The ion beam figuring(IBF) process can produce high accuracy optical surfaces, but the material removal rate is usually lower than 5nm/s and it usually can’t reduce the surface roughness and the middle frequency. This paper study on material removal characteristic of reactive ion beam figuring(RIBF) for optics mirrors, the RIBF process combines physical and chemical effects to remove material, including physical sputtering, spontaneous chemical etching and simultaneous ion bombardment-enhanced desorption. The experiment results indicated that the RIBF process improved the surface quality for optics mirrors by decreased the surface roughness and the middle frequency, and it increased the removal efficiency compare with the IBF process. The research hopes to establish a combined process of RIBF and IBF, and aim to obtain high removal rate and high accuracy surfaces for complex optics mirrors.
Ion beam figuring (IBF) provides a highly deterministic method for the final precision figuring of optical components. According to the Sigmund sputtering theory, the mass of incident ions is an important factor to the sputtering rate and the optical surface quality. Both Ar+ and Kr+ are alternative ions in IBF, but the mass of Kr+ equals two times that of Ar+. In order to achieve the nanometer and sub-nanometer precision fabrication with IBF, the optical material removal property of Ar+ and Kr+ ions was researched. The bombardment process had been simulated with the software TRIM, and the sputtering yield of Ar+ and Kr+ ions for different incident angles was calculated. Then the removal function experiments on Si were conducted. The simulations and experiments result indicated that Ar+ ion beam achieves higher removal rate at 0° incident angle, but Kr+ ion beam performs more efficiently when the incident angle gets across a critical point.