Hologram synthesis for photorealistic reconstruction

Computation of diffraction patterns, and thus holograms, of scenes with photorealistic properties is a highly complicated and demanding process. An algorithm, based primarily on computer graphics methods, for computing full-parallax diffraction patterns of complicated surfaces with realistic texture and reflectivity properties is proposed and tested. The algorithm is implemented on single-CPU, multiple-CPU and GPU platforms. An alternative algorithm, which implements reduced occlusion diffraction patterns for much faster but somewhat lower quality results, is also developed and tested. The algorithms allow GPU-aided calculations and easy parallelization. Both numerical and optical reconstructions are conducted. The results indicate that the presented algorithms compute diffraction patterns that provide successful photorealistic reconstructions; the computation times are acceptable especially on the GPU implementations. © 2008 Optical Society of America

Densities and character of dislocations and size-distribution of subgrains in deformed metals by X-ray diffraction profile analysis

The density and the character of dislocations and the size-distribution of grains or subgrains were determined by a new procedure of X-ray diffraction (XRD) profile analysis in copper specimens deformed by equal channel angular pressing (ECA) or cold rolling. The anisotropic strain broadening of diffraction profiles was accounted for by dislocation contrast factors. The screw or edge character of dislocations was determined by analyzing the dislocation contrast factors. Three size parameters and the dislocation density were obtained by the modified Williamson-Hall and Warren-Averbach procedures. Assuming that the grain-size distribution is log-normal, the median, in, and the variance, sigma, of the size distribution of grains or subgrains were obtained from these three size parameters