A model is valid only if it represents the actual world. This paper presents several applications developed at CSL to improve or confirm multiphysic modeling, the difficulties of which being the coupling between several physical parameters, mechanics, thermals, optics⋯ The objectives of these applications are to improve, develop analytical modeling guidelines and confirm the models. Generally, the validation processes are carried out on simple test cases. The paper will demonstrate that simple test cases are not necessarily easy to measure, and that correlation with the model is not straightforward. Typical study cases presented are: - Heating of a spherical lens fixed in an aluminium barrel, with the presence of temperature gradients impacting the geometrical deformation of the lens and leading to refractive index gradients. - Samples with glued and bolted connections/junctions that can be encountered in stable structures on spacecraft (Silicon Carbide (SiC) and Titanium (TA6V)). These are measured by a holographic method. - The third system is a YAG laser bar heated by means of a dedicated oven. In the first test bench, the impact of thermo-elastic distortions on the optical performances has been measured using a Fizeau interferometer and compared to OOFELIE::Multiphysics' simulation results. The correlation between experimental and numerical data is discussed. For the second the thermo-mechanical correlations are performed, while for the last test bench preliminary testing results are presented.