Patent ID: 7952017
Filing Date: 2011-05-31
Classification: F24S,G02B,H01L,Y02E

Abstract:
1. A conversion device for the conversion of radiation into electrical, thermal or chemical energy, comprising: a receiving surface; and a light concentrator disposed at a predetermined distance from said receiving surface and capable of conveying said radiation towards said receiving surface, said light concentrator including: at least one portion of circular Fresnel lens having rotational symmetry about a centre of symmetry, and having a central optical axis, said central optical axis being perpendicular to said portion of circular Fresnel lens, wherein one face of said portion of circular Fresnel lens has a plurality of annular crests disposed concentrically about the centre of symmetry so as to form a segmented transverse profile of said portion of Fresnel lens, and wherein said segmented profile is formed in such a manner that rays incident parallel to the optical axis are focused, at different focal distances, said focal distances being variable in dependence on the radial distance of the rays from the centre of symmetry of the Fresnel lens, the variation of said focal distances being determined such that said focal distances are equal to a maximum value at the center of symmetry of said portion of circular Fresnel lens, decreasing progressively until they reach a minimum value at the edge of said portion of circular Fresnel lens, in such a way that, when said portion of circular Fresnel lens is illuminated by polychromatic radiation, the superposition of the distributions of irradiance, produced by said portion of circular Fresnel lens at the individual wavelengths constituting the spectrum of the incident radiation, generates a substantially uniform distribution of polychromatic irradiance on said receiving surface of the conversion device.