Progress towards improving glass grindability: a glass chemistry approach

Abstract

Optical glasses have traditionally been selected for use in optical systems based solely on their optical properties, specifically refractive index and dispersion. Ideally, one would like to select an optical material with desired optical properties and the knowledge that it can be easily fabricated using conventional or advanced fabrication techniques with good figure accuracy, low microroughness and subsurface damage. These three criteria have been identified by researcher’s at the Center for Optics Manufacturing (COM) as a benchmark to assess workpiece quality following fabrication using the Opticam family of machine tools. The commercially available machine tools developed at COM with the American Precision Optics Manufacturer’s Association (APOMA), are currently used in industry to fabricate a wide range of optical materials in spherical, aspheric, plano and most recently micro geometries. Research in the science of optic manufacturing has addressed numerous material and tool related questions, including why under identical machine and tool processing conditions, some glass types grind to a high quality finish, while others reproducibly yield high roughness, high damage surfaces. It is our response to this question which forms the basis of this paper.