Fabrication of anti-reflective surfaces by 3-DOF fast tool servo diamond turning

Surface reflection existed in most optical elements that reduce the light transmission quality and bring down the optical system performance. Freeform optics is the key element in modern optics that it is strongly necessary to improve the anti-reflective performance. Therefore, the design and fabrication of anti-reflective freeform surfaces attract many researchers' attention, and this paper proposed a 3-DOF pseudo random turning method for the fabrication. The core idea is that three-processed random signal is coupled to freeform surface normal turning toolpath, and the new toolpath takes the diamond tool do micro-vibration in three directions in the turning process to break down the periodic tool mark residual structure. This method is implemented by a 3-DOF fast tool servo (FTS) system. The cutting results show that the new toolpath can disrupt the periodic turning residual structures which have the anti-reflective property, and higher hardness material is conductive to the formation of surfaces microstructure. Better anti-reflective surfaces can be obtained by optimizing tool geometric parameters and cutting parameters.