离子束加工光学镜面的材料去除特性

Material removal property in ion figuring process for optical components

分析了离子束加工光学镜面的材料去除效率、加工损伤厚度以及表面热效应等材料去除评价指标。基于Sigmund溅射理论,分析了此三个评价指标与离子入射角度和离子能量等加工参数的关系,建立了相关模型。以石英玻璃为例,利用TRIM软件仿真离子溅射过程,分析理论模型各参数,具体研究了三个评价指标与离子能量和入射角度的关系。结果表明:材料去除效率随离子能量的增大而缓慢增大,随入射角度增大而显著增大,60°时的去除效率约为0°时的4.5倍;加工损伤厚度随离子能量增大而近似呈线性增大,随入射角度增大而减小;热效应随离子能量近似呈线性增大,而随入射角度增大而减小。因此,离子束加工工艺过程中,应尽量增大离子束入射倾角来同时提高这三方面的指标。

The material removal property with three important performance factors, the material removal efficiency, depth of the sub-surface damage and thermal effect, in the ion figuring process was analyzed. Based on the Sigmund sputtering theory, the relation models of these three factors with respect to ion energy and incident angle were established. The sputtering process of SiO2 bombarded by Ar^＋ was simulated with the software TRIM, and the parameters of the above theory models were synthesized with the simulated data. Then the relationships among the three factors and the two process parameters were researched by the theory models. The models and simulation results indicate that the removal efficiency increases slowly with the ion energy and fast with the incident angle in some range, the removal efficiency at 60° is about 4.5 times as high as that at 0°; the depth of sub-surface damage increases with the ion energy linearly but decreases with the incident angle; the thermal effect increases with the ion energy linearly approximately but reduces with the incident angle. Therefore, in order to improve the three performance factors at the same time, a larger incident angle should be the best choice.