Unfolded aplanats for high-concentration photovoltaics

The exigencies of high-concentration photovoltaics motivate optics that (1) obviate the need for optical bonds, (2) exhibit maximal optical tolerance, (3) are not damaged at off-axis orientation, and (4) allow convenient location of the solar cell and heat sink. We show that dual-mirror unfolded aplanats can satisfy all these criteria. Lens enhancement improves compactness and, with millimeter-scale cells, concentrator depth is only a few centimeters, amenable to precise large-volume fabrication. (C) 2008 Optical Society of America.