DEVELOPMENT OF A ONE-MICROINCH (250A) SPINDLE FOR DIAMOND TURNING OF OPTICS

摘要

A submicroinch spindle accuracy is a requirement in achieving the capability to machine large-diameter optics to better than a 125-nm (5-Min) contour accuracy. A 100-mm (4-in)-radius air-bearing spindle with the capacity to carry a load of 880 N (200 Ibf), centered at a distance of 305 mm (12 in) from the spindle faceplate, has been assembled and tested. Performance of the upgraded spindle has been evaluated. A 152-mm (6-in)-radius air-bearing spindle, capable of carrying a 2640-N (600-lbf) load centered 152 mm (6 in) from the spindle faceplate, has been fabricated and is now being assembled. Diamond machining of journal-bearing surfaces to better than a 125-nm (5-μin) roundness error was used to achieve the desired spindle accuracy. A disc-type eddy-current motor has been designed, fabricated, and tested in efforts to improve the spindle drive system.