Micromachining of polyurea aerogel using femtosecond laser pulses

We successfully sliced cylindrical polyurea aerogel samples of 10-15 mm in diameter into 1-3 mm disks using femtosecond laser. The experiments were performed using a Ti:sapphire laser with 800 nm wavelength in ambient air with a pulse duration of similar to 40 fs. We found that the laser fluence to breakdown this material is 1.3 J/cm(2). The ablation rate at different energy levels was evaluated. The factors influencing the ablation surface quality were investigated. The proper fluence to slice the porous polyurea is 6.4-8.9 J/cm(2) with the beam linearly scanning the sample at a speed of 0.1 mm/s. 01 5.1-7.6 J/cm(2) with the beam circularly scanning the sample at a speed of 3.5-4 degrees/s, and high quality machining surface was obtained under these conditions. The material removal mechanisms are proposed. Structural details of the machined area were characterized using a number of techniques such as optical microscopy and scanning electron microscopy. This work provides insights for micromachining nanostructured porous polymers using femtosecond lasers. (C) 2010 Elsevier B.V. All rights reserved.