A "below-diffraction-limited" aperture within the readout spot for high-density recording can be achieved on erasable thermal phase change super resolution (EPSR) disks. Compared to the large aperture wall formed by the DC detection method, the small aperture wall formed by pulse readout can not only increase the signal amplitude, but also suppress readout noise when detecting the EPSR disks. The small aperture wall width generated by pulse readout in the EPSR disk resulted in an 8 dB higher in carrier-to-noise (CNR) than that by DC readout in the conventional single-recording-layer phase change disk when reading the below-diffraction-limited marks of 0.4 µm.