Single point diamond turning of glass

Thesis (Ph. D.)--University of Rochester. College of Engineering and Applied Science. Institute of Optics, 1992.The feasibility of single point diamond turning optical quality glass surfaces has been experimentally studied. The main objective of the research is to study the ductile removal process of glass and identify the important parameters. By investigating several optical glasses and varying different machining variables, a matrix of the important parameters has been generated. A precision lathe capable of ductile machining glass has been assembled by adding a nano-positioning toolholder to an existing machine. The toolholder enables the structural loop between the tool and workpiece to be effectively closed. Using a proximity sensor and analog electronics, a feedback loop has been constructed that increases the rigidity, thermal stability, and tool positioning accuracy of the existing machine. With the closed loop system, the tool positioning resolution is 15 nm and the effective structural loop stiffness is 1.75 x 10³ N/μm. The closed loop system has been verified by machining a circular grating in germanium to within 3 nm of its theoretical form. The ductile machining of glass was limited by one key variable, tool edge wear. For every glass investigated, except FCD1, there was nearly instantaneous catastrophic loss of the cutting edge due to oxidation and/or graphitization of the diamond