On-machine correction of form error for structured surfaces with anisotropic diffusion filter

Structured surfaces with high aspect ratio are promising in optical components, healthcare devices, and microelectronics. A preferable method to create precise structured surfaces is using single point diamond turning with on-machine surface measurement (OMSM). However, fabricating these surfaces often pose challenges due to steep gradients and discontinuous slopes, leading to significant form errors in machining. We propose an innovative solution by employing partial differential equation (PDE) filtration in a closed loop compensation process to enhance form accuracy and surface roughness compared to traditional methods. We tackle the problem of over-smoothing induced profile error encountered with traditional Gaussian filters. The proposed compensation strategy adapts to surface curvature and reduces instrument noise during on-machine measurements. Experimental of fabricating a segment spherical artefact, demonstrate improved precision. After adopting the proposed method, the form error is reduced from 1.2 µm to 0.5 µm and vibration ripples are mitigated, and a better surface finish is achieved.