A Gray Level Weighting Method to Reduce Optical Aberration Effect in Holographic Data Storage System

An alignment method for holographic data storage system (HDSS) is proposed in this paper. Due to several types of noises encountered in the HDSS, the signal-to-noise ratio (SNR) is degraded. Errors can be corrected using a channel code for some sorts of noise, while it may require a high quality optical system to reduce the error probability for the other types of noise. A checkerboard pattern is proposed using intensity weighting to find the fiducial points, which could work in a lower SNR system and thus reduce the error likelihood effectively. Reed-solomon (RS) code and oversampling are both made available in the HDSS. As a consequence, the aberration effects are eliminated using the fiducial points, leading to a low SNR system clear of errors after performing decoding. The lowest SNR system is out of error-free recovery condition, so that all the alignment methods proposed in this paper could not reduce the aberration effects to restore the images into the original data.