For the development of the light source and reactor setup simulations, geometric representations of the light sources and reactors were made based on the measured dimensions. These representations, including material properties, were modeled in COMSOL Multiphysics 5.4. For the radiometric raytracing calibration, the UV sensor used for the experimental data was recreated as well. The simulations were conducted using the Geometric Optics module with the time-dependent solver, with time-stepping calculated with the generalized alpha algorithm. Moreover, the solution of the linear system of equations proceeded iteratively with the GMRES method. Here the relevant release information (direction vector, emission profile, ray properties, and total power) could be defined. The irradiated surface (either the sensor or reaction mixture) was defined as an accumulator that freezes the incident ray and deposits the ray's power onto the surface. This allowed us to obtain the optical output power of the light source, through calibration of the virtual received intensities to the experimental quantities, as well as estimate the emission profile at the same time (e.g., Lambertian, conical, or hemispherical emission), by minimizing the error in intensity distribution differences. Both mesh dependency and result convergence studies as a result of simulation size have been done (see Supplementary Information).