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Hirotaka Nakayama

Bio: Hirotaka Nakayama is an academic researcher from Chiba University. The author has contributed to research in topics: Volumetric display & Frame rate. The author has an hindex of 15, co-authored 49 publications receiving 922 citations.


Papers
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Journal ArticleDOI
TL;DR: A rapid calculation method of Fresnel computer-generated-hologram (CGH) using look-up table and wavefront-recording plane (WRP) methods toward three-dimensional (3D) display is presented.
Abstract: A rapid calculation method of Fresnel computer-generated-hologram (CGH) using look-up table and wavefront-recording plane (WRP) methods toward three-dimensional (3D) display is presented. The method consists of two steps: the first step is the calculation of a WRP that is placed between a 3D object and a CGH. In the second step, we obtain an amplitude-type or phase-type CGH to execute diffraction calculation from the WRP to the CGH. The first step of the previous WRP method was difficult to calculate in real-time due to the calculation cost. In this paper, in order to obtain greater acceleration, we apply a look-up table method to the first step. In addition, we use a graphics processing unit in the second step. The total computational complexity is dramatically reduced in comparison with conventional CGH calculations. We show optical reconstructions from a 2,048×2,048 phase-type CGH generated by about 3×10(4) object points over 10 frames per second.

158 citations

Journal ArticleDOI
TL;DR: The HORN-6 special-purpose computer for holography is developed, which succeeds in creating a computer-generated hologram of a three-dimensional image composed of 1,000,000 points at a rate of 1 frame per second.
Abstract: We developed the HORN-6 special-purpose computer for holography. We designed and constructed the HORN-6 board to handle an object image composed of one million points and constructed a cluster system composed of 16 HORN-6 boards. Using this HORN-6 cluster system, we succeeded in creating a computer-generated hologram of a three-dimensional image composed of 1,000,000 points at a rate of 1 frame per second, and a computer-generated hologram of an image composed of 100,000 points at a rate of 10 frames per second, which is near video rate, when the size of a computer-generated hologram is 1,920 x 1,080. The calculation speed is approximately 4,600 times faster than that of a personal computer with an Intel 3.4-GHz Pentium 4 CPU.

125 citations

Journal ArticleDOI
TL;DR: The WRP method using Shifted-Fresnel diffraction to solve the former problem, and all the steps could be implemented on a GPU, and a large CGH was obtained from the object points at the video rate.
Abstract: We report the generation of a real-time large computer generated hologram (CGH) using the wavefront recording plane (WRP) method with the aid of a graphics processing unit (GPU). The WRP method consists of two steps: the first step calculates a complex amplitude on a WRP that is placed between a 3D object and a CGH, from a three-dimensional (3D) object. The second step obtains a CGH by calculating diffraction from the WRP to the CGH. The disadvantages of the previous WRP method include the inability to record a large three-dimensional object that exceeds the size of the CGH, and the difficulty in implementing to all the steps on a GPU. We improved the WRP method using Shifted-Fresnel diffraction to solve the former problem, and all the steps could be implemented on a GPU. We show optical reconstructions from a 1,980 × 1,080 phase only CGH generated by about 3 × 10(4) object points over 90 frames per second. In other words, the improved method obtained a large CGH with about 6 mega pixels (1,980 × 1,080 × 3) from the object points at the video rate.

99 citations

Journal ArticleDOI
TL;DR: This work implements an optimized CGH computation in their multi-graphics processing unit cluster system, which can calculate a CGH of 6,400×3,072 pixels from a three-dimensional object composed of 2,048 points in 55 ms.
Abstract: To overcome the computational complexity of a computer-generated hologram (CGH), we implement an optimized CGH computation in our multi-graphics processing unit cluster system. Our system can calculate a CGH of 6,400×3,072 pixels from a three-dimensional (3D) object composed of 2,048 points in 55 ms. Furthermore, in the case of a 3D object composed of 4096 points, our system is 553 times faster than a conventional central processing unit (using eight threads).

76 citations

Journal ArticleDOI
TL;DR: This work proposes time-division based color electroholography with a one-chip RGB Light Emitting Diode (LED) and a low-priced synchronizing controller and observed a multi-color 3D reconstructed movie at a frame rate of 20 Hz.
Abstract: We propose time-division based color electroholography with a one-chip RGB Light Emitting Diode (LED) and a low-priced synchronizing controller. In electroholography, although color reconstruction methods via time-division have already been proposed, the methods require an LCD with a high refresh rate and output signals from the LCD for synchronizing the RGB reference lights such as laser sources, which consequently increase the development cost. Instead of using such an LCD, the proposed method is capable of using a general LCD panel with a normal refresh rate of 60 Hz. In addition, the LCD panel used in the proposed method does not require the output signals from the LCD. Instead, we generated synchronized signals using an external controller developed by a low-priced one-chip microprocessor, and, use a one-chip RGB LED instead of lasers as the RGB reference lights. The one-chip LED allows us to decrease the development cost and to facilitate optical-axis alignment. Using this method, we observed a multi-color 3D reconstructed movie at a frame rate of 20 Hz.

73 citations


Cited by
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Journal ArticleDOI
TL;DR: In electro-holographic displays, holographic polymer-dispersed, and acousto-optic devices are used as holographic displays as mentioned in this paper, which are based on physical duplication of light distribution.
Abstract: True-3D imaging and display systems are based on physical duplication of light distribution. Holography is a true-3D technique. There are significant developments in electro-holographic displays in recent years. Liquid crystal, liquid crystal on silicon, optically addressed, mirror-based, holographic polymer-dispersed, and acousto-optic devices are used as holographic displays. There are complete electro-holographic display systems and some of them are already commercialized.

252 citations

Journal ArticleDOI
Yan Zhao1, Liangcai Cao1, Hao Zhang1, Dezhao Kong1, Guofan Jin1 
TL;DR: An angular-spectrum based algorithm for layer-oriented CGH that can avoid the huge computational cost of the point-oriented method and yield accurate predictions of the whole diffracted field compared with other layer- oriented methods is proposed.
Abstract: Fast calculation and correct depth cue are crucial issues in the calculation of computer-generated hologram (CGH) for high quality three-dimensional (3-D) display. An angular-spectrum based algorithm for layer-oriented CGH is proposed. Angular spectra from each layer are synthesized as a layer-corresponded sub-hologram based on the fast Fourier transform without paraxial approximation. The proposed method can avoid the huge computational cost of the point-oriented method and yield accurate predictions of the whole diffracted field compared with other layer-oriented methods. CGHs of versatile formats of 3-D digital scenes, including computed tomography and 3-D digital models, are demonstrated with precise depth performance and advanced image quality.

212 citations

Journal ArticleDOI
TL;DR: A simple and fast calculation algorithm for a computer-generated hologram (CGH) by use of wavefront recording plane and the total computational complexity is dramatically reduced in comparison with conventional CGH calculations.
Abstract: We present a simple and fast calculation algorithm for a computer-generated hologram (CGH) by use of wavefront recording plane The wavefront recording plane is placed between the object data and a CGH When the wavefront recording plane is placed close to the object, the object light passes through a small region on the wave recording plane The computational complexity for the object light is very small We can obtain a CGH to execute diffraction calculation from the wavefront recording plane to the CGH The computational complexity is constant The total computational complexity is dramatically reduced in comparison with conventional CGH calculations

202 citations

Journal ArticleDOI
TL;DR: Based on NbOx Mott memristors, the authors report artificial spiking afferent nerves for accessing spiking systems and demonstrate spiking mechanoreceptor systems.
Abstract: Neuromorphic computing based on spikes offers great potential in highly efficient computing paradigms. Recently, several hardware implementations of spiking neural networks based on traditional complementary metal-oxide semiconductor technology or memristors have been developed. However, an interface (called an afferent nerve in biology) with the environment, which converts the analog signal from sensors into spikes in spiking neural networks, is yet to be demonstrated. Here we propose and experimentally demonstrate an artificial spiking afferent nerve based on highly reliable NbOx Mott memristors for the first time. The spiking frequency of the afferent nerve is proportional to the stimuli intensity before encountering noxiously high stimuli, and then starts to reduce the spiking frequency at an inflection point. Using this afferent nerve, we further build a power-free spiking mechanoreceptor system with a passive piezoelectric device as the tactile sensor. The experimental results indicate that our afferent nerve is promising for constructing self-aware neurorobotics in the future.

190 citations