Studies of a mesospheric sodium guidestar pumped by continuous-wave sum-frequency mixing of two Nd:YAG laser lines in lithium triborate

摘要

Mesospheric sodium guidestar radiance is plotted vs. wavelength, fasor power, fasor polarization and date. Peak radiance for circular polarization was about 7000 photons/sec/cm2 (V1 magnitude = 5.1) for 30 watts of pump power in November of 2005. Pumping with circular polarization at high power produces about 2 times more return than linear polarization. Pumping D2a at high power produces about 12 times more return than pumping D2b. A lidar equation is used to determine column density. Estimated maximum possible guidestar radiance is about 3 times greater than measured values. Guidestar radiance may be saturated by atoms becoming trapped in F'=1 and atomic recoil.