Goos-H\"anchen and Imbert-Fedorov shifts for astigmatic Gaussian beams

In this work we investigate the role of the beam astigmatism in the Goos-H"anchen and Imbert-Fedorov shift. As a case study, we consider a Gaussian beam focused by an astigmatic lens and we calculate explicitly the corrections to the standard formulas for beam shifts due to the astigmatism induced by the lens. Our results show that astigmatism may enhance the angular part of the shift.