Isoplanatism, and high spatial resolution solar imaging

A method is presented allowing one to estimate, in the case of daytime observations, the angle-of-arrival isoplanatic patch size from the measurement of the differential image motion of the solar limb. The experimental results have been obtained using the solar astrolabe of Calern Observatory (CERGA-France). Performing a modelization as proposed by Fried (1977) leads to an explanation of these results by an equivalent atmosphere formed with two impulse turbulent layers corresponding to two different scales for the size of the isoplanatic patch. Finally, the isoplanatism is quantified for speckle interferometry and adaptive optics experiments.