Single-dish Diffraction-limited Imaging

Abstract

Turbulence is a state of the flow of a fluid in which apparently random irregularities occur in the instantaneous velocities, often producing major deformations of the flow. In the terrestrial atmosphere, large-scale temperature inhomogeneities caused by non-uniform heating of different portions of the Earth’s surface produce random micro-structures in the spatial distribution of temperature causing the fluctuations in the refractive index of air. The large-scale refractive index inhomogeneities are broken up by non-uniform winds and convection, spreading the scale of the inho-mogeneities to smaller sizes, until thermal molecular dissipation dominates. The disturbance takes the form of distortion of shape of the incoming wavefront and affects the intensity distribution, thereby introducing phase fluctuations. This leads to blurring of the image.