Hello, For a special optical device I'm fabricating, after depositing a 12µm thick SiO2 top cladding (with plasma CVD) around a 6µm X 6µm Ge-doped SiO2 waveguide core, I would need to mechanically planarise the top surface until I expose again the top side of the core. The substrate is a 4'' wafer. The accuracy I would need on the planarisation depth is very high, it should be better than +/-1µm, and of course the surface should not become too rough, otherwise the optical losses due to light scattering would increase too much. If someone of you has a polishing machine who can do this job I would be very interested. Best Regards Matteo Dainese