| 摘要 |
PROBLEM TO BE SOLVED: To provide a high-density recording medium that has high-density stable tracking characteristics and also has excellent pit signal reproduction characteristics. SOLUTION: This medium has concentric or spiral tracking grooves (annular groove) 18 provided at intervals of <=1.2μm and lands 22 as flat areas between the grooves on a substrate where recording or reproduction is performed by irradiation with laser light from the substrate side and meets the requirements that the depth Dg of the groves 18 is λ/7.2n to λ/3.9n and the width Wg of the grooves is 0.26P to 0.48P (hwere λ is the wavelength of the reproduction light, (n) is the refractive index of the substrate, and P is the pitch of the tracks). |
