Study On The Generation Of Antireflective Surface By Diamond Turning

As the processing methods of antireflective surface, many kinds of traditional preparation techniques based on Micro- electro- mechanic system (MEMS), laser or reaction ion beam, and the frontier preparation techniques such as Nano-imprinting, chemical synthesis always bring a lot of problems. These techniques often require high equipment cost, long preparation period, and very few materials can be used. In addition, the above techniques can’t product the antireflective microstructure on complex surface. In this thesis, a three degrees of freedom pseudo random cutting method is proposed to break the limitations of above processing methods. This method can machine the surface structure with antireflective function in the form of diamond turning, and can be achieved in a variety of materials and the free curved surface. The diamond tool is controlled actively to do the three degrees of freedom pseudo random movement, under the premise of ensuring surface precision and machining efficiency. In this way, the free curved surface with aperiodic residual structure can be achieved. The main contributions of this thesis can be summarized as follows:(a). The three degrees of freedom pseudo random cutting tool path is proposed. In the thesis, the cartesian coordinate systems are constructed in the workpiece surface and the diamond cutting tool. By adopting the discrete method, the tool touch locations can be achieved as the blade contour and the target surface are tangent, and the constant feed cutting tool path of free- form surface is solved further. Considering the practical movement constraint of diamond tool, a controlled second order processing system is built to handle the pseudo random signal.(b). A novel totally decoupled FTS mechanism with three degrees of freedom is developed. The movement along the x axis and z axis is implemented, according to the principle of differential, and the movement along the y axis is produced by the part in series, independently. The compliance matrix modeling method and the finite element software are adopted to analyze and validate the statics and dynamics performances of the FTS mechanism. The open loop test is toke to achieve the actual performances of the three degrees of freedom FTS mechanism. The obtained strokes in x,y and z directions are 20.8μm,12.2μm and 23.1μm with resolutions of 10 nm, 12nm and 10nm, respectively. By means of the sweeping tests, the resonant frequencies in the three directions are respectively 870 Hz,1030 Hz and 840 Hz, suggesting a practical working bandwidth of about 300 Hz. The smaller open loop step response time proves the fast tracking ability of the mechanism.(c). The cutting experiment and the antireflective contrast test are conducted. Respectively, based on 6061 aluminum, brass, and copper materials, the actual pseudo random cutting experiment is done under the condition of different parameters. Meanwhile, the surface with residual structure is observed under the laser scanning microscope. The antireflective performance testing system is build by CCD analyzer and laser, and then, the antireflective performance contrast test of above surface with residual structure is conducted by the system. The obtained results show that the surface with periodic residual structure has relatively significant antireflective function.