Influence of stratospheric turbulence on infrared imaging

摘要

We introduce a model for the power spectrum of stratospheric turbulence that is based on data from in situ measurements and on results of the theory of saturated internal gravity waves. We then study the effect of that stratospheric turbulence has on the scintillation, the coherence of starlight, and on the degradation of star image. It is shown that because the stratospheric phase structure function is approximately quadratic over distance comparable with the aperture of a large telescope, stratospheric turbulence does not significantly degrade short-exposure images of star but does degrade long-exposure ones. The influence of stratosphere on star image degradation is more important in the IR than in the visible range because of the specific dependence of the stratospheric coherence radius on the light wavelength. Star image motion and blurring are determined by different characteristics of the atmosphere and cannot be explained solely on the basis of Kolmogorov model. The modified astronomical imaging theory predicts greater improvement in resolution due to tilt removal than a conventional theory.