Towards optimization of pulsed sodium laser guide stars

TL;DR

This paper investigates pulsed sodium laser guide stars, demonstrating their potential to match or surpass continuous-wave systems in photon return, and explores optimal laser formats for improved adaptive optics performance.

Contribution

It introduces a time-dependent analysis of sodium fluorescence for pulsed lasers and evaluates their advantages over continuous-wave systems in LGS applications.

Findings

Pulsed LGS can achieve photon returns comparable to CW systems.

Optimal pulsed laser formats depend on sodium fluorescence dynamics.

Simulation predictions align with existing LGS measurements.

Abstract

Pulsed sodium laser guide stars (LGS) are useful because they allow for Rayleigh blanking and fratricide avoidance in multiple-LGS systems. Bloch-equation simulations of sodium-light interactions show that these may be able to achieve photon returns nearly equal to, and in some cases greater than, what is seen from continuous-wave (CW) excitation. In this work, we study the time-dependent characteristics of sodium fluorescence, and investigate the optimal format for the new fiber laser LGS that will be part of the upgraded adaptive optics (AO) system on the Shane telescope at Mt. Hamilton. Results of this analysis are examined in the context of their general applicability to other LGS systems and the potential benefits of uplink correction are considered. Comparisons of simulation predictions with measurements from existing LGS are also presented and discussed.