We introduce an image upscaling method that reduces bit errors caused by Nyquist apertures. Nyquist apertures used for higher storage densities generate optical aberrations and degrade the quality of the image that is recorded on the medium. Here, to correct the bit errors caused by the Nyquist aperture, an image upscaling method is used to restore the degraded image in the enhanced spatial frequency domain using its point spread function (PSF) as a restoration filter. The proposed method reduces the bit error rate (BER) significantly and hence allows higher storage densities.

In a holographic data storage device, data are stored and retrieved as two-dimensional images. These images can be distorted in various ways. Generally, sync marks are used to acquire exact pixel values in a distorted image. However, this inevitably results in some loss of data density. In this research, a virtual detector that follows the rows of an image like a compact disk (CD) track is used to acquire the data pixels in a distorted image without sync marks. The proposed method can compensate for image distortion without any loss of data density. The feasibility of the new technique is demonstrated by simulation. The procedure is also evaluated on the basis of signal-to-noise ratio and bit error ratio.

We report on the effective optical response of a uniaxial crystal of metal-dielectric-metal nanosandwiches, which exhibits artificial optical magnetism, through full-electrodynamic simulations by the extended layer-multiple-scattering method. Using a recently developed all-angle homogenization procedure, which is based on rigorous results of complex-band-structure and reflection-coefficient calculations, we deduce local effective permittivity and permeability tensors, appropriate for this crystal. We show that the effective-medium description breaks down as we approach the region of the magnetic resonance. In a frequency region close to the resonance the retrieved effective parameters, though doubtful, indicate that the crystal under consideration may exhibit negative refraction. This behaviour is demonstrated by rigorous calculation of the isofrequency surfaces of the actual crystal and determination of the relevant group velocities.

In holographic data storage, tilt is one of the critical disturbances. There are two types of tilt: tangential and radial. In real systems, tangential and radial tilt occur simultaneously. Thus, it is difficult to measure and compensate for tilt. In this study, using a quadratic window, which compares the intensity of a certain area, a tilt error signal was generated and compensated for with the proposed algorithm. The compensated image obtained satisfied a 0.3 dB tolerance.

In holographic data storage system, misalignment of optical components causes fluctuation of path and angle of laser. These phenomena generate data distortion like rotation, barrel, pincushion and mustache distortion, because holographic data storage system has very sensitive tolerance with incident angle of reference beam. Because it is difficult to align perfectly, data distortion occurs inevitably by misalignment. It is important to acquire accurate data page from holographic data storage system without distortion. In this paper, we propose intelligence compensation algorithm for data restoration in holographic data storage system. We used fuzzy system and sub-clustering algorithm to generate fuzzy rules for this compensation algorithm. This proposed algorithm acquires the value how much the data image has barrel distortion. With acquired data form this algorithm, data distortion can be compensated. Barrel image is used for this simulation and it shows good performance.