• Proceedings of the Optical Society of Korea Conference
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• 2008.07a
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• pp.219-220
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• 2008

• Proceedings of the IEEK Conference
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• 2003.11a
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• pp.203-206
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• 2003

This study is focused on proposing a creative system that can display 3D hologram on the real-time basis. This method applies 3D display on volume hologram based on CGH. The process of implementing the system consists of two stages of fringe pattern recording for passive component that includes information on hologram, and irradiating object beam. Distinguished from an existing electronic holographic display system, this system is free from the process of a huge calculation that is necessary to compose CGH for a real-time 3D display.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.2
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• pp.101-109
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• 1998

In this paper, we implemented holographic optical memory systm which can store and reconstruct many images using new input and angular multiplexing method. In the new input method, phase infomation of input image is inputed in the recording material instead of brightness information. To do so, we represented the images, which captured with CCD camera or displayed on the computer monitor, on the liquid crystal television(LCTV) which removed polarizer/analyzer. Therefore, we can generate uniform input beam intensity regardless of the total brightness of input image, and apply the scheduled recording method. Also we can increase the intensity of input beam so reduce the recording time of input image. And reconstructedimage is acquired by transforming phase information into brightness information of image with analyzer. The incident angle of reference beam is acquired by Fourier transform of the binary phase hologram(BPH) which designed with SA algorithm on the LCTV. The proposed optical memory system is stable because the incident angle of the reference beam is controlled easy and electronically. We demonstreated optical experiment which store and reconstruct various type images in BaTiO$_{3}$ using proposed holographic memory system.

• Transactions of the Society of Information Storage Systems
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• v.1 no.1
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• pp.1-22
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• 2005

There are two important trends in the modern information society, including digital networking and ubiquitous environment. Thus it is strongly required to develop new information storage devices such as high density storages to match the increased data capacity and small size storage devices to be applied to the mobile multimedia electronics. So far, many approaches have been studied for the high density memory, including the holographic memory, super-RENS and near-field recording using solid immersion lens (SIL) or nano-probe for the ODD (Optical Disk Drive) system, and the perpendicular magnetic recording and heat-assisted magnetic recording for the HDD (Hard Disk Drive) system. In addition, new mobile storage devices have been prepared using 0.85" HDD and 30mm ODD systems from a lot of foreign and domestic companies and institutes. In this paper, the recent technology trend for the next generation information storage system is summarized to offer a research motivation and encouragement to new researchers in this field with an emphasis on the technical issues of the increase of data capacity and decrease of device size.

• Journal of the Optical Society of Korea
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• v.4 no.1
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• pp.66-70
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• 2000

The main problem of image projection on a transmission type holographic screen is color sepa-ration. And it can be overcome by using a long narrow slit type diffuser as a source of the object beam when we record the screen. But that screen is not optimized and so needs changing several conditions. To set up the system many complicate things should be taken into accounted so it is very important to analyze the basic structure by simple concepts and calculations. We designed the system so that recording and projection axis coincide in one line and showed that the analysis of the system is very simple. We did it by a 1st order paraxial approximation calculation and it was good enough to describe the system. The photo-emulsion layer shrinks after processing of the hologram. It induced unsatisfactory color matching at the viewing zone. To overcome this effect, we pre-checked the shrinkage rate of an emulsion layer by experiments and modified the recording set up to compensate for the amount of shrinkage.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.05a
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• pp.92-95
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• 2005

The silver photodoping effect in amorphous AsGeSeS chalcogenide thin films for holographic recording has been investigated using a HeNe laser ($\lambda$=632.8 nm). The chalcogenide films prepared in this work were thinner in comparison with the penetration depth of recording light ($d_p$=1.66 mm). The variation of the diffraction efficiency $(\eta)$ in amorphous chalcogende films exhibits a tendency, independently of the Ag photodoping. That is, n increases relatively rapidly at the beginning of the recording process, reaches the maximum $({\eta}_{max})$ and slowly decreases. In addition, the value of ${\eta}_{max}$ depends strongly on chalcogenide film thickness(d) and its peak among the films with d = 40, 80, 150, 300, and 633 nm is observed at d = 150 nm (approximately 1/2n), where n is refractive index of the chalcogenide (n=2.0). The ${\eta}$ is largely enhanced by Ag photodoping into the chalcogenides. In particular, the value of hmax in a bilayer of 10-nm-thick Ag/150-nm-thick AsGeSeS film is about 1.6%, which corresponds to ~20 times in comparison with that of the AsGeSeS film (without Ag).

• Korean Journal of Optics and Photonics
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• v.9 no.3
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• pp.199-204
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• 1998

To increase the storage density in hologram recording, a simple scheme to obtain rotational, angular and spatial multiplexing efficiently at the same time is proposed and experimented. Both rotational multiplexing and angular multiplexing are obtained by controlling the reference beam directly by use of a pair of wedge prisms, while spatial multiplexing is obtained by shifting the recording medium in the recording plane. It is possible to get both an acute-angle geometry, in which the angle between the signal and reference beams is less than 90$^{\circ}$, and a 90$^{\circ}$ geometry, in which the angle is approximately 90$^{\circ}$. In experiment, 180 holograms were multiplexed with an acute-angle geometry where a photopolymer was used for the recording medium, and 147 holograms with 90$^{\circ}$ geometry where a Fe-doped LiNbO$_3$ crystal was used. The proposed scheme makes it easy it easy to realize a practical holographic memory system by simplifying the control of three complex mechanical motions that are necessary for the three multiplexing techniques.

• Korean Journal of Optics and Photonics
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• v.14 no.6
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• pp.663-668
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• 2003

We studied a localized hologram recording method that can be used in a disk-shaped medium. In this method, the reference beam is focused by use of a cylindrical lens to get a thin spot in the medium, and then a hologram is recorded in that spot by illuminating the signal beam. Many localized holograms are multiplexed by shifting the medium by a distance more than the thin spot size of the reference beam. This method does not need recording-time scheduling for uniform diffraction efficiencies. We show that a minimal required thickness of the recording medium exists for a given spot size of the signal beam. We performed experiments for data storage and retrieval, and obtained a storage density of 20 bits/${\mu}{\textrm}{m}$$^2$ and a raw-bit error rate (RBER) of 2.5${\times}$10$^{-3}$ , when a 2 mm-thick Fe-doped LiNbO$_3$ crystal was used.

• Journal of Science Education
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• v.34 no.2
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• pp.203-210
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• 2010

The characteristics of diffraction gratings, fabricated using Slavich PFG-01 plates as a holographic recording material, were investigated using various bleach techniques. The changes in diffraction efficiencies, under given development conditions, resulting from the use of a new reversal bleach and a new fixation free rehalogenating bleach are investigated. From the experimental results, it was found that the diffraction efficiencies are influenced by the composition of the developer, the reversal bleach and the fixation free rehalogenating bleach. In this study, the highest values of the maximum diffraction efficiency was obtained when PFG-01 plates were developed in AAC developers contained with l-ascorbic acid 20 g/L and sodium carbonate 60 g/L, processed by a reversal bleach, as high as 89.0%. Moreover, the maximum diffraction efficiency of 82.1% was obtained when PFG-01 plates were processed by a fixation free rehalogenating bleach. In addition, higher diffraction efficiencies are yielded in the case of the revesal bleach than in the case of the fixation free rehalogenating bleach.

• Journal of the Optical Society of Korea
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• v.20 no.1
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• pp.70-77
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• 2016

This paper proposes an optical system for complex holographic display that enhances the quality of the reconstructed three-dimensional image. This work focuses on a new design for an optical system and the evaluation of the complex holographic display, using a single spatial light modulator (SLM) and a circular grating. The optical system is based on a 4-f system in which the imaginary and real information of the hologram is displayed on concentric rectangular areas of the SLM and circular grating. Thus, this method overcomes the lack of accuracy in the pixel positions between two window holograms in previous studies, and achieves a higher intensity of the real object points of the reconstructed hologram than the original phase-reconstructed hologram. The proposed method provides approximately 30% less NMRS (Normal Root Mean Square) error, compared to previous systems, which is verified by both simulation and optical experiment.