| CPC B22F 10/28 (2021.01) [B22F 10/36 (2021.01); B22F 12/43 (2021.01); B22F 12/46 (2021.01); B23K 15/002 (2013.01); B33Y 10/00 (2014.12); B33Y 30/00 (2014.12)] | 24 Claims |

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1. A method for an electron beam system for manufacturing a three-dimensional object by fusing successive layers of powder, said system having at least one lens for reshaping of said electron beam, an electron source and a powder bed, said method comprising the step: selectively blocking a selected cross section of said electron beam by providing a beam blocking part positioned between said at least one lens for reshaping of said electron beam and said powder bed and actively controlling said at least one lens for reshaping of said electron beam to control the amount of beam power blocked by said beam blocking part and thereby the electron beam power that reaches the powder bed, wherein, during said selectively blocking, interference between the selected cross section of said electron beam and the beam blocking part can turn off beam power to the powder bed.
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