A novel high efficiency Reactive Ion Figuring technique based on artificial microporous mask

Abstract

Reactive Ion Figuring (RIF) is a promising technical solution for fabrication of meter-scale aperture optical substrates due to its high efficiency parallel processing and low surface damage feature. However, the existing RIF technique needs multiple cycles of photolithography and etching process which is time-consuming and expensive. An artificial microporous film was designed and fabricated as a mask to perform high efficient RIF process. The location of the artificial microporous is distributed gradually from high-density to the low-density state along the radius according to the law of power aberration, and then fluid simulation was carried out. A designed power aberration was superimposed on a 100 mm aperture quartz substrate in a single cycle of RIF process, proving that the artificial microporous mask is capable of tailoring etching rate distribution. The result shows that the power aberration difference between the designed figure and real fabricating one is around 6 nm, and the reasons behind this were analyzed and discussed. This work demonstrates feasibility of high efficiency RIF based on artificial microporous mask and laid the foundation for future arbitrary surface figuring processes.