Patent ID: 8546717

Claim:
An apparatus for layer manufacturing a three-dimensional work piece, comprising: a) a housing defining a chamber capable of evacuation and within which a metallic work piece is formed layer by layer from a plurality of successively deposited molten pool deposits, the housing enclosing: a. an electron beam gun that melts a metal feed material; b. a table upon which the metallic work piece is formed, the table and the electron beam gun being adjustably spaced relative to each other so that as the metallic work piece is formed layer by layer from the plurality of successively deposited molten pool deposits, the spacing incrementally increases; c. an optical assembly including: i. a first enclosure, ii. optics for reflecting light housed in the first enclosure, iii. an aperture in a wall of the first enclosure for allowing access, into the first enclosure, of light emitted by one or more molten pool deposits so that the light reaches the optics, and iv. a vapor protection device that substantially avoids build-up of metal vapor on the optics during operating of the apparatus; d. an imaging device including: i. a detector array, ii. thermally regulated electronic componentry, and iii. a second enclosure that substantially encloses the detector array and the thermally regulated electronic componentry, and also includes an opening through which light that is emitted by one or more molten pool deposits and is reflected from the optical assembly can communicate with the detector array; and e. a frame that carries the enclosures of the optical assembly and the imaging device in spaced apart relation from each other so that the aperture of first enclosure is substantially overhead of the molten pool deposit, and the first and second enclosures are separated from each other; b) a closed loop control device configured to automatically adjust one or more processing parameters of the apparatus in response to data obtained from the imaging device.