This article describes work undertaken at the University of Bern to model the cavity of a side-pumped crystal laser. The radiation transferred from the pumping diode array to the laser rod was modeled using the non-sequential mode of ZEMAX. The absorbed flux was then transferred to the LASCAD program where it was transformed into a volumetric gain profile, and the subsequent laser modes were predicted. Excellent agreement between predicted and experimentally obtained results was achieved.