Correlation Among Particle Size Distribution, Subsurface Damages Distribution and Surface Roughness in Optical Polishing Process

Abstract

Restricting polishing induced subsurface damage and obtaining super smooth surfaces are important in high quality laser systems. Here, experiments and theoretical simulations are combined to investigate correlations among particle size distribution, subsurface damage distribution, and surface roughness evolution in the optical polishing process. This reveals that the fraction of observable subsurface damage increases rapidly with increased particle size, which results in greater and deeper subsurface damage. In addition, control of the tail end particle size distribution is also critical for controlling polishing-induced subsurface damage. In the high surface roughness period, the surface roughness increases linearly with increased subsurface damage. In the low surface roughness period, without any polishing induced subsurface damage, optimizing pad properties to reduce microscale surface undulation could further improve surface roughness. Making sure that no observable subsurface damage is generated is the precondition for obtaining a super smooth surface. Using nanosized particles could greatly reduce the particles’ bear load and finally obtain a super smooth surface without any subsurface damages.