Influence of Nose Radius on Surface Integrity in Ultra-precision Cylindrical Turning of Single-crystal Calcium Fluoride

Optical micro-resonators attract interests as essential components to develop optical signal processing circuits which can reduce energy loss. Single-crystal calcium fluoride (CaF2) could be the most suitable material from a viewpoint of optical property. To satisfy high form accuracy and surface roughness, ultra-precision cylindrical turning (UPCT) is a feasible fabrication process. In previous research, it was indicated that the tool with sharper nose radius could make UPCT more stable and reduce subsurface damage. In this study, the tool with much smaller nose radius 0.01 mm was applied, then, the influence on surface integrity was investigated by TEM observation.