Restraint of the mid-spatial frequency error on optical surfaces by multi-jet polishing.

Nowadays, the mid-spatial frequency (MSF) error existing in the optical surface after polishing is still a great challenge for the ultra-precision manufacturing of optical components. MSF error severely deteriorates the performances of optical components such as causing small-angle scattering and reducing imaging contrast. In this paper, multi-jet polishing (MJP) was proposed to restrain the MSF error, whose tool influence function (TIF) was relatively more complicated and adjustable than the TIFs of other tools. The results demonstrated that MJP had a superior ability to reduce the ripple error, and the path spacing and nozzle orientation angle both had a significant effect on the MSF error of the polished surface. The optimization of nozzle orientation angle under different path spacings was conducted to achieve a high surface quality. This study contributes to the ultra-precision manufacturing of optical components, achieving a low MSF error together with high finishing efficiency.