FREEFORM SURFACE FABRICATION IN CYLINDRICAL COORDINATES

摘要

Diamond tuning lathes augmented with fast tool servo technology are an efficient and accurate means of producing precision optical and mechanical surfaces. In this paper, a comprehensive approach to the fabrication of freeform surfaces with diamond tools is presented. A variety of fast tool servos have been developed at the Precision Engineering Center (PEC) over the past 25 years. The latest system, FLORA II [1], has a 6 mm range and has demonstrated 2 nm RMS surface finish and 31 nm RMS figure error machining a 50 mm diameter titled flat with 1 mm peak-to-valley excursion at 600 rpm. This is comparable to the best results obtained from the base diamond turning machine, an ASG2500. FLORA has its own DSP based controller and is fully integrated into the machine. Matlab software has been developed to generate tool path data for machining complex surfaces with the FLORA system. This software can also create design data for the spherical coordinate measuring machine, Polaris 3D [2], "closing the loop" from design to fabrication to metrology. Finally two examples are discussed. One is a 100 mm aperture far off-axis segment of a biconic mirror for an infrared spectrometer and the other is a small, multi-element collimating optic for a diode laser.