Achieving a near-perfect flat surface with roughness between 1-10 nm is challenging but possible, particularly in specialized applications like carbon face seals. The best flatness typically observed is around .000035", equivalent to three helium light bands, but achieving nanometer-level flatness introduces significant macroscopic challenges. Polishing to such precision requires a careful, multi-stage process, often done by hand, and is highly material-specific, with Gallium Arsenide being a common focus for research purposes. The need for such low tolerances is driven by the measurement of quantum transport phenomena in GaAs structures, which are critical for fundamental research. Overall, while difficult, the pursuit of ultra-flat surfaces is feasible with the right techniques and investment.
