Atmospheric plasma jet used as polishing tool for optical glasses

Abstract

Plasma Jet assisted smoothing of rough ground optical surfaces is presented. An accurate temperature regime during the process is inevitable to achieve a uniformly smoothed surface. The possibilities for in-process temperature control are demonstrated on the example of Fused Silica and N-BK7® polishing. For both materials, the surface roughness RMS value can be significantly reduced by a factor of 20 to 1000 depending on the material and the initial ground state. An annealing step after smoothing is necessary to minimize birefringence caused by internal stress. The achievement of the existing requirements for precision optics is demonstrated.