M. Autric

High-intensity KrF excimer laser processing of metal surfaces

Abstract The interaction of high-intensity pulsed UV radiation with solid materials involves complex phenomena. Generally, they depend on different factors including laser wavelength, pulse duration, energy and power density, laser spot size, nature of the material and surface characteristics. The experiments presented in this paper have been performed using a 248 nm KrF laser which allowed aluminium and titanium alloys to be irradiated with an energy density from 0.3 up to 100 J/cm 2 and a power density from 1 up to 300 MW/cm 2 .

High-Power Laser Radiation-Induced Shock Waves in Solids

When a solid material is irradiated using high-power laser radiation, a fraction of the incident radiation is dissipated in the form of a shock wave in the sample. This article gives an account of shock measurements carried out using various pressure gauges on aluminium alloy and graphite samples irradiated using a CO2 pulsed laser. These results are then used for comparison with a theoretical model.

Shock Waves and Flows in UV Laser-Produced Plasmas

An experimental study of the flow induced by a high-energy long pulse KrF excimer laser in front of metallic samples is described in this paper. The samples (aluminum and titanium alloys) have been irradiated with an energy density from 5 J/cm2 up to 130 J/cm2 with a pulse duration r=300 ns and at different ambient pressures (from 5.10-3 to 105 Pa) for different background gases (air, nitrogen, argon, helium). We set up a Mach-Zehnder interferometer, using a cw argon laser, and a fast image converter camera to visualize the plasma flow. The absorption of the 5145 A argon wavelength by the neutral titanium vapor plume has permitted to visualize simultaneously the expansion of the plasma flow, the formation of the shock wave and the neutral titanium vapor.

Characterization of metal surfaces irradiated by a long‐pulse KrF excimer laser

Metallic samples were irradiated by a long‐pulse (τ > 300 ns) KrF laser. The experiments were performed with an energy density of 0.3–120 J cm−2 and a power density of 1–400 MW cm−2. The samples investigated were pure aluminum, aluminum alloy, low‐alloy constructional steel and titanium alloy. They were polished to obtain a roughness of 10 < Ra < 0.08 μm and stress‐relief heat‐treated for some residual stress measurements. The characterization of the irradiated metal surfaces was performed using scanning electron microscopy (SEM), roughness analyzers, a microhardness tester and X‐ray diffraction (XRD) residual stress apparatus. The improvement or deterioration in the mechanical properties of the metallic samples and some potential applications are discussed.

High‐energy, long‐pulse, electron‐beam driven KrF laser in laser–matter interaction

A high‐energy, long‐pulse, large‐volume, electron‐beam driven KrF laser was constructed in order to carry out laser–matter interaction experiments with metals, ceramics and polymers in the ultraviolet spectral range at 248 nm. This laser delivers up to 200 J in 400 ns. In the framework of applications such as machining or shock‐hardening, the knowledge of mechanical phenomena is very important in order to understand and maximize laser parameters. An experimental investigation was carried out into the mechanical effects (specific impulse and pressure) in direct ablation and in confined ablation mode.

Characterization of metal surfaces irradiated by a long-pulse KrF excimer laser

Metallic samples have been irradiated by a long-pulse (τ >300 ns) KrF laser. The experiments have been performed with an energy density of 0,3 to 120 J/cm2 and a power density of 1 to 400 MW/cm2. The samples investigated were pure aluminum (1050 A: 99,5% Al), aluminum alloy (2017A), constructional steel (35NCD16: 0,35% C, 4% Ni, 1,8% Cr) and titanium alloy (Ti6A14V). They were polished to obtain a roughness 10 300 ns) KrF laser. The experiments have been performed with an energy density of 0,3 to 120 J/cm2 and a power density of 1 to 400 MW/cm2. The samples investigated were pure aluminum (1050 A: 99,5% Al), aluminum alloy (2017A), constructional steel (35NCD16: 0,35% C, 4% Ni, 1,8% Cr) and titanium alloy (Ti6A14V). They were polished to obtain a roughness 10<Ra<0,08 μm and stress- relief heat treated for some stress measurements after irradiation. The improvement or the decrease of the mechanical properties of these metallic samples and some potential applications are discussed.