Correlation between the surface quality and the abrasive grains wear in optical glass lapping

The subject of this study is to determine the relation between the optical glass surface quality and the wear of abrasive grains used in finishing process. The glass surface quality was characterized by the roughness (rms,CLA and peak to valley). Alumina abrasive grains (Al₂O₃) are used with average sizes (80, 40, 20, 7 μm) respectively. After 2 min lapping for each fraction of grains the following RMS are obtained 1.39, 0.57, 0.51, 0.33 μm. The corresponding peak to valley are respectively 7.5, 3.66, 2.88, 2.10 μm. The grains wear was characterized by the grains edges wear (roundness) and by their fractures. An optical microscope (CMM Scope Check) and a SEM are used for their observation. The alumina grains size distribution was also studied using a laser diffraction particle size analyzer (Shimadzu Sald-2001).