Simulations for the optimization of immersion photolithography processes: This report provides the description of the work carried on in the laboratory of the Computational Lithography Group at CEA - Leti in Grenoble. The work consisted in the exploration of the possibilities of a new simulation software for the photolithography process called Dr.Litho and developed at Fraunhofer IISB. This software introduce a new way to implement photlithography simulations. In fact it has not any interface for the user, but he can build a specific script concatenating the Python functions provided by Fraunhofer in order to consider exactly all the aspects of the process he wants to take in to account.