Patent ID: 6804189
Filing Date: 2004-10-12
Classification: G11B

Abstract:
In a near field optical recording medium having a header area in which at least an addressing signal for reproducing an address or a timing signal for providing datum for writing an address is recorded by means of a concave/convex pattern formed in a substrate wherein recording and/or reproducing is conducted by laser light using a flying optical head, the near field optical recording medium being characterized in that said concave/convex pattern is constituted by concave pits or convex bumps, each width of the pits or the bumps in a direction perpendicular to a track being smaller than the beam spot, wherein |Dpâˆ’Df|/(Dp+Df)&gE;0.05 where Dp is an intensity of returning light returned to the optical head at a position just above a pit or just above a bump and Df is an intensity of returning light returned to the optical head in a flat portion in which no pit or bump is formed, or said concave/convex pattern is constituted by concave portions and convex portions adjacent to each other wherein in a case that returning light returned to the optical head at a position just above a step portion, which is formed at the boundary of a concave portion and a convex portion which are adjacent to each other in a direction of track, is divided into a concave side and a convex side, |Dcâˆ’Dd|/(Dc+Dd)&gE;0.05 where Dc is an intensity of returning light at a concave side and Dd is an intensity of returning light at a convex side.