Indoor characterization of secondary optical elements

We report about the indoor characterization of secondary optical elements (SOEs) at Fraunhofer ISE. The concentration profile at the SOE's exit aperture under various illumination conditions is obtained by imaging a transmissive diffuser via a CCD camera. This method is very fast, easy and can be used to identify deviations from designed shape of the SOEs. To compare different samples quantitatively a simulation model was set up. In this paper we describe the experimental setup, present results for different refractive SOEs made of glass and estimate the loss in a Fresnel lens based CPV system due to the identified errors.