Optical aperture synthesis with electronically connected telescopes

TL;DR

This paper demonstrates the first diffraction-limited optical images from an array of independent telescopes connected electronically, enabling high-resolution astronomy without optical links and overcoming atmospheric turbulence limitations.

Contribution

It introduces a novel electronically connected optical interferometry technique that achieves diffraction-limited imaging in visible light using intensity interferometry.

Findings

First diffraction-limited images in visual light from independent telescopes

Successful measurement of second-order optical coherence over 180 baselines

Potential to achieve high-resolution imaging of stellar surfaces and exoplanets

Abstract

Highest resolution imaging in astronomy is achieved by interferometry, connecting telescopes over increasingly longer distances, and at successively shorter wavelengths. Here, we present the first diffraction-limited images in visual light, produced by an array of independent optical telescopes, connected electronically only, with no optical links between them. With an array of small telescopes, second-order optical coherence of the sources is measured through intensity interferometry over 180 baselines between pairs of telescopes, and two-dimensional images reconstructed. The technique aims at diffraction-limited optical aperture synthesis over kilometre-long baselines to reach resolutions showing details on stellar surfaces and perhaps even the silhouettes of transiting exoplanets. Intensity interferometry circumvents problems of atmospheric turbulence that constrain ordinary interferometry. Since the electronic signal can be copied, many baselines can be built up between dispersed telescopes, and over long distances. Using arrays of air Cherenkov telescopes, this should enable the optical equivalent of interferometric arrays currently operating at radio wavelengths.