MAGNETO-OPTICAL RECORDING MEDIUM

摘要

PROBLEM TO BE SOLVED: To suppress signal imbalance due to changes in the double refraction in a system having a smaller producing signal amplitude. SOLUTION: In the magneto-optical recording medium, data is read out by a Kerr effect. The spacial frequency of the shortest recording signal line in the magneto-optical recording medium is >=1.1×NA/λ(line/m). The photoelastic coefft. of the substrate is specified to <=50×10-13 cm2/dyne. The perpendicular double refraction of the substrate is <=250×10-6, and water absorptivity of the substrate is <=0.2 wt.% and the coefft. of thermal expansion is specified to <=6.5×105 cm/cm. deg.C.