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Gravity interferometer looks inside our galaxy


​​​​​​​Leti, a CEA Tech institute, contributed to the development of the Gravity interferometer. The instrument, which is installed at the ESO’s* Very Large Telescope Interferometer (VLTI) in Chile, makes it possible to observe the stars gravitating around the black hole in the center of the Milky Way.​​​​​

Published on 19 September 2016
​The Gravity interferometer, which includes some technology from Leti, could help unlock the secrets of our universe. Optical interferometers function by using several telescopes to provide enhanced angular resolution. This helps achieve greater granularity in images of the night sky. “We had to produce interference fringes combining the light received from the four auxiliary telescopes,” said a Leti researcher. “The images reconstructed from these fringes provide much greater detail than a single telescope can.”

And Leti’s contribution to Gravity? The institute developed the photonic chip found deep inside the instrument. The chip, ma​​de by engraving doped silica deposited on silicon—a technology Leti originally developed for telecommunications applications—, offers a number of benefits. It can recombine the light from the four telescopes on the VLTI network in just a few square centimeters. It is also compact, stable, and accurate. Leti researchers modified and improved the chip for wavelengths of 2 µm to 2.5 µm, the spectral field required for Gravity to operate to specifications.
Initial testing went very well. Ultimately, the interferometer will be able to probe the space-time very near the supermassive black hole at the center of our galaxy as well as in its surrounding environment.

*European Southern Observatory


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