Fast Extended Depth of Focus Meta-Optics for Varifocal Functionality

TL;DR

This paper introduces a fast, high-resolution meta-optic with extended depth of focus for visible light imaging, enabling varifocal functionality without moving parts, and demonstrating superior depth range and resolution.

Contribution

The work presents a novel meta-optic design achieving a large depth of focus and high resolution at visible wavelengths, surpassing traditional lenses in speed and functionality.

Findings

Achieved a 250-fold increase in depth of focus compared to standard lenses.

Demonstrated high-resolution imaging (~9.84 μm) across a wide focal range.

Integrated a meta-optic camera module capable of imaging at multiple distances.

Abstract

Extended depth of focus (EDOF) optics can enable lower complexity optical imaging systems when compared to active focusing solutions. With existing EDOF optics, however, it is difficult to achieve high resolution and high collection efficiency simultaneously. The subwavelength pitch of meta-optics enables engineering very steep phase gradients, and thus meta-optics can achieve both a large physical aperture and high numerical aperture. Here, we demonstrate a fast (f/1.75) EDOF meta-optic operating at visible wavelengths, with an aperture of 2 mm and focal range from 3.5 mm to 14.5 mm (286 diopters to 69 diopters), which is a 250 elongation of the depth of focus relative to a standard lens. Depth-independent performance is shown by imaging at a range of finite conjugates, with a minimum spatial resolution of ~9.84{\mu}m (50.8 cycles/mm). We also demonstrate operation of a directly integrated EDOF meta-optic camera module to evaluate imaging at multiple object distances, a functionality which would otherwise require a varifocal lens.