Lunch Session LS1  29 June 2020

Towards optical VLBI with Hanbury Brown and Twiss

News: For informal discussion please come to the virtual 'Hanbury Lounge' on zoom.
Meeting ID 877-923-353 and pw 314159
Times: 16:00 CEST each day of the meeting

Aims and scope

As the world saw in 2019, mm-wave VLBI has achieved a resolution of 20 micro-arcsec or 0.1 nano-radians. Could this be matched at optical wavelengths?

Hanbury Brown and Twiss provided a proof of concept already in the 1950s when they invented optical intensity interferometry. This technique does interferometry with narrow-band but incoherent light. Because coherent light is not involved, optical-quality mirrors are not needed, the atmosphere is not a hindrance, nor is there any in-principle limit on baselines. The difficulty lies in getting sufficient signal-to-noise. Hanbury Brown and collaborators, using the photon detectors of the 1960s, could only observe about 30 bright stars.

In the last few years several groups have been reviving the HBT technique using modern detectors, and there are ambitious plans for intensity interferometry over km-long baselines, which if successful would achieve resolutions comparable to the Event Horizon Telescope, but in visible light.

This session aims to bring together researchers building intensity interferometers and attract experts on possible new applications.


  • Selected novel science cases for Intensity Interferometry
  • Intensity interferometry observations with the MAGIC Cherenkov telescopes
  • Instrumentation for Stellar Intensity Interferometry: a functional prototype with the VERITAS Stellar Intensity Interferometer.
  • HBT 2.0: intensity correlations on P Cygni
  • Measurement of the second-order correlation of visible light from Vega in photon counting and future prospects
  • Stellar Intensity Interferometry within a fully digitising camera of the SST-1M project
  • A stellar intensity interferometer for Imaging Air Cherenkov Telescopes
  • Towards a Polarisation Prediction for LISA via Intensity Interferometry

Invited speakers

Scientific organisers

Dainis Dravins (Lund Observatory), Prasenjit Saha (University of Zurich), and Olaf Wucknitz (Max-Planck-Institut für Radioastronomie)


psaha @

Updated on Fri Jun 19 11:53:51 CEST 2020