Enhancement of Repositioning Tolerance by Directionally Controlled Shift Selectivity of Speckle-Multiplexed Holograms

A method for directional control of shift selectivities of speckle-multiplexed holograms with a diffuser whose diffusion angle varies with the diffusion direction is proposed to enhance the tolerance of recorded holograms to repositioning error in holographic storage. The directional dependence and controllability of shift selectivities of holograms are experimentally investigated using various diffusers. By retrieving 50 speckle-multiplexed holograms with deliberate deviations from the original recording position and by measuring bit error rate, it is also confirmed that the tolerance to repositioning error is improved.