Abstract
Kilometric-scale optical baselines are required for imaging features across stellar disks. Ground-based intensity interferometry is insensitive to both atmospheric turbulence and to imperfections in telescope optics, permitting long-baseline observations even at short optical wavelengths. Its required large flux collectors are becoming available as arrays of atmospheric Cherenkov telescopes set up for studying energetic gamma rays. High-speed detectors and digital signal handling enable very many baselines to be synthesized in software between numerous pairs of telescopes in a digital revival of a technique once pioneered by Hanbury Brown & Twiss.
