Line-focusing holographic mirrors for solar ultraviolet energy concentration

We report on the design and the construction of a 1.3-m(2) UV selective solar concentrator intended for photocatalytic water detoxification processes. This concentrator was made by assembling 30 cm x 30 cm line-focusing holographic mirrors. Holograms with an 80% diffraction efficiency concentrate ~40% of the incident solar energy, which is effective for exciting an aqueous suspension of the TiO(2) photocatalyst, and transmit unnecessary longwave radiation. Major problems, such as the low sensitivity of the dichromated gelatin used for recording the holograms and wavelength dispersion, are discussed.