白木 厚司

In this paper, we report a portable and low-cost digital holographic microscopy (DHM). By adopting the Gabor hologram and using a web camera, point light source LED and open-source libraries, development costs were decreased. The cost and size of the setup were less than 7,500 yen (approximately 96 US dollars at 78 yen/dollar) and 120 mm×80 mm×55 mm, respectively. OSA 2012.

In this paper, we report a portable and low-cost digital holographic microscopy (DHM). By adopting the Gabor hologram and using a web camera, point light source LED and open-source libraries, development costs were decreased. The cost and size of the setup were less than 7,500 yen (approximately 96 US dollars at 78 yen/dollar) and 120 mm×80 mm×55 mm, respectively. © 2012 Optical Society of America.

Electroholography using a computer-generated hologram (CGH) is the ultimate technique for realizing 3-D television. We implemented an optimized CGH computation in our multi-GPU environmental PC with four GPUs. In the case of 3D object composed of 10, 240 points, our system is 215 times faster than a CPU.

An electro holography is one of the techniques for achieving three-dimensional television. We developed special-purpose computer HORN-7 for kinoform, which records the phase information of an object light. The HORN-7 can create a 2M pixels hologram of 16, 000 object points in 0.4 sec.

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. (C) 2011 Optical Society of America

We propose the use of a hologram plate, which can be used to reconstruct an active 3-dimensional image by changing the position of light sources. We experimented with using an optical system and reconstructed two kinds of 3-dimensional images by changing the position of the light sources. Theoretically, we can also reconstruct various 3-dimensional images. We then did a computer simulation to confirm our results, and we obtained the same result as that of an optical system. Furthermore, we divided the hologram into segments and did a computer simulation. We obtained reconstructed images from the hologram divided into the segments. We are now investigating the possibility of using the display of a cellular phone as a light source for the plate.

We have developed a one-unit system, including creating and displaying a hologram for real-time reproduction of a three-dimensional image via electroholography. We have constructed this one-unit system by connecting a special-purpose computer for holography and a special display board with a reflective liquid crystal display as a spatial light modulator. Using this one-unit system, we succeeded in reproducing a three-dimensional image composed of 10,000 points at a speed of 30 frames per second, which is the video rate in NTSC format. In addition, we were able to control a three-dimensional image in real-time using our system. (C) 2009 Optical Society of America

We have constructed a simple color electroholography system that has excellent cost performance. It uses a graphics processing unit (GPU) and a liquid crystal display (LCD) projector. The structure of the GPU is suitable for calculating computer-generated holograms (CGHs). The calculation speed of the GPU is approximately 1,500 times faster than that of a central processing unit. The LCD projector is an inexpensive, high-performance device for displaying CGHs. It has high-definition LCD panels for red, green and blue. Thus, it can be easily used for color electroholography. For a three-dimensional object consisting of 1,000 points, our system succeeded in real-time color holographic reconstruction at rate of 30 frames per second. (C) 2009 Optical Society of America

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. (C) 2009 Optical Society of America

Electroholography is one of the techniques for achieving 3-Dimensional (3-D) television. We connected a special-purpose computer for holography and to a display board with a high-definition reflective liquid crystal display, and then we constructed the integration system to make and to display the computer generated hologram. We succeeded in the reproducing 14 frames per second in a 3-D image composed of about 6,000 points using this system.

In optics, several diffraction integrals, such as the angular spectrum method and the Fresnel diffraction, are used for calculating scalar light propagation. The calculation result provides us with the optical characteristics of an optical device, the numerical reconstruction image from a hologram, and so forth. The acceleration of the calculation commonly uses the fast Fourier transform; however, in order to analyze a three-dimensional characteristic of an optical device and compute real-time reconstruction from holograms, recent computers do not have sufficient computational power. In this paper, we develop a numerical calculation library for the diffraction integrals using the graphic processing unit (GPU), the GWO library, and report the performance of the GWO library. The GPU chip allows us to use a highly parallel processor. The maximum computational speed of the GWO library is about 20 times faster than a personal computer.

In this paper, we report an interactive color electroholography system using the field-programmable gate array (FPGA) technology and the time division switching method for color reconstruction. We implemented 30 dedicated-processors for a computer-generated hologram (CGH) into an FPGA chip, and the FPGA chip can generate full-parallax CGHs, on which we record color information for a color 3D object, faster than a personal computer. The time division switching method can reconstruct a color 3D object from the CGHs, to make use of the afterimage effect on human eyes. The system allows us to perform interactive operations for a reconstructed color 3D object using a keyboard, while viewing the reconstructed color 3D object.

Electroholography can realize an ideal three-dimensional (3D) display system however, a practical 3D display using this technique has not been developed yet because electroholography has several problems. The typical problems are the color representation ability for a reconstructed 3D image, and the calculation time for generating a CGH (Computer-Generate-Hologram). In this paper, we report our electroholography system that can calculate CGHs in real-time, and reconstruct color 3D objects from the CGHs. In this system, for the purpose of solving the color reconstruction problem, we used the space-division method and an error diffusion method. The space-division method proposed by one of the authors can reconstruct a color 3D object from one hologram. For real-time calculation for a CGH, we used a GPU (Graphic Processing Unit) cluster. A recent GPU is able to treat as a highly parallel processor. The GPU cluster consists of a PC cluster, whose nodes have a GPU.

Electroholography is one of the techniques for achieving three-dimensional (3-D) television. We connected a special-purpose computer for holography to a display board with a high-definition reflective liquid crystal display. We succeeded in reproducing 30 frames per second in a 3-D image composed of about 2,000 points using this system.

In this paper, we report an electroholographic reconstruction method for a colour three-dimensional (3D) object, using the time division switching of reference lights. We use a reflective liquid crystal display (LCD) panel with a high refresh rate as a spatial light modulator. A colour 3D object is divided into red, green and blue components, from which we compute three computer-generated holograms (CGHs). The LCD panel displays the CGHs in sequence at a refresh rate of about 100 Hz. The LCD panel also outputs synchronized signals, indicating that one of the CGHs is currently displayed on the LCD panel. Red, green and blue light emitting diodes (LEDs), as used for reference lights, are switched by the synchronized signals. As a result of the afterimage effect on human eyes, we can clearly observe a coloured 3D object.

We have applied the graphics processing unit (GPU) to computer generated holograms (CGH) to overcome the high computational cost of CGH and have compared the speed of a GPU implementation to a standard CPU implementation. The calculation speed of a GPU (GeForce 6600, nVIDIA) was found to be about 47 times faster than that of a personal computer with a Pentium 4 processor. Our system can realize real-time reconstruction of a 64-point 3-D object at video rate using a liquid-crystal display of resolution 800 x 600. (c) 2006 Optical Society of America.

In recent years, research of electroholography is studied in various fields. However, since there is not a sufficient device for displaying computer generated hologram, generally it is not put to practical use yet. Then, we put several liquid crystal display panels in order and made a large display area. Consequently, we were able to obtain the larger reconstruction image than the case that only one liquid crystal display panel was used.

We developed an electroholography unit, which consists of a special-purpose computational chip for holography and a reflective liquid-crystal display (LCD) panel, for a three-dimensional (3D) display. The special-purpose chip can compute a computer-generated hologram of 800 x 600 grids in size from a 3D object consisting of approximately 400 points in approximately 0.15 seconds. The pixel pitch and resolution of the LCD panel are 12 mu m and 800 x 600 grids, respectively. We implemented the special purpose chip and LCD panel on a printed circuit board of approximately 28cm x 13cm in size. After the calculation, the computer-generated hologram produced by the special-purpose chip is displayed on the LCD panel. When we illuminate a reference light to the LCD panel, we can observe a 3D animation of approximately 3cm x 3cm x 3cm in size. In the present paper, we report the electroholographic display unit together with a simple 3D display system. (C) 2005 Optical Society of America.

In electroholography, a real-time reconstruction is one of the grand challenges. To realize it, we developed a parallelized high-performance computing board for computer-generated hologram, named HORN-5 board, where four large-scale field programmable gate array chips were mounted. The number of circuits for hologram calculation implemented to the board was 1,408. The board calculated a hologram at higher speed by 360 times than a personal computer with Pentium4 processor. A personal computer connected with four HORN-5 boards calculated a hologram of 1,408 x 1,050 made from a three-dimensional object consisting of 10,000 points at 0.0023 s. In other words, beyond at video rate (30 frames / s), it realized a real-time reconstruction. (C) 2005 Optical Society of America.

We developed an electroholography unit for a three-dimensional display, which consists of a special-purpose computational chip and a high minute reflective liquid-crystal display panel. We implemented them on one board whose size is approximately 28 cm x 13 cm. The chip can compute a computer-generated hologram whose size is 800 x 600 at nearly real time (0.15 s) for an object consisting of 400 points. After the calculation, the LCD panel. displays the computer generated hologram made by the chip, and we can observe a three-dimensional (313) motion image whose size is approximately 3 cm x 3 cm x 3 cm. The pixel pitch of the display panel is 12 pm, and the resolution is 800 x 600. To obtain a 3D motion image with large viewing zone and image size, we need to parallelize the unit. The unit can be readily scaled up, since the units consisting of the chip and the display are easily set in parallel.

We have developed special-purpose computers, named HORN, for a computer-generated hologram. The latest machine HORN-5 calculates a hologram with a 1,408 by 1,050 resolution at video rate for an object consisting of 10,000 points. It is 1,000 times faster than a today's personal computer. We discuss the effectiveness of a special-purpose computer system for a real-time electroholography which requires enormous calculation cost.