High quality laser milling of ceramics, dielectrics and metals using nanosecond and picosecond lasers

Laser milling of industrial materials like ceramics, dielectrics and metals is of significant commercial interest for microfabrication of micro-moulds and other micro-system devices. 2.5D laser machined structures were generated in alumina, tungsten and steel substrates using a nanosecond copper vapour laser (511nm) at 10 kHz. Preliminary results in fused silica, alumina and steel are also presented from a high repetition rate amplified mode-locked picosecond Nd:vanadate laser. It is shown that high quality surface finish can be achieved with both laser types; for example, average surface roughness, Ra ~ 300nm has been demonstrated in steel. Fused silica could only be processed with picosecond laser pulses. Volume removal rates are analysed, which are especially high for difficult materials like tungsten (~0.1mm3/min) and are greater compared to other milling technology like micro-EDM. Surface roughness measurements in these materials using white light interferometry are reported along with SEM analysis.