The use of etched nuclear tracks to create a gradient-index antireflective surface on fused silica was investigated. Fission fragments were used as the nuclear particles. The long-wavelength antireflectivity achieved was broadband but modest, possibly because of large index gradients at the internal and external surfaces. Transmission at short wavelengths was limited by diffuse surface scatter. Laser damage thresholds were high. Residual radioactivity was significant but tolerable for some applications. A theory of the index profile of the porous surface was developed.
Robert W. Hopper, "Broadband reduced reflectivity on silica using etched nuclear tracks," Appl. Opt. 23, 2763-2769 (1984)