Fig. 3: Fabrication of the 2D spatial differentiator.
From: Compact meta-differentiator for achieving isotropically high-contrast ultrasonic imaging
a Transmission and phase shift of acoustic waves traveling through the phase-modulated unit. Inset: details of the phase-modulated unit. b Discrete phase modulations imparted onto the spatial differentiator mapped to the distributions of resin thickness. c Photograph of the fabricated phase meta-grating. d Transmission and phase shift of acoustic waves traveling through the amplitude-modulated unit. Inset: details of the amplitude-modulated unit. e Discrete amplitude modulations mapped to the distributions of slit width. f Photograph of the fabricated amplitude meta-grating.
