Abstract:
The diffraction limited phase retrieval of a degraded image is an important subject that is being implemented in other branches of physics too, for example, electron microscopy, wavefront sensing, and crystallography. A third-order moment (bispectrum) analysis yields the phase allowing the object to be fully reconstructed. This can be extended from the single aperture speckle interferometry to the multi-aperture long baseline interferometry as well. However, in order to obtain snapshot images of the astronomical sources, many-aperture optical array with arbitrarily diluted apertures is required to be built, what is known as Hypertelescope approach. A major challenge for building such a system is the development of adaptive phasing system. Modified wave sensing techniques such as dispersed speckle analysis are planned to be used with these systems. But development and installation of such advanced methods are not available at present. In such a scenario, speckle mode observations with hypertelescope becomes a viable alternative. A study of speckle techniques with such systems is thus of great interest. This lecture is aimed to describe some of these techniques and methods.
