Interlaced Laser Beam Scanning: A Method Enabling an Increase in the Throughput of Ultrafast Laser Machining of Borosilicate Glass

摘要

We provide experimental evidence that the laser beam scanning strategy has a significantinfluence on material removal rate in the ultrafast laser machining of glass. A comparative study oftwo laser beam scanning methods, (i) bidirectional sequential scanning method (SM) and (ii)bidirectional interlaced scanning method (IM), is presented for micromachining 1.1‐mm‐thickborosilicate glass plates (Borofloat? 33). Material removal rate and surface roughness are measuredfor a range of pulse energies, overlaps, and repetition frequencies. With a pulse overlap of ≤90%, IMcan provide double the ablation depth and double the removal rate in comparison to SM, whilstmaintaining very similar surface roughness. In both cases, the root‐mean‐square (RMS) surfaceroughness (Sq) was in the range of 1 μm to 2.5 μm. For a 95% pulse overlap, the difference was morepronounced, with IM providing up to four times the ablation depth of SM; however, this is at thecost of a significant increase in surface roughness (Sq values >5 μm). The increased ablation depthsand removal rates with IM are attributed to a layer‐by‐layer material removal process, providingmore efficient ejection of glass particles and, hence, reduced shielding of the machined area. IM alsohas smaller local angles of incidence of the laser beam that potentially can lead to a better couplingefficiency of the laser beam with the material.