System modeling and optimization of Fourier holographic memory

Abstract

A new fast-Fourier-transform-based model of a page-oriented holographic data-storage system is presented. The model accounts for essential system and storage material features (e.g. diffraction, noises, and saturation) and provides reliable results in the form of output images, histograms, or bit-error rates. The model is built on a modular basis and provides the possibility of working with different system versions, key components, and storage materials. Applications of the method are presented through examples of optimization of the data density, reference beam size at Gaussian beam illumination, and calculation of the storage medium's positioning tolerances in accordance with the results of test measurements.

Hybrid Ternary Modulation Applied to Multiplexing Holograms in Photopolymers for Data Page Storage

“…In addition, they were stored with a beam ratio of 100 and reconstructed on the CCD with a reading beam intensity of 0.03mW/cm 2 [24]. As the holograms are stored in the material, the dynamic range is consumed [21][22][23]25]; therefore, the exposure must be increased in order to store more holograms. Of course, when all the dynamic range is consumed, no more holograms will be formed in the material even if the exposure is increased.…”

“…In order to evaluate the image quality, its histogram was used to calculate the bit error rate (BER) [21][22][23] and determine the contrast between the pixels. BER values of each image were calculated to decide which parameters provide the best image quality (greater contrast and less noise).…”

Multiplexing holograms for data page storage using a LCD as hybrid ternary modulation

“…In addition, they were stored with a beam ratio of 100 and reconstructed on the CCD with a reading beam intensity of 0.03mW/cm 2 24 . As the holograms are stored in the material, the dynamic range is consumed [19][20][21][22] ; therefore, the exposure must be increased in order to store more holograms. Of course, when all the dynamic range is consumed, no more holograms will be formed in the material even if the exposure is increased.…”

“…In order to evaluate the image quality, its histogram was used to calculate the bit error rate (BER) [19][20][21] and determine the contrast between the pixels. BER values of each image were calculated to decide which parameters provide the best image quality (greater contrast and less noise).…”

Multiplexed holographic data page storage on a polyvinyl alcohol/acrylamide photopolymer memory

“…In order to evaluate the image quality, its histogram is used to calculate the bit error rate (BER) [26][27][28][29] and to determine the contrast between white and black pixels. BER values of each image are calculated to decide what parameters provide the best image quality (greater contrast and less noise).…”