Myong-do Ro

Synthesis and Characteristics of Protective Coating on Thin Cover Layer for High Density-Digital Versatile Disc

This study relates to the optical disc used in the high-density digital versatile disc (HD-DVD) system that uses a high numerical aperture of 0.85 at 405 nm wavelength. The disc has a protective layer formed on the light-incident surface for protection against damage and dust. The synthesis of the UV-curable resinous material, as means of making a protective layer within sufficient margins of thickness variation and optical and mechanical properties, was investigated. In addition, the dynamic characteristics, including reflectivity, fluctuation of the RF signal and noise level, were also investigated.

Random Signal Characteristics of Super Resolution Near Field Structure Read-Only Memory Disc

We report the random pattern signal characteristics of the super resolution near field structure (Super-RENS) disk in a red laser optical system. (Laser wavelength 659 nm, numerical aperture 0.6) We improved the carrier to noise ratio (CNR) characteristics and the low frequency noise by optimizing the layer design and the pit structure, which results in 53 dB CNR at 173 nm pit length. It is equivalent to 50 GB capacity if it is converted by Blu-ray Disc (BD) specification according to the ratio of beam size. We also improved the readout power margin and the stability greatly by introducing the thermal control layer. The eye pattern under phase locked loop (PLL) state could be obtained through equalization adjustment (EQ). Through above improvements, we obtain the bER of 4.6×10-4 at 50 GB level by using partial response maximum likelihood (PRML) method.

Phase Change Super Resolution near Field Structure ROM

We confirmed a super resolution phenomenon and a typical super resolution near field structure threshold phenomenon in a read only memory (ROM)-type sample disk. We found that this super resolution phenomenon originates from a phase-change layer and is closely related to the thermal properties of the super resolution layer. We also improved the readout stability using a co-sputtered layer with phase change (GST) and dielectric materials (ZnS-SiO2).

Optical Disc for Small Form Factor Optical Drive

We investigated the signal characteristics of a 46 mm small optical disk in a blue laser system [laser wavelength, 405 nm; numerical aperture (NA), 0.85]. To determine the physical dimensions of the rim area of the disk, we considered some factors affecting this rim area. We confirmed the transcription of the substrate, and the thickness of the cover layer of the disc. Also, by spin coating and selecting the optimum viscosity of the resin used for the 0.1-mm-thick cover layer, it was possible to reduce rim area from 1.5 mm to 1.0 mm. Also, we confirmed that the thickness of the substrate for sufficient mobility should be thicker than 0.5 mm.

Enhancement of shear-force sensitivity using asymmetric response of tuning forks for near-field scanning optical microscopy

Resonance characteristics of a tuning fork are investigated to enhance the shear-force detection sensitivity for near-field scanning optical microscopy. In particular, we show that the asymmetric frequency response of a tuning fork can be utilized to increase quality factors and suppress the background feedback signal. The pinning down effect on one side of the main peak can readily elevate vertical sensitivity and stability. A simplified model based on a coupled harmonic oscillator is presented to describe the asymmetric resonance behavior of the tuning fork. We also show improved topographic images of a blue-ray disc and optical images of a chromium pattern on the quartz using the asymmetric resonance.

Experimental Results of 3-piece 0.4 mm Molded Substrate

To achieve the same margin as that of the digital versatile disk (DVD), using a 0.4 mm substrate has been molded for a high-density optical disk for double-sided dual layer disk. In this paper, the characteristics of a read-only and rewritable high-density optical disk of 0.4 mm plastic substrate is reported using a new resin material for injection molding, to improve both the birefringence and the mechanical characteristics.

Synthesis and characteristics of protective coating on thin cover layer for HD-DVD

Synthesis and Characteristics of Protective Coating on Thin Cover Layer for HD-DVD Doboon Chang*, Inoh Hwang, Myongdn Ro, Duseop Yoon, Insik Park and Dongho Shin Storage Solution Team, Digital Media R&D Center, Samsung Electronics, Suwon, Kpnggi 442-742, Korea *Email: dohoon@amwng.com, Phone: 82-31-200-4864. Fax: 82-31-200-3160

Optical Storage System for 0.4 mm Substrate Media Using 405 nm Laser Diode and Numerical Aperture 0.60/0.65 Objective Lens

The most important application of the blue-laser optical storage system is the recording high-definition digital broadcasting. For this application, the next-generation blue laser optical storage system requires a data capacity of at least 2 h of a digital broadcasting data stream with a data transfer rate of 23.5 megabits per second (Mbps). In addition to the capacity goal, system compatibility with the conventional digital versatile disc (DVD) system as well as the compact disc (CD) system is important. In order to satisfy the requirements of blue-laser optical storage, a system for media with a substrates thickness of 0.4 mm was proposed, and improved molding technology, crosstalk cancellation technology, dynamic tilt compensation technology and quadrature phase shift keying (QPSK) modulated wobble addressing method were developed for the system. We confirm the feasibility of the proposed system for media with a 0.4 mm substrate using a 405 nm blue laser diode and objective lens with a numerical aperture (NA) of 0.6 (0.65 for rewritable system).

EFFECT OF SPUTTERING CONDITION ON DYNAMIC CHARACTERISTICS AND MICROSTRUCTURES OF MAGNETO-OPTICAL 5.25 IN. SIN/TBFECO/SIN/AL DISKS FOR 532 NM RECORDING MEDIA

A systematic study of the effect of sputtering conditions, for each layer of the magneto‐optical SiN 500 A/TbFeCo 200 A/SiN 200 A/Al 600 A disks, such as power and Ar gas flow rate on the noise levels (NL) and carrier‐to‐noise ratio (CNR) was performed for the 532 nm high density storage media in this work. The NL dropped to its minimum value of −71.3 dB as the sputtering power for the first SiN increased from 0.5 to 1.5 kW. With a further increase in sputtering power to 2.5 kW, it sharply increased to −64.5 dB. This was ascribed to the smooth and dense surface of the first layer at 1.5 kW, as was observed in the atomic forces microscopy images. The spherical, isotropic, fine grains with a diameter of about 0.2–0.7 μm at 1.5 kW were found, while the longitudinal, directional granular features with a length of 2.5 μm were seen at 2.5 kW. The highest CNR of 46.3 dB was observed at 0.6 kW with a constant sputtering Ar gas flow rate of 25 sccm for the magneto‐optical layer. The sputtering conditions for other...