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

• Korean Journal of Optics and Photonics
• /
• v.2 no.4
• /
• pp.193-196
• /
• 1991

Reflection holographic filters are developed. Dichromated gelatin films are used for the recording material, and a modified processing method of obtaining high-quality filters is developed. The diffraction efficiency and bandwidth of the fabricated holographic filter is 93% and 17 nm, respectively. The effect of exposure on the spectral bandwidth and center wavelength of the developed filters are measured, and the characteristics of the dichromated gelatin film are investigated from these results.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.24 no.5
• /
• pp.868-873
• /
• 1987

Holographic diffraction gratings which are the core element of the optical instruments such as a spectrophotometer have been fabricated using the photoresist as a recording material. A 488nm line from an argon laser is used in making the gratings. Transmission type surface-relief phase grating and reflection type which is fabsricated by coating the aluminum on the transmission type with thickness 2000\ulcornerare fabricated, the spatical frequency of which are 1200 lines/mm. Diffraction efficiency, scattered light and wave-front aberratin are measured to test the performance of the developed gratings. A marimum diffraction efficiency is given when light is incident at the Bragg angle. Theoretical efficiency is about 80%, but measured efficiency of the transmission type and reflection type is 50% and 45%, respectively.

• Transactions of the Society of Information Storage Systems
• /
• v.2 no.3
• /
• pp.189-195
• /
• 2006

Bragg detuning effect if, one of the serious problems if the photopolymer is used for the recording material of holography memories. And the critical reasons of that are known as the bulk refractive index change and shrinkage of recording material. However, the trials for analyzing the effect are mainly on the K-sphere and biased on the transmission hologram. So, we approached Bragg detuning effect numerically and applied the method to the transmission holograms and the reflection holograms all together. We simulated it with MATLAB. As a result, the bulk refractive index change causes+Bragg detuning effect on the transmission holograms and the reflection holograms. But the shrinkage leads to+Bragg detuning effect on the transmission hologram and-Bragg detuning effect on the reflective hologram. Compared to experimental result, the bulk refractive index change(${\fallingdotseq}4{\times}10^{-4}$) and the ratio of shrinkage to the thickness of the material(${\fallingdotseq}1.67{\times}10^{-3}$) could be matched with Bragg detuning effect on the transmission hologram and the reflection hologram.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.07a
• /
• pp.299-302
• /
• 2000

In this study, we have made the large holographic surface relief gratings on amorphous chalcogenide $As_{40}$$Ge_{10}$$Se_{15}$$S_{35}$ films by two beam interference using a He-Ne laser(632.8nm) light. The film thickness was about 0.6$\mu\textrm{m}$, we could magnify beam size by using beam expander. We made use $90^{\circ}$ holder which was made of reflection mirror and sample. Formed the surface relief structures were investigated using optical microscope. The diffraction efficiency was obtained by measuring +lst order intensity. In addition we investigated grating formation and diffraction efficiency as a function of polarization states which is linear or circular polarization. The results indicate that the grating was formed by linear polarized beam is better clear than that by circular polarized beam.

• Korean Journal of Optics and Photonics
• /
• v.10 no.4
• /
• pp.335-341
• /
• 1999

We fabricate acrylamide photopolymer as a holographic recording material and investigrate photobleaching characteristics. To explain the photobleaching kinetics of photopolymer we adopt two models of the Beer-Lambert law and optical transmittance based on rate equations obtained from a simplified energy-band model. The Beer-Lambert law is in good agreement with the experimental results in a first short-time region but not in long-time region. But the optical transmittance model based on rate equations explains the experimental results very well in both short-and long-time regions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.06a
• /
• pp.445-446
• /
• 2008

In this paper, we investigated the diffraction grating efficiency on Ag-doped amorphous chalcogenide Ag/AsSeS thin film for used to volume hologram. The film thickness was 2 um and diffraction efficiency was obtained from He-Ne (632.8nm) and DPSS(532nm) (P:P) polarized laser beam on Ag/AsSeS thin films. As a result, for the films, the maximum grating diffraction efficiency using He-Ne laser(632nm) is 0.15%[2000sec]. And then The recording speed of DPSS laser was about 40s which of batter than He-Ne lasers.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.06a
• /
• pp.181-182
• /
• 2007

In this paper, we investigated the diffraction grating efficiency on $Ge_{75}Se_{25}$ and Ag-doped amorphous chalcogenide $Ag/Ge_{75}Se_{25}$ thin film for used to volume hologram. The film thickness was 2 um and diffraction efficiency was obtained from He-Ne (632.8nm) and DPSS(532nm) (P:P) polarized laser beam on $Ge_{75}Se_{25}$ and Ag/$Ge_{75}Se_{25}$ thin films. As a result. for the films, the diffraction efficiency on Ag/$Ge_{75}Se_{25}$ double layer, was better than single $Ge_{75}Se_{25}$ thin films. The recording speed of DPSS laser is higher than that of He-Ne laser.

• Transactions of the Society of Information Storage Systems
• /
• v.2 no.4
• /
• pp.224-229
• /
• 2006

There has been studied flow to minimize the spot size to increase data capacity. Optical data storage devices are being developed near practical limits with wavelength and NA of 405nm and 0.85. There has been studied many types of next generation storage devices such as blu-ray multilayer system, probe based data storage and holographic data storage. Among these data storage devices, solid immersion lens(SIL) based near field recording (NFR) has been widely studied. In this system, SIL is the key component that focuses the laser beam with a very small size which enables ultra high data capacity. Therefore, optical performance evaluation system is required for SIL assembly. In this dissertation, a simple and accurate SIL assembly measurement method is proposed with wedge plate lateral shearing interferometer(LSI). Wedge plate LSI is cheaper than commercialized interferometer, robust to the vibration and the moving distance for phase shifting is large that is order of micrometer. We designed the thickness, wedge angle, material, surface quality and wavelength of wedge plate as 1mm, 0.02degree, fused silica, lamda/10(10-5) and 405nm, respectively. Also, we confirmed simulation and experimental results with quantitative analysis. This simple wedge plate LSI can be applied to different types of SIL such as solid immersion mirror(SIM), hemispherical, super-hemispherical and elliptical SIL.