Daytime calibration and testing of the Keck All sky Precision Adaptive Optics Tomography System

TL;DR

This paper presents the development of a daytime calibration and testing infrastructure for the Keck All sky Precision Adaptive Optics system, enabling performance assessment of laser tomography algorithms with simulated guide stars and atmospheric conditions.

Contribution

It introduces a new hardware infrastructure for daytime calibration and testing of the KAPA system's tomographic algorithms, including an asterism simulator and upgraded turbulence simulation tools.

Findings

Successful implementation of fiber-coupled light sources for guide star simulation

Enhanced turbulence simulation with adjustable phase screens

Capability to test performance under realistic atmospheric conditions

Abstract

The development of the Keck All sky Precision Adaptive optics (KAPA) project was initiated in September 2018 to upgrade the Keck I adaptive optics (AO) system to enable laser tomography adaptive optics (LTAO) with a four laser guide star (LGS) asterism. The project includes the replacement of the existing LMCT laser with a Toptica laser, the implementation of a new real-time controller (RTC) and wavefront sensor optics and camera, and a new daytime calibration and test platform to provide the required infrastructure for laser tomography. The work presented here describes the new daytime calibration infrastructure to test the performance for the KAPA tomographic algorithms. This paper outlines the hardware infrastructure for daytime calibration and performance assessment of tomographic algorithms. This includes the implementation of an asterism simulator having fiber-coupled light sources simulating four Laser Guide Stars (LGS) and two Natural Guide Stars (NGS) at the AO bench focus, as well as the upgrade of the existing TelSim on the AO bench to simulate focal anisoplanatism and wind driven atmospheric turbulence. A phase screen, that can be adjusted in effective altitude, is used to simulate wind speeds up to 10 m/s for a duration of upto 3 s.