Atmospheric pressure plasma polishing (APPP) is a precision machining technology used for manufacturing high quality optical surfaces.The changes of surface modulus and hardness after machining prove the distinct improvement of surface mechanical properties.The demonstrated decrease of surface residual stresses testifies the removal of the former deformation layer.And the surface topographies under atomic force microscope (AFM) and scanning electron microscope (SEM) indicate obvious amelioration of the surface status,showing that the 0.926-nm average surface roughness has been achieved.
We investigate reactive fluorine atom spectroscopic characterization in atmospheric pressure of He/SF 6 plasma using atomic emission spectrometry. As input radio frequency (RF) power levels are raised from 140 to 220 W, the emission spectra of 685.60 (3p4D→3s4P transition) and 739.87 nm (3p4P→3s4P transition) increase significantly. Moreover, an optimal value of SF 6 volume concentration in the production of fluorine radicals, which is 0.8% is achieved. Addition of certain amounts of O 2 into He/SF 6 plasma results in the promotion of SF 6 dissociation. Emission intensities of fluorine atoms show the maximum at the O 2 /SF 6 ratio of 0.4.
