Multifocal light concentrator for a device for the conversion of radiation, and in particular for the conversion of solar radiation into electrical, thermal or chemical energy

摘要

A light concentrator is described, for a device for the conversion of solar radiation into electrical, thermal or chemical energy, capable of conveying the radiation towards a surface of the conversion device (20'). The concentrator (10, 10', 10", 10''') comprises at least one portion of .Fresnel lens of rotational symmetry, one face (11) of which has a plurality of crests (12) disposed concentrically about a centre (C) so as to form a segmented transverse profile (13) of the portion of Fresnel lens. The profile (13) is formed in such a manner that the focal distance (F) of the Fresnel lens is variable in dependence on the radial distance (r lens ) from the centre (C) of the lens. The variation of the focal distance (F) is determined such that, when the Fresnel lens is illuminated by polychromatic radiation, the superposition of the distributions of irradiance, produced by the lens at the individual wavelengths constituting the spectrum of the incident radiation, generates a substantially uniform distribution of polychromatic irradiance on the conversion device (20').