It is the higher stratum of society recording layer which is made

摘要

This invention, the entrance place (EF) under, higher stratum of society record layer (L₀) the higher stratum of society record stack which it possesses (ST₀) with, to relate to the optical memory medium which lower stratum record stack (ST₁) with it possesses at least, lower stratum record stack, wave length () possessing, to pass by the entrance place and record or be done to read out entering the said optical memory medium, the focus be brought together in regard to lower stratum record stack, the emission beam which transmits within higher stratum of society record stacking by (4), as for record of higher stratum of society record layer, with the record territory and the non record territory of the said 1st record layerIt brings the deviation of optical thickness, as for deviation, is inside the range of 0.03 lambdas or 0.125 lambdas.