US Patent 8075814 Device for layerwise manufacturing of a three-dimensional object

An apparatus for layerwise manufacturing of a three-dimensional object by solidification of a material, which can be solidified via electromagnetic radiation, includes a source for the electromagnetic radiation, a building space for manufacturing the three-dimensional object, a coupling window, for transmitting the electromagnetic radiation into the building space and a heating element for heating the coupling window. By the heating element the temperature of the lens is increased during the building of the three-dimensional object. By the increased temperature the accumulation of contamination on the coupling window is prevented.