Surface roughness measurement of additive manufactured samples using angular speckle correlation

Abstract

A speckle pattern is a direct fingerprint of surface height variation on the sample. In this paper, angular speckle correlation technique is applied to estimate surface roughness Ra of an additive manufactured sample with different surface roughness Ra values varying from 5μm to 20μm. Feasibility study is conducted to evaluate the correct incidence and the change in incidence angle for angular speckle correlation. Speckle correlation is computed from two speckle images that are recorded at two different incidence angles on the rough surface and surface roughness information is gleaned. Test results in terms of surface roughness measurement from standard calibration plate and additive layer manufactured samples are presented.