Felice Casorati and the reception of Gaussian optics in Italy

We analyze the work on geometrical optics by Felice Casorati who contributed to the dissemination of Gaussian optics in Italy. In his approach to Gauss's (1840) Untersuchungen he applied determinants to describe multiple refractions in an optical system and he explored the extension of the theory to cover slightly non-centered optical systems for which he introduced the cardinal line, a straight line that replaces the optical axis in this framework.