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The tantalum and titanium plates were treated by pulsed, high power CO2 laser in the pressurized atmospheres of N2 and 02. Studies performed by the optical microscopy,microhardness measurements and the Auger electron spectroscopy revealed: (i) topographic modification of the surface caused by the temperature field (ii) metal hardening, caused by the laser shock, and (iii) alloying/cladding, caused by the chemical reaction between the metal surfaceand the gaseous atmosphere.1. INTRODUCTION High power laser-metal interactions in the pressured gaseous atmospheres are verycomplex and include the structural changes in the material, the changes in the surface layer (compositional and structural) as well as formation of patterns usually belonging to the convection process. These changes may be homogeneously or inhomogeneously distributed in space. In the cases studied on refractory metals (Ta and i), very inhomogeneous processes, some of which are interdependent (like thermal convection andthe surface chemical reactions), were analyzed.

An experimental evaluation of different resonator designs has been performed in order to verify the feasibility of a pulsed CO2 laser source for spaceborne Doppler LIDAR with a self-sustained TEA discharge channel. A laser with 10 J of energy/pulse, 1.2 is FWHM pulselength, less than 200 kHz frequency chirp has been demonstrated using a 5x5x100 cm3 active medium volume and a modified Self Filtering Unstable Resonator (SFUR) optical design.

The assessment of surface water salinity is a long standing feature request for water quality assessment by remote sensing. The aim of the present work is to test an empirical method for surface water salinity retrieval by means of multispectral satellite images at medium resolution (30 m). For this purpose, two case studies were selected: the first is Lake Qarun (Egypt), the second is an on-shore tract of central Adriatic Sea, located between the mouths of Tronto and Salinello Rivers (Italy). For the experimentation ALI (Advanced Land Imager) and Landsat ETM imagery was collected. Field data were acquired at both sites by means of in situ conductivity measurements, for calibration purpose. The model applied to convert atmospherically corrected reflectance value in practical salinity units (PSU) has been developed analysing the correlation between field data and an expressly defined salinity index. First results show a promising overall correlation (R 2 = 0.85), even if further work is required to provide a better validation.