Patent ID: 7754135

Claim:
A method of making a three-dimensional object, comprising: forming a powdery layer; irradiating an optical beam on a predetermined portion of the powdery layer to form a sintered layer; forming a new powdery layer on a surface of the sintered layer; irradiating an optical beam on a predetermined portion of the new powdery layer to form a new sintered layer united with the underlying sintered layer; detecting, after the irradiating an optical beam on a predetermined portion of the powdery layer and the irradiating an optical beam on a predetermined portion of the new powdery layer, presence or absence of and a position of an abnormally sintered portion that has been produced on the surface of the sintered layer and is higher than a powdery layer to be subsequently formed, and subsequently removing, when the abnormally sintered portion is detected, only the abnormally sintered portion and a portion in a vicinity of the abnormally sintered portion that are higher than a height of such powdery layer to be subsequently formed; and repeating the forming a new powder layer, the irradiating an optical beam on a predetermined portion of the new powdery layer, the detecting, and the removing, to form a plurality of sintered layers.