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.

中文翻译：

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研磨和机械研磨 Nb 表面的激光加工

研究了脉冲激光抛光对粗糙铌表面的影响。我们使用标准金刚砂纸创建了不同的明确定义的粗糙度轮廓，随后使用纳秒激光脉冲（波长为 1064 nm，脉冲长度为 10 ns）重熔大小约为 2x2 mm^2 的随机表面区域。使用光学轮廓仪和原子力显微镜研究原始和激光处理的表面，并通过相关函数描述表面形貌。对于 7 {\mu}m 以上和以下的分形，分别实现了均匀粗糙和高度光滑的表面几何形状。此外，还详细研究了激光加工过程中异物的行为。还通过检测电信号逐点监测抛光过程，即样品充电、这是强烈的激光照射造成的。发现测量的电荷与局部表面纹理相关。因此，可以直接从检测到的电信号中识别具有初始高粗糙度轮廓的区域和具有大量激光诱导缺陷的区域。