“…According to [11] the calculated absorptivity of pure iron at room temperature and perpendicular incidence is roundly 44 % at 532 nm and 36 % at 1064 nm. However, the absorptivity of laser radiation in metal surfaces does not only depend on wavelength, but also on polarization, workpiece temperature, angle of incidence, alloying elements, surface roughness and oxidation (see [11] for a general discussion). At microdrilling with ultrashort laser pulses, several of the aforementioned influencing values, if at all, are only known within wide limits.…”