2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/9596It is proved that the field of a gravitational lens induces no rotation in the polarization vector of electromagnetic radiation, in agreement with the previous literature, but with a different approach. The result is generalized to the case of less conventional gravitational lenses (static cosmic strings and gravitational waves).8 pagesAstrophysicstext