Study on the Performance of Optical Lenses under High Fluxes of Solar Radiation

This work compares the performance of optical lenses made of silica glass or borosilicate glass (BK-7) when submitted to high-flux radiation emitted by a xenon arc lamp or provided by a high-concentration solar tower. Each irradiation test lasted for 60 min, with continuous monitoring of the radiation-flux incident on the lenses and the temperature generated in their vicinity. All silica glass lenses showed a good performance with both irradiation sources, xenon arc lamp and natural solar radiation, contrary to what was observed with the lenses made of borosilicate glass which fractured when irradiated with a xenon arc lamp. The negative behavior observed with the borosilicate lenses is attributed to the fact that the radiation spectrum of a xenon arc lamp contains certain wavelengths, in the near ultraviolet (UV) region, that are not present in the natural solar radiation spectrum at sea level.