Ultra-precision process of soluble optical crystal considering non-aqueous shear-thickening polishing method

This paper proposes a non-aqueous shear-thickening polishing (NA-STP) method specifically designed for soluble optical crystal materials. NA-STP uses a non-aqueous polar solvent as the dispersion medium, avoiding the corrosion of soluble crystals by water particles. Using potassium dihydrogen phosphate (KDP) crystals as a case study, various formulations of non-Newtonian fluid polishing slurries were prepared, and the effects of different polar dispersing media, dispersed phases, and surfactants on the rheological properties of the polishing slurries and the processing outcomes on KDP crystals were investigated. The study also examined the influence of key process parameters including slurry velocity and impact angle on the surface quality and material removal rate of KDP crystals. The research achieved a nearly damage-free optical surface with a surface roughness of R_a 1.72 nm on KDP crystals, presenting a novel technological approach for the ultra-precision machining of water-soluble optical crystal materials, as exemplified by KDP crystals.