Direct Overwrite Magneto-Optical Disks with Double Mask Type Magnetically Induced Super Resolution

Abstract

Light intensity modulation direct overwrite (LIMDOW) magneto-optical disks with a double mask type rear aperture detection (RAD) magnetically induced super resolution (MSR) function were investigated in comparison with LIMDOW disks with a front aperture detection (FAD) MSR function. Crosstalk, cross-write and carrier-to-noise ratio at various recording densities were evaluated and a track pitch of 0.6 µ m and mark length of 0.4 µ m which corresponds to an areal density of 3.6 Gbit/inch2 in (1, 7) run length limited pulse width modulation was a potential target for a LIMDOW-FAD disk provided that the crosstalk free condition of the L/G recording scheme was satisfied. On the other hand, LIMDOW-RAD disks showed very low crosstalk in a specified readout field range. The high resolution power of double mask RAD also proved to be effective in LIMDOW-RAD disks and it resulted in a wider power margin and higher carrier level than those in FAD-MSR. LIMDOW-RAD disks are more suitable for high density recording, not only in the track density, but also in the linear density.