Differential phase voxel symbol determination

Abstract

A differential voxel symbol reader is alternatively configured to detect phase or polarization changes in a probe light beam caused by interactions with voxels distributed in an optical storage medium as light-scattering nanostructures. Rather than determine an absolute change in the state of the probe signal from an interaction with a voxel being read, a relative change is detected by comparing the probe light beam against an orthogonally-polarized reference light beam that propagates over an overlapping path with the probe light beam. The overlapping paths for the probe and reference light beams provide that each is subject to substantially the same impairments during propagation through the medium. The overlap largely cancels the effects of light scattering and impairments from the other voxels in the medium that cause shifts in phase and/or polarization which would otherwise scramble the signals to thereby reduce the accuracy and reliability of the reading process.