Consideration of coordinated solar tracking of an array of compact solar-pumped lasers combined with photovoltaic cells for electricity generation

A monochromatic laser light with a photon energy just above the band edge of photovoltaic cells can be converted into electricity with minimal thermal loss. To attain efficient conversion of sunlight to laser light, a coordinated solar tracking system for an array of originally designed compact solar-pumped lasers of 50mm aperture diameter is being constructed. As for the feasibility of this system, a prototype with a holding capacity of 25 compact solar-pumped lasers has been fabricated. The primary requisite of this system is that the angular accuracy of tracking should be below 1 mrad for all 25 compact solar-pumped lasers to sustain their continuous lasing. To realize this, imperative challenges have been elucidated including thermal expansion under sunlight. A prototype fabricated with its main frame made of Super Invar alloy was found to fulfill the requisite by measurement using a three-dimensional coordinate measuring machine. (C) 2015 The Japan Society of Applied Physics