| 摘要 |
PURPOSE: To facilitate the accurate tracking servo of an optical disc on which a reflective layer and/or a recording layer are/is formed by a method wherein the servo pits of the optical disc have pit lengths with which the space frequency sensitivity in a reproducing optical system is not less than 0.4. CONSTITUTION: Tracks in which data pits corresponding to information signals are arranged are concentrically or spirally provided on the surface of a transparent substrate 1 on the side where a recording part is formed. The tracks are divided into a plurality of data areas and pairs of servo pits 8a and 8b are formed between the respective data areas. The servo pits 8a and 8b are arranged on both the sides of the center line C of the track alternately in a zigzag form and formed at positions a quarter of the track width apart from the center line C so as to have protruding or recessed shapes. The intensities of signals read from the two types of the servo pits 8a and 8b arranged in a wobbling state on the optical disc are compared with each other to perform the tracking servo of a laser spot. The pit lengths of the servo pits 8a and 8b are so selected as to have the space frequency sensitivity in a reproducing optical system not less than 0.4. |
