This paper presents the main features of an optical instrument for 3D vision, based on the projection of structure light. The envisaged application is the non contact, fast acquisition of points clouds both for dimensional and quality control, and for reverse engineering. The components of the system are a liquid crystal projector, projecting fringe patterns on a the target, and a video-camera for the acquisition of the patterns. The measurement technique developed to elaborate the patterns, and retrieve the depth information is based on the combination of the Gray Code and the Phase Shift methods. It yields an extended measuring range at high resolution, and allows the measurement of a wide typology of objects, characterized by shape discontinuities and by fine surface details. The digitization of large objects is carried out by acquiring multiple views and by aligning them into a global reference system. To this aim, suitable rototranslation matrices are computed and used to perform the transformation. From the extensive set of experiments carried out to evaluate the measurement performance, good linearity has been observed, and an overall variability of the measurement error of +/- 35 micrometers have been estimated in correspondence with each single view. The error due to the alignment of multiple views is within 0.1 mm.