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 SiO

2

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.