Fig. 4
From: Surface structuring of glass with submicrometer features using selective laser etching
Surface topographies structured with a repetition rate of 700 kHz, pulse energy of 350 nJ and writing speed of 20 mm/s. The measured average surface roughnesses \(S_a\) and spatial frequencies \(S_{al}\) with the corresponding polarizations are a \(S_a=30\,nm\) and \(S_{al}=640\,nm\) with a parallel polarization, b \(S_a=65\,nm\) and \(S_{al}=700\,nm\) with a perpendicular polarization and c \(S_a=78\,nm\) and \(S_{al}=800\,nm\) with a circular polarization. Hereby, \(S_a\) gives the average peak-to-valley value and \(S_{al}\) the spatial frequency value averaged over all high frequency height-oscillations of the shown area. The size of section a is \(\approx\) 50 µm × 100 µm and was measured with a 150× objective whereas the sizes of b and c are \(\approx\)100 µm × 250 µm which were measured with a 50× objective in confocal mode.
