Polishing spherical BK7 workpieces with fiber-based tools

This work is a continuation of previously published work on the application of fiber-based tools in precision polishing of optical components. Previous publications mainly focused on understanding how fiber-based tools remove material and the potential of such tools in reducing existing midspatial frequency errors on planar samples. In this work, an exemplary tool consisting of nylon 6/6 fibers is used in a five-axis computerized numerically controlled machine tool to evaluate the tool's ability to polish nonplanar BK7 components. The five-axis system has an inline slurry feed system which is found to produce higher material removal rates than the nonrecirculatory slurry bath configuration used in earlier polishing tests. Polishing results obtained on planar and spherical surfaces in the five-axis system show close agreement with that predicted via convolution. A finite element model of the fiber's interaction with a concave surface shows that the calculated local pressure distribution reflects that observed experimentally, thus further supporting the predictable behavior of fiber-based tools. (C) 2019 Society of Photo-Optical Instrumentation Engineers (SPIE)