A new form of read out for high density read-only memory is presented whereby a data density of400 bits/&mgr;m2,corresponding to256 Gbits/in.2,can be accessed at data rates in the tens of MHz range. The technique is based on detecting the modulation in light scattering from a sharp scattering object due to the dipole-dipole coupling between the probe and surface being scanned using a sensitive homodyne interferometer. Theoretical considerations indicate that data densities in the100 Tbits/in.2range could be accessed at data rates of 100 MHz using this technology. ©1997 American Institute of Physics.