In the semiconductor industry, there is an increasing demand for thermal stability to optimize the performance of lithography machines. This results in a need for computational tools that are able to accurately model radiation heat transfer, with the ability to include specular and angle-dependent reflection and take the influence of the polarization into account. An analytical approximation model of a square passage is formulated, that includes angle-dependent reflecting surfaces and the influence of polarization. These problems can be used as benchmarks to verify radiation modeling tools, e.g., comsol. The tool is validated by modeling an experiment and comparing the numerical results with the experimental data. The impact of angle dependency and polarization on the heat flux through passages is discussed.