Improving the performance of single point diamond turning surface with ion beam figuring

Single point diamond turning (SPDT) can directly produce high precision optical parts, but some regularity micro structure in residual surface, and turning processing characteristics limit the surface quality to further improve. Ion beam figuring (IBF), as the last process of optical processing, can remove certain mid and high frequency errors, improve the surface performances without destroying their forms. Therefore, it is proposed to combine SPDT and IBF to manufacturing ultra-high precision surface. Two samples of diamond-turned sphere aluminum mirror were used in this experiment. One samples with surface PV and RMS 226 nm and 12.6 nm decreased to 113 nm and 7.7 nm after ion beam figuring, another sample was improved in the same degree, and the turning marks is removed with surface roughness decreased to 2.8 nm from 3 nm. The experimental results indicate that IBF can remove the turning marks and improve the surface precision in a certain range without destroying the surface form.