Book excerpt: This volume contains the proceedings of the 8th Epioptics Workshop, held at the Ettore Majorana Foundation and Centre for Scientific Culture, Erice, Sicily. The book assesses the capabilities of state-of-the-art optical techniques in elucidating the fundamental electronic and structural properties of semiconductor and metal surfaces, interfaces, thin layers, and layer structures. The contributions consider the usefulness of these techniques for optimization of high quality multilayer samples through feedback control during materials growth and processing. Particular emphasis is placed on the theory of non-linear optics and on dynamical processes through the use of pump-probe techniques together with the search for new optical sources. Some new applications of Scanning Near-field Optical Microscopy to material science and biological samples, dried and in vivo, with the use of different laser sources are also included.