The potentiality of refractive wavefront correctors

Multi Conjugated Adaptive Optics is, in principle, able to enlarge arbitrarily, the compensate Field of View through the use of multiple correctors conjugated to different portions of the atmosphere. However such enlargement is limited, in practice, to a low number enhancement. We recognize that this is mainly due to the choice of a deformable mirror as a correcting device. We show through a simple optical analysis that the introduction of wavefront corrector working in transmission would made a number of Multi Conjugated Adaptive Optics systems for large telescopes with the aim of compensating a Field of View significantly larger than the isoplanatic patch feasible, while their implementation with deformable mirrors would be extremely impracticable. We discuss the history and the potentiality of these kind of devices pointing out that even the current nomenclature while denoting generically the term of  “wavefront sensor” adopts the term “deformable mirror” for what could be generically named as a “wavefront corrector”  contributing to the lack of efforts into their potential developments. A successful refractive corrector could open Adaptive Optics capabilities that are now unthinkable and has the potential to revolutionize, with simpler retrofitting capabilities.