Graded porous glasses for antireflective applications formed by chemical treatment

Porous glass surface can be achieved by the neutral-solution etch process, which has been reported to be effective in suppressing light reflection from glasses. Samples of a commercial borosilicate glass were submitted to a static aqueous corrosion at 87 degrees C for several hours for introducing porosity on glass surface. Morphology, composition and optical properties of the surface, which were analyzed by scanning electron microscope (SEM), energy dispersive spectrum (EDS) and spectrometer, can be controlled by changing both the neutral-solution concentration and etching time. The results show that the transmittance of glass substrate can be improved after chemical treatment, and the laser-induced damage threshold of graded porous glass is much higher than that of antireflective coatings. The SEM and EDS results revealed a significant corrosion process in the solution, and determined the relationship between the graded porosity and refractive index of glasses. (C) 2012 Elsevier B.V. All rights reserved.