This paper describes the main features of an optical instrument for the acquisition and the registration of 3D images. The system exploits the projection of structured light, specifically developed to perform the measurement of free-form surfaces in an accurate way and over extended fields of view. The acquisition of multiple views is performed by controlling mechanically the rotation of the object under measurement: the corresponding rototranslation matrices are then used to align the partial clouds of points. Special attention is given to the calibration of the optical head, to enhance the flexibility of the measurement. The system layout, the overall elaboration procedure, and a number of significant experimental results are herein presented.