1 NONIMAGING OPTICAL SYSTEMS AND THEIR USES
Nonimaging concentrators and illuminators have several actual and some potential applications, but it is best to explain the general concept of a nonimaging concentrator by highlighting one of its applications; its use of solar energy. The radiation power density received from the sun at the earth’s surface, often denoted by S, peaks at approximately 1kWm−2, depending on many factors. If we attempt to collect this power by absorbing it on a perfect blackbody, the equilibrium temperature T of the blackbody will be given by1
where σ is the Stefan Boltzmann constant, ...