Laser ablation using a long-pulsed, high-fluence, CW single-mode fiber laser

Laser Beam MicroMachining (LBMM) – A review

“…Low peak power will produce low striations and hence it will improve the surface roughness. Harp and Tu [71] investigated whether a fiber laser designed to be used in a continuous mode can be utilized to perform pulsed ablation. It was observed that the MRR is lower for short pulsed laser and it takes approximately 100 pulses to create the same depth as 1 pulse from the CW laser.…”

Process Anatomy for High Aspect Ratio Micro-Hole Drilling with Short Micro-Second Pulses Using a CW Single-Mode Fiber

“…For example, Harp et al (2008) conducted micro-hole drilling with a 300 W, CW, Yb-doped fiber laser (YLR-300, IPG), which has a near perfect beam quality M 2 =1.04 and the beam can be focused down to 10 μm with a 100 mm lens. It can also be modulated to produce pulses from 1 μs to any length of pulse duration.…”

“…The feasibility of laser drilling with such a CW laser via modulation control was demonstrated by Harp et al (2008), in which pulses from 15-40 μs were used to produce holes with diameters from 40 to 100 μm and depths from 25 to 50 μm. This work indicated that, by using high beam quality lasers, micro-hole drilling with pulse durations in the short microsecond range (1-10 μs) has become feasible for applications which require moderate material removal depth per pulse, narrow opening (due to much smaller beam spot sizes), and moderate hole quality (due to moderate melt ejection).…”

“…Vol. 5, No.4;2013 power. Based on the results of Table 1, we can conclude that a hot vapour/plasma over 16,000 K and as high as 71,000 K did exist in the first 1 μs of the process during the laser initial spike.…”

“…5,No. Vol. 5, No.4;2013 Stage 4 (1 μs ~ 2.5 μs) (Process Anatomy Diagram #4): The laser power fell to its steady state (300 W) at 2.5 μs.…”