200mm Optical synthetic aperture imaging over 120 meters distance via Macroscopic Fourier ptychography

TL;DR

This paper introduces a modified Fourier ptychography technique using divergent illumination to achieve high-resolution imaging over 120 meters, significantly surpassing previous distance limits and improving synthetic aperture size.

Contribution

It proposes a novel approach to extend macroscopic Fourier ptychography for long-distance imaging by modifying the far-field condition and optimizing reconstruction algorithms.

Findings

Achieved 200mm synthetic aperture at 120m distance

Expanded imaging distance from 10m to 120m

Improved resolution by over four times compared to single aperture

Abstract

Fourier ptychography (FP) imaging, drawing on the idea of synthetic aperture, has been demonstrated as a potential approach for remote sub-diffraction-limited imaging. Nevertheless, the farthest imaging distance is still limited around 10 m even though there has been a significant improvement in macroscopic FP. The most severely issue in increasing the imaging distance is field of view (FoV) limitation caused by far-field condition for diffraction. Here, we propose to modify the Fourier far-field condition for rough reflective objects, aiming to overcome the small FoV limitation by using a divergent beam to illuminate objects. A joint optimization of pupil function and target image is utilized to attain the aberration-free image while estimating the pupil function simultaneously. Benefiting from the optimized reconstruction algorithm which effectively expands the camera's effective aperture, we experimentally implement several FP systems suited for imaging distance of 12 m, 65 m and 120m with the maximum synthetic aperture of 200 mm. The maximum synthetic aperture is thus improved by more than one order of magnitude of the state-of-the-art works from the furthest distance, with an over fourfold improvement in the resolution compare to single aperture. Our findings demonstrate significant potential for advancing the field of macroscopic FP, propelling it into a new stage of development.