Low-cost optoelectronic system for three-dimensional artwork texture measurement

A new optoelectronic system is proposed for three-dimensional (3D) texture measurement. It is based on a projection unit in which light, coming from a laser diode coupled to an optical fiber, impinges on a diffractive optical element (DOE) to produce sinusoidal fringes. If the projected fringe pattern is viewed at an angle different from the projection angle, the fringe profile is phase-modulated by the 3D object shape. The 3D map information is obtained with the aid of a fringe analyzer based on phase-shifting a synthetic moire pattern, fast Fourier transform (FFT), signal demodulation techniques and a robust and fast phase unwrapping performed by specially developed software. The proposed system is based on simple and low cost equipment; furthermore, it is suitable for in situ measurements by nonskilled operators. Some experimental examples illustrate its performance.