Investigation of the neutral-solution etch process for refractive SOE antireflective surfaces

Antireflection of optically clear glass used in photovoltaic concentrator refractive secondary optical elements (SOEs) was investigated using the neutral-solution etch process. Test coupons and SOEs made from barium zinc glass, which does not solarize under ultraviolet exposure, were successfully etched at the center-point process variable conditions at 87°C and 24 hours. Reflectance of the plano-plano coupons dropped from 7.7% to 0.8%, with a corresponding increase in transmission from 91.7% to 98.5%. The etching process uses nonhydrofluoric relatively nontoxic chemicals in a low-cost process well-suited for use by photovoltaic system manufacturers during production