Holographic display has attracted widespread interest because of its ability to show the complete information of the object and bring people an unprecedented sense of presence. The absence of ideal recording materials...Holographic display has attracted widespread interest because of its ability to show the complete information of the object and bring people an unprecedented sense of presence. The absence of ideal recording materials has hampered the realization of their commercial applications. Here we report that the response time of a bismuth and magnesium codoped lithium niobate(LN:Bi,Mg) crystal is shortened to 7.2 ms and a sensitivity as high as 646 cm/J. The crystal was used to demonstrate a real-time holographic display with a refresh rate of 60 Hz, as that of the popular high-definition television. Moreover, the first-principles calculations indicate that the electron mobility while Bi occupying Nb-site is significantly greater than that in Li-site, which directly induces the fast response of LN:Bi,Mg crystals when the concentration of Mg is above its doping threshold.展开更多
The metasurface possesses great potential in a 3D holographic display due to its powerful ability to manipulate optical fields,ultracompact structure,and extraordinary information capacity.However,the in-plane and int...The metasurface possesses great potential in a 3D holographic display due to its powerful ability to manipulate optical fields,ultracompact structure,and extraordinary information capacity.However,the in-plane and interplane crosstalk caused by the coupling between the meta-atoms of the current 3D holographic metasurface limits the quality of the reconstructed image,which has become a significant obstacle to high-performance 3D display applications.Additionally,the interleaved or multilayer design strategy of metasurfaces increases the complexity of structural design and manufacturing,facing challenges in meeting the requirements for miniaturization and low cost-effectiveness.Here,we propose a strategy for a free-space 3D multiplane color holographic multiplex display based on a single-cell metasurface.By utilizing a modified holographic optimization strategy,multiple holographic information is encoded into three mutually independent bases of incident photons and integrated into a metasurface,thereby creating high-quality 3D vectorial metaholography with minimal crosstalk across the visible spectrum.展开更多
On-chip metasurfaces have been exploited to manipulate guided waves into free space with desired wavefronts and bridge the gap between guided modes and free-space optical fields.However,existing on-chip metasurfaces f...On-chip metasurfaces have been exploited to manipulate guided waves into free space with desired wavefronts and bridge the gap between guided modes and free-space optical fields.However,existing on-chip metasurfaces for guided wave radiation typically lack dynamic tunability and high-capacity multiplexing for their practical applications.Here,we present a dynamic waveguide-based holographic display enabled by on-chip metasurface network on lithium niobate on insulator platform.Based on geometric phase and detour phase,an on-chip multiplexed metasurface network implemented on a 2×2 waveguide crossing array is incorporated with a two-stage lithium niobate(LN)switch to construct an addressable framework.Benefiting from the multiplexing capability of on-chip metasurface and the fast electro-optical response of LN modulators,guided wave radiation in the form of eight holographic images is tunable and addressable at high speeds.This work exemplifies a scalable approach for dynamic manipulation of guided signals and paves the way towards holographic displays,high-capacity optical communications and integrated photonic information processing.展开更多
This Letter describes an approach to encode complex-amplitude light waves with spatiotemporal double-phase holograms(DPHs) for overcoming the limit of the space-bandwidth product(SBP) delivered by existing methods. To...This Letter describes an approach to encode complex-amplitude light waves with spatiotemporal double-phase holograms(DPHs) for overcoming the limit of the space-bandwidth product(SBP) delivered by existing methods. To construct DPHs, two spatially macro-pixel encoded phase components are employed in the SBP-preserved resampling of complex holograms. Four generated sub-DPHs are displayed sequentially in time for high-quality holographic image reconstruction without reducing the image size or discarding any image terms when the DPHs are interweaved. The reconstructed holographic images contain more details and less speckle noise, with their signal-to-noise ratio and structure similarity index being improved by 14.64% and 78.79%,respectively.展开更多
Two different methods from graphic processing unit （GPU） and central processing unit （CPU） are proposed to suitably optimize look-up table algorithms of computer generated holography （CGH）. The numerical simula-...Two different methods from graphic processing unit （GPU） and central processing unit （CPU） are proposed to suitably optimize look-up table algorithms of computer generated holography （CGH）. The numerical simula- tions and experimental results show that we can reconstruct a good quality object. The computation of CGH for a three-dimensional （3D） dynamic holographic display can also be sped up by programming with our proposed method. It can optimize both file loading and the inline calculation process. The phase-only CGH with gigabyte data for reconstructing 10 MB object samplings is generated. In addition, the proposed method effectively re- duced time costs of loading and writing offline tables on a CPU. It is believed the proposed method can provide high speed and huge data CGH for 3D dynamic holographic displays in the near future.展开更多
In order to realize holographic display of three-dimensional （3D） objects and suppress zero-order light, conjugate image, and speckle noise, a novel method is proposed based on multiple fractional Fourier transform ...In order to realize holographic display of three-dimensional （3D） objects and suppress zero-order light, conjugate image, and speckle noise, a novel method is proposed based on multiple fractional Fourier transform （M-FrFT） for cMculating holograms of 3D objects. A series of kinoforms are generated by adding pseudorandom phase factor （PPF） to object planes in calculating each kinoform, and generating the PPF randomly again in the next kinoform calculation. The reconstructed images from kinoform sequence are superposed together in order to suppress the speckle noise of reconstructed image and improve the contrast and detail resolution of the reconstructed images. The qualities of reconstructed images from single amplitude hologram, single kinoform, and kinoform sequence calculated by M-FrFT are compared. The effects of suppressing speckle noise are analyzed by calculating the speckle index of numerical reconstructed images. The analytical results illustrate that, with the proposed method for 3D holographic display, the zero-order light, conjugate image, and speckle noise can be suppressed, and the qualities of reconstructed images can be improved significantly.展开更多
A multiplexed holographic display video has been achieved by using a passive azo-dye-doped liquid crystal （LC） cell. Holograms formed in this cell can be refreshed in the order of several milliseconds. By angular mu...A multiplexed holographic display video has been achieved by using a passive azo-dye-doped liquid crystal （LC） cell. Holograms formed in this cell can be refreshed in the order of several milliseconds. By angular multiplexing technique, dynamically multiplexed holographic videos are realized. Moreover, the reconstructed RGB images are merged into a color image, which illustrates the possibility of a color holographic three-dimensional （3D） display by holographic multiplexing of the LC cell.展开更多
A time-division multiplexing method for computer-generated holograms （CGHs） is proposed to solve the problem of the limited space-bandwidth product. A three-dimensional （3-D） scene is divided into multiple layers ...A time-division multiplexing method for computer-generated holograms （CGHs） is proposed to solve the problem of the limited space-bandwidth product. A three-dimensional （3-D） scene is divided into multiple layers at different depths. The CGH corresponding to each layer is calculated by an angular-spectrum algorithm that is effective at a wide range of propagation distances. All of the CGHs are combined into several group-CGHs. These group-CGHs are sequentially uploaded onto one spatial light modulator at a high frame rate. The spacebandwidth product can be benefited by the time-division processing of the CGHs. The proposed method provides a new approach to achieve high quality 3-D display with a fast and accurate CGH computation.展开更多
We propose a method to improve the quality of the reconstructed images based on compressive sensing principles. The pseudo-inverse matrix and the total variation minimization algorithms are combined to reduce the samp...We propose a method to improve the quality of the reconstructed images based on compressive sensing principles. The pseudo-inverse matrix and the total variation minimization algorithms are combined to reduce the sampling number of the computer generated hologram. Numerical simulations are performed and the results indicate that the peak signal to noise ratio is increased and the sampling ratio is decreased at the same time for holographic display.展开更多
We proposed a method for calculating the computer generated hologram from multi-plane 3D objects by using nonuniform sampled angular spectrum method （NUASM）. Both of the holo-gram plane and the image plane are nonun...We proposed a method for calculating the computer generated hologram from multi-plane 3D objects by using nonuniform sampled angular spectrum method （NUASM）. Both of the holo-gram plane and the image plane are nonuniform sampled according to the distances and positions of the three-dimensional objects. The nonuniform fast Fourier transform （NUFFT） is used to calculate the angular spectrum propagation from the image plane to the hologram plane and the hologram can be calculated in only one step. Simulation and optical experiment results show that the hologram generated in this way can reconstruct objects on multi- planes simultaneously and separately without axial distortion.展开更多
We present holographic storage of three-dimensional（3D） images and data in a photopolymer film without any applied electric field.Its absorption and diffraction efficiency are measured,and reflective analog hologram...We present holographic storage of three-dimensional（3D） images and data in a photopolymer film without any applied electric field.Its absorption and diffraction efficiency are measured,and reflective analog hologram of real object and image of digital information are recorded in the films.The photopolymer is compared with polymer dispersed liquid crystals as holographic materials.Besides holographic diffraction efficiency of the former is little lower than that of the latter,this work demonstrates that the photopolymer is more suitable for analog hologram and big data permanent storage because of its high definition and no need of high voltage electric field.Therefore,our study proposes a potential holographic storage material to apply in large size static 3D holographic displays,including analog hologram displays,digital hologram prints,and holographic disks.展开更多
In this review we will focus on recent progress in the field of two-dimensional（2D） and three-dimensional（3D）display technologies.We present the current display materials and their applications,including organic l...In this review we will focus on recent progress in the field of two-dimensional（2D） and three-dimensional（3D）display technologies.We present the current display materials and their applications,including organic light-emitting diodes（OLEDs）,flexible OLEDs quantum dot light emitting diodes（QLEDs）,active-matrix organic light emitting diodes（AMOLEDs）,electronic paper（E-paper）,curved displays,stereoscopic 3D displays,volumetric 3D displays,light field3 D displays,and holographic 3D displays.Conventional 2D display devices,such as liquid crystal devices（LCDs） often result in ambiguity in high-dimensional data images because of lacking true depth information.This review thus provides a detailed description of 3D display technologies.展开更多
A novel see-through display with a liquid crystal lens array was proposed.A liquid crystal Fresnel lens display（LCFLD） with a holographic screen was demonstrated.The proposed display system has high efficiency,simpl...A novel see-through display with a liquid crystal lens array was proposed.A liquid crystal Fresnel lens display（LCFLD） with a holographic screen was demonstrated.The proposed display system has high efficiency,simple fabrication,and low manufacturing cost due to the absence of a polarizer and color filter.展开更多
Holographic near-eye augmented reality(AR)displays featuring tilted inbound/outbound angles on compact optical combiners hold significant potential yet often struggle to deliver satisfying image quality.This is primar...Holographic near-eye augmented reality(AR)displays featuring tilted inbound/outbound angles on compact optical combiners hold significant potential yet often struggle to deliver satisfying image quality.This is primarily attributed to two reasons:the lack of a robust off-axis-supported phase hologram generation algorithm;and the suboptimal performance of ill-tuned hardware parts such as imperfect holographic optical elements(HOEs).To address these issues,we incorporate a gradient descent-based phase retrieval algorithm with spectrum remapping,allowing for precise hologram generation with wave propagation between nonparallel planes.Further,we apply a camera-calibrated propagation scheme to iteratively optimize holograms,mitigating imperfections arising from the defects in the HOE fabrication process and other hardware parts,thereby significantly lifting the holographic image quality.We build an off-axis holographic near-eye display prototype using off-the-shelf light engine parts and a customized full-color HOE,demonstrating state-of-the-art virtual reality and AR display results.展开更多
Holographic 3D display technology,widely considered the ultimate solution for real 3D display,has broad applications in fields including advertisement,industrial manufacturing and military.However,it is difficult to s...Holographic 3D display technology,widely considered the ultimate solution for real 3D display,has broad applications in fields including advertisement,industrial manufacturing and military.However,it is difficult to simultaneously realize color holographic 3D display with wide viewing angle and high brightness required for an immersive visual experience.Here,a novel holographic 3D display system based on a customized achromatic liquid crystal grating and a phase-only spatial light modulator is proposed.Thanks to the secondary diffraction performed by the achromatic liquid crystal grating,nine secondary diffraction images of red,green and blue channels overlap in space in time sequence.Additionally,a high brightness hologram encoding method is developed,which introduces a frequency loss function with dynamic weights to ensure that differences of all frequency components in the frequency domain can be learned.The proposed method dramatically enhances light energy utilization by a factor of five,resulting in significantly brighter reconstructed images while substantially attenuating background noise in non-target regions.This groundbreaking system,achieving a remarkable~65°wide viewing angle with good image quality and high brightness,represents a significant advancement in holographic technology,offering a comprehensive solution for wide-viewing-angle,high-brightness,color 3D displays with potential applications across diverse technological domains.展开更多
The popularity of deep learning has boosted computer-generated holography(CGH)as a vibrant research field,particularly physics-driven unsupervised learning.Nevertheless,present unsupervised CGH models have not yet exp...The popularity of deep learning has boosted computer-generated holography(CGH)as a vibrant research field,particularly physics-driven unsupervised learning.Nevertheless,present unsupervised CGH models have not yet explored the potential of generating full-color 3D holograms through a unified framework.In this study,we propose a lightweight multiwavelength network model capable of high-fidelity and efficient full-color hologram generation in both 2D and 3D display,called IncepHoloRGB.The high-speed simultaneous generation of RGB holograms at 191 frames per second(FPS)is based on Inception sampling blocks and multi-wavelength propagation module integrated with depth-traced superimposition,achieving an average structural similarity(SSIM)of 0.88 and peak signal-to-noise ratio(PSNR)of 29.00 on the DIV2K test set in reconstruction.Full-color reconstruction of numerical simulations and optical experiments shows that IncepHoloRGB is versatile to diverse scenarios and can obtain authentic full-color holographic 3D display within a unified network model,paving the way for applications towards real-time dynamic naked-eye 3D display,virtual and augmented reality(VR/AR)systems.展开更多
The near-eye display feature in emerging spatial computing systems produces a distinctive visual effect of mixing virtual and real worlds.However,its application for all-day wear is greatly limited by the bulky struct...The near-eye display feature in emerging spatial computing systems produces a distinctive visual effect of mixing virtual and real worlds.However,its application for all-day wear is greatly limited by the bulky structure,energy expenditure,and continuous battery heating.Here,we propose a lightweight holographic near-eye display system that takes advantage of solar energy for self-charging.To guarantee the collection of solar energy and near-eye display without crosstalk,we implement holographic optical elements(HOEs)to diffract sunlight and signal light into a common waveguide.Then,small-area solar cells convert the collected solar energy and power the system.Compact power supply components replace heavy batteries,thus contributing to the lightweight design.The simple acquisition and management of solar energy provide the system with sustainable self-charging capability.We believe that the lightweight design and continuous energy input solution will significantly promote the popularity of near-eye display in our daily lives.展开更多
Holographic display stands as a prominent approach for achieving lifelike three-dimensional(3D)reproductions with continuous depth sensation.However,the generation of a computer-generated hologram(CGH)always relies on...Holographic display stands as a prominent approach for achieving lifelike three-dimensional(3D)reproductions with continuous depth sensation.However,the generation of a computer-generated hologram(CGH)always relies on the repetitive computation of diffraction propagation from point-cloud or multiple depthsliced planar images,which inevitably leads to an increase in computational complexity,making real-time CGH generation impractical.Here,we report a new CGH generation algorithm capable of rapidly synthesizing a 3D hologram in only one-step backward propagation calculation in a novel split Lohmann lens-based diffraction model.By introducing an extra predesigned virtual digital phase modulation of multifocal split Lohmann lens in such a diffraction model,the generated CGH appears to reconstruct 3D scenes with accurate accommodation abilities across the display contents.Compared with the conventional layer-based method,the computation speed of the proposed method is independent of the quantized layer numbers,and therefore can achieve real-time computation speed with a very dense of depth sampling.Both simulation and experimental results validate the proposed method.展开更多
As the fiat panel displays （Liquid Crystal Displays, AMOLED, etc.） reach near perfection in their viewing qualities and display areas, it is natural to seek the next level of displays, including 3D displays. There i...As the fiat panel displays （Liquid Crystal Displays, AMOLED, etc.） reach near perfection in their viewing qualities and display areas, it is natural to seek the next level of displays, including 3D displays. There is a strong surge in 3D liquid crystal displays as a result of the successful movie Avatar. Most of these 3D displays involve the employment of special glasses that allow one view perspective for each of the eyes to achieve a depth perception. Such displays are not real 3D displays. In fact, these displays can only provide one viewing perspective for all viewers, regardless of the viewer＇s position. In addition, a fundamental viewing problem of focusing and accommodation exist that can lead to discomfort and fatigue for many viewers. In this paper, the authors review the current status of stereoscopic 3D displays and their problems. The authors will also discuss the possibility of using fiat panels for the display of both phase and intensity of video image information, leading to the ultimate display of 3D holographic video images. Many of the fundamental issues and limitations will be presented and discussed.展开更多
An ideal holographic 3D display should have the characteristics of large viewing angle,full color,and low speckle noise.However,the viewing angle of the holographic 3D display is usually limited by existing strategies...An ideal holographic 3D display should have the characteristics of large viewing angle,full color,and low speckle noise.However,the viewing angle of the holographic 3D display is usually limited by existing strategies,which vastly hinders its extensive application.In this paper,a large viewing angle holographic 3D display system based on maximum diffraction modulation is proposed.The core of the proposed system comprises the spatial light modulators(SLMs)and liquid crystal grating.We also present a new feasible scheme for the realization of large viewing angle holographic 3D display.This is achieved by considering the maximum diffraction angle of SLM as the limited diffraction modulation range of each image point.By doing so,we could not only give access to the maximum hologram size of the object,but also tune the reconstructed image of secondary diffraction by using a self-engineered liquid crystal grating.More importantly,the proposed maximum diffraction modulation scheme enables the viewing angle of the proposed system to be enlarged to 73.4°.The proposed system has huge application potential in the fields such as education,culture,and entertainment.展开更多
基金The National Key Research and Development Program of China(Grant No.2019YFA0705000)National Natural Science Foundation of China(No.12034010)Program for Changjiang Scholars and Innovative Research Team in University(No.IRT_13R29).
文摘Holographic display has attracted widespread interest because of its ability to show the complete information of the object and bring people an unprecedented sense of presence. The absence of ideal recording materials has hampered the realization of their commercial applications. Here we report that the response time of a bismuth and magnesium codoped lithium niobate(LN:Bi,Mg) crystal is shortened to 7.2 ms and a sensitivity as high as 646 cm/J. The crystal was used to demonstrate a real-time holographic display with a refresh rate of 60 Hz, as that of the popular high-definition television. Moreover, the first-principles calculations indicate that the electron mobility while Bi occupying Nb-site is significantly greater than that in Li-site, which directly induces the fast response of LN:Bi,Mg crystals when the concentration of Mg is above its doping threshold.
基金National Natural Science Foundation of China(61905167)National Key Research and Development Program of China(2020YFA0714001,2021YFC2202203)。
文摘The metasurface possesses great potential in a 3D holographic display due to its powerful ability to manipulate optical fields,ultracompact structure,and extraordinary information capacity.However,the in-plane and interplane crosstalk caused by the coupling between the meta-atoms of the current 3D holographic metasurface limits the quality of the reconstructed image,which has become a significant obstacle to high-performance 3D display applications.Additionally,the interleaved or multilayer design strategy of metasurfaces increases the complexity of structural design and manufacturing,facing challenges in meeting the requirements for miniaturization and low cost-effectiveness.Here,we propose a strategy for a free-space 3D multiplane color holographic multiplex display based on a single-cell metasurface.By utilizing a modified holographic optimization strategy,multiple holographic information is encoded into three mutually independent bases of incident photons and integrated into a metasurface,thereby creating high-quality 3D vectorial metaholography with minimal crosstalk across the visible spectrum.
基金funding provided by National Natural Science Foundation of China(Nos.62288101,62325504,92250304)National Key Research and Development Program of China(No.2022YFA1404301)+1 种基金Key Research and Development Program of Jiangsu Province(No.BE2023083)Dengfeng Project B of Nanjing University.
文摘On-chip metasurfaces have been exploited to manipulate guided waves into free space with desired wavefronts and bridge the gap between guided modes and free-space optical fields.However,existing on-chip metasurfaces for guided wave radiation typically lack dynamic tunability and high-capacity multiplexing for their practical applications.Here,we present a dynamic waveguide-based holographic display enabled by on-chip metasurface network on lithium niobate on insulator platform.Based on geometric phase and detour phase,an on-chip multiplexed metasurface network implemented on a 2×2 waveguide crossing array is incorporated with a two-stage lithium niobate(LN)switch to construct an addressable framework.Benefiting from the multiplexing capability of on-chip metasurface and the fast electro-optical response of LN modulators,guided wave radiation in the form of eight holographic images is tunable and addressable at high speeds.This work exemplifies a scalable approach for dynamic manipulation of guided signals and paves the way towards holographic displays,high-capacity optical communications and integrated photonic information processing.
基金supported by the National Natural Science Foundation of China (NSFC)(Nos. 61827825 and 61775117)Tsinghua University Initiative Scientific Research Program (No. 20193080075)the Cambridge Tsinghua Joint Research Initiative
文摘This Letter describes an approach to encode complex-amplitude light waves with spatiotemporal double-phase holograms(DPHs) for overcoming the limit of the space-bandwidth product(SBP) delivered by existing methods. To construct DPHs, two spatially macro-pixel encoded phase components are employed in the SBP-preserved resampling of complex holograms. Four generated sub-DPHs are displayed sequentially in time for high-quality holographic image reconstruction without reducing the image size or discarding any image terms when the DPHs are interweaved. The reconstructed holographic images contain more details and less speckle noise, with their signal-to-noise ratio and structure similarity index being improved by 14.64% and 78.79%,respectively.
基金supported by the National High Technology Research and Development Program of China(No.2015AA015905)the National Basic Research Program of China(Nos.2013CB328801 and2013CB328806)the National Natural Science Founding of China(Nos.61420106014 and 61235002)
文摘Two different methods from graphic processing unit （GPU） and central processing unit （CPU） are proposed to suitably optimize look-up table algorithms of computer generated holography （CGH）. The numerical simula- tions and experimental results show that we can reconstruct a good quality object. The computation of CGH for a three-dimensional （3D） dynamic holographic display can also be sped up by programming with our proposed method. It can optimize both file loading and the inline calculation process. The phase-only CGH with gigabyte data for reconstructing 10 MB object samplings is generated. In addition, the proposed method effectively re- duced time costs of loading and writing offline tables on a CPU. It is believed the proposed method can provide high speed and huge data CGH for 3D dynamic holographic displays in the near future.
基金supported by the National Natural Science Foundation of China (No. 60772124)the Shanghai University Innovation Funds for Graduates(No. Shucx080215)+1 种基金the Post-doctoral Fund by Scienceand Technology Commission of Shanghai Municipality(No. 09R21412900)the International Cooperation Project of Science and Technology Commission of Shang-hai Municipality (No. 09530708700)
文摘In order to realize holographic display of three-dimensional （3D） objects and suppress zero-order light, conjugate image, and speckle noise, a novel method is proposed based on multiple fractional Fourier transform （M-FrFT） for cMculating holograms of 3D objects. A series of kinoforms are generated by adding pseudorandom phase factor （PPF） to object planes in calculating each kinoform, and generating the PPF randomly again in the next kinoform calculation. The reconstructed images from kinoform sequence are superposed together in order to suppress the speckle noise of reconstructed image and improve the contrast and detail resolution of the reconstructed images. The qualities of reconstructed images from single amplitude hologram, single kinoform, and kinoform sequence calculated by M-FrFT are compared. The effects of suppressing speckle noise are analyzed by calculating the speckle index of numerical reconstructed images. The analytical results illustrate that, with the proposed method for 3D holographic display, the zero-order light, conjugate image, and speckle noise can be suppressed, and the qualities of reconstructed images can be improved significantly.
基金sponsored by the National"973"Program of China(No.2013CB328804)the National Natural Science Foundation of China(No.61307028)the Science & Technology Commission of Shanghai Municipality(Nos.13ZR1420000 and 11JC1405300)
文摘A multiplexed holographic display video has been achieved by using a passive azo-dye-doped liquid crystal （LC） cell. Holograms formed in this cell can be refreshed in the order of several milliseconds. By angular multiplexing technique, dynamically multiplexed holographic videos are realized. Moreover, the reconstructed RGB images are merged into a color image, which illustrates the possibility of a color holographic three-dimensional （3D） display by holographic multiplexing of the LC cell.
基金supported by the National Basic Research Program of China (No. 2013CB328801)the National Natural Science Foundation of China (Nos. 61505095 and 61205013)
文摘A time-division multiplexing method for computer-generated holograms （CGHs） is proposed to solve the problem of the limited space-bandwidth product. A three-dimensional （3-D） scene is divided into multiple layers at different depths. The CGH corresponding to each layer is calculated by an angular-spectrum algorithm that is effective at a wide range of propagation distances. All of the CGHs are combined into several group-CGHs. These group-CGHs are sequentially uploaded onto one spatial light modulator at a high frame rate. The spacebandwidth product can be benefited by the time-division processing of the CGHs. The proposed method provides a new approach to achieve high quality 3-D display with a fast and accurate CGH computation.
基金supported by the National Basic Research Program of China(973 Program Nos.2013CB328801 and 2013CB328806)the National Natural Science Founding of China(No.61235002)
文摘We propose a method to improve the quality of the reconstructed images based on compressive sensing principles. The pseudo-inverse matrix and the total variation minimization algorithms are combined to reduce the sampling number of the computer generated hologram. Numerical simulations are performed and the results indicate that the peak signal to noise ratio is increased and the sampling ratio is decreased at the same time for holographic display.
文摘We proposed a method for calculating the computer generated hologram from multi-plane 3D objects by using nonuniform sampled angular spectrum method （NUASM）. Both of the holo-gram plane and the image plane are nonuniform sampled according to the distances and positions of the three-dimensional objects. The nonuniform fast Fourier transform （NUFFT） is used to calculate the angular spectrum propagation from the image plane to the hologram plane and the hologram can be calculated in only one step. Simulation and optical experiment results show that the hologram generated in this way can reconstruct objects on multi- planes simultaneously and separately without axial distortion.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11474194,11004037,and 61101176)the Natural Science Foundation of Shanghai,China(Grant No.14ZR1415500)
文摘We present holographic storage of three-dimensional（3D） images and data in a photopolymer film without any applied electric field.Its absorption and diffraction efficiency are measured,and reflective analog hologram of real object and image of digital information are recorded in the films.The photopolymer is compared with polymer dispersed liquid crystals as holographic materials.Besides holographic diffraction efficiency of the former is little lower than that of the latter,this work demonstrates that the photopolymer is more suitable for analog hologram and big data permanent storage because of its high definition and no need of high voltage electric field.Therefore,our study proposes a potential holographic storage material to apply in large size static 3D holographic displays,including analog hologram displays,digital hologram prints,and holographic disks.
文摘In this review we will focus on recent progress in the field of two-dimensional（2D） and three-dimensional（3D）display technologies.We present the current display materials and their applications,including organic light-emitting diodes（OLEDs）,flexible OLEDs quantum dot light emitting diodes（QLEDs）,active-matrix organic light emitting diodes（AMOLEDs）,electronic paper（E-paper）,curved displays,stereoscopic 3D displays,volumetric 3D displays,light field3 D displays,and holographic 3D displays.Conventional 2D display devices,such as liquid crystal devices（LCDs） often result in ambiguity in high-dimensional data images because of lacking true depth information.This review thus provides a detailed description of 3D display technologies.
基金Project supported by Partner State Key Laboratory on Advanced Displays and Optoelectronics Technologies HKUST,Chinathe National Natural Science Foundation of China(Grant Nos.61435008 and 61575063)the Fundamental Research Funds for the Central Universities,China(Grant No.WM1514036)
文摘A novel see-through display with a liquid crystal lens array was proposed.A liquid crystal Fresnel lens display（LCFLD） with a holographic screen was demonstrated.The proposed display system has high efficiency,simple fabrication,and low manufacturing cost due to the absence of a polarizer and color filter.
基金National Key Research and Development Program of China(2021YFB2802200)National Natural Science Foundation of China(62322217,62005154)+1 种基金Natural Science Foundation of Shanghai Municipality(20ZR1420500)University Grants Committee(ECS27212822,GRF 17208023)。
文摘Holographic near-eye augmented reality(AR)displays featuring tilted inbound/outbound angles on compact optical combiners hold significant potential yet often struggle to deliver satisfying image quality.This is primarily attributed to two reasons:the lack of a robust off-axis-supported phase hologram generation algorithm;and the suboptimal performance of ill-tuned hardware parts such as imperfect holographic optical elements(HOEs).To address these issues,we incorporate a gradient descent-based phase retrieval algorithm with spectrum remapping,allowing for precise hologram generation with wave propagation between nonparallel planes.Further,we apply a camera-calibrated propagation scheme to iteratively optimize holograms,mitigating imperfections arising from the defects in the HOE fabrication process and other hardware parts,thereby significantly lifting the holographic image quality.We build an off-axis holographic near-eye display prototype using off-the-shelf light engine parts and a customized full-color HOE,demonstrating state-of-the-art virtual reality and AR display results.
基金supported by the National Natural Science Foundation of China under Grant Nos:U22A2079,U21B2034,62275009,623B2008 and 62175006.
文摘Holographic 3D display technology,widely considered the ultimate solution for real 3D display,has broad applications in fields including advertisement,industrial manufacturing and military.However,it is difficult to simultaneously realize color holographic 3D display with wide viewing angle and high brightness required for an immersive visual experience.Here,a novel holographic 3D display system based on a customized achromatic liquid crystal grating and a phase-only spatial light modulator is proposed.Thanks to the secondary diffraction performed by the achromatic liquid crystal grating,nine secondary diffraction images of red,green and blue channels overlap in space in time sequence.Additionally,a high brightness hologram encoding method is developed,which introduces a frequency loss function with dynamic weights to ensure that differences of all frequency components in the frequency domain can be learned.The proposed method dramatically enhances light energy utilization by a factor of five,resulting in significantly brighter reconstructed images while substantially attenuating background noise in non-target regions.This groundbreaking system,achieving a remarkable~65°wide viewing angle with good image quality and high brightness,represents a significant advancement in holographic technology,offering a comprehensive solution for wide-viewing-angle,high-brightness,color 3D displays with potential applications across diverse technological domains.
基金supports from National Natural Science Foundation of China(Grant No.62205117,52275429)National Key Research and Development Program of China(Grant No.2021YFF0502700)+2 种基金Young Elite Scientists Sponsorship Program by CAST(Grant No.2022QNRC001)West Light Foundation of the Chinese Academy of Sciences(Grant No.xbzg-zdsys-202206)Hubei Natural Science Foundation Innovative Research Group Project(2024AFA025).
文摘The popularity of deep learning has boosted computer-generated holography(CGH)as a vibrant research field,particularly physics-driven unsupervised learning.Nevertheless,present unsupervised CGH models have not yet explored the potential of generating full-color 3D holograms through a unified framework.In this study,we propose a lightweight multiwavelength network model capable of high-fidelity and efficient full-color hologram generation in both 2D and 3D display,called IncepHoloRGB.The high-speed simultaneous generation of RGB holograms at 191 frames per second(FPS)is based on Inception sampling blocks and multi-wavelength propagation module integrated with depth-traced superimposition,achieving an average structural similarity(SSIM)of 0.88 and peak signal-to-noise ratio(PSNR)of 29.00 on the DIV2K test set in reconstruction.Full-color reconstruction of numerical simulations and optical experiments shows that IncepHoloRGB is versatile to diverse scenarios and can obtain authentic full-color holographic 3D display within a unified network model,paving the way for applications towards real-time dynamic naked-eye 3D display,virtual and augmented reality(VR/AR)systems.
基金National Natural Science Foundation of China(U22A2079,62035003,61975014)Beijing Municipal Science and Technology Commission,Adminitrative Commission of Zhongguancun Science Park(Z211100004821012).
文摘The near-eye display feature in emerging spatial computing systems produces a distinctive visual effect of mixing virtual and real worlds.However,its application for all-day wear is greatly limited by the bulky structure,energy expenditure,and continuous battery heating.Here,we propose a lightweight holographic near-eye display system that takes advantage of solar energy for self-charging.To guarantee the collection of solar energy and near-eye display without crosstalk,we implement holographic optical elements(HOEs)to diffract sunlight and signal light into a common waveguide.Then,small-area solar cells convert the collected solar energy and power the system.Compact power supply components replace heavy batteries,thus contributing to the lightweight design.The simple acquisition and management of solar energy provide the system with sustainable self-charging capability.We believe that the lightweight design and continuous energy input solution will significantly promote the popularity of near-eye display in our daily lives.
基金supported by the National Special Fund for the Development of Major Research Equipment and Instrument(Grant No.2020YFF01014503)the ShanghaiMunicipal Science and Technology Major Project(Grant No.22ZR1473100)+1 种基金the Youth Innovation Promotion Association,Chinese Academy of Sciences(Grant No.2022232)and the National Key Research and Development Program of China(Grant No.2022YFB2804602).
文摘Holographic display stands as a prominent approach for achieving lifelike three-dimensional(3D)reproductions with continuous depth sensation.However,the generation of a computer-generated hologram(CGH)always relies on the repetitive computation of diffraction propagation from point-cloud or multiple depthsliced planar images,which inevitably leads to an increase in computational complexity,making real-time CGH generation impractical.Here,we report a new CGH generation algorithm capable of rapidly synthesizing a 3D hologram in only one-step backward propagation calculation in a novel split Lohmann lens-based diffraction model.By introducing an extra predesigned virtual digital phase modulation of multifocal split Lohmann lens in such a diffraction model,the generated CGH appears to reconstruct 3D scenes with accurate accommodation abilities across the display contents.Compared with the conventional layer-based method,the computation speed of the proposed method is independent of the quantized layer numbers,and therefore can achieve real-time computation speed with a very dense of depth sampling.Both simulation and experimental results validate the proposed method.
文摘As the fiat panel displays （Liquid Crystal Displays, AMOLED, etc.） reach near perfection in their viewing qualities and display areas, it is natural to seek the next level of displays, including 3D displays. There is a strong surge in 3D liquid crystal displays as a result of the successful movie Avatar. Most of these 3D displays involve the employment of special glasses that allow one view perspective for each of the eyes to achieve a depth perception. Such displays are not real 3D displays. In fact, these displays can only provide one viewing perspective for all viewers, regardless of the viewer＇s position. In addition, a fundamental viewing problem of focusing and accommodation exist that can lead to discomfort and fatigue for many viewers. In this paper, the authors review the current status of stereoscopic 3D displays and their problems. The authors will also discuss the possibility of using fiat panels for the display of both phase and intensity of video image information, leading to the ultimate display of 3D holographic video images. Many of the fundamental issues and limitations will be presented and discussed.
基金supported by the National Natural Science Foundation of China(62020106010,62275009,U22A2079,11974258).
文摘An ideal holographic 3D display should have the characteristics of large viewing angle,full color,and low speckle noise.However,the viewing angle of the holographic 3D display is usually limited by existing strategies,which vastly hinders its extensive application.In this paper,a large viewing angle holographic 3D display system based on maximum diffraction modulation is proposed.The core of the proposed system comprises the spatial light modulators(SLMs)and liquid crystal grating.We also present a new feasible scheme for the realization of large viewing angle holographic 3D display.This is achieved by considering the maximum diffraction angle of SLM as the limited diffraction modulation range of each image point.By doing so,we could not only give access to the maximum hologram size of the object,but also tune the reconstructed image of secondary diffraction by using a self-engineered liquid crystal grating.More importantly,the proposed maximum diffraction modulation scheme enables the viewing angle of the proposed system to be enlarged to 73.4°.The proposed system has huge application potential in the fields such as education,culture,and entertainment.
