Preparation of a Sol-Gel Broadband Antireflective and Scratch-Resistant Coating for Amplifier Blastshields of the French Laser LIL

A broadband antireflective and scratch resistant coating made from tantalum and silicon oxide-based layers has been developed using the sol-gel route for amplifier blastshields of the french laser LIL. Sol-gel synthesis have been carried out starting from cheap precursors in order to produce metallic-based solutions, each one suitable for liquid-deposition technique use such as dip-coating. Baking step temperature does not exceed 150°C during 30 minutes allowing to coat various substrates and to offer scratch-resistance properties in compliance with US-MIL-C-0675C severe test. The antireflective properties of the coating (layer thickness) were optimized to maximize the amplification yield (in comparaison to uncoated blastshield), taking into account the optical and geometrical parameters of the multipass amplification laser cavity. Experimental antireflective coating deposition process onto large-area glass plates sized to the LIL amplifier blastshields (1811 × 635 × 6 mm) is described.