Fig. 3
From: Additive effects of narrowband light and optical defocus on chick eye growth and refraction
Dual-power optical lens. a A schematic diagram showing the dual-power lens (− 10 D/ + 10 D, 50:50). The lens is concentric with alternating rings with + 10 D and − 10 D power. b A schematic diagram showing the two distinct image planes induced by the − 10 D/ + 10 D, 50:50 dual-power lens