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Increased depth of focus in random-phase-free holographic projection

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Chinese Optics Letters 2016年第12期14卷 55-59页

作者： Michal Makowski tomoyoshi Shimobaba tomoyoshi ito Warsaw University of Technology Faculty of Physics Graduate School of Engineering Chiba University

The recently proposed random-phase-free method enables holographic reconstructions with very low noise,which allows fine projections without time integration of sub-holograms. Here, we describe the additional advantage of this method, namely, the extended depth of sharp imaging. It can be attributed to a lower effective aperture of the hologram section forming a given image point at the projection screen. We experimentally compare the depth of focus and imaging resolution for various defocusing parameters in the cases of the random-phase method and the random-phase-free method. Moreover, we discuss the influence of the effective aperture in the presence of local obstacles in the hologram＇s plane.

关键词： projection holographic aperture obstacles pixel sharp camera attributed convergent shadow

Real-time gradation-expressible amplitude-modulationtype electroholography based on binary-weighted computer-generated hologram

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Chinese Optics Letters 2021年第11期19卷 8-15页

作者： Ren Noguchi Kohei Suzuki Yoshiki Moriguchi Minoru Oikawa Yuichiro Mori Takashi Kakue tomoyoshi Shimobaba tomoyoshi ito Naoki Takada Graduate School of Integrated Arts and Sciences Kochi UniversityKochi 780-8520Japan Research and Education Faculty Kochi UniversityKochi 780-8520Japan Graduate School of Engineering Chiba UniversityChiba 263-8522Japan

In amplitude-modulation-type electroholography, the binary-weighted computer-generated hologram(BW-CGH) facilitates the gradation-expressible reconstruction of three-dimensional(3 D) objects. To realize real-time gradation-expressible electroholography, we propose an efficient and high-speed method for calculating bit planes consisting of BW-CGHs. The proposed method is implemented on a multiple graphics processing unit(GPU) cluster system comprising 13 GPUs. The proposed BW-CGH method realizes eight-gradation-expressible electroholography at approximately the same calculation speed as that of conventional electroholography based on binary computer-generated holograms. Consequently, we were able to successfully reconstruct a real-time electroholographic 3 D video comprising approximately 180,000 points expressed in eight gradations at 30 frames per second.

关键词： gradation-expressible electroholography binary-weighted computer-generated hologram digital micromirror device computer-generated hologram

Real-time electroholography using a single spatial light modulator and a cluster of graphics-processing units connected by a gigabit Ethernet network

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Chinese Optics Letters 2020年第7期18卷 23-27页

作者： Hiromi Sannomiya Naoki Takada Tomoya Sakaguchi Hirotaka Nakayama Minoru Oikawa Yuichiro Mori Takashi Kakue tomoyoshi Shimobaba tomoyoshi ito Graduate School of Integrated Arts and Sciences Kochi UniversityKochiKochi 780-8520Japan Research and Education Faculty Kochi UniversityKochiKochi 780-8520Japan National Astronomical Observatory of Japan MitakaTokyo 181-8588Japan Graduate School of Engineering Chiba UniversityChibaChiba 263-8522Japan

Systems containing multiple graphics-processing-unit(GPU)clusters are difficult to use for real-time electroholography when using only a single spatial light modulator because the transfer of the computer-generated hologram data between the GPUs is *** overcome this bottleneck,we propose a rapid GPU packing scheme that significantly reduces the volume of the required data *** proposed method uses a multi-GPU cluster system connected with a cost-effective gigabit Ethernet *** tests,we achieved real-time electroholography of a three-dimensional(3D)video presenting a point-cloud 3D object made up of approximately 200,000 points.

关键词： real-time electroholography multiple-graphics processing unit cluster graphics processing unit gigabit Ethernet

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High-speed playback of spatiotemporal division multiplexing holographic 3D video stored in a solid-state drive using a digital micromirror device

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Chinese Optics Letters 2021年第9期19卷 121-126页

作者： Kohei Suzuki Minori Tao Yuki Maeda Hirotaka Nakayama Ren Noguchi Minoru Oikawa Yuichiro Mori Takashi Kakue tomoyoshi Shimobaba tomoyoshi ito Naoki Takada Graduate School of Integrated Arts and Sciences Kochi UniversityKochi 780-8520Japan Faculty of Science Kochi UniversityKochi 780-8520Japan National Astronomical Observatory of Japan Tokyo 181-8588Japan Research and Education Faculty Kochi UniversityKochi 780-8520Japan Graduate School of Engineering Chiba UniversityChiba 263-8522Japan

We propose a high-speed playback method for the spatiotemporal division multiplexing electroholographic three-dimensional(3D)video stored in a solid-state drive(SSD)using a digital micromirror *** spatiotemporal division multiplexing electroholography prevents deterioration in the reconstructed 3D video from a 3D object comprising many object *** the proposed method,the stored data is remarkably reduced using the packing technique,and the computer-generated holograms are played back at high ***,we successfully reconstructed a clear 3D video of a 3D object comprising approximately 1,100,000 points at 60 frames per second by reducing the reading time of the stored data from an SSD.

关键词： spatiotemporal division multiplexing electroholography digital micromirror device computer-generated hologram high-speed playback

The state-of-the-art in computer generated holography for 3D display

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Light(Advanced Manufacturing) 2022年第3期3卷 168-196页

作者： David Blinder Tobias Birnbaum tomoyoshi ito tomoyoshi Shimobaba Department of Electronics and Informatics(ETRO) Vrije Universiteit Brussel(VUB)Pleinlaan 2B-1050 BrusselBelgium IMEC Kapeldreef 75B-3001 LeuvenBelgium Graduate School of Engineering Chiba University1-33 Yayoi-choInage-kuChibaChibaJapan

Holographic displays have the promise to be the ultimate 3D display technology,able to account for all visual *** advances in photonics and electronics gave rise to high-resolution holographic display prototypes,indicating that they may become widely available in the near *** major challenge in driving those display systems is computational:computer generated holography(CGH)consists of numerically simulating diffraction,which is very computationally *** goal in this paper is to give a broad overview of the state-of-the-art in *** make a classification of modern CGH algorithms,we describe different algorithmic CGH acceleration techniques,discuss the latest dedicated hardware solutions and indicate how to evaluate the perceptual quality of *** summarize our findings,discuss remaining challenges and make projections on the future of CGH.

关键词： Digital holography Holographic display Computer generated holography High-performance computing FPGA Deep learning Visual quality assessment

Color representation method using RGB color binary-weighted computer-generated holograms

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Chinese Optics Letters 2018年第8期16卷 25-29页

作者： Masato Fujiwara Naoki Takada Hiromitsu Araki Shohei Ikawaa Yuki Maeda Hiroaki Niwase Minoru Oikawa Takashi Kakue tomoyoshi Shimobaba tomoyoshi ito Graduate School of h~teg＇rated Arts and Sciences Kochi University Kochi 780-8520 Japan 2Science Department Natural Sciences Cluster Research and Education Faculty Kochi University Kochi 780-8520 Japa Faculty of Science Kochi University Kochi 780-8520 .lapan IGraduate School of Engineering Chiba University Chiba 263-8522 Japan

We propose a method for color electroholography using a simple red-green-blue （RGB） gradation representa- tion method without controlling the respective brightness of tile reference RGB-colored lights. The proposed method uses RGB multiple bit planes comprising RGB binary-weighted computer-generated holograms with various light transmittanees. The object points of a given three-dimensional （3D） object are assigned to RGB nmltiple bit planes according to their RGB gradation levels. The RGB multiple bit planes are sequentially displayed in a tim-division-multiplexe- manner. Consequently, the proposed method yields a color gradation representation of a reconstructed 3D object.

关键词： RGB Color representation method using RGB color binary-weighted computer-generated holograms CGH

Real-time color holographic video reconstruction using multiple-graphics processing unit cluster acceleration and three spatial light modulators

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Chinese Optics Letters 2020年第1期18卷 18-22页

作者： Shohei Ikawa Naoki Takada Hiromitsu Araki Hiroaki Niwase Hiromi Sannomiya Hirotaka Nakayama Minoru Oikawa Yuichiro Mori Takashi Kakue tomoyoshi Shimobaba tomoyoshi ito Faculty of Science Kochi UniversityKochi 780-8520Japan Research and Education Faculty Kochi UniversityKochi 780-8520Japan Graduate School of Integrated Arts and Sciences Kochi UniversityKochi 780-8520Japan Center for Computational Astrophysics National Astronomical Observatory of JapanMitaka-shi 181-8588Japan Graduate School of Engineering Chiba UniversityChiba 263-8522Japan

We demonstrate real-time three-dimensional(3D)color video using a color electroholographic system with a cluster of multiple-graphics processing units(multi-GPU)and three spatial light modulators(SLMs)corresponding respectively to red,green,and blue(RGB)-colored reconstructing *** multi-GPU cluster has a computer-generated hologram(CGH)display node containing a GPU,for displaying calculated CGHs on SLMs,and four CGH calculation nodes using 12 *** GPUs in the CGH calculation node generate CGHs corresponding to RGB reconstructing lights in a 3D color video using pipeline ***-time color electroholography was realized for a 3D color object comprising approximately 21,000 points per color.

关键词： color electroholography real-time electroholography multiple-graphics processing unit cluster graphics processing unit

Gradation representation method using a binary-weighted computer-generated hologram based on pulse-width modulation

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Chinese Optics Letters 2017年第6期15卷 46-49页

作者： Masato Fujiwara Naoki Takada Hiromitsu Araki Chun Wei Ooi Shohei Ikawa Yuki Maeda Hiroaki Niwase Takashi Kakue tomoyoshi Shimobaba tomoyoshi ito Graduate School of Integrated Arts and Sciences Kochi University Kochi 780-8520 Japan Science Department Natural Sciences Cluster Research and Education Faculty Kochi University Kochi 780-8520 Japan Faculty of Science Kochi University Kochi 780-8520 Japan Graduate School of Engineering Chiba University Chiba 263-8522 Japan

We propose a simple gradation representation method using a binary-weighted computer-generated hologram（CGH） to be displayed on a high-speed spatial light modulator that can be controlled by the pulse-width modulation technique. The proposed method uses multiple bit planes comprising binary-weighted CGHs with various pulse widths. The object points of a three-dimensional（3D） object are assigned to multiple bit planes according to their gray levels. The bit planes are sequentially displayed in a time-division-multiplexed ***, the proposed method realizes a gradation representation of a reconstructed 3D object.

关键词： reconstructed displayed gradation modulator sequentially colors manner assigned camera calculating

Distribution of HBV genotypes among HBV carriers in Benin:phylogenetic analysis and virological characteristics of HBV genotype E

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World Journal of Gastroenterology 2005年第41期11卷 6410-6415页

作者： Kei Fujiwara Yasuhito Tanaka Etsuro Orito tomoyoshi Ohno Takanobu Kato Kanji Sugihara Izumi Hasegawa Mayumi Sakurai Kiyoaki ito Atsushi Ozasa Yuko Sakamoto Isao Arita Ahmed El-Gohary Agossou Benoit Sophie I Ogoundele-Akplogan Namiko Yoshihara Ryuzo Ueda Masashi Mizokami Department of Internal Medicine and Molecular Science Nagoya City University Graduate School of Medical Sciences NagoyaJapan Department of Clinical Molecular Informative Medicine Nagoya City University Graduate School of Medical Sciences NagoyaJapan AIDS Research Center National Institute of Infectious Disease TokyoJapan Agency for Cooperation in International Health Kumamoto Japan Clinical Pathology Department Faculty of Medicine Suez Canal UniversityIsmailiaEgypt Central National Blood Transfusion Center Cotonou Benin Hematology Lab-CNHUC Cotonou Benin

AIM: To determine the distribution of Hepatitis B virus (HBV) genotypes in Benin, and to clarify the virological characteristics of the dominant ***: Among 500 blood donors in Benin, 21 HBsAg-positive donors were enrolled in the study. HBV genotypes were determined by enzyme immunoassay and restriction fragment length polymorphism. Complete genome sequences were determined by PCR and direct ***: HBV genotype E (HBV/E) was detected in 20/21 (95.2%), and HBV/A in 1/21 (4.8%). From the age-specific prevalence of HBeAg to anti-HBe seroconversion (SC) in 19 HBV/E subjects, SC was estimated to occur frequently in late teens in HBV/*** comparison of four complete HBV/E genomes from HBeAg-positive subjects in this study and five HBV/E sequences recruited from the database revealed that HBV/E was distributed throughout West Africa with very low genetic divers ity (nucleotide homology 96.7-99.2%).Based on the sequences in the basic core promoter (BCP)to precore region of the nine HBV/E isolates compared to those of the other genotypes, a nucleotide substitution in the BCP, G1757A, was observed in HBV/***: HBV/E is predominant in the Republic of Benin, and SC is estimated to occur in late teens in HBV/E. The specific nucleotide substitution G1757A in BCP, which might influence the virological characteristics,is observed in HBV/E.

关键词： HBV genotype West Africa Basic corepromoter