Alexander Padiy

Near-field read-out of a 50-GB first-surface disc with NA=1.9 and a proposal for a cover-layer-incident, dual-layer near-field system

We present read-out results of a 50 GB disk with a blue laser and a NA=1.9 Solid Immersion Lens in a conventional focus and tracking actuator. Furthermore, we show a light path and a disk design that enable cover-layer incident near field recording on dual-layer disks with a capacity of 300 GB on a double-sided disk.

Signal processing for 35GB on a single-layer Blu-ray disc

We report on the technical progress in increasing the recording density of optical storage systems by means of improved read-channel signal processing and write-channel optimisation. The recording density increase is realized by employing PRML (Viterbi) bit detection in combination with improved timing recovery and adaptive equalisation algorithms, and by using a signal quality characterisation scheme which enables a proper control of the write process in the considered range of storage densities. The Blu-ray Disc (BD) optical disc system employing blue-violet laser with the wavelength of 405nm, objective lens with numerical aperture of 0.85 and disc cover layer thickness of 0.1mm is used as an experimental platform in our present study. Multi-track experimental results for both single-layer read-only (BD-ROM) and single-layer rewritable (BD-RE) media are presented to show the feasibility of the increased-density BD.

On a two‐level Newton‐type procedure applied for solving non‐linear elasticity problems

The present work is devoted to the damped Newton method applied for solving a class of non-linear elasticity problems. Following the approach suggested in earlier related publications, we consider a two-level procedure which involves (i) solving the non-linear problem on a coarse mesh, (ii) interpolating the coarse-mesh solution to the fine mesh, (iii) performing non-linear iterations on the fine mesh. Numerical experiments suggest that in the case when one is interested in the minimization of the L2-norm of the error rather than in the minimization of the residual norm the coarse-mesh solution gives sufficiently accurate approximation to the displacement field on the fine mesh, and only a few (or even just one) of the costly non-linear iterations on the fine mesh are needed to achieve an acceptable accuracy of the solution (the accuracy which is of the same order as the accuracy of the Galerkin solution on the fine mesh). Copyright