Recently, because of the increase of computer information handled by computers, higher density storage devices are expected. The magnetically super resolution (MSR) is one of the high density versions for improving the conventional magneto-optical (MO) disk. The rear aperture detection (RAD) is proposed to increase the capacity by ten times or more. The center aperture detection (CAD) is also proposed for advanced storage magneto-optical (ASMO) disks. Moreover, narrower focused beam can be realized by using blue laser light, so that the track pitch can be much more reduced. Therefore, narrower track pitches give rise to the increase of the crosstalk between adjacent tracks. In the present paper, we try to apply the three-dimensional flnite-difierence time-domain (FDTD) method to the analysis of the light-beam scattering and the characteristic of detected signal from a rear aperture detection-magnetic super resolution (RAD-MSR) disk model and examine the in∞uences of the groove depth on the crosstalk characteristics.