INFRARED OPTICAL-PROPERTIES OF PULSED-LASER DEPOSITED CARBON-FILMS WITH THE BONDING AND PROPERTIES OF DIAMOND

Composed of packed nanophase nodules in which the carbon atoms are linked with the tetrahedral bonding of diamond, laser plasma films are deposited in vacuum onto almost any substrate by condensing carbon ions carrying keV energies. These multiply charged ions are obtained from the laser ablation of graphite at intensities in excess of 10(11) W cm(-2). The high energy of condensation provides both for the chemical bonding of such films to a wide variety of substrates and for low values of residual compressive stress. Coatings of 2-5 mu m thicknesses have extended lifetimes of important optical materials against the erosive wear from high-speed particles and droplets by factors of tens to thousands. In this work, the optical properties of these films at infrared (IR) wavelengths were studied. Transmission spectra of several freestanding films on silicon frames were measured. Using a model considering rough surface scattering and free carrier absorption, satisfactory fits to these transmission spectra were obtained and from them the optical parameters were extracted. The characterization studies performed in this work indicated a great potential for the laser-deposited nanophase diamond films in optical applications.