• Journal of the Institute of Electronics and Information Engineers
• /
• v.54 no.6
• /
• pp.17-21
• /
• 2017

Since holographic data storage has the advantage of high recording density and data transfer rate, it is a candidate for the next generation storage systems. However, Holographic data storage system is affected by interpage interference and two dimensional intersymbol interference. Also, burst error occurs by physical impact. In this paper, we propose an LDPC product code using modified log-likelihood ratio and extrinsic information to correct burst error and improve performance of holographic data storage. The performance of proposed LDPC product code is 0.5dB better than that of the conventional LDPC code.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.21 no.9
• /
• pp.829-834
• /
• 2008

Two-dimensional photonic quasicrystal (PQCs) template patterns have been fabricated on a 1.1 ${\mu}m$-thick DMI-150 photoresist using a multiple-exposure holographic method. A 442-nm HeCd laser was utilized as a light source and the holographic exposure was carried out at a fixed angle of ${\theta}$ = 6$^{\circ}$. After the first holographic exposure, the sample was rotated to a proper angle and the second exposure was performed to the same manner. This exposure process was repeated n/2 times to obtain n-fold symmetric PQC patterns and then the sample was developed. The diffraction patterns of the fabricated PQC template were observed using a 632.8-nm HeNe laser. The fabricated PQCs exhibited 8, 10 and 12-fold rotational symmetry, which was in a good agreement with the interference simulation results. In addition, the diffraction patterns with n-rotation symmetry were observed for the corresponding n-fold PQCs. We believe that the multiple-exposure holography is a good method to fabricate the mesoscale PQCs with a high rotational symmetry.

• Transactions of the Society of Information Storage Systems
• /
• v.3 no.4
• /
• pp.173-177
• /
• 2007

A photo-reactive methacrylate monomer having triazine as a core component was examined for photochromic diffractive image formation. Photochromic photopolymer films as a recording media contained a monomer mixture of triazine difunctional metharylate (DT) and ethylene glycol phenyl ether acrylate, binder polymer, photo initiator, and a photochromic spiro-oxazine dye. The content of photochromic dye was changed to examine the effect of photochromophore on diffraction efficiency and real holographic image formation. Holographic recording was performed on the photopolymer film by the combination of reference and probe beam. The diffraction efficiency of the photopolymer film in real-time measurement reached a maximum of $\sim90%$ within 30s. It was highly dependent on the photochromophore contents. After holographic recording, the color of the recorded area was changed under UV light (365 nm) and reversibly bleached to original color upon exposure to a visible light source. Films containing only photochromophore without monomer mixture were not reactive under the recording beam (491nm). Diffractive image formation and mechanism of the holographic recording in the presence of photochromophore will be presented.

• Korean Journal of Optics and Photonics
• /
• v.16 no.4
• /
• pp.345-353
• /
• 2005

We proposed a new and cost-effective method fer assembling holographic pickup modules without any high resolution vision system. Assembling was accomplished by adjusting photodiode package only, leading to a low cost, holographic pickup module. Focus and tracking error signals were simply determined by comparing spot sizes and by using the 3 beam method, respectively, based on four-sectional holographic optical elements. In experiment, we assembled a hologram module and estimated performance of the proposed method fur a holographic pickup module used in compact disc system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2009.11a
• /
• pp.197-197
• /
• 2009

We have investigated the holographic grating formation on Ag-doped amorphous chalcogenide AsGeSeS thin films with Ag thickness. Holographic gratings have been formed using Diode Pumped Solid State laser (DPSS, 532.0nm) under [P:P] polarized the intensity polarization holography. The diffraction efficiency was obtained by +1st order intensity.

• Electronics and Telecommunications Trends
• /
• v.32 no.5
• /
• pp.30-38
• /
• 2017

Digital holography is generally regarded as one of the most possible candidates for achieving a real 3D display system in that it can fully record and reconstruct the wave characteristics of light. In addition, 3D display systems based on digital holographic technology do not cause a vergence-accommodation mismatch problem. In this report, the recent trends in digital holographic display technology are described, and recent research results related to the fields of augmented reality and virtual reality are also briefly reported.

• Journal of Advanced Marine Engineering and Technology
• /
• v.22 no.3
• /
• pp.353-361
• /
• 1998

The study on the vibration characteristics of annular sector plates is important for structural engineers. In this study the vibration modes and their natural frequencies of annular sector plates clamped along the inner circumferential edge are obtained by the time average holographic interferometer according to the varying sector angle. The experimental results agree well with those obtained by the numerical analysis. The vibration characteristics of annular sector plates shows great dependence on the sector angle. The radial nodal lines converge to the center of annular sector plate.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2007.08b
• /
• pp.1753-1756
• /
• 2007

In the field of 3D display, holographic displays are the only technology allowing optimal user comfort. We have developed systems based on compact projection optics, that allow advantageous new features, like large size full-color3D scenes generated at high rate on a micro-display with state of the art resolution.

• Proceedings of the Optical Society of Korea Conference
• /
• 1990.07a
• /
• pp.87-93
• /
• 1990

Estimation and collection of the suitable recording materials are important for the fabrication of the holographic optical elements. In this study, silver halide emulsion, photoresist and dichromated gelatin are selected as a recording materials to investigate the properties and processing methods. Some parameters which affect the diffraction efficiencies of the holographic optical elements (HOE) are presented. As an example of the HOE, the results of design and the fabrication method of the off axis 12P hologram lens are also presented.

• Korean Journal of Optics and Photonics
• /
• v.5 no.2
• /
• pp.225-230
• /
• 1994

Main parameters and equations necessary for developing the holographic HUD are investigated. Air reflection recording method of obtaining good holographic reflection filters with minimized interference pattern noises is presented. Especially, a new method of correcting the center wavelength shift which takes place after the processing of the DCG film is suggested.gested.