Optimization of Sodium Guide Star Return using Polarization and/or Modulation Control

The research objective of the proposed work is to increase the efficiency of the laser return of a Sodium Guide Star Laser (SGSL) reflected off the sodium layer for increased reliability and applicability of the artificial guide star technique. During Phase I, we will demonstrate the concept of maximizing the SGSL signal returns using numerical simulations that account for the effects of atmospheric turbulence. The simulations will be complemented with laboratory testing of the optics components. The solution will be developed to minimize the effect of the geomagnetic field. The optical beam modulation and polarization control in the laboratory will be attained by using an electro-optics modulator and quarter wave plate on the path of laser delivery and to the return signals. The demonstration of feasibility will be performed for the initial proof of concept and the testing methods at an Air Force SGSL facility. During Phase II, the optical hardware will be built and fabricated based on requirements for the Air Force SGSL facility, followed by on-sky testing to demonstrate improvement in the operational performance of the SGSL system.