SPIE Proceedings [SPIE ICONO '98: Laser Spectroscopy and Optical Diagnostics--Novel Trends and Applications in Laser Chemistry, Biophysics, and Biomedicine - Moscow, Russia (Monday 29 June 1998)] ICONO '98: Fundamental Aspects of Laser-Matter Interaction and New Nonlinear Optical Materials and Physics of Low-Dimensional Structures - Nonlinear optical crystals: principles of the search for new promising materials