Physical optics light propagation through components with measured refractive, diffractive and hybrid surface profiles

The optical function generated by a real optical system differs typically from the simulation result. Differences are caused for example by light source radiation tolerances, by alignment tolerances or deviations of the fabricated surfaces from ideal surfaces. In order to simulate the influence of surface deviations of a real system on the optical function it is required to import surface measurement data into optics software. These measurement data contain often the profile height at discrete data points. In order to do a simulation it is required to import these data into optics software and to create a continuous surface profile with the help of a suitable interpolation method. Surfaces deviations can have high spatial frequencies. This requires often a simulation of light propagation including diffraction, interference and vectorial effects. In general different models of light propagation are needed depending on the required physical simulation accuracy. The authors show the modelling of refractive, diffractive and hybrid surfaces from discrete data sets. It turns out that for the description of these different surface types different interpolation methods are required to allow an efficient construction of a continuous surface from measurement data. In addition the authors introduce the Field Tracing concept that allows using different light propagation models from geometrical optics to rigorous. It enables the adjustment of the physical modelling accuracy in every part of an optical system. The simulation of the effect of measured surface deviations will be demonstrated on the examples of a refractive beam shaping element and of a diffraction grating. It will be shown that it is important to include diffraction and interference effects in the simulation.