| 摘要 |
PURPOSE:To prevent external disturbance from mixing in tracking error signals by forming pregrooves having specified phase depth in the beam incident side of a recording layer in which optical recording and reproducing is available and forming address grooves having specified phase depth in the area between the pregrooves. CONSTITUTION:Pregrooves PG having lambda/(8n) phase depth are formed in a concentric or spiral state in the beam incident side of a recording layer. lambda is the wavelength of beams for recording and reproducing and n is the refractive index of the light transmitting layer 2 through which the beams transmit. Further, in the area between pregrooves PG, address pits AP having lambda/(4n) phase depth are formed and information signals are recorded. With this recording medium, even if the level of tracking error signals is large and the modulation degree of the pregrooves PG fluctuates, little influence is added to the reproducing information signals, and thereby, address pits AP can be reproduced with good S/N and with high yield. Thus, information signals with good S/N and little dropout can be reproduced. |
