Atmospheric turbulence profile plays an important role in designing and operating adaptive optics (AO) systems with multiple laser guide stars. To obtain representative free atmospheric profiles and resolved ground layer profiles for future AO systems at the Subaru Telescope, we are conducting the SHARPEST (Shack-Hartmann Atmospheric tuRbulence Profiling Experiment at the Subaru Telescope) project. In this project, we develop a turbulence profiler comprising two Shack-Hartmann (SH) sensors to observe a pair of bright stars through the Subaru Telescope with high spatial sampling by 2cm subapertures. We perform two main analyses on the SH spot data: variance analysis on the spot scintillation for free atmospheric profiles, and on the spot slope for ground layer profiles. Through the three previous engineering observations, we establish a method to constrain the turbulence profile as well as the total seeing and the wind profile by analyzing data from the SH sensors. The free atmospheric profiles reconstructed by the two independent SH sensors show good agreement and are also consistent with simultaneous measurements by another profiler except for turbulence strength at ∼1km, which might be explained by an overestimation problem of scintillation-based profilers. The wind profiles show good consistency with the direct measurements by a rawinsonde. The ground layer profile results, obtained by combining data from the two SH sensors, suggest that turbulence is concentrated in the range up to ∼50m above the primary mirror. As a comparative measurement for the dome seeing, we are currently planning to install AIRFLOW, a small local turbulence sensor inside the dome.
We present the current status of the ULTIMATE-Subaru Tomography Adaptive optics Research experimenT (ULTIMATE-START) project, an upcoming laser tomography adaptive optics (LTAO) system on the Subaru telescope. The main goal of this project is to realize high Strehl ratio AO correction not only in near-infrared bands but also in visible bands above 600 nm. Our LTAO system will be operated with four 32 × 32 Shack Hartmann wavefront sensors (SH-WFSs) and four laser guide stars (LGSs). The LTAO WFSs will be installed behind AO188, which is the current AO system on the Nasmyth platform of the Subaru telescope. We will use the low-order WFS and DM of AO188 for Tip-Tilt measurements with a natural guide star (NGS) and wavefront correction. The DM of AO188 will be upgraded to a 3228 element DM. Assembling of the LTAO WFS system has completed in 2022. Currently WFS data acquisition and tomographic wavefront (WF) estimation testing are underway. We also performed test observations of a prototype single SH-WFS unit with a NGS and LGS with the Subaru telescope. A new laser launching system has been installed. A single LGS is under on-sky performance verification for the open-use observations, and four LGS system, which can make an asterism with 10-40 arcsec diameter, will be installed in 2022. The first light of the entire LTAO system is planned in early 2023.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.