Observation of superresolution in nonisoplanatic imaging through turbulence

The turbulent superresolution effect of a telescope, caused by the focusing properties of a distant turbulent layer, is discussed theoretically and experimentally. This effect is described as follows. Under certain observational conditions the energy-spectrum components of the instantaneous image correspond to the energy-spectrum components of the object that lie beyond the cutoff diffraction limits of the telescope resolution. The analytical expression for the instantaneous image spectrum of an extended incoherent object is found. This expression shows under what conditions the superresolution effect is observed. Short-exposure photographs of a rectangular grating observed through a turbulent layer are obtained. They demonstrate the existence of this effect.