  The effect of pulsed laser polishing on rough niobium surfaces was
investigated. We created different well-defined roughness profiles with
standard emery papers and subsequently remelted random surface areas with a
size of about 2x2 mm^2 with nanosecond laser pulses (wavelength of 1064 nm,
pulse length of 10 ns). Pristine as well as laser-treated surfaces were
investigated using optical profilometry and atomic force microscopy, and the
surface topography was described by means of correlation functions. Uniformly
rough and highly smooth surface geometries were achieved for fractals above and
below 7 {\mu}m, respectively. Moreover, the behavior of foreign particles
during the laser processing was investigated in detail. The polishing procedure
was also monitored point by point by detecting electrical signals, i.e., sample
charging, which resulted from the intense laser illumination. The measured
electrical charges were found to be correlated with the local surface texture.
Thus, regions with initially high roughness profiles and regions with extensive
laser-induced defects could be directly identified from the detected electrical
signals.

Applied Physics