Fabrication of Antireflective Subwavelength Structure on Spherical Glass Surface Using Imprinting Process

For the first time, an antireflective structure (ARS) on a convex spherical glass surface was fabricated using an imprinting process. The inverted pattern of the ARS with a 250-nm period was fabricated on a SiC mold with a concave surface using electron beam (EB) direct writing and reactive ion etching. The sample surface height was adjusted to the EB focal position along the mold curvature during the step-and-repeat EB lithography. The imprinted lens with the ARS exhibited surface reflectance of 0.2% at a wavelength of 530 nm and a spherical error magnitude of less than 500 nm.