ESO’s ELT ‘MORFEO’ instrument passes preliminary tests...

09 Mar 2023

...while Rensselaer's ultrafast laser method advances satellite-earth links; enabling FSO comms even through rough weather.

MORFEO, an upcoming instrument for ESO’s Extremely Large Telescope (ELT), has passed its preliminary design review. MORFEO’s adaptive optics system will use special sensors to measure the blurring effects of the Earth’s atmosphere, correcting them with deformable mirrors.

This will allow astronomers to get an unprecedented view into the universe, offering detailed observations of distant galaxies and stars at the centre of the Milky Way.

Ground-based telescopes like ESO’s Extremely Large Telescope can only work to their full potential with adaptive-optics systems that correct for the turbulence of the Earth’s atmosphere, which makes stars twinkle and blurs our view of the cosmos.

In addition to sophisticated systems, including a large deformable mirror, that correct for atmospheric distortions as light travels through the ELT, the telescope will also have MORFEO, the Multiconjugate adaptive Optics Relay For ELT Observations; previously known as MAORY.

MORFEO will work with the ELT’s camera, Multi-AO Imaging CamerA for Deep Observations (MICADO), which requires very stable and sharp images to precisely measure the positions, brightness, and motions of stars, one of its scientific goals.

By re-imaging the light coming from the telescope and further correcting for distortions, MORFEO will enable MICADO to capture perfect images across its large field of view in the near-infrared. This will allow the ELT to observe distant galaxies and stars at the centre of the Milky Way in unprecedented detail.

To achieve this, MORFEO will use deformable mirrors and other state-of-the-art systems, such as the ELT’s laser guide stars, to correct for turbulence in different layers of the Earth’s atmosphere. These systems will help MORFEO obtain a 3D map of atmospheric turbulence, and correct it in the images obtained by MICADO.

MORFEO will be one of four instruments on the ELT when it is first used to take astronomical images after construction is finished later this decade. When operational, the ELT will tackle the biggest astronomical challenges of our time, from tracking down potentially habitable Earth-like exoplanets to studying the very first stars and galaxies.

The telescope, in particular its sophisticated adaptive-optics systems, builds on and continues ESO's 60-year success story of international collaboration in astronomy and sharing resources and expertise.

Rensselaer researcher breaks through the clouds

Troy, New York-based Rensselaer Polytechnic Institute’s Moussa N’Gom, assistant professor of physics, applied physics, and astronomy, has devised a method to make communications between satellites and the ground more effective whatever the weather.

In research recently published in the Journal of Applied Physics, N’Gom and his team used ultrafast, femtosecond lasers to cut through the clouds and rain that commonly cause losses in free-space optical communication.

“The lasers we use are so energetic that they change the environment in which they propagate,” said N’Gom. “The environment starts to change the laser that is changing it, and they have a light-matter interaction. It becomes a cascading effect that creates a long filament of light.”

The filament of light is accompanied by a shockwave, along the lines of a sonic boom. The laser filament propagates through clouds and the accompanying shockwave clears the space around the filament, providing an open pathway for visible light. N’Gom uses structured light, in the form of a spiral with a hole at its center, to propagate through the pathway.

“The Laguerre–Gauss beam travels through this empty space without interacting with the filament and is unobstructed by the clouds,” said N’Gom. “Normally, light travels in one, flat wave, but the light we create travels in a spiral. Imagine it like curling a flat piece of paper with scissors.”

On top of facilitating transmission through clouds, the spiral shape of the light also allows for more information to be transmitted. The method presents a significant advance for FSO, which already has substantially higher capacity than radio frequency communication. Previous attempts to overcome the persistent obstacle of rain and clouds required substantial energy, large investments, or were less effective.

“Dr. N’Gom’s innovative research shows how to overcome a fundamental barrier in free-space optical communication,” said Curt Breneman, dean of the Rensselaer School of Science. “I expect free-space optical communication technology of this type to enable hyper-speed secure worldwide quantum communications.”