Measurement of the ablated thickness of films in the launch of laser-driven flyer plates

Laser-driven flyers were launched from substrate-backed aluminium films. The flyers were approximately 1 mm in diameter and a few micrometres thick and were produced by single pulses from a Q-switched Nd:YAG laser, of 10 ns full-width half-maximum and typically up to a few hundred millijoules energy. The ablated thickness of the film was measured using photo-emission spectroscopy to detect the vaporized tracer material in the laser-induced plasma: tracer layers of yttrium were deposited within the aluminium films at various depths, with sub-micrometre accuracy. Using this technique, the ablation depths were measured to be between 280 and 1100 nm for laser pulse energies between 50 and 156 mJ.