• Proceedings of the Optical Society of Korea Conference
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• 2001.08a
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• pp.224-225
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• 2001

• Proceedings of the Optical Society of Korea Conference
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• 1996.09a
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• pp.6-6
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• 1996

• Polymer Science and Technology
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• v.7 no.6
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• pp.646-654
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• 1996

• Korean Journal of Optics and Photonics
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• v.7 no.4
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• pp.434-439
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• 1996

To investigate influence of the incident beams which have the truncated Gaussian amplitude and of the shapes of bump on read-out signal is an optical disc, and the point spread function on bump, the scalar diffraction theory is used in this paper. We consider the truncated Gaussian amplitudes which are $\sigma$=0, 0.5, 1.5, and 2.5, the height of bump which is given by $n{\Delta}_0={\lambda}/4$, and the phase height of bump which is then given by ${\Phi}_0={\pi}$. We also consider the shapes of the bump which are a rectangular shape, a frustoconical shape, and a conical shape. It is shown that as the truncation of incident beam reduces the radius of central spot on bump decreases, the maximum value of read-out signal increases, and that the size of bump decreases. From these results, we get better read-out signal and the reduced cross-talk in optical disc when the truncation of incident beam reduces. Therefore a laser beam having less truncated Gaussian amplitude may useful for an actual optical disc.

• Journal of Korea Multimedia Society
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• v.5 no.2
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• pp.215-221
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• 2002

In high speed optical disc devices, the vibration caused by unbalanced displacement leads the focus and tracking servo systems to be unstable, and increases the data search time. In this paper, we propose a new scheme to solve the unbalanced displacement problem. The proposed method detects the unbalanced rate by differential amplifying optical power received at photo diode and converts it into an electrical signal. controlling the speed of spindle motor, according to the detected unbalanced rate, makes it possible to improve the performance of tracking and data searching tasks. Also, we analyze the dynamic characteristics of focus and tracking servo systems in high speed mode and provide the firmware and hardware architecture that the proposed method can be installed as an add-on- module in the existing system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.398.1-398
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• 2002

A new type actuator has been designed and investigated to overcome thermal problems in slim optical disc drives adopted in mobile storage devices. As the size of optical disc drives decreases, it is more difficult to remove the heat inside a drive and the temperature of an actuator increases. As a result, the second resonance of an actuator moves down to a lower frequency band and the performance of optical parts also deteriorates. (omitted)

• Transactions of the Society of Information Storage Systems
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• v.1 no.1
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• pp.78-83
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• 2005

The Blu-ray disc as a next generation high density optical medium uses an objective lens of high numerical aperture(NA 0.85) and blue laser in order to increase the recording density. The double layer is also useful for doubling the density. The spherical aberration of Blu-ray disc is very sensitive to the thickness of the disk because of high numerical aperture. This paper suggests a method to compensate the spherical aberration caused by the change of disk thickness, by using the Liquid Crystal lens instead of the Liquid Crystal panel. It was possible to develop both the LC panel generating the optical phase difference and LC lens changing the optical power. In this paper, we analyzed the aberration performance and a position sensitivity of the two type LC elements when the samples deviate from the optical axis of the objective lens. The results of applying this analysis show that the LC lenses rather than the LC panels have a significant assembling tolerance. The theoretical characteristics of the two elements are calculated and compared with the measurement data.

• Transactions of the Society of Information Storage Systems
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• v.1 no.1
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• pp.29-33
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• 2005

We have developed an optical pickup head for blu-ray disc. We have adopted a liquid crystal panel to compensate thickness difference of cover layer. By disposing DVD/CD compatible objective inside the BD objective in disc radial direction, we could realize a backward compatibility. Furthermore we have inserted a polarization diffractive optical element to reduce the influence from the other layer in BD dual layer.

• Proceedings of the KAIS Fall Conference
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• 2004.11a
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• pp.77-79
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• 2004

Optical Disc(DVD) 생산 공정에 있어서 생산 효율성을 극대화하는데 많은 어려움이 존재한다. 최적공정 변수를 예측하기가 어렵기 때문에, 사출 성형 공정 시 발생하는 여러 가지 불량에 대한 체계적인 기술이 정립이 되지 않고 있는 실정이다. 본 연구는 Optical Disc 생산 시 요구되는 일반적인 사항들을 고찰하고, 불량품을 최소화하기 위한 여러 가지 사례연구 및 분석을 통하여 얻어진 지식을 바탕으로 문제 해결을 위한 지능형 시스템을 개발하였다.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1580-1580
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• 2007

광디스크를 재생 및 기록 가능한 기기는 그동안 IT에 용이한 컴퓨터 중심의 ODD(Optical Disc Drive)를 기반으로 급속히 발전해 오고 있었으나, 홈 엔터테인먼트의 발전과 이에 대한 관심의 증폭으로 AV용의 레코더가 2000년대에 등장하게 되었다. AV용 DVD 레코더의 경우 PC용 ODD에 비해 소음 및 세트 내부 온도 등 환경의 영향을 많이 받고, 여러 규격들을 만족해야 하기 때문에 구현에 많은 어려움과 제약이 따른다. 그리고 DVD 레코더는 방송 등을 스트림 기록해야 하므로 기록 신뢰성에 더욱 엄격함을 요구한다. 이에 기록 품질에 관련된 중요 Factor들이 존재하게 된다.