Fig. 2

Spectrally selective vs. broadband solar absorbers using fs-laser-treatment: The absorption and emission spectra for SSA and BBA obtained by treating a Al, b stainless steel and c Cu. Cu-SSA shows true spectral selectivity with similar solar absorption and significantly lower thermal emission. SEM images of d Cu-SSA and e Cu-BBA. The insets show the zoom-out view of Cu-SSA and Cu-BBA. Histograms of the size distribution of the formed surface structures for f the Cu-SSA and g the Cu-BBA surfaces. The size distribution was obtained using ImageJ.