PIONIER: combining 4 telescopes of the very large telescope interferometer using a photonics beam combiner

PIONIER (Precision Integrated Optics Near-infrared Imaging ExpeRiment) is a visitor instrument [1] that performs the interferometric beam combination in the near infrared of the light delivered by the 4 main telescopes (8m) or auxiliary telescopes (1.8m) of the VLTI on the ESO Paranal site (Chile).