Micromachining Ultrafast Lasers

One of the challenges for laser micromachining is removing only the desired material, usually through localized heating, while at the same time minimizing the extent of the HAZ to any of the remaining material. Delivering laser irradiation with near-perfect beam quality precisely to the target region is a necessary step to achieving this desired result. Shorter wavelengths and shorter pulse widths are advantageous to achieving higher-quality results. Wavelengths in the VIS and UV spectral regions, for example, are more readily absorbed in most materials, resulting in shallow absorption depths and a significantly reduced HAZ. UV lasers also can be focused into tighter spots for smaller, more precisely machined features, and they have longer depth-of-focus for improved process yields. Ultrashort pulse widths in the ps and fs regime yield intense peak powers that result in nonlinear absorption at the sample for instantaneous material vaporization, very minimal heat transfer into the material, and a negligible HAZ. This process, commonly referred to as a "cold ablation" process, is depicted below. Please see Newport.com for additional information on Laser Micromachining.