dimensional code, and the two-dimensional code image can still be identified and detected to obtain a modulated two-dimensional code image;
3) Because the emergent light intensity modulation function has redundancy, namely the emergent light intensity modulation function turns to angle [0,180 DEG ] at the nano brick]The value range is a non-monotonic function, the same emergent intensity corresponds to a plurality of nano brick steering angles (if the intensity modulation function is cos 2 θ or sin 2 θ, 2; if the intensity modulation function is cos 2 2 theta or sin 2 In 2 theta, 4 are corresponding); according to the method of the step 2), the encoding of the modulated two-dimensional code image is realized by utilizing the emergent light intensity modulation function of the nano brick structure unit, noise pixels are introduced into the two-dimensional code image, so that the gray value types of white pixels in the two-dimensional code image are increased, the steering angle types of the nano brick array corresponding to the modulated two-dimensional code image are increased, the candidate information of various nano brick steering angles can be correspondingly introduced, and the introduction of the plurality of nano brick steering angles does not change the intensity of the near-field two-dimensional code image. However, when circularly polarized light is incident on the super surface, the phase distribution is selected to be more (the phase change amount of the geometric phase and the steering angle of the nano brick have linear relation), so that candidate information of various geometric phase distributions can be correspondingly introduced and obtained, and holographic transformation is carried out according to the obtained various geometric phase distributions to obtain a series of corresponding design holographic images;
4) Based on the redundancy of the holographic design, the same holographic image corresponds to various geometric phase distributions; the fidelity of the holographic design and the fidelity of the two-dimensional code image are used as evaluation indexes (namely, the minimum error of the designed holographic image and the target holographic image is used as the evaluation index), and the simulated annealing optimization algorithm is utilized to select the most suitable noise point introduction mode from the steering angle values of various candidate nano bricks, so that the design and the realization of the near-field two-dimensional code image and the far-field twin-image-free holographic image are realized.
In the step 3), as the phase change amount of the geometric phase is twice as large as the rotation angle of the nano brick, the steering angles of various candidate nano bricks are correspondingly introduced into the candidate information of various geometric phase distribution.
On the basis of the technical proposal, the nanometerEach nano-unit structure in the unit array is equivalent to an intensity modulator, and the emergent light intensity can be continuously changed by changing the steering angle of the nano-structure. By designing the geometric dimension of the nano structure or setting the deflection direction angle of the polarizer and the analyzer, the function relationship between the emergent light intensity and the nano brick steering angle can be cos 2 θ、sin 2 θ、cos 2 2θ、sin 2 2 theta, and the like. To achieve a target intensity distribution, the nanobricks of different steering angles may be arranged.
Specifically, if the polarization direction is α 1 After linear polarization passes through the nano structure, the emergent light intensity I 1 Can be expressed as:
I 1 ＝I 0 [A 2 cos 2 (θ-α 1 )+B 2 sin 2 (θ-α 1 )]
wherein I is 0 For the intensity of incident light, a and B are the complex transmission coefficients or reflection coefficients of the long and short axes of the nanobrick, respectively. When the nano brick is a polarizer, namely a=1, b=0 or a=0, b=1, the outgoing light intensity modulation function can be realized to be cos by designing the polarization direction of the incident ray polarization 2 θ、sin 2 θ。
If the polarization direction is alpha 1 After the linear polarized light passes through the nano structure, the linear polarized light passes through the polarization direction alpha 2 The analyzer of (1) emits light intensity I 2 Can be expressed as:
then by designing alpha 1 、α 2 And A, B, the modulation function of the emergent light intensity can be realized to be cos 2 2θ、sin 2 2 theta. For example, alpha 1 ＝45°，α 2 -45 °, a=1, b= -1 (the nano-brick is a half-wave plate) the output light intensity function is cos 2 2θ。
If the light intensity enhancement function cos is selected 2 θ、sin 2 θ, the nano brick has the characteristic of polarization light splitting through the optimal designThat is, almost all of the linearly polarized light incident in the long axis direction is reflected when passing through the nanobricks, and almost all of the linearly polarized light incident in the short axis direction is transmitted when passing through the nanobricks. Or (and) almost all of the linearly polarized light incident along the long axis direction is transmitted through the nano-brick, and almost all of the linearly polarized light incident along the short axis direction is reflected through the nano-brick.
If the light intensity enhancement function cos is selected 2 2θ、sin 2 And if the structure is a half-wave plate structure, the highest emergent efficiency can be obtained.
When the nano structure is used as a phase modulator, the nano brick steering angle and the phase change amount caused by the nano brick steering angle are based on the geometric phase principleThe relation of (2) is as follows
Thus, the nanostructure can be seen as an intensity modulator in near field imaging. In far field imaging, it can be seen as a phase modulator. Therefore, in order to achieve both functions, an extra degree of freedom in design needs to be found, ensuring that both can exist simultaneously in one structure.
Redundancy of two-dimensional code identification and detection means that some errors or noise are added into the two-dimensional code, and identification and detection of the two-dimensional code are not affected. Redundancy of a holographic design means that the design target hologram is not unique in its corresponding phase distribution. The light intensity modulation redundancy of the nanostructure unit means that when the nanostructure is used as an intensity modulator, the same emergent light intensity can simultaneously correspond to a plurality of steering angles theta in the range of steering angles [0, pi ] of the nano bricks. The design freedom degree brought by the three redundancy degrees is comprehensively utilized, and the problem of the existing near-far field image display technology based on a simple structure can be solved. On a piece of super surface, the two-dimensional code image and the holographic image without twin images are realized simultaneously.
Specifically, the two-dimensional code image includes two parts of a black pixel and a white pixel (the black pixel gray value is 0 and the white pixel gray value is 1). The redundancy of the two-dimensional code can ensure that when white pixels in the two-dimensional code are added with noise points, namely pure white pixels with gray values of 1 are converted into noise point pixels with gray values of 0.25, 0.5, 0.75 and 1, the two-dimensional code image can still be identified.
After adding the noise pixel into the two-dimensional code image, converting the gray value of the noise pixel modulated by the two-dimensional code image into emergent light intensity, and converting the emergent light intensity into a conversion formula cos of a light intensity modulation function 2 θ、sin 2 θ、cos 2 2θ、sin 2 The 2 theta redundancy can be known, and the value range of the nano brick is [0, pi ]]In the method, the number of the turning angles of the nano bricks corresponding to the same emergent intensity is changed into a plurality of, and only one turning angle is not needed, so that the change amount of the geometric phase brought by the nano bricks is changed into a plurality of types, and the method is favorable for designing multi-step phase type holographic and eliminating twin images.
Based on the redundancy of holographic design, the same holographic image can be designed with various geometric phase distributions. For example, when the white pixel point in each two-dimensional code has 4 candidates of gray noise points, if the intensity modulation function is selected as cos 2 And theta, one gray noise point corresponds to two nano brick corners, so that 8 phase change amounts corresponding to far fields are introduced. For a two-dimensional code image with 200x200 white pixels, a total of 8 200x200 Seed noise point introduction scheme is corresponding to 8 200x200 And under the phase distribution condition, the fidelity of the holographic design and the fidelity of the two-dimensional code image (the error between the design image and the target image is the smallest) are taken as evaluation indexes, and the most suitable noise point introduction scheme is selected by using a simulated annealing algorithm, so that the design and the realization of the near-field two-dimensional code image and the far-field twin-free image are realized.
The near-far field double-channel image display method based on the super-surface material has the following advantages and positive effects:
1. on the basis of not changing the two-dimensional code function, a twin-image-free holographic image is encoded in the far field. The method overcomes the limitation of the existing method for realizing the near-far field image display based on a simple structure, and provides a brand new method and approach for the near-far field image display.
2. The method can be realized by only a single nano brick structure, has low processing difficulty and simple structure, and is suitable for large-area integration and processing.
3. The nanostructure required by the present invention is not limited to a specific material, and various materials and various schemes can be implemented.
4. The method has strong robustness to the geometric dimension of the nano structure, so the tolerance to processing errors is high, and the method is more convenient for practical application.
5. The two-dimensional code image and the holographic image are respectively reproduced by imaging modes based on two different principles of nano printing and holography, so that the decoding conditions are different. Near-field images are observed by means of an amplifying system or a microscope, far-field images are observed by constructing holographic light paths by themselves, and complex observation conditions enable the near-field images to have strong application prospects in the fields of encryption, high-end anti-counterfeiting and the like.
6. The multifunctional optical device can work in a transmission mode and a reflection mode, and has great convenience in practical application.
7. The geometry of the super surface is very small and is only of the order of sub-wavelength, and two images with the size of 500x500 pixels are encoded, and only one super surface with the size of 200x200 mu m is needed, so that the super surface has the characteristics of miniaturization, light weight and high integration, and is suitable for large-scale development of future miniaturization and microminiaturization.
8. The method provided by the invention is not limited to nano-size and visible light wave bands, and can be used for pushing traditional optical devices and a plurality of working wave bands.
Drawings
Fig. 1 is a schematic diagram of the structure of a nano brick unit in this example 1.
Fig. 2 is a graph of a transreflective scan of a silver nanoclay brick unit structure in this example 1.
Fig. 3 is a flow chart of the design of the turning angle of the nano-tile in this example 1.
Fig. 4 is a two-dimensional code image of the channel 1 code in the present embodiment 1.
Fig. 5 is a holographic image without twin image encoded by channel 2 in this example 1.
Fig. 6 is a schematic diagram of the structure of the nano brick unit in the present embodiment 1.
Fig. 7 is a reflectance scan of the nano-tile unit structure of this example 2.
Fig. 8 is a two-dimensional code image of the channel 1 code in this embodiment 2.
Fig. 9 is a holographic image without twin image encoded by channel 2 in this example 2.
Detailed Description
In order to more clearly illustrate the embodiments of the present invention and/or the technical solutions in the prior art, the following description will explain specific embodiments of the present invention with reference to the accompanying drawings. It is obvious that the drawings in the following description are only examples of the present invention, and that other drawings and other embodiments may be obtained from these drawings by those skilled in the art without inventive effort.
The invention will now be further described with reference to the drawings by way of specific examples.
In fig. 1, L is the length of the nano brick, W is the width of the nano brick, H is the height of the nano brick, C is the unit size of the nano brick, θ is the direction angle of the nano brick, and is the angle between the long axis and the x axis of the nano brick.
Embodiment 1 and embodiment 2 are specific implementation processes of a near-far field dual-channel image display method based on a super-surface material.
Example 1
In this embodiment, the nano unit structure is composed of a silver nano brick and a silicon substrate, the design wavelength is selected to be λ=633 nm, and for this wavelength, the electromagnetic simulation software CST is used to perform optimization simulation on the nano unit structure, so as to obtain the optimized size parameters of the silver nano brick: the length is L=160 nm, the width is W=80 nm, the height is H=70 nm, and the side length of the unit structure substrate is C=300 nm. The structural parametersThe efficiency of the lower nanoclay to the transmission and reflection of linearly polarized light incident along the long and short axes of the nanoclay is shown in FIG. 2, where R l 、R s Representing the reflected light efficiency of the reflection along the long and short axes of the nanobrick, respectively. Specifically, at an operating wavelength of 633nm, the reflectance R of the nano brick in the long axis direction l And transmittance T in the short axis direction of the nano-brick s Respectively 92.6% and 95.3%, while the reflectivity R along the short axis direction of the nano brick s And transmittance T along long axis direction of the nano-brick l Is suppressed to 4% and 2% or less. Thus, at 633nm, the optimized nanobrick can be considered an ideal polarizer in both reflective and transmissive modes.
Considering the redundancy characteristics of the nanostructure intensity modulation, two-dimensional code recognition and holographic design, the steering angle of the nano brick is determined according to the design flow of fig. 3. Firstly, determining a candidate value of the steering angle of the participating nano structure according to the two-dimensional code target image. Due to the redundancy of the two-dimensional code image and the intensity modulation function, the two-dimensional code image can be built by having various nano brick steering angles. And then according to a target holographic image and a far-field diffraction calculation formula, finding a feasible steering angle distribution which not only meets the two-dimensional code identification but also can realize holographic reconstruction from the selectable space of the nanostructure steering angle. And finally, the simultaneous encoding of the two-dimensional code and the twin-image-free holographic image is realized on the super surface formed by the nano structures with the same size and different steering angles, as shown in fig. 4 and 5.
Example 2
In this embodiment, the nano-unit structure is made of an SOI material, wherein the nano-brick is silicon, and the base material is silicon dioxide and a silicon material, as shown in fig. 6. Selecting a design wavelength of lambda=610 nm, and optimizing and simulating a nano-conversion unit structure by electromagnetic simulation software CST according to the wavelength to obtain the optimized SOI nano-brick with the size parameters of: the length is 180nm, the width is 100nm, the height is 220nm, and the unit structure size is 400. As is apparent from fig. 7, the reflection efficiency of the nano-brick on the linearly polarized light incident along the long axis and the short axis of the nano-brick under the structural parameters is shown, the light incident along the long axis direction of the nano-brick is hardly reflected at 610nm, and the light incident along the short axis direction of the nano-brick is mostly reflected, so that it can be regarded as a reflective polarizer.
The steering angle of the nano-tile is determined according to the design flow of fig. 3. Firstly, determining a nano structure participating in holographic design according to a two-dimensional code target image, and then finding a feasible steering angle distribution which not only meets two-dimensional code encoding but also can realize holographic reproduction from selectable spaces of a nano structure steering angle according to a target holographic image and a far-field diffraction calculation formula. And finally, the simultaneous encoding of the two-dimensional code and the holographic image without the twin images is realized on the super surface formed by the nano structures with the same size and different steering angles, as shown in fig. 8 and 9.
The above-described embodiments are intended to illustrate the present invention, not to limit it, and any modifications and variations may be made thereto within the spirit of the invention and the scope of the appended claims.
Claims (6)
1. A near-far field double-channel image display method based on a super-surface material is characterized by comprising the following steps:
1) The super surface is formed by arranging a plurality of nano brick structure units on a plane, and the corresponding relation between the emergent light intensity and the steering angle of the nano brick structure units in the range of [0,180 ° ] value is obtained by utilizing the emergent light intensity modulation function of the nano brick structure units and the gray information of the two-dimensional code image;
2) A two-dimensional code image is encoded on the near field of the super surface by utilizing the nano brick structure unit, and white pixels in the encoded two-dimensional code image are led into noise points to enable gray values of the white pixels to be converted into noise point pixels between (0 and 1) due to the redundancy of identification and detection of the two-dimensional code, and the two-dimensional code image can still be identified and detected, so that a modulated two-dimensional code image is obtained;
3) Because the emergent light intensity modulation function has redundancy, namely the emergent light intensity modulation function is a non-monotonic function within the range of the turning angles [0,180 DEG ] of the nano bricks, the same emergent intensity corresponds to a plurality of turning angles of the nano bricks; according to the method of the step 2), the coding of the modulated two-dimensional code image is realized by utilizing the emergent light intensity modulation function of the nano brick structural unit, noise pixels are introduced into the two-dimensional code image, the gray value types of the white pixels in the two-dimensional code image are increased, and candidate information of various nano brick steering angles is correspondingly introduced; when circularly polarized light is incident, correspondingly introducing candidate information of various geometric phase distributions;
4) Based on the redundancy of the holographic design, the same holographic image corresponds to various geometric phase distributions; the fidelity of the holographic design and the fidelity of the two-dimensional code image are used as evaluation indexes, and a simulated annealing optimization algorithm is utilized to select the most suitable noise point introduction mode from a plurality of candidate nano brick steering angle values, so that the design and the realization of the near-field two-dimensional code image and the far-field twin-image-free holographic image are realized;
the nano brick structure unit comprises a transparent substrate and nano bricks, wherein the transparent substrate is placed on the plane, and the nano bricks are deposited on the transparent substrate; the steering angle of the nano brick structure unit is theta, and the value range of theta is [0, pi ]; the surface of the transparent substrate on which the nano bricks are deposited is a square working surface with the side length of C, and the side length of C is a sub-wavelength level; the length L, the width W and the height H of the nano brick are all sub-wavelength levels; l, W and H are obtained through electromagnetic simulation optimization according to the wavelength of the selected incident light; establishing an xoy coordinate system by taking a right-angle side of a unit structure as an x-axis and a y-axis, taking a long side of a nano brick as a long axis and a short side of the nano brick as a short axis, wherein an included angle between the long axis and the x-axis of the nano brick is a steering angle theta of the nano brick;
the transparent substrate is made of fused quartz glass material, and the nano brick material comprises gold, silver, aluminum or silicon.
2. The near-far field dual-channel image display method based on a super-surface material as set forth in claim 1, wherein in step 1), the functional relationship between the outgoing light intensity and the turning angle θ is obtained by designing the geometry of the nanostructure unit or setting the deflection angle of the incoming polarizer and analyzer, i.e., the outgoing light intensity modulation function is cos 2 θ、sin 2 θ、cos 2 2 theta or sin 2 2θ。
3. As claimed inThe near-far field dual-channel image display method based on the super-surface material as set forth in claim 2, wherein the polarization direction is alpha 1 After passing through the nanostructure unit, the linear polarized light of (2) is emitted to light intensity I 1 Can be expressed as:
I 1 ＝I 0 [A 2 cos 2 (θ-α 1 )+B 2 sin 2 (θ-α 1 )]
wherein I is 0 For the incident light intensity, A and B are complex transmission coefficients or reflection coefficients of the long axis and the short axis of the nano brick respectively; when the nano brick is a polarizer, namely a=1, b=0 or a=0, b=1, the outgoing light intensity modulation function can be realized to be cos by designing the polarization direction of the incident ray polarization 2 θ or sin 2 θ。
4. The near-far field dual-channel image display method based on super-surface material as set forth in claim 3, characterized in that the outgoing light intensity modulation function is cos 2 θ or sin 2 θ, the optimization design is needed to make the nano-brick have the characteristic of polarization light splitting, that is, when the incident light wave passes through the nano-brick at the working wavelength, the linear polarized light with the polarization direction along the long axis of the nano-brick is reflected, and meanwhile, the linear polarized light with the polarization direction along the short axis of the nano-brick is transmitted, or the linear polarized light with the polarization direction along the long axis of the nano-brick is transmitted, and meanwhile, the linear polarized light with the polarization direction along the short axis of the nano-brick is reflected.
5. The near-far field dual-channel image display method based on the super-surface material as set forth in claim 2, characterized in that the polarization direction is alpha 1 After passing through the nanostructure unit, the linearly polarized light of (a) is polarized to alpha 2 The analyzer of (1) emits light intensity I 2 Can be expressed as:
wherein I is 0 A and B are respectively the long axis and the long axis of the nano brick for the incident light intensityComplex transmission or reflection coefficients of the minor axis; then by designing alpha 1 、α 2 And A, B, the modulation function of the emergent light intensity can be realized to be cos 2 2 theta or sin 2 And 2 theta, wherein the nanostructure unit is of an anisotropic structure, so that near-far field double-channel image display can be realized, and the highest emergent efficiency can be obtained if a half-wave plate structure is optimized.
6. The near-far field dual-channel image display method based on the super-surface material as set forth in claim 1, wherein in the step 2), white pixels in the two-dimensional code image are introduced into noise pixels, so that gray values of the white pixels are converted into noise pixels of 0.25, 0.5, 0.75 and 1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210334315.4A CN114690304B (en) | 2022-03-31 | 2022-03-31 | Near-far field double-channel image display method based on super-surface material |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210334315.4A CN114690304B (en) | 2022-03-31 | 2022-03-31 | Near-far field double-channel image display method based on super-surface material |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN114690304A CN114690304A (en) | 2022-07-01 |
| CN114690304B true CN114690304B (en) | 2023-12-29 |
Family
ID=82140628
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210334315.4A Active CN114690304B (en) | 2022-03-31 | 2022-03-31 | Near-far field double-channel image display method based on super-surface material |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114690304B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2024032525A1 (en) * | 2022-08-09 | 2024-02-15 | 北京与光科技有限公司 | Light modulation layer of spectrum chip, and spectrum chip |
| CN115293312B (en) * | 2022-10-08 | 2023-01-24 | 深圳前海量子云码科技有限公司 | Anti-counterfeiting method, anti-counterfeiting device, computer equipment and storage medium |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110794661A (en) * | 2019-11-22 | 2020-02-14 | 武汉大学 | Method for realizing double-channel nano printing and double-channel holography based on laminated super surface |
| CN110927858A (en) * | 2019-12-16 | 2020-03-27 | 武汉大学 | Super surface for realizing near-field double-color image display and far-field holographic multiplexing and design method thereof |
| CN112882141A (en) * | 2021-01-27 | 2021-06-01 | 武汉大学 | Color nano printing and holographic multiplexing three-channel super surface and design method thereof |
| CN112882139A (en) * | 2021-01-27 | 2021-06-01 | 武汉大学 | Super surface for realizing near-field structural color display and holographic multiplexing and design method thereof |
| CN113589409A (en) * | 2021-07-29 | 2021-11-02 | 中国科学技术大学 | All-optical image processing system and method based on super-surface device |
-
2022
- 2022-03-31 CN CN202210334315.4A patent/CN114690304B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110794661A (en) * | 2019-11-22 | 2020-02-14 | 武汉大学 | Method for realizing double-channel nano printing and double-channel holography based on laminated super surface |
| CN110927858A (en) * | 2019-12-16 | 2020-03-27 | 武汉大学 | Super surface for realizing near-field double-color image display and far-field holographic multiplexing and design method thereof |
| CN112882141A (en) * | 2021-01-27 | 2021-06-01 | 武汉大学 | Color nano printing and holographic multiplexing three-channel super surface and design method thereof |
| CN112882139A (en) * | 2021-01-27 | 2021-06-01 | 武汉大学 | Super surface for realizing near-field structural color display and holographic multiplexing and design method thereof |
| CN113589409A (en) * | 2021-07-29 | 2021-11-02 | 中国科学技术大学 | All-optical image processing system and method based on super-surface device |
Also Published As
| Publication number | Publication date |
|---|---|
| CN114690304A (en) | 2022-07-01 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN114690304B (en) | Near-far field double-channel image display method based on super-surface material | |
| CN110794661B (en) | Method for realizing double-channel nano printing and double-channel holography based on laminated super surface | |
| Jung et al. | Metasurface-driven optically variable devices | |
| CN110335533B (en) | Optical information hiding method based on super-surface array structure | |
| CN107065491B (en) | Nano brick array hologram sheet and its design method applied to holographic false proof | |
| CN110426783B (en) | Multifunctional super surface based on micro-nano half-wave plate | |
| CN111399088B (en) | Three-channel image display method based on micro-nano polarizer array super-surface | |
| CN110376672A (en) | A kind of super surface array structure and its application in image display multiplexing | |
| Dai et al. | Ultracompact, high-resolution and continuous grayscale image display based on resonant dielectric metasurfaces | |
| CN113238302B (en) | Method for realizing dynamically adjustable metasurface based on vector holographic technology | |
| CN110780366A (en) | Optical super-surface focusing imaging element resistant to temperature interference and method thereof | |
| CN110568528A (en) | Double-mode super surface based on SOI material and double-mode display application thereof | |
| CN112601990A (en) | Diffraction grating comprising a two-material structure | |
| CN110647024B (en) | Method for realizing circuitous phase coding multiplexing based on super-surface array structure | |
| Shen et al. | A review on metasurface beam splitters | |
| CN110568557A (en) | Information multiplexing method based on polarization control | |
| CN111258060B (en) | Super surface design method capable of realizing transflective dual-channel holographic multiplexing | |
| Yang et al. | Multiwavelength high-order optical vortex detection and demultiplexing coding using a metasurface | |
| CN111399086B (en) | Fork-shaped grating multiplexing method based on super-surface material | |
| CN113094927B (en) | Method for realizing multi-channel information coding by using novel optical film | |
| Seong et al. | Cost-Effective and Environmentally Friendly Mass Manufacturing of Optical Metasurfaces Towards Practical Applications and Commercialization | |
| CN110568527B (en) | Resonance type SOI super surface and application thereof in nano printing technology | |
| CN111175855B (en) | Multiple information multiplexing super surface and design method thereof | |
| CN115933174A (en) | Phase modulation-based nano printing and holographic multiplexing design method | |
| CN114967396A (en) | Double-layer super surface capable of realizing holographic encryption |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |