Phase-Diverse Speckle Interferometry

Abstract

Imaging extended objects through atmospheric turbulence can be accomplished with stellar speckle interferometry, which requires the collection of many image frames of the same object. The exposure time for each frame must be short enough (≈ 10 msec) that the evolving atmosphere can be regarded as frozen during the exposure. Current stellar speckle interferometric approachs, including Labeyrie’s method, Knox-Thompson, and triple correlation, perform an averaging of the data in the process of individually estimating the Fourier modulus or the Fourier phase of the object. The final estimated object is constructed by combining the Fourier modulus and phase estimates and performing an inverse Fourier transform. In addition, a calibration procedure must be performed using images of an unresolved object through atmospheric turbulence having the same statistics.