Kyohoon Ahn: Commissioning a non-linear curvature wavefront sensor at the Subaru Telescope for the AO3k system

Tuesday, 27 February 2024 2:30 p.m. — 3:30 p.m. MST

Gemini North Hilo Base Facility | 670 N A’ohoku Place Hilo, Hawaii, 96720, USA

Gemini North Talks
Kyohoon Ahn (Subaru Telescope)

The Subaru Telescope recently started the upgrade of the facility adaptive optics (AO) system to improve the AO performance and to enable the technical demonstration toward the future wide-field ground-layer AO (GLAO), which is known as the ULTIMATE-Subaru project. The upgrades include a new real-time control system, laser guide star (LGS) system, deformable mirror (DM) with ~3000 actuators, and wavefront sensors (WFSs). After these upgrades, The facility AO system (AO188) will be upgraded to the AO3k system. We also anticipate these upgrades to provide an improved Strehl ratio for all downstream instrumentations at the Nasmyth platform of the Subaru Telescope.

This presentation will primarily focus on commissioning a non-linear curvature WFS (nlCWFS), which is a new visible WFS for the AO3k system, among the AO upgrade activities. We will first introduce the motivation and new concepts for this work. We will present the integration of the nlCWFS at the Nasmyth platform of the Subaru Telescope and closed-loop performance with an internal source. We also will highlight the first on-sky results of the nlCWFS, and this work will be the first on-sky demonstration of the nlCWFS with an 8-meter class telescope to our best knowledge. We will conclude by comparing the AO performance before and after the AO upgrade and with future works for implementing the non-linear wavefront reconstruction algorithms.

For Zoom connection information, please contact Emanuele Paolo Farina (

Back to Gemini north talks.