Analysis of inter-symbol-interference caused by shift misalignment of two objective lenses in high-NA micro holographic storage

A high-numerical-aperture (NA) optical system with narrower recording distance in transverse direction is required to increase the areal-density in micro holographic storage. When the first data is recorded by shift misalignment of the two objective lenses (OLs) in transverse direction, the second data can cause inter-symbol-interference (ISI) by pre-recorded first data. A tolerance analysis in transverse direction is required because shift misalignment of the two OLs causes ISI and reduces the total-density. This research analyzes the effects of ISI using a 0.85 NA and 320 nm recording distance between two microgratings in adjacent region. We define the recording tolerance of a single micrograting and the calculate total-density based on blu-ray disc specifications while considering the shift errors. Finally, we define the recording tolerance of successively recorded microgratings in adjacent region and propose recording distance for avoiding ISI.