Fig. 1
From: All-Dielectric Metasurface Lenses for Achromatic Imaging Applications
a Schematic diagram of the structural unit made of Si and CaF2 substrate. b Schematic diagram of the metalens. c The relationship between the focal length and the wavelength of a lens with a fixed phase distribution. d Causes of chromatic aberration: different incident positions of light lead to different focusing positions after passing through the lens. e Principle of fixed phase and remaining phase of achromatic metalens