Fractal analysis on topography of KDP surfaces by single point diamond tools method
2D and 3D fractal methods are used to analyze the KDP crystal surfaces machined by SPDT(single point diamond tools) method.The difference between 3D fractal dimension and roughness parameter is analyzed.And 3D fractal dimension has the inverse ratio with 3D roughness.Through 2D profile fractal analyses,it is found that the KDP crystal surfaces machined by SPDT method are strongly anisotropic and microscale wavenesses form to impact the optical performance of KDP components.The microscale waveness is incorrelate with roughness in certain range but has a direct relationship with the profile fractal dimension distribution of machined surface.Hence the microscale waveness can be reduced by adopting reasonable cutting parameters when the same roughness is maintained.In addition the profile fractal dimension distribution has a close directional form with its 2D power spectral density.