Advanced Radial Position Control of a Recording Beam for Super Multilayer Disc with Separated Guide Layer

Abstract

We have developed an advanced radial position control system for a super multilayer disc with a separated guide layer to realize stable recording on the plane recording layers located far from the guide layer. The developed system consists of an advanced sled servo system and a specially designed optics based on the advanced push–pull method. Recorded signals on all recording layers were evaluated by using integrated-maximum likelihood sequence error estimation (i-MLSE) as the evaluation indicator. As a result, we confirmed sufficient recorded signal qualities and feasibility at the quad-speed continuous recording with a constant track pitch of 0.32 µm, the same as that of Blu-ray disc (BD). We believe that our proposed concept is the most practical solution for the next-generation optical disc system and our control system is essential to realize stable multilayer recording with a constant track pitch.

A high transmittance optical recording material with long-term reliability for super-multilayer discs

“…Optical discs are extensively used as long-term storage media for data archival because they offer high data reliability and low operating costs. [1][2][3][4][5] As a means of increasing the data storage capacity, several technologies have been reported, such as holographic technology, 6,7) near-field technology, 8,9) multilayer technology, [10][11][12][13][14][15][16] and others. [17][18][19][20][21][22][23][24] Among these, multilayer recording technology is a promising approach because it can utilize most technologies of the Blu-ray Disc™ system that is already in use as a commercial technology.…”

Decoupled direct tracking control system based on use of a virtual track for multilayer disk with a separate guide layer

“…One solution to this problem is the adjacent track servo system with linear positioning method developed by Urakawa et al [19][20][21][22][23] However, the need to form a particular pit structure on the servo layer to maintain a continuous linear position on the groove-less disk could increase the disk fabrication cost. An alternative is the advanced radial position control system developed by Tanaka et al, [24][25][26][27][28] but its use of feed-forward control it is not sufficiently robust against shock and vibration. The advanced linking techniques reported by Usui et al 29) reduce disk capacity because a specific linking buffer region needs to be placed between previously recorded data marks and the currently recorded data marks.…”

Low-cost ultrahigh areal density optical disc system towards 400 Gbyte/disc

“…Several high-density optical disc techniques have been proposed to reduce the media cost, including volume holographic memory, [3][4][5][6] a super-resolution head, [7][8][9][10][11][12] 3-beam optical heads with a crosstalk-cancelling circuit, 13) multilayered technology for optical discs, [14][15][16][17][18] and a two-photon recording technology. [19][20][21][22] However, these approaches require additional components, such as new optical heads, or disc fabrication processes.…”