Novel simulation technique for efficient fabrication of 2m class hexagonal segments for extremely large telescope primary mirrors

2m class hexagonal primary mirror segments for extremely large telescopes such as OWL and EURO50 receive an increased attention from the optics fabrication community world-wide. We report the development of a novel simulation technique offering cost-effective mass fabrication strategies for such mirrors of tight specifications. A family of static tool influence functions (TIFs) was derived using the Preston's material removal equation. We then confirmed that the mathematical TIFs can re-produce the material removal foot prints of the bulged precessing tooling reported elsewhere. For fabrication simulation, these TIFs are fed into the in-house developed polishing algorithm that uses a combination of the fixed tool path patterns and the floating trajectory management based on the error grid weighting and the irregular tool paths. The algorithm also optimizes other control parameters including dwell time and tool pressure in real-time as the machine runs. Trial simulation runs using various combinations of the TIFs and the polishing algorithm showed the feasibility of producing the 2m class primary segments with the bulged precessing tooling. The details of the simulation technique together with the results and implications for mass fabrication are presented.