Atmospheric turbulence profile estimation using a single laser guide star

摘要

In this paper a technique for estimating a range resolved atmospheric turbulence profile statistics is investigated that uses a single laser guide star in conjunction with a Shack-Hartmann wave front sensor. The technique utilizes the fact that light passing through different layers to different wave front sensor apertures in the wave front sensor array will pass through different regions of the atmosphere whose relative distance varies as a function of distance from the laser guide star. This causes the correlation between tilts measured by each pair of wave front sensors in the array to measure different weighting of the power of the index of refraction variation in the turbulence profile as a function of altitude. This variation allows a set of linear equations to be constructed that can be solved to yield the C_n~2 profile. This general technique has been utilized to estimate the turbulence profile using multiple sources and apertures. This paper suggests the possibility of extending the technique to be used with a set of hardware frequently encountered in adaptive optics systems. The application of this technique at many astronomical telescopes would simply involve an additional signal processing function with no change to the optics or other hardware. Simulations performed in this paper serve to demonstrate the degree to which a single guide star could be used with an array of wave front sensors to recover the turbulence profile.