A slicer mirror is a complex surface composed by many tilted and decentered mirrors sub-surfaces. The major difficulty to model such a complex surface is the large number of parameters used to define it (tilts, curvatures, decenters for each sub-surface). Making use of the User-Defined Surface (UDS-DLL) Zemax capability, we are able to easily consider the set of sub-surfaces as a whole surface. Please when using this DLL, thank author and refer to the article: http://fr.arxiv.org/abs/physics/0510174