Reflective grating interferometer: a folded reversal and sharing wave-front interferometer

The reflecting grating interferometer is a folded and reversal wave-front interferometer sensitive only to asymmetrical aberrations such as third-order come. The RGI can isolate and evaluate coma both in nearly collimated and in noncollimated beams. We propose a RGI with a different optical configuration that includes a lateral shearing in addition to folding and reversal operations. Optical path difference equations for interpreting interferograms and numerical simulations are presented to show how the interferometer works in the shearing configuration. Its potential applications are described and discussed.