Hermanus Johannes Borg

Crystallization behavior of phase change materials: comparison between nucleation- and growth-dominated crystallization

A comparative study of the crystallization behavior of nucleation- and growth-determined materials is presented. The influence of phase change layer thickness, additions and amorphous mark size on the crystallization rate is addressed. The long nucleation time of doped SbTe-type materials allows one to measure the nucleation probability separately, which may provide important information for initialization of optical storage disks.

Small form factor optical drive: miniaturized plastic high-NA objective and optical drive

Recent developments in portable consumer devices call for storage systems solutions using compact drive units and cheap storage media. A major advantage of conventional optical storage is the intrinsic low media cost and the ease of manufacturing of replicated ROM media. Third generation optical storage, using a blue laser and a high numerical aperture objective lens, is a perfect technology candidate for a small form factor optical (SFFO) drive. Using third generation optical storage technology 27 GBytes becomes available on a 12 cm optical disc. Using this data density for an SFFO drive, a storage capacity of over 1 Gbytes become feasible on a coin-sized disc. In this paper we report the realization of a SFFO drive, featuring 1 Gbytes on a 30 mm rewritable optical disc, with dimensions comparable to Compact Flash PCMCIA-like drives. Our main focus in this paper is on the miniaturization of the basic components of the SFFO drive, such as disc, objective and 2D-actuator. Related subjects in Philips R&D are miniature optics and low-dissipation/high-integration electronics.