Diffractive lensless imaging with optimized Voronoi-Fresnel phase

TL;DR

This paper introduces a novel diffractive lensless imaging system using a Voronoi-Fresnel phase, optimized via a new Fourier domain metric, resulting in improved image quality for compact cameras in diverse conditions.

Contribution

It presents a new design principle and optimization framework for diffractive optical elements, enhancing lensless camera performance with a Voronoi-Fresnel phase pattern.

Findings

Outperforms existing lensless camera designs in image quality.

Demonstrates effective imaging in various lighting conditions.

Provides a practical prototype with 1.6-megapixel sensor.

Abstract

Lensless cameras are a class of imaging devices that shrink the physical dimensions to the very close vicinity of the image sensor by replacing conventional compound lenses with integrated flat optics and computational algorithms. Here we report a diffractive lensless camera with spatially-coded Voronoi-Fresnel phase to achieve superior image quality. We propose a design principle of maximizing the acquired information in optics to facilitate the computational reconstruction. By introducing an easy-to-optimize Fourier domain metric, Modulation Transfer Function volume (MTFv), which is related to the Strehl ratio, we devise an optimization framework to guide the optimization of the diffractive optical element. The resulting Voronoi-Fresnel phase features an irregular array of quasi-Centroidal Voronoi cells containing a base first-order Fresnel phase function. We demonstrate and verify the imaging performance for photography applications with a prototype Voronoi-Fresnel lensless camera on a 1.6-megapixel image sensor in various illumination conditions. Results show that the proposed design outperforms existing lensless cameras, and could benefit the development of compact imaging systems that work in extreme physical conditions.