Magneto-optical Disks Using PC Substrates

Magneto-optical disk is one of the most promising candidates for erasable optical media.1)2) Considering mass production, optical disks using resin substrates have the advantage of simple pre-groove formation. Among several resins applicable for use in optical disks substrates, Polycarbonate (PC) has superior injection molding characteristics, good humidity resistance and excellent thermal resistance. However, the noise arising from birefringence is the most significant drawback. On the other hand, it is necessary to use excellent protective films since the magneto-optical films are rapidly oxidized in the air. For this reason, various kinds of protective films have been studied for magneto-optical disks.3)4)5) This paper discusses the characteristics of magneto-optical disks using the noise reduced PC substrates and excellent protective films.