Figure 2.

Large period ripples on an absorbing Si surface made by 1030 nm/230 fs pulses. (a) Large (indefinite) area nanotexturing of Si surface by ripples using cylindrical focusing at 0.5 MHz repetition rate and 50 mm s⁻¹ scan speed; line focus had aspect ratio length/width≈200. (b) Closeup SEM view of the ripples; scale bar=10 μm. (c) Circular grating made by cylindircal focusing with linear polarization rotated at 2° μm⁻¹ using a υ=0.1 mm s⁻¹ linear scan speed; arcs mark tangential line to the ripples orientation. Scale bar=10 μm.