Improving the quality of femtosecond laser processing micro-hole array by coated with aluminum film on fused silica sheet

We demonstrate a novel femtosecond laser beam machining method which is proposed to achieve better quality micro-machining. The fused silica sheet coated with aluminum film was prepared by Pulsed Laser Deposition (PLD) in the high vacuum chamber (below 5 × 10−4 Pa). After femtosecond laser ablation, the aluminum film on fused silica sheet was cleaned by hydrochloric acid solution (HCl) in a solution of 10% until the aluminum film was absolutely reacted, finally the micro-hole array was formed on the silica. The existing of a thin film is found to be effective for improving the quality of micro-machining. The micro-hole arrays fabricated by the new method were quite good in roundness and the morphology of single hole was relatively good, and the edges of the holes were with no cracks and recast layer. In addition, the effect of the fluence of femtosecond laser and the average diameter of the micro-hole array on the fused silica sheet was investigated. Finally, we examined the diffraction characteristic of the micro-hole array to reflect the overall morphology of holes.