Laser beam percussion drilling (LBPD) can create high density holes in aerospace materials with the repeated application of laser pulses at a single spot. In this study, one-parameter-at-a-time approach has been used to investigate the individual effect of peak power, pulse width and pulse frequency on geometrical accuracy and metallurgical distortion during LBPD of 0.85[Formula: see text]mm thick Ti–6Al–4V sheet using 200[Formula: see text]W Yb:YAG fiber laser. It has been found that the output parameters behave differently at the higher and lower values of a particular input process. The increase of pulse width from 1 to 1.50[Formula: see text]ms increases hole taper by 20% whereas the same corresponding change from 1.50 to 2.00[Formula: see text]ms reduces the taper by 20%. The increase of pulse frequency from 10 to 50[Formula: see text]Hz reduces hole circularity by 40% but the same proportionate change from 50 to 90[Formula: see text]Hz reduces circularity by 79%. Increase of peak power from 1.70 to 2.0[Formula: see text]kW increases hole taper by 8% but the corresponding increase from 2 to 2.30[Formula: see text]kW is 143%.
We propose a very simple technique to extract, in a short pulse with good optical quality, all the laser energy in a pulsed system. The method essentially consists of injecting into a high power laser a short and weak pulse at a moment close to the time when the gain is equal to the losses (laser threshold). Subsequently, the spontaneous emission radiation is dominated at all times by the injected pulse. After multipass amplification, all the energy available in the system is extracted by the injected pulse.In this way, pulses of 2 ns have been obtained from a TEA–CO2 laser of 15 J.
172 fs, 243 kW peak power pulse generation from a Ho-doped fiber laser system
