Articoli di riviste: "Holographic image"

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Fan, Fan, Xiaoyu Jiang, Xingpeng Yan, Jun Wen, Song Chen, Teng Zhang e Chao Han. "Holographic Element-Based Effective Perspective Image Segmentation and Mosaicking Holographic Stereogram Printing". Applied Sciences 9, n. 5 (4 marzo 2019): 920. http://dx.doi.org/10.3390/app9050920.

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Effective perspective image segmentation and mosaicking (EPISM) method is an effective holographic stereogram printing method, but a mosaic misplacement of reconstruction image occurred when focusing away from the reconstruction image plane. In this paper, a method known as holographic element-based effective perspective image segmentation and mosaicking is proposed. Holographic element (hogel) correspondence is used in EPISM method as pixel correspondence is used in direct-writing digital holography (DWDH) method to generate effective perspective images segments. The synthetic perspective image for holographic stereogram printing is obtained by mosaicking all the effective perspective images segments. Optical experiments verified that the holographic stereogram printed by the proposed method can provide high-quality reconstruction imagery and solve the mosaic misplacement inherent in the EPISM method.

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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.

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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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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.

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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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Khan, Aamir, Zhang Zhijiang, Yingjie Yu, Muhammad Amir Khan, Ketao Yan e Khizar Aziz. "GAN-Holo: Generative Adversarial Networks-Based Generated Holography Using Deep Learning". Complexity 2021 (21 gennaio 2021): 1–7. http://dx.doi.org/10.1155/2021/6662161.

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Current development in a deep neural network (DNN) has given an opportunity to a novel framework for the reconstruction of a holographic image and a phase recovery method with real-time performance. There are many deep learning-based techniques that have been proposed for the holographic image reconstruction, but these deep learning-based methods can still lack in performance, time complexity, accuracy, and real-time performance. Due to iterative calculation, the generation of a CGH requires a long computation time. A novel deep generative adversarial network holography (GAN-Holo) framework is proposed for hologram reconstruction. This novel framework consists of two phases. In phase one, we used the Fresnel-based method to make the dataset. In the second phase, we trained the raw input image and holographic label image data from phase one acquired images. Our method has the capability of the noniterative process of computer-generated holograms (CGHs). The experimental results have demonstrated that the proposed method outperforms the existing methods.

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Zhang, Tong, Ichirou Yamaguchi e Hywel Morgan. "Digital Holographic Microscopy". Microscopy and Microanalysis 5, S2 (agosto 1999): 362–63. http://dx.doi.org/10.1017/s1431927600015130.

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We applied phase-shifting digital holography to microscopy in this paper. At first lensless microscopy is proposed, in which no optical adjustment is necessary. Then, the method is applied to relax the limitation of focal depth in traditional optical microscopy. A theory for image formation and experimental verification using a few specimens are described.keywords: microscopy, digital holography, phase shiftingDue to the finite focal depth of an imaging lens, a limitation to normal optical microscopy-is that, only the 2-dimensional (2-D) information of an object can be obtained at one time. Besides, it is not convenient for quantitative analysis the observed image. Optical sectioning microscopy (OSM) and scanning confocal microscopy (SCM) which use opto-electronic detection have been proposed for quantitative analysis of a 3-D object. However, the former requires critical mechanical adjustment, while the latter uses timeconsuming mechanical 3-D scanning. Holographic microscopy can solve these problems because it can record 3-D information at one time. But, the chemical processing of holograms and the mechanical focusing at the reconstructed images cause more or less trouble. A 3-D imaging technique without use of photographic recording called optical scanning holography has recently been reported. However, there are also some trouble owing to the twin-image noise.

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Tahara, Tatsuki, Reo Otani e Yasuhiro Takaki. "Wavelength-Selective Phase-Shifting Digital Holography: Color Three-Dimensional Imaging Ability in Relation to Bit Depth of Wavelength-Multiplexed Holograms". Applied Sciences 8, n. 12 (28 novembre 2018): 2410. http://dx.doi.org/10.3390/app8122410.

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The quality of reconstructed images in relation to the bit depth of holograms formed by wavelength-selective phase-shifting digital holography was investigated. Wavelength-selective phase-shifting digital holography is a technique to obtain multiwavelength three-dimensional (3D) images with a full space-bandwidth product of an image sensor from wavelength-multiplexed phase-shifted holograms and has been proposed since 2013. The bit resolution required to obtain a multiwavelength holographic image was quantitatively and experimentally evaluated, and the relationship between wavelength resolution and dynamic range of an image sensor was numerically simulated. The results indicate that two-bit resolution per wavelength is required to conduct color 3D imaging.

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Khan, Javed I., e David Y. Y. Yun. "Holographic image archive". Computerized Medical Imaging and Graphics 20, n. 4 (luglio 1996): 243–57. http://dx.doi.org/10.1016/s0895-6111(96)00017-1.

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Semenov, Vladimir. "Registration of the dispersed composition of aerosol media by the holographic method". E3S Web of Conferences 279 (2021): 02001. http://dx.doi.org/10.1051/e3sconf/202127902001.

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The article describes a device based on the holographic method for measuring the parameters of dispersed aerosols. In the proposed device, the measured particle is irradiated with two beams perpendicular to the main radiation axis, while the resulting holographic image in each of the projections gives an increased amount of information (in contrast to existing solutions) about the parameters of the particles. The information obtained is processed layer by layer using digital holography methods to form a volumetric representation of the aerosol under study, which significantly increases the information content of measurements in comparison with existing devices. Methods and algorithms for layer-by-layer processing of the obtained holographic images are described, which make it possible to reconstruct the parameters of aerosols of complex shapes. The design of the device and an algorithm for layer-by-layer reconstruction of aerosol images are proposed.

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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.

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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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Kochańska, Paula Adrianna, e Michal Makowski. "Compression of computer-generated holograms in image projection". Photonics Letters of Poland 9, n. 2 (1 luglio 2017): 60. http://dx.doi.org/10.4302/plp.v9i2.719.

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Computer-generated holography is a technique of a lossless and lens-less forming of images. Methods that use local devices to compute such holograms are very power- and time-consuming. In order to make it possible to transfer the calculations to the cloud, it is necessary to elaborate efficient algorithms of a lossless compression. In this paper two methods of compression are presented and supported by both simulation and experimental results. A lossy compression method omitting certain bit-planes of the holographic data is also presented, which allows insignificant loss of information, while achieving a greater compression ratio. Full Text: PDF ReferencesM. Makowski "Simple holographic projection in color.", Opt. Express 20, 25130-25136 (2012). CrossRef M. Makowski, I. Ducin, K. Kakarenko, J. Suszek, A. Kowalczyk, "Performance of the 4k phase-only spatial light modulator in image projection by computer-generated holography, " Phot. Lett. Poland 8, 26-28 (2016). CrossRef A. Kowalczyk, M. Bieda, M. Makowski, I. Ducin, K. Kakarenko, J. Suszek, A. Sobczyk, "Analysis of computational complexity in holographic lens-less projection," Phot. Lett. Poland 6, 84-86 (2014). CrossRef M. Makowski, "Minimized speckle noise in lens-less holographic projection by pixel separation," Opt. Express 21, 29205-29216 (2013). CrossRef H. Niwase, N. Takada, H. Araki, Y. Maeda, M. Fujiwara, H. Nakayama, T. Kakue, T. Shimobaba, T. Ito "Real-time electroholography using a multiple-graphics processing unit cluster system with a single spatial light modulator and the InfiniBand network." Opt. Eng. 55, 093108-093108 (2016). CrossRef T. Shimobaba and T. Ito, "Random phase-free computer-generated hologram", Opt. Express 23(7) 9549-9554 (2015) CrossRef S.R. Kodituwakku, "Comparison of lossless data compression algorithms for text data", Indian Journal of Computer Science and Engineering Vol 1 No 4 416-426 (2010) DirectLink

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Zong, Hua, He Zhang e Jinghui Qiu. "Accurate Imaging of Wide Beam Active Millimeter Wave Based on Angular Spectrum Theory and Simulation Verification". Photonics 8, n. 9 (17 settembre 2021): 397. http://dx.doi.org/10.3390/photonics8090397.

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Due to the fact that a millimeter-wave (MMW) has a strong ability to penetrate clothing, MMW holographic imaging technology can conduct a non-contact inspection of the human body’s surface. In recent years, personnel surveillance systems utilizing MMW holographic imaging technology has achieved rapid progress. However, limited by MMW holographic imaging’s image quality, the existing imaging technology cannot accurately detect whether the human body carries hidden objects. Additionally, real-time inspection requirements cannot be practically satisfied, and the system cost is relatively high. In this paper, a reconstruction algorithm with enhanced imaging quality, which can solve the problem of spherical wave attenuation with distance, making imaging results more accurate. The sampling conditions and imaging resolution are simulated and analyzed, which verify the azimuth resolution. Furthermore, the antenna beam’s holographic imaging simulation is optimized, effectively improving the quality of the reconstructed image. The proposed scheme provides theoretical support for determining antenna step and scanning aperture size in engineering and have theoretical guiding significance for improving the image quality of millimeter-wave holography and reducing system cost.

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Shoydin, S. A. "Synthesis of holograms received by a communication channel". Computer Optics 44, n. 4 (agosto 2020): 547–51. http://dx.doi.org/10.18287/2412-6179-co-694.

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A method for the synthesis of holograms that reconstruct a 3D image using two 2D images, including a topographic map of the surface of a 3D object and photographs of the texture of its surface obtained using coherent and incoherent radiation is proposed. The method is suitable for transmitting information about a 3D object via a communication channel at a distance and subsequent synthesis of holograms at a distance from the holography object. It can be used in augmented reality devices, when creating holographic cameras and 3D video cameras, in 3D projectors and microscopes, devices with a synthesized aperture. The proposed method for the remote hologram synthesis is suitable for reproducing 3D holographic images of distant objects at different parts of the electromagnetic spectrum. Examples of 3D image restoration in the infrared spectral range are given. The method is also suitable for the synthesis of holograms in the UV, THz, and even radio range.

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Miyashita, Toyokatsu, e Hiroyuki Hashiguchi. "Superresolved Image Restoration of Multifrequency Holographic Images". Japanese Journal of Applied Physics 29, S1 (1 gennaio 1990): 221. http://dx.doi.org/10.7567/jjaps.29s1.221.

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Ko, Kathryn. "Superimposed holographic image—guided neurosurgery". Journal of Neurosurgery 88, n. 4 (aprile 1998): 777–81. http://dx.doi.org/10.3171/jns.1998.88.4.0777.

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✓ Computerized tomography scanning—derived narrow band reflection holograms of patients undergoing craniofacial procedures were created to evaluate the applicability of superimposing these three-dimensional images (3-D) on the operative field during neurological surgery. These sterilized radiological holograms were positioned over the surgical site by using bone sutures as registration points between the skull and the 3-D image to serve as a visual template between the patient and surgeon. Surgeries were then performed with the surgeon looking through the radiological hologram at the patient. Holograms were accurate to within 2 mm (plus or minus) of the actual calvarial anatomy. The use of the holographic image as a visual guide during surgery eliminated intraoperative guesswork or free-handed contouring. To the author's knowledge, this is the first report of the superimposed holographic image used in situ during surgery.

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SEUBERT, A., e K. HEINZ. "ITERATIVE IMAGE RECOVERY IN HOLOGRAPHIC LEED". Surface Review and Letters 09, n. 03n04 (giugno 2002): 1413–23. http://dx.doi.org/10.1142/s0218625x02003949.

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We report that the quality of atomic images reconstructed directly within the framework of holographic low energy electron diffraction can suffer from considerable atomic displacements. These are due to serious disturbances of the holographic object wave which exist when the object owns the same translational symmetry as the arrangement of beam splitters, for example when the latter induce a substrate reconstruction. We propose and test an iterative procedure for reducing these disturbances by a hybrid combination of the holographic reconstruction and some data fitting procedure. A reliable atomic image results after only a few iteration steps.

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LAUTERBORN, W., E. SCHMITZ e A. JUDT. "EXPERIMENTAL APPROACH TO A COMPLEX ACOUSTIC SYSTEM". International Journal of Bifurcation and Chaos 03, n. 03 (giugno 1993): 635–42. http://dx.doi.org/10.1142/s0218127493000532.

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A liquid is subjected to sound of high intensity to generate a cloud of cavities or bubbles. The correlation between the sound output from the bubble cloud, which follows a subharmonic route to chaos with a low-dimensional strange attractor, and its spatial dynamics is investigated. Several approaches are used. In a light transmission experiment the light modulation resulting from the spatial dynamics gives an integrated measure similar to the acoustic output from a hydrophone. High speed photographic cinematography and, in particular, methods of high speed holographic cinematography are used and developed to capture the spatial dynamics of the three-dimensional bubble pattern, a filamentary structure resembling Lichtenberg figures. The series of three-dimensional images obtained via holography is digitized and analyzed via a transputer-based digital image processing system. First results show strong correlations among the behavior of individual bubbles and indicate a highly cooperative system. The method of high speed holographic cinematography developed together with a digital holographic image processing system will also be of use for the investigation of other complex space-time systems, for example, the Rayleigh-Bénard and Taylor-Couette systems, and is scheduled for fully three-dimensional turbulence studies.

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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.

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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.

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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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Hinsch, K. D. "Holographic particle image velocimetry". Measurement Science and Technology 13, n. 7 (20 giugno 2002): R61—R72. http://dx.doi.org/10.1088/0957-0233/13/7/201.

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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.

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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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Liu, Yulong, Shan Wu, Qi Xu e Hubin Liu. "Holographic Projection Technology in the Field of Digital Media Art". Wireless Communications and Mobile Computing 2021 (18 maggio 2021): 1–12. http://dx.doi.org/10.1155/2021/9997037.

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The advent of the digital age has given new forms and new connotations to artistic creation, and more and more digital media technologies have entered the stage of artistic creation and exhibitions. At present, holographic projection technology has become a hot application technology in the field of digital media art. The purpose of this paper is to explore the technical principles of holographic projection technology and its application in the field of digital media art, so as to provide suggestions for the application and promotion of holographic projection technology and the development and innovation of digital media art. First of all, this article understands the technical principles of holographic projection and its application status in various fields, especially in the field of digital media art, through relevant literature research. Then, this article introduces the digital holographic technology, virtual imaging technology, and computer simulation technology used in the realization of holographic projection technology. Then, based on the advantages of holographic projection technology in three-dimensional image recording and reproduction, this paper proposes to introduce holographic projection technology to digital art museums, digital art exhibitions, and other digital media art applications and to study the effect of holographic projection technology on art through simulation experiments, the effect of recording and reproducing the image of the work. Finally, the three-dimensional reconstruction image of the digital holographic projection experiment on the artwork is compared with the simulated image of the Contour GT profiler to verify the feasibility of applying the holographic projection technology to art exhibitions and the effect of three-dimensional image recording and reproduction. Research shows that the holographic projection technology can achieve 93.34% of the simulation effect of recording and reproducing 3D images of artworks. It is also found that 59.86% of the audience who pay attention to the art experience strongly support the application of holographic projection technology in digital media art fields such as digital art gallery. This fully proves the feasibility of applying holographic projection technology to digital art exhibitions and provides a full range of artistic experience for audiences who cannot be present.

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Wang, Jian Gang, Zhan Jun Yan e Wen Qiang Li. "Optical Design of Waveguide Holographic Binocular Display for Machine Vision". Applied Mechanics and Materials 427-429 (settembre 2013): 763–69. http://dx.doi.org/10.4028/www.scientific.net/amm.427-429.763.

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A binocular display can satisfy competition mechanism of biological vision system and improve display precision. A binocular optical system is designed with waveguide holography (WGH) for small size and light weight. A superimposed holographic volume grating can split the image bearing lights into two equal intensity light beams. The out-coupling waveguide holographic gratings for the left and right eyes can implement image extension and imaging display. The simulation and experimental results reveal that excellent optical performances can be achieved for little distortion of less than 0.05%(nearly zero), light weight of about only 32g, and compact size. The display information can also be overlaid the outside scenes in eyeglass augmented reality and Machine Vision Display applications.

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Tsang, Peter W. M., Jung-Ping Liu, Hoson Lam e Ting-Chung Poon. "Enhancing the Quality of Sampled Phase-Only Hologram (SPOH) Based on Time-Division Comb Filtering". Applied Sciences 10, n. 8 (15 aprile 2020): 2732. http://dx.doi.org/10.3390/app10082732.

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Generation of digital phase-only Fresnel holograms is an important research area in digital holography, as it leads to a substantial simplification of a holographic display system. However, the quality of the reconstructed image of a hologram without the magnitude component is heavily degraded. The problem can be reduced by down-sampling the intensity of an image prior to generating the hologram. The method, referred to as “sampled phase-only hologram” (SPOH) generation, results in reconstructed images that are masked with the pattern of the down-sampling lattice. This paper reports a novel, low complexity method to alleviate this problem through the concept of comb filtering. Results reveal prominent enhancement on the reconstructed image of a SPOH.

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Nienałtowski, Patryk, Maria Baczewska e Małgorzata Kujawińska. "Comparison of fixed and living biological cells parameters investigated with digital holographic microscope". Photonics Letters of Poland 12, n. 1 (31 marzo 2020): 13. http://dx.doi.org/10.4302/plp.v12i1.971.

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The statistical analysis and comparison of biophysical parameters of living and fixed, mouse embryonic fibroblasts cells are presented. The parameters are calculated based on phase measurements performed by means of a digital, holographic microscope. The phases are retrieved from off-axis, image plane holograms, followed by custom image segmentation and statistical analysis of cells’ surface, phase volume and dry mass. The results indicated statistically significant differences between fixed and living cell parameters, which is an important message for setting methodology for further diagnosis based on quantitative phase (label-free) analysis.Full Text: PDF References:K. Alm, et al. "Cells and Holograms – Holograms and Digital Holographic Microscopy as a Tool to Study the Morphology of Living Cells", InTech, 2013. [CrossRef]Y. Rivenson, Y. Wu, A. Ozcan, Light: "Deep learning in holography and coherent imaging", Science & Applications, 8, Art. No. 85 (2019) [CrossRef]Min, et al. Optics Letters, 42, Issue 2, pp. 227-230, (2017) [CrossRef]M. Baczewska, Measurements and analysis of cells and histological skin sections based on digital holographic microscopy, WUT master thesis, 2018. [CrossRef]P. Stępień, D. Korbuszewski, M. Kujawińska, "Digital Holographic Microscopy with extended field of view using tool for generic image stitching", ETRI Journal, 41(1), 73-83, (2019). [CrossRef]S. Beucher, Serge, The Watershed Transformation Applied To Image Segmentation, Scanning microscopy. Supplement 6, (2000) [DirectLink]J. A. Hartigan, M. A. Wong, "A K-Means Clustering Algorithm", Applied Statistics, (1979) [CrossRef]J. Serra, Image Analysis and Mathematical Morphology, Academic Press, (1982) [DirectLink]P. Girshovitz, N. T. Shaked, "Generalized cell morphological parameters based on interferometric phase microscopy and their application to cell life cycle characterization", Biomedical Optics Express Vol. 3, Issue 8, pp. 1757-1773, (2012) [CrossRef]

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SALDIN, D. K. "HOLOGRAPHIC CRYSTALLOGRAPHY FOR SURFACE STUDIES: A REVIEW OF THE BASIC PRINCIPLES". Surface Review and Letters 04, n. 03 (giugno 1997): 441–57. http://dx.doi.org/10.1142/s0218625x97000432.

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In this paper, we review the basic principles of the technique of holographic crystallography (HXT) for surface studies. We discuss the appropriateness of the use of the term "holography" in this field in the light of its relation to other branches of that subject. We compare the effects of multiple scattering and the anisotropies of the reference and object waves on the computer reconstruction of images in HXT. We note that the twin-image problem of conventional holography is a direct consequence of the fact that the hologram is recorded on a two-dimensional surface. Like optical volume holography, which overcomes this problem by recording a diffraction pattern on a thick photographic emulsion, multienergy HXT does so by recording the pattern in a volume of reciprocal space. We consider the relative merits of different reconstruction algorithms, particularly proposals for reducing the deleterious effects of the anisotropies of the reference and object waves. We urge the use of techniques of modern computer graphics to render to full effect the striking 3D images reconstructed.

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Lin, Kuang Tsan, e Sheng Lih Yeh. "Hiding a Covert Digital Image by Assembling the RSA Encryption Method and the Binary Encoding Method". Mathematical Problems in Engineering 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/603659.

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The Rivest-Shamir-Adleman (RSA) encryption method and the binary encoding method are assembled to form a hybrid hiding method to hide a covert digital image into a dot-matrix holographic image. First, the RSA encryption method is used to transform the covert image to form a RSA encryption data string. Then, all the elements of the RSA encryption data string are transferred into binary data. Finally, the binary data are encoded into the dot-matrix holographic image. The pixels of the dot-matrix holographic image contain seven groups of codes used for reconstructing the covert image. The seven groups of codes are identification codes, covert-image dimension codes, covert-image graylevel codes, pre-RSA bit number codes, RSA key codes, post-RSA bit number codes, and information codes. The reconstructed covert image derived from the dot-matrix holographic image and the original covert image are exactly the same.

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Cheng, Yih-Shyang, e Ray-Cheng Chang. "Image-plane cylindrical holographic stereogram". Applied Optics 39, n. 23 (10 agosto 2000): 4058. http://dx.doi.org/10.1364/ao.39.004058.

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Shimobaba, Tomoyoshi, Yutaka Endo, Ryuji Hirayama, Yuki Nagahama, Takayuki Takahashi, Takashi Nishitsuji, Takashi Kakue et al. "Autoencoder-based holographic image restoration". Applied Optics 56, n. 13 (17 febbraio 2017): F27. http://dx.doi.org/10.1364/ao.56.000f27.

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29

Shen, X. A., E. Chiang e R. Kachru. "Time-domain holographic image storage". Optics Letters 19, n. 16 (15 agosto 1994): 1246. http://dx.doi.org/10.1364/ol.19.001246.

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30

Kou, Shan Shan, e Colin J. R. Sheppard. "Image formation in holographic tomography". Optics Letters 33, n. 20 (14 ottobre 2008): 2362. http://dx.doi.org/10.1364/ol.33.002362.

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31

Bruckstein, Alfred M., Robert J. Holt e Arun N. Netravali. "Low discrepancy holographic image sampling". International Journal of Imaging Systems and Technology 15, n. 3 (2005): 155–67. http://dx.doi.org/10.1002/ima.20051.

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32

Bryanston-Cross, P. J., M. Funes-Gallanzi, C. Quan e T. R. Judge. "Holographic particle image velocimetry (HPIV)". Optics & Laser Technology 24, n. 5 (ottobre 1992): 251–56. http://dx.doi.org/10.1016/0030-3992(92)90066-b.

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33

Bruckstein, Alfred Marcel, Martianus Frederic Ezerman, Adamas Aqsa Fahreza e San Ling. "Patch-Based Holographic Image Sensing". SIAM Journal on Imaging Sciences 14, n. 1 (gennaio 2021): 198–223. http://dx.doi.org/10.1137/20m1324041.

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34

Weierstall, U., X. M. Huang e J. C. H. Spence. "Twin Image Suppression and Field Inhomogeneity in In-Line Electron Holography." Microscopy and Microanalysis 3, S2 (agosto 1997): 1143–44. http://dx.doi.org/10.1017/s1431927600012605.

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Abstract (sommario):

Several methods have been suggested for elliminating the twin image in in-line holography, including Franhofer holography as used in our previous work, integration over focus, integration over wavelength, integration over lateral source position and recursion methods such as Gerchberg-Saxton or Fienup (see for all refs.). Fraunhofer holography requires the Fresnel number N =, with d the object size. The integration methods depend on the fact that the real and virtual images have different dependencies on some parameter such as focus, and have proved powerful in photoemission holographic diffraction. Here we apply focus integration and recursion to low voltage, point-projection images of carbon films, and discuss the effects of inhomogeneities in the electric field which arise when the tip is very close to a fibre-shaped sample such as DNA. by embedding biomolecules in solid Xenon at 55K, and using a beam energy of about 9 volts (less than the Xenon bandgap minus the electron affinity), radiation damage to the molecule may be minimized, while the molecule is gently supported by an almost electron transparent medium.

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35

Hei Hung, Fan, e Y. Lam Edmund. "Object Alignment with Refocused Image Using Off-Axis Digital Holography". Electronic Imaging 2021, n. 6 (18 gennaio 2021): 335–1. http://dx.doi.org/10.2352/issn.2470-1173.2021.6.iriacv-335.

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In the semiconductor industry, the integrated circuit density is getting higher, which leads to a smaller margin of error for the bonding process. Therefore, accurate adjustments before bonding are often necessary. An accurate image alignment under a vision system is usually required to fine-tune the bonding position. However, a considerable depth of focus is sacrificed for sufficient resolution of the object, limiting the optics operation range. Digital holographic microscopy with digital refocusing is applied as an enhancement to extend the depth of focus. The proposed algorithm merges the image alignment method with a refocusing algorithm to extend the image alignment capability with digital holography. Tested with simulated images, the proposed algorithm showed no significant deviation to simulated parameters. Also, the alignment result is robust among several test patterns. Moreover, the overall time is reasonable for industrial application.

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Lee, Jonghyun, Youngrok Kim, Kihong Choi, Joonku Hahn, Sung-Wook Min e Hwi Kim. "Digital Incoherent Compressive Holography Using a Geometric Phase Metalens". Sensors 21, n. 16 (20 agosto 2021): 5624. http://dx.doi.org/10.3390/s21165624.

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We propose a compressive self-interference incoherent digital holography (SIDH) with a geometric phase metalens for section-wise holographic object reconstruction. We specify the details of the SIDH with a geometric phase metalens design that covers the visible wavelength band, analyze a spatial distortion problem in the SIDH and address a process of a compressive holographic section-wise reconstruction with analytic spatial calibration. The metalens allows us to realize a compressive SIDH system in the visible wavelength band using an image sensor with relatively low bandwidth. The operation of the proposed compressive SIDH is verified through numerical simulations.

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SALDIN, D. K., X. CHEN, J. A. VAMVAKAS, M. OTT, H. WEDLER, K. REUTER, K. HEINZ e P. L. DE ANDRES. "HOLOGRAPHIC LEED: A REVIEW OF RECENT PROGRESS". Surface Review and Letters 04, n. 05 (ottobre 1997): 991–1001. http://dx.doi.org/10.1142/s0218625x97001176.

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We review the basic ideas of holographic LEED, and the latest progress in the field. We compare several proposed computer reconstruction schemes. Using experimental diffuse LEED data from O/Ni(001) and K/Ni(001) surfaces, we show that the capability now exists for filtering out the effects on the diffraction patterns of possible long-range order amongst the adsorbates, thus making holographic LEED much more analogous to photoelectron holography. Inclusion of a scattered-wave kernel to compensate for the variation of the magnitude of the reference wave at the positions of potential object-wave sources enables the reconstruction of a fully three-dimensional image of substrate atoms in the immediate vicinity of atomic adsorbates from a set of just normal-incidence diffuse LEED patterns.

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Baba, Shigeyuki, Shinichi Yoshimura e Nobuhiro Kihara. "Inter-frame Image Processing Method for Recovering Holographic Images". Japanese Journal of Applied Physics 45, n. 2B (24 febbraio 2006): 1258–65. http://dx.doi.org/10.1143/jjap.45.1258.

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39

Zhuang, Kaige, e Zhijun Xue. "Public Information Dissemination Using Data Mining-Enabled Image Enhancement and Internet of Things". Mobile Information Systems 2021 (31 luglio 2021): 1–8. http://dx.doi.org/10.1155/2021/2489313.

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With the development of the Internet of Things, the requirement of a wide range of human-centered services may now make use of as many computing resources for media technologies and holographic images. The IoT system can monitor the status of equipment in real-time with a robust infrared image recognition algorithm. However, few researchers discuss data mining on images with valuable information. In this study, we present a generic approach that is based on the mining decision tree and holographic image improvement data analysis. We employed advanced data mining techniques to achieve image stability and use light to form a three-dimensional image with real space. The suggested model improves digital image signal transmission and noise through the grey neural network technique and, furthermore, utilization decision tree induction to create attributes-to-target label relations from image pixels. The experimental results show that the suggested approach may be highly efficient and effective for interactive image systems and image mining. Our approach may also be widely utilized and includes extremely efficient convergence systems for essential framework elements.

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40

Kim, Jinwoong, Yongjun Lim, Keehoon Hong, Hayan Kim, Hyun-Eui Kim, Jeho Nam, Joongki Park, Joonku Hahn e Young-ju Kim. "Electronic Tabletop Holographic Display: Design, Implementation, and Evaluation". Applied Sciences 9, n. 4 (18 febbraio 2019): 705. http://dx.doi.org/10.3390/app9040705.

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Most of the previously-tried prototype systems of digital holographic display are of front viewing flat panel-type systems having narrow viewing angle, which do not meet expectations towards holographic displays having more volumetric and realistic 3-dimensional image rendering capability. We have developed a tabletop holographic display system which is capable of 360° rendering of volumetric color hologram moving image, looking much like a real object. Multiple viewers around the display can see the image and perceive very natural binocular as well as motion parallax. We have previously published implementation details of a mono color version of the system, which was the first prototype. In this work, we present requirements, design methods, and the implementation result of a full parallax color tabletop holographic display system, with some recapitulation of motivation and a high-level design concept. We also address the important issue of performance measure and evaluation of a holographic display system and image, with initial results of experiments on our system.

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41

Takahashi, Takayuki, Tomoyoshi Shimobaba, Takashi Kakue e Tomoyoshi Ito. "Time-Division Color Holographic Projection in Large Size Using a Digital Micromirror Device". Applied Sciences 11, n. 14 (7 luglio 2021): 6277. http://dx.doi.org/10.3390/app11146277.

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Abstract (sommario):

Holographic projection is a simple projection as it enlarges or reduces reconstructed images without using a zoom lens. However, one major problem associated with this projection is the deterioration of image quality as the reconstructed image enlarges. In this paper, we propose a time-division holographic projection, in which the original image is divided into blocks and the holograms of each block are calculated. Using a digital micromirror device (DMD), the holograms were projected at high speed to obtain the entire reconstructed image. However, the holograms on the DMD need to be binarized, thereby causing uneven brightness between the divided blocks. We correct this by controlling the displaying time of each hologram. Additionally, combining both the proposed and noise reduction methods, the image quality of the reconstructed image was improved. Results from the simulation and optical reconstructions show we obtained a full-color reconstruction image with reduced noise and uneven brightness.

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42

Chenliang Chang, Chenliang Chang, Yijun Qi Yijun Qi, Jun Wu Jun Wu, Jun Xia Jun Xia e Shouping Nie Shouping Nie. "Image magnified lensless holographic projection by convergent spherical beam illumination". Chinese Optics Letters 16, n. 10 (2018): 100901. http://dx.doi.org/10.3788/col201816.100901.

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43

Tiziani, H. J., e G. Pedrini. "Digital Double-Pulse Holographic Interferometry for Vibration Analysis". Shock and Vibration 3, n. 2 (1996): 117–25. http://dx.doi.org/10.1155/1996/231793.

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Different arrangements for double-pulsed holographic and speckle interferometry for vibration analysis will be described. Experimental results obtained with films (classical holographic interferometry) and CCD cameras (digital holographic interferometry) as storage materials are presented. In digital holography, two separate holograms of an object under test are recorded within a few microseconds using a CCD camera and are stored in a frame grabber. The phases of the two reconstructed wave fields are calculated from the complex amplitudes. The deformation is obtained from the phase difference. In the case of electronic speckle pattern interferometry (or image plane hologram), the phase can be calculated by using the sinusoid-fitting method. In the case of digital holographic interferometry, the phase is obtained by digital reconstruction of the complex amplitudes of the wave fronts. Using three directions of illumination and one direction of observation, all the information necessary for the reconstruction of the 3-dimensional deformation vector can be recorded at the same time. Applications of the method for measuring rotating objects are discussed where a derotator needs to be used.

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44

Sun, H., P. W. Benzie, N. Burns, D. C. Hendry, M. A. Player e J. Watson. "Underwater digital holography for studies of marine plankton". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 366, n. 1871 (25 gennaio 2008): 1789–806. http://dx.doi.org/10.1098/rsta.2007.2187.

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Conventional and digital holographies are proving to be increasingly important for studies of marine zooplankton and other underwater biological applications. This paper reports on the use of a subsea digital holographic camera (eHoloCam) for the analysis and identification of marine organisms and other subsea particles. Unlike recording on a photographic film, a digital hologram (e-hologram) is recorded on an electronic sensor and reconstructed numerically in a computer by simulating the propagation of the optical field in space. By comparison with other imaging techniques, an e-hologram has several advantages such as three-dimensional spatial reconstruction, non-intrusive and non-destructive interrogation of the recording sampling volume and the ability to record holographic videos. The basis of much work in optics lies in Maxwell's electromagnetic theory and holography is no exception: we report here on two of the numerical reconstruction algorithms we have used to reconstruct holograms obtained using eHoloCam and how their starting point lies in Maxwell's equations. Derivation of the angular spectrum algorithm for plane waves is provided as an exact method for the in-line numerical reconstruction of digital holograms. The Fresnel numerical reconstruction algorithm is derived from the angular spectrum method. In-line holograms are numerically processed before and after reconstruction to remove periodic noise from captured images and to increase image contrast. The ability of the Fresnel integration reconstruction algorithm to extend the reconstructed volume beyond the recording sensor dimensions is also shown with a 50% extension of the reconstruction area. Finally, we present some images obtained from recent deployments of eHoloCam in the North Sea and Faeroes Channel.

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Zhou, Hao, Ji Hua Gu e Da Qing Chen. "Multi-Plane 3-D Holographic Image Fusion in DCT Domain". Advanced Materials Research 760-762 (settembre 2013): 572–76. http://dx.doi.org/10.4028/www.scientific.net/amr.760-762.572.

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Abstract (sommario):

An improved multi-plane imaging fusion algorithm for 3-D digital holography is presented. Multiple reconstructed images at different distances from single off-axis Fresnel digital hologram are fused using discrete cosine transform (DCT) with different blocks. The zero order term is removed using a Laplacian operator while the conjugate image and dispersed images of defocused objects are eliminated by selecting a simple rectangular window before image fusion. Compared with those fused images obtained directly from the reconstructed images, the fused images qualities are greatly improved and all of the objects will be clearly in focus more quickly than discrete wavelet (DWT) based fusion method.

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46

Kelly, Damien P., David S. Monaghan, Nitesh Pandey, Tomasz Kozacki, Aneta Michałkiewicz, Grzegorz Finke, Bryan M. Hennelly e Malgorzata Kujawinska. "Digital Holographic Capture and Optoelectronic Reconstruction for 3D Displays". International Journal of Digital Multimedia Broadcasting 2010 (2010): 1–14. http://dx.doi.org/10.1155/2010/759323.

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Abstract (sommario):

The application of digital holography as a viable solution to 3D capture and display technology is examined. A review of the current state of the field is presented in which some of the major challenges involved in a digital holographic solution are highlighted. These challenges include (i) the removal of the DC and conjugate image terms, which are features of the holographic recording process, (ii) the reduction of speckle noise, a characteristic of a coherent imaging process, (iii) increasing the angular range of perspective of digital holograms (iv) and replaying captured and/or processed digital holograms using spatial light modulators. Each of these challenges are examined theoretically and several solutions are put forward. Experimental results are presented that demonstrate the validity of the theoretical solutions.

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47

Wu, Pei-Jung, Chih-Hao Chuang, Chien-Yu Chen, Jeng-Han Wu e Bor-Shyh Lin. "An Augmented Reality Head-Up Display System with a Wide-View Eyebox". International Journal of Optics 2020 (30 giugno 2020): 1–9. http://dx.doi.org/10.1155/2020/4719268.

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This study proposes to apply the combination of two 90-degree prisms and a holographic optical element to an image-dividing element, divide an image into three through the virtual image projection system, and accurately project the images to 160 cm behind the windshield. In order to distinguish the left image, middle image, and right image at the horizontal direction, the 90-degree prism is first utilized for horizontally deflecting the light, a holographic optical element is then used for presenting the vertical deflection of the image, and finally, the images are horizontally arranged as a real image on the diffuser. An image-dividing element is eventually integrated to the virtual image projection system. Then, the divided images are made as a virtual image which is projected to 160 cm behind the windshield to combine with the street scene. The horizontal angle of view of an eyebox is increased from 2.51° to 7.22°, and the size of the eyebox is 31.68 cm × 12.48 cm, allowing a wide-view laser-based head-up display with the large-angle beam-splitting function being successfully designed. It would not affect the field of view on the road, and this system could reduce the space and be arranged easily in a vehicle. Therefore, this proposed system is suitable for the aftermarket.

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Seo, Wontaek, Hoon Song, Jungkwuen An, Juwon Seo, Geeyoung Sung, Yun-Tae Kim, Chil-Sung Choi et al. "Image Quality Assessment for Holographic Display". Electronic Imaging 2017, n. 12 (29 gennaio 2017): 186–90. http://dx.doi.org/10.2352/issn.2470-1173.2017.12.iqsp-241.

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49

Wang Ying-Li, Yao Bao-Li, Chen Yi, Fan Mei-Gong, Zheng Yuan, Menke Nei-Mu-Le, Lei Ming et al. "Polarization holographic image storage with indolylfulgimide". Acta Physica Sinica 53, n. 1 (2004): 66. http://dx.doi.org/10.7498/aps.53.66.

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50

Huebschman, Michael L., Bala Munjuluri e Harold R. Garner. "Dynamic holographic 3-D image projection". Optics Express 11, n. 5 (10 marzo 2003): 437. http://dx.doi.org/10.1364/oe.11.000437.

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