Nanosecond pulsed laser irradiation of sapphire for developing microstructures with deep V-shaped grooves

Nozomi Takayama, Shouhei Asaka, Jiwang Yan

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)


A nanosecond pulsed Nd:YAG laser was used to irradiate a sapphire substrate to produce 3-dimensional microstructures with sharp V-shaped grooves. In initial experiments, where single grooves were machined, a maximum taper angle of ∼79° was obtained. At constant laser parameters, the taper angle remained constant. As the taper angle increases from a flat surface, the irradiated area increases while incident fluence decreases; once the incident fluence approaches the ablation threshold, the taper angle becomes constant. The taper angle could be controlled by the laser fluence, scanning speed and incident angle of the laser beam. Using these results, a kind of surface microstructure, comprised of micropyramids with steep walls, was successfully machined for optical measurement applications. The surface roughness, transmittance and crystallinity of the microstructure surface could be controlled by the laser scanning speed. By applying the taper formation mechanism proposed in this study, the micromachining of sharp microstructures with steep walls on various hard brittle materials becomes possible.

Original languageEnglish
Pages (from-to)440-450
Number of pages11
JournalPrecision Engineering
Publication statusPublished - 2018 Apr


  • Groove formation
  • Hard brittle material
  • Laser processing
  • Microstructure
  • Optical element micromachining
  • Sapphire
  • Taper formation

ASJC Scopus subject areas

  • General Engineering


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