Nanofinishing of BK7 glass using a magnetorheological solid rotating core tool.

Abstract

Surface finishing is a promising method to improve the optical characteristics of crown glass. BK7 finds its applications in transmissive optics, i.e., lenses of binoculars, lenses of microscopes, lenses of telescopes, and light-emitting diodes. The magnetorheological (MR) nanofinishing of optical glasses using a solid rotating core tool is found more advantageous than the other advanced finishing processes in aspects such as precision and accuracy. In the present research, the MR nanofinishing with a solid rotating core tool is carried out on the BK7 glass of size 10×10×3 mm. Response surface methodology is conducted in order to find the optimum process parameters. The effects of process parameters on the percentage change in surface roughness are analyzed. The best surface roughness Ra and Rq values are achieved at 22nm and 32nm from the initial of 41nm and 57nm in 30min of the finishing time cycle. To study the surface morphology of nanofinished BK7 glass, scanning electron microscopy is performed with sputter coating of gold on a glass specimen.