Simple smartphone-based artworks diagnostics by Moiré method and a diffractive optical element

Abstract

The moiré method is a well-known tool in NDT; it is based on the principle of superposition of two sets of lines or gratings, which creates a moiré pattern that can reveal surface deformations caused by underlying defects or damage. In this paper, we propose a simple artwork diagnostic using the moiré method and a smartphone. The technique is based on coupling the acquisition of fringe patterns by the smartphone camera to an effective fringe generator. The fringe generator consists of a diffractive optical element (DOE) illuminated by a laser diode; this optical device proved to be very effective thanks to its ability to produce in a simple way grid patterns of different spatial frequencies. The smartphone camera is used to capture the grid patterns and to store them in the cloud. We demonstrate the proposed approach by giving some preliminary experimental results.