Diamond machining of optical functional surface

Functional surfaces enabled by micro-/ Nano-structures have been investigated intensively in recent years. In the previous work, the authors managed to manufacture an optical functional surface on 2D/3D steel surfaces by micro milling. The surface function was to maximize the contrast introduced by the orthogonal textured anisotropic surfaces where the micro ridges worked as a micro mirror array. However, due to the severe tool wear of the mill, the geometry of the micro ridges was not finished perfectly [1]. The present paper reports a new process chain by utilizing diamond engraving to manufacture the same structures on the surface of RSA 905 with high accuracy. The manufacturing of the functional surface was conducted on an ultraprecision CNC machine. A 90° sharp tip tool were used for the shaping of the micro ridges. The tool path was programmed by Matlab and imported to the machine in the .NC format. A data matrix was used as an experimental object to test the optical functionality. Eight flat samples with different combinations of dimensions were produced to determine the machinability of the RSA 905 in terms of contrast generation. The optimal combination was the slope angle of 45° and the pitch of 50 μm. Moreover, the quantitative evaluation of the geometrical dimensions and the contrast of the microstructures was dedicated to the process optimization.