Conventional material removal of BK7 optical glass will normally result in brittle fracture at thesurface, generating severe subsurface damage and poor surface finish. Subsurface damages inducedby grinding strongly influence the mechanical strength and optical quality of optical glasses.However, through ductile mode grinding it is possible to reduce the surface and subsurface cracks.It is meaningful to evaluate the depth of subsurface cracking through the measurement of surfaceroughness under different grinding parameters. In this research, the surface and subsurface damagesduring micro cup grinding and lapping process of optical glass BK7 are being investigated. In orderto invest the subsurface damages, cross section polishing method is being used and the crosssections are inspected through SEM microscope. The results indicate that number of subsurfacemedian cracks after lapping process are strongly decreased and surface lateral cracks are extendedall over the sample's ground surface. Manuscript profile

Surface roughness is a significant parameter which determines the efficiency of optical components. Surface damages induced by grinding strongly influence the mechanical strength and optical quality of optical glasses. It is meaningful to rapid evaluate the surface roughness through the measurement of different grinding parameters. In this study, a cup diamond wheel (D64) is used in grinding process of the specimens made of BK7optical glass to investigate the influences of grinding parameters on the surface roughness. The grinding parameters used in this study are depth of cut, cutting speed, tables speed and feed rate; and effects of these parameters are studied. The dependence of surface roughness on grinding parameters was systematically analyzed. The experimental results indicate that feed rate, depth of cut and cutting speed have the most significant effect on surface roughness, respectively. By increasing feed rate and depth of cut, the surface roughness increases and increasing cutting speed results in a decrease in surface roughness. Manuscript profile