Fabrication of 3D perturbation target mould using fast tool servo system

3D non-rational symmetrical perturbation target mould was fabricated using fast tool servo (FTS). The fabrication principle of the perturbation target mould was illustrated and a geometry selection method of diamond cutting tool was put forward which was based on the coordinate transformation technique. Requirements of tool nose radius, rake angle, and clearance angle for turning these surfaces were deducted. A tool nose radius compensation algorithm based on cubic Hermite interpolation was proposed, and the calculating method of interpolation node was also discussed in detail. The simulation result shows that the accuracy of this compensation algorithm is less than 2 nm. Then a sinusoidal grid surface with the wave length of 100 μm and the amplitude of 0.7 μm in both X and Y directions was fabricated on the self-developed diamond turning machine. White light interferometer was adopted to survey the machined surface, and a 2D contour line was extracted with the profile error of 0.31 μm and the surface roughness of 13.3 nm. The measurement results show that the FTS based non-rotational symmetrical turning technique is an effective way to fabricate 3D perturbation target mould.