NAOMI (New Adaptive Optics Module for Interferometry) 

NAOMI is the Adpative Optics that are used with VLTI/ATs. It consists in four sets of deformable mirrors with 241 actuators , 4x4 Shack-Hartman sensors and SPARTA Real Time Control operating in the visible (Gaia G band filter). By delivering a higher and more stable Strehl ratio during turbulent conditions, the NAOMI systems allow a more robust fiber coupling in the VLTI instruments which translate into a higher sensitivity and precision in the interferometric data. NAOMI can also provide chopping capabilities up to 4 Hz to subtract the thermal background seen by MATISSE. More detailed information can be obtained from these two publications:

Gonté et al., The Messenger, vol. 177,19-23

Woillez et al., 2019, A&A, 629, A41

GPAO  (GRAVITY PLUS ADAPTIVE OPTICS) 

GPAO is a high-order laser-assisted adaptive optics system that greatly enhances the sky coverage of VLTI/UTs. Since October 2024, each UT Coudé is equipped with a new adaptive optics system called GPAO developed by the GRAVITY+ consortium. The visible Natural Guide Star (NGS) mode of GPAO replaces entirely the former visible MACAO system: wavefront sensor, corrective optics and Real Time Control (RTC). GPAO uses ERIS (Davies et al. 2023) Adaptive Optics as a baseline. It consists in a 43x43 magnetic-actuator driven ALPAO Deformable Mirror placed on a gimbal mount. This sends the corrected wavefront to the Coud\'{e} room located below the telescope. The RTC platform is SPARTA upgrade (ESO). The NGS-VIS wavefront sensor has a 40x40 High Order Shack-Hartmann (SH) Lenslet Array and a Low Order  4x4 SH Lenslet Array allowing AO correction within the full Field of View. Detectors are sub-electron read-noise OCAM2 cameras running at 2kHz (made by First Light Imaging). GPAO now also integrates the near-infrared wavefront sensor GPAO-IR (previously known as CIAO) for VLTI objects that require a red NGS. Following a significant UT infrastructure upgrade, new laser guide star (LGS) facilities on UT1, UT2 and UT3 were commissioned and completed the GPAO systems. More detailed information can be obtained from these two publications:

The GRAVITY Collaboration, The Messenger, vol. 189, 17-22

The GRAVITY Collaboration, A&A, 2025, in press