Characterization of anti-reflective coatings on a spherical lens secondary optical element

A method for characterizing an anti-reflective coating (ARC) on a small spherical object like a spherical secondary optical element in a micro-CPV system has been implemented and validated, concerning reproducibility and uncertainties. This consisted of preparing and measuring a single layer of densely packed AR coated spheres in a photo spectrometer and simulating the measurement setup in a raytracing simulation to retrieve information about the ARC from the measurements. The measurement concept has been confirmed and validated. First exemplary results are provided. The method will be further improved in future work and can contribute to the optimization of an AR coating on a small spherical lens used as SOE in a micro-CPV system.