Modeling light propagation in wave-optical engineering

In wave-optical engineering the propagation of light through an optical system can be simulated by using several physical approximations. Independent of the used method it is necessary to have full access to the complete electromagnetic field information in the desired regions. In this article we firstly go into the question what the required information is to get access to the whole electromagnetic field and as a second step we give some insights into physical modeling accuracy and numerical accuracy which is of high importance to evaluate the quality of the calculated results.