Modeling and realization of a multilevel read-only disk

Abstract

A model for exposing and developing photoresist using the reaction mechanism of physics and the chemistry of resist is built, and the micropatterns of recording marks on a stamper are calculated. Compared with our experimental results, the deviation of pit width in simulation is less than 8%. When the width of recording marks is varied by modulating laser power during exposure, a multilevel (ML) read-only disk can be achieved as a result of the corresponding readout signal. Experimental results show that an 8-level read-only optical disk can be realized. The model of mastering serves well for the development of novel ML disks in which the integration of conventional run-length deviations technologies can greatly increase recording density.

Restrictions on pit length in multi-level read-only disk

“…In latest multi-level read-only recording system, a signal waveform modulation (SWM) ML recording in which a subland/pit is inserted to the original pit/land, leading to variations in waveform of readout signal is realized by using the waveform to differentiate the levels, and is implemented on the DVD platform [8] . While DK (1,9) modulation is used and the minimum pit length is 320nm, write strategy optimization work will be difficult and complex for the special case that four shortest pits stay next to each other surrounded by two longest pits, as the signal waveform of long length pit with high level is similar to this special case. Till now as long length (like pit 9T or 10T) has enough level types to choose, then it is possible to optionally choose level type to avoid similar waveform generated by minimum pit surrounded by longest pits and high level of long length pit.…”

“…Multilevel (ML) recording technology increases the capacity of optical disks without changing the optical and mechanical units [1] . The multi-level read-only disk technology has been researched by Optical Memory National Engineering Research Center (OMNERC) for nearly ten years since 1999.…”

PRML Detection of Multi-Level DVD Channels with Run-Length-Limited Modulation

“…For example, the DR of 4-ary RLL (2, 12) code is 2.4 bits/T min , however, the DR of the RLL (1, 7) code is only 1.33 bits/T min . Therefore, the recording density can be directly increased by 80% if 4-ary RLL (2,12) code is implemented instead of (1, 7) code.…”

“…However, there are few publications related to this topic. Recently, experiments of ML-RLL modulation on DVD-ROM discs are carried out in Tsinghua University, and a multi-level DVD-ROM driver with conventional DVD optical pickup is also developed [12], [13], [14]. In this paper, we introduce the experimental results of four-level RLL modulation on DVD-ROM discs, and discuss the simulation performances of partial-response maximum-likelihood (PRML) detection for this optical recording channel.…”

A new rate 8/12 run-length limited (2, 9) code for four-level read-only optical disc

“…2 Since read only (pre-recorded) optical discs are very popular in consumer electronics market, it is important to investigate the feasibility of ML-RLL modulation on read-only optical discs. 3 However, conventional M -ary RLL codes can result in consecutive multi-level pits on the optical disc, which increases the difficulty of multilevel optical disc replication. More recently, a new class of M -ary RLL codes is proposed to obtain multi-level spaced pits/lands (SPL).…”