Interleaving and sparse random coded aperture for lens-free visible imaging

Abstract

Coded aperture has been applied to short wavelength imaging (e.g., gamma-ray), and it suffers from diffraction and interference for taking longer wavelength images. This paper investigates an interleaving and sparse random (ISR) coded aperture to reduce the impact of diffraction and interference for visible imaging. The interleaving technique treats coded aperture as a combination of many small replicas to reduce the diffraction effects and to increase the angular resolution. The sparse random coded aperture reduces the interference effects by increasing the separations between adjacent open elements. These techniques facilitate the analysis of the imaging model based only on geometric optics. Compressed sensing is applied to recover the coded image by coded aperture, and a physical prototype is developed to examine the proposed techniques.