Surface inspection via projection interferometry

Projection fringe interferometry provides a useful technique for nondestructive surface analysis. Two beam interferometric fringes were projected onto a block of aluminum whose surface had various types of grooves cut into it. The fringes were digitized and analyzed via an automatic fringe tracking algorithm. Three-dimensional topographical maps of the surface's microstructure are presented together with a statistical analysis of surface parameters including average roughness, height distributions, and the autocorrelation function.