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Abstract: The porous polyurethane polishing pads are used in the optical glass chemical mechanical polishing process. The wear of the polishing pad and morphology are important for the polishing process efficiency and the surface quality. The subject of this work is to evaluate the morphology and wear of porous polyurethane polishing pads, and their influence on the material removal rate and quality in the optical glass chemical mechanical polishing process. For this study, several optical glass polishing operations were done using different porous polyurethane polishing pads. The polishing pads were recovered after polishing to be characterized using several techniques such as: the SEM, the optical microscopy and the mechanical profilometry. The obtained results show, that the polyurethane polishing pads produce good surface quality with high material removal rate. The polyurethane polishing pads are relatively wear resistant in the first hour of use; however some changes were seen on the polishing pads, and their characteristics. The most conspicuous change is the abrasive grains incrustation in the polishing pads microstructure that changes their properties. [Copyright &y& Elsevier]

Abstract: The quality of an optical glass component is influenced by the presence of surface and subsurface defects generated by machining processes, especially lapping. However, the damaged area is characterized by roughness and crack layers that contribute to reduce the component''s mechanical and optical performances. Evaluation of these defects leads to the obtainment of the best finishing technique for optical glass components. In this work, the effect of the lapping technological parameters (lapping time and alumina abrasive grain size) on the glass surface roughness as well as the depth of the damaged layer were determined. Furthermore, a proportionality constant between the total height of the roughness profile (Rt) and the subsurface damage layer was calculated. The damaged depth was characterized using mechanical techniques and microscopic analysis. The obtained results show an important damage of the glass surface, since the first few seconds of contact time between the surface and the grains. The increase of the lapping time gives rise to the propagation of this damage to reach its maximum and then a material removal rate is observed. At the end of the operation, a defined final surface roughness and a subsurface damaged layer are obtained. The proportionality constant between the subsurface damage layer and the total height of the roughness profile (Rt) was found to be 6.7±0.8. [Copyright &y& Elsevier]

Abstract: In this work the wear behavior of cerium oxide abrasive grains during the glass polishing was studied. Polishing tests have been done by different types of cerium oxide abrasive grains. The grains have been recovered and examined during the operation. The morphology, the granulometric distribution, the chemical composition and the agglomeration phenomenon of recovered grains have been studied. The results showed that the fracture is the main cause of the abrasive grain wear of the cerium oxide abrasive grains, which permitted to the abrasive grains to preserve their initial morphology for a long time during the process. The cerium oxide abrasive grains undergo a partial wear during their use in polishing and it is closely related to the process parameters. The granular agglomeration phenomenon of the abrasive powder is very much present in the polishing process and generates bigger grains being able to influence the product quality. [Copyright &y& Elsevier]

Ellipsometry is a technique of surfaces analysis, founded on the measure of light polarization state after reflection on a flat surface. The present work consists in characterizing the surface quality of polished optical glass by ellipsometry and use of effective medium model. The measured ellipsometric parameters enabled us to obtain a correlation with surface roughness on the base of the theory of Maxwell-Garnett assuming an effective medium layer of effective thickness de and refractive index ne. Observations by Nomarski microscope made it possible to confirm the results obtained. [ABSTRACT FROM AUTHOR]

Highlights: [•] Measurement of the polishing pressure, the contact surface and the friction coefficient. [•] Establishing a correlation between the friction coefficient, the contact surface and the polishing pressure. [•] Friction behavior and the contact surface effect on the polished glass surface. [•] The polishing pressure and the contact surface influence greatly the frictional behavior. [Copyright &y& Elsevier]