Magnetorheological finishing (MRF) is a deterministic process using a precise interferometrically documented subaperture tool to correct waveform errors by selectively removing material under a controlled and predicted process. MRF computer controlled deterministic processing can remove many of the artisan steps necessary to finish a fine optical surface. Optical form profile is directly fed into MRF machine-based software from an array of advanced 3D metrology platforms. Consistent and reliable data transfer from the world's state of the art metrology systems into MRF based polishing routines creates truly spectacular results on flat, spherical or aspherical surfaces. The guesswork, long iterative processing steps, and expensive empirical labor associated with precision optical surfaces is not present when using MRF technology.
MRF Machines are capable of producing high precision flats, spheres, and aspheres exceeding λ/20 accuracy. In addition to polishing rotationally symmetric parts, they can utilize a raster tool path routine to polish rectangular and polygon surfaces allowing for surface figure correction as well as angular correction. Understanding optical surface performance and utilizing proprietary optical correction software, MRF-based polishing can also be used to induce surface error to correct for total transmitted wavefront errors.
Daniel C. Harris, "History of magnetorheological finishing," Proc. SPIE 8016, Window and Dome Technologies and Materials XII, 80160N (20 May 2011); doi: 10.1117/12.882557; https://doi.org/10.1117/12.882557