a revolutionary technology that takes the mystery out of precision finishing. Optical surfaces are polished in a computer-controlled magnetorheological (MR) finishing slurry. Unlike conventional rigid lap polishing, the MR fluid acts as a compliant polishing lap, whose shape and stiffness can be magnetically manipulated and controlled in real time. The optic's final surface form and finishing results are precisely predicted through the use of computer algorithms that map and control material removal across the workpiece.