Numerical simulation of the return photon flux from sodium laser guide star for atmospheric conditions of Siberia
L.A. Bolbasova, S.A. Ermakov, V.P. Lukin
V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, Tomsk, Russia
Keywords: laser guide star, adaptive optics, atmospheric turbulence, telescope, mesospheric sodium
Abstract
Requirements for the elements of adaptive optics systems are largely related to atmospheric conditions at their locations. The primary task is to ensure a photon flux from a sodium laser guide star (LGS) sufficient for the operation of wavefront sensors. One of ways of increasing the photon flux is the use of circularly polarized laser radiation, due to the influence of the Earth's magnetic field on the energy levels of the sodium atom. The geomagnetic field strength at Siberian observatories is 56-58 nT, which is significantly higher than that of any known observatory. Another feature is the low (about 2 × 1013 atoms/m2) density of sodium atoms in the mesosphere in summer. The article presents the results of numerical simulation of the return photon flux from a sodium LGS for atmospheric conditions in Siberia. Approaches to increasing the LGS brightness are considered.
|
