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Mitamura, Shunsuke. "Holographic Holography". Leonardo 22, n. 3/4 (1989): 337. http://dx.doi.org/10.2307/1575389.
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Kang, Hoonjong, Dimana Nazarova, Branimir Ivanov, Sunghee Hong, Joo Sup Park, Youngmin Kim, Jiyong Park, Nataliya Berberova, Elena Stoykova e Nikola Malinowski. "Digital Holographic Printing Methods for 3D Visualization of Cultural Heritage Artifacts". Digital Presentation and Preservation of Cultural and Scientific Heritage 4 (30 settembre 2014): 69–78. http://dx.doi.org/10.55630/dipp.2014.4.8.
Testo completoAbstract (sommario):
Holography enables capture and reconstruction of the optical field scattered from three-dimensional (3D) objects. The hologram encodes both amplitude and phase of the field under coherent illumination, whereas photography records only the amplitude by incoherent light. 3D visualization feature of holography motivates expansion of research efforts dedicated to digital holographic imaging methods as a holographic display or a holographic printer. The paper presents two holographic 3D printing techniques which combine digital 3D representation of an object with analog holographic recording. Generation of digital contents is considered for a holographic stereogram printer and a recently proposed wavefront printer. These imaging methods could be applied to specific artifacts which are difficult to be recorded by conventional analog holography.
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Desbiens, Jacques. "The Dispositif of Holography". Arts 8, n. 1 (26 febbraio 2019): 28. http://dx.doi.org/10.3390/arts8010028.
Testo completoAbstract (sommario):
The French word dispositif, applied to visual art, encompasses several components of an artwork, such as the apparatus itself as well as its display conditions and the viewers themselves. In this article, I examine the concept of dispositif in the context of holography and, in particular, synthetic holography (computer-generated holography). This analysis concentrates on the holographic space and its effects on time and colors. A few comparisons with the history of spatial representation allow us to state that the holographic dispositif breaks with the perspective tradition and opens a new field of artistic research and experimentation.
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Iano, Randrianasoa, e Randriamaroson Mahandrisoa. "Enhancing Real-Time Pyramid Holographic Display Through Iterative Algorithm Optimization for 3D Image Reconstruction". American Journal of Optics and Photonics 12, n. 1 (29 aprile 2024): 9–17. http://dx.doi.org/10.11648/j.ajop.20241201.12.
Testo completoAbstract (sommario):
Holography, a crucial technology for 3D visualization, strives to create realistic relief images. This research aims to enhance hologram quality and viewer experience by optimizing the image-processing pipeline. Conventional holographic displays face challenges due to their bulkiness and limited viewing angles. To overcome these limitations, this study proposes a novel approach that integrates digital holography with holographic pyramid technology. Digital holography uses computer algorithms for hologram generation, while holographic pyramid technology projects images onto a reflective pyramid for 3D display. The drawback of holographic pyramid displays in low-light environments is addressed through increased diffraction to enhance image resolution. This integrated approach involves comprehensive research, including an examination of existing methods. The anticipated outcome is holograms with improved visibility and resolution from multiple angles. The research presents an initial image preprocessing phase, succeeded by sophisticated processing employing iterative algorithms. This aims to diminish the image size while upholding its quality, thereby achieving an image suitable for pyramidal display. The fusion of digital holography and holographic pyramid display shows promise for immersive visual experiences. However, advancements in processing techniques may lead to increased material complexity, posing a challenge. Through this research, the system aims to unlock creative potentials and pave the way for enhanced holographic displays in various applications.
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Picart, Pascal. "Recent advances in speckle decorrelation modeling and processing in digital holographic interferometry". Photonics Letters of Poland 13, n. 4 (30 dicembre 2021): 73. http://dx.doi.org/10.4302/plp.v13i4.1126.
Testo completoAbstract (sommario):
Digital holography, and especially digital holographic interferometry, is a powerful approach for the characterization of modifications at the surface or in the volume of objects. Nevertheless, the reconstructed phase data from holographic interferometry is corrupted by the speckle noise. In this paper, we discuss on recent advances in speckle decorrelation noise removal. Two main topics are considered. The first one presents recent results in modelling the decorrelation noise in digital Fresnel holography. Especially the anisotropy of the decorrelation noise is established. The second topic presents a new approach for speckle de-noising using deep convolution neural networks. Full Text: PDF ReferencesP. Picart (ed.), New techniques in digital holography (John Wiley & Sons, 2015). CrossRef T.M. Biewer, J.C. Sawyer, C.D. Smith, C.E. Thomas, "Dual laser holography for in situ measurement of plasma facing component erosion (invited)", Rev. Sci. Instr. 89, 10J123 (2018). CrossRef M. Fratz, T. Beckmann, J. Anders, A. Bertz, M. Bayer, T. Gießler, C. Nemeth, D. Carl, "Inline application of digital holography [Invited]", Appl. Opt. 58(34), G120 (2019). CrossRef M.P. Georges, J.-F. Vandenrijt, C. Thizy, Y. Stockman, P. Queeckers, F. Dubois, D. Doyle, "Digital holographic interferometry with CO2 lasers and diffuse illumination applied to large space reflector metrology [Invited]", Appl. Opt. 52(1), A102 (2013). CrossRef E. Meteyer, F. Foucart, M. Secail-Geraud, P. Picart, C. Pezerat, "Full-field force identification with high-speed digital holography", Mech. Syst. Signal Process. 164 (2022). CrossRef L. Lagny, M. Secail-Geraud, J. Le Meur, S. Montresor, K. Heggarty, C. Pezerat, P. Picart, "Visualization of travelling waves propagating in a plate equipped with 2D ABH using wide-field holographic vibrometry", J. Sound Vib. 461 114925 (2019). CrossRef L. Valzania, Y. Zhao, L. Rong, D. Wang, M. Georges, E. Hack, P. Zolliker, "THz coherent lensless imaging", Appl. Opt. 58, G256 (2019). CrossRef V. Bianco, P. Memmolo, M. Leo, S. Montresor, C. Distante, M. Paturzo, P. Picart, B. Javidi, P. Ferraro, "Strategies for reducing speckle noise in digital holography", Light: Sci. Appl. 7(1), 1 (2018). CrossRef V. Bianco, P. Memmolo, M. Paturzo, A. Finizio, B. Javidi, P. Ferraro, "Quasi noise-free digital holography", Light. Sci. Appl. 5(9), e16142 (2016). CrossRef R. Horisaki, R. Takagi, J. Tanida, "Deep-learning-generated holography", Appl. Opt. 57(14), 3859 (2018). CrossRef E. Meteyer, F. Foucart, C. Pezerat, P. Picart, "Modeling of speckle decorrelation in digital Fresnel holographic interferometry", Opt. Expr. 29(22), 36180 (2021). CrossRef M. Piniard, B. Sorrente, G. Hug, P. Picart, "Theoretical analysis of surface-shape-induced decorrelation noise in multi-wavelength digital holography", Opt. Expr. 29(10), 14720 (2021). CrossRef P. Picart, S. Montresor, O. Sakharuk, L. Muravsky, "Refocus criterion based on maximization of the coherence factor in digital three-wavelength holographic interferometry", Opt. Lett. 42(2), 275 (2017). CrossRef P. Picart, J. Leval, "General theoretical formulation of image formation in digital Fresnel holography", J. Opt. Soc. Am. A 25, 1744 (2008). CrossRef S. Montresor, P. Picart, "Quantitative appraisal for noise reduction in digital holographic phase imaging", Opt. Expr. 24(13), 14322 (2016). CrossRef S. Montresor, M. Tahon, A. Laurent, P. Picart, "Computational de-noising based on deep learning for phase data in digital holographic interferometry", APL Photonics 5(3), 030802 (2020). CrossRef M. Tahon, S. Montresor, P. Picart, "Towards Reduced CNNs for De-Noising Phase Images Corrupted with Speckle Noise", Photonics 8(7), 255 (2021). CrossRef E. Meteyer, S. Montresor, F. Foucart, J. Le Meur, K. Heggarty, C. Pezerat, P. Picart, "Lock-in vibration retrieval based on high-speed full-field coherent imaging", Sci. Rep. 11(1), 1 (2021). CrossRef
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Schofield, M. A., e Y. Zhu. "Characterization of JEOL 3000f TEM Equipped for Electron Holography". Microscopy and Microanalysis 6, S2 (agosto 2000): 228–29. http://dx.doi.org/10.1017/s1431927600033638.
Testo completoAbstract (sommario):
Quantitative off-axis electron holography in a transmission electron microscope (TEM) requires careful design of experiment specific to instrumental characteristics. For example, the spatial resolution desired for a particular holography experiment imposes requirements on the spacing of the interference fringes to be recorded. This fringe spacing depends upon the geometric configuration of the TEM/electron biprism system, which is experimentally fixed, but also upon the voltage applied to the biprism wire of the holography unit, which is experimentally adjustable. Hence, knowledge of the holographic interference fringe spacing as a function of applied voltage to the electron biprism is essential to the design of a specific holography experiment. Furthermore, additional instrumental parameters, such as the coherence and virtual size of the electron source, for example, affect the quality of recorded holograms through their effect on the contrast of the holographic fringes.
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Zou, Yijun, Hui Jin, Rongrong Zhu e Ting Zhang. "Metasurface Holography with Multiplexing and Reconfigurability". Nanomaterials 14, n. 1 (26 dicembre 2023): 66. http://dx.doi.org/10.3390/nano14010066.
Testo completoAbstract (sommario):
Metasurface holography offers significant advantages, including a broad field of view, minimal noise, and high imaging quality, making it valuable across various optical domains such as 3D displays, VR, and color displays. However, most passive pure-structured metasurface holographic devices face a limitation: once fabricated, as their functionality remains fixed. In recent developments, the introduction of multiplexed and reconfigurable metasurfaces breaks this limitation. Here, the comprehensive progress in holography from single metasurfaces to multiplexed and reconfigurable metasurfaces is reviewed. First, single metasurface holography is briefly introduced. Second, the latest progress in angular momentum multiplexed metasurface holography, including basic characteristics, design strategies, and diverse applications, is discussed. Next, a detailed overview of wavelength-sensitive, angle-sensitive, and polarization-controlled holograms is considered. The recent progress in reconfigurable metasurface holography based on lumped elements is highlighted. Its instant on-site programmability combined with machine learning provides the possibility of realizing movie-like dynamic holographic displays. Finally, we briefly summarize this rapidly growing area of research, proposing future directions and potential applications.
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Balasubramani, Vinoth, Małgorzata Kujawińska, Cédric Allier, Vijayakumar Anand, Chau-Jern Cheng, Christian Depeursinge, Nathaniel Hai et al. "Roadmap on Digital Holography-Based Quantitative Phase Imaging". Journal of Imaging 7, n. 12 (26 novembre 2021): 252. http://dx.doi.org/10.3390/jimaging7120252.
Testo completoAbstract (sommario):
Quantitative Phase Imaging (QPI) provides unique means for the imaging of biological or technical microstructures, merging beneficial features identified with microscopy, interferometry, holography, and numerical computations. This roadmap article reviews several digital holography-based QPI approaches developed by prominent research groups. It also briefly discusses the present and future perspectives of 2D and 3D QPI research based on digital holographic microscopy, holographic tomography, and their applications.
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MANSURIPUR, MASUD. "Holography and Holographic Interferometry". Optics and Photonics News 9, n. 3 (1 marzo 1998): 41. http://dx.doi.org/10.1364/opn.9.3.000041.
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Lee, Y. J., e J. H. Kim. "A Review of Holography Applications in Multiphase Flow Visualization Study". Journal of Fluids Engineering 108, n. 3 (1 settembre 1986): 279–88. http://dx.doi.org/10.1115/1.3242575.
Testo completoAbstract (sommario):
Holographic techniques are used in many fields of science and engineering including flow observation. The purpose of this paper is to review applications of holography to multiphase flow study with emphasis on gas-solid and gas-liquid two-phase flows. The application of holography to multiphase flow has been actively explored in the areas of particle sizing in particulate flows and nuclei population measurements in cavitation study. It is also recognized that holography holds great potential as a means of visualizing dynamic situations inherent in multiphase flows. This potential has been demonstrated by holographic flow visualization studies of coal combustion processes in gas-solid flows, gas-liquid two-phase critical flow measurements, and flashing flows in a nozzle. More effective and refined holographic techniques as well as efficient image processing methods are very much in need to facilitate and enhance the understanding of complex physical phenomena occurring in multiphase flows.
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Ren, Haoran, Wei Shao, Yi Li, Flora Salim e Min Gu. "Three-dimensional vectorial holography based on machine learning inverse design". Science Advances 6, n. 16 (aprile 2020): eaaz4261. http://dx.doi.org/10.1126/sciadv.aaz4261.
Testo completoAbstract (sommario):
The three-dimensional (3D) vectorial nature of electromagnetic waves of light has not only played a fundamental role in science but also driven disruptive applications in optical display, microscopy, and manipulation. However, conventional optical holography can address only the amplitude and phase information of an optical beam, leaving the 3D vectorial feature of light completely inaccessible. We demonstrate 3D vectorial holography where an arbitrary 3D vectorial field distribution on a wavefront can be precisely reconstructed using the machine learning inverse design based on multilayer perceptron artificial neural networks. This 3D vectorial holography allows the lensless reconstruction of a 3D vectorial holographic image with an ultrawide viewing angle of 94° and a high diffraction efficiency of 78%, necessary for floating displays. The results provide an artificial intelligence–enabled holographic paradigm for harnessing the vectorial nature of light, enabling new machine learning strategies for holographic 3D vectorial fields multiplexing in display and encryption.
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Song, Qinghua, Xingsi Liu, Cheng-Wei Qiu e Patrice Genevet. "Vectorial metasurface holography". Applied Physics Reviews 9, n. 1 (marzo 2022): 011311. http://dx.doi.org/10.1063/5.0078610.
Testo completoAbstract (sommario):
Tailoring light properties using metasurfaces made of optically thin and subwavelength structure arrays has led to a variety of innovative optical components with intriguing functionalities. Transmitted/reflected light field distribution with exquisite nanoscale resolution achievable with metasurfaces has been utilized to encode holographic complex amplitude, leading to arbitrary holographic intensity profile in the plane of interest. Vectorial metasurface holography, which not only controls the intensity profile, but also modifies the polarization distributions of the light field, has recently attracted enormous attention due to their promising applications in photonics and optics. Here, we review the recent progresses of the vectorial metasurface holography, from the basic concept to the practical implementation. Moreover, vectorial metasurfaces can also be multiplexed with other degrees of freedom, such as wavelength and nonlinearity, enriching and broadening its applications in both civil and military field.
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Zhai, Yueyang, Li Cao, Ying Liu e Xiaodi Tan. "A Review of Polarization-Sensitive Materials for Polarization Holography". Materials 13, n. 23 (6 dicembre 2020): 5562. http://dx.doi.org/10.3390/ma13235562.
Testo completoAbstract (sommario):
Polarization holography has the unique capacity to record and retrieve the amplitude, phase, and polarization of light simultaneously in a polarization-sensitive recording material and has attracted widespread attention. Polarization holography is a noteworthy technology with potential applications in the fields of high-capacity data storage, polarization-controlled optical elements, and other related fields. The choice of its high-performance materials is particularly important. To further develop polarization holography applications and improve the quality of the information recorded (i.e., material sensitivity and resolution), a deeper understanding of such materials is needed. We present an overview of the polarization-sensitive materials, which introduced polarization holographic technology and the development of polarization holographic materials. The three main types of polarization holographic materials are described, including azopolymer materials, photopolymer material, and photorefractive polymer material. We examine the key contributions of each work and present many of the suggestions that have been made to improve the different polarization-sensitive photopolymer materials.
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Pepper, Andrew. "The Gallery as a Location for Research-Informed Practice and Critical Reflection". Arts 8, n. 4 (27 settembre 2019): 126. http://dx.doi.org/10.3390/arts8040126.
Testo completoAbstract (sommario):
Creative holography could still be considered a fringe medium or methodology, compared to mainstream art activities. Unsurprisingly, work using this technology continues to be shown together with other holographic works. This paper examines the merits of exhibiting such works alongside other media. It also explores how this can contribute to the development of a personal critical framework and a broader analytical discourse about creative holography. The perceived limitations of showing holograms in a “gallery ghetto” are explored using early critical art reviews about these group exhibitions. An international exhibition, which toured the United Kingdom (UK) and Australia, is used as a framework to expand the discussion. These exhibitions include examples of the author’s holographic work and those of artists working with other (non-holographic) media and approaches. The touring exhibition as a transient, research-informed process is investigated, as is its impact on the critical development of work using holography as a valid medium, approach, and methodology in the creative arts.
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Fedorov, A. G., V. V. Platonov, L. L. Zhondorova e L. N. Fedorova. "Development of a digital holographic microscope model for the investigate of structures in the optical range". Vestnik of North-Eastern Federal University History Political Science Law 21, n. 2 (29 giugno 2024): 77–83. http://dx.doi.org/10.25587/2222-5404-2024-21-2-77-83.
Testo completoAbstract (sommario):
One of the modern and relevant methods for investigating the structures of objects is based on the holographic method of recording signals (holographic microscopy). The main advantage of this method is the ability to obtain complete information about the object. In other words, this method makes it possible to record not only the amplitude, but also the phase of the wave. This is achieved thanks to a recording scheme in which the phase of the wave is some modulation of the intensity. This advantage makes holographic microscopy an effective tool for the investigate of particles/microparticles in gases, liquids and solid materials in the form of thin films or in sufficiently transparent materials for optical waves (one of the main limitations of the holographic recording scheme is to investigate only objects with high transmissivity, i.e. the reference wave is must be about 70% or more of the total wave). Within the framework of this work, we consider the scheme of in-line holography (Gabor holography). The undoubted advantage of the in-line holographic investigation method is that it is limited only by the wavelength range. In other words, by changing the wavelength of the source, a wide range of objects can be examined. For example, in-line holography is used in low energy electron microscopes, which allows the atomic structure of an object to be studied. In the case when the source is a laser (optical range), a holographic microscope provides a wide range of possibilities for investigation the micro-objects, from various bacteria to various fine–structured particles. We developed a model of a digital holographic microscope for the study of structures in the optical range, based on the Gabor in-line holography method. This model of the microscope is developed on the Raspberry Pi Zero 2W platform.
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Zhang, Yu Fei, e Yi Quan Wu. "A Method for Eliminating Zero-Order Image in Digital Holograph Based on Contourlet Transform". Advanced Materials Research 760-762 (settembre 2013): 80–83. http://dx.doi.org/10.4028/www.scientific.net/amr.760-762.80.
Testo completoAbstract (sommario):
In the reconstruction process of digital holograph, zero-order image has a bad impact on the quality of real image. In this paper, a new way to eliminate zero-order image in digital holography is proposed. Firstly, digital holography image is decomposed by contourlet transform, then remove the low frequency. The new digital holography image is obtained by inverse contourlet transform. Experiments show that, compared with spatial filtering, frequency domain filtering, laplacian filtering and eliminate zero-order image method based on wavelet, the new method proposed in this paper can eliminate zero-order image better, whats more, the real image is also strengthened in some way.
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Suzanna, Suzanna. "Application of Holographic Technology in Education". PIKSEL : Penelitian Ilmu Komputer Sistem Embedded and Logic 11, n. 2 (30 settembre 2023): 253–66. http://dx.doi.org/10.33558/piksel.v11i2.7320.
Testo completoAbstract (sommario):
This research examines the benefits of holographic technology so that it can be used in education. The current education system already makes extensive use of computer-based information and communication technology; however, the application of holography technology is still a futuristic (future) concept due to difficulties in implementing technical procedures and software requirements in the application of holography technology. This research discusses technology related to holography and how the practice of holography will be applied in the future, affecting many areas of life, especially the world of education. In this study, researchers also conducted experiments on a group of children aged 3 - 4 years using holography technology with the HolograFX Game as a tool for conducting experiments. From the experimental results, it can be concluded that holograms can be accepted by children and provide them with the opportunity to learn in different ways and methods and provide impressive experiences.
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Chen, Duofang, Lin Wang, Xixin Luo, Hui Xie e Xueli Chen. "Resolution and Contrast Enhancement for Lensless Digital Holographic Microscopy and Its Application in Biomedicine". Photonics 9, n. 5 (19 maggio 2022): 358. http://dx.doi.org/10.3390/photonics9050358.
Testo completoAbstract (sommario):
An important imaging technique in biomedicine, the conventional optical microscopy relies on relatively complicated and bulky lens and alignment mechanics. Based on the Gabor holography, the lensless digital holographic microscopy has the advantages of light weight and low cost. It has developed rapidly and received attention in many fields. However, the finite pixel size at the sensor plane limits the spatial resolution. In this study, we first review the principle of lensless digital holography, then go over some methods to improve image contrast and discuss the methods to enhance the image resolution of the lensless holographic image. Moreover, the applications of lensless digital holographic microscopy in biomedicine are reviewed. Finally, we look forward to the future development and prospect of lensless digital holographic technology.
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Chakravarthula, Praneeth, Seung-Hwan Baek, Florian Schiffers, Ethan Tseng, Grace Kuo, Andrew Maimone, Nathan Matsuda, Oliver Cossairt, Douglas Lanman e Felix Heide. "Pupil-Aware Holography". ACM Transactions on Graphics 41, n. 6 (30 novembre 2022): 1–15. http://dx.doi.org/10.1145/3550454.3555508.
Testo completoAbstract (sommario):
Holographic displays promise to deliver unprecedented display capabilities in augmented reality applications, featuring a wide field of view, wide color gamut, spatial resolution, and depth cues all in a compact form factor. While emerging holographic display approaches have been successful in achieving large étendue and high image quality as seen by a camera, the large étendue also reveals a problem that makes existing displays impractical: the sampling of the holographic field by the eye pupil. Existing methods have not investigated this issue due to the lack of displays with large enough étendue, and, as such, they suffer from severe artifacts with varying eye pupil size and location. We show that the holographic field as sampled by the eye pupil is highly varying for existing display setups, and we propose pupil-aware holography that maximizes the perceptual image quality irrespective of the size, location, and orientation of the eye pupil in a near-eye holographic display. We validate the proposed approach both in simulations and on a prototype holographic display and show that our method eliminates severe artifacts and significantly outperforms existing approaches.
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Gizon, Laurent, Damien Fournier, Dan Yang, Aaron C. Birch e Hélène Barucq. "Signal and noise in helioseismic holography". Astronomy & Astrophysics 620 (dicembre 2018): A136. http://dx.doi.org/10.1051/0004-6361/201833825.
Testo completoAbstract (sommario):
Context. Helioseismic holography is an imaging technique used to study heterogeneities and flows in the solar interior from observations of solar oscillations at the surface. Holographic images contain noise due to the stochastic nature of solar oscillations. Aims. We aim to provide a theoretical framework for modeling signal and noise in Porter–Bojarski helioseismic holography. Methods. The wave equation may be recast into a Helmholtz-like equation, so as to connect with the acoustics literature and define the holography Green’s function in a meaningful way. Sources of wave excitation are assumed to be stationary, horizontally homogeneous, and spatially uncorrelated. Using the first Born approximation we calculated holographic images in the presence of perturbations in sound-speed, density, flows, and source covariance, as well as the noise level as a function of position. This work is a direct extension of the methods used in time-distance helioseismology to model signal and noise. Results. To illustrate the theory, we compute the holographic image intensity numerically for a buried sound-speed perturbation at different depths in the solar interior. The reference Green’s function is obtained for a spherically-symmetric solar model using a finite-element solver in the frequency domain. Below the pupil area on the surface, we find that the spatial resolution of the holographic image intensity is very close to half the local wavelength. For a sound-speed perturbation of size comparable to the local spatial resolution, the signal-to-noise ratio is approximately constant with depth. Averaging the image intensity over a number N of frequencies above 3 mHz increases the signal-to-noise ratio by a factor nearly equal to the square root of N. This may not be the case at lower frequencies, where large variations in the holographic signal are due to the contributions from the long-lived modes of oscillation.
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Wu, Taihui, Jianshe Ma, Chengchen Wang, Haibei Wang e Ping Su. "Full-Color See-Through Three-Dimensional Display Method Based on Volume Holography". Sensors 21, n. 8 (11 aprile 2021): 2698. http://dx.doi.org/10.3390/s21082698.
Testo completoAbstract (sommario):
We propose a full-color see-through three-dimensional (3D) display method based on volume holography. This method is based on real object interference, avoiding the device limitation of spatial light modulator (SLM). The volume holography has a slim and compact structure, which realizes 3D display through one single layer of photopolymer. We analyzed the recording mechanism of volume holographic gratings, diffraction characteristics, and influencing factors of refractive index modulation through Kogelnik’s coupled-wave theory and the monomer diffusion model of photopolymer. We built a multiplexing full-color reflective volume holographic recording optical system and conducted simultaneous exposure experiment. Under the illumination of white light, full-color 3D image can be reconstructed. Experimental results show that the average diffraction efficiency is about 53%, and the grating fringe pitch is less than 0.3 μm. The reconstructed image of volume holography has high diffraction efficiency, high resolution, strong stereo perception, and large observing angle, which provides a technical reference for augmented reality.
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Xu, Xianfeng, Xinwei Wang, Weilong Luo, Hao Wang e Yuting Sun. "Efficient Computer-Generated Holography Based on Mixed Linear Convolutional Neural Networks". Applied Sciences 12, n. 9 (21 aprile 2022): 4177. http://dx.doi.org/10.3390/app12094177.
Testo completoAbstract (sommario):
Imaging based on computer-generated holography using traditional methods has the problems of poor quality and long calculation cycles. However, recently, the development of deep learning has provided new ideas for this problem. Here, an efficient computer-generated holography (ECGH) method is proposed for computational holographic imaging. This method can be used for computational holographic imaging based on mixed linear convolutional neural networks (MLCNN). By introducing fully connected layers in the network, the suggested design is more powerful and efficient at information mining and information exchange. Using the ECGH, the pure phase image required can be obtained after calculating the custom light field. Compared with traditional computed holography based on deep learning, the method used here can reduce the number of network parameters needed for network training by about two-thirds while obtaining a high-quality image in the reconstruction, and the network structure has the potential to solve various image-reconstruction problems.
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Gao, Hui, Yuxi Wang, Xuhao Fan, Binzhang Jiao, Tingan Li, Chenglin Shang, Cheng Zeng et al. "Dynamic 3D meta-holography in visible range with large frame number and high frame rate". Science Advances 6, n. 28 (luglio 2020): eaba8595. http://dx.doi.org/10.1126/sciadv.aba8595.
Testo completoAbstract (sommario):
The hologram is an ideal method for displaying three-dimensional images visible to the naked eye. Metasurfaces consisting of subwavelength structures show great potential in light field manipulation, which is useful for overcoming the drawbacks of common computer-generated holography. However, there are long-existing challenges to achieving dynamic meta-holography in the visible range, such as low frame rate and low frame number. In this work, we demonstrate a design of meta-holography that can achieve 228 different holographic frames and an extremely high frame rate (9523 frames per second) in the visible range. The design is based on a space channel metasurface and a high-speed dynamic structured laser beam modulation module. The space channel consists of silicon nitride nanopillars with a high modulation efficiency. This method can satisfy the needs of a holographic display and be useful in other applications, such as laser fabrication, optical storage, optics communications, and information processing.
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Crenshaw. "The Dynamic Display of Art Holography". Arts 8, n. 3 (19 settembre 2019): 122. http://dx.doi.org/10.3390/arts8030122.
Testo completoAbstract (sommario):
Holograms have been displayed in single-artist and group exhibitions, since the late 1960’s. The content within a holographic image can be greatly compromised if the hologram is not displayed correctly. Holography exhibitions can either enhance or diminish the impact of the images depending on how the exhibit layout and lighting are designed. This paper looks at art holography from the exhibition installation perspective and offers methods for assuring dynamic displays.
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Zhang, Nian, Baoxing Xiong, Xiang Zhang e Xiao Yuan. "Holographic Encryption Applications Using Composite Orbital Angular Momentum Beams". Photonics 9, n. 9 (26 agosto 2022): 605. http://dx.doi.org/10.3390/photonics9090605.
Testo completoAbstract (sommario):
Optical orbital angular momentum (OAM) holography has been developed and implemented as a vital method for optical encryption. However, OAM holography can only be encoded and decoded with an OAM beam, which limits the level of optical encryption. Here, composite OAM beams are introduced using a computer-generated hologram (CGH) for holographic encryption. The target image is encoded with composite helical mode indices, and the OAM holographic image can only be reconstructed under a specific illuminating composite OAM beam. The experimental results are consistent with the theoretical design and numerical simulations, verifying that composite OAM beams can provide a higher security level for optical holographic encryption. The proposed method can be used to enhance anti-counterfeiting applications, secure communication systems, and imaging systems.
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Rashkov, Radoslav. "Integrable structures in low-dimensional holography and cosmologies". International Journal of Modern Physics A 33, n. 34 (10 dicembre 2018): 1845008. http://dx.doi.org/10.1142/s0217751x18450082.
Testo completoAbstract (sommario):
We focus on the integrable properties in low-dimensional holography. The motivation is that most of the integrable structures underlying holographic duality survive weak-strong coupling transition. We found relation between certain integrable structures in low-dimensional holography and key characteristics of the theories. We propose generalizations to higher spin (HS) theories including Sachdev–Ye–Kitaev (SYK) model. We comment on some of the intriguing relations found in this study.
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Wang, Yu Tian, Dong Sheng Wang e Wei Wei Pan. "The Analysis and Research on Digital Holography Signal Based on Wavelet Theory". Advanced Materials Research 216 (marzo 2011): 414–18. http://dx.doi.org/10.4028/www.scientific.net/amr.216.414.
Testo completoAbstract (sommario):
When introduce the wavelet theory to filter the hologram and the reconstructed image in the digital holography, the noise of the reconstructed image is greatly reduced. In the off-axis digital holography, the zero-order wave is decreased dramatically when after a wavelet filter, at the same time, the speckle noise is also reduced, and it turns out that the resolution of the reconstruction image is improved greatly. The system launches the research thoroughly on the three-dimensional body digital holographic technology, from the theory to the application, from the simulation to the experiment, and has elaborated and analyzed each characteristic of three-dimensional body digital holographic technology. It proposes many kinds of improved effective method of three-dimensional body digital holographic restructuring information, and finally has effectively explored the three-dimensional body digital holographic technology application through the experiment.
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Petoukhov, S. V. "GENETIC CODING SYSTEM ANDALGEBRAIC HOLOGRAPHY". Metaphysics, n. 2 (25 agosto 2022): 113–27. http://dx.doi.org/10.22363/2224-7580-2022-2-113-127.
Testo completoAbstract (sommario):
The article is devoted to the structural features of the molecular genetic coding system. These features in their matrix representation turn out to be conjugate with the matrix structures of algebraic holography, which have long been used in digital informatics. The relationship between ensembles of genetic structures and bit-reversing holography, split-quaternions, and the Poincaré disk model of hyperbolic motions is described. This connection leads to well-known works on quantum holographic noise-immune codes and makes it possible to comprehend the facts of the realization of hyperbolic geometry in genetically inherited macrophysiological phenomena.
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Nam, Seung-Woo, Youngjin Kim, Dongyeon Kim e Yoonchan Jeong. "Depolarized Holography with Polarization-Multiplexing Metasurface". ACM Transactions on Graphics 42, n. 6 (5 dicembre 2023): 1–16. http://dx.doi.org/10.1145/3618395.
Testo completoAbstract (sommario):
The evolution of computer-generated holography (CGH) algorithms has prompted significant improvements in the performances of holographic displays. Nonetheless, they start to encounter a limited degree of freedom in CGH optimization and physical constraints stemming from the coherent nature of holograms. To surpass the physical limitations, we consider polarization as a new degree of freedom by utilizing a novel optical platform called metasurface. Polarization-multiplexing metasurfaces enable incoherent-like behavior in holographic displays due to the mutual incoherence of orthogonal polarization states. We leverage this unique characteristic of a metasurface by integrating it into a holographic display and exploiting polarization diversity to bring an additional degree of freedom for CGH algorithms. To minimize the speckle noise while maximizing the image quality, we devise a fully differentiable optimization pipeline by taking into account the metasurface proxy model, thereby jointly optimizing spatial light modulator phase patterns and geometric parameters of metasurface nanostructures. We evaluate the metasurface-enabled depolarized holography through simulations and experiments, demonstrating its ability to reduce speckle noise and enhance image quality.
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Huang, Lingling, Shuang Zhang e Thomas Zentgraf. "Metasurface holography: from fundamentals to applications". Nanophotonics 7, n. 6 (27 giugno 2018): 1169–90. http://dx.doi.org/10.1515/nanoph-2017-0118.
Testo completoAbstract (sommario):
AbstractHolography has emerged as a vital approach to fully engineer the wavefronts of light since its invention dating back to the last century. However, the typically large pixel size, small field of view and limited space-bandwidth impose limitations in the on-demand high-performance applications, especially for three-dimensional displays and large-capacity data storage. Meanwhile, metasurfaces have shown great potential in controlling the propagation of light through the well-tailored scattering behavior of the constituent ultrathin planar elements with a high spatial resolution, making them suitable for holographic beam-shaping elements. Here, we review recent developments in the field of metasurface holography, from the classification of metasurfaces to the design strategies for both free-space and surface waves. By employing the concepts of holographic multiplexing, multiple information channels, such as wavelength, polarization state, spatial position and nonlinear frequency conversion, can be employed using metasurfaces. Meanwhile, the switchable metasurface holography by the integration of functional materials stimulates a gradual transition from passive to active elements. Importantly, the holography principle has become a universal and simple approach to solving inverse engineering problems for electromagnetic waves, thus allowing various related techniques to be achieved.
31
Wang, Feili, Xiangchao Zhang, Rui Xiong, Xinyang Ma, He Yuan, Leheng Li e Xiangqian Jiang. "Flexible Image Reconstruction in the Orbital Angular Momentum Holography with Binarized Airy Lens". Photonics 9, n. 7 (29 giugno 2022): 460. http://dx.doi.org/10.3390/photonics9070460.
Testo completoAbstract (sommario):
The orbital angular momentum (OAM) holography has been marked a path to achieving ultrahigh capacity holographic information systems. However, the practical applicability of the OAM holography is limited by the complicated optical setup and unadjustable image intensity and position. Here, a decoding method is proposed by using a binarized phase map derived from an autofocusing Airy beam. By adjusting the parameters of the phase map, the position and intensity distribution of the reconstructed image become flexibly adjustable. In addition, the cross-talk between different image channels can be effectively reduced thanks to the abruptly autofocusing capability of the Airy beams. As a result, the quality and practicability of the OAM holography can be greatly enhanced.
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Bilić, Neven. "Holographic cosmology and tachyon inflation". International Journal of Modern Physics A 33, n. 34 (10 dicembre 2018): 1845004. http://dx.doi.org/10.1142/s0217751x18450045.
Testo completoAbstract (sommario):
After a brief introduction to the AdS/CFT holography, a tachyon inflation will be discussed in the framework of holographic cosmology. The model is based on a holographic braneworld scenario with an effective tachyon field on a D3-brane located at the holographic bound of an asymptotic ADS5 bulk.
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Fedorov, A. G., e M. P. Mironov. "Numerical simulation of wave propagation through a spherical particle within the framework of generalised Lorenz-Mie theory". Vestnik of North-Eastern Federal University 20, n. 4 (31 dicembre 2023): 31–38. http://dx.doi.org/10.25587/2222-5404-2023-20-4-31-38.
Testo completoAbstract (sommario):
Holography has been widely used for measuring and visualising transients in multiphase flows. Earlier, one of the drawbacks of this approach was the need to register on various photosensitive elements and its subsequent transfer to digital format and restoration. With the development of digital technologies, direct registration of interference patterns (holographic images) into a CCD matrix became possible. However, even in digital holography there are a number of problems that need to be solved. These problems pertain to recovery algorithms, efficient data processing and resolution, among others. Currently, the numerical implementation of the restoration and processing of holographic images can be done within the framework of classical diffraction theory or with the help of generalised Lorenz-Mie theory. The first implies an indirect solution of Maxwell's equations, i.e., application of the Huygens-Fresnel principle. The second approach involves a direct solution of Maxwell's equations for the holographic problem. In the framework of this work, a numerical simulation of holographic imaging of fields from spherical particles based on the generalised Lorenz-Mie theory is proposed. Within the framework of this work, a numerical implementation of modelling of holographic images of a homogeneous sphere based on the generalised Lorenz-Mie theory is presented. The implementation code in the python programming language is presented. The results of the study demonstrate the possibility of effective use of digital holography for visualisation and analysis of spherical objects.
34
Zhao, Jieming, Zhan Gao, Shengjia Wang, Yuhao Niu, Lin Deng e Ye Sa. "Multi-Object Deep-Field Digital Holographic Imaging Based on Inverse Cross-Correlation". Applied Sciences 13, n. 20 (18 ottobre 2023): 11430. http://dx.doi.org/10.3390/app132011430.
Testo completoAbstract (sommario):
To address the complexity of small or unique reconstruction distances in digital holography, we propose an inverse cross-correlation-based algorithm for the digital holographic imaging of multiplanar objects with a large depth of field. In this method, a planar output mapping is closely around the objects, and it is established by calculating the image inverse cross-correlation matrix of the reconstructed image at similar reconstruction distances, whereby the object edges serve as the result guide. Combining the search for edge planes with the depth estimation operator, the depth of field of digital holography is improved, thus allowing for a digital holography that is capable of meeting the requirements of the holographic imaging of multiplanar objects. Compared with the traditional depth estimation operator method, the proposed method solves the reconstruction ambiguity problem in multiple planes with a simple optical path, and no additional optical or mechanical devices need to be added, thus greatly improving the reconstruction quality. The numerical calculation results and the experimental results with multiplanar samples validate the effectiveness of the proposed method.
35
Roseker, W., W. Jo, R. Rysov, F. Westermeier, L. Bocklage, M. Riepp, A. Philippi-Kobs et al. "Hard X-ray USAXS Fourier Transform Holography". Journal of Physics: Conference Series 2380, n. 1 (1 dicembre 2022): 012118. http://dx.doi.org/10.1088/1742-6596/2380/1/012118.
Testo completoAbstract (sommario):
Abstract We report on a Fourier transform holography study, employing hard X-ray energies at a 3rd generation storage ring. Nano-structures of various sizes and shapes have been measured in ultra small angle x-ray scattering configuration reaching a resolution in the holographic reconstructions of about 50 nm. Reliable holograms have been obtained with 6.9×106 incident photons. Our results provide an important step forward towards routine split-pulse Fourier transform holography measurements at FEL sources and 4th generation ultralow-emittance sources.
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Yoneda, Naru, Jung-Ping Liu, Osamu Matoba, Yusuke Saita e Takanori Nomura. "Computational Optical Scanning Holography". Photonics 11, n. 4 (10 aprile 2024): 347. http://dx.doi.org/10.3390/photonics11040347.
Testo completoAbstract (sommario):
Holographic techniques are indispensable tools for modern optical engineering. Over the past two decades, research about incoherent digital holography has continued to attract attention. Optical scanning holography (OSH) can obtain incoherent holograms using single-pixel detection and structured illumination with Fresnel zone patterns (FZPs). Particularly by changing the size of a detector, OSH can also obtain holograms under coherently illuminated conditions. Since 1979, OSH has continuously evolved. According to the evolution of semiconductor technology, spatial light modulators (SLMs) come to be useful for various imaging fields. By using SLM techniques for OSH, the practicality of OSH is improved. These SLM-based OSH methods are termed computational OSH (COSH). In this review, the configurations, recording and reconstruction methods, and proposed applications of COSH are reviewed.
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Gong, Yungui, e Yuan-Zhong Zhang. "Holography and holographic dark energy model". Classical and Quantum Gravity 22, n. 22 (31 ottobre 2005): 4895–901. http://dx.doi.org/10.1088/0264-9381/22/22/014.
Testo completo
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Pu, Ye, Martin Centurion e Demetri Psaltis. "Harmonic holography: a new holographic principle". Applied Optics 47, n. 4 (29 novembre 2007): A103. http://dx.doi.org/10.1364/ao.47.00a103.
Testo completo
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Choi, Suyeon, Manu Gopakumar, Yifan Peng, Jonghyun Kim e Gordon Wetzstein. "Neural 3D holography". ACM Transactions on Graphics 40, n. 6 (dicembre 2021): 1–12. http://dx.doi.org/10.1145/3478513.3480542.
Testo completoAbstract (sommario):
Holographic near-eye displays promise unprecedented capabilities for virtual and augmented reality (VR/AR) systems. The image quality achieved by current holographic displays, however, is limited by the wave propagation models used to simulate the physical optics. We propose a neural network-parameterized plane-to-multiplane wave propagation model that closes the gap between physics and simulation. Our model is automatically trained using camera feedback and it outperforms related techniques in 2D plane-to-plane settings by a large margin. Moreover, it is the first network-parameterized model to naturally extend to 3D settings, enabling high-quality 3D computer-generated holography using a novel phase regularization strategy of the complex-valued wave field. The efficacy of our approach is demonstrated through extensive experimental evaluation with both VR and optical see-through AR display prototypes.
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Lichte, Hannes, Martin Linck, Dorin Geiger e Michael Lehmann. "Aberration Correction and Electron Holography". Microscopy and Microanalysis 16, n. 4 (5 luglio 2010): 434–40. http://dx.doi.org/10.1017/s1431927610093633.
Testo completoAbstract (sommario):
AbstractElectron holography has been shown to allow a posteriori aberration correction. Therefore, an aberration corrector in the transmission electron microscope does not seem to be needed with electron holography to achieve atomic lateral resolution. However, to reach a signal resolution sufficient for detecting single light atoms and very small interatomic fields, the aberration corrector has turned out to be very helpful. The basic reason is the optimized use of the limited number of “coherent” electrons that are provided by the electron source, as described by the brightness. Finally, quantitative interpretation of atomic structures benefits from the holographic facilities of fine-tuning of the aberration coefficients a posteriori and from evaluating both amplitude and phase.
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Takahashi, Yoshitaka, Masatoshi Saito, Toru Nakajima e Masakazu Shingu. "Determination of Phase Shift by Digital Holography". Applied Mechanics and Materials 888 (febbraio 2019): 43–46. http://dx.doi.org/10.4028/www.scientific.net/amm.888.43.
Testo completoAbstract (sommario):
In phase shifting interferometry phase shift is applied by various ways, but applying it with high accuracy, especially by LD current modulation, is not easy. In order to determine the accurate phase shift a new method has been proposed that the value of LD current corresponding to π/2 phase shift can be determined by phase shifting digital holography. The measured data of standard in surface shape measurement were used for calibration, and the obtained value was confirmed to cause noise reduction and improvement of holographic reconstructed images in digital holography.
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Zhang, X., D. C. Joy, L. F. Allard e T. A. Nolan. "Application of electron holography to ferroelectric study". Proceedings, annual meeting, Electron Microscopy Society of America 51 (1 agosto 1993): 1092–93. http://dx.doi.org/10.1017/s0424820100151295.
Testo completoAbstract (sommario):
With the development of FE TEM, electron holography becomes a reality to materials scientists, which opens a new window for materials study. Weak phase objects, such as a thin transparent specimen or an electric or a magnetic field, which have little or no effect on the intensity of the transmitted wave, can readily be observed via holography because of the phase shift that they produce. Application of the electron holographic method has been extended to the study of ferroelectric domain wall structures. This work presents the most recent results in this area.Polarization gradients within domain walls are extremely important for the understanding of the extrinsic elastio-dielectric properties of ferroelectrics. Electron holographic studies of the local domain wall profiles provide essential input parameters for phenomenological theories of domain structure and of the macroscopic properties derived from the theories. Figure 1(a) is an electron hologram of the ferroelectric (BaTiO3) 90° domain wall area.
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Shang, Guanyu, Zhuochao Wang, Haoyu Li, Kuang Zhang, Qun Wu, Shah Burokur e Xumin Ding. "Metasurface Holography in the Microwave Regime". Photonics 8, n. 5 (22 aprile 2021): 135. http://dx.doi.org/10.3390/photonics8050135.
Testo completoAbstract (sommario):
Hologram technology has attracted a great deal of interest in a wide range of optical fields owing to its potential use in future optical applications, such as holographic imaging and optical data storage. Although there have been considerable efforts to develop holographic technologies using conventional optics, critical issues still hinder their future development. A metasurface, as an emerging multifunctional device, can manipulate the phase, magnitude, polarization and resonance properties of electromagnetic fields within a sub-wavelength scale, opening up an alternative for a compact holographic structure and high imaging quality. In this review paper, we first introduce the development history of holographic imaging and metasurfaces, and demonstrate some applications of metasurface holography in the field of optics. We then summarize the latest developments in holographic imaging in the microwave regime. These functionalities include phase- and amplitude-based design, polarization multiplexing, wavelength multiplexing, spatial asymmetric propagation, and a reconfigurable mechanism. Finally, we conclude briefly on this rapidly developing research field and present some outlooks for the near future.
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Tyshchenko, I. A., e V. E. Kraskevich. "Holographic technologies as a way to attract investments". Mathematical machines and systems 3 (2022): 70–76. http://dx.doi.org/10.34121/1028-9763-2022-3-70-76.
Testo completoAbstract (sommario):
The purpose of the work is to research and formalize the methods of conveying visual information at presentations and the expediency of using modern information technologies for the visualization of presentation objects. The object of the research and comparison is the information technology of holographic 3D showcases and the holographic 3D showcase itself as a modern device for the virtualization of static and dynamic objects as well as the addition of real objects that meet the size criteria set by the developer, by creating augmented reality without using mobile applications and smartphone cameras. Holographic technologies and methods of holography are analyzed in the article. The use of holography is due to the increase in realistic advertising, the introduction of new information technologies in society, and the increase in the demands of society for multimedia devices. Methods of presenting holographic technologies can be considered information technologies for creating presentation applications that are used to display 3D holographic presentations. The concepts and features of 3D images are revealed. Achieving the realism of the presented information is possible only by creating three-dimensional images that will be placed in space. Dynamic images allow the authors to fully convey their ideas and create the effect of the presence of a real prototype of the product at the presentation. Since the device does not have visible elements of the display of the image, the viewer has no doubts about what he sees. Creation technologies were analyzed and a comparison of 2D and 3D holography was made. It is shown that each of the technologies has its own characteristics and makes it possible to use a holographic 3D showcase as a full-fledged substitute for the screen. Technological features allow using a hologram as a transparent monitor screen which provides new opportunities for demonstration and visualization of goods.
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Wan, Zhensong, Zijian Shi, Qiang Liu e and Xing Fu. "Holographic Tailoring of Structured Light Field with Digital Device". Photonics 9, n. 7 (21 luglio 2022): 506. http://dx.doi.org/10.3390/photonics9070506.
Testo completoAbstract (sommario):
Structured light fields have attracted much attention due to rich spatial degrees of freedom. The tailoring of an arbitrary structured light field on demand is the precondition for the application of structured light. Therefore, the computer holography method used to reconstruct a coherent light field wavefront has been naturally applied for generating structured light. In this work, we comprehensively demonstrate the principles and procedures of pure-phase computer-generated holography (PP-CGH) and binary-amplitude computer-generated holography (BA-CGH) methods for tailoring structured light, realized by two digitally programmable devices: liquid-crystal spatial light modulators (Lc-SLM) and digital micromirror devices (DMD), respectively. Moreover, we first compare the two approaches in detail and clarify the recipe to obtain a high tailoring accuracy and efficiency, which will help researchers to better understand and utilize the holographic tailoring of structured optical fields.
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Pinheiro, Antonio. "JPEG Column: 91st JPEG Meeting". ACM SIGMultimedia Records 13, n. 2 (giugno 2021): 1. http://dx.doi.org/10.1145/3577941.3577945.
Testo completoAbstract (sommario):
The 91st JPEG meeting was held online from 19 to 23 April 2021. This meeting saw several activities relating to holographic coding, notably the release of the JPEG Pleno Holography Call for Proposals, consolidated with the definition of the use cases and requirements for holographic coding and common test conditions that will assure the evaluation of the future proposals.
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Corda, Roberto, Daniele Giusto, Antonio Liotta, Wei Song e Cristian Perra. "Recent Advances in the Processing and Rendering Algorithms for Computer-Generated Holography". Electronics 8, n. 5 (17 maggio 2019): 556. http://dx.doi.org/10.3390/electronics8050556.
Testo completoAbstract (sommario):
Digital holography represents a novel media which promises to revolutionize the way the users interacts with content. This paper presents an in-depth review of the state-of-the-art algorithms for advanced processing and rendering of computer-generated holography. Open-access holographic data are selected and characterized as references for the experimental analysis. The design of a tool for digital hologram rendering and quality evaluation is presented and implemented as an open-source reference software, with the aim to encourage the approach to the holography research area, and simplify the rendering and quality evaluation tasks. Exploration studies focused on the reproducibility of the results are reported, showing a practical application of the proposed architecture for standardization activities. A final discussion on the results obtained is reported, also highlighting the future developments of the reconstruction software that is made publicly available with this work.
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Dyomin, Victor, Alexander Gribenyukov, Sergey Podzyvalov, Nikolay Yudin, Mikhail Zinoviev, Igor Polovtsev, Alexandra Davydova e Alexey Olshukov. "Application of Infrared Digital Holography for Characterization of Inhomogeneities and Voluminous Defects of Single Crystals on the Example of ZnGeP2". Applied Sciences 10, n. 2 (7 gennaio 2020): 442. http://dx.doi.org/10.3390/app10020442.
Testo completoAbstract (sommario):
In this work, the method of IR digital holography intended for detection of volumetric defects in ZnGeP2 single crystals has been tested. The holographic method is verified by a comparison of the results obtained with the data obtained by other methods. The spatial resolution of the experimental setup is ~15–20 µm. The volumetric defects of the ZnGeP2 crystal structure (in samples with thickness up to 50 mm) such as growth striations, dislocation chain, and inclusions of the second phase (Zn3P2) shaped as needles up to ~100 µm long and ~10 µm wide have been visualized by the method of IR digital holography.
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Thomas, Binu P., e S. Annamala Pillai. "Digital Holographic Interferometry for Wholefield NDT Applications". Journal of Aerospace Sciences and Technologies, 7 agosto 2023, 334–41. http://dx.doi.org/10.61653/joast.v61i2.2009.549.
Testo completoAbstract (sommario):
Holographic interferometry is a non-contact whole field optical technique used as a powerful NDT tool. This technique is highly sensitive and maps the object surface deformation as holographic fringe pattern. Conventional holography technique has practical difficulties in recording and reconstructing holograms. With the development in imaging sensor technology and fast algorithms in image processing, digital holography has been established. Digital holography uses high-resolution digital camera for recording holograms and does reconstruction of holograms numerically using a computer. This has enhanced the scope and application of holography for NDT many fold. In this paper application of digital holography to non-destructive testing is presented. The basic principle of digital holography and digital holographic interferometry in obtaining double exposure hologram for NDT is described. The software developed in house for numerical reconstruction of holograms is also explained. The advantages of digital holography over conventional holography in NDT applications are highlighted. Extensive experiments were carried out to prove the detectability of defects in both metallic and non-metallic materials and the results are presented. It is shown that digital holography is able to identify defects in a wide range of materials with great ease because of its high sensitivity and whole field nature.
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Márquez, Andrés, Chi Li, Augusto Beléndez, Stefan A. Maier e Haoran Ren. "Information multiplexing from optical holography to multi-channel metaholography". Nanophotonics, 27 novembre 2023. http://dx.doi.org/10.1515/nanoph-2023-0605.
Testo completoAbstract (sommario):
Abstract Holography offers a vital platform for optical information storage and processing, which has a profound impact on many photonic applications, including 3D displays, LiDAR, optical encryption, and artificial intelligence. In this review, we provide a comprehensive overview of optical holography, moving from volume holography based on optically thick holograms to digital holography using ultrathin metasurface holograms in nanophotonics. We review the use of volume holograms for holographic multiplexing through the linear momentum selectivity and other approaches and highlight the emerging use of digital holograms that can be implemented by ultrathin metasurfaces. We will summarize the fabrication of different holographic recording media and digital holograms based on recent advances in flat meta-optics and nanotechnology. We highlight the rapidly developing field of metasurface holography, presenting the use of multi-functional metasurfaces for multiplexing holography in the use of polarization, wavelength, and incident angle of light. In the scope of holographic applications, we will focus on high bandwidth metasurface holograms that offer the strong sensitivity to the orbital angular momentum of light. At the end, we will provide a short summary of this review article and our perspectives on the future development of the vivid holography field.