Percussion drilling of metals using bursts of nanosecond pulses.

The effect of ns bursting on percussion drilling of metal is investigated experimentally and analytically, and compared with the efficiency and quality of drilling using single ns pulses. Key advantages are demonstrated, correlating well with the results from a thermal theoretical model. The 1064 nm bursts contain up to 14 pulses of various pulse widths and spacing, and at frequencies of tens of MHz within the burst. The individual pulses have pulse widths of 10 to 200 ns, and up to 12 kW peak power. Burst repetition frequency is single shot to 500 kHz.

Structuring materials with nanosecond laser pulses.

Ablation of silicon and metals is investigated using a 1064 nm pulsed fiber laser, with pulse energy up to 0.5 mJ, peak powers up to 10 kW, and pulse widths from 10 to 250 ns. A simple thermal model is employed to explain the dependence of scribe depth and shape on pulse energy or peak power. We demonstrate that pulses of high peak powers have shallow penetration depths, while longer pulses with lower peak powers have a higher material removal rate with deeper scribes. The key parameter that enables such variation of performance with changes in peak pulse power or peak irradiance on the material surface is the nonlinear increase of the absorption coefficient of silicon or metals as its temperature increases.