Patent ID: 8181642

Claim:
A light absorbing device which comprises an at least partly transparent outer material layer, a space through which a gaseous medium is adapted to be circulated and heated by light radiation passing through the outer material layer, a radiation absorbing material layer which is located in connection to said space, and an element which is adapted to divide the space in at least a first subspace, which comprises a first opening, and a second subspace, which comprises a second opening, wherein the gaseous medium is adapted to flow along a path having an extension from the opening in the first subspace to the opening in the second subspace and that said path has an extension such that the gaseous medium only has possibility to be guided from the first subspace to the second subspace via a passage which is located at a lower level in the space than the levels of the first opening and the second opening, and wherein said element has an extension between an upper end abutting an upper edge surface of the space and a lower end which defines a lower level for an upper portion of the first subspace and an upper portion of the second subspace, wherein the device comprises flow resistance reducing means adapted to reduce the flow resistance for the gaseous medium when it is guided through said path and that said means comprises that the elongated element has an inclination such that said path provides a successively increased width and thus an increased cross section area in the flow direction of the medium in the upper portion of the first subspace and/or in the upper portion of the second subspace.