A conventional biocular has been designed to magnify the image obtained in a cathode ray tube display. Problems of weight and alignment were solved by using four lenses of which one is an axial gradient lens. This lens reduces distortion, field curvature, and angular blur.
© 1985 Optical Society of America
Eli Atad, "Optical design of a gradient-index biocular," Appl. Opt. 24, 4297-4299 (1985)