Surface reconstruction in three-dimensional space using structured illumination

The reconstruction of liquid–air interfaces in three-dimensional (3D) space is of great value for many practical and scientific applications, from manufacturing automation to naval hydrodynamics and much more. This study presents a new, nonintrusive experimental diagnostic for surface reconstruction in the 3D space based on ray tracing and structured illumination. The 3D topography of an air–water interface is obtained based on a robust ray tracing algorithm by imaging, from the gas phase, a vertical 2D laser-induced fluorescent grid generated by Talbot-effect structured illumination. The images of the optically deformed grid are related to the instantaneous surface profiles. The vertical orientation of the structured illumination plane provides boundary conditions for the surface reconstruction and minimizes restrictions of existing schemes. The experimental technique and the profilometry algorithm are presented in detail, and samples of reconstructed surfaces from a droplet impact are discussed. The surface reconstruction performance is assessed by analyzing samples of known topography and estimating residuals for the local surface elevation and slope.