Multi-chip and large size LEDs dominate the lighting market in developed countries these days. Nevertheless, a general optical design method to create prescribed intensity patterns for this type of extended sources does not exist. We present a design strategy in which the source and the target pattern are described by means of "edge wavefronts" of the system. The goal is then finding an optic coupling these wavefronts, which in the current work is a monolithic part comprising up to three freeform surfaces calculated with the simultaneous multiple surface (SMS) method. The resulting optic fully controls, for the first time, three freeform wavefronts, one more than previous SMS designs. Simulations with extended LEDs demonstrate improved intensity tailoring capabilities, confirming the effectiveness of our method and suggesting that enhanced performance features can be achieved by controlling additional wavefronts.
Abstract. The so-called CCS 4 FK is an ultra-flat photovoltaic system of high concentration and high efficiency, with potential to convert, ideally, the equivalent of a 45% of direct solar radiation into electricity by optimizing the usage of sun spectrum and by collecting part of the diffuse radiation, as a flat plate does. LPI has recently finished a design based on this concept and is now developing a prototype based on this technology, thanks to the support of FUNDACION REPSOL-Fondo de Emprendedores, which promotes entrepreneur projects in different areas linked to energy. This works shows some details of the actual design and preliminary potential performance expected, according to accurate spectral simulations.
We present a compact freeform optic, called "Freeform Shell-Mixer", which, when placed on top of a multicolor light source (particularly, a multi-chip LED), turns it into a virtual source in which colors are uniformly mixed. The optic, compatible with injection molding, makes use of étendue-conserving Köhler integration to provide homogeneous mixing of light. Its minimal size (just 2x larger than the source) makes the concept compatible with many luminaries, as ray tracing models show. Simulations indicate that the Freeform Shell-Mixer can reach efficiencies above 95% and both the size of the virtual source and its emission pattern are very similar to the ones of the original source, so the correct performance of the luminaire is secured.
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