Multi-level read-only recording using signal waveform modulation.

A novel multi-level read-only recording using signal waveform modulation (SWM) is presented. The SWM is realized by inserting a sub-pit/sub-land to the original land/pit. Numerical simulation provides a helpful tool for the write strategy optimization.

Improved mastering material for multilevel blue laser disc.

In order to get a small-sized pit, the reaction threshold of a photoresist is enhanced by increasing the prebake temperature and time. With the improved photoresist, a pit size corresponding to or even smaller than the minimum pit on a blue laser disc can be obtained on an industrial DVD product line. The improved photoresist may serve as the master material of future multilevel blue laser discs, which might provide a potential solution for the fabrication of multilevel blue laser discs.

Modeling and realization of a multilevel read-only disk.

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.