근접장을 이용하는 기록 시스템의 문제점 및 개선 방안

Abstract

최근 고밀도의 기록매체가 요구됨에 따라 근접장을 이용하여 광디스크와 같은 기록매체에 데이터를 기록하는 근접장 기록 시스템(Near-field recording system)이 개발되고 있다. 상기의 근접장 기술은 기록 용량을 획기적으로 개선할 수 있는 잠재가치를 가지고 있으나, 종래의 광디스크를 이용한 기록방식과 달라 시스템을 안정화시키기 위한 방안이 요구된다. 특히, 근접장을 이용하기 위한 기술의 특징에 따라 렌즈와 광디스크의 간격을 제어하기 위한 방안이나 근접장에 이용되는 렌즈의 마련이 최우선과제이다. 또한, 다층 기록층을 가지는 광디스크를 이용하여 용량의 극대화를 꾀하기 위하여, 초점의 위치를 조절할 수 있는 방안도 요구된다. 본 논문에서는 상기와 같은 근접장 기록 시스템의 문제점과 그에 대한 해결방안을 모색해본다. 근접장을 이용하는 기술은 데이터를 기록할 수 있는 용량을 획기적으로 증대시킬 수 있으므로 잠재적 가지가 뛰어난 기술이다. 그러나 종래의 기록 방식과 상당한 차이가 있으므로 안정적으로 근접장을 이용할 수 있는 방안이 요구된다.; With the recent increase in demand for a high-density recording medium, the Near-Field Recording System for recording data using a near-field on a recording medium including an optical disc has been developed. Even though the near-field recording technology is potentially very valuable in dramatically improving recording capacity, a recording scheme is different from that using a conventional optical disc so that the method for stabilizing the system has been required. Especially, the preparation of the method for controlling the distance between a lens and an optical disc or the lens used in the near-field, all depending on a characteristic of the technology for utilizing the near-field, is of the highest priority. Further, in order to maximize the capacity by using the optical disc having multiple recording layers, the method for controlling a focus position is also required. In this paper, the problem in the near-field recording system and an improvement thereof will be discussed. The technology using the near-field is potentially very valuable because it can dramatically increase the capacity for recording data. However, it is greatly different from the conventional recording scheme so that the method for using the near field in a stable manner is required. In particular, the control of the distance between the SIL and the optical disc being the characteristic of the near field recording system, the manufacture of the lens unit including the SIL and the object lens, and the development of the method for using the multiple recording layers may be matters in hand. In this respect, the improvements are suggested as follows. First, the distance between the SIL and the optical disc is controlled by using the strength of the reflected light proportional to the distance between the SIL and the optical disc for maintaining the near field. Second, the SIL is manufactured and then the lens unit is manufactured by using the OL compensating the spherical aberration of the SIL. Third, the beam expander formed with the movable lens in addition to the OL is included in the optical system in order to be employed in the optical disc having multiple recording layers.