Surface morphology of cerium oxide ablated by femtosecond-pulsed laser with varying target scanning speeds
An 800 nm femtosecond pulsed laser operating at 80~MHz pulse repetition rate was used to ablate different areas of a pelleted CeO2 target with different scanning speeds in 25-30 mTorr vacuum. After which, the target was examined using surface electron microscopy to observe its surface morphology. The grooves formed along the laser path confirm successful material removal and surface modification. SEM image analysis shows the grooves width to be narrower for faster target rotation speeds. Qualitatively, a faster rotation produces grooves that appear to be melted indicating the onset of ablation. These can be explained by the reduced heat accumulation effect in the material as the target rotates faster and the laser pulses are more spatially displaced at the target surface, leading to a less effective ablation in terms of area ablated.