8 OCT, as a light analog to ultrasound, offers wavelength-encoded depth information about a sample with 1- to 20 - μ m axial resolution. OCT is an optical imaging technique based on low coherence interferometry. Optical coherence tomography (OCT) has recently been proposed to fill this gap. 3 In fact, several techniques have been proposed and adopted for powder bed monitoring: infrared imaging has been used to monitor surface temperature variations that can contribute to part inadequacies, 4 and high-resolution visible wavelength imaging evaluates two-dimensional (2-D) errors in a layer-by-layer geometry both before 5 and after 6, 7 the sintering process.Īlthough these processes monitor each layer of the build, they do not offer subsurface information about the build.

Monitoring the powder bed throughout the build can provide metrics on the health of the process and the quality of the part. The melt pool cools to form the solidified part, and the excess powder is removed.Īs SLS parts begin to be incorporated into devices with heavy governmental regulation (e.g., medical, aerospace) and higher performance, there is a need for precise and accurate feedback to inform the process. A complex part can thus be constructed in a layer-wise manner.

1, 2 After a melt pool is formed for the current layer of the part, a new layer of powder is spread over the entire build area, and the process is repeated. SLS works by selectively sintering (melting) polymer powder beds layer by layer. Selective laser sintering (SLS) in particular is a promising technology for manufacturing parts that have been historically difficult to fabricate using classical machining techniques.

Additive manufacturing (AM) is a growing field with rapid industrial incorporation.

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