Characterizing surface defects in additively manufactured components using smart-phone imaging

Surface defects can be extremely detrimental to performance of fabricated components due to strain concentrations that are known to shorten life due to wear, fatigue, and corrosion. Unfortunately, surface defects are challenging to characterize due to their small size and require advanced equipment such as white-light interferometers. This is not a viable approach when high throughput is of the essence. The present work shows a novel methodology of characterizing surface defects. The method relies on optical imaging of components and characterizing gradients in surface velocities that result from topographical undulations. These gradients naturally arise due to foreshortening, i.e. parallax and can also be artificially introduced to amplify visibility of surface gradients by rigid body rotation. The present work attempts to calibrate these effects using scalable smart-phone imaging as well as advanced optical imaging. Applications on additively manufactured materials are shown. Analytically obtained process limitations are discussed.