| 摘要 |
<p>An optical disc (2) has an information recording surface on which information is recorded, the information being read out and reproduced by irradiating a laser light having predetermined wavelength ( beta ) under the condition of a predetermined numerical aperture (NA) and receiving a diffracted and reflected laser light. The disc includes a track (T) spirally formed on the information recording surface and extending in a disc peripheral direction, a plurality of information units (U) formed on the track each having predetermined unit lengths (L) in both of the disc peripheral direction and a disc radial direction. The information is recorded in the form of an information pit (1) in each of the information units. The information pits have a plurality of pit patterns each of which is formed as combination of pit fragments (PP) having the substantially same shape. Each of the pit fragment has a predetermined optical pit height (h) and a plane figure which is symmetrical with respect to one of a first line (v') or a second line (U'), the first line passing through center points of each of the information units and extending in the disc peripheral direction, the second line passing through the center point and extending in the disc radial direction. <IMAGE></p> |
