Research On Plasma Processing And Characterisation Of Optical Component Variation Rules

In ultra-smooth surface processing,the most critical step is the removal of the damage layer.Among the existing ultra-smooth surface processing technologies,contact processing may cause surface and sub-surface damage to the optical components being processed,while non-contact processing has the disadvantages of low processing efficiency and high processing costs.Atmospheric plasma polishing technology offers high processing efficiency and low cost while removing damaged layers.There is great potential for development in optical component processing methods.However,there are currently problems with temperature effects and secondary adsorption for the processing of fused silica that need to be solved.In this paper,these two problems are studied.The applicability of this processing method to the surface processing of metals is also explored.The main research is as follows:1)Two different working modes of arc discharge atmospheric plasma are studied.The method of arc discharging plasma work depends on the pressure of the carrier gas.When the gas pressure is 0.02MPa,the plasma flame has high temperature,and the arc discharge plasma has the characteristics of physical fire polishing;When the reaction gas SF₆is put in and the pressure on the carrier gas is about 0.045MPa,the flame temperature of the plasma decreases,and the SF₆can chemically react with the processing components.2)Study of the dynamics variation rule of temperature distribution on surface of optical elements under physical fire polishing process of atmospheric plasma.The temperature and stress variation on the fused silica surface is studied by simulation with varying working distance and carrier gas pressure.The simulation results show that the working distance and carrier gas pressure are inversely related to the temperature and stress variation on the fused silica surface.By changing process factors such as working distance,carrier gas pressure,working method and increasing water cooling,the variation rule of the change of process factors on the surface temperature effect of four materials such as fused silica,aluminium,aluminium alloy and Si C in the actual processing of atmospheric plasma is summarized.The results of the actual processing experiments are consistent with the simulations,proving that the simulation model is usable and that the addition of water cooling to the processing can effectively suppress the thermal effects generated on the surface of the component.aluminium,aluminium alloys and Si C dissipate heat quickly and are not sensitive to changes in temperature.3)Investigating the effect of different process factors of atmospheric plasma on the removal efficiency of fused silica.Experimental results show that when the processing method is physical fire polishing,the best effect on fused silica removal is achieved at a working distance of 2mm and a carrier gas pressure of 0.02MPa,with a volume removal rate of 0.048mm³/min,and the method is not applicable to aluminium;when the processing method is chemical reaction processing,the best removal effect is achieved at a working distance of 1mm and a gas flow rate of N₂:SF₆=1:1,with a volume removal rate of 56.525 mm³/min for fused silica and 1.018 mm³/min for aluminium,which enables fast and non-destructive removal of fused silica.4)Study of the evolution of the surface properties of aluminium and fused silica during chemical reaction processing in atmospheric plasma.By testing and analyzing the adsorbed material,the rules of mechanical and optical performance changes on the surface of optical components resulting from atmospheric plasma processing are studied.After that,the secondary adsorbed material is removed using small grinding head polishing methods as well as ion beam polishing methods to restore the optical and mechanical performance of the component surface.Based on the results of these studies,it can be concluded that arc discharge atmospheric plasma can achieve efficient non-destructive removal of fused silica optical components as well as aluminium optical components.These research results provide new ideas for the efficient non-destructive processing of fused silica optical elements as well as metallic optical elements.