Pattern Projection with a Sinusoidal Phase Grating

Abstract

The present work focuses on a sinusoidal phase grating as a pattern projection element in a phase-shifting profilometric system. Usage of the phase grating for fringe pattern generation under coherent illumination proposes several advantages as technical simplicity, high efficiency, minimization of the phase-shifting error, large focal depth and independence of the fringe pattern spatial period on the wavelength. The work considers the frequency content of the projected fringes in the Fresnel diffraction zone and gives the results of test measurements of relative 3D coordinates by means of a pattern projection system with a phase grating that is interferometrically recorded on a holographic plate. Implementation of sinusoidal phase gratings in a four-wavelength profilometric system with parallel recording of the phase-shifted patterns by a multi-camera system for real-time measurements of 3D coordinates of objects and scenes is discussed.