Planar micro-optic solar concentrator based on micro-lenses array and micro-prisms as couplers

In this paper we are presenting an optimized planar micro-optic solar concentrator consisting of a two-dimensional array of micro-lenses for collecting and focusing the optical radiation, and an array of coupling prisms for directing light into a planar waveguide. The optical efficiency of the proposed planar optical concentrator based on total internal reflection (TIR) conditions was modelled and simulated using Ray Optics/COMSOL Multiphysics software considering material parameters, geometry of micro-optic elements (micro-lenses, dihedral apex angle of the micro-prisms, layers thickness) and the alignment between collecting and coupling facets. Micro-lenses and micro-prisms (micro-mirrors) arrays were fabricated by molding technique in silicon molds and replication in polymeric materials using OrmoClear30 elastomer (n=1.56, UV curing). The optical efficiency of the fabricated micro-optic concentrator of 25x25 mm2 area was in the range 60-70%, values which are in agreement with those obtained by simulation.