Additive manufacturing apparatus and method

An additive manufacturing apparatus for building an object by layerwise consolidation of material, the apparatus comprising a build enclosure containing a build support for supporting the object and a powder bed during the build, a material source for forming layers of the powder bed, a radiation device for generating and directing radiation to selected locations on the powder bed and an acoustic sensing system arranged to detect acoustic signals generated in the build enclosure by acoustic signals induced by an interaction of a radiation beam with an upper working surface of the object or a working surface of the powder bed during the build.

An additive manufacturing apparatus comprising:—

• a radiation source for generating a radiation beam to create a melt pool at an exposed working surface of a powder bed to selectively fuse powder of the powder bed to form an object in a layer-by-layer manner,
• an acoustic sensor arranged to detect an acoustic wave generated in the object when the radiation source directs a radiation beam to a build surface of the object, and
• a signal processor arranged to determine a property of the object by analyzing the detected acoustic wave.