Product Code: ICAL05_M204

Feasibility Study of Laser Ablation using Long-Pulsed, 300w, Cw Single-Mode Fiber Laser
Authors:
Jay Tu, North Carolina State Univ.; Raleigh NC USA
Jason Dilwith, North Carolina State University; Raleigh NC USA
Wm. Harp, North Carolina State University; Raleigh NC USA
Presented at ICALEO 2005

Traditionally, nano-second, pico-second, and femto-second pulsing lasers are used for micro-hole drilling. Using the ultra-short pulse duration, extremely high peak powers can be achieved for laser ablation to drill holes. In this study, we examine the use of a 300W CW fiber laser operated in a modulated mode for micro-hole drilling. As the CW power of this fiber laser is extremely high compared with those of short-pulse lasers, it is envisioned that the excellent beam quality of the fiber laser can allow fine focus with a pulse duration in micro-second ranges to achieve very high power density, similar to those achieved by short-pulse lasers. It is hoped that using the continuous power fiber laser will prove to be versatile and can therefore be used for both macro and micro machining of materials. The smallest pulse width that was used for the tests was 100?s and M2 is 1.05. The current setup of the laser has a 9mm beam out of the delivery fiber, into a 5x beam expander followed by a 150mm Gradium focusing optic, which produces a 10.8?m focused spot size. The material that has been used for testing is 304 and 316 stainless steel. The optimal focus has been achieved by using a large range of focusing depths starting from far above the material to well below the material surface. Initial tests have shown that 80?m blind holes can be achieved with one single pulse. The hole roundness is excellent with very small heat affected zones.