Center For Optics Manufacturing Research Articles

Planarization of Gratings using Magnetorheological Finishing

ABSTRACTSurface planarization of BK7 glass gratings with periods of 130, 30, 16, 8 and 5 gm was performed with the magnetorheological finishing (MRF) process at the Center for Optics Manufacturing (COM). Approximately 0.5 μm of material was removed in the experiments. Grating height decreased as a function of grating period, going from ∼0.44 μm to ∼0.044 μm for a 130 μm period, and ∼0.44 μm to ∼30 Å for grating periods of 30, 16, 8 and 5 gm. The microroughness on ridges and in valleys of the grating structures also decreased with material removal from ∼100 Å to ∼10 Å for gratings with 30 and 16 μm periods.