Computer-generated holography technology has been widely applied,and as research in this field deepens,the demand for memory and computational power in small AR and VR devices continues to increase.This paper presents...Computer-generated holography technology has been widely applied,and as research in this field deepens,the demand for memory and computational power in small AR and VR devices continues to increase.This paper presents a hologram generation method,i.e.,a symmetrically high-compressed look-up table method,which can reduce memory usage by50%.In offline computing,half of the basic horizontal and vertical modulation factors are stored,halving the memory requirements without affecting inline speed.Currently,its potential extends to various holographic applications,including the production of optical diffraction elements.展开更多
Holographic recording analysis was performed on the films that were sensitized with ammonium dichromate with albumin of hen and quail (Gallus gallus and Callipepla cali) as abiopolymeric photosensitive matrix. The sam...Holographic recording analysis was performed on the films that were sensitized with ammonium dichromate with albumin of hen and quail (Gallus gallus and Callipepla cali) as abiopolymeric photosensitive matrix. The samples were exposed to an He-Cd laser, λ = 442 nm, at various concentrations, and diffraction efficiencies were measured as a function to the energy, thickness, protein density, aging time, and spatial frequencies. The photosensitivity was measured as a function of storage time, and the gratings were recorded in real time. The photochemical processes involved in the formation of holographic image are described. The results indicate the behavior of colloidal systems based on albumin bird build holographic recording materials.展开更多
To study the selective erasure and rewriting of the multiplexed holographic storage inphotorefractive crystals.According to the mechanism on forming of phase hologram in photore-fractive crystal,by incoherently additi...To study the selective erasure and rewriting of the multiplexed holographic storage inphotorefractive crystals.According to the mechanism on forming of phase hologram in photore-fractive crystal,by incoherently addition of the complementary hologram and the original holo-gram,the selective erasure and rewriting were accomplished.The complementary holography isan effective and convenient technique for selective erasure and rewriting of multiplexed holo-graphic storage in photorefractive crystals.展开更多
Multimodal imaging,including augmented or mixed reality,transforms the physicians’interaction with clinical imaging,allowing more accurate data interpretation,better spatial resolution,and depth perception of the pat...Multimodal imaging,including augmented or mixed reality,transforms the physicians’interaction with clinical imaging,allowing more accurate data interpretation,better spatial resolution,and depth perception of the patient’s anatomy.We successfully overlay 3D holographic visualization to magnetic resonance imaging images for preoperative decision making of a complex case of cardiac tumour in a 7-year-old girl.展开更多
To reduce the computing time of composite computer-generated holograms （CGHs） gen- eration based upon the angular projection algorithm for holographic three-dimensional （3D） display, a grid-based holographic displ...To reduce the computing time of composite computer-generated holograms （CGHs） gen- eration based upon the angular projection algorithm for holographic three-dimensional （3D） display, a grid-based holographic display （ GHD ） scheme was designed. The grid computing technology was applied to numerically process the different angular projections of an object in distributed-parallel manner to create the corresponding CGHs. The whole treatment of a projection was regarded as a job executed on the grid node machine. The number of jobs which were submitted to grid nodes, therefore, was equal to that of the projections of the object. A Condor-based grid testbed was constructed to verify the feasibility of the GHD scheme, and a graphical user interface （GUI） program and several service modules were developed for it. A 3D terrain model as an example was processed on the testbed. The result showed that the scheme was feasible and able to improve the execution elficiency greatly.展开更多
Holograms provide a characteristic manner to display and convey information, and have been improved to provide better user interactions Holographic interactions are important as they improve user interactions with vir...Holograms provide a characteristic manner to display and convey information, and have been improved to provide better user interactions Holographic interactions are important as they improve user interactions with virtual objects. Gesture interaction is a recent research topic, as it allows users to use their bare hands to directly interact with the hologram. However, it remains unclear whether real hand gestures are well suited for hologram applications. Therefore, we discuss the development process and implementation of three-dimensional object manipulation using natural hand gestures in a hologram. We describe the design and development process for hologram applications and its integration with real hand gesture interactions as initial findings. Experimental results from Nasa TLX form are discussed. Based on the findings, we actualize the user interactions in the hologram.展开更多
Coherence preserves phase consistency between wavefields,enabling accurate recording and reconstruction in holography.Although recent advances in computational optics have realized holographic data acquisition using i...Coherence preserves phase consistency between wavefields,enabling accurate recording and reconstruction in holography.Although recent advances in computational optics have realized holographic data acquisition using incoherent light by computationally retrieving information,optical reconstruction still requires partially coherent light sources.We demonstrate a hologram that reconstructs 3-dimensional distribution utilizing incoherence.By decomposing incoherent light into infinitesimal coherent lights and calculating their propagations,the incoherent sum is optimized to resemble the desired 3-dimensional scene,whereas individual coherent lights reconstruct completely different intensities.Incoherence provides high image quality and a wide eyebox,with the reconstructed intensity remaining shift-invariant under pupil displacement,allowing a 1000-fold expansion of the eyebox.We confirm the shift-invariance through a proof-of-concept experiment and demonstrate real-time synthesis of incoherent holograms using a neural network,significantly reducing computational costs.Our method could inspire new approaches in photonics using incoherent light and be practically adopted in holographic displays.展开更多
The generation of tunably focused light at remote locations is a critical photonic functionality for a wide range of applications.Here,we present a novel concept in the emerging field of Metafibers that achieves,for t...The generation of tunably focused light at remote locations is a critical photonic functionality for a wide range of applications.Here,we present a novel concept in the emerging field of Metafibers that achieves,for the first time,fast,alignment-free,fiber-integrated spatial focus control in a monolithic arrangement.This is enabled by 3D nanoprinted intensity-sensitive phase-only on-fiber holograms,which establish a direct correlation between the intensity distribution in the hologram plane and the focus position.Precise adjustment to the relative power between the modes of a dual-core fiber generates a power-controlled interference pattern within the hologram,enabling controlled and dynamic focus shifts.This study addresses all relevant aspects,including computational optimization,advanced 3D nanoprinting,and tailored fiber fabrication.Experimental results supported by simulations validate the feasibility and efficiency of this monolithic Metafiber platform,which enables fast focus modulation and has transformative potential in optical manipulation,high-speed laser micromachining,telecommunications,and minimally invasive surgery.展开更多
With the escalating laser peak power,modulating and detecting the intensity,duration,phase and polarization of ultraintense laser pulses progressively becomes increasingly arduous due to the limited damage thresholds ...With the escalating laser peak power,modulating and detecting the intensity,duration,phase and polarization of ultraintense laser pulses progressively becomes increasingly arduous due to the limited damage thresholds of conventional optical components.In particular,the generation and detection of ultra-intense vortex lasers pose great challenges for current laser technologies,which has limited the widely potential applications of relativistic vortex lasers in various domains.In this study,we propose to reconstruct the vortex phase and generate and amplify the relativistic vortex lasers via surface plasma holograms(SPHs).By interfering with the object laser and reference laser,SPHs are formed on the target and the phase of the interfering laser is imprinted through the modulation of surface plasma density.In particular,using the quadrature phase-shift interference,the vortex phase of the object laser can be well reconstructed.The generated vortex lasers can be focused and enhanced further by one order of magnitude,up to 1.7×10^(21)W/cm^(2),which has been demonstrated by full three-dimensional particle-in-cell simulations.For the first time,we provide a practical way to detect the phase of relativistic vortex lasers,which can be applied in large 1–10 PW laser facilities.This will promote future experimental research of vortex-laser–plasma interaction and open a new avenue of plasma optics in the ultra-relativistic regime.展开更多
Ultracompact metasurfaces have gained a high reputation for manipulating light fields precisely within a subwavelength scale,bringing great development to the fields of nanophotonics,integrated optics,and quantum tech...Ultracompact metasurfaces have gained a high reputation for manipulating light fields precisely within a subwavelength scale,bringing great development to the fields of nanophotonics,integrated optics,and quantum technology.There is broad interest in expanding the working band of metasurfaces to expand functionalities and the scope of applications.However,increasing the number of working wavelengths multiplexed in a single holographic metasurface is always complicated by two vital issues,i.e.,spectral cross talk and the efficiency imbalance between different wavelength channels.Therefore,holographic metasurfaces with multiplexed working wavelengths over three are seldom reported.To address these two issues,we present a design strategy based on unevenly distributed pixels(UEDPs).As a proof of concept,a UEDP-based metasurface is designed to offer a camouflage method to hide four encrypted holographic images in a multicolor printed image.Our results not only demonstrate the idea of UEDP as an easy-to-implement and effective way for strengthening the wavelength multiplexing of metasurfaces but also give rise to a camouflage metasurface by integrating high-capacity and high-security encrypted holographic information with a single printed image.We believe that the generic UEDP-based metasurface design strategy can be readily extended to the realization of artificial functional structures in various disciplines,such as optics,thermology,and acoustics.展开更多
Reprogrammable metasurfaces,which establish a fascinating bridge between physical and information domains,can dynamically control electromagnetic(EM)waves in real time and thus have attracted great attentions from res...Reprogrammable metasurfaces,which establish a fascinating bridge between physical and information domains,can dynamically control electromagnetic(EM)waves in real time and thus have attracted great attentions from researchers around the world.To control EM waves with an arbitrary polarization state,it is desirable that a complete set of basis states be controlled independently since incident EM waves with an arbitrary polarization state can be decomposed as a linear sum of these basis states.In this work,we present the concept of complete-basis-reprogrammable coding metasurface(CBR-CM)in reflective manners,which can achieve independently dynamic controls over the reflection phases while maintaining the same amplitude for left-handed circularly polarized(LCP)waves and right-handed circularly polarized(RCP)waves.Since LCP and RCP waves together constitute a complete basis set of planar EM waves,dynamicallycontrolled holograms can be generated under arbitrarily polarized wave incidence.The dynamically reconfigurable metaparticle is implemented to demonstrate the CBR-CM’s robust capability of controlling the longitudinal and transverse positions of holograms under LCP and RCP waves independently.It’s expected that the proposed CBR-CM opens up ways of realizing more sophisticated and advanced devices with multiple independent information channels,which may provide technical assistance for digital EM environment reproduction.展开更多
Secret sharing is a promising technology for information encryption by splitting the secret information into different shares.However,the traditional scheme suffers from information leakage in decryption process since...Secret sharing is a promising technology for information encryption by splitting the secret information into different shares.However,the traditional scheme suffers from information leakage in decryption process since the amount of available information channels is limited.Herein,we propose and demonstrate an optical secret sharing framework based on the multi-dimensional multiplexing liquid crystal(LC)holograms.The LC holograms are used as spatially separated shares to carry secret images.The polarization of the incident light and the distance between different shares are served as secret keys,which can significantly improve the information security and capacity.Besides,the decryption condition is also restricted by the applied external voltage due to the variant diffraction efficiency,which further increases the information security.In implementation,an artificial neural network(ANN)model is developed to carefully design the phase distribution of each LC hologram.With the advantage of high security,high capacity and simple configuration,our optical secret sharing framework has great potentials in optical encryption and dynamic holographic display.展开更多
Interferometric optical testing using computer-generated hologram （CGH） can give highly accurate measurement of aspheric surfaces has been proved. After the system is designed, a phase function is obtained according...Interferometric optical testing using computer-generated hologram （CGH） can give highly accurate measurement of aspheric surfaces has been proved. After the system is designed, a phase function is obtained according to the CGH＇s surface plane. For the requirement of accuracy, an optimization algorithm that transfers the phase function into a certain mask pattern file is presented in this letter, based on the relationship between the pattern error of CGH and the output wavefront accuracy. Then the writing machine is able to fabricate such a mask with this kind of file. With that mask, an improved procedure on fabrication of phase type CGH is also presented. Interferometrie test results of an aspherie surface show that the whole test system obtains the demanded accuracy.展开更多
Shaping either the spatial or the spectral output of a nonlinear interaction is accomplished by introducing basic concepts of computer-generated holography into the nonlinear optics regime. The possibilities of arbitr...Shaping either the spatial or the spectral output of a nonlinear interaction is accomplished by introducing basic concepts of computer-generated holography into the nonlinear optics regime. The possibilities of arbitrarily spatially shaping the result of a nonlinear interaction are presented for different phase-matching schemes allowing for both one- and two-dimensional shaping. Shaping the spectrum of a beam in nonlinear interaction is also possible by utilizing similar holographic techniques. The novel and complete control of the output of a nonlinear interaction opens exciting options in the fields of particle manipulation, optical communications, spectroscopy and quantum information.展开更多
A three-dimensional （3D） object reconstruction technique that uses pure-phase computer-generated holograms （CGHs） and a phase-only spatial light modulator （SLM） is proposed. The full parallax CGHs are generated ...A three-dimensional （3D） object reconstruction technique that uses pure-phase computer-generated holograms （CGHs） and a phase-only spatial light modulator （SLM） is proposed. The full parallax CGHs are generated by the point source method and the wave-oriented method without paraxial approximation. Different from conventional CGHs, the pure-phase information on the hologram plane is loaded on the SLM to reconstruct the 3D diffusive objects without considering the reference wave. This technique is more efficient in its utilization of the space-bandwidth product of the SLMs. Numerical simulations and experiments are performed, and the results show that our proposed method can reconstruct 3D diffusive objects successfully.展开更多
We have been studying various types of computer-generated holograms for three-dimensional （3D） displays both for a real-time holographic video display and a hard copy, or a printed hologram. For the hard copy output...We have been studying various types of computer-generated holograms for three-dimensional （3D） displays both for a real-time holographic video display and a hard copy, or a printed hologram. For the hard copy output, we have developed a direct fringe printer, which is achieved to print over 100 gigapixels computer-generated hologram with 0.44μm pitch. In this paper, we introduce our recent progresses on the rainbow hologram, the cylindrical holograms, and the disk hologram for 3D display.展开更多
Interferometric optical testing using computer-generated hologram （CGH） has provided an approach to highly accurate measurement of aspheric surfaces. While designing the CGH null correctors, we should make them with...Interferometric optical testing using computer-generated hologram （CGH） has provided an approach to highly accurate measurement of aspheric surfaces. While designing the CGH null correctors, we should make them with as small aperture and low spatial frequency as possible, and with no zero slope of phase except at center, for the sake of insuring low risk of substrate figure error and feasibility of fabrication. On the basis of classic optics, a set of equations for calculating the phase function of CGH are obtained. These equations lead us to find the dependence of the aperture and spatial frequency on the axial distance from the tested aspheric surface for the CGH. We also simulate the optical path difference error of the CGH relative to the accuracy of controlling laser spot during fabrication. Meanwhile, we discuss the constraints used to avoid zero slope of phase except at center and give a design result of the CGH for the tested aspheric surface. The results ensure the feasibility of designing a useful CGH to test aspheric surface fundamentally.展开更多
We propose a new correction method for the splicing dislocation of sub-holograms in synthetic aperture digital holography. By adjusting the splicing distances between sub-holograms during the numerical recon- structio...We propose a new correction method for the splicing dislocation of sub-holograms in synthetic aperture digital holography. By adjusting the splicing distances between sub-holograms during the numerical recon- struction process using the convolution approach, the influence of non-paraxial aberration for the quality of the synthetic reconstructed image is avoided and synthetic reconstructed images corresponding to different splicing distances are obtained. Then, the accurate splicing distance between sub-holograms is determined by evaluating the quality of the corresponding synthetic reconstructed images. Accurate correction for the splicing dislocation of sub-holograms is achieved and high-quality reconstructed images without non- Daraxial aberration are obtained.展开更多
We propose a method for color electroholography using a simple red-green-blue （RGB） gradation representa- tion method without controlling the respective brightness of tile reference RGB-colored lights. The proposed ...We propose a method for color electroholography using a simple red-green-blue （RGB） gradation representa- tion method without controlling the respective brightness of tile reference RGB-colored lights. The proposed method uses RGB multiple bit planes comprising RGB binary-weighted computer-generated holograms with various light transmittanees. The object points of a given three-dimensional （3D） object are assigned to RGB nmltiple bit planes according to their RGB gradation levels. The RGB multiple bit planes are sequentially displayed in a tim-division-multiplexe- manner. Consequently, the proposed method yields a color gradation representation of a reconstructed 3D object.展开更多
The wavefront recording plane （WRP）, subsequently generalized to be known as the virtual diffraction plane （VDP）, is a recent concept that has been successfully deployed in fast generation and processing of digita...The wavefront recording plane （WRP）, subsequently generalized to be known as the virtual diffraction plane （VDP）, is a recent concept that has been successfully deployed in fast generation and processing of digital holograms. In brief, the WRP and its extension, the VDP, is a hypothetical plane that is located between the hologram and the object scene, and which is at close proximity to the latter. As such, the fringe patterns on the hypothetical plane are carrying the holistic information of the hologram, as well as the local optical properties of the object scene. This important property enables a hologram to be processed with classical image processing techniques that are normally unsuitable for handling holographic information. In this paper we shall review a number of works, that have been developed based on the framework of the WRP and the VDP.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No.62205350)the Special Project of Central Government Guiding Local Science and Technology Development in Beijing 2020 (Grant No.Z20111000430000)the Guangxi Nanning Key R&D Program (Grant No.20233067)。
文摘Computer-generated holography technology has been widely applied,and as research in this field deepens,the demand for memory and computational power in small AR and VR devices continues to increase.This paper presents a hologram generation method,i.e.,a symmetrically high-compressed look-up table method,which can reduce memory usage by50%.In offline computing,half of the basic horizontal and vertical modulation factors are stored,halving the memory requirements without affecting inline speed.Currently,its potential extends to various holographic applications,including the production of optical diffraction elements.
基金Thanks are due to The Instituto Nacional de Astrofisica Optica y Electronica(INAOE)for the infrastructure and economic support received.
文摘Holographic recording analysis was performed on the films that were sensitized with ammonium dichromate with albumin of hen and quail (Gallus gallus and Callipepla cali) as abiopolymeric photosensitive matrix. The samples were exposed to an He-Cd laser, λ = 442 nm, at various concentrations, and diffraction efficiencies were measured as a function to the energy, thickness, protein density, aging time, and spatial frequencies. The photosensitivity was measured as a function of storage time, and the gratings were recorded in real time. The photochemical processes involved in the formation of holographic image are described. The results indicate the behavior of colloidal systems based on albumin bird build holographic recording materials.
文摘To study the selective erasure and rewriting of the multiplexed holographic storage inphotorefractive crystals.According to the mechanism on forming of phase hologram in photore-fractive crystal,by incoherently addition of the complementary hologram and the original holo-gram,the selective erasure and rewriting were accomplished.The complementary holography isan effective and convenient technique for selective erasure and rewriting of multiplexed holo-graphic storage in photorefractive crystals.
文摘Multimodal imaging,including augmented or mixed reality,transforms the physicians’interaction with clinical imaging,allowing more accurate data interpretation,better spatial resolution,and depth perception of the patient’s anatomy.We successfully overlay 3D holographic visualization to magnetic resonance imaging images for preoperative decision making of a complex case of cardiac tumour in a 7-year-old girl.
文摘To reduce the computing time of composite computer-generated holograms （CGHs） gen- eration based upon the angular projection algorithm for holographic three-dimensional （3D） display, a grid-based holographic display （ GHD ） scheme was designed. The grid computing technology was applied to numerically process the different angular projections of an object in distributed-parallel manner to create the corresponding CGHs. The whole treatment of a projection was regarded as a job executed on the grid node machine. The number of jobs which were submitted to grid nodes, therefore, was equal to that of the projections of the object. A Condor-based grid testbed was constructed to verify the feasibility of the GHD scheme, and a graphical user interface （GUI） program and several service modules were developed for it. A 3D terrain model as an example was processed on the testbed. The result showed that the scheme was feasible and able to improve the execution elficiency greatly.
文摘Holograms provide a characteristic manner to display and convey information, and have been improved to provide better user interactions Holographic interactions are important as they improve user interactions with virtual objects. Gesture interaction is a recent research topic, as it allows users to use their bare hands to directly interact with the hologram. However, it remains unclear whether real hand gestures are well suited for hologram applications. Therefore, we discuss the development process and implementation of three-dimensional object manipulation using natural hand gestures in a hologram. We describe the design and development process for hologram applications and its integration with real hand gesture interactions as initial findings. Experimental results from Nasa TLX form are discussed. Based on the findings, we actualize the user interactions in the hologram.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIT)(No.RS-2023-00245184 and RS-2024-00341142)。
文摘Coherence preserves phase consistency between wavefields,enabling accurate recording and reconstruction in holography.Although recent advances in computational optics have realized holographic data acquisition using incoherent light by computationally retrieving information,optical reconstruction still requires partially coherent light sources.We demonstrate a hologram that reconstructs 3-dimensional distribution utilizing incoherence.By decomposing incoherent light into infinitesimal coherent lights and calculating their propagations,the incoherent sum is optimized to resemble the desired 3-dimensional scene,whereas individual coherent lights reconstruct completely different intensities.Incoherence provides high image quality and a wide eyebox,with the reconstructed intensity remaining shift-invariant under pupil displacement,allowing a 1000-fold expansion of the eyebox.We confirm the shift-invariance through a proof-of-concept experiment and demonstrate real-time synthesis of incoherent holograms using a neural network,significantly reducing computational costs.Our method could inspire new approaches in photonics using incoherent light and be practically adopted in holographic displays.
基金German Research Foundation(DFG)via the grants SCHM2655/21-1,SCHM2655/23-1,QI 140/2-1。
文摘The generation of tunably focused light at remote locations is a critical photonic functionality for a wide range of applications.Here,we present a novel concept in the emerging field of Metafibers that achieves,for the first time,fast,alignment-free,fiber-integrated spatial focus control in a monolithic arrangement.This is enabled by 3D nanoprinted intensity-sensitive phase-only on-fiber holograms,which establish a direct correlation between the intensity distribution in the hologram plane and the focus position.Precise adjustment to the relative power between the modes of a dual-core fiber generates a power-controlled interference pattern within the hologram,enabling controlled and dynamic focus shifts.This study addresses all relevant aspects,including computational optimization,advanced 3D nanoprinting,and tailored fiber fabrication.Experimental results supported by simulations validate the feasibility and efficiency of this monolithic Metafiber platform,which enables fast focus modulation and has transformative potential in optical manipulation,high-speed laser micromachining,telecommunications,and minimally invasive surgery.
基金supported by the National Natural Science Foundation of China(Grant Nos.12375244,12305265,12135009 and 12174047)the Natural Science Foundation of Hunan Province of China(Grant No.2025JJ30002)。
文摘With the escalating laser peak power,modulating and detecting the intensity,duration,phase and polarization of ultraintense laser pulses progressively becomes increasingly arduous due to the limited damage thresholds of conventional optical components.In particular,the generation and detection of ultra-intense vortex lasers pose great challenges for current laser technologies,which has limited the widely potential applications of relativistic vortex lasers in various domains.In this study,we propose to reconstruct the vortex phase and generate and amplify the relativistic vortex lasers via surface plasma holograms(SPHs).By interfering with the object laser and reference laser,SPHs are formed on the target and the phase of the interfering laser is imprinted through the modulation of surface plasma density.In particular,using the quadrature phase-shift interference,the vortex phase of the object laser can be well reconstructed.The generated vortex lasers can be focused and enhanced further by one order of magnitude,up to 1.7×10^(21)W/cm^(2),which has been demonstrated by full three-dimensional particle-in-cell simulations.For the first time,we provide a practical way to detect the phase of relativistic vortex lasers,which can be applied in large 1–10 PW laser facilities.This will promote future experimental research of vortex-laser–plasma interaction and open a new avenue of plasma optics in the ultra-relativistic regime.
基金supported by the Innovation and Technology Commission of Hong Kong(Grant No.GHP/026/19GD)the Research Grants Council of Hong Kong(Grant No.Ao E/P-502/20)+3 种基金the National Key R&D Program of China(Grant No.2021YFA1400804)the National Natural Science Foundation of China(Grant No.12222415)the Guangdong Natural Science Fund(Grant Nos.2024B1515040013 and 2020A0505140004)the Guangdong Provincial Quantum Science Strategic Initiative(Grant No.GDZX2305005)。
文摘Ultracompact metasurfaces have gained a high reputation for manipulating light fields precisely within a subwavelength scale,bringing great development to the fields of nanophotonics,integrated optics,and quantum technology.There is broad interest in expanding the working band of metasurfaces to expand functionalities and the scope of applications.However,increasing the number of working wavelengths multiplexed in a single holographic metasurface is always complicated by two vital issues,i.e.,spectral cross talk and the efficiency imbalance between different wavelength channels.Therefore,holographic metasurfaces with multiplexed working wavelengths over three are seldom reported.To address these two issues,we present a design strategy based on unevenly distributed pixels(UEDPs).As a proof of concept,a UEDP-based metasurface is designed to offer a camouflage method to hide four encrypted holographic images in a multicolor printed image.Our results not only demonstrate the idea of UEDP as an easy-to-implement and effective way for strengthening the wavelength multiplexing of metasurfaces but also give rise to a camouflage metasurface by integrating high-capacity and high-security encrypted holographic information with a single printed image.We believe that the generic UEDP-based metasurface design strategy can be readily extended to the realization of artificial functional structures in various disciplines,such as optics,thermology,and acoustics.
基金supported by the National Natural Science Foundation of China (62101588)the National Key Research and Development Program of China (SQ2022YFB3806200)+1 种基金the Young Talent Fund of Association for Science and Technology in Shaanxi (20240129)the Postdoctoral Fellowship Program of CPSF (GZC20242285)
文摘Reprogrammable metasurfaces,which establish a fascinating bridge between physical and information domains,can dynamically control electromagnetic(EM)waves in real time and thus have attracted great attentions from researchers around the world.To control EM waves with an arbitrary polarization state,it is desirable that a complete set of basis states be controlled independently since incident EM waves with an arbitrary polarization state can be decomposed as a linear sum of these basis states.In this work,we present the concept of complete-basis-reprogrammable coding metasurface(CBR-CM)in reflective manners,which can achieve independently dynamic controls over the reflection phases while maintaining the same amplitude for left-handed circularly polarized(LCP)waves and right-handed circularly polarized(RCP)waves.Since LCP and RCP waves together constitute a complete basis set of planar EM waves,dynamicallycontrolled holograms can be generated under arbitrarily polarized wave incidence.The dynamically reconfigurable metaparticle is implemented to demonstrate the CBR-CM’s robust capability of controlling the longitudinal and transverse positions of holograms under LCP and RCP waves independently.It’s expected that the proposed CBR-CM opens up ways of realizing more sophisticated and advanced devices with multiple independent information channels,which may provide technical assistance for digital EM environment reproduction.
基金support from the National Natural Science Foundation of China (No.62005164,62222507,62175101,and 62005166)the Shanghai Natural Science Foundation (23ZR1443700)+3 种基金Shuguang Program of Shanghai Education Development Foundation and Shanghai Municipal Education Commission (23SG41)the Young Elite Scientist Sponsorship Program by CAST (No.20220042)Science and Technology Commission of Shanghai Municipality (Grant No.21DZ1100500)the Shanghai Municipal Science and Technology Major Project,and the Shanghai Frontiers Science Center Program (2021-2025 No.20).
文摘Secret sharing is a promising technology for information encryption by splitting the secret information into different shares.However,the traditional scheme suffers from information leakage in decryption process since the amount of available information channels is limited.Herein,we propose and demonstrate an optical secret sharing framework based on the multi-dimensional multiplexing liquid crystal(LC)holograms.The LC holograms are used as spatially separated shares to carry secret images.The polarization of the incident light and the distance between different shares are served as secret keys,which can significantly improve the information security and capacity.Besides,the decryption condition is also restricted by the applied external voltage due to the variant diffraction efficiency,which further increases the information security.In implementation,an artificial neural network(ANN)model is developed to carefully design the phase distribution of each LC hologram.With the advantage of high security,high capacity and simple configuration,our optical secret sharing framework has great potentials in optical encryption and dynamic holographic display.
文摘Interferometric optical testing using computer-generated hologram （CGH） can give highly accurate measurement of aspheric surfaces has been proved. After the system is designed, a phase function is obtained according to the CGH＇s surface plane. For the requirement of accuracy, an optimization algorithm that transfers the phase function into a certain mask pattern file is presented in this letter, based on the relationship between the pattern error of CGH and the output wavefront accuracy. Then the writing machine is able to fabricate such a mask with this kind of file. With that mask, an improved procedure on fabrication of phase type CGH is also presented. Interferometrie test results of an aspherie surface show that the whole test system obtains the demanded accuracy.
基金supported by the Israel Science Foundation(1310/13)the Israeli Ministry of Science,Technology and Space in the framework of the Israel–Italy bi-national collaboration program
文摘Shaping either the spatial or the spectral output of a nonlinear interaction is accomplished by introducing basic concepts of computer-generated holography into the nonlinear optics regime. The possibilities of arbitrarily spatially shaping the result of a nonlinear interaction are presented for different phase-matching schemes allowing for both one- and two-dimensional shaping. Shaping the spectrum of a beam in nonlinear interaction is also possible by utilizing similar holographic techniques. The novel and complete control of the output of a nonlinear interaction opens exciting options in the fields of particle manipulation, optical communications, spectroscopy and quantum information.
基金supported by the Innovation Team Development Program of the Ministry of Education of China (No IRT0606)the National Basic Research Program of China (No 2006CB302901)
文摘A three-dimensional （3D） object reconstruction technique that uses pure-phase computer-generated holograms （CGHs） and a phase-only spatial light modulator （SLM） is proposed. The full parallax CGHs are generated by the point source method and the wave-oriented method without paraxial approximation. Different from conventional CGHs, the pure-phase information on the hologram plane is loaded on the SLM to reconstruct the 3D diffusive objects without considering the reference wave. This technique is more efficient in its utilization of the space-bandwidth product of the SLMs. Numerical simulations and experiments are performed, and the results show that our proposed method can reconstruct 3D diffusive objects successfully.
基金A part of this work was supported by JSPS KAKENHI21760265
文摘We have been studying various types of computer-generated holograms for three-dimensional （3D） displays both for a real-time holographic video display and a hard copy, or a printed hologram. For the hard copy output, we have developed a direct fringe printer, which is achieved to print over 100 gigapixels computer-generated hologram with 0.44μm pitch. In this paper, we introduce our recent progresses on the rainbow hologram, the cylindrical holograms, and the disk hologram for 3D display.
文摘Interferometric optical testing using computer-generated hologram （CGH） has provided an approach to highly accurate measurement of aspheric surfaces. While designing the CGH null correctors, we should make them with as small aperture and low spatial frequency as possible, and with no zero slope of phase except at center, for the sake of insuring low risk of substrate figure error and feasibility of fabrication. On the basis of classic optics, a set of equations for calculating the phase function of CGH are obtained. These equations lead us to find the dependence of the aperture and spatial frequency on the axial distance from the tested aspheric surface for the CGH. We also simulate the optical path difference error of the CGH relative to the accuracy of controlling laser spot during fabrication. Meanwhile, we discuss the constraints used to avoid zero slope of phase except at center and give a design result of the CGH for the tested aspheric surface. The results ensure the feasibility of designing a useful CGH to test aspheric surface fundamentally.
基金supported by the National Natural Science Foundation of China under Grant (Nos. 61077008and 61127011)the Northwestern Polytechnical University (NPU) Foundation for Fundamental Research(No. JC20100237)
文摘We propose a new correction method for the splicing dislocation of sub-holograms in synthetic aperture digital holography. By adjusting the splicing distances between sub-holograms during the numerical recon- struction process using the convolution approach, the influence of non-paraxial aberration for the quality of the synthetic reconstructed image is avoided and synthetic reconstructed images corresponding to different splicing distances are obtained. Then, the accurate splicing distance between sub-holograms is determined by evaluating the quality of the corresponding synthetic reconstructed images. Accurate correction for the splicing dislocation of sub-holograms is achieved and high-quality reconstructed images without non- Daraxial aberration are obtained.
基金supported by the Japan Society for the Promotion of Science through a Grant-in-Aid for Scientific Research(C)(No.15K00153)
文摘We propose a method for color electroholography using a simple red-green-blue （RGB） gradation representa- tion method without controlling the respective brightness of tile reference RGB-colored lights. The proposed method uses RGB multiple bit planes comprising RGB binary-weighted computer-generated holograms with various light transmittanees. The object points of a given three-dimensional （3D） object are assigned to RGB nmltiple bit planes according to their RGB gradation levels. The RGB multiple bit planes are sequentially displayed in a tim-division-multiplexe- manner. Consequently, the proposed method yields a color gradation representation of a reconstructed 3D object.
文摘The wavefront recording plane （WRP）, subsequently generalized to be known as the virtual diffraction plane （VDP）, is a recent concept that has been successfully deployed in fast generation and processing of digital holograms. In brief, the WRP and its extension, the VDP, is a hypothetical plane that is located between the hologram and the object scene, and which is at close proximity to the latter. As such, the fringe patterns on the hypothetical plane are carrying the holistic information of the hologram, as well as the local optical properties of the object scene. This important property enables a hologram to be processed with classical image processing techniques that are normally unsuitable for handling holographic information. In this paper we shall review a number of works, that have been developed based on the framework of the WRP and the VDP.
