초록

hold for preventing distortion of the groove caused by repeated overwriting operation to improve reliability of the optical disc.

대표청구항 ▼

[ What is claimed is:] [1.] An optical disk, comprising:a substrate having a groove configured to guide a light beam and having a land, said groove having a wobble in accordance with a modulation signal and having a depth between 25 nm and 200 nm;a lower protective layer overlying said substrate and

[ What is claimed is:] [1.] An optical disk, comprising:a substrate having a groove configured to guide a light beam and having a land, said groove having a wobble in accordance with a modulation signal and having a depth between 25 nm and 200 nm;a lower protective layer overlying said substrate and having a thickness between 10 nm and 200 nm;a rewritable recording layer on said lower protective layer and comprising a phase-change material; andan upper protective layer on said rewritable recording layer and having a thickness between 10 nm and 60 nm,wherein said wobble is configured to provide a wobble signal having a carrier level to noise ratio not less than 25 dB, and wherein:EQU 0.25.ltoreq.GW/R.sub.0 .ltoreq.0.45, or 0.65.ltoreq.GW/R.sub.0 andEQU 0.03.ltoreq.a.sub.w /GW.ltoreq.0.08, re a.sub.w, R.sub.0 and GW represent a wobble amplitude, a beam diameter of the light beam measured across said groove and a groove width, respectively.